# US 4,392,928 A · Method of doping a semiconductor

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- Number: US 4,392,928 A
- Document ID: US4392928A
- Status: Granted
- Kind: A
- Application number: 06/342,683
- Filed: 1982-01-26
- Granted: 1983-07-12
- Earliest claimed: 1982-01-26
- Assignees: The United States of America as represented by the United States Department of Energy
- Inventors: Chiang Y. Yang; Robert A. Rapp
- Web page: https://patentgrep.com/patent/US4392928A

## CPC

- H10P 32/14: within a single semiconductor body or layer in a solid phase; between different semiconductor bodies or layers, both in a solid phase
- C30B 31/02: by contacting with diffusion materials in the solid state
- H10P 32/17: {characterised by the semiconductor material}
- H10P 95/00: Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass
- H10P 95/80: Electrical treatments, e.g. for electroforming
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR

## Abstract

A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

## Claims

### Claim 1

A method for doping semiconductor material with a chosen impurity comprising the steps of:
(a) establishing an interface between a solid semiconductor and a solid electrolyte, forming a semiconductor/electrolyte cell, said solid electrolyte being an ionic conductor of said impurity and said semiconductor and said electrolyte being jointly chosen so that any compound formed from said semiconductor and said impurity will have a free energy of formation no lower than the free energy of formation of said electrolyte; and,
(b) establishing a potential across said interface, said potential being chosen so as to allow diffusion of impurity ions from said electrolyte into said semiconductor.

### Claim 2 (depends on 1)

The method of claim 1, wherein said semiconductor/electrolyte cell is heated to a temperature sufficient to substantially increase the diffusivity of said impurity in said semiconductor material.

### Claim 3 (depends on 2)

The method of claim 2 wherein a counter-electrode is connected to said solid electrolyte to provide a return path for current and to maintain a substantially constant impurity ion concentration in said electrolyte.

### Claim 4 (depends on 3)

The method of claim 3, wherein a third, reference, electrode is connected to said electrolyte between said working electrode and said counter-electrode and a potentiostat is connected to said electrodes to maintain said potential constant.

### Claim 5 (depends on 4)

The method of claim 4, wherein electrical contact is made to said semiconductor through an extended metal contact, said contact extending over a surface of said semiconductor, said surface being spaced from, essentially parallel to and essentially congruent with said interface, and said contact being formed from a metal substantially impervious to said impurity.

### Claim 6 (depends on 1, 2, 3, 4, 5)

The method of claims 1, 2, 3, 4 or 5, wherein said semiconductor material is in the form of a sample having known values for the parameters A, V and d, said method comprising the additional steps of:
(a) first establishing values for C(E.sub.o.c.), D(T) and C(E.sub.1) for selected values of T and E;
(b) after step (a) of claim 1 heating said cell to said selected value of T;
(c) establishing the selected value of E.sub.1 as the potential step (b) of claim 1; and
(d) continuing to apply said potential for a selected time t, whereby a selected concentration distribution, C(x,t) is established, C(x,t) being approximately determined by the relationship: ##EQU9##

### Claim 7 (depends on 1, 2, 3, 4, 5)

The method of claims 1, 2, 3, 4 or 5, wherein said semiconductor has previously been doped.

### Claim 8 (depends on 6)

The method of claim 6, wherein after a said selected time one of the parameters E, or T is changed and the doping is continued for a further period.