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 .
Response to Amendment
Amendment filed 2/6/2026 has been entered. Claims 1, 11 are amended. Claims 1 – 20 are pending.
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 1 – 20 are rejected under 35 U.S.C. 103 as being unpatentable over Curatola ( Pub. No. 20180138304 A1 ), hereinafter Curatola; in view of Peng ( U: Peng F et al. Simulation of a high-performance enhancement-mode HFET with back-to-back graded AlGaN layers. Sci China Inf Sci, 2019, 62(6): 062403 ), hereinafter Peng; and Li ( V: Liang Li et al. Reduction of threading dislocations in N-polar GaN using a pseudomorphicaly grown graded-Al-fraction AlGaN interlayer, Journal of Crystal Growth, Volume 387, 2014, Pages 1-5 ), hereinafter Li.
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Regarding Independent Claim 1 ( Currently Amended ), Curatola teaches a high electron mobility heterostructure ( Curatola, FIG. 2, 102; [0014], The semiconductor device 100 includes a heterostructure body 102 ), comprising:
a substrate ( Curatola, FIG. 2, 116; [0014], base substrate 116 );
a buffer ( Curatola, FIG. 2, 114, 110; [0014], lattice transition layer 114; buffer region 110 ) on the substrate;
a doped charge compensation layer ( Curatola, FIG. 2, 128, 110; [0018], doped semiconductor region 128; [0014], buffer region 110 ) on the buffer;
a double continuous grade barrier ( Curatola, FIG. 2, 212, 202, 204; [0012], According to embodiments described herein, an HEMT with a graded back-barrier design is disclosed; [0024], According to an embodiment, the back-barrier region 212 includes a first back-barrier region 202 beneath the buffer region 110, and a second back-barrier region 204 beneath the first back-barrier region 202 ) on the doped charge compensation layer having increasing polarization charge and decreasing polarization charge ( Curatola, [0027], According to an embodiment, the first back-barrier region 202 has an aluminum concentration in the range of 1 to 2 percent, and more particularly about 1.5 percent and the second back barrier region 204 has an aluminum concentration in the range of 3.5 percent to 5 percent. More generally, the first back-barrier region 202 can have an aluminum concentration of less than 5 percent and the second back barrier region 204 has an aluminum concentration in the range of greater than four percent ), wherein the doped charge compensation layer ( Curatola, FIG. 2, 128, 110; [0018] ) is disposed between the buffer ( Curatola, FIG. 2, 114, 110; [0014] ) and the double continuous grade barrier ( Curatola, FIG. 2, 212, 202, 204; [0012] );
a channel ( Curatola, [0012], The channel of the HEMT device is formed by a heterojunction between a barrier region and a buffer region; [0015], The difference in band gap and the presence of the polarization charges between the GaN buffer region 110 and the AlGaN barrier region 108 causes a first two-dimensional charge carrier gas region 118 to intrinsically arise near an interface between the buffer region 110 and the barrier region 108 ) on the double continuous grade barrier; and
a charge generation layer ( Curatola, [0014], barrier region 108 ) on the channel.
