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 .
Election/Restrictions
Applicants’ election without traverse of Invention I (claims 1-16) in the reply filed on 22 June 2026 is acknowledged. Claims 17-20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected invention, there being no allowable generic or linking claim. The restriction requirement is deemed proper and made final.
Response to Amendment
The Office acknowledges receipt on 22 June 2026 of Applicants’ amendments in which claims 17-20 are cancelled and claims 21-24 are newly added.
Claim Objections
Claims 1 and 10 are objected to because of the following informalities:
Claim 1, line 3, recites “to from,” which should read “to form” for proper composition.
Claim 10, lines 1-3, recites “a thickness measured form a top surface of the second dielectric layer to a bottom surface of the first dielectric layer,” should read “a thickness measured from a top surface of the second dielectric layer to a bottom surface of the first dielectric layer” for proper composition.
Appropriate correction is required.
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(s) 1, 2, 4, and 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl et al. (US7504699B1) in view of Lou (US6277732B1).
Regarding claim 1, Kohl teaches a method, comprising:
forming a metal layer (50) over a substrate (52) {Fig. 3A; ll. 53-64 of col. 14};
patterning the metal layer (50) to from first and second metal lines with a trench therebetween {Fig. 3B; l. 65 of col. 14 through l. 8 of col. 15};
depositing a sacrificial layer (54) in a lower portion of the trench {Figs. 3C, 3D; ll. 9-19 of col. 15};
forming a first dielectric layer (56) on the sacrificial layer (54) {Fig. 3E; ll. 21-24 of col. 15};
after the forming of the first dielectric layer (56), selectively removing the sacrificial layer (56) to form an air gap (58) between the first and second metal lines {3F; ll. 25-42 of col. 15}.
Kohl does not teach depositing a second dielectric layer over the first dielectric layer and in an upper portion of the trench.
In an analogous art, Lou teaches in Fig. 1D depositing a second dielectric layer (210) over a first dielectric layer (208) and in an upper portion of a trench (trench between 202b and 202c) {l. 64 of col. 3 through l. 6 of col. 4}. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method based on the teachings of Lou, to achieve the above-identified subject matter, so that the gaps in the loosely packed metal line regions … are completely filled. Lou l. 64 of col. 3 through l. 6 of col. 4. Moreover, [b]y forming a low k … dielectric layer followed by forming a low k … dielectric layer having a higher thermal conductivity … [: (1)] the metal line regions have a lower overall dielectric constant [and (2)] the higher thermal condu[c]tivity of the … dielectric layer also makes cooling of the metal line regions much faster. Lou ll. 46-51 of col 4.
Regarding claim 2, Kohl as modified by Lou teaches the method of claim 1, and Kohl further teaches wherein the metal layer (50) includes a noble metal (Au) {ll. 53-64 of col. 14}.
Regarding claim 4, Kohl as modified by Lou teaches the method of claim 1, and Kohl further teaches wherein the first dielectric layer (56) is a porous dielectric layer (56), such that the sacrificial layer (54) is decomposed into volatile compound that diffuses through the porous dielectric layer (56) during the selectively removing of the sacrificial layer (54) {Fig. 3F; ll. 26-42 of col. 15}.
Regarding claim 7, Kohl as modified by Lou teaches the method of claim 1, and Kohl further teaches wherein the forming of the sacrificial layer (54) includes:
depositing a polymer layer (54) in the trench and over the first and second metal lines (50) {Fig. 3C; ll. 9-15 of col. 15};
planarizing the polymer layer (54) {Fig. 3D; ll. 16-19 of col. 15}; and
etching back the polymer layer {Fig. 3D; ll. 16-19 of col. 15}.
Claim(s) 3 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lou as applied to claim 1 above, and further in view of Peng et al. (US20220352073A1).
Regarding claim 3, Kohl as modified by Lou teaches the method of claim 1, but Kohl does not teach wherein the second dielectric layer has a thermal conductivity not less than about 10 W/m·K.
