Extendibility of ultra long throw Ti-barriers passivated in nitrogen

A key to minimize cell size in sub-0.2 mum DRAM technology is reliable cont act structures especially in the periphery of DRAMs because most of the amp lifiers are connected by these bitline contacts and there is almost no poss ibility to use redundancy for these structures. The challenges for barrier depositions are: (i) sufficient base coverage at minimized field thickness, (ii) low contact resistance to gate and junctions and (iii) low costs per wafer. Beside ionized PVD approaches [1-3] also conventional non-ionized PV D techniques, in particular long throw, offer a simple and low-cost alterna tive for this special application. Mainly driven by costs and process windo w at CMP (dishing), the barrier should be as thin as possible especially in dual damascene schemes using W as metal. This work discusses long throw technology [4,5] where the target to substra te spacing is increased to increase the proportion of near-normal species a rriving at the wafer. In this study different cooling gases with emphasis o n ULTRA were investigated to prove extendibility related to desirable low r esistive contacts to diffusion areas.