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 .
Claims 1-22 are presented for examination
Information Disclosure Statement
The information disclosure statement (IDS) filed on April 3rd, 2023 is being considered by the examiner.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
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Annotated Fig. 9 – Mishra
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Annotated Fig.3 - Mishra
Claim(s) 1-21 is/are rejected under 35 U.S.C 103 as being unpatentable over Mishra et al. (US 20100289067 A1), hereinafter Mishra, in view of Torabi et al. (US 20210202729 A1); hereinafter Torabi, and further in view of Radulescu et al. (US 20210359118 A1); hereinafter Radulescu.
As to Claim 1, Mishra teaches: A field effect transistor (Fig.9) comprising:
a substrate (substrate 1);
a buffer region (buffer layer 2) over the substrate (substrate 1) and doped with a deep acceptor (Fig.9, [0026] “buffer layer 2 can be intentionally doped, such as with iron (Fe), carbon (C)”);
a backbarrier region (dispersion blocking layer 3) over the buffer region (buffer layer 2) having a thickness in a range of 50 to 5000 Angstroms (Fig.9, [0027] “less than 500 nm thick, for example, less than 200 nm thick”);
a channel region (channel layer 4) over the backbarrier region (dispersion blocking layer 3, Fig.9);
and
a gate contact (gate contact 7) over the channel region (channel layer 4) and between the source region (source contact 6) and the drain region (drain contact 9, Fig.9).
Mishra does not disclose the exact claimed thickness of the backbarrier region to be in a range of 50 to 5000 Angstroms but teaches a range of less than 500nm [5000 Angstroms]. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Mishra states that a thin layer allows for intentional doping which prevents electrons from getting trapped in the buffer layer reducing electron injection and trapping (Mishra, [0027]).
Mishra does not explicitly teach: at a concentration in a range of 1 X 1016 cm-3 to 1 X 1019 cm-3 ; Mishra discloses doping a buffer layer 2 [buffer region] with carbon but fails to include the concentration at which it was doped at.
However, in an analogous art, Torabi teaches: at a concentration in a range of 1 X 1016 cm-3 to 1 X 1019 cm-3 ([0037] “a beryllium dopant having a doping concentration in a range of 5×1016 to 3×1019 atoms/cm3; and, a carbon dopant having a doping concentration less than the doping concentration of the beryllium, but higher than 1×1016 atoms/cm3”); A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Torabi discloses that levels higher than the doping concentrations provided would result in significant degradation of the GaN crystal quality and results in higher levels of off state leakage and current collapse ([0011], [0020]).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Torabi to modify Mishra. One would be motivated to do so as the concentration range given by Torabi prevents the dopants from acting as high levels of long-lived traps which reduces the current collapse and keeps the off-state leakage at a low and manageable level (Torabi, [0023]).
However, Mishra as modified by Torabi does not explicitly teach: a source region and a drain region; each extending vertically into the channel region and arranged such that at least a portion of the channel region resides between the source region and the drain region. Mishra/Torabi does teach the source and drain region arranged such that at least a portion of the channel region [Mishra, channel layer 4] resides between the source region [Mishra, source contact 6] and the drain region [Mishra, drain contact 9, Fig. 9. [0009] “source contact and drain contact are in electrical contact with the 2DEG and the device is a depletion mode FET”] but fails to disclose each of them vertically extending into the channel region.
In an analogous art, Radulescu teaches: a source region (source 110) and a drain region (drain 112); each extending vertically into the channel region (channel region 104, [0038] “ the source 110 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”; [0040] “the drain 112 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”) and arranged such that at least a portion of the channel region resides between the source region and the drain region (Fig.5).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to modify the positioning of the HEMT source and drain region as taught by Mishra/Torabi to extend vertically into the channel region as taught by Radulescu. One would be motivated to do so as these features contribute to reducing on-state resistance and trapping effects (Radulescu, [0003]).
