# US 10,872,952 B1 · MOSFET and power conversion circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,872,952 B1 - Document ID: US10872952B1 - Status: Granted - Kind: B1 - Application number: 16/497,797 - Filed: 2017-05-26 - Published: 2020-12-03 - Granted: 2020-12-22 - Earliest claimed: 2017-05-26 - Assignees: Shindengen Electric Manufacturing Co., Ltd. - Applicants: Shindengen Electric Manufacturing Co., Ltd. - Inventors: Daisuke Arai; Mizue Kitada - Web page: https://patentgrep.com/patent/US10872952B1 ## CPC - H10D 62/111: {Multiple RESURF structures, e.g. double RESURF or 3D-RESURF structures} - H02M 3/003: {Constructional details, e.g. physical layout, assembly, wiring or busbar connections} - H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators - H02M 7/48: using discharge tubes with control electrode or semiconductor devices with control electrode - H02M 7/537: using semiconductor devices only, e.g. single switched pulse inverters - H10D 30/668: {having trench gate electrodes, e.g. UMOS transistors} - H10D 62/105: {by having particular doping profiles, shapes or arrangements of PN junctions; by having supplementary regions, e.g. junction termination extension [JTE] (IGFETs having LDD or drain extension regions H10D30/601)} - H10D 62/125: {Shapes of junctions between the regions} - H10D 62/157: {Impurity concentrations or distributions} - H10D 62/393: {Body regions of DMOS transistors or IGBTs (cell layout of DMOS H10D62/127)} - H10D 84/144: {in antiparallel diode configurations} - H10D 62/159: {Shapes} - H10D 62/8325: {Silicon carbide} - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract A MOSFET according to the present invention includes a semiconductor base substrate having a super junction structure. A gate electrode is on a first main surface side of the semiconductor base substrate by way of a gate insulation film, wherein in a state where a total amount of dopant in an n-type column region differs from a total amount of dopant in a p-type column region, assuming a depth position where an average positive charge density ρ(x) becomes 0 as Xm′, assuming a deepest depth position of the surface of the depletion layer on the first main surface side as X0′, assuming a depth position where the reference average positive charge density ρ0(x) becomes 0 as Xm, and assuming a deepest depth position of the depletion layer on the first main surface side as X0, a relationship of |X0−X0′|<|Xm−Xm′| is satisfied. ## Claims ### Claim 1 A MOSFET comprising: a semiconductor base substrate having a super junction structure which is formed of an n-type column region and a p-type column region; and a gate electrode formed on a first main surface side of the semiconductor base substrate by way of a gate insulation film, wherein using a deepest depth position of a surface of a depletion layer on the first main surface side when the depletion layer extends most in the super junction structure by turning off the MOSFET as a reference, in a graph where a depth x at a predetermined depth position of the super junction structure is taken on an axis of abscissas, average positive charge density ρ(x) at the predetermined depth position of the super junction structure expressed by a following formula (1) when the super junction structure is depleted by turning off the MOSFET is taken on an axis of ordinates, and assuming a depth of a surface of the depletion layer on a second main surface side at a shallowest depth position when the depletion layer extends most in the super junction structure by turning off the MOSFET as a, in a curve which expresses the average positive charge density ρ(x), a value of the average positive charge density ρ(0) when x=0 becomes a negative value and a value of the average positive charge density ρ(a) when x=a becomes a positive value, an area of a region surrounded by a curve which expresses the average positive charge density ρ(x), a straight line when x=0, and an x axis is equal to an area of a region surrounded by the curve which expresses the average positive charge density ρ(x), a straight line when x=a, and the x axis, in a case that a state where a total amount of dopant in the n-type column region differs from a total amount of dopant in the p-type column region is brought about, using a surface of the super junction structure on the first main surface side as a reference, in the state where the total amount of dopant in the n-type column region differs from the total amount of dopant in the p-type column region, assuming a depth position where the average positive charge density ρ(x) becomes 0 as Xm′, and assuming a deepest depth position of the surface of the depletion layer on the first main surface side when the depletion layer extends most in the super junction structure by turning off the MOSFET as X0′, and using the surface of the super junction structure on the first main surface side as a reference, in a case