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 Species II (FIG. 4) and sub-species D (FIG. 6(d)) in the reply filed on 5 Jun 2026 is acknowledged.
Claims 5–9, 11, and 18–20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected species/sub-species, there being no allowable generic or linking claim. Election was made without traverse in the reply filed on 5 Jun 2026.
Response to Amendment
Applicant’s reply dated 5 Jun 2026 in response to the requirement for restriction/election dated 7 Apr 2026 included amendments to the specification (replacements for paragraphs [0083], [0084], [0101], and [0049]) and drawings (replacements for all drawing sheets). These amendments correct all of the problems numbered 1–14 that were noted by the examiner on pages 8–10 of the requirement for restriction/election dated 7 Apr 2026.
Specification
The title of the invention (SEMICONDUCTOR STRUCTURE AND PREPARATION METHOD THEREOF) is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed. The examiner suggests the following title: VERTICALLY CONDUCTIVE NITRIDE SEMICONDUCTOR STRUCTURE AND PREPARATION METHOD THEREOF.
Claim Objections
Claims 3–4, 6, 8–12, and 14–20 are objected to because of the following informalities. Appropriate correction is required.
Claim 3 states “along an epitaxial growth direction” three times (in lines 2, 5, and 9). The examiner suggests keeping “an” in line 2 but changing lines 5 and 9 to state “along the epitaxial growth direction”.
Claim 4: the examiner suggests adding a comma after “stepped increment” in line 4 and in line 7 to follow the list format “A, B, or C”:
4. (Proposed Amendment) The semiconductor structure according to claim 3, wherein, along the epitaxial growth direction, the Al composition of the AlGaN insertion layer changes from the initial growth to a point of a maximum Al composition in one or a combination of continuous increment, stepped increment[,] or oscillatory increment; and
along the epitaxial growth direction, the Al composition of the AlGaN insertion layer changes from the maximum Al composition to the end of growth in one or a combination of continuous decrement, stepped decrement[,] or oscillating decrement.
Claim 6: although this claim currently stands as withdrawn/nonelected, in case the claim is later rejoined, the examiner suggests adding “a” in “a width” in line 1, and adding a comma after “stepped decreasing”:
6. (Proposed Amendment) The semiconductor structure according to claim 1, wherein, from a bottom of the groove to a top of the groove, a width of the groove is constant, linearly increasing, linearly decreasing, periodically varying, increasing first and decreasing after, stepped increasing[,] or stepped decreasing.
Claim 8: although this claim currently stands as withdrawn/nonelected, in case the claim is later rejoined, the examiner suggests the following amendment in lines 4–5: “the first sub-layer and the second sub-layer are arranged, respectively, from a bottom of the third nitride semiconductor layer to a top of the third nitride semiconductor layer”.
Claim 9: although this claim currently stands as withdrawn/nonelected, in case the claim is later rejoined, the examiner suggests the following amendment:
9. (Proposed Amendment) The semiconductor structure according to claim 1, wherein, from a bottom of the source region to a top of the source region, the source region comprises a first sub-layer and a second sub-layer, wherein a doping concentration of the first sub-layer of the source region is lower than a doping concentration of the second sub-layer of the source region, and a top of an upper surface of the first sub-layer of the source region does not exceed the groove.
Claim 10: the examiner suggests the following amendment:
10. (Proposed Amendment) The semiconductor structure according to claim 1, wherein, the third nitride semiconductor layer includes aluminum (Al), and a composition curve of the Al composition in an epitaxial direction comprises one or a combination of the following variation stages: periodic variation, increasing variation[,] and decreasing variation, and
the Al composition has no jump at a contact interface between the third nitride semiconductor layer and the second nitride semiconductor layer.
Claim 11: although this claim currently stands as withdrawn/nonelected, in case the claim is later rejoined, the examiner suggests changing “the” to “a” in “the gate electrode being arranged on a top surface of the third nitride semiconductor layer” (in lines 3–4).
