Technique for CD measurement on the basis of area fraction determination
AssigneeAdvanced Micro Devices, Inc.
InventorsEckhard Langer, Moritz-Andreas Meyer
Life of this patent
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Abstract
The present invention provides a technique for estimating critical dimensions of highly scaled circuit features on the basis of scanning electron microscopy, wherein area fractions of a scan area are determined. Preferably, the SEM is operated with high electron beam energies to enhance the overall resolution and to reduce edge effects and image artifacts. Thus, fast and statistically significant measurement results may be obtained, thereby allowing enhanced process control.
Claims11
A method of monitoring critical dimensions of features formed above a substrate, the method comprising:
- scanning an area of said substrate by a scanning inspection tool to obtain an image of said area, said area including at least a portion of one or more of said features;
- determining an area fraction in said image on the basis of at least one image parameter and a predefined threshold for said parameter;
- and
- using said area fraction as a measure of a mean value of said critical dimension in said area.
An inspection system, comprising:
- a measurement section configured to generate an image signal in response to scanning a selected area of a surface portion of a substrate;
- an image processing section configured to establish an image of said selected area on the basis of said image signal;
- an area calculation section configured to determine an area fraction in said image on the basis of a threshold for a predefined image parameter;
- and
- a comparison unit configured to compare said area fraction with a reference value for estimating critical dimensions of features contained in said area.
Dependencies are inferred from the claim text.