Bipolar vertical transistors in monolithic integrated circuit - are made using dopant masks for forming base and transistor zones

摘要

A monocrystalline semiconductor substrate is coated with a layer of an inorganic insulating material contg. dopant windows so dopant masks are obtd. for forming a base zone and a transistor zone which surrounds the former zone (B). Windows have a rectangular shape, and form two dopant masks where at least some of the rectangular exposed zones of the substrate have the same side dimension. One pref. process uses a mask of SiO2 with dopant windows which can be partly covered by a layer of siO2 which is subsequently removed, i.e. so windows of different area can be employed in a sequence of doping operation. Used in the mfr. of integrated injection logic or merged transistor logic circuits with a space saving of e.g. 60% w.r.t. conventional devices.