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 .
Election/Restrictions
Applicant’s election without traverse of Invention I in the reply filed on 5/19/2026 is acknowledged.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claim 26 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 26 further recites the limitation "the first body conductivity type" in line 1 of the claim. There is insufficient antecedent basis for this limitation in the claim. Further, it is unclear whether it is intended to refer to “the first conductivity type” recited in claim 21, or refer to a conductivity type for “the first body region” or “the first body contact region” recited in claim 21. For purposes of examination on the merits, it will be understood to refer to “the first conductivity type”.
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.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-10, and 17-20 are rejected under 35 U.S.C. 103 as being unpatentable over US patent publications US 20210399089 A1 (Saggio et al hereinafter Saggio) in view of US 20150270354 A1 (Shimizu et al hereinafter Shimizu).
Regarding claim 1, Saggio discloses a MOSFET device of a vertical conduction type (the device of FIG. 2 ¶ [0021]) comprising: a substrate (FIG. 2, semiconductor body 102 is an SiC substrate ¶ [0028]) of silicon carbide having a first conductivity type (N type ¶ [0028]) and a main face (FIG. 2, top surface 102a ¶ [0027]); a body region (FIG. 2, a body region 105 ¶ [0030]) of a second conductivity type (P type ¶ [0029]) extending into the substrate from the main face (FIG. 2, body regions 105 extend into semiconductor body 102 through top surface 102a), the body region having a first depth (FIG. 2, body regions 105 extend into semiconductor body 102 to a depth) along a first direction (a vertical direction in the context of the view of FIG. 2); a first and a second source region (FIG. 2, a person of ordinary skill in the art can observe that a pair of N+ type source regions 108 may be located at left and right sides of interfaces 114 ¶ [0030]; furthermore, a person of ordinary skill in the art before the effective filing date of the claimed invention would have found it obvious to have each interface 114 having a source region 108 at each of its left and right sides, because even though FIG. 2 does not explicitly illustrate that, it is stated that the structure of FIG. 2 may be replicated ¶ [0025], and the non-illustrated portions of interfaces 114 having source regions 108 at both left and right sides would be obvious to include to increase the device’s functionality) of the first conductivity type extending inside the body region from the main face parallel to each other (FIG. 2 show a lateral cross-section, and it is repeated in a manner such that source regions 108 run parallel to each other ¶ [0024-0026]), the first and second source regions each having a second depth (FIG. 2, source regions 108 extend less far into semiconductor body 102 along the illustrated vertical direction than body region 105 extends ¶ [0031]) along the first direction smaller than the first depth and being mutually spaced by a distance in a second direction (FIG. 2, source regions 108 are spaced apart along a horizontal X direction with interface 114 between them) perpendicular to the first direction, the first and second source regions extending in an extension direction locally perpendicular to the first and the second directions (FIG. 2, being a lateral cross-section, implies that source regions extend along an inward/outward direction ¶ [0024-0026]);
and a body contact region (FIG. 2, P+ type electrical-contact interface 114 extends through surface 102a into semiconductor body 102 between a pair of source regions 108 ¶ [0035]]) of the second conductivity type extending inside the body region between the first and the second source regions, the body contact region having a third depth (FIG. 2, interface 114 has a depth further down along the vertical direction than source regions 108) along the first direction greater than or equal to the second depth, wherein the body contact region has a width in the second direction (FIG. 2, interface 114 extends some distance along the horizontal X direction).
Saggio does not explicitly disclose a length in the extension direction greater than the width, as the extents to which the body contact regions length and width respectively extend is not explicitly stated or illustrated in the disclosure of Saggio, such a comparison not being an element of particular importance to the disclosure of their invention.
