公开(公告)号：US20150138523A1

公开(公告)日：2015-05-21

申请号：US14403010

申请日：2013-05-01

Applicant: ASML Netherland B.V.

Inventor： Martin Jacobus Johan Jak ,  Armand Eugene Albert Koolen ,  Hendrik Jan Hidde Smilde

IPC: G03F7/20

CPC classification number: G03F7/70625 ,  G03F7/70483 ,  G03F7/70633 ,  G03F7/70683

Abstract: A metrology target formed by a lithographic process on a substrate includes a plurality of component gratings. Images of the target are formed using +1 and −1 orders of radiation diffracted by the component gratings. Regions of interest (ROIs) in the detected image are identified corresponding the component gratings. Intensity values within each ROI are processed and compared between images, to obtain a measurement of asymmetry and hence overlay error. Separation zones are formed between the component gratings and design so as to provide dark regions in the image. In an embodiment, the ROIs are selected with their boundaries falling within the image regions corresponding to the separation zones. By this measure, the asymmetry measurement is made more tolerant of variations in the position of the ROI. The dark regions also assist in recognition of the target in the images.

Abstract translation: 由基板上的光刻工艺形成的测量目标包括多个分量光栅。 使用由分量光栅衍射的+1和-1次辐射来形成目标的图像。 识别检测到的图像中的感兴趣区域（ROI）对应于分量光栅。 在每个ROI内的强度值被处理并在图像之间进行比较，以获得不对称性的测量并因此获得覆盖误差。 在分量光栅之间形成分离区并设计成在图像中提供暗区。 在一个实施例中，选择其边界落入对应于分离区域的图像区域内的ROI。 通过这种措施，使不对称测量更加容忍ROI的位置的变化。 黑暗的地区也有助于识别图像中的目标。