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AssigneeNational Semiconductor Corporation
InventorsAshok K. Kapoor, J. Frank Ciacchella
Estimating the term…
There is disclosed herein a transistor having a sidewall base contact. The base region of the transistor is in a column of selectively grown epitaxial silicon isolated from adjacent structures in a field of oxide. The sidewall base contact is a layer of doped polysilicon which is embedded in the insulating material surrounding the column of epitaxial silicon. The collector contact is formed of another column of selectively grown epitaxial silicon grown over and in electrical contact with a buried layer underlying the first column of epitaxial silicon. The emitter region is implanted into the top of column doped as the base region. In one embodiment, the base contact is a buried polysilicon layer. In another embodiment, the base contact is epitaxial silicon which is grown over oxide by uncontrolled growth following controlled selective growth. There are also disclosed two processes for making the structure comprised of the steps of forming a layer of oxide, etching two holes in it and growing the epitaxial silicon in the holes. Thereafter, in one embodiment, the oxide is etched back to expose the sidewalls of the columns and polysilicon is deposited, doped and etched to form the sidewall base contacts. In another embodiment, the base contact is formed by allowing the selectively grown epitaxial silicon to grow laterally out over the top of the oxide layer in the columns of epi are grown. The structure is then planarized, the emitter region is formed, and the contact holes are etched and contacts are formed.
An integrated circuit bipolar transistor comprising:
An integrated circuit bipolar transistor comprising:
An integrated circuit bipolar transistor comprising:
Dependencies are inferred from the claim text.