Curatola fails to disclose:
a double continuous grade barrier on the doped charge compensation layer having increasing polarization charge and decreasing polarization charge; … wherein the double continuous grade barrier comprises a lower continuously-graded back barrier and an upper continuously-graded back barrier;
However, Peng teaches:
a double continuous grade barrier on the doped charge compensation layer having increasing polarization charge ( Peng, page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN …, as shown in Figure 1(b) ) and decreasing polarization charge ( Peng, page 2, line 24, The aluminum (Al) composition … and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b) ) … wherein the double continuous grade barrier comprises a lower continuously-graded back barrier ( Peng, page 2, line 24, the positive-graded AlGaN in Figure 1(b) )and an upper continuously-graded back barrier ( Peng, page 2, line 24, the negative-graded AlGaN in Figure 1(b) );
Curatola does not explicitly disclose:
wherein the doped charge compensation layer is disposed between the buffer and the double continuous grade barrier;
However, Curatola teaches:
The purpose of doped semiconductor region 128 is to control the channel conductivity ( i.e. disrupt the conductivity ) and the gate threshold voltage, [0019], cited “ That is, the parameters of the doped semiconductor region are controlled to disrupt the conductive connection between the source and drain electrodes 122, 124 in the absence of a gate bias and therefore provide a normally-off HEMT device. The gate structure 126 is configured to turn the device ON with a sufficient voltage applied to the gate electrode 130 that removes the depleted region of the first two-dimensional charge carrier gas region 118 underneath the gate structure 126 118. As a result, the first two-dimensional charge carrier gas region 118 forms a conductive connection between the source and drain contacts 114, 116 ”. Based on this teaching it would be within the skill level of one in the art, to dispose the doped charge compensation layer between the buffer and the double continuous grade barrier.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to create wherein the doped charge compensation layer is disposed between the buffer and the double continuous grade barrier in order to disrupt the conductivity ( e.g. set the depletion depth ). For example see ( e.g. US 20130161698 A1, FIG. 10, heavily doped threshold tune layer 70 between back-barrier layer 66 and layer 68 ), which provides doped charge compensation layer between the buffer and barrier.
Curatola and Peng are both considered to be analogous to the claimed invention because they are forming high electron mobility heterostructure. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified Curatola ( [0012], an HEMT with a graded back-barrier design is disclosed; [0024], the back-barrier region 212 includes a first back-barrier region 202 …, and a second back-barrier region 204 beneath the first back-barrier region 202 ), to incorporate the teachings of Peng ( page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b) ), to implement that the back-to-back graded AlGaN (BGA) barrier layers consisting of a positive-graded AlGaN layer and a negative-graded AlGaN layer. Doing so would provide three-dimensional electron gas (3DEG), and vertical conductive channel between the source and 3DEG is blocked by the 3DHG, and therefore the performance ( e.g. on-state current ) of high electron mobility heterostructure can be improved.
Curatola and Peng do not explicitly disclose:
the double continuous grade barrier … including pseudomorphically-strained layers, and wherein a combined thickness of the lower continuously-graded back barrier and the upper continuously-graded back barrier is less than a critical thickness for relaxation;
However, Li teaches: page 4, left column, line 3, “ This means that our designed thickness of graded AlGaN interlayer ( the total thickness is 50nm ) is far smaller than the critical thickness; therefore, there should be a pseudomorphic growth of graded AlGaN interlayer on GaN layer ”.
Curatola and Peng and Li are all considered to be analogous to the claimed invention because they are forming high electron mobility heterostructure. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified Curatola ( [0012], an HEMT with a graded back-barrier design is disclosed; [0024], the back-barrier region 212 includes a first back-barrier region 202 …, and a second back-barrier region 204 beneath the first back-barrier region 202 ), to incorporate the teachings of Peng ( page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b) ) and Li ( page 4, left column, line 3, our designed thickness of graded AlGaN interlayer ( the total thickness is 50nm ) is far smaller than the critical thickness; … a pseudomorphic growth of graded AlGaN interlayer on GaN layer ), to implement that the back-to-back graded AlGaN (BGA) barrier layers consisting of a positive-graded AlGaN layer and a negative-graded AlGaN layer, and “ the double continuous grade barrier … including pseudomorphically-strained layers, and the thickness of graded AlGaN interlayer is smaller than the critical thickness ”. Doing so would provide three-dimensional electron gas (3DEG), and vertical conductive channel between the source and 3DEG is blocked by the 3DHG, and annihilation of threading dislocations (TDs); and therefore the performance ( e.g. on-state current, reduction of TDs densities ) of high electron mobility heterostructure can be improved.
Regarding Claim 2 ( Original ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 1, on which this claim is dependent, Curatola and Peng further teach:
wherein the substrate is one of Silicon (Si), Silicon Carbide (SiC), Sapphire, Gallium Nitride (GaN), Aluminum Nitride (AlN), Boron Nitride (BN), and diamond ( Curatola; [0016], The base substrate 116 can include any material that is suitable for epitaxial growth thereon. Exemplary materials for the base substrate 116 include silicon and carbon; Peng, page 3, line4, The back-to-back graded AlGaN could be epitaxially grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) on the Ga-face (0111) GaN buffer layer; page 3, line 9, sapphire substrate ).
