Calibration of azimuth angle for optical metrology stage using grating-coupled surface plasmon resonance

A method of calibrating an optical metrology device, comprising:

• measuring a grating-coupled surface plasmon resonance response of a calibration grating that is coupled to a stage, the grating-coupled surface plasmon resonance response is produced in response to a beam of light from an optical system along a plane of incidence (POI) that is incident on the calibration grating;
• determining an azimuth angle between an orientation of the calibration grating and the POI of the optical system based on the grating-coupled surface plasmon resonance response of the calibration grating;
• and
• correcting for an azimuth angle offset between a sample on the stage and the POI of the optical system using the determined azimuth angle between the orientation of the calibration grating and the POI of the optical system.

An optical metrology device configured for calibration, comprising:

• means for producing grating-coupled surface plasmon resonance in response to a beam of light from an optical system along a plane of incidence (POI);
• means for measuring a grating-coupled surface plasmon resonance response to the beam of light with respect to a stage;
• means for determining an azimuth angle between the stage and the POI of the optical system based on the grating-coupled surface plasmon resonance response;
• and
• means for correcting an azimuth angle offset between a sample on the stage and the POI of the optical system using a determined azimuth angle between the stage and the POI of the optical system.