STRUCTURAL INTEGRITY AND THERMAL-STABILITY OF TIN/COSI2 USED AS LOCAL INTERCONNECT IN A SELF-ALIGNED COSI2 PROCESS

The TiN/CoSi2/Si structure is of interest for local interconnect applications on Si integrated circuits. The thermal stability of this structure at 850-degrees-C is explored for the case where the TiN layer is formed by reactive ion sputtering or by thermal nitridation of a deposited Ti layer. The stability of a Ti/CoSi2/Si structure at 850-degrees-C also is investigated. AES, thin-film XRD, and cross-sectional TEM are employed to identify the nitridation and interface reaction products, their structure and composition, phase sequence and layer morphology. It is found that un-nitrided Ti reacts with both the CoSi2 and the underlying Si. The XRD data suggest the formation of TiSi2 and the intermetallic Co2Ti compound.