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 .
IDS
The IDS document(s) filed on 11/21/2023 have been considered. Copies of the PTO-1449 documents are herewith enclosed with this office action.
Claim Objections
Claim 8 is objected to because of the following informalities: The last line of claim 8 recites “thrid portion” (emphasis added) but should recite “third portion”. Appropriate correction is required.
Claim Rejections - 35 U.S.C. § 112(b)
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 11-13 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.
As to claim 11, it is unclear what is meant by “the plurality of flushes is greater than a number of flushes with the first etching gas” (emphasis added).
Double Patenting
The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the “right to exclude” granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the conflicting claims are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969).
A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on nonstatutory double patenting provided the reference application or patent either is shown to be commonly owned with the examined application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. See MPEP § 717.02 for applications subject to examination under the first inventor to file provisions of the AIA as explained in MPEP § 2159. See MPEP § 2146 et seq. for applications not subject to examination under the first inventor to file provisions of the AIA . A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b).
The filing of a terminal disclaimer by itself is not a complete reply to a nonstatutory double patenting (NSDP) rejection. A complete reply requires that the terminal disclaimer be accompanied by a reply requesting reconsideration of the prior Office action. Even where the NSDP rejection is provisional the reply must be complete. See MPEP § 804, subsection I.B.1. For a reply to a non-final Office action, see 37 CFR 1.111(a). For a reply to final Office action, see 37 CFR 1.113(c). A request for reconsideration while not provided for in 37 CFR 1.113(c) may be filed after final for consideration. See MPEP §§ 706.07(e) and 714.13.
The USPTO Internet website contains terminal disclaimer forms which may be used. Please visit www.uspto.gov/patent/patents-forms. The actual filing date of the application in which the form is filed determines what form (e.g., PTO/SB/25, PTO/SB/26, PTO/AIA /25, or PTO/AIA /26) should be used. A web-based eTerminal Disclaimer may be filled out completely online using web-screens. An eTerminal Disclaimer that meets all requirements is auto-processed and approved immediately upon submission. For more information about eTerminal Disclaimers, refer to www.uspto.gov/patents/apply/applying-online/eterminal-disclaimer.
Claims 1-20 are rejected on the ground of nonstatutory double patenting as being unpatentable over claims 1-20 of U.S. Patent No. 11854831 B2 in view of Lee et a. (US 9548303), hereafter “Lee”. Although the claims at issue are not identical, they are not patentably distinct from each other as demonstrated in the table below:
Application # 18516431
Patent # US 11854831 B2
Claim 1 - A method, comprising:
cleaning a substrate with a plasma;
depositing, on the substrate, an epitaxial layer comprising:
epitaxially growing a first portion of the epitaxial layer with a precursor;
cleaning the substrate with a flush of a first etching gas; and
epitaxially growing a second portion of the epitaxial layer with the precursor,
wherein the first portion and the second portion have a same composition; and
etching a portion of the epitaxial layer with a second etching gas.
Claim 1 - A method of forming an epitaxial layer on a substrate in a chamber, comprising:
cleaning the chamber with a first etching gas;
depositing, on the substrate, the epitaxial layer comprising:
epitaxially growing a first portion of the epitaxial layer with a precursor;
cleaning the substrate and the chamber with a flush of a second etching gas different from the first etching gas; and
epitaxially growing a second portion of the epitaxial layer with the precursor,
wherein the first portion and the second portion have a same composition; and
etching a portion of the epitaxial layer with a third etching gas having a flow rate higher than that of the second etching gas.
Claim 9 - A method, comprising:
depositing, in a chamber, a first epitaxial layer on a substrate, wherein the depositing the first epitaxial layer comprises:
epitaxially growing a first portion of the first epitaxial layer on the substrate with a precursor;
cleaning the substrate and the chamber with a first etching gas; and
epitaxially growing a second portion of the first epitaxial layer with the precursor,
wherein the first portion and the second portion have a same composition;
etching a portion of the first epitaxial layer with a second etching gas; and
depositing, on the first epitaxial layer, a second epitaxial layer.