where the average positive charge density when the super junction structure is depleted by turning off the reference MOSFET which is configured such that the total amount of dopant in the n-type column region is set equal to the total amount of dopant in the p-type column region is set as a reference average positive charge density ρ0(x), assuming a depth position where the reference average positive charge density ρ0(x) becomes 0 as Xm, and assuming a deepest depth position of the depletion layer on the first main surface side when the depletion layer extends most in the super junction structure by turning off the reference MOSFET as X0, a relationship of |X0−X0′|<|Xm−Xm′| is satisfied, [ Formula ⁢ ⁢ 1 ] ρ ⁡ ( x ) = q 2 ⁢ w ⁡ [ w n ⁡ ( x ) · ⁢ N d ⁡ ( x ) - w p ⁡ ( x ) · N a ⁢ ( x ) ] ( 1 ) (In the formula (1), Wn(x) indicates a width of the n-type column region at the predetermined depth position, Nd(x) indicates average density of a positive charge at the predetermined depth position of the n-type column region when the super junction structure is depleted by turning off the MOSFET, Wp(x) indicates a width of the p-type column region at the predetermined depth position, Na(x) indicates average density of a negative charge at the predetermined depth position of the p-type column region when the super junction structure is depleted by turning off the MOSFET, q indicates an elementary charge, and w indicates a positive constant which satisfies Wn(x)+Wp(x)=2w). ### Claim 2 (depends on 1) The MOSFET according to claim 1, wherein the average positive charge density ρ(x) is expressed by an upward convex curve projecting in a right upward direction. ### Claim 3 (depends on 1) The MOSFET according to claim 1, wherein in a graph where a depth x of the predetermined depth position of the super junction structure is taken on an axis of abscissas and a width Wp(x) at the predetermined depth position of the p-type column region or a width Wn(x) at the predetermined depth position of the n-type column region is taken on an axis of ordinates, the width Wp(x) at the predetermined depth position of the p-type column region is expressed by a following formula (2), and [ Formula ⁢ ⁢ 2 ] Wp ⁡ ( x ) = - [ - A ⁢ ⁢ exp ⁡ ( - x λ ) + B ] + W ⁢ ( symbols ⁢ ⁢ A , B , λ ⁢ ⁢ being ⁢ ⁢ constants ) ( 2 ) the width Wn(x) at the predetermined depth position of the n-type column region is expressed by a following formula (3). [ Formula ⁢ ⁢ 3 ] Wn ⁡ ( x ) = [ - A ⁢ ⁢ exp ⁡ ( - x λ ) + B ] + W ⁢ ( symbols ⁢ ⁢ A , B , λ ⁢ ⁢ being ⁢ ⁢ constants ) . ( 3 ) ### Claim 4 (depends on 1) The MOSFET according to claim 1, wherein in a graph where a depth x at a predetermined depth position of the super junction structure is taken on an axis of abscissas and average density Na(x) of a negative charge at the predetermined depth position of the p-type column region or average density Nd(x) of a positive charge at the predetermined depth position of the n-type column region when the super junction structure is depleted by turning off the MOSFET is taken on an axis of ordinates, the average density Na(x) of a negative charge at the predetermined depth position of the p-type column region when the super junction structure is depleted by turning off the MOSFET is expressed by a following formula (4), and [ Formula ⁢ ⁢ 4 ] Na ⁡ ( x ) = - [ - A ⁢ ⁢ exp ⁡ ( - x λ ) + B ] + N ⁢ ( symbols ⁢ ⁢ A , B , λ ⁢ ⁢ being ⁢ ⁢ constants ) ( 4 ) the average density Nd(x) of the positive charge at the predetermined depth position of the n-type column region when the super junction structure is depleted by turning off the MOSFET is expressed by a following formula (5). [ Formula ⁢ ⁢ 5 ] Nd ⁡ ( x ) = [ - A ⁢ ⁢ exp ⁡ ( - x λ ) + B ] + N ⁢ ( symbols ⁢ ⁢ A , B , λ ⁢ ⁢ being ⁢ ⁢ constants ) . ( 5 ) ### Claim 5 (depends on 1) The MOSFET according to claim 1, wherein in the case that in the state where the total amount of dopant in the n-type column region differs from the total amount of dopant in the p-type column region is brought about, using the surface of the super junction structure on the first main surface side as the reference, in the state where the total amount of dopant in the n-type column region differs from the total amount of dopant in the p-type column region, assuming the average positive charge density at the deepest depth position X0′ of the surface of the depletion layer on the first main surface side when the depletion layer extends most in the super junction structure by turning off the MOSFET as ρ(X0′), and assuming the reference average positive charge density at the deepest depth position X0 of the depletion layer on the first main surface side when the depletion layer extends most in the super junction structure by turning off the reference MOSFET as ρ0(X0), a relationship of ρ0(X0)>ρ(X0′) is satisfied. ### Claim 6 (depends on 1) The MOSFET according to claim 1, wherein in the case that in the state where