Reticle Optimization Algorithms and Optimal Target Design

摘要

Metrology target designs on reticle and wafer, and target design and processing methods are provided. Target designs are orthogonal periodic structures perpendicular to the measurement direction, having Coles pitch periodic structures with sub-element CD and / or fine pitch sub-elements varying in height, orthogonal unresolved pitch between periodically repeated bars. Which provides calibration parameters to achieve well printed targets. Orthogonal periodic structures may be designed on the reticle and not degraded, or may be applied in a cutting pattern on the process layer, with a relatively low sensitivity to the cutting layer overlay. Designed targets can be used to measure process parameters such as scanner aberrations and pitch walk as well as overlay metrology.