Critical Feature and Process Tuning Software

1
Critical Feature and Process Tuning Software
TEA Systems Products

• Weir PW
• Weir PSFM Calibration
• Weir PSFM Fixed-Focus

Weir TR Vector Raptor Weir DMA
65 Schlossburg St. Alburtis, PA 18011 (1) 610
682 4146 tzavecz_at_TEAsystems.com http//www.TEAsyst
ems.com
Ver 1-June-2007
2
Outline

• Products from TEA Systems
• Vector Raptor
• Weir PW
• Weir TR
• Weir PSFM Calibration
• Weir PSFM Fixed Focus
• Weir DM and Weir DMA
• Product Features
• Applications
• Addressed by each product
• System Requirements
• License Basis
• Sample Wafer Plots

3
Vector Raptor

• Vector Raptor Overlay Double Patterning
• Classic Overlay Modeling
• Classic models WITH additional
• Graphics control
• Portability
• Apply to
• whole field, row (reticle scan response) and
  column (scan-slit response)
• Advanced Features
• Match to any other CDU metrology
• Proprietary modeling engine
• Models adaptive
• Multi-level, automate and manual methods for data
  culling
• Multi-Family Analysis
• overlay-structure and pattern-split analysis
• Error Source Discrimination
• Resolve error sources
• Process
• Wafer-chuck
• Field

4
Weir PW LithoWorks PEB

• Weir PW
• Process Windows and much more.
• Critical feature,overlay, registration,electrical
  and film models for simulator calibration,
  process setup, control and characterization
• Weir TR
• Time Response based studies
• Automated Phase and energy calculation
• Post Exposure Bake and other thermal studies
• Correlate temperature data to Weir PW analyses
  for a true analysis of thermal uniformity.

IsoFocal Analysis
PEB Thermal Energy vs Resist
5
Weir PSFM

• Weir PSFM Calibration
• Phase Shift Focus Monitor and other linear of
  exposure-tool focus to specialized test
  structures.
• Works with Benchmark PSFM, CANON Zspin, AMD
  Phase-Grating, ASML Focal, Toshiba Phase
  Gratings, End-of-Line Shortening and other
  reticle patterns
• Models the calibration-derived focal-plane of the
  exposure tool to derive reticle and tool focus
  budget.
• Weir PSFM Fixed Focus
• Analysis of full-field, wafer and lot
  focus-uniformity data.
• Use Weir PSFM Calibration templates to convert
  measured offset data to Focus
• Model the flatness of films, wafers, reticles,
  reticle scanners and lens perturbations.

PSFM Calibration
Focus Uniformity
6
Weir DM Weir DMA

• Weir DM
• Daily Monitor, two-click automation
• Any Weir PW or PSFM analysis using user-created
  Macros
• Trend charts, password protection, graphic
  displays
• Weir DMA
• Daily Monitor Automated
• External program-callable Macros
• Automated alarms and output
• User selected output formats and variables

Weir DM Macro Setup Interface
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Running Weir DM
The 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 Templates
Files in the data directory. Sorted
alphabetically.
Starts the calibration.
One-Click Analysis

• pre-selected templates in drop-down listings
• Data files, sorted and pre-selected in a
  drop-down listing.

8
Astigmatism Trend Chart on Weir DM

• Astigmatism, also sensitive to lens heating, is
  shown to settle after the 8th wafer.

9
Outline Product Features

• Products from TEA Systems
• General Product Features
• Data Import
• Graphics Features
• 2D Graphics
• 3D Graphics
• General Analyses
• Data Tools
• Retention Reporting
• Applications
• As addressed by each product
• System Requirements
• License Basis

10
Data Import Features

• Import ANY metrology
• If we dont have the import now, we will create
  it
• Focus-Exposure excel spreadsheets
• Overlay, film-thickness, profile, Cdsem,
  electrical test, etc.
• Open data format
• Microsoft Excel Workbooks
• A unique Weir Workbook is created for each
  dataset
• Any number of variables
• Any size dataset

• Weir imports data from any ASCII, Binary or
  database.
• After import, data is converted into a standard
  Weir format Excel Workbook.
• Workbook Stores
• Intermediate analysis data,
• analysis reports,
• Graphics
• Derived datasets
• HTML delivery
• Weir Worksheets can be saved as HTM or HTML files
  for internet display

11
Graphics Features

• Drill-down graphics
• Any graphic
• Easy user modification
• Mouse selected graphics
• View sub-plots
• Save to spreadsheet data from sub-sections
• Cull specific data points/sites or areas of data.
• Single-click access to graphs, sub-graphics, data
  selection and culling.

12
Viewing variations across wafer diameter

• Use mouse to drag and outline a section.
• Plot graphic by x column position
• Notice astigmatism and how it increases at
  wafers edge.

