1. 3rd Annual SFR Workshop & Review, May 24, 2001
8:30 – 9:00 Research and Educational Objectives / Spanos
9:00 – 9:45 CMP / Doyle, Dornfeld, Talbot, Spanos
9:45 – 10:30 Plasma & Diffusion / Graves, Lieberman, Cheung, Haller
10:30 – 10:45 break
10:45 – 12:00 Poster Session / Education, CMP, Plasma, Diffusion
12:00 – 1:00 lunch
1:00 – 1:45 Lithography / Spanos, Neureuther, Bokor
1:45 – 2:30 Sensors & Controls /Aydil, Poolla, Smith, Dunn, Cheung, Spanos
2:30 – 2:45 Break
2:40 – 4:30 Poster Session / all subjects
3:30 – 4:30 Steering Committee Meeting in room 373 Soda
4:30 – 5:30 Feedback Session
3rd Annual SFR Workshop & Review, May 24, 2001

2. Costas Spanos, Jeffrey Bokor
Lithography
SFR Workshop
May 24, 2001
Costas Spanos, Jeffrey Bokor
Andy Neureuther
Berkeley, CA
5/24/2001

3. Outline
Sensitivity of Spectroscopic Scatterometry: Sub-100nm Technology
Process Monitoring and Optimization Using Simulation and Full-profile Metrology
Effects of Line-Edge Roughness on MOSFET Electrical Behavior
DUV ASML 5500/90 Stepper for Novel Lithography
Automated Characterization of Optical Image Quality
Methodology for rapid and accurate simulation of alternating PSM
Resist Resolution Enhancement and Line-end Shortening Simulation
5/24/2001

4. Which part of the spectrum contains the most information?
Sensitivity of Spectroscopic Scatterometry: Sub-100nm Technology
EM Response Variations
Tan Y
Simulations for variation in parameter X
[X(-),X(Nominal), X(+)]
Profile Parameters
Lambda
Cos D
Are Variations Detectable?
Lambda
NoYes
Commercial Equipment Analysis
Determine Noise Contributions
Tan Y, Cos D Noise Spectrum
Which part of the spectrum contains the most information?
5/24/2001

5. Signal-to-Noise Ratio for SOPRA Ellipsometer
Intensity fluctuation is the main contributor of measurement noise in ellipsometers.
Monte-Carlo simulations incorporating intensity fluctuations are used to determine the final distributions of Tan Y and Cos D.
The ‘Minimum Detectable Variation’ lines represent the sum of the 3s errors of each of the 2 profiles measured to obtain the variation.
The graphs demonstrate a trend toward significant information contained in a narrow band in the lower wavelength spectrum.
Signal averaged over 30 measurements
Noise represents 1s standard deviation for each wavelength
Empirical formula for signal-to-noise ratio:
Noise = 0.412(Intensity)0.632
(R2 Value = 0.937)
5/24/2001

6. Detectable (Above yellow line) Undetectable (Below yellow line)
70nm Technology Simulations
70nm Dense Lines (ASIC)
45nm Isolated Lines (MPU)
Detectable (Above yellow line)
Undetectable (Below yellow line)
5/24/2001

7. Detectable (Above yellow line) Undetectable (Below yellow line)
50nm Technology Simulations
50nm Dense Lines (ASIC)
30nm Isolated Lines (MPU)
Detectable (Above yellow line)
Undetectable (Below yellow line)
5/24/2001

8. Scatterometry Milestones
Characterize the capabilities of scatterometry in fulfilling the needs of the 100nm technology node, by 9/31/2001- Done!
Feasibility of 100nm profile extraction using small footprint, in-line spectroscopic ellipsometry, by 9/31/2002
Lithography controller that merges full profile in-line information with available metrology, by 9/31/2003
5/24/2001

9. Process Monitoring and Optimization Using Simulation and Full-profile Metrology
Profile Diagnostics
DUV Photolithography
PR Deposition, Focus, Exposure, Bake Time, Development Time, etc
Process Flow
In-Line Scatterometry
Wafers
Feedback Control Loop
5/24/2001

10. The Lithography Control Framework Using Scatterometry
Noise
Noise
Control parameter
Patterned wafer
Lithography
module
Ellipsometer
+/-
Adjusted
offset
Measured spectrum
Feedback
controller
Measured profile
Control param.
extractor
Scatterometry
library
Extracted
control parameters
5/24/2001

11. The Simulation Framework For Process Control Using Scatterometry
Noise
Control parameter
Patterned wafer
Prolith process
simulator
Grating response
simulator
+/-
+/-
Adjusted
offset
Measured spectrum
Feedback
controller
Measured profile
Control param.
extractor
Scatterometry
library
Extracted
control parameters
5/24/2001

12. Structure, Profiles and Spectrum:
Process Simulation and Scatter Predictions match well
480 nm
160 nm
Resist 505 nm
ARC 61 nm
5/24/2001