However, Shimizu discloses a MOSFET device of a vertical conduction type (the device of FIGS. 20 and 21B ¶ [0206-0209]) which comprises a P+ type body contact region (FIG. 20, p-well contact region 40 ¶ [0207]) which includes a width along a horizontal second direction (FIG. 20, widths of illustrated contact regions 20) and a length (FIG. 20B, a lengthwise vertical direction of metal p-well contact region 41, which is stated to correspond to p-well contact region 40 ¶ [0209]) along an extension direction (a vertical direction as illustrated in the orientation of FIG. 21B), and the length in the extension direction is greater than the width. Shimizu also teaches that the body contact region can be adjusted to form an ohmic contact between the source electrode and the p-well contact region (¶ [0150]).
Saggio and Shimizu both pertain to the field of MOSFET devices of a vertical conduction type, placing them in the same field of endeavor as the claimed invention. Therefore, a person of ordinary skill in the art before the effective filing date of the claimed invention would have found it obvious to modify the device of Saggio in view of Shimizu to include a length in the extension direction greater than the width, in order to dispose the body contact region of Saggio throughout the device to form an ohmic contact of the source electrode to other elements of the transistor as is demonstrated by Shimizu.
Regarding claim 2, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, but do not explicitly teach that the length of the body region is at least one hundred times the width of the body region, though based on the view given by Shimizu FIG. 21B the disparity is ostensibly quite large. However, a person of ordinary skill in the art before the effective filing date of the claimed invention would recognize that the relative length and width of the body region affects the density in which the stripe-pattern configuration of the device can be implemented, such relation therefore is a result-effective variable.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to vary, through routine optimization, the relation of the body region’s length to its width since it has been identified as a result-effective variable. Further, one of ordinary skill in the art would have had a reasonable expectation of success to arrive at a configuration wherein the length of the body region is at least one hundred times the width of the body region, in order to fine-tune the device-density according to desired properties. See also MPEP 2144.05.
Furthermore, the applicant has not presented persuasive evidence that the claimed relationship is for a particular purpose that is critical to the overall claimed invention (i.e., that the invention would not work without the specific claimed dimensions).
Regarding claim 3, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, and they further disclose that the body contact region extends continuously along the extension direction (Shimizu FIG. 21B, p-well contact region 40, which corresponds to metal p-well contact region 41, extends continuously along the extension direction, which in the orientation of Shimizu FIG. 21B, is the vertical direction).
Regarding claim 4, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, and they further disclose that the body contact region extends throughout a length of the source regions (Saggio FIG. 2, interface 114 extends between source regions 108 throughout the device; this is further illustrated in view of Shimizu FIG. 21B with the extension of p-well 40/41).
Regarding claim 5, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, and they further disclose that the body contact region is a single body contact region (Shimizu FIG. 21B, a given instance of p-well 40/41 is a continuous, single body contact region).
Regarding claim 6, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, and they further disclose that the width of the body contact region, in the second direction, is equal to the distance between the source regions (Saggio FIG. 2, a person of ordinary skill in the art would observe that interface 114 may separate two instances of source region 108 such that its width is equal to the separation distance between the two source regions 108, as an interface 114 directly borders a source region 108 on its left, and an interface 114 directly borders a source region 108 on its right).
Regarding claim 7, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, and they further disclose that the body contact region is contiguous to the source regions (Saggio FIG. 2, interface 114 is contiguous with source regions 108).
Regarding claim 8, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, and they further disclose that the body region has a first doping level (Saggio FIG. 2, body region 105 has a p-dopant level indicated as “P” ¶ [0029]) and the body contact region has a second doping level (Saggio FIG. 2, interface 114 has a p-dopant level indicated as “P+” ¶ [0035]), higher than the first doping level (a person of ordinary skill in the art would deduce that a “P+” dopant level is higher than a “P” dopant level).
Regarding claim 9, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, and they further disclose that the extension direction is a rectilinear longitudinal direction and the first, second and third directions are Cartesian axes (Saggio FIG. 2, the XYZ axis designates three mutually-orthogonal Cartesian axes which correspond to the claimed first, second, and third directions, and the extension direction is a rectilinear longitudinal direction; see also Shimizu FIGS. 20 and 21B).
