Impact of Thermal Properties of Pad Materials on CMP Process Stability

Chemical mechanical planarization (CMP) remains a pivotal step in the fabrication of devices for upcoming technology nodes. The optimal performance of a CMP process hinges on a precise combination of pad, slurry, and pad conditioner. Utilizing engineered pads and cutting-edge slurries proves instrumental in enhancing CMP performance to align with the stringent process demands of advanced technology nodes. This study underscores the indispensable role of thermal stability in CMP pad materials for ensuring process stability. Our research demonstrates that by modifying the thermal properties of CMP pad materials, we successfully mitigated the exponential increase in platen motor torque (indicative of friction) and pad temperature. Additionally, we explore the stability challenges associated with different wafer films such as thermal oxide and TEOS, offering effective solutions to address them. Furthermore, our investigation sheds light on the substantial impact of slurry flow rate on motor torque, emphasizing how the thermal instability of the pad material significantly influences process stability. Notably, we observed a direct correlation between the glass transition temperature of the CMP pad material and the ramp rate of motor torque and pad temperature. These foundational insights are invaluable for the design of advanced CMP pads for meeting the stringent requirements of future technology nodes, providing a comprehensive understanding of the intricate interplay between thermal stability and CMP process performance.