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23/11/00 Repli0011 1

Measuring Size, Shape andPosition of Pits and Grooves

Donald A. Chernoff and David L. BurkheadAdvanced Surface Microscopy Inc.

Indianapolis, IN USA

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Outline◆ Why make Physical Measurements of

Pits and Grooves?◆ Pit Geometry and Jitter (DVD-ROM)◆ Groove Geometry (CD-R)◆ Track centering in

complex headers (M-O)◆ Wobble groove amplitude (DVD+RW,

CD-R)

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DVD = NanoTechnology◆ Feature Size:

400 nm L x 320 nm W x 120 nm H◆ Track Pitch: 740 nm

Mean +/- 10Range 710-770

◆ Jitter: 8% = 11 nm◆ Nanometer Manufacturing needs

Nanometer Inspection Tools

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Scanning Probe Microscope

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Atomic Force Microscope

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Probes

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DiscTrack Plus makes AFM more Powerful

◆ AFM = Atomic Force Microscope◆ AFM gives 3-Dimensional Images of

individual pits◆ AFM is used at many Disc companies◆ Root Cause Analysis◆ Correlation of Dimensions

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Plowing Marks (“clouds”)

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Process Optimization

ProductionVariables

PitGeometry

ElectricalPerformance

◆ Indirect Control Using Disc Analyzer

Pit Geometry is a hidden variable

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Process Optimization

ProductionVariables

PitGeometry

ElectricalPerformance

◆ DiscTrack Plus provides missing link

Causes and Effects of Pit Geometrycan now be Examined

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Data Analysis◆ Old Method

– Built-in Tools◆ New Method

– Add-on Tools:DiscTrack PlusTM

– Patented

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Old Method◆ Height 149 nm◆ Width 335 nm◆ Pitch 1481/2

= 740 nm

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Method Characteristics: Old New

◆ Quick, easyfor singlemeasurements

◆ Imprecise (1 pixel)◆ Inaccurate (up to

5% error)◆ Slow, tedious

for manymeasurements

◆ Find FeaturesAutomatically

◆ Sub-Pixel Precision◆ Detect, correct

measurement errors(to 0.3% accuracy)

◆ Measure 100s ofFeatures Easily

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Mental State vs.Measurement Number

Manual Automatic

10

100

10000

100000

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Automated measurementwithout calibration correction

300

350

400

450

500

300 500 700 900 1100 1300 1500

Length at Threshold (nm)

Wid

th a

t Thr

esho

ld (n

m)

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Automated measurementwith calibration correction

300

350

400

450

500

300 500 700 900 1100 1300 1500

Length at Threshold (nm)

Wid

th a

t Thr

esho

ld (n

m)

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Mean values of T3 width(Automated measurements)

245

265

285

305

325

345

-15 -10 -5 0 5 10 15

Relative Laser Power (%)

Wid

th o

f T3

(nm

)

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Feature Geometry

Automated, high-accuracy measurementof size, shape, and position of individual

features

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Feature GeometryH eight Profile across a bum p

Position

Hei

ght

Height

W idth N ear Top

W idth at user defined height

W idth N ear Bottom

Sidewall Angle

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Data Capture: 10 um Scans for DVD

Calibrator Test (DVD Stamper)

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Pit Geometry of DVD

300

350

400

450

500

300 500 700 900 1100 1300 1500

Length at Threshold (nm)

Wid

th a

t Thr

esho

ld (n

m)

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Feature Width:Defect Identification

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Feature detail

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Expansion of Feature detail

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Length Analysis gives“AFM Jitter” and more

Length AnalysisBumps Lands

Jitter 6.82% 6.00%Channel bit length (nm) 134.38 133.68Offset (nm) 31.88 -36.76

Good Stampers have Jitter about 3 - 3.5%

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Length deviation vs T number(Power series stamper)

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

0 2 4 6 8 10 12

T#

Devi

atio

n (n

m)

12.50%0.00%-10.00%

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Write Strategy / Length OffsetLength vs. T Number

Length Analysis(Write Strategy)

-200

0

200

400

600

800

1000

1200

1400

1600

0 2 4 6 8 10 12

T Number

Effe

ct L

engt

h (n

m)

Y Intercept = -34.21 nm(Length Offset)

Slope = 133.51(Channel Bit length)

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Length offset vs relative laserpower

-100

-90

-80

-70

-60

-50

-40

-12% -7% -2% 3%Relative laser power

Leng

th o

ffset

(nm

)

