# US 7,608,865 B1 · Club extension to a T-gate high electron mobility transistor

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- Number: US 7,608,865 B1
- Document ID: US7608865B1
- Status: Granted
- Kind: B1
- Application number: 12/150,417
- Filed: 2008-04-28
- Published: 2009-10-29
- Granted: 2009-10-27
- Earliest claimed: 2008-04-28
- Assignees: Northrop Grumman Space & Mission Systems Corp.
- Inventors: Carol Osaka Namba; Po-Hsin Liu; Ioulia Smorchkova; Michael Wojtowicz; Robert Coffie; Yaochung Chen
- Web page: https://patentgrep.com/patent/US7608865B1

## CPC

- H10D 64/411: {for FETs}
- 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}
- H10P 76/202: {for lift-off processes}
- H10P 76/2045: {Electron beam lithography processes}
- H10D 62/8325: {Silicon carbide}
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method of fabricating a T-gate HEMT with a club extension comprising the steps of: providing a substrate; providing a bi-layer resist on the substrate; exposing an area of the bi-layer resist to electron beam lithography where the area corresponds to a T-gate opening; exposing an area of the bi-layer resist to electron beam lithography where the area corresponds to the shape of the club extension wherein the area corresponding to the club extension is approximately 1 micron to an ohmic source side of a T-gate and approximately 0.5 microns forward from a front of the T-gate; developing out the bi-layer resist in the exposed area that corresponds to the T-gate opening; developing out the bi-layer resist in the exposed area that corresponds to the club extension; and forming the T-gate and club extension through a metallization process.

## Claims

### Claim 1

A system comprising:
a T-gate high electron mobility transistor (HEMT);
a club extension positioned on an ohmic source side of a proximate front of the T-gate HEMT and approximately 0.03 to 0.5 microns forward from a front of the T-gate HEMT; and
wherein the club extension is metallically affixed to the T-gate HEMT and the T-gate HEMT is affixed to a substrate.

### Claim 2 (depends on 1)

The system of claim 1 wherein the substrate is one of GaN, Sapphire, SiN, SiC, and a III V substrate.

### Claim 3 (depends on 1)

The system of claim 1 wherein the club extends to the substrate.

### Claim 4 (depends on 3)

The system of claim 3 wherein the club approximates a circle with an approximate diameter of 0.4 to 2 microns.

### Claim 5 (depends on 3)

The system of claim 3 wherein the club approximates a square wherein:
a length of a side of the approximate square is approximately 0.4 to 2 microns; and
at least one side of the approximate square is substantially parallel to a wing of the T-gate HEMT.

### Claim 6 (depends on 3)

The system of claim 3 wherein the club approximates a parallelogram wherein:
a height of the approximate parallelogram is approximately 0.4 to 2 microns;
a width of the approximate parallelogram is approximately 0.4 to 2 microns; and
a longer side of the approximate parallelogram is parallel to a wing of the T-gate HEMT.

### Claim 7 (depends on 3)

The system of claim 3 wherein the club approximates a polygon wherein a diameter of the approximate polygon is approximately 0.4 to 2 microns.

### Claim 8 (depends on 1)

The system of claim 1 wherein the club does not extend to the substrate.

### Claim 9 (depends on 8)

The system of claim 8 wherein the club approximates a circle wherein the approximately circular club has an approximate diameter of 0.4 to 2 microns.

### Claim 10 (depends on 8)

The system of claim 8 wherein the club approximates a square wherein:
a length of a side of the approximately square is approximately 0.4 to 2 microns; and
at least one side of the approximately square club is parallel to a wing of the T-gate HEMT.

### Claim 11 (depends on 8)

The system of claim 8 wherein the club approximates a parallelogram wherein:
a height of the approximate parallelogram is approximately 0.4 to 2 microns;
a width of the approximate parallelogram is approximately 0.4 to 2 microns; and
the longer side of the approximate parallelogram is parallel to a wing of the T-gate HEMT.

### Claim 12 (depends on 8)

The system of claim 8 wherein the club approximates a polygon wherein:
a diameter of the approximate polygon is approximately 0.4 to 2 microns.