Nitride semiconductor device and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-9859413-B2
Application number	US-201715399443-A
Country	US
Kind code	B2
Filing date	Jan 5, 2017
Priority date	Jul 11, 2014
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

A nitride semiconductor device including a substrate, a channel layer, a carbon-poor barrier layer having a recess, a carbon-rich barrier layer disposed over the recess and the carbon-poor barrier layer, and a gate electrode above the recess, wherein the carbon-poor and carbon-rich barrier layers have bandgaps larger than that of the channel layer, the upper surface of the carbon-rich barrier layer includes a first main surface including a source electrode and a drain electrode, and a bottom surface of a depression disposed along the recess, and side surfaces of the depression connecting the first main surface to the bottom surface of the depression, and among edges of the depression of the carbon-rich barrier layer which are boundaries between the first main surface and the side surfaces of the depression, the edge of the depression of the carbon-rich barrier layer closest to the drain electrode is covered with the gate electrode.

First claim

What is claimed is:

1. A nitride semiconductor device, comprising:
a substrate;
a channel layer disposed on the substrate;
a carbon-poor barrier layer disposed on the channel layer and having a recess;
a carbon-rich barrier layer disposed over the recess and the carbon-poor barrier layer, and having a carbon content higher than a carbon content of the carbon-poor barrier layer;
a gate electrode disposed on the recess; and
a source electrode and a drain electrode disposed on opposing sides of the gate electrode and spaced from the gate electrode,
wherein the carbon-poor barrier layer and the carbon-rich barrier layer contain carbon,
the carbon-rich barrier layer has a carbon content higher than a carbon content of the carbon-poor barrier layer,
the carbon-poor barrier layer and the carbon-rich barrier layer have bandgaps larger than a bandgap of the channel layer,
an upper surface of the carbon-rich barrier layer includes a first main surface on which the source electrode and the drain electrode are disposed, a bottom surface of a depression disposed along the recess, and side surfaces of the depression connecting the first main surface to the bottom surface of depression, and
among edges of the depression of the carbon-rich barrier layer which are boundaries between the first main surface and the side surfaces of the depression, an edge of the depression of the carbon-rich barrier layer closest to the drain electrode is covered with the gate electrode.

2. The nitride semiconductor device according to claim 1 ,
wherein the upper surface of the carbon-poor barrier layer includes a second main surface facing the first main surface, and side surfaces of the recess, and
in a cross-sectional view of the gate electrode and the carbon-rich barrier layer,
among edges of the recess which are boundaries between the second main surface and the side surfaces of the recess, an edge of the drain electrode closest to the recess is located immediately under an edge of the gate electrode close to the drain.

3. The nitride semiconductor device according to claim 1 ,
wherein the upper surface of the carbon-poor barrier layer includes a second main surface facing the first main surface, and side surfaces of the recess, and
in a cross-sectional view of the gate electrode and the carbon-rich barrier layer,
among the edges of the recess which are boundaries between the second main surface and the side surfaces of the recess, the edge of the recess closest to the drain electrode is located in a position opposite to the drain electrode with respect to a position immediately under the edge of the gate electrode close to the drain.

4. The nitride semiconductor device according to claim 1 ,
wherein the recess has a recess opening having a length longer than a length of a recess bottom in an aligning direction of the source electrode and the drain electrode.

5. The nitride semiconductor device according to claim 1 ,
wherein in the carbon-rich barrier layer, a carbon concentration of a region including the bottom surface of the depression is higher than a carbon concentration of a region including the side surfaces of the depression.

6. The nitride semiconductor device according to claim 1 ,
wherein the recess has a penetrating recess structure in which the recess penetrates from an upper surface through a bottom surface of the carbon-poor barrier layer,
the carbon-rich barrier layer includes
a barrier portion disposed above a first extending surface extending from an interface between the carbon-poor barrier layer and the channel layer in a non-recess portion, and
a channel portion disposed below the first extending surface, and
a carbon concentration of the channel portion is higher than a carbon concentration of the barrier portion.

7. A nitride semiconductor device, comprising:
a substrate;
a channel layer disposed on the substrate;
a carbon-poor barrier layer disposed on the channel layer and having a recess;
a carbon-rich barrier layer disposed over the recess and the carbon-poor barrier layer, and having a carbon content higher than a carbon content of the carbon-poor barrier layer;
a gate electrode disposed on the recess; and
a source electrode and a drain electrode disposed spaced from the gate electrode with the gate electrode being interposed between the source electrode and the drain electrode,
wherein the carbon-rich barrier layer has a depression having an opening having a length longer than a length of a bottom of the depression in an aligning direction of the source electrode and the drain electrode,
the carbon-poor barrier layer and the carbon-rich barrier layer both contain carbon,
the carbon-rich barrier layer has a carbon content higher than a carbon content of the carbon-poor barrier layer,
the carbon-poor barrier layer and the carbon-rich barrier layer have bandgaps larger than a bandgap of the channel layer,
an upper surface of the carbon-rich barrier layer includes a first main surface on which the source electrode and the drain electrode are disposed, a bottom surface of the depression disposed along the recess, and side surfaces of the depression connecting the first main surface to the bottom surface of depression, and
among edges of the bottom surface of the depression which are boundaries between the bottom surface of the depression and the side surfaces of the depression, an edge of the bottom surface of the depression closest to the drain electrode is covered with the gate electrode.

8. The nitride semiconductor device according to claim 7 ,
wherein the recess has a penetrating recess structure in which the recess penetrates from an upper surface to a bottom surface of the carbon-poor barrier layer,
the upper surface of the carbon-poor barrier layer includes a second main surface facing the first main surface, and side surfaces of the recess connecting the second main surface to the bottom surface of the recess, and
in a cross-sectional view of the gate electrode and the carbon-poor barrier layer,
among edges of the bottom surface of the recess which are boundaries between the side surfaces of the recess and the bottom surface of the recess, an edge of the bottom surface of the recess closest to the drain electrode is located in a position opposite to the drain electrode with respect to a position immediately under an edge of the gate electrode close to the drain.

9. The nitride semiconductor device according to claim 7 ,
wherein among edges of the depression of the carbon-rich barrier layer which are boundaries between the first main surface and the side surfaces of the depression, an edge of the depression of the carbon-rich barrier layer closest to the drain electrode is covered with the gate electrode.

10. The nitride semiconductor device according to claim 7 ,
wherein an upper surface of the carbon-poor barrier layer includes a second main surface facing the first main surface, and side surfaces of the recess,
in a cross-sectional view of the gate electrode and the carbon-rich barrier layer,
among edges of the recess which are boundaries between the second main surface and the side surfaces of the recess, an edge of the recess closest to the drain electrode is located at a position opposite to the drain electrode with respect to a position immediately under an edge of the gate electrode close to the drain.

11. The nitride semiconductor device according to claim 1 ,
in a cross-sectional view of the gate electrode, the carbon-poor barrier layer, and the carbon-rich barrier layer,
a total thickness of the carbon-poor barrier layer and the carbon-rich barrier layer located immediately under the edge of the gate electrode close to

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Okita Hideyuki
• Hikita Masahiro
• Matsuo Hisayoshi
• Uemoto Yasuhiro

Classifications

• H10D62/8503

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

• H01L29/66462

  Electricity · mapped topic

• H01L29/42356

  Electricity · mapped topic

• H01L29/7787 Primary

  Electricity · mapped topic

• H01L29/0642

  Electricity · mapped topic