Research Results OverviewResearch Results Overview

Review of former work on instantaneous fluid Review of former work on instantaneous fluid film thickness measurementsfilm thickness measurements

Most recent friction dataMost recent friction data Calibration for film thickness measurementsCalibration for film thickness measurements Friction and film thickness correlationFriction and film thickness correlation Imaging issuesImaging issues Patterning and profiles for pad Deformation Patterning and profiles for pad Deformation

StudiesStudies Static images of patterned wafersStatic images of patterned wafers Preliminary dynamic pad deformation results.Preliminary dynamic pad deformation results.

Results from last year: Slurry Results from last year: Slurry thickness in timethickness in time

The first Instantaneous fluid film thickness The first Instantaneous fluid film thickness measurements in time show some periodicity.measurements in time show some periodicity.

Friction vs TimeFriction vs Time

No apparent pattern at standard run conditions.No apparent pattern at standard run conditions. Pictured below are fiction measurements at Pictured below are fiction measurements at

“slow” rotation speeds show periodicity.“slow” rotation speeds show periodicity.

Reproduction of Friction Reproduction of Friction DataData

Pad/Wafer Rotation = 60 RPMPad/Wafer Rotation = 60 RPM Slurry Flow = 50 cc/minSlurry Flow = 50 cc/min Friction sample rate = 1000HzFriction sample rate = 1000Hz

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Time (s) 0 5 10 15 20 25 30 0 5 10 15 20 25 30

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Accurate Film Thickness Accurate Film Thickness CalibrationCalibration

2 Microscope slides are 2 Microscope slides are shimmed with 80shimmed with 80m m double stick tape.double stick tape.

The end opposite the The end opposite the tape is assumed to have tape is assumed to have a thickness of 0.a thickness of 0.

Slurry is inserted Slurry is inserted between the slides with between the slides with know slope.know slope.

Height = 40Ratio - 14

Film Thickness Film Thickness MeasurementsMeasurements

““Standard Conditions”: Pad/Wafer Rotation Standard Conditions”: Pad/Wafer Rotation = 60 RPM, Slurry Flow = 50 cc/min.= 60 RPM, Slurry Flow = 50 cc/min.

Film Thickness Measurements Film Thickness Measurements “Slow” Rotation“Slow” Rotation

Film thickness for pad/wafer rotation speed = 5rpm.Film thickness for pad/wafer rotation speed = 5rpm.

Is there a correlation?Is there a correlation?

Accurately time stamp images.Accurately time stamp images. Time between laser pulsesTime between laser pulses Time at which the camera takes the pictureTime at which the camera takes the picture

Correlate pulse (~2Hz) with Friction (1000Hz)Correlate pulse (~2Hz) with Friction (1000Hz)

Friction and Film Thickness at Friction and Film Thickness at “Standard” conditions“Standard” conditions

Extreme ImagesExtreme Images•This image has approximately uniform intensity.•There is slurry on top of the wafer creating a dark circle.

•This image has variable intensity.•The dark areas might be bubbles passing beneath the wafer or areas where the pad and wafer are in contact.

Summary of Friction ResultsSummary of Friction Results

Accurately Correlate FrictionAccurately Correlate Friction No Apparent CorrelationNo Apparent Correlation

Fluid film thickness is measured locally Fluid film thickness is measured locally whereas friction is measured over the whereas friction is measured over the entire wafer.entire wafer.

Images need to be examined Images need to be examined individually. A more appropriate region individually. A more appropriate region of interest should be selected.of interest should be selected.

Pad Deformation StudiesPad Deformation Studies

Two Patterning Two Patterning MethodsMethods Spin coating with a Spin coating with a

tape masktape mask HF acid etchHF acid etch

Observation MethodObservation Method Collect Surface Collect Surface

ProfilesProfiles Static DELIF ImagingStatic DELIF Imaging Dynamic DELIF Dynamic DELIF

ImagingImaging

Profilometer Images of HF Profilometer Images of HF Etched WaferEtched Wafer

3D Construction 2D Profile

Profilometer Images of Spin Profilometer Images of Spin Coated WaferCoated Wafer

Static Images of HF Patterned Static Images of HF Patterned waferwafer

Static Images of Spin Coated Static Images of Spin Coated WaferWaferThe difference in the average value of the ratio is .05, corresponding to a 2 m step.

The coating seems to chemically weather after prolonged exposure to the slurry.

Dynamic Images of HF Etched Dynamic Images of HF Etched waferwafer

•Many Images were flooded in around the edges of the wafer.

•Epoxy made the images grainy.•The wafer looked flat during

polishing.•Post-polishing there was there

was little change in step height.

Summary of Pad Summary of Pad DeformationDeformation

There are 2 successful patterning There are 2 successful patterning methods.methods.

Static DELIF image data seems to Static DELIF image data seems to reproduce profilometer data.reproduce profilometer data.

Dynamic DELIF has not reproduced Dynamic DELIF has not reproduced profilometer data, but the technique profilometer data, but the technique is still under developmentis still under development

Proposal for next DataProposal for next Data

FictionFiction Why are we not seeing a correlation between Why are we not seeing a correlation between

friction and film thickness?friction and film thickness? Develop new method to select region of interest that Develop new method to select region of interest that

corresponds to friction measurementscorresponds to friction measurements Determine the origin of low intensity regionsDetermine the origin of low intensity regions

Pad DeformationPad Deformation How accurately can we measure deformation in How accurately can we measure deformation in

situ?situ? Dynamic measurements of HF etched and spin coated Dynamic measurements of HF etched and spin coated

waferswafers Develop techniques for attaching the etched wafer to the Develop techniques for attaching the etched wafer to the

polisher for better optics.polisher for better optics.