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 .
Drawings and Specification
The drawing and specification amendment filed on 06/13/2025
has been entered and thus previous objections to drawing and specification have been withdrawn.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-6 and 13-20 are rejected under 35 U.S.C. 103 as being unpatentable over Jiang et al. (US 2014/0147650 A1, as provided in IDS filed 06/08/2023; hereinafter Jiang) in view of Imer et al. (US 7,361,576 B2, as provided in IDS filed 06/08/2023; hereinafter Imer).
Regarding claims 1, 5, and 20, Jiang teaches a method of manufacturing high quality ammonothermal group-III metal nitride crystals (Jiang, abstract; Fig. 13-14; [0003]; [0011]; [0040]; [0045]-[0046]; [0050]-[0052]; [0058]-[0059]; [0098]-[0107]; [0113]; Examples 1-6) comprising,
wherein the method comprises depositing patterned mask layers 111 on surface 102 of substrate 101 (i.e., patterned mask layer on a first surface of a substrate) (Jiang, [0014]-[0016]; [0040]; [0046]-[0049]; Fig. 1B-2 and 13-14),
wherein substrate 101 comprises single-crystalline group-III metal nitride, gallium-containing nitride, or gallium nitride and such single crystalline group III metal nitride with large surface 102 having have a crystallographic orientation within 5 degrees, within 2 degrees, within 1 degree, or within 0.5 degree of (000-1)-c-plane (para. [0040]), wherein substrate 101 may have a stacking-fault concentration below about 104 cm -1 (Jiang, [0041]);
wherein substrate 101 may comprise regions having a relatively high concentration of threading dislocations separated by regions having a relatively low concentration of threading dislocations, wherein the concentration of threading dislocations in the relatively high concentration regions may be greater than about 105 cm-2, greater than about 107 cm-2, or greater than about 108 cm-2, and wherein the concentration of threading dislocations in the relatively low concentration regions may be less than about 106 cm-2, or less than about 104 cm-2 (Jiang, [0042]);
wherein patterned mask layer(s) 111 may be deposited on surface 102, wherein the patterned mask layer(s) 111 have openings with a pitch dimension between about 5 micrometers and about 20 millimeters (Jiang, [0046]-[0049]; Fig. 1B-1D and 13-14);
wherein the patterned substrate 101 may then be used for ammonothermal crystal growth process wherein ammonothermal group III metal nitride layer grows within on the patterned substrate (i.e., bulk crystal growth process using substrate 101 as a seed crystal) (Jiang, [0051]-[0052]; Fig. 2 and 13-14);
wherein the ammonothermal crystal growth process comprises placing patterned substrate 101 in a sealable container along with a group Ill metal source, at least one mineralizer composition, and ammonia, wherein the sealable container is then heated to a temperature above about 400 degrees Celsius and pressurized above about 50 megapascal to perform ammonothermal crystal growth, wherein the sealable container can be maintained at these temperature for a duration, such as approximately 100 hours, approximately 116 hours, approximately 138 hours, or approximately 230 hours, for example, wherein during the ammonothermal crystal growth process ammonothermal group III metal nitride material grows within the openings of patterned mask layer 111, grows outward through the openings, and grows laterally over patterned mask 111 (Jiang, [0050]-[0052]; [0113]; Fig. 13-14; Examples 1, 2, 5, and 6).
As set forth in MPEP 2144.05, in the case where the claimed range “overlap or lie inside ranges disclosed by the prior art”, a prima facie case of obviousness exists, In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Jiang further teaches wherein substrate 101 may have a thickness between about 10 micrometers and about 10 millimeters (Jiang, [0040]).
Regarding claims 1, 5, and 20, Jiang does not explicitly disclose (a) removing portions of the substrate exposed within the array of openings to form trenches in the substrate, wherein an ammonothermal group Ill metal nitride material grows within the plurality of trenches, and wherein the bulk crystal growth is initiated from sidewalls of the trenches, and (b) wherein the trenches having a depth below the first surface of greater than 50 micrometers, as presently claimed.
