WO2012099080A1 - 逆阻止型半導体素子の製造方法 - Google Patents
逆阻止型半導体素子の製造方法 Download PDFInfo
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- WO2012099080A1 WO2012099080A1 PCT/JP2012/050760 JP2012050760W WO2012099080A1 WO 2012099080 A1 WO2012099080 A1 WO 2012099080A1 JP 2012050760 W JP2012050760 W JP 2012050760W WO 2012099080 A1 WO2012099080 A1 WO 2012099080A1
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- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
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- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
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Definitions
- a reverse voltage blocking capability (hereinafter abbreviated as reverse blocking capability) is generally added to an insulated gate bipolar transistor (hereinafter abbreviated as IGBT), which normally has a reliability of only forward voltage blocking capability.
- IGBT insulated gate bipolar transistor
- the present invention relates to an improvement in a manufacturing method of a reverse blocking semiconductor element that maintains the same reliability as a forward voltage blocking capability (abbreviated as a forward blocking capability), and particularly to an improvement in a manufacturing method of a reverse blocking IGBT.
- reverse blocking capability equivalent to forward blocking capability is required.
- a reverse breakdown voltage pn junction on the back surface which is normally formed in a flat shape, is curved near the side surface of the chip, and the junction termination is made from the back surface side to the surface of the semiconductor chip. Need to be extended.
- the diffusion layer for forming the pn junction extended by bending from the back surface side to the front surface is referred to as a separation layer in the following description.
- FIG. 12 is a cross-sectional view of a principal part of a semiconductor substrate showing a separation layer forming method by conventional coating diffusion.
- 12 (a) to 12 (c) are cross-sectional views of the main part of the semiconductor substrate showing the main manufacturing process for forming the isolation layer of the conventional reverse blocking IGBT in the order of steps.
- FIG. 13 is a cross-sectional view of the vicinity of an end portion of a reverse blocking IGBT having a separation layer formed by conventional coating diffusion. Briefly speaking, the point of the manufacturing method shown in FIG. 13 is a method of forming a separation layer by coating diffusion.
- a thermal oxidation with a film thickness of about 2.5 ⁇ m is performed on a thick semiconductor substrate 1 having a diameter of 6 inches and a thickness of about 625 ⁇ m for use as a dopant mask.
- the oxide film 2 formed in (1) is formed (FIG. 12A).
- an opening 3 for forming the separation layer 4 is formed in the oxide film 2 formed on the semiconductor substrate 1 by patterning and etching (FIG. 12B).
- Boron source 5 is applied to the opening 3 formed in the oxide film 2, and then heat treatment is performed at a high temperature for a long time in a diffusion furnace to form a p-type diffusion layer 4a having a depth of about several hundred ⁇ m. (FIG. 12 (c)).
- This p-type diffusion layer can be used as the separation layer 4 by a process in a later step which will be described later.
- the back surface reaches the bottom of the separation layer 4 (FIG. 12C).
- the semiconductor substrate 1 is thinned by polishing to the broken line of FIG. 2, a back surface structure composed of the p collector layer 6 and the collector electrode 7 is formed on the polished surface, and the semiconductor is formed by the scribe line 8 located at the center of the separation layer 4.
- the substrate 1 is cut. Thereby, the reverse blocking type IGBT chip shown in FIG. 14 is obtained.
- FIG. 14 is a fragmentary cross-sectional view of a semiconductor substrate showing a conventional method for forming an isolation layer using a trench.
- FIG. 15 is a cross-sectional view of the vicinity of an end portion of a reverse blocking IGBT having a separation layer using a conventional trench.
- 14 (a) to 14 (c) are cross-sectional views of the main part of the semiconductor substrate showing the process of forming a separation layer of a conventional reverse blocking IGBT different from that shown in FIG. 12 in the order of steps.
- This formation process is a method in which a trench (groove) 11 is dug from the surface of the semiconductor substrate 1 and a diffusion layer 4 a is formed on the side surface to form the separation layer 4.
- FIG. 14 in the process of forming the semiconductor substrate 1 showing the conventional method for forming an isolation layer using a trench, first, a thick oxide film 2 of several ⁇ m is formed on one surface side of the semiconductor substrate 1 ( FIG. 14 (a)). Next, after forming an opening 3 in the oxide film 2, anisotropic dry etching is performed on the semiconductor substrate 1, and a trench 11 having a depth of about several hundred ⁇ m is formed from the oxide film 2 side where the opening 3 is formed. It forms (FIG.14 (b)).
- Patent Document 1 Such a method of digging the trench 11 and forming the separation layer 4 on the side surface thereof is disclosed in, for example, Patent Documents 1 to 3 below.
- a deep vertical trench that reaches the pn junction on the lower surface side from the upper surface of the device chip is formed so as to surround the device region of the semiconductor element, and a p-type diffusion layer (separation layer) is formed on the side surface of the trench. Is formed and connected to the p-type diffusion layer on the lower side of the device, so that the pn junction on the lower surface side of the device is bent by the separation layer and the junction termination extends to the upper surface of the device. .
- Patent Documents 2 and 3 as in Patent Document 1, by forming a trench reaching the pn junction on the lower surface side from the upper surface of the device, and forming a diffusion layer on the side surface of the trench, a device having reverse blocking capability It is said.
- a boron source (boron liquid diffusion source) is applied from the surface, and boron is subjected to heat treatment. To diffuse.
- the quartz board, quartz tube (quartz tube), quartz nozzle constituting the diffusion furnace are used. The occurrence of defects such as the sag of the quartz jig, contamination from the heater, and strength reduction due to the devitrification phenomenon of the quartz jig is inevitable.
