Method for focusing projection printer
US4681430A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 27, 1986 |
| Grant date | Jul 21, 1987 |
| Priority date | — |
| Expiry date | Aug 27, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7026
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An improved method for automatically focusing an integrated circuit manufacturing projection step and repeat photolithography printer employing an optical signal to focus the printer is disclosed. The automatic focusing is achieved by reflecting an optical signal off a photoresist layer on the surface of a wafer and converting the reflected optical signal into an electronic signal employed to focus the printer. According to the preferred embodiment of the present invention, a dye which absorbs light at the wavelength the optical signal is added to the photoresist layer to improve the quality of the reflected optical signal thereby considerably reducing or eliminating focusing errors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.