Form-error-cancelling mirror-support devices and related methods, and microlithography systems comprising same

In an X-ray optical system comprising at least one X-ray-reflective mirror mounted to a mounting structure in an optical column, a method for reducing a form error of the mirror, the method comprising:

• measuring a profile of a reflective surface of the mirror so as to determine a region on the reflective surface exhibiting a respective form error;
• contacting a mirror-side surface of the mirror with at least three mirror-support devices selected from the group consisting of pushing devices and pulling devices, wherein the at least three mirror-support devices contacting the mirror-side surface include at least one pushing device and at least one pulling device;
• positioning the mirror-support devices, between the mirror-side surface and the mounting structure, relative to each other and peripherally to the mirror so as (a) to contact the mounting structure and to hold the mirror relative to the mounting structure, and (b) on a respective first location on the mirror-side surface adjacent the region exhibiting the form error, to apply a respective compressive or tensile stress to the location using a respective mirror-support device, the stress being of a magnitude and direction sufficient to cancel at least a portion of the form error in the adjacent region.

A mirror-support apparatus for a reflective mirror having a mirror-side surface, the apparatus comprising:

• a mirror-mounting structure;
• and
• at least three mirror-support devices selected from the group consisting of pushing devices and pulling devices, the at least three mirror-support devices including at least one pushing device and at least one pulling device, the mirror-support devices being positioned, between the mirror-side surface and the mounting structure, relative to each other and peripherally to the mirror so as (a) to contact the mirror-mounting structure and to hold the mirror relative to the mounting structure, and (b) on a first location on the mirror-side surface adjacent an area of the mirror exhibiting a form error, to apply a compressive or tensile stress to the location using one of the pushing and pulling devices, respectively, the stress being of a magnitude and direction sufficient to cancel at least a portion of the form error in the adjacent area.

An X-ray optical system, comprising:

• an X-ray-reflective mirror having a mirror-side surface and a reflective surface;
• and
• a mirror-support apparatus for the mirror, the apparatus comprising (a) a mirror-mounting structure, and (b) at least three mirror-support devices selected from the group consisting of pushing devices and pulling devices, the at least three mirror-support devices including at least one pushing device and at least one pulling device, the mirror-support devices being positioned, between the mirror-side surface and the mounting structure, relative to each other and peripherally to the mirror so as to (i) to contact the mounting structure and to hold the mirror relative to the mounting structure, and (ii) on a first location on the mirror-side surface adjacent an area on the mirror exhibiting a form error, to apply a respective compressive or tensile stress to the location using one of the pushing and pulling devices, respectively, the stress being of a magnitude and direction sufficient to cancel at least a portion of the form error in the adjacent area.