A demonstrator adaptive optics-system with a thermally actuated active mirror (AM) is presented to pre-study feasibility of sub-nm wavefront control in extreme ultraviolet (EUV) lithography. The AM is thermally actuated by selective heating using a spatial controllable heat source. Four different methods have been implemented to control the deformation of the AM. First thermal feedforward using estimated state feedback (ESF), second thermal feedback using proportional integral (PI) control, third their combination and fourth deformation feedback using PI control. To support ESF, a thermo-elastic finite element model is employed that describes the thermal deformation of the AM. ESF shows satisfying performance with a time constant of 10 s and a residual error of 0.7 nm. Thermal feedback shows large fluctuations of 12 nm for spherical aberrations of due to feedback of noise from the thermal camera. By applying deformation feedback the RMS-error is reduced to a satisfying 0.25 nm. This study shows that deformation control of this AM can be realised using thermal feedforward and deformation feedback to meet the requirements for EUV lithography.

A new contact-less transport system for thin and fragile products like silicon wafers is introduced. The product is carried on a thin film of air separating the product from the system, and is transported using the relative velocity of the pressurized and moving air film parallel and adjacent to the system surface. This innovative concept can produce both the high stiffness and acceleration required for high precision positioning and efficient product transport. In this paper the basic design principles of this system are presented. Experimental verification is demonstrated on a 6-dof planar air actuated high precision positioning stage.

An autonomous capacitive sensor system for high accuracy and stability position measurement, such as required in high-precision industrial equipment, is presented. The system incorporates a self-alignment funcion based on a thermal stepping motor and a built-in capacitive reference, to guarantee that the relative position between the sensor electrodes is set to 10 ± 0.1µm. This is needed to achieve the performance specifications with the capacitive readout. In addition, an electronic zoom-in method is used to reach the 10 pm resolution with minimum power dissipation. Finally, periodic self-calibration of the electronic capacitance readout is realized using a very accurate and stable built-in resistive reference. The performance is evaluated experimentally and with simulations. Keywords: Capacitive Sensor System, Position Measurement, Self Alignment, Self Calibration, Thermal Actuator