Conformal Chemical Vapor Deposition TiN(111) Film Formation as an Underlayer of Al for Highly Reliable Interconnects

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Abstract
Chemical vapor deposition (CVD) TiN film having the (111) preferred orientation and conformal step coverage was developed for the first time. The key processes are predeposition of the Ti(002) layer before the CVD TiN film deposition and optimization of the flow rate of reactants: TiCl4, NH3 and H2. Growth of (111) crystal plane seems to be induced due to the lattice matching of crystal plane of the Ti film. On the other hand, conformal step coverage is obtained by using a lower flow rate of NH3, resulting in the surface-limited chemical reaction. It was also demonstrated that both sputtering and CVD Al, deposited on the CVD TiN having stronger (111) orientation, showed stronger (111) orientation which is advantageous for obtaining high electromigration (EM) resistance. Furthermore, simultaneous contact hole filling and interconnects formation using CVD Al/CVD TiN stacked film are successfully demonstrated.