DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Priority
Acknowledgment is made of applicant’s claim for foreign priority under 35 U.S.C. 119 (a)-(d). The certified copy has been filed on August 08, 2024.
Information Disclosure Statement
The information disclosure statement (IDS) filed on August 08, 2024 has been considered by the examiner.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claim 2 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 2 recites the limitation "… an area density of the second region is more than 0 and 2.0 /cm2 or less" in lines 7-8. It is unclear as to which range of area density is claimed.
For the purpose of examination, the Examiner will interpret "… an area density of the second region is more than 0 and 2.0 /cm2 or less" as the following, "… an area density of the second region is more than 0 and less than 2.0 /cm2".
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-10 are rejected under 35 U.S.C. 103 as being unpatentable over Wada (US 2018/0096854 A1) in view of Wada (US 2018/0363166 A1), hereinafter, Wada*.
Claim 1, Wada discloses a silicon carbide epitaxial substrate (silicon carbide epitaxial substrate 101, [0101], Fig. 13) comprising:
a silicon carbide substrate (silicon carbide single crystal substrate 10 is a silicon carbide substrate, hereinafter, silicon carbide substrate 10, [0101], Fig. 13); and
a silicon carbide layer (first layer 11 and epitaxial layer 13 are a silicon carbide layer, hereinafter, silicon carbide layer 11/13, [0073], Fig. 13) located on the silicon carbide substrate 10 (silicon carbide layer 11/13 is located on the silicon carbide substrate 10, [0073], Fig. 13), wherein
the silicon carbide layer 11/13 includes a first region 11/13/30, and a second region 34 surrounded by the first region 11/13/30 when viewed in a plan view (silicon carbide layer 11/13 includes a first region 11/13/30, and a second region 34 surrounded by the first region 30 when viewed in a plan view, [0073], Fig. 13),
the second region 34 has a third region expanded in a <11-20> (i.e. <
11
2
-
0
>) direction (second region 34 has a trapezoidal defect 20 which is a third region expanded in a <
11
2
-
0
> direction, hereinafter, third region 20, [0076], Figs. 7 and 13), the first region 11/13/30 is composed of silicon carbide having a polytype of 4H (first region 11/13/30 is composed of silicon carbide having a polytype of 4H, [0050], Figs. 2 and 13), and
when a surface of the first region 11/13/30 is defined as a first surface (upper base portion 21 which is a first surface, hereinafter, first surface 21, [0087], Figs. 11 and 13) and a surface of the third region 20 is defined as a second surface (lower base portion 22 which is a second surface, hereinafter, second surface 22, [0087], Figs. 7 and 13), at least a portion of the second surface 22 protrudes with respect to the first surface 21 in a direction from the silicon carbide substrate 10 toward the silicon carbide layer 11/13 (at least a portion of the second surface 22 protrudes with respect to the first surface 21 in a direction from the silicon carbide substrate 10 toward the silicon carbide layer 11/13, [0080], Figs. 7 and 13).
Wada does not explicitly disclose wherein the third region is composed of silicon carbide having a polytype of 3C.
However, Wada* (US 2018/0363166 A1) discloses the third region is composed of silicon carbide having a polytype of 3C (Wada*, second region has a trapezoidal defect 70 which is a third region expanded in a <
11
2
-
0
> direction, hereinafter, third region 70 and is composed of silicon carbide having a polytype of 3C, [0125], Fig. 11; Wada, third region 20, [0076], Figs. 7 and 13). The combination to utilize both 4H and 3C polytypes of silicon carbide enables in-plane uniformity of a carrier concentration to be improved and surface roughness can be reduced (Wada*, [0063]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date to utilize both 4H and 3C polytypes of silicon carbide to enable in-plane uniformity of a carrier concentration to be improved and surface roughness can be reduced (Wada*, [0063]).
Claim 2, Wada/Wada*discloses the silicon carbide epitaxial substrate (Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44) according to claim 1.
Wada/Wada* discloses wherein the silicon carbide layer includes a main surface (Wada, silicon carbide layer 11/13 includes a third main surface 93 which is a main surface, hereinafter, main surface 93, [0073], Fig. 13; Wada*, third region 70 and is composed of silicon carbide having a polytype of 3C, [0125], Fig. 11), the main surface being located opposite to a boundary surface between the silicon carbide substrate and the silicon carbide layer (Wada, main surface 93 is located opposite to a boundary surface between the silicon carbide substrate 10 and the silicon carbide layer 11/13, [0073], Fig. 13; Wada*, third region 70 and is composed of silicon carbide having a polytype of 3C, [0125], Fig. 11), the main surface being constituted of the first surface and the second surface (Wada, main surface 93 is constituted of the first surface 21 and the second surface 22, [0073], Fig. 13; Wada*, third region 70 and is composed of silicon carbide having a polytype of 3C, [0125], Fig. 11), and
in the main surface, an area density of the second region is more than 0 and less than 2.0 /cm2 93 (i.e. including first surface 21 and second surface 22), an area density of the second region 34 may be more than 0 /cm2 and less than 0.5 /cm2, [0073], Fig. 13; Wada*, third region 70 and is composed of silicon carbide having a polytype of 3C, [0125], Fig. 11).
