US 6,982,796 B2
Wavefront splitting element for EUV light and phase measuring apparatus using the same
Ryuichi Sato, Tochigi (Japan)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Filed on Jan. 30, 2003, as Appl. No. 10/354,657.
Claims priority of application No. 2002-024470 (JP), filed on Jan. 31, 2002.
Prior Publication US 2003/0142322 A1, Jul. 31, 2003
Int. Cl. G01B 9/02 (2006.01)
U.S. Cl. 356—521 2 Claims
OG exemplary drawing
 
1. A phase measuring apparatus that measures phase information dependent on an angle incident on a film applied onto an object to be tested based on the interference information, said phase measuring apparatus comprising:
a beam splitter using a diffraction grating to split a beam from a light source into multiple beams including transmitting light and reflected light;
a reflecting mechanism for condensing one beam that has been split by said beam splitter, and introduces the beam to the object as well as introducing detection light reflected from the object into said beam splitter;
a reference plate for reflecting another beam that has been split by said beam splitter, and brings it into said beam splitter as reference light;
an imaging system for forming, on a predetermined surface, interference light obtained when the detection light and the reference light are superimposed by said beam splitter; and
a detector for detecting the interference information on the predetermined surface.