Growth, stability and decomposition of Mg2Si ultra-thin films on Si (100)

Abstract

International audienceUsing Auger Electron Spectroscopy (AES), Scanning Tunneling Microscopy/Spectroscopy (STM/STS) and Low Energy Electron Diffraction (LEED), we report an in-situ study of amorphous magnesium silicide (Mg2Si) ultra-thin films grown by thermally enhanced solid-phase reaction of few Mg monolayers deposited at room temperature (RT) on a Si(100) surface. Silicidation of magnesium films can be achieved in the nanometric thickness range with high chemical purity and a high thermal stability after annealing at 150 °C, before reaching a regime of magnesium desorption for temperatures higher than 350 °C. The thermally enhanced reaction of one Mg monolayer (ML) results in the appearance of Mg2Si nanometric crystallites leaving the silicon surface partially uncovered. For thicker Mg deposition nevertheless, continuous 2D silicide films are formed with a volcano shape surface topography characteristic up to 4 Mg MLs. Due to high reactivity between magnesium and oxygen species, the thermal oxidation process in which a thin Mg2Si film is fully decomposed (0.75 eV band gap) into a magnesium oxide layer (6–8 eV band gap) is also reported

A comprehensive atomistic picture of the as-deposited Ni-Si interface before thermal silicidation process

“…Silicides in microelectronics are formed as a directly integrated material from a silicon substrate, by a solid-state reaction between a metal and the silicon material, forming an alloy compound. Different silicides have been used depending on the technological node and the dimension of the transistor gate associated with smaller and smaller sizes and more and more complex architectures [3,[8][9][10][11][12][13]. Among them, NiSi is one the most promising silicides for the development of new technologies in advanced devices with complex 3D architecture to form high-conductivity nickel silicide/silicon contacts [14].…”