Paper
30 July 2002 Theoretical analysis of the potential for maskless lithography
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Abstract
In order to be practical, maskless lithography schemes are limited as to how small the physical address grid can be. Thus, graybeam techniques are used to create a small virtual address grid while maintaining a large physical address grid. One important consideration for maskless lithography is the impact of these small 'virtual' address grids on image quality. Using simple simulations of aerial image formation as the summation of Gaussian spots and PROLITH simulations of the projection of square pixels, several important conclusions about the use of graybeam are made. Graybeam results in a non-linear variation in edge position with gray level, with the non-linearity increasing with larger physical address grid size. While this edge position deviation from non-linearity can be calibrated out of the writing scheme, the calibration curve is process dependent. One problem with the use of graybeam is the reduction of image quality as expressed by the image log-slope. For the raster scan case of a physical address grid equal to half of the spot size, the worst case graybeam level has an image log-slope at the edge that is 20% less than the best case. For the projection imaging case of a physical address grid equal to the pixel size, the worst case graybeam level has an image log-slope at the edge that is 15% less than the best case.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Chris A. Mack "Theoretical analysis of the potential for maskless lithography", Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); https://doi.org/10.1117/12.474474
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Cited by 3 scholarly publications.
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KEYWORDS
Image quality

Calibration

Image processing

Maskless lithography

Raster graphics

Image acquisition

Modulation

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