WO2019059102A1 - 炭化珪素半導体基板を用いた半導体装置の製造方法 - Google Patents

炭化珪素半導体基板を用いた半導体装置の製造方法 Download PDF

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Publication number
WO2019059102A1
WO2019059102A1 PCT/JP2018/034054 JP2018034054W WO2019059102A1 WO 2019059102 A1 WO2019059102 A1 WO 2019059102A1 JP 2018034054 W JP2018034054 W JP 2018034054W WO 2019059102 A1 WO2019059102 A1 WO 2019059102A1
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WIPO (PCT)
Prior art keywords
trench
epitaxial layer
silicon carbide
shape
forming
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Ceased
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PCT/JP2018/034054
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English (en)
French (fr)
Japanese (ja)
Inventor
愛子 梶
周平 箕谷
治人 市川
竹内　有一
渡辺　行彦
成岡　英樹
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Denso Corp
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Denso Corp
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Publication of WO2019059102A1 publication Critical patent/WO2019059102A1/ja
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
    • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
    • H10P72/50—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for positioning, orientation or alignment

Definitions

  • the present disclosure relates to a method of manufacturing a SiC semiconductor device configured using a silicon carbide (hereinafter referred to as SiC) semiconductor substrate on which alignment marks are formed.
  • SiC silicon carbide
  • a trench serving as an alignment mark is formed on such a SiC semiconductor substrate, and an impurity region having a planar pattern is formed by ion implantation or the like.
  • a predetermined manufacturing process such as growing an epitaxial layer or heat treatment is performed.
  • the position of the alignment mark is specified by the reader, and a predetermined semiconductor manufacturing process using resist patterning or the like is subsequently performed based on the alignment mark.
  • the epitaxial layer when the epitaxial layer is grown on the SiC semiconductor substrate in which the trench is formed, the epitaxial layer may not grow (that is, deposit) along the wall surface on the downstream side in the off direction of the trench. . That is, when the epitaxial layer is grown on the SiC semiconductor substrate, the epitaxial layer may be grown on the downstream side in the off direction of the trench so as to form a facet of the (0001) plane. In this case, the position of the alignment mark can not be specified with high precision due to the influence of the facets, and pattern deviation may occur before and after formation of the epitaxial layer.
  • Patent Document 1 when an epitaxial layer is grown on a SiC semiconductor substrate and a facet is formed on the downstream side in the off direction of the trench, a new trench is formed on the facet. It has been disclosed to form
  • the new trench is formed in the facet of the (0001) plane. Therefore, even if the epitaxial layer is further grown on the SiC semiconductor substrate or heat treatment is performed, formation of a facet on the downstream side in the off direction of the new trench can be suppressed. it can. Therefore, by reading the new trench as the alignment mark by the reader, it is possible to suppress the occurrence of positional deviation when specifying the position of the alignment mark.
  • the off direction means "a direction parallel to a vector obtained by projecting the normal vector of the growth surface onto the (0001) plane".
  • the downstream side in the off direction defines one of the sides, and means "the side where the tip of the vector obtained by projecting the normal vector of the growth surface onto the (0001) plane is facing”.
  • An object of the present disclosure is to provide a method of manufacturing a SiC semiconductor device capable of accurately reading a trench formed in an epitaxial layer without increasing or complicating a manufacturing process.
  • a SiC semiconductor device in a method of manufacturing a SiC semiconductor device, it is a SiC single crystal having a main surface provided with an off angle in the (0001) plane and having an off direction of ⁇ 11-20>.
  • Providing a structured SiC semiconductor substrate, forming a first trench in the main surface, and SiC having a second trench on the main surface that inherits the shape of the first trench formed in the main surface And growing the epitaxial layer formed in the second trench and performing predetermined processing by reading the second trench, and forming the first trench, the opening is rectangular and the longitudinal direction is off.
  • a plurality of first trenches parallel to the direction are formed along the direction orthogonal to the off direction.
