Online Semi-radius Probe Tip Cleaning and Reshaping
Online Semi-radius Probe Tip Cleaning and Reshaping
Online Semi-radius Probe Tip Cleaning and Reshaping
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<strong>Online</strong> <strong>Semi</strong>-<strong>radius</strong> <strong>Probe</strong> <strong>Tip</strong> <strong>Cleaning</strong><br />
<strong>and</strong> <strong>Reshaping</strong><br />
Authors:<br />
Sam McKnight <strong>and</strong> Michael Agbesi<br />
June 3, 2007<br />
IEEE SW Test Workshop 1
Agenda<br />
Acknowledgements<br />
Background info<br />
Setup <strong>and</strong> measurement technique<br />
Contact resistance results<br />
<strong>Cleaning</strong> recipe parameters to consider<br />
Silicone vs polymer based materials<br />
Summary<br />
Future work<br />
June 3, 2007<br />
IEEE SW Test Workshop 2
Acknowledgements<br />
Jack Courtney<br />
John Cartier<br />
Steve Duda<br />
Les Griffith<br />
Rob Holwager<br />
Glen Langsman<br />
Josh Pendergast<br />
June 3, 2007<br />
IEEE SW Test Workshop 3
Basic cantilever probe types<br />
June 3, 2007<br />
IEEE SW Test Workshop 4
Why <strong>Semi</strong>-<strong>radius</strong>?<br />
Lower pad damage in general for today’s<br />
soft aluminum<br />
Approximately same scrub length as flat tip<br />
while reducing the amount of material<br />
removed from base material<br />
Equivalent contact resistance to flat or full<br />
<strong>radius</strong> tip<br />
Reflectivity similar to flat tip for prober <strong>and</strong><br />
probe metrology alignment (easier to align<br />
to vs. full <strong>radius</strong> material)<br />
June 3, 2007<br />
IEEE SW Test Workshop 5
Bonding – <strong>Semi</strong> <strong>radius</strong> tips<br />
Pad opening shown is 29X29 microns - running out of room!<br />
June 3, 2007<br />
IEEE SW Test Workshop 6
The problem with <strong>Semi</strong>-<br />
<strong>radius</strong>ed probes<br />
Variable tip geometry using st<strong>and</strong>ard<br />
material cleaning solutions<br />
No insitu solution – non silicone based<br />
Either flat tip or <strong>radius</strong>ed tip solution but no<br />
semi-<strong>radius</strong>ed solution<br />
June 3, 2007<br />
IEEE SW Test Workshop 7
Traditional way to maintain semi-<strong>radius</strong><br />
probe tips<br />
Use elastomeric abrasive i.e.<br />
polymer based material – continues<br />
to <strong>radius</strong> tips<br />
Remove periodically to reshape (put<br />
a flat back on it)<br />
June 3, 2007<br />
IEEE SW Test Workshop 8
The solution<br />
Two part cleaning – insitu<br />
‣ Abrasive material for flat tip – SiC<br />
‣ Elastomeric material for <strong>radius</strong> tip<br />
<strong>and</strong> removes stringers (contact<br />
pad <strong>and</strong> cleaning detritus)<br />
June 3, 2007<br />
IEEE SW Test Workshop 9
Two basic cleaning mediums<br />
Two part cleaning – insitu<br />
‣ Solid Abrasive material for flat tip – SiC<br />
(Silicon Carbide)<br />
‣ Elastomeric material for <strong>radius</strong> tip <strong>and</strong><br />
removes stringers (contact pad detritus)<br />
‣ Order is important – see data<br />
June 3, 2007<br />
IEEE SW Test Workshop 10
June 3, 2007<br />
Typical recipes<br />
5 -10 up/down touchdowns on each medium<br />
‣ SiC abrasive removes all detritus down to<br />
base material (flat tip)<br />
‣ Elastomeric abrasive -removes<br />
probing/cleaning detritus (<strong>radius</strong> tip)<br />
Use same OD as with product for SiC, OD +<br />
30% for elastomeric (typical) - pitch dependant<br />
Move to new location between Up/Down<br />
cycles<br />
IEEE SW Test Workshop 11
Polymer based abrasive clean<br />
Before clean<br />
After clean<br />
June 3, 2007<br />
IEEE SW Test Workshop 12
Contact resistance - Elastomeric<br />
5<br />
4.5<br />
4<br />
Elastomeric cleaner<br />
50um OD 25C clean freq 100 die<br />
Wafer average 0.59 ohms<br />
Cres(ohms)<br />
3.5<br />
3<br />
2.5<br />
2<br />
1.5<br />
Min<br />
Max<br />
Average<br />
1<br />
0.5<br />
<strong>Cleaning</strong> cycle<br />
0<br />
1<br />
501<br />
1001<br />
1501<br />
2001<br />
2501<br />
3001<br />
3501<br />
4001<br />
4501<br />
Test #<br />
5001<br />