Regarding Claim 3 ( Original ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 1, on which this claim is dependent, Curatola further teaches:
wherein the buffer is one of Gallium Nitride (GaN) ( Curatola, [0015], buffer region 110 is a region of GaN ) and Aluminum Nitride (AlN) ( Curatola, [0016], After providing the base substrate 116 an AlN nucleation layer (not shown) and the lattice transition layer 114 is epitaxially grown on the base substrate 116 ).
Regarding Claim 4 ( Original ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 1, on which this claim is dependent, Curatola and Peng further teach:
wherein the doped charge compensation layer ( Curatola, [0018], doped semiconductor region 128 is formed from a p-type semiconductor nitride material (e.g., p-type GaN) ) is Gallium Nitride (GaN) doped with at least one of Beryllium, Magnesium, Iron, Carbon, and Manganese ( Peng, page 2, line 31, The N region under the source is used to regulate Vth, with doping concentration Ns. The drain and the negative-graded AlGaN are isolated by a gap to avoid the migration of the hole leakage current from the drain to the gate ).
Regarding Claim 5 ( Original ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 1, on which this claim is dependent, Curatola and Peng further teach:
wherein the double continuous grade barrier ( Curatola, FIG. 2, 212, 202, 204; [0012], According to embodiments described herein, an HEMT with a graded back-barrier design is disclosed; [0024], According to an embodiment, the back-barrier region 212 includes a first back-barrier region 202 beneath the buffer region 110, and a second back-barrier region 204 beneath the first back-barrier region 202 ) comprises:
a first Aluminum Gallium Nitride (AlGaN) barrier layer with an Aluminum (Al) content graded from a first range of 0% to 5% to a second range of 2% to 30% having monotonically increasing polarization charge ( Peng, page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN …, as shown in Figure 1(b); Curatola, [0027], … and more particularly about 1.5 percent and the second back barrier region 204 has an aluminum concentration in the range of 3.5 percent to 5 percent. More generally, … and the second back barrier region 204 has an aluminum concentration in the range of greater than four percent ); and
a second AlGaN barrier layer on the first AlGaN barrier layer with an Aluminum (Al) content graded from a first range of 2% to 30% to a second range of 0% to 5% having monotonically decreasing polarization charge ( Peng, page 2, line 24, The aluminum (Al) composition … and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b); Curatola, [0027], the first back-barrier region 202 has an aluminum concentration in the range of 1 to 2 percent, and more particularly about 1.5 percent and … More generally, the first back-barrier region 202 can have an aluminum concentration of less than 5 percent and … ).
Regarding Claim 6 ( Original ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 5, on which this claim is dependent, Curatola and Peng further teach:
wherein the first range of the first AlGaN barrier layer comprises one of: same as the second range of the second AlGaN barrier layer and different from the second range of the second AlGaN barrier layer; and
wherein the second range of the first AlGaN barrier layer comprises one of: same as the first range of the second AlGaN barrier layer and different from the first range of the second AlGaN barrier layer.
( Peng, page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b); Curatola, [0027], According to an embodiment, the first back-barrier region 202 has an aluminum concentration in the range of 1 to 2 percent, and more particularly about 1.5 percent and the second back barrier region 204 has an aluminum concentration in the range of 3.5 percent to 5 percent. More generally, the first back-barrier region 202 can have an aluminum concentration of less than 5 percent and the second back barrier region 204 has an aluminum concentration in the range of greater than four percent )
Regarding Claim 7 ( Original ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 5, on which this claim is dependent, Curatola and Peng further teach:
wherein first AlGaN barrier layer has a thickness greater than 3nm ( Curatola, [0027], According to one embodiment, the buffer region 110 is a 75 nm thick layer of gallium nitride, … , and the second back-barrier region 204 is a layer of aluminum gallium nitride that is at least 125 nm thick ), wherein the second AlGaN barrier layer has a thickness greater than 3nm ( Curatola, [0027], According to one embodiment, the buffer region 110 is a 75 nm thick layer of gallium nitride, the first back-barrier region 202 is a layer of aluminum gallium nitride that is at least 125 nm thick , … ), wherein the thickness of the first barrier layer is one of: same as and different from the thickness of the second barrier layer, and wherein a thickness of a combination of the first AlGaN barrier layer and the second AlGaN barrier layer has a thickness less than a critical thickness for relaxation ( Peng, page 7, line 15, Consequently, the maximum values of xAl and d discussed herein are 0.4 and 100 nm, respectively ).
