KR20140066492A - Method of forming conductive pattern using inkjet printing technique - Google Patents

Method of forming conductive pattern using inkjet printing technique Download PDF

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Publication number
KR20140066492A
KR20140066492A KR1020120133781A KR20120133781A KR20140066492A KR 20140066492 A KR20140066492 A KR 20140066492A KR 1020120133781 A KR1020120133781 A KR 1020120133781A KR 20120133781 A KR20120133781 A KR 20120133781A KR 20140066492 A KR20140066492 A KR 20140066492A
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KR
South Korea
Prior art keywords
opening
substrate
conductive pattern
ink
mask
Prior art date
Application number
KR1020120133781A
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Korean (ko)
Inventor
이승호
김중혁
홍영기
강성규
홍진석
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삼성전자주식회사
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Priority to KR1020120133781A priority Critical patent/KR20140066492A/en
Publication of KR20140066492A publication Critical patent/KR20140066492A/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • 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
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/0271—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers
    • H01L21/0273—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers characterised by the treatment of photoresist layers
    • H01L21/0274—Photolithographic processes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
    • H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
    • H01L21/288—Deposition of conductive or insulating materials for electrodes conducting electric current from a liquid, e.g. electrolytic deposition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
    • H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors

Abstract

A method of forming a conductive pattern on a substrate using an ink-jet printing technique, comprising: forming a mask of a thermoplastic material having an opening on one side of the substrate; Re-heating and softening the mask to re-shape the sidewall of the opening into an open shape; Discharging ink containing conductive particles to the substrate through the opening; And forming a conductive pattern made of conductive particles in the opening by a drying process and a baking process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of forming a conductive pattern using an inkjet printing technique,

And a method of forming a conductive pattern on a substrate using an ink-jet printing technique.

2. Description of the Related Art In general, an ink-jet printing apparatus refers to an apparatus that prints a predetermined image by ejecting a minute droplet of ink through a nozzle of an ink-jet head to a desired position on a print medium. In recent years, such an ink-jet printing apparatus has been widely used in the fields of flat panel displays such as liquid crystal displays (LCDs), organic light emitting devices (OLEDs) and the like, flexible display fields such as electronic paper (e-paper) (OTFT), biotechnology, and bioscience, in the field of printed electronics such as metal wiring and the like.

One of the important technical issues in applying the process of forming the conductive pattern by the inkjet printing apparatus to the above-mentioned fields is to reliably form thick wirings with a small width without a short circuit or open. 2. Description of the Related Art As electronic devices rapidly become smaller, higher performance, and more versatile, wiring boards for mounting electronic devices such as semiconductor devices are required to have higher density and higher reliability. For example, as the TFT-LCD becomes super-high resolution, large-sized, or circuits of semiconductor devices become denser, a thick wiring with a fine line width is desired in order to solve wiring resistance increase and RC delay (Resistance × Capacitance Delay).

It is another object of the present invention to provide a method of forming a thick conductive pattern on a substrate by an inkjet printing process.

According to an aspect of the present invention, there is provided a method of forming a conductive pattern on a substrate using an ink-jet printing technique, comprising: forming a mask made of a thermoplastic material having an opening on one side of the substrate; Re-heating and softening the mask to reform the sidewall of the opening into an upwardly open shape; Discharging ink containing conductive particles to the substrate through the opening; And forming a conductive pattern of the conductive particles in the opening by a drying process and a baking process.

The mask can be formed by photo-etching the photoresist layer. The photoresist layer may be a positive photoresist.

The method may further include, after performing the drying step, removing the mask before performing the firing process.

The method may further include forming a hydrophobic layer on the mask and the substrate before performing the step of ejecting the ink droplet.

The reheating temperature and time may be determined so that the ratio of the upper width to the lower width of the opening is 1 or more.

The mask may be formed of a polyimide resin.

According to the embodiments of the present invention described above, it is possible to easily form a thick conductive pattern by an ink-jet printing technique.

1 schematically shows an example of an ink-jet printing apparatus applied to a process of forming a conductive pattern.
2A is a diagram showing a state in which a mask layer having an opening is formed in a substrate.
2B is a view showing the shape of the opening after the mask layer is softened and reflowed.
2C is a view showing a state where a hydrophobic layer is formed on a substrate on which a mask layer is formed
2D is a view showing a state in which the opening is filled with ink.
Figure 2e shows the conductive particles remaining in the openings after the drying process.
FIG. 2F is a view showing a state in which the mask layer is removed after the drying process. FIG.
FIG. 2G is a view showing a state in which formation of the conductive pattern is completed after the baking process.
Fig. 3 is a schematic view of an opening formed by the softening process.
4 is a graph showing the thickness ratio (t / W) of the conductive pattern according to the change of the aspect ratio (h / W) of the opening.
5A is an optical microscope photograph showing the shape of the opening before the softening process is performed as an experimental example.
FIG. 5B is an optical microscope photograph showing the shape of an opening formed by an excessive softening process as an experimental example.
FIG. 5C is an optical microscope photograph showing the shape of the opening formed by the softening process as an experimental example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements, and the size and thickness of each element may be exaggerated for clarity of explanation.

