Silicon carbide semiconductor device and method for manufacturing the same

• US 20090272983A1
• Filed: 07/09/2009
• Published: 11/05/2009
• Est. Priority Date: 11/08/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Takeuchi, Yuichi, Kumar, Malhan Rajesh
• Granted Patent: US 8,097,917 B2
• Time in Patent Office: Days
• US Class Current: 257/77
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/66666 Vertical transistors H01L29/66712, H01L29/66742 take precedence
• CPC Class Codes: H01L 29/7391 Gated diode structures
• CPC Class Codes: H01L 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/7828 without inversion channel, e.g. vertical ACCUFETs, normally-on vertical MISFETs
• CPC Class Codes: Y10S 438/931 Silicon carbide semiconductor

Abstract

A silicon carbide semiconductor device includes: a semiconductor substrate having a silicon carbide substrate, a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer; a trench penetrating the second and the third semiconductor layers to reach the first semiconductor layer; a channel layer on a sidewall and a bottom of the trench; an oxide film on the channel layer; a gate electrode on the oxide film; a first electrode connecting to the third semiconductor layer; and a second electrode connecting to the silicon carbide substrate. A position of a boundary between the first semiconductor layer and the second semiconductor layer is disposed lower than an utmost lowest position of the oxide film.

Claims

1-7. -7. (canceled)

8. A silicon carbide semiconductor device comprising:

a semiconductor substrate including a silicon carbide substrate having a first conductive type or a second conductive type, a first semiconductor layer made of first conductive type silicon carbide and having an impurity concentration lower than that of the silicon carbide substrate, a second semiconductor layer made of second conductive type silicon carbide, and a third semiconductor layer made of the first conductive type silicon carbide, which are stacked in this order;

a trench disposed in a cell region of the semiconductor substrate and penetrating the second and the third semiconductor layers to reach the first semiconductor layer;

a channel layer having the first conductive type and disposed on a sidewall and a bottom of the trench;

an oxide film disposed on the channel layer in the trench and including a part for functioning as a gate oxide film;

a gate electrode disposed on a surface of the oxide film in the trench;

a first electrode electrically connecting to the third semiconductor layer; and

a second electrode electrically connecting to the silicon carbide substrate, wherein

a position of a boundary between the first semiconductor layer and the second semiconductor layer is disposed lower than an utmost lowest position of the oxide film in the trench,

the silicon carbide substrate has the first conductive type,

a plurality of second trenches are disposed in the silicon carbide substrate, each second trench being disposed from a backside of the silicon carbide substrate to the first semiconductor layer,

the second trenches are embedded with an impurity layer having the second conductive type, and

the second electrode contacts the silicon carbide substrate and the impurity layer.

9. A silicon carbide semiconductor device comprising:

a semiconductor substrate including a silicon carbide substrate having a first conductive type or a second conductive type, a first semiconductor layer made of first conductive type silicon carbide and having an impurity concentration lower than that of the silicon carbide substrate, a second semiconductor layer made of second conductive type silicon carbide, and a third semiconductor layer made of the first conductive type silicon carbide, which are stacked in this order;

a trench disposed in a cell region of the semiconductor substrate and penetrating the second and the third semiconductor layers to reach the first semiconductor layer;

a channel layer having the first conductive type and disposed on a sidewall and a bottom of the trench;

an oxide film disposed on the channel layer in the trench and including a part for functioning as a gate oxide film;

a gate electrode disposed on a surface of the oxide film in the trench;

a first electrode electrically connecting to the third semiconductor layer; and

a second electrode electrically connecting to the silicon carbide substrate, wherein

a position of a boundary between the first semiconductor layer and the second semiconductor layer is disposed lower than an utmost lowest position of the oxide film in the trench,

the silicon carbide substrate has the second conductive type,

a plurality of second trenches are disposed in the substrate, each second trench being disposed from a backside of the silicon carbide substrate to the first semiconductor layer,

the second trenches are embedded with an impurity layer having the first conductive type, and

the second electrode contacts the silicon carbide substrate and the impurity layer.

10-16. -16. (canceled)