Vistec Semiconductor Systems Gmbh

Kla-Tencor Mie Gmbh

Wolfgang Sulik

Michael Heiden

Lambert Danner

Alexander Buettner

A method for focusing an object plane () through an objective () and an optical assembly (), with which the method can be carried out, are disclosed. A geometric reference structure () is positioned in a plane () conjugate to a field plane () of the objective () and is imaged onto the object plane (). The geometric reference structure () is illuminated with a light beam (), which encloses a non-zero angle (&#x3c6;) with a normal direction () of the conjugate plane (). Therefore a position (Y) of an image () of the geometric reference structure () in the object plane () depends on the signed distance () between the object plane () and the field plane (), and correspondingly is evaluated for the determination of the focus position. The optical assembly () preferentially may be a metrology tool () for measuring structures () on masks (), wherein the objective () is the measurement objective of the metrology tool ().

Method for focusing an object plane and optical assembly

An apparatus for inspecting a surface of a wafer includes an illumination device for illuminating an imaging area of the wafer with at least one broad-band spectrum, and an optical imaging device with a detector for polychromatic imaging of the imaging area of the wafer based on the illumination, wherein the imaging device includes a filter arrangement for selecting a plurality of narrow-band spectra. In addition, a method for inspecting the surface of a wafer, includes the steps of leveling a plurality of narrow-band spectra to a common intensity range, illuminating an imaging area of the wafer with at least one broad-band spectrum, and imaging a plurality of narrow-band spectra from the imaging area based on the illumination.

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Asslar, Germany

Wolfgang Sulik