Watkins- Johnson Company

Wj Communications, Inc.

Walter A Strifler

Ronald David Remba

Nanlei Larry Wang

Paul E Brunemeier

William Robert Hitchens

Daniel H Rosenblatt

Bruce C Schmukler

Brad D Cantos

Carol Yu-Bin Lee

The embodiments of the present invention include a bias circuit for a power-amplifying device, which receives and amplifies an input RF signal having a series of RF cycles within a modulation envelop. The bias circuit compensates odd-order distortion processes by detecting the power in the input signal and providing a dynamic adjustment to a bias stimulus for the power-amplifying device within a time scale of the modulation envelope.

Bias circuit for BJT amplifier

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

Disclosed is a method of forming a uniform length gate electrode and contact for a microwave field-effect transistor where the gate electrode has a length of less than one micron. A photoresist plug is formed on the surface of a first photoresist layer, the plug functioning as a shadow mask in the subsequent deposition of a plasma-etch-resistant material (aluminum) over the surface of the plug and the first photoresist layer. A third photoresist layer is formed over the device structure whereby a contact region can be formed on the surface of the semiconductor sub-strate adjacent to the device region. Subsequently, the third photoresist layer is removed, and the previously shielded photoresist material over the gate electrode location is removed by plasma etch using the metal-covered plug and metal-covered first photoresist layer as a plasma-etch shield. A metal is then deposited in the exposed surface region for the gate electrode and contact, and thereafter the photoresist material is removed leaving the gate electrode and contact on the substrate surface.

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Sunnyvale, CA, United States of America

Walter A Strifler