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 .
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 07/22/2024, 01/27/2025, 05/02/2025, 05/15/2025, 09/26/2025, 02/03/2026, in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL. —The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claim 19 is rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 19 recite “a second width that is larger than the first width”. However, the specifications and the drawings do not support a second width that is larger than the first width. Furthermore, drawings and description of the specifications suggest a second width which is width of the doped epitaxial layer 114 is smaller than the first width which is the width of the epitaxial material 104.
Appropriate corrections are required.
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.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 10-14 and 19 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.
Claim 10, line 12 recited “within a central region of the epitaxial structure” without defining “a central region of the epitaxial structure” earlier in the claim or in the specification. There is insufficient antecedent basis for these limitations in the claim. Therefore, it is unclear, and the scope of the claim is unclear. For examination purposes, 114 in Fig. 9A-9B will be interpreted as “a central region of the epitaxial structure”.
Claims 11-14 inherit the deficiencies of the Independent Claim 10.
Claim 13 line 1 recited “within a part of the central region” without defining “a central region of the epitaxial structure” earlier in the claim or in the specification. There is insufficient antecedent basis for these limitations in the claim. Therefore, it is unclear, and the scope of the claim is unclear. For examination purposes, 114 in Fig. 9A-9B will be interpreted as “a central region of the epitaxial structure”.
Claim 19 lines 3-4 recited “a second width that is larger than the first width”. However, drawings and description of the specifications disclose, a second width which is width of the doped epitaxial layer 114 that is smaller than the first width which is the width of the epitaxial material 104. There is insufficient antecedent basis for these limitations in the claim. Therefore, it is unclear, and the scope of the claim is unclear.
Appropriate corrections are required.
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.
Claim(s) 1, 3, and 6, 9-12, 15-17 and 20 are rejected under 35 U.S.C. 102 as being anticipated by Sze, Jhy-Jyi (US 20200105812 A1) “Sze”.
With Regards to Independent Claim 1, Sze Figs. 2-3B, 6, 11-16 discloses, an integrated chip structure 600 (“a three-dimensional integrated chip (3DIC) 600” ¶ [0057]), comprising:
a base substrate 103 (“substrate 103.” ¶ [0065]) comprising one or more interior surfaces defining a recess (“remove a portion of the first and second dielectric layers 134, 132 and the substrate 103 defining an opening 1104 within the substrate 103.” ¶ [0065]) within an upper surface of the base substrate 103 (opening 1104 within the substrate 103.” ¶ [0065]);
an epitaxial material 146 (“layer 146 …. be formed by …. suitable epitaxial process,” ¶ [0066]) disposed within the recess 1104 (“layer 146 of a first image sensor element 110 is formed within the opening 1104” ¶ [0066]);
a first doped photodiode region 204 (“doped region 204” ¶ [0068]) disposed within the epitaxial material 146 and comprising a first doping type (“the first heavily doped region 204 is formed by doping the active layer 146 with arsenic, phosphorus, some other suitable N-type dopants” ¶ [0069]);
a second doped photodiode region 202 (“deep well 202 is formed around the first heavily doped region 204” ¶ [0068]) disposed within the epitaxial material 146 and comprising a second doping type (“second deep well 202 is formed by doping the active layer 146 with boron or some other suitable P-type dopants” ¶ [0069]),
wherein the second doped photodiode region 202 laterally surrounds the first doped photodiode region 204 (“deep well 202 is formed around the first heavily doped region 204” ¶ [0068]); and
a doped epitaxial layer 144 (“layer 144 may, for example, be formed by … suitable epitaxial process” ¶ [0066]) disposed horizontally and vertically between the base substrate 103 and the epitaxial material 146 (Fig. 12 shows the layer 144 is disposed horizontally and vertically between the base substrate 103 and the epitaxial material 146), the doped epitaxial layer 144 having the second doping type (“the buffer layer 144 may, for example, be or comprise silicon germanium doped with boron or some other suitable P-type dopants” ¶ [0067]).
