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Examination of some key CMP input parameters on slurry fluid mechanics
PI: Chris Rogers
Researchers: Jonathan CoppetaChris Duska
Jeremy Javidi Samuel Brodsky
Corporate Sponsors: Cabot Corporation (Frank Kaufman)Intel Corporation (Ara Philipossian)VEECO Corporation
Numerical Simulations
Fluid Thickness
Thermal Gradients
Mixing Measurements
Polishing Data
ResultsYear 3Integration
Research Strategy
Friction Data Fd
Polishing Platform
100 RPMStruers RotoPol-31
Drill Press
Weighted Traverse
Two Aligned 12 BitCamera
Three Way Solenoid Valve
Tagged Slurry
Slurry
Design of Experiment
43 RunsVariables
-Pad Manufacturer (Cabot, Rodel, Freudenberg)-Pad Groove Depth (0-40 mils)-Wafer Down Force (2-6 psi)-Platen Speed (30-90 rpm)-Slurry Flow Rate (20-50 ml/min)
Constants-Groove Style (X-Y Grooving, 0.025” width)-Head Speed (60 rpm)-Head Position (3/4” wafer to platen edge)-Injection Location (pad center)-Conditioning (163 Micron diamond grit)
Slurry Transport
Interrogation Region
Wafer
Post
Examining;-Mean slurry age-Residence time-Slurry Gradients
(flat pads)-Drag on wafer-fluid thickness measurements
Pad
Repeatability
Flat Pad
Grooved PadManufacturer: CabotSlurry Flow Rate: 35 cc/minWafer Down Force: 4 psiPlaten Speed: 60 rpmX-Y Groove Depth: 20 mils
Time (sec)
Per
cen
t N
ew S
lurr
y
Repeatability
Flat Pad
Grooved Pad Manufacturer: RodelSlurry Flow Rate: 35 cc/minWafer Down Force: 4 psiPlaten Speed: 60 rpmX-Y Groove Depth: 20 mils
Time (sec)
Per
cen
t N
ew S
lurr
y
Slurry Flow Rate
Flat Pad
Grooved PadManufacturer: RodelSlurry Flow Rate: x cc/minWafer Down Force: 4 psiPlaten Speed: 60 rpmX-Y Groove Depth: 20 mils
Time (sec)
Per
cen
t N
ew S
lurr
y
Platen Speed
Manufacturer: FreudenbergSlurry Flow Rate: 35 cc/minWafer Down Force: 4 psiPlaten Speed: x rpmX-Y Groove Depth: 20 mils
Flat Pad
Grooved Pad
Time (sec)
Per
cen
t N
ew S
lurr
y
Static Case
Pad deformation: (4 psi, 0 rpm)
Image of a single pad Thickness profile as determined by ratiometric technique
-80
-70
-60
-50
-40
-30
-20
-10
0r/3
< edge center >
Prof
ile (m
icro
ns) 2 psi
4 psi
6 psi
wafer profile
Radial Profile (static cases)
Static Fluid Thickness Measurements
wafer
PAD
Trapped slurryTrapped slurry
Asperity?Asperity?Surface tension?Surface tension?
Friction Measurements
Cabot Pad6 psi down force35 cc/min30 rpm platen speed20 mils x-y groove depth
Friction Data~0.5 Hz Sine Wave
Time (sec)
Coe
ffic
ien
t of
Fri
ctio
n
Polishing Rates for Crown Glass
Polishing of Crown Glass
0
1000
2000
3000
4000
5000
0 0.2 0.4 0.6 0.8 1
% of Radius
Po
lish
ing
Ra
te
(A/m
in)
3.0” Diameter wafer
Polishing Rate vs Radius
0200400600800
100012001400
0 0.2 0.4 0.6 0.8 1
% of radius
Po
lish
ing
Ra
te (
A/m
in)
Polishing Rates for BK7
3.5” Diameter wafer
Conclusion
-Functional scaled down polishing platform•Polishing data•Slurry mixing measurements•Slurry film thickness measurements•Friction measurements
-Beginning of DOE analysis•Slurry mixing rates depend on:
Platen speedFlow rateIn situ conditioning
Future Directions
-Optimize Struers Polishing performance
-New DOE study on pad material properties
-Scale results to an industrial polisher
-Verify data on an IPEC 372 polisher
-Correlate fluid mechanics to polishing performance
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