Reactive ion etching of TiSi2/n+ polysilicon polycide structure for very large scale integrated application

TiSi2 has the lowest resistivity among various refractory metal silicides and a low forming temperature also. It is considered that TiSi2 would be an important material for the scale above 4M dynamic random access memory integration, it has given rise to universal attention. In this paper, reactive ion etching characteristics of TiSi2/n+ polysilicon polycide structure are investigated in detail, and the probable mechanisms are discussed. The mixture of SF6–Cl2 is chosen as etch gases for TiSi2 polycide patterning. The experimental analysis indicates that the etch rates are dependent on various etching process parameters, such as gas composition, radio frequency power, and gas pressure, the etching profiles are dependent on gas composition. Strict anisotropic etching of TiSi2/n+ polysilicon double layer structure with 0.6 μm linewidth has been achieved by a single-step process. The etch rate ratio of n+ polysilicon to TiSi2 is equal to 1.03 and that of n+ polysilicon to SiO2 is equal to 18. The integrity of resist mask is good. The reproducibility of the process is satisfactory.