Optical projection systems and projection-exposure apparatus comprising same

摘要

The invention pertains to optical projection-exposure apparatus for photolithography that can focus a pattern defined by a mask onto a non-flat substrate. In one embodiment, piezoelectric elements are used as an actuator for adjusting the optical path length between the mask and the substrate. A first reflector reflects a light flux transmitted by the mask. A telecentric optical system then forms an image of the mask in a focal plane. A second reflector reflects the light flux from the telecentric perpendicularly onto the substrate. The actuator moves the first or second reflectors, changing the optical path length of the light flux. A focus sensor detects the height of the sensitized surface of the substrate in a direction perpendicular to the sensitized surface of the substrate and thereby provides a focus signal to the actuator. The actuator then moves the focal plane to the sensitized surface.