Lithographic apparatus and device manufacturing method
AssigneeASML Netherlands B.V.
InventorWilliam Peter Van Drent
Life of this patent
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Abstract
A level sensor configured to measure a height level of a substrate arranged in a measurement position is disclosed. The level sensor comprises a projection unit to project multiple measurement beams on multiple measurement locations on the substrate, a detection unit to receive the measurement beams after reflection on the substrate, and a processing unit to calculate a height level on the basis of the reflected measurement beams received by the detection unit, wherein the projection unit and the detection unit are arranged next to the substrate, when the substrate is arranged in the measurement position.
Claims20
A level sensor configured to measure a height level of a substrate arranged in a measurement position, the level sensor comprising:
- a projection unit to project multiple measurement beams on multiple measurement locations on the substrate;
- a detection unit to receive the measurement beams after reflection on the substrate;
- a processing unit to calculate a height level on the basis of the reflected measurement beams received by the detection unit;
- a first reflection bar arranged to receive the measurement beams from the projection unit, and to direct the measurement beams to the substrate, the first reflection bar comprising an oblique first reflective surface onto which the measurement beams are incident and to reflect the measurement beams towards the substrate;
- and
- a second reflection bar arranged to receive the reflected measurement beams from the substrate, and to direct the reflected measurement beams to the detection unit, the second reflection bar comprising an oblique second reflective surface onto which the reflected measurement beams are incident and to reflect the reflected measurement beams towards the detection unit,
- wherein the first and second reflective surfaces face toward each other and toward the substrate.
A lithographic apparatus comprising:
- a support constructed to support a patterning device, the patterning device being capable of providing a radiation beam with a pattern in its cross-section;
- a substrate table constructed to hold a substrate;
- a projection system configured to project the patterned radiation beam onto a target portion of the substrate;
- and
- a level sensor configured to measure a height level of a substrate on the substrate table arranged in a measurement position, comprising:
- a projection unit to project multiple measurement beams on multiple measurement locations on the substrate,
- a first reflection bar arranged to receive the measurement beams from the projection unit and to direct the measurement beams to the substrate,
- a detection unit to receive the measurement beams after reflection on the substrate,
- a second reflection bar arranged to receive the reflected measurement beams from the substrate, and to direct the reflected measurement beams to the detection unit, wherein the length of the first and second reflection bars combine to be longer than the width of the substrate,
- a processing unit to calculate a height level on the basis of the reflected measurement beams received by the detection unit.
A method to determine a height map of a substrate, the method comprising:
- measuring a height of a substrate at a measurement location by projecting a measurement beam on the substrate using a projection unit and an oblique first reflective surface onto which the measurement beam is incident and to reflect the measurement beam towards the substrate, receiving the reflected beam from the substrate using a detection unit and an oblique second reflective surface onto which the reflected beam is incident and to reflect the reflected beam towards the detection unit, wherein the first and second reflective surfaces face toward each other and toward the substrate, and determining a height level based on the reflected beam received by the detection unit;
- repeating the measuring for multiple measurement locations on the substrate;
- and
- determining a height map of the substrate on the basis of the height levels.
Dependencies are inferred from the claim text.