With respect to the difference (a), Imer teaches a method of performing a lateral epitaxial overgrowth of III-nitride material from sidewalls of etched template material through a patterned mask, wherein the template material may be any non-polar or semi-polar III-Nitride template material, including but not limited to GaN, AlGaN, and InGaN with various thicknesses and crystallographic orientations, wherein the result of the method is a free standing III-Nitride wafer or a substrate (Imer, abstract; col. 1, lines 39-41; col. 2, lines 50-64; col. 4, lines 28-67; col. 5, lines 1-57; col. 6, line 59 – col. 7, line 29; col. 8, lines 4-8; claims 1-4, 8-11, and 13-17; Fig. 3);
wherein the method comprises (1) forming the patterned mask on the template material, (2) etching the template material through one or more openings in the patterned mask to form one or more trenches or pillars in the template material, wherein the trenches or pillars define sidewalls (i.e., removing portions of the substrate exposed within the array of openings to form trenches in the substrate), and (3) growing the III-Nitride material laterally from tops of the sidewalls (i.e., bulk crystal grow is initiated from sidewalls of the trenches), wherein the III-Nitride material growing laterally from the tops of the sidewalls coalesces and blocks the III-Nitride material growing vertically from the bottoms of the trenches, and wherein the III-Nitride material grows through the openings after coalescence (i.e., the III-Nitride material grows within the plurality of trenches), and then grows laterally over the patterned mask to form an overgrown III-Nitride film (Imer, abstract; col. 2, lines 50-64; col. 4, lines 28-67; col. 5, lines 1-57; col. 6, line 59 – col. 7, line 29; col. 8, lines 4-8; claims 1-4, 8-11, and 13-17; Fig. 3).
As Imer expressly teaches, dislocation densities in directly grown (Ga, In, Al, B)N materials are quite high, wherein high-performance devices could be achieved by reducing or ideally eliminating these defects, and while such defects have been reduced by various methods involving lateral epitaxial overgrowth (LEO) in GaN, by using sidewall lateral epitaxial overgrowth (SLEO) (i.e., where the III-nitride nucleates and grows from the tops of the trench sidewalls), dislocation densities can be reduced down to even lower values by eliminating defects not only in the overgrown regions but also in the window regions, wherein by favoring Ga face growth and limiting N face growth, stacking fault densities can be made orders of magnitude lower, and further, the SLEO method allows significant defect reduction by leaving most areas defect-free while involving only one processing and growth step, in other words, having double-step LEO results in terms of quality and reduction in the majority of defects while using the simple and efficient process of single-step LEO processes, wherein the SLEO method can reduce dislocation densities by at least one order of magnitude compared to single step LEO processes (i.e., reduction in dislocation density in process employing using trenches) (Imer, abstract; col. 3, lines 2-20; col. 4, lines 7-45; col. 5, lines 34-36; col. 6, lines 32-49; col. 7, lines 23-27; col. 8, lines 55-61; col. 9, lines 17-37; Fig. 3).
Imer is analogous art, as Imer is drawn to a method of performing a lateral epitaxial overgrowth of III-nitride material from sidewalls of etched template material through a patterned mask, wherein the template material is a III-Nitride template material, including but not limited to GaN, AlGaN, and InGaN, and wherein the result of the method is a free standing III-Nitride wafer or a substrate (Imer, abstract; col. 1, lines 39-41; col. 2, lines 50-64; col. 4, lines 28-67; col. 5, lines 1-57; col. 6, line 59 – col. 7, line 29; col. 8, lines 4-8; claims 1-4, 8-11, and 13-17; Fig. 3).
In light of the motivation of using nucleation and growth initiating from the sidewalls of trenches taught in Imer, it therefore would have been obvious to one of ordinary skill in the art to incorporate the etching the III-Nitride substrate through the openings in the patterned mask to form trenches prior to bulk crystal growth of Imer in the process of Jiang, in order to efficiently and effectively reduce defects of the resulting ammonothermal group III metal nitride layer, and thereby arrive at the claimed invention.
