Optimization of key process parameters for cobalt sputtering in 0.11  <i>μ</i> m CMOS devices

This study systematically investigates the effects of cobalt (Co) film thickness, pretreatment conditions, and radio frequency (RF) bias power on the formation of CoSi2 films and the corresponding device performance in 0.11 μm CMOS technology. The results indicate that a Co thickness of 9 nm is optimal; deviations from this value lead to abnormal contact resistance variations and yield loss. The interface quality is optimal when using argon plasma bombardment to remove an oxide layer thickness (i.e., the pretreatment thickness) of 3 nm. Thicknesses exceeding 4 nm can damage the silicon lattice, leading to leakage fluctuations and reduced yield (yield is only 83% at 6 nm). When the RF bias power is 200 W, it is the optimal condition compared with 140 and 260 W. Additionally, the queue time (Q-time) between wet preclean and Co deposition must be controlled within 4 h; extending to 8 h increases leakage current by 25% and reduces yield to 91%. The optimized Co deposition parameters provide a reliable process window for industrial manufacturing.