Illumination system and method employing a deformable mirror and diffractive optical elements
US5684566A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 24, 1995 |
| Grant date | Nov 4, 1997 |
| Priority date | — |
| Expiry date | May 24, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70358
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An illumination system for use in photolithography using a laser or radiation beam source. A deformable mirror is used to shape the beam of laser radiation to obtain global uniformity. A profile sensing means is used to detect any global non-uniformities. The output of this sensing means is fed to a controller for calculating a mirror contour and controlling actuators that shape the deformable mirror to obtain a globally uniform intensity. A diffractive or diffusive optical element, such as a microlens array, eliminates local non-uniformities. Movement of this element eliminates speckle caused by interference due to the coherent beam source. A uniform intensity profile and appropriate angular spread is achieved with very little transmission loss and is automatically compensated for degraded or changing source performance. The illumination system is particularly applicable to a scanning photolithography process as used in the manufacture of semiconductor substrates.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.