US-20260129895-A1 - NITRIDE SEMICONDUCTOR DEVICE

US20260129895A1US 20260129895 A1US20260129895 A1US 20260129895A1US-20260129895-A1

Abstract

A nitride semiconductor device includes a substrate a substrate, a semiconductor laminate disposed above the substrate and including a channel and a first and a second nitride semiconductor layers, a source electrode and a drain electrode each being in contact with the semiconductor laminate, a threshold adjustment layer located between the source electrode and the drain electrode, and a gate electrode disposed above the threshold adjustment layer. The second nitride semiconductor layer includes a first thin film portion located between the gate electrode and the source electrode and a first thick film portion that is located between the gate electrode and the drain electrode and is thicker than the first thin film portion. The threshold adjustment layer extends across the first thin film portion and the first thick film portion. An end of the threshold adjustment layer on the source electrode side is located on the first thin film portion.

Inventors

Naohiro Tsurumi
Hiroyuki Handa
Satoshi Tamura

Assignees

PANASONIC HOLDINGS CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251024
Priority Date: 20241105

Claims (20)

1 . A nitride semiconductor device comprising: a substrate; a semiconductor laminate disposed above the substrate and including a channel; a source electrode and a drain electrode each being in contact with the semiconductor laminate; a threshold adjustment layer located between the source electrode and the drain electrode; and a gate electrode disposed above the threshold adjustment layer, wherein the semiconductor laminate includes: a first nitride semiconductor layer; and a second nitride semiconductor layer disposed above the first nitride semiconductor layer, the second nitride semiconductor layer includes: a first thin film portion located between the gate electrode and the source electrode in a plan view of the substrate; and a first thick film portion that is located between the gate electrode and the drain electrode in a plan view of the substrate and is thicker than the first thin film portion, the threshold adjustment layer extends across the first thin film portion and the first thick film portion in a plan view of the substrate, and an end of the threshold adjustment layer on the source electrode side is located on the first thin film portion.
2 . The nitride semiconductor device according to claim 1 , wherein the source electrode is disposed on the first thin film portion, and the drain electrode is disposed on the first thick film portion.
3 . The nitride semiconductor device according to claim 1 , wherein the second nitride semiconductor layer further includes a second thick film portion located between the first thin film portion and the source electrode in a plan view of the substrate, the source electrode is disposed on the second thick film portion, and the drain electrode is disposed on the first thick film portion.
4 . The nitride semiconductor device according to claim 1 , wherein the second nitride semiconductor layer further includes a second thin film portion that is located between the first thick film portion and the drain electrode in a plan view of the substrate and is thinner than the first thick film portion, the source electrode is disposed on the first thin film portion, and the drain electrode is disposed on the second thin film portion.
5 . The nitride semiconductor device according to claim 1 , wherein the second nitride semiconductor layer further includes a first inclined portion located between the first thin film portion and the first thick film portion in a plan view of the substrate and having an inclined upper surface.
6 . The nitride semiconductor device according to claim 3 , wherein the second nitride semiconductor layer further includes: a first inclined portion located between the first thin film portion and the first thick film portion in a plan view of the substrate and having an inclined upper surface; and a second inclined portion located between the first thin film portion and the second thick film portion in a plan view of the substrate and having an inclined upper surface, and an inclination of the inclined upper surface of the first inclined portion is gentler than an inclination of the inclined upper surface of the second inclined portion.
7 . The nitride semiconductor device according to claim 1 , wherein the threshold adjustment layer is a p-type nitride semiconductor layer.
8 . The nitride semiconductor device according to claim 1 , wherein the nitride semiconductor device is divided into an active region and an inactive region in a plan view of the substrate, the source electrode and the drain electrode are disposed in the active region, the nitride semiconductor device further includes a drain pad disposed in the inactive region and electrically connected to the drain electrode, the first thick film portion, the first thin film portion, and the threshold adjustment layer are all further located between the source electrode and the drain pad in a plan view of the substrate, and the threshold adjustment layer extends across the first thin film portion and the first thick film portion between the source electrode and the drain pad in a plan view of the substrate.
9 . A nitride semiconductor device comprising: a substrate; a semiconductor laminate disposed above the substrate and including a channel; a first electrode and a second electrode each being in contact with the semiconductor laminate; a first threshold adjustment layer located between the first electrode and the second electrode; a second threshold adjustment layer located between the first threshold adjustment layer and the second electrode; a first gate electrode disposed above the first threshold adjustment layer; and a second gate electrode disposed above the second threshold adjustment layer, wherein the semiconductor laminate includes: a first nitride semiconductor layer; and a second nitride semiconductor layer disposed above the first nitride semiconductor layer, the second nitride semiconductor layer includes: a first thin film portion located between the first gate electrode and the first electrode in a plan view of the substrate; a second thin film portion located between the second gate electrode and the second electrode in a plan view of the substrate; and a first thick film portion that is located between the first thin film portion and the second thin film portion in a plan view of the substrate and is thicker than both of the first thin film portion and the second thin film portion, the first threshold adjustment layer extends across the first thin film portion and the first thick film portion in a plan view of the substrate, the second threshold adjustment layer extends across the second thin film portion and the first thick film portion in a plan view of the substrate, an end of the first threshold adjustment layer on the first electrode side is located on the first thin film portion, and an end of the second threshold adjustment layer on the second electrode side is located on the second thin film portion.
10 . The nitride semiconductor device according to claim 9 , wherein the first electrode is disposed on the first thin film portion, and the second electrode is disposed on the second thin film portion.
