Small chips 8″ wafer dot pin mark
Requirement
Marking of 8″ silicon wafer with grid size of 3000 to 4000 and able to accept warpage up to 6 mm. As the chip size of 40-50 um is so small it can only host a dot pin mark. Requirement accuracy is ≤ ±20um. Since the marking surface is featureless an IR camera option is used to determine the marking position from the image of the street feature on the bottom side. A 20W SHG green laser with Scanvision enhancement is included to achieve the required accuracy.
Result – dot marking
The result of the mark is clear and distinct with good visibility under vision camera. The mark is clean and debris free with depth of < 1 um. The diameter of the pin is 40 um. The mark placement throughout the wafer is consistent and repeatable. Can achieve uph of 740k chips/hour.
Result – position
From the above, the system is placing the dots accurately on each chip in each quadrant of the wafer with ≤ ±20um landing accuracy.
Result – dot mark presentation
Show both the image under dark field and bright field at 200x magnification.
Full machine proposal
If higher UPH is required, we do have a ready solution for a dual laser marking station in a single machine which is able to almost double the output with minimal increase in tool size.
Above are different sampling images across wafer 2 at the stitching intersection points captured by the inline IR vision imaging. We can see that the dot position accuracy is better than ≤ ±20um. Higher accuracy of ≤ ±10um can be achieved with reduce uph.
Above are different sampling images across wafer 3 at the stitching intersection points captured by the inline IR vision imaging. We can see that the dot position accuracy is better than ≤ ±20um. Higher accuracy of ≤ ±10um can be achieved with reduce uph.
