Instrumentation in Precision Metrology

1. Instrumentation in Precision Metrology
Hung-Ming Tai
Instrument & Sensor Technology Development Division
Center for Measurement Standards (CMS)
ITRI

2. ITRI
Outlines
• Needs on Nanometrology in Industry
• Approaches for Reducing Metrology Errors
for FPD Industry
• Examples of Using New Metrology Tools
in Industry
• Conclusions

3. Needs on Nanometrology in
Industry

4. ITRI
Background
Academic Research
•Material Science
•Surface Physics
•Bio-Science
Instruments for Nanotechnology
Scientific Applications
Semiconductor Industry
1985~
FPD Industry
Precision Mechtronics
Industry
2000~
2005~

5. ITRI
Needs
•Film thickness : hundreds of um
•Light guide (LG), Brightness-Enhancement-
Film (BEF) pit/prism height : 1~100 um
•Interval : 5~500 um
Module
•Color Filter (CF) film thickness : hundreds
of nm
•Interval : hundreds of um
Cell
•TFT, ITO film thickness : angstroms to
100nm
•Period : hundreds of um
Array
Feature DimensionsProcess
Flat Panel Display (FPD) manufacturing processes and their
feature dimensions

6. ITRI
2002 2004 2006 2008 2010 2012
Gen 8
Gen 7.5
Gen 3 / 4.5 / 5
Gen 10
Flexible
Rollable
Rigid
Paper like
R2R (continuous)
Flat-Flat
(Batch)
Lithography
Printing
Needs
Display Evolutions
Simpler 0-2D Complex 0-3D
Size
Critical features
Shape
Production
Color Filter CF free
OLED
Mechanism
LCD
BLU
Array
(MVA,BEF,CF,PS, etc)
Gen 11

7. ITRI
Old
design
New
design
Before
improvement
Example
Light Guide in the Small Display
Single LCD backlight guide
(Ref : Integra)
After
improvement

8. Approaches for Reducing Metrology
Errors for FPD Industry

9. ITRI
Metrology Errors
• Material : transparent or non-transparent
• Structure : periodic or non-periodic
Reflection
Too large spot size
Blunt tip of stylus profilers
Optical microscope Probe microscope
Too small range
Interference

10. ITRI
Measurement error
caused by the reflection
of the other slope
10
Slope Effect Flaws
(Information from research activity in NPL, UK)

11. ITRI
Nanometrology in CMS
• Importance of metrology for optical thin films
with micro-structures
– Play important rolls in flat-panel display
– Light guide, BEF, CF, PS,
• Metrology technology in CMS ITRI:
– Enhanced AFM-based nano profiler
– Large scan interferometer profiler

12. ITRI
• Core technologies :
• Nanometers resolution in surface roughness
• Precision focus control
• 3D image reconstruction
• Calibration
Gauge 量測
Technology Focus
Center of gravity
Interferometer
Center of focus
Interferometer rotation center
Thermal noise,
Vibration
Metrology by Tilted Interferometer

13. ITRI
Stand-alone BEF measurement system

14. ITRI
Integrated Interferometer and AFM System
Long travel : 250x250x100um

15. Examples of Using New
Metrology Tools in Industry

16. ITRI
Examples of Using New
Metrology Tools in Industry
• Light Guide
• Backlight enhancement film
• Cell in FPD manufacturing process

17. Light Guide

18. ITRI
Light Guide
Penetrating Light
Reflected
Light
Incident Light
Microstructures

19. ITRI
LG (Light Guide) Metrology
by Long-Travel AFM

20. ITRI
Light guide plate
Light guide 3D
(scan range：100 μm x 100 μm )
LG Metrology by Long-Travel AFM
Roughness characterized

21. ITRI
• Checking roughness
of V-CUT yields
better brightness
• Roughness
specification now is
reaching to 10nm
(W.J..Jen)
By Diamond cutter (Ra<20nm)
By Tungsten Carbide cutter (Ra>50nm)
Brightness
2467
cd/m²
Brightness
2826
cd/m²
(Improvem
ent : 15%)
Light Guide Made by Two Cutters

22. ITRI Light Guide Shape Effect
Improvem
ent of the
total light
emission :
20.2%
(C.J. Ho)
Micro-structure
Brightness
Micro-structure
Brightness

23. Brightness Enhancement Film

24. ITRI
Brightness Enhancement Film

25. ITRI
BEF Metrology by Long-Travel AFM
Measuring BEF properties
- Pitch, surface roughness, tip angle
BEF BEF
(scan range：100 μm x 100 μm ) (scan range：100 μm x 100 μm )

