In situ estimation of blanket polish rates and wafer-to-wafer variation

Presents a scheme for extracting information from interferometry signals off patterned wafer polish during nonendpointed chemical-mechanical polishing (CMP). This enables one to obtain blanket removal rates immediately after a patterned wafer finishes polishing as well as estimate post-polish within lot thickness variation. A nonlinear regression algorithm is presented that enables one to estimate this information from less than a full interferometry trace cycle and with a lower sampling rate compared to peak-valley detection schemes.