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Asymmetry vs Length Offset

-8%

-6%

-4%

-2%

0%

2%

4%

6%

-100 -90 -80 -70 -60 -50 -40

Length Offset (nm)

Ass

ymm

etry

(%)

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Comparison of DiscTrack Plus with Stamper Player

Relative Laser Power 12.5% 0.0% -10.0% 12.5% 0.0% -10.0%Jitter (%) 3.20% 3.29% 3.34% 3.00% 3.35% 3.54%Channel Bit Length 132.94 133.05 132.63 132.66 133.26 135.05Offset -7.09 -37.61 -74.91 1.90 34.20 65.32Mean Width at T3 322.27 299.13 259.80Width Variation (Total SD within group) 9.61 7.29 7.30

Jitter (%) 10.10% 7.10% 15.20%

Asymmetry 17.90% 6.10% -5.90%Stam

per

Play

er

Effect (Bump) Land

AFM

- D

iscT

rack

Plu

s

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How do you fix a jitterproblem?

Edge Placement Variation

Asymmetry

Length Bias

Other effects

Comes

from

Jitter

Disc Analyzers giveyou a number

Jitter

Length Offset (Deviation)

Channel Bit Length

Pit GeometryTrack Pitch

DiscTrack Plus Tells youwhat causes it

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Image of CD-R Stamper

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Summary of Measurements

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Individual WidthMeasurements

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Width of stamper ridges

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Height of Stamper Ridges

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OD angle in stamper ridges

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ID angle in stamper ridges

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Geometry of pre-formedgroove in CD-R

Mean values Brand A Brand BGroove Depth (nm) 135.61 172.18Width at Half-Ht. (nm) 442.82 569.49Left Side Angle (deg.) (Outer Diameter Direction) 26.37 26.91Right Side Angle (deg) (Inner Diameter Direction) 21.85 24.5

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Complex Header Structure:Magneto Optical Disc

◆ Are the Pits Centered between the Grooves?B

A

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Track Pitch measurement ofMagneto Optical disc

Feature Centering

500520540560580600620640660680700

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Half Track

Pitc

h (n

m)

Spacing between pit and groove to left

Spacing between pit and groove to right

A

B

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Pitch results for Groups A and B(left and right half tracks)

Half Tracks Mean (nm) StDev Max Min RangeLeft 622.98 10.61 631.37 601.02 30.35Right 547.45 2.14 551.01 544.83 6.18

BA

◆ Groups A and B had different Pitch, so Pitsnot centered between grooves

◆ Group A pitch had 5x less variation thanGroup B pitch, so Group A corresponds to 2beams locked together. Group B pitchvariation reflects stage motion in LBR.

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DVD+RW Groove Wobble

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Measurement of GrooveWobble Amplitude

◆ Direct Physical Measurement usingmany, high-precision track pitchmeasurements

◆ Can Measure stampers or mastersbefore replication

◆ Independent check on electrical testers

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Pitch Measurements

Measure 50 pitchvalues along eachpair of tracks.

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Wobble MeasurementsDVD+RW Wobble

680

700

720

740

760

780

800

1 2 3 4 5 6 7 8 9 10 11 12

Track Number

Pitc

h (n

m)

Pitch (nm)Mean 746.35

Range 114.37Wobble

Amplitude 28.59

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Compute Wobblefrom Track Pitch

Wobble in adjacent tracks

Track one

Track two

Wobble Amplitude(A)

Mean Pitch(P) P-2A P+2A

Difference4A

Typical Measurementregion

Wobble amplitudegreatly exaggerated

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Wobble Measurement SampleResults

Wobble as measured in track pitch

1470

1490

1510

1530

1550

1570

1590

1610

Track #

Pitc

h (n

m)

Pitch

Range: 136 nm

Wobble: 34 nm

1 2 3 4 5 6 7 8 9 10 11 12

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Summary◆ AFM plus Automatic Tools◆ Improved Calibration & Precision◆ High Count --> Statistical Analysis

– Track Pitch– Pit Geometry– Width Variation– Defects– Wobble

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Advanced Surface Microscopy

◆ We don’t make the AFM,we make the AFM better.

◆ DiscTrack PlusTM Media MeasurementSystem

◆ www.asmicro.com◆ donc@asmicro.com

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Where is ASM?

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What does ASM do?◆ Analytical Service Lab specializing in

SPM (Scanning Probe Microscopy)◆ Precision measurement systems and

other software enhancements forSPM’s

◆ Buy and sell used NanoScopes◆ Consulting and training in SPM