Method of forming resist pattern and photomask therefor
US5324600A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 7, 1992 |
| Grant date | Jun 28, 1994 |
| Priority date | — |
| Expiry date | Jul 7, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70466
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In a photomask for use in forming a resist pattern by projection exposure of a resist through the photomask, a phase shifter has a first edge part whose image is to be transferred and a second edge part whose image is not to be transferred. A light attenuator is provided to cover the first edge part. The light attenuator may include an array of opaque stripes arranged at a pitch of not more than the limit of resolution, i.e., 0.5.times..lambda./NA, where .lambda. represents the wavelength of light used for the projection exposure, and NA represents the numerical aperture of an optical system used for the projection exposure. In another embodiment, the light attenuator is formed to cover a shifter edge part in alignment with a line of a transmission mask. In a further embodiment, one or more light attenuators having different transparency are used to obtain lines of a resist pattern having different widths.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.