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 .
Allowable Subject Matter
Claims 22, 23, 26, 30 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.
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim(s) 1, 2, 4-7, 11, 12, 16, 17, 19, 31 is/are rejected under 35 U.S.C. 103 as being unpatentable over Laflaquière et al. (US 11418006 B1) hereafter referred to as Laflaquière in view of Kouvetakis et al. (US 20130313579 A1) hereafter referred to as Kouvetakis. Akselrod et al. (US 20210141060 A1) hereafter referred to as Akselrod is provided as evidence.
In regard to claim 1 Laflaquière teaches a photodiode detector [see Fig. 6A, 6B “The resonant cavity defined by the upper and lower DBR stacks enhances the absorption by the quantum well structure of the reflected photons that are received at the resonant emission frequency, while blocking background photons outside the resonance band”, see it is photodiode, it has p type at the top and n type at the bottom, “substrate 30, such as a silicon die”] comprising:
an optical cavity comprising [ “upper and lower DBR stacks together define an optical cavity containing quantum well structure 40 and having a selected resonant frequency at which the quantum wells emit, for example 940 nm”] an overlying light-receiving portion [“upper, solid curve in FIG. 3B shows absorption of photons that are normally incident on upper DBR stack 42”] and an underlying mirror [“lower DBR stack 44” “Upper and lower DBR stacks 42 and 44 comprise multiple alternating layers of high and low refractive index, such as alternating layers of Al.sub.aGa.sub.1-aAs (a<0.5) and Al.sub.bGa.sub.1-bAs (b>0.5), as is known in the art”];
a absorption layer [“FIG. 6B shows details of quantum well structure 40 and the associated sub-layers in device 70. In the present example, these sub-layers are made from GaAs and alloys of GaAs, as noted earlier, and have respective thicknesses in the range of 10-100 nm, depending on design parameters. The quantum well layer itself is marked as the “absorption layer” in FIG. 6B” “Optically-active structure 28 may also comprise a multiplication layer in proximity to quantum well structure 40 (as shown in FIG. 6B), which gives rise, during phase 3, to avalanche amplification of photocurrent induced due to absorption of photons in quantum well structure 40”]; and
a multiplier layer [see Fig. 6B “multiplication layer”] disposed adjacent [it is noted that adjacent does not mean touching] to the absorption layer,
wherein the absorption layer is disposed within the optical cavity [see between Upper and lower DBR stacks 42 and 44] and arranged between [see Fig. 6A, 6B] the overlying light-receiving portion and the multiplier layer,
the multiplier layer is arranged between [see Fig. 6A, 6B] the absorption layer and the underlying mirror,
the overlying light-receiving portion is configured to receive light [“In phase 3, optical pulse 52 has reflected from target 54 back through upper DBR stack 42 to quantum well structure 40. The incident photons cause optically-active structure 28 to output an electrical pulse to drive and detection circuit 32”] to be detected by the photodiode detector, and
the optical cavity is configured to confine [“the optical cavity defined by upper and lower DBR stacks 42 and 44 has a resonant wavelength” “The upper, solid curve in FIG. 3B shows absorption of photons that are normally incident on upper DBR stack 42 (i.e., along an axis perpendicular to the outer surface), whereas the lower, dashed curve shows absorption of photons that are incident 10° from the normal. The plot illustrates the high directional selectivity of the absorption by optically-active structure 28, as well as the high quantum efficiency that is achievable as a result of the resonant detection geometry: For normal incidence and proper design of quantum well structure 40, the quantum efficiency reaches 70%” see that because the photons received are those emitted by the resonant cavity, the received photons also resonate and inherently there is a standing wave. The Examiner notes that even if the Applicant claims recognition of the standing wave, the fact that the inventor has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious. See Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985)] the received light in the absorption layer in a form of a standing wave propagating between [see Fig. 6A, 6B] the overlying light-receiving portion and the underlying mirror along a longitudinal axis of the optical cavity.
but does not state that the absorption layer is GeSn.
See Akselrod is provided as evidence, see paragraph 0034 “Specific examples of operating wavelengths suitable for lidar include operating wavelengths of 850 nanometers, 905 nanometers, 940 nanometers, and 1550 nanometers”.