Regarding claim 10, Saggio in view of Shimizu discloses the limitations of claim 1 as detailed above, and they further disclose that the first conductivity type is N (N type conductivity is used for semiconductor body 102 ¶ [0028]) and the second conductivity type is P (P type conductivity is used for body region 105 ¶ [0029]).
Regarding claim 17, Saggio discloses a MOSFET device of a vertical conduction type (the device of FIG. 2 ¶ [0021]), comprising: a substrate (FIG. 2, semiconductor body 102 is an SiC substrate ¶ [0028]) of silicon carbide having a first conductivity type (N type ¶ [0028]); a body region (FIG. 2, a body region 105 ¶ [0030]) of a second conductivity type (P type ¶ [0029]) extending into the substrate from a top surface (FIG. 2, top surface 102a is where body region 105 extends from ¶ [0027]) of the substrate; a first source region (FIG. 2, N+ type source region 108 located at left side of right interface 114 extends into semiconductor body 102 through surface 102a ¶ [0030]) of the first conductivity type extending into the body region from the top surface of the substrate; a second source region (a person of ordinary skill in the art before the effective filing date of the claimed invention would have found it obvious to have each interface 114 having a source region 108 at each of its left and right sides, because while FIG. 2 does not explicitly illustrate that, it is stated that the structure of FIG. 2 may be replicated ¶ [0025], and the non-illustrated portions of interfaces 114 having source regions 108 at both left and right sides would be obvious to include to increase the device’s functionality; the right N+ type source region 108 located at right side of right interface 114 extends into semiconductor body 102 through surface 102a ¶ [0030]) of the first conductivity type extending into the body region from the top surface of the substrate; and a body contact region (FIG. 2, right electrical contact interface 114 is a P+ type body contact region ¶ [0035]) of the second conductivity type positioned in the body region between the first source region and the second source region (in view of the obvious modification replicating the structure of FIG. 2, right electrical contact interface 114 is between a source region 108 at each of its sides) and extending downward from the top surface of the substrate (FIG. 2, interface 114 extends downward from top surface 102a).
Saggio does not explicitly disclose that the first source region, the second source region, and the body contact region extend as parallel stripes along the top surface of the substrate, though Saggio does indicate that body region 105, in which those elements are included, may extend in a stripe pattern (the embodiments of FIGS. 4A-4D indicate such a stripe pattern for body region 105 ¶ [0054-0059]).
Further, Shimizu discloses a MOSFET device of a vertical conduction type (the device of FIGS. 20 and 21B ¶ [0206-0209]) which comprises a P+ type body contact region (FIG. 20, p-well contact region 40 ¶ [0207]) and a pair of N+ type source regions (FIG. 20, source regions 38 ¶ [0144]) at left and right sides of the body contact regions, and extend (FIG. 20B, a lengthwise vertical direction of metal p-well contact region 41, which is stated to correspond to p-well contact region 40 ¶ [0209]) along an extension direction (a vertical direction as illustrated in the orientation of FIG. 21B) in parallel stripe patterns. To maintain contact in a manner consistent with the lateral cross-section shown in FIG. 20, a person of ordinary skill in the art before the effective filing date of the claimed invention would have found it obvious to have the body contact region extend as parallel stripes along the top surface of the substrate, to provide the stripe structure indicated in Shimizu FIGS. 20 and 21B and maintain electrical contact between the source electrode and other transistor elements, consistent with the depiction of Saggio’s body region 105 in Saggio FIGS. 4A-4D.
Saggio and Shimizu both pertain to the field of MOSFET devices of a vertical conduction type, placing them in the same field of endeavor as the claimed invention. Therefore, a person of ordinary skill in the art before the effective filing date of the claimed invention would have found it obvious to modify the device of Saggio in view of Shimizu to have the first source region, the second source region, and the body contact region extend as parallel stripes along the top surface of the substrate, in order to provide a stripe structure consistent with the depiction of Saggio’s body region 105 in Saggio FIGS. 4A-4D where electrical contact is maintained between the source electrode and other transistor elements, as indicated in in Shimizu FIGS. 20 and 21B.
