Semiconductor device with varying thickness of insulating film between electrode and gate electrode and method of manufacturing semiconductor device

Patent metadata

Field	Value
Publication number	US-9559183-B2
Application number	US-201414271277-A
Country	US
Kind code	B2
Filing date	May 6, 2014
Priority date	Jun 3, 2013
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

To provide a semiconductor device having improved characteristics. The semiconductor device has a substrate and thereon a buffer layer, a channel layer, a barrier layer, a trench penetrating therethrough and reaching the inside of the channel layer, a gate electrode placed in the trench via a gate insulating film, and drain and source electrodes on the barrier layer on both sides of the gate electrode. The gate insulating film has a first portion made of a first insulating film and extending from the end portion of the trench to the side of the drain electrode and a second portion made of first and second insulating films and placed on the side of the drain electrode relative to the first portion. The on resistance can be reduced by decreasing the thickness of the first portion at the end portion of the trench on the side of the drain electrode.

First claim

What is claimed is:

1. A semiconductor device, comprising:
a first nitride semiconductor layer formed over a substrate;
a second nitride semiconductor layer formed over the first nitride semiconductor layer and having a band gap wider than that of the first nitride semiconductor layer;
a trench penetrating through the second nitride semiconductor layer and reaching an inside of the first nitride semiconductor layer;
a gate electrode placed in the trench above a gate insulating film;
a first electrode and a second electrode formed over the second nitride semiconductor layer on both sides of the gate electrode, respectively,
wherein the gate insulating film includes:
a first portion extending from an end portion of the trench toward the first electrode, and located on a side of the end portion of the trench;
a second portion located between the first electrode and the first portion, having a film thickness greater than that of the first portion, and including a first side surface facing the first electrode; and
a third portion located between the first electrode and the second portion, having a film thickness less than the film thickness of the second portion, and including a second side surface facing the first electrode; and

an insulating layer disposed on the first side surface, the second side surface, and an upper surface of the third portion, the insulating layer extending from the first electrode to reach to the first side surface of the second portion,
wherein the first side surface and the second side surface each contact the upper surface of the third portion.

2. The semiconductor device according to claim 1 , wherein the first portion includes a second film placed over the second nitride semiconductor layer, and
wherein the second portion includes a first film and the second film, the second film being placed over the second nitride semiconductor layer and the first film.

3. The semiconductor device according to claim 2 , wherein the second film comprises a film containing aluminum oxide.

4. The semiconductor device according to claim 3 , wherein the first film comprises a film containing silicon nitride.

5. The semiconductor device according to claim 1 , wherein the trench comprises a tapered side wall.

6. The semiconductor device according to claim 5 , wherein an angle between a side surface of the trench and an extension of a bottom surface of the trench is 90° or less.

7. The semiconductor device according to claim 6 , wherein the angle is 70° or greater but not greater than 90°.

8. The semiconductor device according to claim 2 , wherein a distance between the end portion of the trench and the first film is equal to or greater than a thickness of the second film.

9. The semiconductor device according to claim 8 , wherein the distance between the end portion of the trench and the first film is 0.2 μm or greater.

10. The semiconductor device according to claim 2 , wherein a distance between the end portion of the trench and the first film is 5 nm or greater but not greater than 0.1 μm.

11. The semiconductor device according to claim 1 , wherein the insulating layer is disposed on an upper surface of the second portion of the gate insulating film.

12. The semiconductor device according to claim 1 , wherein the second portion includes a first film and a second film, the second film being placed over the second nitride semiconductor layer and the first film, and
wherein the insulating layer is disposed on an upper surface of the second portion of the gate insulating film.

Assignees

• Renesas Electronics Corp

Inventors

• Inoue Takashi
• Nakayama Tatsuo
• Okamoto Yasuhiro
• Kawaguchi Hiroshi
• Takewaki Toshiyuki
• Nagura Nobuhiro
• Nagai Takayuki
• Miura Yoshinao
• Miyamoto Hironobu

Classifications

• H10P50/691

  for Group V materials or Group III-V materials · CPC title

• H10P14/3416

  Nitrides · CPC title

• H10P14/24

  using chemical vapour deposition [CVD] · CPC title

• H10D64/01358 Primary

  the insulator being formed after the semiconductor body, the semiconductor being a Group III-V material · CPC title

• H10D62/8503

  Nitride Group III-V materials, e.g. AlN or GaN · CPC title