Gate structures to enable lower subthreshold slope in gallium nitride-based transistors

Patent metadata

Field	Value
Publication number	US-12439627-B2
Application number	US-202117557827-A
Country	US
Kind code	B2
Filing date	Dec 21, 2021
Priority date	Dec 21, 2021
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

In one embodiment, a transistor includes a substrate, a buffer layer on the substrate a channel layer on the buffer layer, and one or more polarization layers on the channel layer. The one or more polarization layers include a group III-N material comprising a first group III constituent and a second group III constituent. The transistor further includes a plurality of p-type doped layers on the one or more polarization layers. Each of the plurality of p-type doped layers includes a first p-type dopant and the III-N material, wherein each successive layer of the first p-type doped layers has a lower proportion of the first group III constituent to the second group III constituent relative to a layer below it. The transistor also includes a p-type doped layer on the plurality of p-type doped layers comprising a second p-type dopant and a group III-N material.

First claim

The invention claimed is:

1. An apparatus comprising:
a substrate;
a buffer layer on the substrate, the buffer layer comprising a first group III-nitride (III-N) material;
a channel layer on the buffer layer, the channel layer comprising a second III-N material;
one or more polarization layers on the channel layer, the one or more polarization layers comprising a third III-N material comprising a first group III constituent and a second group III constituent;
a plurality of p-type doped layers on the one or more polarization layers, each of the plurality of p-type doped layers comprising a first p-type dopant and the third III-N material, wherein each successive layer of the first p-type doped layers has a lower proportion of the first group III constituent to the second group III constituent relative to a layer below it;
a p-type doped layer on the plurality of p-type doped layers comprising a second p-type dopant and a fourth III-N material; and
a source region adjacent one end of the channel layer; and
a drain region adjacent another end of the channel layer.

2. The apparatus of claim 1 , wherein the one or more polarization layers comprise a plurality of polarization layers, each successive layer of the polarization layers having a lower proportion of the first group III constituent to the second group III constituent than a layer below it.

3. The apparatus of claim 1 , wherein:
the one or more polarization layers comprise:
a first polarization layer on the channel layer, wherein the first group III constituent of the first polarization layer is in a first proportion to the second group III constituent of the first polarization layer; and
a second polarization layer on the first polarization layer, wherein the first group III constituent of the second polarization layer is in a second proportion to the second group III constituent of the second polarization layer;

the plurality of p-type doped layers comprise:
a first p-type doped layer on the second polarization layer, wherein the first group III constituent of the first p-type doped layer is in a third proportion to the second group III constituent of the first p-type doped layer;
a second p-type doped layer on the first p-type doped layer, wherein the first group III constituent of the second p-type doped layer is in a fourth proportion to the second group III constituent of the second p-type doped layer;

the fourth proportion is lower than the third proportion;
the third proportion is lower than the second proportion; and
the second proportion is lower than the first proportion.

4. The apparatus of claim 1 , wherein the first III-N material comprises aluminum, gallium, and nitrogen.

5. The apparatus of claim 1 , wherein the second III-N material comprises gallium, and nitrogen.

6. The apparatus of claim 1 , wherein the third III-N material comprises aluminum, gallium, and nitrogen or indium, aluminum, and nitrogen.

7. The apparatus of claim 1 , wherein the fourth III-N material comprises gallium and nitrogen or aluminum and nitrogen.

8. The apparatus of claim 1 , wherein the first p-type dopant comprises one or more of magnesium and beryllium and the second p-type dopant comprises one or more of magnesium and beryllium.

9. The apparatus of claim 1 , wherein the source region and the drain region each comprise a fifth III-N material comprising indium, gallium, and nitrogen.

10. An apparatus comprising:
a substrate;
a buffer layer on the substrate, the buffer layer comprising a first group III-nitride (III-N) material;
a channel layer on the buffer layer, the channel layer comprising a second III-N material;
one or more polarization layers on the channel layer, the one or more polarization layers comprising a third III-N material comprising a first group III constituent and a second group III constituent;
a first p-type doped layer on the one or more polarization layers, the first p-type doped layer comprising a first p-type dopant and the third III-N material, wherein a proportion of the first group III constituent to the second group III constituent is a gradient;
a second p-type doped layer on the first p-type doped layer, the second p-type doped layer comprising a second p-type dopant and a fourth III-N material; and
a source region adjacent one end of the channel layer; and
a drain region adjacent another end of the channel layer.

11. The apparatus of claim 10 , wherein the one or more polarization layers comprise a plurality of polarization layers, each successive layer of the polarization layers having a lower proportion of the first group III constituent to the second group III constituent than a layer below it.

12. The apparatus of claim 10 , wherein:
the one or more polarization layers comprise:
a first polarization layer on the channel layer, wherein the first group III constituent of the first polarization layer is in a first proportion to the second group III constituent of the first polarization layer; and
a second polarization layer on the first polarization layer, wherein the first group III constituent of the second polarization layer is in a second proportion to the second group III constituent of the second polarization layer;

the first p-type layer is on the second polarization layer, and the proportion of the first group III constituent to the second group III constituent in the first p-type doped layer is at a third proportion adjacent the second polarization layer and at a fourth proportion adjacent the second p-type doped layer;
the fourth proportion is lower than the third proportion
the third proportion is lower than the second proportion; and
the second proportion is lower than the first proportion.

13. The apparatus of claim 10 , wherein the first III-N material comprises aluminum, gallium, and nitrogen.

14. The apparatus of claim 10 , wherein the second III-N material comprises gallium, and nitrogen.

15. The apparatus of claim 10 , wherein the third III-N material comprises aluminum, gallium, and nitrogen or indium, aluminum, and nitrogen.

16. The apparatus of claim 10 , wherein the fourth III-N material comprises gallium and nitrogen or aluminum and nitrogen.

17. The apparatus of claim 10 , wherein the first p-type dopant comprises one or more of magnesium and beryllium and the second p-type dopant comprises one or more of magnesium and beryllium.

18. The apparatus of claim 10 , wherein the source region and the drain region each comprise a fifth III-N material comprising indium, gallium, and nitrogen.

19. An apparatus comprising:
a substrate;
a buffer layer on the substrate, the buffer layer comprising a first group III-nitride (III-N) material;
a channel layer on the buffer layer, the channel layer comprising a second III-N material;
one or more polarization layers on the channel layer, the one or more polarization layers comprising a third III-N material comprising a first group III constituent and a second group III constituent;
one or more first p-type doped layers on the one or more polarization layers comprising a first p-type dopant and the third III-N material;
a second p-type doped layer on the one or more first p-type doped layers, the second p-type doped layer comprising a second p-type dopant and a fourth III-N material;
wherein the one or more first p-type doped layers comprise a first proportion of the first group III constituent to the second group III constituent in a region adjacent to the one or more polarization layers and a second proportion of the first group III constituent t

Assignees

• Intel Corp

Inventors

• Bajaj Sanyam
• Beumer Michael S
• Ehlert Robert
• Mcnerney Gregory P
• Minutillo Nicholas
• Qin Xiaoye
• Rode Johann C
• Tanaka Atsunori
• Vishwanath Suresh
• Wallace Patrick M

Classifications

• H10D64/411

  for FETs · CPC title

• H10D62/8503

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

• H10D62/824

  comprising only Group III-V materials heterojunctions, e.g. GaN/AlGaN heterojunctions · CPC title

• H10D30/015

  of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT · CPC title

• H10D30/475

  having wider bandgap layer formed on top of lower bandgap active layer, e.g. undoped barrier HEMTs such as i-AlGaN/GaN HEMTs · CPC title