Regarding claim 18, Saggio in view of Shimizu discloses the limitations of claim 17 as detailed above, and they further disclose that the body contact region abuts the first source region and the second source region (Saggio FIG. 2, in view of the obvious modification replicating the structure of FIG. 2, electrical contact interface 114 is between a source region 108 at each of its sides and directly contacts/abuts each of the two source regions 108).
Regarding claim 19, Saggio in view of Shimizu discloses the limitations of claim 17 as detailed above, and they further disclose that the body contact region is wider than the first source region and the second source region (Saggio FIG. 2, it can be observed that interface 114 is wider than either of source regions 108; MPEP 2125 I states that “Drawings and pictures can anticipate claims if they clearly show the structure which is claimed…. When the reference is a utility patent, it does not matter that the feature shown is unintended or unexplained in the specification. The drawings must be evaluated for what they reasonably disclose and suggest to one of ordinary skill in the art.”).
Regarding claim 20, Saggio in view of Shimizu discloses the limitations of claim 17 as detailed above, and they further disclose that the body region has a first doping level (Saggio FIG. 2, body region 105 has a p-dopant level indicated as “P” ¶ [0029]) and the body contact region has a second doping level (Saggio FIG. 2, interface 114 has a p-dopant level indicated as “P+” ¶ [0035]) higher than the first doping level (a person of ordinary skill in the art would deduce that a “P+” dopant level is higher than a “P” dopant level).
Claims 21-26 are rejected under 35 U.S.C. 103 as being unpatentable over Saggio.
Regarding claim 21, Saggio discloses a MOSFET device (the device of FIG. 2 ¶ [0021]), comprising: a substrate (FIG. 2, semiconductor body 102 is an SiC substrate ¶ [0028]) of silicon carbide having a first conductivity type (N type ¶ [0028]) and a top surface (FIG. 2, top surface 102a ¶ [0027]); a first gate electrode (FIG. 2, left instance of gate conductive layer 106a ¶ [0031]) extending lengthwise in a first lateral direction (FIG. 2, gate conductive layer 106a extends along the X direction over top surface 102a) on the top surface; a first body region (FIG. 2, left instance of body region 105 ¶ [0030]) of a second conductivity type (P type ¶ [0029]) in the substrate extending lengthwise in the first direction (FIG. 2, left instance of body region 105 is seated in semiconductor body 102 and extends along the X direction) below a first edge of the gate electrode (FIG. 2, left instance of body region 105 is vertically below a left edge of left gate conductive layer 106a); a second body region (FIG. 2, right instance of body region 105 which is also P type ¶ [0029-0030]) of the second conductivity type in the substrate extending lengthwise in the first direction (FIG. 2, right instance of body region 105 is seated in semiconductor body 102 and extends along the X direction) below a second edge of the gate electrode (FIG. 2, right instance of body region 105 is vertically below a right edge of left gate conductive layer 106a; it is not currently required that the gate electrode vertically overlap the second body region); a first source region (FIG. 2, N+ type source region 108 located at the right side of left interface 114 extends into semiconductor body 102 through surface 102a ¶ [0030]) of the first conductivity type embedded in the first body region below the first edge of the gate electrode; a second source region (a person of ordinary skill in the art before the effective filing date of the claimed invention would have found it obvious to have each interface 114 having a source region 108 at each of its left and right sides, because while FIG. 2 does not explicitly illustrate that, it is stated that the structure of FIG. 2 may be replicated ¶ [0025], and the non-illustrated portions of interfaces 114 having source regions 108 at both left and right sides would be obvious to include to increase the device’s functionality; an N+ type source region 108 located at the left side of left interface 114 of FIG. 2 extends into semiconductor body 102 through surface 102a ¶ [0030]) of the first conductivity type embedded in the first body region below the first edge of the gate electrode (the N+ type source region 108 located at the left side of left interface 114 of FIG. 2 is embedded in the left body region 105 and is vertically below left gate conductive layer 106a’s left edge; it is not currently required that the gate electrode’s edge vertically overlap the second source region);
a first body contact region (FIG. 2, left instance of electrical contact interface 114 is a P+ type body contact region ¶ [0035]) of the second conductivity type extending downward from the top surface through the first source region into the first body region (FIG. 2, left interface 114 extends into left body region 105 through top surface 102a) and extending lengthwise in the first lateral direction (FIG. 2, left interface 114 extends along the X direction); and a second body contact region (FIG. 2, right instance of electrical contact interface 114 is a P+ type body contact region ¶ [0035]) of the second conductivity type extending downward from the top surface through the second source region into the second body region(FIG. 2, right interface 114 extends into right body region 105 through top surface 102a) and extending lengthwise in the first lateral direction (FIG. 2, right interface 114 extends along the X direction).