Xfocus Yfocus and Average
13
Graph Editor
Graphic interface modification Point-click
adjustments Graphs are mouse sensitive to show
and highlight individual points
14
2D Graphs

• Histograms
• 1 2 variable
• XY Plots
• Line and scatter plots
• BoxPlots, Fitted Curves and notes can be added to
  any plot
• BoxPlots
• Can be added to ANY XY plot
• Population Density Plots
• Field Wafer Contour
• Radial Variation
• Range Plots
• 1D and 2D Vector Plots
• Variable Covariance plots
• Plus all Excel based graphics

Raw Photoresist Thickness from Ellipsometer
15
3D Graphs

• Field 3D surface graphics
• General response surface graphics

16
General Analyses

• Plots and statistics
• For Raw, Modeled and Residual data.
• Reticle data at true(4x) and final (1x) size
• Mask Error Function (MEF) plotting
• Removal of Reticle data from wafer for true
  process response
• Optimum or Best Focus
• From PSFM and other specialty reticles
• From variable Feature profiles for reticle design
  simulator validation
• Automated Precision Error Budget calculation
• Automated variable Covariance

17
Data Tools

• View raw, modeled and residual data
• Model any wafer, field,lens, slit and scan
  systematic errors
• For any variable
• View individual wafer, field, slit,etc modeled,
  residual data
• Multiple field models
• Weir custom and scanner vendor emulated
• View data as astigmatic, average, max/min data
  variations.
• Field Mean, max, minimum, MinMax, IFD, Range MEF
  etc.
• Stepper as well as scanner oriented models
• Also hotplate, etch symmetric and asymmetric
  models
• Exposure Layouts
• Across wafer Lot variations for Focus, Dose,
  Numeric Aperture, Partial Coherence, Scan
  Direction are stored with data.
• Layouts can be imported from the data
• Graphic, mouse-driven utility for easy manual
  entry of the layout
• Layout library is maintained for easy updating of
  new datasets with a single click of the mouse

18
Data Retention

• Data is imported and stored in an open format
• Easily adapted to other software analyses or user
  analysis using Excel native tools
• Data is stored in the same workbook for
• Raw data
• Recipe and measurement notes
• Site locations
• Analysis reports and graphics
• All intermediate modeling surfaces
• All calculated data surface

19
Outline Applications

• Products from TEA Systems
• Product Features
• Applications (Automated by Weir DMA)
• Overlay
• Exposure Tool setup Characterization
• Photomask Process Control
• Reticle RET Qualification
• Thermal Process setup
• Metrology validation
• LER, ARC and Resist evaluation
• Process Setup Control
• Modeled Production Gating
• Simulation validation
• Focus optimization
• System Requirements
• License Basis

20
Exposure Tool Setup Characterization

• Weir PW
• spatial feature process window models
• Calculate component precision and their
  contributions to feature distortion.
• Remove reticle average field data
• enhanced exposure tuning and scan-and-slit
  performance mapping.
• Classic lens aberrations
• and their influence on feature size.
• Classic process windows PLUS
• Across entire field for any number of variables.
• Model Films, BARC, TARC, swing curve etc.
  behavior
• Wafer-edge and field-edge aberrations.
• Scan region sensitivity
• Dose Uniformity
• Derive Reticle sizes from wafer data
• Lens and reticle heating during exposure.
• Map DoF uniformity
• Simulate tool performance What if

• Weir PSFM (Focus)
• Map aerial image, focal plane uniformity
• Model wholewafer autofocus stability
• Map wafer flatness and derive the influence of
  substrate films on autofocus sensitivity.
• Model lens-slit and reticle-scan static and
  dynamic performance signatures.
• Extract wafer-edge and edge-bead effects.
• Calculate classic lens aberrations through their
  influence on feature focus.

21
BottomCD vs Focus
Isofocal region on Scanner A vs B
Scanner A
Scanner "B"
Up SCAN
Down - SCAN
22
Photomask Process Control

• Weir PW
• Metrology from any data source or manual entry
• Process Windows, Bossung Plots etc.
• Model etch uniformity from scatterometry
• Model feature profiles and etch depth
• Correlate to wafer response across the process
  window
• Encapsulate data
• standard format for the wafer-fabrication
  engineer
• Provides a valuable commodity by giving the wafer
  engineer a reticle signature library entry for
• Reticle design qualification
• Reticle use re-validation
• Wafer process setup thru reticle signature
  removal
• Tool setup for thermal bake and exposure-tool
  reticle bending

23
MoSiON Fingerprint

• MoSiON uniformity across Reticle
• 1D vector plot (top left)
• Contour (top right)
• 3D Contour bottom left

