| 摘要 |
PURPOSE:To manufacture a hetero-junction semiconductor device having small emitter resistance and also small emitter capacitance by forming the structure of an emitter layer in a mushroom shape expanding toward the emitter electrode side from the base layer side. CONSTITUTION:A base layer 2, a graded-emitter layer 3 and an emitter layer 4 are grown on a substrate 1 functioning as an N<+> type GaAs collector layer in combination by applying a molecular-beam epitaxial growth method. The mitter layer 4 is etched while using an emitter electrode 5 as a mask by applying a dry-etching method. The graded-emitter layer 3 is etched through a wet- etching method. The etching of the base layer 2 side in the graded-emitter layer 3 progresses at a speed faster than that of the emitter layer 4 side, thus resulting in a mushroom shape at a stage when etching is completed. Accordingly, emitter capacitance is reduced because the area of the emitter layer 3 being in contact with the base layer 2 is minimized, and emitter resistance is lowered because the area of the emitter layer 4 being in contact with the emitter electrode is increased. |
