System for monitoring optical properties of photolithography equipment
US5898479A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 1997 |
| Grant date | Apr 27, 1999 |
| Priority date | — |
| Expiry date | Jul 10, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70641
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A focus evaluation technique for photolithography equipment is disclosed. This technique includes providing a substrate having a photoresist coating for treatment by the equipment. The equipment is activated to focus a first part of a image on a region of the surface and defocus a second part of the image relative to the region. The region is tilted relative to an image plane defined by the equipment. This activation is repeated for each of a number of spaced-apart regions along the surface. The substrate is processed to provide a pattern for each of the regions corresponding to the first and second parts. The equipment is characterized from the pattern for each of the regions. This characterization may result from inspection of the pattern relative to reference marks provided for each region. Focus information for the equipment which accounts for lens heating may be determined from this inspection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.