Effects of native oxide removal from silicon substrate and annealing on SiO2 films deposited at 120 °C by plasma enhanced chemical vapor deposition using disilane and nitrous oxide

Abstract

The effects of native oxide removal from the Si substrate surface and annealing on SiO2 films deposited by plasma enhanced chemical vapor deposition at 120 °C using Si2H6 and N2O are investigated. The effective oxide charge and the interface trap densities for the as-deposited films with the native oxide etched off the substrate surface prior to the film deposition were nearly five times higher than for the as-deposited films without the removal of the native oxide. Postdeposition annealing in N2 reduced the effective oxide charges for the films deposited on substrates without the native oxide. However, a 30 min postmetallization anneal at 400 °C in 5% H2 in N2 ambient reduced both the effective oxide charge density and the interface trap density much more effectively. The values for both these charge densities and the dielectric breakdown field were comparable after this postmetallization annealing regardless of the substrate cleaning procedure and the postdeposition annealing cycle in N2.