LOW-TEMPERATURE METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION OF ADVANCED BARRIER LAYERS FOR THE MICROELECTRONICS INDUSTRY

Metal-organic chemical vapor deposition (MOCVD) of TiN thin films at low temperatures and low pressures using tetrakis(diethylamino)Ti (TDEAT) and NH3 is described. Conformal TN films, having layer resistivities of less than 200 muOMEGA cm, densities close to those in sputtered films and low impurity contents can be obtained with this chemistry. These TiN films can be applied as adhesion layers for chemically vapor-deposited W, or as barrier layers between Si and Al. Many papers describe deposition of TiN using tetrakis(dimethylamino)Ti (TDMAT) and NH3 to form TiN, presumably because of the conveniently higher vapor pressure of TDMAT compared with TDEAT. A direct liquid injection system is used here to enable reproducible introduction of both amines in the reactor. A direct comparison between the TDMAT-NH3 and TDEAT-NH3 chemistries and the properties of the resulting films is made. It is found that the more reactive TDMAT-NH3 chemistry produces non-conformal films having a higher resistivity (> 1200 muOMEGA cm) and lower density. Finally, MOCVD of advanced amorphous barrier materials, comprising a ternary Ti-Si-N alloy, is described. Such amorphous ternary barriers are candidates for application in future Cu metallization schemes.