Gettering of Copper in Silicon‐on‐Insulator Structures Formed by Oxygen Ion Implantation

Abstract

Copper is shown to be inadvertently introduced as an impurity during the formation of silicon‐on‐insulator structures by high fluence oxygen implantation. Postimplantation annealing causes the copper to diffuse from the silicon surface through the oxide and be preferentially gettered to dislocations that originate at the oxide‐silicon substrate interface. The concentration of copper in the silicon surface layer is reduced by a factor of two, and no copper remains in the buried oxide layer. Sufficient gettering occurs for the fabrication of fully functional n‐channel metal‐oxide‐semiconductor field‐effect‐transistors, with, however, a low yield. Also, the effective carrier mobility in the inversion layer of the transistors is severely degraded, and this is attributed primarily to copper retained in that layer.