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 .
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claim(s) 1-2 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by WANG (W-X Wang et al; Tensile mechanical behaviors of silicon carbide thin films; Comp Mat Sci 62 (2012); pgs. 195-202).
Regarding claim 1, WANG discloses a silicon carbide substrate, comprising: a substrate made of silicon carbide and having a Young's modulus of 475 GPa or more at 500°C (bulk 3C-SiC such as a substrate can have a Young's Modulus E of roughly 490 GPa at 500C or 800K, see fig 7, pg. 198 and figure I below) measured by a resonance method.
Regarding the claimed feature(s) "measured by a resonance method", this is considered to be product-by-process limitation in that the silicon carbide substrate’s Young’s Modulus value is measured specifically by a resonance method. However, in a product claim, when the structure recited in the reference is substantially similar to that of the claims, the determination of how the Young’s Modulus value is measured is not patentable. The determination of patentability itself is not based on the method, but the product itself (MPEP 2113). The structure of the reference is capable of performing the same function as the claimed structure. See MPEP 2114.II: A claim containing a “recitation with respect to the manner in which a claimed apparatus is intended to be employed does not differentiate the claimed apparatus from a prior art apparatus” if the prior art apparatus teaches all the structural limitations of the claim.
Regarding claim 2, WANG discloses the silicon carbide substrate according to claim 1, wherein the substrate has a Young's modulus of 465 GPa or more at 1000°C (bulk 3C-SiC such as a substrate can have a Young's Modulus E of roughly 470 GpA at 1000C or 1300K, see fig 7, pg 198 and figure I below) measured by a resonance method.
Regarding the claimed feature(s) "measured by a resonance method", this is considered to be product-by-process limitation in that the silicon carbide substrate’s Young’s Modulus value is measured specifically by a resonance method. However, in a product claim, when the structure recited in the reference is substantially similar to that of the claims, the determination of how the Young’s Modulus value is measured is not patentable. The determination of patentability itself is not based on the method, but the product itself (MPEP 2113). The structure of the reference is capable of performing the same function as the claimed structure. See MPEP 2114.II: A claim containing a “recitation with respect to the manner in which a claimed apparatus is intended to be employed does not differentiate the claimed apparatus from a prior art apparatus” if the prior art apparatus teaches all the structural limitations of the claim.
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Figure I: WANG figure 7 with added annotations
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.
Claim(s) 3 is/are rejected under 35 U.S.C. 103 as being unpatentable over WANG (W-X Wang et al; Tensile mechanical behaviors of silicon carbide thin films; Comp Mat Sci 62 (2012); pg 195-202) in view of WIRTHS (US 20240079554).
Regarding claim 3, WANG discloses the silicon carbide substrate according to claim 1.
WANG fails to explicitly disclose a device, wherein a contaminant impurity contained in the substrate is 1.0×10^16 atoms/cm^3 or less.
WIRTHS teaches a device, wherein a contaminant impurity contained in the substrate is 1.0×10^16 atoms/cm^3 or less (substrate 20B can be 3C-SiC with a doping concentration of 1E16 or less, see fig 3A, para 58).
WANG and WIRTHS are analogous art because they both are directed towards devices with SiC semiconductor layers and one of ordinary skill in the art would have had a reasonable expectation of success to modify the device of WANG with the doping of WIRTH because they are from the same field of endeavor.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify to modify the device of WANG with the doping of WIRTH in order to make a device with lower on-resistance (see WIRTHS para 12).
Claim(s) 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over WANG (W-X Wang et al; Tensile mechanical behaviors of silicon carbide thin films; Comp Mat Sci 62 (2012); pg 195-202) in view of HARADA (US 20120061687).
Regarding claim 4, WANG discloses the silicon carbide substrate according to claim 1.
WANG fails to explicitly disclose a device, wherein the substrate has a thickness within a range of 300 to 600 μm, a specific resistance of 30 mΩ·cm or less, and an n-type impurity concentration of 5.0×10^18 to 1.0×10^20 cm^-3.
HARADA teaches a device, wherein the substrate has a thickness within a range of 300 to 600 μm (substrate 10 can have a thickness of 500 microns, see fig 2, para 121), a specific resistance of 30 mΩ·cm or less (the substrate 10 can have a resistivity of 20 mOhm*cm, see fig 2, para 121), and an n-type impurity concentration of 5.0×10^18 to 1.0×10^20 cm^-3 (the substrate 10 can have a doping concentration of 2x10^19 per cm^3, see fig 2, para 74).
WANG and HARADA are analogous art because they both are directed towards devices with SiC semiconductor substrates and one of ordinary skill in the art would have had a reasonable expectation of success to modify the device of WANG with the layer properties of HARADA because they are from the same field of endeavor.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the device of WANG with the layer properties of HARADA in order to improve channel mobility (see HARADA para 87).
Claim(s) 5-8 is/are rejected under 35 U.S.C. 103 as being unpatentable over WANG (W-X Wang et al; Tensile mechanical behaviors of silicon carbide thin films; Comp Mat Sci 62 (2012); pg 195-202) in view of BARTOLF (US 20180286963).
