# US 2021/0280678 A1 · Greyscale lithography for double-slanted gate connected field plate

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2021/0280678 A1
- Document ID: US20210280678A1
- Status: Published application
- Kind: A1
- Application number: 17/197,008
- Filed: 2021-03-09
- Published: 2021-09-09
- Earliest claimed: 2020-03-09
- Assignees: Insyt, Inc.
- Inventors: Kedar Patel
- Web page: https://patentgrep.com/patent/US20210280678A1

## CPC

- 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 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT}
- H10D 64/111: {Field plates}
- H10P 50/73: {using masks for insulating materials}
- H10P 76/2041: {Photolithographic processes}
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 64/01: Manufacture or treatment
- H10D 64/256: {for lateral devices wherein the source or drain electrodes are recessed in semiconductor bodies (source or drain electrodes of TFTs H10D30/673)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Methods for manufacturing double-slanted gate connected field plates that allow for the simultaneous optimization of electric field distributions between gate and drain terminals and gate and source terminals are described. A technical benefit of manufacturing the double-slanted gate connected field plate using greyscale lithography is that fabrication costs may be substantially reduced by reducing the number of process steps required to form the double-slanted gate connected field plate. The source-side slope and the drain-side slope of the double-slanted gate connected field plate may be concurrently formed with two different slopes or two different step profiles.

## Claims

### Claim 1

A method for fabricating a double-slanted gate connected field plate using greyscale lithography, comprising:
depositing a passivation layer above a substrate;
depositing a layer of photoresist above the passivation layer;
defining a slanted photoresist profile for the layer of photoresist using a greyscale mask, the slanted photoresist profile includes a first slope associated with a source-side slope of the double-slanted gate connected field plate and a second slope associated with a drain-side slope of the double-slanted gate connected field plate;
etching a portion of the passivation layer to transfer the slanted photoresist profile from the layer of photoresist to the passivation layer; and
depositing a metal stack within the etched portion of the passivation layer to form the double-slanted gate connected field plate.

### Claim 2 (depends on 1)

The method of claim 1, wherein:
the first slope is steeper than the second slope.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
the defining the slanted photoresist profile includes exposing the layer of photoresist to light and then removing a portion of the layer of the photoresist to form the slanted photoresist profile.

### Claim 4

A method for fabricating a double-sided gate connected field plate using greyscale lithography, comprising:
depositing a dielectric layer above a surface;
depositing a layer of photoresist above the dielectric layer;
forming a profile within the layer of photoresist using greyscale lithography, the profile includes one uniform slope associated with a slope of the double-sided gate connected field plate or one or more steps associated with a staircase of the double-sided gate connected field plate;
etching a portion of the dielectric layer to transfer the profile from the layer of photoresist to the dielectric layer; and
depositing one or more layers of metal within the etched portion of the dielectric layer to form the double-sided gate connected field plate.

### Claim 5 (depends on 4)

The method of claim 4, wherein:
the one or more steps associated with the drain-side staircase comprises three steps;
the slope of the double-sided gate connected field plate comprises a drain-side slope of the double-sided gate connected field plate; and
the staircase of the double-sided gate connected field plate comprises a drain-side staircase of the double-sided gate connected field plate.

### Claim 6 (depends on 4)

The method of claim 4, wherein:
the forming the profile within the layer of photoresist using greyscale lithography includes forming a source-side slope for the double-sided gate connected field plate and one or more drain-side steps for the double-sided gate connected field plate.