With Regards to Claim 3, Sze discloses the limitations of claim 1. Sze further discloses, wherein the doped epitaxial layer 144 (“the buffer layer 144 may, for example, be or comprise silicon germanium doped with boron or some other suitable P-type dopants” ¶ [0067]) is a same material as the base substrate 103 (“the substrate 103 may, for example, be a bulk substrate (e.g., a bulk silicon substrate), a silicon-on-insulator (SOI) substrate doped with boron or some other suitable P-type dopants” ¶ [0060]).
With Regards to Claim 6, Sze discloses the limitations of claim 1. Sze further discloses, wherein the base substrate 103 comprises silicon (“substrate 103 is comprised of a second material (e.g., silicon)” ¶ [0022]) and the epitaxial material 146 comprises germanium (“layer 146 comprising the first material (e.g., germanium)” ¶ [0036).
With Regards to Claim 9, Sze discloses the limitations of claim 1. Sze Figs. 3B and 5 further discloses, wherein the doped epitaxial layer 144 continuously wraps around (“a layout of the regions/layers in and/or around the active layer 146.” ¶ [0044]) the epitaxial material 146 in a closed loop, as viewed in a plan view (“With reference to FIG. 3B, some embodiments of a top view 300b of the stacked image sensor device 200 of FIG. 2” ¶ [0043]).
With Regards to Independent Claim 10, Sze Figs. 2-3B, 11-16 discloses, an integrated chip structure, comprising:
a substrate 103 (“substrate 103.” ¶ [0065]) comprising one or more interior surfaces forming a recess (“remove a portion of the first and second dielectric layers 134, 132 and the substrate 103 defining an opening 1104 within the substrate 103.” ¶ [0065]) within an upper surface of the substrate103 (opening 1104 within the substrate 103.” ¶ [0065]);
an epitaxial structure (142, 144, 146) (“In some embodiments, the top isolation structure 142, the buffer layer 144, and/or the active layer 146 may, for example, be formed by MBE, VPE, LPE, some other suitable epitaxial process, or any combination of the foregoing.” ¶ [0066]) disposed within the recess 1104 (“layer 146 of a first image sensor element 110 is formed within the opening 1104” ¶ [0066]);
a first doped photodiode region 204 (“doped region 204” ¶ [0068]) disposed within the epitaxial structure 146 and comprising a first doping type (“the first heavily doped region 204 is formed by doping the active layer 146 with arsenic, phosphorus, some other suitable N-type dopants” ¶ [0069]);
a second doped photodiode region 202 (“deep well 202 is formed around the first heavily doped region 204” ¶ [0068]) disposed within the epitaxial structure 146 and comprising a second doping type (“second deep well 202 is formed by doping the active layer 146 with boron or some other suitable P-type dopants” ¶ [0069]),
wherein the second doped photodiode region 202 laterally surrounds the first doped photodiode region 204 (“deep well 202 is formed around the first heavily doped region 204” ¶ [0068]); and
wherein the epitaxial structure (142, 144, 146) is partially doped with a dopant having the second doping type (“the top isolation structure 142 may, for example, be or comprise silicon doped with boron or some other suitable P-type dopants”; “the buffer layer 144 may, for example, be or comprise silicon germanium doped with boron or some other suitable P-type dopants”; “layer 146 may, for example, be or comprise germanium doped with boron or some other suitable P-type dopants” ¶ [0067]),
the dopant having a first doping concentration (“the top isolation structure 142 may, for example, be or comprise silicon doped with boron or some other suitable P-type dopants with a concentration of approximately 1×10.sup.18 to approximately 1×10.sup.19 atoms/cm.sup.3.” ¶ [0067]) along an outermost edge 142 of the epitaxial structure (142, 144, 146) and a second doping concentration (“the buffer layer 144 may, for example, be or comprise silicon germanium doped with boron or some other suitable P-type dopants with a concentration of approximately 3×10.sup.16 atoms/cm.sup.3 or less.” ¶ [0067]) within a central region 144 of the epitaxial structure (142, 144, 146), the first doping concentration being larger than the second doping concentration (a concentration of approximately 1×10.sup.18 to approximately 1×10.sup.19 atoms/cm.sup.3. is larger than a concentration of approximately 3×10.sup.16 atoms/cm.sup.3 or less.).
