International Business Machines Corporation

William A Edel

Joseph Regh

A method of making an integrated circuit wherein a subcollector diffusion mask is formed on a semiconductor wafer. A principal impurity of a predetermined conductivity type is then diffused through windows in the mask and into the wafer to form subcollector regions spaced from each other. A compensating impurity of a conductivity type opposite that of the principal impurity is then diffused through the same mask windows into the subcollector regions to a relatively shallow depth. An epitaxial layer is then grown on the wafer during which an amount of the principal impurity diffuses from the subcollector regions into the gas and then into the epitaxial layer and the wafer in areas thereof exterior to the peripheries of the subcollector regions thereby resulting in an autodoping effect. However, the compensating impurity simultaneously diffuses into the exterior areas so as to compensate approximately for the principal impurity and thereby to counteract the autodoping effect of the principal impurity.

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Poughkeepsie, NY, United States of America

William A Edel