Abstract: 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.

Abstract: 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.

Abstract: The disclosed HBT IC process can fabricate npn heterojunction bipolar transistors, Schottky diodes, MIM capacitors, spiral inductors, and NiCr resistors. Two levels of interconnect metal are available. The first level metal is a conventional dielectric-insulated metal conductor. The second level metal includes an air-bridge for contacting the HBT emitters, which are on top of three level mesa structures. It is also an advanced low loss, low capacitance, air dielectric conductor useful for long interconnects and inductors. MIM capacitors are formed by sandwiching silicon nitride between the first layer metal and a capacitor top plate made with landed air-bridge metal. Precision thin film resistors are fabricated by depositing NiCr on silicon nitride. The three-level active mesa structure is etched down to the GaAs substrate, for lateral device isolation, with a truncated pyramidal shape which permits good step coverage of dielectric and metallization layers. The wet etching process uses a composition of H.sub.

Abstract: 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.