Ultra-rapid determination of material removal rates based solely on tribological data in chemical mechanical planarization

Single-run Stribeck+ curves are constructed using real-time, high-frequency, shear force and normal force data from the wafer-slurry-pad interface during copper and cobalt (on ILD wafers) CMP in conjunction with multiple slurries, pads and conditioning discs at various pressures and relative velocities. To avoid having to perform actual polishing experiments to obtain blanket film removal rates, “big data” sets from the same Stribeck+ curves are used to construct new “Kinetic” curves to help infer relative blanket wafer removal rates. The “Kinetic” curves, which are based on the assumption that material removal is Prestonian, are eventually validated with actual removal rate studies involving different wafer types processed at various pressures-velocity combinations with the same pads, conditioning discs and slurries. A strong correlation is seen between the actual and “inferred” removal rates which renders credibility to our new ultra-rapid and ultra-low-budget approach for determining removal rates that does not require any wafer polishing nor any film thickness metrology.