DETAILED ACTION
This is the Office action based on the 17948350 application filed September 20, 2022, and in response to applicant’s argument/remark filed on September 29, 2025. Claims 1-16 are currently pending and have been considered below.
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 .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Claim Interpretations
Claim 1 recites the limitation “a ratio of a surface area of the holes to a volume of the holes is greater than or equal to 4 centimeters-1”. The specification teaches “Hole surface area of one of the holes is defined by 2πrh*L, where rh is the radius of the hole and L is the thickness of the gas distribution device. Hole volume for a single hole is defined by πrh2*L”. Therefore, the limitation is equivalent to (2πrh*L)/( πrh2*L) ≥ 4 centimeters-1, which is equivalent to rh ≤ 0.5 cm.
Claim 1 recites the term “epitaxial-silicon (epi-Si)”. The specification fails to define this term.This term refers to a silicon that is formed by epitaxial process, which is a product-by-process. Since claim 1 fails to recite a process step of forming the epi-Si, for the purpose of examining any silicon that is capable of being formed by an epitaxial process will be assumed to meet this limitation.
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 of this title, 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 set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied 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 1-4 and 6-8 rejected under 35 U.S.C. 103 as being unpatentable over Mitzutani et al. (U.S. PGPub. No. 20150279852), hereinafter “Mitzutani”, in view of Berry et al. (U.S. PGPub. No. 20160181116), hereinafter “Berry”, in view of Lubomirsky et al. (U.S. PGPub. No. 20180096821), hereinafter “Lubomirsky”, and Sandhu et al. (U.S. PGPub. No. 20060040437), hereinafter “Sandhu”:--Claims 1, 6, 7, 8: Mitzutani teaches a method of forming a semiconductor device, comprisingforming a stack comprising a protrusion 1B and a layer 121 (Fig. 51), wherein the protrusion 1B comprises epitaxial silicon (Fig. 11B, [0037]), and the layer 121 comprises silicon nitride ([0080-0081]);selectively etch the silicon nitride layer 121 without etching the epitaxial silicon protrusion 1B or a silicon oxide layer. Mitzutani is silent about a method of selectively etching the silicon nitride layer 121. Berry, also directed to a method of forming a semiconductor device, teaches a method for selectively etching a silicon nitride layer with respect to a silicon-containing layer during manufacturing a semiconductor device ([0001-0002]), comprisingloading a silicon substrate 516 comprising the silicon nitride layer and the silicon-containing layer on a chuck 520 in a process chamber (Fig. 5, [0079-0082]), wherein the silicon-containing layer may be a silicon oxide layer or a silicon layer, wherein the silicon layer may include polysilicon, amorphous silicon, and crystalline silicon ([0004, 0030]);supplying etching gas through a showerhead to the process chamber, then supply RF power to generating a plasma to selectively etch the silicon nitride layer ([0079], Claim 33);defluorinating the substrate ([0048]). Therefore, it would have been obvious to one of ordinary skill in the art at the effective filing date of the invention to use the method taught by Berry to selectively etch the silicon nitride layer in the invention of Mitzutani because Mitzutani is silent about a method of etching and Berry teaches that such method would be effective. Berry further teaches that the etching gas may comprise fluorine-containing etchant species, such as CF4 ([0063]), and optionally a hydrogen-containing fluorocarbons, such as CH3F ([0041]). Berry is silent about a structure of the showerhead. Lubomirsky, also directed to a method of plasma processing a wafer in a process chamber (abstract, [0002-0003, 0083]), wherein process gases flow through a showerhead having a plurality of holes toward the wafer positioned on a pedestal electrode 250 (Fig. 2, [0077]). Therefore, it would have been obvious to one of ordinary skill in the art at the effective filing date of the invention to use the showerhead taught by Lubomirsky in the invention of Berry because Berry teaches that the etching gas flows through the showerhead is silent about a structure of the showerhead, and Lubomirsky teaches that such showerhead would be effective. Lubomirsky further teaches that the pedestal electrode 250 is movable along a distance in a direction normal to the showerhead, and an etch process may be implemented by moving the pedestal between first and second predetermined positions relative to the first showerhead in order to control heat transfer between the pedestal electrode 250 and the first showerhead (Fig. 2, [0043]). Therefore, although Lubomirsky is silent about a distance between the lower surface of the showerhead and the top surface of the wafer, it would have been obvious to one of ordinary skill in the art at the effective filing date of the invention, in routine experimentations, to use a distance about 20 mm – 80 mm since it has been established that "[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)”. MPEP 2144.05(II)(A). Lubomirsky further teaches that the showerhead may comprise a gas distribution plate comprising 500-10,000 holes ([0068, 0071]), each having diameter about 2.5 mm ([0067-0068]), wherein the gas distribution plate may have a thickness of about 0.1 - 2 mm ([0077]).
