THERMAL-STABILITY OF SILICIDE ON POLYCRYSTALLINE SI

The thermal stability of silicide on polycrystalline Si (poly-Si) has been investigated. At elevated temperatures, the silicide/poly-Si laye red structure becomes morphologically unstable, because of the grain g rowth of poly-Si. The driving force for the high temperature instabili ty is the reduction of the grain boundary energy and surface energy of the poly-Si. In situ stress measurement shows that the grain growth i s accompanied by a decrease in the compressive stress of as-deposited poly-Si. A change in crystallographic texture from (110) to (111) is a lso observed during the grain growth, indicating a process similar to that of secondary grain growth. A study of the grain growth kinetics s hows that the grain growth of poly-Si is enhanced by fast diffusion in the silicide, but is not rate limited by the diffusion of the dominan t diffusion species in the silicide. A strong correlation is found bet ween the onset temperature for plastic deformation in the silicide and that of the grain growth in poly-Si.