BiCMOS process having narrow bipolar emitter and implanted aluminum isolation
AssigneeFairchild Semiconductor Corporation
InventorSurinder Krishna
Life of this patent
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Abstract
A bipolar/CMOS process includes bipolar transistors having emitters formed in less than a minimal masking dimension. An opening is formed through a polycrystalline silicon layer deposited on a silicon substrate. After coating the sides of the opening with silicon dioxide, the intrinsic base region of the bipolar transistor and the emitter region are implanted. The extrinsic base is formed by outdiffusion from the polycrystalline silicon layer. The structure includes an epitaxial layer which is more strongly doped below its surface than at its surface to enhance the performance of CMOS transistors formed therein. Additionally, the bipolar and complementary MOS transistors are self-aligned to each other by the manner in which the buried layers are formed.
Claims12
A method of fabricating a semiconductor structure comprising:
- depositing an electrically conductive layer on an underlying region of first conductivity type semiconductor material, the layer including opposite conductivity type impurity;
- removing a first region of the layer extending to the underlying region to thereby provide an opening having sides;
- forming a coating of selected material on the sides of the opening;
- introducing opposite conductivity type impurity through the opening to thereby form a first doped region in the underlying region;
- introducing first conductivity type impurity through the opening to thereby form a second doped region in the first doped region;
- treating the structure to cause some of the opposite conductivity type impurity in the electrically conductive layer to diffuse into the semiconductor material to thereby form a third doped region in contact with the first doped region but not the second doped region;
- and
- providing electrical connections to each of the electrically conductive layers and the second doped region.
Dependencies are inferred from the claim text.