In an analogous art, Peng teaches in paragraph [0028] a dielectric layer (324 made of AlN, which is the same material identified in paragraph [0031] of the instant application) having a high thermal conductivity, similar to Lou’s high thermally-conductive dielectric layer, with a thermal conductivity not less than about 10 W/m·K. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the teachings of Peng, to achieve the above-identified subject matter, because [t]he selection of a known material based on its suitability for its intended use [is] … prima facie obviousness. MPEP §2144.07.
Claim(s) 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lou as applied to claim 1 above, and further in view of Lin et al. (US20200185264A1).
Regarding claim 5, Kohl as modified by Lou teaches the method of claim 1, but Kohl does not teach further comprising: before the forming of the sacrificial layer, depositing a capping layer, wherein the air gap is vertically between the capping layer and the first dielectric layer.
In an analogous art, Lin teaches in Figs. 3D-3G and paragraphs [0044-0048] before the forming of a sacrificial layer (214; Fig. 3E), depositing a capping layer (216; Fig. 3D), wherein an air gap (218) is vertically between the capping layer (216) and a first dielectric layer (220a). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the teachings of Lin, to achieve the above-identified subject matter, to insulate the metal elements. Lin [0044].
Claim(s) 6 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lou and Lin as applied to claim 5 above, and further in view of Peng.
Regarding claim 6, Kohl as modified by Lou and Lin teaches the method of claim 5, but Kohl does not teach wherein the capping layer includes a thermal conductive material with a thermal conductivity not less than about 10 W/m·K.
However, Lin teaches in paragraph [0044] the capping layer (216) may be aluminum nitride.
Peng teaches in paragraph [0028] a dielectric layer (324 made of AlN, which is the same material identified in paragraph [0031] of the instant application) with a thermal conductivity not less than about 10 W/m·K. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou and Lin based on the teachings of Peng, to achieve the above-identified subject matter, because [t]he selection of a known material based on its suitability for its intended use [is] … prima facie obviousness. MPEP §2144.07.
Claim(s) 8-10 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lou as applied to claim 1 above, and further in view of Huang et al. (US20210082802A1).
Regarding claim 8, Kohl as modified by Lou teaches the method of claim 1, but Kohl does not teach further comprising: prior to the forming of the metal layer, forming a dielectric layer over the substrate with a via through the dielectric layer, wherein the via is directly under one of the first and second metal lines, and wherein the trench partially exposes a top surface of the via.
In an analogous art, Huang teaches in Figs. 1A-1C prior to the forming of a metal layer (130; Fig. 1B; [0043]), forming a dielectric layer (124) over a substrate (102) with a via (125) through the dielectric layer (124; Fig. 1A; [0035, 0036]), wherein the via (125) is directly under one of first and second metal lines (130’; Fig. 1C), and wherein a trench (136) partially exposes a top surface of the via (125) {[0046, 0048]}. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the teachings of Huang, to achieve the above-identified subject matter, so as to form one interconnect layer of the multilayer interconnect structure that is formed over and coupled to the previous interconnect layer. Huang [0035].
Examiner’s Note 1: Huang’s dielectric layer (124) is misidentified as a bulk metal of the via (125) in Huang’s specification, but is correctly identified herein.
Examiner’s Note 2: the recited feature of a “surface” is defined by the American Heritage College Dictionary, fourth edition, in its first (i.e., most common) sense as “[t]he outer … boundary of an object.” Huang teaches a pint of the outer boundary of the via is exposed by the trench.
Regarding claim 9, Kohl as modified by Lou teaches the method of claim 1, but Kohl does not teach further comprising: after the depositing of the second dielectric layer, performing a planarization process to expose the first and second metal lines.
Huang teaches in Figs. 1D and 1E and paragraph [0056] after depositing a dielectric layer (140), performing a planarization process to expose first and second metal lines (130’). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the teachings of Huang, to achieve the above-identified subject matter, so that one or more of the first and second metal lines may be electrically connected to an external environment. See, e.g., Huang’s Fig. 4C.
Regarding claim 10, Kohl as modified by Lou teaches the method of claim 9, but Kohl does not teach wherein after the performing of the planarization process, a thickness measured form (sic) [from] a top surface of the second dielectric layer to a bottom surface of the first dielectric layer is about 20% to about 50% of a thickness of the first and second metal lines.