As to Claim 2, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 1 (Mishra, Fig.9; Torabi [0037]; Radulescu, Fig.5) wherein the buffer region (Mishra, buffer layer 2) is formed from gallium nitride (GaN) (Mishra, Fig.3, [0026] “can be a simple layer of a single material” [0030] “an iron doped GaN layer 22 on the nucleation layer”), and the backbarrier region (Mishra, dispersion blocking layer 3) is formed from aluminum gallium nitride (AlGaN) (Mishra, Fig.3, [0029] “ can be formed of a III-nitride layer… ternary alloy such as AxGa1-xN with 0≦x<1”).
As to Claim 3, Mishra/Radulescu teaches: The field effect transistor of claim 2 (Mishra Fig. 3,9; Torabi [0037]; Radulescu, Fig.5) wherein the buffer region (Mishra, buffer layer 2) is doped with the deep acceptor (Mishra, [0026] “buffer layer 2 can be intentionally doped, such as with iron (Fe), carbon (C)”).
Mishra/Radulescu does not explicitly teach: at a concentration in a range of 2 X 1016 cm-3 to 5 X 1017 cm-3. Mishra discloses doping a buffer layer 2 [buffer region] with carbon but fails to include the concentration at which it was doped at.
However, in an analogous art, Torabi teaches: at a concentration in a range of 2 X 1016 cm-3 to 5 X 1017 cm-3. ([0037] “a beryllium dopant having a doping concentration in a range of 5×1016 to 3×1019 atoms/cm3; and, a carbon dopant having a doping concentration less than the doping concentration of the beryllium, but higher than 1×1016 atoms/cm3”); A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Torabi discloses that levels higher than the doping concentrations provided would result in significant degradation of the GaN crystal quality and results in higher levels of off state leakage and current collapse ([0011], [0020]).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Torabi to modify Mishra/Radulescu. One would be motivated to do so as the concentration range given by Torabi prevents the dopants from acting as high levels of long-lived traps which reduces the current collapse and keeps the off-state leakage at a low and manageable level ([Torabi, [0023]).
As to Claim 4, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 2 (Mishra, Fig. 3, 9; Torabi [0037]; Radulescu, Fig.5) wherein the thickness of the backbarrier region (Mishra, dispersion blocking layer 3) is in a range of 200 to 2000 Angstroms (Mishra, [0027] “less than 500 nm thick, for example, less than 200 nm thick”).
Mishra/Torabi/Radulescu does not disclose the exact claimed thickness of the backbarrier region to be in a range of 200 to 2000 Angstroms but Mishra teaches a range of less than 500nm [Mishra, 5000 Angstroms]. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Mishra states that a thin layer allows for intentional doping which prevents electrons from getting trapped in the buffer layer reducing electron injection and trapping (Mishra, [0027]).
As to Claim 5, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 2 (Mishra, Fig. 3, 9; Torabi [0037]; Radulescu, Fig.5) wherein the thickness of the backbarrier region (Mishra, dispersion blocking layer 3) is in a range of 500 to 1500 Angstroms (Mishra, [0027] “less than 500 nm thick, for example, less than 200 nm thick”).
Mishra/Torabi/Radulescu does not disclose the exact claimed thickness of the backbarrier region to be in a range of 500 to 1500 Angstroms but Mishra teaches a range of less than 500nm [Mishra, 5000 Angstroms]. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Mishra states that a thin layer allows for intentional doping which prevents electrons from getting trapped in the buffer layer reducing electron injection and trapping (Mishra, [0027]).
As to Claim 6, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 2 (Mishra, Fig. 3, 9; Torabi [0037]; Radulescu, Fig.5) wherein the deep acceptor is carbon (Mishra, [0026] “buffer layer 2 can be intentionally doped, such as with iron (Fe), carbon (C)”).
As to Claim 7, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 2 (Mishra, Fig. 3, 9; Torabi [0037]; Radulescu, Fig.5) wherein the substrate (Mishra, substrate 1) is formed from silicon carbide (SiC) (Mishra, [0030] “Substrate 1 is silicon carbide”).