It is noted that epitaxy is ordered growth and CVD is ordered growth, CVD is a form of epitaxy.
See Kouvetakis teaches see Fig. 2A, Fig. 4 “FIG. 4 show the responsivities of heterostructure pin diodes on n-type Si substrates”, see paragraph 0017 “the present disclosure provides photodiodes comprising a doped substrate having a surface layer; an intrinsic Ge(Sn) alloy layer formed directly over the Si surface layer; and a second Ge(Sn) alloy layer directly over the intrinsic Ge(Sn) alloy layer, wherein one of the substrate surface layer and the second Ge(Sn) alloy layer is p-doped and the other is n-doped” “dopant levels of Sn in the Ge(Sn) alloys can be incorporated at temperatures between about 370.degree. C. and about 420.degree. C., to yield layers that can be atomically smooth and/or devoid of threading defects. Such growth conditions are more compatible with CMOS processing” “Using the Sn concentration as an adjustable parameter, large increases in responsivity can be achieved while keeping the growth temperature at very low values compatible with CMOS processing” “The results suggest that Sn-doped Ge has an intriguing potential in the field of silicon photonics” “Photonic circuit elements may comprise a photodiode as described above, or any embodiment thereof, and a waveguiding structure in optical communication with the photodiode”. See Kouvetakis teaches in Fig. 2A see that the contact to the lower doped region i.e. n-Silicon can be made from the top. See Kouvetakis paragraphs 0007-0017 “Ge-like materials incorporating very low Sn (e.g., 0.05-0.3% Sn range; about 7-13.times.10.sup.19 atoms/cm.sup.3) are illustrated” “higher Sn-content GeSn alloys, such as Ge.sub.0.98Sn.sub.0.02” “Ge.sub.1-xSn.sub.x, wherein x is greater than 0 and less than 0.01 (e.g, greater than 0 and less than or equal to about 0.003, such as, between about 0.0005 and about 0.003)” see Kouvetakis paragraph 0005, 0176 “the doping-level amounts of Sn are sufficient to engineer the optical properties of Ge around the critical 1550 nm wavelength” “using the known compositional dependence of the direct band gap, it is estimated that only 0.2% of Sn is needed to double the room-temperature absorption coefficient at 1550 nm relative to pure Ge” , see paragraph 0183 “deposition experiments were performed at low temperatures of 390-400.degree. C. and 0.300 Torr pressure using ultra high vacuum chemical vapor deposition (UHV CVD) methods and protocols similar to those described above” see Kouvetakis paragraphs 0077-0082, 0104-0109, 0112 “p-Type Ge(Sn) alloy layers can be prepared by the controlled substitution of B, Al, or Ga atoms in the Ge(Sn) alloy lattice according to methods known to those skilled in the art. One example includes, but is not limited to, conventional CVD or MBE of SnD.sub.4, Ge.sub.2H.sub.6 and B.sub.2H.sub.6 at low temperatures”.
The Examiner notes that a person of ordinary skill in the art knows that Si and Ge can be used to form Bragg reflectors due to their difference in refractive index for use in Si, Ge, Sn based device.
Thus, it 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 to modify Laflaquière to include that the absorption layer is GeSn.
Thus it would be obvious to combine the references to arrive at the claimed invention.
The motivation is to obtain desired bandgap of absorption material using standard compound semiconductor design to obtain capability to use longer wavelength such as 1550 nm.
In regard to claim 2 Laflaquière and Kouvetakis as combined teaches wherein the overlying light- receiving portion is a surface [see combination, see that light comes from the top, see that the light propagates vertically up-down in the device, passing through each surface which receives the light, and similarly each portion of the standing wave is a standing wave] of the GeSn absorption layer, and the underlying mirror has a refractive index [it is different because it is a DBR stack] different from a refractive index of the GeSn absorption layer surface.
