WO2006057394A1 - Method and device for forming solder bump - Google Patents

Method and device for forming solder bump Download PDF

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Publication number
WO2006057394A1
WO2006057394A1 PCT/JP2005/021833 JP2005021833W WO2006057394A1 WO 2006057394 A1 WO2006057394 A1 WO 2006057394A1 JP 2005021833 W JP2005021833 W JP 2005021833W WO 2006057394 A1 WO2006057394 A1 WO 2006057394A1
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WO
WIPO (PCT)
Prior art keywords
solder
fine particles
forming
inert gas
solder fine
Prior art date
Application number
PCT/JP2005/021833
Other languages
French (fr)
Japanese (ja)
Inventor
Junichi Onozaki
Isao Sakamoto
Masaru Shirai
Original Assignee
Tamura Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tamura Corporation filed Critical Tamura Corporation
Priority to JP2006547921A priority Critical patent/JPWO2006057394A1/en
Publication of WO2006057394A1 publication Critical patent/WO2006057394A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
    • H01L21/4814—Conductive parts
    • H01L21/4846—Leads on or in insulating or insulated substrates, e.g. metallisation
    • H01L21/4853—Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps
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    • H01L24/10—Bump connectors ; Manufacturing methods related thereto
    • H01L24/11—Manufacturing methods
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    • H01L24/10—Bump connectors ; Manufacturing methods related thereto
    • H01L24/12—Structure, shape, material or disposition of the bump connectors prior to the connecting process
    • H01L24/13—Structure, shape, material or disposition of the bump connectors prior to the connecting process of an individual bump connector
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    • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
    • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
    • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
    • H05K3/3457—Solder materials or compositions; Methods of application thereof
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Definitions

  • the present invention relates to the formation of solder bumps that are used when FC (flip chip) or BGA (ball grid array) are manufactured by forming hemispherical solder bumps on a semiconductor substrate or interposer substrate.
  • FC flip chip
  • BGA ball grid array
  • FC and BGA with hemispherical solder bumps are used as semiconductor devices to achieve this high-density mounting!
  • solder method As a method for forming solder bumps on the nod electrode, a method in which the pad electrode is brought into contact with the molten solder (molten solder method), and a method in which a solder paste is screen printed on the pad electrode and reflowed (screen printing method)
  • molten solder method a method in which the pad electrode is brought into contact with the molten solder
  • screen printing method a method in which a solder paste is screen printed on the pad electrode and reflowed
  • solder ball method a method of placing a solder ball on the solder electrode and reflowing
  • meh method a method of soldering the solder electrode
  • a solder bump forming method described in Patent Document 1 is known.
  • FIG. 10 is a schematic cross-sectional view showing the solder forming method described in Patent Document 1. Hereinafter, description will be given based on this drawing.
  • a wafer 82 having a copper electrode 81 on the surface thereof is immersed in an inert solvent 80 heated to a melting point or higher of the solder so that the surface is on the bottom.
  • solder particles 84 made of molten solder 83 are sprayed upward in an inert solvent 80 to bring the solder particles 84 into contact with the wafer 82 and solder bumps (not shown) are formed on the copper electrodes 81. Form. This will be described in more detail.
  • the temperature of the molten solder 83 and the inert solvent 80 in the heating tank 85 is controlled to a temperature slightly higher than the melting point of the solder, for example, 200 ° C.
  • the molten solder 83 in the heating tank 85 is sucked into the solder fine particle device 87 from the solder introduction tube 86.
  • the solder fine particle device 87 sucks the inert solvent 80 having the same temperature as the molten solder 83 from the inert solvent introduction pipe 88, and These two liquids are mixed and stirred to crush the molten solder 83 into particles.
  • the inert solvent 80 containing the solder particles 84 is fed from the mixed solution outlet pipe 89 to the ejection device 90 and is ejected upward from the nozzle 91.
  • solder particles 84 in the inert solvent 80 are covered with the inert solvent 80, they do not come into contact with the outside air. For this reason, the surface of the solder particle 84 keeps the metal surface and is in an active state. Then, when the solder particles 84 in the inert solvent 80 come into contact with the copper electrode 81 of the wafer 82 immersed in the inert solvent 80, a solder alloy layer is formed with the copper electrode 81 and adheres to the surface of the copper electrode 81. By doing so, the surface of the copper electrode 81 is covered with a molten solder film (not shown). Subsequently, since the solder particles 84 are likely to be adsorbed to the solder film, the solder particles 84 in this portion adhere to the solder film one after another.
  • solder particles 84 that have not adhered to the copper electrode 81 gradually fall due to the difference in specific gravity, and accumulate on the bottom of the heating tank 85.
  • solder bumps (not shown) can be selectively applied only to the surface of the copper electrode 81. ) Can be formed.
  • Patent Document 1 Japanese Patent Publication No. 7-114205 (Fig. 1 etc.)
  • the molten solder method has a feature that it is suitable for fine pitch of the nod electrode, it has a drawback that the solder amount of the solder bump is small and its variation is large.
  • the screen printing method has the feature that solder bumps can be easily formed in one batch, clogging and uneven solder amount are likely to occur when a fine pitch mask is used.
  • the solder ball method has a drawback in that the number of solder balls used in one semiconductor device is extremely large as a recent trend, and the manufacturing cost is high because the force and the size of the solder balls are extremely small.
  • the plating method has the disadvantage that there is no suitable plating solution for lead-free solder, which has become widespread in recent years.
  • solder fine particles are difficult to adhere to a copper electrode! / That is, solder wettability is poor, and thus it has been difficult to put it to practical use.
  • the present inventor has developed the following technique. First, solder fine particles, a liquid having flux action, and a substrate having electrodes on the surface are prepared. Then, the liquid is heated above the melting point of the solder, the substrate is positioned in the liquid with the surface facing up, and solder fine particles are sprayed into the liquid and dropped toward the electrodes on the substrate. As a result, solder bumps are formed on the pad electrodes. As a result, the conventional problems could be solved, and finer pitch solder bumps were achieved.
  • solder fine particles are large, solder bridges are likely to occur between the electrodes.
  • solder fine particles the lower the falling speed of the solder fine particles in the liquid, and the longer it takes to form the solder bumps.
  • the reason will be described below.
  • the solder fine particles shall fall in the liquid while receiving a viscous resistance proportional to the velocity.
  • the mass of the solder fine particles is m
  • the gravitational acceleration is g
  • the viscosity coefficient is k
  • the z-axis is taken vertically upward
  • an object of the present invention is to provide a solder bump forming method capable of obtaining a fine pitch of the nod electrode, obtaining a solder bump with a large amount of solder and little variation, and capable of forming the solder bump in a short time. And providing an apparatus.
  • a method for forming a solder bump according to the present invention includes a substrate having a pad electrode on a surface thereof.
  • the solder bumps are placed on the pad electrode by spraying (sending out) solder fine particles, which are positioned in an inert gas so that the surface is on top, and have a molten solder force, into the inert gas and dropping the solder fine particles onto the substrate. Is formed.
  • a solder bump is formed on a node electrode by placing the substrate in a dispersion system (aerosol) composed of a dispersion medium of an inert gas and a dispersion phase of liquid solder fine particles. This technology is also included.
  • the “substrate” here includes a semiconductor wafer, a wiring board, and the like.
  • the “solder bump” is not limited to a hemispherical shape or a protrusion shape, but includes a film shape.
  • the inert gas is mainly composed of nitrogen or argon, it may be a gas containing a certain amount of oxygen so long as it is substantially inert without adversely affecting the soldering.
  • the substrate In the inert gas, the substrate is held with the nod electrode side facing up. At this time, when the solder fine particles are sprayed into the inert gas on the substrate, the solder fine particles spontaneously drop due to gravity and reach the substrate. The solder fine particles that have reached the pad electrode of the substrate stay there due to gravity, and after a certain period of time, spreads on the surface of the pad electrode to form a solder film. Subsequently, the solder fine particles that have reached the solder film stay there due to gravity, and in the same way, after a certain amount of time has passed, it spreads and thickens the solder film. This is repeated, and the solder film grows to become solder bumps.
  • solder wetting time In order for the solder to get wet, the aforementioned “certain time” (hereinafter referred to as “solder wetting time”) is necessary.
  • solder wetting time since the solder fine particles are sprayed and brought into contact with the downward-facing pad electrode in the inert liquid, it takes only a moment for the solder fine particles to contact the pad electrode. The wettability is considered bad.
  • solder fine particles even if the solder fine particles come into contact with each other during the fall in the inert gas, the present inventor cannot easily prepare the condition that these fine particles are united into large solder fine particles. It has been found that there is no problem in sending out toward the substrate through the inert gas. Therefore, in the present invention, a solder bridge or the like does not occur even for a fine pitch pad electrode. Furthermore, the solder amount of the solder bump can be easily adjusted by changing the supply amount of the solder fine particles. Since the solder fine particles are extremely small compared to the node electrode, a large amount of solder fine particles are supplied, so that the solder fine particles are uniformly dispersed in the inert gas.
  • solder fine particles are foggy. Since it is extremely fine, it is suitable for making fine pitches of pad electrodes.
  • the soldering force the falling speed of the solder fine particles is large because the solder fine particles fall in the gas, not in the liquid, and the viscosity coefficient k in the above-mentioned formula ⁇ 3 >> becomes extremely small. That is, even if the solder fine particles are small, they fall quickly, so the time required for forming the solder bumps is short.
  • solder bumps are formed on the pad electrodes.
  • solder fine particles are sprayed toward the pad electrode, the surface of the substrate does not necessarily have to be in the inert gas, and may be laterally, downwardly or diagonally! / ⁇ . Solder particles move erratically due to Brownian motion due to their mist, ie, very fine. Therefore, when the solder fine particles are sprayed toward the pad electrode, the solder fine particles float around the pad electrode, so that the solder fine particles can remain on the pad electrode for the solder wet time or longer. In this case, solder fine particles are sprayed at the initial velocity V in the + z direction.
  • the solder bump forming method according to the present invention is such that when the substrate is positioned in an inert gas, the surface of the substrate is positioned downward. In this case, unnecessary solder fine particles that have the same force as the solder bumps can easily drop on the substrate, facilitating cleaning in subsequent processes.
  • the solder bump forming method according to the present invention is such that when the solder fine particles are sprayed, the flux is also sprayed.
  • the spraying of solder fine particles is, for example, before spraying the solder fine particles, at the same time as spraying, or immediately after spraying.
  • the solder wettability in an inert gas is further improved by the action of the flux.
  • flux includes rosin, surfactant, and other substances that have the effect of removing the acid film on the solder surface.
  • the solder bump forming method according to the present invention is such that hydrogen gas is mixed in an inert gas. Since hydrogen gas reduces and removes the oxide film on the surface of the pad electrode and the surface of the solder fine particles, the solder wettability in an inert gas is further improved.
  • the solder bump forming method according to the present invention is such that the diameter of the solder fine particles is smaller than the shortest distance between the peripheral ends of adjacent pad electrodes. In this case, the solder fine particles that have reached each of the two adjacent pad electrodes do not come into contact with each other, so that they do not combine to form a solder bridge.
  • the solder bump forming method according to the present invention is such that the inert gas is heated to a temperature higher than the melting point of the solder.
  • the solder fine particles are in an inert gas having a melting point higher than the melting point of the solder, the solder fine particles are surely kept in a liquid state. In other words, the solder fine particles do not solidify by any chance, so the solder wettability is good.
  • solder bump forming method according to the present invention is such that the solder fine particle force is sprayed as a solid and melted in an inert gas. Solid solder fine particles will not be combined in that state! So, handle! /, Easy.
  • the solder bump forming apparatus includes a gas tank and a solder sprayer.
  • the gas tank contains an inert gas and a substrate that has a pad electrode on its surface and is positioned in the inert gas so that the surface is on top.
  • the solder sprayer sprays solder fine particles, such as molten solder particles, into an inert gas and drops the solder fine particles onto the substrate.
  • the substrate In an inert gas in the gas tank, the substrate is held with the pad electrode side facing up. At this time, when the solder fine particles are sprayed into the inert gas on the substrate such as the solder sprayer, the solder fine particles naturally fall by gravity and reach the substrate. Hereinafter, the same effect as the above forming method is exhibited.
  • a solder bump forming apparatus includes a gas tank and a solder sprayer.
  • the gas tank accommodates an inert gas heated to a temperature equal to or higher than the melting point of the solder and a substrate that has a nod electrode on its surface and is positioned in the inert gas.
  • the solder sprayer sprays solder fine particles with molten solder force toward the pad electrode in an inert gas. The same effect as the above forming method is achieved.
  • the solder bump forming apparatus according to the present invention is such that the substrate is positioned in an inert gas so that the surface of the substrate faces down. It has the same effect as the above forming method.
  • the solder bump forming apparatus according to the present invention is such that when the solder sprayer sprays solder fine particles toward the pad electrode, the flux is also sprayed. It has the same effect as the above forming method.
  • hydrogen gas is mixed in an inert gas.
  • the solder bump forming apparatus according to the present invention is such that the diameter of the solder fine particles is smaller than the shortest distance between the peripheral edges of adjacent pad electrodes. The same effect as the above forming method is achieved.
  • the solder bump forming apparatus according to the present invention is such that the inert gas is heated above the melting point of the solder. The same effect as the above forming method is achieved.
  • the solder bump forming apparatus according to the present invention is such that the solder fine particle force is sprayed as a solid and melts in an inert gas. The same effect as the above forming method is achieved.
  • the method for forming a solder bump according to the present invention uses solder fine particles having a solid solder force instead of solder fine particles having a molten solder force, and coats the solder fine particles with a liquid having a flux action. It sprays fine particles.
  • the method for forming a solder bump according to the present invention uses a solder fine particle having a solid solder force instead of a solder fine particle having a melted solder force, and coats the solder fine particle with an organic film, and further a liquid having a flux action. In this state, solder fine particles are coated and solder fine particles are sprayed.
  • the solder bump forming method according to the present invention heats the solder fine particles dropped on the substrate to the melting point or higher and evaporates the liquid by this heating. As the liquid evaporates, the solder particles gradually approach and unite to form solder bumps. For this reason, unnecessary coalescence of solder fine particles is unlikely to occur, and the occurrence of solder bridges is suppressed.
  • the solder bump forming method according to the present invention is inactive when the solder fine particles are sprayed.
  • the gas is depressurized below atmospheric pressure.
  • the viscosity coefficient k decreases, so that the falling speed of the solder fine particles further increases. For this reason, the time required for forming the solder bumps is further reduced.
  • the sprayer is coated with a liquid having a flux action and the solder fine particles having a solid solder force. To spray, t.
  • the sprayer is coated with a liquid having a flux action and is coated with an organic film, instead of the solder fine particles made of molten solder powder. It sprays solder fine particles that also have soldering power.
  • the solder bump forming apparatus further includes heating means for heating the solder fine particles dropped on the substrate to the melting point or higher and evaporating the liquid by this heating. The same effect as the above forming method is achieved.
  • the solder bump forming apparatus further includes a depressurizing means for depressurizing the inert gas to atmospheric pressure or lower when spraying the solder fine particles. Has the same effect as the above formation method.
  • the solder fine particles are sprayed in an inert gas, and the solder fine particles are dropped on the substrate to form the solder bumps on the pad electrodes.
  • the solder wettability can be improved because the solder fine particles can be kept there by the gravitational force over the solder wetting time.
  • solder fine particles come into contact with each other in an inert gas, there are few things that coalesce into large solder fine particles, and the solder fine particles are mist-like, that is, extremely fine. Solder bridges etc. at pad electrodes can be prevented.
  • the amount of solder bumps can be easily adjusted by changing the amount of solder fine particles supplied. Since the solder fine particles are extremely small as compared with the pad electrode, they are supplied in a large amount and uniformly dispersed in the inert gas, so that the solder amount of the solder bumps can be made uniform. Accordingly, it is possible to obtain a solder bump with a small amount of solder and a small amount of variation while achieving a fine pitch of the electrode / electrode. [0048] Moreover, the time required for the solder fine particles to reach the pad electrode is extremely short compared to that in the liquid! As a matter of fact, even if the solder fine particles are small, they reach the pad electrode immediately, which is necessary for forming the solder bumps. You can save time. This effect can greatly contribute to the reduction of solder fine particles accompanying further fine pitch.
  • the substrate can be placed in any direction in the inert gas by spraying the solder fine particles toward the pad electrode. Therefore, the degree of freedom of work can be improved.
  • solder fine particles that have the same strength as solder bumps are sprayed from the lower side with the pad electrode side of the substrate facing down. Since it is difficult to adhere to the substrate, it is possible to facilitate cleaning in a later process.
  • solder bump forming method and apparatus of the present invention since the flats are also sprayed in the inert gas, the solder wettability in the inert gas can be further improved.
  • solder bump forming method and apparatus of the present invention since hydrogen gas is included in the inert gas, the solder wettability in the inert gas can be further improved.
  • the diameter of the solder fine particles is made smaller than the shortest distance between the peripheral ends of adjacent pad electrodes, so that Therefore, it is possible to prevent the solder bridges from being generated more reliably.
  • the inert gas is heated to the melting point of the solder or higher, so that the solder fine particles are reliably kept in a liquid state in the inert gas. Therefore, solderability can be improved reliably.
  • the solder fine particles are sprayed in a solid state and melted in an inert gas, so that it can be stored in the state of solid solder fine particles. Therefore, the handleability can be improved.
  • solder bumps According to the method and apparatus for forming solder bumps according to the present invention, by spraying solid solder fine particles coated with a liquid having a flux action, the same degree as solder bump formation in the liquid. Despite the quality of Since the time to reach the pole is much shorter than in liquid, the time required to form solder bumps can be greatly reduced.
  • the organic film and the liquid are used by spraying solid solder fine particles coated with the organic film and a liquid having a flux action.
  • the time required for solder bump formation can be greatly reduced because the time for solder fine particles to reach the pad electrode is much shorter than in liquid.
  • solder fine particles dropped on the substrate are heated to the melting point or higher, and the liquid is evaporated by this heating. As the solder fine particles gradually approach and unite with each other, the occurrence of solder bridges can be suppressed.
  • the falling velocity of the solder fine particles can be further increased by reducing the inert gas to atmospheric pressure or lower. Therefore, the time required for forming the solder bumps can be further shortened.
  • FIG. 1 is a schematic configuration diagram showing a first embodiment of a solder bump forming method and apparatus according to the present invention, and the process proceeds in the order of FIG. 1 [1] to FIG. 1 [3].
  • description will be made based on this drawing. Since there is no appropriate symbol for indicating gas, in Fig. 1 and Fig. 2, the symbol of liquid is used to indicate inert gas.
  • the forming apparatus 10 includes a gas tank 11 and a solder sprayer 12.
  • the gas tank 11 accommodates an inert gas 13 heated to the melting point of the solder or higher and a substrate 20 positioned in the inert gas 13 so that the surface 21 faces upward.
  • the solder sprayer 12 is provided with a blow pipe 16 for spraying the solder fine particles 14 having a molten solder force into the inert gas 13 and evenly dropping the solder fine particles 14 onto the substrate 20.
  • Solder is, for example, Sn-Pb (melting point 183 ° C), Sn-Ag-Cu (melting point 218 ° C), Sn-Ag (melting point 221 ° C), Sn-Cu (melting point 227 ° C) Etc.
  • the inert gas 13 can be anything as long as it does not react with the solder, for example, nitrogen gas. Good. Further, the inert gas 13 may be mixed with hydrogen gas.
  • the temperature of the inert gas 13 is not necessarily higher than the melting point of the solder as long as the solder fine particles 14 can be kept in a liquid state.
  • the inert gas 13 need not be 100%, but may contain a small amount of oxygen without adversely affecting the soldering.
  • the gas tank 11 is a container made of, for example, stainless steel or heat-resistant resin, and an electric heater (not shown) or a cooling device for keeping the inert gas 13 at or above the melting point of the solder (for example, a melting point + 50 ° C). Water rejection piping etc. are installed.
  • a mounting table 17 for positioning the substrate 20 in the inert gas 13 is provided in the gas tank 11.
  • the gas tank 11 is provided with an introduction pipe 111 for introducing the inert gas 13 into the gas tank 11 and a discharge pipe 112 for discharging the inert gas 13 from the gas tank 11.
  • the mounting table 17 is maintained at a temperature equal to or higher than the melting point of the solder, like the inert gas 13.
  • the solder sprayer 12 forms solder fine particles 14 by atomizing molten solder in an inert gas 13 using, for example, a spraying principle or an ultrasonic vibrator.
  • a pipe for introducing the solder fine particles 14 (molten solder) sinking to the bottom of the gas tank 11 and the inert gas 13 in the gas tank 11 may be provided between the gas tank 11.
  • the solder sprayer 12 may be configured to spray the flux, or a separate flux sprayer may be provided.
  • the blow-out pipe 16 has a large number of blow-out openings (not shown) up to the tip, and the solder fine particles 14 are evenly dropped into the inert gas 13 from the blow-out openings. Thereby, the solder fine particles 14 are sent out from the solder sprayer 12 and fall into the inert gas 13 in the gas tank 11 from the blowing pipe 16.
  • the solder fine particles 14 may be mixed with an inert gas and sent out from the blowing pipe 16.