Claim 9 - A method, comprising:
depositing, on a substrate in a chamber, a first epitaxial layer comprising:
epitaxially growing a first portion of the first epitaxial layer with a precursor;
cleaning the substrate and the chamber with a first etching gas; and
epitaxially growing a second portion of the first epitaxial layer with the precursor,
wherein the first portion and the second portion have a same composition;
etching a portion of the first epitaxial layer with a second etching gas, wherein a flow rate of the second etching gas is higher than a flow rate of the first etching gas; and
depositing, on the first epitaxial layer, a second epitaxial layer with a different composition from the first epitaxial layer.
Claim 16 - A method, comprising:
forming a first fin structure and a second fin structure on a substrate;
etching a portion of the first and second fin structures;
epitaxially growing a first portion of a first epitaxial layer on the etched first and second fin structures with a precursor;
cleaning the substrate with a first etching gas;
epitaxially growing a second portion of the first epitaxial layer with the precursor, wherein the first and second portions have a same composition; and
etching a third portion of the first epitaxial layer with a second etching gas, wherein a flow rate of the second etching gas is higher than a flow rate of the first etching gas.
Claim 16 - A method, comprising:
forming a first fin structure and a second fin structure on a substrate;
etching a portion of the first and second fin structures; and
forming a source/drain (S/D) epitaxial structure on the etched first and second fin structures, wherein the forming the S/D epitaxial structure comprises:
epitaxially growing a first portion of a first epitaxial layer in a chamber with a precursor;
cleaning the substrate and the chamber with a first etching gas;
epitaxially growing a second portion of the first epitaxial layer with the precursor, wherein the first and second portions have a same composition; and
etching a third portion of the first epitaxial layer with a second etching gas, wherein a flow rate of the second etching gas is higher than a flow rate of the first etching gas.
Claims 2-20 of the instant application correspond to claims 2-20 of the patent.
For claim 1 of the instant application, it would have been obvious to one of ordinary skill in the art to apply the use of cleaning a substrate with plasma as taught by Lee into the process of Chiou to remove native oxide and ensure good quality (Col. 6, Lines 59-65).
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 16-17 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Chiou et al. (US 2018/0175046), hereafter “Chiou”.
As to claim 16, Chiou teaches a method, comprising:
forming a first fin structure and a second fin structure (222A, Fig. 3A, ⁋ [0023]) on a substrate (210, Fig. 3A, ⁋ [0021]);
etching a portion of the first and second fin structures (Fig. 3C, ⁋ [0030]);
epitaxially growing a first portion (see annotated Fig. 3D below) of a first epitaxial layer on the etched first and second fin structures with a precursor (⁋ [0031], “The SEG process uses gaseous precursors…”);
cleaning the substrate with a first etching gas (⁋⁋ [0017], [0033], “cyclic deposition etch”);
epitaxially growing a second portion (see annotated Fig. 3D) of the first epitaxial layer with the precursor (⁋ [0031], “The SEG process uses gaseous precursors…”), wherein the first and second portions have a same composition (both are within 255A); and
etching a third portion of the first epitaxial layer with a second etching gas (⁋ [0035]), wherein a flow rate of the second etching gas (⁋ [0035, “100 sccm to about 1,000 sccm”) is higher than a flow rate of the first etching gas (⁋ [0033], “20 sccm to about 100 sccm”).
As to claim 17, Chiou teaches the method of claim 16, further comprising epitaxially growing, on the first epitaxial layer, a second epitaxial layer (265A, Fig. 3F, ⁋ [0038]) having a different composition from the first epitaxial layer (⁋ [0038], “in situ doped”).
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Claim Rejections - 35 U.S.C. § 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.
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.
Claims 1, 3 and 8 are rejected under 35 U.S.C. 103 as being unpatentable over Chiou, and further in view of Lee.
