Transcript General/CD Uniformity Overview

http://www.TEAsystems.com
CD Uniformity Overview
Origin:
Terrence E. Zavecz
[email protected]
ITRS Lithography Roadmap “A” (2005)
http://www.TEAsystems.com - 2
TEA Systems
Yield Enhancement thru Modeling
ITRS 2005 Methods B Lithography
http://www.TEAsystems.com - 3
TEA Systems
Yield Enhancement thru Modeling
Technology Requirements
http://www.TEAsystems.com - 4
TEA Systems
Yield Enhancement thru Modeling
Optical Mask Requirements
http://www.TEAsystems.com - 5
TEA Systems
Yield Enhancement thru Modeling
Exposure Tool Solutions
http://www.TEAsystems.com - 6
TEA Systems
Yield Enhancement thru Modeling
Lithography Wafer Metrology Precision
http://www.TEAsystems.com - 7
TEA Systems
Yield Enhancement thru Modeling
CD Metrology Technology
http://www.TEAsystems.com - 8
TEA Systems
Yield Enhancement thru Modeling
Overlay Technology
http://www.TEAsystems.com - 9
TEA Systems
Yield Enhancement thru Modeling
IntraWafer Critical Feature Uniformity
Approach to APC
BlueControl etch APC

Blue Control web site





http://www.bluecontroltech.com
Cypress Installation
MIMO Gate control etch in production
Lot-to-Lot controller (2004)
Future


W2W
WIW
http://www.TEAsystems.com - 12
TEA Systems
Yield Enhancement thru Modeling
Simulation Addressed Signatures
Reticle
Scanner
Track & Process
Transmission
Exposure Dose
BARC Uniformity
Uniformity
Slit Uniformity
Resist Film Uniform
Flatness
Focus Stability
PEB Temp & Time
Feature CD
Chuck Flatness
Develop
Up-Down Scan
Soft Metrology Error
Substrate
Wafer flatness
Device topography
Scan Linearity
Effective Focus
Effective Dose
CDU
 Primary disturbances causing CD Uniformity (CDU) variations grouped
upon their sources.
http://www.TEAsystems.com - 13
TEA Systems
Yield Enhancement thru Modeling
Reticle Enhancement Techniques
 “What you See” is not “What you get”
 Design for Manufacture (DFM) Problems




Simulation
 Neglect of most Process & Optic-stack signatures
Optical Proximity Correction
 High-Frequency Limitations of Optical System
Inverse Lithography
 Luminescent
Phase Shift Masks
 Etch depth bias
 Phase-Element Uniformity
http://www.TEAsystems.com - 14
TEA Systems
Yield Enhancement thru Modeling
What Effect on Wafer?
MoSiON Fingerprint on Reticle
Nanometrics Atlas M Scatterometry
TEA Systems Weir PW Data Analysis
http://www.TEAsystems.com - 15
TEA Systems
Yield Enhancement thru Modeling
Photoresist & BCD due to Moly Signature
Raw Photoresist Thickness
Modeled BCD
MoSiON Signature

Photoresist


Modeled BCD
1:1 90 nm features
BCD Full-Field Symmetric Model



BCD component due to MoSiON
Piston & high-order removed
4.5 nm Range
http://www.TEAsystems.com - 16
TEA Systems
Yield Enhancement thru Modeling
Modeling Wafer Bias
CDsem
Reticle
Wafer
http://www.TEAsystems.com - 17
All Dimensions scaled to wafer final size
Scatter
Reticle
TEA Systems
Yield Enhancement thru Modeling
Bias Modeled FEM
 Full-field systematic
response
http://www.TEAsystems.com - 18
TEA Systems
Yield Enhancement thru Modeling
Feed Forward lithograph controls
Process A
Measurement A
Process B
 Models, Simulation and a
database are needed
 Add in process dependencies.
 Objective:

