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V.
APPLICATIONS
A.
Topside Delayering of Single Die IC’s
i.
Parallel Delayering Techniques
The standard lap for delayering used on the Advance is the 8 inch polyurethane lap. This is used with
0.05μm colloidal silica slurry. Make sure to have the drain plugged in the gray basin using the rubber
plug, otherwise fluid will drain. Use the recirculation pump to circulate the slurry back on to the lap.
With the system calibrated, sample mounted and aligned, lap, slurry and pump in place, you are now
ready to polish.
1.
Using the Z-micro adjust knob located at the top of the mast, lower the sample until you see a
deflection on the dial indicator of 20μm (each division on the dial indicator represents 10μm).
2.
Set pressure control to the lightest possible (turn pressure control knob CCW until the center-shaft
begins to lift and then back off a bit).
3.
Set the timer for desired length of time.
4.
Turn oscillation switch to ON and turn dial to desired speed.
5.
Turn rotation switch to ON and turn dial to desired speed.
6.
Pick lap direction.
7.
Turn pump on (point nozzle towards the area directly in front of the sample).
8.
Press START.
The amount of lap time varies from each sample type to sample type, driven by density of device,
composition and size of the die. A good starting point would be a one minute cycle to observe the
removal rate.
ii.
Tips for Delayering
•
Mounting the die, do not cover center hole with any thing, this includes wax, tape, and etc.
•
When first starting, remember orientation of die on puck, this will help you to correct for tilt later.
•
Start with a one minute lap time. This allows you to observe removal rate and tilt so that you may
adjust for them accordingly.
•
A slow rotation speed of the sample minimizes edge rounding effects.
•
You can adjust pressure by turning the pressure control knob (lightest pressure tends to work
best).
•
Smaller sweep amplitude ensures planarity.
•
Use the SECOND set of crosshairs as a reference to “OFFSET” for any tilt that arises from the
difference in planarity from topside to backside.
B.
Backside Preparation
i.
Package Level (e.g. Flip chip)
Mounting
First, decap a small window on topside so that Ultracollimator has a direct line of sight to a shiny
surface. This will be used to adjust for tilt. If not possible, just make sure to press down on the center
of the package to ensure that the thin wax layer has been minimized (this assumes that you are using
Crystal wax to hold sample to holder.)
