Innovative Probe Needle Cleaning Techniques

AppliedPrecision
Productivity solutions for a small world
Innovative Probe Tip
Cleaning
Techniques
James Andersen
Applied Precision Inc.
(425) 557-1000
jander@api.com
© 1998 Applied Precision, Inc.

Industry Survey
• What are the suspected contaminants?
• What is thought to cause high Contact
Resistance?
– Aluminum Oxide
– Anti-reflectives
– Tungsten Oxide
– Passivation
– Silicon Nitride
– Tri-nitrides
– Polymers & Fluorocarbons (due to over etch)
– Lapping media (adhesive)
– Electrically activated buildup of dielectrics
– Outgassing of packing materials
© 1998 Applied Precision, Inc.

Industry Survey
• Compounds containing these elements
were identified using SEM & Auger
Analysis
– Oxygen
– Sulfur
– Chlorine
– Carbon
– Nitrogen
– Copper
– Aluminum
– Silicon
© 1998 Applied Precision, Inc.

Industry Survey
• How do you determine when a
card is “dirty”?
– It exhibits high contact resistance
– Yield fallout assumed to be a result of high Cres
– Reprobe failure rate doesn’t improve - assumed to be
a result of high Cres
– By visual inspection
© 1998 Applied Precision, Inc.

Industry Survey
• What methods do you use to
“clean”?
– Scrub on Tungsten Carbide
– Scrub on Lapping films
– Scrub on SandPaper
– Camel Hair dry brushing - to remove particulates
– IPA wet brushing
– Scrub on Ceramic
– Dish Soap followed by DI water
• What do you think reduces Cres??
– Abrasion, physically removing the “contaminants”
© 1998 Applied Precision, Inc.

Scrubbing on Tungsten Carbide
Effectively reduces contact resistance
20.00
18.00
16.00
14.00
12.00
1000 TD's
W SCRUB
OHMS
10.00
8.00
6.00
4.00
2.00
0.00
49
51
53
42
39
40
37
38
35
PROBE
36
33
34
31
32
29
30
27
20
18
16
1000 TD's
BUT...
© 1998 Applied Precision, Inc.

Abrasive Cleaning
• Abrasive Cleaning...
– Causes deformation of the tips
– Reduces Probe Card Life
– Produces additional contaminants
– Is incompatible with some probe card technology
A non-destructive
cleaning alternative
is needed!
© 1998 Applied Precision, Inc.

Chemicals and Solvents
• Sodium Hydroxide
• Potassium Hydroxide
Did not pursue evaluation of wet
chemicals due to restricted usage
in wafer fabrication environments
• Solvents
Process intensive usage and appear
to have little or no effect on contact
resistance.
© 1998 Applied Precision, Inc.

Chemicals
18.0000
16.0000
DEOXIT
5 Minute Bath in 100% Solution
Cres Before
14.0000
12.0000
10.0000
8.0000
6.0000
4.0000
2.0000
Cres After
0.0000
162
163
164
54
60
53
61
52
62
51
63
50
64
49
127
48
125
43
42
41
© 1998 Applied Precision, Inc.

Our Mission ...
To meet the industry requirement we
need to find a cleaning method that
is
Non-abrasive
Non-destructive
Non-chemical
Material Independent
© 1998 Applied Precision, Inc.
and EFFECTIVELY Reduces Contact
Resistance

Acoustic Pressure Waves
© 1998 Applied Precision, Inc.
TIPS IN AN ACOUSTIC FOUNTAIN

Acoustic Energy
High
Frequency
Acoustics
produce a
spatially
defined energy
field
PRESSURE FIELD AS A STANDING WAVE
© 1998 Applied Precision, Inc.

MegaSonic Acoustics
BEFORE CLEANING
AFTER CLEANING
© 1998 Applied Precision, Inc.
Radiation Pressure Forces and Localized
Microstreaming Effectively Remove
Particulates
However...

MegaSonic Acoustics
…Contact Resistance Increases!
10.000
9.000
8.000
AFTER
7.000
OHMS
6.000
5.000
4.000
3.000
2.000
BEFORE
1.000
0.000
47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 23 29 28 27 22 25 24
S1
© 1998 Applied Precision, Inc.
PROBE

Carbon Dioxide “Snow”
• Removes particles and organic
contamination
– High velocity gas
– Momentum Transfer
– Sublimation
18.00
Provides Excellent
Particle Removal
but Minimal
Contact Resistance
Improvement
ohms
16.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
Test 1
Test 2
0.00
49
51
53
42
39
40
37
38
35
36
channel
33
34
31
32
29
30
27
20
18
16
Test 1
© 1998 Applied Precision, Inc.

What Causes Contact Resistance?
This Card Has Never Touched a Wafer !
16.00
14.00
12.00
10.00
OHMS
8.00
6.00
4.00
2.00
0.00
49 52 51 54 53 64 42 63 39 66 40 65 37 68 38 67 35 70 36 69 33 2 34 1 31 4 32 3 29 6 30 5 27 8 20 17 18 15 16
CRes
PROBE
© 1998 Applied Precision, Inc.

Probe Card Storage
OHMS
1.40
1.20
1.00
0.80
0.60
Test 1
Test 2
Nitrogen
Purging/Vacuum
Sealing Controls
Contact Resistance
0.40
4.50
0.20
0.00
43
42
41
125
48
127
49
64
50
63
51
62
52
PROBE
Vacuum Sealed
61
53
60
54
162
163
164
Test 1
OHMS
4.00
3.50
3.00
2.50
2.00
Test 1
Test 2
1.50
Test Performed at
one week intervals
1.00
0.50
0.00
43
42
41
125
48
127
49
64
50
63
Stored in Air
51
62
52
PROBE
61
53
60
54
162
163
164
Test 1
© 1998 Applied Precision, Inc.

What Causes Contact Resistance?
Presence of Oxygen
Suggests Existence of
an Oxide Layer
© 1998 Applied Precision, Inc.

MicroCluster Beam Technology
© 1998 Applied Precision, Inc.

MicroCluster Beam Technology
© 1998 Applied Precision, Inc.

MicroCluster Beam Technology
© 1998 Applied Precision, Inc.

Rocket Science Reduces Resistance
25.00
20.00
Test 2 Test 1
15.00
OHMS
10.00
5.00
0.00
© 1998 Applied Precision, Inc.

MicroCluster Beam Technology
BEFORE
AFTER
MicroCluster Beam Cleaning Results in NO
Measurable Changes to Probe Alignment,
Planarity, or Tip Profile
© 1998 Applied Precision, Inc.

Summary
– Abrasive Scrubbing works, but is destructive.
– Chemicals can work, but are destructive and face
restricted usage in Fab environments.
– Solvents are messy and ineffective.
– High Frequency Acoustic Cleaning removes particulates
but increases contact resistance.
– CO 2
Snow removes particulates but did not reduce contact
resistance.
Is MicroCluster Beam Technology
the Solution?
© 1998 Applied Precision, Inc.

Conclusion
MicroCluster Beam Technology Exceeds Our
Mission Objectives
– Non-abrasive Method
– No Measurable Probe Wear or Damage
– Non-chemical
– Dry process - No Bakeout Required
– Independent of probe material, pitch, topography, type.
MicroCluster Beam Technology Effectively and
Consistently Reduces Contact Resistance!
© 1998 Applied Precision, Inc.