Defocus determination method using sub-resolution feature (srf) printing
AssigneeTexas Instruments Incorporated
InventorYong Seok Choi
Life of this patent
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Abstract
The present application is directed to apparatus and methods for determining a magnitude of defocus and a direction of defocus for a photolithography process. A sub-resolution feature on a reticle which is not printed on a wafer at the best focus offset, but is formed on a wafer at some defocus during the photolithography process is analyzed to determine the magnitude and direction of defocus. The magnitude and direction of defocus are used to adjust the photolithography process to an optimal focus based on the determined magnitude of defocus and the determined direction of defocus.
Claims22
An apparatus for determining a magnitude of defocus and direction of defocus for photolithography, comprising:
- an analyzer to analyze a shot for a sub-resolution feature;
- a magnitude determiner to determine a magnitude of the sub-resolution feature on the shot;
- and
- a defocus magnitude determiner to determine the magnitude of defocus;
- and
- a defocus direction determiner to determine the direction of defocus based on the sub-resolution feature.
A method of determining a magnitude of defocus and direction of defocus for photolithography, comprising:
- analyzing a wafer for a sub-resolution feature;
- determining a magnitude of the sub-resolution feature;
- calculating a magnitude of defocus;
- and
- calculating a direction of defocus based on the magnitude of the sub-resolution feature.
Apparatus for determining a magnitude of defocus and direction of defocus for photolithography, comprising:
- means for analyzing a wafer for a sub-resolution feature;
- means for determining a magnitude of the sub-resolution feature;
- means for calculating a magnitude of defocus;
- and
- means for calculating a direction of defocus based on the magnitude of the sub-resolution feature.
Dependencies are inferred from the claim text.