A unified approach for correcting global CDU, long-range, and short-range effects in advanced photomasks

With the advent of High-NA EUV lithography, the demand for photomasks to resolve tiny curvilinear shapes and to have local- and global Critical Dimension Uniformity (CDU) with more stringent specifications has become increasingly important. The development of Multi-Beam Mask Writers (MBMW) has been a fundamental advancement in meeting those advanced patterning requirements. MBMWs push the limits of various key metrics, like resolution, pattern placement, overlay, LER, etc. and enable masks that maintain tight CD control, if combined with leading-edge mask process correction (MPC). MPC plays a critical role in meeting High-NA EUV mask specs, as it allows consistent corrections from nanometer- to millimeter ranges, very difficult to achieve with on-tool corrections alone. In our earlier work, we demonstrated the integration of e-beam writer dose modulation into MPC simulation, enabling a consistent correction of short- and long-range effects and delivering significant improvements in residual CD errors. Building on our previous work, we now extend the methodology to include global CD uniformity (CDU) correction within the same flow. The global CDU model captures position-dependent bias, such as center-edge, top-bottom, or other position dependent CD variations. By integrating global CDU correction with short- and long-range corrections, we achieve a fully consistent correction of mask errors in MPC, resulting in masks with better local- and global CDU. Moreover, the integrated correction of all the effects in MPC reduces multiple corrections applied in the mask data preparation flow to a single operation.