Weir PSFM Weir PSFM Focus uniformity calculations for lens aberrations, stage & scan characterization and reticle-platen tuning Weir PSFM Weir PSFM and the Benchmark PSFM/PSG reticle form a wavefront engineering toolset unique in the industry for • critical focal-plane element analysis, • Tool control calculation, • yield estimation, • behavioral visualization and • automated modeling for capability optimization. TEA Systems Corp. 65 Schlossburg St. Alburtis, PA 18011 610 682 4146 [email protected]
Data Input Any overlay or registration metrologyAutomated input.
Data Storage Microsoft Excel workbooks.
Organization “Open” system with easy access to data and analysis results
Applications Metrology verification and setupReticle verificationExposure tool
setup and analysis of lens, reticle-platen and wafer chuck Lens matching uniformity analysis Sub-system precision calculation focus budget optimization
Process Optimization Error budget analysis Yield estimation
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Agenda
• Weir PSFM Overview
• Data acquisition & setup
• The three modes of operation PSFM & PGM Reticle Calibration Lens aberrations in the “Best Focus” field Fixed Focus analysis
• Wafer and Field Modeling
• Example: Astigmatism and wafer model
• Resolution of topographic steps
• Tool Precision calculation
• Analysis Automation with Weir DM
• Summary
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Weir Data Import• manual data import
Data is selected from the Weir Analysis import screen• Weir can import Binary, ASCII or Excel data formats
The data is stored in an Excel spreadsheet. Weir uses user-defined variable names from the raw data set.
• “Test” numbers correlate to information shown on the “Sites” spreadsheet.
• The information sheet contains additional setup parameters
Therma-Wave Optiprobe CD
Supports any metrology data including overlay, CD, thickness etc.
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Layout optimizer• Provides
Layout fine tuning for centering and parameter updates.
• Point-and-click updates of scan, NA, focus, dose coherence etc.
Basic metrology with statistics and visualization graphics such as histograms, XY-scatter, wafer, field plots, contour and 3D plots
Exposure tool library maintenance and selection
Access to Weir focus, process window and daily monitor modules.
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Operational Modes
• Weir Calibration lens aberrations calibration templates for reticles tuning
Weir Software Suite • PSFM Reticle Patterns
Perform isolated –feature based analysis
• PGM or PSG Patterns Analyze performance for
dense-packed features
• Weir Fixed-Focus Wafer stage
performance Slit & scan
characterization tuning
• Weir DM Calibration, fixed
focus & raw data Trend charts Lot analysis
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Analysis Flow - Reticle Calibration
Import and layout dataImport and layout data
Calibrate the PSFM Reticle
Calibrate the PSFM Reticle
Optional: Calculate the “Best Focus” Aerial Image
response
Optional: Calculate the “Best Focus” Aerial Image
response
Save the calibration
to a Calibration Template
Save the calibration
to a Calibration Template
Reticle CalibrationReticle Calibration/ Template Generation:Perform one-time for a given Reticle and NA/Sigma
Template Library
Templates are needed for each unique Reticle, NA & Sigma value used
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Automated calibration of every site
1. Field object shows site layout
2. Calibration can be restricted by layout variable setup.
3. Set automated range & sigma data culling, press calibrate and every site on the reticle is calibrated.
4. Calibrations are displayed and stored in the spreadsheet.
5. Accuracy (= 193nm) • PSFM < 12 nm focus
• PSFM < 1.5 nm - 3 sigma
12
4
3
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Best Focus – the lens Aerial Image 1. Most accurate calculation of lens aberrations• Piston, Tilt, Astigmatism, Curvature
2. Focus budget:• Astigmatism: 0.034 um
• After tilt & bow are accounted for
• Tilt; loss of 0.019 um• Curvature: 0.017 um
• -9nm in X, +9 nm in Y
• Residuals 0.143 um• Residuals are also contributing to astigmatism.
3. Best Focus Setting• The best focus Tool setting is at –0.042 um.
1. Most accurate calculation of lens aberrations• Piston, Tilt, Astigmatism, Curvature
2. Focus budget:• Astigmatism: 0.034 um
• After tilt & bow are accounted for
• Tilt; loss of 0.019 um• Curvature: 0.017 um
• -9nm in X, +9 nm in Y
• Residuals 0.143 um• Residuals are also contributing to astigmatism.
3. Best Focus Setting• The best focus Tool setting is at –0.042 um.
“What if” Simulations
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Analysis Flow for Fixed Focus
Import and layout dataImport and layout data
Calibrate the PSFM ReticleCalibrate the PSFM Reticle
Optional: Calculate the “Best Focus” Aerial Image
response
Optional: Calculate the “Best Focus” Aerial Image
response
Save the calibration to a
Calibration Template
Save the calibration to a
Calibration Template
Reticle CalibrationReticle Calibration/ Template Generation:Perform one-time for a given Reticle and NA/Sigma
Import and layout dataImport and layout data
Go to Focus uniformity Analysis Window
Go to Focus uniformity Analysis Window
Select the proper
Calibration Template
Select the proper
Calibration Template
Fixed-Focus Fixed-Focus AnalysisAnalysis:Perform daily or as needed.
