Detailed Action
This office action is in response to the amendment filed on June 26th, 2026. Claims 25-26, 37, and 58 are pending.
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 .
Response to Arguments
Applicant's arguments filed June 26th, 2026, have been fully considered but they are not persuasive.
Applicant argues (pg. 3, “Remarks”) that Sasaki indicates p-type doping of Ga2O3 increases resistance. A person of ordinary skill in the art would not reasonably believe that increasing resistance in a semiconductor material would allow them to form a semiconductor device with “excellent performance”. Additionally, Sasaki describes that “Ga2O3-based MESFETs have excellent performance since a high-quality β-Ga2O3 single crystal film is used as a channel layer”. However, this rejection is not that it would be obvious to make a MESFET; rather, the rejection is that it would be obvious to replace the SnO of Varley-1 with Ga2O3. Sasaki does not teach that all semiconductor devices formed from Ga2O3 have excellent performance. Accordingly, Sasaki fails to provide the requisite motivation underpinning this rejection alleged in the office action.
The device formed by Sasaki functions as a normally-off transistor ([0085]). This functionality is only possible when the resistance is sufficiently high to inhibit the flow of current. A person of ordinary skill in the art would recognize that a device with such a feature would allow them to form a device with “excellent performance”. Additionally, Varley-1 does not restrict which devices the metal oxide can be applied to. While Sasaki specifically discusses MISFET performance, the p-type, hydrogen doped, Ga2O3 channel provides this benefit. Therefore, a person of ordinary skill in the art would recognize that the replacement of material provides a clear benefit and would incentivize formation of one material over the other.
Therefore, applicant’s arguments are not persuasive.
Applicant argues (pgs. 3-4, “Remarks”) that a person of ordinary skill in the art would not reasonably assume that simply because SnO can be doped p-type with hydrogen atoms, other oxide materials can similarly be doped p-type with hydrogen atoms. There’s a notable difference in this regard between even SnO2 and SnO, as Varley-1 explains. Sasaki does not seriously contribute to this expectation, since Sasaki merely lists hydrogen as one of 25 possible p-type dopants. Sasaki does not describe aspects of the Ga2O3 band structure which would allow a person of ordinary skill in the art to determine, based on Varley-1’s description, that it should allow for p-type doping with hydrogen atoms.
While the examiner agrees that Varley-1 describes differences between SnO2 and SnO, there is no discussion of Ga2O3 that would teach away from being doped with hydrogen. Sasaki lists a finite number of dopants that predictably dope materials with a p-type conductivity. A person of ordinary skill in the art would be capable of choosing hydrogen from the list of materials and forming a p-type, hydrogen doped Ga2O3 layer as described by Sasaki. See MPEP § 2144.07 and In re Leshin, 277 F.2d 197, 125 USPQ 416 (CCPA 1960). Additionally, Sasaki is not required to describe Ga2O3 band structure as this is not recited in the claims and is inherent to β-Ga2O3 as a material and are well known.
Therefore, applicant’s arguments are not persuasive.
Applicant argues (pg. 4, “Remarks”) that while applicant recognizes that the present claims are limited to p-type doping, the ability of Ga2O3 to be doped either p-type or n-type with hydrogen atoms as described in the present application is an unexpected result as evidenced at least by Varley-1’s disclosure that other semiconductors do not have the band structure conducive to ambipolar doping. This is an unexpected result which evidences the non-obviousness of the present claims.
The claim does not require Ga2O3 to be doped both p-type and n-type with hydrogen, it only requires Ga2O3 to be doped p-type with hydrogen. As rejected by Varley-1 and Sasaki below, p-type, hydrogen doped Ga2O3 does not appear to be an unexpected result. While the preamble suggests bipolar doping, the claim does not describe or limit it as suggested by the applicant. The claim does not require the n-type doping with hydrogen atoms or the band structures that may lend to unexpected results.
Therefore, applicant’s arguments are not persuasive.
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.
Rejection Note: Italicized claim limitations indicate that the corresponding limitations are addressed with a secondary reference/embodiment in an obviousness analysis.
Claims 25 and 58 are rejected under 35 U.S.C. 103 as being unpatentable over Varley et al. (Varley et al. “Ambipolar doping in SnO”, Applied Physics Letters, 2013, Volume 103, pages 1-5; hereinafter Varley-1) in view of Sasaki et al. (2014/0217469 A1; hereinafter Sasaki).
Regarding Claim 25, Varley-1 teaches a method of bipolar doping (Pg. 1, Col. 1, Para. 1, ambipolar doping of SnO), the method comprising: partially filling cation vacancies (Pg. 1, Col. 2, Para. 1, Sn vacancies) in an oxide semiconductor material (SnO) with hydrogen, thereby lowering their acceptor states to act as shallow acceptors (Pg. 1, Col. 2, Para. 1, formation energy is lowered and Sn vacancies act as shallow acceptors), so as to dope the oxide semiconductor material p-type (Pg. 1, Col. 2, Para. 1, forms p-type conductivity), wherein the oxide semiconductor material comprises undoped Ga2O3.
