| 摘要 |
PURPOSE:To obtain a transistor good in its high-speed performance, by forming an insulation layer between a second electrode and a third semiconductor layer and also forming an insulation layer between the second electrode and a third electrode and besides extending the second electrode, with the insulation layer in between, to the upper position facing the third electrode. CONSTITUTION:Since a second electrode 6 is disposed to extend to the upper position facing a third electrode 7, with an insulation layer 9 in between, the second electrode 6, that is, a base electrode becomes so large in its width that the base resistance can be decreased effectively. When the width of the base electrode is enlarged in this way, the base electrode of planar structure is seen to overlap the third electrode 7, that is, an emitter electrode, and so a planar dimension of an element is not increased. A self-align film forming technique is used to form the insulation layer 9 very thinly on side walls of a third semiconductor layer 4. Since the second electrode, that is, the base electrode 6 is formed with this layer 9 in between, the base electrode 6 can be made to approach an emitter/base junction 10 adequately. Hence, a transistor capable of an high-speed operation can be easily obtained.
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