Engineering crystallinity of atomic layer deposited gate stacks containing ultrathin HfO2 and a Ti-based metal gate: Effects of postmetal gate anneal and integration schemes

In this study, the authors examined the effects of different annealing schemes on crystallinity in atomic layer deposition (ALD) grown Ti-containing metal gates and ultrathin ALD HfO2 high-k dielectric layers, and corresponding electrical results in metal oxide semiconductor capacitor (MOSCAP) devices. The authors investigated the effect of a postmetal deposition anneal (PMA) on the underlying HfO2, which was deposited using either a standard ALD process or a process which utilized a cyclical deposition and annealing scheme (termed DADA). The effect of the starting substrate surface, either chemically grown SiO2 or H-terminated Si, on HfO2 crystallinity was also studied. For 40 cycle ALD HfO2 (∼32 A) with a TiN overlayer, a transition from an amorphous state to a cubic phase was observed with the application of a PMA treatment. Evidence of the orthorhombic phase of HfO2 with some level of texturing was observed for 40 cycle DADA processed films annealed with a TiN cap. Concomitantly a cubic (111) texture ...