As to Claim 8, Mishra/Radulescu teaches: The field effect transistor of claim 1 (Mishra, Fig.9; Radulescu, Fig.5) wherein:
the substrate (Mishra, substrate 1) is formed from silicon carbide (SiC) ([0030] “Substrate 1 is silicon carbide”);
the buffer region (Mishra, buffer layer 2) is formed from gallium nitride (GaN) (Mishra, Fig.3, [0026] “can be a simple layer of a single material”; [0030] “an iron doped GaN layer 22 on the nucleation layer”);
the backbarrier region (Mishra, dispersion blocking layer 3) is formed from aluminum gallium nitride (AlGaN) (Mishra, Fig.3, [0029] “ can be formed of a III-nitride layer… ternary alloy such as AlxGa1-xN with 0≦x<1”); and
the buffer region is doped with the deep acceptor (Mishra, [0026] “buffer layer 2 can be intentionally doped, such as with iron (Fe), carbon (C)”)
Mishra/Radulescu does not explicitly teach: at a concentration in a range of 2 X 1016 cm-3 to 5 X 1017 cm-3. Mishra discloses doping a buffer layer 2 [buffer region] with carbon but fails to include the concentration at which it was doped at.
However, in an analogous art, Torabi teaches: at a concentration in a range of 2 X 1016 cm-3 to 5 X 1017 cm-3 ([0037] “a beryllium dopant having a doping concentration in a range of 5×1016 to 3×1019 atoms/cm3; and, a carbon dopant having a doping concentration less than the doping concentration of the beryllium, but higher than 1×1016 atoms/cm3”); A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Torabi discloses that levels higher than the doping concentrations provided would result in significant degradation of the GaN crystal quality and results in higher levels of off state leakage and current collapse ([0011], [0020]).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Torabi to modify Mishra/Radulescu. One would be motivated to do so as the concentration range given by Torabi prevents the dopants from acting as high levels of long-lived traps which reduces the current collapse and keeps the off-state leakage at a low and manageable level (Torabi, [0023]).
As to Claim 9, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 8 (Mishra, Fig.3,9; Torabi [0037]) wherein the thickness of the backbarrier region (Mishra, dispersion blocking layer 3) is in a range of 200 to 2000 Angstroms (Mishra, [0027] “less than 500 nm thick, for example, less than 200 nm thick”).
Mishra/Torabi/Radulescu does not disclose the exact claimed thickness of the backbarrier region to be in a range of 200 to 2000 Angstroms but Mishra teaches a range of less than 500nm [Mishra, 5000 Angstroms]. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Mishra states that a thin layer allows for intentional doping which prevents electrons from getting trapped in the buffer layer reducing electron injection and trapping (Mishra, [0027]).
As to Claim 10, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 8 (Mishra, Fig.3,9; Torabi [0037]; Radulescu, Fig.5) wherein the thickness of the backbarrier region (Mishra, dispersion blocking layer 3) is in a range of 500 to 1500 Angstroms (Mishra, [0027] “less than 500 nm thick, for example, less than 200 nm thick”).
Mishra/Torabi/Radulescu does not disclose the exact claimed thickness of the backbarrier region to be in a range of 500 to 1500 Angstroms but Mishra teaches a range of less than 500nm [Mishra, 5000 Angstroms]. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Mishra states that a thin layer allows for intentional doping which prevents electrons from getting trapped in the buffer layer reducing electron injection and trapping (Mishra, [0027]).
As to Claim 11, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 10 (Mishra, Fig.3,9; Torabi [0037]; Radulescu, Fig.5) wherein the deep acceptor dopant is carbon (Mishra, [0026] “buffer layer 2 can be intentionally doped, such as with iron (Fe), carbon (C)”).
As to Claim 12, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 8 (Mishra, Fig.3,9; Torabi [0037]; Radulescu, Fig.5) wherein the deep acceptor is carbon (Mishra, [0026] “buffer layer 2 can be intentionally doped, such as with iron (Fe), carbon (C)”).
As to Claim 13, Mishra teaches: The field effect transistor of claim 12 (Fig.3,9) further comprising:
a spacer region (Mishra, Fig.3, [0030] “0.6 nm AlN layer 51”) over the channel region (channel layer 4);
a top barrier region (Mishra, Fig. 3, [0030] “27 nm Al0.28Ga0.72N layer 52”) over the spacer region (Mishra, 0.6 nm AlN layer 51);
the spacer region is formed from aluminum nitride (AlN) (Mishra, [0030] “0.6 nm AlN layer 51”);
the top barrier region comprises aluminum, gallium, and nitride (AlGaN) (Mishra, [0030] “27 nm Al0.28Ga0.72N layer 52”);
and the cap region comprises gallium nitride (GaN).
