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 .
Status of Claims
Applicant cancelled Claims 1-14 and added new Claims 15-28.
Claims 15 and 28 are directed to two inventions – a device (Claims 15-22) and a method of manufacturing a device (Claims 23-28), which are commonly are subjected to restriction requirements.
However, since the method claims do not have limitations directed to specific method steps, the current Office Action examine both – device and method claims.
Claims 15-28 are examined on merits herein.
Drawings
The drawings are objected to as failing to comply with 37 CFR 1.84(p)(4) because reference characters "102" and "110b" are directed to source metal 102, while 110b shall be directed to a gate trench (e.g., the arrow from 110b shall be closer to a gate) Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
The drawings are objected to under 37 CFR 1.83(a). The drawings must show every feature of the invention specified in the claims. Therefore, “a region of a bottom of the respective gate trench remains free”, cited by Claims 19 and 27 must be shown or the feature canceled from the claims. Currently, there is no figure showing a bottom of the gate trench being free – all gate trenches are filled either by a gate dielectric or by a portion of a source electrode. No new matter should be entered.
Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Abstract
Applicant is reminded of the proper content of an abstract of the disclosure.
A patent abstract is a concise statement of the technical disclosure of the patent and should include that which is new in the art to which the invention pertains. The abstract should not refer to purported merits or speculative applications of the invention and should not compare the invention with the prior art.
If the patent is of a basic nature, the entire technical disclosure may be new in the art, and the abstract should be directed to the entire disclosure. If the patent is in the nature of an improvement in an old apparatus, process, product, or composition, the abstract should include the technical disclosure of the improvement. The abstract should also mention by way of example any preferred modifications or alternatives.
Where applicable, the abstract should include the following: (1) if a machine or apparatus, its organization and operation; (2) if an article, its method of making; (3) if a chemical compound, its identity and use; (4) if a mixture, its ingredients; (5) if a process, the steps.
Extensive mechanical and design details of an apparatus should not be included in the abstract. The abstract should be in narrative form and generally limited to a single paragraph within the range of 50 to 150 words in length.
See MPEP § 608.01(b) for guidelines for the preparation of patent abstracts.
Abstract is objected to due to its recitation: “several gate trenches extending vertically from the n-doped source layer to the n-doped drain layer”. The recitation is unclear, since, based on a structure of the current application, it is a channel layer 106 that “extends vertically from the n-doped source layer 104 to the n-doped drain layer 120”. For a better clarity of the objection, Fig. 1 of the structure of the current application is reproduced below. It shows that a gate trench (with gates 110a or 110b) is disposed from a surface coplanar with a top surface of the source region 104 to a drain region.
Annotate Fig. 1
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Appropriate correction/clarification is required.
Specification
The disclosure is objected to because of the following informalities:
Specification is not quite clear with respect to a citation: “several gate trenches which extend vertically from the n-doped source layer to the n-doped drain layer”, as paragraphs 0004 and 0014 of the SUMMARY of the application state. Paragraph 0043 (of the Detailed Description), referring to Fig. 5, also have a similar statement, but since it refers to a particular figure, it allows to understood that a gate trench extends from a level coplanar with a top surface of a source layer to a drain layer 120. Appropriate correction of at least paragraphs 0004 and 0014 is required.
Specification is unclear with respect to a recitation: “a bottom of the gate trench remains free”, which is cited by paragraphs 0005 and 0017 of the published application US 2024/0128342 and repeated by Claims 19 and 27. Does the recitation mean that a portion of a gate trench is free from a gate material (a gate electrode and/or a gate insulation) or that a trench is in contact with an air? Since no figure of the application shows a contact between a bottom of the gate trench and an air, it looks like the recitation mans: “being free from a gate electrode”, but no explicit statement on this is made.
Appropriate correction/clarification is required.
Claim Objections
Claim 16 objected to because of the following informalities:
Claim 16 recites: “each two adjacent one of the fins”. Examiner suggests changing the recitation to: “each two adjacent fins”, - as being more grammatically correct.
Appropriate correction is required.
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.
