Patent ID: 11971664
Assignee: KLA-TENCOR CORPORATION
Field: Optics (Instruments)
Classification: CPC G  H | IPC G  H

Claim 0:
1. A process control method utilizing a metrology target on a wafer in lithographic preparation, the metrology target comprising a previous layer that includes periodic structures, the process control method comprising:
deriving metrology measurements from the periodic structures at the previous layer directly following production thereof and prior to production of a current layer that includes periodic structures,
deriving metrology measurements from the periodic structures at the previous layer after an etch stage is applied thereto, and prior to the production of the periodic structures at the current layer, wherein at least some of the periodic structures in the current layer are directly over the periodic structures in the previous layer in a grating-over-grating arrangement, wherein the metrology measurements from before and after the etch stage are used to generate derived metrology measurements, and wherein at least part of the periodic structures at the previous layer are not printed or are etched away due to process errors, and
using the derived metrology measurements from only the previous layer to adjust at least a lithography stage that is part of production of the current layer, wherein the periodic structures at the previous layer directly following production, the periodic structures at the previous layer after the etch stage, and the periodic structures at the current layer each include pairs of the periodic structures that are aligned end-to-end in a same measurement direction, and wherein in each of the pair at the previous layer and the pair in the current layer, one periodic structure is segmented with device-like segmentation and the other periodic structure is unsegmented.