In-Situ Friction and Pad Topography Measurements During CMP

Abstract

Duel Emission Laser Induced Fluorescence (DELIF) and friction measurements are taken in-situ during CMP to observe slurry flow beneath a model of an integrated circuit (IC) wafer. Friction measurements average around 7.5 lb and multiple frequencies are observed. Slurry film thicknesses on the order of a 10±3µm were observed during CMP of a flat wafer. The film thickness seems uncorrelated to friction measurements except when the pad and wafer rotation speeds are significantly slowed. DELIF has also accurately measured a 9µm etched step, with noise in the image equal to ±3 µm.

Impact of Pad–Wafer Contact Area in Chemical Mechanical Polishing

“…[15][16][17][18][19][20] Chemical properties were characterized using Fourier transform infrared ͑FTIR͒ spectroscopy, pad stress nonuniformity with scanning ultrasound transmission testing, pad coefficient of friction by various noncommercial instruments, and slurry transport by pad using dual emission laser induced fluorescence. 14,16,[21][22][23][24][25] Pad properties were reported as a function of temperature, soaking time in various solutions, and conditioning treatments. 10,15,[26][27][28][29][30] Different pad types were tested to optimize the removal rate and planarizability for various CMP processes.…”