Low temperature metal-organic chemical vapor deposition of advanced barrier layers for the microelectronics industry

Abstract

Metal-organic chemical vapor deposition (MOCVD) of TiN thin films at low temperatures and low pressures using tetrakis(diethylamino) Ti (TDEAT) and NH 3 is described. Conformal TiN films, having layer resistivities of less than 200 μΩcm, 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 NH 3 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NH 3 and TDEATNH 3 chemistries and the properties of the resulting films is made. It is found that the more reactive TDMATNH 3 chemistry produces non-conformal films having a higher resistivity (>1200 micro ohm 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.