Determination of Effective Diffusion Coefficient of Copper in Silicon by Diffusion from Bulk into the Polysilicon Backside

Abstract

The dependence of the effective diffusion coefficient of Cu on boron concentration in p-type silicon at different temperatures has been measured. The quantitative diffusion and gettering of Copper from the bulk into the polysilicon backside have been measured at different temperatures 200 °C, 250 °C, 300 °C and 350 °C, in silicon doped with 1.14x10 1 8 (0.04 Ωcm), 3.24x10 1 8 (0.02 Qcm) and 8.49x10 1 8 (0.01 Qcm) boron atoms/cm 3 . This result has been compared with modeling values calculated by the equation for effective diffusion coefficient reported by A. Istratov et al. We have proposed a simple numerical equation for the calculation of the effective Cu diffusion coefficient for a wide range of boron concentration N a <10 1 9 atoms/cm 3 in silicon. From the results of this study it has been suggested that in the presence of high boron concentrations the gettering mechanism in backside polysilicon is governed by segregation type gettering.