Claims 15-28 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
In re Claim 15: Lines 6-7 of Claim 15 recites: “gate trenches which extend vertically from the n-doped source layer to the n-doped drain layer”. The recitation is unclear for the same reason that explains in objection to paragraphs 0004 and 0014 of the specification. Detailed description of the application shows that the gate trenches extend from a level coplanar with a top surface of the source layer, not from a bottom of the source layer.
Appropriate correction is required to clarify the claim language.
For this Office Action, the cited limitation was interpreted as: “gate trenches which extend vertically from a level coplanar with a top surface of the n-doped source layer to the n-doped drain layer”.
In re Claim 15: Claim 15 recites (lines 8-9): “a fin is respectively formed between each two of the gate trenches, wherein at least two of the fins have different widths”. There is a lack of antecedent basis for using “fins” with article “the”, since the claim earlier does not recite: “fins”, but recite: “a fin”.
Appropriate correction is required to clarify the claim language.
For this Office Action, the cited recitation was interpreted as: “fins are formed between gate trenches such that one fin is disposed between two adjacent gate trenches, wherein at least two fins have different widths”.
In re Claim 17: Claim 17 recites: “wherein the several fins in total have at least three different widths”. There is a lack of antecedent basis for using article “the” with: “several fins”, since “several fins” were not cited earlier by Claim 17 or by Claim 15 on which Claim 17 depends. In addition, it is unclear whether the recitation means that each fin has a few different widths or that each fin has one width and widths of three fins are different from each other.
Appropriate correction is required to clarify the claim language.
For this Office action, the cited recitation of Claim 17 was interpreted as: “wherein the field-effect transistor has at least three fins each comprising its own width different from widths of two other fins”.
In re Claim 18: Claim 18 recites: “several gate electrodes surrounded at least partially by a dielectric, wherein the gate electrodes are respectively arranged in the gate trenches”. The recitation is unclear, since leads to a question: Are several gate electrodes are surrounded by one dielectric or each gate electrode is surrounded by a gate dielectric?
Appropriate correction is required to clarify the claim language.
For this Office Action, the cited recitation was interpreted (based on the specification) as: “several gate electrodes, each gate electrode being surrounded, at least partially, by a dielectric and arranged in a corresponding gate trench”.
In re Claim 19: Claim 19 has a recitation: “a region of a bottom of the respective gate trench remains free”. The recitation is not quite clear for the same reason that is explained in the objection to the specification.
Appropriate correction is required to clarify the claim language.
For this Office Action, the cited recitation is interpreted as: “a region of a bottom of the respective gate trench remains free from a gate material”.
In re Claim 23: Claim 23 is unclear for the same reasons that are explained for Claim 15, since it has same limitations as lines 6-7 and lines 8-9 of Claim 15. Appropriate corrections are required to clarify the claim language.
For Office Action, the cited limitation was interpreted similar to its interpretation of Claim 15.
In re Claim 27: Claim 27 is unclear for the same reason that is cited for Claim 19, and for this Office Action, it was interpreted in a similar way.
In re Claim 28: Claim 28 recites: “further comprising, after introduction of the gate electrodes: metallizing”. The recitation is not quite clear, since the specification does not explicitly teach “metallizing”. It teaches (in a device structure of Fig. 1, but not in a method of manufacturing of Figs. 5) – a deposited metal source electrode 102 (paragraph 0029 of the published application).
Appropriate correction is required to clarify the claim language.
For this Office Action, the cited limitation was interpreted as: “further comprising, after introduction of the gate electrodes: depositing a metal source electrode”.
In re Claims 16, 20-22, and 24-26: Claims 16, 20-22, and 24-26 are rejected under 35 U.S.C. 112(b) due to dependency on one of independent Claims 15 or 23.
Claim Rejections - 35 USC § 102
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.
As far as the claims are understood, Claims 15, 16, 18, and 20 are rejected under 35 U.S.C. 102(a)(2) as being anticipated by Okumura et al. (US 6,060,747).
