Renewing i-line laser mask writers with reduced power consumption and increased productivity

Abstract

A significant proportion of the world’s photomasks are written by the ALTATM i-line laser mask writers that started shipping in 1994. Many of these masks are used for manufacturing devices in the growing “ICAPS” markets: the Internet of Things, Communications, Automotive, Power and Sensors. Every ALTA i-line writer shipped is still in production due to sustained investments, driven by the motivation to keep fully depreciated equipment running as long as possible. Technology developments recently created the opportunity for a comprehensive renewal of this installed base. A field upgrade package has been developed that replaces the legacy computing systems and electronics with modern equivalents, while substantially reducing the power consumption and significantly increasing productivity. The software-based data path developed for ALTA DUV laser mask writers has been ported to iline, bringing an order of magnitude increase in processing speed for data prep and rasterization compared to the original hardware-based method. The data path accepts MEBES, OASIS and GDSII data formats, and the 33x (0.8 NA) system outputs data on a grid reduced to 0.625 nm. The new data path also provides optionally-enabled compensation for process footprint and pattern-density related CD errors, and the multicore server accounts for a large share of the system speedup. Another improvement adopted from the DUV writer is an axis-parallel, 32-beam brush with a new scan lens, enabling a novel bidirectional writing scheme that minimizes overhead time and contributes to the increased writing speed. The legacy gas laser has been replaced with a solid state, optically pumped semiconductor laser (OPSL) designed to match the original wavelength, reducing system power consumption by about 75%.