- This mask oxide film requires a high quality and thick oxide film in order to withstand long-time boron diffusion.
- a thermal oxide film is used as a method of obtaining a silicon oxide film having a high mask resistance, that is, a good quality.
- the trench is formed by dry etching, boron is introduced into the formed trench side wall to form the separation layer, and then the trench is formed. Fill with a reinforcing material such as an insulating film to form a high aspect ratio trench.
- a reinforcing material such as an insulating film
- FIG. 16 is a cross-sectional view in the vicinity of an end portion showing a problem of a reverse blocking IGBT having a separation layer using a conventional trench. Further, as shown in FIG. 16, in the separation layer forming process using a deep trench having a high aspect ratio by dry etching, there are sufficient technical problems regarding a method for removing the chemical residue 12 and the resist residue 13 in the trench 11. It has not been resolved. For this reason, there are problems that cause adverse effects such as a decrease in yield and a decrease in reliability.
- the trench sidewall is vertical. Therefore, the dopant is introduced into the trench sidewall by ion implantation with the semiconductor substrate inclined.
- introduction of dopants into trench sidewalls with a high aspect ratio can lead to a decrease in effective dose (according to an increase in implantation time), a decrease in effective projection range, a dose loss due to a screen oxide film, and a decrease in implantation uniformity. Cause harmful effects.
- a gasified dopant zero atmosphere such as PH 3 (phosphine) or B 2 H 6 (diborane) is used instead of ion implantation.
- a vapor phase diffusion method in which a semiconductor substrate is exposed is used.
- the vapor phase diffusion method is inferior in the precise controllability of the dose compared with the ion implantation method.
- a tapered groove (groove formed such that the side surface of the groove has a predetermined inclination angle with respect to the main surface) is formed so that the surface area on the emitter side or the collector side is smaller than the surface area on the other side.
- a separation layer 4b is formed by ion-implanting a chip having a side surface in a wafer state into the side surface of the chip and annealing.
- FIG. 17 is a cross-sectional view of a reverse blocking IGBT having a separation layer on a tapered surface using anisotropic etching.
- a method is known in which a tapered groove is formed by selective anisotropic etching for a chip having a tapered groove inclined in a direction in which the surface area on the emitter side becomes smaller than the surface area on the collector side. (For example, see Patent Documents 4 and 5 below.)
- a reverse blocking IGBT having a tapered side surface inclined in a direction in which the collector-side surface area becomes smaller than the emitter side (See Patent Document 6)
- the surface on the emitter side can be used more widely than the reverse blocking IGBT of FIG. That is, since the area that can be used for the n emitter region 15 and the p base region 16 formed in the vicinity of the emitter side surface is increased, the current density can be increased, and the chip area can be reduced for the same current rating.
- reference numeral 1 denotes a semiconductor substrate
- 6 denotes a collector layer
- 7 denotes a collector electrode.
- the separation layer 4b is formed by ion implantation and annealing, so that there are problems of crystal defects and oxygen-induced defects due to long-time thermal diffusion as described above. Can solve the problem of furnace damage.
- the aspect ratio is lower than that of the manufacturing method by trench deep as shown in FIG. 14 described above, problems such as chemical residue and resist residue as described in FIG. 16 occur when the tapered groove is formed.
- the dopant can be easily introduced by ion implantation into the inclined side surface.
- Patent Document 7 a technique is known in which the activation rate is improved by ion implantation in a state where a semiconductor substrate is heated to 400 ° C. to 500 ° C.
- the separation layer is formed thin (or shallow) because it does not use diffusion for a long time.
- the crystal defects accompanying the ion implantation remain without being sufficiently recovered by the annealing process, the crystal defects remain in the vicinity of the pn junction of the separation layer, so that the leakage current during reverse bias increases.
- the reverse withstand voltage designed to obtain a predetermined blocking voltage is likely to decrease.
- the focal position (the position that contributes effectively to the activation of the separation layer of the tapered groove during the lamp annealing process) must be controlled properly. Similarly, there is a problem that the activation of the separation layer becomes insufficient and crystal defects remain.
- the present invention has been made in view of the above points.
- a tapered groove is formed, and a diffusion layer formed by ion implantation and annealing treatment is formed on the side surface of the diffusion layer so that the end of the reverse breakdown voltage pn junction is curved.
- a method for manufacturing a reverse blocking semiconductor element capable of ensuring a reverse breakdown voltage and reducing a leakage current at the time of reverse bias even in a manufacturing method having a manufacturing process of forming a separation layer for extending to the surface. For the purpose.
- the present invention provides a step of forming a main surface structure including a MOS gate structure on one main surface of a first conductivity type semiconductor substrate, and a second conductivity type collector layer on the other main surface. And connecting the two main surfaces along the side surface of the tapered groove formed by etching from one main surface to the other main surface, on the outer periphery surrounding the main surface structure.
- the second conductivity type impurity element is ion-implanted in a state where the semiconductor substrate is held at any temperature of 400 ° C. to 500 ° C., and laser annealing treatment and 350 ° C. are performed.
- the reverse blocking semiconductor element is a step of forming both the second conductivity type collector layer and the second conductivity type separation layer by performing both annealing treatment and furnace annealing treatment at any temperature of up to 500 ° C. Let it be a manufacturing method.
- both of the annealing processes may be a process in which a laser annealing process is performed first, and then a furnace annealing process at any temperature of 350 ° C. to 500 ° C. is performed in that order. it can.
- both of the annealing treatments may be processing in which a furnace annealing treatment at a temperature of 350 ° C. to 500 ° C. is performed first, and then laser annealing treatment is performed in this order. preferable.
- the step of forming the second conductivity type collector layer and the second conductivity type separation layer is simultaneously performed in the above invention.