With Regards to Claim 11, Sze discloses the limitations of claim 10. Sze further discloses, wherein the first doping concentration (“the top isolation structure 142 may, for example, be or comprise silicon doped with boron or some other suitable P-type dopants with a concentration of approximately 1×10.sup.18 to approximately 1×10.sup.19 atoms/cm.sup.3.” ¶ [0067]) is more than 2 orders of magnitude larger than the second doping concentration (“the buffer layer 144 may, for example, be or comprise silicon germanium doped with boron or some other suitable P-type dopants with a concentration of approximately 3×10.sup.16 atoms/cm.sup.3 or less.” ¶ [0067]; a concentration of 1×10.sup.19 atoms/cm.sup.3. is more than 2 orders of magnitude larger than a concentration of approximately 3×10.sup.16 atoms/cm.sup.3 or less.).
With Regards to Claim 12, Sze discloses the limitations of claim 10. Sze Fig. 3B further discloses, wherein the second doped photodiode region 202 continuously wraps around the first doped photodiode region 204 in a closed loop (Fig. 3B shows the second doped photodiode region 202 continuously wraps around the first doped photodiode region 204 in a closed loop), as viewed in a top view (“With reference to FIG. 3B, some embodiments of a top view 300b of the stacked image sensor device 200 of FIG. 2” ¶ [0043]).
With Regards to Claim 14, Sze discloses the limitations of claim 10. Sze further discloses, further comprising:
a cap layer 130 (“a third dielectric layer 130 is formed over the first and second dielectric layers 134, 132 and the substrate 103” ¶ [0068]) disposed onto an uppermost surface of the epitaxial structure (142, 144, 146);
a dielectric material (“A first dielectric layer 134 is formed over the substrate 103” ¶ [0061]) disposed onto the epitaxial structure (142, 144, 146) and along sidewalls of the cap layer 130;
an etch stop layer disposed along upper surfaces and sidewalls of the dielectric material (“In some embodiments, the second deep well 202 is formed before the third dielectric layer 130 by performing an etch process according to a hard mask formed over the active layer 146 defining a guard ring opening, forming the second material (silicon) within the guard ring opening, and performing a planarization process (not shown).” ¶ [0069]); and
an interlevel dielectric (ILD) material region 119 (“Formation of the interconnect structure 102 includes forming an ILD layer 119 over the third dielectric layer 130” ¶ [0070]) disposed on the etch stop layer, wherein the ILD material surrounds one or more interconnects coupled to the first doped photodiode region and the second doped photodiode region (“Formation of the interconnect structure 102 includes forming an ILD layer 119 over the third dielectric layer 130, a plurality of contacts 122 are formed within the ILD layer 119 in direct contact with contact regions within the substrate 103 and/or electrodes over the substrate 103, a second IMD layer 120 is formed over the ILD layer 119, a plurality of conductive wires 124 and a plurality of conductive vias 126 are formed within the second IMD layer 120. A top metal layer 602 is formed within the second IMD layer 120.” ¶ [0070]).
With Regards to Independent Claim 15, Sze Figs. 2-3B, 11-16 discloses, an integrated chip structure, comprising:
a substrate 103 (“the substrate 103” ¶ [0060]) comprising a first semiconductor material (“the substrate 103 may, for example, be a bulk substrate (e.g., a bulk silicon substrate),” ¶ [0060]);
an epitaxial structure (142, 144, 146) (“In some embodiments, the top isolation structure 142, the buffer layer 144, and/or the active layer 146 may, for example, be formed by MBE, VPE, LPE, some other suitable epitaxial process, or any combination of the foregoing.” ¶ [0066]) arranged between one or more interior sidewalls of the substrate 103, wherein the epitaxial structure comprises a second semiconductor material (“the top isolation structure 142 may, for example, be or comprise silicon doped with boron or some other suitable P-type dopants”; “the buffer layer 144 may, for example, be or comprise silicon germanium doped with boron or some other suitable P-type dopants”; “layer 146 may, for example, be or comprise germanium doped with boron or some other suitable P-type dopants” ¶ [0067]), that is different than the first semiconductor material;
a first doped photodiode region 204 (“doped region 204” ¶ [0068]) disposed within the epitaxial structure (142, 144, 146);
a second doped photodiode region 202 (“deep well 202 is formed around the first heavily doped region 204” ¶ [0068]) disposed within the epitaxial structure (142, 144, 146); and
wherein the epitaxial structure (142, 144, 146) is doped with a dopant (“suitable P-type dopants” ¶ [0067]), the dopant having a maximum concentration (“the top isolation structure 142 may, for example, be or comprise silicon doped with boron or some other suitable P-type dopants with a concentration of approximately 1×10.sup.18 to approximately 1×10.sup.19 atoms/cm.sup.3.” ¶ [0067]; “the buffer layer 144 may, for example, be or comprise silicon germanium doped with boron or some other suitable P-type dopants with a concentration of approximately 3×10.sup.16 atoms/cm.sup.3 or less.” ¶ [0067]) along an interface (142 along an interface with the substrate 103 has maximum doping concentration) with the substrate 103.