  • the openings are rectangular and a plurality of first trenches having a longitudinal direction parallel to the off direction are formed along the direction orthogonal to the off direction, the first trenches are turned off.
  • the length in the direction orthogonal to the direction becomes short. Therefore, when the epitaxial layer is grown, formation of facets can be suppressed on the downstream side in the off direction of each first trench. Therefore, the second trench can be read with high accuracy.
  • the manufacturing process is not increased or complicated.
  • FIG. 7 is a cross-sectional view showing the manufacturing process of the SiC semiconductor device in the first embodiment. It is sectional drawing which shows the manufacturing process of the SiC semiconductor device in 1st Embodiment following FIG. 1A. It is sectional drawing which shows the manufacturing process of the SiC semiconductor device in 1st Embodiment following FIG. 1B. It is a top view which shows the planar shape and arrangement
  • FIG. 16 is a cross sectional view showing a manufacturing step of the SiC semiconductor device in the second embodiment, and a cross sectional view of an alignment mark formation region. It is sectional drawing which shows the manufacturing process of the SiC semiconductor device in 2nd Embodiment following FIG. 5A. It is sectional drawing which shows the manufacturing process of the SiC semiconductor device in 2nd Embodiment following FIG. 5B. It is sectional drawing which shows the manufacturing process of the SiC semiconductor device in 2nd Embodiment following FIG. 5C. It is a top view which shows the planar shape and arrangement of a trench used as a mark for alignment inspection. It is a top view of the test pattern vicinity in FIG. 5D.
  • the SiC semiconductor substrate 10 configured by the above is prepared.
  • a region for forming an alignment mark is referred to as an alignment mark formation region R1
  • a region for forming a device such as a semiconductor element is referred to as a device formation region R2.
  • a mask material 11 such as a resist is disposed on the main surface of SiC semiconductor substrate 10, and a region corresponding to a trench formation planned region of mask material 11 is opened. Then, while the SiC semiconductor substrate 10 is covered with the mask material 11, anisotropic dry etching such as RIE (that is, Reactive Ion Etching) is performed to form a trench 12 to be an alignment mark in the alignment mark formation region R1. Do. In the present embodiment, the trench 12 corresponds to a first trench and a first main trench.
  • RIE Reactive Ion Etching
  • a plurality of trenches 12 having rectangular openings and whose longitudinal direction is parallel to the off direction are formed along the direction orthogonal to the off direction.
  • the more detailed shape of the trench 12 will be described later.
  • an epitaxial layer 13 composed of SiC is grown on the SiC semiconductor substrate 10 by, for example, a CVD (that is, Chemical Vapor Deposition) method.
  • a CVD that is, Chemical Vapor Deposition
  • the shape of the SiC semiconductor substrate 10 to be the base is taken over to the surface of the epitaxial layer 13. Therefore, on the surface of epitaxial layer 13, trench 14 is formed at a position corresponding to trench 12. Then, the trench 14 becomes a new alignment mark.
  • the trench 14 corresponds to a second trench and a second main trench.
  • a facet may be formed on the downstream side of the trench 14 in the off direction, but the facet is formed depending on the length of the trench 14 in the direction orthogonal to the off direction. That is, as the length in the direction orthogonal to the off direction is shorter, the facets are less likely to be formed. Therefore, formation of the facets can be suppressed by forming the trench 12 so that the opening has a rectangular shape and the longitudinal direction is parallel to the off direction as in the present embodiment.
  • the epitaxial layer 13 if the growth rate is too fast, defects such as 3C-SiC defects may be generated. For this reason, in the present embodiment, the epitaxial layer 13 is grown under the conditions of a growth rate of 2 ⁇ m / h or less.
  • the trench 14 serving as an alignment mark is read by a reader (not shown), and a predetermined manufacturing process such as ion implantation or etching is performed on the device formation region R2.
  • the laser diode when reading an alignment mark with a reader, the laser diode is irradiated with a plurality of laser beams while scanning the reader, and the SiC semiconductor substrate 10 on which the epitaxial layer 13 is formed is reflected. Analyze the information contained in the received laser light. Thereby, the formation position of the trench 14 is specified.