In regard to claim 4 Laflaquière and Kouvetakis as combined teaches wherein the photodiode detector is an avalanche [see Laflaquière “Quantum well structure 40 absorbs the photons, giving rise to a pulse of photocurrent, which may be amplified by avalanche multiplication assuming the reverse bias voltage is sufficient”] photodiode detector; and/or wherein the photodiode detector further comprises a substrate having a planar surface [see Laflaquière Fig. 6A] ,the optical cavity is being arranged extending upwardly from [see Laflaquière Fig. 6A] the planar surface, with the underlying mirror being adjacent to [see Laflaquière Fig. 6A] the substrate or with the substrate forming an integrated part of the underlying mirror.
In regard to claim 5 Laflaquière and Kouvetakis as combined teaches wherein the underlying mirror is [“lower DBR stack 44” “Upper and lower DBR stacks 42 and 44 comprise multiple alternating layers of high and low refractive index, such as alternating layers of Al.sub.aGa.sub.1-aAs (a<0.5) and Al.sub.bGa.sub.1-bAs (b>0.5), as is known in the art” see combination Si and Ge can be used to form Bragg reflectors due to their difference in refractive index for use in Si, Ge, Sn based device] a distributed Bragg reflector, and the overlying light-receiving portion comprises [see Laflaquière Fig. 6B the layers above Absorption can be called as “passivation” under broadest reasonable interpretation] a passivation layer.
In regard to claim 6 Laflaquière and Kouvetakis as combined teaches wherein the underlying mirror is a first distributed Bragg reflector [“Upper and lower DBR stacks 42 and 44 comprise multiple alternating layers of high and low refractive index, such as alternating layers of Al.sub.aGa.sub.1-aAs (a<0.5) and Al.sub.bGa.sub.1-bAs (b>0.5), as is known in the art” see combination Si and Ge can be used to form Bragg reflectors due to their difference in refractive index for use in Si, Ge, Sn based device], and the overlying light-receiving portion is a second distributed Bragg reflector.
In regard to claim 31 Laflaquière and Kouvetakis as combined teaches wherein each of the first distributed Bragg reflector and the second distributed Bragg reflector comprises [“Upper and lower DBR stacks 42 and 44 comprise multiple alternating layers of high and low refractive index, such as alternating layers of Al.sub.aGa.sub.1-aAs (a<0.5) and Al.sub.bGa.sub.1-bAs (b>0.5), as is known in the art” see combination Si and Ge can be used to form Bragg reflectors due to their difference in refractive index for use in Si, Ge, Sn based device] a dielectric distributed Bragg reflector or a semiconductor distributed Bragg reflector.
In regard to claim 7 Laflaquière and Kouvetakis as combined teaches wherein the first distributed Bragg reflector and the second distributed Bragg reflector comprise [“Upper and lower DBR stacks 42 and 44 comprise multiple alternating layers of high and low refractive index, such as alternating layers of Al.sub.aGa.sub.1-aAs (a<0.5) and Al.sub.bGa.sub.1-bAs (b>0.5), as is known in the art” see combination Si and Ge can be used to form Bragg reflectors due to their difference in refractive index for use in Si, Ge, Sn based device] one of the following:same number of material pairs; or different numbers of material pairs; or same type of material pairs; or different types of material pairs.
In regard to claim 11 Laflaquière and Kouvetakis as combined teaches wherein the distributed Bragg reflector comprises [“Upper and lower DBR stacks 42 and 44 comprise multiple alternating layers of high and low refractive index, such as alternating layers of Al.sub.aGa.sub.1-aAs (a<0.5) and Al.sub.bGa.sub.1-bAs (b>0.5), as is known in the art” see combination Si and Ge can be used to form Bragg reflectors due to their difference in refractive index for use in Si, Ge, Sn based device] a dielectric distributed Bragg reflector or a semiconductor distributed Bragg reflector.
In regard to claim 12 Laflaquière and Kouvetakis as combined teaches wherein the multiplier layer comprises [see combination it is a Si device with GeSn Absorber] a Si multiplier layer; and/or wherein an anode of the photodiode detector comprises a first metal contact for external electrical connection, the first metal contact overlying at least part of a positively doped p region of the GeSn absorption layer; and a cathode of the photodiode detector comprises a second metal contact for external electrical connection, the second metal contact overlying at least part of a negatively doped n region of the multiplier layer.
