Patent ID: 6989301
Filing Date: 2006-01-24
Classification: H01L

Abstract:
1. A method for manufacturing a semiconductor device having a hetero-junction bipolar transistor over a semiconductor substrate, comprising the steps of: (a) preparing a semiconductor substrate having a first semiconductor layer of a first type over the semiconductor substrate, a second semiconductor layer of a second type over the first semiconductor layer, and a third semiconductor layer of the first type over the second semiconductor layer, wherein the first type and the second type are opposite; (b) forming an emitter electrode of the hetero-junction bipolar transistor over the third semiconductor layer; (c) after the step (b), forming the third semiconductor layer into a mesa-shaped emitter layer of the hetero-junction bipolar transistor; (d) after the step (c), forming a base electrode over the second semiconductor layer outside the mesa-shaped emitter layer; (e) after the step (d), forming a photo resist film over the emitter and base electrodes; and (f) after the step (e), etching the second semiconductor layer to form a mesa-shaped base layer of the hetero-junction bipolar transistor, wherein in the step (e), an outer periphery of the base electrode is exposed from the photo resist film; and in the step (f), the photo resist film and base electrode act as an etching mask.