  • the intensity of the laser beam reflected by the epitaxial layer 13 depends on the distance between the light source and the epitaxial layer 13 in the reader, and is compared with the portion where the alignment mark is not formed. Distance becomes longer and the strength becomes weaker. Therefore, the position of the alignment mark can be specified by reading the intensity signals of the plurality of reflected laser beams, for example.
  • the reading device converts the read intensity signal into a signal that causes a peak to appear when the intensity signal changes, for example.
  • the position of the alignment mark can also be identified based on the signal.
  • the trench 12 has a rectangular shape whose short side is a direction in which the opening is orthogonal to the off direction.
  • the formation of facets in the trench 14 is suppressed. Therefore, the reading of the alignment mark by the reader can be performed with high accuracy.
  • each trench 12 of the present embodiment will be described with reference to FIGS. 3 and 4.
  • the readable range is different between the case where the epitaxial layer 13 is grown to 1.4 ⁇ m and the case where the epitaxial layer 13 is grown to 2.1 ⁇ m, and the film of the epitaxial layer 13 is different.
  • the thicker the thickness the narrower the readable range.
  • hatched portions that is, portions surrounded by straight lines L1 to L5 each have a shape of trench 12 in which trench 14 can be read with high accuracy.
  • the shape of the trench 12 be defined in consideration of the film thickness of the epitaxial layer 13 to be grown, and the trench 12 is formed so as to satisfy all of the following mathematical expressions 1 to 5.
  • the length in the direction perpendicular to the longitudinal direction of trench 12 and along the surface direction of SiC semiconductor substrate 10 is also referred to as width w of trench 12, and the depth of trench 12 is the depth of trench 12. It is also called d.
  • the width W of the trench 12 is in the vertical direction in the drawing.
  • the trench 14 can not be read with high accuracy, the trench 14 can be read with high accuracy by the presence of a plurality of intensity change peaks (that is, facets) in the intensity signal read by the reader. Cases that can not be included are included.
  • the case where the intensity change itself can not be read clearly may be included.
  • FIG. 3 shows that the trench 14 may be able to be read correctly if the width w is about 1.3 ⁇ m or more. It is shown in FIG. 4 that the trench 14 may be able to be read correctly if the width w is greater than about 1.95 ⁇ m. Therefore, when the film thickness of the epitaxial layer 13 to be grown is t, the trench 12 is formed to satisfy the following equation.
  • the trench 12 is easily filled and the trench 14 is not formed in the epitaxial layer 13 if the trench 12 has a small depth d even if the width w is slightly increased. That is, the reading device can not read the alignment mark.
  • FIG. 3 shows that it may be possible to read the trench 14 correctly if d ⁇ ⁇ 0.56 w + 1.18.
  • FIG. 4 shows that it may be possible to read the trench 14 correctly if d ⁇ ⁇ 0.86 w + 1.76.
  • the trench 12 is formed such that the width w and the depth d satisfy the following equation based on the film thickness t of the epitaxial layer 13 to be grown.
  • the trench 12 is formed such that the depth d satisfies the following equation based on the thickness t of the epitaxial layer 13 to be grown.
  • the trench 12 may not be able to accurately read the trench 14 by the reading device. This is because the shape of the opening of the trench 14 becomes gentle depending on the shape of the trench 12 and the reader can not clearly detect the change of the intensity signal. It is shown in FIG. 3 that it may be possible to read the trench 14 correctly if d ⁇ 0.67 w ⁇ 1.4. It is shown in FIG. 4 that the trench 14 may be able to be read correctly if d ⁇ 1.0 w ⁇ 2.1. For this reason, the trench 12 is formed such that the width w and the depth d satisfy the following equation based on the film thickness t of the epitaxial layer 13 to be grown.
