# US 10,374,163 B2 · Intermetallic contact for carbon nanotube FETs

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- Number: US 10,374,163 B2
- Document ID: US10374163B2
- Status: Granted
- Kind: B2
- Application number: 15/803,074
- Filed: 2017-11-03
- Published: 2018-07-12
- Granted: 2019-08-06
- Earliest claimed: 2017-01-12
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Matthew W. Copel; Damon B. Farmer; Talia S. Gershon; Paul M. Solomon
- Web page: https://patentgrep.com/patent/US10374163B2

## CPC

- H10K 71/60: Forming conductive regions or layers, e.g. electrodes
- H10K 10/466: {Lateral bottom-gate IGFETs comprising only a single gate}
- H10K 10/478: {the gate dielectric comprising a layer of composite material comprising interpenetrating or embedded materials, e.g. TiO2 particles in a polymer matrix}
- H10K 10/484: {characterised by the channel regions}
- H10K 10/82: Electrodes
- H10K 85/221: {Carbon nanotubes}
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

A field effect transistor includes a carbon nanotube layer formed adjacent to a gate structure. Two intermetallic contacts are formed on the carbon nanotube layer. The two intermetallic contacts include an oxidation resistant compound having a work function below about 4.4 electron-volts.

## Claims

### Claim 1

A method for forming a field effect transistor, comprising:
forming a gate dielectric on a gate electrode;
forming a carbon nanotube layer on the gate dielectric; and
forming intermetallic contacts on the carbon nanotube layer, the intermetallic contacts including an oxidation resistant compound having a work function below 4.4 electron-volts.

### Claim 2 (depends on 1)

The method as recited in claim 1, wherein forming the intermetallic contacts includes forming the intermetallic contacts from a material selected from the group consisting of lanthanum boride, cerium boride, samarium boride, lanthanum aluminide, europium aluminide and strontium aluminide.

### Claim 3 (depends on 1)

The method as recited in claim 1, wherein forming the intermetallic contacts includes sputtering or evaporation.

### Claim 4 (depends on 1)

The method as recited in claim 1, further comprising forming a capping layer on the intermetallic contacts, wherein the capping layer includes at least one of aluminum and titanium.

### Claim 5 (depends on 1)

The method as recited in claim 1, wherein forming the intermetallic contacts includes depositing a layer of intermetallic material on the carbon nanotube layer.

### Claim 6 (depends on 1)

The method as recited in claim 1, wherein forming the intermetallic contacts includes forming the intermetallic contacts from a material that includes rare earth aluminide.

### Claim 7 (depends on 1)

The method as recited in claim 1, wherein the intermetallic contacts include an oxidation resistance greater than that of pure lanthanum.

### Claim 8 (depends on 1)

The method as recited in claim 1, wherein the gate dielectric includes an oxygen containing compound.

### Claim 9 (depends on 1)

The method as recited in claim 1, wherein forming the intermetallic contacts includes etching through an intermetallic layer down to the carbon nanotube layer.

### Claim 10 (depends on 1)

The method as recited in claim 1, wherein forming the intermetallic contacts includes a lift-off process.

### Claim 11

A method for forming a field effect transistor, comprising:
forming a gate electrode with a substrate;
depositing a gate dielectric on the gate electrode;
forming a carbon nanotube layer on the gate dielectric;
patterning the carbon nanotube layer; and
depositing intermetallic contacts on the carbon nanotube layer, the intermetallic contacts including an oxidation resistant compound having oxidation resistance better than lanthanum.

### Claim 12 (depends on 11)

The method as recited in claim 11, wherein forming the intermetallic contacts includes forming the intermetallic contacts from a material including a metal boride.

### Claim 13 (depends on 11)

The method as recited in claim 11, wherein forming the intermetallic contacts includes forming the intermetallic contacts from a material including a rare-earth boride.

### Claim 14 (depends on 11)

The method as recited in claim 11, wherein forming the intermetallic contacts includes forming the intermetallic contacts from a material selected from the group consisting of lanthanum boride, cerium boride, samarium boride.

### Claim 15 (depends on 11)

The method as recited in claim 11, wherein forming the intermetallic contacts includes forming the intermetallic contacts from a material including a rare-earth aluminide.

### Claim 16 (depends on 11)

The method as recited in claim 11, wherein forming the intermetallic contacts includes forming the intermetallic contacts from a material selected from the group consisting of lanthanum aluminide, europium aluminide and strontium aluminide.

### Claim 17 (depends on 11)

The method as recited in claim 11, wherein forming the intermetallic contacts includes sputtering or evaporation.

### Claim 18 (depends on 11)

The method as recited in claim 11, further comprising forming a capping layer on the intermetallic contacts, wherein the capping layer includes at least one of aluminum and titanium.

### Claim 19 (depends on 11)

The method as recited in claim 11, wherein forming the intermetallic contacts includes etching through an intermetallic layer down to the carbon nanotube layer.

### Claim 20 (depends on 11)

The method as recited in claim 11, wherein forming the intermetallic contacts includes a lift-off process.