Non-intrusive pellicle height measurement system
US6459491B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 12, 2001 |
| Grant date | Oct 1, 2002 |
| Priority date | — |
| Expiry date | Jul 12, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0616
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method to monitor a dimension of a pellicle includes projecting a first light signal against a surface of the pellicle. A second light signal reflected from the surface of the pellicle is detected, with the second light signal being a representation of the first light signal. The method determines if the dimension of the pellicle is within an allowable value based on a characteristic of the detected second light signal. The characteristic of the detected second light signal can include time periods between pulses of the detected second light signal, an intensity of the detected second light signal, or a positional displacement of the detected second light signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.