With respect to the difference (b), although there are no explicit disclosures on the depth of the trenches below the surface 102, as presently claimed, it has long been an axiom of United States patent law that it is not inventive to discover the optimum or workable ranges of result-effective variables by routine experimentation. In re Peterson, 315 F.3d 1325, 1330 (Fed. Cir. 2003) (“The normal desire of scientists or artisans to improve upon what is already generally known provides the motivation to determine where in a disclosed set of percentage ranges is the optimum combination of percentages.”); In re Boesch, 617 F.2d 272, 276 (CCPA 1980) (“[D]iscovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art.”); In re Aller, 220 F.2d 454, 456 (CCPA 1955) (“[W]here 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.”). “Only if the ‘results of optimizing a variable’ are ‘unexpectedly good’ can a patent be obtained for the claimed critical range.” In re Geisler, 116 F.3d 1465, 1470 (Fed. Cir. 1997) (quoting In re Antonie, 559 F.2d 618, 620 (CCPA 1977)).
At the time of the invention, it would have been obvious to one of ordinary skill in the art to vary the depth of the trenches, including over the amounts presently claimed, in order to allow growth from the tops of the sidewalls of the trenches to coalesce before defected material growing from the bottom of the trenches reaches the tops of the sidewalls (Imer, abstract; Fig. 3; col. 2, lines 55-61; col. 6, lines 10-15; col. 8, lines 21-25; claim 7), and thereby arrive at the claimed invention.
Regarding claim 2, Jiang further teaches wherein the openings in patterned mask layer(s) 111 may be square, rectangular, or the like, and may have an opening dimension between about 1 micrometer and about 5 millimeters (Jiang, [0049]; Fig. 1C-1D, 5, 8-9C), wherein in certain embodiments, the openings comprise an array of slits with width W and period L that run across the entire length of substrate 101, wherein the substrate 101 has a surface 102 with a maximum dimension between about 5 millimeters and about 600 millimeters and a minimum dimension between about 1 millimeter and about 600 millimeters (Jiang, [0040]; [0049]; Fig. 1C-1D, 5, 8-9C), wherein for example, the pattern can comprise linear arrays of 20-micrometer wide by 1-centimeter-long slits (Jiang, [0084]).
While Jiang in view of Imer does not explicitly disclose the width and length of the trenches, given the trenches are formed in the openings of the patterned mask, it would have been obvious to one of ordinary skill in the art that the width and length dimensions of the trenches of Jiang in view of Imer would be approximately equivalent to the width and length dimensions of the openings of the patterned mask, and thereby arrive at the claimed invention.
As set forth in MPEP 2144.05, in the case where the claimed range “overlap or lie inside ranges disclosed by the prior art”, a prima facie case of obviousness exists, In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Alternatively, although there are no explicit disclosures on the width and length of the trenches, as presently claimed, it has long been an axiom of United States patent law that it is not inventive to discover the optimum or workable ranges of result-effective variables by routine experimentation. In re Peterson, 315 F.3d 1325, 1330 (Fed. Cir. 2003) (“The normal desire of scientists or artisans to improve upon what is already generally known provides the motivation to determine where in a disclosed set of percentage ranges is the optimum combination of percentages.”); In re Boesch, 617 F.2d 272, 276 (CCPA 1980) (“[D]iscovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art.”); In re Aller, 220 F.2d 454, 456 (CCPA 1955) (“[W]here 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.”). “Only if the ‘results of optimizing a variable’ are ‘unexpectedly good’ can a patent be obtained for the claimed critical range.” In re Geisler, 116 F.3d 1465, 1470 (Fed. Cir. 1997) (quoting In re Antonie, 559 F.2d 618, 620 (CCPA 1977)).
