Attorney Docket Number: GUH-544US-L
Filing Date: 8/17/2023
Foreign Priority Date: 2/18/2021 (CN202110187733.0)
Inventors: Li et al.
Examiner: Thomas McCoy
DETAILED ACTION
This Office action responds to the amendments/arguments filed 1/30/2026.
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 . In the event the determination of the status of the application as to 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 a 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.
Acknowledgement
The Amendment filed on 1/30/2026, responding to the Office action mailed 10/31/2025, has been entered. Applicant amended claims 1, 6-7, and 12. Applicant cancelled claims 2-3 and claim 8. The present Office action is made with all the suggested amendments being fully considered. Accordingly, pending in this application are claims 1, 4-7, and 9-12.
Response to Arguments/Amendments
Applicant’s amendments to the claims have failed overcome the claim rejections under 35 U.S.C. 35 U.S.C. 102 and 35 U.S.C. 103 as previously formulated in the Non-Final Office action mailed on 10/31/2025. Applicant’s arguments are considered but are not persuasive. The Applicant’s response filed 1/30/2026 argues that the second oxide structure does not physically extend all the way to and terminating on the junction between the first end portion and the second end portion, but this specific limitation is not mentioned in the claims. The amended claim limitation simply recites that the second oxide structure extends along an upper surface of the first end portion to a junction of the first end portion and the second end portion, but it is noted that the examiner is entitled to the broadest reasonable interpretation of the claim language. Additionally, although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
In the instant case, it is noted that the limitation “…extending to…” as argued, i.e., “…physically extending all the way to and terminating on…” configuration is not recited in the body of the claims. Instead, applicant merely relied on limiting the argued configuration as “…extending to…”, which under BRI, is not precluded from being interpreted as, “…extending in the direction of…” as in Huang. Applicant is encouraged to recite the argued limitations in the body of the claims, so as to clearly distinguish the instant inventions from the prior art of record.
The applicant also argues that Huang doesn’t disclose a field plate structure comprising a gradually increasing thickness, instead comprising distinct “jumps” in thickness from the body side toward the drift side, but Huang (see, e.g., annotated fig. 1 below) explicitly discloses a gradually increasing thickness within the field plate structure (note that the field plate structure is the combination of the first drift oxide region 44 and the second drift oxide region 45).
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Annotated Fig. 1
The applicant also argues that Huang in view of Aoki fails to teach the claimed inclined second oxide structure configuration, but Aoki specifically discloses an inclined oxide structure (as seen in fig. 1 of Aoki) that curves/bends into an upper surface, and reasons for combining such limitations are disclosed in the claim rejection below (e.g., modifying the profile of the field plate structure thickness). Applicant also that the majority of the oxide layer’s upper surface of Aoki is horizontal and not inclined, but only the inclined structure configuration and the diagonal stacking of the oxide layers are considered necessary in regards to the modification as written below.
The applicant also argues that Huang does not disclose the angle limitation of 30-60 degrees because Huang emphasizes adjusting d2 relative to d1 to maintain breakdown voltage, but it’s noted this adjustment simply shows a plurality of potential angles and embodiments of the second drift oxide region, and the current embodiment of fig. 7I within Huang is simply one of these embodiments that continues to show this angle limitation well within the substantially large claimed range of 30 to 60 degrees. In addition, see the rejection of amended claim 1 below in regards to the claimed range of 30-60 degrees.
The applicant also argues that Huang does not a specific geometric profile in which the thickness of the field plate structure increases smoothly and gradually from the body region toward the drift region, this controlled thickness progression-implemented through the particular extension relationship of the second oxide structure to the junction, together with the upwardly extending inclined surface and the specified angular range, but it is noted that the examiner is entitled to the broadest reasonable interpretation of the claim language. Additionally, although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
In the instant case, it is noted that the limitation “…the thickness of the field plate structure gradually increases to a preset value along a direction from the end of the field plate structure close to the body region to the end of the field plate structure away from the body region…” as argued, i.e., “…the thickness of the field plate structure gradually increases to a preset value directly from the end of the second field oxide structure close to the body region to the end of the field plate structure away from the body region…” configuration is not recited in the body of the claims. Instead, applicant merely relied on limiting the argued configuration as “…the thickness of the field plate structure gradually increases to a preset value along a direction from the end of the field plate structure close to the body region to the end of the field plate structure away from the body region…”, which under BRI, is not precluded from being interpreted as, “…some portion of the field plate structure has a thickness that gradually increases to a preset value along a direction from the end of the field plate structure close to the body region to the end of the field plate structure away from the body region…” as in Huang. Applicant is encouraged to recite the argued limitations in the body of the claims, so as to clearly distinguish the instant inventions from the prior art of record.