Claim 3, Wada/Wada*discloses the silicon carbide epitaxial substrate (Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44) according to claim 1.
Wada/Wada* discloses wherein in the direction from the silicon carbide substrate toward the silicon carbide layer, a distance between the first surface and a most-protruding portion of the second surface is 5 nm or more and 100 nm or less (Wada, in the direction from the silicon carbide substrate 10 toward the silicon carbide layer 11/13, a distance between the first surface 21 and a most-protruding portion of the second surface 22 is 5 nm or more and 20 nm or less; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44)
Claim 4, Wada/Wada*discloses the silicon carbide epitaxial substrate (Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44) according to claim 1.
Wada/Wada* discloses wherein when viewed in the direction from the silicon carbide layer toward the silicon carbide substrate, the second region has a bottom side extending in a direction perpendicular to the <11-20> (i.e. <
11
2
-
0
>) direction (Wada, when viewed in the direction from the silicon carbide layer 11/13 toward the silicon carbide substrate 10, the second region 34 has a bottom side extending in a direction perpendicular to the <
11
2
-
0
> direction, [0081], Fig. 9; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44).
Claim 5, Wada/Wada*discloses the silicon carbide epitaxial substrate (Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44) according to claim 1.
Wada/Wada* discloses wherein a whole of the second surface protrudes with respect to the first surface in the direction from the silicon carbide substrate toward the silicon carbide layer (Wada, wherein a whole of the second surface 22 protrudes with respect to the first surface 21 in the direction from the silicon carbide substrate 10 toward the silicon carbide layer 11/13, [0081], Fig. 9; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44).
Claim 6, Wada/Wada*discloses the silicon carbide epitaxial substrate (Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44) according to claim 1.
Wada/Wada* discloses wherein the second region has a fourth region recessed with respect to the first surface (Wada, wherein the second region 34 has a fourth region 23 recessed with respect to the first surface 21, [0080], Fig. 7; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44),
the fourth region has a third surface (Wada, fourth region 23 has a third surface 91, [0080], Fig. 7; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44),
the first surface is located between the second surface and the third surface in the direction from the silicon carbide substrate toward the silicon carbide layer (Wada, first surface 21 is located between the second surface 22 and the third surface 91 in the direction from the silicon carbide substrate 10 toward the silicon carbide layer 11/13, [0080], Fig. 7; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44), and
in the <11-20> (i.e. <
11
2
-
0
>) direction, a width of the second surface is 10 µm or more (Wada, in the <
11
2
-
0
> direction, a width of the second surface 21 is 10 µm or more, [0077], Fig. 6; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44).
Claim 7, Wada/Wada*discloses the silicon carbide epitaxial substrate (Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44) according to claim 1.
Wada/Wada* discloses further comprising a downfall contiguous to the second region (Wada*, further comprising a downfall contiguous to the second region 53, [0116], Figs. 23 and 44; Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13).
Claim 8, Wada discloses a silicon carbide epitaxial substrate (silicon carbide epitaxial substrate 101, [0101], Fig. 13) comprising:
a silicon carbide substrate (silicon carbide single crystal substrate 10 is a silicon carbide substrate, hereinafter, silicon carbide substrate 10, [0101], Fig. 13); and
a silicon carbide layer (first layer 11 and epitaxial layer 13 are a silicon carbide layer, hereinafter, silicon carbide layer 11/13, [0073], Fig. 13) located on the silicon carbide substrate 10 (silicon carbide layer 11/13 is located on the silicon carbide substrate 10, [0073], Fig. 13), wherein
the silicon carbide layer 11/13 includes a first region 11/13/30, and a second region 34 surrounded by the first region 11/13/30 when viewed in a plan view (silicon carbide layer 11/13 includes a first region 11/13/30, and a second region 34 surrounded by the first region 30 when viewed in a plan view, [0073], Fig. 13), and
the second region 34 has a third region expanded in a <11-20> (i.e. <
11
2
-
0
>) direction (second region 34 has a trapezoidal defect 20 which is a third region expanded in a <
11
2
-
0
> direction, hereinafter, third region 20, [0076], Figs. 7 and 13).