It is noted that the aperture diameter of 2.5 mm satisfies the limitation “a ratio of a surface area of the holes to a volume of the holes is greater than or equal to 4 centimeters-1” , and that a crystalline silicon layer is capable of being formed by an epitaxial process (see Claim Interpretations above). Berry further teaches that the silicon-containing layer may be polysilicon, amorphous silicon, or crystalline silicon ([0030, 0047]). Berry fails to teach that the crystalline silicon may be an epitaxial silicon. Sandhu, also directed to a method of selectively dry etching a silicon nitride layer 24 with respect to a semiconductor layer 26 during manufacturing a semiconductor device, teaches that the semiconductor layer 26 may be a silicon layer, a polysilicon layer, or an epitaxial silicon layer 26 ([0031-0032], Fig. 4-5). Therefore, it would have been obvious to one of ordinary skill in the art at the effective filing date of the invention, in routine experimentations, to use an epitaxial silicon layer as the silicon-containing layer in the invention of Berry because Berry teaches that the silicon-containing layer may be polysilicon, amorphous silicon, or crystalline silicon, and Sandhu teaches that a silicon nitride layer may be selectively dry etched with respect to a silicon layer, a polysilicon layer, or an epitaxial silicon layer.
--Claim 2: Lubomirsky further teaches that the showerhead comprises a channel for a temperature control fluid ([0059]), and a plurality of gas distribution plates and plenums (Fig. 5, [0050-0061]), and that argon flow may be directed through the showerhead to the substrate ([0038-0039]). Although Lubomirsky does not disclose the argon gas is supplied into the plenums, since there is no other path to the substrate without going through at least one plenum (Fig. 5), it would have been obvious to one of ordinary skill in the art at the effective filing date of the invention to supply the argon gas to at least a plenum toward the substrate. It is noted that argon may be considered a purge gas.--Claims 3, 4: Berry further teaches to perform a defluorination of the substrate after the etching prior to turning off the plasma by using a scavenging gas mixture comprising O2 and NH3 (Step 110 in Fig. 1, [0054-0055]). It is noted that O2 reads on the claimed oxide species and NH3 reads on the claimed hydrogen species.
Claim 5 rejected under 35 U.S.C. 103 as being unpatentable over Mitzutani in view of Berry, Lubomirsky and Sandhu as applied to claim 1 and 9 above, and further in view of Baldasseroni et al. (U.S. PGPub. No. 20160056032), hereinafter “Baldasseroni”--Claim 5: Mitzutani modified by Berry, Lubomirsky and Sandhu teaches the invention as above. Lubomirsky further teaches that the showerhead may comprise a gas distribution plate comprising 500-10,000 holes ([0068, 0071]), each having diameter about 2.5 mm ([0067-0068]), wherein the gas distribution plate may have a thickness of about 0.1 - 2 mm ([0077]). Lubomirsky is silent about a diameter of the plate. Baldasseroni, also directed to a method of plasma processing during manufacturing a semiconductor device ([0001, 0032-0033]), teaches that the plasma is formed by supplying process gases through a showerhead 106 then applying RF power (Fig. 1, [0036, 0067]). Baldasseroni further teaches that a diameter of a face plate of a showerhead may be 100 to 125% of the wafer size, and that a wafer diameter may be 12” ([0100]). Therefore, it would have been obvious to one of ordinary skill in the art at the effective filing date of the invention, in routine experimentations, to use a plate having a diameter of 12”-15” in the showerhead in the invention of Berry modified by Lubomirsky and Sandhu because Lubomirsky is silent about a diameter of the plate and Baldasseroni teaches that such plate diameter would be effective.
