P A P E R    T I T L E
Electrochemical Etching in the Fabrication of Short Gate-Length InAlAs/InGaAs Heterojunction FETs

A U T H O R  /  C R E D I T S
Dong Xu * , Takatomo Enoki, and Yasunobu Ishii
advance Device and Technology Lab., System Electronics Laboratories, Nippon Telegraph and Telephone Corporation,
3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198, Japan
*now with Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 56556, U.S.A.
telephone: (219) 613 8245, fax: (219) 631 4393, email: dxu@nd.edu

The use of electrochemical etching in fabricating InAlAs/InGaAs heterojunction field-effect transistors (HFETs) is presented. The electrochemical etching arises when resist openings are employed to monitor the drain current of HFETs during wet-chemical gate recess, which results in etching rates for InGaAs and InAlAs that are significantly different from those calibrated with wafer pieces. The electrochemical phenomena are investigated. Their applications in improving layout-independence and short-channel effects of HFETs are shown. In addition, an electrochemical-etching-based manu-facturing technology is demonstrated to fabricate high-per-formance short gate-length enhancement-mode HFETs.