Contact TiSi2and Barrier TiN Layers for ULSI Multilevel Metallization

TiSi₂and TiN thin films are deposited with the surface-diffusion reactions of titanium with silicon and nitrogen, respectively. It is demonstrated that the deposition of a TiSi_1.3alloy onto an Si substrate heated to 675°C produces a low-resistivity TiSi₂film. At the same time, a silicide film forms on SiO₂. This film can be distinguished from the disilicide on Si for the purpose of total selective etching. Special process conditions are determined for the fabrication of homogeneous polycrystalline TiN films with a columnar structure and low resistivity (25–35 cm)     

Phase Formation during the Surface-Diffusion Growth of Ti–Co–Si–N and Ti–Co–N Thin Films on Si and SiO2

The kinetics of phase formation in Ti–Co–Si–N and Ti–Co–N thin films on Si and SiO₂is investigated experimentally. With the deposition on Si, rapid thermal annealing (T 900°C) is shown to cause phase separation that ends in a TiN/CoSi₂/Si structure. If SiO₂is used, the alloy reacts with the substrate to produce compounds that are difficult to remove with selective etchants. This limits the potential uses of this process in the fabrication of contact systems for CMOS devices. It is shown that structure- and phase-dissimilar films can be formed on Si and SiO₂by means of the surface-diffusion reactions between a Ti–Co–Si–N or Ti–Co–N alloy and the substrate at 650–700°C. The effect of a TiN, Ti, or CoSi₂thin layer at the alloy–substrate interface on the phase separation is investigated.