![Page 1: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/1.jpg)
Transferable Fine‐Pitch Probes
S.L. Wright, Y. Liu, B. Dang IBM T.J. Watson Research Center
![Page 2: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/2.jpg)
Overview• Motivation (3D Si, “smart” probe)• Transferrable probe tip process• Issues• Test vehicles, apparatus• Contact resistance, force, max current• Touchdown quality to date• Probe stations in the future
2S.L. Wright
![Page 3: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/3.jpg)
3S.L. Wright
2008
![Page 4: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/4.jpg)
3D IntegrationBenefits Challenges
Reduced package thickness and area
Bond and assembly
Reduced package complexity
Cooling
Improved performance(fine pitch & short length
interconnections)
Design methodology
Mixed chip technologies Test for KGD, KGS
Reduced cost (holistic view)
Increased cost (Si processing viewpoint)
4
Future-fab.com
S.L. Wright
![Page 5: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/5.jpg)
5S.L. Wright
Fine Pitch / 3D Probing
“SMART”
Silicon wafer
Low frequency board
Silicon chuck
Integrated 3D Si probe headw/ drive circuitry, multiplexing, data processing
TSV space transformation
Transferable probe tips
“”CTE-matched”
Example: L. Namburi, G. Maier SWTW 2013
“Poll” the SMART probe for analyzed test results
S.L. Wright
![Page 6: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/6.jpg)
6
Transferable Tips
silicon mold (anisotropic etch) Fill with metal and build metal pillar
TestRelease
S.L. Wright
![Page 7: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/7.jpg)
1st Generation
Tips are 4-sided pyramids with 70.5 degree cone angle.
S.L. Wright
![Page 8: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/8.jpg)
2nd Generation
S.L. Wright
![Page 9: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/9.jpg)
9
Solder recovery at 250°C in formic acid atmosphere.
Transferable probe tips on 50 µm 3D silicon chip
Uniform probe marks
S.L. Wright
![Page 10: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/10.jpg)
Transferable Tips• Low‐temp process • Variety of possible tip materials• Variety of possible substrates
– Silicon, ceramic, glass, laminate, MEMs structure
• Precise size, shape, location• Precisely planar• Non‐compliant versions to‐date
– Large compliance requires MEMs structure
10S.L. Wright
![Page 11: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/11.jpg)
IBM Zurich Nanotip (2014)• “nm‐sized” tip, 1000 °C• “chisel” into polymer • 10 nm resolution• ≤ 40nm penetration• 11x14 µm Panda image in
11 minutes• 30 µm wide Canada
image, 1 Mpix in 1 min? (McGill Univ)
• Licensed to SwissLitho– “NanoFrazor”
S.L. Wright11
![Page 12: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/12.jpg)
12S.L. Wright
Fine Pitch / 3D Probing
“SMART”
Silicon wafer
Low frequency board
Silicon chuck
Chip stack Chip stackChip stack
S.L. Wright
![Page 13: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/13.jpg)
smart
13
Silicon Wafer
Hybrid Probe Mode
S.L. Wright
positioner Conventional cantilever probes (coarse pitch).
![Page 14: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/14.jpg)
14S.L. Wright
“Smart” TCA
Hybrid Probe Mode w/“Smart” Temporary Chip Attach (TCA) Wafer
“Smart” TCA “Smart” TCA
S.L. Wright
positioner
Silicon Wafer
![Page 15: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/15.jpg)
Issues• Convert processor chip into probe head
– Low‐temp tip transfer process on thin die
• Need 3D Si technology for space transformer • Tip integrity and contact
– Vertical indent (no scrub) with small force– Thermal expansion issues with high‐power test?– Compliance needed?
• Damaged probe head?– Throw it away!
15S.L. Wright
![Page 16: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/16.jpg)
Compliance / Planarity• High interconnection yield with flip‐chip bond
– Routine lab yield 99.999 to 99.9999 % (50 µm pitch)– Pads/melted bumps → ps/bumps
• Probe compliance issues– Bump plating non‐uniformity scales with thickness
• 10% of 100 µm bump (200 µm pitch) is 10 µm• 10% of 15 µm bump (50 µm pitch) is 1.5 µm
– Probe non‐uniformity• Large over‐drive required for many probe technologies• Not an issue with transferable tips.
– Particle contamination • Do we need compliance?
