Patent ID: 6440810
Filing Date: 2002-08-27
Classification: H01L

Abstract:
In the fabrication of a silicon bipolar transistor, a method for forming base regions and for opening an emitter window comprising the steps of:providing a silicon substrate with suitable device isolation; forming a first base region in or on top of said substrate; forming a thin layer of oxide on said first base region; forming a layer of silicon on top of said thin oxide layer, said silicon layer is to be a second base region; forming a layer of a dielectric on top of said silicon layer, said dielectric is to isolate base and emitter regions of said transistor; patterning the hereby obtained structure in order to define said emitter window; etching said structure inside said defined emitter window area and through said dielectric and silicon layers, wherein said thin oxide layer is used as etch stop, thus forming said emitter window; and subsequently heat treating said structure and thus break up said oxide such that said first and second base regions will contact each other.