Crystal Surface Defects and Oxygen Gettering in Thermally Oxidized Bonded SOI Wafers

Abstract

This work investigates the role of interstitial oxygen content in the starting Czochralski bonding wafers, and the effects of buried layered implants and thermal processing on the formation of crystalline defects in the surface of bonded silicon on insulator (SOI) material. We found that unimplanted SOI material originating from Si with high oxygen levels were populated with heavy oxygen precipitation and related crystal defects, and were also characterized by low minority carrier lifetime values. However, a dramatic improvement was observed in the behavior of SOI with low oxygen levels where the development of oxygen precipitation in the SOI layer was inhibited. Incorporation of a buried As ion implanted layer in high oxygen level SOI increased the lifetime of the material and suppressed the formation of oxygen precipitates through an oxygen gettering effect. The gettering efficiency of the buried defect layer was found to be related to the dose of the As ion implantation, the annealing temperature, and type of starting silicon material. A dose of was sufficient for effective gettering. © 2001 The Electrochemical Society. All rights reserved.