Regarding Claim 8 ( Original ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 1, on which this claim is dependent, Curatola further teaches:
wherein the channel is an unintentionally doped channel ( Curatola, [0015], The difference in band gap and the presence of the polarization charges between the GaN buffer region 110 and the AlGaN barrier region 108 causes a first two-dimensional charge carrier gas region 118 to intrinsically arise near an interface between the buffer region 110 and the barrier region 108 ) that is one of Gallium Nitride (GaN) and Indium Gallium Nitride (InGaN).
Regarding Claim 9 ( Original ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 1, on which this claim is dependent, Curatola further teaches:
wherein the charge generation layer is one of Aluminum Gallium Nitride (AlGaN), Scandium Aluminum Nitride (ScAlN), Indium Aluminum Nitride (InAlN), Indium Aluminum Gallium Nitride (InAlGaN), and Aluminum Nitride (AlN) ( Curatola, [0015], AlGaN barrier region 108 ).
Regarding Claim 10 ( Previously Presented ), Curatola and Peng teach the high electron mobility heterostructure as claimed in claim 1, on which this claim is dependent, Curatola further teaches:
a nucleation layer ( Curatola, [0016], After providing the base substrate 116 an AlN nucleation layer (not shown) and the lattice transition layer 114 is epitaxially grown on the base substrate 116 ) between the substrate and the buffer;
at least one interlayer ( Curatola, [0014], buffer region 110 ) between the channel and the charge generation layer ( Curatola, [0014], barrier region 108 ); and
a capping layer ( Curatola, [0018], a doped semiconductor region 128 that is formed on the main surface 104 ) on the charge generation layer ( Curatola, [0014], barrier region 108 ), wherein the at least one interlayer ( Curatola, [0027], According to one embodiment, the buffer region 110 is a 75 nm thick layer of gallium nitride ) is one of Aluminum Nitride (AlN) and Gallium Nitride (GaN), and wherein the capping layer is one of GaN ( Curatola, [0018], According to an embodiment, the doped semiconductor region 128 is formed from a p-type semiconductor nitride material (e.g., p-type GaN) ), AlN, and Silicon Nitride (SiNx), where x is a positive rational number.
Regarding Independent Claim 11 ( Currently Amended ), Curatola teaches a method of fabricating a high electron mobility heterostructure ( Curatola, FIG. 2, 102; [0014], The semiconductor device 100 includes a heterostructure body 102 ), comprising:
forming a substrate ( Curatola, FIG. 2, 116; [0014], base substrate 116 );
forming a buffer ( Curatola, FIG. 2, 114, 110; [0014], lattice transition layer 114; buffer region 110 ) on the substrate;
forming a doped charge compensation layer ( Curatola, FIG. 2, 128, 110; [0018], doped semiconductor region 128; [0014], buffer region 110 ) on the buffer;
forming a double continuous grade barrier ( Curatola, FIG. 2, 212, 202, 204; [0012], According to embodiments described herein, an HEMT with a graded back-barrier design is disclosed; [0024], According to an embodiment, the back-barrier region 212 includes a first back-barrier region 202 beneath the buffer region 110, and a second back-barrier region 204 beneath the first back-barrier region 202 ) on the doped charge compensation layer having increasing polarization charge and decreasing polarization charge ( Curatola, [0027], According to an embodiment, the first back-barrier region 202 has an aluminum concentration in the range of 1 to 2 percent, and more particularly about 1.5 percent and the second back barrier region 204 has an aluminum concentration in the range of 3.5 percent to 5 percent. More generally, the first back-barrier region 202 can have an aluminum concentration of less than 5 percent and the second back barrier region 204 has an aluminum concentration in the range of greater than four percent ), wherein the doped charge compensation layer ( Curatola, FIG. 2, 128, 110; [0018] ) is disposed between the buffer ( Curatola, FIG. 2, 114, 110; [0014] ) and the double continuous grade barrier ( Curatola, FIG. 2, 212, 202, 204; [0012] );
forming a channel ( Curatola, [0012], The channel of the HEMT device is formed by a heterojunction between a barrier region and a buffer region; [0015], The difference in band gap and the presence of the polarization charges between the GaN buffer region 110 and the AlGaN barrier region 108 causes a first two-dimensional charge carrier gas region 118 to intrinsically arise near an interface between the buffer region 110 and the barrier region 108 ) on the double continuous grade barrier; and
forming a charge generation layer ( Curatola, [0014], barrier region 108 ) on the channel.
