Claims
- 1. A method of estimation of blanket polish rates for product wafers comprising the steps of:sensing sample signals representing polishing trace from product wafers and processing said sample signals from product wafers using samples taken near the end of polishing period to get a processed rate estimate.
- 2. The method of claim 1 wherein said end of polishing period is in the planarization region.
- 3. The method of claim 1 wherein said sensing includes an interferometer.
- 4. The method of claim 3 wherein said processing step includes calculating estimates using sample signals from less than a full interferometry trace cycle.
- 5. The method of claim 4 wherein said processing step includes calculating estimates using a non-linear regression algorithm and iterative optimization processing.
- 6. The method of claim 5 wherein said processing step includes assuming an initial rate and determining what sinusoidal will give the trace by working backward in time and determining a least mean square fit.
- 7. The method of claim 6 including filtering said rate estimate to remove noise and feeding back to the nonlinear regression algorithm to seed subsequent iterations.
- 8. The method of claim 6 including the step of estimating rate of post-polish metrology to validate estimates and weed out outliers that make it past the fit metric.
- 9. The method of claim 6 including the step of feeding rate estimate fed back to a sampler that identifies the portion of the trace of interest and selecting samples from that portion of the trace for processing.
- 10. The method of claim 1 wherein said samples taken are approximately ¼ wave of samples from the end of the polish trace.
Parent Case Info
This application claims priority under 35 U.S.C. §119(e)(1) of provisional application numbers 60/310,853, filed Aug. 9, 2001 and 60/313,460 filed Aug. 21, 2001.
US Referenced Citations (9)
Non-Patent Literature Citations (4)
Entry |
Ouma et al., “Characterization and Modeling of Oxide Chemical-Mechanical Polishing Using Planarization Lenght and pattern Density Concepts”, IEEE, 2002.* |
Patel et al., “In Situ Estimation of Blanket Polish Rates and Wafer-to-Wafer Variation”, IEEE, 2002.* |
Fang et al., “Control of Dielectric Chemical Mechanical Polishing (CMP) Using an Interferometry Based Endpoint Sensor”,IEEE, 1998.* |
Boning et al., “Run by Run Control of Chemical-Mechnaical Polishing”, IEEE, 1995. |
Provisional Applications (2)
|
Number |
Date |
Country |
|
60/310853 |
Aug 2001 |
US |
|
60/313460 |
Aug 2001 |
US |