24
Reticle RET Qualification

• Qualify Reticle Enhancement Techniques
• Weir PW
• Use Focus or Focus-Dose Matrices
• Calculate true reticle size
• Weir automatically removes wafer, film and focus
  errors as well as dose perturbations
• Sub-nanometer accuracy from CDsem or
  Scatterometry
• Works with all RET methods
• Correlate to measured reticle variables
• Optimize reticle etch depth for RET
• Calculate Depth-of-Focus uniformity for each
  scanner/stepper
• Calculate Best Focus for this RET design
• Qualify simulator responses
• Determine simulator variable values

Reticle signature and damaged site
25
Calculated measured Reticle Size
CD-SEM Reticle MEF 4.3292
Optimized BCD from Wafer
Nanometrics Reticle MEF 4.305813
26
Thermal Process setup

• Weir TR - PEB Setup
• Import Thermal probe data from any commercial
  system
• Visualize and model thermal flow, cycles,
  uniformity.
• Calculate energy delivered to segments of the
  substrate.
• Align and correlate thermal energy and model data
  to spatial models of critical feature elements
  across the wafer and bake plate.
• Weir PW
• Correlate wafer-spatial model response to thermal
  response variables

LithoWorks PEB Thermal Probe Plot
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PEB 7 Thermal energy variation

• Energy variation around the average temperature.
• Represents the area under the curve
• Variations below the mean wafer temperature at
  each slice are considered negative (deg-sec)
• Right side of wafer receives less themal energy

28
Thermal range and transitions PEB 8
29
Bake versus Feature correlations
Photoresist Thickness
30
Metrology validation

• Weir PW
• Validate scatterometry model range and
  repeatability
• Calculate metrology tool precision
• Determine the limits of metrology tool variation

31
Metrology Variable Covariance

• Understanding the covariance of thresholds and
  measured values is critical.
• Below is a covariance matrix of multiple features
  measured in the data set.
• The plot shows the covariance of two selected
  variables
• Graph selections are easily made using the
  drop-down and check-boxes provided.

Top bottom die sites
32
LER, ARC and Resist evaluation

• Weir PW
• Use with 4-point probe, electrical or
  scatterometry data
• Calculate swing curves from normal product data
  or focusdose matrices
• LER from any CDsem or other linewidth tool
• mapped to wafer/field position
• Calculate covariance with other metrology
  variables
• ARC thickness and Photoresist optimization
• Bottom or Top ARCs
• Determine thickness changes with focus/dose
• Calculate changes in optimum focus with ARC type
  and dose
• Compare to other brands for process window,
  influence on DoF, optimum focus etc.

33
Process Setup Control

• Weir PW
• Standard Process Windows
• Independent / simultaneous rectangular and
  elliptical windows
• Full-field process window models
• Needed for sub-90 nm nodes
• Any number of features and field-sites.
• Full-field Depth-of-Focus
• Removal of wafer tilt and bow prior to modeling
• User and automated data culling
• Swing curve fitting from production or dose
  matrix data sets.
• Thickness-loss curve fitting
• Film uniformity monitors
• Visual, whole-wafer and whole field mapping of
  process window.
• Wafer radial and edge-bead analysis.
• Exposure tool dose uniformity evaluations.

• Weir PSFM
• Aerial Image, full-field and wafer focus modeling
• Flatness Tilt control
• Only software capable of calculating wafer tilt
• Focus uniformity
• Edge influence on auto-leveling and auto-focus
• Edge bead analysis

34
Scatterometry Process Window

• Exposures
• 193nm litho process for 100nm features
• AT1100 scanner, 0.75NA with annular illumination
• 90nm gratings at 11 with full field coverage
• 240nm resist on 78nm Barc on Si
• OCD metrology NI, rotating polarized light
  (Nano9030)
• diffractive optical metrology (scatterometry) -
  outputs spectral intensity changes of 0th order
  diffracted light intensity
• Weir PW Software from TEA Systems

35
Metrology Process Independent Characteristics
Focus Uniformity
Depth of Focus Uniformity
36
Process Window Setup Interface
37
Process Window - center of field
38
Spatial comparison of parameters
SWA v Wafer Radius
SWA

• Examine and compare systematic variations across
  the wafer
• Provides information of process sensitivity
• Systematic errors can be removed from data to
  enhance analysis resolution.
• Data shown as 1D vector contour plot (lower
  right)

ARC Coat
CD Threshold
PResist thickness
39
Dose _at_ Best Focus
40
Report Dose _at_ Best Focus
Portion of a Weir Data Workbook report on BCD vs
Dose response when Focus errors are removed
41
Modeled Production Gating

• Weir PW
• Model profile variation across the field and
  wafer
• Pass/fail wafers for redo loops or control based
  on modeled results
• Results in fewer wafers rejected when compared to
  mean3 sigma gating tests
• Model film thickness, profiles, Side-wall-angle
  (SWA), CD size, etc.

