| 摘要 |
PROBLEM TO BE SOLVED: To optimize high-frequency characteristics of a hetero bipolar transistor by minimizing the capacitance of parastic base collector so as to increase cut-off frequencies fT and fmax. SOLUTION: A transistor is structured in a mesa structure type, and a first planarization process is applied to the upper boundary and limit of a base 3. The surface of the base 3 is protected by the protective layers 41 and 42 of an emitter layer 4 on the base 3, and then the protective layers 41 and 42 are removed and a base metal 8 is adhered thereto. Further a second planarization process is applied to the base, emitter and mesa, and a terminal metallized part 10 is adhered.
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