In regard to claim 16 Laflaquière and Kouvetakis as combined teaches [see combination see Kouvetakis paragraphs 0007-0017 “Ge-like materials incorporating very low Sn (e.g., 0.05-0.3% Sn range; about 7-13.times.10.sup.19 atoms/cm.sup.3) are illustrated” “higher Sn-content GeSn alloys, such as Ge.sub.0.98Sn.sub.0.02” “Ge.sub.1-xSn.sub.x, wherein x is greater than 0 and less than 0.01 (e.g, greater than 0 and less than or equal to about 0.003, such as, between about 0.0005 and about 0.003)”] wherein the GeSn absorption layer has at least one of the following:a Sn content of near 0% to about 11%; or a thickness of more than 100 nm.
In regard to claim 17 Laflaquière and Kouvetakis as combined does not specifically teach wherein the GeSn absorption layer has the Sn content of about 3 % to 4% to enhance absorption coefficient at a wavelength of 1550 nm, or about 10% to enhance absorption coefficient at a wavelength of 2000 nm.
However see Kouvetakis Figs 3A-Fig. 16 see the effect of varying Sn concentration, see variation of optical behavior with Sn, see 1550 nm and 2000 nm are shown in the figures in the X axis see also energy is shown on the X axis.
It 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 to use “wherein the GeSn absorption layer has the Sn content of about 3 % to 4% to enhance absorption coefficient at a wavelength of 1550 nm, or about 10% to enhance absorption coefficient at a wavelength of 2000 nm.”, since it has been held that where the general conditions of a claim are disclosed in the prior art, discovering the optimum or working ranges involves only routine skill in the art. In re Aller, 105 USPQ 233
In regard to claim 19 Laflaquière and Kouvetakis as combined does not specifically teach wherein the underlying mirror has a thickness sufficient to provide about 0.5 reflectivity or more at a wavelength of 1550 nm or 2000 nm.
However see that the Bragg reflectance is a known equation to a person of ordinary skill in the art, and that relectance increases with number of periods, see combination Si and Ge can be used to form Bragg reflectors due to their difference in refractive index for use in Si, Ge, Sn based device.
See Laflaquière “The plot relates to photons at the resonant wavelength of the optical cavity, for example 940 nm” it is an example, see “FIG. 3A is a schematic plot of a reflectance spectrum of optically-active structure 28, calculated as a function of wavelength”, see in Fig. 3A reflectivity as high as 1, see Kouvetakis paragraph 0176 “the doping-level amounts of Sn are sufficient to engineer the optical properties of Ge around the critical 1550 nm wavelength”.
Thus, it 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 to modify Laflaquière to include that wherein the underlying mirror has a thickness sufficient to provide about 0.5 reflectivity or more at a wavelength of 1550 nm or 2000 nm.
Thus it would be obvious to combine the references to arrive at the claimed invention.
The motivation is to obtain good reflection of the photons back to avoid wasting photons at all desired wavelengths for example longer wavelengths.
Claim(s) 20, 21, 25, 32 is/are rejected under 35 U.S.C. 103 as being unpatentable over Laflaquière et al. (US 11418006 B1) hereafter referred to as Laflaquière in view of Kouvetakis et al. (US 20130313579 A1) hereafter referred to as Kouvetakis. Akselrod et al. (US 20210141060 A1) hereafter referred to as Akselrod is provided as evidence.