Curatola fails to disclose:
forming a double continuous grade barrier on the doped charge compensation layer having increasing polarization charge and decreasing polarization charge;
However, Peng teaches:
forming a double continuous grade barrier on the doped charge compensation layer having increasing polarization charge ( Peng, page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN …, as shown in Figure 1(b) ) and decreasing polarization charge ( Peng, page 2, line 24, The aluminum (Al) composition … and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b) ) … wherein the double continuous grade barrier comprises a lower continuously-graded back barrier ( Peng, page 2, line 24, the positive-graded AlGaN in Figure 1(b) )and an upper continuously-graded back barrier ( Peng, page 2, line 24, the negative-graded AlGaN in Figure 1(b) );
Curatola does not explicitly disclose:
wherein the doped charge compensation layer is disposed between the buffer and the double continuous grade barrier;
However, Curatola teaches:
The purpose of doped semiconductor region 128 is to control the channel conductivity ( i.e. disrupt the conductivity ) and the gate threshold voltage, [0019], cited “ That is, the parameters of the doped semiconductor region are controlled to disrupt the conductive connection between the source and drain electrodes 122, 124 in the absence of a gate bias and therefore provide a normally-off HEMT device. The gate structure 126 is configured to turn the device ON with a sufficient voltage applied to the gate electrode 130 that removes the depleted region of the first two-dimensional charge carrier gas region 118 underneath the gate structure 126 118. As a result, the first two-dimensional charge carrier gas region 118 forms a conductive connection between the source and drain contacts 114, 116 ”.
Therefore, based on Curatola’s teachings above, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to create wherein the doped charge compensation layer is disposed between the buffer and the double continuous grade barrier in order to disrupt the conductivity ( e.g. set the depletion depth ), since this is within the skill level of one in the art ( e.g. US 20130161698 A1, FIG. 10, heavily doped threshold tune layer 70 between back-barrier layer 66 and layer 68 ).
Curatola and Peng are both considered to be analogous to the claimed invention because they are forming high electron mobility heterostructure. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified Curatola ( [0012], an HEMT with a graded back-barrier design is disclosed; [0024], the back-barrier region 212 includes a first back-barrier region 202 …, and a second back-barrier region 204 beneath the first back-barrier region 202 ), to incorporate the teachings of Peng ( page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b) ), to implement that the back-to-back graded AlGaN (BGA) barrier layers consisting of a positive-graded AlGaN layer and a negative-graded AlGaN layer. Doing so would provide three-dimensional electron gas (3DEG), and vertical conductive channel between the source and 3DEG is blocked by the 3DHG, and therefore the performance ( e.g. on-state current ) of high electron mobility heterostructure can be improved.
