Evaluation of local CD and placement distribution on EUV mask and its impact on wafer

The mask is a known contributor to intra-field fingerprints at the wafer level. Traditionally, a 3σ distribution of critical dimensions (CDs) on mask was considered sufficient to characterize the contribution to the CD distribution at wafer level. Recent studies report wafer local CD distributions characterized for statistics beyond 3σ1. Mask has been shown to contribute to wafer local CD distribution also which is typically quantified as Local CD Uniformity (LCDU), a 3σ metric2. Additionally, the local placement distribution on wafer could be a contributor to Edge Placement Error (EPE)3. Consequently, it is imperative to understand, characterize and ultimately control the mask contributions to local CD and placement distribution at wafer level. This work is an investigation of local CD and placement distribution on an EUV mask and its impact on distributions at wafer level.