  • FIGS. 3 and 4 show that the trench 14 may be able to be read correctly if the width w is less than about 3.0 ⁇ m. Therefore, the trench 12 is formed to satisfy the following equation.
  • the trench 12 is formed so as to satisfy the equations 1 to 4 based on the film thickness t of the epitaxial layer 13 while satisfying the equation 5.
  • a plurality of the trenches 12 whose opening is rectangular and whose longitudinal direction is parallel to the off direction are formed in the direction orthogonal to the off direction. Therefore, when the epitaxial layer 13 is grown, formation of facets on the downstream side in the off direction of each trench 12 is suppressed. Therefore, trench 14 after epitaxial layer 13 is grown can be read with high accuracy as an alignment mark. Further, in the present embodiment, since it is not necessary to form a new trench, the number of manufacturing steps is not increased or complicated.
  • the trench 12 has a width w of 3.0 ⁇ m or less. Thus, the formation of facets in the trench 14 is suppressed.
  • the trench 12 is formed so as to satisfy the above formulas (1) to (4). Therefore, it can be suppressed that the trench 14 is not formed in the epitaxial layer 13 and that the trench 14 formed in the epitaxial layer 13 can not be read correctly.
  • the region corresponding to the trench formation planned region of the mask material 11 and the region corresponding to the inspection trench formation planned region are opened. Do. Then, while the SiC semiconductor substrate 10 is covered with the mask material 11, anisotropic dry etching such as RIE is performed to form the inspection trench 21 together with the trench 12 in the alignment mark formation region R1.
  • the inspection trench 21 has a first direction trench 21a and a second direction trench 21b.
  • the first direction trench 21a and the second direction trench 21b are formed such that a region surrounded by the first direction trench 21a and the second direction trench 21b has a substantially shape.
  • the first direction trench 21 a has the same shape as the trench 12. Further, in the present embodiment, two rows of first direction trenches 21a are formed along the direction orthogonal to the off direction.
  • the second direction trench 21b has a rectangular shape whose longitudinal direction is the off direction, and the length in the longitudinal direction is larger than that of the first direction trench 21a.
  • the second direction trenches 21b are formed on both end sides in the arrangement direction of the first direction trenches 21a.
  • the first direction trench 21a corresponds to the first trench and the first sub-trench.
  • the inspection trench 22 which inherits the shape of the inspection trench 21 is formed together with the trench 14.
  • the inspection trench 22 corresponds to a second trench and a second sub-trench.
  • a film 23 for pattern formation made of an oxide film or the like is formed by a CVD method or the like.
  • the trench 15 corresponding to the shape of the trench 14 and the inspection trench 24 corresponding to the shape of the inspection trench 22 are formed in the film 23 for pattern formation. That is, in the pattern forming film 23, the inspection trench 24 which inherits the shapes of the trench 14 and the inspection trench 22 is formed.
  • the trench 15 corresponds to a third main trench
  • the inspection trench 24 corresponds to a third sub-trench.
  • a resist 25 is formed on the pattern forming film 23 by a coating method or the like.
  • the trench 16 corresponding to the shape of the trench 15 and the inspection trench 26 corresponding to the shape of the inspection trench 24 are formed. That is, in the resist 25, the inspection trench 26 which inherits the shape of the trench 15 and the shape of the inspection trench 24 is formed.
  • the trench 16 corresponds to a fourth main trench
  • the inspection trench 26 corresponds to a fourth sub-trench.
  • the resist 25 is exposed and developed to pattern the resist 25.
  • an inspection pattern 27 composed of a trench is simultaneously formed in the resist 25.
  • the inspection pattern 27 is formed in the region surrounded by the inspection trench 26.
  • the inspection pattern 27 and the inspection trench 26 are read by a reading device (not shown), and the distance between the inspection pattern 27 and the inspection trench 26 is measured to inspect the alignment accuracy.
  • the inspection trench 26 and the inspection pattern 27 formed on the first direction trench 21a are read along the off direction, and the intervals x1 and x2 are measured.
