Maskless lithography with sub-pixel resolution

Abstract

Sub-pixel digital resolution is provided in a maskless microlithography system by a sub-pixel voting system using multiple, slightly-offset, digitally-controlled, unit-pixel, partial exposures with cumulative voting identifying regions of full exposure for sub-pixel-selection. Computer control of a virtual-mask pixel-selection device of unit-pixel resolution usually provides pixel-resolution patterns. To achieve sub-pixel resolution, the virtual mask, after a first partial exposure, is offset by less than a pixel-width and a second partial exposure is made. If the offset is {fraction (1/2 )} pixel-width, then an image region of half-pixel size with full exposure is realized. Finer voting can be defined by number of pulses, by significantly changing the offset, and by offset in another dimension, and by increasing the multiplicity of exposures, thus enabling resolution enhancement by large multiples. The same offsetting techniques can be used for other than binary voting, for example to drill controlled-depth vias or to provide topography controls for laser-milling a controlled microsurface.

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