the total amount of dopant in the n-type column region differs from the total amount of dopant in the p-type column region is brought about, using the surface of the super junction structure on the first main surface side as the reference, in the state where the total amount of dopant in the n-type column region differs from the total amount of dopant in the p-type column region, assuming the depth position where the average positive charge density ρ(x) becomes 0 as Xm′, and assuming the depth of the surface of the depletion layer on the second main surface side at a shallowest depth position when the depletion layer extends most in the super junction structure by turning off the MOSFET as X1′, assuming the depth position where the reference average positive charge density ρ0(x) becomes 0 as Xm, and assuming the shallowest depth position of the surface of the depletion layer on the second main surface side when the depletion layer extends most in the super junction structure by turning off the reference MOSFET as X1, a relationship of |Xm−Xm′|<|X1−X1′| is satisfied. ### Claim 7 (depends on 1) The MOSFET according to claim 1, wherein in the case that in the state where the total amount of dopant in the n-type column region differs from the total amount of dopant in the p-type column region is brought about, using the surface of the super junction structure on the first main surface side as the reference, in the state where the total amount of dopant in the n-type column region differs from the total amount of dopant in the p-type column region, assuming the average positive charge density at a depth X1′ of the surface of the depletion layer on the second main surface side at the shallowest depth position when the depletion layer extends most in the super junction structure by turning off the MOSFET as ρ(X1′), and assuming the reference average positive charge density at the shallowest depth position X1 of the surface of the depletion layer on the second main surface side when the depletion layer extends most in the super junction structure by turning off the reference MOSFET as ρ0(X1), a relationship of ρ0(X1)<ρ(X1′) is satisfied. ### Claim 8 (depends on 1) The MOSFET according to claim 1, wherein in a graph where a difference between the total amount of dopant in the n-type column region and the total amount of dopant in the p-type column region is taken on an axis of abscissas, and a depth X1 of a surface of the depletion layer on the second main surface side at a shallowest depth position when the depletion layer extends most in the super junction structure by turning off the MOSFET using the surface of the super junction structure on the first main surface side as a reference is taken on an axis of ordinates, in a case where the total amount of dopant in the p-type column region is larger than the total amount of dopant in the n-type column region, a curve which expresses the depth X1 is converged to a predetermined value when a difference between the total amount of dopant in the n-type column region and the total amount of dopant in the p-type column region is increased. ### Claim 9 (depends on 1) The MOSFET according to claim 1, wherein in the state where the total amount of dopant in the n-type column region differs from the total amount of dopant in the p-type column region, using a deepest depth position of a surface of a depletion layer on the first main surface side when the depletion layer extends most in the super junction structure by turning off the MOSFET as a reference, assuming a depth of a surface of the depletion layer on the second main surface side at a shallowest depth position when the depletion layer extends most in the super junction structure by turning off the MOSFET as a′, and assuming a depth of a surface of the depletion layer on the second main surface side at a shallowest depth position when the depletion layer extends most in the super junction structure by turning off the reference MOSFET as a, an area of a region surrounded by a curve which expresses the average positive charge density ρ(x), a straight line when x=a′, and an x axis is set equal to an area of a region surrounded by a curve which expresses the reference average positive charge density ρ0(x), a straight line when x=a, and an x axis. ### Claim 10 (depends on 1) The MOSFET according to claim 1, wherein using a deepest depth position of a surface of a depletion layer on the first main surface side when the depletion layer extends most in the super junction structure by turning off the MOSFET as a reference, assuming a shallowest depth position of a surface of the depletion layer on the second main surface side when the depletion layer extends most in the super junction structure by turning off the MOSFET as a, and assuming a depth of a depth position where the average positive charge density ρ(x) becomes 0 in the super junction structure as d, a relationship of 0