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 § 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.
Claims 1-2 and 7-9 are rejected under 35 U.S.C. 103 as being unpatentable over by Sasaki et al. (US 10,153,181; hereinafter Sasaki).
Regarding claim 1, Sasaki discloses a method for forming a semiconductor structure, comprising:
dispensing a dehydrating chemical (IPA rinsing step S12 and process liquid supplying step S13, Figs. 12-13) in a liquid state (IPA and process liquid, Figs. 12-13) over a fin (pattern Wp, Fig. 13) of a substrate (substrate W, Fig. 13),
wherein the dehydrating chemical comprises:
a first chemical (IPA, Fig. 12); and
a second chemical (process liquid or dry assistant liquid 62, step S13, Figs. 12-13) having a melting point greater than the melting point of the first chemical (melting point of IPA = approximately ‒89 °C), because Sasaki further discloses that the dry assistant liquid 62 includes “Compound (A): a fluoroalkane having 3 to 6 carbon atoms, or the fluoroalkane to which a substituent is bonded; Compound (B): a fluorocycloalkane having 3 to 6 carbon atoms, or the fluorocycloalkane to which a substituent is bonded; Compound (C): a fluorobicycloalkane having 10 carbon atoms, or the fluorobicycloalkane to which a substituent is bonded; Compound (D): a fluorotetracyanoquinodimetane, or the fluorotetracyanoquinodimetane to which a substituent is bonded; and Compound (E): a fluorocyclotriphosphazene, or the fluorocyclotriphosphazene to which a substituent is bonded” (Col. 19, lines 35-47) and it is well-known in the art that these fluorinated carbon compounds would have higher melting point than IPA. For example, one of the listed compounds by Sasaki in a group of the compound (B) is “monofluorocyclohexane” (Col. 20, line 50) and the melting point of monofluorocyclohexane is approximately 13 °C, which is much greater than the melting point of IPA (approximately minus 89 °C); and
solidifying the dehydrating chemical (solidifying step S14, Figs. 12-13).
Sasaki does not explicitly disclose a fin over the substrate.
However, it is obvious to one of ordinary skill in the art that a substrate treating apparatus and method by Sasaki can be applied to the substrate treatment of a FinFET device, because a method of manufacturing FinFET requires various wet chemical treatments using liquid, and subsequently the substrate is subjected to a drying treatment for removing the liquid adhering on the substrate by the wet treatment, as disclosed by Sasaki (Col. 1, lines 20-24).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the substrate treatment method disclosed by Sasaki can be used for a method of manufacturing FinFET device in order to effectively remove liquid residues from various wet chemical etching processes, and therefore, reduce possible defects from the residues.
Regarding claim 2, Sasaki further discloses that removing the dehydrating chemical by vaporizing the solidified dehydrating chemical (sublimation step S15, Figs. 12-13).
Regarding claim 7, Sasaki further discloses that spinning the substrate subsequent to solidifying the dehydrating chemical, because the substrate W by Sasaki et al. is located on the spin base 53 (Figs. 1-2), and the substrate treatment would be processed during spinning the substrate and “the rotation speed of the substrate W is preferably set to make the membrane thickness of a membrane made of IPA higher than the height of the convexities Wp1 on the whole of the front surface Wf…” (Col. 24, lines 2-5).
Regarding claim 8, Sasaki further discloses that the first chemical comprises at least one of isopropyl alcohol (IPA), CH3COCH3 (acetone), propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monomethyl ether (PGMEA), because Sasaki uses IPA in the rinsing step S12 (Fig. 12).
Regarding claim 9, Sasaki further discloses that the second chemical comprises at least one of tert-butanol (TBA), hexachloroethane, pentaerythritol, camphor, tropinone, norcamphor, naphthalene, cyclohexanol, camphene, borneol, and isoborneol, because Sasaki uses t-butanol (TBA in the claimed invention), which is well-known for a conventional dry assistant substance (Col. 59, lines 43-44).
Claim 3-4 are rejected under 35 U.S.C. 103 as being unpatentable over Sasaki et al. (US 10,153,181; hereinafter Sasaki) in view of Wojtczak et al. (US 11,508,569; hereinafter Wojtczak). The teachings of Sasaki et al. are discussed above.
Regarding claim 3, Sasaki does not explicitly disclose that dispensing diluted hydrogen fluoride acid over the substrate prior to dispensing the dehydrating chemical.
