International Business Machines Corporation

Randall D Isaac

Tak H Ning

Paul Michael Solomon

Denny D Tang

An inverted polycide extrinsic base contact serves as a diffusion source, yet still has low resistivity and is readily etchable down to silicon by techniques useful in manufacturing integrated circuits. The extrinsic base contact layer is made up of a metal silicide (e.g. WSi.sub.2) with an overlying doped polysilicon layer with coextensive apertures through doped polysilicon and metal silicide layers defining the emitter and intrinsic base region. The extrinsic base region is formed by diffusing boron impurities from the p.sup.+ polysilicon layer through the silicide layer. The silicide layer is of a metal silicide such as tungsten silicide (WSi.sub.2). The polysilicon layer acts as a diffusion source, since appropriate dopants (e.g., boron) diffuse rapidly through the metal silicide. Both the top surface of the p.sup.+ polysilicon layer and the sidewall edges of the polysilicon and silicide layers are covered by an insulating layer (e.g. SiO.sub.2) which also separates the emitter contact from the base contact layers.

Self-aligned bipolar transistor with inverted polycide base contact

A bipolar transistor device is disclosed having a structure wherein a layer of insulating material extends over and covers the structure substrate up to the region of the extrinsic base around the emitter. A very small area conductive base contact is provided to the extrinsic base, and a protective wall of insulating material is located on the sidewall of the base contact to isolate it from the emitter contact. This structure is made possible by a fabrication process incorporating a double-self-alignment technique wherein the base is self-aligned to a window in the insulating material and the emitter is self-aligned to the base.

Double self-aligned fabrication process for making a bipolar transistor

An integrated circuit containing a refractory metallic silicide beneath a field isolation region and in electrical contact with electrical conductive regions of active impurity dopants in a semiconductive substrate; and process for the fabrication thereof.

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Yorktown Heights, NY, United States of America

Randall D Isaac