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:
Dec. 20, 1994
Filed:
Mar. 25, 1993
Ronald D Remba, Sunnyvale, CA (US);
Paul E Brunemeier, Sunnyvale, CA (US);
Bruce C Schmukler, Mountain View, CA (US);
Walter A Strifler, Sunnyvale, CA (US);
Daniel H Rosenblatt, Belmont, CA (US);
Watkins Johnson Company, Palo Alto, CA (US);
Abstract
A solution of hydrogen peroxide [H.sub.2 O.sub.2 ], citric acid [HOC(CH.sub.2 COOH).sub.2 COOH.H.sub.2 O], and a salt of citric acid such as potassium citrate [HOC(CH.sub.2 COOK).sub.2 COOK.H.sub.2 O], and hydrogen peroxide [H.sub.2 O.sub.2 ], in a proper pH range, selectively etches GaAs-containing Group III-V compounds in the presence of other Group III-V compounds. As an illustration, Al.sub.y Ga.sub.1-y As is selectively etched in the presence of Al.sub.x Ga.sub.1-x As (0.ltoreq.y<0.2 & x>0.2) when the pH range of the etchant solution is between approximately 3 and 6. The etchant solution described herein may be utilized in the fabrication of, for example, high-frequency transistors exhibiting improved saturated current (I.sub.dss) and threshold voltage (V.sub.th) uniformity.