Abstract: A process for manufacturing GaAs FET's having refractory metal gates provides for reducing the size of the gate relative to a mask by an etch sequence which results in precisely controlled and repeatable self-limited undercutting of the mask. A reactive ion etch of the refractory metal in a CF.sub.4 O.sub.2 plasma containing an inert gas provides the self-limiting undercut at a pressure in the range of 175-250 mTorr when the power is less than 0.15 W/cm.sup.2. Preceeding the undercut, an anisotropic RIE in a CF.sub.4 plasma can be employed to clear unmasked areas of the refractory metal and an initial sputter cleaning in argon improves the quality of the initial etch.
Type:
Grant
Filed:
December 23, 1987
Date of Patent:
July 18, 1989
Assignee:
ITT A Division of ITT Corporation Gallium Arsenide Technology Center
Inventors:
Matthew L. Balzan, Arthur E. Geissberger, Robert A. Sadler