Improving Cost of Ownership on KLA-Tencor Wafer Fab Reticle Inspections by Implementing Pixel Migration via New STARlight2+ Capability

In the ever-changing semiconductor industry, wafer fabs and mask shops alike are adding low cost of ownership (CoO) to the list of requirements for inspections tools. KLA-Tencor has developed and introduced STARlight2+ (SL2+) to satisfy this need. This new software algorithm is available on all TeraScanHR and TeraFab models. KLA-Tencor has cooperated with United Microelectronics Corporation (UMC) to demonstrate and improve SL2+, including its ability to lower CoO, on 65nm and below photomasks. These improvements are built on the rich history of STARlight. Over the years, STARlight has become one of the industry standards for reticle inspection. Like its predecessors, SL2+ uses only transmitted and reflected light images from a reticle to identify defects on the reticle. These images along with plate-specific information are then processed by SL2+ to generate reference images of how the patterns on the reticle should appear. These reference images are then compared with the initial optical images to identify the defects. The new and improved SL2+ generates more accurate reference images. These images reduce background noise and increase the usable sensitivity. With the results from controlled engineering tests, a fab or mask shop can then decide to inspect reticles at a given technology node with a large pixel; this is sometimes referred to as pixel migration. The larger pixel with SL2+ can then perform the inspections at similar sensitivity settings and higher throughput, thus lowering CoO.