US 11,940,264 B2
Mirror calibrating method, a position measuring method, a lithographic apparatus and a device manufacturing method
Johannes Mathias Theodorus Antonius Adriaens, Eindhoven (NL); Carolus Johannes Catharina Schoormans, Hooge Mierde (NL); and Luuk Johannes Helena Seelen, Vlodrop (NL)
Assigned to ASML NETHERLANDS B.V., Veldhoven (NL)
Appl. No. 17/624,276
Filed by ASML NETHERLANDS B.V., Veldhoven (NL)
PCT Filed Jun. 5, 2020, PCT No. PCT/EP2020/065651
§ 371(c)(1), (2) Date Dec. 31, 2021,
PCT Pub. No. WO2021/004709, PCT Pub. Date Jan. 14, 2021.
Claims priority of application No. 19184747 (EP), filed on Jul. 5, 2019.
Prior Publication US 2022/0357147 A1, Nov. 10, 2022
Int. Cl. G01B 11/00 (2006.01); G03F 7/00 (2006.01)
CPC G01B 11/005 (2013.01) [G03F 7/70775 (2013.01); G03F 7/7085 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for calibrating a mirror of an interferometer system configured to measure a position of an object, which interferometer system includes a first interferometer and a second interferometer, wherein the first interferometer is arranged to provide a first position signal representative of a position of the object in a X-direction by directing a first measurement beam on a first mirror, wherein the second interferometer is arranged to provide a second position signal representative of the position of the object in the X-direction by directing a second measurement beam on a second mirror, and wherein the first mirror and the second mirror are arranged on opposite sides of the object and extend in a Y-direction, wherein the method comprises
a. generating a first data set comprising the first position signal and the second position signal for each of a plurality of positions of the object in the Y-direction while the object is in a first rotational orientation and in a first position in a Z-direction;
b. tilting the object to a second rotational orientation about a rotation axis perpendicular to the X-direction;
c. generating a second data set comprising the first position signal and the second position signal for each of a plurality of positions of the object in the Y-direction while the object is in the second rotational orientation and in the first position in the Z-direction; and
d. determining a shape of the first mirror and/or a shape of the second mirror in the Y-direction based on the first data set and the second data set.