Self-aligned CoSi2 and TiW(N) local interconnect in a submicron CMOS process

Abstract

Abstract The integration aspects of a self-aligned CoSi 2 and TiW(N) local interconnect technology in a submicron CMOS process are described. The effect of substrate type and dope on the final sheet resistance of CoSi 2 has been investigated. A small influence of the dope concentration has been observed on the formation of CoSi, however no significant effect is measured on the sheet resistance of the finally formed CoSi 2 . The CoSi reaction has been found to be very sensitive to the SiCo interface condition. A sacrificial oxidation has proven to be a suitable method to ensure a proper reaction. An electrical testing method is presented, which has shown to be a very sensitive method to detect overgrowth (bridging) in the salicide process. Voltage contrast SEM analysis showed to be suitable to locate overgrowth. The use of the CoSi 2 salicide process did not provoke any serious degradation of transistor performance or gate oxide integrity. The results are comparable with those of TiSi 2 . TiW(N) is reported to be a good material for local interconnect in combination with CoSi 2 . The integration aspects of the TiW(N) local interconnect technology are discussed. The etching process of TiW(N) appears to be the most critical step.