1. 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

2. 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

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

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

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.
11/8/2000

6. 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

7. 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

8. 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

9. 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