<title>Recent advances in endpoint and in-line monitoring techniques for chemical-mechanical polishing processes</title>

Abstract

Executive SummaryWe present a summary of the recent advances in endpoint and in-line monitoring techniques for chemical-mechanical polishing (CMP) processes. We discuss the technical challenges and review some of the approaches that have been published and/or patented. These methods include optical, thermal (pad temperature), friction (torque motor current), electrochemical, chemical, electrical, and acoustic (vibration). We also present experimental data obtained in our laboratory using selected endpoint methods for metal and oxide CMP.Extended Abstract In-line monitoring and automatic endpoint of chemical-mechanical polishing (CMP) offers many manufacturing advantages such as improved process yields, reduced product variability, closer conformance to target requirements, and higher throughput. There are many potential payoffs however in-line monitoring and automatic endpoint is difficult to implement due to the nature of the CMP process. Ideally, output specifications such as final planarity, film thickness, and defectivity would be monitored directly in real time. There are a number of technical issues associated with equipment design, sensor performance, rotating machinery, and the harsh slurry environment. Currently, on-line metrology equipment that is integrated into the polishing tool is an attractive option for improving throughput while maintaining good quality control.

Correlating Shear Force and Coefficient of Friction to Platen Motor Current in Copper, Cobalt, and Shallow Trench Isolation Chemical Mechanical Planarization at Steady-State Conditions

“…[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] The most popular of such methods measures the carrier or the platen motor current (CMC or PMC). [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] During polishings, both wafer and platen rotate at desired velocity setpoints. The pad-slurry-wafer interface undergoes a myriad of 3-body interactions which, due to the frictional forces involved, may facilitate or resist the platen and wafer rotation.…”

Correlating Shear Force and Coefficient of Friction to Platen Motor Current in Copper, Cobalt, and Shallow Trench Isolation Chemical Mechanical Planarization at Highly Non-Steady-State Conditions

“…[29][30][31][32][33][34][35][36][37][38][39] The most popular of such alternate methods is centered around measuring the carrier, or the platen, motor current (CMC, or PMC). [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] During CMP, the wafer and the platen co-rotate at desired velocity setpoints. The pad-slurry-wafer interface undergoes a myriad of 3-body interactions which, due to the frictional forces involved, may facilitate or resist platen and wafer rotation.…”

Real-Time Shear and Normal Force Trends in Tungsten Chemical Mechanical Planarization with Different Conditioning Discs

“…Carrier head motor current measurements, sometimes combined with the Hall Effect, correspond to instantaneous changes in friction at the interface. 6 Another method relies on a displacement sensor attached to the shaft that rotates the wafer carrier. One study found a principal vibration mode of their polisher, and that the RR of oxide correlated to shear force intensity without significant change in COF.…”