SOLID-PHASE REACTIONS AND CHANGE IN STRESS OF TIN/TI/SI FOR A DIFFUSION BARRIER

Solid phase reactions and change in stress of TiN/Ti/Si which is expected to have a low contact resistance to both n+ and p+ silicon and good adhesion to the Si substrate has been investigated. The TiN layer is a uniform polycrystal on the Si substrate; however, its texture is caused by the textured Ti layer. By annealing at 600°C, Si and N atoms diffuse into the Ti layer which causes a distortion of the Ti lattice and an increase in the sheet resistance. By annealing at a higher temperature, as Ti starts to react with Si, the sheet resistance decreases. The silicidation sequences are the same as the previous results and the kinetics slightly differ. The change in film stress is well explained by these solid phase reactions. A TiN layer has excellent thermal stability in an Al/TiN/Ti/Si system, because TiN does not react with Al, Ti, and Si up to 600°C.