However, Lou teaches that [b]y forming a low k … dielectric layer followed by forming a low k … dielectric layer having a higher thermal conductivity … [: (1)] the metal line regions have a lower overall dielectric constant [and (2)] the higher thermal condu[c]tivity … dielectric layer also makes cooling of the metal line regions much faster. Lou ll. 46-51 of col 4. And Kohl teaches in ll. 21-29 and 42-49 of col. 1 and lines 51-57 of col. 2 the desirability of employing air gaps as a dielectric layer to reduce the dielectric constant of the material layer to the lowest possible (i.e., most ideal) dielectric constant possible for reducing capacitive coupling, crosstalk, and RC time delays. Together, Kohl and Lou teach that: (1) the amount of capacitive coupling, crosstalk, and RC time delays is inversely proportional to the thickness of lower K dielectric layer (e.g., air gap) with respect to the total thickness of both the lower K dielectric layer and the higher thermal conductivity dielectric layer and (2) the amount of cooling provided by the higher thermal conductivity dielectric layer is inversely proportional to the thickness of lower K dielectric layer (e.g., air gap) with respect to the total thickness of both the lower K dielectric layer and the higher thermal conductivity dielectric layer. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the further teachings of Lou for discovering an optimum or workable range of: (i) capacitive coupling, crosstalk, and RC time delays on the one hand and (ii) cooling (e.g., thermal conductivity) on the other hand – such that a thickness measured from a top surface of the second dielectric layer to a bottom surface of the first dielectric layer is about 20% to about 50% of a thickness of the first and second metal lines – because where 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. MPEP §2144.05(II)(A).
Examiner’s Note: Although paragraph [0036] of the instant application identifies some putative criticality for the range of thickness recited in the claim, such putative criticality does not: (A) materially differ from that taught by Kohl and Lou and (B) provide evidence of an unexpected result differing from that a skilled artisan would expect in view of the teachings of Kohl and Lou. See, e.g., MPEP §2144.05(III)(A).
Claim(s) 11-15 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lin, Lou, Peng, and Huang.
Regarding claim 11, Kohl teaches a method, comprising:
forming a metal layer (50) over a substrate (52) {Fig. 3A; ll. 53-64 of col. 14};
patterning the metal layer (50) to form a trench separating the metal layer (50) into at least a first portion and a second portion {Fig. 3B; l. 65 of col. 14 through l. 8 of col. 15};
depositing a sustaining layer (56) between the first and second portions of the metal layer (50) to seal the trench to form an air gap (58) {Fig. 3E; ll. 21-24 of col. 15; 3F; ll. 25-42 of col. 15}.
Kohl does not teach forming a capping layer extending along top and sidewall surfaces of the first and second portions of the metal layer.
Lin teaches in Fig. 3D and paragraphs [0044-0045] forming a capping layer (216) extending along top and sidewall surfaces of first and second portions of a metal layer (204). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method based on the teachings of Lin, to achieve the above-identified subject matter, to insulate the metal elements. Lin [0044].
Kohl as modified by Lin does not teach depositing a thermal conductive layer over the sustaining layer and over the first and second portions of the metal layer.
Lou teaches in Fig. 1D depositing a thermally-conductive dielectric layer (210) over another dielectric layer (208) (e.g., a sustaining layer) and over the first and second portions of a metal layer (202) {l. 64 of col. 3 through l. 6 of col. 4}. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lin based on the teachings of Lou, to achieve the above-identified subject matter, so that the gaps in the loosely packed metal line regions … are completely filled. Lou l. 64 of col. 3 through l. 6 of col. 4. Moreover, [b]y forming a low k … dielectric layer followed by forming a low k … dielectric layer having a higher thermal conductivity … [: (1)] the metal line regions have a lower overall dielectric constant [and (2)] the higher thermal condu[c]tivity of the … dielectric layer also makes cooling of the metal line regions much faster. Lou ll. 46-51 of col 4.
Kohl as modified by Lin and Lou does not teach the thermal conductive layer has a thermal conductivity not less than about 10 W/m·K.
