Being the survey instrument and the survey instrument which measures the property of manner, the lithography device, the lithography

摘要

PROBLEM TO BE SOLVED: To provide an optical focus or position sensor, not requiring frequent off-line calibration, and/or achieving faster servo response.;SOLUTION: A scatterometer has a focus sensor arranged to detect whether or not the target being measured is in a correct focal plane. A modulation is applied to a component of the focus sensor or the scatterometer such that a defocus as measured by the focus sensor varies according to a certain function. From knowledge of the modulation, the gain of the sensor can be calibrated.;COPYRIGHT: (C)2009,JPO&INPIT