Abstract: 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.

Abstract: A semiconductor device is described that operates as an improved junction field effect transistor (JFET). A bipolar transistor with a collector region, a base region, an emitter region, a first base contact, and a second base contact insulated from the first base contact, has the base region lightly doped to about a 1E16 to 5E17 atoms/cm3 doping level. A connection is provided between the emitter region and the collector region to act as a JFET gate contact for the bipolar transistor. The semiconductor device operates as an improved JFET with the first base contact being a drain contact and the second base contact being a source contact. A method for manufacture of an improved JFET on a chip containing conventional bipolar devices is also described. The improved JFET is shown being used with a write head in a disk drive system for providing electrostatic discharge protection.