Therefore, all previous claim rejections are upheld.
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 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, 4, 6-7, and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Huang (US 20190348533 A1) in view of Aoki (US 20200027956 A1).
Regarding claim 1, Huang (see, e.g., figs. 7A-7I) shows most aspects of the instant invention, including a laterally diffused metal oxide semiconductor device comprising:
a substrate (e.g., substrate 41 + semiconductor layer 41’);
a body region (e.g., channel well region 46), having a first conductivity type (see, e.g., paragraph 59 “…the channel well region 46 has the second conductivity type”) and being formed in the substrate (e.g., substrate 41 + semiconductor layer 41’);
a drift region (e.g., drift well region 42), having a second conductivity type (see, e.g., paragraph 59 “…wherein the drift well region 42 has the first conductivity type…”), being formed in the substrate (e.g., substrate 41 + semiconductor layer 41’) and being adjacent to the body region (e.g., channel well region 46), wherein the second conductivity type is opposite to the first conductivity type (see, e.g., paragraph 29 “For example the first conductivity type is N-type and the second conductivity type is P-type, or the first conductivity type is P-type and the second conductivity type is N-type”);
a field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45), formed on the drift region (e.g., drift well region 42), wherein a lower surface (see, e.g., bottom surface of second drift oxide region 45) of an end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) close to the body region (e.g., channel well region 46) is flush with an upper surface (e.g., top surface 41a) of the substrate (e.g., substrate 41 + semiconductor layer 41’), and the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) close to the body region (e.g., channel well region 46) also has an upwardly extending inclined surface, wherein a lower surface of an end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) away from the body region (e.g., channel well region 46) is lower than the upper surface (e.g., top surface 41a) of the substrate (e.g., substrate 41 + semiconductor layer 41’); wherein a thickness of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) gradually increases to a preset value along a direction from the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) close to the body region (e.g., channel well region 46) to an end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) away from the body region (e.g., channel well region 46);
a drain region (e.g., drain region 49), having the second conductivity type (see, e.g., paragraph 63 “The drain 49 has the same conductivity type as the drift well region 42 in this embodiment which is for example the first conductivity type”), and being in contact with the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) away (e.g., note that drain 49 is in contact with first drift oxide region 44 on opposite side from channel region 46) from the body region (e.g., channel well region 46), wherein the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) comprises:
a first oxide structure (e.g., first drift oxide region 44), wherein the first oxide structure (e.g., first drift oxide region 44) is the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) away from the body region (e.g., channel well region 46), wherein the first oxide structure (e.g., first drift oxide region 44) is formed on the drift region (e.g., drift well region 42), and an upper surface (e.g., top surface of first drift oxide region 44) of the first oxide structure (e.g., first drift oxide region 44) is not lower than the upper surface (e.g., top surface 41a) of the substrate (e.g., substrate 41 + semiconductor layer 41’); wherein along a direction from the body region (e.g., channel well region 46) to the drift region (e.g., drift well region 42), the first oxide structure (e.g., first drift oxide region 44) sequentially comprises a first end portion (see, e.g., first portion within annotated figure 2 below) and a second end portion (see, e.g., second portion within annotated figure 2 below); wherein a thickness of the first oxide structure (e.g., first drift oxide region 44) gradually increases to a preset value from the first end portion (see, e.g., first portion within annotated figure 2 below) toward the second end portion (see, e.g., second portion within annotated figure 2 below) and;
a second oxide structure (e.g., second drift oxide region 45), wherein the second oxide structure (e.g., second drift oxide region 45) is formed on an upper surface of an end of the drift region (e.g., drift well region 42) close to the body region (e.g., channel well region 46), and extends along an upper surface of the first end portion (see, e.g., first portion within annotated figure 2 below) to a junction of the first end portion (see, e.g., first portion within annotated figure 2 below) and the second end portion (see, e.g., second portion within annotated figure 2 below).
