Bipolar transistor having lightly doped epitaxial collector region constant in dopant impurity and process of fabrication thereof

摘要

A bipolar transistor has a lightly doped n-type single crystal silicon layer epitaxially grown in a recess formed in a heavily doped n-type impurity region after a selective growth of a thick field oxide layer, a base region, an emitter region and a collector contact region are formed in surface portions of the lightly doped n-type single crystal silicon layer, and the single crystal silicon layer is not affected by the heat during the growth of the thick field oxide layer, and has a flat zone constant in dopant concentration regardless of the thickness thereof.