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 .
Title
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. Currently, the title has been changed to:
“A SEMICONDUCTOR DEVICE WITH A LOW CONCENTRATION REGION ABOVE THE ANDOE REGION”
DETAILED ACTION
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)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 1, 5, 9 and 14-18 are rejected under 35 U.S.C. 102(a)(2) as being anticipated by Liu et al. (Pub. No. US 2023/0343827 A1, herein Liu).
Regarding claim 1, Liu discloses a semiconductor device comprising a transistor portion IGBT and a diode portion FWD, wherein the semiconductor device including: a plurality of trench portions 218/210 provided on a front surface of a semiconductor substrate; a drift region 205 of a first conductivity type provided in the semiconductor substrate (Liu: Figs. 2, 9, 19 and paragraph [0050]); an anode region 207/307 of a second conductivity type provided above the drift region in the diode portion; a low concentration region 215/315 provided above the anode region and having a doping concentration an absolute value of which is lower than that of the anode region; and a high concentration region 212/312 of the second conductivity type provided above the anode region and having a doping concentration higher than that of the anode region (Liu: Figs. 2, 9, 19 and paragraphs [0050], [0063]).
Regarding claim 5, Liu discloses the semiconductor device according to claim 1, wherein in a depth direction of the semiconductor substrate, the low concentration region is shallower than a peak position of a doping concentration of the anode region (Liu: Figs. 2, 9, 19 and paragraphs [0050], [0063]).
Regarding claim 9, Liu discloses the semiconductor device according to claim 1, wherein in a depth direction of the semiconductor substrate, a peak position of a doping concentration of the anode region is deeper than the high concentration region (Liu: Figs. 2, 9, 19 and paragraphs [0050], [0063]).
Regarding claim 14, Liu discloses the semiconductor device according to claim 1, wherein the high concentration region is discretely provided in a trench extending direction (Liu: Figs. 2, 9, 19 and paragraphs [0050], [0063]).
Regarding claim 15, Liu discloses the semiconductor device according to claim 1, wherein the high concentration region is provided to be spaced apart from the plurality of trench portions (Liu: Figs. 2, 9, 19 and paragraphs [0050], [0063]).
Regarding claim 16, Liu discloses the semiconductor device according to claim 1, comprising a cathode region 202 of a first conductivity type below the low concentration region and the high concentration region, having a doping concentration higher than that of the drift region (Liu: Figs. 2, 9, 19 and paragraphs [0050], [0063]).
Regarding claim 17, Liu discloses the semiconductor device according to claim 1, comprising a trench contact portion 214/314 provided on the front surface of the semiconductor substrate (Liu: Figs. 2, 9, 19 and paragraphs [0050], [0063]).
Regarding claim 18, Liu discloses the semiconductor device according to claim 17, wherein the high concentration region is provided at a lower end of the trench contact portion (Liu: Figs. 2, 9, 19 and paragraphs [0050], [0063]).
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.
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.
Claims 2-4, 7-8 and 10-13 are rejected under 35 U.S.C. 103 as being unpatentable over Liu.
Regarding claims 2-3, 6-7, 11 and 13, Liu, in paragraphs [0010], [0016], [0026], states “the heavily doped first conductivity type emitter region has a doping concentration greater than 1e18 cm−3, and forms an ohmic contact with the emitter electrode. A punch-through voltage of the triode can be changed to 0.3 V to 1 V by adjusting a junction depth and a doping concentration of the lightly doped second conductivity type base region... Further, a doping concentration of the lightly doped second conductivity type base region is much less than that of each of the second conductivity type base region and the floating FP region, but numerically greater than that of the first conductivity type drift region…And then performing ion implantation to form a heavily doped first conductivity type emitter region, wherein a concentration of the lightly doped second conductivity type base region is much less than that of the second conductivity type base region…The concentration of the lightly doped P−-type base region 215 is much less than that of the P-type base region 207. Then, the change in the doping concentrations of the P-type base region 207 and the heavily doped N+-type emitter region 211 is negligible.”
