Maskless vortex phase shift optical direct write lithography
View Patent ↗The present invention provides methods and apparatus for accomplishing optical direct write phase shift lithography. A lithography system and method are provided wherein a mirror array is configured to generate vortex phase shift optical patterns that are directed onto a photosensitive layer of a substrate. The lithography methods and systems facilitate pattern transfer using such vortex phase shift exposure patterns.
1. A maskless lithography system for patterning a substrate having a layer of photoimageable material formed thereon, the system comprising:
a mirror array comprising a plurality of movable mirrors arranged in a plurality of tiles configured in vortex phase shift optical patterns enabling the generation of corresponding vortex phase shift exposure patterns;
an illumination source arranged to direct light onto the mirror array to generate the respective vortex phase shift exposure patterns;
optics configured to project the vortex phase shift exposure patterns onto a substrate; and
a stage for holding the substrate to facilitate exposure of at least a portion of the substrate to the vortex phase shift optical patterns.
2. The maskless lithography system of claim 1 , wherein the plurality of tiles each include a plurality of mirror sets each having a multiplicity of movable mirrors, the mirror sets arranged in a spiral arrangement so that the mirrors in one of the mirror sets are vertically displaced relative to mirrors of an adjacent mirror set, wherein the amount of displacement between the mirror sets is associated with a phase difference in light reflected by the mirror sets.
3. The maskless lithography system of claim 2 , wherein the mirror sets of a tile include a first mirror set and a plurality of successive mirror sets arranged in a spiral pattern with the first mirror set having a displacement corresponding to a zero phase difference and each successive mirror set in the spiral pattern having a progressively greater displacement relative to the first mirror set with each progressively greater displacement being associated with a greater phase difference relative to the first mirror set.
4. The maskless lithography system of claim 2 , wherein the mirror sets are configured in a spiral pattern arranged about an axis of the tile to form the vortex phase shift optical pattern for each tile.
5. The maskless lithography system of claim 4 , wherein the mirror sets of the tile comprise n mirror sets arranged in a spiral pattern about the tile axis such that the amount of displacement between the mirrors of a mirror set is associated with an about 360/n degree phase difference in light reflected by an adjacent mirror set of the tile, where n is an integer greater than one.
6. The maskless lithography system of claim 4 , wherein the spiral pattern of the mirror sets is the same for each tile.
7. The maskless lithography system of claim 4 , wherein the spiral pattern of the mirror sets for a portion of the tiles is different than the spiral pattern of the mirror sets for another portion of the tiles.
8. The maskless lithography system of claim 7 , wherein a first spiral pattern of mirror sets for a first tile is different from a second spiral pattern of mirror sets for a second adjacent tile.
9. The maskless lithography system of claim 8 wherein the second spiral pattern of mirror sets for the second tile is rotated relative to the first spiral pattern of mirror sets for the first tile.
10. The maskless lithography system of claim 1 , wherein the plurality of mirrors comprising the mirror array are movable mirrors operative to be controllably displaced from an original position to move the mirror sets of a tile to reconfigure the vortex phase shift optical pattern of the tile thereby enabling generation of a different vortex phase shift exposure pattern after reconfiguration.
11. The maskless lithography system of claim 1 , wherein the stage is movable and wherein the movable stage is operative to move the substrate to illuminate different portions of the substrate with the exposure pattern.
12. The maskless lithography system of claim 1 , wherein the mirror array comprising a plurality of mirrors arranged in a plurality of tiles configured in vortex phase shift optical patterns is operative to generate vortex phase shift exposure patterns that form dark spots on the photoimageable layer of the substrate.
13. The maskless lithography system of claim 12 , wherein the configuration of the vortex phase shift optical patterns enables generation of dark spots having different sizes.
14. The maskless lithography system of claim 1 , wherein each of the plurality of tiles includes a plurality of mirror sets each having a multiplicity of movable mirrors, the mirror sets arranged in a spiral arrangement so that each mirror set reflects light having a phase difference relative to light reflected by adjacent mirror sets.
15. The maskless lithography system of claim 14 , wherein the spiral arrangement of mirror sets of each tile forms a spiral pattern.
16. The maskless lithography system of claim 15 , wherein the spiral pattern of the mirror sets is the same for each tile.
17. The maskless lithography system of claim 15 , wherein the spiral pattern of the mirror sets for a portion of the tiles is different than the spiral pattern of the mirror sets for another portion of the tiles.
18. The maskless lithography system of claim 17 , wherein a first spiral pattern of mirror sets for a first tile is different from a second spiral pattern of mirror sets for a second adjacent tile.
19. A maskless lithography system, comprising:
a mirror array comprising a plurality of movable mirrors configurable as a plurality of tiles arranged in a phase shift optical pattern that each generate a vortex phase shift exposure pattern when illuminated;
a control element for reconfiguring the plurality of mirrors to generate a desired vortex phase shift optical pattern for each tile;
an illumination source operative for directing light onto the mirror array to generate the vortex phase shift exposure patterns that are projected onto a substrate; and
a stage operative to move the substrate to facilitate exposure of at least a portion of the substrate to the vortex phase shift exposure pattern.
20. The maskless lithography system of claim 19 , wherein the plurality of tiles comprises a first tile and a second tile adjacent to the first tile, wherein the first tile is arranged in a first vortex phase shift optical pattern and the second tile is arranged in a second vortex phase shift optical pattern.
21. The maskless lithography system of claim 20 , wherein the first vortex phase shift optical pattern is different from the second vortex phase shift optical pattern.
22. The maskless lithography system of 21 , wherein for a given amount of illumination energy the first vortex phase shift optical pattern generates a smaller dark spot than a dark spot produced by the second vortex phase shift optical pattern.
23. The maskless lithography system of claim 20 , wherein the first vortex phase shift optical pattern is the same as the second vortex phase shift optical pattern.