Distortion-Free X-ray Mask Technology.

摘要

The objective of this research project is to develop a closed-loop, feedback-controlled, robust system for reliably achieving zero stress in tungsten (W) films sputtered onto various x-ray mask membranes, and to transfer the technology to the National X-ray mask shop. Our system for controlling stress in sputtered W films is based on the measurement of resonant frequency. Since resonant frequency depends on both the thickness and the stress of the W films, if the thickness is known, the stress is easily calculated.