System and method for optical photomask inspection through pellicle
US7679736B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 26, 2008 |
| Grant date | Mar 16, 2010 |
| Priority date | — |
| Expiry date | Jul 26, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/95676
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A pellicle correction factor is determined by comparing a first measurement of a reference photomask alone with a second measurement of that reference photomask through a reference pellicle protecting the mask layers of the photomask. A number of pellicle correction factors may be determined for different type pellicles and made accessible in pellicle correction factor lookup table of the system or supplied on a separate data storage medium. Raw Reflectance and/or Transmittance measurement data of a generic photomask through a generic pellicle is consecutively corrected for the measurement distorting effects of that pellicle by applying a matching one of the previously determined pellicle correction factors. The pellicle correction factor is preferably an attenuation signature across a predetermined measurement irradiation spectrum.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.