  • FIG. 2 is a partially enlarged cross-sectional view of FIG. 1, and FIGS. 2 [1] to 2 [3] correspond to FIGS. 1 [1] to 1 [3], respectively.
  • FIG. 2 is a partially enlarged cross-sectional view of FIG. 1, and FIGS. 2 [1] to 2 [3] correspond to FIGS. 1 [1] to 1 [3], respectively.
  • description will be given based on these drawings. However, the same parts as those in FIG. In FIG. 2, the up-down direction is shown larger than the left-right direction.
  • the substrate 20 used in the present embodiment will be described.
  • the substrate 20 is a silicon wafer.
  • a pad electrode 22 is formed on the surface 21 of the substrate 20.
  • Solder bumps 23 are formed on the pad electrodes 22 by the forming method of the present embodiment.
  • Board 20 is solder The bumps 23 are electrically and mechanically connected to other semiconductor chips and wiring boards.
  • the pad electrode 22 has a circular shape, for example, and a diameter c of, for example, 40 m.
  • the distance d between the centers of the adjacent pad electrodes 22 is, for example, 80 m.
  • the diameter b of the solder fine particles 14 is, for example, 1 to 15 ⁇ m.
  • the pad electrode 22 includes an aluminum electrode 24 formed on the substrate 20, a nickel layer 25 formed on the aluminum electrode 24, and a gold layer 26 formed on the nickel layer 25.
  • -The Keckenore layer 25 and the gold layer 26 are UBM (under barrier metal or under bump metallurgy) layers. Portions other than the pad electrode 22 on the substrate 20 are covered with a protective film 27.
  • the aluminum electrode 24 is formed on the substrate 20, and the protective film 27 is formed on the portion other than the aluminum electrode 24 by polyimide resin. These are formed using, for example, a photolithography technique and an etching technique. Subsequently, after the surface of the aluminum electrode 24 is subjected to a zincate treatment, a nickel layer 25 and a gold layer 26 are formed on the aluminum electrode 24 using an electroless plating method. The reason for providing this UBM layer is to provide solder wettability to the aluminum electrode 24.
  • the substrate 20 is positioned in the inert gas 13 in the gas tank 11 so that the surface 21 faces upward.
  • a pad electrode 22 is formed on the surface 21 of the substrate 20.
  • the inert gas 13 is heated above the melting point of the solder. At this time, apply flux to the surface of the pad electrode 22!
  • the inert gas 13 containing the solder fine particles 14 is sent from the solder sprayer 12 to the blowing pipe 16, and the solder fine particles 14 are also fed into the blowing pipe 16 by force. Drop onto substrate 20 in inert gas 13.
  • the flux is sprayed together with the solder fine particles 14, before spraying the solder fine particles 14, or immediately after the solder fine particles 14 are sprayed.
  • hydrogen gas may be mixed in the inert gas 13.
  • the solder fine particles 14 fall in the gas instead of in the liquid, so that the viscosity coefficient k in the above-mentioned equation ⁇ 3 >> becomes extremely small.
  • the falling speed of the solder fine particles 14 is large. That is, even if the solder fine particles 14 are small, they quickly fall and reach the substrate 20, so that the time required for forming the solder bumps 23 is short.
  • the substrate 20 is held with the pad electrode 22 side facing up.
  • solder fine particles 14 when the solder fine particles 14 are sprayed into the inert gas 13 on the substrate 20, the solder fine particles 14 spontaneously drop by gravity and reach the substrate 20.
  • the plurality of solder fine particles 14 that have reached the pad electrode 22 of the substrate 20 stay there due to gravity, and the surface oxide film is removed by the action of the flux.
  • a solder film 23 ′ is formed on the surface of the nod electrode 22.
  • solder film 23 'grows into solder bumps 23 (Fig. 1 [3] and Fig. 2 [3]). Thereafter, unnecessary solder fine particles 14 (FIG. 2 [3]) having a sufficient force on the solder bump 23 are also removed by cleaning or the like.
  • the solder wetting time is a time for which the solder fine particles 14 are in contact with the pad electrode 22 or the solder film 23 'and is a time necessary for the solder to get wet (for example, several seconds to several tens of seconds).
  • the solder fine particles 14 fall and reach the pad electrode 22 or the solder coating 23 ', the solder fine particles 14 remain there due to the action of gravity. Therefore, the solder fine particles 14 and the pad electrode 22 or the solder film 23 ′ are in contact with each other until the solder wetting time elapses. Therefore, the solder wettability is good.
  • the present inventor has also found that even when the solder fine particles 14 come into contact with each other during the fall in the inert gas 13, there are few that combine to become large solder fine particles. Therefore, no solder bridge or the like is generated on the fine pitch pad electrode 22.
  • the diameter b of the solder fine particles 14 is preferably smaller than the shortest distance a between the peripheral ends of the adjacent pad electrodes 22. In this case, the solder fine particles 14 that have reached the two adjacent pad electrodes 22 do not come into contact with each other, so that they do not merge to form a solder bridge.
  • solder amount of the solder bump 23 is determined by the solder sprayer 12 using the solder fine particles 14. It can be easily adjusted by changing the supply amount. Since the solder fine particles 14 are supplied in a large amount because they are extremely small compared to the pad electrode 22, they are uniformly dispersed in the inert gas 13. Therefore, the solder bump 23 has little variation in the amount of solder.
  • the present invention is not limited to the above embodiment.
  • the surface of the substrate does not necessarily have to be up in an inert gas, and may be horizontal, down, or diagonal.
  • a wiring board (BGA) may be used instead of the silicon wafer (FC).
  • the solder fine particles may be sprayed in a solid state, and the solder fine particles may be melted in an inert gas.
  • 3 to 6 show a second embodiment of a solder bump forming method and apparatus according to the present invention.
  • description will be given based on these drawings.
  • the same part as 1st embodiment attaches
  • FIG. 3 is an enlarged cross-sectional view showing a first example of solder fine particles used in the present embodiment.
  • the solder fine particles 14 sprayed in the present embodiment are made of solid solder powder and the surface thereof is coated with a liquid 31 having a flux action.
  • the liquid 31 having a flux action means that the liquid 31 contains a component having a flux action.
  • the main component of the liquid 31 is preferably a volatile liquid such as hydrocarbons, esters, alcohols, glycols and the like.
  • an acid or an organic acid metal salt is used as the component having a flux action.
  • the acid promotes coalescence of the solder particles.
  • the acid include organic acids such as carboxylic acid, inorganic acids such as hydrochloric acid, and rosin.
  • Examples of the carboxylic acid include formic acid, oleic acid, stearic acid, and succinic acid.
  • Examples of the rosin include rosin derivatives such as L-abietic acid, rosin, and hydrogenated rosin.
  • the organic acid metal salt is composed of, for example, an acid and at least one metal element constituting the solder fine particles 14. The organic acid metal salt promotes the flux action, reacts with the molten metal salt, precipitates into an organic film, and suppresses the coalescence of solder fine particles. In the present embodiment, it is assumed that the main component of the liquid 31 is isopropyl alcohol, and the component having a flux action is an organic acid.
  • FIG. 4 and 6 show a solder bump forming process in the second embodiment
  • FIG. 4 and FIG. 5 are schematic configuration diagrams
  • FIG. 6 is a partially enlarged sectional view. The process proceeds in the order of Fig. 4 [1] to Fig. 6 [3].
  • action and effect are demonstrated about the formation method and apparatus of the solder bump of this embodiment.
  • the solder bump forming apparatus 30 of this embodiment includes a heater 32 as a heating means.
  • the heater 32 heats the substrate 20 from the bottom surface of the gas tank 11.
  • the solder sprayer may be the same as that of the first embodiment.
  • the mounting table for the substrate 20 is not shown.
  • the substrate 20 is positioned in the inert gas 13 in the gas tank 11 with the pad electrode 22 facing up. Then, a solder composition in which the liquid 31 and the solid solder fine particles 14 are mixed is sprayed into the inert gas 13 from the blowing pipe 16 (FIG. 4 [1]).
  • the solder fine particles 14 are coated with the liquid 31 shown in FIG. 3 [1] and drop onto the substrate 20 in the inert gas 13.
  • the solder fine particles 14 naturally fall by gravity and reach the substrate 20 (FIG. 4 [2]).
  • the falling speed of the solder fine particles 14 is falling in the gas, it is much higher than the falling speed in the liquid. Therefore, even if the solder fine particles 14 are small, they quickly fall and reach the substrate 20, so that the time required for forming the solder bumps 23 is short.
  • solder fine particles 14 are melted to the melting point or higher, and the liquid 31 starts to evaporate.
  • the solder bumps 23 are formed as the molten solder particles 14 gradually approach and unite (Figs. 5 [2] and 6 [1]-[3] ). Therefore, unnecessary coalescence of the solder fine particles 14 hardly occurs! /, So that the occurrence of solder bridges is suppressed.
  • the following state is caused by the action of the organic acid contained in the liquid 31. First, the coalescence between the solder fine particles 14 is suppressed. However, although not shown in FIG. 6 [2], some of the solder fine particles 14 become larger together.
  • solder fine particles 14 there is no problem even if the solder fine particles 14 are united with each other as long as they are below a certain size.
  • the solder fine particles 14 spread on the pad electrode 22 and form an alloy layer at the interface.
  • a solder film 23 ′ is formed on the pad electrode 22, and solder fine particles 14 are further combined with the solder film 23 ′. That is, the solder film 23 'grows to become a solder bump 23 as shown in FIG. 6 [3].
  • the solder fine particles 14 that have not been used for forming the solder bumps 23 are washed away in the subsequent process together with the liquid 31 residue.
  • the solder fine particles 14 have only a natural oxide film on the surface.
  • the flux action of the liquid 31 promotes the soldering between the solder fine particles 14 and the pad electrode 22 while suppressing the coalescence of the solder fine particles 14 while being heated to the melting point of the solder fine particles 14 or more, and the It promotes coalescence of the solder coating 23 ′ formed on the electrode 22 and the solder fine particles 14.
  • Such a component of flux action has been discovered by the present inventors through repeated experiments and considerations.
  • Acids can be broadly classified into inorganic acids (for example, hydrochloric acid) and organic acids (for example, fatty acids).
  • organic acids for example, fatty acids.
  • the organic acid has a small effect of bringing the solder fine particles 14 together, but has a great effect of causing the solder to wet the pad electrode 22”.
  • the following (1) and (2) can be considered as the reason why such an action occurs.
  • the organic acid has a weak effect of removing the acid film of the solder fine particles 14. For this reason, the coalescence of the solder fine particles 14 can be suppressed by the natural oxide film of the solder fine particles 14 without intentionally forming an oxide film on the solder fine particles 14.
  • the organic acid spreads the solder fine particles 14 to the pad electrode 22 to alloy the interface, and combines the solder fine particles 14 with the solder film 23 'formed on the nod electrode 22. There is an action to make it. Despite the fact that the solder fine particles 14 hardly merge with each other, the mechanism of solder wetting on the pad electrode 22 is not clear. As a presumption, there is something that breaks a little oxide film between the solder fine particles 14 and the pad electrode 22. It is thought that this reaction is occurring. For example, in the case of the gold-plated pad electrode 22, the solder wets due to the diffusion effect of gold into the solder even if the solder fine particles 14 have a thin oxide film.
  • the pad electrode 22 that also has copper power
  • copper reacts with an organic acid to form an organic acid copper salt
  • the organic acid copper salt is reduced by the difference in ionization tendency by contacting with the solder, and the metallic copper is contained in the solder. Diffusion and solder wetting progress.
  • the reason why the solder fine particles 14 are united with the solder film 23 ′ formed on the pad electrode 22 is, for example, surface tension.
  • solder fine particles 14 are coated with the organic film 33, and the solder fine particles 14 are further coated with the liquid 31 having a flux action, and the solder fine particles 14 are sprayed in this state.
  • the solder fine particles 14 As a method of coating the solder fine particles 14 with the organic film 33, the solder is melted in a dispersion medium of a heated oily liquid, and this is stirred to form droplet fine particles, which are cooled and solidified to form a spherical shape.
  • An oil-in-atomization method that obtains solder particles of the above may be mentioned. An example is described.
  • Tin-silver-copper solder is a lead-free solder with a composition of Sn 3.0 mass% Ag 0.5 mass% Cu and a melting point of 220 ° C.
  • the refined castor oil is heated to 230 ° C and the stirrer is rotated at 10,000 rpm to break the solder alloy in the refined castor oil.
  • a solder powder having the surface of the solder fine particles 14 with the organic coating 33 of maleic acid-modified rosin is obtained.
  • the inside of the container is replaced with a nitrogen atmosphere. Solder powder is washed with ethyl acetate after removing the supernatant of the container and dried in vacuum.
  • solder fine particles 14 coated with the organic film 33 are heated in the same state as in FIGS. 6 [1] to [3].
  • Each solder fine particle 14 is substantially spherical and has a uniform diameter.
  • n pieces of the fine particles 14 are united, and the volume and the amount of the organic film are n times and the surface area is n / 3 times.
  • the new solder fine particles 14 in which n solder fine particles 14 are united have an organic film amount per unit surface area n 1/3 times. That is, as the coalescence of the solder fine particles 14 progresses, the amount of the organic film per unit surface area increases.
  • solder fine particles 14 For example, eight solder fine particles 14 As a result, the volume and the amount of organic film are 8 times, the surface area is 4 times, and the amount of organic film per unit surface area is doubled. Also, as the amount of organic film per unit surface area increases, it becomes more difficult for the solder particles 14 under the organic film 33 to contact each other, so coalescence of solder particles is suppressed.
  • the solder film 23 ′ on the nod electrode 22 grows when the solder fine particles 14 merge with the solder film 31. Therefore, as the coalescence of the solder fine particles 14 progresses on the pad electrode 22, the growth of the solder film 23 ′ stops when the amount of the organic film per unit surface area of the solder film 23 ′ reaches a constant value. That is, the final solder amount of the solder film 23 ′ is determined by the size of the first solder fine particles 14 and the amount of the organic film in addition to the size of the nod electrode 22. It should be noted that the solder fine particles 14 whose amount of organic film per unit surface area has reached a constant value do not merge with the solder film 23 '.
  • the amount of the organic film of the first solder fine particle 14 allows the coalescence of the solder fine particle 14 to the solder film 23 ′ until the solder film 23 ′ reaches a certain amount of solder and is suppressed when the certain amount of solder is exceeded. Is set to do.
  • the volume is VI and the amount of the organic film is F1.
  • the shape of the solder fine particles 14 is spherical.
  • the volume is V2
  • the organic coating amount is F2
  • the surface area is S2.
  • the area of the pad electrode 22 is SO.
  • A is a correction coefficient indicating the relationship between the surface area of the solder bump 23 and the area of the pad electrode 22. Let Fmax be the maximum amount of organic coating per unit surface area.
  • the correction coefficient A varies depending on the volume of the solder bump 23, the shape of the pad electrode 22, the surface tension of the molten solder, and the like. For example, since the surface area of the solder bump 23 increases as the volume of the solder bump 23 increases, A also increases. Since the shape of the anode / node electrode 22 is less likely to be a square spherical force than a circle, the surface area is increased, and therefore A is a large value. The smaller the surface tension of the molten solder, the greater the surface area due to the difficulty of becoming a spherical surface, so A is also a large value. The actual correction factor A is obtained experimentally.
  • FIG. 7 is a schematic configuration diagram showing a third embodiment of the method and apparatus for forming solder bumps according to the present invention, and the process proceeds in the order of FIG. 7 [1] to FIG. 7 [2].
  • description will be made based on this drawing. However, the same parts as those in FIG. 1 and FIG.
  • the solder bump forming apparatus 40 of the present embodiment is further provided with a depressurizing means for depressurizing the inert gas 13 to an atmospheric pressure or lower when the solder fine particles 14 are sprayed.
  • This pressure reducing means is constituted by a part of the function of the controller 41, a vacuum pump 42, electromagnetic valves 43, 44, and the like.
  • the controller 41 is, for example, a microcomputer, and controls on / off of the vacuum pump 42 and the solder sprayer 12 and also controls opening and closing of the electromagnetic valves 43 and 44 according to a program.
  • Solenoid valve 43 is a pipe connecting vacuum pump 42 and gas tank 11
  • the solenoid valve 44 is provided in a pipe 46 that connects the solder sprayer 12 and the blowing pipe 16.
  • the controller 41 operates as follows, for example. First, the inert gas 13 in the gas tank 11 is decompressed by turning on the vacuum pump 42, opening the solenoid valve 43, turning off the solder sprayer 12, and closing the solenoid valve 44 (FIG. 7 [1]). When a certain time elapses or the pressure of the inert gas 13 falls below a certain level, the vacuum pump 42 is turned off, the solenoid valve 43 is closed, the solder sprayer 12 is turned on, and the solenoid valve 44 is opened. Fine particles 14 are sprayed into the gas tank 11 (Fig. 7 [2]).
  • the flux based on the inert gas 13 in the gas tank 11 or the viscosity based on the hydrogen gas affects the solder fine particles 14 as the inert gas 13 is depressurized. Since the viscosity coefficient k during the dropping of the solder fine particles 14 becomes small, the falling velocity V of the solder fine particles 14 becomes further larger. Therefore, the time required for forming the solder bump can be further shortened.
  • the surface of the solder fine particles 14 shown in Fig. 3 [2] is covered with the organic film 33, and the surface of the organic film 33 is covered with the liquid 31 containing the flux component. Yes.
  • the liquid 31 may be the flack material itself. In the following embodiment, the case where a flux material is used as the liquid 31 will be described.
  • solder bump forming apparatus used in the present embodiment is constructed as shown in FIG. 8, and the solder bump forming apparatus shown in FIG. 8 has substantially the same configuration as the solder bump forming apparatus shown in FIG. Built.
  • the solder bump forming apparatus 50 used in the present embodiment includes a gas tank 11, an inert gas supply device 51, a solder supply device 52, a flux supply device 53, a redox agent supply device 54, It has a controller 55 that controls these!
  • the gas tank 11 includes a mounting table 17.
  • the substrate 20 is set on the mounting table 17 with the surface 21 on which the pad electrode is formed facing upward.
  • the solder feeder 50 is used to evenly drop the solder fine particles having the structure shown in FIG. 3 [2] toward the substrate 20 on the mounting table 17.
  • the blowout pipe 56 is arranged in the upper space in the gas tank 11.
  • the blower pipe 56 of the solder feeder 50 has a number of blowout ports (not shown) arranged in a line up to the tip of the base force, so that the solder fine particles 14 can be evenly dropped into the inert gas 13 from the blowout ports. It has become.
  • solder fine particles other than the structure shown in FIG.
  • the solder dispenser 50 makes the molten solder into a fine particle state by using, for example, a spraying principle or an ultrasonic vibrator.
  • the structure to be supplied to may be out of alignment.
  • the gas tank 11 may be additionally provided with piping equipment for discharging the remaining excess solder in which solder bumps are formed on the pad electrodes of the substrate.
  • the gas tank 11 is an electric heating (not shown) for keeping the inert gas 13 above the melting point of the solder (for example, a melting point + 50 ° C) in a container made of, for example, stainless steel or heat resistant resin.
  • a heater and cooling water piping are provided.
  • the mounting table 17 is maintained in the vicinity of the melting point of the solder in the same manner as the inert gas 13 by an electric heater (not shown).
  • the inert gas supplier 51 supplies the inert gas 13 into the gas tank 11 under the control of the controller 55.
  • An inert atmosphere is formed in the gas tank 11 by the inert gas 13 supplied from the inert gas supply device 51.
  • the flux supplier 53 supplies the flux into the inert atmosphere (inert gas 13) in the gas tank 11 under the control of the controller 55.
  • the solder fine particles 14 shown in FIG. 3 [2] have a flux, so there is no need to actively supply the flux into the gas tank 11 by the flux feeder 53. On the contrary, when the flux held by the solder fine particles 14 is insufficient, the insufficient flux is supplementarily supplied.
  • the acid reducing agent supplier 54 supplies, for example, an oxygen reducing agent such as hydrogen gas as fine particles to the inert atmosphere (inert gas 13) in the gas tank 11. It is like this.
  • an oxygen reducing agent such as hydrogen gas
  • the oxidation-reduction agent supplier 54 supplies the solder fine particles adhering to the natural oxide film into the gas tank. It is desirable to actively supply the acid reducing agent into the gas tank.
  • the inert gas 13 is supplied from the inert gas supply 51 into the gas tank 11, and the inert gas 13 and the mounting table 17 in the gas tank 11 are attached with a solder melting point. Heat to near.
  • the substrate 20 is temporarily set and preheated in a preliminary chamber (not shown) communicating with the gas tank 11 and shielded from the external atmosphere.
  • the preliminary chamber communicates with the gas tank 11, the substrate 20 is set on the mounting table 17 in the gas tank 11, and the substrate 20 is positioned in the inert atmosphere of the inert gas 13. In this state, the pad electrode 22 of the substrate 20 is heated to near the solder melting point.
  • solder fine particles 14 shown in FIG. Is fed into the inert atmosphere in the gas tank 11 through the blow pipe 56.
  • the sent solder fine particles 14 form a layer and drop toward the pad electrode 22 of the substrate 20.