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Annotated Fig. 2
Huang (see, e.g., figs 7A-7I) fails to explicitly show wherein an angle between the inclined surface and the lower surface of the end of the field plate structure close to the body region is not less than 30 degrees and not more than 60 degrees.
However, Huang (see, e.g., fig. 8) shows the angle between the inclined surface and the lower surface of the end of the field plate structure close to the body region is substantial (the incline is very pronounced, thus substantially close to 45 degrees). Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to adopt this approximate 45 degree angle with the substantially inclined oxide structure, as the magnitude of the angle becomes a design choice based on the desired configuration between the first and second oxide structure and the thickness/height of the first oxide structure.
Huang (see, e.g., fig. 8), however, fails to show wherein the inclined surface is an upper surface of an end of the second oxide structure close to the body region.
Aoki (see, e.g., fig. 1), in a similar device to Huang, teaches an oxide structure (e.g., oxide layer 43) has an inclined surface having an upper surface (see, e.g., inclined profile of oxide layer 43 and curve into upper surface).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the inclined surface having an upper surface of Aoki within the second oxide structure of Huang onto the first oxide structure, in order to increase the thickness of the field plate structure in certain areas (areas with first oxide structure v.s. areas with first oxide structure + second oxide structure), changing the profile of the electric field distribution.
Regarding claim 4, Aoki (see, e.g., fig. 1) teaches a thickness of an oxide structure (e.g., oxide layer 43) is not greater than 1500 Å (see, e.g., paragraph 58 “The thickness of the oxide layer 43 preferably is set to be smaller than that of the oxide layer 41 and be within a range of 0.05 to 0.3 μm, in order to increase the effect of the field plate.” + note .05 μm, for instance, is equivalent to 500 Å).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the oxide layer thickness of Aoki within the second oxide structure of Huang, in order to manipulate the thickness of the field plate structure in regions comprising the surface of the second oxide structure, changing the profile of the electric field distribution.
Regarding claim 6, Huang (see, e.g., fig. 8) shows a source region (e.g., source 48), wherein the source region (e.g., source 48) has the second conductivity type (see, e.g., paragraph 63 “the source 48 has the same conductivity type as the drift well region 42 in the present embodiment, which is for example the first conductivity type.”) and is formed in an upper layer of the body region (e.g., channel well region 46), a polysilicon gate (e.g., gate 47 + paragraph 62 “…the gate 47 comprises a conductive material, for example but not limited to, a metal or a polysilicon…”), wherein the polysilicon gate (e.g., gate 47 + paragraph 62 “…the gate 47 comprises a conductive material, for example but not limited to, a metal or a polysilicon…”) is formed on the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) and extends along the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) to cover a portion of the substrate (e.g., substrate 41 + semiconductor layer 41’) between the source region (e.g., source 48) and the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45), shallow trench isolation structures (e.g., isolation oxide regions 43), wherein the shallow trench isolation structures (e.g., isolation oxide regions 43) are formed (Next, as shown in FIG. 7C, the isolation oxide region 43 and the first drift oxide region 44 are formed on the top surface 41a and in contact with the top surface 41a) in the substrate (e.g., substrate 41 + semiconductor layer 41’), wherein a first shallow trench isolation structure (e.g., right-side isolation oxide region 43) of the shallow trench isolation structures (e.g., isolation oxide regions 43) is in contact with the drain region (e.g., drain 49), and a portion of a lower surface (e.g., bottom surface of right-side isolation oxide region 43) is in contact with the drift region (e.g., drift well region 42).