13. Parameter Disturbance Emulating Process Drift
First order integrated moving average disturbance model ( = 0.3)
5/24/2001

14. Extracted vs. Input Focus and Exposure Settings: Full Profile Extraction detects process inputs
Standard deviation of detection error: m (focus), 0.23 mJ/cm2 (exposure)
5/24/2001

15. CD and Sidewall Angle Variation
No control
CD only
Full profile
Bottom CD (m)
8.9
4.5
3.4
Sidewall angle (degree)
0.35
0.23
0.14
5/24/2001

16. Control Conclusions and Future Work
Focus and exposure drifts can be monitored with scatterometry.
CD and sidewall angle variations are reduced by feedback control of focus and exposure according to simulation.
Next:
Study the effect of noise and modeling deficiencies on control results.
Study the case of multi-wafer delay between metrology and control.
Original Milestones:
Simulator tuning for full profile matching over a range of focus and exposure conditions, by 9/30/2002 (on target)
Simulator tuning for full statistical profile matching over a range of conditions, by 9/30/2002.
Implement lithography controller that merges full profile in-line information with available metrology, by 9/30/2003.
5/24/2001

17. Effects of Line-Edge Roughness on MOSFET Electrical Behavior
SFR Workshop
November 8, 2000
Shiying Xiong, J. Bokor
EECS of UC-Berkeley
Qi Xiang, Philip Fisher
AMD Strategic Technology Group
5/24/2001

18. Motivation
Several possible LER effects have been predicted from device simulations
Increase of leakage and driving current
Variation of Vt
Effect on lateral diffusion and doping profile (high frequency effect)
An efficient way to determine these effects in advanced MOSFETs has not been established
Experimental data from devices with different LER needs to be obtained to make a meaningful comparison with simulation results
5/24/2001

19. Motivation
Several possible LER effects have been predicted from device simulations
Increase of leakage and drive current
Variation of Vt
Effect on lateral diffusion and doping profile (high frequency effect)
An efficient way to determine these effects in advanced MOSFETs has not been established
Experimental data from devices with different LER needs to be obtained to make a meaningful comparison with simulation results
5/24/2001

20. LER Experiments with AMD
Characterize LER on AMD wafers and develop ways to vary LER
We have developed methods to measure and characterize LER
AMD results so far has not given reliable increase of LER
Need to work harder to increase LER for the study purpose
Simulate LER effect on AMD device using our method – DONE!
AMD fabricates devices with different LER values
Comparison of experimental data with simulation results
5/24/2001

21. Simulation of LER Effect on AMD 50nm Technology
5/24/2001

22. Summary Milestones Poly line width RMS on AMD wafers: 1.5nm~4.5nm
Roughness correlation length, Lc is generally greater than 25nm
HF LER effects are insignificant
Our simulations suggest that the AMD prospective 50nm technology is insensitive the typical LER produced in their process.
We need to produce LER with 4-6nm RMS to test our model
Milestones
AMD will fab devices with controlled roughness in this June
Shiying will perform device characterization and comparison with simulation (Fall ’01)
5/24/2001

23. DUV ASML 5500/90 Stepper for Novel Lithography
SFR Workshop
May 24, 2001
SFR:Andrew R. Neureuther, Mosong Cheng, Haolin Zhang
SRC/DARPA Garth Robins, Mike Williamson, Lei Yuan
Microlab: Sia Parsa, Kim Chan, Evan Stateler, Bob Hamilton
MEMS: Sunil Behave, Richard Yeh
Berkeley, CA
2001 GOAL: Complete initial simulations and experiments sufficient to design polarization masks and multi-parameter test structures 9/30/2001 (On Target: tool installed).
5/24/2001

24. (including unanticipated costs of $75K)
ASML 5500/90 Tool and Track
Light path
Mask Port
Donated/installed by ASML with Cymer laser support
(including unanticipated costs of $75K)
Operational May 4, 2001 with 0.25 mm images
Some track issues being resolved
5/24/2001

25. Special Test Mask and First Wafer
Running UCB Mann 3600 and Photo Sciences versions
LER Determination
Test Mask
Electrical Test
Double Exposure
Gratings
Aberration
Targets
Basic Resolution
5/24/2001

26. 2002 and 2003 Goals Aberration Targets Flexible Illumination
Polarization orthogonal spillover
Phase-shifted spillover
Polarization adjusted half-tone
Fly’s eye
Hexagonal light pipe
Slit for apodizing
Aberration
Targets
Flexible Illumination
Conduct and quantitatively interpret polarization masks, and multi-parameter test structures, by 9/30/2002.
Define apparatus, specify testing procedures, and interpret data for polarization masks, and multi-parameter test structures, by 9/30/2003.
5/24/2001

