Northern Telecom Limited

Xiao-Ming Li

Sorin P Voinigescu

T Victor Herak

A lateral bipolar transistor comprising a self-aligned polysilicon base contact, and polysilicon emitter and collector contacts is provided. The self-aligned base contact significantly reduces the base width and therefore the base resistance compared with conventional lateral bipolar transistors, thus improving f.sub.t and f.sub.max. The polysilicon emitter and collector contacts improve the emitter efficiency and current gain, and allows for more flexible contact placement. The process is compatible with conventional double-poly bipolar processes.

Method for forming a lateral bipolar transistor

Lateral bipolar transistor having buried base contact

A self-aligned single polysilicon bipolar transistor structure and a method of formation thereof are provided. The transistor has an emitter structure characterised by T shape defined by inwardly extending sidewall spacers formed by oxidation of amorphous or polycrystalline silicon, rather than the conventional oxide deposition and anisotropic etch back. Advantageously the method compatible with bipolar CMOS processing and provides a single polysilicon self-aligned bipolar transistor with a reduced number of processing steps. Further the formation of inwardly extending sidewalls defining the emitter width reduces the emitter base junction width significantly from the minimum dimension which is defined by photolithography, while a large area emitter contact is also provided.

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Ottawa, Canada

Xiao-Ming Li