May 21, 2001 7AF Dual Fine Grind and Dual Coarse Grind
STRASBAUGH CONFIDENTIAL INFORMATION
1
7AF Dual Fine Grind and Dual Coarse Grind
05/21/2001 Steve Jacobson
Purpose
The 7AF has always been used with a coarse grind wheel on the left and a fine grind wheel on the right. To
perform only a fine grind or only a coarse grind, the grind cycle would use only one of those wheels. It is now
possible to attach two fine wheels or two coarse wheels and to operate the 7AF in a new mode that understands
that both wheels are the same. This is done primarily for Dual Fine Grind, where the throughput should increase
over the available throughput when using just one wheel. Dual Coarse Grind is also available.
Dual Fine Grind and Dual Coarse Grind are sold as option 248313.
How to Select the New Modes
Machine variable 48, Dual Coarse or Fine Grnd, allows you to set the values:
0 Traditional 7AF one coarse wheel on the left and one fine wheel on the right
1 Dual Fine two fine wheels
2 Dual Coarse two coarse wheels
Any other value will be treated the same as zero. You are not required to Home and Reference after changing
this value, but you must attach the correct grind wheels. Software is unable to test for correct wheels.
Changes to Screens and Messages in the New Modes
Where the screen displays the words Coarse and Fine in Traditional 7AF mode, it will identify both wheels as
Fine or Coarse in the other two modes. The words Left and Right have been added to some screens, since some
of the screens and messages will now refer to Left Grind Wheel and Right Grind Wheel. The wafer counts on
the Grind Data screen are labeled as having been ground on the left wheel or the right wheel. The headings for
the two halves of the Edit Recipes screen will say Left Wheel on Right Chuck, Right Wheel on Left Chuck.
On the Grind Cycle screen, there are two additional changes. The button labeled Select Grind will always be
disabled in the two new modes. You cannot select the type of grind using this button. The display on the
screen that normally shows the result of using this button is also changed. It now tells which grind wheels are
being used and it is automatically set according to the choice of work chucks. Both chucks require both wheels;
left-chuck-only requires right-wheel-only; right-chuck-only requires left-wheel-only.
Wafer Path and Bridge Motion in the New Modes
In the two new modes the bridge will never stop in the center during the grind cycle. When the bridge is at the
left, it will be grinding a wafer on the left chuck using the right grind wheel. The uncovered right chuck will be
unloaded, conditioned, and reloaded. Then the bridge will move to the right and grind the wafer on the right
chuck using the left grind wheel. The uncovered left chuck will be unloaded, conditioned, and reloaded.
If only the left chuck is being used, as specified on the Machine Setup screen, then only the right grind wheel will
be used during the grind cycle. When the bridge is at the left, grinding will take place on the left chuck using the
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