John CaldwellMicron Technology, Inc.
Electrical Planarity Electrical Planarity Characterization of High Characterization of High Parallelism Probe CardsParallelism Probe Cards
June 8June 8--11, 200811, 2008San Diego, CA USASan Diego, CA USA
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 222
IntroductionIntroduction• Challenge
– High parallelism (1TD 300mm)– Thermal deflection– High probe count– Shrinking bond pads
• Can we maintain the same probe card planarity specification as 32x to 64x parallelism five years ago??– Yes!
• Micron has employed techniques for analyzing optical and electrical planarity data; resulting in…– Improved test cell performance– Better understanding of high parallelism probe card planarity
characteristics– Correlation between metrology and test cell tools
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 333
Introduction (2)Introduction (2)• Optical versus electrical… Or, optical +
electrical?– Optical + electrical
• Electrical first-to-last (EF2L) provides information on potential variance components within the test cell– Probe card planarity and tilt– Prober chuck curvature, tilt, or deflection– System deflection
• Proper analysis of EF2L data allows the user to minimize test cell variance components to achieve the best possible planarity
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 444
TopicsTopics• Pitch and roll• EF2L Sequence• EF2L Examples
1. %Contact by delta-Z2. System-to-system planarity & tilt comparison3. Test cell stack-up error correction4. Optical-to-electrical planarity correlation5. Probe card technology benchmark
• Summary
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 555
Pitch and Roll
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 666
Pitch and RollPitch and Roll• Pitch and roll is. . .
– A metric that represents probe card tilt when installed in metrology systems and/or test cells
– A relative comparison from one system to another when characterizing the same probe card
– Estimated by best-fit linear plane and represented in terms of µRadians
– Not a metric that was invented by Micron or used exclusively by Micron (data analysis methods vary)
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 777
Within Planarity vs. TiltWithin Planarity vs. Tilt
Radius = 295000µm
mPlanarityWithin μδ )_(
mradmTilt RadiusRollPitch μμμδ ⋅≈ )()( &
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 888
µµRadians to Radians to µµmm
05
10152025
303540
4550
0 10 20 30 40 50 60 70 80 90 100
110
120
130
140
150
r = 295,000um (300mm 1TD)r = 150,000um
µRadians
Prob
e C
ard
Tilt
(µm
)
Slide 10 of conference proceedings
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 999
Estimating Pitch and RollEstimating Pitch and Roll
Range = 42µm
-300000
-250000
-200000
-150000
-100000
-50000
0
Y
-150000 -100000 -50000 0 50000 100000 150000 200000
X
0 10 20 30 40
100.0%99.5%97.5%90.0%75.0%50.0%25.0%10.0%2.5%0.5%0.0%
maximum
quartilemedianquartile
minimum
42.00042.00038.62528.50021.00018.000
9.0006.0006.0002.4750.000
Quantiles
Planarity (um)
Pitch = -7µrad Roll = 73.4µrad R2 = 0.36
0
10
20
30
40
50
-1.5e+5
-1.0e+5
-5.0e+4
0.0
5.0e+4
1.0e+5
1.5e+5
2.0e+5 -3e+5
-3e+5
-2e+5
-2e+5
-1e+5
-5e+4
0Ele
ctri
cal
Pla
nari
ty (
um
)
X (Prober Front)
Y
TILT
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 101010
Residual Plot (Within Planarity)Residual Plot (Within Planarity)
-15 -5 0 5 10 15 20
100.0%99.5%97.5%90.0%75.0%50.0%25.0%10.0%2.5%0.5%0.0%
maximum
quartilemedianquartile
minimum
22.2620.7017.1210.18
3.14-0.53-5.26-7.83
-11.14-12.83-12.94
Quantiles
Linear Fit Residuals (um)
-300000
-250000
-200000
-150000
-100000
-50000
0
Y
-150000 -100000 -50000 0 50000 100000 150000 200000
X
Range = 35µm
Pitch = 2.5µradRoll = 1.5µrad
-20
-10
0
10
20
30
-1e+5
0
1e+5
2e+5 -3e+5
-2e+5
-1e+5
0
Ele
ctri
cal P
lan
ari
ty (
um
)
X (Prober Front)
Y
MIN TILT
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 111111
~73~73µµrad Doesnrad Doesn’’t t ReallyReally AddAdd ~21~21µµm To Planarity Windowm To Planarity Window
-40
-20
0
20
40
60
-2e+5-2e+5-1e+5-5e+405e+41e+5
-3e+5 -2e+5 -1e+5 0
Z D
ata
X D
ata
Y Data
mmTilt
mradmTilt
mradmTilt RadiusRollPitch
μμ
μμμ
μμμ
δ
δ
δ
7.21
000,2954.73
&
)(
)(
)()(
≈
⋅≈
