US 11,754,934 B2
Projection exposure apparatus for semiconductor lithography having an optical element with sensor reference and method for aligning the sensor reference
Peter Nieland, Aalen (DE); Matthias Stepper, Ansbach (DE); and Hans-Martin Hoevel, Lippstadt (DE)
Assigned to Carl Zeiss SMT GmbH, Oberkochen (DE)
Filed by Carl Zeiss SMT GmbH, Oberkochen (DE)
Filed on Sep. 14, 2021, as Appl. No. 17/475,168.
Application 17/475,168 is a continuation of application No. PCT/EP2020/055413, filed on Mar. 2, 2020.
Claims priority of application No. 102019203838.7 (DE), filed on Mar. 20, 2019.
Prior Publication US 2022/0004111 A1, Jan. 6, 2022
Int. Cl. G03F 7/20 (2006.01); G03F 7/00 (2006.01)
CPC G03F 7/70833 (2013.01) [G03F 7/70258 (2013.01); G03F 7/70825 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of aligning a sensor reference with respect to a referential surface of a main body in an EUV projection exposure apparatus, the sensor reference comprising a reference element and a receiving element, the receiving element being fixed on the main body or a part of the main body, the method comprising:
determining an orientation of the referential surface in a reference coordinate system of the main body;
determining a deviation of the orientation of the referential surface from a target orientation thereof;
inserting the reference element into the receiving element;
determining a position and an orientation of the reference element in the reference coordinate system of the main body;
determining a deviation of the reference element from a target orientation thereof taking account of the previously determined orientation of the reference element and the deviation of the referential surface from its target orientation;
aligning the reference element with its target orientation;
fixing the orientation of the reference element with respect to the referential surface when the reference element is in its target orientation; and
checking the target orientation of the reference element in the reference coordinate system,
wherein the referential surface is configured so that, during use of the EUV projection exposure apparatus, the referential surface reflects EUV radiation.