As to claim 1, Chiou teaches a method, comprising:
cleaning a substrate (210, Fig. 3A, ⁋ [0021]);
depositing, on the substrate, an epitaxial layer (255A, Fig. 3D, ⁋ [0031]) comprising:
epitaxially growing a first portion (see annotated Fig. 3D) of the epitaxial layer with a precursor (⁋ [0031], “The SEG process uses gaseous precursors…”);
cleaning the substrate with a flush of a first etching gas (⁋⁋ [0017], [0033]); and
epitaxially growing a second portion (see annotated Fig. 3D) of the epitaxial layer with the precursor (⁋ [0031], “The SEG process uses gaseous precursors…”),
wherein the first portion and the second portion have a same composition (both are within 255A); and
etching a portion of the epitaxial layer with a second etching gas (⁋ [0035]).
Chiou fails to teach cleaning a substrate with a plasma.
Lee teaches a similar cleaning process where the substrate is cleaned with a plasma (330, Fig. 13, Col. 7, Lines 3-8).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the use of plasma as taught by Lee into the process of Chiou to remove native oxide and ensure good quality (Col. 6, Lines 59-65).
As to claim 3, Chiou in view of Lee teaches the method of claim 1, Chiou further teaches wherein the first etching gas comprises hydrogen chloride (HCl) (⁋ [0033]).
As to claim 8, Chiou in view of Lee teaches the method of claim 1, further comprising:
cleaning the substrate with an additional flush of the first etching gas after epitaxially growing a second portion of the epitaxial layer (⁋⁋ [0017], [0033], etchant gas is being flowed in while the epitaxial layer is growing and would still be flowing after the second portion is grown); and
epitaxially growing a third portion (see annotated Fig. 3D) of the epitaxial layer with the precursor (⁋ [0031], “The SEG process uses gaseous precursors…”), wherein the third portion and the second portion have a same composition (also within 255A).
Claims 2 and 4 are rejected under 35 U.S.C. 103 as being unpatentable over Chiou in view of Lee, as applied to claim 1, and further in view of Kim (US 7588980), hereafter “Kim ‘980”.
As to claim 2, Chiou in view of Lee teach the method of claim 1, Chiou teaches a time for the etching the epitaxial layer with the second etching gas (⁋ [0035], “20 seconds to about 50 seconds”) but does not explicitly teach wherein the etching the portion of the epitaxial layer comprises etching the epitaxial layer with the second etching gas for a time greater than a time of cleaning the substrate with the first etching gas.
Kim ‘980 teaches a method of forming an epitaxial layer on a substrate wherein HCl and/or Cl2 (same material used by Chiou) is flowed into a process chamber (Col. 4, Lines 66-67) for about 5 to 10 seconds (Col. 5, Lines 3-5).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of the time taught by Kim ‘980 into the process of Chiou and Lee as they both teach the same materials being utilized for the same function therefore it would have been obvious to use the time for its intended purpose.
As a result of the combination, the time of etching the epitaxial layer with the second etching gas (Chiou; 20-50 seconds) is greater than a time of cleaning the substrate with the first etching gas (Kim ‘980; 5-10 seconds).
As to claim 4, Chiou in view of Lee fails to teach the method of claim 1, wherein a time of cleaning the substrate with the first etching gas ranges from about 3 seconds to about 10 seconds.
Kim ‘980 teaches a method of forming an epitaxial layer on a substrate wherein HCl and/or Cl2 (same material used by Chiou) is flowed into a process chamber (Col. 4, Lines 66-67) for about 5 to 10 seconds (Col. 5, Lines 3-5).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of the time taught by Kim ‘980 into the process of Chiou and Lee as they both teach the same materials being utilized for the same function therefore it would have been obvious to use the time for its intended purpose.
Additionally, the Examiner notes Applicant has not specified a criticality to the range.
