Scanning InfraRed Depolarization
The SIRD is a stress measurement system at wafer level for process monitoring, which will contribute to cost reduction as well as yield improvement.
The introduction of the 300mm wafers has brought new standards for the suppliers of bare wafers: The increase to 300mm diameter has more than doubled the wafer surface area and weight; however the thickness has remained very much the same, substantially increasing the risk of breakage. Whenever a 300mm wafer has areas of high internal mechanical tensions (stress), this will significantly increase the breakage probability during the IC manufacturing process along with all the implied very costly consequences. Therefore, the early detection of stressed wafers and prevention of breakage has gained more and more attention. Additionally, wafer stress does also have a negative influence on Silicon crystal lattice characteristics hence the device functionality.