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 method of forming a pattern on a substrate, the method comprising:
providing a substrate having formed thereon a photosensitive layer;
providing a mirror array comprising a plurality of movable mirrors;
configuring the mirrors such that the arrangement of the mirrors comprises a desired vortex phase shift optical pattern in the mirror array;
illuminating the mirror array to form a resultant vortex phase shift exposure pattern associated with the desired vortex phase shift optical pattern in the mirror array;
directing the exposure pattern onto the photosensitive layer of the substrate; and
exposing the photosensitive layer of the substrate with the resultant vortex phase shift exposure pattern to facilitate pattern transfer to the photosensitive layer.
2. The method of claim 1 , wherein configuring the mirrors such that the arrangement of the mirrors comprises a desired vortex phase shift optical pattern in the mirror array comprises arranging the plurality of mirrors as a plurality of tiles configured as vortex phase shift optical patterns operative to generate respective vortex phase shift exposure patterns.
3. The method of claim 2 , wherein arranging the plurality of mirrors as a plurality of tiles configured as vortex phase shift optical patterns comprises arranging the tiles to produce a pattern of dark spots, and wherein directing the exposure pattern comprises directing the pattern of dark spots onto the photosensitive layer of the substrate.
4. The method of claim 2 , wherein:
providing a mirror array comprising a plurality of movable mirrors includes providing the mirror array with a plurality of movable piston mirrors; and
arranging the plurality of mirrors further includes arranging the tiles in a plurality of mirror sets each comprising a plurality of mirrors, wherein the mirror sets are 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.
5. The method of claim 4 , wherein arranging the tiles in a plurality of mirror sets comprises arranging the mirror sets of each tile in a spiral pattern arranged about an axis of the tile to form the vortex phase shift optical pattern for each tile.
6. The method of claim 4 , wherein arranging the tiles in a plurality of mirror sets comprises arranging n mirror sets of the tile into 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.
7. The method of claim 4 , wherein arranging the tiles in a plurality of mirror sets comprises arranging the mirror sets of each tile such that the spiral pattern of the mirror sets is the same for each tile.
8. The method of claim 4 , wherein arranging the tiles in a plurality of mirror sets comprises arranging the mirror sets of a first tile differently than the mirror sets of a second tile.
9. The method of claim 4 , wherein arranging the plurality of mirrors includes arranging the mirror sets of a tile as a first mirror set and as 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 being arranged 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.
10. The method of claim 4 , wherein configuring the mirrors comprises moving the mirror sets by controllably displacing the mirrors of the mirror sets 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 the generation of a different vortex phase shift exposure pattern after reconfiguration.