However, Wojtczak discloses for surface treatment of semiconductor device that a patterned substrate is cleaned using RCA clean sequence with a diluted hydrofluoric acid/ammonium hydrogen peroxide/hydrogen peroxide and hydrochloric acid prior to surface modification and sublimation to prevent stiction drying (Col. 14, lines 6-13).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that hydrofluoric acid can be used to clean patterned substrate in the manufacturing process of semiconductor device prior to surface modification with a sublimating material, as disclosed by Wojtczak, in order to remove unnecessary residues from a substrate for subsequent surface treatments.
Regarding claim 4, Wojtczak further discloses that dispensing deionized water in a liquid state over the substrate subsequent to dispensing diluted fluoride, because after RCA clean sequence with diluted hydrofluoric acid, the patterned substrate was “rinsed with water, isopropanol or other rinse or combination of rinse…” (emphasis added, Col. 14, lines 6-8).
Claim 5-6 and 17-19 are rejected under 35 U.S.C. 103 as being unpatentable over Sasaki et al. (US 10,153,181; hereinafter Sasaki) in view of Ohtou et al. (US 10,038,079; hereinafter Ohtou). The teachings of Sasaki et al. are discussed above.
Regarding claim 5, Sasaki does not explicitly disclose that forming a gate stack over the fin.
However, Ohtou discloses a Fin-FET device including the gate electrode 40 formed over the fin structure 20 (Fig. 1B), thereby teaching the claimed gate stack formed over the fin. Ohtou’s Fin-FET structure is representative of a conventional Fin-FET architecture well known in the semiconductor art.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the substrate surface treatment disclosed by Sasaki during the fabrication of the Fin-FET device taught by Ohtou. Sasaki’s surface treatment is not limited to a particular transistor architecture and is generally directed to improving substrate surface conditions during semiconductor fabrication. One of ordinary skill in the semiconductor art would have reasonably expected Sasaki’s surface treatment method to be equally applicable to the manufacture of Fin-FET devices, in order to improve surface cleanliness and reduce moisture residue on the substrate from subsequent processing.
Regarding claim 6, Sasaki in view of Ohtou does not explicitly disclose that forming a sacrificial gate subsequent to removing the dehydrating chemical and prior to forming the gate stack.
However, Ohtou discloses forming dummy gate layers 110 over the fin structure 20 during fabrication of Fin-FET device (Fig. 5C) and as discussed above in claim 5, one of ordinary skill in the art would have recognized that Sasaki’s surface treatment method is generally applicable to semiconductor substrate preparation and is not limited to any particular transistor architecture. Therefore, one of ordinary skill in the art would have reasonably expected the surface treatment by Sasaki, including removal of the hydrating chemical, to be performed before forming Ohtou’s dummy gate layers in order to provide clean, low-moisture substrate surface for subsequent gate electrode formation.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to incorporate the substrate surface treatment disclosed by Sasaki into the fabrication of the Fin-FET device taught by Ohtou such that the substrate surface is treated prior to formation of the dummy gate layers and the subsequent gate stack. Applying Sasaki’s surface treatment at this step would improve surface cleanliness and reduce moisture residue on the substrate for from subsequent gate stack formation.
Regarding claim 17, Sasaki further discloses for a method for forming a semiconductor structure, comprising:
providing a substrate (substrate W, Fig. 13) comprising fins (pattern Wp, Fig. 13) and trenches (trenches between Wp, Fig. 13) surrounding the fins (Wp, Fig. 13);
dispensing a dehydrating chemical (IPA rinsing step S12 and process liquid supplying step S13, Figs. 12-13) in a liquid state (IPA and process liquid, Figs. 12-13) on the fins (Wp, Fig. 13) and the trenches (trenches between Wp, Fig. 13),
wherein the dehydrating chemical comprises a first chemical (IPA, Fig. 12) and a second chemical (process liquid or dry assistant liquid 62, step S13, Figs. 12-13) having a melting point greater than the melting point of the first chemical, because Sasaki further discloses that the dry assistant liquid 62 includes “Compound (A): a fluoroalkane having 3 to 6 carbon atoms, or the fluoroalkane to which a substituent is bonded; Compound (B): a fluorocycloalkane having 3 to 6 carbon atoms, or the fluorocycloalkane to which a substituent is bonded; Compound (C): a fluorobicycloalkane having 10 carbon atoms, or the fluorobicycloalkane to which a substituent is bonded; Compound (D): a fluorotetracyanoquinodimetane, or the fluorotetracyanoquinodimetane to which a substituent is bonded; and Compound (E): a fluorocyclotriphosphazene, or the fluorocyclotriphosphazene to which a substituent is bonded” (Col. 19, lines 35-47) and it is well-known in the art that these fluorinated carbon compounds would have higher melting point than IPA. For example, one of the listed compounds by Sasaki in a group of the compound (B) is “monofluorocyclohexane” (Col. 20, line 50) and the melting point of monofluorocyclohexane is approximately 13 °C, which is much greater than the melting point of IPA (approximately minus 89 °C) and
solidifying the dehydrating chemical (solidifying step S14, Figs. 12-13);
vaporizing the solidified dehydrating chemical to expose the fins and the trenches (sublimating step S15, Figs. 12-13).
