Actinic review of EUV masks: challenges and achievements in delivering the perfect mask for EUV production

Actinic review of potential defect sites and verification of their repair is a key step in producing defect free masks. The AIMS TM systems are the industry proven standard for this task and the AIMSTM EUV has been developed to provide this functionality for EUV masks. Thereby it closes an important gap in the EUV mask infrastructure for volume production. In this paper, we show the readiness of the AIMS TM EUV for defect review and verification, and discuss the use of actinic aerial image metrology beyond this core application. In particular, we show measurements on mask 3D effects and the contribution of photon stochastics on wafer local CDU.