WO2017158747A1 - Epitaxial substrate manufacturing method and semiconductor device manufacturing method - Google Patents

Epitaxial substrate manufacturing method and semiconductor device manufacturing method Download PDF

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WO2017158747A1
WO2017158747A1 PCT/JP2016/058239 JP2016058239W WO2017158747A1 WO 2017158747 A1 WO2017158747 A1 WO 2017158747A1 JP 2016058239 W JP2016058239 W JP 2016058239W WO 2017158747 A1 WO2017158747 A1 WO 2017158747A1
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substrate
epitaxial
forming
outer peripheral
bulk
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PCT/JP2016/058239
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French (fr)
Japanese (ja)
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渡辺　直樹
広行 吉元
廉一 山田
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株式会社日立製作所
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Priority to PCT/JP2016/058239 priority Critical patent/WO2017158747A1/en
Priority to JP2018505125A priority patent/JP6507308B2/en
Publication of WO2017158747A1 publication Critical patent/WO2017158747A1/en

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    • 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
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/66007—Multistep manufacturing processes
    • H01L29/66053—Multistep manufacturing processes of devices having a semiconductor body comprising crystalline silicon carbide
    • H01L29/66068—Multistep manufacturing processes of devices having a semiconductor body comprising crystalline silicon carbide 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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    • H01L29/66234—Bipolar junction transistors [BJT]
    • H01L29/66325—Bipolar junction transistors [BJT] controlled by field-effect, e.g. insulated gate bipolar transistors [IGBT]
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    • H01L29/66409—Unipolar field-effect transistors
    • H01L29/66477—Unipolar field-effect transistors with an insulated gate, i.e. MISFET
    • H01L29/66674—DMOS transistors, i.e. MISFETs with a channel accommodating body or base region adjoining a drain drift region
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/70—Bipolar devices
    • H01L29/72—Transistor-type devices, i.e. able to continuously respond to applied control signals
    • H01L29/739—Transistor-type devices, i.e. able to continuously respond to applied control signals controlled by field-effect, e.g. bipolar static induction transistors [BSIT]
    • H01L29/7393—Insulated gate bipolar mode transistors, i.e. IGBT; IGT; COMFET
    • H01L29/7395—Vertical transistors, e.g. vertical IGBT
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/7801—DMOS transistors, i.e. MISFETs with a channel accommodating body or base region adjoining a drain drift region
    • H01L29/7802—Vertical DMOS transistors, i.e. VDMOS transistors
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    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic System
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    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
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    • H01L29/20—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only AIIIBV compounds
    • H01L29/2003—Nitride compounds

Definitions

  • the present invention particularly relates to a method for manufacturing an epitaxial substrate that suppresses substrate cracks from the outer peripheral edge of the substrate, and a method for manufacturing a semiconductor device using the same.
  • the thickness of the drift layer can be reduced to 1/10 of Si in the case of a power semiconductor device having the same breakdown voltage.
  • the drift layer resistance can be greatly reduced, so that the on-resistance of the entire element can be reduced.
  • SiC and GaN semiconductor devices include unipolar Schottky barrier diodes (Schottky Barrier Diodes: SBDs) and power MOSFETs (Metal Oxide Field Effect Transistors), bipolar devices such as PN diodes and insulated gate bipolar transistors (Insulated Gate Bipolar Transistor: IGBT)
  • SBDs Schottky Barrier Diodes
  • MOSFETs Metal Oxide Field Effect Transistors
  • bipolar devices such as PN diodes and insulated gate bipolar transistors (Insulated Gate Bipolar Transistor: IGBT)
  • IGBT Insulated Gate Bipolar Transistor
  • the above-described power semiconductor element is generally manufactured using an epitaxial substrate obtained by epitaxially growing a semiconductor material on a bulk substrate.
  • FIG. 3 shows the main steps of a general epitaxial substrate manufacturing process flow. Turn the semiconductor ingot into S101, then chamfer S102 on the outer peripheral edge to prevent chipping of the substrate, and then perform grinding S103 and chemical mechanical polishing (CMP) S104, and bulk substrate 12 Is made.
  • CMP chemical mechanical polishing
  • FIG. 4 shows an enlarged schematic cross-sectional view of the outer peripheral end portion of the epitaxial substrate 200 manufactured in the manufacturing process shown in FIG. Since epitaxial growth is performed after chamfering the outer peripheral edge, the epitaxial layers 2 and 4 are bent or curved along the surface of the bulk substrate 12 at the chamfered portion 201.
  • the bulk substrate When manufacturing a power semiconductor element using an epitaxial substrate, the bulk substrate usually has a certain thickness. Therefore, in order to obtain a desired laminated structure, part or all of the bulk substrate is removed by grinding or the like. There is a need.
  • the conductivity type of the drain region 2 is n-type, and the drain region 2 can be formed using an n-type bulk substrate.
  • the film thickness of the n-type SiC bulk substrate is, for example, about 300 ⁇ m to 500 ⁇ m, it is necessary to remove the bulk substrate in order to reduce the on-resistance of the element generated by the bulk substrate and achieve low loss.
  • the collector layer 32 on the back surface schematically shown in FIG. 11 is p-type, but a high-quality p-type SiC bulk substrate must be fabricated.
  • a stacked structure is formed on the n-type SiC bulk substrate 12, and then the bulk substrate 12 is removed to expose the p-type epitaxial layer 32 on the back side. There is a need.
  • the grinding process of the bulk substrate 12 is important in manufacturing a high-performance power semiconductor device, and it is necessary to prevent substrate cracking during substrate grinding in order to improve device manufacturing yield.
  • the substrate 200 having the bulk substrate / epitaxial layer interface 201 bent or curved at the outer peripheral edge of the substrate as shown in FIG. 4 is ground from the bulk substrate 12 side, as shown in FIG. A part of the layers 2 and 4 is exposed to the grinding surface, and a surface 202 on which the bulk substrate and the epitaxial layer exist simultaneously is formed on the grinding surface.
  • the crystal growth method is different between the bulk substrate and the epitaxial layer, even if the materials are the same, the crystal quality, purity, and hardness of both are greatly different, and the grinding rate is different. Therefore, if grinding of the grinding surface 202 is continued, stress is generated on the substrate and chipping occurs, which causes cracking of the substrate starting from the chipping. Therefore, it is a problem to realize an epitaxial substrate that suppresses substrate cracking during grinding.
  • an object of the present invention is to provide an epitaxial substrate manufacturing method that suppresses bending or bending of the interface between the bulk substrate and the epitaxial layer at the outer peripheral edge of the substrate and prevents substrate cracking during grinding. It is. Moreover, the manufacturing method of the power semiconductor element using this epitaxial substrate is provided.
  • the method for manufacturing an epitaxial substrate according to the present invention includes a step of cutting a semiconductor single crystal generated by crystal growth into a bulk substrate, and maintaining the edge of the cut surface of the bulk substrate. And / or grinding and polishing of the back surface, and epitaxial growth is performed on the substrate while maintaining the outer peripheral edge of the substrate formed by the polishing, and then the outer periphery of the substrate is chamfered.
  • the semiconductor device manufacturing method is such that the interface between the bulk substrate and the epitaxial layer is formed flat up to the outer peripheral edge of the substrate, and the edge of the outer peripheral edge of the substrate is on the side surface of the substrate.
  • a step of removing the bulk substrate on the back surface by grinding is executed first, and the epitaxial substrate is epitaxially formed.
  • the step of forming a semiconductor device structure in the drift layer of the layer and on the drift layer is subsequently performed.
  • the method of manufacturing a semiconductor device according to the present invention is such that the interface between the bulk substrate and the epitaxial layer is formed flat up to the outer peripheral edge of the substrate, and the edge of the outer peripheral edge of the substrate is against the side surface of the substrate.
  • a step of preparing an inclined epitaxial substrate a step of forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate; Removing the substrate by grinding, forming the electrode on the p + -type epitaxial layer of the epitaxial substrate that has appeared by removing the bulk substrate, and conducting the electrode on the back surface of the epitaxial substrate entirely, the epitaxial substrate Applying a probe to the electrode of each semiconductor element on the surface of the substrate to conduct an electrical characteristic test, and Epitaxial configure and a step of performing chip dicing of the substrate.
  • an epitaxial substrate manufacturing method that suppresses bending or bending of the epitaxial layer at the outer peripheral edge of the substrate and prevents substrate cracking during grinding. Accordingly, it is possible to increase the yield in the power semiconductor element manufacturing process having a bulk substrate grinding process, such as n-channel SiC / MOSFET and n-channel SiC / IGBT, and to realize cost reduction of a high-performance power semiconductor element.
  • FIG. 6 is a flowchart showing main steps of the epitaxial substrate manufacturing process according to the first embodiment of the present invention.
  • the semiconductor ingot was cut into pieces S101, the sharp edge of the cut surface of the bulk substrate immediately after slicing was maintained, and then grinding S103 and polishing were performed.
  • CMP polishing
  • Epitaxial growth S105 is performed using the substrate after the polishing (CMP), and thereafter, chamfering S102 of the outer peripheral end is performed to prevent chipping of the substrate.
  • the semiconductor ingot used here is, for example, n-type single crystal 4H-SiC containing nitrogen, phosphorus, etc., manufactured by a sublimation recrystallization method.
  • the grinding step S103 is performed by, for example, diamond lapping, and the polishing (CMP) step S104 is polished by using a polishing liquid having an etching action such as a colloidal silica slurry.
  • the epitaxial growth step S105 is performed by, for example, a chemical vapor deposition method (Chemical Vapor Deposition: CVD) using monosilane and propane.
