Advanced laser mask repair in the current wafer foundry environment

Abstract

Contrary to the prior assumptions of its technical demise, deep UV (DUV) femtosecond pulsed laser repair of photomasks is continuing to mature and improve as a technology. Similar to the optical enhancements that allow for 193 nm wavelength light to continue being used down to the 32, or even in some cases 22 nm, node, the process regimes for this type of laser repair continue to expand as new processes are discovered. This work reviews the qualification of repair performance for production at a major wafer foundry site. In addition advances are shown in the area of through-pellicle repair (TRP) process development. These advances include the preferential (versus surrounding reference mask structures) removal of soft defects and the capability to remove or manipulate particles on top of a flat absorber region with no detectable removal of the absorber. These developments will further demonstrate the progressive decoupling of the laser repair spot size from the minimum technology node for laser repair.