| 摘要 |
PURPOSE:To form an ohmic electrode having high reliability and low contacting resistance by forming a metal film made by sequentially laminating Ti and Pt on a semiconductor of specific carrier density. CONSTITUTION:A collector contact layer 2, a collector layer 3, a base layer 4, an emitter layer 5 and an emitter contact layer 6 are sequentially formed on a substrate 1 made of an Fe-doped insulating InP of a bipolar transistor. A portion made of InP and a portion made of In0.76Ga0.24As0.56P0.44 are selectively mesa etched with etchants of hydrochloric acid, phosphoric acid and sulfuric acid, hydrogen peroxide, water. Then, emitter base and collector electrodes 7, 8, 9 formed by sequentially laminating Ti and Pt are formed by a lifting-OFF method using a resist, an SiO2 is further accumulated by CVD, patterned to form a protective film 11, and a cover electrode 10 is formed by lifting OFF of the resist. Since the Ti lacks a reaction with the semiconductor and the Pt prevents Au of the cover electrode 10 from invading to the semiconductor layer, the decrease of the reliability due to the deterioration of the electrodes can be largely suppressed. The electrodes made of the Ti and the Pt are ohmic for the P-type semiconductor to be simply manufactured.
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