Regarding claim 22, Saggio discloses the limitations of claim 21 as detailed above and further discloses a source metallization (FIG. 2, metal layer 110 functions as a source metallization ¶ [0034-0035]) overlying the gate electrode and contacting the first source region, the first body contact region, the second source region, and the second body contact region (FIG. 2, metal layer 110 overlies gate conductive layers 106a and electrically contacts source regions 108 and interfaces 114 ¶ [0035]).
Regarding claim 23, Saggio discloses the limitations of claim 22 as detailed above and further discloses a drain region (FIG. 2, drain terminal D is in a drain region ¶ [0025]) below the gate electrode between the first body region and the second body region (FIG. 2, drain terminal D is between the left and right instances of body regions 105).
Regarding claim 24, Saggio discloses the limitations of claim 23 as detailed above but does not explicitly show a drain metalization below the substrate. Saggio does however teach that a drain terminal is below the substrate (FIG. 2, drain terminal D is below semiconductor body 102 which represents the claimed SiC substrate ¶ [0025]), and discusses the drain terminal alongside a source terminal S and gate terminal G. The source and the gate are both metallizations (metal layer 110 functions as a source metallization ¶ [0034-0035], and metal gate conductive layer 106a functions as a gate metallization ¶ [0031]). A person of ordinary skill in the art before the effective filing date of the claimed invention would have also found it obvious to also include a drain metallization at the drain terminal D below the substrate as claimed, since metallization was found to be suitable for both the source and gate terminals of Saggio and it is known in the art that a metal material is a suitable conductor in a transistor terminal. Therefore, having drain terminal D formed of metallization would be obvious to a person of ordinary skill in the art, and could prove beneficial in view of materials costs and changing market conditions.
Regarding claim 25, Saggio discloses the limitations of claim 21 as detailed above and further discloses that the first body region has a first doping level (FIG. 2, body region 105 has a p-dopant level indicated as “P” ¶ [0029]) and the first body contact region has a second doping level (FIG. 2, interface 114 has a p-dopant level indicated as “P+” ¶ [0035]) higher than the first doping level (a person of ordinary skill in the art would deduce that a “P+” dopant level is higher than a “P” dopant level).
Regarding claim 26, Saggio discloses the limitations of claim 21 as detailed above and further discloses that the first body conductivity type is N-type (N type conductivity is used as the first conductivity type for semiconductor body 102, ¶ [0028]).
Cited Prior Art
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure: US patent publications US 20230086599 A1, US 20200203513 A1, and US 20130009256 A1.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to EDWARD RHETT CHEEK whose telephone number is (571)272-3461. The examiner can normally be reached Monday - Thursday 7:30am - 5pm, Every other Friday 8:30am - 5pm.
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/E.R.C./Examiner, Art Unit 2813
/STEVEN B GAUTHIER/Supervisory Patent Examiner, Art Unit 2813
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