11 . The nitride semiconductor device according to claim 9 , wherein the second nitride semiconductor layer further includes: a second thick film portion located between the first thin film portion and the first electrode in a plan view of the substrate; and a third thick film portion located between the second thin film portion and the second electrode in a plan view of the substrate, the first electrode is disposed on the second thick film portion, and the second electrode is disposed on the third thick film portion.
12 . The nitride semiconductor device according to claim 9 , wherein the second nitride semiconductor layer further includes: a first inclined portion located between the first thin film portion and the first thick film portion in a plan view of the substrate and having an inclined upper surface; and a third inclined portion located between the second thin film portion and the first thick film portion in a plan view of the substrate and having an inclined upper surface.
13 . The nitride semiconductor device according to claim 9 , further comprising: an n-type third nitride semiconductor layer disposed above the substrate; a p-type fourth nitride semiconductor layer disposed above the third nitride semiconductor layer; and a drain electrode disposed below the substrate, wherein the semiconductor laminate is disposed to cover an inner surface of an opening penetrating the fourth nitride semiconductor layer and reaching the third nitride semiconductor layer and an upper side of the fourth nitride semiconductor layer, the opening is located between the first electrode and the second electrode in a plan view of the substrate, the first electrode and the second electrode are each a source electrode and are electrically connected to each other, the first gate electrode and the first threshold adjustment layer are located between a bottom surface of the opening and the first electrode in a plan view of the substrate, and the second gate electrode and the second threshold adjustment layer are located between a bottom surface of the opening and the second electrode in a plan view of the substrate.
14 . The nitride semiconductor device according to claim 13 , further comprising: a p-type fifth nitride semiconductor layer disposed above the semiconductor laminate at a location overlapping the bottom surface of the opening in a plan view of the substrate; and a third electrode disposed above the fifth nitride semiconductor layer and set to the same potential as the source electrode.
15 . The nitride semiconductor device according to claim 9 , wherein the first threshold adjustment layer and the second threshold adjustment layer are each a p-type nitride semiconductor layer.
16 . The nitride semiconductor device according to claim 9 , wherein the nitride semiconductor device is divided into an active region and an inactive region in a plan view of the substrate; the first electrode and the second electrode are disposed in the active region; the nitride semiconductor device further includes: a first pad disposed in the inactive region and electrically connected to the first electrode; and a second pad disposed in the inactive region and electrically connected to the second electrode, all of the first thick film portion, the first thin film portion, and the first threshold adjustment layer are further located between the first electrode and the first pad in a plan view of the substrate, the first threshold adjustment layer extends across the first thin film portion and the first thick film portion between the first electrode and the first pad in a plan view of the substrate, all of the first thick film portion, the second thin film portion, and the second threshold adjustment layer are further located between the second electrode and the second pad in a plan view of the substrate, and the second threshold adjustment layer extends across the second thin film portion and the first thick film portion between the second electrode and the second pad in a plan view of the substrate.
17 . A nitride semiconductor device comprising: a substrate; an n-type third nitride semiconductor layer disposed above the substrate; a p-type fourth nitride semiconductor layer disposed above the third nitride semiconductor layer; a semiconductor laminate disposed to cover an inner surface of an opening penetrating the fourth nitride semiconductor layer and reaching the third nitride semiconductor layer and an upper side of the fourth nitride semiconductor layer, and including a channel; a first electrode and a second electrode each being in contact with the semiconductor laminate; a threshold adjustment layer located between the first electrode and the second electrode; a gate electrode disposed above the threshold adjustment layer; and a drain electrode disposed below the substrate, wherein the opening is located between the first electrode and the second electrode in a plan view of the substrate, the first electrode and the second electrode are each a source electrode and are electrically connected to each other, the semiconductor laminate includes: a first nitride semiconductor layer; and a second nitride semiconductor layer disposed above the first nitride semiconductor layer, the second nitride semiconductor layer includes: a first thin film portion located between the gate electrode and the first electrode in a plan view of the substrate; a second thin film portion located between the gate electrode and the second electrode in a plan view of the substrate; and a first thick film portion that is located between the first thin film portion and the second thin film portion in a plan view of the substrate and is thicker than both of the first thin film portion and the second thin film portion, the threshold adjustment layer extends across the first thin film portion and the first thick film portion and extends across the second thin film portion and the first thick film portion in a plan view of the substrate, an end of the threshold adjustment layer on the first electrode side is located on the first thin film portion, and an end of the threshold adjustment layer on the second electrode side is located on the second thin film portion.
18 . The nitride semiconductor device according to claim 17 , wherein the first electrode is disposed on the first thin film portion, and the second electrode is disposed on the second thin film portion.
19 . The nitride semiconductor device according to claim 17 , wherein the second nitride semiconductor layer further includes: a second thick film portion located between the first thin film portion and the first electrode in a plan view of the substrate; and a third thick film portion located between the second thin film portion and the second electrode in a plan view of the substrate, the first electrode is disposed on the second thick film portion, and the second electrode is disposed on the third thick film portion.
20 . The nitride semiconductor device according to claim 17 , wherein the second nitride semiconductor layer further includes: a first inclined portion located between the first thin film portion and the first thick film portion in a plan view of the substrate and having an inclined upper surface; and a third inclined portion located between the second thin film portion and the first thick film portion in a plan view of the substrate and having an inclined upper surface.

