Role of local microchemistry and surface structure in electrical resistivity of 50 nm electroless films Ag–W–oxygen

Abstract

We studied electroless 50 nm films Ag (0.2–1.2 at.% W) which contain also some oxygen and were deposited onto SiO 2/Si substrate. The films showed better corrosion resistance and hardness than pure Ag, but rather high electrical resistivity ρ which decayed fast after annealing at T ⩾ 100 °C [Y. Shacham-Diamand, A. Inberg, Y. Sverdlov, N. Croitoru, J. Electrochem. Soc. 147 (2000), 3345–3349; A. Inberg, V. Bogush, N. Croitoru, V. Dubin, Y. Shacham-Diamand, J. Electrochem. Soc. 150 (2003) C285–C291; V. Bogush, E. Ginsburg, A. Inberg, N. Croitoru, V. Dubin, Y. Shacham-Diamand, in: G.W. Ray et al. (Eds.), Advanced Metallization Conference 2003 (AMC 2003), MRS, Warrendale, PA, 2004, pp. 607–611; E.E. Glickman, A. Inberg, V. Bogush, N. Croitoru, Y. Shacham-Diamand, Microelectron. Eng. 70 (2003) 495–500; E.E. Glickman, A. Inberg, V. Bogush, G. Aviram, N. Croitoru, Y. Shacham-Diamand, Microelectron. Eng. 76 (2004) 182–189]. Application of XPS, HRTEM/EELS and HRSEM/EDS made it possible to reveal that open porosity, co-segregation of W and oxygen and formation of non-metallic phases Ag 2W 2O 7 and AgO at the grain/cluster of grains interfaces are the major factors which contributed to high ρ in the as-deposited films. AFM data treated in terms of fractal scaling theory suggest that surface tension driven sintering in the course of annealing at 125 °C is responsible for the resistivity decay, while HRTEM shows that grain size does not change.