With Regards to Claim 16, Sze discloses the limitations of claim 15. Sze further Fig. 12 discloses, wherein the epitaxial structure comprises:
an epitaxial material 146 (“An active layer 146 of a first image sensor element 110 is formed within the opening 1104 over the buffer layer 144.” ¶ [0066]); and
a doped epitaxial layer 142 & 144 (“the top isolation structure 142, the buffer layer 144,” ¶ [0066]) separating (Fig. 12 shows 146 is separated from 103 by 142 &144) the epitaxial material 146 from the substrate 103.
With Regards to Claim 17, Sze discloses the limitations of claim 16. Sze further Fig. 12 discloses, wherein the doped epitaxial layer 142 (“the top isolation structure 142 may, for example, be or comprise silicon doped with boron or some other suitable P-type dopants with a concentration of approximately 1×10.sup.18 to approximately 1×10.sup.19 atoms/cm.sup.3.” ¶ [0067]) has a larger concentration (a concentration of approximately 1×10.sup.18 to approximately 1×10.sup.19 atoms/cm.sup.3. is larger than a concentration of approximately 3×10.sup.16 atoms/cm.sup.3 or less.); of the dopant than the epitaxial material 146 (“the active layer 146 may, for example, be or comprise germanium doped with boron or some other suitable P-type dopants with a concentration of approximately 3×10.sup.16 atoms/cm.sup.3 or less” ¶ [0067]).
With Regards to Claim 20, Sze discloses the limitations of claim 16. Sze further Fig. 3B discloses, wherein the doped epitaxial layer 142 &144 has a substantially equal thickness along the interior sidewalls (Fig. 3B shows the doped epitaxial layer 142 &144 has a substantially equal thickness along the interior sidewalls and an upper surface of the substrate 103) and an upper surface of the substrate 103.
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 7-8 are rejected under 35 U.S.C. 103 as being unpatentable over Sze, Jhy-Jyi (US 20200105812 A1) “Sze”.
With Regards to Claim 7, Sze discloses the limitations of claim 1. However, the embodiment of 600 does not disclose, wherein the epitaxial material laterally separates opposing sides of the first doped photodiode region from the second doped photodiode region.
In the In the similar field of endeavor of image sensor, Sze Fig. 4 further discloses, wherein the epitaxial material 146 laterally separates opposing sides of the first doped photodiode region 406/408 from the second doped photodiode region 410 (“the first and second floating nodes 406, 408 are laterally offset from the first heavily doped region 410 by a non-zero distance, respectively” ¶ [0048]).
It would have been obvious to person having ordinary skill in the art before the effective filling date to modify the embodiment 600 of Sze with embodiment 400 of Sze in order to control the flow of photon-generated carriers (Sze, ¶ [0053]).
With Regards to Claim 8, Sze discloses the limitations of claim 1. However, the embodiment of 600 does not disclose, one or more isolation regions disposed within the base substrate along opposing sides of the epitaxial material, wherein the base substrate is directly between a side of the one or more isolation regions and a side of the doped epitaxial layer.
In the similar field of endeavor of image sensor, Sze Fig. 4 further discloses, further comprising: one or more isolation regions (“a shallow trench isolation (STI) structure 136 comprising multiple segments within the substrate 103.” ¶ [0061]) disposed within the base substrate 103 along opposing sides of the epitaxial material 146, wherein the base substrate 103 is directly between a side of the one or more isolation regions 136 and a side of the doped epitaxial layer 144 (Fig. 4 shows the base substrate 103 is directly between a side of the one or more isolation regions 136 and a side of the doped epitaxial layer 144).
