Patent Number: 7,821,625

Title: Systems and methods for lithographic illuminator beam deviation measurement and calibration using grating sensors

Abstract: Angular deviation of illumination beam is measured with high accuracy for an expanded continuous range of angles using grating sensors that are configured to exhibit Surface Plasmon Resonance effects at actinic wavelengths. The beam deviation measurement systems and procedures are applicable to both mask-based and maskless lithography tools. A control system adopts an appropriate calibration algorithm based on whether the SPR effect is detected or not. Relative intensity shift in an SPR-affected diffractive order, and/or relative position and slope change in non-SPR-affected diffractive orders are used as a basis of the adopted calibration algorithm.

Inventors: Downey; Todd R. (Monroe, CT)

Assignee: ASML Holding N.V.

International Classification: G01C 1/00 (20060101)

Expiration Date: 2018-10-26 0:00:00