Claim 12: the examiner suggests the following amendment to correct informalities:
12. (Proposed Amendment) A preparation method of a semiconductor structure, comprising:
providing a first nitride semiconductor layer;
forming a second nitride semiconductor layer covering the first nitride semiconductor layer, a conductivity type of the second nitride semiconductor layer and a conductivity type of the first nitride semiconductor layer being same, and [a] doping concentration of the second nitride semiconductor layer being lower than [a] doping concentration of the first nitride semiconductor layer;
forming a third nitride semiconductor layer covering the second nitride semiconductor layer, wherein a conductivity type of the third nitride semiconductor layer is opposite to the conductivity type of the second nitride semiconductor layer;
forming a mask layer covering the third nitride semiconductor layer;
forming an opening on the mask layer, the opening exposing the third nitride semiconductor layer;
etching the third nitride semiconductor layer to form a groove, the groove penetrating the third nitride semiconductor layer; and
forming a source region after filling the groove, wherein the source region is connected with the second nitride semiconductor layer, and a conductivity type of the source region and the conductivity type of the second nitride semiconductor layer are the same.
Claim 14: the examiner suggests the following amendment to correct informalities:
14. (Proposed Amendment) The preparation method of the semiconductor structure according to claim 13, wherein, the groove is formed by a two-step eching of the third nitride semiconductor layer as follows:
dry-etching the third nitride semiconductor layer to form the groove, wherein the dry-etching is stopped right before etching the AlGaN insertion layer;
cleaning the groove; and
in-situ etching a surface of the groove until the bottom of the groove exposes the AlGaN insertion layer.
Claim 15: the examiner suggests adding “an” before “Al composition” in line 3: “along an epitaxial growth direction, an Al composition of the AlGaN insertion layer increases …”
Claim 16: the examiner suggests adding a comma after “stepped increment” in line 4 and in line 7 to follow the list format “A, B, or C”.
Claim 17: the examiner suggests the following amendment to correct informalities:
17. (Proposed Amendment) The preparation method of the semiconductor structure according to claim 12, wherein,
the third nitride semiconductor layer includes aluminum (Al), and a composition curve of the Al composition in an epitaxial direction comprises one or a combination of the following variation stages: periodic variation, increasing variation[,] and decreasing variation,
wherein the Al composition has no jump at a contact interface between the third nitride semiconductor layer and the second nitride semiconductor layer.
Claim 18: although this claim currently stands as withdrawn/nonelected, in case the claim is later rejoined, the examiner suggests the following amendment:
18. (Proposed Amendment) The preparation method of the semiconductor structure according to claim 12, wherein, from a bottom to a top of the groove, [a] width of the groove is constant, linearly increasing, linearly decreasing, periodically varying, increasing first and decreasing after, stepped increasing[,] or stepped decreasing.
Claim 19: although this claim currently stands as withdrawn/nonelected, in case the claim is later rejoined, the examiner suggests the following amendment in lines 4–5: “the first sub-layer and the second sub-layer are respectively arranged from a bottom of the third nitride semiconductor layer to a top of the third nitride semiconductor layer”.
Claim 20: although this claim currently stands as withdrawn/nonelected, in case the claim is later rejoined, the examiner suggests the following amendment:
20. (Proposed Amendment) The preparation method of the semiconductor structure according to claim 12, wherein, from a bottom of the source region to a top of the source region, the source region comprises a first sub-layer and a second sub-layer, wherein a doping concentration of the first sub-layer of the source region is lower than [a] doping concentration of the second sub-layer of the source region, and a top of an upper surface of the first sub-layer of the source region does not exceed the groove.
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.
Claims 1–20 are 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.
Regarding claim 1, the examiner finds the following text from lines 9–11 of claim 1 to be indefinite: “a conductivity type of the third nitride semiconductor layer being opposite to the doping concentration of the second nitride semiconductor layer”. Conductivity type is either p-type or n-type, with the two conductivity types being opposites to each other, representing either positive or negative majority charge carriers, respectively. In contrast, doping concentration (which is a number density in units of cm−3, for example) is a continuous variable having infinitely many possible values, representing the average number of majority charge carriers per unit volume within a semiconductor material. Thus, it is unclear how a conductivity type (binary choice + or −) can be “opposite” to a number density (continuous variable). To make claim 1 definite, the examiner suggests the following amendment to the aforementioned portion: “a conductivity type of the third nitride semiconductor layer being opposite to a conductivity type of the second nitride semiconductor layer” (in agreement with ¶[0007, 0027, 0064, 0077]).
