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1. (WO2017148577) DEVICE FOR CHANGING A SURFACE SHAPE OF AN OPTICAL ELEMENT BY MEANS OF ELECTRON IRRADIATION

Pub. No.:    WO/2017/148577    International Application No.:    PCT/EP2017/000255
Publication Date: Sat Sep 09 01:59:59 CEST 2017 International Filing Date: Fri Feb 24 00:59:59 CET 2017
IPC: G02B 1/12
G02B 5/08
G03F 7/20
Applicants: CARL ZEISS SMT GMBH
Inventors: PAULS, Walter
AHLES, Florian
WEISER, Martin
Title: DEVICE FOR CHANGING A SURFACE SHAPE OF AN OPTICAL ELEMENT BY MEANS OF ELECTRON IRRADIATION
Abstract:
The invention relates to a device (10) for changing the shape of a surface (12) of an optical element (14) by means of electron irradiation. The device (10) comprises an electron irradiation device (16) for irradiating electrons onto the surface (12) with a spatially resolved energy dose distribution (36) in order to produce local material compressions in the optical element (14). The device (10) further comprises a controller (32) for ascertaining a spatially resolved energy dose distribution (36) from a specified target change (34) in the surface shape of the optical element (14) by means of an optimization process with a minimization of a quality function (50) such that a difference between the target change and an actual change in the surface shape of the optical element produced on the basis of the ascertained specification is minimized. The quality function (50) contains a conversion term (42) for converting a local compaction, which describes a material compression in the region of the surface (12), into a resulting shape change of the surface (12). The conversion term (42) takes into consideration both a surface depression (20) produced by the local compaction as well as a deformation of the surface (12) produced on the basis of forces acting parallel to the surface (12). The invention further relates to a corresponding method and a projection objective for microlithography.