Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Achieving Low Contact Resistance onAluminum Using Pyramid Probe Tips with
MicroscrubTM Technology
Ken Smith, Cascade MicrotechSWTW 1999
Pyramid Probe’s New Facility (Formerly Etec Building)
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Outline
1. Industry Requirements
2. Microscrub Technology Operation
3. Current Implementation
4. Sematech/Sandia Evaluation
5. Lucent Evaluation
6. Intel Evaluation
7. Summary
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Industry Requirements
● Contact resistance reliably less than 1.0ohm
● Minimize pad damage● Minimize scrub for small bond pads and
fine pitch● Minimal cleaning and maintenance● DESIGN REQUIREMENT: Uniform scrub
independent of position on the probe
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Microscrub Tip with Integral Beam
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Microscrub Principles of Operation
● Integral beam
● Offset forces
● Compliant backing
● Rotational moment
● Uniform scrub for all probe tips
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Initial Microscrub Implementation(1996)
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Typical Initial Contact ResistanceResults (1996)
Contact Resistance during Life Test
00.050.1
0.150.2
0.250.3
0.350.4
0.450.5
1460
00
1560
00
1660
00
1760
00
1860
00
1960
00
2060
00
2160
00
2260
00
2360
00
2460
00
2560
00
Minimum
Maximum
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Current Microscrub Implementation(1998)
● Smaller tips (30 >> 15 microns)● Taller tips (30 >> 60 microns)● Less probe force (20 >> 10 grams)● Engineering DOE parameters:
– Independent variables: Beam length,thickness, tip height, tip diameter,elastomer durometer, thickness, force pertip
– Indicators: Contact resistance,compliance, interaction with wafercontamination
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Pyramid Probe Tips with MEMsProcess
9 M I C R O T E C HCASCADETM
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Evaluation at Sandia
● Same set up as SWTW ‘98 Sematechcantilever probe data
– Three point Kelvin– HP 4062– EG 4090– Sematech funded facility
● No cleaning
● Stepped off wafer multiple times
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Pyramid Probe Contact Resistancefrom Sandia Lifetest (@ 85 C)
Lifetest at Sandia on a blank aluminum wafer
0 10 20 30 40 50 60 70 80
90 100
110120
160
170
180
190200
210
220230
240
250260
270
280
320
330
340
350360
370
380
390
400410
420
430440
Touchdowns (x 1000)(box plot without tails comparative to data shown at SWTW '98
page 24)
0
0.5
1
1.5
2
2.5
3
Resistance (contact + signal line) (ohm
s)
(5 mil overtravel at 85 C)
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Conventional Cantilever Probe CardContact Resistance (@ 85 C)
SEMATECH Applied Precision, Inc.Advanced Probing Systems, Inc. Sandia National LabsSWTW ‘98
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Comparison of Cantilever (@ 30 C) vs.Pyramid (@ 85 C)
Lifetest at Sandia on a blank aluminum wafer
0 10 20 30 40 50 60 70 80
90 100
110120
160
170
180
190200
210
220230
240
250260
270
280
320
330
340
350360
370
380
390
400410
420
430440
Touchdowns (x 1000)(box plot without tails comparative to data shown at SWTW '98
page 24)
0
0.5
1
1.5
2
2.5
3
Resistance (contact + signal line) (ohm
s)
(5 mil overtravel at 85 C)
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Lucent Evaluation: 200K Cycles WithNo Cleaning
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0TD
2KTD
13KTD
24KTD
35KTD
46KTD
46KIN
IT56
KTD67
KTD82
KTD11
1K13
3K17
7K21
0K
loop res AVGcres STDDEV
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Typical Pyramid Probe and Cantilever Marks
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Single Pyramid Mark SEM
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
One Cantilever, Two Pyramid Scrub Marks
1
21
41
61
81
S1S8
S15
S22
S29
S36
S43
S50
S57
S64
S71
S78
S85
S92
S99
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
Z - height (microns)
X - one division = one micron
Y - one division = one micron
One Cantilever and two Pyramid Probe scrub marks from Sandia Labs test wafer
2.5-32-2.51.5-21-1.50.5-10-0.5-0.5-0-1--0.5-1.5--1
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Intel Multi-DUT FlashRAM
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Multi-DUT Testing of FlashRAM
● 2 X 5 Multi-DUTprobe layout forFlashRam devices
● 500 I/O● 25 mm square
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Standard Internal Infant Lifetest
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
1 70 139 208 277 346 415 484 553 622 691 760 829 898 967 1036
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Acknowledgements
● NIST/ATP, DARPA, Sandia Labs,Sematech
● Rey Rincon, Phil Seitzer, DaveUnzicker, Khe Ting
● About 30 Cascade team members
Advanced Microelectronic Probing Solutions M I C R O T E C HCASCADE TM
Summary
● This is the first time Membrane probes havepublished excellent contact resistance and lifetest results on aluminum
● Small contacts and small scrub distancedrastically reduce pad damage and allow smallerpads
● Uniformly engineered consistent Microscrub isthe magic that makes it work
● Microscrub contact structure is compatible withfine pitch, array, multitest and high frequencyapplications
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