Claims 2–11 depend on claim 1 and therefore include the indefinite language of claim 1 by reference.
Regarding claims 3–4, claim 4 references “from the initial growth” and “to the end of growth”. However, claim 3, upon which claim 4 depends, only mentions “at initial growth” and “at the end of growth” in the first of the three paragraphs that begin with “along an epitaxial growth direction”. Thus, it is unclear to the examiner if the limitations of dependent claim 4 only apply to the first of the three paragraphs in claim 3 that begin with “along an epitaxial growth direction”, or if the limitations of dependent claim 4 apply to all three of the three paragraphs in claim 3 that begin with “along an epitaxial growth direction”. If the latter case is Applicant’s intended meaning, the examiner suggests making claims 3 and 4 both definite by clarifying that “at initial growth” and “at the end of growth” apply to all three cases of claim 3 with the following amendment to claim 3:
3. (Proposed Amendment) The semiconductor structure according to claim 2, wherein, along an epitaxial growth direction from an initial growth to an end of growth,
an Al composition of the AlGaN insertion layer increases from 0 of Al composition to a maximum value of Al composition, and then to 0 of Al composition ; or
the Al composition of the AlGaN insertion layer increases from 0 of Al composition to the maximum value of Al composition or increases from 0 of Al composition to the maximum value of Al composition and then decreases to an intermediate value of Al composition; or
the Al composition of the AlGaN insertion layer decreases from the maximum value to 0 of Al composition or increases from the intermediate value to the maximum value of Al composition and then decreases to 0 of Al composition.
Note that claim 15 contains similar subject matter to claim 3. Thus, if Applicant amends claim 3 following the examiner’s suggestion above, Applicant may also wish to amend claim 15 in a similar way.
Claim 12 recites the limitation in the last 3 lines of “forming a source region after filling the groove, wherein the source region is connected with the second nitride semiconductor layer, and a conductivity type of the source region and the conductivity type of the second nitride semiconductor layer being same”. The examiner finds the use of the word “after” to be indefinite because, as written, it suggests that forming the source region 4 is a separate process that happens after a process of filling in the groove with some other material, when in fact, the source region 4 is the same material that fills the groove 30 (as shown in FIGS. 5(c) and 5(d)). The examiner suggests amending this portion of claim 12 to either “forming a source region by filling the groove” (as in ¶[0031]) or “forming a source region filling the groove” (as in ¶[0080] and ¶[0098]).
Claims 13–20 depend on claim 12 and therefore include the indefinite language of claim 12 by reference.
Claim 13 recites the limitation “the AlGaN insertion layer” in line 2. There is insufficient antecedent basis for this limitation in the claim because neither claim 13 nor claim 12, upon which claim 13 depends, has previously introduced “an AlGaN insertion layer”. Therefore, a portion of line 2 of claim 13 should be amended as “the second nitride semiconductor layer comprises an AlGaN insertion layer”.
Allowable Subject Matter
The following is a statement of reasons for the indication of allowable subject matter:
Claim 1 would be allowable if rewritten or amended to overcome the rejection under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action. The closest prior art of Chinese patent application publication CN-115036220-A by Sun et al. (“Sun” hereafter, relying on attached machine translation) fails to teach
“the third nitride semiconductor layer comprising a groove, and the groove penetrating the third nitride semiconductor layer; and
a source region formed in the groove, and a conductivity type of the source region and the conductivity type of the second nitride semiconductor layer being same”
in combination with all other limitations in the claim as claimed and defined by applicant.
