Arrangement for stabilizing an irradiated mask

Abstract

A system for stabilizing an irradiated mask for use in lithographic set-ups, the mask including formations which are permeable to electromagnetic or corpuscular radiations, especially ion beams, the system having one or more cooling surfaces that surround the beam axis, are disposed in the field of view of the mask, and are located between the mask and the radiation source and/or behind the mask. The cooling surfaces preferably are in the form of surfaces of revolutions, are comprised of metal, have grooves that produce multiple reflections of the thermal radiation and are spaced equal distances apart from the axis of the optical path. The distances from the cooling surfaces to the axis of the optical path preferably exceed the distance from the edge of the mask sheet to the axis of the optical path. The mask is disposed in a chamber which is maintained by automatic control at a constant temperature, particularly at room temperature, e.g. by heating of the walls. The mask sheet is movable in the chamber to extend in front of an opening that is formed in a chamber wall and disposed in the optical path; the opening optionally being formed in a shutter which constitutes a part of the chamber wall, and the cooling surfaces are disposed in the field of view of the mask when the latter is disposed in front of the opening in the optical path, so that the heating action of the beam of radiation on the mask can be compensated by the cooling surfaces and the mask will be maintained approximately at the chamber temperature also during an irradiation.