In re Claim 15, Okumura teaches a field-effect transistor (such as a MOSFET, see Claim 5), comprising (Figs. 3-4, Embodiment 1):
an n-doped source layer 13 (column 6 line 24);
an n-doped drain layer 19 (column 7, line 51);
a channel layer 12 (called “base layer”, column 6 line 21) located vertically between the n-doped source layer 13 and the n-doped drain layer 19; and
several gate trenches 14 (column 6 line 36) which extend vertically from the n-doped source layer 13 to the n-doped drain layer 19, and adjoining the channel layer 12; wherein
a fin (comprised semiconductors 12 and 13) is respectively formed between each two of the gate trenches 14, wherein
at least two of the fins have different widths – such as T1 and T2 (column 6 lines 63-67, column 7 lines 1-7).
In re Claim 16, Okumura teaches the field-effect transistor according to Claim 15, wherein (Figs 3-4) each two adjacent one of the fins have different widths T1 and T2 (as shown and as described for Claim 15).
In re Claim 18, Okumura teaches the field-effect transistor according to Claim 15, further comprising (Figs. 3-4) several gate electrodes 16 (column 6 line 41) surrounded at least partially by a dielectric 15 (column 6 line 43), wherein the gate electrodes 16 are respectively arranged in the gate trenches 14.
In re Claim 20, Okumura teaches the field-effect transistor according to Claim gate trench 14, wherein (Figs. 3-4) the channel layer 12 is p-doped (column 6 line 23).
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.
As far as the claims are understood, Claims 21-23, 26, and 28 are rejected under 35 U.S.C. 103 as being unpatentable over Okumura in view of Saggio et al. (US 2022/0157989).
In re Claim 21, Okumura teaches the field-effect transistor according to Claim 15 as cited above, but does not teach a p-doped shielding region vertically below a respective gate trench, in the n-doped drain layer.
Saggio teaches (Fig. 2) a p-doped shielding region 44a (or 44b, paragraph 0048) vertically below a gate trench (with gates 42, paragraph 0041) in an n-doped drain layer 34/36 (paragraphs 0034, 0036, 0059).
Okumura and Saggio teach analogous arts directed to MOSFETs with trenched gates, and one of ordinary skill in the art before the effective date of filing the application would have had a reasonable expectation of success in modifying the Okumura device in view of the Saggio device, since they are from the same field of endeavor, and Saggio created a successfully operated device.
It would have been obvious for one of ordinary skill in the art before the effective date of filing the application to modify the Okumura device by creating a p-type shield region below each gate trench, in the n-doped drain layer, wherein it is desirable to create the field-effect transistor with a low on-state resistance and a high reliability (Saggio, paragraph 0028).
In re Claim 22, Okumura teaches the field-effect transistor according to Claim 15 as cited above, but does not teach that the field-effect transistor is a SiC or GaN or gallium-oxide field-effect transistor – no explicit semiconductor material for creating the transistor is disclosed by Okumura.
Saggio teaches a SiC field effect transistor (paragraph 0001).
It would have been obvious for one of ordinary skill in the art before the effective date of filing the application to create the field-effect transistor of Okumura from SiC semiconductor, at least in order to enable creation of the semiconductor material.
In re Claim 23, Okumura teaches a method (inherently) for producing a field-effect transistor, comprising the following steps (Fig. 4):
forming (obviously) several gate trenches 14, which extend vertically from the n-doped source layer 13 (column line) to the n-doped drain layer 11/19 (column 6, line 23 and column 7 lines 8-10), and
adjoin the channel layer 12 (called “p-type base, column 6 line 21) so that a fin is respectively formed between each two of the gate trenches 14, wherein at least two of the fins have different widths T1 and T2 (column 6 lines 63-67 and column 7 lines 1-7).
Okumura does not teach (at least, explicitly) a step of providing a starting material including: an n-doped source layer, an n-doped drain layer, and a channel layer located vertically between the n-doped source layer 13 (column line) and the n-doped drain layer before forming the trenches.
Saggio teaches a method of manufacturing a field-effect transistor (Figs. 3A-3F), which begins from a step (Fig. 3A) of providing a starting material including an n-doped source layer 70 (paragraph 0064), an n-doped drain layer 64, 66 (paragraphs 0061, 0062, 0059), and a p-doped channel layer 68 (paragraph 0063) located vertically between the source and drain layers, followed by formation of trenches 74 (Fig. 3B, paragraph 0067).
