Wide bandgap semiconductor device and method for manufacturing the same

• US 20030201482A1
• Filed: 04/10/2003
• Published: 10/30/2003
• Est. Priority Date: 04/24/2002
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Tanaka, Hideaki, Hoshi, Masakatsu, Shimoida, Yoshio, Kaneko, Saichirou
• Granted Patent: US 6,737,677 B2
• Time in Patent Office: Days
• US Class Current: 257/302
• CPC Class Codes: H01L 21/0465 using masks
• CPC Class Codes: H01L 21/049 Conductor-insulator-semiconductor electrodes, e.g. MIS contacts
• CPC Class Codes: H01L 21/8213 the substrate being a semiconductor, using SiC technology H01L21/8258 takes precedence
• CPC Class Codes: H01L 27/0605 integrated circuits made of compound material, e.g. AIIIBV
• 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

Abstract

The present invention provides a wide bandgap semiconductor device encompassing: (a) a drift layer of a first conductivity type made of a wide bandgap semiconductor material; (b) a body region of a second conductivity type made of the wide bandgap semiconductor material, disposed at the top surface of and in the drift layer; (c) a source region of the first conductivity type disposed in the body region; (d) a channel layer of the first conductivity type, disposed in the body region neighboring to the source region and further disposed in the drift layer; and (e) a gate electrode including semiconductor layer at the bottom so that the semiconductor layer directly contact with the top surface of the channel layer, the semiconductor layer made of a semiconductor material having a different bandgap energy from that of the wide bandgap semiconductor material.

Claims

1. A wide bandgap semiconductor device comprising:

a drift layer of a first conductivity type made of a wide bandgap semiconductor material;

a body region of a second conductivity type opposite to the first conductivity type made of the wide bandgap semiconductor material, disposed at the top surface of and in the drift layer;

a source region of the first conductivity type made of the wide bandgap semiconductor material, disposed at the top surface of and in the body region;

a channel layer of the first conductivity type made of the wide bandgap semiconductor material, disposed at the top surface of and in the body region neighboring to the source region and further disposed at the top surface of and in the drift layer; and

a gate electrode including semiconductor layer at the bottom so that the semiconductor layer directly contact with the top surface of the channel layer, the semiconductor layer made of a semiconductor material having a different bandgap energy from that of the wide bandgap semiconductor material.

2. The wide bandgap semiconductor device of claim 1, wherein an edge of the gate electrode reaches to the source region.

3. The wide bandgap semiconductor device of claim 1, wherein at least lower portion of the gate electrode comprises the semiconductor layer in which impurities are doped in an nonuniform profile so that the bottom of the gate electrode can manifest a high resistivity characteristics.

4. The wide bandgap semiconductor device of claim 3, wherein the impurity concentration decreases from the top surface of the gate electrode to the bottom surface so that the bottom of the gate electrode can manifest the high resistivity characteristics.

5. The wide bandgap semiconductor device of claim 1, wherein at least lower portion of the gate electrode comprises silicon layer in which impurities are doped in an nonuniform profile so that the bottom of the silicon layer can manifest a high resistivity characteristics.

6. The wide bandgap semiconductor device of claim 5, wherein the silicon layer is selected from the group consisting of an amorphous silicon, a polysilicon and a single crystalline silicon.

7. The wide bandgap semiconductor device of claim 5, wherein the impurity concentration decreases from the top surface of the silicon layer to the bottom surface so that the bottom of the silicon layer can manifest the high resistivity characteristics.

8. The wide bandgap semiconductor device of claim 5, wherein the impurity atoms doped in the upper portion differs from the impurity atoms doped in the lower portion of silicon layer.

9. The wide bandgap semiconductor device of claim 8, wherein the impurity atoms doped in the upper portion of the silicon layer are one of donor impurity atoms and acceptor impurity atoms, and the impurity atoms doped in the lower portion of the silicon layer is oxygen atoms.

10. The wide bandgap semiconductor device of claim 1, wherein the wide bandgap semiconductor material is silicon carbide.

11. The wide bandgap semiconductor device of claim 1, further comprising a body contact region of the second conductivity type made of the wide bandgap semiconductor material, disposed at the top surface of and in the body region.

12. The wide bandgap semiconductor device of claim 1, wherein the source region surrounds the periphery of the body contact region in a ring shape.

13. The wide bandgap semiconductor device of claim 1, further comprising a source electrode contacting to the source region.

14. The wide bandgap semiconductor device of claim 11, further comprising a source electrode contacting both to the source region and the body contact region.

15. The wide bandgap semiconductor device of claim 11, further comprising a metallic interconnect contacting independently to the body contact region so as to apply different potential to the body region from the source region.

16. The wide bandgap semiconductor device of claim 1, further comprising a drain region contacting to drift layer.

17. The wide bandgap semiconductor device of claim 16, further comprising a drain electrode contacting to drain region.

18. A wide bandgap semiconductor device made of wide bandgap semiconductor material for controlling current flowing from source means to drain means by gate means, comprising:

drift means for transporting carriers by drift field between the source means and drain means;

body means disposed in the drift means for storing the carriers to be injected into the drift means;

source means disposed in the body means for providing the carriers so that the carriers can serve as the current flowing from the source means to the drain means;

channel means disposed at the top surface of the body means neighboring to the source means and further disposed at the top surface of the drift means for providing a current path between the source means and drain means; and

gate means directly contact with the top surface of the channel means so that an edge of gate means reaches to the source means, for controlling potential in the channel means, and simultaneously for achieving electrical isolation between the gate means and source means.

19. A method for manufacturing a wide bandgap semiconductor device, comprising:

forming a drift layer of a first conductivity type made of a wide bandgap semiconductor material on a base material made of the wide bandgap semiconductor material;

forming a body region of a second conductivity type opposite to the first conductivity type made of the wide bandgap semiconductor material at the top surface of and in the drift layer;

forming a source region of the first conductivity type made of the wide bandgap semiconductor material at the top surface of and in the body region;

forming a channel layer of the first conductivity type made of the wide bandgap semiconductor material at the top surface of and in the body region neighboring to the source region and further at the top surface of and in the drift layer;

depositing a semiconductor layer having a different bandgap energy from that of the wide bandgap semiconductor material directly on the channel layer; and

doping impurity atoms from the top surface of the semiconductor layer.

20. A method for manufacturing a wide bandgap semiconductor device, comprising:

forming a drift layer of a first conductivity type made of a wide bandgap semiconductor material on a base material made of the wide bandgap semiconductor material;

forming a body region of a second conductivity type opposite to the first conductivity type made of the wide bandgap semiconductor material at the top surface of and in the drift layer;

forming a channel layer of the first conductivity type made of the wide bandgap semiconductor material at the top surface of and in the body region neighboring to the source region and further at the top surface of and in the drift layer; and

depositing a semiconductor layer having a different bandgap energy from that of the wide bandgap semiconductor material directly on the channel layer;

delineating the semiconductor layer so as to form a window portion, exposing a portion of the body region, and to form a pattern of a gate electrode; and

doping the first conductivity type impurity atoms from the top surface of the semiconductor layer so as not dope the bottom portion of the semiconductor layer, and simultaneously doping the portion of the body region exposed in the window portion, thereby simultaneously forming the gate electrode directly contacting with the top surface of the channel layer and a source region of the first conductivity type at the top surface of and in the body region.