Online Semi-radius Probe Tip Cleaning and Reshaping · Probe – 50 micron pitch 1X25 tungsten...
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June 3, 2007 June 3, 2007 IEEE SW Test Workshop IEEE SW Test Workshop 1 1 Online Semi Online Semi - - radius Probe Tip Cleaning radius Probe Tip Cleaning and Reshaping and Reshaping Authors: Authors: Sam McKnight and Michael Agbesi Sam McKnight and Michael Agbesi
Transcript of Online Semi-radius Probe Tip Cleaning and Reshaping · Probe – 50 micron pitch 1X25 tungsten...
June 3, 2007June 3, 2007 IEEE SW Test WorkshopIEEE SW Test Workshop 11
Online SemiOnline Semi--radius Probe Tip Cleaning radius Probe Tip Cleaning and Reshapingand Reshaping
Authors: Authors: Sam McKnight and Michael Agbesi Sam McKnight and Michael Agbesi
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AcknowledgementsAcknowledgementsBackground infoBackground infoSetup and measurement techniqueSetup and measurement techniqueContact resistance results Contact resistance results Cleaning recipe parameters to considerCleaning recipe parameters to considerSilicone Silicone vsvs polymer based materialspolymer based materialsSummarySummaryFuture workFuture work
AgendaAgenda
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AcknowledgementsAcknowledgements
Glen LangsmanGlen LangsmanJosh PendergastJosh Pendergast
Jack CourtneyJack CourtneyJohn CartierJohn CartierSteve Steve DudaDudaLes GriffithLes GriffithRob Rob HolwagerHolwager
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Basic cantilever probe typesBasic cantilever probe types
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Lower pad damage in general for todayLower pad damage in general for today’’s s soft aluminumsoft aluminumApproximately same scrub length as flat tip Approximately same scrub length as flat tip while reducing the amount of material while reducing the amount of material removed from base materialremoved from base materialEquivalent contact resistance to flat or full Equivalent contact resistance to flat or full radius tipradius tipReflectivity similar to flat tip for prober and Reflectivity similar to flat tip for prober and probe metrology alignment (easier to align probe metrology alignment (easier to align to vs. full radius material)to vs. full radius material)
Why SemiWhy Semi--radius?radius?
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Bonding Bonding –– Semi radius tipsSemi radius tips
Pad opening shown is 29X29 microns - running out of room!
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The problem with SemiThe problem with Semi--radiused probesradiused probes
Variable tip geometry using standard material cleaning solutions No insitu solution – non silicone basedEither flat tip or radiused tip solution but no
semi-radiused solution
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Traditional way to maintain semiTraditional way to maintain semi--radius radius probe tipsprobe tips
Use elastomeric abrasive i.e. Use elastomeric abrasive i.e. polymer based material polymer based material –– continues continues to radius tipsto radius tipsRemove periodically to reshape (put Remove periodically to reshape (put a flat back on it) a flat back on it)
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The solutionThe solution
Two part cleaning – insitu
Abrasive material for flat tip – SiC
Elastomeric material for radius tip and removes stringers (contact pad and cleaning detritus)
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Two basic cleaning mediumsTwo basic cleaning mediums
Two part cleaning – insitu
Solid Abrasive material for flat tip – SiC(Silicon Carbide)
Elastomeric material for radius tip and removes stringers (contact pad detritus)
Order is important – see data
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Typical recipesTypical recipes5 -10 up/down touchdowns on each medium
SiC abrasive removes all detritus down to base material (flat tip)
Elastomeric abrasive -removes probing/cleaning detritus (radius tip)
Use same OD as with product for SiC, OD + 30% for elastomeric (typical) - pitch dependant
Move to new location between Up/Down cycles
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Before clean After clean
Polymer based abrasive cleanPolymer based abrasive clean
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Contact resistance Contact resistance -- ElastomericElastomeric
Each "test" represents 25 contacts (190K data points total) opens removed from average data – all CRES charts
Cleaning cycle
Elastomeric cleaner50um OD 25C clean freq 100 die
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
1
501
1001
1501
2001
2501
3001
3501
4001
4501
5001
5501
6001
6501
7001
7501
Test #
Cre
s(oh
ms) Min
MaxAverage
Wafer average 0.59 ohms
Cleaning cycle
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SIC abrasive50um OD 25C clean freq 100 die
00.5
11.5
22.5
33.5
44.5
5
150
110
0115
0120
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0130
0135
0140
0145
0150
0155
0160
0165
0170
0175
01
Test #
Cre
s(oh
ms) Min
MaxAverage
Wafer average 0.10 ohms
Cleaning cycle
Contact resistance Contact resistance –– silicon carbisilicon carbid
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Contact resistance Contact resistance –– dual cleandual cleanJEM elsatomeric & SIC abrasive50um OD 25C clean freq 100 die
Each "test" represents 25 contacts (190K data points)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
1
501
1001
1501
2001
2501
3001
3501
4001
4501
5001
5501
6001
6501
7001
7501
Test #
Cre
s(oh
ms) Min
MaxAverage
S. McKnight05/02/2007
Wafer average 0.40 ohms opensremoved from average data
Cleaning cycle
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Contact resistance setup and Contact resistance setup and measurement techniquemeasurement technique
TEL P12XLN prober @ 25C, Maximum z velocityTEL P12XLN prober @ 25C, Maximum z velocityProbe Probe –– 50 micron pitch 1X25 tungsten rhenium 50 micron pitch 1X25 tungsten rhenium material, 20 micron nominal tip diameter ~ 1gf/mil spring material, 20 micron nominal tip diameter ~ 1gf/mil spring raterate50 micron overdrive from first touch (contacts were 50 micron overdrive from first touch (contacts were within 9 microns from first to last touch)within 9 microns from first to last touch)100 touchdowns between cleans100 touchdowns between cleansRelative measurement Relative measurement –– not 4 pointnot 4 pointAll data All data ““nullednulled”” –– path or bulk resistance removedpath or bulk resistance removed300mm wafer 300mm wafer –– 1.2 micron as deposited aluminum 1.2 micron as deposited aluminum ––blanket depositionblanket deposition
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Measurement circuitMeasurement circuit
VI source
Return path
Shorted wafer
Contact undertest
Note: actual return path pins = 24
• Test stimulus 10 ma forcing current – 5V clamp
• Min - Max - Average data collected plus raw data
• Keithley based matrix switch and source/measurement unit
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Polymer based abrasive cleanPolymer based abrasive clean
SiC abrasive
Probe tip
Abraded area – largest area expose to cleaning medium
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SiCSiC cleancleanTypical flat tip Silicon Carbide abrasive – 3µm
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““RecipeRecipe”” ConsiderationsConsiderationsProbe characteristics
Tip diameter
Tip length
Taper
Spring rate
Material
Cleaning order
Lowest CRES use SIC last
Maximum particulate removal use Elastomeric last
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Sequence and motion (use animation)Sequence and motion (use animation)
Elastomeric material
SIC material
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BenefitsBenefits
Low cost solution – use existing materials
Comparable CRES to SiC material
Non Silicone
Uniform tip shape throughout life of probe
Longer probe life
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DetractorDetractor
Die Size limited – effectively cut cleaning area in half
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Cleaning Cleaning summarysummary
Radius materialFlat material
+ =Semi-Radius tip
155
mm
142 mm
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Future workFuture work15
5 m
m
142 mm
Evaluate even lower cost materials
Look for extension to other probe technologies i.e. Cobra, metrology usage
Maximize cleaning medium lifetime
Larger cleaning plate
Thank you! Questions?Thank you! Questions?