Sasaki does not explicitly disclose that a weight percentage of the first chemical is greater than a weight percentage of the second chemical.
However, one of ordinary skill in the art would have recognized that the relative weight percentages of the first and second chemicals in the hydrating chemical composition affect the physical and processing characteristics of the composition, such as viscosity, wetting, melting point, vapor pressure, and film formation during deposition and subsequent processing. The relative weight percentage (i.e., concentration) of the constituent chemicals in the hydrating chemical is therefore a result-effective variable to be optimized by repeated experiments.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to vary, through routine optimization, the relative weight percentages of the first and second chemical in the hydrating chemical, which has identified as a result-effective variable to obtain suitable processing characteristics and resulting film properties. Further, one of ordinary skill in the art would have had a reasonable expectation of success to arrive at a weight percentage of the first chemical is greater than a weight percentage of the second chemical, in order to achieve the desired properties of resulting film of the hydrating chemical, as well known in the art. Furthermore, the applicant has not presented persuasive evidence that the claimed weight percentage relationship between the first and second chemicals is for a particular purpose that is critical to the overall claimed invention (i.e., that the invention would not work without the specific relative weight percentage relationship).
Further regarding claim 17, Sasaki does not explicitly disclose that forming gate stacks over the fins.
However, Ohtou discloses a Fin-FET device including the gate electrode 40 formed over the fin structure 20 (Fig. 1B), thereby teaching the claimed gate stack formed over the fin. Ohtou’s Fin-FET structure is representative of a conventional Fin-FET architecture well known in the semiconductor art.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the substrate surface treatment disclosed by Sasaki during the fabrication of the Fin-FET device taught by Ohtou. Sasaki’s surface treatment is not limited to a particular transistor architecture and is generally directed to improving substrate surface conditions during semiconductor fabrication. One of ordinary skill in the semiconductor art would have reasonably expected Sasaki’s surface treatment method to be equally applicable to the manufacture of Fin-FET devices, in order to improve surface cleanliness and reduce moisture residue on the substrate from subsequent processing.
Regarding claim 18, Sasaki further discloses that the first chemical comprises at least one of isopropyl alcohol (IPA), CH3COCH3 (acetone), propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monomethyl ether (PGMEA), because Sasaki uses IPA in the rinsing step S12 (Fig. 12).
Regarding claim 19, Sasaki further discloses that the second chemical comprises at least one of tert-butanol (TBA), hexachloroethane, pentaerythritol, camphor, tropinone, norcamphor, naphthalene, cyclohexanol, camphene, borneol, and isoborneol, because Sasaki uses t-butanol (TBA in the claimed invention), which is well-known for a conventional dry assistant substance (Col. 59, lines 43-44).
Allowable Subject Matter
Claims 10-16 are allowed, because the prior arts cited in this Office Action do not teach the claim limitation, “detecting a first environment temperature of a first environment, wherein the dehydrating chemical is transported in the first environment prior to being dispensed on the substrate; detecting a second environment temperature of a second environment, wherein the dehydrating chemical is transported in the second environment subsequent to being dispensed on the substrate; and adjusting a mixing ratio of the first chemical and the second chemical in the dehydrating chemical according to the first environment temperature and the second environment temperature” recited in claim 10. Claims 11-16 depend on claim 10.
Claim 20 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, because the prior arts cited in this Office Action do not teach the claim limitation, “the coolant comprises deionized water and isopropyl alcohol (IPA)”, recited in claim 20.
Conclusion
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/JAY C KIM/Primary Examiner, Art Unit 2815
/WOO K LEE/Examiner, Art Unit 2815
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