公开(公告)号：US20160180517A1

公开(公告)日：2016-06-23

申请号：US14971887

申请日：2015-12-16

Applicant: ASML NETHERLANDS B.V.

Inventor： Andreas FUCHS ,  Peter Hanzen WARDENIER ,  Amandev SINGH ,  Maxime D' ALFONSO ,  Hilko Dirk BOS

IPC: G06T7/00

CPC classification number: G06T7/0004 ,  G03F7/70633 ,  G03F7/70941 ,  G06T7/11 ,  G06T2207/30148

Abstract: A scatterometer is used in a dark-field imaging mode to measure asymmetry-related parameters such as overlay. Measurements of small grating targets are made using identical optical paths, with the target in two orientations to obtain separate measurements of +1 and −1 diffraction orders. In this way, intensity scaling differences (tool asymmetry) are avoided. However, additive intensity defects due to stray radiation (ghosts) in the optical system cannot be avoided. Additive intensity issues strongly depend on the ratio between 0th and 1st order diffraction and are therefore strongly substrate (process) dependent. Calibration measurements are made on a few representative target gratings having biases. The calibration measurements are made, using not only different substrate rotations but also complementary apertures. Corrections are calculated and applied to correct asymmetry, to reduce error caused by stray radiation.

Abstract translation: 在暗场成像模式中使用散射仪来测量不对称相关的参数，如覆盖。 使用相同的光路进行小光栅目标的测量，目标在两个取向上以获得+1和-1衍射级的单独测量。 以这种方式，避免了强度缩放差异（工具不对称）。 然而，由于光学系统中的杂散辐射（重影）引起的附加强度缺陷是不能避免的。 添加强度问题很大程度上依赖于第0级和第1级衍射之间的比例，因此依赖于衬底（工艺）。 在具有偏差的几个代表性目标光栅上进行校准测量。 进行校准测量，不仅使用不同的衬底旋转，而且使用互补的孔。 校正被计算并应用于纠正不对称性，以减少由杂散辐射引起的误差。