27. Automated Characterization of Optical Image Quality
Programmed-Probe Based Aberration Targets
Dark Field Patterns
Grid is 0.1 l/NA
Probe
Astigmatism
ARN on SMART Garth Robins on SRC/DARPA
Spherical
1 at 90o
Trefoil
Coma
1 at 180o
1 at 0o
2001 GOAL: Complete initial simulations and experiments sufficient to design polarization masks and multi-parameter test structures 9/30/2001. (On Target: Thy, Sim done, Exp in progress)
5/24/2001

28. Model for Aberration Target Design and Measurement
Huygen’s Principle and the Fraunhofer (far field) give
(x,y) are wafer and (r,q) are lens pupil coordinates
Assuming mask diffracted fields are Zernike’s gives
Mask targets are inverse Fourier transform of Zernike’s
E-field and Intensity at target center of
Additive term proportional to the aberration level and quality of the target.
Ideal Probe
5/24/2001

29. Ideal Target Examples: Rotationally Symmetric
Defocus (Z3)
Spherical (Z8)
Null on-axis
Radius of peak is 0.54 l/NA
Radius of peak is 0.84 l/NA
5/24/2001

30. Novel Targets to Distinguish Defocus and Spherical
0.1 wave defocus
0.03
Z8 and Z15
5/24/2001

31. 2002 and 2003 Goals Aberration Targets Measure with CD SEM
Polarization orthogonal spillover
Phase-shifted spillover
Polarization adjusted half-tone
Electrical Test
Haolin Zhang and Costas Spanos
Garth Robins on SMART
Conduct and quantitatively interpret polarization masks, and multi-parameter test structures, by 9/30/2002.
Define apparatus, specify testing procedures, and interpret data for polarization masks, and multi-parameter test structures, by 9/30/2003.
5/24/2001

32. Modeling and Simulation (Mask): Methodology for rapid and accurate simulation of alternating PSM
Kostas Adam
100 nm feature with 180 opening
193 nm, NA = , s =0.3, 4X
k-1 k0
k+1
By adjusting the complex diffracted orders the thin mask within the NA of the objective is better than 0.5%!
Adam SPIE 4346
2001 GOAL: to demonstrate accuracy and generality of simulation method for application to other mask technologies by 9/30/2001. (Done and pursuing further enhancements)
5/24/2001

33. Fast Simulation: 90o/270o contact alt. PSM
CD=150nm(1X), 1:1.5 4 3
270o
90o
Ey (TE)
3mm (4X) 2 1
90o
270o x y
3mm (4X)
The modified mask transmission function is determined independently for the x- and y- directions => f(x,y) = f(x)f(y)
A few (1-4, TE and TM) 2D rigorous EM simulations (~8min)
A full 3D rigorous EM simulation requires many hours
Accuracy 99% at 100X computational speed-up
Adam SPIE 4346
5/24/2001

34. Scatterning from the Phase-Well Corner
After vertical wave subtracted
l=193nm
Ey (TE) 1
n=1
39.7o
n=1.563
Front 2
Sources of cross-talk!
Adam SPIE 4346
5/24/2001

35. 2002-2003 Goals “At Mask” Modeling and Simulation PSM Masks and 3D Defects
Kostas Adam
Extend k-space modeling 3D defects interacting with features and establish defect printability guidelines.
Establish guidelines for 3D defect sizing and feature interactions by 9/30/2002.
Extend defect modeling to relate inspection to printing 9/30/2003.
5/24/2001

36. Novel technologies and Modeling and Simulation (Wafer): Resist Resolution Enhancement and Line-end Shortening Simulation
Imaging Model
< Base PEB Model
< Tuned PEB Model
Mosong Cheng
2001 GOAL: to investigate the impact of electric-field-enhanced post exposure baking on resist profile; validate resist/lens aberration-based line-end shortening model by 9/30/2001.(On Track)
5/24/2001

37. Electric-Field-Enhanced Post Exposure Bake
Electric-Field-Assisted Top Surface Imaging: a potential solution of resist to enable short-wavelength lithography. Generate acid at the resist surface, induce reaction in bulk resist by EFE-PEB.
EFE-PEB applied to optical exposure.
Invention disclosure filled 4/20/01
Resist E
photoacid
5/24/2001

38. 2002 and 2003 Goals “At Wafer”
Involves “At Wafer” aspects of both task 1.1) Novel Technologies and 1.2) Modeling and Simulation
Mosong Cheng
Investigate the impacts of the applied electric field polarity, frequency and magnitude on post exposure bake on e-beam and DUV exposure tools by 9/30/2002.
Optimize the electric-field-enhanced post exposure baking process by 9/30/2003.
Complete the resist/lens aberrations-based line-end shortening model and validate the simulation in 248nm and 193nm lithography by 9/30/2002.
Enable 3D EM simulation of substrate topography effects by 9/30/2003.
5/24/2001