Low‐temperature reaction in tungsten layers deposited on Si(100) substrates

Tungsten layers have been evaporated with an electron gun under ultrahigh vacuum conditions on atomically clean Si(100) substrates. The metallic films deposited on substrates at room temperature are mostly in the body‐centered‐cubic α phase of tungsten. Upon annealing at 400 °C, the bulk of the layer stays unreacted but we have observed the appearance of cracks in the metallic film and the segregation of silicon atoms at the surface. These atoms are not in the form of crystalline WSi2.