Mishra does not explicitly teach: and a cap region over the top barrier region, wherein: the gate contact is over the cap region; Mishra discloses a 27 nm Al0.28Ga0.72N layer 52 [top barrier region] and a gate contact 7 [gate contact] but does not form a cap region which is over a top barrier layer or disclose a gate contact over a cap region as claimed.
However, in an analogous art, Torabi teaches: and a cap region (Fig.3C, GaN cap layer) over the top barrier region (Fig.3C, AlGaN barrier), wherein: the gate contact (Schottky gate contact, [0039]) is over the cap region (Fig.3C, [0039] “drain contacts and a Schottky gate contact, fabricated from the epitaxial structures shown in FIGS. 3A, 3B and 3C”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to supplement the FET structure as taught by Mishra to include a GaN cap layer. One would be motivated to do so as the GaN cap layer acts as a high resistivity buffer layer (Torabi, [0038]).
However, Mishra as modified by Torabi fails to explicitly teach: each of the source region and the drain region extends vertically through the cap region, the top barrier region, the spacer region, and into the channel region. Mishra discloses a 27 nm Al0.28Ga0.72N layer 52 [top barrier region] and a gate contact 7 [gate contact]. Torabi discloses a cap region [GaN cap layer] over a top barrier layer [AlGaN barrier]. Both remain silent on the source and drain contact extending vertically into the channel region.
In an analogous art, Radulescu teaches: each of the source region (source 110) and the drain region (drain 112) extends vertically through the cap region, the top barrier region (barrier layer 108), the spacer region (spacer layer 116), and into the channel region (channel layer 104, Fig. 5, [0038] “ the source 110 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”; [0040] “the drain 112 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to modify the positioning of the HEMT source and drain region as taught by Mishra/Torabi to extend vertically into the channel region as taught by Radulescu. One would be motivated to do so as these features contribute to reducing on-state resistance and trapping effects (Radulescu, [0003]).
As to Claim 14, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 8 (Mishra, Fig.3, 9; Torabi [0037]; Radulescu, Fig.5) wherein the backbarrier region (Mishra, dispersion blocking layer 3) is formed from AlxGa1-xN, wherein x = 0.01 – 0.15 (Mishra, Fig.3, [0029] “ can be formed of a III-nitride layer… ternary alloy such as AlxGa1-xN with 0≦x<1”).
Mishra/Torabi/Radulescu does not disclose the exact range of ‘x’ of the chemical compound to be in a range of x=0.01-0.15 but Mishra teaches a range 0≦x<1, which the claimed range lies entirely within. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. The range disclosed by Mishra is where the compound is graded or stepped in Al composition (Mishra, [0029]).
As to Claim 15, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 1 (Mishra, Fig.9; Torabi [0037]; Radulescu, Fig.5) wherein the backbarrier region (Mishra, dispersion blocking layer 3) is formed from AlxGa1-xN, wherein x = 0.01 – 0.15 (Mishra, Fig.3, [0029] “ can be formed of a III-nitride layer… ternary alloy such as AlxGa1-xN with 0≦x<1”).
Mishra/Torabi/Radulescu does not disclose the exact range of ‘x’ of the chemical compound to be in a range of x=0.01-0.15 but Mishra teaches a range 0≦x<1, which the claimed range lies entirely within. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. The range disclosed by Mishra is where the compound is graded or stepped in Al composition (Mishra, [0029]).
As to Claim 16, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 15 (Mishra, Fig.9; Torabi [0037]; Radulescu, Fig.5) wherein the channel region (Mishra, channel layer 4) has a thickness in a range of 30 to 500 Angstroms (Mishra, [0030] “thickness of less than 500 nm, such as about 50 nm”).