  • solder fine particles those having a nano-order particle size may be used. For example, when such solder fine particles are allowed to settle in a liquid, they may not reach the substrate 20 smoothly due to the viscosity of the liquid, and the settling direction may be bent.
  • the viscosity coefficient k in the above-described equation ⁇ 3> is extremely small, so that the solder fine particles 14 fall at a high speed. That is, even if the solder fine particles 14 are small, the solder fine particles 14 immediately fall and reach the substrate 20, so that the time required for forming the solder bumps 23 is short.
  • the solder particles 14 fall in the inert gas 13
  • the solder fine particles 14 easily take a form of falling in a layered form when supplied from the blowing pipe 56.
  • the inert gas 13 is heated near the melting point of the solder when the solder fine particles 14 fall in the inert gas 13, the solder fine particles 14 receive the radiant heat from the inert gas 13, while the substrate 20 Drops toward the pad electrode 22
  • solder film 23 ′ is formed on the surface of the pad electrode 22 using the solder fine particles 14 as the core of the film.
  • the solder film Consider the process by which 23 'is formed. This consideration is based on the assumption of the present inventor, but based on this consideration, the principle that the solder bump 23 is formed on the pad electrode 22 can be reasonably explained.
  • solder fine particles 14 shown in FIG. 3 [2] reach the cathode / node electrode 22 of the substrate 20, they receive the radiant heat of the heated substrate 20, and the flux 31, the organic film 33 and the solder fine particles 14 Is heated.
  • the organic film 33 dissolves into the melting flux 31 as indicated by the arrows.
  • solder 14a is the core of the solder bump 23.
  • the solder bump 23 is formed on the pad electrode 22 by the eutectic phenomenon at the interface between the solder 14a and the pad electrode 22 and the action of the newly formed organic film 33a.
  • the nucleus of the solder bump 23 is localized and grown in the range of the pad electrode 22 of the substrate 20, Even when the pad electrodes 22 are formed with a fine pitch interval, the occurrence of solder bridges between adjacent pad electrodes 22 can be suppressed.
  • the present embodiment illustrated in FIG. 8 is not limited to the illustrated configuration.
  • the surface of the substrate does not necessarily have to be up in the inert gas, and may be horizontal, down, or diagonal.
  • a wiring board (BGA) may be used instead of the silicon wafer (FC).
  • the solder fine particles may be sprayed as a solid, and the solder fine particles may be melted in an inert gas.
  • the inert gas supply device 51, the solder supply device 52, the flux supply device 53, and the oxidation-reduction agent supply device 54 may be integrated in an integrated structure like the solder sprayer 12 shown in FIG.
  • the solder bump forming apparatus shown in FIG. 8 may be equipped with a decompression means for decompressing the gas tank 11 as shown in FIG.
  • the fine pitch of the nod electrode can be achieved, and a solder bump having a large amount of solder and little variation can be obtained, and a bump can be formed in a short time. .
  • FIG. 1 is a schematic configuration diagram showing a first embodiment of a solder bump forming method and apparatus according to the present invention, and the steps proceed in the order of FIG. 1 [1] to FIG. 1 [3].
  • FIG.2 Partially enlarged sectional view of Fig. 1.
  • Fig.2 [1] to Fig.2 [3] correspond to Fig.1 [1] to Fig.1 [3], respectively.
  • FIG. 3 [1] is a first example
  • FIG. 3 [2] Is a second example.
  • ⁇ 4 It is a schematic configuration diagram showing the second embodiment, and the process proceeds in the order of FIG. 4 [1] to FIG. 4 [2].
  • ⁇ 5 It is a schematic configuration diagram showing the second embodiment, and the process proceeds in the order of FIG. 5 [1] to FIG. 5 [2].
  • FIG. 7 is a schematic configuration diagram showing a third embodiment of the method and apparatus for forming solder bumps according to the present invention, in which the process proceeds in the order of FIGS. 7 [1] to 7 [2].
  • FIG. 8 is a schematic configuration diagram showing another embodiment of the present invention.
  • FIG. 10 is a schematic cross-sectional view showing a conventional solder bump forming method.

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Abstract

[PROBLEMS] To form pad electrodes at a fine interval, and to obtain bumps having sufficient quantity of solder and having less variation. [MEANS FOR SOLVING PROBLEMS] A board (20) is positioned, at first, in inert gas (13) within a gas tank (11) with its surface (21) facing upward. Then, the inert gas (13) containing fine solder particles (14) is fed from a solder spray (12) to the gas tank (11), and the fine solder particles (14) are dropped from a blowing pipe (16) onto the board (20) in the inert gas (13). The fine solder particles (14) fall naturally by gravity and reach the board (20). The fine solder particles (14) having reached a pad electrode of the board (20) stay there by gravity and spread over the surface of the pad electrode upon the elapse of solder wetting time to form a solder film.

Description

明 細 書  Specification
はんだバンプの形成方法及び装置  Method and apparatus for forming solder bumps
技術分野  Technical field
[0001] 本発明は、半導体基板やインターポーザ基板の上に半球状のはんだバンプを形成 して、 FC (flip chip)や BGA (ball grid array)を製造する際に用いられる、はんだバン プの形成方法及び装置に関する。  [0001] The present invention relates to the formation of solder bumps that are used when FC (flip chip) or BGA (ball grid array) are manufactured by forming hemispherical solder bumps on a semiconductor substrate or interposer substrate. The present invention relates to a method and an apparatus.
背景技術  Background art
[0002] 近年、電子機器の小型化及び薄型化に伴!、、電子部品の高密度実装技術が急速 に進展している。この高密度実装を実現する半導体装置として、半球状のはんだバ ンプを有する FCや BGAが使われて!/、る。  [0002] In recent years, with the miniaturization and thinning of electronic devices, high-density mounting technology for electronic components is rapidly progressing. FC and BGA with hemispherical solder bumps are used as semiconductor devices to achieve this high-density mounting!
[0003] ノッド電極上にはんだバンプを形成する方法として、溶融はんだにパッド電極を接 触させる方法 (溶融はんだ法）、パッド電極上にはんだペーストをスクリーン印刷しリフ ローする方法 (スクリーン印刷法）、ノ¾ /ド電極上にはんだボールを載置しリフローす る方法（はんだボール法）、ノ^ド電極にはんだメツキを施す方法 (メツキ法)等が一般 的である。これら以外にも、例えば特許文献 1に記載されたはんだバンプの形成方法 が知られている。  [0003] As a method for forming solder bumps on the nod electrode, a method in which the pad electrode is brought into contact with the molten solder (molten solder method), and a method in which a solder paste is screen printed on the pad electrode and reflowed (screen printing method) In general, there are a method of placing a solder ball on the solder electrode and reflowing (solder ball method), a method of soldering the solder electrode (mesh method), and the like. In addition to these, for example, a solder bump forming method described in Patent Document 1 is known.
[0004] 図 10は、特許文献 1に記載されたはんだ形成方法を示す概略断面図である。以下 、この図面に基づき説明する。  FIG. 10 is a schematic cross-sectional view showing the solder forming method described in Patent Document 1. Hereinafter, description will be given based on this drawing.
[0005] この形成方法では、まず、はんだの融点以上に加熱された不活性溶剤 80中に、銅 電極 81を表面に有するウェハ 82を当該表面が下になるように浸漬する。続いて、不 活性溶剤 80中において、溶融はんだ 83から成るはんだ粒子 84を上へ向けて噴射 することにより、はんだ粒子 84をウェハ 82に接触させて銅電極 81にはんだバンプ（ 図示せず)を形成する。更に詳しく説明する。  In this forming method, first, a wafer 82 having a copper electrode 81 on the surface thereof is immersed in an inert solvent 80 heated to a melting point or higher of the solder so that the surface is on the bottom. Subsequently, solder particles 84 made of molten solder 83 are sprayed upward in an inert solvent 80 to bring the solder particles 84 into contact with the wafer 82 and solder bumps (not shown) are formed on the copper electrodes 81. Form. This will be described in more detail.
[0006] 加熱槽 85内の溶融はんだ 83と不活性溶剤 80とは、はんだの融点よりやや高い温 度、例えば 200°Cに温度制御される。加熱槽 85内の溶融はんだ 83は、はんだ導入 管 86からはんだ微粒ィ匕装置 87内に吸引される。また、はんだ微粒ィ匕装置 87は、溶 融はんだ 83と同温となっている不活性溶剤 80を不活性溶剤導入管 88から吸引し、 これら 2液を混合攪拌して溶融はんだ 83を破砕し粒子化する。そして、はんだ粒子 8 4を含んだ不活性溶剤 80は、混合液導出管 89から噴出装置 90に液送され、ノズル 91から上方へ噴射される。 [0006] The temperature of the molten solder 83 and the inert solvent 80 in the heating tank 85 is controlled to a temperature slightly higher than the melting point of the solder, for example, 200 ° C. The molten solder 83 in the heating tank 85 is sucked into the solder fine particle device 87 from the solder introduction tube 86. Also, the solder fine particle device 87 sucks the inert solvent 80 having the same temperature as the molten solder 83 from the inert solvent introduction pipe 88, and These two liquids are mixed and stirred to crush the molten solder 83 into particles. Then, the inert solvent 80 containing the solder particles 84 is fed from the mixed solution outlet pipe 89 to the ejection device 90 and is ejected upward from the nozzle 91.
[0007] 不活性溶剤 80中のはんだ粒子 84は、不活性溶剤 80で被覆された状態となってい るので、外気と接触することがない。このため、はんだ粒子 84の表面は、金属表面を 保ち、活性状態にある。そして、不活性溶剤 80中のはんだ粒子 84は、不活性溶剤 8 0中に浸漬されたウェハ 82の銅電極 81に接触すると、銅電極 81とはんだ合金層を 形成して銅電極 81表面に付着することにより、銅電極 81表面を溶融したはんだ皮膜 (図示せず)で覆う。続いて、はんだ粒子 84はこのはんだ皮膜に吸着しやすいので、 この部分のはんだ粒子 84が次々にはんだ皮膜上に付着する。  [0007] Since the solder particles 84 in the inert solvent 80 are covered with the inert solvent 80, they do not come into contact with the outside air. For this reason, the surface of the solder particle 84 keeps the metal surface and is in an active state. Then, when the solder particles 84 in the inert solvent 80 come into contact with the copper electrode 81 of the wafer 82 immersed in the inert solvent 80, a solder alloy layer is formed with the copper electrode 81 and adheres to the surface of the copper electrode 81. By doing so, the surface of the copper electrode 81 is covered with a molten solder film (not shown). Subsequently, since the solder particles 84 are likely to be adsorbed to the solder film, the solder particles 84 in this portion adhere to the solder film one after another.
[0008] 一方、銅電極 81上に付着しなかったはんだ粒子 84は、その比重差により徐々に下 降し、加熱槽 85の底部に堆積する。このように、はんだ粒子 84が上方へ噴出する不 活性溶剤 80中に、銅電極 81を下にしてウェハ 82を浸漬することにより、銅電極 81表 面にのみ選択的にはんだバンプ（図示せず)を形成することができる。  On the other hand, the solder particles 84 that have not adhered to the copper electrode 81 gradually fall due to the difference in specific gravity, and accumulate on the bottom of the heating tank 85. In this way, by immersing the wafer 82 with the copper electrode 81 facing down in the inert solvent 80 in which the solder particles 84 are ejected upward, solder bumps (not shown) can be selectively applied only to the surface of the copper electrode 81. ) Can be formed.
[0009] 特許文献 1：特公平 7— 114205号公報 (第 1図等）  [0009] Patent Document 1: Japanese Patent Publication No. 7-114205 (Fig. 1 etc.)
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0010] し力しながら、溶融はんだ法は、ノッド電極のファインピッチ化に適するという特長 があるものの、はんだバンプのはんだ量が少なくかつそのバラツキも大きいという欠点 がある。スクリーン印刷法は、一括で容易にはんだバンプを形成することができるとい う特長があるものの、ファインピッチのマスクを使用すると目詰まりやはんだ量の不均 一が発生しやすいので、ファインピッチ化に適さないという欠点がある。はんだボール 法は、近年の傾向として一つの半導体装置に使われるはんだボールの数が極めて 多くなり、し力もはんだボールの大きさも極めて小さくなつていることから、製造コスト が高くつくという欠点がある。メツキ法は、近年普及しつつある鉛フリーはんだに対し て適当なメツキ液がないという欠点がある。また、特許文献 1の形成方法では、銅電 極にはんだ粒子が付着しにく!/、、すなわちはんだ濡れ性が悪 、と 、う欠点があるた め、実用化が困難であった。 [0011] また、本発明者は、次のような技術を開発した。まず、はんだ微粒子と、フラックス作 用を有する液体と、表面に電極を有する基板とを用意する。そして、はんだの融点以 上に前記液体を加熱し、表面を上にして基板を液体中に位置付け、はんだ微粒子を 前記液体中に噴射して基板上の電極に向けて落下させる。これにより、パッド電極上 にはんだバンプを形成する。その結果、従来の諸問題を解決でき、はんだバンプの ファインピッチ化が一応達成された。 [0010] However, although the molten solder method has a feature that it is suitable for fine pitch of the nod electrode, it has a drawback that the solder amount of the solder bump is small and its variation is large. Although the screen printing method has the feature that solder bumps can be easily formed in one batch, clogging and uneven solder amount are likely to occur when a fine pitch mask is used. There is a disadvantage that it is not suitable. The solder ball method has a drawback in that the number of solder balls used in one semiconductor device is extremely large as a recent trend, and the manufacturing cost is high because the force and the size of the solder balls are extremely small. The plating method has the disadvantage that there is no suitable plating solution for lead-free solder, which has become widespread in recent years. Further, the forming method of Patent Document 1 has a drawback that solder particles are difficult to adhere to a copper electrode! / That is, solder wettability is poor, and thus it has been difficult to put it to practical use. [0011] Further, the present inventor has developed the following technique. First, solder fine particles, a liquid having flux action, and a substrate having electrodes on the surface are prepared. Then, the liquid is heated above the melting point of the solder, the substrate is positioned in the liquid with the surface facing up, and solder fine particles are sprayed into the liquid and dropped toward the electrodes on the substrate. As a result, solder bumps are formed on the pad electrodes. As a result, the conventional problems could be solved, and finer pitch solder bumps were achieved.
[0012] ここで、更なるファインピッチ化を図るには、はんだ微粒子を小さくする必要がある。  Here, in order to achieve a finer pitch, it is necessary to reduce the solder fine particles.
はんだ微粒子が大きいと、電極間ではんだブリッジが発生しやすくなるからである。し かし、はんだ微粒子を小さくすればするほど、液体中でのはんだ微粒子の落下速度 が低下するため、はんだバンプの形成に長時間を要することになる。  This is because if the solder fine particles are large, solder bridges are likely to occur between the electrodes. However, the smaller the solder fine particles, the lower the falling speed of the solder fine particles in the liquid, and the longer it takes to form the solder bumps.
[0013] その理由について、以下に説明する。はんだ微粒子は、速度に比例する粘性抵抗 力を受けながら液体中を落下するものとする。このとき、はんだ微粒子の質量を m、 重力加速度を g、粘性係数を kとし、鉛直上向きに z軸をとると、落下するはんだ微粒 子の運動方程式は次式で表せる。  [0013] The reason will be described below. The solder fine particles shall fall in the liquid while receiving a viscous resistance proportional to the velocity. At this time, if the mass of the solder fine particles is m, the gravitational acceleration is g, the viscosity coefficient is k, and the z-axis is taken vertically upward, the equation of motion of the falling solder fine particles can be expressed by the following equation.
m (d2z/dt2) = - mg - k (dz/dt) · , ·《1》 m (d 2 z / dt 2 ) =-mg-k (dz / dt)
[0014] 式《1》の右辺第二項が粘性抵抗力である。初速度 Vを 0として式《1》を解くことによ  [0014] The second term on the right side of the formula << 1 >> is the viscous resistance. By solving equation << 1 >> with initial velocity V set to 0
0  0
り、時刻 tにおけるはんだ微粒子の速度 v(t)が次式で表せる。  Thus, the velocity v (t) of the solder fine particles at time t can be expressed by the following equation.
v(t)= (mg/k) e-(k m)t- (m/k) g -((2)> v (t) = (mg / k) e- (km) t- (m / k) g-((2)>
[0015] ここで、 k》mとすると、式《2》の右辺第一項を無視できる。したがって、次式が得ら れる。 [0015] Here, if k >> m, the first term on the right side of the expression << 2 >> can be ignored. Therefore, the following equation is obtained.
v= - (m/k) g …く〈3》  v =-(m / k) g ... <3>
[0016] 式《3》から明らかなように、はんだ微粒子が小さいほどすなわち mが小さいほど、液 体中でのはんだ微粒子の落下速度 Vが低下する。  As is apparent from the equation << 3 >>, the smaller the solder fine particles, that is, the smaller m is, the lower the falling velocity V of the solder fine particles in the liquid.
[0017] そこで、本発明の目的は、ノッド電極のファインピッチ化を図れるとともに、はんだ量 が多くかつバラツキも少ないはんだバンプを得られ、しかも短時間ではんだバンプを 形成できる、はんだバンプの形成方法及び装置を提供することにある。  [0017] Therefore, an object of the present invention is to provide a solder bump forming method capable of obtaining a fine pitch of the nod electrode, obtaining a solder bump with a large amount of solder and little variation, and capable of forming the solder bump in a short time. And providing an apparatus.
課題を解決するための手段  Means for solving the problem
[0018] 本発明に係るはんだバンプの形成方法は、パッド電極を表面に有する基板を当該 表面が上になるように不活性気体中に位置付け、溶融はんだ力も成るはんだ微粒子 を不活性気体中に噴霧し (送りだす)、当該はんだ微粒子を基板上に落下させること により、パッド電極上にはんだバンプを形成する、というものである。本発明には、不 活性気体の分散媒と液体のはんだ微粒子の分散相とから成る分散系（エー口ゾル: a erosol)中に基板を置くことにより、ノ ッド電極上にはんだバンプを形成する技術も含 まれる。ここでいう「基板」には、半導体ウェハや配線板などが含まれる。また、「はん だバンプ」には、半球状や突起状のものに限らず、膜状のものも含まれる。不活性気 体は、窒素やアルゴンなどを主成分とするものの、実質的に不活性であればよぐは んだ付に悪影響を与えな 、程度の酸素を含む気体であってもよ 、。 [0018] A method for forming a solder bump according to the present invention includes a substrate having a pad electrode on a surface thereof. The solder bumps are placed on the pad electrode by spraying (sending out) solder fine particles, which are positioned in an inert gas so that the surface is on top, and have a molten solder force, into the inert gas and dropping the solder fine particles onto the substrate. Is formed. In the present invention, a solder bump is formed on a node electrode by placing the substrate in a dispersion system (aerosol) composed of a dispersion medium of an inert gas and a dispersion phase of liquid solder fine particles. This technology is also included. The “substrate” here includes a semiconductor wafer, a wiring board, and the like. The “solder bump” is not limited to a hemispherical shape or a protrusion shape, but includes a film shape. Although the inert gas is mainly composed of nitrogen or argon, it may be a gas containing a certain amount of oxygen so long as it is substantially inert without adversely affecting the soldering.
[0019] 不活性気体中において、基板はノッド電極側を上にして保持されている。このとき、 基板上の不活性気体中にはんだ微粒子を噴霧すると、はんだ微粒子は重力によつ て自然落下し基板上に到達する。基板のパッド電極上に到達したはんだ微粒子は、 重力によってそこに留まり、「ある時間」が経過するとパッド電極表面に広がってはん だ皮膜を形成する。続いて、そのはんだ皮膜上に到達したはんだ微粒子は、重力に よってそこに留まり、同じように「ある時間」が経過すると広がってはんだ皮膜を厚くす る。これが繰り返されて、はんだ皮膜が成長してはんだバンプとなる。  In the inert gas, the substrate is held with the nod electrode side facing up. At this time, when the solder fine particles are sprayed into the inert gas on the substrate, the solder fine particles spontaneously drop due to gravity and reach the substrate. The solder fine particles that have reached the pad electrode of the substrate stay there due to gravity, and after a certain period of time, spreads on the surface of the pad electrode to form a solder film. Subsequently, the solder fine particles that have reached the solder film stay there due to gravity, and in the same way, after a certain amount of time has passed, it spreads and thickens the solder film. This is repeated, and the solder film grows to become solder bumps.
[0020] はんだが濡れるために、前述した「ある時間」（以下「はんだ濡れ時間」という。 )が必 要である。特許文献 1の技術では、不活性液体中において下向きのパッド電極に対 してはんだ微粒子を噴き上げて接触させるため、はんだ微粒子がパッド電極に接す る時間が一瞬でしかな!/、ので、はんだ濡れ性が悪 ヽと考えられる。  [0020] In order for the solder to get wet, the aforementioned "certain time" (hereinafter referred to as "solder wetting time") is necessary. In the technique of Patent Document 1, since the solder fine particles are sprayed and brought into contact with the downward-facing pad electrode in the inert liquid, it takes only a moment for the solder fine particles to contact the pad electrode. The wettability is considered bad.
