PVA SIRD

PVA&Tepla SIRD（Primitive name Jena Wave）
Scanning Infra-Red Depolarization Non-contact internal stress measurement system

A laser sources below the Wafer, Horizontal direction of a laser beam through the Wafer by polarizer, at the top of the sample there is a photo diodes to receive, if Wafer stress free, laser can directly through the Wafer without any change, the corresponding P will not receive any signal, the corresponding P value is 0, the resulting D value is 0, means sample internal stress free, if the Wafer has internal stress, the laser beam will polarized, and be split by a spectroscope, P will receive the corresponding signal at this moment, Finally, the calculated D value > 0, indicating that there is stress inside the sample.

Due to the wafer internal stress, it may lead the product defective in the next process, so wafer internal stress should be measured in wafer production, or after wafer shipped to wafer fab plant, to confirm whether the wafer can be shipped, or do processes, SIRD used for monitor products internal stress after each process, confirm when the machine need replace parts, or need to repair, reduce defects and improve product yield.




Application examples