It would have been obvious to person having ordinary skill in the art before the effective filling date to modify the embodiment 600 of Sze with embodiment 400 of Sze in order to provide electrical isolation between the first image sensor element 110 and pixel devices and/or contact regions within the substrate 103. (Sze, ¶ [0028]).
Claims 2, 4-5 are rejected under 35 U.S.C. 103 as being unpatentable over Sze, Jhy-Jyi (US 20200105812 A1) “Sze” in view of Hong, Sungkwon C. (US 20070045682 A1) “Hong”.
With Regards to Claim 2, Sze discloses the limitations of claim 1. However, Sze does not disclose, wherein a doping concentration within the epitaxial material changes from approximately 1e16 atoms/cm3 to approximately 1e17 atoms/cm3 over a distance that is less than or equal to approximately 1000 Angstroms.
In the similar field of endeavor of image sensor, Hong discloses, wherein a doping concentration 350 (“epitaxial layer 311 dopant gradient 350 has a dopant concentration that increases from the upper surface of the epitaxial layer 311 toward the bottom surface of the epitaxial layer 311” ¶ [0023]) within the epitaxial material 311 changes from approximately 1e16 atoms/cm3 to approximately 1e17 atoms/cm3 (“dopant concentration at the surface of the epitaxial layer 311 is about 1.times.10.sup.14 atoms/cm.sup.3 to about 5.times.10.sup.15 atoms/cm.sup.3, and changes in a gradient manner to the bottom surface of the epitaxial layer 311, which has a dopant concentration of about 5.times.10.sup.16 atoms/cm.sup.3 to about 5.times.10.sup.18 atoms/cm.sup.3 or more.” [0023]; (The maximum change by an order of magnitude is 10000 between the top and bottom surface of 311) over a distance 355 (“The thickness 355 can be between about 2 µm and about 20 µm.” ¶ [0029]; Therefore, the gradient of the concentration vs the distance is (10000/20000 = 0.5), which is in the range of the claimed gradient of concentration vs distance (10/1000 = 0.01 or greater than 0.01, for the distances less than 1000 Angstroms) depending on the distance/thickness of the epitaxial layer) that is less than or equal to approximately 1000 Angstroms.
It would have been obvious to person having ordinary skill in the art before the effective filling date to modify the epitaxial layer of Sze with the gradient doping concentration of the epitaxial layer of Hong in order to narrow the depletion region at the pn junction. Additionally, the dopant gradient 350 creates a vertical electric field that serves to induce electrons toward the surface of the epitaxial layer 311 where such electrons can be collected by the photo-conversion device 23. (Although the photo-conversion device is depicted as a pinned photodiode, it could instead be another type of photo-conversion device, such as a non-pinned photodiode, or photogate, among others.) Accordingly, in addition to minimizing the loss of quantum efficiency at longer wavelengths, the invention also serves to maintain photon sensitivity and reduce image lag (Hong, ¶ [0026]).
With Regards to Claim 4, Sze discloses the limitations of claim 1, as discussed above. However, Sze does not disclose, wherein a doping concentration within the epitaxial material changes by over an order of magnitude over a distance that is less than or equal to approximately 1000 Angstroms.
In the similar field of endeavor of image sensor, Hong discloses wherein a doping concentration 350 (“epitaxial layer 311 dopant gradient 350 has a dopant concentration that increases from the upper surface of the epitaxial layer 311 toward the bottom surface of the epitaxial layer 311” ¶ [0023]) within the epitaxial material 311 (“An epitaxial layer 311” ¶ [0029]) changes by an order of magnitude (“the dopant concentration at the surface of the epitaxial layer 311 is about 1.times.10.sup.14 atoms/cm.sup.3 to about 5.times.10.sup.15 atoms/cm.sup.3, and changes in a gradient manner to the bottom surface of the epitaxial layer 311, which has a dopant concentration of about 5.times.10.sup.16 atoms/cm.sup.3 to about 5.times.10.sup.18 atoms/cm.sup.3 or more.” [0023]; The maximum change by an order of magnitude is 10000 between the top and bottom surface of 311) over a distance 355 (“The thickness 355 can be between about 2 µm and about 20 µm.” ¶ [0029]; Therefore, the gradient of the concentration vs the distance is (10000/20000 = 0.5), which is in the range of the claimed gradient of concentration vs distance (10/1000 = 0.01 or greater than .01, for the distances less than 1000 Angstroms) depending on the distance/thickness of the epitaxial layer) that is less than or equal to approximately 1000 Angstroms.