[0021] また、本発明者は、不活性気体中ではんだ微粒子同士が落下中に接触しても、こ れらが合体して大きいはんだ微粒子になる条件が整えにく 、ため、はんだ微粒子を 不活性気体中を介して基板に向けて送りだすことに問題がないことを見出した。した がって、本発明では、ファインピッチのパッド電極に対しても、はんだブリッジ等が発 生しない。更に、はんだバンプのはんだ量は、はんだ微粒子の供給量を変えることに より容易に調整できる。し力も、はんだ微粒子は、ノ^ド電極に比べて極めて小さいこ とにより多量に供給されるので、不活性気体中に均一に分散する。したがって、はん だバンプのはんだ量のバラツキも少ない。これにカ卩え、はんだ微粒子が霧状すなわ ち極めて微細になっているので、パッド電極のファインピッチ化に適する。し力も、は んだ微粒子は液体中ではなく気体中を落下することにより、前述の式《3》における粘 性係数 kが極めて小さくなるため、はんだ微粒子の落下速度は大きい。すなわち、は んだ微粒子が小さくてもすぐに落下するので、はんだバンプの形成に要する時間も 短い。 [0021] In addition, even if the solder fine particles come into contact with each other during the fall in the inert gas, the present inventor cannot easily prepare the condition that these fine particles are united into large solder fine particles. It has been found that there is no problem in sending out toward the substrate through the inert gas. Therefore, in the present invention, a solder bridge or the like does not occur even for a fine pitch pad electrode. Furthermore, the solder amount of the solder bump can be easily adjusted by changing the supply amount of the solder fine particles. Since the solder fine particles are extremely small compared to the node electrode, a large amount of solder fine particles are supplied, so that the solder fine particles are uniformly dispersed in the inert gas. Therefore, there is little variation in the solder amount of solder bumps. In addition to this, the solder fine particles are foggy. Since it is extremely fine, it is suitable for making fine pitches of pad electrodes. As for the soldering force, the falling speed of the solder fine particles is large because the solder fine particles fall in the gas, not in the liquid, and the viscosity coefficient k in the above-mentioned formula << 3 >> becomes extremely small. That is, even if the solder fine particles are small, they fall quickly, so the time required for forming the solder bumps is short.
[0022] 本発明に係るはんだバンプの形成方法は、パッド電極を表面に有する基板を不活 性気体中に位置付け、不活性気体中にぉ 、て溶融はんだ力 成るはんだ微粒子を ノッド電極に向けて噴霧することにより、パッド電極上にはんだバンプを形成する、と いうものである。  [0022] In the method for forming a solder bump according to the present invention, a substrate having a pad electrode on its surface is positioned in an inert gas, and the solder fine particles having a molten solder force are directed toward the nod electrode in the inert gas. By spraying, solder bumps are formed on the pad electrodes.
[0023] はんだ微粒子をパッド電極に向けて噴霧するのであれば、不活性気体中にぉ 、て 基板の表面は必ずしも上にする必要はなく横でも下でも斜めでもよ！/ヽ。はんだ微粒 子は、霧状すなわち極めて微細であることにより、ブラウン運動によって不規則に動く 。したがって、はんだ微粒子をパッド電極に向けて噴霧すると、はんだ微粒子がパッ ド電極の周囲を浮遊するので、はんだ微粒子をパッド電極にはんだ濡れ時間以上留 まらせることができる。この場合は、 + z方向に初速度 Vではんだ微粒子を噴霧したと  [0023] If the solder fine particles are sprayed toward the pad electrode, the surface of the substrate does not necessarily have to be in the inert gas, and may be laterally, downwardly or diagonally! / ヽ. Solder particles move erratically due to Brownian motion due to their mist, ie, very fine. Therefore, when the solder fine particles are sprayed toward the pad electrode, the solder fine particles float around the pad electrode, so that the solder fine particles can remain on the pad electrode for the solder wet time or longer. In this case, solder fine particles are sprayed at the initial velocity V in the + z direction.
0  0
して前述の式《1》を解けば明らかなように、はんだ微粒子がパッド電極に到達する時 間は液体中に比べて極めて短い。すなわち、はんだ微粒子が小さくてもすぐにパッド 電極に到達するので、はんだバンプの形成に要する時間も短 、。  As is clear from the above equation << 1 >>, the time for the solder fine particles to reach the pad electrode is extremely short compared to that in the liquid. In other words, even if the solder particles are small, they reach the pad electrode immediately, so the time required to form the solder bumps is short.
[0024] 本発明に係るはんだバンプの形成方法は、不活性気体中に基板を位置付ける際 に、基板の表面が下になるように位置付ける、というものである。この場合は、はんだ バンプにならな力つた不要なはんだ微粒子が基板上力も落下しやす 、ので、後工程 における洗浄等が容易になる。  [0024] The solder bump forming method according to the present invention is such that when the substrate is positioned in an inert gas, the surface of the substrate is positioned downward. In this case, unnecessary solder fine particles that have the same force as the solder bumps can easily drop on the substrate, facilitating cleaning in subsequent processes.
[0025] 本発明に係るはんだバンプの形成方法は、はんだ微粒子を噴霧する際にフラック スも噴霧する、というものである。はんだ微粒子を噴霧する際とは、例えばはんだ微粒 子を噴霧する前、噴霧すると同時、又は噴霧した直後などである。フラックスの作用に よって、不活性気体中でのはんだ濡れ性が更に向上する。ここでいう「フラックス」に は、ロジン、界面活性剤、その他はんだ表面の酸ィ匕膜を除去する作用を有するもの が含まれる。 [0026] 本発明に係るはんだバンプの形成方法は、不活性気体中に水素ガスを混合した、 というものである。水素ガスは、パッド電極表面及びはんだ微粒子表面の酸ィ匕膜を還 元して除去するので、不活性気体中でのはんだ濡れ性が更に向上する。 [0025] The solder bump forming method according to the present invention is such that when the solder fine particles are sprayed, the flux is also sprayed. The spraying of solder fine particles is, for example, before spraying the solder fine particles, at the same time as spraying, or immediately after spraying. The solder wettability in an inert gas is further improved by the action of the flux. As used herein, “flux” includes rosin, surfactant, and other substances that have the effect of removing the acid film on the solder surface. [0026] The solder bump forming method according to the present invention is such that hydrogen gas is mixed in an inert gas. Since hydrogen gas reduces and removes the oxide film on the surface of the pad electrode and the surface of the solder fine particles, the solder wettability in an inert gas is further improved.
[0027] 本発明に係るはんだバンプの形成方法は、はんだ微粒子の直径は隣接するパッド 電極同士の周端間の最短距離よりも小さい、というものである。この場合、隣接する二 つのパッド電極上にそれぞれ到達したはんだ微粒子同士は、接することがな 、ので、 合体してはんだブリッジを形成することがない。  [0027] The solder bump forming method according to the present invention is such that the diameter of the solder fine particles is smaller than the shortest distance between the peripheral ends of adjacent pad electrodes. In this case, the solder fine particles that have reached each of the two adjacent pad electrodes do not come into contact with each other, so that they do not combine to form a solder bridge.
[0028] 本発明に係るはんだバンプの形成方法は、不活性気体がはんだの融点以上に加 熱されている、というものである。この場合、はんだ微粒子は、はんだの融点以上の不 活性気体中にあるので、確実に液体の状態に保たれる。換言すると、はんだ微粒子 は万が一にも固体ィ匕することがないので、はんだ濡れ性が良好である。  [0028] The solder bump forming method according to the present invention is such that the inert gas is heated to a temperature higher than the melting point of the solder. In this case, since the solder fine particles are in an inert gas having a melting point higher than the melting point of the solder, the solder fine particles are surely kept in a liquid state. In other words, the solder fine particles do not solidify by any chance, so the solder wettability is good.
[0029] 本発明に係るはんだバンプの形成方法は、はんだ微粒子力 固体のまま噴霧され 、不活性気体中で溶融する、というものである。固体のはんだ微粒子はその状態で一 体ィ匕してしまうことがな！、ので、取り扱！/、が容易である。  [0029] The solder bump forming method according to the present invention is such that the solder fine particle force is sprayed as a solid and melted in an inert gas. Solid solder fine particles will not be combined in that state! So, handle! /, Easy.
[0030] 本発明に係るはんだバンプの形成装置は、気体槽及びはんだ噴霧器を備えたもの である。気体槽は、不活性気体と、パッド電極を表面に有するとともに当該表面が上 になるように不活性気体中に位置付けられる基板とを収容する。はんだ噴霧器は、溶 融したはんだカゝら成るはんだ微粒子を不活性気体中に噴霧し、はんだ微粒子を基板 上に落下させる。  The solder bump forming apparatus according to the present invention includes a gas tank and a solder sprayer. The gas tank contains an inert gas and a substrate that has a pad electrode on its surface and is positioned in the inert gas so that the surface is on top. The solder sprayer sprays solder fine particles, such as molten solder particles, into an inert gas and drops the solder fine particles onto the substrate.
[0031] 気体槽内の不活性気体中にお!ヽて、基板はパッド電極側を上にして保持されて ヽ る。このとき、はんだ噴霧器カゝら基板上の不活性気体中にはんだ微粒子を噴霧する と、はんだ微粒子は重力によって自然落下し基板上に到達する。以下、上記形成方 法と同じ作用を奏する。  [0031] In an inert gas in the gas tank, the substrate is held with the pad electrode side facing up. At this time, when the solder fine particles are sprayed into the inert gas on the substrate such as the solder sprayer, the solder fine particles naturally fall by gravity and reach the substrate. Hereinafter, the same effect as the above forming method is exhibited.
[0032] 本発明に係るはんだバンプの形成装置は、気体槽及びはんだ噴霧器を備えたもの である。気体槽は、はんだの融点以上に加熱された不活性気体と、ノッド電極を表面 に有するとともに不活性気体中に位置付けられる基板とを収容する。はんだ噴霧器 は、溶融はんだ力も成るはんだ微粒子を、不活性気体中においてパッド電極に向け て噴霧する。上記形成方法と同じ作用を奏する。 [0033] 本発明に係るはんだバンプの形成装置は、基板は不活性気体中に当該基板の表 面が下になるように位置付けられる、というものである。上記形成方法と同じ作用を奏 する。 [0032] A solder bump forming apparatus according to the present invention includes a gas tank and a solder sprayer. The gas tank accommodates an inert gas heated to a temperature equal to or higher than the melting point of the solder and a substrate that has a nod electrode on its surface and is positioned in the inert gas. The solder sprayer sprays solder fine particles with molten solder force toward the pad electrode in an inert gas. The same effect as the above forming method is achieved. [0033] The solder bump forming apparatus according to the present invention is such that the substrate is positioned in an inert gas so that the surface of the substrate faces down. It has the same effect as the above forming method.
[0034] 本発明に係るはんだバンプの形成装置は、はんだ噴霧器がはんだ微粒子をパッド 電極に向けて噴霧する際に、フラックスも噴霧する、というものである。上記形成方法 と同じ作用を奏する。  The solder bump forming apparatus according to the present invention is such that when the solder sprayer sprays solder fine particles toward the pad electrode, the flux is also sprayed. It has the same effect as the above forming method.
[0035] 本発明に係るはんだバンプの形成装置は、不活性気体中に水素ガスが混合された In the solder bump forming apparatus according to the present invention, hydrogen gas is mixed in an inert gas.
、というものである。上記形成方法と同じ作用を奏する。 That's it. The same effect as the above forming method is achieved.
[0036] 本発明に係るはんだバンプの形成装置は、はんだ微粒子の直径が隣接するパッド 電極同士の周端間の最短距離よりも小さい、というものである。上記形成方法と同じ 作用を奏する。 The solder bump forming apparatus according to the present invention is such that the diameter of the solder fine particles is smaller than the shortest distance between the peripheral edges of adjacent pad electrodes. The same effect as the above forming method is achieved.
[0037] 本発明に係るはんだバンプの形成装置は、不活性気体がはんだの融点以上に加 熱されている、というものである。上記形成方法と同じ作用を奏する。  [0037] The solder bump forming apparatus according to the present invention is such that the inert gas is heated above the melting point of the solder. The same effect as the above forming method is achieved.
[0038] 本発明に係るはんだバンプの形成装置は、はんだ微粒子力 固体のまま噴霧され 、不活性気体中で溶融する、というものである。上記形成方法と同じ作用を奏する。  The solder bump forming apparatus according to the present invention is such that the solder fine particle force is sprayed as a solid and melts in an inert gas. The same effect as the above forming method is achieved.
[0039] 本発明に係るはんだバンプの形成方法は、溶融したはんだ力も成るはんだ微粒子 に代えて固体のはんだ力 成るはんだ微粒子を用い、フラックス作用を有する液体で はんだ微粒子を被覆し、この状態ではんだ微粒子を噴霧する、というものである。  The method for forming a solder bump according to the present invention uses solder fine particles having a solid solder force instead of solder fine particles having a molten solder force, and coats the solder fine particles with a liquid having a flux action. It sprays fine particles.
[0040] 本発明に係るはんだバンプの形成方法は、溶融したはんだ力も成るはんだ微粒子 に代えて固体のはんだ力 成るはんだ微粒子を用い、有機皮膜ではんだ微粒子を 被覆し、更にフラックス作用を有する液体ではんだ微粒子を被覆し、この状態ではん だ微粒子を噴霧する、というものである。  [0040] The method for forming a solder bump according to the present invention uses a solder fine particle having a solid solder force instead of a solder fine particle having a melted solder force, and coats the solder fine particle with an organic film, and further a liquid having a flux action. In this state, solder fine particles are coated and solder fine particles are sprayed.
[0041] 本発明に係るはんだバンプの形成方法は、基板上に落下したはんだ微粒子をその 融点以上に加熱するとともに、この加熱によって液体を蒸発させる、というものである 。液体の蒸発に伴い、はんだ微粒子同士が徐々に接近して合一することにより、はん だバンプが形成される。そのため、はんだ微粒子の不要な合一が発生しにくいので、 はんだブリッジの発生等が抑制される。  [0041] The solder bump forming method according to the present invention heats the solder fine particles dropped on the substrate to the melting point or higher and evaporates the liquid by this heating. As the liquid evaporates, the solder particles gradually approach and unite to form solder bumps. For this reason, unnecessary coalescence of solder fine particles is unlikely to occur, and the occurrence of solder bridges is suppressed.
[0042] 本発明に係るはんだバンプの形成方法は、はんだ微粒子を噴霧する際に、不活性 気体を大気圧以下に減圧しておぐというものである。このとき、不活性気体が減圧さ れるほど、粘性係数 kが小さくなるので、はんだ微粒子の落下速度は更に大きくなる。 そのため、はんだバンプの形成に要する時間が更に短力べなる。 [0042] The solder bump forming method according to the present invention is inactive when the solder fine particles are sprayed. The gas is depressurized below atmospheric pressure. At this time, as the inert gas is depressurized, the viscosity coefficient k decreases, so that the falling speed of the solder fine particles further increases. For this reason, the time required for forming the solder bumps is further reduced.
[0043] 本発明に係るはんだバンプの形成装置は、噴霧器は、溶融したはんだ力も成るは んだ微粒子に代えて、フラックス作用を有する液体で被覆されるとともに固体のはん だ力も成るはんだ微粒子を噴霧する、 t 、うものである。  [0043] In the solder bump forming apparatus according to the present invention, instead of the solder fine particles having a molten solder force, the sprayer is coated with a liquid having a flux action and the solder fine particles having a solid solder force. To spray, t.
[0044] 本発明に係るはんだバンプの形成装置は、噴霧器が、溶融したはんだカゝら成るは んだ微粒子に代えて、有機皮膜で被覆され更にフラックス作用を有する液体で被覆 されるとともに固体のはんだ力も成るはんだ微粒子を噴霧する、というものである。 [0044] In the solder bump forming apparatus according to the present invention, the sprayer is coated with a liquid having a flux action and is coated with an organic film, instead of the solder fine particles made of molten solder powder. It sprays solder fine particles that also have soldering power.
[0045] 本発明に係るはんだバンプの形成装置は、基板上に落下したはんだ微粒子をその 融点以上に加熱するとともに、この加熱によって液体を蒸発させる加熱手段を、更に 備えたものである。上記形成方法と同じ作用を奏する。 [0045] The solder bump forming apparatus according to the present invention further includes heating means for heating the solder fine particles dropped on the substrate to the melting point or higher and evaporating the liquid by this heating. The same effect as the above forming method is achieved.
[0046] 本発明に係るはんだバンプの形成装置は、はんだ微粒子を噴霧する際に、不活性 気体を大気圧以下に減圧しておく減圧手段を、更に備えたものである。上記形成方 法と同じ作用を奏する。 The solder bump forming apparatus according to the present invention further includes a depressurizing means for depressurizing the inert gas to atmospheric pressure or lower when spraying the solder fine particles. Has the same effect as the above formation method.
発明の効果  The invention's effect
[0047] 本発明に係るはんだバンプの形成方法及び装置によれば、不活性気体中にぉ ヽ てはんだ微粒子を噴霧し、はんだ微粒子を基板上に落下させてパッド電極上にはん だバンプを形成することにより、パッド電極上に到達したはんだ微粒子を重力によつ てはんだ濡れ時間以上そこに留めておくことができるので、はんだ濡れ性を向上でき る。また、不活性気体中ではんだ微粒子同士が接触しても、これらが合体して大きい はんだ微粒子になるものは少なぐなおかつ、はんだ微粒子が霧状すなわち極めて 微細になって 、るので、ファインピッチのパッド電極でのはんだブリッジ等を防止でき る。更に、はんだ微粒子の供給量を変えることにより、はんだバンプのはんだ量を容 易に調整できる。し力も、はんだ微粒子はパッド電極に比べて極めて小さいことにより 、多量に供給されて不活性気体中に均一に分散するので、はんだバンプのはんだ量 を均一化できる。したがって、ノ¾ /ド電極のファインピッチ化を図れるとともに、はんだ 量が多くかつバラツキも少ないはんだバンプを得られる。 [0048] しかも、はんだ微粒子がパッド電極に到達する時間は液体中に比べて極めて短!ヽ こと力ゝら、はんだ微粒子が小さくてもすぐにパッド電極に到達するので、はんだバンプ の形成に要する時間を短縮できる。この効果は、更なるファインピッチ化に伴うはん だ微粒子の縮小化に、大きく寄与できる。 [0047] According to the method and apparatus for forming a solder bump according to the present invention, the solder fine particles are sprayed in an inert gas, and the solder fine particles are dropped on the substrate to form the solder bumps on the pad electrodes. By forming the solder fine particles that have reached the pad electrode, the solder wettability can be improved because the solder fine particles can be kept there by the gravitational force over the solder wetting time. In addition, even if solder fine particles come into contact with each other in an inert gas, there are few things that coalesce into large solder fine particles, and the solder fine particles are mist-like, that is, extremely fine. Solder bridges etc. at pad electrodes can be prevented. Furthermore, the amount of solder bumps can be easily adjusted by changing the amount of solder fine particles supplied. Since the solder fine particles are extremely small as compared with the pad electrode, they are supplied in a large amount and uniformly dispersed in the inert gas, so that the solder amount of the solder bumps can be made uniform. Accordingly, it is possible to obtain a solder bump with a small amount of solder and a small amount of variation while achieving a fine pitch of the electrode / electrode. [0048] Moreover, the time required for the solder fine particles to reach the pad electrode is extremely short compared to that in the liquid! As a matter of fact, even if the solder fine particles are small, they reach the pad electrode immediately, which is necessary for forming the solder bumps. You can save time. This effect can greatly contribute to the reduction of solder fine particles accompanying further fine pitch.
[0049] さらに、本発明に係るはんだバンプの形成方法及び装置によれば、はんだ微粒子 をパッド電極に向けて噴霧することにより、不活性気体中において基板をどのような 向きにも置くことができるので、作業の自由度を向上できる。  Furthermore, according to the method and apparatus for forming a solder bump according to the present invention, the substrate can be placed in any direction in the inert gas by spraying the solder fine particles toward the pad electrode. Therefore, the degree of freedom of work can be improved.
[0050] 本発明に係るはんだバンプの形成方法及び装置によれば、基板のパッド電極側を 下にして、下側からはんだ微粒子を噴霧することにより、はんだバンプにならな力つた 不要なはんだ微粒子が基板に付着しにくいので、後工程における洗浄等を容易化 できる。  [0050] According to the method and apparatus for forming solder bumps according to the present invention, unnecessary solder fine particles that have the same strength as solder bumps are sprayed from the lower side with the pad electrode side of the substrate facing down. Since it is difficult to adhere to the substrate, it is possible to facilitate cleaning in a later process.
[0051] 本発明に係るはんだバンプの形成方法及び装置によれば、不活性気体中にフラッ タスも噴霧するようにしたので、不活性気体中でのはんだ濡れ性を更に向上できる。  [0051] According to the solder bump forming method and apparatus of the present invention, since the flats are also sprayed in the inert gas, the solder wettability in the inert gas can be further improved.
[0052] 本発明に係るはんだバンプの形成方法及び装置によれば、不活性気体中に水素 ガスを含ませたので、不活性気体中でのはんだ濡れ性を更に向上できる。  [0052] According to the solder bump forming method and apparatus of the present invention, since hydrogen gas is included in the inert gas, the solder wettability in the inert gas can be further improved.