5501<br />
6001<br />
6501<br />
7001<br />
7501<br />
June 3, 2007<br />
Each "test" represents 25 contacts (190K data points total)<br />
opens removed from average data – all CRES charts<br />
IEEE SW Test Workshop 13
Contact resistance – silicon carbid<br />
SIC abrasive<br />
50um OD 25C clean freq 100 die<br />
Cres(ohms)<br />
5<br />
4.5<br />
4<br />
3.5<br />
3<br />
2.5<br />
2<br />
1.5<br />
1<br />
0.5<br />
0<br />
Wafer average 0.10 ohms<br />
Min<br />
Max<br />
Average<br />
<strong>Cleaning</strong> cycle<br />
1<br />
501<br />
1001<br />
1501<br />
2001<br />
2501<br />
3001<br />
3501<br />
4001<br />
4501<br />
5001<br />
5501<br />
6001<br />
6501<br />
7001<br />
7501<br />
Test #<br />
June 3, 2007<br />
IEEE SW Test Workshop 14
Contact resistance – dual clean<br />
JEM elsatomeric & SIC abrasive<br />
50um OD 25C clean freq 100 die<br />
Each "test" represents 25 contacts (190K data points)<br />
5<br />
4.5<br />
4<br />
Wafer average 0.40 ohms opens<br />
removed from average data<br />
Cres(ohms)<br />
3.5<br />
3<br />
2.5<br />
2<br />
1.5<br />
1<br />
Min<br />
Max<br />
Average<br />
0.5<br />
0<br />
1<br />
501<br />
1001<br />
1501<br />
2001<br />
2501<br />
3001<br />
3501<br />
4001<br />
Test #<br />
4501<br />
5001<br />
5501<br />
6001<br />
6501<br />
7001<br />
7501<br />
S. McKnight<br />
05/02/2007<br />
<strong>Cleaning</strong> cycle<br />
June 3, 2007<br />
IEEE SW Test Workshop 15
Contact resistance setup <strong>and</strong><br />
measurement technique<br />
TEL P12XLN prober @ 25C, Maximum z velocity<br />
<strong>Probe</strong> – 50 micron pitch 1X25 tungsten rhenium<br />
material, 20 micron nominal tip diameter ~ 1gf/mil spring<br />
rate<br />
50 micron overdrive from first touch (contacts were<br />
within 9 microns from first to last touch)<br />
100 touchdowns between cleans<br />
Relative measurement – not 4 point<br />
All data “nulled” – path or bulk resistance removed<br />
300mm wafer – 1.2 micron as deposited aluminum –<br />
blanket deposition<br />
June 3, 2007<br />
IEEE SW Test Workshop 16
Measurement circuit<br />
• Test stimulus 10 ma forcing current – 5V clamp<br />
• Min - Max - Average data collected plus raw data<br />
• Keithley based matrix switch <strong>and</strong> source/measurement unit<br />
VI source<br />
Contact under<br />
test<br />
Return path<br />
June 3, 2007<br />
Shorted wafer<br />
Note: actual return path pins = 24<br />
IEEE SW Test Workshop 17
Polymer based abrasive clean<br />
SiC abrasive<br />
<strong>Probe</strong> tip<br />
Abraded area – largest area expose to cleaning medium<br />
June 3, 2007<br />
IEEE SW Test Workshop 18
SiC clean<br />
Typical flat tip Silicon Carbide abrasive – 3µm<br />
June 3, 2007<br />
IEEE SW Test Workshop 19
“Recipe” Considerations<br />
<strong>Probe</strong> characteristics<br />
‣ <strong>Tip</strong> diameter<br />
‣ <strong>Tip</strong> length<br />
‣ Taper<br />
‣ Spring rate<br />
‣ Material<br />
<strong>Cleaning</strong> order<br />
‣ Lowest CRES use SIC last<br />
June 3, 2007<br />
‣ Maximum particulate removal use<br />
Elastomeric last<br />
IEEE SW Test Workshop 20
Sequence <strong>and</strong> motion (use animation)<br />
Elastomeric<br />
material<br />
SIC material<br />
June 3, 2007<br />
IEEE SW Test Workshop 21
Benefits<br />
Low cost solution – use existing materials<br />
Comparable CRES to SiC material<br />
Non Silicone<br />
Uniform tip shape throughout life of probe<br />
Longer probe life<br />
June 3, 2007<br />
IEEE SW Test Workshop 22
Detractor<br />
Die Size limited – effectively cut cleaning<br />
area in half<br />
June 3, 2007<br />
IEEE SW Test Workshop 23
142 mm<br />
155 mm<br />
<strong>Cleaning</strong><br />
summary<br />
Flat material<br />
Radius material<br />
<strong>Semi</strong>-Radius tip<br />
+ =<br />
June 3, 2007<br />
IEEE SW Test Workshop 24
142 mm<br />
155 mm<br />
Future work<br />
Evaluate even lower cost materials<br />
Look for extension to other probe<br />
technologies i.e. Cobra, metrology usage<br />
Maximize cleaning medium lifetime<br />
Larger cleaning plate<br />
Thank you! Questions?<br />
June 3, 2007<br />
IEEE SW Test Workshop 25