Patent ID: 6436780
Filing Date: 2002-08-20
Classification: H01L

Abstract:
A method of making a semiconductor device having a plurality of vertically oriented bipolar transistors formed in a body of silicon, each transistor having a collector, an emitter and a base positioned between the collector and the emitter, the collectors lying in a common buried plane buried within the body, the emitter of at least one of the transistors being positioned at an outer planar surface of the body, the method comprising the steps of:a) forming a recess in the body below the outer planar surface with a depth by local sacrificial oxidation of the silicon; b) positioning the base of said at least one transistor within the recess; and c) controlling the depth of the recess to vary a characteristic of the device so that a spacing between the base of said at least one transistor and the collector of said at least one transistor at the buried plane is a predetermined value, the spacing being dependent upon the depth of the recess.