  • the chamfering step S102 on the outer peripheral edge of the substrate is performed, for example, by pressing a V-shaped grindstone against the substrate side surface while rotating the epitaxial substrate.
  • FIG. 7 schematically shows a cross section of an example of a semiconductor substrate manufactured by the semiconductor substrate manufacturing process according to the present embodiment.
  • the semiconductor substrate 210 shown here is, for example, 4H—SiC having a crystal orientation (0001) 4 ° off, and includes an n-type bulk substrate 12, an n + -type epitaxial layer 2, and an n ⁇ -type epitaxial layer 4.
  • the n + type epitaxial layer 2 is n-type SiC containing nitrogen and phosphorus as impurities
  • the n ⁇ type epitaxial layer 4 is n-type SiC containing nitrogen and phosphorus as impurities.
  • the impurity concentration of the n ⁇ type epitaxial layer 4 is, for example, less than 5 ⁇ 10 15 cm ⁇ 3 .
  • the impurity concentration of the n + type epitaxial layer 2 is higher than the impurity concentration of the n ⁇ type epitaxial layer 4, for example.
  • the point of the present invention is that the epitaxial growth step S105 is performed while maintaining the shape of the flat bulk substrate surface obtained by the polishing (CMP) step S104 (without chamfering the edge on the outer periphery of the substrate).
  • CMP polishing
  • FIG. 8 shows a process of removing the bulk substrate 12 by grinding using the 4H-SiC epitaxial substrate 210 manufactured by the process of this example.
  • the grinding of the bulk substrate 12 is performed, for example, by grinding a grinding wheel from the bulk substrate side.
  • the interface between the bulk and the epitaxial layer is flat, so that the epitaxial layer is exposed to the grinding surface at the outer edge of the substrate during bulk substrate grinding. Can be prevented. Accordingly, it is possible to prevent the distribution of the grinding rate from occurring in the grinding surface during substrate grinding, and to reduce the possibility of chipping due to the non-uniform distribution of the grinding force, thereby preventing substrate cracking.
  • the invention of this embodiment is an invention related to the order of the chamfering process in the epitaxial substrate manufacturing process, the number of epitaxial layers stacked, the conductivity type of each epitaxial layer and bulk substrate, film thickness, impurity concentration, plane orientation, etc. are not limited to those exemplified in the present embodiment, and can be arbitrarily set. Further, the semiconductor material of each epitaxial layer and bulk substrate can be applied to, for example, Si, GaN, etc. in addition to the SiC exemplified in the present embodiment.
  • This embodiment is an epitaxial substrate manufacturing process in which the substrate outer peripheral end portion 221 is processed into a taper round shape as shown in FIG. 9 with respect to the chamfering step S102 of the epitaxial substrate in the first embodiment.
  • the chamfering is performed, for example, by pressing the grindstone 301 from the side surface of the substrate to the center while rotating the epitaxial substrate 220 using the grindstone 301 having a U-shaped grinding section shown in FIG.
  • the third embodiment relates to a power semiconductor element manufacturing process using a substrate manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment.
  • an n ⁇ type drift region 4 containing nitrogen, phosphorus, etc. is formed on the SiC substrate, and an n + type drain region 2 containing nitrogen, phosphorus, etc. is formed below the n ⁇ type drift region 4. Is formed.
  • a drain electrode 1 is provided below the drain region 2.
  • a p-type well region 5 containing aluminum, boron, or the like is formed inside the drift region 4, and an n + -type source region 6 containing nitrogen, phosphorus, etc., and a p containing aluminum, boron, etc. are formed inside the well region 5.
  • a + type source region 7 is formed.
  • a gate insulating film 8 is formed so as to cover the source region 6, the well region 5, and the drift region 4, and a gate electrode 9 is provided so as to cover the gate insulating film 8.
  • a source electrode 10 is formed so as to cover the source regions 6, 7 and the well region 5, and an interlayer insulating film 11 is formed to insulate the gate electrode 9 from the source electrode 10.
  • an SiC epitaxial substrate that is homoepitaxially grown in the order of the drain region 2 and the drift region 4 on the n-type SiC bulk substrate 12 is manufactured.
  • the impurity concentration of the drift region 4 is, for example, less than 5 ⁇ 10 15 cm ⁇ 3 .
  • the impurity concentration of the drain region 2 is higher than the impurity concentration of the drift region 4, for example.
  • the bulk substrate 12 is removed by grinding, for example, a grindstone.
  • the well region 5 is formed in the drift layer by, for example, impurity implantation or epitaxial growth.
  • Source regions 6 and 7 is a region formed by, for example, injecting example impurities at a high concentration such as 1 ⁇ 10 19 cm -3 or more.
  • the gate insulating film 8 is formed by, for example, wet oxidation, dry oxidation, or CVD (Chemical Vapor Deposition) of SiO 2 oxide film.
  • the gate electrode 9 is an electrode region formed by, after forming the gate insulating film 8, immediately after CVD of polysilicon or CVD of amorphous silicon, and then changing to polysilicon by heat treatment.
  • the interlayer insulating film 11 is formed by CVD or the like of SiO 2 oxide film, and then the source electrode 10 is formed by sputtering, metal vapor deposition or the like using a metal such as aluminum, titanium, or nickel.
  • the drain electrode 1 is formed by a method such as sputtering or metal vapor deposition using a metal such as aluminum, titanium, nickel, or gold.
  • a SiC epitaxial substrate is manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment, and then the well region 5, the source regions 6, 7, the gate insulating film 8, and the gate electrode 9.
  • An element structure such as a source electrode 10 and an interlayer insulating film 11 is formed.
  • the bulk substrate 12 is removed from the SiC epitaxial substrate having the element structure formed on the surface, for example, by grinding with a grindstone.
  • the drain electrode 1 is formed.
  • substrate cracking is suppressed in grinding of the bulk substrate. Can be improved.
  • the fourth embodiment relates to an n-channel SiC-IGBT manufacturing process using a substrate manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment.
  • an n ⁇ type drift region 4 containing nitrogen, phosphorus or the like is formed on the SiC substrate, and an n-type buffer region 33 containing nitrogen, phosphorus or the like is formed below the n ⁇ type drift region 4. Is formed.
  • the buffer region 33 is not necessarily required, but is provided for improving the breakdown voltage and suppressing conduction loss.
  • a p + -type collector region 32 containing aluminum, boron, or the like is formed in the lower portion of the buffer region, and a collector electrode 31 is provided in the lower portion thereof.
  • a p-type well region 5 containing aluminum, boron, or the like is formed inside the drift region 4, and an n + -type emitter region 34 containing nitrogen, phosphorus, etc., and a p containing aluminum, boron, etc. are formed inside the well region 5.
  • a + -type emitter region 35 is formed.
  • a gate insulating film 8 is formed so as to cover the emitter region 34, the well region 5, and the drift region 4, and a gate electrode 9 is provided so as to cover the gate insulating film 8.
  • An emitter electrode 36 is formed so as to cover the emitter regions 34 and 35 and the well region 5, and an interlayer insulating film 11 is formed to insulate the gate electrode 9 and the emitter electrode 36 from each other.
  • an SiC epitaxial substrate that is homoepitaxially grown in the order of the collector region 32, the buffer region 33, and the drift region 4 on the n-type SiC bulk substrate 12 is manufactured.
  • the impurity concentration of the collector region 32 is, for example, 1 ⁇ 10 18 cm ⁇ 3 or more.
  • the impurity concentration of the buffer region 33 is lower than the impurity concentration of the collector region 32, for example.
  • the impurity concentration of the drift region 4 is, for example, less than 5 ⁇ 10 15 cm ⁇ 3 .
  • the bulk substrate is removed by, for example, grinding with a grindstone as in the third embodiment shown in FIG.
  • the well region 5 is formed in the drift layer by, for example, impurity implantation or epitaxial growth.
  • the emitter regions 34 and 35 are regions formed by implanting impurities at a high concentration such as 1 ⁇ 10 19 cm ⁇ 3 or more.
  • the gate insulating film 8 is, for example wet oxidation, is formed by a CVD dry oxidation or SiO 2 oxide film (Chemical Vapor Deposition).
  • the gate electrode 9 is an electrode region formed by, after forming the gate insulating film 8, immediately after CVD of polysilicon or CVD of amorphous silicon, and then changing to polysilicon by heat treatment.
  • the interlayer insulating film 11 is formed by CVD or the like of SiO 2 oxide film, and then the emitter electrode 36 is formed by sputtering or metal vapor deposition using a metal such as aluminum, titanium, or nickel.
  • the collector electrode 31 is formed by a method such as sputtering or metal vapor deposition using a metal such as aluminum, titanium, nickel, or gold.
  • a SiC epitaxial substrate is manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment, and then the well region 5, the emitter regions 34 and 35, the gate insulating film 8, the gate electrode 9, the emitter electrode 36, and the interlayer An element structure such as the insulating film 11 is formed. Thereafter, the bulk substrate 12 is removed from the SiC epitaxial substrate having the element structure formed on the surface, for example, by grinding with a grindstone. Thereafter, the collector electrode 31 is formed.
  • substrate cracking is suppressed in grinding of the bulk substrate. Can be improved.
  • Examples 3 and 4 described above are inventions relating to a power semiconductor element manufacturing process including bulk substrate grinding, the present invention is not limited to MOSFETs and IGBTs but can be applied to other power semiconductor elements. Further, the present invention is not limited to the n-type channel structure but can be applied to a p-type channel structure.
  • the semiconductor material can be applied to, for example, Si or GaN other than the SiC exemplified in the present embodiment.
  • the fifth embodiment relates to an improvement in probe inspection efficiency for a power semiconductor element manufactured by the manufacturing process according to the fourth embodiment.
