Method for fabricating bipolar transistors

A method for making a double polysilicon bipolar transistor including an emitter having the form of a stripe, a base, a polysilicon base conductive layer, and a polysilicon emitter contact comprising the steps of:

• A. providing a workpiece comprising a silicon substrate including a doped buried layer, a doped epitaxial layer overlying the buried layer, a device well region and isolation regions overlying the doped epitaxial layer;
• B. forming on the workpiece a sacrificial layer with etch selectivity to the underlying silicon substrate;
• C. patterning the sacrificial layer into a patterned sacrificial layer including the form of an emitter stripe and a mask for subsequent deposition of the polysilicon base conductive layer;
• D. implanting a link region using the patterned sacrificial layer as a self-aligned implant barrier;
• E. forming sidewall spacers on the walls of the patterned sacrificial layer;
• F. depositing a polysilicon base conductive layer using the patterned sacrificial layer as a mask;
• G. planarizing the workpiece to remove the polysilicon base conductive layer overlying the patterned sacrificial layer;
• H. forming a dielectric layer on the polysilicon base conductive layer;
• I. removing the patterned sacrificial layer and implanting the base in the substrate;
• and
• J. forming the polysilicon emitter contact.