New trends in CVD metallization for ULSI

This paper reports on advances in blanket and selective deposition of metals and silicides using CVD techniques that have stimulated interest in this approach for meeting requirements for high aspect ration vias and contacts for 4M bit and 16M bit DRAM devices. Most U.S. semiconductor manufacturers have developed CVD tungsten processes for current and 2-5 year time frame needs and are showing interest in selective CVD copper techniques for the longer term. The importance of in-situ cleaning, by plasma etching or vapor phase HF cleaning, has been recognized in achieving low contact resistance and good selectivity. A review of the current status of these developments and a discussion of future trends are presented