Liu does not specifically state the claimed ranges in claims 2-3, 7, 11 and 13. However, the claimed ranges are recognized as a result-effective variable, i.e., a variable which achieves a recognized result. In an IGBT the lightly doped drift region concentration primarily sets the breakdown voltage and on-state voltage drop, with lower doping increasing blocking capability but raising conduction losses. The highly doped regions (emitter/body) and the anode (collector) doping control carrier injection efficiency and conductivity modulation, thereby reducing on-state resistance but also increasing stored charged and switching losses. Therefore, it would have been an obvious matter of design choice bounded by well-known manufacturing constraints and ascertainable by routine experimentation and optimization to choose the particular claimed concentration ranges because applicant has not disclosed that the limitations are for a particular unobvious purpose, produce an unexpected result, or are otherwise critical, and it appears prima facie that the process would possess utility using another temperature range. The claim(s) is(are) obvious without showing that the claimed range(s) achieve unexpected results relative to the prior art range. See In re Aller, 105 USPQ 233 (CCPA 1955) and In re Woodruff, 16 USPQ2d 1935, 1937 (Fed. Cir. 1990). See also In re Huang, 40 USPQ2d 1685, 1688 (Fed. Cir. 1996) (claimed ranges of a result effective variable, which do not overlap the prior art ranges, are unpatentable unless they produce a new and unexpected result which is different in kind and not merely in degree from the results of the prior art). See also In re Boesch, 205 USPQ 215 (CCPA) (discovery of optimum value of result effective variable in known process is ordinarily within skill of art).
Regarding claim 4, Liu does not specifically show wherein in a top view, the low concentration region is provided to surround the high concentration region on the front surface of the semiconductor substrate. However, a person having ordinary skill in the art would have readily recognized that in a top view layout of the Liu’s RC-IGBT, the low concentration region laterally surrounds the highly doped region to provide uniform current distribution and effective carrier injection.
Regarding claims 8, 10 and 12, Liu, in paragraph [0017], states “the thickness of the gate dielectric layer is smaller than the width of the gate electrode and is about 0.1 μm to 2 μm. And the gate dielectric layer is made of insulating materials such as silicon dioxide and silicon nitride.”
Liu does not specifically state the claimed depth and thickness ranges in claims 8, 10 and 12. However, the claimed ranges are recognized as a result-effective variable, i.e., a variable which achieves a recognized result. The depth and thickness of the highly doped regions and the anode determine the series resistance and carrier injection efficiency, directly impacting the on-state voltage and reverse-conduction characteristics. Thicker or deeper highly doped and anode regions reduce resistance and improve conductivity modulation, but increase stored charge, leading to higher switching losses and slower turn-off behavior. Therefore, it would have been an obvious matter of design choice bounded by well-known manufacturing constraints and ascertainable by routine experimentation and optimization to choose the particular claimed concentration ranges because applicant has not disclosed that the limitations are for a particular unobvious purpose, produce an unexpected result, or are otherwise critical, and it appears prima facie that the process would possess utility using another temperature range. The claim(s) is(are) obvious without showing that the claimed range(s) achieve unexpected results relative to the prior art range. See In re Aller, 105 USPQ 233 (CCPA 1955) and In re Woodruff, 16 USPQ2d 1935, 1937 (Fed. Cir. 1990). See also In re Huang, 40 USPQ2d 1685, 1688 (Fed. Cir. 1996) (claimed ranges of a result effective variable, which do not overlap the prior art ranges, are unpatentable unless they produce a new and unexpected result which is different in kind and not merely in degree from the results of the prior art). See also In re Boesch, 205 USPQ 215 (CCPA) (discovery of optimum value of result effective variable in known process is ordinarily within skill of art).
Allowable Subject Matter
Claims 19-21 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:
With respect to claim 19, the prior art of record alone or in combination do not teach or fairly suggest, in combination with other elements of the claims, wherein the low concentration region is provided at a lower end and a side wall of the trench contact portion. Claim 20 is included likewise as it depends from claim 19.
With respect to claim 21, the prior art of record alone or in combination do not teach or fairly suggest, in combination with other elements of the claims, wherein in a depth direction of the semiconductor substrate, a lower end of the trench contact portion is deeper than a lower end of the low concentration region.
Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee. Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.”
Conclusion
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January 6, 2026
/MALIHEH MALEK/Primary Examiner, Art Unit 2813