Strasbaugh Calibration Variables
17
Number: 97 Value: 0.0 Label: Probe Options 0=No
This used to be called “Raise Probe Before Dwell.” In software versions
5.04-5.07, it became a two-digit number with different meanings assigned to
each digit. For the one’s digit,
0 Raise the probe after the Dwell step of the recipe.
1 Raise the probe before the Dwell step of the recipe.
Sometimes the probe etched a circle onto the wafer during the Dwell. If so,
the one’s digit was set to raise the probe before it could do that. The price
of this protection was that the Dwell step had less useful information in the
Grind Data file.
In software versions 6.00 and 6.01, new choices were added for the one’s
digit, allowing Semi-Probeless and Fully Probeless Grinding.
0 Raise the probe after the Dwell step of the recipe.
1 Raise the probe before the Dwell step of the recipe.
2 Raise the probe after fine grind step 3
3 Raise the probe after fine grind step 2 (semi-probeless)
4 Raise the probe after fine grind step 1 (semi-probeless)
5 Never lower the probe during grind (fully probeless)
6-9 Undefined; same as 0.
Another probe option, originating in software version 5.04, is useful for
wafers with wavy or irregular surfaces. With the chuck rotating at 20 rpm,
take several probe readings around the entire wafer. Use the highest
“mountain” to determine the approach height, that is, the height to which the
grind wheel can be lowered at high speed. Use the lowest “valley” to
calculate the target thickness for delta grind. Without selecting this
Approach Option, the normal behavior is to use one probe reading for both
of these calculations. The price of the Approach Option is the time spent in
accelerating/decelerating the work chuck and the time spent taking probe
readings. On a Pentium 133 MHz computer, the total time is about ten
seconds per wafer. To activate the Approach Option, place a 1 into the ten’s
digit of this variable.
In software version 6.00 this was improved to calculate low, high, and
average probe readings, and to allow you to select any of these three to
calculate the target thickness for delta grind or for Ind Wafer grind. Set the
ten’s digit to 1,2,3 for these three choices.
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