26. ITRI
Computation– 3D Reconstruction

27. ITRI
Measurement of BEF mold
sample

28. ITRI
Artifact-reduced Metrology
5.4± 3um
(±55%)
15.0±
2.1um
(±14%)
Stylus
Unstable
(>±55%)
Unstable
(>±20%)
Laser scan
head
0.040±
0.005nm
(±13%)
15.0± 1um
(±7%)
ITRI
Research
ProfileRaDepthTest
Comparison
0
0
0
0
0
0
1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103 109 115 121 127 133 139 145 151 157 163 169 175 181 187 193 199

29. ITRI
Study on Wear of BEF
Film or glass to be contacted
Tip radius r < 100nm
r > 1000nm
Heat, humidity
Deformation due to
•Reaction with H2O
•Stress release
•Micro reflow of polymer
Vibration induces
wear
Micro-structures
BEF

30. ITRI
Nano-tribology Study by 3D Metrology
Blunt edge
High recycling
Sharp edge
• Prism wear
Low recycling

31. ITRI
磨耗率(平行摩擦)
0.0%
20.0%
40.0%
60.0%
80.0%
10 100 1000
摩擦週期數 (轉)
高度磨耗率
3M
EFUN
國外A廠
國內B廠 高度磨耗率
ASTM abrasion resistance test
16
12
8
4
0
Wear(um)
Nano-tribology Study by 3D Metrology
Wear percentage
Wear Cycles

32. ITRI
0%
2%
4%
6%
8%
10%
12%
0 2 4 6
Wear(um)
BrightnessLossPercentage
Brightness Loss
Percentage v.s.
Wear
0
50
100
150
200
250
300
350
-60 -40 -20 0 20 40 60
Angle (degree)
Brightness(cd/m^2)
磨損區
未磨損區
Brightness loss
when prism tip
with 1.1-1.4um
wear
Brightness loss for
prism tip wear
with 3 levels

33. Other Examples

34. ITRI
Nanometrology for FPD Application
Color filter (CF)
Photo spacer
height
MVA
angle
R、G、B
thickness
Before CF is really attached
to TFT, volume of liquid
crystal is estimated based
on all the dimensions
measured.

35. ITRI
Spec.：In ordinary floor vibration，3σ<10nm
所有軸系全關(下班後) 軸系全開PIDdown氣缸承壓抑振
軸系全關+廣播 軸系全開
Vibration Isolation for Interferometer Profiler

36. ITRI
○
○
○
Module
-Glass
◎◎◎◎3D
○Electrical
○○Brightness
○○1D
○○○○2D
Module
-Backlight
Color
filter
CellArray
Metrology Model vs. Processes
◎ Still open to applicable metrology tools
○ Industry has had solutions
Metrology
model
Process

37. ITRI
Smart Buildings with Functional Films
• High-efficiency
solar panel
• Lotus effect
• Chameleon effect
• Adaptive functional film
artificial skin
sun-tracing
• Solar light guide
• Light-controlling film
• High-efficiency LED
• Solar light emulator

38. ITRI
Advanced 3D Metrology for FPD Industry
Roller makers
Roller machine makers Verifying patterns and
comparing optical/
Module integrators
Film makers
Supply chain

39. ITRI
Conclusions
• Demanding metrology needs from FPD industry
push instrument to meet nanometer resolution for
optical elements
• Long-travel SPM shows its strength for measuring
micro-structured thin film for FPD industry
• New interferometer profiler with large tilt angle
shows its promising capability for large sloped
micro-structured thin film measurement and in-
line nano-metrology

40. ITRI
Technology Map
Technology Barrier
HighLow
3D
2D
1D
Metrology
model
Mura
Short/breakage
defects
Glass thickness
Line width
Brightness testOptical response
Micro crack
Light-guide structure
Photo spacer
CF film
Array verification
Stress/strain
Advanced 3DAdvanced 3D
MetrologyMetrology
(Ultra slope+透明)
(Small slope)
(Large slope)

41. ITRI
Measuring Photo-spacer and CF
Photo-spacer
(scan range：100 μm x 100 μm )
CF (color filter)
MVA (wide
view angle)
Photo-spacer
MVA (wide
view angle)
BM (black matrix)
CF
MVA
廣視角
Photo-
spacer
MVA
廣視角
BM

42. ITRI
Tilted Microscope with Ultra Large Angle