Evaluation of the `HiVol´ above-wafer in-situ particle monitoring sensor

The `HiVol´ above wafer in-situ particle monitoring (AWISPM) sensor was developed to overcome many of the fundamental design issues typically associated with most ISPM sensor applications. The AWISPM sensor is capable of monitoring particulate contamination levels directly within a process chamber, and the use of a scanned laser beam creates a much larger detection volume. Since a particle is also detected multiple times within the detection volume, the use of an `auto-correlation´ algorithm results in a significant decrease in the level of false counts. Project results demonstrate that the AWISPM sensor provides better correlation to wafer-level defects and to the corresponding product yield impact. Consequently, the AWISPM sensor can be effective in the early detection of defect excursions and in enhancing product yields. The sensor was also shown to be useful in forecasting the need for equipment preventative maintenance, and in reducing the reliance upon off-line wafer defect inspection systems