Thermal Stability of Thin Submicrometer Lines of CoSi2

Abstract

The thermal stability of thin submicrometer lines on Si substrate was investigated using electrical evaluation,in situ transmission electron microscopy observations, Rutherford backscattering, and scanning electron microscopy measurements. Heat‐treatments were performed at temperatures ranging from 800°C up to 1100°C for 10 s in or Ar ambients. It was found that as‐formed silicide was thinner at the edges of features giving rise to an apparent difference between the electrically equivalent line width and its physical size. The ∼45 nm silicide films started to degrade above 1000°C. Arsenic implantation into the silicide exacerbated its degradation at high temperatures, which resulted in an apparent higher sheet resistance. Narrower lines exhibited a greater relative degradation in resistance than wider ones, and the electrically measured line width decreased after annealing. However, no line width dependence of this line width reduction was observed up to 1000°C for line widths down to 0.45 μm. Pull back of from the edges of submicrometer lines and the formation of islands were observed after annealing at 1000°C for about 300 s. A model was proposed to explain the degradation of submicrometer lines of based on the observed thinner edge phenomenon.