National Semiconductor Corporation

Jayasimha S Prasad

Waclaw C Koscielniak

Kulwant S Egan

Ury Priel

Mark S Ebel

Giora Yaron

Ying K Shum

An improved method and an apparatus for forming a self-aligned epitaxial base bipolar transistor in a semiconductor material is disclosed. The method of the invention involves forming an intrinsic base region formed by growing an epitaxial semiconductor material over a collector region. A raised sacrificial emitter core is then formed on the intrinsic base region followed by depositing a substantially conformal spacer layer over the sacrificial emitter core. Next, the spacer material is anisotropically etched such that a protective spacer ring is formed about the sacrificial emitter core. An extrinsic base is then formed by implanting dopant into the epitaxial base region wherein the sacrificial emitter core and the spacer ring preserve an emitter region. The spacer ring also serves to self-align the extrinsic base region to the emitter region. The protective sacrificial emitter core and spacer ring are then removed. The self-aligned epitaxial base bipolar transistor is then formed by doping the emitter region.

Forming a self-aligned epitaxial base bipolar transistor

An electrically programmable and eraseable memory cell in which charge carriers are tunnelled between a floating gate and a drain region in the substrate through a thin oxide tunnel region, the borders of said tunnel region being confined to a small area well inside the borders of both the drain region and the floating gate. Dual paths are utilized to connect the tunnel region of the gate to the memory cell region of the gate.

Electrically programmable and erasable memory cell

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San Jose, CA, United States of America

Jayasimha S Prasad