1 schematically shows an ink-jet printing apparatus for performing a method of forming a conductive pattern according to an embodiment of the present invention. Referring to FIG. 1, the inkjet printing apparatus 1 may include an inkjet head 2. As the ink jet head 2, various types of liquid discharging means such as a piezoelectric method using a piezoelectric driving force, an electrostatic method using an electrostatic driving force, or a piezoelectric / electrostatic hybrid method using them together can be employed. The inkjet head 2 is movably provided above the substrate 100 and ejects the ink 4 onto the surface of the substrate 100 to form predetermined print patterns. The inkjet head 2 can be connected to the ink chamber 3 for supplying the ink 4.

The ink 4 may be a solution in which conductive particles such as Au, Ag or Cu particles are dispersed in a solvent. When the ink 4 is discharged onto the substrate 100 and then the solvent is evaporated through the drying process, only the conductive particles remain on the substrate 100. Thereafter, a conductive pattern, that is, wiring is formed on the substrate 100 by performing a sintering process.

As described above, the ink 4 is a form in which conductive particles are dispersed in a solvent, and the solvent is evaporated through a drying process. Since the proportion of the conductive particles in the ink 4 is very low, the thickness of the conductive particles remaining on the substrate 100 through the drying process is only a few to several tens of minutes of the ink 4. Furthermore, the thickness of the conductive pattern is further reduced by densification by high-temperature firing. It is possible to consider increasing the amount of the ink 4 in order to increase the thickness of the conductive pattern. In this case, however, the ink 4 spreads to the adjacent conductive pattern and there is a risk of short-circuiting. As another approach, it is possible to consider forming a trench having a large aspect ratio in the substrate, i.e., a deep trench, but the aspect ratio of the trench may be limited due to process factors.

Hereinafter, a method of forming a conductive pattern capable of forming a thick wiring by an ink-jet printing method will be described.

First, as shown in FIG. 2A, a mask layer 200 having an opening 201 on one side of the substrate 100, for example, the upper surface 101, is formed. The mask layer 200 may be formed of a resin, for example, a thermoplastic resin, which can be softened by applying heat. The opening 201 corresponds to an area to which ink is to be ejected to form a conductive pattern. The upper surface 101 of the substrate 100 on which the conductive pattern is to be formed is exposed by the opening 201. [

The mask layer 200 may be formed, for example, from a photoresist. A mask layer 200 having openings 201 can be formed by patterning the photoresist layer by, for example, a photolithography method after forming a layer of photoresist on the upper surface 101 of the substrate 100 have. The photoresist may be a negative photoresist or a positive photoresist. A negative photoresist refers to a photoresist where the exposed portion is cured to leave after patterning and the unexposed portions are removed. On the contrary, the positive porter resists are photoresists that are exposed in the patterning process.

Next, the substrate 100 on which the mask layer 200 is formed is heated to the softening temperature of the mask layer 200. Then, the mask layer 200 is softened and reflowed, and the opening 201 is re-formed into a shape widening upward as shown in FIG. 2B. Then, the inner volume of the opening 201 is increased as compared with that before softening, so that more ink can be accommodated in the opening 201.

The process of forming the hydrophobic layer 300 as shown in FIG. 2C may be performed before the ink is ejected into the opening 201. The hydrophobic layer 300 may be formed on the mask layer 200 and the exposed upper surface 101 of the substrate 100. The hydrophobic layer 300 may be a self-assembled monolayer (SAM) and may be an organic film layer containing a fluorine component. The self-assembled material forming the self-assembled monolayer can be formed, for example, by an organosilicon compound. The organosilicon compound may be, for example, a compound represented by RSiX3. Wherein X is a halogen or an alkoxy group and R is an n-alkylsilane such as an n-alkyl group (n-CnH2n + 1) such as n-alkyltriclorosilane, n- ). The hydrophobic layer 300 may be formed by applying a self-assembled material or an organic material containing a fluorine component to the substrate 100 and the mask layer 200 by a process such as dip coating or spin coating. For example, a self-assembled material or an organic material containing a fluorine component may be mixed with a solvent to form a solution, and the substrate 100 on which the mask layer 200 is formed may be exposed to the solution. In order to easily form the hydrophobic layer 300, a process of removing foreign substances on the surface of the substrate 100 and the mask layer 200 may be performed first. The step of removing the foreign matter can be performed by, for example, irradiating deep UV, ultraviolet ozone, oxygen plasma, or argon plasma.

