The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 09, 1993
Filed:
Jun. 12, 1991
Pham N Tung, Paris, FR;
Martine Chapuis, Yerres, FR;
Thomson Composants Microondes, Puteaux, FR;
Abstract
Disclosed is a method for making a mushroom gate for a microwave transistor. Three masking layers are deposited on the semiconductor body of a transistor. At least two of these masking layers are different and have selective solvents. After the opening of the external layer, the intermediate layer is dissolved with sub-etching with respect to the external layer, then the base of the gate is etched in the internal layer. The edges of the sub-etching prevent the metal deposited on the mask from adhering to the gate, thus facilitating the lift-off of the mask. Application to microwave transistors with symmetrical or disymmetrical mushroom gate.