Fabricating a field effect transistor utilizing a dummy gate

US4728621A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Volker Graf · Lambach, DE
• Albertus Oosenbrug · Denzlingen, DE

Key dates

• Filing date: Nov 24, 1986
• Grant date: Mar 1, 1988
• Expiry date: Nov 24, 2006

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D64/017

Abstract

A process for the fabrication of "low temperature"-gate MESFET structures, i.e., gate metal deposition takes place after annealing of an n.sup.+ -implant that form source- and drain- contact regions. The process permits self-alignment of all three important MESFET parts, namely, the implanted contact regions, and both, the ohmic, as well as the gate, contact metallizations. In the process, a multi-layer "inverted-T" structure is used as a mask for the n.sup.+ -implant and for the ohmic and gate metallizations. The upper part of the "inverted-T" is a so-called dummy gate which is replaced by the Schottky gate after ohmic contact metal deposition. The source-gate and drain-gate separations are determined by the shoulders of the lower layer of the "inverted-T", the shoulders being obtained using sidewall techniques.