Characterization of Wafer-Bonded Oxide-Free Silicon with Surfaces Treated with an Ion-Bombardment Procedure

Abstract

Oxide-free silicon surfaces were obtained using a high-vacuum wafer-bonding system by bombarding silicon wafer surfaces with argon ions. Wafers were subsequently bonded after the ion treatment. Both single wafers and bonded wafers were characterized. The results of argon ions with ion energies varying over one order of magnitude (from a factor of 0.5 to 5 of a baseline energy E0) are presented in this study. It is found that the resulting damage layer thickness increases with increasing ion energy but the layer density is ion-energy independent, which was about 80% of bulk crystalline silicon density. Annealing the bonded samples at 450 °C for short times reduces and for longer times, eliminates the damaged layer at the bonded interface.