[0053] 本発明に係るはんだバンプの形成方法及び装置によれば、隣接するパッド電極同 士の周端間の最短距離よりもはんだ微粒子の直径を小さくしたことにより、隣接する 二つのノッド電極上にそれぞれ到達したはんだ微粒子同士の接触を回避できるので 、はんだブリッジの発生をより確実に防止できる。  [0053] According to the method and apparatus for forming solder bumps according to the present invention, the diameter of the solder fine particles is made smaller than the shortest distance between the peripheral ends of adjacent pad electrodes, so that Therefore, it is possible to prevent the solder bridges from being generated more reliably.
[0054] 本発明に係るはんだバンプの形成方法及び装置によれば、不活性気体がはんだ の融点以上に加熱されていることにより、はんだ微粒子を不活性気体中で確実に液 体の状態に保つことができるので、はんだ塗れ性を確実に向上できる。  [0054] According to the solder bump forming method and apparatus of the present invention, the inert gas is heated to the melting point of the solder or higher, so that the solder fine particles are reliably kept in a liquid state in the inert gas. Therefore, solderability can be improved reliably.
[0055] 本発明に係るはんだバンプの形成方法及び装置によれば、はんだ微粒子が固体 のまま噴霧されて不活性気体中で溶融することにより、固体のはんだ微粒子の状態 で保存等が可能となるので、取り扱い性を向上できる。  [0055] According to the method and apparatus for forming a solder bump according to the present invention, the solder fine particles are sprayed in a solid state and melted in an inert gas, so that it can be stored in the state of solid solder fine particles. Therefore, the handleability can be improved.
[0056] 本発明に係るはんだバンプの形成方法及び装置によれば、フラックス作用を有する 液体で被覆された固体のはんだ微粒子を噴霧することにより、当該液体中でのはん だバンプ形成と同程度の品質が得られるにもかかわらず、はんだ微粒子がパッド電 極に到達する時間は液体中に比べて極めて短いことから、はんだバンプの形成に要 する時間を大幅に短縮できる。 [0056] According to the method and apparatus for forming solder bumps according to the present invention, by spraying solid solder fine particles coated with a liquid having a flux action, the same degree as solder bump formation in the liquid. Despite the quality of Since the time to reach the pole is much shorter than in liquid, the time required to form solder bumps can be greatly reduced.
[0057] 本発明に係るはんだバンプの形成方法及び装置によれば、有機皮膜及びフラック ス作用を有する液体で被覆された固体のはんだ微粒子を噴霧することにより、当該 有機皮膜及び当該液体を用いたはんだバンプ形成と同程度の品質が得られるにも かかわらず、はんだ微粒子がパッド電極に到達する時間は液体中に比べて極めて短 いことから、はんだバンプの形成に要する時間を大幅に短縮できる。  [0057] According to the method and apparatus for forming a solder bump according to the present invention, the organic film and the liquid are used by spraying solid solder fine particles coated with the organic film and a liquid having a flux action. Despite the same level of quality as solder bump formation, the time required for solder bump formation can be greatly reduced because the time for solder fine particles to reach the pad electrode is much shorter than in liquid.
[0058] 本発明に係るはんだバンプの形成方法及び装置によれば、基板上に落下したはん だ微粒子をその融点以上に加熱するとともに、この加熱によって液体を蒸発させるこ とにより、液体の蒸発に伴いはんだ微粒子同士が徐々に接近して合一するので、は んだブリッジの発生等を抑制できる。  [0058] According to the method and apparatus for forming a solder bump according to the present invention, the solder fine particles dropped on the substrate are heated to the melting point or higher, and the liquid is evaporated by this heating. As the solder fine particles gradually approach and unite with each other, the occurrence of solder bridges can be suppressed.
[0059] 本発明に係るはんだバンプの形成方法及び装置によれば、はんだ微粒子を噴霧 する際に、不活性気体を大気圧以下に減圧しておくことにより、はんだ微粒子の落下 速度を更に増大できるので、はんだバンプの形成に要する時間を更に短縮できる。 発明を実施するための最良の形態  [0059] According to the method and apparatus for forming a solder bump according to the present invention, when spraying solder fine particles, the falling velocity of the solder fine particles can be further increased by reducing the inert gas to atmospheric pressure or lower. Therefore, the time required for forming the solder bumps can be further shortened. BEST MODE FOR CARRYING OUT THE INVENTION
[0060] 図 1は本発明に係るはんだバンプの形成方法及び装置の第一実施形態を示す概 略構成図であり、図 1 [1]〜図 1 [3]の順に工程が進行する。以下、この図面に基づ き説明する。なお、気体を示す適当な記号がないので、図 1及び図 2では液体の記 号を用 ヽて不活性気体を示すことにする。  FIG. 1 is a schematic configuration diagram showing a first embodiment of a solder bump forming method and apparatus according to the present invention, and the process proceeds in the order of FIG. 1 [1] to FIG. 1 [3]. Hereinafter, description will be made based on this drawing. Since there is no appropriate symbol for indicating gas, in Fig. 1 and Fig. 2, the symbol of liquid is used to indicate inert gas.
[0061] 本実施形態で使用するはんだバンプの形成装置 10について説明する。形成装置 10は、気体槽 11及びはんだ噴霧器 12を備えたものである。気体槽 11は、はんだの 融点以上に加熱された不活性気体 13と、表面 21が上になるように不活性気体 13中 に位置付けられる基板 20とを収容する。はんだ噴霧器 12は、溶融はんだ力も成るは んだ微粒子 14を不活性気体 13中に噴霧するとともに、はんだ微粒子 14を基板 20上 に均等に落下させるための吹き出し管 16を備えている。  A solder bump forming apparatus 10 used in the present embodiment will be described. The forming apparatus 10 includes a gas tank 11 and a solder sprayer 12. The gas tank 11 accommodates an inert gas 13 heated to the melting point of the solder or higher and a substrate 20 positioned in the inert gas 13 so that the surface 21 faces upward. The solder sprayer 12 is provided with a blow pipe 16 for spraying the solder fine particles 14 having a molten solder force into the inert gas 13 and evenly dropping the solder fine particles 14 onto the substrate 20.
[0062] はんだは、例えば、 Sn— Pb (融点 183°C)、 Sn— Ag— Cu (融点 218°C)、 Sn— A g (融点 221°C)、 Sn— Cu (融点 227°C)等を使用する。不活性気体 13は、はんだと 反応しない気体であれば何でもよぐ例えば窒素ガスであるが、アルゴンガスなどでも よい。また、不活性気体 13に水素ガスを混ぜてもよい。なお、不活性気体 13の温度 は、はんだ微粒子 14を液体の状態に保てれば、必ずしもはんだの融点以上にする 必要はない。不活性気体 13は、 100%である必要はなぐはんだ付に悪影響を与え な 、程度の少量の酸素が含まれて 、てもよ 、。 [0062] Solder is, for example, Sn-Pb (melting point 183 ° C), Sn-Ag-Cu (melting point 218 ° C), Sn-Ag (melting point 221 ° C), Sn-Cu (melting point 227 ° C) Etc. The inert gas 13 can be anything as long as it does not react with the solder, for example, nitrogen gas. Good. Further, the inert gas 13 may be mixed with hydrogen gas. The temperature of the inert gas 13 is not necessarily higher than the melting point of the solder as long as the solder fine particles 14 can be kept in a liquid state. The inert gas 13 need not be 100%, but may contain a small amount of oxygen without adversely affecting the soldering.
[0063] 気体槽 11は、例えばステンレスや耐熱性榭脂などカゝら成る容器に、不活性気体 13 をはんだの融点以上 (例えば融点 + 50°C)に保っための図示しない電熱ヒータや冷 却水配管等が設置されたものである。また、気体槽 11内には、基板 20を不活性気体 13中に位置付けるための載置台 17が設けられている。更に、気体槽 11には、不活 性気体 13を気体槽 11内へ導入する導入管 111、及び不活性気体 13を気体槽 11 内から排出する排出管 112が設けられている。なお、載置台 17は、不活性気体 13と 同様にはんだの融点以上に保たれている。  [0063] The gas tank 11 is a container made of, for example, stainless steel or heat-resistant resin, and an electric heater (not shown) or a cooling device for keeping the inert gas 13 at or above the melting point of the solder (for example, a melting point + 50 ° C). Water rejection piping etc. are installed. In the gas tank 11, a mounting table 17 for positioning the substrate 20 in the inert gas 13 is provided. Further, the gas tank 11 is provided with an introduction pipe 111 for introducing the inert gas 13 into the gas tank 11 and a discharge pipe 112 for discharging the inert gas 13 from the gas tank 11. The mounting table 17 is maintained at a temperature equal to or higher than the melting point of the solder, like the inert gas 13.
[0064] はんだ噴霧器 12は、例えば、霧吹きの原理や超音波振動子などを用いて、溶融は んだを不活性気体 13中で霧化することにより、はんだ微粒子 14を形成するものであ る。この場合、気体槽 11の底に沈んだはんだ微粒子 14 (溶融はんだ)及び気体槽 1 1内の不活性気体 13を導入するための配管を、気体槽 11との間に設けてもよい。ま た、はんだ噴霧器 12をフラックスも噴霧できる構成としてもよいし、別〖こフラックス噴霧 器を設けてもよい。吹き出し管 16は、例えば図示しない吹き出し口が基端力も先端ま で多数設けられており、この吹き出し口からはんだ微粒子 14を不活性気体 13中へ 均等に落下させる。これにより、はんだ微粒子 14は、はんだ噴霧器 12から送り出され 、吹き出し管 16から気体槽 11内の不活性気体 13中へ落下する。なお、はんだ微粒 子 14は、不活性気体に混在させて吹き出し管 16から送りだしてもよい。  [0064] The solder sprayer 12 forms solder fine particles 14 by atomizing molten solder in an inert gas 13 using, for example, a spraying principle or an ultrasonic vibrator. . In this case, a pipe for introducing the solder fine particles 14 (molten solder) sinking to the bottom of the gas tank 11 and the inert gas 13 in the gas tank 11 may be provided between the gas tank 11. Further, the solder sprayer 12 may be configured to spray the flux, or a separate flux sprayer may be provided. For example, the blow-out pipe 16 has a large number of blow-out openings (not shown) up to the tip, and the solder fine particles 14 are evenly dropped into the inert gas 13 from the blow-out openings. Thereby, the solder fine particles 14 are sent out from the solder sprayer 12 and fall into the inert gas 13 in the gas tank 11 from the blowing pipe 16. The solder fine particles 14 may be mixed with an inert gas and sent out from the blowing pipe 16.
[0065] 図 2は図 1の部分拡大断面図であり、図 2[1]〜図 2[3]はそれぞれ図 1 [1]〜図 1 [ 3]に対応する。以下、これらの図面に基づき説明する。ただし、図 1と同じ部分は同 じ符号を付すことにより説明を省略する。なお、図 2において、上下方向は左右方向 よりも拡大して示している。  FIG. 2 is a partially enlarged cross-sectional view of FIG. 1, and FIGS. 2 [1] to 2 [3] correspond to FIGS. 1 [1] to 1 [3], respectively. Hereinafter, description will be given based on these drawings. However, the same parts as those in FIG. In FIG. 2, the up-down direction is shown larger than the left-right direction.
[0066] まず、本実施形態で使用する基板 20について説明する。基板 20はシリコンウェハ である。基板 20の表面 21には、パッド電極 22が形成されている。パッド電極 22上に は、本実施形態の形成方法によってはんだバンプ 23が形成される。基板 20は、はん だバンプ 23を介して、他の半導体チップや配線板に電気的及び機械的に接続され る。パッド電極 22は、形状が例えば円であり、直径 cが例えば 40 mである。隣接す るパッド電極 22の中心間の距離 dは、例えば 80 mである。はんだ微粒子 14の直径 bは、例えば 1〜15 μ mである。 [0066] First, the substrate 20 used in the present embodiment will be described. The substrate 20 is a silicon wafer. A pad electrode 22 is formed on the surface 21 of the substrate 20. Solder bumps 23 are formed on the pad electrodes 22 by the forming method of the present embodiment. Board 20 is solder The bumps 23 are electrically and mechanically connected to other semiconductor chips and wiring boards. The pad electrode 22 has a circular shape, for example, and a diameter c of, for example, 40 m. The distance d between the centers of the adjacent pad electrodes 22 is, for example, 80 m. The diameter b of the solder fine particles 14 is, for example, 1 to 15 μm.
[0067] パッド電極 22は、基板 20上に形成されたアルミニウム電極 24と、アルミニウム電極 24上に形成されたニッケル層 25と、ニッケル層 25上に形成された金層 26とから成る 。 -ッケノレ層 25及び金層 26は UBM (under barrier metal又は under bump metallurg y)層である。基板 20上のパッド電極 22以外の部分は、保護膜 27で覆われている。  The pad electrode 22 includes an aluminum electrode 24 formed on the substrate 20, a nickel layer 25 formed on the aluminum electrode 24, and a gold layer 26 formed on the nickel layer 25. -The Keckenore layer 25 and the gold layer 26 are UBM (under barrier metal or under bump metallurgy) layers. Portions other than the pad electrode 22 on the substrate 20 are covered with a protective film 27.
[0068] 次に、パッド電極 22の形成方法について説明する。まず、基板 20上にアルミニウム 電極 24を形成し、アルミニウム電極 24以外の部分にポリイミド榭脂によって保護膜 2 7を形成する。これらは、例えばフォトリソグラフィ技術及びエッチング技術を用いて形 成される。続いて、アルミニウム電極 24表面にジンケート処理を施した後に、無電解 めっき法を用いてアルミニウム電極 24上にニッケル層 25及び金層 26を形成する。こ の UBM層を設ける理由は、アルミニウム電極 24にはんだ濡れ性を付与するためで ある。  Next, a method for forming the pad electrode 22 will be described. First, the aluminum electrode 24 is formed on the substrate 20, and the protective film 27 is formed on the portion other than the aluminum electrode 24 by polyimide resin. These are formed using, for example, a photolithography technique and an etching technique. Subsequently, after the surface of the aluminum electrode 24 is subjected to a zincate treatment, a nickel layer 25 and a gold layer 26 are formed on the aluminum electrode 24 using an electroless plating method. The reason for providing this UBM layer is to provide solder wettability to the aluminum electrode 24.
[0069] 次に、図 1及び図 2に基づき、本実施形態のはんだバンプの形成方法及び装置に ついて、作用及び効果を説明する。  Next, based on FIGS. 1 and 2, the operation and effect of the solder bump forming method and apparatus of this embodiment will be described.
[0070] まず、図 1 [1]及び図 2[1]に示すように、気体槽 11内の不活性気体 13中に、基板 20を表面 21が上になるように位置付ける。基板 20の表面 21には、パッド電極 22が 形成されている。不活性気体 13ははんだの融点以上に加熱されている。このとき、パ ッド電極 22の表面に、フラックスを塗布してお!、てもよ!/、。  First, as shown in FIG. 1 [1] and FIG. 2 [1], the substrate 20 is positioned in the inert gas 13 in the gas tank 11 so that the surface 21 faces upward. A pad electrode 22 is formed on the surface 21 of the substrate 20. The inert gas 13 is heated above the melting point of the solder. At this time, apply flux to the surface of the pad electrode 22!
[0071] 続いて、図 1 [2]及び図 2[2]に示すように、はんだ噴霧器 12からはんだ微粒子 14 を含む不活性気体 13を吹き出し管 16へ送り出し、はんだ微粒子 14を吹き出し管 16 力も不活性気体 13中の基板 20上へ落下させる。はんだ微粒子を噴霧する際にフラ ックスをはんだ微粒子 14と共に、或いははんだ微粒子 14を噴霧する前に、或いはは んだ微粒子 14を噴霧した直後に噴霧する。また、不活性気体中 13中に水素ガスを 混合してもよい。はんだ微粒を噴霧するとき、はんだ微粒子 14は液体中ではなく気 体中を落下することにより、前述の式《3》における粘性係数 kが極めて小さくなるため 、はんだ微粒子 14の落下速度は大きい。すなわち、はんだ微粒子 14が小さくてもす ぐに落下して基板 20に到達するので、はんだバンプ 23の形成に要する時間も短 、。 [0071] Subsequently, as shown in FIG. 1 [2] and FIG. 2 [2], the inert gas 13 containing the solder fine particles 14 is sent from the solder sprayer 12 to the blowing pipe 16, and the solder fine particles 14 are also fed into the blowing pipe 16 by force. Drop onto substrate 20 in inert gas 13. When spraying the solder fine particles, the flux is sprayed together with the solder fine particles 14, before spraying the solder fine particles 14, or immediately after the solder fine particles 14 are sprayed. Further, hydrogen gas may be mixed in the inert gas 13. When the solder fine particles are sprayed, the solder fine particles 14 fall in the gas instead of in the liquid, so that the viscosity coefficient k in the above-mentioned equation << 3 >> becomes extremely small. The falling speed of the solder fine particles 14 is large. That is, even if the solder fine particles 14 are small, they quickly fall and reach the substrate 20, so that the time required for forming the solder bumps 23 is short.
[0072] 不活性気体 13中において、基板 20はパッド電極 22側を上にして保持されている。 In the inert gas 13, the substrate 20 is held with the pad electrode 22 side facing up.
このとき、基板 20上の不活性気体 13中にはんだ微粒子 14を噴霧すると、はんだ微 粒子 14は重力によって自然落下し基板 20上に到達する。基板 20のパッド電極 22 上に到達した複数のはんだ微粒子 14は、重力によってそこに留まり、フラックスの作 用により表面の酸ィ匕膜が除去され、はんだ濡れ時間が経過すると、互いに合一して ノッド電極 22表面にはんだ皮膜 23'を形成する。続いて、そのはんだ皮膜 23'上に 到達したはんだ微粒子 14は、重力によってそこに留まり、同じようにフラックスの作用 により表面の酸ィ匕膜が除去され、はんだ濡れ時間が経過すると、前記はんだ皮膜 23 'に取込まれ、はんだ皮膜 23'が厚くなる。これが繰り返されて、はんだ皮膜 23'が成 長してはんだバンプ 23となる（図 1 [3]及び図 2[3])。その後、はんだバンプ 23にな らな力つた不要なはんだ微粒子 14 (図 2[3])を、洗浄等により基板 20上力も除去す る。  At this time, when the solder fine particles 14 are sprayed into the inert gas 13 on the substrate 20, the solder fine particles 14 spontaneously drop by gravity and reach the substrate 20. The plurality of solder fine particles 14 that have reached the pad electrode 22 of the substrate 20 stay there due to gravity, and the surface oxide film is removed by the action of the flux. A solder film 23 ′ is formed on the surface of the nod electrode 22. Subsequently, the solder fine particles 14 that have reached the solder film 23 'remain there due to gravity, and in the same way, the surface oxide film is removed by the action of the flux, and when the solder wetting time elapses, the solder film 14' 23 'is taken in, and the solder film 23' becomes thick. This process is repeated, and the solder film 23 'grows into solder bumps 23 (Fig. 1 [3] and Fig. 2 [3]). Thereafter, unnecessary solder fine particles 14 (FIG. 2 [3]) having a sufficient force on the solder bump 23 are also removed by cleaning or the like.
[0073] はんだ濡れ時間とは、はんだ微粒子 14とパッド電極 22又ははんだ皮膜 23'とが接 する時間であって、はんだが濡れるために必要な時間（例えば数秒〜数十秒)である 。本実施形態では、はんだ微粒子 14が落下してパッド電極 22又ははんだ皮膜 23' に到達すると、はんだ微粒子 14は重力の作用によってそこに留まる。そのため、はん だ微粒子 14とパッド電極 22又ははんだ皮膜 23'とは、はんだ濡れ時間が経過するま で接すること〖こなる。したがって、はんだ濡れ性は良好である。  [0073] The solder wetting time is a time for which the solder fine particles 14 are in contact with the pad electrode 22 or the solder film 23 'and is a time necessary for the solder to get wet (for example, several seconds to several tens of seconds). In the present embodiment, when the solder fine particles 14 fall and reach the pad electrode 22 or the solder coating 23 ', the solder fine particles 14 remain there due to the action of gravity. Therefore, the solder fine particles 14 and the pad electrode 22 or the solder film 23 ′ are in contact with each other until the solder wetting time elapses. Therefore, the solder wettability is good.
[0074] また、本発明者は、不活性気体 13中ではんだ微粒子 14同士が落下中に接触して も、これらが合体して大きいはんだ微粒子になるものは少ない、ということも見出した。 したがって、ファインピッチのパッド電極 22に対しても、はんだブリッジ等が発生しな い。特に、隣接するパッド電極 22同士の周端間の最短距離 aよりも、はんだ微粒子 1 4の直径 bを小さくするとよい。この場合、隣接する二つのパッド電極 22上にそれぞれ 到達したはんだ微粒子 14同士は、接触しな 、ため合体してはんだブリッジを形成す ることがない。  [0074] Further, the present inventor has also found that even when the solder fine particles 14 come into contact with each other during the fall in the inert gas 13, there are few that combine to become large solder fine particles. Therefore, no solder bridge or the like is generated on the fine pitch pad electrode 22. In particular, the diameter b of the solder fine particles 14 is preferably smaller than the shortest distance a between the peripheral ends of the adjacent pad electrodes 22. In this case, the solder fine particles 14 that have reached the two adjacent pad electrodes 22 do not come into contact with each other, so that they do not merge to form a solder bridge.
