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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 12/19/2025 has been entered.
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 1-12 are rejected under 35 U.S.C. 103 as being obvious over US 2020/0219972 A1 to Leendertz et al. (hereinafter “Leendertz” – previously cited reference).
Regarding claim 1, Leendertz discloses a semiconductor device, comprising:
a trench gate structure in a silicon carbide (SiC) semiconductor body (trench gate structure 150 in SiC body 100; Fig. 4C; paragraph [0080]);
a source region of a first conductivity type that adjoins the trench gate structure in a first segment (n-type source region 110 adjoining trench gate structure 150 in a first left side portion of body 100; Fig. 4C; paragraphs [0078]-[0080]);
a semiconductor region of a second conductivity type, wherein the semiconductor region comprises a first sub-region arranged below the source region in the first segment, and a second sub-region arranged in a second segment that adjoins the first segment (p-type region having body region 120 below source region 110 and adjoining shield portion 172 in second right side portion of body 100 adjacent first left side portion; Fig. 4C; paragraphs [0080]-[0081]); and
a current spread region of the first conductivity type (n-type current spread region 137; Fig. 4C; paragraph [0082]), wherein the current spread region comprises a first sub-region that adjoins the trench gate structure in the first segment at a vertical distance to a first surface of the SiC semiconductor body (first portion of current spread region 137 adjoining trench gate structure 150 and surface of SiC body 100; Fig. 4C), and a second sub-region that is spaced from the trench gate structure in the second segment at the vertical distance to the first surface by a lateral distance (second portion of current spread region 137 spaced apart from trench gate structure 150 in an adjacent iteration of the design pattern; Fig. 4C), wherein the semiconductor region (i) is continuous through the first segment and the second segment along an axis that extends perpendicular to a lateral direction along which the trench gate structure is stripe-shaped (p-type region continuous through first left side and second right side portions of body 100 along an axis that extends perpendicular to a lateral direction along which a trench gate structure 150 is stripe-shaped; Figs. 4C & 4D), (ii) extends, in the first segment, between the source region and the first sub-region of the current spread region (p-type region having a part in the first left side portion of body 100 between source region 110 and first portion of current spread region 137 adjoining trench gate structure 150; Fig. 4C), and (iii) extends, in the second segment, between the trench gate structure and the second sub-region of the current spread region that is spaced from the trench gate structure in the second segment (p-type region having a part in the second right side portion of body 100 between trench gate structure 150 and second portion of current spread region 137 spaced apart from trench gate structure 150; Fig. 4C).
Leendertz fails to disclose wherein the semiconductor region (i) is continuous through the first segment and the second segment along an axis that extends in parallel to a lateral direction along which the trench gate structure is stripe-shaped.
However, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have modified Leendertz in this manner given that power device active areas are typically much larger than the cell pitch in both directions, making the layout effectively symmetric on a macro scale and so parallel and perpendicular orientations would yield similar electrical performance.
Regarding claim 2, Leendertz discloses the semiconductor device of claim 1, wherein: a doping concentration profile defining the current spread region changes, along a first lateral direction, from a first doping concentration level in the first segment to a second doping concentration level in the second segment; and at least a part of the trench gate structure extends along the first lateral direction (first portion of n-type current spread region 137 may have different doping concentration profile than second portion of n-type current spread region 137 in a lateral direction along which trench gate structure 150 may extend; Fig. 4C; paragraphs [0030]-[0031]).
Regarding claim 3, Leendertz discloses the semiconductor device of claim 1, comprising: a pn junction between the semiconductor region and the current spread region (pn junction formed between the p-type body region 120 and n-type current spread region 137; Fig. 4C), wherein: a vertical distance from the pn junction to the first surface changes, along a first lateral direction, from a first vertical distance in the first segment to a second vertical distance in the second segment; and at least a part of the trench gate structure extends along the first lateral direction (vertical distance between pn junction and surface of SiC body 100 changes along a lateral direction between first and second portion of current spread region 137 along which trench gate structure 150 may extend; Fig 4C).
Regarding claim 4, Leendertz discloses the semiconductor device of claim 1, wherein a vertical concentration profile of dopants defining the first sub-region of the semiconductor region is different from a vertical concentration profile of dopants defining the second sub-region of the semiconductor region (body region 120 has different doping concentration relative shield portion 172; paragraph [0081]).
Regarding claim 5, Leendertz discloses the semiconductor device of claim 1, wherein a doping concentration profile defining the current spread region alternates, along the first lateral direction, between a first doping concentration level and a second doping concentration level (current spread region 137 alternates between n doping and n- doping along the lateral direction; Fig. 11B), wherein first sub-regions and second sub-regions of the current spread region are arranged in a repeating alternating pattern along the first lateral direction, each first sub-region being doped to the first doping concentration level and each second sub-region being doped to the second doping concentration level (first and second portion of region 137 arranged in iterative fashion where each first portion of region 137 has an n doped portion and each second portion of region 137 has an n- doped portion; Figs. 4C and 11B).
Regarding claim 6, Leendertz discloses the semiconductor device of claim 1, comprising: a pn junction between the semiconductor region and the current spread region (pn junction formed between the p-type body region 120 and n-type current spread region 137; Fig. 4C), wherein a vertical distance from the pn junction to the first surface varies within the second segment (vertical distance between pn junction and surface of SiC body 100 changes along a lateral direction within second portion of current spread region 137; Fig 4C).
