US 7,002,694 B2Granted

Interferometer system and method for recording an interferogram using weighted averaging over multiple frequencies, and method for providing and manufacturing an object having a target surface

AssigneeCarl Zeiss SMT GmbH

InventorsStefan Schulte, Bernd Dörband, Henriette Müller, Wolfgang Kähler

Life of this patent

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Abstract

An interferometer system comprises a reference surface, a support for an object providing an object surface, a radiation source for emitting radiation of an adjustable frequency onto the reference surface and the object surface, a position-sensitive radiation detector, a controller for adjusting a plurality of different frequencies of the radiation emitted by the radiation source, and an integrator for averaging the interference patterns superposed on the radiation detector at different frequencies. Moreover, there is provided a method for recording an interferogram, a method for providing an object with a target surface as well as a method for manufacturing an object with a target surface.

Claims14

Dependent claims

An interferometer system, comprising:

a radiation source for emitting radiation of an adjustable frequency;
a reference surface;
a support for an object providing an object surface;
a position-sensitive radiation detector;
a disturbing interference surface;
a controller;
and
an integrator;
wherein the radiation source, the reference surface, the support and the radiation detector are positioned such that a first portion of the radiation emitted by the radiation source is incident on the reference surface and reflected as a reference wave field therefrom, a second portion of the radiation emitted by the radiation source is directed towards the object surface to generate an object wave field reflected from the object surface, and the reference wave field and the object wave field are superposed to form an interference pattern having a position-dependent intensity distribution on the radiation detector;
wherein the disturbing interference surface is positioned such that radiation emitted from the radiation source is incident thereon and that a disturbing wave field reflected from the disturbing interference surface contributes to the position-dependent intensity distribution on the radiation detector;
wherein the controller is configured for setting the adjustable frequency of the radiation emitted by the radiation source to a plurality of different frequencies;
and
wherein the integrator is controlled to perform position-dependent averaging over the different frequencies of the interference patterns formed on the radiation detector to thereby generate an interferogram.

10 more elements

A method of manufacturing an object having an object surface of a target shape, the method comprising:

illuminating a reference surface and the object surface with coherent radiation having a frequency;
superposing a reference wave field reflected from the reference surface and an object wave field reflected from the object surface such that an interference pattern with a position-dependent radiation intensity distribution is formed on a radiation receiving surface;
changing the frequency of the radiation successively to a plurality of different radiation frequencies, such that a plurality of interference patterns is successively formed on the radiation receiving surface in accordance with the respective different radiation frequencies;
generating an interferogram by a weighted averaging over the different radiation frequencies of intensities of the plurality of interference patterns at respective positions of the interferogram;
and
machining the object surface in dependence of the generated interferogram.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/743,792Filed 24 Dec 2003 · continuation
Priority: DE 101 30 90227 Jun 2001
Published: US 2004/0190002 A130 Sep 2004
Granted: 21 Feb 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

G01B 9/02057
Passive reduction of errors: by using common path configuration, i.e. reference and object path almost entirely overlapping
G01B 9/02004
Using two or more frequencies: using frequency scans
G01B 9/02039
Shaping the wavefront, e.g. generating a spherical wavefront: by matching the wavefront with a particular object surface shape
G01B 9/02059
Passive reduction of errors: reducing effect of parasitic reflections, e.g. cyclic errors