Mechanical stress in coevaporated b-FeSi thin films on silicon 2qÍ substrates

Amorphous thin films of FeSi2qÍ ÍF"0.12.of 310 nm were prepared by simultaneous electron beam evaporation of Si and Fe onto Si-wafers. Mechanical stresses caused by the evaporation process and subsequent annealing up to about 7008C were analyzed by laser-optical substrate curvature measurements. Large tensile film stress is generated due to structural relaxation of the amorphous film material during deposition and annealing up to 4008C. Surprisingly, the crystallization to b-FeSi2 at about 4008C does only induce a very small stress component for ÍF0, but a distinct tensile stress for Í)0. The material densification during the phase transition is mainly translated into film thickness reduction. As no stress relaxation reduces the high tensile stress of 1300–1600 MPa cracking and delamination was observed. q1998 Elsevier Science B.V. All rights reserved