# US 7,411,258 B2 · Cobalt disilicide structure

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- Number: US 7,411,258 B2
- Document ID: US7411258B2
- Status: Granted
- Kind: B2
- Application number: 09/939,895
- Filed: 2001-08-27
- Published: 2002-01-10
- Granted: 2008-08-12
- Earliest claimed: 1999-04-22
- Assignees: International Business Machines Corporation
- Inventors: David Paul Agnello; Mary Conroy Bushey; Donna K. Johnson; Jerome Brett Lasky; Peter James Lindgren; Kirk David Peterson
- Web page: https://patentgrep.com/patent/US7411258B2

## CPC

- H10D 30/0212: {using self-aligned silicidation}
- H10D 64/0112: {using conductive layers comprising silicides}
- H10P 50/283: {by chemical means}
- H10P 50/667: {by liquid etching only}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A structure relating to removal of an oxide of titanium generated as a byproduct of a process that forms cobalt disilicide within an insulated-gate field effect transistor (FET). The structure may comprise a layer of cobalt disilicide that is substantially free of cobalt monosilicide, with substantially no stringer of an oxide of titanium on the layer of cobalt disilicide. The structure may alternatively comprise a layer of cobalt disilicide, a patch of an oxide of titanium, and a reagent in contact with the patch at a temperature and for a period of time. The layer is substantially free of cobalt monosilicide. The patch is on the layer of cobalt disilicide. The reagent is adapted to remove the patch within the period of time. The reagent does not chemically react with the layer of cobalt disilicide, and the reagent comprises water, ammonium hydroxide, and hydrogen peroxide.

## Claims

### Claim 1

A structure, comprising a layer of cobalt disilicide and a layer of silicon, wherein the layer of cobalt disilicide is on the layer of silicon, wherein the layer of cobalt disilicide is substantially free of cobalt monosilicide, wherein there is essentially no stringer of an oxide of titanium on the layer of cobalt disilicide, and wherein the layer of cobalt disilicide is in contact with a reagent comprising water, ammonium hydroxide, and hydrogen peroxide.

### Claim 2 (depends on 1)

The structure of claim 1, wherein the reagent is not adapted to chemically react with the layer of cobalt disilicide.

### Claim 3 (depends on 1)

The structure of claim 1, wherein the ammonium hydroxide comprises approximately 4 percent of a total reagent volume of the reagent, and wherein the hydrogen peroxide comprises approximately 4 percent of the total reagent volume.

### Claim 4 (depends on 1)

The structure of claim 1, wherein the reagent is at a temperature within a range of about 45 degrees celsius to about 95 degrees celsius.

### Claim 5

A structure having a substrate, wherein the substrate includes:
an insulated-gate field effect transistor (FET), wherein the FET includes a source, a drain, and a gate;
a first layer of cobalt disilicide on the source, said first layer having substantially no cobalt monosilicide, and said first layer having essentially no stringer of an oxide of titanium thereon;
a second layer of cobalt disilicide on the drain, said second layer having substantially no cobalt monosilicide, and said second layer having essentially no stringer of an oxide of titanium thereon; and
a third layer of cobalt disilicide on the gate, said third layer having substantially no cobalt monosilicide, and said third layer having essentially no stringer of an oxide of titanium thereon, wherein the first layer of cobalt disilicide, the second layer of cobalt disilicide, and the third layer of cobalt disilicide are each in contact with a reagent comprising water, ammonium hydroxide, and hydrogen peroxide.

### Claim 6 (depends on 5)

The structure of claim 5, further comprising:
a first insulating structure bordering a side of the source and bordering a side of the first layer of cobalt disilicide; and
a second insulating structure bordering a side of the drain and bordering a side of the second layer of cobalt disilicide.

### Claim 7 (depends on 5)

The structure of claim 5, wherein the reagent is not adapted to chemically react with the first layer of cobalt disilicide, wherein the reagent is not adapted to chemically react with the second layer of cobalt disilicide, and wherein the reagent is not adapted to chemically react with the third layer of cobalt disilicide.

### Claim 8 (depends on 5)

The structure of claim 5, wherein the ammonium hydroxide comprises approximately 4 percent of a total reagent volume of the reagent, and wherein the hydrogen peroxide comprises approximately 4 percent of the total reagent volume.

### Claim 9 (depends on 5)

The structure of claim 5, wherein the reagent is at a temperature within a range of about 45 degrees celsius to about 95 degrees celsius.