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
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 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.
Claim(s) 5 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Yoshida et al (JP 2013-033887), an English computer translation is provided.
Yoshida et al teaches a method for manufacturing a nitride semiconductor substrate in which a nitride semiconductor is formed on a substrate for film formation, the method comprising the steps of: (1) subjecting a substrate 1 for film formation made of single-crystal silicon to heat treatment under a nitrogen atmosphere to form a silicon nitride film 2 on the substrate for film formation; (2) growing an AIN film 3 on the silicon nitride film; and (3) growing a GaN film on the AlN film (CT [0012]; [0050]-[0055]) teaches forming a silicon nitride layer on a silicon single crystal substrate by heating to 900-1000°C in a 100 vol% nitrogen gas). Yoshida et al teaches a silicon nitride thickness of 1 nm or more and 3 nm or less; and an explicit example of 1.8 nm (CT [0044]; [0069]).
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
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.
Claim(s) 7 and 9 is/are rejected under 35 U.S.C. 102(a)(1) as anticipated by or, in the alternative, under 35 U.S.C. 103 as obvious over Yoshida et al (JP 2013-033887), an English computer translation is provided, as applied to claim 5 above.
Referring to claim 7, Yoshida et al does not explicitly teach the silicon nitride is a single crystal. Yoshida et al teaches forming a single crystal aluminum nitride on the silicon nitride layer (Yoshida CT [0050]-[0053]); therefore, the silicon nitride layer would be expected to be a single crystal to be suitable to form a single crystal AlN, thereon. In the alternative, it would have been obvious to one of ordinary skill in the art at the time of filing to modify Yoshida et al to have a single crystal SiN layer to make a substrate suitable for single crystal growth.
Referring to claim 9, Yoshida et al teaches all of the limitations of claim 9 except Yoshida et al does not explicitly teach an Al diffusion concentration of 4e15 atoms/cm3 or less on a growth substrate surface. Yoshida et al teaches a silicon nitride thickness of 1 nm or more and 3 nm or less; and an explicit example of 1.8 nm (CT [0044]; [0069]).
Applicant teaches a silicon nitride film with a thickness preferably 1 to 4 nm, particularly about 2 nm; and when the silicon nitride film is formed, the diffusion of Al to the surface of a high resistance single-crystal silicon growth substrate from the AlN buffer layer and generation of a low resistance layer can be prevented (See [0031]-[0032] of published application).
Therefore, an Al diffusion concentration of 4e15 atoms/cm3 or less on a growth substrate surface would be expected because Yoshida et al teaches forming a SiN layer with overlapping thickness to the SiN layer taught by applicant that is used to obtain the claimed Al diffusion concentration. In the alternative, It would have been obvious to one of ordinary skill in the art at the time of filing to modify Yoshida et al to have a SiN layer within sufficient thickness to obtain the claimed Al diffusion concentration of 4e15 atoms/cm3 or less.
Claim(s) 5-12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Yamada et al (US 2015/0332914), in view of Richardson et al (US 6,228,732).
Yamada et al teaches a method for manufacturing a nitride semiconductor substrate in which a nitride semiconductor is formed on a substrate for film formation, the method comprising the steps of: (1) subjecting a substrate for film formation made of single-crystal silicon to heat treatment under a nitrogen containing atmosphere to form a silicon nitride film on the substrate for film formation; (2) growing an AIN film on the silicon nitride film; and (3) growing a GaN film, an AlGaN film, or both on the AlN film ([0007]-[0033]; Fig 1, 3C, 5C, 10A-10B teaches a silicon substrate (111) 10 which reads on a single crystal silicon substrate, heating the substrate and nitriding the silicon substrate with NH3 to form a silicon nitride layer 12 having a thickness of 1 nm or more, which clearly suggests a heat treatment under a nitrogen containing atmosphere to form a silicon nitride film ([0034], [0054], [0068], [0073]); a single crystal aluminum nitride layer 14 disposed on the silicon nitride layer; and a single crystal aluminum gallium nitride layer 16 disposed over the aluminum nitride layer and a single crystal GaN layer 18 disposed over the single crystal aluminum nitride layer).
Yamada et al teaches nitriding in a nitrogen containing atmosphere, such as ammonia. Yamada et al does not teach a nitrogen atmosphere, which applicant defines as 100% nitrogen gas in paragraph [0032] of the published application.
In a method of nitriding a silicon substrate to form SiN, Richardson et al teaches a monocrystalline silicon substrate is heated at a sufficient temperature and for a sufficient time to grow the predetermined thickness of silicon nitride; and for thermal nitridation in a rapid thermal processor, which clearly suggests an RTA furnace, a typical nitridation temperature ranges from between 400°C. to about 1200°C, and a typical nitridation time ranges from about 5 seconds to about 120 seconds, and the preferred nitrogen-containing gases for thermal nitridation include nitrogen (N2), ammonia (NH3), a mixture of nitrogen and ammonia, and a mixture of nitrogen and hydrogen (N2/H2) (col 7, ln 65 to col 8, ln 45). Richardson et al teaches forming a silicon nitride layer having a thickness of 1 to 3 nanometers (claim 7). Richardson et al teaches overlapping ranges for the temperature and time. Overlapping ranges are prima facie obvious (MPEP 2144.05).
It would have been obvious to one of ordinary skill in the art at the time of filing to modify Yamada et al nitriding process using nitrogen (N2) gas by using the rapid thermal processor and conditions taught by Richardson et al to form a SiN rapidly thereby reducing processing time, and because the selection of a known material based on its suitability for its intended purpose is prima facie obvious (MPEP 2144.07) and substituting equivalents known for the same purpose is prima facie obvious (MPEP 2144.06 II).
Referring to claim 6, the combination of Yamada et al and Richardson et al teaches overlapping temperatures and times to produce silicon nitride of a desired thickness (Richardson col 8, ln 1-25). Overlapping ranges are prima facie obvious (MPEP 2144.05).
Referring to claim 7-8, the combination of Yamada et al and Richardson et al does not explicitly teach the silicon nitride is a single crystal. However, the combination of Yamada et al and Richardson et al teaches a similar method of making the silicon nitride using the same temperature and time (See claim 6); therefore, a similar method would be expected to produce a similar result. Also, the combination of Yamada et al and Richardson et al teaches forming a single crystal aluminum nitride on the silicon nitride layer (Yamada [0080]); therefore, the silicon nitride layer would be expected to be a single crystal to be suitable to form a single crystal AlN, thereon.
Referring to claim 9-12, The combination of Yamada et al and Richardson et al teaches all of the limitations of claim 9, as discussed above, except the combination of Yamada et al and Richardson et al does not explicitly teach an Al diffusion concentration of 4e15 atoms/cm3 or less on a growth substrate surface. Yamada et al teaches a 1 to 10 nm thick SiN layer ([0047]), and examples of 3 to 4 nm thick SiN ([0086]-[0090]). Applicant teaches a silicon nitride film with a thickness preferably 1 to 4 nm, particularly about 2 nm; and when the silicon nitride film is formed, the diffusion of Al to the surface of a high resistance single-crystal silicon growth substrate from the AlN buffer layer and generation of a low resistance layer can be prevented (See [0031]-[0032] of published application). Therefore, an Al diffusion concentration of 4e15 atoms/cm3 or less on a growth substrate surface would be expected because the combination of Yamada et al and Richardson et al teaches forming a SiN layer with overlapping thickness to the SiN layer taught by applicant that is used to obtain the claimed Al diffusion concentration.
Conclusion
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MATTHEW J. SONG
Examiner
Art Unit 1714
/MATTHEW J SONG/ Primary Examiner, Art Unit 1714