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 .
Notice to Applicant
Applicant’s Preliminary Amendment filed on October 4, 2023 has been entered and made of record.
Specification
The title of the invention is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed (see MPEP § 606.01).
This may result in slightly longer titles, but the loss in brevity of title will be more than offset by the gain in its informative value in indexing, classifying, searching, etc.
The following title is suggested: “MULTILAYER FILM STRUCTURE INCLUDING SIC SUBSTRATE AND GAN FILM AND METHOD FOR PRODUCING THE SAME.”
If Applicant does not agree with the suggested title above, Applicant must provide a new title that clearly reflects the invention to which the claims are directed.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1, 3-7 and 9-11 are rejected under 35 U.S.C. 103 as being unpatentable over Miyakaze et al (US Pub. 2021/0301422; hereinafter “Miyakaze”) in view of Whiteley et al. (US Pub. 2021/0356658; hereinafter “Whiteley”).
Regarding Claim 1, Miyakaze discloses a multilayer film structure 10 comprising a SiC substrate 20 (page 1, paragraph 16), wherein the multilayer film structure 10 has an off-angle of 0.03o or more and 8o or less (1 to 5o; page 1, paragraph 17) with respect to a Silicon face of a (0001) plane of a SiC single crystal forming the SiC substrate 20 (page 1, paragraph 17; page 6, paragraph 53.
Miyakaze fails to disclose explicitly wherein a film disposed on the SiC substrate and containing a nitride-based material at least containing Ga, and the film containing the nitride-based material has a C content of 2 x 1019 atoms/cm3 or less and a Cl content of 2 x 1018 atoms/cm3 or less; and [Re Claim 3] wherein the nitride-based material is gallium nitride.
However, Whiteley discloses a gallium nitride (GaN) layer 910 is grown on a silicon carbide substrate 902 (page 5, paragraphs 84 and 85; see fig. 9). And Miyakaze discloses a high-frequency power device including the SiC composite substrate and GaN and AlGaN layers etc. deposited thereon (page 3, paragraph 25). Accordingly, a GaN layer may be deposited on the SiC substrate 20.
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have a GaN layer deposited on the SiC substrate, as taught by Whiteley, in order to obtain high-frequency, high-power electronic devices and light-emitting devices enabling with superior properties, including high breakdown voltage, high electron mobility, and excellent thermal stability.
Neither Miyakaze nor Whiteley explicitly disclose the carbon and chlorine concentrations in the GaN layer. However, it is well understood in the art, during a deposition of GaN layers, impurities such as carbon and chlorine are undesirable contaminants, and their concentrations are typically minimized because lower impurity levels improve material quality and device performance.
The claimed carbon and chlorine concentration limits therefore represent a degree of purity of the Ga-containing nitride film. It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to control and reduce such impurity concentrations through routine optimization of know epitaxial growth processes (e.g., by adjusting precursor purity, growth conditions, and reactor environment), thereby achieving impurity levels at or below the claimed ranges with a reasonable expectation of improved material and device performance.
Regarding Claim 4, Miyakaze discloses wherein the multilayer film structure 10 has a surface having an arithmetic average roughness (Ra) of 10.0 nm or less (0.1 nm; page 7, paragraph 60).
Regarding Claim 5, Miyakaze in view of Whiteley fails to disclose explicitly wherein the film containing the nitride-based material has a film thickness of 20 nm or more.
However, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention because determining optimum process conditions would have involved no more than routine experimentation using a limited number of result-effective variables. Accordingly, the claim is prima facie obvious unless the claimed variables produce unexpected results (see MPEP 2144.05; In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955); Peterson, 315 F.3d at 1330, 65 USPQ2d at 1382; In re Hoeschele, 406 F.2d 1403, 160 USPQ 809 (CCPA 1969)).
Furthermore, providing a nitride-based material having a certain thickness would have been obvious in order to achieve desired electrical and structural characteristics, since the film thickness directly affects strain, defect density, and overall device performance.
Regarding Claim 6, Miyakaze in view of Whiteley discloses a GaN layer is grown on a SiC substrate, as discussed in the rejection of claim 1 above. However, Whiteley does not explicitly disclose that the GaN layer has a surface with gallium (Ga) polarity.
Nevertheless, it is well understood in the art that GaN typically crystallize in a hexagonal (wurtzite) structure and may exhibit either Ga-polar or N-polar surfaces depending on growth conditions. In particular, when GaN is grown on a Si-face of (0001) plane of SiC substrate under conventional epitaxial growth conditions, Ga-polar surfaces are commonly obtained.
Therefore, the polarity of the GaN surface is a result-effective variable that depends on known process parameters, such as substrate preparations and growth conditions. It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to select or adjust these known parameters to obtain a Ga-polar GaN surface, since Ga-polar orientation is known to provide favorable growth characteristics and improved device performance.
Regarding Claim 7, Miyakaze discloses wherein an amorphous is present on the SiC substrate and the amorphous layer has a thickness of 0 nm or more and less than 1.0 nm (because the claim permits the amorphous layer to have a thickness of 0 nm, the amorphous layer need not to be physically present on the SiC substrate).
Regarding Claim 9, Miyakaze in view of Whiteley discloses wherein the film containing the nitride-based material is a gallium nitride-based sputtered film (see rejection of claim 1 above).
