National Semiconductor Corporation

Joseph Anthony DeSantis

Alexei Sadovnikov

Rashid Bashir

Richard Wendell Foote, Jr

Kevin Carl Brown

Wipawan Yindeepol

Joel M McGregor

Edward F Pressley

Christoher J Knorr

An improved method for manufacturing bipolar transistors is disclosed. The method for forming a PNP transistor comprises the steps of forming a P type collector on a substrate, forming a PNP epitaxial base on the P type collector, forming a PNP extrinsic base in the PNP epitaxial base, and forming a PNP emitter in contact with the PNP extrinsic base. The method for forming an NPN transistor comprises the steps of forming an N type collector on a substrate, forming a NPN epitaxial base on the N type collector, forming an NPN extrinsic base in the NPN epitaxial base, and forming an NPN emitter in contact with the NPN extrinsic base. The PNP and NPN transistors may be manufactured in the same control flow process.

Method for manufacturing bipolar transistors

A method of forming and planarizing a deep isolation trench in a silicon-on-insulator (SOI) structure begins with a base semiconductor substrate, a buried insulator layer formed on the base semiconductor substrate, and an active silicon layer formed on the buried insulator layer. First, an ONO layer is formed on the active silicon layer. The ONO layer includes a layer of field oxide, a first layer of silicon nitride and a layer of deposited hardmask oxide. A trench having sidewalls that extend to the buried oxide layer is formed. A layer of trench lining oxide is then formed on the exposed sidewalls of the trench. Then, a second layer of silicon nitride is conformally formed on the substrate. The second nitride layer is then anisotropically etched to remove the nitride from the exposed horizontal surface of the hardmask oxide and the buried oxide in the bottom of the trench, but leaving silicon nitride on the vertical sidewall portions of the hardmask oxide, on the sidewalls of the first nitride layer on the sidewalls of the field oxide and on the trench lining oxide. A layer of polysilicon is then deposited to fill the trench and etched back such that the top surface of the polysilicon substantially corresponds to the top surface of the layer of field oxide. The hardmask oxide layer is then removed and the top surface of the polysilicon layer is oxidized.

Method of forming and planarizing deep isolation trenches in a

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San Jose, CA, United States of America

Joseph Anthony DeSantis