It would have been obvious to person having ordinary skill in the art before the effective filling date to modify the epitaxial layer of Sze with the gradient doping concentration of the epitaxial layer of Hong in order to narrow the depletion region at the pn junction. Additionally, the dopant gradient 350 creates a vertical electric field that serves to induce electrons toward the surface of the epitaxial layer 311 where such electrons can be collected by the photo-conversion device 23. (Although the photo-conversion device is depicted as a pinned photodiode, it could instead be another type of photo-conversion device, such as a non-pinned photodiode, or photogate, among others.) Accordingly, in addition to minimizing the loss of quantum efficiency at longer wavelengths, the invention also serves to maintain photon sensitivity and reduce image lag (Hong, ¶ [0026]).
With Regards to Claim 5, Sze discloses the limitations of claim 1. Sze further discloses, wherein the doped epitaxial layer 144 has a gradient doping concentration that decreases away from the base substrate (“In some embodiments, the buffer layer is comprised of a first material (e.g., germanium) and a second material (e.g., silicon) such that a concentration of the second material continuously decreases from an inner surface of the top isolation structure 142 to an outer surface of the active layer 146” ¶ [0067]; As layer 146 is further away from the substrate 103 and the concentration of the second material decreases to an outer surface of the 146, therefore doped epitaxial layer 144 has a gradient doping concentration that decreases away from the base substrate 103).
However, Sze does not disclose, does not explicitly disclose, wherein the doped epitaxial layer has a gradient doping concentration that decreases away from the base substrate.
In the similar field of endeavor of image sensor, Hong Figs. 4A-5C discloses, wherein the doped epitaxial layer 311 has a gradient doping concentration that decreases away (“The epitaxial layer has a dopant gradient, wherein the dopant concentration decreases from the bottom of the epitaxial layer adjacent the substrate to the surface of the epitaxial layer opposite the substrate.” ¶ [0009]) from the base substrate 312 (“The p-type epitaxial layer 311 dopant gradient 350 has a dopant concentration that increases from the upper surface of the epitaxial layer 311 toward the bottom surface of the epitaxial layer 311, which interfaces with the substrate 312” ¶ [0023]).
It would have been obvious to person having ordinary skill in the art before the effective filling date to modify the epitaxial layer of Sze with the gradient doping concentration of the epitaxial layer of Hong in order to narrow the depletion region at the pn junction. Additionally, the dopant gradient 350 creates a vertical electric field that serves to induce electrons toward the surface of the epitaxial layer 311 where such electrons can be collected by the photo-conversion device 23. (Although the photo-conversion device is depicted as a pinned photodiode, it could instead be another type of photo-conversion device, such as a non-pinned photodiode, or photogate, among others.) Accordingly, in addition to minimizing the loss of quantum efficiency at longer wavelengths, the invention also serves to maintain photon sensitivity and reduce image lag (Hong, ¶ [0026]).
Claims 3, 18-19 are rejected under 35 U.S.C. 103 as being unpatentable over Sze, Jhy-Jyi (US 20200105812 A1) “Sze” in view of Moriyama; Takashi (US 20160027825 A1) “Moriyama”.
With Regards to Claim 13, Sze discloses the limitations of claim 10. Sze Fig. 3B further discloses, However, Sze does not disclose, wherein the dopant has a gradient concentration along a line; and wherein the gradient concentration increases at a first rate within a part of the central region and at a second rate within a peripheral region of the epitaxial structure surrounding the central region, the first rate being larger than the second rate.