⋅≈
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 121212
~73~73µµrad Doesnrad Doesn’’t t ReallyReally AddAdd ~21~21µµm To Planarity Windowm To Planarity Window
-40
-20
0
20
40
60
-2e+5-2e+5-1e+5-5e+405e+41e+5
-3e+5 -2e+5 -1e+5 0
Z D
ata
X D
ata
Y Data
mmPlanarityWithin μδ
μ42)_( =
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 131313
~73~73µµrad Doesnrad Doesn’’t t ReallyReally AddAdd ~21~21µµm To Planarity Windowm To Planarity Window
-40
-20
0
20
40
60
-2e+5-2e+5-1e+5-5e+405e+41e+5
-3e+5 -2e+5 -1e+5 0
Z D
ata
X D
ata
Y Data
mmPlanarityWithin μδ
μ35)_( =
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 141414
EF2L Sequence
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 151515
EF2L SequenceEF2L Sequence
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 161616
EF2L Examples
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 171717
Example: %pass DataExample: %pass Datadelta-Z #PASS DELTA-PASS %PASS
0 6 6 0.2%
3 12 6 0.4%
6 18 6 0.6%
9 28 10 0.9%
12 146 118 4.8%
15 443 297 14.6%
18 695 252 23.0%
21 1403 708 46.4%
24 2016 613 66.7%
27 2315 299 76.6%
30 2720 405 89.9%
33 2914 194 96.4%
36 2953 39 97.7%
39 2967 14 98.1%
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 181818
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51
0:00:00
0:07:14
0:58:10
1:16:12
1:49:41
%pass by delta%pass by delta--ZZ
deltadelta--ZZ
%pas
s%p
ass
Soak Soak TimeTime
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 191919
Example: Pin HeightExample: Pin HeightTESTER DUT X-COORD
(um)Y-COORD
(um) PROBE# PIN_HEIGHT (um)
0 -59903 -235432 1 15
0 -59903 -235432 2 18
0 -59903 -235432 3 18
0 -59903 -235432 4 15
0 -59903 -235432 5 18
0 -59903 -235432 6 18
0 -59903 -235432 7 15
… … … … …
… … … … …
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 202020
SystemSystem--toto--System Planarity CorrelationSystem Planarity Correlation
-200000
-100000
0
Y
-100000 0 100000
X
-200000
-100000
0
Y
-100000 0 100000
X
-200000
-100000
0
Y
-100000 0 100000
X
-200000
-100000
0
Y
-100000 0 100000
X
TSTR1 TSTR2
TSTR3 TSTR4
Legend
Pin Height (um)<= 0.000<= 5.833<= 11.667<= 17.500<= 23.333<= 29.167<= 35.000> 35.000
Problem Test Cell
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 212121
Test Cell Problem ResolutionTest Cell Problem Resolution
• Planarity signature: Inverted bowl
• Root cause: Prober chuck curvature
• Solution: Replaced prober chuck
<=-35um<=-15um
0um
Prober Chuck Profile
-200000
-100000
0
Y
-100000 0 100000
XTSTR4
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 222222
SystemSystem--toto--System Tilt CorrelationSystem Tilt Correlation
Best Fit Linear Plane
TSTR1 TSTR2 TSTR3 TSTR4
TSTR1 TSTR2 TSTR3 TSTR4 Range
Pitch (µrad) 41 42 53 5 48
Roll (µrad) 30 5 44 24 39
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 232323
OpticalOptical--toto--Electrical CorrelationElectrical Correlation
-300000
-250000
-200000
-150000
-100000
-50000
0
Y
-200000 -150000 -100000 -50000 0 50000 100000
X
-200000
-100000
0
Y
-100000 0 100000
X
Electrical (EF2L)
Legend
Pin Height (um)<= 0.000<= 5.833<= 11.667<= 17.500<= 23.333<= 29.167<= 35.000> 35.000
Pitch (µrad) 49
Roll (µrad) 13
Pitch (µrad) 54
Roll (µrad) 45
Optical (PTPA)
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 242424
Probe Card Technology BenchmarkProbe Card Technology Benchmark
Legend
Pin Height (um)<= 0.000<= 5.833<= 11.667<= 17.500<= 23.333<= 29.167<= 35.000> 35.000
-300000
-200000
-100000
0
Y
-100000 0 100000
X
-300000
-200000
-100000
0
Y
-100000 0 100000
X
Technology
- A
Excellent Planarity Planarity Out Of Spec
*Both probe cards 1TD 300mm
Technology
- B
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 252525
• Meeting the challenge– High parallelism (1TD 300mm)– Thermal deflection– High probe count– Shrinking bond pads
• EF2L is a key component in understanding probe card planarity– Electrical planarity spec validation– System-to-system correlation– Probe card technology benchmark– Thermal profile / soak– Identify other test cell issues, such as prober chuck curvature and
system deflection
SummarySummary
June 8 to 11, 2008June 8 to 11, 2008June 8 to 11, 2008 IEEE SW Test WorkshopIEEE SW Test WorkshopIEEE SW Test Workshop 262626
Thank You!Thank You!