Regarding claim 7, Leendertz discloses a semiconductor device, comprising:
a trench gate structure in a silicon carbide (SiC) semiconductor body, wherein at least a part of the trench gate structure extends along a first lateral direction (trench gate structure 150 extending along lateral direction in SiC body 100; Fig. 4C; paragraph [0080]);
a source region of a first conductivity type that adjoins the trench gate structure in a first segment (n-type source region 110 adjoining trench gate structure 150 in a first portion; Fig. 4C; paragraphs [0078]-[0080]);
a semiconductor region of a second conductivity type, wherein the semiconductor region comprises a first sub-region arranged below the source region in the first segment, and a second sub-region arranged in a second segment that adjoins the first segment (p-type region having body region 120 below source region 110 and adjoining shield portion 172; Fig. 4C; paragraphs [0080]-[0081]); and
a current spread region of the first conductivity type (n-type current spread region 137; Fig. 4C; paragraph [0082]), wherein a doping concentration profile defining the current spread region changes, along the first lateral direction, from a first doping concentration level in the first segment to a second doping concentration level in the second segment (first portion of n-type current spread region 137 may have different doping concentration profile than second portion of n-type current spread region 137 in a lateral direction; Fig. 4C; paragraphs [0030]-[0031]), wherein the semiconductor region (i) is continuous through the first segment and the second segment along an axis that extends perpendicular to a lateral direction along which the trench gate structure is stripe-shaped (p-type region continuous through first left side and second right side portions of body 100 along an axis that extends perpendicular to a lateral direction along which a trench gate structure 150 is stripe-shaped; Figs. 4C & 4D), (ii) extends, in the first segment, between the source region and the current spread region (p-type region having a part in the first portion of body 100 between source region 110 and first portion of current spread region 137 adjoining trench gate structure 150; Fig. 4C), and (iii) extends, in the second segment, between the trench gate structure and the current spread region (p-type region having a part in the second portion of body 100 between trench gate structure 150 and second portion of current spread region 137; Fig. 4C).
Leendertz fails to disclose wherein the semiconductor region (i) is continuous through the first segment and the second segment along an axis that extends in parallel to a lateral direction along which the trench gate structure is stripe-shaped.
However, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to have modified Leendertz in this manner given that power device active areas are typically much larger than the cell pitch in both directions, making the layout effectively symmetric on a macro scale and so parallel and perpendicular orientations would yield similar electrical performance.
Regarding claim 8, Leendertz discloses the semiconductor device of claim 7, wherein the second sub-region of the semiconductor region is arranged between the current spread region and the trench gate structure (shield portion 172 arranged between current spread region 137 and trench gate structure 150; Fig. 4C).
Regarding claim 9, Leendertz discloses the semiconductor device of claim 7, comprising: a pn junction between the semiconductor region and the current spread region (pn junction formed between the p-type body region 120 and n-type current spread region 137; Fig. 4C), wherein a vertical distance from the pn junction to a first surface of the SiC semiconductor body changes, along the first lateral direction, from a first vertical distance in the first segment to a second vertical distance in the second segment (vertical distance between pn junction and surface of SiC body 100 changes along a lateral direction between first and second portion of current spread region 137; Fig 4C).
Regarding claim 10, Leendertz discloses the semiconductor device of claim 7, wherein a vertical concentration profile of dopants defining the first sub-region of the semiconductor region is different from a vertical concentration profile of dopants defining the second sub-region of the semiconductor region (body region 120 has different doping concentration relative shield portion 172; paragraph [0081]).
Regarding claim 11, Leendertz discloses semiconductor device of claim 7, wherein the doping concentration profile defining the current spread region alternates, along the first lateral direction, between the first doping concentration level and the second doping concentration level (current spread region 137 alternates between n doping and n- doping along the lateral direction; Fig. 11B).
Regarding claim 12, Leendertz discloses the semiconductor device of claim 7, comprising: a pn junction between the semiconductor region and the current spread region (pn junction formed between the p-type body region 120 and n-type current spread region 137; Fig. 4C), wherein a vertical distance from the pn junction to a first surface of the SiC semiconductor body varies within the second segment (vertical distance between pn junction and surface of SiC body 100 changes along a lateral direction within second portion of current spread region 137; Fig 4C).
Response to Arguments
Applicant's arguments filed December 19, 2025 have been fully considered. Applicant amended claims 1 and 7 and provided corresponding arguments. Specifically, Applicant argues that Figs. 4A and 4C of Leendertz illustrates a p-type region continuous through first left side and second right side portions of body 100 along an axis that extends perpendicular to a lateral direction along which a trench gate structure 150 is stripe-shaped. Examiner agrees with this assertion. However, this slight difference in shape between the invention and the disclosure of Leendertz is obvious for the reasons provided above. Further, Applicant asserts that Leendertz discloses a shielding connection portion being between the trench gate structure and the current spread region, but this would appear to read on the second amended limitation in claim 1 that the current spread region is spaced from the trench gate structure. Therefore, while Examiner agrees that amended claims 1 and 7 overcome the 35 USC 102 rejection using Leendertz, the amended claim set has been rejected on new grounds under 35 USC 103 using the same reference.
Conclusion
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/IAN DEGRASSE/Examiner, Art Unit 2818
/JEFF W NATALINI/Supervisory Patent Examiner, Art Unit 2818