Where patentability is said to be based upon particular chosen dimensions or upon another variable recited in a claim, the applicant must show that the chosen dimensions or variable are critical. "The law is replete with cases in which the difference between the claimed invention and the prior art is some range or other variable within the claims. . . . In such a situation, the applicant must show that the particular range is critical, generally by showing that the claimed range achieves unexpected results relative to the prior art range." In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou in view of Lee, as applied to claim 1, and further in view of Murphy et al. (2011/0147828), hereafter “Murthy”.
As to claim 5, Chiou in view of Lee teaches the method of claim 1, but fails to teach further comprising, prior to depositing the epitaxial layer, baking the substrate in a hydrogen environment at a temperature ranging from about 800 0C to about 850 °C.
Murthy teaches a similar epitaxial growth process baking the substrate prior to depositing the epitaxial layer in a hydrogen environment at a temperature ranging from about 700 °C to about 1050 °C (⁋ [0048]).
It would have been obvious to one of ordinary skill in the art before the effective filing date to include the hydrogen bake treatment as taught by Murthy into the epitaxial growth process as taught by Chiou and Lee in order to clean the recessed source and drain interfaces, desorb oxygen and render surface reconstruction so that the epitaxial films can readily nucleate without formation of defects (⁋ [0048]).
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou in view of Lee, as applied to claim 1, and further in view of Hahn et al. (US 6500719), hereafter “Hahn”.
As to claim 6, Chiou in view of Lee teach the method of claim 1, but fail to teach further comprising, after depositing the epitaxial layer, heating the substrate with the epitaxial layer in a hydrogen environment at a temperature ranging from about 800 °C to about 850 °C.
Hahn teaches a method in a similar field of endeavor in which after depositing an epitaxial layer (85, Fig. 8C, Col. 57-60) a hydrogen bake occurs at a temperature ranging from 750 to 850 °C (Col. 6, Lines 24-25).
It would have been obvious to one of ordinary skill in the art before the effective filing date to include the hydrogen bake treatment as taught by Hahn into the epitaxial growth process as taught by Chiou and Lee for the purpose of removing any oxide and grow the next epitaxial layer (Col. 6, Lines 22-24).
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou in view of Lee, as applied to claim 1, and further in view of Ching et al. (US 20160308048), hereafter “Ching”.
As to claim 7, Chiou in view of Lee teach the method of claim 1, but fail to teach further comprising coating the substrate with a semiconductor seed layer comprising silicon prior to depositing the epitaxial layer, wherein the semiconductor seed layer has a composition different from that of the epitaxial layer.
Ching teaches a similar epitaxial growth process where an epitaxial seed layer (70, Fig. 12, ⁋ [0037]) comprising silicon and may be doped or undoped (⁋ [0038]), is formed over a substrate prior to depositing the epitaxial layer (80, Fig. 16, ⁋ [0041]).
It would have been obvious to one of ordinary skill in the art before the effective filing date to include the seed layer taught by Ching into the epitaxial growth process as taught by Chiou and Lee in order to enhance the epitaxial growth of the Si based material (⁋ [0042]).
Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou, and further in view of Kim et al. (US 2016/0293750), hereafter “Kim”.
As to claim 9, Chiou teaches a method, comprising:
depositing, a first epitaxial layer on a substrate (210, Fig. 3A, ⁋ [0021]), wherein the depositing the first epitaxial layer comprises:
epitaxially growing a first portion of the first epitaxial layer (see annotated Fig. 3D) on the substrate with a precursor (⁋ [0031], “The SEG process uses gaseous precursors…”);;
cleaning the substrate and the chamber with a first etching gas (⁋⁋ [0017], [0033], “cyclic deposition etch”); and
epitaxially growing a second portion (see annotated Fig. 3D) of the first epitaxial layer with the precursor (⁋ [0031], “The SEG process uses gaseous precursors…”),
wherein the first portion and the second portion have a same composition (both are within 255A);
etching a portion of the first epitaxial layer with a second etching gas (⁋ [0035]); and
depositing, on the first epitaxial layer, a second epitaxial layer (265A, Fig. 3F, ⁋ [0038]).
