Mask stretching for next generation lithography masks

Next generation lithography tools, such as X-ray, ion, or electron beam lithography equipment set different standards for mask fabrication. A thin film membrane is now the carrier of the pattern to be copied on a substrate. Systematic aberrations are inevitable due to heat distortion during exposure and other influences. The possibility of integrating an active correction system in the mask is investigated and the mechanics for the elastic in-plane stretching of the mask are developed. Equations that relate actuator displacements to the displacement of a finite number of measurement points (or precision points) are derived for in-plane actuation of the mask membrane. A large-scale experimental model as well as a finite-element model was used to demonstrate the validity of this method.