Stepped collector implant and method for fabrication

US6506656B2 · kind B2 · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Gregory G. Freeman · Hopewell Junction, US
• Basanth Jagannathan · Beacon, US
• Shwu-Jen Jeng · Wappingers Falls, US
• Jeffrey B. Johnson · Hague, US

Key dates

• Filing date: Mar 19, 2001
• Grant date: Jan 14, 2003
• Expiry date: Mar 19, 2021

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D62/60

Abstract

The present invention provides a unique device structure and method that provides increased transistor performance in integrated bipolar circuit devices. The preferred embodiment of the present invention provides improved high speed performance with a stepped collector dopant profile that reduces emitter-collector transit time and parasitic resistance with minimal increase in parasitic capacitances. The preferred stepped collector dopant profile includes a shallow implant and a deeper implant. The shallow implant reduces the base-collector space-charge region width, reduce resistance, and tailors the collector-base breakdown characteristics. The deeper implant links the buried collector to the subcollector and provides a low resistance path to the subcollector. The stepped collector dopant profile has minimal impact on the collector-base capacitance outside the intrinsic region of the device since the higher dopant is compensated by, or buried in, the extrinsic base dopants outside the intrinsic region.