Regarding claim 7, Huang (see, e.g., fig. 8) shows most aspects of the instant invention, including a method for preparing a laterally diffused metal oxide semiconductor device comprising:
Providing a substrate (e.g., substrate 41 + semiconductor layer 41’);
Forming a body region (e.g., channel well region 46) and a drift region (e.g., drift well region 42) that are adjacent to each other in the substrate (e.g., substrate 41 + semiconductor layer 41’), wherein the body region (e.g., channel well region 46) has a first conductivity type (see, e.g., paragraph 59 “…the channel well region 46 has the second conductivity type”), and the drift region (e.g., drift well region 42) has a second conductivity type (see, e.g., paragraph 59 “…wherein the drift well region 42 has the first conductivity type…”) opposite to the first conductivity type (see, e.g., paragraph 29 “For example the first conductivity type is N-type and the second conductivity type is P-type, or the first conductivity type is P-type and the second conductivity type is N-type”);
forming a field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) on the drift region (e.g., drift well region 42), wherein a lower surface (e.g., bottom surface of second drift oxide region 45) of an end of the field plate structure (see, e.g., first drift oxide region 44 + second drift oxide region 45) close to the body region (e.g., channel well region 46) is flush with an upper surface (e.g., top surface 41a) of the substrate (e.g., substrate 41 + semiconductor layer 41’), and the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) close to the body region (e.g., channel well region 46) has an upwardly extending inclined surface; wherein a lower surface of an end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) away from the body region (e.g., channel well region 46) is lower than the upper surface of the substrate (e.g., substrate 41 + semiconductor layer 41’); wherein a thickness of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) gradually increases to a preset value along a direction from the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) close to the body region (e.g., channel well region 46) to the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) away from the body region (e.g., channel well region 46); and
forming a drain region (e.g., drain 49) of the second conductivity type (see, e.g., paragraph 63 “The drain 49 has the same conductivity type as the drift well region 42 in this embodiment which is for example the first conductivity type”) in an upper layer of the drift region (e.g., drift well region 42), wherein the drain region (e.g., drain 49) is in contact with the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) away (e.g., note that drain 49 is in contact with first drift oxide region 44 on opposite side from channel region 46) from the body region (e.g., channel well region 46);
wherein forming the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) on the drift region (e.g., drift well region 42) comprises:
forming a first oxide structure (e.g., first drift oxide region 44) on the drift region (e.g., drift well region 42), wherein along a direction from the body region (e.g., channel well region 46) to the drift region (e.g., drift well region 42), the first oxide structure (e.g., first drift oxide region 44) sequentially comprises a first end portion (see, e.g., first portion within annotated figure 3 below) and a second end portion (see, e.g., second portion within annotated figure 3 below), and a thickness of the first oxide structure (e.g., first drift oxide region 44) gradually increases to a preset value from the first end portion (see, e.g., first portion within annotated figure 3 below) toward the second end portion (see, e.g., second portion within annotated figure 3 below), and forming a second oxide structure (e.g., second drift oxide region 45) on an upper surface of an end of the drift region (e.g., drift well region 42) close to the body region (e.g., channel well region 46), wherein the second oxide structure (e.g., second drift oxide region 45) extends along an upper surface of the first end portion (see, e.g., first portion within annotated figure 3 below) to a junction of the first end portion (see, e.g., first portion within annotated figure 3 below) and the second end portion (see, e.g., second portion within annotated figure 3 below); wherein the first oxide structure (e.g., first drift oxide region 44) is the end of the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) away from the body region (e.g., channel well region 46), wherein the thickness of the second end portion (e.g., second end portion of annotated fig. 3) on the side close to the first end portion (e.g., first end portion) is the preset value (e.g., thickness of second end portion, also the widest thickness of first drift oxide region 44, see green bar of annotated fig. 3 below).
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Annotated Fig. 3
Huang (see, e.g., figs 7A-7I) fails to explicitly show wherein an angle between the inclined surface and the lower surface of the end of the field plate structure close to the body region is not less than 30 degrees and not more than 60 degrees.
However, Huang (see, e.g., fig. 8) shows the angle between the inclined surface and the lower surface of the end of the field plate structure close to the body region is substantial (the incline is very pronounced, thus substantially close to 45 degrees). Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to adopt this approximate 45 degree angle with the substantially inclined oxide structure, as the magnitude of the angle becomes a design choice based on the desired configuration between the first and second oxide structure and the thickness/height of the first oxide structure.
Huang (see, e.g., figs 7A-7I) fails to explicitly show wherein an angle between the inclined surface and the lower surface of the end of the field plate structure close to the body region is not less than 30 degrees and not more than 60 degrees.
However, Huang (see, e.g., fig. 8) shows the angle between the inclined surface and the lower surface of the end of the field plate structure close to the body region is substantial (the incline is very pronounced, thus substantially close to 45 degrees). Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to adopt this approximate 45 degree angle with the substantially inclined oxide structure, as the magnitude of the angle becomes a design choice based on the desired configuration between the first and second oxide structure and the thickness/height of the first oxide structure.