  • an n-channel SiC IGBT is manufactured by a manufacturing process including grinding of a bulk substrate using an epitaxial substrate manufactured by a conventional general semiconductor substrate manufacturing process
  • the epitaxial layer at the outer peripheral edge of the substrate is shown in FIG.
  • the interface 201 of the bulk substrate is bent or curved, and a surface 203 different from the original back surface structure is formed at the outer peripheral edge of the ground surface (the back surface of the n-channel SiC IGBT must be p + type) Therefore, an n-type epitaxial layer comes out at the outer peripheral edge of the substrate and causes a failure in electrical measurement), so it cannot be accurately evaluated if electrical measurement is performed in the substrate state (conventionally after chip dicing) Electrical measurements were made on individual chips).
  • the same surface 211 as the original back surface structure is formed on the entire ground surface as shown in FIG. Therefore, as shown in the flowchart of FIG. 13, an SiC epitaxial substrate is prepared and S201 is formed, and an n-channel SiC IGBT is formed S202 using the substrate, and probe inspection S203 of electrical characteristics is accurately performed while the substrate is in the state.
  • the entire surface of the table on which the substrate is placed is electrically connected to the collector electrode on the back surface of the substrate, and a probe is applied to the electrode of each chip on the substrate surface side to inspect the electrical characteristics).
  • Drain electrode 2 n + type epitaxial layer (drain region) 4 n - -type epitaxial layer (drift region) 5 p-type well region 6 n + type source region 7 p + -type source region 8 Gate insulation film 9 Gate electrode 10 Source electrode 11 Interlayer insulation film 12 Bulk substrate 31 Collector electrode 32 p + type epitaxial layer (collector region) 33 n-type epitaxial layer (buffer region) 34 n + emitter region 35 p + emitter region 36 Emitter electrode 200 Epitaxial substrates fabricated by conventional general manufacturing processes 201 Bulk substrate / epitaxial layer interface bent or curved along chamfered surface 202 Grinding surface with bulk substrate and epitaxial layer simultaneously 203 Grinding surface at which the layer different from the original back surface structure is exposed at the outer edge of the substrate 210 Epitaxial substrate manufactured by the manufacturing process according to the first embodiment 211 Ground surface with the same surface as the original back structure on the entire surface 220 Epitaxial substrate manufactured by the manufacturing process according to the second embodiment 221 Perimeter edge of substrate

Abstract

To provide an epitaxial substrate manufacturing method wherein substrate breakage from an epitaxial substrate outer peripheral end portion can be suppressed. The present invention discloses a process for manufacturing an epitaxial substrate wherein an epitaxially grown layer is formed on a cut bulk substrate formed by cutting a semiconductor single crystal. A cut surface of the bulk substrate is polished after being cut, epitaxial growth is performed in a state wherein an wafer outer peripheral end portion formed by the polishing is maintained, then chamfering of a substrate outer periphery is performed, thereby planarizing an interface between the epitaxial layer and the bulk substrate, said interface being at a substrate outer peripheral end portion, suppressing nonconformity of grinding rates at the time of removing the bulk substrate by grinding, and suppressing substrate breakage.

Description

エピタキシャル基板の製造方法および半導体装置の製造方法Epitaxial substrate manufacturing method and semiconductor device manufacturing method
　本発明は、特に基板外周端部からの基板割れを抑制するエピタキシャル基板の製造方法、およびそれを使用した半導体装置の製造方法に関するものである。 The present invention particularly relates to a method for manufacturing an epitaxial substrate that suppresses substrate cracks from the outer peripheral edge of the substrate, and a method for manufacturing a semiconductor device using the same.
　パワーエレクトロニクス機器の省エネルギー化のため、炭化ケイ素 (SiC) や窒化ガリウム (GaN) などのワイドギャップ半導体材料を用いた低損失パワー半導体素子が研究されている。SiCやGaNは絶縁破壊電界強度がシリコン (Si) より10倍程度高いため、同じ耐圧のパワー半導体素子の場合、ドリフト層の膜厚をSiの10分の1にすることができる。このようにドリフト層を薄くすることにより、ドリフト層抵抗が大幅に下げられるため、素子全体のオン抵抗を下げることができる。SiC, GaNの半導体素子への応用先として、ユニポーラ素子であるショットキーバリアダイオード (Schottky Barrier Diode: SBD) やパワーMOSFET (Metal Oxide Field Effect Transistor)、またバイポーラ素子であるPNダイオードや絶縁ゲートバイポーラトランジスタ(Insulated Gate Bipolar Transistor: IGBT) などがある。特にSiCを用いたバイポーラ素子は、6.5kVを超える超高耐圧用途において低い導通損失を実現する素子として期待されている。 In order to save energy in power electronics devices, low-loss power semiconductor devices using wide gap semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) are being studied. Since SiC and GaN have a breakdown electric field strength about 10 times higher than that of silicon (Si), the thickness of the drift layer can be reduced to 1/10 of Si in the case of a power semiconductor device having the same breakdown voltage. By thinning the drift layer in this manner, the drift layer resistance can be greatly reduced, so that the on-resistance of the entire element can be reduced. Applications of SiC and GaN semiconductor devices include unipolar Schottky barrier diodes (Schottky Barrier Diodes: SBDs) and power MOSFETs (Metal Oxide Field Effect Transistors), bipolar devices such as PN diodes and insulated gate bipolar transistors (Insulated Gate Bipolar Transistor: IGBT) In particular, a bipolar device using SiC is expected as a device that realizes a low conduction loss in an ultrahigh withstand voltage application exceeding 6.5 kV.
　上記したパワー半導体素子の作製は、一般的にバルク基板上に半導体材料がエピタキシャル成長されたエピタキシャル基板を用いて行う。図3に一般的なエピタキシャル基板の製造工程フローの主要工程を示す。半導体インゴットを輪切りS101にして、次に基板の欠け防止のため外周端部の面取りS102を行い、その後、研削S103、および化学的機械的研磨 (Chemical Mechanical Polishing: CMP) S104を行い、バルク基板12を作製する。 The above-described power semiconductor element is generally manufactured using an epitaxial substrate obtained by epitaxially growing a semiconductor material on a bulk substrate. FIG. 3 shows the main steps of a general epitaxial substrate manufacturing process flow. Turn the semiconductor ingot into S101, then chamfer S102 on the outer peripheral edge to prevent chipping of the substrate, and then perform grinding S103 and chemical mechanical polishing (CMP) S104, and bulk substrate 12 Is made.
　以上のバルク基板12を作製する工程では、特許文献１に記載されるように、半導体基板の高い表面清浄度を得るためには、基板の表面のみならず、裏面、側端面、面取り面も鏡面に研磨することが有効と述べている。特許文献１でも従来と同様に、半導体インゴットをスライスした直後の半導体基板を、鋭利な端面のままでは続く処理工程での搬送や位置合わせなどの取り扱い時に容易に割れたり欠けたりして基板表面を傷付けたり汚染したりすることを防ぐため、面取りを行っている。 In the above-described process for producing the bulk substrate 12, as described in Patent Document 1, in order to obtain a high surface cleanliness of the semiconductor substrate, not only the surface of the substrate but also the back surface, side end surfaces, and chamfered surfaces are mirror surfaces. It is said that polishing is effective. Also in Patent Document 1, as in the conventional case, the semiconductor substrate immediately after slicing the semiconductor ingot is easily cracked or chipped during handling such as transport and alignment in the subsequent processing step with the sharp end face, and the substrate surface is removed. Chamfering is performed to prevent damage and contamination.
　従来は、そのようなバルク基板12上の結晶の積層構造や方位関係を引き継ぎながらエピタキシャル成長S105を行い、エピタキシャル基板を作製している。図3に示す製造工程で作製したエピタキシャル基板200の外周端部の拡大断面模式図を図4に示す。外周端部の面取り後にエピタキシャル成長を行っているため、面取りされた箇所201ではエピタキシャル層2,4がバルク基板12表面に沿って屈曲若しくは湾曲している。 Conventionally, epitaxial growth S105 is performed while inheriting such a laminated structure and orientation relationship of crystals on the bulk substrate 12 to produce an epitaxial substrate. FIG. 4 shows an enlarged schematic cross-sectional view of the outer peripheral end portion of the epitaxial substrate 200 manufactured in the manufacturing process shown in FIG. Since epitaxial growth is performed after chamfering the outer peripheral edge, the epitaxial layers 2 and 4 are bent or curved along the surface of the bulk substrate 12 at the chamfered portion 201.
特開平６－８４８５６号公報JP-A-6-84856
　エピタキシャル基板を使用して、パワー半導体素子を製造する場合に、通常、バルク基板はある程度の厚みを持つため、所望の積層構造を得るために、バルク基板の一部や全部を研削などによって除去する必要がある。 When manufacturing a power semiconductor element using an epitaxial substrate, the bulk substrate usually has a certain thickness. Therefore, in order to obtain a desired laminated structure, part or all of the bulk substrate is removed by grinding or the like. There is a need.
　例えば、図1に模式的に示すnチャネルMOSFETではドレイン領域2の伝導型はn型であり、n型バルク基板を用いてドレイン領域2を形成することが可能である。しかしn型SiCバルク基板の膜厚は例えば300μmから500μm程度であるため、バルク基板により生じる素子のオン抵抗を減少させて低損失化を実現するためには、バルク基板の除去が必要となる。 For example, in the n-channel MOSFET schematically shown in FIG. 1, the conductivity type of the drain region 2 is n-type, and the drain region 2 can be formed using an n-type bulk substrate. However, since the film thickness of the n-type SiC bulk substrate is, for example, about 300 μm to 500 μm, it is necessary to remove the bulk substrate in order to reduce the on-resistance of the element generated by the bulk substrate and achieve low loss.
