Method and Apparatus for Determining Alignment Properties of a Beam of Radiation
AssigneeASML Netherlands B.V.
InventorSietse Thijmen VAN DER POST
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Abstract
A method of and an apparatus for use in determining one or more alignment properties of an illumination beam of radiation emitted by a radiation source are provided. The illumination beam is for irradiating a target area on a substrate in a metrology apparatus. The method comprises: (a) obtaining a first set of intensity data; (b) obtaining a second set of intensity data; (c) processing said first and second sets of intensity data to determine said one or more alignment properties of said illumination beam of radiation; wherein said processing involves comparing said first and second sets of intensity data to calculate a value which is indicative of a translation of said illumination beam of radiation.
Claims17
-15. (canceled)
A method of determining one or more alignment properties of an illumination beam of radiation emitted by a radiation source, wherein the illumination beam is for irradiating a target area on a substrate in a metrology apparatus, the method comprising:
- (a) obtaining a first set of intensity data representing a reference measurement, the first set of intensity data representing a projection of a first beam of radiation originating from the illumination beam of radiation onto a first pixelated sensor;
- (b) obtaining a second set of intensity data representing a projection of a second beam of radiation originating from the illumination beam of radiation onto the first pixelated sensor or a second pixelated sensor;
- and
- (c) processing the first and second sets of intensity data to determine the one or more alignment properties of the illumination beam of radiation;
- wherein the processing involves comparing the first and second sets of intensity data to calculate a signal value that is indicative of a change in an alignment property of the illumination beam of radiation.
The method of 22, wherein the first periodic structure is arranged to diffract radiation into a second diffraction order, and the first and second sets of intensity data are obtained by detecting radiation diffracted into the second diffraction order.
A metrology apparatus for use in determining a property of a structure on a substrate and to determine one or more alignment properties of an illumination beam of radiation emitted by a radiation source, the apparatus comprising:
- an irradiation system for generating the illumination beam of radiation;
- a substrate support operable with the irradiation system for irradiating a periodic structure formed on a target area of the substrate held by the substrate support;
- a specular detection branch detector for detecting a spectrum of radiation diffracted by the periodic structure;
- and
- one or more processors configured to:
- obtain a first set of intensity data representing a reference measurement, the first set of intensity data representing a projection of a first beam of radiation originating from the illumination beam of radiation onto a first pixelated sensor;
- obtain a second set of intensity data, the second set of intensity data representing a projection of a second beam of radiation originating from the illumination beam of radiation onto the first pixelated sensor, or a second pixelated sensor;
- and
- process the first and second sets of intensity data to determine the one or more alignment properties of the illumination beam of radiation;
- wherein the processing involves comparing the first and second sets of intensity data to calculate a value which is indicative of a change in an alignment property of the illumination beam of radiation.
The metrology apparatus of claim 31, wherein the one or more processors are further configured to use the alignment property to control the illumination beam in order to adjust a value of the alignment property.
Dependencies are inferred from the claim text.