Huang (see, e.g., fig. 8), however, fails to show the inclined surface is an upper surface of an end of the second oxide structure close to the body region, wherein an angle between the inclined surface.
Aoki (see, e.g., fig. 1), in a similar device to Huang, teaches an oxide structure (e.g., oxide layer 43) has an inclined surface having an upper surface (see, e.g., inclined profile of oxide layer 43 and curve into upper surface).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the inclined surface having an upper surface of Aoki within the second oxide structure of Huang onto the first oxide structure, in order to increase the thickness of the field plate structure in certain areas (areas with first oxide structure v.s. areas with first oxide structure + second oxide structure), changing the profile of the electric field distribution.
Regarding claim 12, Huang (see, e.g., figs 7A-7I) shows forming shallow trench isolation structures (e.g., isolation oxide regions 43) in the substrate (e.g., substrate 41 + semiconductor layer 41’), wherein a first shallow trench isolation structure (e.g., right-side isolation oxide region 43) of the shallow trench isolation structures (e.g., isolation oxide regions 43) is in contact with the drain region (e.g., drain 49), and a portion of a lower surface (e.g., bottom surface of right-side isolation oxide region 43) is in contact with the drift region (e.g., drift well region 42), forming a source region (e.g., source 48) with the second conductivity type (see, e.g., paragraph 63 “the source 48 has the same conductivity type as the drift well region 42 in the present embodiment, which is for example the first conductivity type.”) in an upper layer of the body region (e.g., channel well region 46), and forming a polysilicon gate (e.g., gate 47 + paragraph 62 “…the gate 47 comprises a conductive material, for example but not limited to, a metal or a polysilicon…”) on the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45), wherein the polysilicon gate (e.g., gate 47 + paragraph 62 “…the gate 47 comprises a conductive material, for example but not limited to, a metal or a polysilicon…”) extends along the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45) to cover a portion of the substrate (e.g., substrate 41 + semiconductor layer 41’) between the source region (e.g., source 48) and the field plate structure (e.g., first drift oxide region 44 + second drift oxide region 45).
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Huang in view of Aoki further in view of Boos (US 20150194421 A1).
Regarding claim 5, Huang (see, e.g., figs. 7A-7I) shows the first oxide structure (e.g., first drift oxide region 44) includes a local silicon isolation oxide structure (see, e.g., paragraph 60 “…the first drift oxide region 44 are, for example but not limited to, local oxidation of silicon (LOCOS) structure”).
Huang in view of Aoki, however, fails to teach the local silicon isolation oxide structure is made by a recess portion.
Boos (see, e.g., fig. 1), in a similar device to Huang in view of Aoki, teaches a local silicon isolation oxide structure (e.g., LOCOS layer, see paragraph 18) is made by a recess process (see, e.g., paragraph 18 “forming a recess in a silicon layer over the substrate; locally [oxidizing] the silicon layer within the recess to partially consume the silicon layer beneath the recess, thereby forming a LOCOS layer of silicon oxide filling the recess…”).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to use the recess process of Boos to form the LOCOS of Huang in view of Aoki, as a recess process was well-known in the art at the time of filing the invention to form a local silicon isolation oxide structure, as taught by Boos.
Claim 9 is rejected under 35 U.S.C. 103 as being unpatentable over Huang in view of Aoki further in view of Lei (CN 110943030 A).
Regarding claim 9, Huang (see, e.g., figs. 7A-7I) shows a local silicon isolation oxide structure (see, e.g., paragraph 60 “…the first drift oxide region 44 are, for example but not limited to, local oxidation of silicon (LOCOS) structure”).
Huang in view of Aoki, however, fails to teach forming of the first oxide structure on the drift region comprises: forming a hard mask layer on the substrate, and forming a groove in the hard mask layer, wherein the groove exposes a portion of the substrate where a predetermined area of the first oxide structure is located; forming a sidewall structure on sidewalls of the groove, wherein the sidewall structure is in contact with the hard mask layer, and a lower surface of the sidewall structure is flush with a bottom of the groove; and forming the first oxide structure at the bottom of the groove by performing a local thermal oxidation process.
