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 .
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)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(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.
Claims 1-3, 7-8, 10-13, and 16-19 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Eric Harley et al. (US 20160181285 A1; hereinafter Harley).
Regarding Claim 1, Harley discloses a device (Fig. 1A-5B) comprising:
a first fin (106; ¶0029) extending from a substrate (102/104; ¶0029);
a first gate stack (108; ¶0032) over and along sidewalls of the first fin (106) (as described in ¶0004);
a first gate spacer (110; ¶0032) disposed along a sidewall of the first gate stack (108);
a first source/drain region (402; ¶0040) in the first fin (106; as shown in Fig. 4B) and adjacent the first gate spacer (110), the first source/drain region (402) comprising:
a first carbon-containing buffer layer (302; ¶0039) on the first fin (106), the first carbon-containing buffer layer (302) having a first dopant concentration (¶0039); and
a first epitaxial structure (404/406/408; ¶0040, ¶0041, ¶0043) on the first carbon-containing buffer layer (302), the first epitaxial structure (404/406/408) having a second dopant concentration (¶0041) higher than the first dopant concentration (¶0039), the first carbon-containing buffer layer (302) being thicker at a bottom of the first source/drain region than at sides of the first source/drain region (as shown in Fig. 4B; ¶0038), and the first epitaxial structure (404/406/408) extending above an upper surface of the first fin (106) (as shown in Fig. 2B/4B).
Regarding Claim 2, Harley discloses the device of claim 1, wherein the first epitaxial structure (404/406/408) has a faceted top surface (using the broadest reasonable interpretation of “faceted top surface” which means a crystalline material split into distinct flat surfaces, in light of the lack of definition in the specification, the top surface of Harley’s epitaxial structure includes the top surface of 406/408 which has distinct different flat surfaces and is therefore faceted).
Regarding Claim 3, Harley discloses the device of claim 1, wherein the first carbon-containing buffer layer (302) comprises silicon arsenide doped with carbon (¶0039).
Regarding Claim 7, Harley discloses the device of claim 1, wherein the first epitaxial structure (404/406/408) contacts the first gate spacer (110) (Fig. 4B).
Regarding Claim 8, Harley discloses the device of claim 1, wherein the first epitaxial structure (404/406/408) comprises silicon, silicon carbide, phosphorous doped silicon carbide, or silicon phosphide. (as described in ¶0041-¶0042).
Regarding Claim 10, Harley discloses a device (Fig. 1A-5B) comprising:
a plurality of fins (plurality of 106; ¶0028-¶0029) extending from a substrate (102/104; ¶0029);
a plurality of gate stacks (plurality of 108; ¶0032) over and along sidewalls of the plurality of fins (as described in ¶0004);
gate spacers (110; ¶0032) disposed along sidewalls of the plurality of gate stacks (108);
source/drain regions (402; ¶0040) in the plurality of fins (106) and adjacent the gate spacers (110), each of the source/drain regions (402) comprising:
a carbon-containing buffer layer (302; ¶0039) on a respective fin (106) of the plurality of fins, the carbon-containing buffer layer (302) having a first dopant concentration (¶0039); and
an epitaxial structure (404/406/408; ¶0040, ¶0041, ¶0043) on the carbon-containing buffer layer (302), the epitaxial structure (404/406/408) having a second dopant concentration (¶0041) higher than the first dopant concentration (¶0039).
Regarding Claim 11, Harley discloses the device of claim 10, wherein the carbon-containing buffer layer (302) of each source/drain region (402) is thicker at a bottom than at sides of the respective source/drain region (as shown in Fig. 4B; ¶0038).
Regarding Claim 12, Harley discloses the device of claim 10, wherein the epitaxial structure (404/406/408) of each source/drain region has a faceted top surface (using the broadest reasonable interpretation of “faceted top surface” which means a crystalline material split into distinct flat surfaces, in light of the lack of definition in the specification, the top surface of Harley’s epitaxial structure includes the top surface of 406/408 which has distinct flat surfaces and is therefore faceted) and comprises multiple layers (404/406) with different dopant concentrations (as described in ¶0041).
Regarding Claim 13, Harley discloses the device of claim 10, wherein the carbon-containing buffer layer (302) of each source/drain region comprises silicon arsenide doped with carbon (¶0039).
Regarding Claim 16, Harley discloses the device of claim 10, wherein the epitaxial structures (404/406/408) of the source/drain regions contact the gate spacers (110) (Fig. 4B).