- the furnace annealing treatment can be held for 1 hour to 10 hours.
- the tapered groove is formed, and the diffusion layer formed on the side surface by ion implantation and annealing is used as the separation layer for extending the end of the reverse breakdown voltage pn junction to the surface. Even in a manufacturing method having a manufacturing process, it is possible to provide a manufacturing method of a reverse blocking semiconductor element capable of ensuring a reverse breakdown voltage and reducing a leakage current at the time of reverse bias.
- FIG. 1 is a cross-sectional view of a semiconductor substrate showing main manufacturing steps according to the method of manufacturing a reverse blocking semiconductor element of the present invention.
- FIG. 2 is an impurity concentration profile diagram of the collector layer and the separation layer according to the first embodiment of the present invention.
- FIG. 3 is an impurity concentration profile diagram of the collector layer and the separation layer according to the second exemplary embodiment of the present invention.
- FIG. 4A is a cross-sectional view (part 1) of the semiconductor substrate showing a direction of ion implantation for forming a separation layer on a tapered surface.
- FIG. 4-2 is a sectional view (No. 2) of the semiconductor substrate showing the direction of ion implantation for forming the separation layer on the tapered surface.
- FIG. 1 is a cross-sectional view of a semiconductor substrate showing main manufacturing steps according to the method of manufacturing a reverse blocking semiconductor element of the present invention.
- FIG. 2 is an impurity concentration profile diagram of the collector layer and the separation layer according to the first embodiment of the
- FIG. 5 is an impurity concentration profile diagram (conventional example) of a separation layer formed by activating the ion-implanted region on the tapered surface by a conventional laser annealing process.
- FIG. 6 is a cross-sectional view (conventional example) showing the remaining state of crystal defects when the ion-implanted region on the tapered surface is activated by a conventional laser annealing process, where (a) is the collector layer and (b) is the collector layer. It is sectional drawing which shows the crystal defect state of a separated layer.
- FIG. 7 is a reverse current-voltage waveform diagram of the present invention, a comparative example, and a conventional reverse blocking IGBT (comparative example).
- FIGS. 8A and 8B are impurity concentration profile diagrams of the collector layer and the separation layer according to Comparative Example 1.
- FIGS. 8A and 8B show the case where the substrate temperature during ion implantation is 400 ° C. + furnace annealing
- FIGS. ) Are impurity concentration profile diagrams of the collector layers (a) and (c) and the separation layers (b) and (d), respectively, in the case of the substrate temperature at the time of ion implantation of 500 ° C. + furnace annealing.
- FIGS. 9A and 9B are cross-sectional views showing the remaining state of crystal defects according to Comparative Example 1.
- FIGS. 9A and 9B are substrate temperatures at the time of ion implantation of 400 ° C.
- FIG. 10 is a cross-sectional view showing the remaining state of crystal defects according to Comparative Example 1.
- (a) and (b) are substrate temperatures during ion implantation at 400 ° C.
- (c) and (d) are It is sectional drawing which shows the crystal defect state of a collector layer and a separated layer in the case of the process of the substrate temperature at the time of 500 degreeC ion implantation, respectively.
- FIG. 10 is a cross-sectional view showing the remaining state of crystal defects according to Comparative Example 1.
- (a) and (b) are substrate temperatures during ion implantation at 400 ° C.
- (c) and (d) are It is sectional drawing which shows the crystal defect state of a collector layer and a separated layer in the case of the process of the substrate temperature at the time of 500 degreeC ion implantation, respectively.
- FIG. 11 is a cross-sectional view of the separation layer portion showing the remaining state of crystal defects according to Comparative Example 2, wherein (a) and (b) are substrate temperatures at the time of ion implantation of 400 ° C., (c), (D) is sectional drawing which shows the crystal defect state of a collector layer and a separation layer in the case of the process of the substrate temperature at the time of ion implantation of 500 degreeC, respectively.
- FIG. 12 is a fragmentary cross-sectional view of a semiconductor substrate showing a conventional method for forming a separation layer by coating diffusion.
- FIG. 13 is a cross-sectional view of the vicinity of an end portion of a reverse blocking IGBT having a separation layer formed by conventional coating diffusion.
- FIG. 14 is a fragmentary cross-sectional view of a semiconductor substrate illustrating a conventional method for forming an isolation layer using a trench.
- FIG. 15 is a cross-sectional view of the vicinity of an end portion of a reverse blocking IGBT having a separation layer using a conventional trench.
- FIG. 16 is a cross-sectional view in the vicinity of an end portion showing a problem of a reverse blocking IGBT having a separation layer using a conventional trench.
- FIG. 17 is a cross-sectional view of a reverse blocking IGBT having a separation layer on a tapered surface using anisotropic etching.
- FIG. 18 is an enlarged cross-sectional view of a tapered groove showing a region A where crystal defects are likely to remain on the side surface of the separation layer.
- n-type is used as the first conductivity type
- p-type is used as the second conductivity type.
- One main surface is the emitter side or surface of the IGBT, and the other main surface is the collector side or back surface of the IGBT.
- an n-type reverse blocking IGBT is taken as a reverse blocking semiconductor element according to the present invention, and in particular, a side surface derived from a tapered groove in such a direction that the surface area on the collector side is smaller than the surface area on the emitter side.
- a general method for manufacturing the formed reverse blocking IGBT will be described. The same manufacturing process as in the prior art will be described as simply as possible.
- Examples 1 and 2 to be described later is a detailed description of the characteristic part of the present invention and the effect of the invention related to the characteristic part.