Chiou fails to teach depositing a first epitaxial layer in a chamber.
Kim teaches a similar epitaxial growth process where an epitaxial growth layer is deposited on a substrate in a chamber (⁋⁋ [0101-0102].
It would have been obvious to one of ordinary skill in the art before the effective filing date to include the deposition of an epitaxial layer on a substrate in a chamber taught by Kim with the epitaxial growth process taught by Hsu in order to work within a controlled environment and decrease any unwanted possible defects during the growth process.
Claim 10 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou in view of Kim, as applied to claim 9, and further in view of Kim ‘980.
As to claim 10, Chiou in view of Kim teach the method of claim 9, Chiou teaches a time for the etching the epitaxial layer with the second etching gas (⁋ [0035], “20 seconds to about 50 seconds”) but fails to teach wherein the etching the portion of the first epitaxial layer comprises etching the first epitaxial layer with the second etching gas for a time greater than a time of cleaning the substrate and the chamber with the first etching gas.
Kim ‘980 teaches a method of forming an epitaxial layer on a substrate wherein HCl and/or Cl2 (same material used by Chiou) is flowed into a process chamber (Col. 4, Lines 66-67) for about 5 to 10 seconds (Col. 5, Lines 3-5).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of the time taught by Kim ‘980 into the process of Chiou and Kim as they both teach the same materials being utilized for the same function therefore it would have been obvious to use the time for its intended purpose.
As a result of the combination, the time of etching the epitaxial layer with the second etching gas (Chiou; 20-50 seconds) is greater than a time of cleaning the substrate and the chamber with the first etching gas (Kim ‘980; 5-10 seconds).
Claim 14 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou in view of Kim, as applied to claim 9, and further in view of Chang et al. (US 10515951), hereafter “Chang”.
As to claim 14, Chiou in view of Kim teach the method of claim 9, Chiou teaches a flow rate of the first etching gas (⁋ [0033], “20 sccm to about 100 sccm”), and a time of etching the first epitaxial layer with the second etching gas (⁋ [0035], “20 seconds to about 50 seconds”).
Chiou in view of Kim fails to teach further comprising etching the second epitaxial layer with a third etching gas comprising a silicon-based precursor, wherein a flow rate of the third etching gas is higher than a flow rate of the first etching gas and a time of etching the second epitaxial layer with the third etching gas is substantially equal to a time of etching the first epitaxial layer with the second etching gas.
Chang taches a similar epitaxial growth process where a selective etching process is implemented, wherein an epitaxial layer (201, Fig. 2E, Col. 11, Lines 3-5) is etched by an etchant containing a silicon-based precursor (SiH4, Col. 11, Lines 29-34)) with a flow rate of between about 0.1 sccm and about 100000 sccm, such as about 1000 sccm (Col. 11, Lines 38-41), and the etching time with the third etching gas is less than 1 to 100 sec (Col. 11, Lines 60-63, “about 1 nm/sec and about 100 nm/sec”; Col. 12, Line 21 “about 20 nm and about 2000 nm”). Examiner notes Chang doesn’t explicitly teach a time for the etching but does give an etching rate along with a width of the original source/drain region W2 shown in Fig. 2E, from which an etching time can be calculated, and indicates the final structure shown in Fig. 3B has a width W3 has a smaller width (Col. 12, Line 20).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of etching the epitaxial layer taught by Chang into the epitaxial growth process as taught by Chiou and Kim for the benefit of modifying the shape of the merged source/drain regions (Col. 11, Lines 5-8). Additionally larger sized source/drain region can be provided which further allows for a reduction in the resistance of the channel and the parasitic resistance, allowing for a device boost (Col. 12, Lines 51-54).