Next, the ink is ejected into the opening 201 by using the ink-jet printing apparatus 1 shown in Fig. Then, as shown in Fig. 2D, the opening 201 is filled with ink.

When the liquid is placed on the horizontal plane of the solid, it may become a droplet that maintains a constant lens shape. At this time, the surface of the droplet becomes a curved surface, and the angle formed by the tangent to the surface of the droplet and the surface of the solid at the contact point at which the solid contacts the droplet is referred to as the contact angle. The contact angle is generally determined by the type of liquid and solid. The larger the contact angle, the more phobic the liquid is, and the smaller the contact angle, the more hydrophilic the liquid is to the solid. The larger the difference in surface energy between the solid and the liquid, the larger the contact angle. If the contact angle is large, the liquid spreads on the surface of the solid, which does not wettably wet the solid surface, and the liquid on the solid surface aggregates in the form of a droplet. If the contact angle is small, the liquid spreads along the surface of the solid, so that adjacent droplets join together and wet the surface of the solid.

The hydrophobic layer 300 increases the contact angle between the ink and the mask layer 200, thereby weakening the tendency of the ink to spread along the surface of the mask layer 200. Therefore, it is possible to reduce the risk that the ink ejected to the adjacent opening 201 is connected to each other and is short-circuited. The ink ejected onto the surface of the mask layer 200 enters the opening 201 by a capillary force to fill the opening 201 and merges with the ink ejected to the opening 201, It coalesces. Therefore, more ink can be filled in the opening 201 as compared with when the contact angle is small, which is helpful in forming a thick wiring.

The drying process can then be carried out. For example, from room temperature to about 120 캜 for a certain period of time to evaporate the solvent of the ink. Then, only the conductive particles remain in the opening 201 as shown in Fig. 2E. As shown in FIG. 2B, when the reflow process is performed by softening, the opening 201 becomes a shape that flares upward as shown in FIG. 2B, and the amount of ink to be filled is larger than that of the opening 201 having a rectangular cross- More. Therefore, the thickness of the remaining conductive particles can be increased after the drying process.

Next, a firing process is performed. The firing process is a process for suppressing the internal pore of the conductive pattern through densification of the conductive pattern and improving the adhesion with the surface of the substrate 100. For example, it can be fired in a short time by using an electric furnace for rapid thermal annealing at a high temperature of 500 to 600 ° C. Thus, as shown in FIG. 2G, the conductive pattern 400 is formed on the substrate 100.

A process of removing the mask layer 200 as necessary before carrying out the firing process can be performed first. The photoresist can be removed, for example, with an acetone or photoresist stripper solution. If the hydrophobic layer 300 is first removed by irradiating deep UV, UV-ozone, oxygen plasma, or argon plasma before removing the photoresist, It is possible to easily penetrate the photoresist and cleanly remove the photoresist.

The mask layer 200 can serve to insulate wires or structurally support the wires. Therefore, if the mask layer 200 is made of a material capable of withstanding the firing temperature, the firing process may be performed without removing it as necessary. For example, in the case of forming the mask layer 200 using a polyimide series photoresist capable of withstanding a high temperature of about 500 ° C., the firing process is performed without removing the mask layer 200 It is possible.

In general, when the mask layer 200 is formed of a negative photoresist, the shape of the opening 201 tends to become slightly narrower toward the upper side. On the other hand, when the mask layer 200 is formed of a positive photoresist, the shape of the opening 201 tends to become slightly wider toward the upper side. Therefore, forming the mask layer 200 with a positive photoresist may be advantageous for forming the thick conductive pattern 400. [

[Example]

A mask layer 200 having openings 201 was formed in a photolithography process in which a positive photoresist (AZ4903) was coated on a glass substrate 100 to a thickness of 20 mu m and then exposed and developed using a mask. The width of the opening 201 is in the range of about 2 to 10 mu m. Subsequently, the substrate 100 on which the mask layer 200 is formed is subjected to a reflow process using a hot plate at a temperature of 100 to 110 ° C for 1 to 5 minutes so that the opening 201 is slightly rounded. . Next, the entire surface of the substrate 100 on which the mask layer 200 was formed was irradiated with oxygen plasma to modify the surface, and then dip-coated with a fluorine coating agent (3M Novec EGC-1720) to form the hydrophobic layer 300. Next, conductive silver ink (Harima Ink, NPS-J-HTB) was discharged into the opening 201 with the inkjet printer head to fill the opening 201. The filled ink was kept at room temperature for about 4 hours to dry naturally. Subsequently, the hydrophobic layer 300 on the substrate surface was irradiated with oxygen plasma again, and the substrate 100 was immersed in acetone for about 20 to 30 seconds to remove all the photoresist components. The substrate 100 having only dried silver (Ag) ink is fired at 500 to 550 ° C for 3 to 6 minutes using an electric furnace for rapid thermal annealing to finally form a conductive pattern 400 having a dense structure Respectively. As a result of checking with an optical microscope and FIB cross-sectional photograph, a conductive pattern 400 having a line width of about 3 to 4 μm and a height of about 2 to 3 μm was formed. As a result of measuring the resistivity of the conductive pattern 400, it showed a very good conductivity of 3 to 4 μΩ · cm.

