# US 10,312,378 B2 · Lateral gallium nitride JFET with controlled doping profile

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- Number: US 10,312,378 B2
- Document ID: US10312378B2
- Status: Granted
- Kind: B2
- Application number: 15/882,955
- Filed: 2018-01-29
- Published: 2018-08-02
- Granted: 2019-06-04
- Earliest claimed: 2017-01-30
- Assignees: QROMIS, Inc.
- Applicants: QROMIS, Inc.
- Inventors: Vladimir Odnoblyudov; Ozgur Aktas
- Web page: https://patentgrep.com/patent/US10312378B2

## CPC

- H10D 30/83: FETs having PN junction gate electrodes
- H10D 30/01: Manufacture or treatment
- H10D 30/051: {of FETs having PN junction gates (H10D30/015 takes precedence)}
- H10D 62/105: {by having particular doping profiles, shapes or arrangements of PN junctions; by having supplementary regions, e.g. junction termination extension [JTE] (IGFETs having LDD or drain extension regions H10D30/601)}
- H10D 62/115: {Dielectric isolations, e.g. air gaps}
- H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)}
- H10D 62/328: {having PN junction gates}
- H10D 62/343: {Gate regions of field-effect devices having PN junction gates}
- H10D 62/60: Impurity distributions or concentrations
- H10D 62/81: of structures exhibiting quantum-confinement effects, e.g. single quantum wells; of structures having periodic or quasi-periodic potential variation
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 64/258: {characterised by the relative positions of the source or drain electrodes with respect to the gate electrode}
- H10D 64/311: {Gate electrodes for field-effect devices}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A lateral junction field-effect transistor includes a substrate of a first conductivity type having a dopant concentration; a first semiconductor layer of the first conductivity type having a first dopant concentration lower than the dopant concentration and disposed on the substrate; a second semiconductor layer of a second conductivity type having a second dopant concentration, the second conductivity type being different from the first conductivity type, the second semiconductor layer disposed on the first semiconductor layer; a third semiconductor layer of the first conductivity type having a third dopant concentration, the third semiconductor layer disposed on the second semiconductor layer; a fourth semiconductor layer of the first conductivity type having a fourth dopant concentration lower than the dopant concentration, the fourth semiconductor layer disposed on the third semiconductor layer; a source region and a drain region disposed in the second semiconductor layer and on opposite sides of the third semiconductor layer.

## Claims

### Claim 1

A lateral junction field-effect transistor comprising:
a substrate of a first conductivity type having a dopant concentration;
a first semiconductor layer of the first conductivity type having a first dopant concentration lower than the dopant concentration of the substrate and disposed on the substrate;
a second semiconductor layer of a second conductivity type having a second dopant concentration, the second conductivity type being different from the first conductivity type, the second semiconductor layer disposed on the first semiconductor layer;
a third semiconductor layer of the first conductivity type having a third dopant concentration, the third semiconductor layer disposed on the second semiconductor layer;
a fourth semiconductor layer of the first conductivity type having a fourth dopant concentration lower than the dopant concentration, the fourth semiconductor layer disposed on the third semiconductor layer; and
a source region and a drain region disposed in the second semiconductor layer and on opposite sides of the third semiconductor layer.

### Claim 2 (depends on 1)

The lateral junction field-effect transistor of claim 1 further comprising:
a source electrode on the source region;
a drain electrode on the drain region; and
a gate electrode on the fourth semiconductor layer.

### Claim 3 (depends on 2)

The lateral junction field-effect transistor of claim 2 further comprising a backside source electrode on a backside of the substrate, wherein the backside source electrode and the source electrode are electrically connected together.

### Claim 4 (depends on 1)

The lateral junction field-effect transistor of claim 1 wherein the first dopant concentration and the fourth dopant concentration have a same dopant concentration.

### Claim 5 (depends on 1)

The lateral junction field-effect transistor of claim 1 wherein the third dopant concentration of the third semiconductor layer comprises a first portion below the fourth semiconductor layer having a uniformly distributed dopant concentration and a second portion not below the fourth semiconductor layer having a gradually decreasing dopant concentration in a lateral direction toward the drain region.

### Claim 6 (depends on 1)

The lateral junction field-effect transistor of claim 1 further comprising an air gap between the third semiconductor layer and the drain region.

### Claim 7 (depends on 6)

The lateral junction field-effect transistor of claim 6 wherein the second dopant concentration of the second semiconductor layer comprises:
a first dopant concentration portion in the source region;
a second dopant concentration portion in a portion of the second semiconductor layer between the source region and the drain region;
a third dopant concentration portion below a portion of the third semiconductor layer that is not below the fourth semiconductor layer;
a fourth dopant concentration portion below the air gap; and
a fifth dopant concentration portion adjacent the fourth dopant concentration portion,
wherein:
the first dopant concentration portion has a same dopant concentration as the second dopant concentration;
the third dopant concentration portion has a gradually decreasing dopant concentration in a lateral direction toward the source region; and
the fourth dopant concentration portion and the fifth dopant concentration portion each have a dopant concentration that gradually decreases stepwise in a vertical direction toward the substrate.

### Claim 8 (depends on 7)

The lateral junction field-effect transistor of claim 7 wherein the fourth dopant concentration portion has a first number of zones having different dopant concentrations in the vertical direction, and the fifth dopant concentration portion has a second number of zones having different dopant concentrations in the vertical direction.

### Claim 9 (depends on 8)

The lateral junction field-effect transistor of claim 8 wherein the first number of zones is less than the second number of zones.

### Claim 10 (depends on 8)

The lateral junction field-effect transistor of claim 8 wherein each zone has a constant dopant concentration.