Measurement method of overlay mark
AssigneeUnited Microelectronics Corp.
InventorsWei-Jhe Tzai, Kuei-Chun Hung, Chun-Chi Yu, Chien-Hao Chen, Chia-Ching Lin
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Abstract
A measurement method of an overlay mark is provided. An overlay mark on a wafer is measured with a plurality of different wavelength regions of an optical measurement tool, so as to obtain a plurality of overlay values corresponding to the wavelength regions. The overlay mark on the wafer is measured with an electrical measurement tool to obtain a reference overlay value. The wavelength region that corresponds to the overlay value closest to the reference overlay value is determined as a correct wavelength region for the overlay mark.
Claims19
A measurement method of an overlay mark, comprising:
- measuring an overlay mark on a wafer with a plurality of different wavelength regions of an optical measurement tool, so as to obtain a plurality of overlay values corresponding to the wavelength regions;
- measuring the overlay mark on the wafer with an electrical measurement tool to obtain a reference overlay value;
- and
- determining, as a correct wavelength region for the overlay mark, the wavelength region that corresponds to the overlay value closest to the reference overlay value.
Dependencies are inferred from the claim text.