As a result of the combination of Chiou in view of Kim and Chang, the limitations of claim 14 are taught.
Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou in view of Kim, as applied to claim 9, in view of Hsu et al. (2020/0105888), hereafter “Hsu”, in view of Iwata et al. (2019/0296012), hereafter “Iwata”, in view of Chang, and further in view of Hahn.
As to claim 15, Chiou in view of Kim teaches the method of claim 9, but fails to teach further comprising:
depositing a third epitaxial layer on the second epitaxial layer, wherein the depositing the third epitaxial layer comprises cleaning the substrate and the chamber with the first etching gas;
etching the third epitaxial layer with a third etching gas comprising a silicon-based precursor;
depositing a fourth epitaxial layer on the third epitaxial layer, wherein the depositing the fourth epitaxial layer comprises cleaning the substrate and the chamber with the first etching gas;
etching the fourth epitaxial layer with a fourth etching gas comprising a germanium- based precursor; and
heating the first, second, third, and fourth epitaxial layers in a hydrogen environment at a temperature ranging from about 800 0C to about 850 °C.
Hsu teaches a method in a similar field of endeavor in which an additional epitaxial layer (66, Fig. 7, ⁋ [0044]) is formed over another epitaxial layer.
It would have been obvious to one of ordinary skill in the art before the effective filing date to add an additional epitaxial layer as taught by Hsu into the epitaxial growth process as taught by Chiou and Kim for the purpose of increased volume which can improve device performance by providing a larger volume of the source/drain region.
Chiou in view of Kim and Hsu fail to teach wherein the depositing the third epitaxial layer comprises:
cleaning the substrate and the chamber with the first etching gas;
etching the third epitaxial layer with a third etching gas comprising a silicon-based precursor;
wherein the depositing the fourth epitaxial layer comprises cleaning the substrate and the chamber with the first etching gas;
etching the fourth epitaxial layer with a fourth etching gas comprising a germanium- based precursor; and
heating the first, second, third, and fourth epitaxial layers in a hydrogen environment at a temperature ranging from about 800 0C to about 850 °C.
Iwata teaches a device in a similar field of endeavor, wherein an etching gas (HCl) is “simultaneously or concurrently flowed into a process chamber” (⁋ [0132]) for cleaning.
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of flowing the HCl gas into the chamber as taught by Iwata within the process of Chiou, Kim and Hsu so the etchant may timely remove any residual semiconductor material that nucleates on dielectric surfaces to prevent growth of the semiconductor material from the dielectric surfaces, while the at least one reactant gas provides a greater deposition rate for the semiconductor material than the etch rate that the etchant provides for the semiconductor material (⁋ [0032]).
Chiou in view of Kim, Hsu, and Iwata fail to teach wherein the depositing the third epitaxial layer comprises:
etching the third epitaxial layer with a third etching gas comprising a silicon-based precursor;
etching the fourth epitaxial layer with a fourth etching gas comprising a germanium- based precursor; and
heating the first, second, third, and fourth epitaxial layers in a hydrogen environment at a temperature ranging from about 800 0C to about 850 °C.
Chang taches a similar epitaxial growth process where a selective etching process is implemented, wherein an epitaxial layer (201, Fig. 2E, Col. 11, Lines 3-5) is etched by an etchant containing a silicon-based precursor (SiH4, Col. 11, Lines 29-34)) and alternatively a germanium-based precursor (GeH.sub.4, Col. 11, Lines 34-36).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of etching the epitaxial layer taught by Chang into the epitaxial growth process as taught by Chiou, Kim, Hsu and Iwata for the benefit of modifying the shape of the merged source/drain regions (Col. 11, Lines 5-8). Additionally larger sized source/drain region can be provided which further allows for a reduction in the resistance of the channel and the parasitic resistance, allowing for a device boost (Col. 12, Lines 51-54).
