公开(公告)号：US20190279842A1

公开(公告)日：2019-09-12

申请号：US16357309

申请日：2019-03-18

Applicant: ASML Netherlands B.V.

Inventor： Weiming REN ,  Shuai LI ,  Xuedong LIU ,  Zhongwei CHEN ,  Jack JAU

IPC: H01J37/28

Abstract: A multi-beam apparatus for observing a sample with oblique illumination is proposed. In the apparatus, a new source-conversion unit changes a single electron source into a slant virtual multi-source array, a primary projection imaging system projects the array to form plural probe spots on the sample with oblique illumination, and a condenser lens adjusts the currents of the plural probe spots. In the source-conversion unit, the image-forming means not only forms the slant virtual multi-source array, but also compensates the off-axis aberrations of the plurality of probe spots. The apparatus can provide dark-field images and/or bright-field images of the sample.