　また、例えば超高耐圧スイッチング素子として期待されるn型SiC IGBTの場合、図11に模式的に示す裏面のコレクタ層32がp型となるが、高品質なp型SiCバルク基板を作製することは困難であるため、図12に示す製造工程フローのように、n型SiCバルク基板12上に積層構造を形成し、その後バルク基板12を除去してp型エピタキシャル層32を裏面側に露出させる必要がある。 For example, in the case of an n-type SiC-IGBT expected as an ultra-high voltage switching device, the collector layer 32 on the back surface schematically shown in FIG. 11 is p-type, but a high-quality p-type SiC bulk substrate must be fabricated. As shown in the manufacturing process flow shown in FIG. 12, a stacked structure is formed on the n-type SiC bulk substrate 12, and then the bulk substrate 12 is removed to expose the p-type epitaxial layer 32 on the back side. There is a need.
　従って、バルク基板12の研削工程は高性能なパワー半導体素子を製造する上で重要であり、素子製造の歩留まりを向上するため、基板研削時の基板割れを防止することが必要となる。 Therefore, the grinding process of the bulk substrate 12 is important in manufacturing a high-performance power semiconductor device, and it is necessary to prevent substrate cracking during substrate grinding in order to improve device manufacturing yield.
　ところが、前記した図４で示すような基板外周端部で屈曲若しくは湾曲したバルク基板／エピタキシャル層界面201を持つ基板200をバルク基板12側から研削すると、図5に示すように、研削途中でエピタキシャル層2,4の一部が研削面に露出し、バルク基板とエピタキシャル層が同時に存在する面202が研削面に生じる。一般的にバルク基板とエピタキシャル層は結晶成長方法が異なるため、例え材料が同一であっても両者の結晶品質、純度、硬度が大きく異なり、研削レートに差異が生じる。そのため、研削面202の研削を続けると基板に応力が生じてチッピングが起こり、そのチッピングが起点となって基板割れの原因となる。従って、研削時の基板割れを抑制するエピタキシャル基板を実現することが課題である。 However, when the substrate 200 having the bulk substrate / epitaxial layer interface 201 bent or curved at the outer peripheral edge of the substrate as shown in FIG. 4 is ground from the bulk substrate 12 side, as shown in FIG. A part of the layers 2 and 4 is exposed to the grinding surface, and a surface 202 on which the bulk substrate and the epitaxial layer exist simultaneously is formed on the grinding surface. In general, since the crystal growth method is different between the bulk substrate and the epitaxial layer, even if the materials are the same, the crystal quality, purity, and hardness of both are greatly different, and the grinding rate is different. Therefore, if grinding of the grinding surface 202 is continued, stress is generated on the substrate and chipping occurs, which causes cracking of the substrate starting from the chipping. Therefore, it is a problem to realize an epitaxial substrate that suppresses substrate cracking during grinding.
　以上の課題に鑑み、本発明の目的は、基板外周端部でのバルク基板とエピタキシャル層の界面の屈曲若しくは湾曲を抑制し、研削時の基板割れを防止するエピタキシャル基板の製造方法を提供することである。また、このエピタキシャル基板を使用したパワー半導体素子の製造方法を提供する。 In view of the above problems, an object of the present invention is to provide an epitaxial substrate manufacturing method that suppresses bending or bending of the interface between the bulk substrate and the epitaxial layer at the outer peripheral edge of the substrate and prevents substrate cracking during grinding. It is. Moreover, the manufacturing method of the power semiconductor element using this epitaxial substrate is provided.
　上記課題を解決するために本発明のエピタキシャル基板の製造方法を、結晶成長により生成した半導体単結晶をバルク基板に切断し、前記バルク基板の切断面のエッジを維持した状態で、前記基板の表面、および／または裏面の研削、および研磨を行い、前記研磨により形成された基板外周端部を維持した状態で基板上にエピタキシャル成長を行い、その後、基板外周の面取りを行うように構成する。 In order to solve the above-described problem, the method for manufacturing an epitaxial substrate according to the present invention includes a step of cutting a semiconductor single crystal generated by crystal growth into a bulk substrate, and maintaining the edge of the cut surface of the bulk substrate. And / or grinding and polishing of the back surface, and epitaxial growth is performed on the substrate while maintaining the outer peripheral edge of the substrate formed by the polishing, and then the outer periphery of the substrate is chamfered.
　また、上記課題を解決するために本発明の半導体装置の製造方法を、バルク基板とエピタキシャル層の界面が基板外周端部まで平坦に形成され、および基板外周端部のエッジが基板側面に対して傾斜面となっているエピタキシャル基板を準備する工程と、前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程と、前記エピタキシャル基板を反転して、裏面のバルク基板を研削により除去する工程と、前記バルク基板の除去により現れた前記エピタキシャル基板のエピタキシャル層に電極を形成する工程とを有して構成する。 In order to solve the above-described problem, the semiconductor device manufacturing method according to the present invention is such that the interface between the bulk substrate and the epitaxial layer is formed flat up to the outer peripheral edge of the substrate, and the edge of the outer peripheral edge of the substrate is on the side surface of the substrate. A step of preparing an inclined epitaxial substrate; a step of forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate; A step of removing the substrate by grinding, and a step of forming an electrode on the epitaxial layer of the epitaxial substrate that appears by removing the bulk substrate.
　また、本発明の他の特徴として、前記半導体装置の製造方法において、前記エピタキシャル基板を準備する工程に続けて、裏面のバルク基板を研削により除去する工程を先に実行し、前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程をその後に実行する。 Further, as another feature of the present invention, in the method for manufacturing a semiconductor device, following the step of preparing the epitaxial substrate, a step of removing the bulk substrate on the back surface by grinding is executed first, and the epitaxial substrate is epitaxially formed. The step of forming a semiconductor device structure in the drift layer of the layer and on the drift layer is subsequently performed.
　また、上記課題を解決するために本発明の半導体装置の製造方法を、バルク基板とエピタキシャル層の界面が基板外周端部まで平坦に形成され、および基板外周端部のエッジが基板側面に対して傾斜面となっているエピタキシャル基板を準備する工程と、前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程と、前記エピタキシャル基板を反転して、裏面のバルク基板を研削により除去する工程と、前記バルク基板の除去により現れた前記エピタキシャル基板のp+型エピタキシャル層に電極を形成する工程と前記エピタキシャル基板の裏面の前記電極を全面導通させて、前記エピタキシャル基板の表面の各半導体素子の電極にプローブを当てて電気的特性検査を行う工程と、前記エピタキシャル基板のチップダイシングを行う工程とを有して構成する。 In order to solve the above-described problem, the method of manufacturing a semiconductor device according to the present invention is such that the interface between the bulk substrate and the epitaxial layer is formed flat up to the outer peripheral edge of the substrate, and the edge of the outer peripheral edge of the substrate is against the side surface of the substrate. A step of preparing an inclined epitaxial substrate; a step of forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate; Removing the substrate by grinding, forming the electrode on the p + -type epitaxial layer of the epitaxial substrate that has appeared by removing the bulk substrate, and conducting the electrode on the back surface of the epitaxial substrate entirely, the epitaxial substrate Applying a probe to the electrode of each semiconductor element on the surface of the substrate to conduct an electrical characteristic test, and Epitaxial configure and a step of performing chip dicing of the substrate.
　本発明によれば、基板外周端部でのエピタキシャル層の屈曲若しくは湾曲を抑制し、研削時の基板割れを防止するエピタキシャル基板の製造方法が提供される。従って、nチャネルSiC MOSFET、nチャネルSiC IGBTのように、バルク基板研削工程を有するパワー半導体素子製造プロセスにおける歩留まりを増大させることが可能となり、高性能なパワー半導体素子の低コスト化が実現できる。 According to the present invention, there is provided an epitaxial substrate manufacturing method that suppresses bending or bending of the epitaxial layer at the outer peripheral edge of the substrate and prevents substrate cracking during grinding. Accordingly, it is possible to increase the yield in the power semiconductor element manufacturing process having a bulk substrate grinding process, such as n-channel SiC / MOSFET and n-channel SiC / IGBT, and to realize cost reduction of a high-performance power semiconductor element.
