Silicon carbide semiconductor device and method for manufacturing the same

• US 8,872,242 B2
• Filed: 04/17/2013
• Issued: 10/28/2014
• Est. Priority Date: 05/22/2012
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Masuda, Takeyoshi, Hayashi, Hideki
• Primary Examiner(s): PRENTY, MARK V
• Application Number:
  US13/864,917
• Publication Number:
  US 20130313568A1
• Time in Patent Office: 559 Days
• Field of Search: 257/263, 257/77, 257/E29.313
• US Class Current: 257/263
• CPC Class Codes: H01L 21/28008 Making conductor-insulator-semiconductor electrodes
• CPC Class Codes: H01L 29/0692 Surface layout
• CPC Class Codes: H01L 29/1066 Gate region of field-effect devices with PN junction gate
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/66068 the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
• CPC Class Codes: H01L 29/8083 Vertical transistors SIT H01L29/7722

Abstract

A silicon carbide substrate has a first conductivity type. The silicon carbide substrate has a first surface provided with a first electrode and a second surface provided with first trenches arranged to be spaced from one another. A gate layer covers an inner surface of each of the first trenches. The gate layer has a second conductivity type different from the first conductivity type. A filling portion fills each of the first trenches covered with the gate layer. A second electrode is separated from the gate layer and provided on the second surface of the silicon carbide substrate. A gate electrode is electrically insulated from the silicon carbide substrate and electrically connected to the gate layer. Thereby, a silicon carbide semiconductor device capable of being easily manufactured can be provided.

Claims

1. A silicon carbide semiconductor device, comprising:

a first electrode;

a silicon carbide substrate having a first surface provided with said first electrode and a second surface opposite to said first surface, and having a first conductivity type, said silicon carbide substrate having a plurality of first trenches arranged to be spaced from one another in said second surface;

a gate layer covering an inner surface of each of said plurality of first trenches and having a second conductivity type different from said first conductivity type;

a filling portion filling each of said plurality of first trenches covered with said gate layer;

a second electrode separated from said gate layer and provided on said second surface of said silicon carbide substrate; and

a gate electrode electrically insulated from said silicon carbide substrate and electrically connected to said gate layer,

wherein said filling portion is made of one of a semiconductor and a conductor, and separated from said silicon carbide substrate by said gate layer, and

wherein said gate electrode is in contact with said filling portion.

2. A silicon carbide semiconductor device, comprising:

a first electrode;

a silicon carbide substrate having a first surface provided with said first electrode and a second surface opposite to said first surface, and having a first conductivity type, said silicon carbide substrate having a plurality of first trenches arranged to be spaced from one another in said second surface;

a gate layer covering an inner surface of each of said plurality of first trenches and having a second conductivity type different from said first conductivity type;

a filling portion filling each of said plurality of first trenches covered with said gate layer;

a second electrode separated from said gate layer and provided on said second surface of said silicon carbide substrate; and

a gate electrode electrically insulated from said silicon carbide substrate and electrically connected to said gate layer,

wherein said silicon carbide semiconductor device includes a plurality of cells having said plurality of first trenches, respectively, in a planar layout, and

wherein said silicon carbide substrate has a second trench in said second surface at a position where at least three of said plurality of cells are adjacent to one another.

3. A silicon carbide semiconductor device, comprising:

a first electrode;

a silicon carbide substrate having a first surface provided with said first electrode and a second surface opposite to said first surface, and having a first conductivity type, said silicon carbide substrate having a plurality of first trenches arranged to be spaced from one another in said second surface;

a gate layer covering an inner surface of each of said plurality of first trenches and having a second conductivity type different from said first conductivity type;

a filling portion filling each of said plurality of first trenches covered with said gate layer;

a second electrode separated from said gate layer and provided on said second surface of said silicon carbide substrate; and

a gate electrode electrically insulated from said silicon carbide substrate and electrically connected to said gate layer,

wherein said silicon carbide substrate includes a first layer and a second layer provided on said first layer and forming said second surface of said silicon carbide substrate,

wherein each of said plurality of first trenches penetrates said second layer and reaches into said first layer, and

wherein said first layer has an impurity concentration higher than that of said second layer.

4. The silicon carbide semiconductor device according to claim 3, wherein each of said plurality of first trenches has a depth of not less than 5 μ

m in said first layer.