公开(公告)号：EP2457251A4

公开(公告)日：2017-11-08

申请号：EP10802700

申请日：2010-07-16

Applicant: KLA-TENCOR CORP

Inventor： ZHAO GUOHENG ,  VAEZ-IRAVANI MEHDI ,  YOUNG SCOTT ,  BHASKAR KRIS

IPC: G01N21/95 ,  G01N21/88

CPC classification number: G01N21/9501 ,  G01N21/8806 ,  G01N2021/8822

Abstract: A dark field inspection system that minimizes the speckle noise due to sample surface roughness can include a plurality of beam shaping paths for generating a composite, focused illumination line on a wafer. Each beam shaping path can illuminate the wafer at an oblique angle. The plurality of beam shaping paths can form a ring illumination. This ring illumination can reduce the speckle effect, thereby improving SNR. An objective lens can capture scattered light from the wafer and an imaging sensor can receive an output of the objective lens. Because the wafer illumination occurs at oblique angles, the objective lens can have a high NA, thereby improving optical resolution of the imaging sensor, and the resulting signal level.