Full Profile CMP Metrology SFR Workshop November 8, 2000 Runzi Chang, Costas Spanos Berkeley, CA 2001 GOAL: Develop periodic grating metrology to support integrated CMP model (with Dornfeld and Talbot) 11/8/2000

Motivation CMP is an enabling technology for the semiconductor industry in its drive toward gigabit chips and sub-180nm feature sizes Non-uniformity problems on patterned wafers Depth of focus problem on lithography High resistance interconnect degrades circuit performance The first principal model can help optimize the operation of CMP and drive the technology further in the long run 11/8/2000

Key idea Oxide Substrate Use Scatterometry to monitor the profile evolution The results can be used for better CMP modeling 11/8/2000

Mask Design The size of the metrology cell is 250m by 250m 2m pitch with 50% pattern density 11/8/2000

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. 11/8/2000

Current Status Done mask design and processing in the Lab, some proof-of concept wafers are ready to polish Before the characterization experiments, we would like to know Is the scattermeter signal sensitive to the profile evolution? Answer: yes. How does the initial profile look like? LEO (SEM) can give a cross section view (we need to cut the wafer, then can’t do CMP on this wafer anymore!) AFM can give a smooth profile (but it needs some calibration) 11/8/2000

Comparison of LEO and AFM measurements They are similar except that the height from LEO is smaller due to some tilt at the measurement We’re calling help for a well calibrated AFM 11/8/2000

Next Step Do measurements using Sopra for the initial structures, compare results with the AFM measurements Build an electromagnetic response library Design experiments, polish finished wafers and do scatterometry measurements Collect AFM measurements in order to refine the library 11/8/2000

2002 and 2003 Goals Integrate initial chemical models into basic CMP model; Validate predicted pattern development (with Dornfeld and Talbot), by 8/31/2002. Develop comprehensive chemical and mechanical model (with Dornfeld and Talbot); Perform experimental and metrological validation , by 8/31/2003. 11/8/2000