Patent ID: 7528461
Filing Date: 2009-05-05
Classification: H01L

Abstract:
1. A bipolar power transistor comprising: a substrate having a first type of conductivity; a collector diffusion having the first type of conductivity on a back side of said substrate; a first buried base region having a second type of conductivity on a front side of said substrate; a first buried emitter region having the first type of conductivity in said first buried base region; an epitaxial layer on an upper surface of said first buried base region, an upper surface of said first buried emitter region and an upper surface of said substrate; a base contact diffusion and an emitter contact diffusion respectively having the second and first type of conductivities, and extending through said epitaxial layer for respectively contacting said first buried base region and said first buried emitter region; an equalization diffusion having the first type of conductivity and extending through said epitaxial layer and contacting said substrate; an auxiliary diffusion having the second type of conductivity and extending through said epitaxial layer and laterally spaced from said first base region, said auxiliary diffusion forming with said equalization diffusion a junction; and an equalization conduction layer in contact with said equalization diffusion and said auxiliary diffusion for electrically shorting the junction.