In regard to claim 20 Laflaquière teaches a method of fabricating a photodiode detector [see Fig. 6A, 6B “The resonant cavity defined by the upper and lower DBR stacks enhances the absorption by the quantum well structure of the reflected photons that are received at the resonant emission frequency, while blocking background photons outside the resonance band”, see it is photodiode, it has p type at the top and n type at the bottom] the method comprising:
forming a first wafer comprising [see Fig. 6A, see 30 and 44 “substrate 30, such as a silicon die”] an underlying mirror [“lower DBR stack 44” “Upper and lower DBR stacks 42 and 44 comprise multiple alternating layers of high and low refractive index, such as alternating layers of Al.sub.aGa.sub.1-aAs (a<0.5) and Al.sub.bGa.sub.1-bAs (b>0.5), as is known in the art”];
growing a multiplier layer [see Fig. 6B “multiplication layer” see epitaxial growth, “Optically-active structure 28 comprises multiple epitaxial layers, defining a quantum well structure 40 with P- and N-doped layers above and below it”] over the underlying mirror;
forming a absorption layer [“FIG. 6B shows details of quantum well structure 40 and the associated sub-layers in device 70. In the present example, these sub-layers are made from GaAs and alloys of GaAs, as noted earlier, and have respective thicknesses in the range of 10-100 nm, depending on design parameters. The quantum well layer itself is marked as the “absorption layer” in FIG. 6B” “Optically-active structure 28 may also comprise a multiplication layer in proximity to quantum well structure 40 (as shown in FIG. 6B), which gives rise, during phase 3, to avalanche amplification of photocurrent induced due to absorption of photons in quantum well structure 40”] over the first wafer; and
forming an overlying light-receiving portion [see Fig. 6B light enters from the top and passes vertically up-down, “upper, solid curve in FIG. 3B shows absorption of photons that are normally incident on upper DBR stack 42” see epitaxial growth, “Optically-active structure 28 comprises multiple epitaxial layers, defining a quantum well structure 40 with P- and N-doped layers above and below it”] over the absorption layer,
wherein the photodiode detector comprises an optical cavity [“upper and lower DBR stacks together define an optical cavity containing quantum well structure 40 and having a selected resonant frequency at which the quantum wells emit, for example 940 nm”] including the overlying light-receiving portion and the underlying mirror,
such that when in use, the overlying light- receiving portion receives light to be detected [“In phase 3, optical pulse 52 has reflected from target 54 back through upper DBR stack 42 to quantum well structure 40. The incident photons cause optically-active structure 28 to output an electrical pulse to drive and detection circuit 32”] by the photodiode detector, and the optical cavity confines [“the optical cavity defined by upper and lower DBR stacks 42 and 44 has a resonant wavelength” “The upper, solid curve in FIG. 3B shows absorption of photons that are normally incident on upper DBR stack 42 (i.e., along an axis perpendicular to the outer surface), whereas the lower, dashed curve shows absorption of photons that are incident 10° from the normal. The plot illustrates the high directional selectivity of the absorption by optically-active structure 28, as well as the high quantum efficiency that is achievable as a result of the resonant detection geometry: For normal incidence and proper design of quantum well structure 40, the quantum efficiency reaches 70%” see that because the photons received are those emitted by the resonant cavity, the received photons also resonate and inherently there is a standing wave. The Examiner notes that even if the Applicant claims recognition of the standing wave, the fact that the inventor has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious. See Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985)] the received light in the absorption layer in a form of a standing wave propagating between [see Fig. 6A, 6B see that light comes from the top, see that the light propagates vertically up-down in the device, passing through each surface and similarly each portion of the standing wave is a standing wave] the overlying light-receiving portion and the underlying mirror along a longitudinal axis of the optical cavity,
but does not state “using reduced pressure chemical vapour deposition” and that the absorption layer is GeSn.
See Akselrod is provided as evidence, see paragraph 0034 “Specific examples of operating wavelengths suitable for lidar include operating wavelengths of 850 nanometers, 905 nanometers, 940 nanometers, and 1550 nanometers”.
It is noted that epitaxy is ordered growth and CVD is ordered growth, CVD is a form of epitaxy.
