# US 4,394,673 A · Rare earth silicide Schottky barriers

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- Number: US 4,394,673 A
- Document ID: US4394673A
- Status: Granted
- Kind: A
- Application number: 06/191,565
- Filed: 1980-09-29
- Granted: 1983-07-19
- Earliest claimed: 1980-09-29
- Assignees: International Business Machines Corporation
- Inventors: Richard D. Thompson; Boryeu Tsaur; King-Ning Tu
- Web page: https://patentgrep.com/patent/US4394673A

## CPC

- H10D 64/64: Electrodes comprising a Schottky barrier to a semiconductor
- H10D 64/0121: {to Group IV semiconductors}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

In the practice of this disclosure, rare earth disilicide low Schottky barriers (.ltorsim.0.4 eV) are used as low resistance contacts to n-Si. Further, high resistance contacts to p-Si (Schottky barrier of .gtorsim.0.7 eV) are also available by practice of this disclosure. A method is disclosed for forming contemporaneously high (.gtorsim.0.8 eV) and low (.ltorsim.0.4 eV) energy Schottky barriers on an n-doped silicon substrate. Illustratively, the high energy Schottky barrier is formed by reacting platinum or iridium with silicon; the low energy Schottky barrier is formed by reacting a rare earth with silicon to form a disilicide. Illustratively, a double layer of Pt/on W is an effective diffusion barrier on Gd and prevents the Gd from oxidation.

## Claims

### Claim 1

A disilicide Schottky barrier contact having a barrier potential of about 0.4 eV, comprising:
an n-type silicon substrate; and
a rare earth metal deposited on said n-type silicon substrate, wherein said disilicide Schottky barrier contact is formed by heating said silicon substrate and said rare earth metal.

### Claim 2 (depends on 1)

A disilicide Schottky barrier contact as set forth in claim 1 wherein said rare earth metal is a member of the group consisting of Ho, Gd, Er, Dy, Y and La.

### Claim 3 (depends on 2)

A disilicide Schottky barrier contact as set forth in claim 2 wherein said heating is at approximately 400.degree. C. for about 30 minutes.

### Claim 4 (depends on 3)

A disilicide Schottky barrier contact as set forth in claim 3 including an oxidation barrier layer deposited on said rare earth metal.

### Claim 5 (depends on 4)

A disilicide Schottky barrier contact as set forth in claim 4 wherein said oxidation barrier layer is one member of the group consisting of a transition metal Pt, Pd, Ni and refractory metals W, V, Cr, Mo and Ti.

### Claim 6

A disilicide Schottky barrier contact having a barrier potential of about 0.7 eV, comprising:
an p-type silicon substrate; and
a rare earth metal deposited on said p-type silicon substrate, wherein said disilicide Schottky barrier contact is formed by heating said silicon substrate and said rare earth metal.

### Claim 7 (depends on 6)

A disilicide Schottky barrier contact as set forth in claim 6 wherein said rare earth metal is a member of the group consisting of Ho, Gd, Er, Dy, Y and La.

### Claim 8 (depends on 7)

A disilicide Schottky barrier contact as set forth in claim 7 wherein said heating is at approximately 400.degree. C. for about 30 minutes.

### Claim 9 (depends on 8)

A disilicide Schottky barrier contact as set forth in claim 8 including an oxidation barrier layer deposited on said rare earth metal.

### Claim 10 (depends on 9)

A disilicide Schottky barrier contact as set forth in claim 9 wherein said oxidation barrier layer is one member of the group consisting of a transition metal Pt, Pd, Ni and refractory metals W, V. Cr, Mo and Ti.