nチャネルSiC MOSFETの構造を模式的に示す図である。It is a figure which shows typically the structure of n channel SiC-MOSFET. 第３の実施形態におけるnチャネルSiC MOSFETの製造プロセスの主要工程を示す図である。It is a figure which shows the main processes of the manufacturing process of n channel SiC * MOSFET in 3rd Embodiment. 従来の一般的なエピタキシャル基板製造プロセスフローの主要工程を示す図である。It is a figure which shows the main processes of the conventional general epitaxial substrate manufacturing process flow. 従来の一般的な製造工程で作製されたエピタキシャル基板の外周端部の断面模式図である。It is a cross-sectional schematic diagram of the outer periphery edge part of the epitaxial substrate produced by the conventional general manufacturing process. 従来の一般的な製造工程で作製されたエピタキシャル基板のバルク基板研削工程を説明する図である。It is a figure explaining the bulk substrate grinding process of the epitaxial substrate produced by the conventional general manufacturing process. 第１の実施形態に係るエピタキシャル基板製造プロセスフローの主要工程を示す図である。It is a figure which shows the main processes of the epitaxial substrate manufacturing process flow which concerns on 1st Embodiment. 第１の実施形態に係るエピタキシャル基板製造プロセスで作製されたエピタキシャル基板の外周端部の断面模式図である。It is a cross-sectional schematic diagram of the outer peripheral edge part of the epitaxial substrate produced by the epitaxial substrate manufacturing process which concerns on 1st Embodiment. 第１の実施形態に係るエピタキシャル基板製造プロセスで作製されたエピタキシャル基板のバルク基板研削工程を説明する図である。It is a figure explaining the bulk substrate grinding process of the epitaxial substrate produced by the epitaxial substrate manufacturing process concerning a 1st embodiment. 第２の実施形態に係るエピタキシャル基板製造プロセスで作製されたエピタキシャル基板の外周端部の断面模式図である。It is a cross-sectional schematic diagram of the outer periphery edge part of the epitaxial substrate produced by the epitaxial substrate manufacturing process which concerns on 2nd Embodiment. 第２の実施形態に係るエピタキシャル基板製造プロセスにおいて面取りに用いる砥石の断面模式図である。It is a cross-sectional schematic diagram of the grindstone used for chamfering in the epitaxial substrate manufacturing process which concerns on 2nd Embodiment. nチャネルSiC IGBTの構造を模式的に示す図である。It is a figure which shows typically the structure of n channel SiC-IGBT. 第４の実施形態におけるnチャネルSiC IGBTの製造プロセスの主要工程を示す図である。It is a figure which shows the main processes of the manufacturing process of n channel SiC * IGBT in 4th Embodiment. 第５の実施形態に係るnチャネルSiC IGBT製造プロセスにおける良品選別のフローを示す図である。It is a figure which shows the flow of non-defective item selection in the n channel SiCSiIGBT manufacturing process according to the fifth embodiment.
　以下に、図面を用いて、本発明の実施の形態を詳細に述べる。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
　図6は本発明の第１の実施形態に係るエピタキシャル基板製造プロセスの主要工程を示すフローチャートである。図6に示されるように、本実施例の製造プロセスは、半導体インゴットを輪切りS101にした後、スライスした直後のバルク基板の切断面の鋭利なエッジを維持した状態で、次に研削S103および研磨(CMP) S104を行うようにしている。その研磨(CMP)を施した後の基板を用いてエピタキシャル成長S105を行い、その後、基板の欠け防止のため外周端部の面取りS102を行う。 FIG. 6 is a flowchart showing main steps of the epitaxial substrate manufacturing process according to the first embodiment of the present invention. As shown in FIG. 6, in the manufacturing process of this example, after the semiconductor ingot was cut into pieces S101, the sharp edge of the cut surface of the bulk substrate immediately after slicing was maintained, and then grinding S103 and polishing were performed. (CMP) S104 is performed. Epitaxial growth S105 is performed using the substrate after the polishing (CMP), and thereafter, chamfering S102 of the outer peripheral end is performed to prevent chipping of the substrate.
　ここで用いる半導体インゴットは例えば、昇華再結晶法により製造される、窒素やリンなどを含むn型単結晶4H-SiCである。研削工程S103は例えばダイヤモンドラッピングにより行い、研磨(CMP)工程 S104は例えばコロイダルシリカスラリーなどのエッチング作用のある研磨液を用いて研磨する。エピタキシャル成長工程S105は例えばモノシランとプロパンを用いた化学気相堆積法 (Chemical Vapor Deposition: CVD) により行われる。基板外周端部の面取り工程S102は例えば、エピタキシャル基板を回転させながら、V字型の砥石を基板側面に押し当てることにより行われる。 The semiconductor ingot used here is, for example, n-type single crystal 4H-SiC containing nitrogen, phosphorus, etc., manufactured by a sublimation recrystallization method. The grinding step S103 is performed by, for example, diamond lapping, and the polishing (CMP) step S104 is polished by using a polishing liquid having an etching action such as a colloidal silica slurry. The epitaxial growth step S105 is performed by, for example, a chemical vapor deposition method (Chemical Vapor Deposition: CVD) using monosilane and propane. The chamfering step S102 on the outer peripheral edge of the substrate is performed, for example, by pressing a V-shaped grindstone against the substrate side surface while rotating the epitaxial substrate.
　図7には、本実施形態に係る半導体基板製造プロセスにより製造された半導体基板の一例の断面を模式的に示している。ここで示す半導体基板210は例えば結晶方位 (0001) 4°オフを有する4H-SiCであり、n型バルク基板12とn+型エピタキシャル層2、およびn-型エピタキシャル層4を備えている。n+型エピタキシャル層2は窒素やリンを不純物に含むn型SiC、n-型エピタキシャル層4は窒素やリンを不純物に含むn型SiCである。n-型エピタキシャル層4の不純物濃度は、例えば5×1015cm-3未満である。n+型エピタキシャル層2の不純物濃度は、例えばn-型エピタキシャル層4の不純物濃度より高い値である。 FIG. 7 schematically shows a cross section of an example of a semiconductor substrate manufactured by the semiconductor substrate manufacturing process according to the present embodiment. The semiconductor substrate 210 shown here is, for example, 4H—SiC having a crystal orientation (0001) 4 ° off, and includes an n-type bulk substrate 12, an n + -type epitaxial layer 2, and an n − -type epitaxial layer 4. The n + type epitaxial layer 2 is n-type SiC containing nitrogen and phosphorus as impurities, and the n − type epitaxial layer 4 is n-type SiC containing nitrogen and phosphorus as impurities. The impurity concentration of the n − type epitaxial layer 4 is, for example, less than 5 × 10 15 cm −3 . The impurity concentration of the n + type epitaxial layer 2 is higher than the impurity concentration of the n − type epitaxial layer 4, for example.
　本実施例の発明のポイントは、研磨(CMP)工程 S104により得られた平坦なバルク基板表面の形状を維持したまま(基板の外周部にあるエッジを面取りすること無しに)エピタキシャル成長工程S105を行うことで、図7に示すような基板外周端部までバルク12とエピタキシャル層2の界面が平坦なエピタキシャル基板を製造することである。 The point of the present invention is that the epitaxial growth step S105 is performed while maintaining the shape of the flat bulk substrate surface obtained by the polishing (CMP) step S104 (without chamfering the edge on the outer periphery of the substrate). Thus, an epitaxial substrate in which the interface between the bulk 12 and the epitaxial layer 2 is flat up to the outer peripheral edge of the substrate as shown in FIG. 7 is manufactured.
　図8に、本実施例の工程により製造される4H-SiCエピタキシャル基板210を用いて、バルク基板12を研削により除去する工程を示す。バルク基板12の研削は、例えばバルク基板側から砥石研削により行われる。図5に示す従来の工程により製造されるエピタキシャル基板の研削と異なり、バルクとエピタキシャル層の界面が平坦であるため、バルク基板研削中に基板外周端部でエピタキシャル層が研削面に露出することを防止できる。したがって、基板研削中に研削面内で研削レートに分布が生じることを防ぎ、研削力の不均一な分布によるチッピングが起こる可能性も減って、基板割れを防止することができる。 FIG. 8 shows a process of removing the bulk substrate 12 by grinding using the 4H-SiC epitaxial substrate 210 manufactured by the process of this example. The grinding of the bulk substrate 12 is performed, for example, by grinding a grinding wheel from the bulk substrate side. Unlike the grinding of the epitaxial substrate manufactured by the conventional process shown in FIG. 5, the interface between the bulk and the epitaxial layer is flat, so that the epitaxial layer is exposed to the grinding surface at the outer edge of the substrate during bulk substrate grinding. Can be prevented. Accordingly, it is possible to prevent the distribution of the grinding rate from occurring in the grinding surface during substrate grinding, and to reduce the possibility of chipping due to the non-uniform distribution of the grinding force, thereby preventing substrate cracking.
　以上のように、本実施の形態によりバルク基板研削時の基板割れを抑制するエピタキシャル基板の製造プロセスを提供することが可能となる。なお、本実施例の発明はエピタキシャル基板製造プロセス中の面取り工程の順序に関する発明であるため、エピタキシャル層の積層数や、各エピタキシャル層およびバルク基板の伝導型、膜厚、不純物濃度、面方位などは、本実施例で例示したものに限らず、任意に設定できる。また、各エピタキシャル層およびバルク基板の半導体材料は本実施形態で例示したSiC以外に、例えばSiやGaNなどに適用可能である。 As described above, according to this embodiment, it is possible to provide an epitaxial substrate manufacturing process that suppresses substrate cracking during bulk substrate grinding. Since the invention of this embodiment is an invention related to the order of the chamfering process in the epitaxial substrate manufacturing process, the number of epitaxial layers stacked, the conductivity type of each epitaxial layer and bulk substrate, film thickness, impurity concentration, plane orientation, etc. Are not limited to those exemplified in the present embodiment, and can be arbitrarily set. Further, the semiconductor material of each epitaxial layer and bulk substrate can be applied to, for example, Si, GaN, etc. in addition to the SiC exemplified in the present embodiment.
　本実施形態は、第１の実施形態におけるエピタキシャル基板の面取りの工程S102について、図9に示すように、基板外周端部221をテーパーラウンド形状に加工するエピタキシャル基板製造プロセスである。面取りは例えば、図10に示すU字型状の研削断面を有する砥石301を用いて、エピタキシャル基板220を回転させながら、砥石301を基板側面から中心部へ押し付けることにより行われる。本実施の形態の面取りにより、基板外周端面での基板欠け防止効果が向上したエピタキシャル基板の製造プロセスを提供することが可能となる。 This embodiment is an epitaxial substrate manufacturing process in which the substrate outer peripheral end portion 221 is processed into a taper round shape as shown in FIG. 9 with respect to the chamfering step S102 of the epitaxial substrate in the first embodiment. The chamfering is performed, for example, by pressing the grindstone 301 from the side surface of the substrate to the center while rotating the epitaxial substrate 220 using the grindstone 301 having a U-shaped grinding section shown in FIG. By the chamfering of the present embodiment, it is possible to provide an epitaxial substrate manufacturing process with improved substrate chipping prevention effect on the substrate outer peripheral end surface.