Claims 9-16 rejected under 35 U.S.C. 103 as being unpatentable over Mitzutani in view of Berry, Lubomirsky, Sandhu and Baldasseroni --Claims 9, 10, 11, 12, 13, 14: Mitzutani modified by Berry, Lubomirsky and Sandhu teaches the invention as above. Berry further teaches that the process temperature is 0-80°C, such as 0-20°C ([0035), and that the chamber temperature, the substrate temperature and plasma temperature are controlled by a controller ([0065, 0069]). Lubomirsky further teaches that the showerhead comprises a channel for a temperature control fluid ([0059]), and a plurality of gas distribution plates and plenums (Fig. 5, [0050-0061]), and that an argon flow may be directed through the showerhead to the substrate ([0038-0039]). Lubomirsky further teaches that the pedestal electrode 250 is movable along a distance in a direction normal to the showerhead as a means of controlling heat transfer between the chuck and the showerhead (Fig. 2, [0043]). Lubomirsky fails to teach the claimed feature the showerhead comprises circulating fluid around a periphery of a gas distribution plate and keeping a temperature in a upper region to less than 100°C. It is noted that argon may be considered a purge gas. Baldasseroni, also directed to a method of plasma processing during manufacturing a semiconductor device ([0001, 0032-0033]), teaches that the temperature differentials between showerhead and substrate holder may be maintained by actively thermally adjusting and/or controlling showerhead temperature and, in some embodiments, also employing such active thermal adjustment/control of the substrate holder temperature ([0029]). Baldasseroni further teaches that the showerhead may be controlled at 5-30°C ([0030]) by flowing a cooling fluid, such as argon, through a helical conduit around a peripheral of the showerhead ([0107, 0115, 0120], Fig. 4A-C). Fig. 1 shows that the argon gas would flow in a region around a peripheral of the showerhead 106. Therefore, it would have been obvious to one of ordinary skill in the art at the effective filing date of the invention, in routine experimentations, to flow argon as a cooling fluid around a peripheral of the showerhead in the invention of Berry modified by Lubomirsky and Sandhu because Lubomirsky teaches that it is important to control the temperature of the showerhead, but is silent about the details, and Baldasseroni teaches that such method would be effective. Although Lubomirsky and Baldasseroni are silent about a temperature in an upper region of the showerhead to less than 100°C, since Baldasseroni teaches that the showerhead may be controlled at 5-30°C, it would have been obvious to one of ordinary skill in the art at the effective filing date of the invention, in routine experimentations, that temperature in an upper region of the showerhead is less than 100°C. --Claims 15, 16: Berry further teaches to perform a defluorination of the substrate after the etching prior to turning off the plasma by using a scavenging gas mixture comprising O2 and NH3 (Step 110 in Fig. 1, [0054-0055]). It is noted that O2 reads on the claimed oxide species and NH3 reads on the claimed hydrogen species.
Response to Arguments
Applicant's arguments filed September 29, 2025 have been fully considered as follows:--Regarding Applicant’s argument that the previously cited prior arts do not teach selectively etching a silicon nitride layer relative to an epitaxial silicon layer, this arguments is persuasive. New grounds of rejection based on newly found prior arts are shown above. This Office action is made non-final.--Regarding Applicant’s argument that Examiner’s interpretation of the feature “a ratio of a surface area of the holes to a volume of the holes is greater than or equal to 4 centimeters-1” as the limitation is equivalent to (2πrh*L)/( πrh2*L) ≥ 4 centimeters-1, which is equivalent to rh ≤ 0.5 cm, is not proper, Applicant fails to produce any evidence or reasoning; therefore, this interpretation is maintained.--Likewise, Applicant’s fails to produce any reasoning or evidence that Berry modified by Lubomirsky does not teaches the claimed feature “a gap between a lower surface of the gas distribution device and an upper surface of the substrate during the etching is 20 mm to 80 mm; therefore, the rejection relate to this feature is maintained.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to THOMAS PHAM whose telephone number is (571) 270-7670 and fax number is (571) 270-8670. The examiner can normally be reached on MTWThF9to6 PST.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Joshua Allen can be reached on (571) 270-3176. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/THOMAS T PHAM/Primary Examiner, Art Unit 1713
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