Journal of Micro/Nanolithography, MEMS, and MOEMSCr photomask etch
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Theoretical and experimental Cr photomask etch studies are carried out using different resists [ZEP, chemically amplified resists (CAR), and optical resists] and different brand etch tools. The effects of chrome loading are analyzed, and theoretical equations are developed for etch time calculations and endpoint determinations of extremely low Cr load photomasks. It was found that these equations agreed well with experimental data. Etch critical dimension (CD) movement data are analyzed and calculated, showing agreement with experimental data. Metrology measurement and characterization tools include a profilometer, an optical film measurement system, and SEM and optical CD measurement systems. Significant etch performance differences are noted across etch tools, irrespective of the resist type used. An etch property number method is proposed, which is found to accurately describe the etch process analysis and the extent to which etch performance can be expected to be improved. Etch properties are focused on etch CD movement, isolated/dense etch CD bias, radial CD etch contribution, and Cr load effects.