- an annealing method for forming both the p-type collector layer and the separation layer by ion implantation according to the characteristic part of the present invention, and subsequently performing both the laser annealing process and the furnace annealing process is based on the conventional example and the comparative examples 1 and 2. It will be described while clarifying that the present invention has an excellent effect by mutual comparison with each effect.
- FIG. 1 is a cross-sectional view of a semiconductor substrate showing main manufacturing steps according to the method of manufacturing a reverse blocking semiconductor element of the present invention.
- a surface layer whose main surface is the (001) plane of the FZ-n semiconductor substrate hereinafter referred to as “semiconductor substrate” 1 shown in FIG.
- semiconductor substrate As shown in FIG. 1B, a p base region 16 and an n emitter region 15 are formed in the device active region where the main current flows in the device region.
- the n emitter region 15 is formed in the p base region 16.
- a gate electrode 22 is formed on the surface of the semiconductor substrate 1 and the surface of the p base region 16 sandwiched between the n emitter regions 15 through a gate insulating film 21 to form a MOS gate structure.
- an emitter electrode 24 that is in contact with the p base region 16 and the n emitter region 15 is further provided to form the surface structure 10 of the reverse blocking IGBT.
- the emitter electrode 24 is formed by, for example, coating an Al / Si film by sputtering or the like and then heat-treating the Al / Si film at 400 ° C. to 500 ° C.
- a different alkaline etchant such as a KOH aqueous solution or a 5% solution of TMAH (Tetra Methyl Ammonium Hydroxide)
- TMAH Tetra Methyl Ammonium Hydroxide
- the etching mask pattern is formed so that the above-described reverse blocking IGBT MOS gate structure is arranged on the surface side of the region surrounded by the tapered groove.
- a support plate (not shown) on the surface side so that the device chips are not dispersed even after the etching is finished.
- the depth of the tapered groove can be made shallower than the thickness of the semiconductor substrate 1 so that the process without the support plate can be performed.
- ion implantation of the p-type collector layer 6 and the separation layer 4 formed from the back side of the semiconductor substrate 1 is performed by an oxide film mask (not shown) having a low-temperature oxide film opened in a desired region. ) Is performed on the side surface and main surface of the tapered groove.
- oxide film mask not shown
- the substrate temperature at the time of ion implantation into the separation layer 4 is 400 to 500 ° C., respectively.
- boron dose is set to 1 ⁇ 10 15 cm ⁇ 2 and acceleration voltage is set to 150 keV. Thereafter, furnace annealing and laser annealing are performed in this order or reverse order as annealing treatment.
- the irradiation energy density of a YAG2 ⁇ laser (wavelength 532 nm; pulse width 100 ns) is 3 J / cm 2 , and the furnace annealing condition is 350 ° C. to 500 ° C. for 1 to 10 hours.
- FIGS. 4A and 4B are cross-sectional views of the semiconductor substrate showing the direction of ion implantation for forming the separation layer on the tapered surface.
- a rectangular chip for example, as shown in FIG. 4A, it is possible to form a mask 2 on the main surface and perform ion implantation on the four side surfaces at once.
- each ion implantation into the four side surfaces is tapered with the side surfaces inclined with respect to the main surface.
- the tilt of the semiconductor substrate is changed, and the substrate is rotated 90 degrees for each of the four side surfaces and implanted four times to perform doping from the taper angle and another tilt. it can.
- a control such as a mask such as SUS (stainless steel) or a shutter (shielding plate).
- Furnace annealing using an electric furnace maintained at a constant temperature is performed on the emitter-side surfaces such as the n emitter region 15, the p base region 16, the gate insulating film 21, the gate electrode 22, and the emitter electrode 24 formed in the preceding process.
- the annealing is performed at a low temperature that does not adversely affect the structure, and in a temperature range of 350 ° C. to 500 ° C. where an annealing effect for activation is effective.
- the collector electrode 7 is formed by vapor-depositing a sputtered metal film made of a laminate of Al / Ti / Ni / Au on the surface of the collector layer 6.
- the collector electrode 7 is provided on the surface of the collector layer 6, the metal electrode on the side surface of the tapered shape is removed on the surface, and the reverse blocking type is obtained by cutting at the center of the tapered groove or removing the support plate.
- An IGBT chip can be made.
- the manufacturing method including the step of forming the diffusion layer (separation layer 4) only on the four side surfaces of the device chip as described above is tapered in a direction in which the surface area on the emitter side is smaller than the surface area on the collector side.
- the present invention can be similarly applied to a reverse blocking IGBT in which a side surface is formed.
- the collector layer 6 and the separation layer 4 can be simultaneously performed without ion implantation and annealing.
- the lithography process and the ion implantation process for mask formation can be omitted once compared to the case where the collector layer 6 and the separation layer 4 are separately ion-implanted and annealed. This is preferable because the cost can be reduced.
- the energy density in the laser annealing process on the tapered surface when forming the separation layer is also 0.58 times the energy density irradiated in the annealing process on the collector surface. Therefore, it is necessary to set conditions for ion implantation and laser annealing in consideration of these 0.58 times in advance.
- the separation layer 4 is formed by ion implantation of boron from the back surface
- the substrate temperature at the time of ion implantation is set to room temperature
- the ion implantation is performed with a boron dose of 1 ⁇ 10 15 cm ⁇ 2 and an acceleration voltage of 150 keV.
- the subsequent annealing treatment is only laser annealing treatment.
- the laser annealing treatment condition is a YAG2 ⁇ laser (wavelength 532 nm; pulse width 100 ns) irradiation energy density, 3 J / cm 2 .
- FIG. 5 shows the measurement result (spreading resistance measurement result) of the SR concentration profile of the formed collector layer 6 and the simultaneously formed separation layer 4.