At the time of the invention, it would have been obvious to one of ordinary skill in the art to vary the dimensions (i.e., including width and length), including over the amounts presently claimed, in order to compensate for competing lateral and vertical growth rates and ensure the growth from the tops of the sidewalls of the trenches coalesce before defected material growing from the bottom of the trenches reaches the tops of the sidewalls (Imer, claims 6-7; abstract; Fig. 3; col. 2, lines 55-61; col. 5, line 58 – col. 6, line 15; col. 8, lines 21-25), and thereby arrive at the claimed invention.
Regarding claims 3 and 4, Jiang further teaches wherein the patterned mask layer(s) 111 include an adhesion layer 105, a diffusion barrier layer 107 overlaying the adhesion layer 105, and an inert layer 109 overlaying the diffusion barrier layer 107, wherein the adhesion layer 105 may comprise one or more of Ti, TiN, TiNy, TiSi2, Ta, TaNy, Al, Ge, AlxGey, Cu, Si, Cr, V, Ni, W, TiWx, TiWxNy or the like and may have a thickness between about 1 nanometer and about 1 micrometer, wherein the diffusion barrier layer 107 may comprise one or more of TiN, TiNy, TiSi2, W, TiWx, TiNy, WNy, TaNy, TiWxNy, TiWxSi2Ny, TiC, TiCN, Pd, Rh, Cr, or the like, and have a thickness between about 1 nanometer and about 10 micrometers, and wherein the inert layer 109 may comprise one or more of Au, Ag, Pt, Pd, Rh, Ru, Ir, Ni, Cr, V, Ti, or Ta and may have a thickness between about 10 nanometers and about 100 micrometers (Jiang, [0046]; [0099]-[0102]; Fig. 1B, 2, and 13).
Regarding claim 6, Jiang further teaches wherein during the ammonothermal crystal growth process, ammonothermal group III metal nitride material grows laterally over patterned mask 111, and coalesces, forming coalescence fronts 219, wherein the coalescence fronts propagate a pattern of locally-approximately-linear arrays of threading dislocations, wherein the linear concentration of threading dislocations in the pattern may be less than about 1x105 cm-1 and may be greater than 5 cm-1 (Jiang, [0052]; [0055]; [0064]; Fig. 2, 5, and 13).
Regarding claim 13, Jiang further teaches wherein the openings in patterned mask layer(s) 111 may be round, square, rectangular, triangular, hexagonal, or the like, and may have an opening dimension between about 1 micrometer and about 5 millimeters, (Jiang, [0049]; Fig. 1C-1D, 5, 8-9C).
Regarding claim 14, Jiang further teaches wherein the openings in patterned mask layer(s) 111 may be square, rectangular, or the like, and may have an opening dimension between about 1 micrometer and about 5 millimeters (i.e., includes slits with overlapping ranges for width and length dimensions) (Jiang, [0049]; Fig. 1C-1D, 5, 8-9C),
wherein in certain embodiments, the openings comprise an array of slits with width W and period L that run across the entire length of substrate 101, wherein the substrate 101 has a surface 102 with a maximum dimension between about 5 millimeters and about 600 millimeters and a minimum dimension between about 1 millimeter and about 600 millimeters (Jiang, [0040]; [0049]; Fig. 1C-1D, 5, 8-9C);
wherein for example, the pattern can comprise linear arrays of 20-micrometer wide by 1-centimeter-long slits (Jiang, [0084]).
As set forth in MPEP 2144.05, in the case where the claimed range “overlap or lie inside ranges disclosed by the prior art”, a prima facie case of obviousness exists, In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990).
Regarding claims 15 and 16, Jiang further teaches wherein the openings may be arranged in a rectangular, parallelogram, hexagonal, or trapezoidal array, wherein the slits may be arranged to define a length period L2, wherein adjacent rows of slits may be offset in the lateral direction from one another or arranged directly adjacent, as shown in FIG. 1C-1D, wherein in certain embodiments, the adjacent rows of slits may be offset in the longitudinal direction from one another, wherein the slits may be oriented in more than one direction, as also shown in FIG.1D (Jiang, [0049]; Fig. 1C-1D, 5, 8-9C).