Chiou in view of Kim, Hsu, Iwata, and Chang fail to teach wherein the depositing the third epitaxial layer comprises:
heating the first, second, third, and fourth epitaxial layers in a hydrogen environment at a temperature ranging from about 800 0C to about 850 °C.
Hahn teaches a method in a similar field of endeavor in which after depositing an epitaxial layer (85, Fig. 8C, Col. 57-60) a hydrogen bake occurs at a temperature ranging from 750 to 850 °C (Col. 6, Lines 24-25).
It would have been obvious to one of ordinary skill in the art before the effective filing date to include the hydrogen bake treatment as taught by Hahn into the epitaxial growth process as taught by Chiou, Kim, Hsu, Iwata and Chang for the purpose of removing any oxide and grow the next epitaxial layer (Col. 6, Lines 22-24).
Claim 19 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou, as applied to claim 16, and further in view of Chang.
As to claim 19, Chiou teaches the method of claim 17, but fails to teach further comprising etching the second epitaxial layer with a third etching gas comprising a silicon-based precursor.
Chang taches a similar epitaxial growth process where a selective etching process is implemented, wherein an epitaxial layer (201, Fig. 2E, Col. 11, Lines 3-5) is etched by an etchant containing a silicon-based precursor (SiH4, Col. 11, Lines 29-34)).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of etching the epitaxial layer taught by Chang into the epitaxial growth process as taught by Chiou for the benefit of modifying the shape of the merged source/drain regions (Col. 11, Lines 5-8). Additionally larger sized source/drain region can be provided which further allows for a reduction in the resistance of the channel and the parasitic resistance, allowing for a device boost (Col. 12, Lines 51-54).
Claim 20 is rejected under 35 U.S.C. 103 as being unpatentable over Chiou, as applied to claim 16, and further in view of Kim ‘980.
As to claim 20, Chiou teaches the method of claim 16, wherein the first etching gas comprises hydrogen chloride (HCl) (⁋ [0033]), but fails to teach wherein a time of cleaning the substrate with the first etching gas ranges from about 3s to about 10s.
Kim ‘980 teaches a method of forming an epitaxial layer on a substrate wherein HCl and/or Cl2 (same material used by Chiou) is flowed into a process chamber (Col. 4, Lines 66-67) for about 5 to 10 seconds (Col. 5, Lines 3-5).
It would have been obvious to one of ordinary skill in the art before the effective filing date to apply the teaching of the time taught by Kim ‘980 into the process of Chiou as they both teach the same materials being utilized for the same function therefore it would have been obvious to use the time for its intended purpose.
Additionally, the Examiner notes Applicant has not specified a criticality to the range.
Where patentability is said to be based upon particular chosen dimensions or upon another variable recited in a claim, the applicant must show that the chosen dimensions or variable are critical. "The law is replete with cases in which the difference between the claimed invention and the prior art is some range or other variable within the claims. . . . In such a situation, the applicant must show that the particular range is critical, generally by showing that the claimed range achieves unexpected results relative to the prior art range." In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Allowable Subject Matter
Claim 18 is 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.
As to claim 11, Chiou is the closest prior art and fails to teach wherein the epitaxially growing the second epitaxial layer comprises cleaning the substrate with a plurality of flushes of the first etching gas, and wherein an interval between each of the plurality of flushes of the first etching gas ranges from about 30 s to about 50 s.
Claims 11-13 would be allowable if rewritten to overcome the rejection(s) under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action and to include all of the limitations of the base claim and any intervening claims.
As to claim 11 (from which 12 and 13 depend), Chiou is the closest prior art and fails to teach wherein the depositing the second epitaxial layer comprises cleaning the substrate and the chamber with a plurality of flushes of the first etching gas, and wherein a number of the plurality of flushes is greater than a number of flushes with the first etching gas during depositing the first epitaxial layer.
Conclusion
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/CARNELL HUNTER III/Examiner, Art Unit 2893
/SUE A PURVIS/ Supervisory Patent Examiner, Art Unit 2893
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