In the similar field of endeavor of image sensor, Moriyama Figs. 2-3 discloses wherein the dopant has a gradient concentration along a line (Fig. 2 shows the dopant has a gradient concentration along a line); and
wherein the gradient concentration increases at a first rate within a part of the central region (Fig. 2 shows a steep slope in the central part) and at a second rate within a peripheral region (Fig. 2 shows the slope of the curve is flatter in the portion right after the steep slope portion) of the epitaxial structure (“p-type semiconductor region 3 is the epitaxial layer formed on the p-type semiconductor region 2 by the epitaxial growth method.” ¶ [0026]) surrounding the central region, the first rate being larger than the second rate (Steeper portion of the curve with a higher slope is larger rate than the flat portion of the curve with lower slope).
It would have been obvious to person having ordinary skill in the art before the effective filling date to modify the epitaxial layer of Sze with the gradient doping concentration of the epitaxial layer of Moriyama so that charges generated in the deep position of the substrate are collected efficiently toward the surface (upper side) of the semiconductor region. Furthermore, the epitaxial growth method can form a semiconductor region with a low lattice defect density (Moriyama, ¶ [0026]).
With Regards to Claim 18, Sze discloses the limitations of claim 16. Sze Fig. 3B further discloses, However, Sze does not disclose, wherein a first concentration of the dopant within the epitaxial material increases at a larger rate than a second concentration of the dopant within the doped epitaxial layer.
In the similar field of endeavor of image sensor, Moriyama Figs. 2-3 discloses wherein a first concentration of the dopant within the epitaxial material increases at a larger rate than a second concentration of the dopant within the doped epitaxial layer (“p-type semiconductor region 3 is the epitaxial layer formed on the p-type semiconductor region 2 by the epitaxial growth method.” ¶ [0026]; Fig. 2 shows a steep slope in the central part; the slope of the curve is flatter in the portion right after the steep slope portion; Steeper portion of the curve with a higher slope is larger rate than the flat portion of the curve with lower slope).
It would have been obvious to person having ordinary skill in the art before the effective filling date to modify the epitaxial layer of Sze with the gradient doping concentration of the epitaxial layer of Moriyama so that charges generated in the deep position of the substrate are collected efficiently toward the surface (upper side) of the semiconductor region. Furthermore, the epitaxial growth method can form a semiconductor region with a low lattice defect density (Moriyama, ¶ [0026]).
With Regards to Claim 19, Sze discloses the limitations of claim 16. Sze Fig. 3B further discloses, However, Sze does not disclose, wherein a first concentration of the dopant within the epitaxial material varies over a first width and a second concentration of the dopant within the doped epitaxial layer varies over a second width that is larger than the first width.
In the similar field of endeavor of image sensor, Moriyama Figs. 1-3 discloses wherein a first concentration of the dopant within the epitaxial material (“the n-type semiconductor region 4 (epitaxial layer) provided on the p-type semiconductor region 3” ¶ [0027]) varies over a first width (Width of layer 4 in Figs. 1-2) and a second concentration of the dopant within the doped epitaxial layer (“p-type semiconductor region 3 is the epitaxial layer formed on the p-type semiconductor region 2 by the epitaxial growth method.” ¶ [0026]) varies over a second width (Width of layer 3 in Figs. 1-2) that is larger than the first width (Figs. 1-2 shows width of 3 is larger than width of 4).
It would have been obvious to person having ordinary skill in the art before the effective filling date to modify the epitaxial layer of Sze with the gradient doping concentration and width of the epitaxial layer of Moriyama so that charges generated in the deep position of the substrate are collected efficiently toward the surface (upper side) of the semiconductor region. Furthermore, the epitaxial growth method can form a semiconductor region with a low lattice defect density (Moriyama, ¶ [0026]) and to be a thickness that can control the impurity concentration distribution at high precision by ion implantation (Moriyama, ¶ [0034]).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to AKHEE SARKERNAG whose telephone number is (703)756-4655. The examiner can normally be reached Monday - Friday 7:15 AM to 5:30 PM.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, YARA J. GREEN can be reached on (571) 270-3035. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/AKHEE SARKER-NAG/Examiner, Art Unit 2893
/YARA B GREEN/Supervisor Patent Examiner, Art Unit 2893
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