| 摘要 |
A method of forming bipolar transistors by using the same mask to form the collector region in a substrate of an opposite conductivity type as to form the base in the collector region. More specifically, impurities of a first conductivity type are introduced into a region of a substrate of a second conductivity type through a first aperture in a first mask to form a collector region. Impurities of the second conductivity type are introduced in the collector through the first aperture in the first mask to form the base region. Impurities of the first conductivity type are then introduced into the base region through a second aperture in a second mask to form the emitter region. The minimum dimension of the first aperture of the first mask is selected for a desired collector to base breakdown voltage. This allows tuning of the breakdown voltage.
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