Varley-1 doesn’t teach wherein the oxide semiconductor material comprises undoped Ga2O3.
However, Sasaki (fig. 1) teaches doping an oxide semiconductor ([0084], Ga2O3) material with hydrogen ([0084], H), so as to dope the oxide semiconductor material p-type ([0084]), wherein the oxide semiconductor material comprises undoped Ga2O3 ([0079], Ga2O3 is originally undoped, [0081], Ga2O3 is then doped p-type). Sasaki also teaches that devices formed from Ga2O3 have excellent performance ([0086]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to replace the SnO film of Varley-1 with the Ga2O3 film of Sasaki to form semiconductor devices with excellent performance.
Regarding Claim 58, Varley-1 teaches the method of claim 25, wherein the cation vacancies (Sn vacancies) are partially filled such that the cation vacancies (Sn vacancies) maintain a negative charge (Pg. 3, Col. 1, Para. 4-5; Sn vacancy filled with hydrogen is still negatively charged).
Claim 26 is rejected under 35 U.S.C. 103 as being unpatentable over Varley-1 and Sasaki, as applied to Claim 25 above, and further in view of Nomura (U.S. 2016/0133751 A1; hereinafter Nomura).
Regarding Claim 26, Varley-1 doesn’t teach placing the oxide semiconductor material in a sealed system; evacuating air from the sealed system; introducing hydrogen gas into the sealed system; and annealing the oxide semiconductor material in the sealed system at an elevated temperature for a period of time to allow the hydrogen gas to diffuse into the oxide semiconductor material and thereby dope the oxide semiconductor material p-type. Varley-1 does teach that hydrogen that leads to p-type doping is often incorporated in growth and processing environments (Pg. 1, Col. 2, Para. 1).
However, Nomura (see fig. 5), in a similar method for doping an oxide semiconductor, teaches placing the oxide semiconductor material ([0072], [0089], SnO for example) in a sealed system ([0087], processing chamber); evacuating air from the sealed system ([0097], hydrogen annealing contains no air); introducing hydrogen gas into the sealed system ([0090], H2 process gas); and annealing the oxide semiconductor material in the sealed system at an elevated temperature for a period of time ([0090], annealing temperature) to allow the hydrogen gas to diffuse into the oxide semiconductor material and thereby dope the oxide semiconductor material p-type ([0090], hydrogen diffuses into the oxide semiconductor). Nomura also teaches that p-type oxide semiconductors formed by this method provide significantly improved TFT characteristics ([0066]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine the method for doping an oxide semiconductor p-type of Varley-1 to include the growth and processing environment and steps of Nomura to provide a p-type oxide semiconductor with improved TFT characteristics.
Claim 37 is rejected under 35 U.S.C. 103 as being unpatentable over Varley-1, Sasaki, and Nomura as applied to Claim 26 above, and further in view of Ritter et al. (Jacob R. Ritter, Jesse Huso, Peter T. Dickens, Joel B. Varley, Kelvin G. Lynn, Matthew D. McCluskey; Compensation and hydrogen passivation of magnesium acceptors in β-Ga2O3. Appl. Phys. Lett. 30 July 2018; 113 (5): 052101.; hereinafter Ritter).
Regarding Claim 37, Nomura does not teach the method of claim 26, wherein the elevated temperature is about 950 °C, the period of time is about 2 hours, and the sealed system is at a pressure of about 580 torr during the annealing. Nomura teaches the extent of hydrogenation may be controlled by parameters including anneal time, temperature, and H2 concentration ([0090]).
However, Ritter, teaches the elevated temperature is about 950 °C (Pg. 1, Col. 2, Para. 3; 820 C), the period of time is about 2 hours (Pg. 1, Col. 2, Para. 3; 2 hours), and the sealed system is at a pressure of about 580 torr during the annealing (Pg. 1, Col. 2, Para. 3; ½ atm) while still yielding the predictable result of diffusing hydrogen into a metal oxide. These processing conditions would have been obvious to one of ordinary skill in the art to be optimizable through routine experimentation, since the temperature, time, and pressure are result-effective variables, that is, a variable which achieves a recognized result, as stated in MPEP § 2144.05. In this case, these processing conditions will determine the extent of the hydrogenation of the Ga2O3. It has been well established that the optimum or workable ranges of a result-effective variable can be characterized as routine experimentation.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to use the processing conditions of Ritter because generally, differences in temperature, time, and pressure will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Wei et al. (“interaction between hydrogen and gallium vacancies in Beta-Ga2O3”, see IDS filed February 14th, 2024). Wei teaches hydrogen doping of Ga2O3 and the effects of hydrogen bound to gallium vacancies.
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/A.H./Examiner, Art Unit 2817 /NICHOLAS J TOBERGTE/Primary Examiner, Art Unit 2817