Description

BACKGROUND 1. Technical Field The present disclosure relates to a nitride semiconductor device. 2. Description of the Related Art Patent Literature (PTL) 1 discloses a nitride semiconductor device including a two-dimensional electron gas (2DEG) as a channel. In the nitride semiconductor device disclosed in PTL 1, a p-type nitride semiconductor layer is provided so as to cover a side surface of the gate recess on the source electrode side, and a gate electrode is provided on an upper surface of the p-type nitride semiconductor layer. As a result, it is described that the parasitic capacitance generated between the gate electrode and the 2DEG can be reduced. PTL 1: Japanese Patent No. 6742301 SUMMARY The nitride semiconductor device according to one aspect of the present disclosure includes: a substrate; a semiconductor laminate disposed above the substrate and including a channel; a source electrode and a drain electrode each being in contact with the semiconductor laminate; a threshold adjustment layer located between the source electrode and the drain electrode; and a gate electrode disposed above the threshold adjustment layer. The semiconductor laminate includes a first nitride semiconductor layer and a second nitride semiconductor layer disposed above the first nitride semiconductor layer, The second nitride semiconductor layer includes a first thin film portion located between the gate electrode and the source electrode in a plan view of the substrate and a first thick film portion that is located between the gate electrode and the drain electrode in a plan view of the substrate and is thicker than the first thin film portion. The threshold adjustment layer extends across the first thin film portion and the first thick film portion in a plan view of the substrate. An end of the threshold adjustment layer on the source electrode side is located on the first thin film portion. The nitride semiconductor device according to another aspect of the present disclosure includes: a substrate; a semiconductor laminate disposed above the substrate and including a channel; a first electrode and a second electrode each being in contact with the semiconductor laminate; a first threshold adjustment layer located between the first electrode and the second electrode; a second threshold adjustment layer located between the first threshold adjustment layer and the second electrode; a first gate electrode disposed above the first threshold adjustment layer; and a second gate electrode disposed above the second threshold adjustment layer. The semiconductor laminate includes a first nitride semiconductor layer and a second nitride semiconductor layer disposed above the first nitride semiconductor layer. The second nitride semiconductor layer includes a first thin film portion located between the first gate electrode and the first electrode in a plan view of the substrate, a second thin film portion located between the second gate electrode and the second electrode in a plan view of the substrate, and a first thick film portion that is located between the first thin film portion and the second thin film portion in a plan view of the substrate and is thicker than both of the first thin film portion and the second thin film portion. The first threshold adjustment layer extends across the first thin film portion and the first thick film portion in a plan view of the substrate. The second threshold adjustment layer extends across the second thin film portion and the first thick film portion in a plan view of the substrate. An end of the first threshold adjustment layer on the first electrode side is located on the first thin film portion. An end of the second threshold adjustment layer on the second electrode side is located on the second thin film portion. A nitride semiconductor device according to another aspect of the present disclosure includes: a substrate; an n-type third nitride semiconductor layer disposed above the substrate; a p-type fourth nitride semiconductor layer disposed above the third nitride semiconductor layer; a semiconductor laminate disposed to cover an inner surface of an opening penetrating the fourth nitride semiconductor layer and reaching the third nitride semiconductor layer and an upper side of the fourth nitride semiconductor layer, and including a channel; a first electrode and a second electrode each being in contact with the semiconductor laminate; a threshold adjustment layer located between the first electrode and the second electrode; a gate electrode disposed above the threshold adjustment layer; and a drain electrode disposed below the substrate. The opening is located between the first electrode and the second electrode in a plan view of the substrate. The first electrode and the second electrode are each a source electrode and are electrically connected to each other. The semiconductor laminate includes a first nitride semiconductor layer and a second nitride semiconductor layer provided