Regarding claim 17, Jiang does not explicitly disclose , wherein the trenches penetrate the entire thickness of the substrate, as presently claimed.
With respect to the difference, Imer further teaches wherein the III-Nitride template material (1) is provided on a substrate (2), and wherein growth from the bottoms (9) of the trenches (5) may be prevented by etching to the substrate (2) (i.e., trenches penetrate the entire thickness of the III-Nitride template material) (Imer, col. 5, lines 1-20; col. 6, lines 16-20; col. 8, lines 20-26; Fig. 3).
As Imer expressly teaches, III-Nitride material nucleates on and grows from both tops of sidewalls and the bottoms of the trenches, wherein the III-Nitride material that grows from the bottom of the trenches is defective, and wherein growth from the bottoms of the trenches may be prevented by etching to the substrate (Imer, col. 5, lines 34-36; col. 6, lines 10-20; col. 8, lines 20-26; Fig. 3).
In light of the motivation of etching to the substrate (i.e., etching the entire thickness of the III-Nitride template material) taught in Imer, it therefore would have been obvious to one of ordinary skill in the art to incorporate the providing the III-Nitride template material on another substrate and etching trenches to the substrate of Imer in the process of Jiang, in order to prevent defective ammonothermal group III metal nitride material from nucleating and growing from the bottom of the trenches, and thereby arrive at the claimed invention.
Regarding claims 18-19, Jiang further teaches wherein ammonothermal group III metal nitride layer 213 is grown on substrate 101, wherein during the ammonothermal crystal growth process ammonothermal group III metal nitride material grows laterally over patterned mask 111, and coalesces to form ammonothermal group III metal nitride layer 213 (i.e., laterally-grown group III metal nitride material), wherein substrate 101 is then removed from ammonothermal group III metal nitride layer 213 to a form free-standing ammonothermal group III metal nitride boule 413, wherein free-standing ammonothermal group III metal nitride boule 413 can be sliced into one or more free-standing ammonothermal group III metal nitride wafers 431, wherein the free-standing ammonothermal group III metal nitride crystal or wafer is used as a seed crystal for further bulk growth (i.e., substrate) (Jiang, [0052]-[0053]; [0062]-[0064]; [0073]; [0105]-[0107]; Fig. 2 and 4).
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Jiang in view of Imer, as applied to claim 1 above, and further in view of Jain et al. (US 2008/0176398 A1; hereinafter Jain) and Ozono et al., High-speed ablation etching of GaN semiconductor using femtosecond laser (hereinafter Ozono).
Regarding claim 8, Jiang further teaches wherein a patterned photoresist layer 103 can be used to pattern the patterned masking layers 111, wherein the photoresist layer 103 may be deposited on surface 102, baked, exposed to UV light through a photomask to form a pre-determined pattern of cross-linked photoresist, and developed to remove non-cross linked material (i.e., photolithography process) (Jiang, [0045]-[0046]; Fig. 1A).
Additionally, Imer further teaches wherein the GaN exposed through the openings of the mask layer can be etched using reactive ion etching (RIE) (i.e., forming the trenches using RIE process) (Imer, col. 6, line 65 – col. 7, line 15).
However, Jiang in view of Imer does not explicitly disclose (a) wherein the openings in the patterned mask layer are formed by a laser process and (b) wherein the trenches are formed by a laser process, as presently claimed.
With respect to the difference (a), Jain teaches a method of making patterns of microsized and/or nanosized structures, wherein the method is compatible with large area substrates, such as device substrates for semiconductors, and is useful for fabrication applications requiring patterning of layered materials (Jain, abstract; [0014]-[0016]), and wherein laser ablation is used to pattern a mask layer on a substrate (Jain, abstract; [0020]-[0022]; [0015]-[0018]; claim 1).