Regarding Claim 17, Harley discloses the device of claim 10, wherein the epitaxial structures (404/406/408) of the source/drain regions comprise silicon, silicon carbide, phosphorous doped silicon carbide, or silicon phosphide. (as described in ¶0041-¶0042).
Regarding Claim 18, a device (Fig. 1A-5B) comprising:
a first fin (106; ¶0029) and a second fin (other 106 as shown in Fig. 1A) extending from a substrate (102/104; ¶0029);
a first gate stack (108; ¶0032) over and along sidewalls of the first fin (106) (as described in ¶0004);
a second gate stack (other 108) over and along sidewalls of the second fin (other 106);
first gate spacers (110; ¶0032) disposed along sidewalls of the first gate stack (108);
second gate spacers (other 110) disposed along sidewalls of the second gate stack (other 108);
first source/drain regions (402; ¶0040) in the first fin (106) and adjacent the first gate spacers (110);
second source/drain regions (other 402) in the second fin (other 106) and adjacent the second gate spacers (other 110), wherein each of the first (402) and second (other 402) source/drain regions comprises:
a carbon-containing buffer layer (302; ¶0039) on the respective fin (106), the carbon-containing buffer layer (302) having a first dopant concentration (¶0039); and
an epitaxial structure (404/406/408; ¶0040, ¶0041, ¶0043) on the carbon-containing buffer layer (302), the epitaxial structure (404/406/408) having a second dopant concentration (¶0041) higher than the first dopant concentration (¶0039), wherein the epitaxial structure (404/406/408) extends above an upper surface of the respective fin (106) (as shown in Fig. 2B/4B; ¶0040).
Regarding Claim 19, Harley discloses the device of claim 18, wherein the carbon-containing buffer layers (302) of the first and second source/drain regions are thicker at bottoms than at sides of the respective source/drain regions (as shown in Fig. 4B; ¶0038).
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.
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Harley in view of Seok Hoon Kim et al. (US 20180138269 A1; hereinafter Kim).
Regarding Claim 4, Harley discloses the device of claim 1, but is silent regarding wherein the first carbon-containing buffer layer (302) has a weight percentage (wt %) of carbon in a range from 0.2 wt % to 2.0 wt %. Harley discloses the carbon concentration is “up to 4%” in ¶0038, but does not disclose if this is atomic percent or weight percent.
However, in the same FinFET field of endeavor, Kim teaches a method of making a FinFET with epitaxial source/drains (Kim; Abstract) which includes growing a carbon doped buffer layer (Kim; Fig. 2; 155; ¶0089) with a carbon doping range of 0.01% to 5% by weight (Kim; ¶0089) as a result effective variable to prevent dopant diffusion from the source/drain region into the channel.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to optimize the doping percentage of carbon of the disclosures to be within the claimed range in order to obtain the expected result of suppressing diffusion of the dopant from the source/drain into the channel region, as described in Kim ¶0089. Please refer to MPEP 2144.05 II A "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
Claims 5-6, 9, 14-15, and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Harley in view of Tzu-Ching Lin et al. (US 20200105606 A1; hereinafter Lin).
Regarding Claim 5, Harley discloses the device of claim 1.
Harley is silent regarding the source/drain contact features; further comprising:
an etch stop layer over the first source/drain region and on a sidewall of the first gate spacer; a first interlayer dielectric over the etch stop layer; a second interlayer dielectric over the first interlayer dielectric; and a first conductive contact extending through the first and second interlayer dielectrics and the etch stop layer, the first conductive contact being electrically coupled to the first source/drain region.
In the same field of endeavor, Lin teaches (Fig. 11A-14A) an etch stop layer (89; ¶0056) over a first source/drain region (80; ¶0012 comprising a buffer 80A and epitaxial structure 80B+80C) and on a sidewall of a first gate spacer (87; ¶0032); a first interlayer dielectric (90; ¶0057) over the etch stop layer (89); a second interlayer dielectric (92; ¶0065) over the first interlayer dielectric (90); and a first conductive contact (102B/95; ¶0068-¶0069) extending through the first and second interlayer dielectrics (90 and 92) and the etch stop layer (89), the first conductive contact being electrically coupled to the first source/drain region (80).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have the source/drain contact features of Lin in the device of Harley in order to make a functional device while improving contact resistance (Lin; ¶0067).
Regarding Claim 6, modified Harley teaches the device of claim 5, wherein the first conductive contact (as modified by Lin; 102B/95) physically contacts the first epitaxial structure (Lin; 80B/80C), and the first conductive contact is separated from the first carbon-containing buffer layer (302 equivalent to Lin 80A) by the first epitaxial structure (404/406/408 equivalent to Lin 80B/80C and as shown in Lin Fig. 14A).