　第３の実施形態は、第１、または第２の実施形態に係るエピタキシャル基板製造プロセスにより製造された基板を用いた、パワー半導体素子の製造プロセスに関する。 The third embodiment relates to a power semiconductor element manufacturing process using a substrate manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment.
　図1に模式的に示すnチャネルSiC MOSFETにおいて、SiC基板に窒素やリンなどを含むn-型ドリフト領域4が形成されており、その下部には窒素やリンなどを含むn+型ドレイン領域2が形成されている。ドレイン領域2の下部にはドレイン電極1が備えられている。ドリフト領域4内部にはアルミニウムやボロンなどを含むp型ウェル領域5が形成されており、ウェル領域5内部には窒素やリンなどを含むn+型ソース領域6、およびアルミニウムやボロンなどを含むp+型ソース領域7が形成されている。ソース領域6と、ウェル領域5、ドリフト領域4を被覆するようにゲート絶縁膜8が形成されており、ゲート絶縁膜8を被覆するようにゲート電極9が備えられている。ソース領域6,7とウェル領域5を被覆するようにソース電極10が形成されており、ゲート電極9とソース電極10を絶縁するために層間絶縁膜11が形成されている。 In the n-channel SiC MOSFET schematically shown in FIG. 1, an n − type drift region 4 containing nitrogen, phosphorus, etc. is formed on the SiC substrate, and an n + type drain region 2 containing nitrogen, phosphorus, etc. is formed below the n − type drift region 4. Is formed. A drain electrode 1 is provided below the drain region 2. A p-type well region 5 containing aluminum, boron, or the like is formed inside the drift region 4, and an n + -type source region 6 containing nitrogen, phosphorus, etc., and a p containing aluminum, boron, etc. are formed inside the well region 5. A + type source region 7 is formed. A gate insulating film 8 is formed so as to cover the source region 6, the well region 5, and the drift region 4, and a gate electrode 9 is provided so as to cover the gate insulating film 8. A source electrode 10 is formed so as to cover the source regions 6, 7 and the well region 5, and an interlayer insulating film 11 is formed to insulate the gate electrode 9 from the source electrode 10.
　第１、または第２の実施形態に係るエピタキシャル基板製造プロセスにより、例えばn型のSiCバルク基板12上にドレイン領域2、ドリフト領域4の順番でホモエピタキシャル成長したSiCエピタキシャル基板を製造する。ドリフト領域4の不純物濃度は、例えば5×1015cm-3未満である。ドレイン領域2の不純物濃度は、例えばドリフト領域4の不純物濃度より高い値である。その後、図8に示すように、例えば砥石研削によりバルク基板12を除去する。 By the epitaxial substrate manufacturing process according to the first or second embodiment, for example, an SiC epitaxial substrate that is homoepitaxially grown in the order of the drain region 2 and the drift region 4 on the n-type SiC bulk substrate 12 is manufactured. The impurity concentration of the drift region 4 is, for example, less than 5 × 10 15 cm −3 . The impurity concentration of the drain region 2 is higher than the impurity concentration of the drift region 4, for example. Thereafter, as shown in FIG. 8, the bulk substrate 12 is removed by grinding, for example, a grindstone.
　ウェル領域5は例えば不純物注入またはエピタキシャル成長などでドリフト層中に形成する。ソース領域6,7は、例えば不純物を1×1019cm-3以上など高濃度に注入するなどして形成した領域である。ゲート絶縁膜8は例えばウェット酸化、ドライ酸化あるいはSiO2酸化膜のCVD (Chemical Vapor Deposition)などによって形成する。ゲート電極9はゲート絶縁膜8の形成後、その直上にポリシリコンのCVDまたはアモルファスシリコンのCVD後、熱処理でポリシリコンに変性させるなどで形成した電極領域である。SiO2酸化膜のCVDなどによって層間絶縁膜11を形成し、その後ソース電極10をアルミニウム、チタン、ニッケルなどの金属を用いて、スパッタや金属蒸着法などにより形成する。ドレイン電極1は例えばアルミニウム、チタン、ニッケル、金などの金属を用いて、スパッタや金属蒸着法などの方法により形成する。 The well region 5 is formed in the drift layer by, for example, impurity implantation or epitaxial growth. Source regions 6 and 7 is a region formed by, for example, injecting example impurities at a high concentration such as 1 × 10 19 cm -3 or more. The gate insulating film 8 is formed by, for example, wet oxidation, dry oxidation, or CVD (Chemical Vapor Deposition) of SiO 2 oxide film. The gate electrode 9 is an electrode region formed by, after forming the gate insulating film 8, immediately after CVD of polysilicon or CVD of amorphous silicon, and then changing to polysilicon by heat treatment. The interlayer insulating film 11 is formed by CVD or the like of SiO 2 oxide film, and then the source electrode 10 is formed by sputtering, metal vapor deposition or the like using a metal such as aluminum, titanium, or nickel. The drain electrode 1 is formed by a method such as sputtering or metal vapor deposition using a metal such as aluminum, titanium, nickel, or gold.
　もしくは、図2に示すように、第１、または第２の実施形態に係るエピタキシャル基板製造プロセスによりSiCエピタキシャル基板を製造し、その後ウェル領域5、ソース領域6,7、ゲート絶縁膜8、ゲート電極9、ソース電極10、層間絶縁膜11など素子構造を形成する。その後、表面に素子構造が形成されたSiCエピタキシャル基板について、例えば砥石研削によりバルク基板12を除去する。その後、ドレイン電極1を形成する。 Alternatively, as shown in FIG. 2, a SiC epitaxial substrate is manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment, and then the well region 5, the source regions 6, 7, the gate insulating film 8, and the gate electrode 9. An element structure such as a source electrode 10 and an interlayer insulating film 11 is formed. Thereafter, the bulk substrate 12 is removed from the SiC epitaxial substrate having the element structure formed on the surface, for example, by grinding with a grindstone. Thereafter, the drain electrode 1 is formed.
　いずれの場合においても、第１、または第２の実施形態に係るエピタキシャル基板製造プロセスにより製造したエピタキシャル基板を用いることにより、バルク基板の研削において基板割れが抑制されるため、パワー半導体素子製造の歩留まりを向上することが可能となる。 In either case, by using the epitaxial substrate manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment, substrate cracking is suppressed in grinding of the bulk substrate. Can be improved.
　第４の実施形態は、第１、または第２の実施形態に係るエピタキシャル基板製造プロセスにより製造された基板を用いた、nチャネルSiC IGBTの製造プロセスに関する。 The fourth embodiment relates to an n-channel SiC-IGBT manufacturing process using a substrate manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment.
　図11に模式的に示すnチャネルSiC IGBTにおいて、SiC基板に窒素やリンなどを含むn-型ドリフト領域4が形成されており、その下部には窒素やリンなどを含むn型バッファ領域33が形成されている。バッファ領域33は必ずしも必要なものではないが、耐圧の向上と導通損失の抑制のために設けている。バッファ領域の下部にはアルミニウムやボロンなどを含むp+型コレクタ領域32が形成されており、その下部にはコレクタ電極31が備えられている。ドリフト領域4内部にはアルミニウムやボロンなどを含むp型ウェル領域5が形成されており、ウェル領域5内部には窒素やリンなどを含むn+型エミッタ領域34、およびアルミニウムやボロンなどを含むp+型エミッタ領域35が形成されている。エミッタ領域34と、ウェル領域5、ドリフト領域4を被覆するようにゲート絶縁膜8が形成されており、ゲート絶縁膜8を被覆するようにゲート電極9が備えられている。エミッタ領域34,35とウェル領域5を被覆するようにエミッタ電極36が形成されており、ゲート電極9とエミッタ電極36を絶縁するために層間絶縁膜11が形成されている。 In the n-channel SiC IGBT schematically shown in FIG. 11, an n − type drift region 4 containing nitrogen, phosphorus or the like is formed on the SiC substrate, and an n-type buffer region 33 containing nitrogen, phosphorus or the like is formed below the n − type drift region 4. Is formed. The buffer region 33 is not necessarily required, but is provided for improving the breakdown voltage and suppressing conduction loss. A p + -type collector region 32 containing aluminum, boron, or the like is formed in the lower portion of the buffer region, and a collector electrode 31 is provided in the lower portion thereof. A p-type well region 5 containing aluminum, boron, or the like is formed inside the drift region 4, and an n + -type emitter region 34 containing nitrogen, phosphorus, etc., and a p containing aluminum, boron, etc. are formed inside the well region 5. A + -type emitter region 35 is formed. A gate insulating film 8 is formed so as to cover the emitter region 34, the well region 5, and the drift region 4, and a gate electrode 9 is provided so as to cover the gate insulating film 8. An emitter electrode 36 is formed so as to cover the emitter regions 34 and 35 and the well region 5, and an interlayer insulating film 11 is formed to insulate the gate electrode 9 and the emitter electrode 36 from each other.
