US 5,849,630 A · Process for forming ohmic contact for III-V semiconductor devices

Abstract

A dependable ohmic contact with consistently low specific contact resistance (<1.times.10.sub.-6 .OMEGA.-cm.sup.2) to n-type GaAs (10) is produced by a three or four step procedure. The procedure, which is employed following implantation to form doped regions in the GaAs substrate for contacting thereto, comprises: (a) adsorbing or reacting sulfur or a sulfur-containing compound (26) with the GaAs surface (10') at locations where the contact metal (28) is to be deposited; (b) forming a metal contact layer (28) on the treated portions of the GaAs surface; (c) optionally forming a protective layer (30) over the metal contact; and (d) heating the assembly (metal and substrate) to form the final ohmic contact. The surface treatment provides a lower specific contact resistance of the ohmic contact. Elimination of gold in the ohmic contact further improves the contact, since intermetallic compounds formed between gold and aluminum interconnects ("purple plague") are avoided. In addition, the absence of gold in the metal improves the reliability of ohmic contacts, and the resulting metal can be patterned by etching or lift-off process.

Claims35

Dependent claims

A process for forming a thermally stable, low resistance ohmic contact on a major surface of a III-V semiconductor substrate, comprising:

(a) doping at least one region in said major surface of said III-V semiconductor substrate with a dopant to form an active region to which said ohmic contact is to be made;
(b) introducing a Group VI element onto the surface of said at least one active region to form treated portions of said III-V surface of said at least one active region, said treated portions limited to substantially the surface thereof;
(c) forming a metal contact, capable of forming said ohmic contact to said III-V semiconductor, on said treated portions of said III-V surface;
(d) forming a protective layer over said metal contact;
and
(e) heating said metal contact and said III-V semiconductor to form said low resistance ohmic contact.

3 more elements

Dependencies are inferred from the claim text.

Process for forming ohmic contact for III-V semiconductor devices

Life of this patent

Process for forming ohmic contact for III-V semiconductor devices

Life of this patent

Abstract

Claims35