PILED BARRIER - DIFFUSION SOURCE AND ETCHING OBSTACLE FOR DUPLEX POLYSILICON BIPOLAR TRANSISTOR WITH PATTERNIZED BASE BOND

摘要

PROBLEM TO BE SOLVED: To create a double polysilicon bipolar transistor with a base link by a simple treatment process by covering with a barrier layer to protect a base link diffusion source layer that is constituted of a material that is selectively etched for silicon. SOLUTION: A base link diffusion source layer 118 is formed by covering the part of a collector region. Also, a barrier layer 119 is formed by covering a base link diffusion source layer to protect the base link diffusion source layer 118 at a later continuous treatment. A base electrode 114 is formed, so that one edge part of a barrier layer 119 and the base link diffusion layer 118 can be covered, and the exposed part of the barrier layer 119 and the base link diffusion layer 118 under it are eliminated. The base link diffusion source layer 118 can be selectively eliminated for a collector region, thus preventing the region from being damaged and hence protecting the base link diffusion source layer against damages and excessive etchings.