US 12,406,777 B2
Optical element for a EUV projection exposure system
Hartmut Enkisch, Aalen (DE); Sandro Hoffmann, Giengen (DE); Joern Weber, Aalen (DE); Sebastian Strobel, Aalen (DE); Mirko Ribow, Oberkochen (DE); Christoph Nottbohm, Ulm (DE); Matthias Sturm, Waiblingen (DE); and Michael Krause, Ulm (DE)
Assigned to CARL ZEISS SMT GMBH, Oberkochen (DE)
Filed by Carl Zeiss SMT GmbH, Oberkochen (DE)
Filed on Dec. 22, 2022, as Appl. No. 18/087,262.
Application 18/087,262 is a continuation of application No. PCT/EP2021/065352, filed on Jun. 8, 2021.
Claims priority of application No. 10 2020 207 807.6 (DE), filed on Jun. 24, 2020.
Prior Publication US 2023/0126018 A1, Apr. 27, 2023
Int. Cl. G21K 1/06 (2006.01); G02B 1/12 (2006.01); G02B 5/08 (2006.01); G02B 5/18 (2006.01); G02B 5/20 (2006.01); G03F 7/00 (2006.01)
CPC G21K 1/062 (2013.01) [G02B 1/12 (2013.01); G02B 5/208 (2013.01); G03F 7/70175 (2013.01); G02B 5/0891 (2013.01); G02B 5/1857 (2013.01); G02B 2207/107 (2013.01); G21K 2201/064 (2013.01)] 14 Claims
OG exemplary drawing
 
1. An optical element for an extreme ultraviolet (EUV) projection exposure apparatus, comprising:
a substrate specifying a curved basic topography,
at least two shaping layers, applied onto the substrate, each with a layer thickness (Di(s)) according to a specified layer thickness profile (Div(s)),
a plurality of etch stop layers,
an EUV radiation-reflecting layer,
wherein at least one of the shaping layers is structured to form a grating structure with a bottom region, a front side, and a flank,
wherein a transition from the bottom region to the flank has a radius of curvature of at most 5 μm, and
wherein the EUV-radiation-reflecting layer is applied at least to the bottom region and to the front side of the grating structure.