CPC G03F 7/70191 (2013.01) [G03F 7/7085 (2013.01); G03F 7/70091 (2013.01)] | 20 Claims |
1. A system comprising:
an illumination system configured to generate a beam of radiation having a first spatial intensity distribution at a pupil plane and a second spatial intensity distribution at a plane of a target, wherein the first spatial intensity distribution comprises an annular intensity profile or an intensity profile corresponding to three or more beams;
a lens element configured to focus the beam onto the target, wherein the second spatial intensity distribution is a conjugate of the first intensity distribution and comprises an intensity profile corresponding to a central beam and one or more side lobes that are substantially isolated from the central beam, and wherein the central beam has a beam diameter of approximately 20 microns or less at the target; and
a detector configured to receive radiation scattered by the target and to generate a measurement signal based on the received radiation.
|