Curatola and Peng do not explicitly disclose:
the double continuous grade barrier … including pseudomorphically-strained layers, and wherein a combined thickness of the lower continuously-graded back barrier and the upper continuously-graded back barrier is less than a critical thickness for relaxation;
However, Li teaches: page 4, left column, line 3, “ This means that our designed thickness of graded AlGaN interlayer ( the total thickness is 50nm ) is far smaller than the critical thickness; therefore, there should be a pseudomorphic growth of graded AlGaN interlayer on GaN layer ”.
Curatola and Peng and Li are all considered to be analogous to the claimed invention because they are forming high electron mobility heterostructure. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified Curatola ( [0012], an HEMT with a graded back-barrier design is disclosed; [0024], the back-barrier region 212 includes a first back-barrier region 202 …, and a second back-barrier region 204 beneath the first back-barrier region 202 ), to incorporate the teachings of Peng ( page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b) ) and Li ( page 4, left column, line 3, our designed thickness of graded AlGaN interlayer ( the total thickness is 50nm ) is far smaller than the critical thickness; … a pseudomorphic growth of graded AlGaN interlayer on GaN layer ), to implement that the back-to-back graded AlGaN (BGA) barrier layers consisting of a positive-graded AlGaN layer and a negative-graded AlGaN layer, and “ the double continuous grade barrier … including pseudomorphically-strained layers, and the thickness of graded AlGaN interlayer is smaller than the critical thickness ”. Doing so would provide three-dimensional electron gas (3DEG), and vertical conductive channel between the source and 3DEG is blocked by the 3DHG, and annihilation of threading dislocations (TDs); and therefore the performance ( e.g. on-state current, reduction of TDs densities ) of high electron mobility heterostructure can be improved.
Regarding Claim 12 ( Original ), Curatola and Peng teach the method as claimed in claim 11, on which this claim is dependent, Curatola and Peng further teach:
wherein the substrate is one of Silicon (Si), Silicon Carbide (SiC), Sapphire, Gallium Nitride (GaN), Aluminum Nitride (AlN), Boron Nitride (BN), and diamond ( Curatola; [0016], The base substrate 116 can include any material that is suitable for epitaxial growth thereon. Exemplary materials for the base substrate 116 include silicon and carbon; Peng, page 3, line4, The back-to-back graded AlGaN could be epitaxially grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) on the Ga-face (0111) GaN buffer layer; page 3, line 9, sapphire substrate ).
Regarding Claim 13 ( Original ), Curatola and Peng teach the method as claimed in claim 11, on which this claim is dependent, Curatola further teaches:
wherein the buffer is one of Gallium Nitride (GaN) ( Curatola, [0015], buffer region 110 is a region of GaN ) and Aluminum Nitride (AlN) ( Curatola, [0016], After providing the base substrate 116 an AlN nucleation layer (not shown) and the lattice transition layer 114 is epitaxially grown on the base substrate 116 ).
Regarding Claim 14 ( Original ), Curatola and Peng teach the method as claimed in claim 11, on which this claim is dependent, Curatola and Peng further teach:
wherein the doped charge compensation layer ( Curatola, [0018], doped semiconductor region 128 is formed from a p-type semiconductor nitride material (e.g., p-type GaN) ) is Gallium Nitride (GaN) doped with at least one of Beryllium, Magnesium, Iron, Carbon, and Manganese ( Peng, page 2, line 31, The N region under the source is used to regulate Vth, with doping concentration Ns. The drain and the negative-graded AlGaN are isolated by a gap to avoid the migration of the hole leakage current from the drain to the gate ).
