Comparison of PECVD-WN/sub x/ and CVD-TiN films for the upper electrode of Ta/sub 2/O/sub 5/ capacitors

The electrical characteristics of PECVD-WN/sub x/ and CVD-TiN films as the upper electrode for Ta/sub 2/O/sub 5/ capacitors were compared in a 3D stack structure. In terms of step coverage, CVD-TiN shows excellent results of about 90% at the stack structure corner, but PECVD-WN/sub x/ only reaches about 50%. However, WN/sub x/ electrodes at even 100 /spl Aring/-thickness exhibit equivalent capacitance and leakage current when compared with 150 /spl Aring/-thick CVD-TiN electrodes. It is demonstrated that both PECVD-WN/sub x/ and CVD-TiN are good candidates for the upper electrodes of Ta/sub 2/O/sub 5/ capacitors for ULSI DRAMs.