Peng teaches in paragraph [0028] a dielectric layer (324 made of AlN, which is the same material identified in paragraph [0031] of the instant application) having a high thermal conductivity, similar to Lou’s high thermally-conductive dielectric layer, with a thermal conductivity not less than about 10 W/m·K. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lin and Lou based on the teachings of Peng, to achieve the above-identified subject matter, because [t]he selection of a known material based on its suitability for its intended use [is] … prima facie obviousness. MPEP §2144.07.
Kohl as modified by Lin, Lou, and Peng does not teach performing a planarization process to partially remove the thermal conductive layer and expose the first and second portions of the metal layer.
Huang teaches in Figs. 1D and 1E and paragraph [0056] performing a planarization process to partially remove a dielectric layer (140) {[0053]; made of a low-k dielectric material similar to that of the thermal conductive layer of the instant application} and expose the first and second portions of the metal layer (130). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lin, Lou, and Peng based on the teachings of Huang, to achieve the above-identified subject matter, so that one or more of the first and second portions of the metal layer may be electrically connected to an external environment. See, e.g., Huang’s Fig. 4C.
Regarding claim 12, Kohl as modified by Lin, Lou, Peng, and Huang teaches the method of claim 11, but Kohl does not teach wherein the capping layer has a thermal conductivity not less than about 10 W/m·K.
However, Lin teaches in paragraph [0044] the capping layer (216) may be aluminum nitride.
Peng teaches in paragraph [0028] a dielectric layer (324 made of AlN, which is the same material identified in paragraph [0031] of the instant application) with a thermal conductivity not less than about 10 W/m·K. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lin, Lou, Peng, and Huang based on the further teachings of Lin and Peng, to achieve the above-identified subject matter, because [t]he selection of a known material based on its suitability for its intended use [is] … prima facie obviousness. MPEP §2144.07.
Regarding claim 13, Kohl as modified by Lin, Lou, Peng, and Huang teaches the method of claim 11, but Kohl does not teach further comprising:
depositing a polymer layer over the capping layer and under the sustaining layer to partially fill the trench; and
selectively removing the polymer layer after the depositing of the sustaining layer to form the air gap.
Lin teaches in Figs. 3D-3G and paragraphs [0044-0048] depositing a layer (214) over the capping layer (216) and under a sustaining layer (220a) to partially fill a trench; and selectively removing the layer (214) after the depositing of the sustaining layer (220a) to form an air gap (218). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lin, Lou, Peng, and Huang based on the further teachings of Lin, to achieve the above-identified subject matter, so: (1) [t]he parasitic capacitance between the metal elements … is … reduced and (2) [t]he RC constant is thereby reduced. Lin [0050].
Kohl as modified by Lin does not teach the layer that is removed to form the air gap is a polymer layer.
Kohl teaches in ll. 9-15 of col. 15 the layer (54) that is removed to form the air gap is a polymer layer (54). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lin, Lou, Peng, and Huang based on the further teachings of Kohl, to achieve the above-identified subject matter, because [t]he selection of a known material based on its suitability for its intended use [is] … prima facie obviousness. MPEP §2144.07.
Regarding claim 14, Kohl as modified by Lin, Lou, Peng, and Huang teaches the method of claim 13, and Kohl further teaches wherein the selectively removing of the polymer layer (54) includes decomposing the polymer layer (54) into volatile compound that diffuses through the sustaining layer (56) {Fig. 3F; ll. 26-42 of col. 15}.
Regarding claim 15, Kohl as modified by Lin, Lou, Peng, and Huang teaches the method of claim 11, and Kohl further teaches wherein the metal layer (50) includes a noble metal (Au) {ll. 53-64 of col. 14}.
Claim(s) 16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lin, Lou, Peng, and Huang as applied to claim 11 above, and further in view of Dalton et al. (US20100237467A1).
Regarding claim 16, Kohl as modified by Lin, Lou, Peng, and Huang teaches the method of claim 11, but Kohl does not teach wherein the thermal conductive layer is a diamond or a diamond-like carbon.
In an analogous art, Dalton teaches in paragraph [0046] a thermal conductive layer (50) is a diamond. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lin, Lou, Peng, and Huang based on the teachings of Dalton, to achieve the above-identified subject matter, because [t]he selection of a known material based on its suitability for its intended use [is] … prima facie obviousness. MPEP §2144.07.
