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Enabling Full Profile CMP Metrology and Modeling

Enabling Full Profile CMP Metrology and Modeling. SFR Workshop May 24, 2001 Runzi Chang, Costas Spanos Berkeley, CA. 2001 GOAL: Develop periodic grating metrology to support integrated CMP model by 9/30/2001. Motivation.

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Enabling Full Profile CMP Metrology and Modeling

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  1. Enabling Full Profile CMP Metrology and Modeling SFR Workshop May 24, 2001 Runzi Chang, Costas Spanos Berkeley, CA 2001 GOAL: Develop periodic grating metrology to support integrated CMP model by 9/30/2001.

  2. Motivation • First-principle based modeling can help optimize the operation of CMP and drive the technology further. • The ability to measure profile evolution at various polish stages is a key ingredient in establishing and confirming models. • Formal CMP modeling can the be used to address issues relasted to non-uniformity, pattern loading effects, etc.

  3. Key idea: measure the evolution of a 1-D periodic pattern at various polish stages • Use scatterometry to monitor the profile evolution • The results can be used for better CMP modeling Oxide Substrate

  4. Mask Designed to explore Profile as a function of pattern density • The size of the metrology cell is 250m by 250m • Periodic pattern has 2m pitch with 50% pattern density

  5. Sensitivity of Scatterometry (GTK simulation) • We simulated 1 mm feature size, 2 mm pitch and 500nm initial step height, as it polishes. • The simulation shows that the response difference was fairly strong and detectable.

  6. Characterization Experiments • Three one-minute polishing steps were done using the DOE parameters Initial profiles Sopra/AFM Wafer cleaning Nanospec Thickness measurement CMP Sopra Spectroscopic ellipsometer AFM (AMD/SDC)

  7. C D E A oxide B Substrate Library-based Full-profile CMP Metrology • Five variables were used in describing the oxide profile to generate the response library: bottom oxide height (A), bottom width (B), slope 1 (C), slope 2 (D) and top oxide height (E). Reference: X. Niu, N. Jakatdar, J. Bao, C. Spanos, S. Yedur, “Specular spectroscopic scatterometry in DUV lithography”, Proceedings of the SPIE, vol.3677, pt.1-2, March 1999.

  8. Scatterometry AFM SEM Results • Extracted profiles match SEM pictures with 10nm precision • Scatterometry is non-destructive, faster and produces more descriptive than competing methods.

  9. Conclusions and 2002 / 2003 Goals • We have demonstrated that scatterometry, in conjunction with specialized profile libraries, can be used for complete profile evaluation during polish. • This method has been demonstrated on clean, dry samples. It will be interesting to examine the feasibility of using wet samples, for in-situ/in-line deployment of full-profile CMP metrology. • Our next goals are: • Integrate initial chemical models into basic CMP model; Validate predicted pattern development (with Dornfeld and Talbot), by 9/30/2002. • Develop comprehensive chemical and mechanical model (with Dornfeld and Talbot); Perform experimental and metrological validation, by 9/30/2003.

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