　第１、または第２の実施形態に係るエピタキシャル基板製造プロセスにより、例えばn型のSiCバルク基板12上にコレクタ領域32、バッファ領域33、ドリフト領域4の順番でホモエピタキシャル成長したSiCエピタキシャル基板を製造する。コレクタ領域32の不純物濃度は、例えば1×1018cm-3以上である。バッファ領域33の不純物濃度は、例えばコレクタ領域32の不純物濃度より低い値である。ドリフト領域4の不純物濃度は、例えば5×1015cm-3未満である。その後、図8に示す実施例３と同様に、例えば砥石研削によりバルク基板を除去する。 By the epitaxial substrate manufacturing process according to the first or second embodiment, for example, an SiC epitaxial substrate that is homoepitaxially grown in the order of the collector region 32, the buffer region 33, and the drift region 4 on the n-type SiC bulk substrate 12 is manufactured. . The impurity concentration of the collector region 32 is, for example, 1 × 10 18 cm −3 or more. The impurity concentration of the buffer region 33 is lower than the impurity concentration of the collector region 32, for example. The impurity concentration of the drift region 4 is, for example, less than 5 × 10 15 cm −3 . Thereafter, the bulk substrate is removed by, for example, grinding with a grindstone as in the third embodiment shown in FIG.
　ウェル領域5は例えば不純物注入またはエピタキシャル成長などでドリフト層中に形成する。エミッタ領域34,35は、例えば不純物を1×1019cm-3以上など高濃度に注入して形成した領域である。ゲート絶縁膜8は例えばウェット酸化、ドライ酸化あるいはSiO2酸化膜のCVD (Chemical Vapor Deposition)などによって形成する。ゲート電極9はゲート絶縁膜8の形成後、その直上にポリシリコンのCVDまたはアモルファスシリコンのCVD後、熱処理でポリシリコンに変性させるなどで形成した電極領域である。SiO2酸化膜のCVDなどによって層間絶縁膜11を形成し、その後エミッタ電極36をアルミニウム、チタン、ニッケルなどの金属を用いて、スパッタや金属蒸着法などにより形成する。コレクタ電極31は例えばアルミニウム、チタン、ニッケル、金などの金属を用いて、スパッタや金属蒸着法などの方法により形成する。 The well region 5 is formed in the drift layer by, for example, impurity implantation or epitaxial growth. The emitter regions 34 and 35 are regions formed by implanting impurities at a high concentration such as 1 × 10 19 cm −3 or more. The gate insulating film 8 is, for example wet oxidation, is formed by a CVD dry oxidation or SiO 2 oxide film (Chemical Vapor Deposition). The gate electrode 9 is an electrode region formed by, after forming the gate insulating film 8, immediately after CVD of polysilicon or CVD of amorphous silicon, and then changing to polysilicon by heat treatment. The interlayer insulating film 11 is formed by CVD or the like of SiO 2 oxide film, and then the emitter electrode 36 is formed by sputtering or metal vapor deposition using a metal such as aluminum, titanium, or nickel. The collector electrode 31 is formed by a method such as sputtering or metal vapor deposition using a metal such as aluminum, titanium, nickel, or gold.
　もしくは、第１、または第２の実施形態に係るエピタキシャル基板製造プロセスによりSiCエピタキシャル基板を製造し、その後ウェル領域5、エミッタ領域34,35、ゲート絶縁膜8、ゲート電極9、エミッタ電極36、層間絶縁膜11など素子構造を形成する。その後、表面に素子構造が形成されたSiCエピタキシャル基板について、例えば砥石研削によりバルク基板12を除去する。その後、コレクタ電極31を形成する。 Alternatively, a SiC epitaxial substrate is manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment, and then the well region 5, the emitter regions 34 and 35, the gate insulating film 8, the gate electrode 9, the emitter electrode 36, and the interlayer An element structure such as the insulating film 11 is formed. Thereafter, the bulk substrate 12 is removed from the SiC epitaxial substrate having the element structure formed on the surface, for example, by grinding with a grindstone. Thereafter, the collector electrode 31 is formed.
　いずれの場合においても、第１、または第２の実施形態に係るエピタキシャル基板製造プロセスにより製造したエピタキシャル基板を用いることにより、バルク基板の研削において基板割れが抑制されるため、パワー半導体素子製造の歩留まりを向上することが可能となる。 In either case, by using the epitaxial substrate manufactured by the epitaxial substrate manufacturing process according to the first or second embodiment, substrate cracking is suppressed in grinding of the bulk substrate. Can be improved.
　なお、以上説明した実施例３、４はバルク基板研削を含んだパワー半導体素子製造プロセスに関する発明であるため、MOSFET、IGBTに限らず、他のパワー半導体素子に適用可能である。また、本発明はn型チャネル構造に限らず、p型チャネル構造に適用可能である。半導体材料は本実施形態で例示したSiC以外に、例えばSiやGaNなどに適用可能である。 In addition, since Examples 3 and 4 described above are inventions relating to a power semiconductor element manufacturing process including bulk substrate grinding, the present invention is not limited to MOSFETs and IGBTs but can be applied to other power semiconductor elements. Further, the present invention is not limited to the n-type channel structure but can be applied to a p-type channel structure. The semiconductor material can be applied to, for example, Si or GaN other than the SiC exemplified in the present embodiment.
　第５の実施形態は、第４の実施形態に係る製造プロセスにより製造されたパワー半導体素子について、プローブ検査の効率向上に関する。 The fifth embodiment relates to an improvement in probe inspection efficiency for a power semiconductor element manufactured by the manufacturing process according to the fourth embodiment.
　従来の一般的な半導体基板製造プロセスにより製造されたエピタキシャル基板を用いて、バルク基板の研削を含む製造プロセスによりnチャネルSiC IGBTを製造した場合、図5に示すように基板外周端部のエピタキシャル層とバルク基板の界面201が屈曲若しくは湾曲し、研削面の基板外周端部では本来の裏面構造とは異なる面203が形成される(nチャネルSiC IGBTの裏面はp+型でなければいけないのだが、基板外周端部にn型のエピタキシャル層が出てきて電気測定の不良が出る要因となる)ため、基板状態のまま電気測定を行うと正確に評価できない(従来は、チップダイシングをしてから個別チップに電気測定をしていた)。一方、本発明の第４の実施形態に係る製造プロセスは、図8に示すように研削面全面において本来の裏面構造と同じ面211が形成される。したがって、図13に示すフローチャートのように、SiCエピタキシャル基板を準備しS201、前記基板を用いてnチャネルSiC IGBTの形成S202を行い、基板状態のままで電気的特性のプローブ検査S203を正確に行うことが可能となる(例えば、基板を載置するテーブル全面を基板の裏面のコレクタ電極と導通させ、基板表面側の各チップの電極にプローブを当てて電気的特性を検査する)。チップダイシングS204よりも先にプローブ検査S203を行うことにより、プローブ検査による良品選別の効率を向上させることが可能となる。 When an n-channel SiC IGBT is manufactured by a manufacturing process including grinding of a bulk substrate using an epitaxial substrate manufactured by a conventional general semiconductor substrate manufacturing process, the epitaxial layer at the outer peripheral edge of the substrate is shown in FIG. The interface 201 of the bulk substrate is bent or curved, and a surface 203 different from the original back surface structure is formed at the outer peripheral edge of the ground surface (the back surface of the n-channel SiC IGBT must be p + type) Therefore, an n-type epitaxial layer comes out at the outer peripheral edge of the substrate and causes a failure in electrical measurement), so it cannot be accurately evaluated if electrical measurement is performed in the substrate state (conventionally after chip dicing) Electrical measurements were made on individual chips). On the other hand, in the manufacturing process according to the fourth embodiment of the present invention, the same surface 211 as the original back surface structure is formed on the entire ground surface as shown in FIG. Therefore, as shown in the flowchart of FIG. 13, an SiC epitaxial substrate is prepared and S201 is formed, and an n-channel SiC IGBT is formed S202 using the substrate, and probe inspection S203 of electrical characteristics is accurately performed while the substrate is in the state. (For example, the entire surface of the table on which the substrate is placed is electrically connected to the collector electrode on the back surface of the substrate, and a probe is applied to the electrode of each chip on the substrate surface side to inspect the electrical characteristics). By performing the probe inspection S203 prior to the chip dicing S204, it becomes possible to improve the efficiency of the non-defective product selection by the probe inspection.