Mishra/Torabi/Radulescu does not disclose the exact claimed thickness of the channel region to be in a range of 30 to 500 Angstroms but Mishra teaches a range of less than 500nm [Mishra, 5000 Angstroms]. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Mishra states that a thick channel region is not needed since it is difficult to grow uninterrupted gallium nitride layers on silicon substrates (Mishra, [0010]).
As to Claim 17, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 1 (Mishra, Fig.9; Torabi [0037]; Radulescu, Fig.5) wherein the channel region (Mishra, channel layer 4) has a thickness in a range of 30 to 500 Angstroms (Mishra, [0030] “thickness of less than 500 nm, such as about 50 nm”).
Mishra/Torabi/Radulescu does not disclose the exact claimed thickness of the channel region to be in a range of 30 to 500 Angstroms but Mishra teaches a range of less than 500nm [Mishra, 5000 Angstroms]. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Mishra states that channel region within this region is the optimal thickness range for this since it is difficult to grow uninterrupted gallium nitride layers on silicon substrates (Mishra, [0010]).
As to Claim 18, Mishra teaches: The field effect transistor of claim 1 (Mishra Fig.9) further comprising:
a spacer region (0.6 nm AlN layer 51) over the channel region (channel layer 4) (Fig.3);
a top barrier region (27 nm Al0.28Ga0.72N layer 52) over the spacer region (0.6 nm AlN layer 51, Fig.3);
Mishra does not explicitly teach: and a cap region over the top barrier region, wherein: the gate contact is over the cap region; Mishra discloses a 27 nm Al0.28Ga0.72N layer 52 [top barrier region] and a gate contact 7 [gate contact] but does not form a cap region which is over a top barrier layer or disclose a gate contact over a cap region as claimed.
However, in an analogous art, Torabi teaches: and a cap region (Fig.3C, GaN cap layer) over the top barrier region (Fig.3C, AlGaN barrier), wherein: the gate contact (Schottky gate contact, [0039]) is over the cap region (Fig.3C, [0039] “drain contacts and a Schottky gate contact, fabricated from the epitaxial structures shown in FIGS. 3A, 3B and 3C”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to supplement the FET structure as taught by Mishra to include a GaN cap layer. One would be motivated to do so as the GaN cap layer acts as a high resistivity buffer layer (Torabi, [0038]).
However, Mishra as modified by Torabi fails to explicitly teach: and each of the source region and the drain region extends vertically through the cap region, the top barrier region, the spacer region, and into the channel region. Mishra discloses a 27 nm Al0.28Ga0.72N layer 52 [top barrier region] and a gate contact 7 [gate contact]. Torabi discloses a cap region [GaN cap layer] over a top barrier layer [AlGaN barrier]. Both remain silent on the source and drain contact extending vertically into the channel region.
In an analogous art, Radulescu teaches: and each of the source region (source 110) and the drain region (drain 112) extends vertically through the cap region, the top barrier region (barrier layer 108), the spacer region (spacer layer 116), and into the channel region (channel layer 104, Fig. 5, [0038] “ the source 110 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”; [0040] “the drain 112 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to modify the positioning of the HEMT source and drain region as taught by Mishra/Torabi to extend vertically into the channel region as taught by Radulescu. One would be motivated to do so as these features contribute to reducing on-state resistance and trapping effects (Radulescu, [0003]).
As to Claim 19, Mishra/Radulescu teaches: The field effect transistor of claim 18 (Mishra FIG. 9; Radulescu, Fig.5) wherein:
the substrate (Mishra, substrate 1) is formed from silicon carbide (SiC) (Mishra, [0030] “Substrate 1 is silicon carbide”);
the spacer region (Mishra, 0.6 nm AlN layer 51) is formed from aluminum nitride (AlN) (Mishra, Fig.3, [0030] “0.6 nm AlN layer 51”);
the top barrier region (Mishra, 27 nm Al0.28Ga0.72N layer 52) comprises aluminum gallium nitride (AlGaN) (Mishra, [0030] “27 nm Al0.28Ga0.72N layer 52”);
Mishra/Radulescu does not explicitly teach: and the cap region comprises gallium nitride (GaN).
