Silicon carbide semiconductor device and silicon carbide semiconductor device manufacturing method

Patent metadata

Field	Value
Publication number	US-2016336392-A1
Application number	US-201515111642-A
Country	US
Kind code	A1
Filing date	Jan 16, 2015
Priority date	Jan 28, 2014
Publication date	Nov 17, 2016
Grant date	—

Abstract

A silicon carbide semiconductor device capable of achieving a decrease in ON resistance and an increase in breakdown voltage and a method for manufacturing a silicon carbide semiconductor device. A silicon carbide semiconductor device includes a silicon carbide substrate and a drift layer. The drift layer includes a breakdown voltage holding layer extending from a point where a doping concentration has a predetermined value to a surface of the drift layer. The doping concentration in the breakdown voltage holding layer continuously decreases from the point where the doping concentration has the predetermined value to a modulation point located further toward the surface of the drift layer than a midpoint in a film thickness direction of the breakdown voltage holding layer. The doping concentration in the breakdown voltage holding layer continuously increases from the modulation point to the surface of the drift layer.

First claim

1 - 16 . (canceled)

17 : A silicon carbide semiconductor device, comprising:
a silicon carbide substrate of a first conductivity type; a drift layer of the first conductivity type that is formed on said silicon carbide substrate and is doped with a dopant; and a plurality of body regions of a second conductivity type located at an interval from each other in a surface layer of said drift layer, wherein said plurality of body regions sandwich a region in the surface layer of said drift layer, and the region is a JFET region, said JFET region and said body region are cyclically formed, a surface of said drift layer is a lower surface of said body region, a doping concentration N F [cm −3 ] in the surface of said drift layer is expressed by
N F =8.52×10 19 V 1.19   [Math 1]

where V [V] represents a rated breakdown voltage, said drift layer includes a breakdown voltage holding layer that extends from the surface of said drift layer in a film thickness direction and that has a film thickness of d [μm], said breakdown voltage holding layer has a film thickness d [μm] in a range expressed by
3.40×10 −3 V 1.10 <d< 4.16×10 −3 V 1.10 ,  [Math 2]

the doping concentration, which is greater than or equal to 3×10 15 cm −3 and less than or equal to 1×10 17 cm −3 , of said dopant in said breakdown voltage holding layer from the surface of said drift layer to a point of the depth d [μm]:
continuously decreases in a film thickness direction of said breakdown voltage holding layer toward the surface of said drift layer from the point of the depth d [μm] from the surface of said drift layer to a modulation point located further toward the surface of said drift layer than a midpoint in the film thickness direction of said breakdown voltage holding layer, and
continuously increases in the film thickness direction of said breakdown voltage holding layer toward the surface of said drift layer from said modulation point to the surface of said drift layer, and
when 0≦x<d min , an ideal doping concentration distribution h (N F , L fp , L j , x) [cm −3 ] is expressed by

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h

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λ

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when d min ≦x<d, the ideal doping concentration distribution h (N F , L fp , L j , x) [cm −3 ] is expressed by

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h

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and by using the ideal doping concentration distribution h (N F , L fp , L j , x) calculated from the expressions, a concentration distribution g(x) [cm −3 ] of said breakdown voltage holding layer is expressed by
(1−0.2) h ( N F ,L fp ,L j ,x )< g ( x )<(1+0.2) h ( N F ,L fp ,L j ,x )  [Math 5]

where an x axis direction represents said film thickness direction, x=0 [μm] represents the surface of said drift layer, x=d [μm] represents the point of the depth d [μm] from the surface of said drift layer, d min [μm] represents a distance from the surface of said drift layer to said modulation point in the film thickness direction, L fp [μm] represents an arrangement pitch of said body regions, L j [μm] represents a width of said JFET region located between said body regions adjacent to each other, and λ [m 5 C 2 N/V 2 F 2 ] represents a negative value that defines a concentration distribution.

18 : A silicon carbide semiconductor device, comprising:
a silicon carbide substrate of a first conductivity type; a drift layer of the first conductivity type that is formed on said silicon carbide substrate and is doped with a dopant; and a plurality of body regions of a second conductivity type located at an interval from each other in a surface layer of said drift layer, wherein said plurality of body regions sandwich a region in the surface layer of said drift layer, and the region is a JFET region, said JFET region is discretely formed in a y direction and a z direction, which are two pl

Assignees

• Mitsubishi Electric Corp

Inventors

• Tominaga Takaaki
• Kawabata Naoyuki
• Tomita Nobuyuki

Classifications

• H10D30/662

  having a drift region having a doping concentration that is higher between adjacent body regions relative to other parts of the drift region · CPC title

• H10D62/128

  Anode regions of diodes · CPC title

• H10D62/834

  further characterised by the dopants · CPC title

• H10D64/64

  Electrodes comprising a Schottky barrier to a semiconductor · CPC title

• H10D62/8325

  Silicon carbide · CPC title