1　ドレイン電極
2　n+型エピタキシャル層 (ドレイン領域)
4　n-型エピタキシャル層 (ドリフト領域)
5　p型ウェル領域
6　n+型ソース領域
7　p+型ソース領域
8　ゲート絶縁膜
9　ゲート電極
10　ソース電極
11　層間絶縁膜
12　バルク基板 
31　コレクタ電極
32　p+型エピタキシャル層 (コレクタ領域)
33　n型エピタキシャル層 (バッファ領域)
34　n+型エミッタ領域
35　p+型エミッタ領域
36　エミッタ電極
200　従来の一般的な製造プロセスにより作製されたエピタキシャル基板
201　面取り面に沿って屈曲若しくは湾曲したバルク基板／エピタキシャル層界面
202　バルク基板とエピタキシャル層が同時に存在する研削面
203　基板外周端部で本来の裏面構造とは異なる層が露出する研削面
210　第１の実施形態に係る製造プロセスにより作製されたエピタキシャル基板
211　全面において本来の裏面構造と同じ面が形成された研削面
220　第２の実施形態に係る製造プロセスにより作製されたエピタキシャル基板
221　テーパーラウンド形状に面取りした基板外周端部
301　U字型状の研削断面を有する砥石
S101　スライシング (インゴットの輪切り) 工程
S102　半導体基板の基板外周端部の面取り工程
S103　半導体基板の研削工程
S104　半導体基板の研磨工程
S105　半導体基板を用いたエピタキシャル成長工程
S201　本発明に係るエピタキシャル基板製造工程
S202　パワー半導体素子製造工程
S203　電気特性のプローブ検査および良品選別工程
S204　基板からチップをダイシングする工程 1 Drain electrode
2 n + type epitaxial layer (drain region)
4 n - -type epitaxial layer (drift region)
5 p-type well region
6 n + type source region
7 p + -type source region
8 Gate insulation film
9 Gate electrode
10 Source electrode
11 Interlayer insulation film
12 Bulk substrate
31 Collector electrode
32 p + type epitaxial layer (collector region)
33 n-type epitaxial layer (buffer region)
34 n + emitter region
35 p + emitter region
36 Emitter electrode
200 Epitaxial substrates fabricated by conventional general manufacturing processes
201 Bulk substrate / epitaxial layer interface bent or curved along chamfered surface
202 Grinding surface with bulk substrate and epitaxial layer simultaneously
203 Grinding surface at which the layer different from the original back surface structure is exposed at the outer edge of the substrate
210 Epitaxial substrate manufactured by the manufacturing process according to the first embodiment
211 Ground surface with the same surface as the original back structure on the entire surface
220 Epitaxial substrate manufactured by the manufacturing process according to the second embodiment
221 Perimeter edge of substrate chamfered in taper round shape
301 Grinding wheel with U-shaped grinding section
S101 Slicing process
S102 Chamfering process of the outer peripheral edge of the semiconductor substrate
S103 Semiconductor substrate grinding process
S104 Semiconductor substrate polishing process
S105 Epitaxial growth process using semiconductor substrate
S201 Epitaxial substrate manufacturing process according to the present invention
S202 Power semiconductor device manufacturing process
S203 Electrical property probe inspection and non-defective product selection process
S204 Process of dicing chip from substrate

Claims (10)

  1. 　結晶成長により生成した半導体単結晶をバルク基板に切断し、
    　前記バルク基板の切断面のエッジを維持した状態で、前記基板の表面、および／または裏面の研削、および研磨を行い、
    　前記研磨により形成された基板外周端部を維持した状態で基板上にエピタキシャル成長を行い、
    　その後、基板外周の面取りを行うことを特徴とするエピタキシャル基板の製造方法。     A semiconductor single crystal generated by crystal growth is cut into a bulk substrate,
    While maintaining the edge of the cut surface of the bulk substrate, the front surface and / or the back surface of the substrate is ground and polished,
    Epitaxial growth on the substrate while maintaining the outer peripheral edge of the substrate formed by the polishing,
    Then, the manufacturing method of the epitaxial substrate characterized by chamfering the outer periphery of a board | substrate.
  2. 　前記基板外周の面取りがテーパーラウンド形状であることを特徴とする請求項1に記載のエピタキシャル基板の製造方法。 2. The method for manufacturing an epitaxial substrate according to claim 1, wherein the chamfering of the outer periphery of the substrate has a tapered round shape.
  3. 　バルク基板とエピタキシャル層の界面が基板外周端部まで平坦に形成され、および基板外周端部のエッジが基板側面に対して傾斜面となっているエピタキシャル基板を準備する工程と、
    　前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程と、
    　前記エピタキシャル基板を反転して、裏面のバルク基板を研削により除去する工程と、
    　前記バルク基板の除去により現れた前記エピタキシャル基板のエピタキシャル層に電極を形成する工程とを有することを特徴とする半導体装置の製造方法。     Preparing an epitaxial substrate in which the interface between the bulk substrate and the epitaxial layer is formed flat up to the outer peripheral edge of the substrate, and the edge of the outer peripheral edge of the substrate is inclined with respect to the side surface of the substrate;
    Forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate;
    Reversing the epitaxial substrate and removing the backside bulk substrate by grinding;
    And a step of forming an electrode on the epitaxial layer of the epitaxial substrate that has appeared due to the removal of the bulk substrate.
  4. 　前記エピタキシャル基板を準備する工程に続けて、裏面のバルク基板を研削により除去する工程を先に実行し、
    　前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程をその後に実行することを特徴とする請求項3に記載の半導体装置の製造方法。     Following the step of preparing the epitaxial substrate, the step of removing the bulk substrate on the back surface by grinding is executed first,
    4. The method of manufacturing a semiconductor device according to claim 3, wherein the step of forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate is subsequently performed.
  5. 　前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程が、
    　前記エピタキシャル層の第1導電型を有するドリフト層中に、第2導電型を有するウェル領域を形成する工程と、
    　前記ウェル領域内部に第1導電型を有するソース領域、および第2導電型を有するソース領域を形成する工程と、
    　前記第1導電型を有するソース領域、前記ウェル領域、および前記ドリフト層を被覆してゲート絶縁膜を形成する工程と、
    　前記ゲート絶縁膜の真上を被覆してゲート電極を形成する工程と、
    　前記ゲート電極を覆って層間絶縁膜を形成した後、前記ソース領域、および前記ウェル領域を被覆してソース電極を形成する工程と、
    　を含むことを特徴とする請求項3、または請求項4に記載の半導体装置の製造方法。     Forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate,
    Forming a well region having a second conductivity type in the drift layer having the first conductivity type of the epitaxial layer;
    Forming a source region having a first conductivity type and a source region having a second conductivity type inside the well region;
    Forming a gate insulating film covering the source region having the first conductivity type, the well region, and the drift layer;
    Forming a gate electrode by covering the gate insulating film directly above;
    Forming an interlayer insulating film covering the gate electrode, and then forming the source electrode by covering the source region and the well region;
    5. The method for manufacturing a semiconductor device according to claim 3, wherein the method includes:
  6. 　前記基板外周端部のエッジが基板側面に対して傾斜面となっているエピタキシャル基板に代えて、前記基板外周端部がテーパーラウンド形状となっているエピタキシャル基板を準備することを特徴とする請求項3に記載の半導体装置の製造方法。 The epitaxial substrate having the substrate outer peripheral end portion in a tapered round shape is prepared instead of the epitaxial substrate in which the edge of the substrate outer peripheral end portion is inclined with respect to the substrate side surface. 4. A method for manufacturing a semiconductor device according to 3.
  7. 　バルク基板とエピタキシャル層の界面が基板外周端部まで平坦に形成され、および基板外周端部のエッジが基板側面に対して傾斜面となっているエピタキシャル基板を準備する工程と、
    　前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程と、
    　前記エピタキシャル基板を反転して、裏面のバルク基板を研削により除去する工程と、
    　前記バルク基板の除去により現れた前記エピタキシャル基板のエピタキシャル層に電極を形成する工程と
    　前記エピタキシャル基板の裏面の前記電極を全面導通させて、前記エピタキシャル基板の表面の各半導体素子の電極にプローブを当てて電気的特性検査を行う工程と、
    　前記エピタキシャル基板のチップダイシングを行う工程とを有することを特徴とする半導体装置の製造方法。     Preparing an epitaxial substrate in which the interface between the bulk substrate and the epitaxial layer is formed flat up to the outer peripheral edge of the substrate, and the edge of the outer peripheral edge of the substrate is inclined with respect to the side surface of the substrate;
    Forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate;
    Reversing the epitaxial substrate and removing the backside bulk substrate by grinding;
    A step of forming an electrode on the epitaxial layer of the epitaxial substrate that appears upon removal of the bulk substrate and conducting the entire surface of the electrode on the back surface of the epitaxial substrate so that a probe is applied to the electrode of each semiconductor element on the surface of the epitaxial substrate. The electrical property inspection process,
    And a step of chip dicing the epitaxial substrate.
  8. 　前記エピタキシャル基板を準備する工程に続けて、裏面のバルク基板を研削により除去する工程を先に実行し、
    　前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程をその後に実行することを特徴とする請求項7に記載の半導体装置の製造方法。     Following the step of preparing the epitaxial substrate, the step of removing the bulk substrate on the back surface by grinding is executed first,
    8. The method for manufacturing a semiconductor device according to claim 7, wherein the step of forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate is subsequently performed.
  9. 　前記エピタキシャル基板のエピタキシャル層のドリフト層中、およびドリフト層上に半導体素子構造を形成する工程が、
    　前記エピタキシャル層の第1導電型を有するドリフト層中に、第2導電型を有するウェル領域を形成する工程と、
    　前記ウェル領域内部に第1導電型を有するエミッタ領域、および第2導電型を有するエミッタ領域を形成する工程と、
    　前記第1導電型を有するエミッタ領域、前記ウェル領域、および前記ドリフト層を被覆してゲート絶縁膜を形成する工程と、
    　前記ゲート絶縁膜の真上を被覆してゲート電極を形成する工程と、
    　前記ゲート電極を覆って層間絶縁膜を形成した後、前記エミッタ領域、および前記ウェル領域を被覆してエミッタ電極を形成する工程と、
    　を含むことを特徴とする請求項3、4、7、または請求項8のいずれか１項に記載の半導体装置の製造方法。     Forming a semiconductor element structure in and on the drift layer of the epitaxial layer of the epitaxial substrate,
    Forming a well region having a second conductivity type in the drift layer having the first conductivity type of the epitaxial layer;
    Forming an emitter region having a first conductivity type and an emitter region having a second conductivity type inside the well region;
    Forming a gate insulating film covering the emitter region having the first conductivity type, the well region, and the drift layer;
    Forming a gate electrode by covering the gate insulating film directly above;
    Forming an interlayer insulating film covering the gate electrode, and then forming an emitter electrode covering the emitter region and the well region;
    9. The method of manufacturing a semiconductor device according to claim 3, wherein the method includes:
  10. 　前記基板外周端部のエッジが基板側面に対して傾斜面となっているエピタキシャル基板に代えて、前記基板外周端部がテーパーラウンド形状となっているエピタキシャル基板を準備することを特徴とする請求項7に記載の半導体装置の製造方法。 The epitaxial substrate having the substrate outer peripheral end portion in a tapered round shape is prepared instead of the epitaxial substrate in which the edge of the substrate outer peripheral end portion is inclined with respect to the substrate side surface. 8. A method for manufacturing a semiconductor device according to 7.
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