However, in an analogous art, Torabi teaches: and the cap region comprises gallium nitride (GaN) (Fig.3C, GaN cap layer) .
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to supplement the FET structure as taught by Mishra/Radulescu to include a GaN cap layer. One would be motivated to do so as the GaN cap layer acts as a high resistivity buffer layer (Torabi, [0038]).
As to Claim 20, Mishra/Torabi/Radulescu teaches: The field effect transistor of claim 1 (Mishra, Fig.9; Torabi [0037]; Radulescu, Fig.5) wherein the field effect transistor is a high electron mobility transistor (Mishra, [0035] “Fig. 9 shows a cross-section of a GaN-on-Si depletion mode (D-mode) HEMT that has a dispersion blocking layer”).
As to Claim 21, Mishra teaches: A method of fabricating a field effect transistor comprising (Fig.9):
providing a substrate (Fig.9, substrate 1);
providing a buffer region (buffer layer 2) over the substrate (substrate 1) and doped with a deep acceptor (Fig.9, [0026] “buffer layer 2 can be intentionally doped, such as with iron (Fe), carbon (C)”);
providing a backbarrier region (dispersion blocking layer 3) over the buffer region (buffer layer 2) having a thickness in a range of 50-5000 Angstroms (Fig.9, [0027] “less than 500 nm thick, for example, less than 200 nm thick”);
providing a channel region (channel layer 4) over the backbarrier region (dispersion blocking layer 3, Fig.9); and
providing a gate contact (gate contact 7) over the channel region (channel layer 4) and between the source region (source contact 6) and the drain region (drain contact 9, Fig.9).
Mishra does not disclose the exact claimed thickness of the backbarrier region to be in a range of 50 to 5000 Angstroms but teaches a range of less than 500nm [5000 Angstroms]. A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Mishra states that a thin layer allows for intentional doping which prevents electrons from getting trapped in the buffer layer reducing electron injection and trapping (Mishra, [0027]).
Mishra does not explicitly teach: at a concentration: at a concentration in a range of 5 X 1016 cm-3 to 1 X 1018 cm-3. Mishra discloses doping a buffer layer 2 [buffer region] with carbon but fails to include the concentration at which it was doped at.
However, in an analogous art, Torabi teaches: of 5 X 1016 cm-3 to 1 X 1018 cm-3 ([0037] “a beryllium dopant having a doping concentration in a range of 5×1016 to 3×1019 atoms/cm3; and, a carbon dopant having a doping concentration less than the doping concentration of the beryllium, but higher than 1×1016 atoms/cm3”); A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Torabi discloses that levels higher than the doping concentrations provided would result in significant degradation of the GaN crystal quality and results in higher levels of off state leakage and current collapse ([0011], [0020]).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Torabi to modify Mishra. One would be motivated to do so as the concentration range given by Torabi prevents the dopants from acting as high levels of long-lived traps which reduces the current collapse and keeps the off-state leakage at a low and manageable level (Torabi, [0023]).
However, Mishra as modified by Torabi does not explicitly teach: providing a source region and a drain region; each extending vertically into the channel region and arranged such that at least a portion of the channel region resides between the source region and the drain region. Mishra/Torabi does teach the source and drain region arranged such that at least a portion of the channel region [Mishra, channel layer 4] resides between the source region [Mishra, source contact 6] and the drain region [Mishra, drain contact 9, Fig. 9. [0009] “source contact and drain contact are in electrical contact with the 2DEG and the device is a depletion mode FET”] but fails to disclose each of them vertically extending into the channel region.
In an analogous art, Radulescu teaches: providing a source region (source 110) and a drain region (drain 112); each extending vertically into the channel region (channel region 104, [0038] “ the source 110 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”; [0040] “the drain 112 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”) and arranged such that at least a portion of the channel region resides between the source region and the drain region (Fig.5).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to modify the positioning of the HEMT source and drain region as taught by Mishra/Torabi to extend vertically into the channel region as taught by Radulescu. One would be motivated to do so as these features contribute to reducing on-state resistance and trapping effects (Radulescu, [0003]).
