Apparatus for projecting a pattern on a semiconductor substrate
US4592650A · kind A · utility
4Cited by
3References
10Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jan 23, 1985 |
| Grant date | Jun 3, 1986 |
| Priority date | — |
| Expiry date | Jan 23, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/70
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An apparatus for determining the focus state of a system for the projection exposure of a mask on a semiconductive substrate for producing integrated circuits without relatively displacing the mask, projection objective and substrate along the common optical axis, utilizes an arrangement for varying cyclically the optical path length for rays at least arising from a projected image on the substrate and running through the objective to a detector plane so that an intensity measurement of the light intensity at this plane indicates the path length required for sharpness and hence the focus state of the projection assembly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.