Regarding Claim 9, Harley discloses the device of claim 1, but is silent regarding this thickness of the buffer layer:
wherein a thickness of the first carbon-containing buffer layer at the sides of the first source/drain region is in a range from 1 nm to 6 nm.
In the same field of endeavor, Lin teaches a first buffer layer (Fig. 14A; 80A) lining a trench in a fin (64; ¶0012) with an epitaxial structure (80B/80C; ¶0041-¶0043) thereon in the same manner as Harley, wherein the first layer (80A) is thicker at a bottom than on sidewalls, with a thickness at the sides is in a range of 1nm-5nm (¶0037). Lin also discloses in ¶0038 that the process conditions of the epitaxy process can be adjusted accordingly to control the profile of 80A.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have the thickness range of Lin for the buffer layer in the device of Harley because of its art-recognized suitability for the intended purpose of lining a source/drain feature between a fin and an epitaxial structure, and/or to adjust the result-effective epitaxy conditions to achieve the desired profile.
Regarding Claim 14, Harley discloses the device of claim 10, but is silent regarding further comprising:
an etch stop layer over the source/drain regions and on sidewalls of the gate spacers; a first interlayer dielectric over the etch stop layer; a second interlayer dielectric over the first interlayer dielectric; and conductive contacts extending through the first and second interlayer dielectrics and the etch stop layer, the conductive contacts being electrically coupled to the source/drain regions.
In the same field of endeavor, Lin teaches (Fig. 11A-14A) an etch stop layer (89; ¶0056) over source/drain regions (80; ¶0012 comprising a buffer 80A and epitaxial structure 80B+80C) and on sidewalls gate spacers (87; ¶0032); a first interlayer dielectric (90; ¶0057) over the etch stop layer (89); a second interlayer dielectric (92; ¶0065) over the first interlayer dielectric (90); and conductive contacts (102B/95; ¶0068-¶0069) extending through the first and second interlayer dielectrics (90 and 92) and the etch stop layer (89), the conductive contacts being electrically coupled to the source/drain regions (80).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have the source/drain contact features of Lin in the device of Harley in order to make a functional device while improving contact resistance (Lin; ¶0067).
Regarding Claim 15, modified Harley teaches the device of claim 14, wherein the conductive contacts (as modified by Lin; 102B/95) physically contact the epitaxial structures (Lin; 80B/80C) of the source/drain regions, and the conductive contacts are separated from the carbon-containing buffer layers (302 equivalent to Lin 80A) by the epitaxial structures (404/406/408 equivalent to Lin 80B/80C and as shown in Lin Fig. 14A).
Regarding Claim 20, Harley discloses the device of claim 18, but is silent regarding further comprising:
an etch stop layer over the first and second source/drain regions and on sidewalls of the first and second gate spacers; a first interlayer dielectric over the etch stop layer; a second interlayer dielectric over the first interlayer dielectric; and conductive contacts extending through the first and second interlayer dielectrics and the etch stop layer, the conductive contacts being electrically coupled to the first and second source/drain regions, wherein the conductive contacts physically contact the epitaxial structures of the first and second source/drain regions and are separated from the carbon-containing buffer layers by the epitaxial structures.
In the same field of endeavor, Lin teaches (Fig. 11A-14A) an etch stop layer (89; ¶0056) over source/drain regions (80; ¶0012 comprising a buffer 80A and epitaxial structure 80B+80C) and on sidewalls gate spacers (87; ¶0032); a first interlayer dielectric (90; ¶0057) over the etch stop layer (89); a second interlayer dielectric (92; ¶0065) over the first interlayer dielectric (90); and conductive contacts (102B/95; ¶0068-¶0069) extending through the first and second interlayer dielectrics (90 and 92) and the etch stop layer (89), the conductive contacts being electrically coupled to the source/drain regions (80), wherein the conductive contacts (102B/95) physically contact the epitaxial structures (80B+80C) of the first and second source/drain regions and are separated from the buffer layers (80A) by the epitaxial structures.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have the source/drain contact features of Lin in the device of Harley in order to make a functional device while improving contact resistance (Lin; ¶0067).
Conclusion
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NATHAN PRIDEMORE
Examiner
Art Unit 2898
/NATHAN PRIDEMORE/Examiner, Art Unit 2898 /JULIO J MALDONADO/Supervisory Patent Examiner, Art Unit 2898
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