See Kouvetakis teaches see Fig. 2A, Fig. 4 “FIG. 4 show the responsivities of heterostructure pin diodes on n-type Si substrates”, see paragraph 0017 “the present disclosure provides photodiodes comprising a doped substrate having a surface layer; an intrinsic Ge(Sn) alloy layer formed directly over the Si surface layer; and a second Ge(Sn) alloy layer directly over the intrinsic Ge(Sn) alloy layer, wherein one of the substrate surface layer and the second Ge(Sn) alloy layer is p-doped and the other is n-doped” “dopant levels of Sn in the Ge(Sn) alloys can be incorporated at temperatures between about 370.degree. C. and about 420.degree. C., to yield layers that can be atomically smooth and/or devoid of threading defects. Such growth conditions are more compatible with CMOS processing” “Using the Sn concentration as an adjustable parameter, large increases in responsivity can be achieved while keeping the growth temperature at very low values compatible with CMOS processing” “The results suggest that Sn-doped Ge has an intriguing potential in the field of silicon photonics” “Photonic circuit elements may comprise a photodiode as described above, or any embodiment thereof, and a waveguiding structure in optical communication with the photodiode”. See Kouvetakis teaches in Fig. 2A see that the contact to the lower doped region i.e. n-Silicon can be made from the top. See Kouvetakis paragraphs 0007-0017 “Ge-like materials incorporating very low Sn (e.g., 0.05-0.3% Sn range; about 7-13.times.10.sup.19 atoms/cm.sup.3) are illustrated” “higher Sn-content GeSn alloys, such as Ge.sub.0.98Sn.sub.0.02” “Ge.sub.1-xSn.sub.x, wherein x is greater than 0 and less than 0.01 (e.g, greater than 0 and less than or equal to about 0.003, such as, between about 0.0005 and about 0.003)” see Kouvetakis paragraph 0005, 0176 “the doping-level amounts of Sn are sufficient to engineer the optical properties of Ge around the critical 1550 nm wavelength” “using the known compositional dependence of the direct band gap, it is estimated that only 0.2% of Sn is needed to double the room-temperature absorption coefficient at 1550 nm relative to pure Ge” , see paragraph 0183 “deposition experiments were performed at low temperatures of 390-400.degree. C. and 0.300 Torr pressure using ultra high vacuum chemical vapor deposition (UHV CVD) methods and protocols similar to those described above” see Kouvetakis paragraphs 0077-0082, 0104-0109, 0112 “p-Type Ge(Sn) alloy layers can be prepared by the controlled substitution of B, Al, or Ga atoms in the Ge(Sn) alloy lattice according to methods known to those skilled in the art. One example includes, but is not limited to, conventional CVD or MBE of SnD.sub.4, Ge.sub.2H.sub.6 and B.sub.2H.sub.6 at low temperatures” see Kouvetakis teaches low pressure CVD “In various further embodiments, the vapor is introduced at a partial pressure a pressure between about 1 mTorr and about 1000 mTorr. In one embodiment, the vapor is introduced at a pressure between about 100 mTorr and about 1000 mTorr. In one embodiment, the vapor is introduced at a pressure between about 100 mTorr and about 500 mTorr. In one embodiment, the vapor is introduced at a pressure between about 200 mTorr and about 500 mTorr. In one embodiment, the vapor is introduced at a pressure between about 250 mTorr and about 400 mTorr. In one embodiment, the vapor is introduced at a pressure of about 300 mTorr”.
The Examiner notes that a person of ordinary skill in the art knows that Si and Ge can be used to form Bragg reflectors due to their difference in refractive index for use in Si, Ge, Sn based device.
Thus, it 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 to modify Laflaquière to include that “using reduced pressure chemical vapour deposition” and that the absorption layer is GeSn.
Thus it would be obvious to combine the references to arrive at the claimed invention.
The motivation is to obtain desired bandgap of absorption material using standard compound semiconductor design to obtain capability to use longer wavelength such as 1550 nm, and that reduced pressure chemical vapour deposition is standard in the art of epitaxial growth gives excellent results to form excellent quality layers for use in semiconductor devices.
In regard to claim 21 Laflaquière and Kouvetakis as combined teaches wherein the step of forming the GeSn absorption layer over the first wafer comprises one of the following:(a) forming a second wafer comprising the GeSn absorption layer; and wafer-bonding the first wafer and the second wafer, wherein the GeSn absorption layer on the second wafer is facing toward the first wafer; or (b) growing the GeSn absorption layer and a p++ GeSn top contact layer [see combination Kouvetakis, see paragraph 0183 “deposition experiments were performed at low temperatures of 390-400.degree. C. and 0.300 Torr pressure using ultra high vacuum chemical vapor deposition (UHV CVD) methods and protocols similar to those described above”, see that p++ is relative term, see “Electrode 48 contacts a P-doped contact layer 72 at the lower side of upper DBR stack 42, while electrode 50 contacts an N-doped contact layer 74 at the upper side of lower DBR stack 44”] over the first wafer using reduced pressure chemical vapour deposition.