As Jain expressly teaches, the patterning method using laser ablation of the mask layer provides a number of advantages over conventional photolithography, including that definition of the laser ablated patterned layer serving as the mask is carried out via a single, efficient laser ablation processing step, wherein in contrast to conventional photolithographic patterning, this has the advantage of eliminating some of the photolithographic processing and material etching steps, thereby reducing net processing time and costs (Jain, [0020]; [0015]-[0016]), and wherein laser ablation provides a very high degree of control over the physical dimensions and spatial orientations of the recessed features that are patterned, and is capable of making patterns of structures with high resolution, good pattern fidelity and high precision (Jain, [0016]-[0018]; [0020]; abstract)
Jain is analogous art, as Jain is drawn to methods for making patterns of structures for electronic, optical and optoelectronic devices, wherein the method uses laser ablation to pattern a mask layer on a substrate (Jain, abstract; [0015]; [0020]-[0022]; claim 1).
In light of the motivation of using laser ablation taught in Jain, it therefore would have been obvious to one of ordinary skill in the art to substitute in using laser ablation of Jain as the process step to form the opening in the patterned mask layer in Jiang in view of Imer, in order to reduce net processing time and costs, and to use a process with a very high degree of control over the physical dimensions and spatial orientations of the recessed features that are patterned, capable of making patterns of structures with high resolution, good pattern fidelity and high precision, and thereby arrive at the claimed invention.
With respect to the difference (b), Ozono teaches a method of etching of GaN using laser etching (Ozono, abstract; page 103, right col., last paragraph – page 104, left col., line 3).
As Ozono expressly teaches, wherein high etch rates of 100-1500 nm/s can be obtained using laser etching, which are significantly higher than those achieved with RIE etching of GaN (Ozono, page 103, right col., last paragraph – page 104, left col., line 3; page 105, left col., 1st paragraph).
Ozono is analogous art, as Ozono is drawn to a method of etching of GaN substrate using laser etching (Ozono, page 103, right col., last paragraph – page 104, left col., line 3; abstract).
In light of the motivation of using laser etching taught in Ozono, it therefore would have been obvious to one of ordinary skill in the art to substitute in the use of laser ablation of Ozono in the process step to form the trenches in Jiang in view of Imer and Jain, in order to use a process with significantly higher etch rates and therefore reduce etching time, and thereby arrive at the claimed invention.
Claims 10 and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Jiang in view of Imer, Jain, and Ozono, as applied to claim 8 above, and further in view of Nakashima et al., Fabrication of High-aspect-ratio Nanohole Arrays on GaN Surface by Using Wet-chemical-assisted Femtosecond Laser Ablation (hereinafter Nakashima).
Regarding claims 10 and 11, Jiang in view of Imer, Jain, and Ozono does not explicitly disclose wherein the laser process comprises scanning over an entire pattern on the first surface repetitively to form openings in the mask layer and trenches having predetermined dimensions, and wherein residual damage in the trenches is removed by a wet etching or by a photoelectrochemical etching process, as presently claimed.
With respect to the difference, Nakashima teaches wherein a periodic array of nanoholes (i.e., pattern) with high aspect ratios was successfully fabricated by using a multi-scan laser irradiation technique on single-crystal GaN substrates, wherein wet-chemical-assisted ablation process is used (Nakashima, abstract; page 15, right col., last paragraph; page 16, left col. 1st paragraph; page 16, right col., 1st paragraph; page 18, left col., 1st paragraph; conclusions),
wherein the multi-scan irradiation technique involves performing a series of sequential scans, wherein each position is irradiated with a single laser pulse during each scan (i.e., scanning over an entire pattern on the first surface repetitively to form openings) (Nakashima, page 16, right col., 1st paragraph; page 17, left col., 1st paragraph; page 18, left col., 1st paragraph);
wherein the wet-chemical-assisted ablation process involves performing laser ablation on a GaN substrate immersed in an HCl solution, wherein when the first pulse irradiates the surface of the GaN substrate, an ablation reaction occurs just at the surface, wherein almost simultaneously, the Ga-rich phase remaining on the surface of the nano-crater (i.e., trenches) is chemically removed by the HCl acid solution (i.e., residual damage in the trenches is removed by a wet etching process) (Nakashima, page 18, left col., 1st paragraph).