Claim(s) 22 is/are rejected under 35 U.S.C 103 as being unpatentable over Mishra/Torabi/Radulescu as applied to claims 1-21 above, and further in view of Zhao et al. (US 20050014473 A1); hereinafter Zhao.
As to Claim 22, Mishra teaches: comprises a field effect transistor (Mishra, Fig. 9) comprising:
a substrate (substrate 1);
a buffer region (buffer layer 2) over the substrate (substrate 1) and doped with a deep acceptor (Fig.9, [0026] “buffer layer 2 can be intentionally doped, such as with iron (Fe), carbon (C)”);
a backbarrier region (dispersion blocking layer 3) over the buffer region (buffer layer 2) having a thickness in a range of 50 to 5000 Angstroms (Fig.9, [0027] “less than 500 nm thick, for example, less than 200 nm thick”);
a channel region (channel layer 4) over the backbarrier region (dispersion blocking layer 3, Fig.9);
a source region (source contact 6) and a drain region (drain contact 9) arranged such that at least a portion of the channel
region (channel layer 4) resides between the source region and the drain region (Fig. 9. [0009] “source contact and drain contact are in electrical contact with the 2DEG and the device is a depletion mode FET”; and
a gate contact (gate contact 7) over the channel region (channel layer 4) and between the source region (source contact 6) and the drain region (drain contact 9, Fig.9).
Mishra does not explicitly teach: at a concentration in a range of 1 X 1016 cm-3 to 1 X 1019 cm-3 ; Mishra discloses doping a buffer layer 2 [buffer region] with carbon but fails to include the concentration at which it was doped at.
However, in an analogous art, Torabi teaches: at a concentration in a range of 1 X 1016 cm-3 to 1 X 1019 cm-3 ([0037] “a beryllium dopant having a doping concentration in a range of 5×1016 to 3×1019 atoms/cm3; and, a carbon dopant having a doping concentration less than the doping concentration of the beryllium, but higher than 1×1016 atoms/cm3”); A prima facie case of obviousness exists where the claimed ranges or amounts “overlap or lie inside ranges disclosed by the prior art”. See MPEP 2144.05. Torabi discloses that levels higher than the doping concentrations provided would result in significant degradation of the GaN crystal quality and results in higher levels of off state leakage and current collapse ([0011], [0020]).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Torabi to modify Mishra. One would be motivated to do so as the concentration range given by Torabi prevents the dopants from acting as high levels of long-lived traps which reduces the current collapse and keeps the off-state leakage at a low and manageable level (Torabi, [0023]).
However, Mishra as modified by Torabi does not explicitly teach: a source region and a drain region; each extending vertically into the channel region and arranged such that at least a portion of the channel region resides between the source region and the drain region. Mishra/Torabi does teach the source and drain region arranged such that at least a portion of the channel region [Mishra, channel layer 4] resides between the source region [Mishra, source contact 6] and the drain region [Mishra, drain contact 9, Fig. 9. [0009] “source contact and drain contact are in electrical contact with the 2DEG and the device is a depletion mode FET”] but fails to disclose each of them vertically extending into the channel region.
In an analogous art, Radulescu teaches: a source region (source 110) and a drain region (drain 112); each extending vertically into the channel region (channel region 104, [0038] “ the source 110 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”; [0040] “the drain 112 may be structured and arranged to extend through the barrier layer 108 and extend partially through the channel layer 104”) and arranged such that at least a portion of the channel region resides between the source region and the drain region (Fig.5).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to modify the positioning of the HEMT source and drain region as taught by Mishra/Torabi to extend vertically into the channel region as taught by Radulescu. One would be motivated to do so as these features contribute to reducing on-state resistance and trapping effects (Radulescu, [0003]).
However, Mishra as modified by Torabi and Radulescu, does not explicitly teach: A user element ([001] “wireless communication systems”) comprising transmit and receive circuitry wherein at least one of the transmit and receive circuitry comprises a field effect transistor comprising: Mishra/Torabi/Radelescu do teach a field effect transistor (Mishra, Fig.9; Torabi, Fig. 3C; Radulescu, Fig. 5) specifically a High Electron Mobility transistor. Mishra also teaches the advantages of HEMTs for high power electronics including a larger bandgap and low thermal generation current (Mishra, [0002]).