Claim(s) 21 and 23 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lou and Peng.
Regarding claim 21, Kohl teaches a method of forming an interconnect structure, comprising:
forming a metal layer (50) over a substrate (52) {Fig. 3A; ll. 53-64 of col. 14};
patterning the metal layer (50) to form a first metal line and a second metal line spaced apart from each other by a trench {Fig. 3B; l. 65 of col. 14 through l. 8 of col. 15};
forming a sacrificial layer (54) that fills a lower portion of the trench {Figs. 3C, 3D; ll. 9-19 of col. 15};
forming a sustaining layer (56) over the sacrificial layer (54), the sustaining layer (56) having a porous structure {Figs. 3E, 3F; ll. 21-24 and 26-42 of col. 15};
after the forming of the sustaining layer (56), selectively removing the sacrificial layer (54) through the sustaining layer (56) to form an air gap (58) between the first metal line and the second metal line {3F; ll. 25-42 of col. 15}.
Kohl does not teach forming a thermal conductive layer over the sustaining layer and in an upper portion of the trench.
Lou teaches in Fig. 1D forming a thermal conductive layer (210) over another dielectric layer (208) (e.g., a sustaining layer) and in an upper portion of a trench (trench between 202b and 202c) {l. 64 of col. 3 through l. 6 of col. 4}. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method based on the teachings of Lou, to achieve the above-identified subject matter, so that the gaps in the loosely packed metal line regions … are completely filled. Lou l. 64 of col. 3 through l. 6 of col. 4. Moreover, [b]y forming a low k … dielectric layer followed by forming a low k … dielectric layer having a higher thermal conductivity … [: (1)] the metal line regions have a lower overall dielectric constant [and (2)] the higher thermal condu[c]tivity of the … dielectric layer also makes cooling of the metal line regions much faster. Lou ll. 46-51 of col 4.
Kohl as modified by Lou does not teach the thermal conductive layer having a thermal conductivity not less than 10 W/m-K.
Peng teaches in paragraph [0028] a dielectric layer (324 made of AlN, which is the same material identified in paragraph [0031] of the instant application) having a high thermal conductivity, similar to Lou’s high thermally-conductive dielectric layer, with a thermal conductivity not less than about 10 W/m·K. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the teachings of Peng, to achieve the above-identified subject matter, because [t]he selection of a known material based on its suitability for its intended use [is] … prima facie obviousness. MPEP §2144.07.
Regarding claim 23, Kohl as modified by Lou and Peng teaches the method of claim 21, and Kohl further teaches wherein the selectively removing of the sacrificial layer (54) includes performing a thermal treatment that decomposes the sacrificial layer (54) into a volatile compound that diffuses through the porous structure of the sustaining layer (56) {Fig. 3F; ll. 26-42 of col. 15}.
Claim(s) 22 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lou and Peng as applied to claim 21 above, and further in view of Lin.
Regarding claim 22, Kohl as modified by Lou and Peng teaches the method of claim 21, but Kohl does not teach further comprising:
before the forming of the sacrificial layer, conformally depositing a capping layer in the trench,
wherein the capping layer has a thermal conductivity not less than 10 W/m- K, and wherein the air gap is vertically between the capping layer and the sustaining layer.
Lin teaches in Figs. 3D-3G and paragraphs [0044-0048] before the forming of a sacrificial layer (214; Fig. 3E), conformally depositing a capping layer (216; Fig. 3D) in a trench (trench filled by air gap 208), wherein an air gap (218) is vertically between the capping layer (216) and a sustaining layer (220a). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the teachings of Lin, to achieve the above-identified subject matter, to insulate the metal elements. Lin [0044].
Kohl as modified by Lin does not teach the capping layer has a thermal conductivity not less than 10 W/m- K
However, Lin teaches in paragraph [0044] the capping layer (216) may be aluminum nitride.
