Kla Tencor Corporation

Haixing Zhou

Shankar Krishnan

Walter Dean Mieher

Haiming Wang

David Lidsky

Methods and apparatus for measuring an optical azimuth angle &#x3c6;of a substrate relative to a plane of detection in scatterometry tools are disclosed. A grating target on a stage of a scatterometry tool may be illuminated and positions of the resulting diffraction orders may be observed. The optical azimuth angle may be determined from the positions of the diffraction orders. Alternatively, polarization-dependent signals of radiation scattered from a line grating may be measured for equal and opposite polarization angles +A and &#x2212;A. A combination signal may be computed from the polarization-dependent signals obtained at +A and &#x2212;A and a property of the combination signal may be calculated for several mechanical Azimuth angles &#x3c6;. A relationship between the optical azimuth angle &#x3c6;and the mechanical azimuth angle &#x3c6;may be determined from a behavior of the property as a function of mechanical azimuth angle &#x3c6;.

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Sunnyvale, CA, United States of America

Haixing Zhou