Plural interleaved exposure process for increased feature aspect ratio in dense arrays
US6451508B1 · kind B1 · utility
Assignees
Inventors
Key dates
| Filing date | Apr 28, 2000 |
| Grant date | Sep 17, 2002 |
| Priority date | — |
| Expiry date | Apr 28, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/70
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method for exposing a workpiece in a dual exposure step-and-repeat process starts by forming a design for a reticle mask. Deconstruct the design for the reticle mask by removing a set(s) of the features that are juxtaposed. Form unexposed resist on the workpiece. Load the workpiece and the reticle mask into the stepper. Expose the workpiece through the reticle mask. Reposition the workpiece by a nanostep. Then expose the workpiece through the reticle mask after the repositioning. Test whether the plural exposure process is finished. If the result of the test is NO the process loops back to repeat some of the above steps. Otherwise the process has been completed. An overlay mark is produced by plural exposures of a single mark. A dead zone is provided surrounding an array region in which printing occurs subsequent to exposure in an original exposure. Stepper-framing-blades are moved over the dead zone to prevent additional exposures after an initial exposure. Alternatively, the workpiece can be fully exposed first by stepping a series of full steps, then going back to the starting position, making a nanostep to reset the starting position and re-exposing from the reset starting po…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.