The underlined limitation is interpreted as a product-by-process limitation. The claim is directed to the resulting structure, not the method of formation. Miyakaze in view of Whiteley discloses a GaN layer grown on a SiC substrate (see rejection of claim 1).
“Even though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.” In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985) (citations omitted). Furthermore, “because validity is determined based on the requirements of patentability, a patent is invalid if a product made by the process recited in a product-by-process claim is anticipated by or obvious from prior art products, even if those prior art products are made by different processes.” Amgen Inc. v. F. Hoffman-La Roche Ltd., 580 F.3d 1340, 1370 n 14, 92 USPQ2d 1289, 1312, n 14 (Fed. Cir. 2009). However, in the context of an infringement analysis, a product-by-process claim is only infringed by a product made by the process recited in the claim. Id. at 1370 (see MPEP § 2113).
Regarding Claim 10, Miyakaze in view of Whiteley discloses a semiconductor device comprising the multilayer film structure according to claim 1 (see rejection of claim 1).
Regarding Claim 11, Miyakaze in view of Whiteley discloses an electronic device comprising a semiconductor device comprising according to claim 10 (see rejection of claim 1).
Claims 12-15 are rejected under 35 U.S.C. 103 as being unpatentable over Miyakaze in view of Whiteley as applied to claim 1 above, and further in view of Sasaki et al. (US Pub. 2011/0001163; hereinafter “Sasaki”).
Regarding Claim 12, Miyakaze in view of Whiteley discloses a method for producing the multilayer film structure according to claim 1 (see rejection of claim 1 above).
Miyakaze in view of Whiteley fails to disclose explicitly wherein the method comprising a step of preparing a SiC substrate, a step of immersing the SiC substrate in a cleaning solution and a step of forming, on the immersed SiC substrate, a film containing a nitride-based material by a sputtering process, wherein, during formation of the film containing the nitride-based material, a sputtering energy (Es) represented by Formula: Es = [supplied power (unit: W/cm2)]/[introduced gas pressure (unit: Pa)]2 is set to 0.1 W/cm2Pa2 or more and 150 W/cm2Pa2 or less.
However, Sasaki discloses a method comprising pretreating a substrate 11 (SiC; page 4, paragraph 79) by cleaning using a wet method such as the well-known RCA cleaning method (page 8, paragraph 150; in a standard RCA cleaning method, the substrate is immersed in the cleaning solution), a group III nitride film is forming on the pretreated substrate 11 by sputtering (page 8, paragraph 151), wherein, during formation of the film, a supplied power is preferably in a range of from 1.5 W/cm2 to 5 kW/cm2 (page 9, paragraph 158), and a pressure in a chamber is preferably 0.3 Pa or more (page 9, paragraph 159). Therefore, the sputtering energy (Es) represent by the Formula above is set to 16.7 W/cm2Pa2 or more.
It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to use a certain method to pretreat the substrate and to form the film containing a nitride-based material, as taught by Sasaki, in order to improve surface cleanliness removing surface contaminants and promote high quality deposition of the film, thereby reducing defects and enhancing the electrical and structural properties of the resulting device.
Regarding Claims 13 and 14, Sasaki fails to disclose explicitly [Re Claim 13] wherein the sputtering process is performed after an ultimate vacuum of less than 5.0 x 10-4 Pa is reached; and [Re Claim 14] wherein, during formation of the film containing the nitride-based material, an ultimate vacuum within a film-forming apparatus immediately before film formation is set to 1 x 10-4 Pa or less.
However, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention because determining optimum process conditions would have involved no more than routine experimentation using a limited number of result-effective variables. Accordingly, the claim is prima facie obvious unless the claimed variables produce unexpected results (see MPEP 2144.05; In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955); Peterson, 315 F.3d at 1330, 65 USPQ2d at 1382; In re Hoeschele, 406 F.2d 1403, 160 USPQ 809 (CCPA 1969)).
Furthermore, providing a specific ultimate vacuum prior to formation of the film containing the nitride-based material would have been obvious in order to reduce residual gas species and contamination within the deposition chamber, thereby improving film purity and uniformity, promoting high quality deposition, and enhancing overall device performance.
Regarding Claim 15, Sasaki fails to disclose explicitly wherein the sputtering process is performed using a target having a carbon content of 1 mass % or less and a chlorine content of 100 ppm or less.
However, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention because determining optimum process conditions would have involved no more than routine experimentation using a limited number of result-effective variables. Accordingly, the claim is prima facie obvious unless the claimed variables produce unexpected results (see MPEP 2144.05; In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955); Peterson, 315 F.3d at 1330, 65 USPQ2d at 1382; In re Hoeschele, 406 F.2d 1403, 160 USPQ 809 (CCPA 1969)).
Furthermore, providing a sputtering target having controlled carbon and chlorine contents would have been obvious in order to minimize incorporation of these impurities into the deposited film, thereby improving film purity, reducing defect formation, and enhancing the electrical and structural properties of the resulting device.
Allowable Subject Matter
Claims 2 and 8 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter:
Claim 2 recites a (0002) plane in a surface has a rocking-curve full width at half maximum of 5.30° or less.
Claim 8 recites the amorphous layer has a thickness of more than 0 nm and less than 1.0 nm.
These features in combination with the other elements of the base claim are neither disclosed nor suggested by the prior art of record.
Conclusion
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/CHEUNG LEE/Primary Examiner, Art Unit 2812 April 12, 2026
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