16S.L. Wright
![Page 17: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/17.jpg)
17
0.5
0.4
0.3
25 C
60 C
90 C
4.9
3.6
2.5
3.7
3.3
2.2
3.5
3.2
2.0
1
1.5
2
2.5
3
3.5
4
4.5
5
Prob
e M
ark
Dep
th (u
m)
Force (gram/tip)
Probe Mark Characterization
25 C60 C90 C
Probe Mark Depth vs Force and Temperature
Flipchip “Tackdown”SnAg
S.L. Wright
![Page 18: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/18.jpg)
18
PA300 (Suss/Cascade)
platen
chuck side
scope
Chuck camera:Probe theta correctionProbe mark positionParallelism
Platen camera:Chuck thetaDie mark position“blob” position
Side camera:Height adjustment“near contact” viewRough parallelism
Scope camera:Initial setupParallelismPost-test inspection
Note: none of the axes are perfectly aligned.
Manual alignment procedure developed:X-Y alignment = +/- 1 mZ-parallelism ~ 2 m at 10 mm (0.01 deg)
S.L. Wright
![Page 19: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/19.jpg)
Probe Card
19
Observation holes
Force sensors
wirebondsProbe die with tips
S.L. Wright
![Page 20: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/20.jpg)
Hybrid Mode
20S.L. Wright
Manual probes
Bottom chuck w/probe tip die
Top vacuum chuck w/bumped die
![Page 21: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/21.jpg)
Force Plot
Touchdown has “stabilized” when all four forces increase at the same rate.
S.L. Wright
![Page 22: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/22.jpg)
Probe Marks
22S.L. Wright
8x8 m pyramid indent = 5.6 m indent tip depth
“max” indent
![Page 23: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/23.jpg)
23
Test Vehicle
Contact resistance sites (4-pt)
50 m pitch45,406 bumps (total)12,644 electrically-testable bumpsChain lengths from 1 to 230 links
S.L. Wright
Top die (bumped)
Bottom die (tip transfer)
![Page 24: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/24.jpg)
3‐pt Contact Resistance
24S.L. Wright
Additional force of ~ 0.01 gm/bump reduced contact resistance by ~ 40 m.
![Page 25: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/25.jpg)
4‐pt Contact Resistance
25
Rc depends upon probe force, “good” contact at 0.05 - 0.5 g/bump.Lowest Rc measured thus far ~ 30 mΩTypical Rc = 10-30 mΩ in joined parts (melted bump/pad)
S.L. Wright
![Page 26: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/26.jpg)
Contact Resistance and Force
26S.L. Wright
![Page 27: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/27.jpg)
Chain Resistance
Linear fit to data up to 21 links.
Touchdown contact yield of 99.9% demonstrated thus far. -Limited by test parameters, not test vehicle.
S.L. Wright
Longer chains include some high-R contacts.
![Page 28: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/28.jpg)
DC Current Stress: 2‐bump chain
Joule heating Dwell = few minutes
Joule heating apparent at ~ 500 mA……1A short‐duration current should be acceptable.
S.L. Wright
Still working!
![Page 29: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/29.jpg)
Power Dissipation in 2‐bump Chain
~100 W/mm2 !!!
S.L. Wright
![Page 30: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/30.jpg)
Post‐Mortem
Current = 2ACurrent = 2A
S.L. Wright
![Page 31: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/31.jpg)
Post‐Mortem (cont’d)Solder residue
Pull‐out on bump side
Tip indent w/oxidation
S.L. Wright
![Page 32: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/32.jpg)
Touchdown Alignment• Stage movement accuracy ~ ± 1 µm (x,y,z)• Homemade “semi‐automatic” alignment procedure
– X,Y,ϴ→ ∆x, ∆y ~ ± 1 µm
• Parallelism is biggest challenge– No auto‐leveling capability in prober (co‐parallelism)– Have not yet found conditions for “gimbal‐ing”– ∆z ~ ± 2 µm over 12 mm die (0.01 deg tilt)
• No probe damage or debris seen thus far– < 100 touchdowns
32S.L. Wright
![Page 33: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/33.jpg)
• Area‐array probing at pitches < 50 µm– > 100,000 connections
• Clean tool environment• Flip‐chip bonder capabilities
– Soften or melt solder– Controlled ambient
• Vacuum , plasma, formic acid ….
• Inexpensive, high‐performance “smart” probe heads
S.L. Wright33
Future Probe Stations
![Page 34: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/34.jpg)
Transferrable Probe Tip (TPT) technology
• Fine‐pitch capability– < 50 m
• Active‐device probe head (“smart probe”)– Low cost, high‐speed test
• Vertical probe without compliance– Minimal damage and debris– High current capability– Disposable probe head
S.L. Wright 34
![Page 35: Transferable Fine Pitch Probes - SWTest.org · S.L. Wright 5 Fine Pitch / 3D Probing “SMART” Silicon wafer Low frequency board Silicon chuck Integrated 3D Si probe head w/ drive](https://reader033.vdocuments.site/reader033/viewer/2022050201/5f548ad9f369ae7d0e0ecc6e/html5/thumbnails/35.jpg)
300 mm wafer capability…..
S.L. Wright