International Business Machines Corporation

Hitendra N Ghosh

Madhukar L Joshi

Wolfgang Alfred Westdorp

Tsu-Hsing Yeh

Ashok Murgai

An improved method of growing silicon crystals by the Czochralski method to obtain a desired oxygen concentration level with both axial and radial uniformity. A crucible is located within a heater to achieve a given temperature profile which is related to the oxygen concentration, and then raised and rotated at an increasing speed together with a high crystal rotation rate to achieve the uniformity.

Method of controlling oxygen content and distribution in grown silicon

A substantially square N-type impurity distribution profile in a silicon substrate produces much superior dc and ac characteristics in PN junction devices than can be expected from the usual phosphorus distribution profile. Such a square profile is obtained by diffusion of arsenic in the silicon substrate. The sharper impurity gradient allows a relatively low surface concentration to be used for the device. This lower surface concentration relieves precipitation and dislocation problems.

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Poughkeepsie, NY, United States of America

Hitendra N Ghosh