METAS mask measuring system

The mask measuring machine developed at METAS is an optical two-coordinate measuring machine with a measuring range of 400 mm × 300 mm.

The structures to be measured are captured using a reflected-light microscope and evaluated by means of digital image processing. A precision air-bearing X-Y translation stage, a differential two-axis interferometer and a reference mirror mount made of temperature-stable glass-ceramic material (Zerodur) enable measurement uncertainties of Q[50 nm, 0.1E-6xL].

A specially designed measurement cabin in the cleanroom area at METAS is also essential for achieving the low measurement uncertainty. It maintains a constant temperature of 20 °C with fluctuations of only a few hundredths of a degree Celsius. The measurement cabin is designed as an ISO Class 5 cleanroom in accordance with ISO 14644.

Together with each calibration of a 2D photo mask customers obtain additionally to the measured values a data evaluation program which helps to characterise 2D measurement equipments such as projectors, measuring microscopes, optical probing 2D coordinate measuring machines according to ISO 10360.