Process N
Anticipate corrections to new
lots BEFORE exposure.
Measurement N
Feed-Forward
Litho
Process
(one tool)
Rework
CD &
Overlay
Process
Dependencies
Modeled
Analysis
Feed-Back
Next Process
http://www.TEAsystems.com - 19
TEA Systems
Yield Enhancement thru Modeling
Feed Forward Techniques
 EWMA
 Exponentially Weighted Moving Average
 Assumes a stable, continuous process
 Enhanced EWMA
 Include separate estimates and trend charts for:
 Exposure Tool combinations
 Process steps
 Problems
 ASIC or Logic fabs with many processes and devices
 Each process-stream must maintain separate tracking and trends for each
process and reticle set.
 Short Lifetime devices
 Long device start intervals
 Model Enhanced Signatures
 Include systematic modeling of tools and process
 Compensate by adding systematic signatures prior to exposure.
 Signatures for processes and tools used in lot history.
 Signatures for target tools of next process step.
http://www.TEAsystems.com - 20
TEA Systems
Yield Enhancement thru Modeling
TRANSLATION
EWMA Feed-Forward
Tool # 3
Translation as recorded
0.1
0.05
0.3
X+ 3 s = 0.0847
0.25
0
0.2
-0.05
0.15
-0.1
-0.15
0.1
X+ 3 s = 0.0736
0.05
-0.2
0
-0.25
-0.05
-0.3
-0.1
EWMA improved by 10 nm
http://www.TEAsystems.com - 21
TEA Systems
Yield Enhancement thru Modeling
Modeled Systematic Error Tracking
0.1
0.08
0.06
0.04
X Translation
0.02
0
-0.02
-0.04
-0.06
-0.08
Y Translation
-0.1
31 10 20 30 09 19 01 11 21 31 10 20 30 10 20 30
/D /J
/J
/J
/F /F /M /M /M /M /A /A /A /M /M /M
p
p
p
ec an an an eb eb ar ar a
a
a
a
a
/9
/9
/9
/9
/9
/9 r/9 r/9 r/9 r/9 r/9 y/9 y/9 y/9
/9
/9
9
9
9
9
9
9
9
9
9
9
9
9
8
0:
0: 9 .. 9 .. 9 ..
0:
0:
0:
0:
0: 0:
0: 0:
0:
0: 0:
.
.
0
0
0
0
0
0
00
0
0 00 .
0 00 00 00 00
0
0
0 00
http://www.TEAsystems.com - 22
TEA Systems
Yield Enhancement thru Modeling
Seeing the Forest . . .
1.
1.
2.
3.
A single tool
aberration
signature.
2.
Identical
signatures
with varying
frequency and
amplitude.
“Random”
noise in daily
Trend Charts
3.
http://www.TEAsystems.com - 23
TEA Systems
Yield Enhancement thru Modeling
Process and Tool offsets
Modeled Translation between two tools
0.06
0.05
0.04
0.03
0.02
0.01
0.00
-0.01
-0.02
-0.03
-0.04
Tool 2
Tool 2
Met3
Via3
M3
Via2
M2
Via1
M1
Contact
Poly
Tool 2
0.20
0.19
0.18
0.17
0.16
0.15
0.14
0.13
0.12
0.11
0.1
0.09
Production variations, and tool setup, are a function of:
• Reticle
• Film Stress
• Residual Matching
• Film Alignment Sensitivity
http://www.TEAsystems.com - 24
TEA Systems
Yield Enhancement thru Modeling
Differentiate Tool Match & Reticle Errors
0.1
0.05
Tool_3
Reticle 1
Tool_3
Reticle 6
Metal Level
Tool_4
Reticle 1
0.2
0.0276
0.15
-0.0288
0
0.1
-0.0422
0.0244
-0.05
0.05
-0.0259
-0.0288
-0.1
0
-0.15
-0.05
-0.2
-0.1
Equipment
Tool 4 - Tool3
Ret 06 - Ret 01
X_shift
-9.1
56.4
http://www.TEAsystems.com - 25
Y_shift
-10.4 nm
50.3 nm
TEA Systems
Yield Enhancement thru Modeling
Statistical Tools
0.100
0.075
Translation
0.050
Bad InterField Stage
Precision.
0.025
CMP Mark
“SMEAR”
0.000
-0.025
-0.050
-0.075
-0.100
CMP Mark
“SMEAR”
-0.125
 Model based statistics -- Global Alignment, Precision – are used to:
 Qualify tool process capability
 Provide data set quality values for Advanced Process Control
http://www.TEAsystems.com - 26
TEA Systems
Yield Enhancement thru Modeling
Implementing the Feed-Forward model
 Aberration signatures add as vectors
Coef feed-forward as: Pr ocess
 Apply
Tlevel n  A  B * (T level n )  C * (T



Re ticle
level n
Tool
)  D * (T level n )
Where “T” is the ith vector coefficient ( Translation, dose, mag etc.) of the
process model that is similarly implemented as:
k
i
i
A,B,C,D are derived dependency ori weighting
factors
0
Tlevel-n values are the vector-coefficients of the process, reticle and tools sets for
level “n” with the reference layer “m” coefficients subtracted, or
dP   T * p
T leveln  T coefficient _ level"n"  T coefficient _ referenceto"n"
http://www.TEAsystems.com - 27
TEA Systems
Yield Enhancement thru Modeling
Putting it together - Tool & Reticle!
Reticle Used
Before Corrections
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
Lot Overlay
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
Exposure Tool
Improvement: (Mean +3Sigma)
Before:
After:

X axis
0.150
0.073
Y axis
0.108
0.084
um
um
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2

Data includes multiple
Exposure Tools and reticles
in a single layer.
Corrections added included
only:


reticle &
Tool Match Residual
After Corrections
Trans X
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
Trans Y
Exposure Tool
http://www.TEAsystems.com - 28
TEA Systems
Yield Enhancement thru Modeling