As Nakashima expressly teaches, the saturated value for wet-chemical-assisted ablation is 30 % higher than that for ablation in air, wherein the reason for this is thought to be that in the multi-scan irradiation method, when the first pulse irradiates the surface of the GaN substrate, an ablation reaction occurs just at the surface, almost simultaneously, the Ga-rich phase remaining on the surface of the nano-crater is chemically removed by the acid solution, wherein after a sufficient amount of time, the micro-bubbles disappear and the next laser pulse arrives in the subsequent scan, wherein during the second pulse, ablation occurs at the new surface cropped out by the preceding ablation process (Nakashima, abstract; page 18, left col., 1st paragraph; page 16, right col., 1st paragraph; conclusion). Additionally, as Nakashima teaches, when the ablation reaction takes place in a liquid solution, which is the case for wet-chemical-assisted ablation, the micro-bubbles generated by the preceding pulses interfere with subsequent pulses, and the fabrication efficiency is drastically decreased, however, if the time interval between the pulses was longer than the time scale for disappearing of bubbles, such interference would be minimal, wherein although this could be achieved by using a low repetition rate of pulses, the fabrication time would inevitably become much longer, wherein to avoid this drawback, the multi-scan irradiation technique involving a series of sequential scans is performed and each position is irradiated with a single laser pulse during each scan is used, which provides sufficient time for the disappearance of microbubbles generated by the proceeding pulses, so that each pulse can successfully reach the substrate surface, wherein in addition, high speed processing is feasible because, in principle, it is not necessary to decrease the repetition rate (Nakashima, page 16, right col., 1st paragraph; page 17, left col., 1st paragraph; page 18, left col., 1st paragraph; abstract; conclusion). Nakashima further teaches wherein compared to ablation in air followed by HCl etching, the wet-chemical-assisted ablation process enhances the aspect ratio by about 30 % because of the high refractive index of the HCl solution (Nakashima, abstract; page 16, right col., 1st paragraph; page 17, left col., 1st paragraph; page 18, left col., 1st paragraph; conclusion).
Nakashima is analogous art, as Nakashima is drawn to wherein a periodic array of nanoholes was successfully fabricated by using a multi-scan laser irradiation technique on single-crystal GaN substrates (i.e., patterning a GaN substrate using laser ablation) (Nakashima, abstract; page 15, right col., last paragraph; page 16, left col. 1st paragraph; page 16, right col., 1st paragraph; page 18, left col., 1st paragraph; conclusions).
In light of the motivation of using a multi-scan irradiation technique and wet-chemical-assisted ablation for the laser ablation process taught in Nakashima, it therefore would have been obvious to one of ordinary skill in the art to incorporate the multi-scan technique and wet-chemical-assisted ablation process of Nakashima in the process of patterning and forming trenches of Jiang in view of Imer, Jain, and Ozono, in order to achieve a higher saturated value and aspect ratio, compared to ablation in air, by removing ablated material remaining on the surface of the substrate between pulses, and to use a high speed process while allowing sufficient time for micro-bubbles to subside between pulses, and thereby arrive at the claimed invention.
Response to Arguments
Applicant’s amendment filed on 06/13/2025 have been acknowledged and thus previous claim objections have been withdrawn.
Applicant’s arguments filed on 06/13/2025 have been fully considered but they are moot in view of current rejections. As for the amended limitation of the first surface has a crystallographic orientation within about 5 degrees of (000-1)-c-plane, as the examiner pointed out during previous interview summary (dated 06/05/2025), Jiang et al already teaches such limitation. Specifically, Jiang et al. teaches gallium nitride and such single crystalline group III metal nitride (i.e. gallium nitride) with large surface 102 having a crystallographic orientation within 5 degrees, within 2 degrees, within 1 degree, or within 0.5 degree of (000-1)-c-plane (para. [0040]).
