29 June 1984 Improvement Of Overlay And Focusing Accuracy Of Wafer Step-And-Repeat Aligners By Automatic Calibration
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Abstract
A new method is described which permits fully automated, high-speed measurement and compensation of the residual alignment and focusing offsets in advanced wafer step-and-repeat aligners which, despite being very small (0.1 micron range), cannot be tolerated in high performance lithography. A special reticle is projected onto a special measuring field to determine the exact position of the image in the exposure light. This position is used to calculate the alignment and focusing offsets between the aligned image and the actual image. The autocalibration procedure described represents a considerable advance over the present state-of-the-art, cutting down machine set-up times from hours to 90 seconds. The residual offsets are reduced to ± 0.05 μm (3 d ) for alignment and ± 0.15 μm (3 6 ) for focusing.
© (1984) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Herbert E Mayer, Herbert E Mayer, } "Improvement Of Overlay And Focusing Accuracy Of Wafer Step-And-Repeat Aligners By Automatic Calibration", Proc. SPIE 0470, Optical Microlithography III: Technology for the Next Decade, (29 June 1984); doi: 10.1117/12.941911; https://doi.org/10.1117/12.941911
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