Fig. 3 is a schematic view of the opening 201 formed by the softening process. 3, the bottom width of the opening 201 is W, the top width is W2, and the depth of the opening 201 is h. and t is the thickness of the conductive pattern 400 after being fired. The volume of the finally fired conductive pattern 400 is about several to ten to several ten percent of the volume of the ink ejected to the opening 201. Therefore, assuming that the volume of the finally fired conductive pattern 400 is about 10% of the volume of the ink ejected to the opening 201, a change in the aspect ratio (h / W) of the opening 201 The thickness ratio t / W of the conductive pattern 400 can be expressed as shown in the graph shown in FIG. 4, the larger the ratio W2 / W of the upper width W2 to the lower width W of the opening 201, the greater the thickness ratio t / W. When the ratio W2 / W is "1", the opening 201 having the aspect ratio of about 10 is required. However, when the ratio W2 / W is equal to 1, Quot; 2 ", an opening 201 having an aspect ratio of about 5 is required. That is, if the ratio W2 / W is larger than 1, the thick conductive pattern 400 can be formed without significantly increasing the aspect ratio of the opening 201. [ Therefore, the process conditions such as the temperature and the duration of the softening process can be set so that the ratio W2 / W of the openings 201 is larger than "1 ".

[Experimental Example]

Substrate: glass substrate

Mask layer: positive photoresist (AZ4903), thickness 20 mu m

Opening: 3-4㎛

In the above experimental example, before the softening process is performed, as shown in Fig. 5A, the width of the opening 201 is about 4 mu m. As shown in FIG. 5B, when the substrate is heated at about 110 ° C. for about 1 minute, it can be seen that the opening 201 is changed into an excessively round shape. It can be confirmed that when the substrate is heated at about 100 占 폚 for about 2 minutes, the opening 201 changes into a shape that flares as the opening 201 appropriately goes up as shown in Fig. 5c. When the reflow process by softening is performed excessively, the shape of the opening 201 may be excessively expanded, and the shape of the conductive particles remaining after drying may be shaped like a wing shape at the upper portion. Therefore, the reflow process by softening needs to be controlled in temperature and process time so that the opening 201 is not excessively opened.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the true scope of the present invention should be determined by the appended claims.

1 ... Ink-jet printing device 2 ... Ink-jet head
3 ... Ink tank 4 ... Ink
100 ... substrate 200 ... mask layer
201 ... opening 300 ... hydrophobic layer
400 ... conductive pattern

Claims (7)

A method of forming a conductive pattern on a substrate using an inkjet printing technique,
Forming a mask of a thermoplastic material having openings on one side of the substrate;
Re-heating and softening the mask to reform the sidewall of the opening into an upwardly open shape;
Discharging ink containing conductive particles to the substrate through the opening;
And forming a conductive pattern of the conductive particles in the opening by a drying process and a baking process. The method according to claim 1,
Wherein the mask is formed by photo-etching the photoresist layer. 3. The method of claim 2,
Wherein the photoresist layer is a positive photoresist. The method of claim 3,
Further comprising the step of removing the mask after performing the drying step and before performing the firing step. 5. The method according to any one of claims 1 to 4,
And forming a hydrophobic layer on the mask and the substrate before performing the step of ejecting the ink droplet. 5. The method according to any one of claims 1 to 4,
Wherein the reheating temperature and the time are determined so that the ratio of the overhang to the bottom width of the opening is 1 or more. The method according to claim 1,
Wherein the mask is formed of a polyimide resin.
KR1020120133781A 2012-11-23 2012-11-23 Method of forming conductive pattern using inkjet printing technique KR20140066492A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20220075115A (en) * 2020-11-27 2022-06-07 한국생산기술연구원 Method for manufacturing stretchable microelectrode

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20220075115A (en) * 2020-11-27 2022-06-07 한국생산기술연구원 Method for manufacturing stretchable microelectrode

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