- FIG. 5 is an impurity concentration profile diagram (conventional example) of a separation layer formed by activating the ion-implanted region on the tapered surface by a conventional laser annealing process.
- FIG. 6 is a cross-sectional view (conventional example) showing the remaining state of crystal defects when the ion-implanted region on the tapered surface is activated by a conventional laser annealing process, where (a) is the collector layer and (b) is the collector layer. It is sectional drawing which shows the crystal defect state of a separated layer.
- FIG. 6 shows crystal defects 20 (point defects) of the collector layer 6 and the separation layer 5 (side surface) when irradiated under the ion implantation and laser annealing treatment conditions of this conventional example.
- FIG. 7 is a reverse current-voltage waveform diagram of the present invention, a comparative example, and a conventional reverse blocking IGBT (comparative example).
- the leakage current hereinafter referred to as reverse leakage current
- FIG. 7 Shown in comparison.
- (a) is a current-voltage waveform of a conventional example
- (b) is Comparative Example 1
- (c) is Comparative Example 2
- (d) is Embodiment 1
- (e) is Embodiment 2.
- the substrate temperatures at the time of ion implantation into the separation layer were 400 ° C. and 500 ° C. (room temperature in the conventional example), respectively, and the annealing treatment was a furnace annealing treatment (Comparative Example 1). ) Or laser annealing treatment (Comparative Example 2).
- the first and second embodiments are the same as the first and second comparative examples in that the temperatures at the time of ion implantation into the separation layer are 400 ° C. and 500 ° C., respectively.
- the process is characterized by an annealing process in which two types of annealing are combined, such as an annealing process in the order of the treatment and the furnace annealing process or vice versa.
- Comparative Examples 1 and 2 are incorporated in the description of the present invention as described above is that the first and second embodiments are characterized in that the annealing treatment is a combination of two types of laser annealing treatment and furnace annealing treatment.
- the substrate temperature rise at the time of ion implantation and the annealing treatment of the present invention are overlapped and unclear about the part of activation and reduction of crystal defects. is there.
- the peak concentration of the device according to the conventional example exceeds 1 ⁇ 10 19 cm ⁇ 3 in both the collector layer and the separation layer and is sufficiently activated. You can see that This is an effect of the laser annealing treatment.
- the diffusion depth shown on the horizontal axis of FIG. 5 is shallower than the SR concentration profiles (FIGS. 2 and 3) of the first and second embodiments described later.
- the crystal defect 20 does not remain in the collector layer as shown in (a), but is formed incidentally on the side surface (separation layer) during ion implantation as shown in (b). It is shown that crystal defects 20 (point defects) remain.
- the reverse current is caused by the residual crystal defects described later.
- the reverse current is larger than (d) and (e) showing the waveforms of the first and second embodiments that are not in the separation layer.
- there is a residual crystal defect on the side surface (separation layer) which means that the crystal defect formed with the ion implantation into the side surface of the separation layer is not easily recovered by laser annealing. This is a result of reflecting.
- the laser annealing process performed from the back surface of the substrate is laser irradiation for a short time (several tens to several ⁇ s), and the focal position of the irradiation does not coincide with the separation layer, and deviation tends to occur.
- the laser annealing process performed from the back surface of the substrate has an advantage in that the irradiation region does not adversely affect the surface structure of the device because the irradiation region is not limited to the entire separation layer but tends to stay in part.
- the region of the effect of recovering the crystal defects is also limited, and it is considered that the defect recovery in the region near the surface side of the separation layer formed in the tapered portion tends to be insufficient, and the reverse leakage current is increased. .
- Comparative Example 1 (Description of Manufacturing Method for Comparative Example 1)
- boron is implanted into the back surface of the FZ-n substrate heated to 400 ° C. to 500 ° C.
- the annealing process is a process for performing a furnace annealing process.
- an FZ-n substrate is placed on a sample stage equipped with a substrate heating mechanism such as a heater with the surface side (side on which the surface electrode is formed) facing down, and this is placed at a predetermined temperature (400 ° C. to 400 ° C.).
- the conditions for the furnace annealing treatment were 400 ° C. and 5 hours.
- FIGS. 8A and 8B are impurity concentration profile diagrams of the collector layer and the separation layer according to Comparative Example 1.
- FIGS. 8A and 8B show the case where the substrate temperature during ion implantation is 400 ° C. + furnace annealing
- FIGS. ) Are impurity concentration profile diagrams of the collector layers (a) and (c) and the separation layers (b) and (d), respectively, in the case of the substrate temperature at the time of ion implantation of 500 ° C. + furnace annealing.
- the horizontal axis represents the depth ( ⁇ m) of the boron ion implantation region from the back surface of the FZ-n substrate, and the vertical axis represents the boron concentration (cm ⁇ 3 ) in the boron ion implantation region.
- the boron ion implantation condition is that the semiconductor substrate 1 is heated at 400 ° C. and 500 ° C., and boron is ion-implanted on the back surface at a dose of 1 ⁇ 10 15 cm ⁇ 2 and an acceleration energy of 150 keV.
- the activation rate of the boron ion implantation layer is about 2% when the ion implantation temperature by the substrate heating is 400 ° C. and about when the ion implantation temperature is 500 ° C. 5%. It is not preferable to set the ion implantation temperature to 500 ° C. or higher because the emitter electrode made of Al / Si may be dissolved.
- the peak concentration is 1 ⁇ 10 17 cm ⁇ 3 to 7 ⁇ 10 18 cm ⁇ 3 , which is lower than that in FIG.
- the low concentration is due to furnace annealing in which the degree of activation is lower than that of the conventional annealing process (laser annealing process) of FIG.