[0075] 更に、はんだバンプ 23のはんだ量は、はんだ噴霧器 12によってはんだ微粒子 14 の供給量を変えることにより容易に調整できる。し力も、はんだ微粒子 14は、パッド電 極 22に比べて極めて小さいことにより多量に供給されるので、不活性気体 13中に均 一に分散する。したがって、はんだバンプ 23のはんだ量のバラツキも少ない。 Further, the solder amount of the solder bump 23 is determined by the solder sprayer 12 using the solder fine particles 14. It can be easily adjusted by changing the supply amount. Since the solder fine particles 14 are supplied in a large amount because they are extremely small compared to the pad electrode 22, they are uniformly dispersed in the inert gas 13. Therefore, the solder bump 23 has little variation in the amount of solder.
[0076] なお、本発明は、言うまでもないが、上記実施形態に限定されるものではない。例 えば、はんだ微粒子をパッド電極に向けて噴霧するのであれば、不活性気体中にお いて基板の表面は必ずしも上にする必要はなく横でも下でも斜めでもよい。また、シリ コンウェハ (FC)の代わりに、配線板 (BGA)を用いてもよい。更に、はんだ微粒子を 固体のまま噴霧し、そのはんだ微粒子を不活性気体中で溶融してもよい。  [0076] Needless to say, the present invention is not limited to the above embodiment. For example, if the solder fine particles are sprayed toward the pad electrode, the surface of the substrate does not necessarily have to be up in an inert gas, and may be horizontal, down, or diagonal. A wiring board (BGA) may be used instead of the silicon wafer (FC). Further, the solder fine particles may be sprayed in a solid state, and the solder fine particles may be melted in an inert gas.
[0077] 図 3乃至図 6は、本発明に係るはんだバンプの形成方法及び装置の第二実施形態 を示す。以下、これらの図面に基づき説明する。ただし、本実施形態について、第一 実施形態と同じ部分は同じ符号を付すことにより説明を省略する。  3 to 6 show a second embodiment of a solder bump forming method and apparatus according to the present invention. Hereinafter, description will be given based on these drawings. However, about this embodiment, the same part as 1st embodiment attaches | subjects the same code | symbol, and abbreviate | omits description.
[0078] 図 3は [1]は、本実施形態で用いるはんだ微粒子の第一例を示す拡大断面図であ る。本実施形態で噴霧されるはんだ微粒子 14は、固体のはんだカゝら成るとともに、フ ラックス作用を有する液体 31で表面が被覆されている。ここに、フラックス作用を有す る液体 31とは、液体 31中にフラックス作用を有する成分が含まれて 、ることを意味す る。液体 31の主成分は、揮発性を有する液体、例えば炭化水素類、エステル類、ァ ルコール類、グリコール類などが好ましい。フラックス作用を有する成分としては、例 えば酸、有機酸金属塩などが用いられる。酸ははんだ粒子の合一を促進する。酸は 、例えばカルボン酸などの有機酸、塩酸などの無機酸、ロジンなどである。カルボン 酸は、例えば蟻酸、ォレイン酸、ステアリン酸、蓚酸などである。ロジンは、例えば L— ァビエチン酸、ロジン、水添ロジン等のロジン誘導体などである。有機酸金属塩は、 例えば酸とはんだ微粒子 14を構成する少なくとも一つの金属元素とからなるものであ る。有機酸金属塩は、その有機酸がフラックス作用を促進し、金属塩が溶融したはん だと反応して析出して有機皮膜となりはんだ微粒子の合一を抑制する。本実施形態 では、液体 31の主成分がイソプロピルアルコールであり、フラックス作用を有する成 分が有機酸であるとする。  FIG. 3 is an enlarged cross-sectional view showing a first example of solder fine particles used in the present embodiment. The solder fine particles 14 sprayed in the present embodiment are made of solid solder powder and the surface thereof is coated with a liquid 31 having a flux action. Here, the liquid 31 having a flux action means that the liquid 31 contains a component having a flux action. The main component of the liquid 31 is preferably a volatile liquid such as hydrocarbons, esters, alcohols, glycols and the like. For example, an acid or an organic acid metal salt is used as the component having a flux action. The acid promotes coalescence of the solder particles. Examples of the acid include organic acids such as carboxylic acid, inorganic acids such as hydrochloric acid, and rosin. Examples of the carboxylic acid include formic acid, oleic acid, stearic acid, and succinic acid. Examples of the rosin include rosin derivatives such as L-abietic acid, rosin, and hydrogenated rosin. The organic acid metal salt is composed of, for example, an acid and at least one metal element constituting the solder fine particles 14. The organic acid metal salt promotes the flux action, reacts with the molten metal salt, precipitates into an organic film, and suppresses the coalescence of solder fine particles. In the present embodiment, it is assumed that the main component of the liquid 31 is isopropyl alcohol, and the component having a flux action is an organic acid.
[0079] 以上のように、はんだ微粒子 14力 フラックス成分を含む液体 31により被覆されて いると、はんだ微粒子 14を気体槽 11内に送りだす際に、別途フラックスを噴霧する 必要がなくなる。なお、液体 31に含まれるフラックス成分だけでは不足が生じた場合 に、別途フラックスを供給するようにしてもょ 、ものである。 [0079] As described above, when the solder fine particles 14 are coated with the liquid 31 containing the flux component, when the solder fine particles 14 are fed into the gas tank 11, the flux is separately sprayed. There is no need. It is also possible to supply the flux separately when the flux component contained in the liquid 31 is insufficient.
[0080] 図 4及び図 6は第二実施形態におけるはんだバンプの形成工程を示し、図 4及び 図 5は概略構成図であり、図 6は部分拡大断面図である。図 4[1]〜図 6 [3]の順に 工程が進行する。以下、図 3乃至図 6に基づき、本実施形態のはんだバンプの形成 方法及び装置について、作用及び効果を説明する。 4 and 6 show a solder bump forming process in the second embodiment, FIG. 4 and FIG. 5 are schematic configuration diagrams, and FIG. 6 is a partially enlarged sectional view. The process proceeds in the order of Fig. 4 [1] to Fig. 6 [3]. Hereinafter, based on FIG. 3 thru | or FIG. 6, the effect | action and effect are demonstrated about the formation method and apparatus of the solder bump of this embodiment.
[0081] 本実施形態のはんだバンプの形成装置 30は、加熱手段としてのヒータ 32を備えて いる。ヒータ 32は、気体槽 11の底面から基板 20を加熱する。はんだ噴霧器は、図示 を略すが、第一実施形態と同じものでよい。なお、基板 20の載置台等は図示を略し ている。 The solder bump forming apparatus 30 of this embodiment includes a heater 32 as a heating means. The heater 32 heats the substrate 20 from the bottom surface of the gas tank 11. Although not shown, the solder sprayer may be the same as that of the first embodiment. The mounting table for the substrate 20 is not shown.
[0082] まず、気体槽 11内の不活性気体 13中に、パッド電極 22を上にして基板 20を位置 付ける。そして、液体 31と固体のはんだ微粒子 14とが混合されて成るはんだ組成物 を、吹き出し管 16から不活性気体 13中へ噴霧する（図 4[1])。  First, the substrate 20 is positioned in the inert gas 13 in the gas tank 11 with the pad electrode 22 facing up. Then, a solder composition in which the liquid 31 and the solid solder fine particles 14 are mixed is sprayed into the inert gas 13 from the blowing pipe 16 (FIG. 4 [1]).
[0083] これにより、図 3 [1]に示した液体 31によって被覆されたはんだ微粒子 14力 不活 性気体 13中の基板 20上へ落下する。つまり、はんだ微粒子 14は重力によって自然 落下し基板 20上に到達する（図 4[2])。このとき、はんだ微粒子 14の落下速度は、 気体中での落下であるから、液体中での落下速度に比べて極めて大きい。したがつ て、はんだ微粒子 14が小さくてもすぐに落下して基板 20に到達するので、はんだバ ンプ 23の形成に要する時間も短い。  As a result, the solder fine particles 14 are coated with the liquid 31 shown in FIG. 3 [1] and drop onto the substrate 20 in the inert gas 13. In other words, the solder fine particles 14 naturally fall by gravity and reach the substrate 20 (FIG. 4 [2]). At this time, since the falling speed of the solder fine particles 14 is falling in the gas, it is much higher than the falling speed in the liquid. Therefore, even if the solder fine particles 14 are small, they quickly fall and reach the substrate 20, so that the time required for forming the solder bumps 23 is short.
[0084] そして、基板 20をヒータ 32で加熱すると、はんだ微粒子 14を覆っていた液体 31の 粘性が低下することにより、液体 31がはんだ微粒子 14から離れて気体槽 11の底に 溜まる。また、液体 31のみ力も成る微粒子が噴霧されて気体槽 11の底に溜まる場合 もある。その結果、基板 20全体が液体 31中に浸漬された状態となる（図 5 [1])。  Then, when the substrate 20 is heated by the heater 32, the viscosity of the liquid 31 that has covered the solder fine particles 14 decreases, so that the liquid 31 separates from the solder fine particles 14 and accumulates at the bottom of the gas tank 11. In addition, there are cases where fine particles having a force only in the liquid 31 are sprayed and collected at the bottom of the gas tank 11. As a result, the entire substrate 20 is immersed in the liquid 31 (FIG. 5 [1]).
[0085] 続いて、基板 20をヒータ 32で更に加熱すると、はんだ微粒子 14が融点以上になつ て溶融するとともに、液体 31が蒸発し始める。液体 31の蒸発に伴い、溶融したはん だ微粒子 14同士が徐々に接近して合一することにより、はんだバンプ 23が形成され る（図 5 [2]及び図 6 [1]〜[3])。そのため、はんだ微粒子 14の不要な合一が発生し にく!/、ので、はんだブリッジの発生等が抑制される。 [0086] このとき、液体 31に含まれる有機酸の作用によって、次のような状態が引き起こされ る。まず、はんだ微粒子 14同士は合一が抑えられる。ただし、図 6 [2]では図示して いないが、一部のはんだ微粒子 14同士は合一して大きくなる。つまり、はんだ微粒子 14同士は合一しても一定の大きさ以下であれば問題ない。一方、はんだ微粒子 14 は、パッド電極 22上に広がって界面に合金層を形成する。その結果、パッド電極 22 上にはんだ皮膜 23'が形成され、はんだ皮膜 23'に更にはんだ微粒子 14が合一す る。すなわち、はんだ皮膜 23'は成長して、図 6 [3]に示すようなはんだバンプ 23とな る。なお、図 6 [3]において、はんだバンプ 23の形成に使用されなかったはんだ微粒 子 14は、液体 31の残渣とともに後工程で洗い落とされる。 [0085] Subsequently, when the substrate 20 is further heated by the heater 32, the solder fine particles 14 are melted to the melting point or higher, and the liquid 31 starts to evaporate. As the liquid 31 evaporates, the solder bumps 23 are formed as the molten solder particles 14 gradually approach and unite (Figs. 5 [2] and 6 [1]-[3] ). Therefore, unnecessary coalescence of the solder fine particles 14 hardly occurs! /, So that the occurrence of solder bridges is suppressed. At this time, the following state is caused by the action of the organic acid contained in the liquid 31. First, the coalescence between the solder fine particles 14 is suppressed. However, although not shown in FIG. 6 [2], some of the solder fine particles 14 become larger together. That is, there is no problem even if the solder fine particles 14 are united with each other as long as they are below a certain size. On the other hand, the solder fine particles 14 spread on the pad electrode 22 and form an alloy layer at the interface. As a result, a solder film 23 ′ is formed on the pad electrode 22, and solder fine particles 14 are further combined with the solder film 23 ′. That is, the solder film 23 'grows to become a solder bump 23 as shown in FIG. 6 [3]. In FIG. 6 [3], the solder fine particles 14 that have not been used for forming the solder bumps 23 are washed away in the subsequent process together with the liquid 31 residue.
[0087] 更に詳しく説明する。はんだ微粒子 14は、表面に自然酸化膜のみを有する。液体 31のフラックス作用は、はんだ微粒子 14の融点以上に加熱された状態で、はんだ微 粒子 14同士の合一を抑制しつつ、はんだ微粒子 14とパッド電極 22とのはんだ付け を促進するとともに、ノッド電極 22上に形成されたはんだ皮膜 23'とはんだ微粒子 1 4との合一を促進するものである。このようなフラックス作用の成分は、本発明者が実 験及び考察を繰り返して発見したものである。  [0087] Further details will be described. The solder fine particles 14 have only a natural oxide film on the surface. The flux action of the liquid 31 promotes the soldering between the solder fine particles 14 and the pad electrode 22 while suppressing the coalescence of the solder fine particles 14 while being heated to the melting point of the solder fine particles 14 or more, and the It promotes coalescence of the solder coating 23 ′ formed on the electrode 22 and the solder fine particles 14. Such a component of flux action has been discovered by the present inventors through repeated experiments and considerations.
[0088] このような成分としては、例えば酸が挙げられる。酸は無機酸 (例えば塩酸）と有機 酸 (例えば脂肪酸)とに大別できるが、ここでは有機酸を例に説明する。  [0088] Examples of such components include acids. Acids can be broadly classified into inorganic acids (for example, hydrochloric acid) and organic acids (for example, fatty acids). Here, organic acids will be described as examples.
[0089] 本発明者は、「有機酸は、はんだ微粒子 14同士を合一させる作用は小さいが、パッ ド電極 22にはんだ濡れを生じさせる作用は大きい。」ということを見出した。このような 作用が生じる理由として、次の（1) , (2)のようなことが考えられる。  The present inventor has found that “the organic acid has a small effect of bringing the solder fine particles 14 together, but has a great effect of causing the solder to wet the pad electrode 22”. The following (1) and (2) can be considered as the reason why such an action occurs.
[0090] (1) .有機酸には、はんだ微粒子 14の酸ィ匕膜を除去する作用が弱い。そのため、 はんだ微粒子 14に故意に酸ィ匕膜を形成しなくても、はんだ微粒子 14の自然酸化膜 によって、はんだ微粒子 14同士の合一を抑えることができる。  [0090] (1) The organic acid has a weak effect of removing the acid film of the solder fine particles 14. For this reason, the coalescence of the solder fine particles 14 can be suppressed by the natural oxide film of the solder fine particles 14 without intentionally forming an oxide film on the solder fine particles 14.
[0091] (2) .有機酸は、何らかの理由によって、はんだ微粒子 14をパッド電極 22に広げて 界面を合金化するとともに、ノッド電極 22上に形成されたはんだ皮膜 23'にはんだ 微粒子 14を合一させる作用がある。はんだ微粒子 14同士はほとんど合一しないにも かかわらず、パッド電極 22上ではんだ濡れが生ずるメカニズムは定かではない。推 測として、はんだ微粒子 14とパッド電極 22との間で、僅かな酸ィ匕膜を打ち破る何らか の反応が起こっていると考えられる。例えば、金メッキされたパッド電極 22であれば、 金のはんだ中への拡散効果により、はんだ微粒子 14に例え薄い酸ィ匕膜があつたとし てもはんだ濡れが生ずる。銅力もなるパッド電極 22の場合は、銅が有機酸と反応して 有機酸銅塩となり、その有機酸銅塩がはんだと接触することによりイオン化傾向の差 から還元され、金属銅がはんだ中に拡散してはんだ濡れが進行する。パッド電極 22 上に形成されたはんだ皮膜 23'にはんだ微粒子 14が合一する理由については、例 えば表面張力が考えられる。 [0091] (2) For some reason, the organic acid spreads the solder fine particles 14 to the pad electrode 22 to alloy the interface, and combines the solder fine particles 14 with the solder film 23 'formed on the nod electrode 22. There is an action to make it. Despite the fact that the solder fine particles 14 hardly merge with each other, the mechanism of solder wetting on the pad electrode 22 is not clear. As a presumption, there is something that breaks a little oxide film between the solder fine particles 14 and the pad electrode 22. It is thought that this reaction is occurring. For example, in the case of the gold-plated pad electrode 22, the solder wets due to the diffusion effect of gold into the solder even if the solder fine particles 14 have a thin oxide film. In the case of the pad electrode 22 that also has copper power, copper reacts with an organic acid to form an organic acid copper salt, and the organic acid copper salt is reduced by the difference in ionization tendency by contacting with the solder, and the metallic copper is contained in the solder. Diffusion and solder wetting progress. The reason why the solder fine particles 14 are united with the solder film 23 ′ formed on the pad electrode 22 is, for example, surface tension.
[0092] 次に、本実施形態で用いるはんだ微粒子の第二例について説明する。図 3 [2]に 示すように、有機皮膜 33ではんだ微粒子 14を被覆し、更にフラックス作用を有する 液体 31ではんだ微粒子 14を被覆し、この状態ではんだ微粒子 14を噴霧してもょ ヽ 。はんだ微粒子 14を有機皮膜 33で被覆する方法としては、加熱した油状液体の分 散媒中ではんだを溶融し、これを撹拌して液滴の微粒子を形成し、これを冷却固化さ せて球状のはんだ粒子を得る、油中アトマイズ法が挙げられる。その一例を述べる。 まず、容器に入った精製ひまし油 900g中に、錫銀銅はんだを 90g、マレイン酸変性 ロジンを 18g加える。錫銀銅はんだは、組成が Sn 3.0mass%Ag 0.5mass%Cuの鉛 フリーはんだであり、融点が 220°Cである。そして、この精製ひまし油を 230°Cに加熱 して撹拌機を 10,000rpmで回転させることにより、精製ひまし油中ではんだ合金を破 砕する。これにより、はんだ微粒子 14表面にマレイン酸変性ロジンの有機皮膜 33が 付いたはんだ粉末を得る。なお、撹拌中は容器内を窒素雰囲気に置換する。また、 はんだ粉末は、容器の上澄みを除いた後に酢酸ェチルによって洗浄し、これを真空 乾燥する。 Next, a second example of solder fine particles used in the present embodiment will be described. As shown in Fig. 3 [2], the solder fine particles 14 are coated with the organic film 33, and the solder fine particles 14 are further coated with the liquid 31 having a flux action, and the solder fine particles 14 are sprayed in this state. As a method of coating the solder fine particles 14 with the organic film 33, the solder is melted in a dispersion medium of a heated oily liquid, and this is stirred to form droplet fine particles, which are cooled and solidified to form a spherical shape. An oil-in-atomization method that obtains solder particles of the above may be mentioned. An example is described. First, 90 g of tin-silver-copper solder and 18 g of maleic acid-modified rosin are added to 900 g of purified castor oil in a container. Tin-silver-copper solder is a lead-free solder with a composition of Sn 3.0 mass% Ag 0.5 mass% Cu and a melting point of 220 ° C. The refined castor oil is heated to 230 ° C and the stirrer is rotated at 10,000 rpm to break the solder alloy in the refined castor oil. As a result, a solder powder having the surface of the solder fine particles 14 with the organic coating 33 of maleic acid-modified rosin is obtained. During stirring, the inside of the container is replaced with a nitrogen atmosphere. Solder powder is washed with ethyl acetate after removing the supernatant of the container and dried in vacuum.
[0093] ここで、有機皮膜 33で被覆されたはんだ微粒子 14を、図 6 [1]〜[3]と同じ状態で 加熱したとする。各はんだ微粒子 14は、ほぼ球状であり、直径も均一である。ここで、 はんだ微粒子 14及び液体 31をはんだ微粒子 14の融点以上に加熱すると、 n個のは んだ微粒子 14が合一して、体積及び有機皮膜量が n倍、表面積が n /3倍となる。そ のため、 n個のはんだ微粒子 14が合一した新たなはんだ微粒子 14は、単位表面積 当たりの有機皮膜量が n1/3倍となる。すなわち、はんだ微粒子 14の合一が進むほど、 単位表面積当たりの有機皮膜量が増加する。例えば、 8個のはんだ微粒子 14が合 一すると、体積及び有機皮膜量が 8倍、表面積が 4倍、単位表面積当たりの有機皮 膜量が 2倍となる。また、単位表面積当たりの有機皮膜量が増えるほど、有機皮膜 33 下のはんだ微粒子 14同士の接触が難しくなるので、はんだ粒子の合一が抑制される Here, it is assumed that the solder fine particles 14 coated with the organic film 33 are heated in the same state as in FIGS. 6 [1] to [3]. Each solder fine particle 14 is substantially spherical and has a uniform diameter. Here, when the solder fine particles 14 and the liquid 31 are heated to the melting point of the solder fine particles 14 or more, n pieces of the fine particles 14 are united, and the volume and the amount of the organic film are n times and the surface area is n / 3 times. Become. Therefore, the new solder fine particles 14 in which n solder fine particles 14 are united have an organic film amount per unit surface area n 1/3 times. That is, as the coalescence of the solder fine particles 14 progresses, the amount of the organic film per unit surface area increases. For example, eight solder fine particles 14 As a result, the volume and the amount of organic film are 8 times, the surface area is 4 times, and the amount of organic film per unit surface area is doubled. Also, as the amount of organic film per unit surface area increases, it becomes more difficult for the solder particles 14 under the organic film 33 to contact each other, so coalescence of solder particles is suppressed.