Peng teaches in paragraph [0028] a dielectric layer (324 made of AlN, which is the same material identified in paragraph [0031] of the instant application) with a thermal conductivity not less than about 10 W/m·K. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou and Lin based on the teachings of Peng, to achieve the above-identified subject matter, because [t]he selection of a known material based on its suitability for its intended use [is] … prima facie obviousness. MPEP §2144.07.
Claim(s) 24 is/are rejected under 35 U.S.C. 103 as being unpatentable over Kohl in view of Lou and Peng as applied to claim 21 above, and further in view of Huang.
Regarding claim 24, Kohl as modified by Lou and Peng teaches the method of claim 21, but Kohl does not teach further comprising:
after the forming of the thermal conductive layer, performing a planarization process to expose the first metal line and the second metal line,
wherein after the planarization process a height measured from a top surface of the thermal conductive layer to a bottom surface of the sustaining layer is about 20% to about 50% of a height of the first metal line and the second metal line.
Huang teaches in Figs. 1D and 1E and paragraph [0056] after depositing a dielectric layer (140) (e.g., Lou’s thermal conductive layer 210), performing a planarization process to expose first and second metal lines (130’). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the teachings of Huang, to achieve the above-identified subject matter, so that one or more of the first and second metal lines may be electrically connected to an external environment. See, e.g., Huang’s Fig. 4C.
Kohl as modified by Huang does not teach wherein after the planarization process a height measured from a top surface of the thermal conductive layer to a bottom surface of the sustaining layer is about 20% to about 50% of a height of the first metal line and the second metal line.
However, Lou teaches that [b]y forming a low k … dielectric layer followed by forming a low k … dielectric layer having a higher thermal conductivity … [: (1)] the metal line regions have a lower overall dielectric constant [and (2)] the higher thermal condu[c]tivity … dielectric layer also makes cooling of the metal line regions much faster. Lou ll. 46-51 of col 4. And Kohl teaches in ll. 21-29 and 42-49 of col. 1 and lines 51-57 of col. 2 the desirability of employing air gaps as a dielectric layer to reduce the dielectric constant of the material layer to the lowest possible (i.e., most ideal) dielectric constant possible for reducing capacitive coupling, crosstalk, and RC time delays. Together, Kohl and Lou teach that: (1) the amount of capacitive coupling, crosstalk, and RC time delays is inversely proportional to the thickness of lower K dielectric layer (e.g., air gap) with respect to the total thickness of both the lower K dielectric layer and the higher thermal conductivity dielectric layer and (2) the amount of cooling provided by the higher thermal conductivity dielectric layer is inversely proportional to the thickness of lower K dielectric layer (e.g., air gap) with respect to the total thickness of both the lower K dielectric layer and the higher thermal conductivity dielectric layer. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify Kohl’s method as modified by Lou based on the further teachings of Lou for discovering an optimum or workable range of: (i) capacitive coupling, crosstalk, and RC time delays on the one hand and (ii) cooling (e.g., thermal conductivity) on the other hand – such that a height measured from a top surface of the thermal conductive layer to a bottom surface of the sustaining layer is about 20% to about 50% of a height of the first metal line and the second metal line – because where 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. MPEP §2144.05(II)(A).
Examiner’s Note: Although paragraph [0036] of the instant application identifies some putative criticality for the range of thickness recited in the claim, such putative criticality does not: (A) materially differ from that taught by Kohl and Lou and (B) provide evidence of an unexpected result differing from that a skilled artisan would expect in view of the teachings of Kohl and Lou. See, e.g., MPEP §2144.05(III)(A).
Citation of Pertinent Prior Art
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Briggs et al. (US20170278796A1) teaches a method of forming an interconnect to an electrical device is provided. The structure produced by the method may include a plurality of metal lines in a region of a substrate positioned in an array of metal lines all having parallel lengths; and a plurality of air gaps between the metal lines in a same level as the metal lines, wherein an air gap is present between each set of adjacent metal lines. A plurality of interconnects may be present in electrical communication with said plurality of metal lines, wherein an exclusion zone for said plurality of interconnects is not present in said array of metal lines.
Conclusion
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/D.W.W./Examiner, Art Unit 2891
/MATTHEW C LANDAU/Supervisory Patent Examiner, Art Unit 2891
Prosecution Insights