Wada does not explicitly disclose the first region and the third region are observed using a confocal differential interference microscope in a state in which a light source is disposed opposite to the third region in the <11-20> (i.e. <
1
1
-
00
>) direction when viewed in a plan view and is disposed in a <1-100> (i.e. <
1
1
-
00
>) direction, a side of the third region located close to the light source is brighter than each of a surface of the third region and a surface of the first region, and a side of the third region located away from the light source is darker than each of the surface of the third region and the surface of the first region..
However, Wada* discloses the first region and the third region are observed using a confocal differential interference microscope in a state in which a light source is disposed opposite to the third region in the <
1
1
-
00
> direction when viewed in a plan view and is disposed in a <
1
1
-
00
> direction (Wada*, the first region 30 and the third region 70 are observed using a confocal differential interference microscope in a state in which a light source is disposed opposite to the third region 70 in the <
1
1
-
00
> direction when viewed in a plan view and is disposed in a <
1
1
-
00
> direction, [0123], Figs. 23 and 44; Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13), a side of the third region located close to the light source is brighter than each of a surface of the third region and a surface of the first region (Wada*, a side of the third region 70 located close to the light source is brighter than each of a surface of the third region 70 and a surface of the first region 30, [0114], Figs. 23 and 44; Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13), and a side of the third region located away from the light source is darker than each of the surface of the third region and the surface of the first region (Wada*, a side of the third region 70 located away from the light source is darker than each of the surface of the third region 70 and the surface of the first region 30, [0114], Figs. 23 and 44; Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13). The combination to utilize a confocal differential interference microscope in combination with a haze measurement would ensure specification of the type, location, and number of defects present in the sample as well as enables in-plane uniformity of a carrier concentration to be improved and surface roughness can be reduced (Wada*, [0063] and [0123]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date to utilize a confocal differential interference microscope in combination with a haze measurement to ensure specification of the type, location, and number of defects present in the sample as well as to enable in-plane uniformity of a carrier concentration to be improved and surface roughness can be reduced (Wada*, [0063] and [0123]).
Claim 9, Wada/Wada*discloses the silicon carbide epitaxial substrate (Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44) according to claim 8.
Wada/Wada* discloses wherein the first region is composed of silicon carbide having a polytype of 4H (Wada, first region 11/13/30 is composed of silicon carbide having a polytype of 4H, [0050], Figs. 2 and 13; Wada*, second region has a trapezoidal defect 70 which is a third region expanded in a <
11
2
-
0
> direction, hereinafter, third region 70 and is composed of silicon carbide having a polytype of 3C, [0125], Fig. 11), and
the third region is composed of silicon carbide having a polytype of 3C (Wada*, second region has a trapezoidal defect 70 which is a third region expanded in a <
11
2
-
0
> direction, hereinafter, third region 70 and is composed of silicon carbide having a polytype of 3C, [0125], Fig. 11; Wada, third region 20, [0076], Figs. 7 and 13).
Claim 10, Wada/Wada* discloses a method of manufacturing a silicon carbide semiconductor device (Wada, silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44), the method comprising:
preparing the silicon carbide epitaxial substrate according to claim 1 (Wada, preparing the silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, preparing the silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44); and
processing the silicon carbide epitaxial substrate (Wada, processing the silicon carbide epitaxial substrate 101, [0101], Fig. 13; Wada*, processing the silicon carbide epitaxial substrate 100/101, [0048], Figs. 2, 11, and 44).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Ellison (US 2009/0230406 A1) discloses a silicon carbide epitaxial substrate (SiC substrate including a SiC homoepitaxial boundary layer and a SiC homoepitaxial device layer, Abstract) comprising: a silicon carbide substrate SiC substrate; and a silicon carbide layer SiC homoepitaxial device layer located on the silicon carbide substrate SiC substrate, wherein the silicon carbide layer includes a first region, and a second region surrounded by the first region when viewed in a plan view, the second region has a third region expanded in a <11-20> (i.e. <
11
2
-
0
>) direction, the first region is composed of silicon carbide having a polytype of 4H, the third region is composed of silicon carbide having a polytype of 3C, and when a surface of the first region is defined as a first surface and a surface of the third region is defined as a second surface, at least a portion of the second surface protrudes with respect to the first surface in a direction from the silicon carbide substrate toward the silicon carbide layer.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to CHEVY J BOEGEL whose telephone number is (703)756-1299. The examiner can normally be reached Monday - Friday 8:00 AM - 5:00 PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, William Partridge can be reached at 571-270-1402. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/CHEVY J BOEGEL/Examiner, Art Unit 2812
/William B Partridge/Supervisory Patent Examiner, Art Unit 2812
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