Regarding Claim 15 ( Original ), Curatola and Peng teach the method as claimed in claim 11, on which this claim is dependent, Curatola and Peng further teach:
wherein the double continuous grade barrier ( Curatola, FIG. 2, 212, 202, 204; [0012], According to embodiments described herein, an HEMT with a graded back-barrier design is disclosed; [0024], According to an embodiment, the back-barrier region 212 includes a first back-barrier region 202 beneath the buffer region 110, and a second back-barrier region 204 beneath the first back-barrier region 202 ) comprises:
a first Aluminum Gallium Nitride (AlGaN) barrier layer with an Aluminum (Al) content graded from a first range of 0% to 5% to a second range of 2% to 30% having monotonically increasing polarization charge ( Peng, page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN …, as shown in Figure 1(b); Curatola, [0027], … and more particularly about 1.5 percent and the second back barrier region 204 has an aluminum concentration in the range of 3.5 percent to 5 percent. More generally, … and the second back barrier region 204 has an aluminum concentration in the range of greater than four percent ); and
a second AlGaN barrier layer on the first AlGaN barrier layer with an Aluminum (Al) content graded from a first range of 2% to 30% to a second range of 0% to 5% having monotonically decreasing polarization charge ( Peng, page 2, line 24, The aluminum (Al) composition … and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b); Curatola, [0027], the first back-barrier region 202 has an aluminum concentration in the range of 1 to 2 percent, and more particularly about 1.5 percent and … More generally, the first back-barrier region 202 can have an aluminum concentration of less than 5 percent and … ).
Regarding Claim 16 ( Original ), Curatola and Peng teach the method as claimed in claim 15, on which this claim is dependent, Curatola and Peng further teach:
wherein the first range of the first AlGaN barrier layer comprises one of same as the second range of the second AlGaN barrier layer and different from the second range of the second AlGaN barrier layer; and
wherein the second range of the first AlGaN barrier layer comprises one of same as the first range of the second AlGaN barrier layer and different from the first range of the second AlGaN barrier layer.
( Peng, page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b); Curatola, [0027], According to an embodiment, the first back-barrier region 202 has an aluminum concentration in the range of 1 to 2 percent, and more particularly about 1.5 percent and the second back barrier region 204 has an aluminum concentration in the range of 3.5 percent to 5 percent. More generally, the first back-barrier region 202 can have an aluminum concentration of less than 5 percent and the second back barrier region 204 has an aluminum concentration in the range of greater than four percent )
Regarding Claim 17 ( Original ), Curatola and Peng teach the method as claimed in claim 15, on which this claim is dependent, Curatola and Peng further teach:
wherein first AlGaN barrier layer has a thickness greater than 3nm ( Curatola, [0027], According to one embodiment, the buffer region 110 is a 75 nm thick layer of gallium nitride, … , and the second back-barrier region 204 is a layer of aluminum gallium nitride that is at least 125 nm thick ), wherein the second AlGaN barrier layer has a thickness greater than 3nm ( Curatola, [0027], According to one embodiment, the buffer region 110 is a 75 nm thick layer of gallium nitride, the first back-barrier region 202 is a layer of aluminum gallium nitride that is at least 125 nm thick , … ), wherein the thickness of the first barrier layer is one of: same as and different from the thickness of the second barrier layer, and wherein a thickness of a combination of the first AlGaN barrier layer and the second AlGaN barrier layer has a thickness less than a critical thickness for relaxation ( Peng, page 7, line 15, Consequently, the maximum values of xAl and d discussed herein are 0.4 and 100 nm, respectively ).
Regarding Claim 18 ( Original ), Curatola and Peng teach the method as claimed in claim 11, on which this claim is dependent, Curatola further teaches:
wherein the channel is an unintentionally doped channel ( Curatola, [0015], The difference in band gap and the presence of the polarization charges between the GaN buffer region 110 and the AlGaN barrier region 108 causes a first two-dimensional charge carrier gas region 118 to intrinsically arise near an interface between the buffer region 110 and the barrier region 108 ) that is one of Gallium Nitride (GaN) and Indium Gallium Nitride (InGaN).
Regarding Claim 19 ( Original ), Curatola and Peng teach the method as claimed in claim 11, on which this claim is dependent, Curatola further teaches:
wherein the charge generation layer is one of Aluminum Gallium Nitride (AlGaN), Scandium Aluminum Nitride (ScAlN), Indium Aluminum Nitride (InAlN), Indium Aluminum Gallium Nitride (InAlGaN), and Aluminum Nitride (AlN) ( Curatola, [0015], AlGaN barrier region 108 ).
