DETAILED ACTION
General Remarks
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
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 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.
When responding to this office action, applicants are advised to provide the examiner with line numbers and page numbers in the application and/or references cited to assist the examiner in locating appropriate paragraphs.
Per MPEP 2111 and 2111.01, the claims are given their broadest reasonable interpretation and the words of the claims are given their plain meaning consistent with the specification without importing claim limitations from the specification.
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Status of claim(s) to be treated in this office action:
Independent: 1 and 12.
Pending: 1-18.
Response to Arguments
Applicant's arguments with respect to claim(s) 12-18 have been considered but are moot in view of the new ground(s) of rejection. In light of Applicant's amendment and amended drawing, the object to specification’s title and drawing objection has been withdrawn.
Claim Rejections - 35 USC § 103
The following is a quotation of AIA 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 of this title, 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) 12-18 is/are rejected under AIA 35 U.S.C. 103 as being unpatentable over Blank et al., US Patent 8558308 B1; in view of Cheng et al., US PG pub. 20130240984 A1.
Re: Independent Claim 12, Blank discloses an epitaxial layer (100, fig. 2b) having a source polysilicon (160, fig. 2b) rib which extends perpendicularly to a plane of the epitaxial layer (100, fig. 2b), and comprises bars of gate polysilicon (150, fig. 2b) provided on either side of an upper end of the source polysilicon (160, fig. 2b) rib, an insulator (170, fig. 2b) deposited between the gate polysilicon (150, fig. 2b) and the source polysilicon (160, fig. 2b), and an insulator (170, fig. 2b) between gate polysilicon (150, fig. 2b) and the epitaxial layer (100, fig. 2b) is thermally grown (column 9, lines 10-14).
Blank is silent regarding: wherein each bar of gate polysilicon (150, fig. 2b) includes a step in its bottom surface, and wherein the gate polysilicon (150, fig. 2b) is stepping downwards in the direction of the source polysilicon (160, fig. 2b).
Cheng discloses wherein each bar of gate polysilicon (144a, fig. 1a) includes a step in its bottom surface, and wherein the gate polysilicon (144a, fig. 1a) is stepping downwards.
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to include gate polysilicon to have a step downward shape toward the substrate direction since the extended downward gate have an overlapping distance which can improve parasitic capacitance which can also optimize of switching speed.
Re: Claim 13, Blank disclose(s) all the limitations of claim 12 on which this claim depends. Blank further discloses: wherein each bar of gate polysilicon (150, fig. 2b) has a depth of up to 3 microns (column 5, lines 45-48).
Re: Claim 14, Blank discloses all the limitations of claim 12 on which this claim depends. Blank further discloses: wherein each bar of gate polysilicon (150, fig. 2b) has a depth of at least 0.6 microns (column 5, lines 45-48).
Blank did not disclose the depth of the gate polysilicon has a at least 0.7 microns, however, according to the MPEP, Section 2144.05, a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close. The depth discloses by Blank et al. is so close to those claimed that one skilled in the art would have expected them to have the same properties Titanium Metals Corp. of America v. Banner, 778 F.2d 775, 783, 227 USPQ 773, 779 (Fed. Cir. 1985), See also Warner-Jenkinson Co., Inc. v. Hilton Davis Chemical Co., 520 U.S. 17, 41 USPQ2d 1865 (1997). Hence, overlapping ranges are not required to find a claim prima facie obvious.
Re: Claim 15, Blank disclose(s) all the limitations of claim 12 on which this claim depends. Blank further discloses: silicon dioxide (170, fig. 2b) present between each bar of gate polysilicon (150, fig. 2b) and the epitaxial layer (100, fig. 2b) and has a thickness of 800A or less (column 4, lines 55-60).
Re: Claim 16, Blank discloses all the limitations of claim 13 on which this claim depends. Blank further discloses: wherein each bar of gate polysilicon (150, fig. 2b) has a depth of at least 0.6 microns (column 5, lines 45-48).
Blank did not disclose the depth of the gate polysilicon has a at least 0.7 microns, however, according to the MPEP, Section 2144.05, a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close. The depth discloses by Blank et al. is so close to those claimed that one skilled in the art would have expected them to have the same properties Titanium Metals Corp. of America v. Banner, 778 F.2d 775, 783, 227 USPQ 773, 779 (Fed. Cir. 1985), See also Warner-Jenkinson Co., Inc. v. Hilton Davis Chemical Co., 520 U.S. 17, 41 USPQ2d 1865 (1997). Hence, overlapping ranges are not required to find a claim prima facie obvious.
Re: Claim 17, Blank disclose(s) all the limitations of claim 13 on which this claim depends. Blank further discloses: silicon dioxide (170, fig. 2b) present between each bar of gate polysilicon (150, fig. 2b) and the epitaxial layer (100, fig. 2b) and has a thickness of 800A or less (column 4, lines 55-60).
Re: Claim 18, Blank disclose(s) all the limitations of claim 16 on which this claim depends. Blank further discloses: silicon dioxide (170, fig. 2b) present between each bar of gate polysilicon (150, fig. 2b) and the epitaxial layer (100, fig. 2b) and has a thickness of 800A or less (column 4, lines 55-60).
Allowable Subject Matter
Claims 1-11 are allowed.
Re: Independent Claim 1 (and its dependent claim(s) 2-11), the prior art of record do not disclose or suggest, in combination with all other limitations in the claim: thermally growing an insulating layer on inner walls of the trench; depositing an insulator on the inner walls of the trench; depositing polysilicon in the trench to form a source polysilicon rib; providing trenches on either side of an upper portion of the source polysilicon rib, with inner walls of the trenches being formed by a deposited insulator; providing mask material which extends into the trench; providing photoresist on the epitaxial layer and using photolithography to pattern the photoresist; using the patterned photoresist to selectively etch the insulator, wherein the insulator has a portion that is in contact with the source polysilicon being protected from etching by the mask material; removing the mask material and thereby forming trenches on either side of the source polysilicon, wherein each trench has an inner wall formed by insulator which was protected from etching by the mask material; providing an insulator on the epitaxial layer; and providing a bar of gate polysilicon in each trench.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to TSZ CHIU whose telephone number is 571-272-8656. The examiner can normally be reached on M-F, 9:00AM to 5:00PM (EST).
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/TSZ K CHIU/Examiner, Art Unit 2898 Tsz.Chiu@uspto.gov
/Leonard Chang/Supervisory Patent Examiner, Art Unit 2898
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