Method of making emitter trench BiCMOS using integrated dual layer emitter mask

Patent 5488003 Issued on January 30, 1996. Estimated Expiration Date:

March 31, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Method for making a base etched transistor integrated circuit
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Inventors

Application

No. 040673 filed on 03/31/1993

US Classes:

438/309, FORMING BIPOLAR TRANSISTOR BY FORMATION OR ALTERATION OF SEMICONDUCTIVE ACTIVE REGIONS257/565, BIPOLAR TRANSISTOR STRUCTURE257/587, With specified electrode means257/E21.375, Silicon vertical transistor (EPO)257/E21.696, Bipolar and MOS technologies (EPO)257/E29.03, Emitter regions of bipolar transistors (EPO)438/368, Simultaneously outdiffusing plural dopants from polysilicon or amorphous semiconductor438/370, Forming buried region (e.g., implanting through insulating layer, etc.)438/561Dopant source within trench or groove

Examiners

Primary: Chaudhuri, Olik
Assistant: Pham, Long

Attorney, Agent or Firm

Blakely, Sokoloff, Taylor & Zafman

Foreign Patent References

0033495 EP. 01/11/1981

International Class

H01L 021/265

Abstract

A new method of isolating a polysilicon emitter from the base region of a bipolar transistor, trenching the polysilicon emitter into the semiconductor substrate, and maintaining a consistent base width of a bipolar transistor independent of variations in emitter mask thicknesses is disclosed. The polysilicon emitter isolation provides for better electrical breakdown characteristics between the emitter and the base by protecting the dielectric layer between the polysilicon emitter and base regions from defects and contamination associated with the BiCMOS manufacturing environment. The polysilicon emitter is trenched into the semiconductor substrate in order to reduce transistor operation problems associated with hot electron injection. Consistent base widths improve transistor performance uniformity thereby improving manufacturability and reliability.