# US 10,770,556 B2 · Fluorinated graphene passivated AlGaN/GaN-based HEMT device and manufacturing method

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- Number: US 10,770,556 B2
- Document ID: US10770556B2
- Status: Granted
- Kind: B2
- Application number: 15/772,033
- Filed: 2016-03-04
- Published: 2019-01-31
- Granted: 2020-09-08
- Earliest claimed: 2015-11-12
- Assignees: Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science
- Applicants: Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences
- Inventors: Xinhong Cheng; Lingyan Shen; Zhongjian Wang; Duo Cao; Li Zheng; Qian Wang; Dongliang Zhang; Jingjie Li; Yuehui Yu
- Web page: https://patentgrep.com/patent/US10770556B2

## CPC

- H10D 64/118: {Electrodes comprising insulating layers having particular dielectric or electrostatic properties, e.g. having static charges}
- H10D 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT}
- H10D 30/475: {having wider bandgap layer formed on top of lower bandgap active layer, e.g. undoped barrier HEMTs such as i-AlGaN/GaN HEMTs}
- H10D 30/4755: {having wide bandgap charge-carrier supplying layers, e.g. modulation doped HEMTs such as n-AlGaAs/GaAs HEMTs}
- H10D 62/824: comprising only Group III-V materials heterojunctions, e.g. GaN/AlGaN heterojunctions
- H10D 64/01: Manufacture or treatment
- H10D 64/685: {being perpendicular to the channel plane}
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 64/691: {comprising metallic compounds, e.g. metal oxides or metal silicates (insulators comprising nitrogen H10D64/693)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

An AlGaN/GaN HEMT based on fluorinated graphene passivation and a manufacturing method thereof. Monolayer graphene (108) is transferred to an AlGaN (104) surface, is treated by using fluoride ions and then is insulated to thereby replace a conventional nitride passivation layer. Then, a high-k material (109) is grown on the graphene (108), and the high-k material (109) and the graphene (108) are jointly used as a gate dielectric for preparing an AlGaN/GaN metal-insulator-semiconductor (MIS) HEMT. Compared with the traditional passivation structure, the graphene (108) has the advantages of small physical thickness (sub-nanometer scale) and low additional threshold voltage. The structure and the method are simple, the effect is remarkable and the application prospect in technical fields of microelectronics and solid-state electronics is wide.

## Claims

### Claim 1

An AlGaN/GaN HEMT based on fluorinated graphene passivation, characterized in that the HEMT comprises:
a substrate;
a GaN layer located above the substrate;
an AlGaN layer bonded to the GaN layer, a two-dimensional electron gas surface formed by an interface between the AlGaN layer and the GaN layer;
a source and a drain formed at two ends of the AlGaN layer;
an insulated graphene passivation layer bonded to a surface of the AlGaN layer, wherein the insulated graphene passivation layer is fluorinated;
a gate dielectric layer bonded to a surface of the insulated graphene passivation layer; and
a gate metal layer bonded to a surface of the gate dielectric layer.

### Claim 2 (depends on 1)

A method for manufacturing AlGaN/GaN HEMT based on fluorinated graphene passivation of claim 1, characterized in that the method comprises the following steps:
1) providing a substrate and sequentially forming a GaN layer and an AlGaN layer on a surface of the substrate, an interface between the GaN layer and the AlGaN layer forming a two-dimensional electron gas surface;
2) forming a source ohmic contact and a drain ohmic contact on the AlGaN layer;
3) covering a surface of the AlGaN layer with graphene and performing fluorination treatment to the graphene to form an insulated graphene passivation layer; and
4) forming a gate dielectric layer on a surface of the insulated graphene passivation layer and forming a gate metal layer on a surface of the gate dielectric layer.

### Claim 3 (depends on 1, 2)

The manufacturing method for the AlGaN/GaN HEMT based on fluorinated graphene passivation of claim 1 according to claim 2, characterized in that the method further comprises the following steps:
5) performing mesa isolation to a device region;
6) depositing an isolating layer on a surface of the device;
7) etching windows corresponding to the source ohmic contact, the drain ohmic contact and the gate metal layer in the isolating layer; and
8) manufacturing metal extraction electrodes based on each window.

### Claim 4 (depends on 1, 2)

The manufacturing method for the AlGaN/GaN HEMT based on fluorinated graphene passivation of claim 1 according to claim 2, characterized in that method for covering the surface of the AlGaN layer with graphene in step 3) is selected from: a. growing graphene on a Cu substrate and then transferring the graphene grown on the Cu substrate to the surface of the AlGaN layer; or b. directly growing graphene on the surface of the AlGaN layer.

### Claim 5 (depends on 1, 2)

The manufacturing method for the AlGaN/GaN HEMT based on fluorinated graphene passivation of claim 1 according to claim 2, characterized in that step 3) of performing fluorination treatment to the graphene comprises the following step: treating the graphene by using SF6 plasmas, treatment time being 60-120 s.

### Claim 6 (depends on 1, 2)

The manufacturing method for the AlGaN/GaN HEMT based on fluorinated graphene passivation of claim 1 according to claim 2, characterized in that step 1) further comprises a step of forming a buffer layer between the substrate and the GaN layer.

### Claim 7 (depends on 1, 2)

The manufacturing method for the AlGaN/GaN HEMT based on fluorinated graphene passivation of claim 1 according to claim 2, characterized in that the gate dielectric layer is a high-k gate dielectric layer.

### Claim 8 (depends on 1)

The AlGaN/GaN HEMT based on fluorinated graphene passivation according to claim 1, characterized in that the substrate comprises a silicon substrate in a (111) crystal orientation.

### Claim 9 (depends on 1)

The AlGaN/GaN HEMT based on fluorinated graphene passivation according to claim 1, characterized in that the gate dielectric layer is a high-k dielectric layer.

### Claim 10 (depends on 1)

The AlGaN/GaN HEMT based on fluorinated graphene passivation according to claim 1, characterized in that a buffer layer is provided between the substrate and the GaN layer.

### Claim 11 (depends on 10)

The AlGaN/GaN HEMT based on fluorinated graphene passivation according to claim 10, characterized in that a thickness range of the buffer layer is 2-10 μm.