DETAILED ACTION
Claim Rejections - 35 USC § 103
The following is a quotation of AIA 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1, 3-8, 10-15, 17-20 are rejected under 35 U.S.C. 103 as being unpatentable by Park (US 20220254946 A1) in view of Mazzillo (US 20170098730 A1).
Re: Independent Claim 1, Park discloses a structure (annotated Figs. 2A-B) comprising:
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a diode photodetector (¶ [0002] disclosing a single photon avalanche diode, a type of photodetector) including an anode (112) within a doped well (doped well 124) and a cathode (114) within the doped well (124); and
a guard ring (116) within the doped well and between the cathode and the anode (Figs. 2A-B), wherein a semiconductor material of the guard ring and the doped well have opposite doping types (116 is of first conductive type, ¶ [0040], doped well 124 is of second conductive type, ¶ [0041]).
Park is silent regarding a plurality of guard ring contacts each electrically coupling a different biasing voltage to a respective one of a plurality of the guard ring regions, wherein the guard ring contact electrically biases the respective region of the guard ring thereunder and the plurality of guard ring regions are each coupled to one of the different biasing voltages through one of the plurality of guard ring contacts.
Mazzillo, in the same field of endeavor, discloses (Fig. 29, [0072-0073]) an avalanche photodiode for detecting ultraviolet radiation comprising a cathode (8) surrounding a guard ring (16) and the guard ring contiguously surrounding an anode (12), the guard ring is provided with electrical contacts (30, 35) and electrical probes (Fig. 1) for biasing the PNI junction (¶¶ [0035, 0038]).
Adding the conductive contact to the guard ring would have ensured sufficient contact area for a low resistance connection between the PN junction, thus facilitating the flow of current and enabling the device to function properly. Biasing each of the contacts with different biasing voltage is intended use and it does not change the structure of the diode.
Therefore, one of ordinary skill in the art before the filing date of the invention would have incorporated the metal contact to the guarding for electrical biasing as taught by Mazzillo into the photodiode of Park to achieve better electrical connection and device performance.
Re: Claim 3, Park in view of Mazzillo discloses the structure of claim 1, wherein the guard ring horizontally surrounds the anode (Figs. 2A, 2B).
Re: Claim 4, Park in view of Mazzillo discloses the structure of claim 3, wherein the cathode horizontally surrounds the guard ring (Figs. 2A, 2B).
Re: Claim 5, Park in view of Mazzillo discloses the structure of claim 1, wherein the guard ring includes a lower surface vertically between a lower surface of the anode and a lower surface of the cathode (Park: Fig. 2B and ¶ [40] disclosing depth of guard ring 116 is greater than depth of anode region 112 but less than depth of region 114).
Re: Claim 6, Park in view of Mazzillo discloses the structure of claim 1, wherein the doped well is in one of a bulk semiconductor substrate and a semiconductor layer of a semiconductor on insulator (SOI) substrate (Park: ¶ [0025] disclosing the substrate Sub is a silicon-on-insulation (SOI) wafer and doped well region 124 is in the substrate Sub).
Re: Claim 7, Park in view of Mazzillo discloses the structure of claim 1, wherein the semiconductor material of the guard ring and the anode have a same doping type, and wherein a dopant concentration in the anode is greater than a dopant concentration in the semiconductor material of the guard ring (Park: ¶ [0040] discloses anode region 112 and guard ring 116 have same first conductive type and 116 has less doping concentration than that of 112).
Re: Independent Claim 8, Park discloses a structure (annotated Figs. 2A, 2B above) comprising:
a doped well (124) within a substrate (Sub S1);
a diode photodetector (2) within the substrate, the diode photodetector including:
an anode (112) within a first portion of the doped well and having an anode contact (Anode1) thereto,
a cathode (114) within a second portion of the doped well and having a cathode contact (Cathode1) thereto, wherein the cathode is horizontally distal to the anode within the doped well; and
a guard ring (116) including a semiconductor material (first doping type, ¶ [0040) within the doped well between the cathode and the anode (see Figs. 2A-B), wherein the semiconductor material and the doped well have opposite doping types (124 has second doping type, ¶ [0041]).
Park is silent regarding a plurality of guard ring contacts electrically coupling a different biasing voltage to a respective one of a plurality of the guard ring regions, wherein the guard ring contact electrically biases the respective region of the guard ring thereunder and the plurality of guard ring regions are each coupled to one of the different biasing voltages through one of the plurality of guard ring contacts.
Mazzillo, in the same field of endeavor, discloses (Fig. 29, ¶¶ [0072-0073]) an avalanche photodiode for detecting ultraviolet radiation comprising a cathode (8) surrounding a guard ring (16) and the guard ring contiguously surrounding an anode (12), the guard ring is provided with electrical contacts (30, 35) and electrical probes (Fig. 1) for biasing the PNI junction (¶¶ [0035, 0038]).
Adding the conductive contact to the guard ring would have ensured sufficient contact area for a low resistance connection between the PN junction, thus facilitating the flow of current and enabling the device to function properly. Biasing each of the contacts with different biasing voltage is intended use and it does not change the structure of the diode.
Therefore, one of ordinary skill in the art before the filing date of the invention would have incorporated the metal contact to the guarding for electrical biasing as taught by Mazzillo into the photodiode of Park to achieve better electrical connection and device performance.