In case the Applicant wishes to argue that p++ has special meaning, it 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 to modify Laflaquière to include that “p++”.
Thus it would be obvious to combine the references to arrive at the claimed invention.
The motivation is higher doping gives good conductivity for the contact.
In regard to claim 25 Laflaquière and Kouvetakis as combined teaches metal contacts, see Fig. 6A p-metal and n-metal however does not state further comprising at least one of the following: prior to the step of forming the first wafer, fabricating the underlying mirror using a double- SOI process; or after forming the overlying light-receiving portion over the GeSn absorption layer, forming two metal contacts for external electrical connections of the photodiode detector, using a metal deposition process, or a process comprising photolithography, electron-beam deposition, and subsequent lift-off process.
See Kouvetakis metal contact touches the lower doped layer from the top, see paragraph 0196 “Cr/Au metal contacts were deposited by e-beam and defined by lithography”.
Thus it 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 to modify Laflaquière to include further comprising at least one of the following: prior to the step of forming the first wafer, fabricating the underlying mirror using a double- SOI process; or after forming the overlying light-receiving portion over the GeSn absorption layer, forming two metal contacts for external electrical connections of the photodiode detector, using a metal deposition process, or a process comprising photolithography, electron-beam deposition, and subsequent lift-off process.
Thus it would be obvious to combine the references to arrive at the claimed invention.
The motivation is that these are standard metal forming techniques known to give good results to form contacts for semiconductor devices.
In regard to claim 32 Laflaquière and Kouvetakis as combined teaches further comprising prior to the step of forming the two metal contacts, patterning a mesa [see Fig. 6A layers of 72 and under are a mesa and the 42 is another mesa] on at least portion of the photodiode detector.
Response to Arguments
Applicant's arguments filed 1/9/2026 have been fully considered but they are not persuasive.
Applicant’s arguments with respect to claim(s) 1-32 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
The Examiner notes that the primary reference to address amended claims is Laflaquière.
On page 10 the Applicant argues “structure of Meyers, the p-type region 105 and bottom mirror 103 do notform an "optical cavity configured to confine the received light in the GeSn absorption layer in a form of a standing wave propagating between the overlying light-receiving portion and the underlying mirror along a longitudinal axis of the optical cavity," as required by currently amended claim 1. This element is shown by the black arrows inserted into FIG. 4 of the present application (as reproduced below). Applicant further submits that the device of Meyers having the thin light absorbing region being a single type-II InAs- GaSb interface or a QW structure teaches away from the photodiode detector as claimed in currently amended claim 1”.
The Examiner disagrees, see that in Meyers Fig. 1 “top and bottom mirrors 103/108 form a resonant cavity 100 that significantly enhances the net absorption for high QE”, the reflection is up-down.
On page 13 the Applicant argues “Applicant highlights that as described in the Specification, a vertical optical cavity is introduced to sandwich the conventional separate absorption and carrier multiplication (SACM) structure of SPAD (i.e. the optical cavity configured to confine the received light in the GeSn absorption layer in a form of a standing wave propagating between the overlying light- receiving portion and the underlying mirror along a longitudinal axis of the optical cavity) to advantageously enhance the absorption efficiency (approaching 100%) and thin the absorption layer as well, which makes the SPAD with high detection efficiency, low noise and high photon timing possible. See Specification at 11 [0093]-[0096]. The photodiode detector has other advantages such as broad detection wavelength coverage up to 2500 nm, and compatibility with Si-CMOS technology with ease to be scaled down, leading to low costs of the devices. See id. For at least the above reasons, Applicant submits that Meyers, Kouvetakis, and Yue fail to teach or suggest amended independent Claims 1 and 20”.
The Examiner notes that the primary reference to address amended claims is Laflaquière.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
M. Ghioni, teaches "Resonant-Cavity-Enhanced Single-Photon Avalanche Diodes on Reflecting Silicon Substrates".
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to SITARAMARAO S YECHURI whose telephone number is (571)272-8764. The examiner can normally be reached M-F 8:00-4:30 PM.
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/SITARAMARAO S YECHURI/ Primary Examiner, Art Unit 2893