Sub-nm topography measurement by deflectometry: Flatness standard and wafer nanotopography
- R. D. Geckeler, I. Weingartner
- Proc. SPIE, 4779, 2002, p1-12
This paper describes high-resolution autocollimator calibration system in NMIJ. A goniometer system with nano-radian resolution provides precision rotation angles of a mirror attached on the rotation axis and rotation angles read by an autocollimator are compared to the set angles. The rotation angle is detected by a highprecision angle interferometer that observes motions of corner reflectors attached to the axis. The interferometer is calibrated to output absolute angles by a 24-sided optical polygon that is attached to the rotation axis. The performance of the system is verified by comparing the calibration curves of same autocollimator taken by this system and those taken by the national standard of NMIJ.