[0094] 一方、ノッド電極 22上のはんだ皮膜 23'は、はんだ微粒子 14がはんだ皮膜 31に 合一することによって成長する。そのため、パッド電極 22上ではんだ微粒子 14の合 一が進むにつれて、はんだ皮膜 23'の単位表面積当たりの有機皮膜量が一定に達 すると、はんだ皮膜 23'の成長が停止する。つまり、はんだ皮膜 23'の最終的なはん だ量は、ノッド電極 22の大きさに加え最初のはんだ微粒子 14の大きさ及び有機皮 膜量によって決まる。なお、単位表面積当たりの有機皮膜量が一定に達したはんだ 微粒子 14も、はんだ皮膜 23'に合一することはない。 On the other hand, the solder film 23 ′ on the nod electrode 22 grows when the solder fine particles 14 merge with the solder film 31. Therefore, as the coalescence of the solder fine particles 14 progresses on the pad electrode 22, the growth of the solder film 23 ′ stops when the amount of the organic film per unit surface area of the solder film 23 ′ reaches a constant value. That is, the final solder amount of the solder film 23 ′ is determined by the size of the first solder fine particles 14 and the amount of the organic film in addition to the size of the nod electrode 22. It should be noted that the solder fine particles 14 whose amount of organic film per unit surface area has reached a constant value do not merge with the solder film 23 '.
[0095] これにより、はんだ微粒子 14がパッド電極 22上で必要以上に合一することを抑制 できるので、はんだバンプ 23のはんだ量を均一化できるとともに、パッド電極 22のシ ョート不良を防止できる。例えば、最初のはんだ微粒子 14の有機皮膜量は、はんだ 皮膜 23 'へのはんだ微粒子 14の合一を、はんだ皮膜 23'が一定のはんだ量になる までは許容し一定のはんだ量を越えると抑制するように、設定されている。  Accordingly, it is possible to prevent the solder fine particles 14 from being unnecessarily united on the pad electrode 22, so that the solder amount of the solder bump 23 can be made uniform and a short circuit failure of the pad electrode 22 can be prevented. For example, the amount of the organic film of the first solder fine particle 14 allows the coalescence of the solder fine particle 14 to the solder film 23 ′ until the solder film 23 ′ reaches a certain amount of solder and is suppressed when the certain amount of solder is exceeded. Is set to do.
[0096] 次に、所望のはんだバンプ 23の高さを得るための、はんだ微粒子 14及びその有機 皮膜 33の量の設計方法にっ 、て説明する。  Next, a method for designing the amount of the solder fine particles 14 and the organic film 33 in order to obtain a desired height of the solder bump 23 will be described.
[0097] はんだ微粒子 14について、体積を VI、有機皮膜量を F1とする。はんだ微粒子 14 の形状は球形である。はんだバンプ 23について、体積を V2、有機皮膜量を F2、表 面積を S 2とする。パッド電極 22の面積を SOとする。はんだバンプ 23の表面積とパッ ド電極 22の面積との関係を示す補正係数を Aとする。単位表面積当たりの最大の有 機皮膜量を Fmaxとする。  [0097] For the solder fine particles 14, the volume is VI and the amount of the organic film is F1. The shape of the solder fine particles 14 is spherical. For solder bump 23, the volume is V2, the organic coating amount is F2, and the surface area is S2. The area of the pad electrode 22 is SO. A is a correction coefficient indicating the relationship between the surface area of the solder bump 23 and the area of the pad electrode 22. Let Fmax be the maximum amount of organic coating per unit surface area.
[0098] このとき、以下の関係が成り立つ。  At this time, the following relationship is established.
F2= (V2/V1) X F1 · · · (1)  F2 = (V2 / V1) X F1 (1)
Fmax=F2/S2 · · · (2)  Fmax = F2 / S2 (2)
S2=A X S0 · · · (3)  S2 = A X S0 (3)
式（3)を式（2)に代入することにより、次式を得る。 Fmax=F2/ (AX SO) By substituting equation (3) into equation (2), the following equation is obtained. Fmax = F2 / (AX SO)
.'.F2=Fmax XAX S0 …（4)  . '. F2 = Fmax XAX S0… (4)
続いて、式 (4)を式（1)に代入することにより、次式を得る。  Subsequently, the following equation is obtained by substituting equation (4) into equation (1).
FmaxXA X S0= (V2/Vl) X F1 · · · (5)  FmaxXA X S0 = (V2 / Vl) X F1 (5)
Fl = (V1/V2) X Fmax X A X SO · · · (6)  Fl = (V1 / V2) X Fmax X A X SO (6)
ここで、所望のはんだバンプ 23の高さに対応して V2が決まり， VI, Fmax, A, SO も既に決まっていれば、式（6)から F1が求められる。  Here, if V2 is determined corresponding to the desired height of the solder bump 23 and VI, Fmax, A, and SO are already determined, F1 is obtained from equation (6).
また、はんだ微粒子 14の大きさ（すなわち VI)が決まっていなければ、式（5)から 得られる次式の、  If the size of the solder fine particles 14 (ie VI) is not determined, the following equation obtained from equation (5)
F1/V1 = (1/V2) X Fmax X AX SO · · · (7)  F1 / V1 = (1 / V2) X Fmax X AX SO (7)
の関係を満たす Fl, VIが求められる。  Fl and VI satisfying the above relationship are required.
[0099] なお、式（3)にお!/、て、補正係数 Aは、はんだバンプ 23の体積、パッド電極 22の形 状、溶融はんだの表面張力などによって異なる値をとる。例えば、はんだバンプ 23の 体積が大きいほど、はんだバンプ 23の表面積が大きくなるので、 Aも大きい値となる 。ノ¾ /ド電極 22の形状が円形よりも四角形の方力 球面になりにくいことにより表面積 が大きくなるので、 Aも大きい値となる。溶融はんだの表面張力が小さい方が、球面 になりにくいことにより表面積が大きくなるので、 Aも大きい値となる。実際の補正係数 Aは、実験的に求められる。 [0099] In equation (3),! /, The correction coefficient A varies depending on the volume of the solder bump 23, the shape of the pad electrode 22, the surface tension of the molten solder, and the like. For example, since the surface area of the solder bump 23 increases as the volume of the solder bump 23 increases, A also increases. Since the shape of the anode / node electrode 22 is less likely to be a square spherical force than a circle, the surface area is increased, and therefore A is a large value. The smaller the surface tension of the molten solder, the greater the surface area due to the difficulty of becoming a spherical surface, so A is also a large value. The actual correction factor A is obtained experimentally.
[0100] 図 7は本発明に係るはんだバンプの形成方法及び装置の第三実施形態を示す概 略構成図であり、図 7[1]〜図 7[2]の順に工程が進行する。以下、この図面に基づ き説明する。ただし、図 1及び図 4と同じ部分は同じ符号を付すことにより説明を省略 する。 FIG. 7 is a schematic configuration diagram showing a third embodiment of the method and apparatus for forming solder bumps according to the present invention, and the process proceeds in the order of FIG. 7 [1] to FIG. 7 [2]. Hereinafter, description will be made based on this drawing. However, the same parts as those in FIG. 1 and FIG.
[0101] 本実施形態のはんだバンプの形成装置 40は、はんだ微粒子 14を噴霧する際に、 不活性気体 13を大気圧以下に減圧しておく減圧手段を、更に備えたものである。こ の減圧手段は、コントローラ 41の機能の一部、真空ポンプ 42、電磁弁 43, 44等によ つて構成されている。コントローラ 41は、例えばマイクロコンピュータであり、プロダラ ムに従って、真空ポンプ 42及びはんだ噴霧器 12のオン'オフを制御するとともに、電 磁弁 43, 44の開閉を制御する。電磁弁 43は真空ポンプ 42と気体槽 11とを繋ぐ配管 45に設けられ、電磁弁 44ははんだ噴霧器 12と吹き出し管 16とを繋ぐ配管 46に設け られている。 [0101] The solder bump forming apparatus 40 of the present embodiment is further provided with a depressurizing means for depressurizing the inert gas 13 to an atmospheric pressure or lower when the solder fine particles 14 are sprayed. This pressure reducing means is constituted by a part of the function of the controller 41, a vacuum pump 42, electromagnetic valves 43, 44, and the like. The controller 41 is, for example, a microcomputer, and controls on / off of the vacuum pump 42 and the solder sprayer 12 and also controls opening and closing of the electromagnetic valves 43 and 44 according to a program. Solenoid valve 43 is a pipe connecting vacuum pump 42 and gas tank 11 The solenoid valve 44 is provided in a pipe 46 that connects the solder sprayer 12 and the blowing pipe 16.
[0102] コントローラ 41は、例えば次のように動作する。まず、真空ポンプ 42をオン、電磁弁 43を開、はんだ噴霧器 12をオフ、電磁弁 44を閉とすることにより、気体槽 11内の不 活性気体 13を減圧する（図 7[1])。一定時間が経過するか又は不活性気体 13の圧 力が一定以下になると、真空ポンプ 42をオフ、電磁弁 43を閉、はんだ噴霧器 12をォ ン、電磁弁 44を開とすることにより、はんだ微粒子 14を気体槽 11内へ噴霧する（図 7 [2])。  [0102] The controller 41 operates as follows, for example. First, the inert gas 13 in the gas tank 11 is decompressed by turning on the vacuum pump 42, opening the solenoid valve 43, turning off the solder sprayer 12, and closing the solenoid valve 44 (FIG. 7 [1]). When a certain time elapses or the pressure of the inert gas 13 falls below a certain level, the vacuum pump 42 is turned off, the solenoid valve 43 is closed, the solder sprayer 12 is turned on, and the solenoid valve 44 is opened. Fine particles 14 are sprayed into the gas tank 11 (Fig. 7 [2]).
[0103] 本実施形態によれば、不活性気体 13が減圧されるほど、気体槽 11内の不活性気 体 13中に噴霧されたフラックス或 、は水素ガスに基づく粘性がはんだ微粒子 14に 影響を与えないため、はんだ微粒子 14の落下中の粘性係数 kが小さくなるので、は んだ微粒子 14の落下速度 Vは更に大きくなる。そのため、はんだバンプの形成に要 する時間を更に短縮できる。  According to the present embodiment, the flux based on the inert gas 13 in the gas tank 11 or the viscosity based on the hydrogen gas affects the solder fine particles 14 as the inert gas 13 is depressurized. Since the viscosity coefficient k during the dropping of the solder fine particles 14 becomes small, the falling velocity V of the solder fine particles 14 becomes further larger. Therefore, the time required for forming the solder bump can be further shortened.
[0104] 次に、図 3 [2]に示すはんだ微粒子 14を使用したはんだバンプの形成方法につい て説明する。  [0104] Next, a method of forming solder bumps using the solder fine particles 14 shown in FIG. 3 [2] will be described.
[0105] 図 3 [2]に示すはんだ微粒子 14は上述したように、その表面が有機皮膜 33にて被 覆されており、有機皮膜 33の表面は、フラックス成分を含む液体 31により被覆されて いる。なお、液体 31は、フラック材そのものであってもよい。以下の実施形態では、液 体 31としてフラックス材を用いた場合にっ 、て説明する。  [0105] As described above, the surface of the solder fine particles 14 shown in Fig. 3 [2] is covered with the organic film 33, and the surface of the organic film 33 is covered with the liquid 31 containing the flux component. Yes. The liquid 31 may be the flack material itself. In the following embodiment, the case where a flux material is used as the liquid 31 will be described.
[0106] 本実施形態に用いるはんだバンプ形成装置は図 8に示す構成に構築されており、 図 8に示すはんだバンプ形成装置は、図 1に示すはんだバンプ形成装置と実質的に 同一の構成として構築されて 、る。  The solder bump forming apparatus used in the present embodiment is constructed as shown in FIG. 8, and the solder bump forming apparatus shown in FIG. 8 has substantially the same configuration as the solder bump forming apparatus shown in FIG. Built.
[0107] 本実施形態で使用するはんだバンプの形成装置 50は、気体槽 11と、不活性気体 供給器 51と、はんだ供給器 52と、フラックス供給器 53と、酸化還元剤供給器 54と、こ れらを制御するコントローラ 55を有して!/、る。  [0107] The solder bump forming apparatus 50 used in the present embodiment includes a gas tank 11, an inert gas supply device 51, a solder supply device 52, a flux supply device 53, a redox agent supply device 54, It has a controller 55 that controls these!
[0108] 気体槽 11は、載置台 17を備えている。基板 20は、パッド電極が形成された表面 2 1を上に向けた状態で載置台 17上にセットされる。はんだ供給器 50は、載置台 17上 の基板 20に向けて図 3 [ 2]に示す構造のはんだ微粒子を均等に落下させるための 吹き出し管 56を気体槽 11内の上部空間に配置して 、る。はんだ供給器 50の吹き出 し管 56は、図示しない吹き出し口が基端力 先端まで列状に多数設けられており、こ の吹き出し口からはんだ微粒子 14を不活性気体 13中へ均等に落下させるようにな つている。なお、図 3 [2]に示す構造以外のはんだ微粒子を供給する場合、はんだ供 給器 50は、例えば霧吹きの原理や超音波振動子などを用いて、溶融はんだを微粒 子状態にすることにより、はんだ微粒子 14を吹き出し管 56に通して気体槽 11内の不 活性気体 13中に供給する構造、或いは粉末状のはんだ微粒子 14を吹き出し管 56 に通して気体槽 11内の不活性気体 13中に供給する構造の 、ずれのもであってもよ い。なお、気体槽 11には、基板のパッド電極にはんだバンプを形成した残りの余剰 なはんだを排出する配管設備を増設してもよいものである。なお、前記溶融はんだを 用いる場合には、微粒子状態にされた状態で、冷却されて固形化され、相互に付着 しないので、吹き出し管 56を通して供給する際に、特に問題とならない。 The gas tank 11 includes a mounting table 17. The substrate 20 is set on the mounting table 17 with the surface 21 on which the pad electrode is formed facing upward. The solder feeder 50 is used to evenly drop the solder fine particles having the structure shown in FIG. 3 [2] toward the substrate 20 on the mounting table 17. The blowout pipe 56 is arranged in the upper space in the gas tank 11. The blower pipe 56 of the solder feeder 50 has a number of blowout ports (not shown) arranged in a line up to the tip of the base force, so that the solder fine particles 14 can be evenly dropped into the inert gas 13 from the blowout ports. It has become. In addition, when supplying solder fine particles other than the structure shown in FIG. 3 [2], the solder dispenser 50 makes the molten solder into a fine particle state by using, for example, a spraying principle or an ultrasonic vibrator. A structure in which the solder fine particles 14 are supplied to the inert gas 13 in the gas tank 11 through the blowing pipe 56 or the powdered solder fine particles 14 are passed through the blowing pipe 56 in the inert gas 13 in the gas tank 11. The structure to be supplied to may be out of alignment. Note that the gas tank 11 may be additionally provided with piping equipment for discharging the remaining excess solder in which solder bumps are formed on the pad electrodes of the substrate. When the molten solder is used, it is cooled and solidified in a fine particle state and does not adhere to each other.
[0109] また、気体槽 11は、例えばステンレスや耐熱性榭脂などカゝら成る容器に、不活性気 体 13をはんだの融点以上 (例えば融点 + 50°C)に保っための図示しない電熱ヒータ や冷却水配管等を備えている。載置台 17は、図示しない電熱ヒータなどにより、不活 性気体 13と同様にはんだの融点付近に保たれている。  [0109] Further, the gas tank 11 is an electric heating (not shown) for keeping the inert gas 13 above the melting point of the solder (for example, a melting point + 50 ° C) in a container made of, for example, stainless steel or heat resistant resin. A heater and cooling water piping are provided. The mounting table 17 is maintained in the vicinity of the melting point of the solder in the same manner as the inert gas 13 by an electric heater (not shown).
[0110] 不活性気体供給器 51は、コントローラ 55の制御の下に、不活性気体 13を気体槽 1 1内に供給するようになって ヽる。不活性気体供給器 51により供給された不活性気 体 13により、気体槽 11内に不活性雰囲気が形成される。フラックス供給器 53は、コ ントローラ 55の制御の下に、フラックスを気体槽 11内の不活性雰囲気 (不活性気体 1 3)中に供給するようになっている。なお、図 3 [2]のはんだ微粒子 14を使用する場合 には、はんだ微粒子 14がフラックスを有しているため、フラックス供給器 53により積極 的にフラックスを気体槽 11内に供給する必要はなぐ寧ろはんだ微粒子 14が保有す るフラックスが不足している場合などに補助的に不足分のフラックスを供給する。酸ィ匕 還元剤供給器 54は、コントローラ 55の制御の下に、例えば水素ガスなどの酸ィ匕還元 剤を微粒子にして気体槽 11内の不活性雰囲気 (不活性気体 13)中に供給するよう になっている。なお、図 3 [2]のはんだ微粒子 14を使用する場合には、酸化還元剤 供給器 54は、自然酸化膜で付着したはんだ微粒子を気体槽内に供給する場合に、 酸ィ匕還元剤を積極的に気体槽内に供給することが望ましいものである。 [0110] The inert gas supplier 51 supplies the inert gas 13 into the gas tank 11 under the control of the controller 55. An inert atmosphere is formed in the gas tank 11 by the inert gas 13 supplied from the inert gas supply device 51. The flux supplier 53 supplies the flux into the inert atmosphere (inert gas 13) in the gas tank 11 under the control of the controller 55. In addition, when using the solder fine particles 14 shown in FIG. 3 [2], the solder fine particles 14 have a flux, so there is no need to actively supply the flux into the gas tank 11 by the flux feeder 53. On the contrary, when the flux held by the solder fine particles 14 is insufficient, the insufficient flux is supplementarily supplied. Under the control of the controller 55, the acid reducing agent supplier 54 supplies, for example, an oxygen reducing agent such as hydrogen gas as fine particles to the inert atmosphere (inert gas 13) in the gas tank 11. It is like this. When the solder fine particles 14 shown in FIG. 3 [2] are used, the oxidation-reduction agent supplier 54 supplies the solder fine particles adhering to the natural oxide film into the gas tank. It is desirable to actively supply the acid reducing agent into the gas tank.
[0111] 次に、図 3 [2]に示すはんだ微粒子を用い、図 8に示すはんだバンプ形成装置によ り、基板 20のパッド電極 22上にはんだバンプを形成する方法について説明する。  Next, a method of forming solder bumps on the pad electrodes 22 of the substrate 20 by using the solder fine particles shown in FIG. 3 [2] and using the solder bump forming apparatus shown in FIG.
[0112] 先ず、コントローラ 54の制御の下に不活性気体供給器 51から不活性気体 13を気 体槽 11内に供給し、気体槽 11内の不活性気体 13及び載置台 17をはんだ融点付 近まで加熱する。一方、基板 20を気体槽 11に連通する、外部雰囲気から遮断した 図示しない予備室に一時セットして予熱する。次いで、前記予備室と気体槽 11の間 を連通し、基板 20を気体槽 11内の載置台 17上にセットし、基板 20を不活性気体 13 の不活性雰囲気中に位置付けする。この状態で基板 20のパッド電極 22をはんだ融 点付近まで加熱する。  [0112] First, under the control of the controller 54, the inert gas 13 is supplied from the inert gas supply 51 into the gas tank 11, and the inert gas 13 and the mounting table 17 in the gas tank 11 are attached with a solder melting point. Heat to near. On the other hand, the substrate 20 is temporarily set and preheated in a preliminary chamber (not shown) communicating with the gas tank 11 and shielded from the external atmosphere. Next, the preliminary chamber communicates with the gas tank 11, the substrate 20 is set on the mounting table 17 in the gas tank 11, and the substrate 20 is positioned in the inert atmosphere of the inert gas 13. In this state, the pad electrode 22 of the substrate 20 is heated to near the solder melting point.
