Process Preparation
The grind recipe is prepared as if the wafers were not mounted on a substrate. The numeric portion of the
recipe looks like an ordinary Target Grind recipe. The target thickness for each step should be the target
thickness of the wafer (the top layer of the sandwich). Then:
1. Set Feed Wafer Thickness = maximum thickness of wafer (the top layer of the sandwich).
2. Set Tape Thickness = maximum thickness of wax+substrate (the bottom two sandwich layers).
3. Select IND WAFER as the Grind Mode for the recipe.
4. In addition to constructing the recipe, set machine variable 50, Reference Wafer, to the maximum
possible thickness of wafer+wax+substrate (the entire sandwich).
The next step is to measure the wafers (the top layers) and prepare the data file. It is critical that the
measurement for each wafer correspond to the correct line in the data file. The file must be prepared and
named for use on Send Cassette 1 or 2. The cassette must be placed onto the correct turret for the grind to
work correctly. One way to help ensure that the correct file is used is to prepare and load only one file and
cassette at a time. Therefore, if the cassette is placed on the wrong turret, the measurement file will not be
found and an error will be generated.
Successful loading of a measurement file will result in the deletion of the measurement file. This is to ensure
that the file will not be subsequently misused. If the file is incorrect, deleting it prevents it from being used to
grind wafers. If the grind sequence is interrupted, another file must be made, or the original file must be
modified and presented a second time to the 7AF. To use the old file could result in over-ground or
destroyed wafers. It is highly recommended that the measurement files be rebuilt and assignment to
cassettes/turrets be made again. If these files are to be re-used or stored, they must be stored off the 7AF.
Warning: If a floppy disk is used to submit the data file to the 7AF, do not write-protect the floppy disk.
Selecting the grind recipe on the Grind Cycle screen is the same as any other process. When an IND
WAFER recipe is selected, the 7AF software will try to find measurement files for send cassettes that are
placed on turrets and are facing the robot. When a cassette is scanned and a measurement file is found, the
scan results and the measurement file contents are compared. If every filled slot corresponds to a non-zero
data value and if all the data values are sensible, grinding will begin for that cassette. Later, as cassettes are
scanned and data files are found, they will also be compared. If a data file mismatch occurs, a warning
message will appear, but wafers from the preceding cassette will be completed. To respond to the warning,
supply the correct data file via GEM or on a floppy. Data files will not be read while actual grinding is taking
place, so there may be a delay from the time a data file is submitted until the warning is erased. That will
probably occur when the bridge moves.
If a cross slot error occurs, rotate the turret and correct the cross slot. It may be necessary in this case to re-
submit the data file. It is likely that the file has already been read and deleted.
Topflush/Backflush
Some 7AF’s have a topflush option that operates together with the work chuck backflush to clean the
surface of the chuck. This does a better job of cleaning, but has one problem during Machine Maintenance.
While the backflush can be run at any time, the topflush must only be run when the bridge is not covering the
chuck. Otherwise water will reflect off the bridge and spray the robot. To inform software of the presence
of the topflush, set machine variable 17, Work Chuck TopFlush 0=No, to a non-zero value. A non-zero
value will prevent an operator from turning on the backflush (and the topflush) when the bridge is in the way.
Work Chuck Coolant Failure
If there is an interruption to the work chuck coolant (also called grinding water or cutting water) during the
grind cycle or dress cycle, serious damage can occur to the chuck, the grind wheel, and to the wafer on the
chuck. This will happen quickly. Machine variable 99, Chuck Coolant Timers, allows you to specify the
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