公开(公告)号：US20200232931A1

公开(公告)日：2020-07-23

申请号：US16751104

申请日：2020-01-23

申请人： ASML Netherlands B.V. ,  Stichting Nederlandse Wetenschappelijk Onderzoek Instituten ,  Stichting VU ,  Universiteit van Amsterdam

发明人： Stefan Michiel WITTE ,  Gijsbert Simon Matthijs JANSEN ,  Lars Christian FREISEM ,  Kjeld Sijbrand Eduard EIKEMA ,  Simon Gijsbert Josephus MATHIJSSEN

IPC分类号： G01N21/88 ,  G03F7/20 ,  G01J9/00 ,  G01J1/42 ,  G01N21/95

摘要： A metrology apparatus (302) includes a higher harmonic generation (HHG) radiation source for generating (310) EUV radiation. Operation of the HHG source is monitored using a wavefront sensor (420) which comprises an aperture array (424, 702) and an image sensor (426). A grating (706) disperses the radiation passing through each aperture so that the image detector captures positions and intensities of higher diffraction orders for different spectral components and different locations across the beam. In this way, the wavefront sensor can be arranged to measure a wavefront tilt for multiple harmonics at each location in said array. In one embodiment, the apertures are divided into two subsets (A) and (B), the gratings (706) of each subset having a different direction of dispersion. The spectrally resolved wavefront information (430) is used in feedback control (432) to stabilize operation of the HGG source, and/or to improve accuracy of metrology results.