[0113] 不活性気体 13及び基板 20のパッド電極 22がはんだ融点付近まで加熱されている 状態において、コントローラ 55の制御の下にはんだ供給器 52から図 3 [2]に示すは んだ微粒子 14を吹き出し管 56に通して気体槽 11内の不活性雰囲気中に送りだす。 送りだされたはんだ微粒子 14は、層状をなして基板 20のパッド電極 22に向けて落 下する。前記はんだ微粒子としては、ナノオーダの粒径をもつものが使われる場合が ある。このようなはんだ微粒子は、例えば液体中を沈降させる場合、液体による粘性 によりスムーズに基板 20に到達せず、また沈降方向が曲げられてしまう場合がある。 本実施形態では、はんだ微粒子 14は不活性気体 13中に落下するため、前述の式〈く 3》における粘性係数 kが極めて小さくなるため、はんだ微粒子 14の落下速度は大き い。すなわち、はんだ微粒子 14が小さくてもすぐに落下して基板 20に到達するので 、はんだバンプ 23の形成に要する時間も短い。また、不活性気体 13中を落下するた め、はんだ微粒子 14は吹き出し管 56から供給された際に層状をなして落下する形 態を取りやすいものである。さらに、はんだ微粒子 14が不活性気体 13中を落下する 際に、不活性気体 13がはんだ融点付近に加熱されているため、はんだ微粒子 14は 、不活性気体 13からの輻射熱を受けながら、基板 20のパッド電極 22に向けて落下 する。  [0113] In the state where the inert gas 13 and the pad electrode 22 of the substrate 20 are heated to near the solder melting point, the solder fine particles 14 shown in FIG. Is fed into the inert atmosphere in the gas tank 11 through the blow pipe 56. The sent solder fine particles 14 form a layer and drop toward the pad electrode 22 of the substrate 20. As the solder fine particles, those having a nano-order particle size may be used. For example, when such solder fine particles are allowed to settle in a liquid, they may not reach the substrate 20 smoothly due to the viscosity of the liquid, and the settling direction may be bent. In the present embodiment, since the solder fine particles 14 fall into the inert gas 13, the viscosity coefficient k in the above-described equation <3> is extremely small, so that the solder fine particles 14 fall at a high speed. That is, even if the solder fine particles 14 are small, the solder fine particles 14 immediately fall and reach the substrate 20, so that the time required for forming the solder bumps 23 is short. In addition, since the solder particles 14 fall in the inert gas 13, the solder fine particles 14 easily take a form of falling in a layered form when supplied from the blowing pipe 56. Further, since the inert gas 13 is heated near the melting point of the solder when the solder fine particles 14 fall in the inert gas 13, the solder fine particles 14 receive the radiant heat from the inert gas 13, while the substrate 20 Drops toward the pad electrode 22
[0114] はんだ微粒子 14が基板 20のパッド電極 22上に到達すると、はんだ微粒子 14を皮 膜の核としてパッド電極 22の表面にはんだ皮膜 23'が形成される。前記はんだ皮膜 23 'が形成される過程について考察する。この考察は本発明者の推測に基づくもの であるが、この考察に基づくと、パッド電極 22上にはんだバンプ 23が形成される原理 を理路整然と説明することができる。 When the solder fine particles 14 reach the pad electrode 22 of the substrate 20, a solder film 23 ′ is formed on the surface of the pad electrode 22 using the solder fine particles 14 as the core of the film. The solder film Consider the process by which 23 'is formed. This consideration is based on the assumption of the present inventor, but based on this consideration, the principle that the solder bump 23 is formed on the pad electrode 22 can be reasonably explained.
[0115] 図 3 [2]に示すはんだ微粒子 14が基板 20のノ¾ /ド電極 22上に到達すると、加熱さ れた基板 20の輻射熱を受けて、フラックス 31,有機皮膜 33及びはんだ微粒子 14が 加熱される。有機皮膜 33によっては図 9 (a)に示すように、矢印で示すように溶融す るフラックス 31内に溶け出るものがある。  [0115] When the solder fine particles 14 shown in FIG. 3 [2] reach the cathode / node electrode 22 of the substrate 20, they receive the radiant heat of the heated substrate 20, and the flux 31, the organic film 33 and the solder fine particles 14 Is heated. Depending on the organic film 33, as shown in FIG. 9 (a), some of the organic film 33 dissolves into the melting flux 31 as indicated by the arrows.
[0116] 図 9 (a)の状態でさらに、基板 20からの輻射熱を受けてフラックス 31が溶融すると、 図 9 (b)に示すように、フラックス 31によりはんだ微粒子 14の表面に付着した自然酸 化膜などの酸化膜及び有機皮膜 33が除去され、フラックス 31内に、溶融したはんだ 微粒子の表面が露出するものと考えられる。以上の現象は、ノッド電極 22上に隣接 したはんだ微粒子 14の全てにぉ 、て生じるものと考えられる。隣接したはんだ微粒 子 14のフラックス 31が溶融すると、その溶融したフラックス 31同士が融合し、その融 合したフラックス 31内に溶融したはんだ微粒子 14が包込まれることとなる。  In the state of FIG. 9 (a), when the flux 31 is further melted by receiving radiant heat from the substrate 20, as shown in FIG. 9 (b), the natural acid adhered to the surface of the solder fine particles 14 by the flux 31. It is considered that the oxide film such as the oxide film and the organic film 33 are removed, and the surface of the molten solder fine particles is exposed in the flux 31. The above phenomenon is considered to occur in all the solder fine particles 14 adjacent on the nod electrode 22. When the flux 31 of the adjacent solder fine particles 14 is melted, the melted fluxes 31 are fused, and the melted solder fine particles 14 are encapsulated in the fused flux 31.
[0117] 融合したフラックス 31内に包込まれた溶融したはんだ微粒子 14は、その表面が露 出しているため、図 9 (c)に示すように互いに合一して粒径の大きなはんだ 14aとして 成長する。はんだ 14aは、はんだバンプ 23の核となるものである。  [0117] Since the surface of the molten solder fine particles 14 encapsulated in the fused flux 31 is exposed, they are united with each other as shown in FIG. grow up. The solder 14a is the core of the solder bump 23.
[0118] 一方、有機皮膜 33は溶融してフラックス 31内に溶け出して実質的に除去されてい るため、溶融したフラックス 31と溶融したはんだ 14aは直接接触するため、図 9 (c)に 示すようにフラックス 31とはんだ 14aが化学反応を起し、新たな有機皮膜 33aを析出 する。当初に形成される有機皮膜 33aは極薄いものである。  [0118] On the other hand, since the organic film 33 is melted and dissolved in the flux 31 and is substantially removed, the molten flux 31 and the molten solder 14a are in direct contact with each other, as shown in FIG. 9 (c). Thus, the flux 31 and the solder 14a cause a chemical reaction to deposit a new organic film 33a. The organic film 33a initially formed is extremely thin.
[0119] 当初にはんだ 14aの表面に形成される有機皮膜 33aは極薄いため、パッド電極 22 とはんだ 14aの間に共晶化現象が生じ、ノッド電極 14とはんだ 14aの界面が融合し 、その両者が接合するものと考えられる。したがって、パッド電極 22以外の基板 20は 、保護膜 27で覆われているため、パッド電極 22以外の領域にはんだバンプ 23の核 は成長しないこととなる。  [0119] Since the organic film 33a initially formed on the surface of the solder 14a is extremely thin, an eutectic phenomenon occurs between the pad electrode 22 and the solder 14a, and the interface between the nod electrode 14 and the solder 14a is fused. It is thought that both join. Therefore, since the substrate 20 other than the pad electrode 22 is covered with the protective film 27, the nucleus of the solder bump 23 does not grow in a region other than the pad electrode 22.
[0120] 以上の現象が、ノ^ド電極 22上に到達した複数のはんだ微粒子 14同士間で生じ、 この現象により、はんだ微粒子 14は大きな粒径のはんだ 14aに成長する。以上の現 象が繰返して行われると、当初極薄い膜厚であった有機皮膜 33aは、その膜厚が徐 々に厚くなり、やがて、有機皮膜 33aの膜厚は、フラックス 31によって除去困難な厚 みとなる。このため、大きな粒径のはんだ 14aの成長は停止し、このはんだ 14aがは んだバンプ 23としてパッド電極 22上に存在する。 [0120] The above phenomenon occurs between the plurality of solder fine particles 14 that have reached the node electrode 22, and by this phenomenon, the solder fine particles 14 grow into solder 14a having a large particle diameter. Above current When the elephant is repeated, the film thickness of the organic film 33a, which was extremely thin at the beginning, gradually increases, and eventually, the film thickness of the organic film 33a has a thickness that is difficult to remove by the flux 31. Become. For this reason, the growth of the solder 14a having a large grain size stops, and the solder 14a exists on the pad electrode 22 as a bump 23 in which the solder 14a is inserted.
[0121] 以上のように、はんだ 14aとパッド電極 22との界面における共晶現象、及び新たに 成膜される有機皮膜 33aの作用により、パッド電極 22上にはんだバンプ 23が形成さ れる。 [0121] As described above, the solder bump 23 is formed on the pad electrode 22 by the eutectic phenomenon at the interface between the solder 14a and the pad electrode 22 and the action of the newly formed organic film 33a.
[0122] したがって、本実施形態によれば、有機皮膜 33aの作用によりはんだの粒径を制御 させることにより、はんだバンプ 23の核を基板 20のパッド電極 22の範囲に定位させ て成長させるため、パッド電極 22がファインピッチの間隔でもって形成する場合にも、 隣接するパッド電極 22の相互間におけるはんだブリッジの発生を抑制することができ る。  Therefore, according to the present embodiment, by controlling the particle size of the solder by the action of the organic film 33a, the nucleus of the solder bump 23 is localized and grown in the range of the pad electrode 22 of the substrate 20, Even when the pad electrodes 22 are formed with a fine pitch interval, the occurrence of solder bridges between adjacent pad electrodes 22 can be suppressed.
[0123] なお、図 8に示す本実施形態は、図示した構成に限定されるものではない。例えば 、はんだ微粒子をパッド電極に向けて噴霧するのであれば、不活性気体中において 基板の表面は必ずしも上にする必要はなく横でも下でも斜めでもよい。また、シリコン ウェハ (FC)の代わりに、配線板 (BGA)を用いてもよい。更に、はんだ微粒子を固体 のまま噴霧し、そのはんだ微粒子を不活性気体中で溶融してもよい。また、不活性気 体供給器 51 ,はんだ供給器 52,フラックス供給器 53,酸化還元剤供給器 54を、図 1 に示すはんだ噴霧器 12のように一体構造に集積してもよいものである。また、図 8に 示すはんだバンプ形成装置にぉ ヽて、図 7のように気体槽 11内を減圧する減圧手段 を装備するようにしてもょ 、ものである。  Note that the present embodiment illustrated in FIG. 8 is not limited to the illustrated configuration. For example, if the solder fine particles are sprayed toward the pad electrode, the surface of the substrate does not necessarily have to be up in the inert gas, and may be horizontal, down, or diagonal. A wiring board (BGA) may be used instead of the silicon wafer (FC). Further, the solder fine particles may be sprayed as a solid, and the solder fine particles may be melted in an inert gas. Further, the inert gas supply device 51, the solder supply device 52, the flux supply device 53, and the oxidation-reduction agent supply device 54 may be integrated in an integrated structure like the solder sprayer 12 shown in FIG. In addition, the solder bump forming apparatus shown in FIG. 8 may be equipped with a decompression means for decompressing the gas tank 11 as shown in FIG.
産業上の利用可能性  Industrial applicability
[0124] 以上説明したように本発明によれば、ノッド電極のファインピッチ化を図れるととも に、はんだ量が多くかつバラツキも少ないはんだバンプを得られ、しかも短時間では んだバンプを形成できる。 As described above, according to the present invention, the fine pitch of the nod electrode can be achieved, and a solder bump having a large amount of solder and little variation can be obtained, and a bump can be formed in a short time. .
図面の簡単な説明  Brief Description of Drawings
[0125] [図 1]本発明に係るはんだバンプの形成方法及び装置の第一実施形態を示す概略 構成図であり、図 1 [1]〜図 1 [3]の順に工程が進行する。 FIG. 1 is a schematic configuration diagram showing a first embodiment of a solder bump forming method and apparatus according to the present invention, and the steps proceed in the order of FIG. 1 [1] to FIG. 1 [3].
[図 2]図 1の部分拡大断面図であり、図 2[1]〜図 2[3]はそれぞれ図 1 [1]〜図 1 [3] に対 〇応する。 [Fig.2] Partially enlarged sectional view of Fig. 1. Fig.2 [1] to Fig.2 [3] correspond to Fig.1 [1] to Fig.1 [3], respectively.
圆 3]本発明に係るはんだバンプの形成方法及び装置の第二実施形態で用いるは んだ微粒子を示す拡大断面図であり、図 3 [1]は第一例であり、図 3 [2]は第二例で ある。 3] An enlarged cross-sectional view showing the solder fine particles used in the second embodiment of the solder bump forming method and apparatus according to the present invention, FIG. 3 [1] is a first example, and FIG. 3 [2] Is a second example.
圆 4]第二実施形態を示す概略構成図であり、図 4[1]〜図 4[2]の順に工程が進行 する。 圆 4] It is a schematic configuration diagram showing the second embodiment, and the process proceeds in the order of FIG. 4 [1] to FIG. 4 [2].
圆 5]第二実施形態を示す概略構成図であり、図 5 [1]〜図 5 [2]の順に工程が進行 する。 圆 5] It is a schematic configuration diagram showing the second embodiment, and the process proceeds in the order of FIG. 5 [1] to FIG. 5 [2].
圆 6]第二実施形態を示す部分拡大断面図であり、図 6 [1]〜図 6 [3]の順に工程が 進行する。 圆 6] It is a partially enlarged sectional view showing the second embodiment, and the process proceeds in the order of FIG. 6 [1] to FIG. 6 [3].
[図 7]本発明に係るはんだバンプの形成方法及び装置の第三実施形態を示す概略 構成図であり、図 7[1]〜図 7[2]の順に工程が進行する。  FIG. 7 is a schematic configuration diagram showing a third embodiment of the method and apparatus for forming solder bumps according to the present invention, in which the process proceeds in the order of FIGS. 7 [1] to 7 [2].
圆 8]本発明の他の実施形態を示す概略構成図である。 [8] FIG. 8 is a schematic configuration diagram showing another embodiment of the present invention.
圆 9]はんだバンプが形成される過程を示す断面図である。 9] A sectional view showing a process of forming solder bumps.
[図 10]従来のはんだバンプの形成方法を示す概略断面図である。  FIG. 10 is a schematic cross-sectional view showing a conventional solder bump forming method.
符号の説明 Explanation of symbols
30, 40 はんだバンプの形成装置  30, 40 Solder bump forming equipment
11 気体槽  11 Gas tank
12 はんだ噴霧器  12 Solder sprayer
13 不活性気体  13 Inert gas
14 はんだ微粒子  14 Solder particles
20 基板  20 substrates
21 基板の表面  21 Board surface
22 パッド電極  22 Pad electrode
23 はんだバンプ  23 Solder bump
31 液体  31 liquid
32 ヒータ (加熱手段） 有機皮膜 32 Heater (heating means) Organic film
コントローラ (減圧手段) 真空ポンプ (減圧手段） 44 電磁弁 (減圧手段) Controller (pressure reduction means) Vacuum pump (pressure reduction means) 44 Solenoid valve (pressure reduction means)

Claims

請求の範囲 The scope of the claims
[I] パッド電極を不活性気体中に位置付け、  [I] Position the pad electrode in an inert gas,
はんだ微粒子を前記不活性気体中のパッド電極に向けて送り出すことにより、前記 ノ ッド電極にはんだバンプを形成することを特徴とするはんだバンプの形成方法。  A method for forming a solder bump, comprising: forming solder bumps on the node electrode by sending solder fine particles toward the pad electrode in the inert gas.
[2] 前記はんだ微粒子を、フラックスを含む前記不活性気体中に送りだすことを特徴と する請求項 1に記載のはんだバンプの形成方法。  [2] The method for forming a solder bump according to [1], wherein the solder fine particles are fed into the inert gas containing a flux.
[3] 前記はんだ微粒子を、水素ガスを含む不活性気体中に送りだすことを特徴とする 請求項 1又は 2のいずれか一項に記載のはんだバンプの形成方法。 [3] The method for forming a solder bump according to any one of claims 1 and 2, wherein the solder fine particles are fed into an inert gas containing hydrogen gas.
[4] 隣接する前記パッド電極相互間の間隔より小さい直径をもつ前記はんだ微粒子を 前記不活性雰囲気中に送りだすことを特徴とする請求項 1に記載のはんだバンプの 形成方法。 [4] The method for forming solder bumps according to [1], wherein the solder fine particles having a diameter smaller than a distance between adjacent pad electrodes are sent into the inert atmosphere.
[5] 有機皮膜で被覆された前記はんだ微粒子を送りだすことを特徴とする請求項 1〜4 のいずれか一項に記載のはんだバンプの形成方法。  [5] The method for forming a solder bump according to any one of [1] to [4], wherein the solder fine particles coated with an organic film are sent out.
[6] フラックス作用をもつ皮膜で被覆された前記はんだ微粒子を送りだすことを特徴と する請求項 1〜4のいずれか一項に記載のはんだバンプの形成方法。 [6] The method for forming a solder bump according to any one of [1] to [4], wherein the solder fine particles coated with a film having a flux action are sent out.
[7] 前記はんだ微粒子を送りだす際に、前記不活性気体を大気圧以下に減圧しておく ことを特徴とする請求項 1〜4のいずれか一項に記載のはんだバンプの形成方法。 [7] The method for forming a solder bump according to any one of [1] to [4], wherein when the solder fine particles are sent out, the inert gas is depressurized to an atmospheric pressure or lower.
[8] パッド電極を有する基板が位置付けされる不活性雰囲気を形成するための気体槽 と、 [8] a gas tank for forming an inert atmosphere in which a substrate having a pad electrode is positioned;
前記不活性雰囲気中に位置付けられた前記基板のパッド電極に向けてはんだ微 粒子を送りだすはんだ噴霧器を有することを特徴とするはんだバンプの形成装置。  An apparatus for forming a solder bump, comprising: a solder sprayer that sends out solder fine particles toward the pad electrode of the substrate positioned in the inert atmosphere.
[9] 前記はんだ噴霧器は、前記はんだ微粒子を送りだすことに加えて、フラックスを前 記不活性雰囲気中に送りだすことを特徴とする請求項 5に記載のはんだバンプの形 成装置。 [9] The solder bump forming device according to [5], wherein the solder sprayer sends the flux into the inert atmosphere in addition to feeding the solder fine particles.
[10] 前記はんだ噴霧器は、前記はんだ微粒子を送りだすことに加えて、フラックス及び 又は水素ガスを前記不活性雰囲気中に送りだすことを特徴とする請求項 5に記載の はんだバンプの形成装置。  10. The solder bump forming apparatus according to claim 5, wherein the solder sprayer sends a flux and / or hydrogen gas into the inert atmosphere in addition to sending the solder fine particles.
[II] 前記はんだ噴霧器は、隣接する前記パッド電極相互間の間隔より小さい直径をも つはんだ微粒子を、前記はんだ微粒子として用いることを特徴とする請求項 5に記載 のはんだバンプの形成装置。 [II] The solder sprayer has a diameter smaller than a distance between adjacent pad electrodes. The solder bump forming apparatus according to claim 5, wherein one solder fine particle is used as the solder fine particle.
[12] 前記気体槽内を減圧する減圧手段を有することを特徴とする請求項 5に記載のは んだバンプの形成装置。 [12] The solder bump forming apparatus according to [5], further comprising a decompression means for decompressing the inside of the gas tank.
[13] はんだ微粒子によるはんだバンプを電極上に形成するはんだバンプ形成方法にお いて、 [13] In a solder bump forming method of forming solder bumps on electrodes with solder fine particles,
前記はんだバンプとして、有機皮膜及びフラックスにより被覆されたはんだ微粒子 を用い、  Using solder fine particles coated with an organic film and flux as the solder bumps,
不活性雰囲気中に前記電極を位置付けするセットステップと、  A set step of positioning the electrode in an inert atmosphere;
前記不活性雰囲気及び電極を加熱しながら、はんだ微粒子を前記不活性雰囲気 中に供給する供給ステップと、  Supplying the solder fine particles into the inert atmosphere while heating the inert atmosphere and the electrode;
有機皮膜によってはんだの粒径を制御させることにより、はんだバンプの核を前記 電極の範囲に定位させる成長ステップを有することを特徴とするはんだバンプ形成方 法。  A method for forming a solder bump, comprising a growth step in which the core of the solder bump is localized in the range of the electrode by controlling the particle size of the solder with an organic film.
[14] はんだ微粒子によるはんだバンプを形成するはんだ形成装置にぉ 、て、  [14] In a solder forming apparatus for forming solder bumps with solder fine particles,
不活性雰囲気を形成する気体槽と、  A gas tank forming an inert atmosphere;
前記気体槽内の前記不活性雰囲気中にはんだ微粒子を供給するはんだ供給器を 有することを特徴とするはんだバンプ形成装置。  A solder bump forming apparatus, comprising: a solder feeder for supplying solder fine particles into the inert atmosphere in the gas tank.
[15] 前記はんだ供給器は、有機皮膜及びフラックスにより被覆されたはんだ微粒子を供 給することを特徴とする請求項 14に記載のはんだバンプの形成装置。 15. The solder bump forming apparatus according to claim 14, wherein the solder supply device supplies solder fine particles coated with an organic film and a flux.
[16] 前記気体槽内を減圧する減圧手段を有することを特徴とする請求項 14に記載のは んだバンプの形成装置。 [16] The solder bump forming apparatus according to [14], further comprising a decompression unit configured to decompress the inside of the gas tank.
PCT/JP2005/021833 2004-11-29 2005-11-29 Method and device for forming solder bump WO2006057394A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013026559A (en) * 2011-07-25 2013-02-04 Tdk Corp Solder bump forming method

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002076043A (en) * 2000-08-28 2002-03-15 Mitsubishi Electric Corp Bump forming method, semiconductor device, and bump forming device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002076043A (en) * 2000-08-28 2002-03-15 Mitsubishi Electric Corp Bump forming method, semiconductor device, and bump forming device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013026559A (en) * 2011-07-25 2013-02-04 Tdk Corp Solder bump forming method

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