- the depth of the boron ion implantation layer is a little deeper in the collector layer and the separation layer than in the conventional example of FIG. 6 because of the substrate temperature heating at the time of ion implantation and the furnace annealing treatment at 400 ° C. Show.
- FIGS. 9A and 9B are cross-sectional views showing the remaining state of crystal defects according to Comparative Example 1.
- FIGS. 9A and 9B are substrate temperatures at the time of ion implantation of 400 ° C.
- FIGS. It is sectional drawing which shows the crystal defect state of a collector layer and a separated layer in the case of the process of the substrate temperature at the time of 500 degreeC ion implantation, respectively. From FIG. 9, comparing 400 ° C. and 500 ° C. in the furnace annealing treatment shows that the crystal defects are smaller at 500 ° C., so that the substrate heating during ion implantation contributes to the reduction of crystal defects. Is shown.
- the comparative example 1 according to FIG. 9 has fewer crystal defects. Since the number of crystal defects is reduced as described above, the reverse leakage current is compared with the conventional example (FIG. 7A) in comparison example 1 (FIG. 7B) as shown in FIGS. 7A and 7B. ) Becomes smaller.
- the comparative example 2 is different from the process of the comparative example 1 in that the annealing process is changed from the furnace annealing process to the laser annealing process, and the other processes are the same.
- Conditions of the laser annealing process the same, YAG2omega laser as laser annealing conditions of the conventional example described above, an irradiation energy density (wavelength 532nm Pulse width 100 ns), the conditions of 3J / cm 2.
- FIG. 10 is a cross-sectional view showing the remaining state of crystal defects according to Comparative Example 1.
- (a) and (b) are substrate temperatures during ion implantation at 400 ° C.
- (c) and (d) are It is sectional drawing which shows the crystal defect state of a collector layer and a separated layer in the case of the process of the substrate temperature at the time of 500 degreeC ion implantation, respectively.
- Comparative Example 2 since the heating at 400 ° C. and 500 ° C.
- the impurity concentration of the collector layer and the separation layer is not only higher than that of Comparative Example 1, but also the above-mentioned diagram of the conventional example. It can be seen that it is slightly higher than the impurity concentration of 6.
- the comparative example 2 is more activated than the conventional example and the comparative example 1.
- the diffusion depth it can be seen that by performing ion implantation while heating, both the collector layer and the separation layer have a diffusion effect and become slightly deeper than the ion implantation of the conventional example without heating (FIG. 5).
- the crystal defects in FIG. 12 of Comparative Example 2 it is considered that the heating during ion implantation contributes to the reduction of the crystal defects on the deep side from the comparison between FIG. 6 (conventional example) and FIG. 11 (Comparative Example 2).
- FIGS. 11A and 11C show that there is no crystal defect in the collector layer (back surface).
- FIGS. 9B and 9D show that the point defect in FIG. 11B and FIG. The decrease is considered to be due to the recovery of the crystal defects in the central part from the upper part of the side surface having the separation layer. It seems that the effect of heating and furnace annealing during ion implantation appears.
- the reverse current (reverse leakage current) of the comparative example 2 (FIG. 7C) is compared with the conventional example of the laser annealing process of FIG. 7A and the comparative example 1 (FIG. 7B). You can see that it is smaller. This is presumably because the leakage current at the time of reverse bias is reduced because the recovery of crystal defects accompanying the ion implantation into the side surface of the separation layer is effective.
- FIG. 1 A first embodiment according to the reverse blocking IGBT of the present invention will be described.
- ion implantation is performed while heating the semiconductor substrate 1 during ion implantation.
- the feature of the reverse blocking semiconductor element manufacturing method according to the first embodiment is that both the laser annealing process and the furnace annealing process are performed in this order for activation.
- FIG. 2 is an impurity concentration profile diagram of the collector layer and the separation layer according to the first exemplary embodiment of the present invention.
- the boron dose is 1 ⁇ 10 15 cm ⁇ 2
- the acceleration voltage is 150 keV
- the semiconductor substrate temperatures during ion implantation are 400 ° C. ((a), (b)) and 500 ° C. ((c) , (D))
- the SR concentration profile measurement results (spreading resistance measurement results) on the side surfaces of the collector layers ((a), (c)) and the separation layers ((b), (d)). Show.
- the laser annealing treatment conditions a YAG 2 ⁇ laser (wavelength 532 nm; pulse width 100 ns) is used, and the irradiation energy density is set to 3.0 J / cm 2 .
- the furnace annealing treatment conditions were a temperature of 400 ° C./5 hours. As described above, the laser annealing treatment was performed first, and then the furnace annealing treatment was performed under the above-described conditions.
- the peak concentration is a high concentration exceeding 1 ⁇ 10 19 cm ⁇ 3 for both the back surface (collector layer 6) and the separation layer 4 and is sufficiently activated.
- the peak concentration is the same level as in Comparative Example 2 (FIG. 11).
- the diffusion depth adds a diffusion effect by using substrate heating at the time of ion implantation, laser annealing treatment, and furnace annealing treatment. Therefore, the diffusion depth is deeper than that of the conventional example and the comparative examples 1 and 2, particularly near 0.6 ⁇ m. It shows that it is deeper.
- ion implantation is performed while heating the semiconductor substrate 1 to 400 ° C. to 500 ° C. during ion implantation.
- furnace annealing is performed first, followed by laser annealing.
- FIG. 3 is an impurity concentration profile diagram of the collector layer and the separation layer according to the second exemplary embodiment of the present invention.
- the dose amount of boron is 1 ⁇ 10 15 cm ⁇ 2
- the acceleration voltage is 150 keV
- the ion implantation temperatures are 400 ° C. ((a), (b)) and 500 ° C. ((c), (d ))
- the furnace annealing treatment condition is 400 ° C./5 hours.