Regarding claim 1, Sun teaches:
A semiconductor structure (FIG. 16, “a GaN all-vertical structure electronic device” ¶[0033]), comprising:
a first nitride semiconductor layer 30 (“an n+ type GaN epitaxial layer 30” ¶[0081]) comprising a first surface (top) and a second surface (bottom) being opposite to the first surface (top);
a second nitride semiconductor layer 40 (“an n− type GaN epitaxial layer 40” ¶[0081]) formed on the first nitride semiconductor layer 30, a conductivity type (n) of the second nitride semiconductor layer 40 and a conductivity type (n) of the first nitride semiconductor layer 30 being the same (n), and a doping concentration (low doping as indicated by the “−” in “n− type GaN epitaxial layer 40”) of the second nitride semiconductor layer 40 being lower than a doping concentration (high doping as indicated by the “+” in “n+ type GaN epitaxial layer 30”) of the first nitride semiconductor layer 30;
a third nitride semiconductor layer 60 (“a p-type GaN layer 60” ¶[0081]) formed on the second nitride semiconductor layer 40, a conductivity type (p) of the third nitride semiconductor layer 60 being opposite to the doping concentration1 (a conductivity type of n) of the second nitride semiconductor layer 40, the third nitride semiconductor layer 60 comprising a groove (the U-shaped recesses in the third nitride semiconductor layer 60 in FIG. 6 which are formed as a “groove structure” ¶[0036] in FIG. 9), and the groove penetrating the third nitride semiconductor layer 60.
However, instead of having a “source region formed in the groove” as required by claim 1 of the present application, Sun’s FIG. 16 has (“an anode Schottky contact electrode … 100” ¶[0081] formed in the groove. Sun’s anode Schottky contact electrode 100 is made of a metal: “Anode Schottky metal is deposited in the groove structure by means of thermal evaporation and annealing to form the first electrode 100, so that the first electrode 100 forms a good Schottky contact with the exposed Al-containing group III nitride semiconductor insertion layer 50, as shown in Figure 12” ¶[0089]. A metal electrode such as Sun’s anode Schottky contact electrode 100 cannot be described as having a same conductivity type (n) as the second nitride semiconductor layer 40 (“an n− type GaN epitaxial layer 40” ¶[0081]) because it is understood in the field of semiconductors that the terms “p-type” and “n-type” specifically refer to a semiconductor material that has been doped with dopants to cause the semiconductor material to have an excess of positive charge carriers (holes) or negative charge carriers (electrons), respectively. Thus, a metal electrode such as Sun’s anode Schottky contact electrode 100 is neither p-type nor n-type since these descriptors apply specifically to semiconductors, and Sun’s anode Schottky contact electrode 100 is not made of a semiconductor material. Therefore, Sun’s anode Schottky contact electrode 100 does not meet the requirements of the source region of claim 1 of the present application because the source region must be made of a semiconductor material having a same conductivity type (n) as the second nitride semiconductor layer 40.
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Other similar prior art of patent application publication US 2013/0161633 A1 by Nie et al. (“Nie” hereafter) teaches:
A semiconductor structure (FIG. 11, “a vertical JFET” ¶[0014]), comprising:
a first nitride semiconductor layer 200 (“GaN substrate 200” ¶[0036]) comprising a first surface (top) and a second surface (bottom) being opposite to the first surface (top);
a second nitride semiconductor layer 201 (“first GaN epitaxial layer 201” ¶[0036]) formed on the first nitride semiconductor layer 200, a conductivity type of the second nitride semiconductor layer 201 and a conductivity type of the first nitride semiconductor layer 200 being the same (“a first GaN epitaxial layer 201 is formed on a GaN substrate 200 having the same conductivity type” ¶[0036]), and a doping concentration of the second nitride semiconductor layer 201 being lower than a doping concentration of the first nitride semiconductor layer 200 (“a GaN substrate 200 can have an n+ conductivity type, with dopant concentrations ranging from 1×1017 cm−3 to 1×1019 cm−3” ¶[0036] and “The first GaN epitaxial layer 201 can serve as a drift region for the Schottky diode, and therefore can be a relatively low-doped material. For example, the first GaN epitaxial layer 201 can have an n− conductivity type, with dopant concentrations ranging from 1×1014 cm−3 to 1×1018 cm−3” ¶[0037]);
a third nitride semiconductor layer 1130 (“gate regions 1130” ¶[0073]) formed on the second nitride semiconductor layer 201, a conductivity type of the third nitride semiconductor layer 1130 being opposite to the doping concentration [conductivity type] of the second nitride semiconductor layer 201 (“Gate regions 1130 can be formed from the same epitaxial growth or regrowth as the edge termination structures 1102 and 1103, which has an opposite conductivity type as the first GaN epitaxial layer 201” ¶[0073]), the third nitride semiconductor layer 1130 comprising a groove (where the “channel region 1110” ¶[0073] is located), and the groove penetrating the third nitride semiconductor layer 1130 (the channel region 1110 penetrates the third nitride semiconductor layer 1130 as shown in FIG. 11).
