Projection objective of a microlithographic projection exposure apparatus

摘要

A projection objective of a microlithographic projection exposure apparatus includes a wavefront correction device including a refractive optical element that has two opposite optical surfaces, through which projection light passes, and a circumferential rim surface extending between the two optical surfaces. A first and a second optical system are configured to direct first and second heating light to different portions of the rim surface such that at least a portion of the first and second heating light enters the refractive optical element. A temperature distribution caused by a partial absorption of the heating light results in a refractive index distribution inside the refractive optical element that corrects a wavefront error. At least the first optical system includes a focusing optical element that focuses the first heating light in a focal area such that the first heating light emerging from the focal area impinges on the rim surface.

主权项

1. A projection objective configured to use projection light to image an object onto a light sensitive surface, the projection objective comprising:
a wavefront correction device, comprising:
a refractive optical element comprising a first optical surface, a second optical surface opposite the first optical surface, and a circumferential rim surface between the first and second optical surfaces, wherein the first and second optical surfaces are configured so that, during use of the projection objective to image the object onto the light sensitive surface, projection light passes through the first and second optical surfaces;a first optical system configured to direct a first heating light to a first portion of the circumferential rim surface so that at least a portion of the first heating light enters the refractive optical element; anda second optical system configured to direct a second heating light to a second portion of the circumferential rim surface so that at least a portion of the second heating light enters the refractive optical element, wherein:
the second portion of the circumferential rim surface is different from the first portion of the circumferential rim surface;during use of the first and second optical systems, a temperature distribution caused by a partial absorption of the first heating light and the second heating light changes a refractive index distribution inside the refractive optical element;the first optical system comprises a focusing optical element configured to focus the first heating light in a focal area so that, during use of the first optical system, heating light emerging from the focal area impinges on the first portion of the rim surface;the first heating light is strongly absorbed in the refractive optical element than the projection light;the second heating light is strongly absorbed in the refractive optical element than the projection light;the first heating light has a center wavelength between 2.0 μm and 2.3 μm or between 2.6 μm and 2.8 μm;the second heating light has a center wavelength between 2.0 μm and 2.3 μm or between 2.6 μm and 2.8 μm;the projection light has a center wavelength between 150 nm and 500 nm; andthe projection objective is a microlithography projection objective.