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 .
Claim Objections
Claim 2 is objected to because of the following informalities: “S?D”. For the purpose of examination, it is considered as “S/D”. Appropriate correction is required.
Double Patenting
1. Claims 1-2,5-7 rejected on the ground of nonstatutory double patenting as being unpatentable over claim 1 of U.S. Patent No. 11222951 B2 (‘951 from hereon) in view of US 20130288439 A1 (Xia) and US 20200043793 A1 (Huang).
Although the claims at issue are not identical, they are not patentably distinct from each other because of the following:
Instant application ‘804
‘951
1. A method of semiconductor fabrication, comprising:
forming a first epitaxial source/drain (S/D) feature of a first type over a first active region;
forming a second epitaxial S/D feature of a second type over a second active region;
performing an etching process to form a first recess in the first epitaxial S/D feature and a second recess in the second epitaxial S/D feature, wherein the etching process concurrently forms the first recess and the second recess, and wherein the first recess is of a greater depth than the second recess; and
forming a first contact in the first recess and a second contact in the second recess.
2. The method of claim 1, wherein the first epitaxial S/D feature of the first type is an n-type material.
5. The method of claim 1, wherein the performing the etching process includes:
introducing a first etchant gas;
reacting the first etchant gas with the first epitaxial S/D feature, wherein the reacting removes a first thickness of the first epitaxial S/D feature;
reacting the first etchant gas with the second epitaxial S/D feature, wherein the reacting removes a second thickness of the second epitaxial S/D feature, the second thickness less than the first thickness; and
introducing a second etchant gas after completing the introducing the first etchant gas.
6. The method of claim 5, wherein the introducing the first etchant gas introduces fluoromethane (CH3F), hydrogen (H2), and carbonyl sulfide (COS).
7. The method of claim 6, wherein the introducing the second etchant gas includes diazene (N2H2).
1. A method of semiconductor fabrication, comprising: providing a semiconductor structure having: a substrate; and first, second, third, and fourth fins above the substrate;
forming an n-type epitaxial source/drain (S/D) feature on the first and second fins; and
forming a p-type epitaxial S/D feature on the third and fourth fins; and
performing a selective etch process on the semiconductor structure to
remove upper portions of the n-type epitaxial S/D feature and the p-type epitaxial S/D feature such that more is removed from the n-type epitaxial S/D feature than the p-type epitaxial S/D feature.
(Shown below)
(In claim 1).
2. The method of claim 1, wherein the selective etch process includes a plurality of cycles, wherein each cycle comprises: performing a first dry etch process on the semiconductor structure using a first etchant gas; performing a second dry etch process on the semiconductor structure using a second etchant gas different from the first etchant gas; and performing a wet clean process to remove a polymer layer that has been formed in the first dry etch process.
3. The method of claim 2, wherein the first etchant gas is a gas mixture that includes fluoromethane (CH.sub.3F), hydrogen (H.sub.2), and carbonyl sulfide (COS), wherein the gas mixture reacts with silicon germanium in the p-type epitaxial S/D feature in the first dry etch process, thereby forming the polymer layer that includes silicon sulfide.
4. The method of claim 3, wherein the first dry etch process removes a first thickness of the n-type epitaxial S/D feature, wherein the first dry etch process removes a second thickness of the p-type epitaxial S/D feature that is less than the first thickness due to presence of the polymer layer on the p-type epitaxial S/D feature, and wherein the first dry etch process also forms carbon fluoride (C.sub.xF.sub.y) as a byproduct on both the n-type epitaxial S/D feature and the p-type epitaxial S/D feature.
5. The method of claim 4, wherein the second etchant gas includes diazene (N.sub.2H.sub.2) configured to remove the carbon fluoride formed in the first dry etch process.
Regarding claim 1, ‘951 does not show wherein the etching process concurrently forms the first recess and the second recess;
forming a first contact in the first recess and a second contact in the second recess.
Xia shows wherein the etching process concurrently forms the first recess and the second recess (claim 16 teaches the etching of first and second S/D recesses concurrently).
It would have been obvious to one of ordinary skill in the art, at or before the effective filing date of the invention was made, to modify the invention of ‘951, including etching of S/D, with the invention of Xia.
The motivation to do so is that the combination produces faster process of manufacturing.
‘951 in combination with Xia does not show forming a first contact in the first recess and a second contact in the second recess.
Huang shows (Fig. 10A) forming a first contact in the first recess (recess for 60 on top, para 46) and a second contact in the second recess (60 for middle).
It would have been obvious to one of ordinary skill in the art, at or before the effective filing date of the invention was made, to add the invention of Huang, with contacts in recesses, to the invention of ‘951 in combination with Xia.
The motivation to do so is that the selection of an art recognized recesses for contacts by Huang is suitable for the intended use of ‘951 in combination with Xia (MPEP §2144.07).
2. Claims 3-4 are rejected on the ground of nonstatutory double patenting as being unpatentable over ‘951 in view of Xia and Huang as applied to claim 1 above further in view of US 20180175046 A1 (Chiou).
Regarding claim 3, ‘951 in view of Xia and Huang shows the substrate.
‘951 in view of Xia and Huang does not show forming the first active region includes forming a first fin and a second fin extending from a substrate.
Chiou shows (Fig. 3E) forming the first active region includes forming a first fin (222B, para 31) and a second fin (222C, para 27) extending from a substrate (210, para 21).
It would have been obvious to one of ordinary skill in the art, at or before the effective filing date of the invention was made, to add the invention of Chiou, with active areas from fins of Chiou, to the invention of ‘951 in view of Xia and Huang.
The motivation to do so is that the selection of an art recognized active areas from fins by Chiou is suitable for the intended use of ‘951 in view of Xia and Huang (MPEP §2144.07).
Regarding claim 4, Chiou shows (Fig. 3E) wherein the forming the first epitaxial S/D feature includes forming the first epitaxial S/D feature (255B, para 33) extending between the first fin and the second fin.
Allowable Subject Matter
Claims 8-9 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.
Regarding claim 8, the prior art of record, either singularly or in combination, does not disclose or suggest the combination of limitations including “wherein the second thickness is approximately zero”.
Regarding claim 9, the prior art of record, either singularly or in combination, does not disclose or suggest the combination of limitations including “wherein the reacting the first etchant gas with the second epitaxial S/D feature forms a polymer layer on the second epitaxial S/D feature”.
Claims 10-20 are allowed.
Regarding claim 10, the prior art of record, either singularly or in combination, does not disclose or suggest the combination of limitations including “form a first recess and a second recess respectively, wherein the second recess is of greater depth than the first recess” when taken in combination with all the remaining limitations of the independent claim.
Regarding claim 15, the prior art of record, either singularly or in combination, does not disclose or suggest the combination of limitations including “wherein the etching process includes: a first etching step including introducing a first gas, forming a first layer from an interaction of the first gas on the second feature, and removing a first thickness of the first S/D feature” when taken in combination with all the remaining limitations of the independent claim.
Conclusion
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/WASIUL HAIDER/Primary Examiner, Art Unit 2812
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