Patent ID: 6313000
Filing Date: 2001-11-06
Classification: H01L

Abstract:
A process for forming a bipolar transistor comprising the steps of:forming a first trench in a semiconductor workpiece of a first conductivity type, the first trench circumscribing a precursor device region;filling the first trench with a sacrificial material;introducing a conductivity-altering dopant of a second conductivity type opposite to the first conductivity type into the precursor device region;causing the conductivity-altering dopant of the second type to diffuse in a vertical direction into the semiconductor workpiece, the first trench constraining lateral diffusion within the semiconductor workpiece of the conductivity-altering dopant of the second type;forming a second trench in the semiconductor workpiece, the second trench broader than and encompassing the first trench, such that the sacrificial material is consumed;filling the second trench with a dielectric material;forming a collector of the first conductivity type within the precursor device region;forming a base of the second conductivity type within the collector;forming an emitter of the first conductivity type within the base.