| 摘要 |
PROBLEM TO BE SOLVED: To prevent the influence of TiW on grain size by placing a Pt layer of a specified thickness between a TiW layer and an Au layer of specified thickness. SOLUTION: An active layer 2 and a n<+> -layer 3 are formed on a semi- insulating GaAs substrate 1, and Si ions are implanted therein. Activation is performed by annealing, and then electrodes of gate 4, source 5, and drain 6 are formed to complete FET. A TiW layer 11 as lower metal, a Pt layer 12 and an Au layer 13 are continuously formed in this order by sputtering. The thickness of the Pt layer is from 50Åto 300Åinclusive. The thickness of the TiW layer is from 50Åto 500Åinclusive. These layers 11, 12, 13 are removed by ion milling, and then a TiW layer 21, a Pt layer 22, and an Au layer 23 are formed as a second wiring layer. This makes it possible to prevent increase in the grain size of Au, and to significantly reduce variation in resistance value even after a long-term energizing test.
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