In response to applicant’s arguments about teaching away from the currently claimed invention because “Imer states multiple times in the application that growth in a Ga direction (e.g., as would occur while during growth on a Ga-(0001) face substrate) is preferred over growth in an N direction (e.g., as would occur during growth on a N-(000- 1) face substrate), and that growth from N-face will lead to highly defective crystals being formed. (For example, see Imer column 3, lines 8-11; column 4, lines 1-9; and column 4, lines 47-59)”, Imer noticed the disadvantages of N-face growth, therefore, Imer expressly teaches “decreases stacking fault densities with an anisotropy factor, i.e., by encouraging higher growth rates on the Ga-(0001) face and limiting the N-(000-1) face growth rates” (col. 4 lines 46-58). In other words, Imer teaches encouraging lateral growth on the Ga-(0001) face, which is the same as that of instant application (See filed specification para. [0044], [0055]). Therefore, Imer is analogous art, in light of the motivation of using nucleation and growth initiating from the sidewalls of trenches taught in Imer, it therefore would have been obvious to one of ordinary skill in the art to incorporate the etching the III-Nitride substrate through the openings in the patterned mask to form trenches prior to bulk crystal growth of Imer in the process of Jiang, in order to efficiently and effectively reduce defects of the resulting ammonothermal group III metal nitride layer, and thereby arrive at the claimed invention.
In response to applicant’s arguments about “inventors have found that forming a group Ill metal containing nitride free-standing crystal by use of a process that at least includes depositing a patterned mask layer on a first surface of a substrate, wherein the patterned mask layer comprises an array of openings that have a pitch in a first direction between 5 micrometers and 20 millimeters and the first surface has a crystallographic orientation within about 5 degrees of (000-1) -c-plane provides significant advantages, which include a low dislocation density and a reduction in the probability that cracks are formed in a group Ill metal containing nitride free-standing crystal during the crystal formation process (See paragraphs [0075] and [0078])”, Jiang et al. already teaches forming group III metal containing nitride free-standing crystal comprising depositing patterned mask layers 111 on surface 102 of substrate 101 (i.e., patterned mask layer on a first surface of a substrate) (Jiang, [0014]-[0016]; [0040]; [0046]-[0049]; Fig. 1B-2 and 13-14), wherein patterned mask layer(s) 111 may be deposited on surface 102, wherein the patterned mask layer(s) 111 have openings with a pitch dimension between about 5 micrometers and about 20 millimeters (Jiang, [0046]-[0049]; Fig. 1B-1D and 13-14), wherein substrate 101 comprises single-crystalline group-III metal nitride, gallium-containing nitride, or gallium nitride and such single crystalline group III metal nitride with large surface 102 having have a crystallographic orientation within 5 degrees, within 2 degrees, within 1 degree, or within 0.5 degree of (000-1)-c-plane (para. [0040]), Jiang et al. also teaches a same or substantially the same low dislocation density as that of instantly claimed with the process being same or same or substantially the same as that of instant application, therefore, same or substantially the same reducing cracking formation as that of instant application would be expected.
In response to applicant’s arguments about “the use of trenches, together with the use of a (000-1) -c-plane substrate orientation, enables reduction in the miscut variation in each of two orthogonal crystallographic orientations across wafers prepared from a group III metal containing nitride free-standing crystal (see paragraphs [0076] and [0092]), the combined teachings of Jiang et al. and Imer teaches a same or substantially the same using of trenches together with use of a (000-1) -c-plane substrate orientation as that of instantly claimed. Therefore, same or substantially the same enabling in the miscut variation in each of two orthogonal crystallographic orientations across wafers prepared from a group III metal containing nitride free-standing crystal as that of instant application would be expected as well.
Conclusion
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.
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/JUN LI/ Primary Examiner, Art Unit 1732