Regarding Claim 20 ( Original ), Curatola and Peng teach the method as claimed in claim 11, on which this claim is dependent, Curatola further teaches:
a nucleation layer ( Curatola, [0016], After providing the base substrate 116 an AlN nucleation layer (not shown) and the lattice transition layer 114 is epitaxially grown on the base substrate 116 ) between the substrate and the buffer;
at least one interlayer ( Curatola, [0014], buffer region 110 ) between the channel and the charge generation layer ( Curatola, [0014], barrier region 108 ); and
a capping layer ( Curatola, [0018], a doped semiconductor region 128 that is formed on the main surface 104 ) on the charge generation layer ( Curatola, [0014], barrier region 108 ), wherein the at least one interlayer ( Curatola, [0027], According to one embodiment, the buffer region 110 is a 75 nm thick layer of gallium nitride ) is one of Aluminum Nitride (AlN) and Gallium Nitride (GaN), and wherein the capping layer is one of GaN ( Curatola, [0018], According to an embodiment, the doped semiconductor region 128 is formed from a p-type semiconductor nitride material (e.g., p-type GaN) ), AlN, and Silicon Nitride (SiNx), where x is a positive rational number.
Response to Arguments
Applicant's arguments filed 2/6/2026 have been fully considered but they are not persuasive.
Applicant's remarks regarding Claim 1 ( Currently Amended ): page 9, line 11 from bottom, cited “ Curatola does not disclose or suggest that the first back-barrier region 202 and the second back-barrier region 204 include pseudomorphically-strained back-barrier layers. Curatola also does not disclose or suggest that the first back-barrier region 202 and the second back-barrier region 204 have a combined thickness that is less than a critical thickness for relaxation. The back-barrier regions 202 and 204 of Curatola are described only as having different fixed aluminum concentrations with no discussion of strain management or pseudomorphic strain. (Curatola, par. [0025]). ”.
Examiners’ response: Please refer to claim 1 in Claim Rejections - 35 USC § 103 of this office action, cited “
Curatola and Peng do not explicitly disclose:
the double continuous grade barrier … including pseudomorphically-strained layers, and wherein a combined thickness of the lower continuously-graded back barrier and the upper continuously-graded back barrier is less than a critical thickness for relaxation;
However, Li teaches: page 4, left column, line 3, “ This means that our designed thickness of graded AlGaN interlayer ( the total thickness is 50nm ) is far smaller than the critical thickness; therefore, there should be a pseudomorphic growth of graded AlGaN interlayer on GaN layer ”.
Curatola and Peng and Li are all considered to be analogous to the claimed invention because they are forming high electron mobility heterostructure. Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to have modified Curatola ( [0012], an HEMT with a graded back-barrier design is disclosed; [0024], the back-barrier region 212 includes a first back-barrier region 202 …, and a second back-barrier region 204 beneath the first back-barrier region 202 ), to incorporate the teachings of Peng ( page 2, line 24, The aluminum (Al) composition linearly increases from 0 to xAl for the positive-graded AlGaN and subsequently decreases from xAl to 0 through the negative-graded AlGaN in the vertical direction, as shown in Figure 1(b) ) and Li ( page 4, left column, line 3, our designed thickness of graded AlGaN interlayer ( the total thickness is 50nm ) is far smaller than the critical thickness; … a pseudomorphic growth of graded AlGaN interlayer on GaN layer ), to implement that the back-to-back graded AlGaN (BGA) barrier layers consisting of a positive-graded AlGaN layer and a negative-graded AlGaN layer, and “ the double continuous grade barrier … including pseudomorphically-strained layers, and the thickness of graded AlGaN interlayer is smaller than the critical thickness ”. Doing so would provide three-dimensional electron gas (3DEG), and vertical conductive channel between the source and 3DEG is blocked by the 3DHG, and annihilation of threading dislocations (TDs); and therefore the performance ( e.g. on-state current, reduction of TDs densities ) of high electron mobility heterostructure can be improved. ”.
Conclusion
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/DA-WEI LEE/Examiner, Art Unit 2817
/MARLON T FLETCHER/Supervisory Primary Examiner, Art Unit 2817
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