42
Simulation validation

• Weir PW
• Evaluate film thickness and feature profiles
• Correlate data with outputs from Prolith, Sigma C
  etc.
• Calculate simulator variables to improve
  simulations
• Determine influence of the full process window on
  simulators

43
Focus optimization

• Weir PW
• Derive focus and dose uniformity
• from feature focus-matrices and
  line-end-shortening.
• Calculate "Best Focus" across field (IFD) and
  Focal-plane uniformity
• from any Critical Feature metrology set,
  Line-End-Shortening
• Determine Dose response from focus-error-free
  data
• Weir PSFM
• Calibrate Phase Shift Focus Monitor (PSFM), Phase
  Grating( PGM), End-of-Line, and Z-spin Reticles.
• Apply reticle calibrations to whole-wafer focus
  uniformity analyses.
• Calculate both wafer and field tilt, bow and
  random errors
• Calculate the effects of thermal heating during
  exposure
• Effects of film, trench-etch, wafer and and
  scanner stage
• Wafer edge-bead and edge-die influence
• Measure wafer flatness.
• Analyze ASML FOCAL focus data
• with raw or modeled full-field analyses

44
Focus Slit Profile
PGM
PSFM160
PSFM180
FOCAL

• Focus uniformity across lens (slit)
• Field-modeled piston and tilt have been removed.

45
X-Slit Astigmatism
Artemis (from 3/2002)
Annular (0.85/0.55)
FOCAL
PSFM 180
PGM
PSFM 160

• Shape of curve for Z5 Artemis coefficient and the
  Focal Astigmatism plot is good
• Field tilt is included in the FOCAL data
• Magnitude of the plots is off
• Also recall that the FOCAL data is from a
  ring-aperture setting.

46
Tool Programmed Offsets
Background focus, no offsets

• Mean focus is plotted
• Tool focus set to 0.1
• Median effective focus -0.028
• Offsets follow programmed values (above) very
  closely.
• -0.24 field is shown by arrow for orientation

47
Relative Measured Field Offsets

• Restricted analysis wafer diameter to 85 mm
  radius
• Removed mean field
• Relative offsets of each field is clearer

48
Recommended System Requirements

• Minimum recommended system
• Windows 2000 or XP Professional
• Microsoft Excel version 9 or later
• Pentium IV, 1.2 Gigahertz CPU
• 256 Megabytes of RAM
• Monitor 1024x780

49
License Basis

• License formats
• Licenses are software locks that are keyed to the
  hardware upon which it is installed.
• Licenses can be input manually or delivered via
  email text files.
• License periods can be set from 1 to 365 days or
  as a permanent license
• Demonstration, lease and permanent licenses are
  available.
• Single-user node-locked license
• License is locked to a computers disk
• Only one user, on the target computer may use the
  license
• Floating node license
• License is locked to a computers disk
• Any user on the network can access and use the
  software
• Only one user at a time may use the software
• Software image shuts-down after 30 minutes of
  non-use
• Thereby freeing the license for the next user.

50
Summary of Weir PW

• Any metrology data can be imported
• Weir PW contains a layout optimizer and basic
  metrology analysis capabilities
• Any user-defined variable names may be used
• Data is stored in Microsoft Excel worksheet and
  workbooks
• Multiple data sets can be combined and data
  sub-sets selected for analysis
• Point-and-click mouse interaction for data
  viewing and culling
• Metrology analysis
• Automated metrology covariance
• Automated error-budget analysis.
• Spatial analysis of variables
• Provides information on variation with scan
  direction and film thickness variation
• Point-and-click drill down capability for
  sub-field graphics, data viewing and analysis
• Remove critical systematic components to see the
  true exposure performance
• Process Window analysis and more!
• Extend beyond the single feature/family analysis.
• Examine process window performance variation
  across the full field of exposure.
• Automation
• Weir DM can be used to automate process-monitor
  points for any variable series.

51
Extra Wafer Maps of 6th order parameter
variation(next section)
These slides illustrate the variation of measured
feature size across the wafer and field. More
importantly, they illustrate that feature sizes
can be modeled as systematic errors across each.
Note that when these systematic errors are
removed, the residuals track the variation of
underlying film thickness (such
as.anti-reflective coatings) and
thermal-variation (Post Exposure Bake) across the
wafer during processing. Slide 34 is a good
example. Weir therefore provides a direct method
of measuring both feature and film-variation
influence on feature size.
52
Photoresist
Residuals to all terms
All terms
4th 6th only
53
ARC
Wafer Model
Residuals to all Wafer Coefs
Residuals to Wafer Model Mean Field Removed
54
CD 95 Threshold
Wafer model 4th 6th order only
Wafer Model
Residuals to Wafer Model mean field removed.
55
SWA