Bipolar Junction Transistor with a Reduced Collector-Substrate Capacitance

A process for forming a bipolar junction transistor (BJT) in a semiconductor substrate and a BJT formed according to the process. A buried isolation region is formed underlying BJT structures to isolate the BJT structures from the p-type semi-conductor substrate. To reduce capacitance between a BJT subcollector and the buried isolation region, prior to implanting the subcollector spaced-apart structures are formed on a surface of the substrate. The subcollector is formed by implanting ions through the spaced-apart structures and through a region intermediate the spaced-apart structures. The formed BJT subcollector therefore comprises a body portion and end portions extending therefrom, with the end portions disposed at a shallower depth than the body portion, since the ions implanting the end portions must pass through the spaced-apart structures. The shallower depth of the end portions reduces the capacitance.