Lei (see, e.g., figs. 1-9), in a similar device to Huang in view of Aoki, teaches forming an oxide structure (e.g., field oxide layer 108) comprises: forming a hard mask layer (e.g., pad oxide layer 102 + sacrificial dielectric layer 103) on a substrate (e.g., substrate 101), and forming a groove (e.g., recess 105) in the hard mask layer (e.g., pad oxide layer 102 + sacrificial dielectric layer 103), wherein the groove (e.g., recess 105) exposes a portion of the substrate (e.g., substrate 101), forming a sidewall structure (e.g., side wall 107) on sidewalls of the groove (e.g., recess 105), wherein the sidewall structure (e.g., sidewall 107) is in contact with the hard mask layer (e.g., pad oxide layer 102 + sacrificial dielectric layer 103), and a lower surface of the sidewall structure (e.g., sidewall 107) is flush with a bottom of the groove (e.g., recess 105), and forming the first oxide structure (e.g., field oxide layer 108) at the bottom of the groove (e.g., recess 105) by performing a local thermal oxidation process (see, e.g., paragraph text “…then performing a thermal oxidation on the exposed silicon substrate growing a field oxide layer…”).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the process of Lei within the method of Huang in view of Aoki, as the oxide structure forming process was well-known in the art at the time of filing the invention, as taught by Lei.
Claims 10-11 are rejected under 35 U.S.C. 103 as being unpatentable over Huang in view of Aoki further in view of Kawahara (US 20180226502 A1).
Regarding claim 10, Huang in view of Aoki fails to teach wherein the forming of the second oxide structure on the upper surface of the end of the drift region close to the body region comprises: forming an oxide film on the upper surface of the substrate; forming a photoresist mask layer on the oxide film, wherein the photoresist mask layer covers a portion of the oxide film where a predetermined region of the second oxide structure is located; and removing excess oxide film by performing a wet etching process, to obtain the second oxide structure consisting of the remaining oxide film in the predetermined region of the second oxide structure.
Kawahara (see, e.g., fig. 3), in a similar device to Huang in view of Aoki, teaches forming an oxide film (see, e.g., paragraph 38 “…onto the top surface 304 to form a silicon oxide layer…”) on the upper surface (see, e.g., paragraph 38 “…onto the top surface 304…) of the substrate (e.g., substrate 302), forming a photoresist mask layer (e.g., see, e.g., paragraph 38 “…followed by forming a photoresist mask on the top surface 304…”) on the oxide film (e.g., see, e.g., paragraph 38 “…silicon oxide layer…”), removing excess oxide film by performing a wet etching process (see, e.g., paragraph 38 “followed by an buffered hydrofluoric acid (BHF) etch to expose the transistor region…”), to obtain the oxide structure (e.g., dielectric layer 332 + paragraph 38 “The dielectric layer 332 may include an oxide layer…” + remaining portions of paragraph 38).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the oxide forming structure of Kawahara within the method of Huang in view of Aoki, as the oxide structure forming process was well-known in the art at the time of filing the invention, as taught by Kawahara.
Regarding claim 11, Aoki (see, e.g., fig. 1) teaches a thickness of an oxide structure (e.g., oxide layer 43) is not greater than 1500 Å (see, e.g., paragraph 58 “The thickness of the oxide layer 43 preferably is set to be smaller than that of the oxide layer 41 and be within a range of 0.05 to 0.3 μm, in order to increase the effect of the field plate.” + note .05 μm, for instance, is equivalent to 500 Å).
Accordingly, it would have been obvious to one of ordinary skill in the art at the time of filing the invention to include the oxide layer thickness of Aoki within the second oxide structure of Huang in view of Aoki further in view of Kawahara, in order to manipulate the thickness of the field plate structure in regions comprising the surface of the second oxide structure, changing the profile of the electric field distribution.
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.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to THOMAS WILSON MCCOY whose telephone number is (571)272-0282. The examiner can normally be reached 8:30-6:00 EST.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Wael Fahmy can be reached at (571) 272-1705. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/THOMAS WILSON MCCOY/Examiner, Art Unit 2814 /WAEL M FAHMY/Supervisory Patent Examiner, Art Unit 2814
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