Strasbaugh nTellect (Model 7AF) Wafer Grinder
14 - 12 Version 1.2 - June 2004
Figure 14-4
3. Circular Marks Around Center of Wafer
Description: These marks form concentric rings around the center of the wafer.
They are sometimes hard to see and may not decrease the overall strength of the
wafer. However, when such marks are apparent, the problem should be corrected.
Corrective Action: The concentric rings are probably caused by debris in the
spin/rinse station brush. The brush should be cleaned thoroughly with D. I. water. If
cleaning the brush does not work, other possible causes should be investigated.
Figure 14-5
4. Cross-Hatching at the Center of the Wafer
Description: These marks radiate from the center of the wafer and curve in the
opposite direction of the normal grind pattern. There may be a few marks of this
nature present at the center of a wafer with a good finish. However, if the marks are
greater than 1/2 inch in length, the problem should be corrected.
Corrective Action: The fine wheel needs to be dressed. If dressing the fine wheel
does not work, the problem should be investigated until a satisfactory solution is
found. Remove tape from the center of the wafer at the prealigner.
To Next Page
Loading...