It would have been obvious for one of ordinary skill in the art before filing the application to modify the Okumura method by including an initial step of providing a starting material, including an n-doped source layer, an n-doped layer, and p-doped channel layer disposed between the n-type source and drain layers, before forming trenches, in order to enable formation of the initial step of the method.
In re Claim 26, Okumura/Saggio teaches the method according to Claim 23 as cited above and further comprising, after the formation of the several gate trenches (Saggio, Figs. 3C-3E, paragraphs 0081, 0078): introducing a gate electrode 82, which is surrounded at least partially by a dielectric 80, into each respective gate trench of the gate trenches.
In re Claim 28, Okumura/Saggio teaches the method according to Claim 26, further comprising, after introduction of the gate electrodes: metallizing – e.g., (Fig. 4 of Saggio, paragraphs 0057, 0084) forming a metal source electrode 50.
Allowable Subject Matter
Claims 17, 19, 24, 25, and 27, as interpreted, contain allowable subject matter and will be allowed if amended to incorporate all limitations of a corresponding base claim and all intervening claims (if any) with corrected issues of 35 U.S.C. 112(b).
Reasons for Indicating Allowable Subject Matter
Re Claim 17: Although such prior art as Hsieh (US 2011/0254086) teaches a possibility of having fins that differ from each other by a widths, Hsieh cannot be combined with Okumura for teaching the limitation of Claim 17 ( “several fins in total have at least three different widths”), in combination with other limitations of Claim 17 and with all limitations of Claim 15 (corrected to remove grounds for rejections under 35 U.S.C. 112(b)), since the Hsieh fins are disposed in a termination region, and modifying the fins of Okumura in an active region to repeat shapes of fins of Hsieh would be too difficult to implement, while having no reasonable motivation for such modification.
Re Claim 19: Although such prior art as Hsieh (US 2008/0121986) teaches a possibility of creating a trench having an electrode divided into at least two parts in such a way that “a region of a bottom of the trench is free” (as interpreted), the Examiner found no motivation in modifying the Okumura gate trench of Claim 15 with such dispositions of portions of the gate electrode in the trench: Hsieh uses the cited structure because different parts of his (field) electrode are connected to different potentials, while there is no reason connecting different parts of the Okumura gates to different potentials.
Re Claim 24: The prior arts of record, alone or in combination, fail(s) to anticipate or render obvious such limitation of Claim 24 as: “finally forming the several gate trenches, wherein the fins are respectively narrowed evenly”, in combination with other limitations of Claim 24 and with all limitations of Claim 23, corrected by removing grounds for rejections under 35 U.S.C. 112(b). Claim 25 depends on Claim 24.
Re Claim 27: Although such prior art as Hsieh (US 2008/0121986) teaches a possibility of creating a trench having an electrode divided into at least two parts in such a way that “a region of a bottom of the trench is free” (as interpreted), the Examiner found no motivation in modifying the Okumura/Saggio method of Claim 23 (corrected for removal grounds for rejections under 112(b)) with such dispositions of portions of the gate electrode in the trench: Hsieh using the cited structure because different parts of his electrode are connected to different potentials, while there is no reason connecting different parts of the Okumura gates in different potentials.
The prior arts of record considered for this Office Action, in addition to all prior arts cited above, also include at least: Kubo (US 2002/0043684), Chen et al. (US 9,484,451), Cao (US 7,075,147), Burke et al. (US 2018/0096849), as well as the prior art of the IDS.
Conclusion
Any inquiry concerning this communication should be directed to GALINA G YUSHINA whose telephone number is 571-270-7440. The Examiner can normally be reached between 8 AM - 7 PM Pacific Time (Flexible).
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/GALINA G YUSHINA/Primary Patent Examiner, Art Unit 2811, TC 2800,
United States Patent and Trademark Office
E-mail: galina.yushina@USPTO.gov
Phone: 571-270-7440
Date: 01/12/26