However, Nie’s FIG. 11 does not show a “source region formed in the groove”, as required by claim 1 of the present application. Rather, the source region 1120 (“source region 1120” ¶[0073]) is located directly above the channel region 1110, and the channel region 1110 fills the groove such that no part of the source region 1120 is located inside of the groove. That is, the source region 1120 is formed directly above the groove in the third semiconductor layer 1130 where the channel region 1110 is located, but the source region 1120 is not formed inside of the groove.
Note that in agreement with claim 1, Nie’s source region 1120 has the same conductivity type as the second nitride layer 201: “a source region 1120 can be formed from an epitaxial layer of the same conductivity type as the channel region 1110 and the first GaN epitaxial layer 201” ¶[0073].
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Claims 2–11 would be allowable at least because they depend on claim 1, which contains allowable subject matter as explained above, if claims 3–4, 6, and 8–11 were amended to overcome the objections provided in this office action, and if claims 1 and 3–4 were amended to overcome the rejections under 35 USC § 112(b) provided in this office action. In such chase, withdrawn/nonelected claims 5–9 and 11 would be rejoined since they include all the limitations of an allowable claim (claim 1).
Claim 12 would be allowable if rewritten or amended to overcome the rejection under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action. The closest prior art of Sun and Nie, as cited above in reference to claim 1, fail to teach
“forming a source region after [by] filling the groove, wherein the source region is connected with the second nitride semiconductor layer, and a conductivity type of the source region and the conductivity type of the second nitride semiconductor layer being same”
in combination with all other limitations in the claim as claimed and defined by applicant.
Claims 13–20 would be allowable at least because they depend on claim 12, which contains allowable subject matter as explained above, if claims 12 and 14–20 were amended to overcome the objections provided in this office action, and if claims 12–13 were amended to overcome the rejections under 35 USC § 112(b) provided in this office action. In such chase, withdrawn/nonelected claims 17–20 would be rejoined since they include all the limitations of an allowable claim (claim 12).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
Same inventor name (Kai Cheng) and applicant/assignee name (ENKRIS SEMICONDUCTOR, INC.) as the present application, and discloses somewhat similar vertical semiconductor devices as in the present application, but does not qualify as prior art under 35 USC § 102(a)(1) because published after filing date of present application, and does not qualify as prior art under 35 USC § 102(a)(2) because does not name another inventor (also, exception under 35 USC §102(b)(2)(C) would most likely apply):
US 2024/0120370 A1
US 2024/0079449 A1
Vertical semiconductor devices with drain electrode at the bottom and source and gate electrodes at the top, many of these devices having nitride semiconductor layers similar to the present application, but typically the gate is in a groove/trench, rather than the source region being in a groove/trench as required by claims 1 and 12 of the present application:
JP-2022115676-A: see FIG. 6
US 11,251,298 B2: see FIG. 1
US 12,262,547 B2: see FIG. 1
US 2020/0219980 A1: see FIG. 1
US 9,520,489 B2: see FIG. 1
US 2015/0243758 A1: see FIG. 5K
US 11,107,895 B2: see FIG. 2
JP-2015061065-A: see FIG. 1
KR-20140114646-A: see FIG. 2
US 2014/0191241 A1: see FIG. 5K
US 2013/0164893 A1: see FIG. 14
US 2013/0126885 A1: see FIG. 11
US 2013/0087879 A1: see FIG. 11
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Adam J Mott whose telephone number is (571)272-2367. The examiner can normally be reached Mon-Fri 8:30AM-5:00PM EST.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Eliseo Ramos Feliciano can be reached at (571) 272-7925. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/A.J.M./Examiner, Art Unit 2817
/RATISHA MEHTA/Primary Examiner, Art Unit 2817
1 See rejection under 35 USC § 112(b); here the “doping concentration” is understood to refer to a conductivity type.
Prosecution Insights