  • the inspection trench 26 and the inspection pattern 27 formed on the second direction trench 21b are read along the direction orthogonal to the off direction, and the interval y1 and the interval y2 are measured. Then, it is determined whether or not each interval x1, x2, y1, y2 is an allowable error, and if it is an allowable error, the subsequent steps are performed using the resist 25 as a mask.
  • the resist 25 is removed and a new resist is formed again. Then, new inspection patterns are formed in consideration of the measured intervals x1, x2, y1, and y2 so that the intervals x1, x2, y1, and y2 become tolerances.
  • a plurality of first direction trenches 21a having a rectangular opening and a longitudinal direction parallel to the off direction are formed in the direction orthogonal to the off direction. Therefore, when the epitaxial layer 13 is grown, formation of facets is suppressed on the downstream side of the first direction trenches 21 a in the off direction. That is, when the pattern forming film 23 and the resist 25 are formed on the epitaxial layer 13, formation of facets in the inspection trenches 24 and 26 formed on the first direction trench 21 a is suppressed. Therefore, the inspection trench 26 formed on the first direction trench 21a can be read with high accuracy, and in particular, the alignment inspection regarding positional deviation in the off direction can be performed with high accuracy.
  • the 4H-type SiC semiconductor substrate 10 has been described as an example, but other polymorphic SiC semiconductor substrates such as 6H-type, 3C-type, 15R-type, etc. may be used. Also, although 4 ° has been exemplified as the off angle with respect to the (0001) plane, other angles may be used.
  • the inspection trench 21 may have only the first direction trench 21a. In this case, only one row of first direction trenches 21a may be formed in the direction orthogonal to the off direction.
  • a bar (-) should normally be added above the desired number, but since there is a limitation in expression based on the electronic application, it is desirable in the present specification to be a desired one. A bar shall be put in front of the numbers.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)
PCT/JP2018/034054 2017-09-19 2018-09-13 炭化珪素半導体基板を用いた半導体装置の製造方法 Ceased WO2019059102A1 (ja)

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JP2017-179509 2017-09-19

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04127551A (ja) * 1990-09-19 1992-04-28 Fujitsu Ltd 露光パターンの検査方法
JP2002031885A (ja) * 2000-07-17 2002-01-31 Nikon Corp マスク、露光装置の検査方法、並びに露光方法
JP2003142357A (ja) * 2001-11-05 2003-05-16 Denso Corp 半導体装置の製造方法、エピタキシャル膜の膜厚測定方法及び半導体装置
JP2005328014A (ja) * 2004-04-14 2005-11-24 Denso Corp 半導体装置の製造方法
JP2008053363A (ja) * 2006-08-23 2008-03-06 Matsushita Electric Ind Co Ltd 半導体基板およびその製造方法
JP2009170558A (ja) * 2008-01-14 2009-07-30 Denso Corp 炭化珪素半導体装置の製造方法
WO2014199749A1 (ja) * 2013-06-13 2014-12-18 住友電気工業株式会社 炭化珪素半導体装置の製造方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04127551A (ja) * 1990-09-19 1992-04-28 Fujitsu Ltd 露光パターンの検査方法
JP2002031885A (ja) * 2000-07-17 2002-01-31 Nikon Corp マスク、露光装置の検査方法、並びに露光方法
JP2003142357A (ja) * 2001-11-05 2003-05-16 Denso Corp 半導体装置の製造方法、エピタキシャル膜の膜厚測定方法及び半導体装置
JP2005328014A (ja) * 2004-04-14 2005-11-24 Denso Corp 半導体装置の製造方法
JP2008053363A (ja) * 2006-08-23 2008-03-06 Matsushita Electric Ind Co Ltd 半導体基板およびその製造方法
JP2009170558A (ja) * 2008-01-14 2009-07-30 Denso Corp 炭化珪素半導体装置の製造方法
WO2014199749A1 (ja) * 2013-06-13 2014-12-18 住友電気工業株式会社 炭化珪素半導体装置の製造方法

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