- the laser annealing treatment conditions were YAG2 ⁇ laser (wavelength 532 nm; pulse width 100 ns), and the irradiation energy density of laser annealing treatment was 3.0 J / cm 2 . Further, furnace annealing was performed first, and then laser annealing was performed under the above-described conditions.
- the peak concentration is seen to have been collector layer, sufficiently activated becomes 1 ⁇ 10 19 cm -3 or more high concentration in both the separation layer.
- the peak concentration is the same level as in Comparative Example 2 (FIG. 11) and Example 1 (FIG. 2).
- the diffusion depth adds a diffusion effect by using the substrate heating at the time of ion implantation, furnace annealing treatment and laser annealing treatment, so that it is deeper than the above-mentioned conventional examples, comparative examples 1 and 2 and example 1, especially 0. It can be seen that the depth around .6 ⁇ m is particularly deep.
- the diffusion depth is deeper than that in the first embodiment.
- the laser annealing treatment is performed first, so that the irradiation outermost surface is fixed. This is because the phase is melted, the reflection of the laser light is increased, and the dopant is difficult to diffuse in the depth direction.
- Embodiments 1 and 2 it is more effective for activation of the deeper layer when furnace annealing is performed and a dopant is added deeply by low-temperature diffusion and then laser annealing is performed.
- the peak concentration is located deeper than in the first embodiment because the furnace annealing process is performed first so that it is in a state of being easily diffused. It is because it becomes easy to become.
- n-type reverse blocking IGBT in which boron ions are diffused in the separation layer has been described, but aluminum can be used as impurity ions instead of boron.
- phosphorus ions may be used as a dopant for the separation layer.
- the laser annealing process used for the annealing process in the first and second embodiments described above has been described using a YAG2 ⁇ laser as an all-solid-state laser.
- a laser such as An excimer laser such as XeCl (308 nm), KrF, or XeF may be used instead of the all solid-state laser.
- the use of a semiconductor laser having a long penetration depth into the silicon semiconductor substrate is effective in recovering defects in the implanted layer on the deeper side.
- the semiconductor substrate is heated at the time of ion implantation to perform the ion implantation in a state where the temperature of the semiconductor substrate is raised, and further, furnace annealing treatment and laser annealing treatment are performed at 350 ° C. to 500 ° C. for 1 hour to 10 hours.
- furnace annealing treatment and laser annealing treatment are performed at 350 ° C. to 500 ° C. for 1 hour to 10 hours.
- the reverse is provided with the taper of the structure in which the region A in which the defects are not sufficiently recovered exists even when the laser annealing process as described above is used. Even in the manufacturing method of the blocking semiconductor element, the reverse breakdown voltage is not reduced, the yield rate is improved, and the chip cost can be reduced.
- the method of manufacturing a reverse blocking semiconductor device normally has an insulated gate bipolar transistor (hereinafter abbreviated as IGBT), which usually has a reliability of only forward voltage blocking capability. ),
- IGBT insulated gate bipolar transistor
- the reverse voltage blocking capability (hereinafter abbreviated as reverse blocking capability) is also useful for a method of manufacturing a reverse blocking semiconductor element that maintains the same reliability as the forward voltage blocking capability (abbreviated as forward blocking capability). It is suitable for the manufacturing method of reverse blocking IGBT.
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Abstract
Description
裏面からのボロンのイオン注入により分離層4を形成する際に、イオン注入時の基板温度を室温とし、イオン注入を、ボロンのドーズ量を1×1015cm-2,加速電圧を150keVとして行なう。続くアニール処理は、レーザーアニール処理のみとする。レーザーアニール処理条件は、YAG2ωレーザー(波長532nm;パルス幅100ns)の照射エネルギー密度、3J/cm2の条件で行なう。