In an analogous art, Zhao teaches: A user element ([001] “wireless communication systems”) comprising transmit (transmitter port 3) and receive circuitry (receiver port 8) wherein at least one of the transmit and receive circuitry comprises a field effect transistor (Fig. 1, FET 5) comprising:
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the instant application to apply the teaching of Zhao to the field effect transistor device as taught by Mishra/Torabi/Radulescu. One would be motivated to do so as HEMT switches allow for high power, low insertion loss, and low distortion performance in wireless communication systems (Zhao, Abstract).
Response to Arguments
Applicant’s arguments filed August 28th, 2026, with respect to the rejection(s) of Claims 1, 13, 18, 21, and 22 under 35 U.S.C. § 103 have been fully considered and are persuasive in light of the associated claim amendments.
Applicant argues in substance:
Mishra fails to disclose the aforementioned feature. In rejecting claim 1, the Examiner maps source contact 6 and drain contact 9 of Mishra to the claimed source and drain regions. However, as shown in Figure 9, source contact 6 and drain contact 9 are formed over barrier layer 5 and do not extend vertically into channel layer 4. Mishra likewise describes forming channel layer 4 and barrier layer 5 before forming ohmic source contact 6 and drain contact 9, without disclosing that the source and drain contacts extend through barrier layer 5 and into
channel layer 4. Mishra's disclosure that the source and drain contacts are in electrical contact with the 2DEG does not establish that the contacts physically extend vertically into the channel layer. Accordingly, Mishra fails to disclose the claimed structural relationship between the source and drain regions and the channel region.
This argument is persuasive. Therefore, the prior rejection has been withdrawn. However, upon further search and consideration, a new ground(s) of rejection is made in view of the combination of Mishra, Torabi and Radulescu (for Claims 1, 13, 18, and 21), as Radulescu discloses a source region and a drain region each extending into the channel region with at least a portion of the channel region residing between the source and drain region (See new rejection associated with Claims 1, 13, 18, 21, and 22 above).
Claim 22 was rejected under 35 U.S.C. § 103 as being unpatentable over Mishra in view of Torabi, and further in view of U.S. Patent Application Publication No. US 20050014473 Al to Zhao et al. (hereinafter "Zhao"). Applicant respectfully traverses. The standards for obviousness are set forth above. Claim 22 includes features similar to those recited in claim 1. Accordingly, claim 22 is allowable for at least the same reasons discussed above with respect to claim 1. Zhao does not cure the deficiencies of Mishra and Torabi discussed above. Accordingly, the combination of Mishra, Torabi, and Zhao fails to disclose or suggest each and every feature of claim 22, and withdrawal of the rejection of claim 22 is respectfully requested.
This argument is persuasive. Therefore, the prior rejection has been withdrawn. However, upon further search and consideration, a new ground(s) of rejection is made in view of the combination of Mishra, Torabi, Radulescu, and Zhao (for Claim 22), as Radulescu discloses a source region and a drain region each extending into the channel region with at least a portion of the channel region residing between the source and drain region (See new rejection associated with Claims 1, 13, 18, 21, and 22 above).
In the interest of compact prosecution, Examiner respectfully requests that Applicant please consider a telephone interview with the Examiner to discuss proposed claim amendments to overcome the rejection of Claims 1-22 before filing a written response to this Final Office Action. Perhaps Applicant could please consider amending Claim 1 to further clarify the shape and positioning of elements from Fig. 1 of the instant claims from Fig. 9 of Mishra (For example, Applicant can consider clarifying the shape of the gate contact as being T-shaped and that the gate contact is positioned in between the passivation region as shown in Fig. 1 of the instant claims). Applicant The Examiner would welcome such a discussion and is available at the telephone number provided below.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. 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 Mashal Ahmed whose telephone number is (571)270-1754. The examiner can normally be reached M-F, 9AM to 5 PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, William (Blake) Partridge can be reached at (571) 270-1402. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/MASHAL AHMED/Examiner, Art Unit 2812
/William B Partridge/Supervisory Patent Examiner, Art Unit 2812
