Patent ID: 10824081

Abstract:
A method and apparatus is disclosed for monitoring critical dimensions in a pattern of 1-dimensional and/or 2-dimensional features, produced on a substrate in a process step that is part of or related to a manufacturing process for producing a semiconductor device, the process step being performed in accordance with a predefined pattern design, wherein one or more metrology targets (1) are added to the pattern design. The targets comprise one or more versions of an asymmetric metrology mark, each version of the mark comprising a uniform portion (2) and a periodic portion (3), the latter comprising a regular array of parallel line-shaped features or an array of 2-dimensional features. The design width of the features is situated in a range situated around a nominal design width w0. A position-related parameter S is defined that is essentially proportional to the design widths in the range. Determination of the shift δS of the S parameter with respect to a pre-defined process operating point, allows to assess the critical dimension of the features produced by the process step.