Select the Conversion
Option. “All-Sites” is
default.
Select the Conversion
Option. “All-Sites” is
default.
Press “(re)Calculate” command button to convert
overlay to Focus
Press “(re)Calculate” command button to convert
overlay to Focus
Optional: select data sub-set of wafer, dose, NA, PC etc
values
Optional: select data sub-set of wafer, dose, NA, PC etc
values
Wafer Graphic will appear to show you the
focus data selected
Wafer Graphic will appear to show you the
focus data selected
Select “Analysis” tab
to continue FOCUS analysis
Select “Analysis” tab
to continue FOCUS analysis
Template Library
Templates are needed for each unique Reticle, NA & Sigma value used
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Fixed Focus: Wafer & Field Modeling • Wier’s Zernike wafer analysis clearly resolves the 10 urad of chuck tilt (shown here as a correction of –10 urad) and 15 urad of reticle tilt.
• Modeled results are stored in the excel spreadsheet along with the data (see below).
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Residuals re-plotted
Slit & scan by column
Slit & scan by column
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Modeled Residuals
plotted by Column
plotted by Rows
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Tool Precision budget
1. Click on the Precision tab to calculate the precision dataset.
1. Values are displayed in “one-sigma” variations.
2. Definitions & method of calculated can be viewed by pressing the F1 key or by going into the help menu.
2. Values in the “Scan” (Y) direction varied more than along the slit (X)
3. Wafer-to-wafer or InterWafer variation is small.
4. InterField variation from stage stepping, leveling and focusing is greater than IntraField, or fixed field variation.
5. Overall lot precision is (64.5, 85.9) nm one-sigma.
6. Results are stored on the “Precision” spreadsheet of the workbook.
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Weir DM: Analysis AutomationAny analysis sequence can be
automated for implementation in the production environment using the Weir Daily Monitor (DM)
• Weir DM Setup Screen
• entered through the Weir Engineer “Tools/Daily Monitor Setup” menu item.
• Statistics displayed will be specified in the second “Graphics Display” tab.
• Statistics and trend charts maintained are specified in the “Statistics Display” tab.
Any analysis sequence can be automated for implementation in the production environment using the Weir Daily Monitor (DM)
• Weir DM Setup Screen
• entered through the Weir Engineer “Tools/Daily Monitor Setup” menu item.
• Statistics displayed will be specified in the second “Graphics Display” tab.
• Statistics and trend charts maintained are specified in the “Statistics Display” tab.
Reticle data or Component (Mean or
Best Focus fields) can be removed.
Reticle data or Component (Mean or
Best Focus fields) can be removed.
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Running Weir DMThe Weir DM is a “stand-alone” program that can also be called from the Weir Engineering interface.
The analysis for a calibration uses the layout specified in the template.Current DM TemplatesCurrent DM Templates
Files in the data directory.
Sorted alphabetically.
Files in the data directory.
Sorted alphabetically.
Starts the calibration.Starts the calibration.
“One-Click”Analysis
• pre-selected templates in drop-down listings
• Data files, sorted and pre-selected in a drop-down listing.
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Weir DM Trend Charts
• The Weir DM software plots one template chart for each data variable selected. Above is shown the data for the “Mean -3sigma statistic”. Corresponding data for the Best Focus, or data mean is shown on the right
• Here we observe “Mean” feature settings. Vertical (X) and Horizontal (Y) focus data can also be viewed.
Measurement date shown on the
abscissa.
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Field Focus• Field modeled best focus is changing with wafer number
(right).
• If we look at vertical (slit) focus, we can see the focus drift until about the 6th wafer.
• Horizontal (scan) focus remains constant.
• This is consistent with lens heating effects.
Lens (slit) focus Scan focus
Average
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Astigmatism
• Astigmatism, also sensitive to lens heating, is shown to settle after the 8th wafer.
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Summary of Weir PSFM• Any metrology data can be imported
Weir PW contains a layout optimizer and basic metrology analysis capabilities Data is stored in Microsoft Excel® worksheet and workbooks
• Layout of Dose, Focus, NA, PC and stage/scan direction Supported by graphic tools as well as simple point-and-click entry.
Fixed-Focus• Stage and wafer-edge performance• Average or selected field analysis.• User can remove mean-field, best-focus or selected modeled aberrations prior to performing
analysis.• Modeled wafer and field
Weir DM• Automation of frequently performed Calibration, Fixed-Focus or Raw Data.
• Automation Weir DM can be used to automate process-monitor points for any variable series.
