The diffusion coefficient of As in 260nm-thick polycrystalline Ni2Si layers was

measured both in grains and in grain boundaries. As was implanted in Ni2Si layers

prepared via the reaction between a Si layer and a Ni layer deposited by magnetron

sputtering on a (100) Si substrate covered with a SiO2 film. The As concentration profiles in the samples were measured using secondary ion mass spectroscopy

before and after annealing (400 to 700C). The diffusion coefficients in the grains

and the grain boundaries were determined using two-dimensional finite element

simulations based on the Fisher model geometry. For short-term annealing (1h) at

below 600C, lattice diffusion was not observed. However, grain boundary diffusion

was observed at as low as 400C. For higher thermal budgets, As diffuses

simultaneously in the volume of the grains and in the grain boundaries. Lattice

diffusion was characterized by a pre-exponential factor of about 0.15cm2/s and an

activation energy of about 2.72eV. In the case of grain boundary diffusion, the

triple product of the As segregation coefficient, the grain boundary width and the

diffusion coefficient was found to be given by:

sδDGB (cm3/s) = 9.0 x 10−3 exp[−3.07(eV)/kT]

Lattice and Grain-Boundary Diffusion of as in Ni2Si. I.Blum, A.Portavoce,

D.Mangelinck, R.Daineche, K.Hoummada, J.L.Lábár, V.Carron, C.Perrin: Journal

of Applied Physics, 2008, 104[11], 114312