Effects of nitrogen ion implantation on the formation of nickel silicide contacts on shallow junctions

The effects of nitrogen ion implantation on the formation of nickel silicid e contacts on shallow junctions have been investigated. The phase formation of nickel silicides on nitrogen implanted (001)Si was suppressed and shift ed to a higher temperature compared to samples not implanted with nitrogen. The sheet resistance was found to be nearly constant in a wide range of te mperature in nitrogen ion implanted samples. It indicates that low-resistiv ity NiSi is the dominant phase for the 1 x 10(15) N+/cm(2) implanted sample s annealed at 400-750 degrees C and for the 2 x 10(15) N-2(+)/cm(2) implant ed samples annealed at 400-800 degrees C. The diffusion of nickel atoms is thought to be retarded by the presence of nitrogen atoms. The presence of n itrogen ion can also improve the thermal stability of nickel disilicide. Th e effects of nitrogen on nickel silicide formation become more pronounced w ith an increase in the nitrogen dose up to a certain value. (C) 1999 Elsevi er Science S.A. All rights reserved.