Regarding claim 5, WANG discloses a silicon carbide wafer comprising:
the silicon carbide substrate according to claim 1.
WANG fails to explicitly disclose a device comprising an epitaxial layer formed on the silicon carbide substrate,
wherein the epitaxial layer has a thickness within a range of 4 to 40 μm.
BARTOLF teaches a device comprising an epitaxial layer (the layer comprising 25 and 2 which is formed epitaxially on 8, see fig 1, para 63) formed on the silicon carbide substrate (substrate 8, see fig 1, para 63),
wherein the epitaxial layer has a thickness within a range of 4 to 40 μm (the total thickness of 25 and 2 can be 30 microns, see fig 1, para 33-34).
WANG and BARTOLF are analogous art because they both are directed towards devices with SiC semiconductor substrates and one of ordinary skill in the art would have had a reasonable expectation of success to modify the device of WANG with the epitaxial SiC layer of BARTOLF because they are from the same field of endeavor.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the device of WANG with the epitaxial SiC layer of BARTOLF in order to make a device with improved electrical properties (see BARTOLF para 4).
Regarding claim 6, WANG discloses the silicon carbide wafer according to claim 5.
WANG fails to explicitly disclose a device, wherein a part of the epitaxial layer has an impurity concentration of 1.0×10^15 to 1.0×10^19 cm^-3.
BARTOLF teaches a device, wherein a part of the epitaxial layer has an impurity concentration of 1.0×10^15 to 1.0×10^19 cm^-3 (2 can have a doping concentration of 1E17 per cc, see fig 1, para 33).
WANG and BARTOLF are analogous art because they both are directed towards devices with SiC semiconductor substrates and one of ordinary skill in the art would have had a reasonable expectation of success to modify the device of WANG with the epitaxial SiC layer of BARTOLF because they are from the same field of endeavor.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the device of WANG with the epitaxial SiC layer of BARTOLF in order to make a device with improved electrical properties (see BARTOLF para 4).
Regarding claim 7, WANG discloses the silicon carbide wafer according to claim 6.
WANG fails to explicitly disclose a device, wherein the epitaxial layer includes:
a buffer layer positioned adjacent to the silicon carbide substrate; and a drift layer positioned on the buffer layer,
the buffer layer has an n-type impurity concentration of 1.0×10^18 to 1.0×10^19 cm^-3, and
the drift layer has an n-type impurity concentration of 1.0×10^15 to 5.0×10^16 cm^-3.
BARTOLF teaches a device, wherein the epitaxial layer includes:
a buffer layer (buffer layer 25, see fig 1, para 34) positioned adjacent to the silicon carbide substrate; and a drift layer (drift layer 2, see fig 1, para 34) positioned on the buffer layer,
the buffer layer has an n-type impurity concentration of 1.0×10^18 to 1.0×10^19 cm^-3 (25 can have a doping concentration of 1E19 per cc, see fig 1, para 34), and
the drift layer has an n-type impurity concentration of 1.0×10^15 to 5.0×10^16 cm^-3 (2 can have a doping concentration of 1E16 per cc, see fig 1, para 33).
WANG and BARTOLF are analogous art because they both are directed towards devices with SiC semiconductor substrates and one of ordinary skill in the art would have had a reasonable expectation of success to modify the device of WANG with the epitaxial SiC layer of BARTOLF because they are from the same field of endeavor.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the device of WANG with the epitaxial SiC layer of BARTOLF in order to make a device with improved electrical properties (see BARTOLF para 4).
Regarding claim 8, WANG discloses a silicon carbide semiconductor device comprising:
the silicon carbide substrate according to claim 1.
WANG fails to explicitly disclose a device comprising an epitaxial layer formed on the silicon carbide substrate; and
a semiconductor element in which a current flows in a stacking direction of the silicon carbide substrate and the epitaxial layer.
BARTOLF teaches a device comprising an epitaxial layer formed on the silicon carbide substrate (epi layer 25 and 2 formed on 8, see fig 1, para 63); and
a semiconductor element in which a current flows in a stacking direction of the silicon carbide substrate and the epitaxial layer (the device can be a vertical device which will have vertical current flow, see fig 1, para 54).
WANG and BARTOLF are analogous art because they both are directed towards devices with SiC semiconductor substrates and one of ordinary skill in the art would have had a reasonable expectation of success to modify the device of WANG with the epitaxial SiC layer of BARTOLF because they are from the same field of endeavor.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the device of WANG with the epitaxial SiC layer of BARTOLF in order to make a device with improved electrical properties (see BARTOLF para 4).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JONAS TYLER BEARDSLEY whose telephone number is (571)272-3227. The examiner can normally be reached 930-600 M-F.
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/JONAS T BEARDSLEY/Examiner, Art Unit 2811
/LYNNE A GURLEY/Supervisory Patent Examiner, Art Unit 2811
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