公开(公告)号：WO2016096524A1

公开(公告)日：2016-06-23

申请号：PCT/EP2015/078915

申请日：2015-12-08

Applicant: ASML NETHERLANDS B.V.

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

IPC: G03F7/20

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 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 light (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 wafer (process) dependent opposite. Calibration measurements (CM1-CM4) are made on a few representative target gratings having biases (+d, –d). The calibration measurements are made, using not only different wafer rotation (RZ = 0, π ) but also complementary apertures (13N, 13S). Corrections (δ, G) are calculated and applied calculate corrected asymmetry A', to reduce error caused by stray light.

Abstract translation: 在暗场成像模式中使用散射仪来测量不对称相关参数，如覆盖。 使用相同的光路进行小光栅靶的测量，其中目标在两个取向中以获得+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光（重影）引起的附加强度缺陷是无法避免的。 添加强度问题很大程度上取决于第0级和第1级衍射之间的比例，因此强晶片（工艺）依赖相反。 校准测量（CM1-CM4）在具有偏差（+ d，-d）的几个代表性目标光栅上进行。 进行校准测量，不仅使用不同的晶片旋转（RZ = 0，π），而且使用互补孔（13N，13S）。 校正（δ，G）被计算并应用计算校正不对称A'，以减少由杂散光引起的误差。