Watkins- Johnson Company

Ronald David Remba

Walter A Strifler

Paul E Brunemeier

William Robert Hitchens

Bruce C Schmukler

Daniel H Rosenblatt

Carol Yu-Bin Lee

Disclosed is a method of fabricating semiconductor devices having sub-micron gate electrodes using angle and direct evaporation techniques. A first and second photoresist layer are formed atop a substrate and the second layer is selectively processed to form an edge with a well controlled profile. A first metal is evaporated at a first angle and the edge of the second photoresist layer shields a portion of the first photoresist layer form metal deposition which defines a patterned opening of desired width. The patterned opening is now etched in a well controlled manner to expose a portion of the active channel region of the device, and a desired height is defined by the distance from the first metal layer to the exposed channel region. A second layer is deposited by evaporation at a second angle thereby forming a plug in the channel region wherein placement of one edge of the plug is determined by the height and the second angle. A gate metal is now directly deposited atop the semiconductor to form a gate electrode in the active channel region, said electrode having a gate length defined by the distance between the edge of the plug and one side of the first metal patterned opening.

Method of fabricating sub-micron gate electrode by angle and direct

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&lt;0.2 & x&gt;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.

Method of fabricating group III-V compound

Growing community of inventors

Sunnyvale, CA, United States of America

Ronald David Remba