Nanoscale effect on the formation of the amorphous Ni silicide by rapid thermal annealing from crystalline and pre-amorphized silicon

The Ni monosilicide alloyed with Pt is widely used as contact material in advanced microelectronics devices and a good knowledge of silicide formation kinetics is required for the process control. In this work, the nature, and the growth kinetics of the first silicide obtained during the solid-state reaction between the Ni0.9Pt0.1 and the Si are studied for different pre amorphization implant (PAI) conditions as well as for a reference sample without PAI. Reactions between a 10 nm thick Ni0.9Pt0.1 film and Si (100) substrate are analyzed after several rapid thermal anneals (RTA). The nature of the first silicide is determined by Fourier Transform of TEM images and by chemical TEM-EDX analyses. The silicide growth behavior is determined by measuring the silicide thickness by X ray reflectivity (XRR) after the partial reaction induced by RTAs at different temperatures and times. To determine the growth law, the linear parabolic model is first considered but a nonlinear reactive diffusion model must be developed to accurately reproduce the experimental results. From this model, the effective diffusion coefficient as well as its activation energy were determined for the three samples with PAI and the reference sample without PAI. The influence of the driving force on the nonlinear diffusion for thin films is proved, and the impact of the amorphous substrate on the kinetics parameters is quantified and compared to the literature.