Re: Claim 10, Park in view of Mazzillo discloses the structure of claim 8, wherein the guard ring horizontally surrounds the anode (see Figs. 2A, 2B and ¶ [0038]).
Re: Claim 11, Park in view of Mazzillo discloses the structure of claim 10, wherein the cathode horizontally surrounds the guard ring (see Figs. 2A, 2B).
Re: Claim 12, Park in view of Mazzillo discloses the structure of claim 8, wherein the guard ring includes a lower surface vertically between a lower surface of the anode and a lower surface of the cathode (Park: Fig. 2B and ¶ [0040] disclosing bottom surface of 116 is greater than bottom surface of 112 and bottom surface of 116 is lower than bottom surface of region 114).
Re: Claim 13, Park in view of Mazzillo discloses the structure of claim 8, wherein the doped well is in one of a bulk semiconductor substrate and a semiconductor layer of a semiconductor on insulator (SOI) substrate (Park: ¶ [0025] disclosing substrate Sub is a semiconductor-on-insulator substrate and the region 124 is in the substrate).
Re: Claim 14, Park in view of Mazzillo discloses the structure of claim 8, wherein the semiconductor material and the anode have a same doping type, and wherein a dopant concentration in the anode is greater than a dopant concentration in the semiconductor material (Park: ¶ [0040] disclosing guard ring 116 and anode 112 are of the same conductive type and 116 has less doping concentration than that of 112).
Re: Independent Claim 15, Park discloses a method (¶ [0008]) comprising:
forming a diode photodetector (¶ [0002]) including
an anode (Figs. 2A, 2B and ¶¶ [0034, 0036] disclosing forming impurity region 112 and Anode1)
within a doped well (Figs. 2A, 2B and ¶ [0047] disclosing forming impurity region 124)
and a cathode (Figs. 2A, 2B and ¶ [0034,0036] disclosing forming second impurity region 114 Cathode1) within the doped well;
forming a guard ring (Figs. 2A, 2B and ¶ [ 0040] disclosing forming impurity region 116) within the doped well and between the cathode and the anode (¶¶ [0040-0041] ¶ [0041] disclosing doped), wherein a semiconductor material of the guard ring and the doped well have opposite doping types (¶ [0040] disclosing guard ring 116 having the first conductive type; ¶ [0041] disclosing the doped well 124 having the second conductive type).
Park is silent regarding the guard ring electrically coupling a plurality of guard ring contacts to a respective one of a plurality of the guard ring regions, wherein the guard ring contact electrically biases the respective region of the guard ring thereunder and the plurality of guard ring regions are each coupled to one of the different biasing voltages through one of the plurality of guard ring contact.
Mazzillo discloses a method (¶ [0011]) of forming a photodiode (Fig. 29, ¶¶ [0072-0073]) comprising forming a guard ring (16) between anode (12) and cathode (8) concentrically, and forming the metal contacts (30, 35) in direct to the guard ring for electrical biasing the PNI junction (¶¶ [0035, 0038]).
Adding the conductive contact to the guard ring would have ensured sufficient contact area for a low resistance connection between the PN junction, thus facilitating the flow of current and enabling the device to function properly. Biasing each of the contacts with different biasing voltage is intended use and it does not change the structure of the diode.
Therefore, one of ordinary skill in the art before the filing date of the invention would have incorporated the metal contact to the guarding for electrical biasing as taught by Mazzillo into the photodiode of Park to achieve better electrical connection and device performance.
Re: Claim 17, Park in view of Mazzillo discloses the method of claim 15, further comprising applying a bias voltage to the semiconductor material through the guard ring. Park’s photodiode modified by Mozzillo would allow guard ring and the anode to have the same potential. It is well known in the art that biasing guard ring to the same potential as the anode would create a region where the electric field is nearly zero or gently sloping, thus “shielding” the main anode from stray currents and field crowding at the edge, preventing leakage and breakdown by making the potential gradient flatter.
Re: Claim 18, Park in view of Mozzillo discloses the method of claim 15, wherein forming the guard ring causes the semiconductor material to horizontally surround the anode (Park: Figs. 2A, 2B and ¶ [40] disclosing guard ring surrounds anode region 112).
Re: Claim 19, Park in view of Mozzillo discloses the method of claim 15, wherein forming the guard ring includes forming a lower surface of the guard ring vertically between a lower surface of the anode and a lower surface of the cathode (Park: [0040] disclosing the depth of guard ring 116 measured from the upper surface S1 of the substrate Sub is greater than the depth of anode region 112; Fig. 2B showing the lowermost surface of guard ring 116 is lower than the lowermost surface of cathode region 114).
Re: Claim 20, Park in view of Mozzillo discloses the method of claim 15, further comprising forming the doped well in one of a bulk semiconductor substrate and a semiconductor layer of a semiconductor on insulator (SOI) substrate (Park: ¶ [0035] disclosing "… The substrate Sub may include a bulk single crystalline silicon wafer, a silicon-on-insulation (SOI) wafer ...").
13. Prior art made of record and not relied upon are considered pertinent to current application disclosure.
Chavez (EP 4213219 A1), Huang (WO 2014018032 A1) disclosing a guard ring encircles between an anode and cathodes with a plurality of guard ring contacts.
Conclusion
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/DTH/Examiner, Art Unit 2898
/Leonard Chang/Supervisory Patent Examiner, Art Unit 2898
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