Maskless lithography with sub-pixel resolution
First Claim
1. A maskless lithographic system of sub-pixel resolution having a radiation source and an optical system with unit-pixel resolution pattern defining means between radiation source and a substrate mounted on a high-precision stage characterized by:
- a) means to provide a first set of virtual-mask partial exposures on a unit-pixel basis; and
b) means to provide at least one subsequent set of virtual-mask partial exposures on a unit-pixel basis, partially overlapping and offset from said first set;
whereby overlapping sub-pixel partial exposures form full exposures at sub-pixel areas, thus providing properly defined image areas of sub-pixel size.
1 Assignment
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Accused Products
Abstract
Maskless microlithography provides a sub-pixel voting system using multiple, slightly-offset, digitally-controlled, unit-pixel, partial exposures with cumulative voting to identify 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 ½ pixel-width, the result is a half-pixel size image region of full exposure. Finer voting can be defined by number of pulses, by significantly changing the offset, by offset in another dimension, and by increasing the multiplicity of exposures, thus enabling resolution enhancement by large multiples. The offsetting techniques can also be used to drill controlled-depth vias or to provide topography controls for laser-milling.
77 Citations
12 Claims
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1. A maskless lithographic system of sub-pixel resolution having a radiation source and an optical system with unit-pixel resolution pattern defining means between radiation source and a substrate mounted on a high-precision stage characterized by:
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a) means to provide a first set of virtual-mask partial exposures on a unit-pixel basis; and
b) means to provide at least one subsequent set of virtual-mask partial exposures on a unit-pixel basis, partially overlapping and offset from said first set;
whereby overlapping sub-pixel partial exposures form full exposures at sub-pixel areas, thus providing properly defined image areas of sub-pixel size. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
a) mean to supply description of the full image information to the system control computer;
b) software means to determine the sets of partial exposures necessary to achieve full exposure at the desired image location; and
c) software means to optimize the sets of partial exposure so as to minimize their number.
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12. A maskless lithographic method for providing sub-pixel resolution from components having unit-pixel resolution, in the following steps:
- a) partially imaging in a first set of exposures on a unit-pixel basis with exposure values less than full exposure at both unselected sub-pixel locations and selected sub-pixel locations;
b) partially imaging at least one subsequent set of exposures on a unit-pixel basis with exposure values less than full exposure at both unselected sub-pixel locations and selected sub-pixel locations during the subsequent set of exposures, with offset to said first set of exposures, in such fashion that selected sub-pixel locations receive cumulative exposure equal to fill exposure as a composite of both said first set of exposures and said subsequent set of exposures;
c) supplying a description of the full image information to the system control computer;
d) determining with software means all the sets of partial exposures necessary to achieve full exposure at the desired image locations; and
e) optimizing with software means the sets of partial exposures so as to minimize their number.
- a) partially imaging in a first set of exposures on a unit-pixel basis with exposure values less than full exposure at both unselected sub-pixel locations and selected sub-pixel locations;
Specification