Patent ID: 9164402
Filing Date: 2015-10-20
Classification: G02B,G03F

Abstract:
1. A method, comprising: providing a projection objective which comprises a wavefront correction device, the wavefront correction device comprising: a first refractive optical element comprising a first optical material having, for an operating wavelength of the projection exposure apparatus, an index of refraction that decreases with increasing temperature; and a second refractive optical element comprising a second optical material having, for the operating wavelength of the projection exposure apparatus, an index of refraction that increases with increasing temperature, determining an aberration of the projection objective via measurement and/or simulation; determining, by taking into account the aberration, a first phase variation and a second phase variation, wherein, if the first phase variation is generated by the first refractive optical element and the second phase variation is generated by the second refractive optical element, the determined aberration is modified; generating the first phase variation by changing a temperature distribution in the first optical material using a first heating device; and generating the second phase variation by changing a temperature distribution in the second optical material using a second heating device that is distinct and independent from the first heating device.