Systematic method for production of phase-shifting photolithographic masks
US5527645A · kind A · utility
Inventors
Key dates
| Filing date | Nov 17, 1994 |
| Grant date | Jun 18, 1996 |
| Priority date | — |
| Expiry date | Nov 17, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/28
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A systematic method of producing a mask for use within a photolithographic illumination system characterized by a transmission function in which light is transmitted through non-opaque portions of the mask positioned in an object plane and in which an image is formed on an image plane is disclosed herein. The method includes the steps of defining a binary image pattern to be formed by the illumination system on the image plane; generating a continuous mask function of continuously-varying phase which satisfies predetermined error criteria based on the transmission function and the binary image pattern; transforming the mask function into a quadrature-phase mask function by dividing the continuously-varying phase into four phase levels; and generating the mask in accordance with the quadrature-phase mask function, wherein the mask includes a plurality of pixel regions each of which has a transmittance corresponding to one of the four phase levels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.