DETAILED ACTION
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.
Claim(s) 1, 5, 8, 10, 11, 14 and 17-20 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Hadamek et al. “Epitaxial growth of β-Ga2O3 on SrTiO3 (001) and SrTiO3-buffered Si (001) substrates by plasma-assisted molecular beam epitaxy” (J. Appl. Phys. 131, 14702 (04/8/2022)).
Regarding claims 1, 5, 8 and 10, Hadamek discloses:
A wafer comprising:
a Si substrate;
a buffer layer comprising a thin film of at least one of epitaxial strontium titanate (STO) or magnesium oxide (MgO) formed on the Si substrate; and
a thin film comprising a gallium oxide formed on the buffer layer.
- (see section “II. Experimental” on page 145702-2 (right column) … “The STO buffer layer on Si was grown on a 2-in. Si (001) wafer, and the Ga2O3 film was grown on this pseudo-substrate”)
(claim 5) see page 145702-8 … “hetero-epitaxy of β-Ga2O3 on STO (001)”.
(claim 8) see section “”III. Results”, pages 145702-2 through 145702-3 … discussion of small crystal grain sizes.
(claim 10) see Title and section “Abstract”.
Regarding claims 11, 14, 17 and 18, Hadamek discloses:
A method of forming an epitaxial stack structure, wherein the method comprises comprising:
forming, on a silicon (Si) substrate, a buffer layer comprising at least one of strontium titanate (STO) or magnesium oxide (MgO); and
forming a thin film comprising gallium oxide on the buffer layer.
- (see section “II Experimental” on page 14702-2 (right column) … “The STO buffer layer on Si was grown on a 2-in. Si (001) wafer, and the Ga2O3 film was grown on this pseudo-substrate”)
(claim 14) see page 145702-8 … “hetero-epitaxy of β-Ga2O3 on STO (001)”.
(claim 17) see page 145702-1 … “annealing, leading to grains of β-Ga2O3”.
(claim 18) see Title and section “Abstract”.
Regarding claims 19 and 20, Hadamek discloses:
A power electronics device comprising:
a wafer comprising an epitaxial stack structure, wherein the epitaxial stack structure comprising a silicon (Si)-substrate and a thin film comprising gallium oxide;
means for receiving a first electric current coupled to a first portion of the wafer; and
means for transmitting a second electric current coupled to a second portion of the wafer.
- (see section “II. Experimental” on page 145702-2 (right column) … “The STO buffer layer on Si was grown on a 2-in. Si (001) wafer, and the Ga2O3 film was grown on this pseudo-substrate” and see section “I. Introduction” on page 145702-1 (left column) … Ga2O3 is a highly promising wide-bandgap semiconductor with potential applications in solar-blind ultra-violet (UV) photodetectors, UV-transparent conductive films, UV detectors, high-power electronics, and possibly microwave switching and amplification. Advantages of the material include its ultra-wide bandgap, transparency in the UV, and the availability of relatively low-cost bulk substrates. Because of its large bandgap of ∼5 eV, Ga2O3 has a high theoretical breakdown field of about 8MV/cm.3”).
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 2, 3, 6, 7, 9, 12, 13, 15 and 16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Hadamek et al. “Epitaxial growth of β-Ga2O3 on SrTiO3 (001) and SrTiO3-buffered Si (001) substrates by plasma-assisted molecular beam epitaxy” (J. Appl. Phys. 131, 14702 (04/8/2022)).
Regarding claims 2, 3, 6, 7, 9, 12, 13, 15 and 16, Hadamek discloses:
Discusses various oxide substrates used to grow Ga2O3 … page 145702-1 though 145702-2 …. “We have also recently reported the integration of β-Ga2O3 by plasma-assisted molecular beam epitaxy (MBE) onto a γ-Al2O3 (111) buffer layer; and the use of buffer layers on a silicon substrate as noted in claim 1 above.
As a result. it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to determine the use in which a multi-buffer layer including γ-Al2O3 and STO to grow a Ga2O3 film on silicon, based on Hadamek’s disclosure as a whole since both buffers have been disclosed in previous experimentation for growing a sufficient crystal Ga2O3 film. One skilled in the art would be apt to perform a similar layered structure to at least condition the crystalline Si substrate for growth of the Ga2O3 film using various buffering layer configurations to determine the Ga2O3 film. Even further, such experimentation would be obvious to one skilled in the art to determine a layered structure where γ-Al2O3 and Ga2O3 layers would be further grown to determine the required characteristics desired for the final Ga2O4 film above.
Claims 4 is/are rejected under 35 U.S.C. 103 as being unpatentable over Hadamek , as applied to claim 2 above, in view of Kaneko et al. US 2015/0194479 A1.
Regarding claim 4, Hadamek does not disclose:
wherein the aluminum oxide comprises an aluminum-gallium alloy oxide.
Kaneko discloses a publication from a similar field of endeavor in which:
wherein the aluminum oxide comprises an aluminum-gallium alloy oxide (paras 0009 and 0013 where aluminum oxide and an aluminum-gallium alloy oxide are interchangeable based on the impurity doping desired i.e. Alx1Gay1O3 where 0<=x1<=2, 0<=y1<=2, and x1+y1=1.5 to 2.5).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to determine the aluminum oxide of Hadamek as an aluminum-gallium alloy oxide of Kaneko to further refine the lattice constant of the buffer layer within Hadamek’s s wafer structure to determined the desired resulting Ga2O3 film.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ERROL V FERNANDES whose telephone number is (571)270-7433. The examiner can normally be reached on 9-5:30.
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/ERROL V FERNANDES/Primary Examiner, AU 2893
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