比較例1では、前述の従来例と異なり、基板の裏面側プロセスでpコレクタ層を形成する際に、FZ-n基板を400℃~500℃に加熱した状態で、その裏面にボロンを注入し、アニール処理は炉アニール処理を行うプロセスである。たとえば、ヒータ等の基板加熱機構を備えた試料台の上にFZ-n基板をその表面側(表面電極が形成されている側)を下にして載置し、これを所定温度(400℃~500℃)で加熱するとともに、半導体基板(FZ-n半導体基板)1の裏面側(pコレクタ層を形成する側)から、ボロンのイオン注入を行うプロセスとする。炉アニール処理の条件は、400℃で、5時間とした。
比較例2は前記比較例1のプロセスのうち、アニール処理を炉アニール処理からレーザーアニール処理に変更したことが異なり、その他のプロセスは同じである。レーザーアニール処理の条件は、前述の従来例のレーザーアニール処理条件と同じ、YAG2ωレーザー(波長532nm;パルス幅100ns)の照射エネルギー密度、3J/cm2の条件である。
本発明の逆阻止型IGBTにかかる実施の形態1について説明する。コレクタ層6および分離層4におけるイオン注入層を活性化するために、イオン注入時に半導体基板1を加熱しながらイオン注入をおこなう。そして、さらに、活性化のためにレーザーアニール処理と炉アニール処理との両方のアニール処理を、この順に、行うところが実施の形態1にかかる逆阻止型半導体素子の製造方法の特徴部分である。
つぎに、本発明の逆阻止型IGBTにかかる実施の形態2について説明する。コレクタ層6および分離層4のイオン注入層を活性化するためにイオン注入時に半導体基板1を400℃~500℃に加熱しながらイオン注入をおこなう。そして、更に活性化のために先に炉アニール処理、その後、レーザーアニール処理を行う。
2 酸化膜マスク
3 開口部
4、4b 分離層
4a 拡散層
5 ボロンソース
6 pコレクタ層
7 コレクタ電極
8 スクライブライン
10 表面構造
11 トレンチ
12 薬液残渣
13 レジスト残渣
15 nエミッタ領域
16 pベース領域
20 結晶欠陥
21 ゲート絶縁膜
22 ゲート電極
23 層間絶縁膜
24 エミッタ電極
Claims (5)
- 第1導電型の半導体基板の一方の主面にMOSゲート構造を含む主要表面構造を形成する工程と、他方の主面に第2導電型コレクタ層を形成する工程と、前記主要表面構造を取り巻く外周にあって、いずれか一方の主面から他方の主面にかけてエッチング形成されるテーパー溝の側辺面に沿って、前記両主面間を連結するとともに前記他方の主面の第2導電型コレクタ層に接続される第2導電型分離層を形成する工程とを有する逆阻止型半導体素子の製造方法において、前記第2導電型コレクタ層と前記第2導電型分離層とを形成する工程がそれぞれ前記半導体基板を400℃乃至500℃のいずれかの温度に保持した状態で第2導電型不純物元素をイオン注入し、レーザーアニール処理と350℃乃至500℃のいずれかの温度による炉アニール処理との両方のアニール処理を行って前記第2導電型コレクタ層と前記第2導電型分離層とをそれぞれ形成する工程であることを特徴とする逆阻止型半導体素子の製造方法。
- 前記両方のアニール処理を、レーザーアニール処理を先にして、その後、350℃乃至500℃のいずれかの温度による炉アニール処理の順に行うことを特徴とする請求項1記載の逆阻止型半導体素子の製造方法。
- 前記両方のアニール処理を、350℃乃至500℃のいずれかの温度による炉アニール処理を先にして、その後、レーザーアニール処理の順に行うことを特徴とする請求項1記載の逆阻止型半導体素子の製造方法。
- 前記第2導電型コレクタ層と前記第2導電型分離層とを形成する工程が同時に行われることを特徴とする請求項1乃至3のいずれか一項に記載の逆阻止型半導体素子の製造方法。
- 前記350℃乃至500℃のいずれかの温度による炉アニール処理の保持時間を1時間乃至10時間とすることを特徴とする請求項1記載の逆阻止型半導体素子の製造方法。
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US13/980,048 US8853009B2 (en) | 2011-01-18 | 2012-01-16 | Method for manufacturing reverse-blocking semiconductor element |
JP2012553716A JP5692241B2 (ja) | 2011-01-18 | 2012-01-16 | 逆阻止型半導体素子の製造方法 |
DE112012000501T DE112012000501T5 (de) | 2011-01-18 | 2012-01-16 | Verfahren zur Herstellung eines rückwärts sperrenden Halbleiterelements |
CN201280005473XA CN103329255A (zh) | 2011-01-18 | 2012-01-16 | 反向阻断型半导体元件的制造方法 |
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JP (1) | JP5692241B2 (ja) |
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JP7339819B2 (ja) * | 2019-09-04 | 2023-09-06 | 株式会社東芝 | 半導体装置の製造方法および半導体装置 |
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JP2003059856A (ja) * | 2001-08-09 | 2003-02-28 | Fuji Electric Co Ltd | 半導体装置の製造方法 |
JP2005268487A (ja) * | 2004-03-18 | 2005-09-29 | Fuji Electric Device Technology Co Ltd | 半導体素子の製造方法および半導体素子の製造装置 |
JP2006303410A (ja) * | 2005-03-25 | 2006-11-02 | Fuji Electric Holdings Co Ltd | 半導体装置およびその製造方法 |
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US4904609A (en) | 1988-05-06 | 1990-02-27 | General Electric Company | Method of making symmetrical blocking high voltage breakdown semiconductor device |
JP4696337B2 (ja) | 1999-10-15 | 2011-06-08 | 富士電機システムズ株式会社 | 半導体装置 |
JP4788028B2 (ja) | 2000-08-28 | 2011-10-05 | 富士電機株式会社 | 逆阻止型igbtを逆並列に接続した双方向igbt |
JP4747260B2 (ja) | 2003-04-16 | 2011-08-17 | 富士電機株式会社 | 逆阻止型絶縁ゲート形バイポーラトランジスタの製造方法 |
US7776672B2 (en) * | 2004-08-19 | 2010-08-17 | Fuji Electric Systems Co., Ltd. | Semiconductor device and manufacturing method thereof |
JP4982948B2 (ja) | 2004-08-19 | 2012-07-25 | 富士電機株式会社 | 半導体装置の製造方法 |
DE102008003953A1 (de) | 2007-02-28 | 2008-09-04 | Fuji Electric Device Technology Co. Ltd. | Verfahren zur Herstellung eines Halbleiterelements |
JP5668270B2 (ja) | 2008-12-11 | 2015-02-12 | 富士電機株式会社 | 半導体素子の製造方法 |
JP2010212530A (ja) | 2009-03-12 | 2010-09-24 | Fuji Electric Systems Co Ltd | 半導体素子の製造方法 |
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JP2003059856A (ja) * | 2001-08-09 | 2003-02-28 | Fuji Electric Co Ltd | 半導体装置の製造方法 |
JP2005268487A (ja) * | 2004-03-18 | 2005-09-29 | Fuji Electric Device Technology Co Ltd | 半導体素子の製造方法および半導体素子の製造装置 |
JP2006303410A (ja) * | 2005-03-25 | 2006-11-02 | Fuji Electric Holdings Co Ltd | 半導体装置およびその製造方法 |
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US20130295729A1 (en) | 2013-11-07 |
US8853009B2 (en) | 2014-10-07 |
CN103329255A (zh) | 2013-09-25 |
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