Method of measurement, an inspection apparatus and a lithographic apparatus
AssigneeASML Netherlands B.V.
InventorsEverhardus Cornelis Mos, Maurits Van Der Schaar
Life of this patent
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Abstract
Radiation is projected onto a plurality of targets on a substrate. By assuming that the overlay error derivable from asymmetry varies smoothly across the substrate, the number of targets measured can be reduced. This may result in a smaller area of the scribe lane being used by targets for each layer of the substrate.
Claims16
A method of measuring an overlay error in a substrate, the method comprising:
- projecting a beam of radiation onto a plurality of targets at a plurality of positions on the substrate;
- measuring radiation reflected from each of the plurality of targets on the substrate using a scatterometer;
- and
- detecting and calculating an extent of the overlay error from the reflected radiation,
- wherein the calculation assumes that a proportion of the overlay error in each target deriving from asymmetry of the targets is constant for the plurality of positions.
An inspection apparatus configured to measure a property of a substrate, the apparatus comprising:
- a radiation projector configured to project radiation onto a plurality of targets at a plurality of positions on the substrate;
- a detector configured to detect radiation reflected from each of the targets;
- and
- a data handling unit configured to calculate overlay error on the basis of the radiation reflected from the plurality of targets assuming that the overlay error deriving from the asymmetry of the targets is constant for the plurality of targets.
A lithographic apparatus comprising:
- an illumination support configured to condition a radiation beam;
- a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam;
- 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
- an inspection apparatus configured to measure a property of a substrate, the apparatus comprising:
- a detector configured to detect radiation reflected from each of a plurality of targets at a plurality of positions on a substrate;
- and
- a data handling unit configured to calculate overlay error on the basis of the radiation reflected from the plurality of targets assuming that the overlay error deriving from the asymmetry of the targets is constant for the plurality of targets.
A method of measuring an overlay error in a substrate, the method comprising:
- projecting a beam of radiation onto a plurality of targets at a plurality of positions on the substrate;
- measuring radiation reflected from each of the plurality of targets on the substrate using a scatterometer;
- and
- detecting and calculating an extent of the overlay error from the reflected radiation,
- wherein the calculation assumes that a proportion of the overlay error in each target deriving from a parameter is constant for the plurality of positions.
An inspection apparatus configured to measure a property of a substrate, the apparatus comprising:
- a radiation projector configured to project radiation onto a plurality of targets at a plurality of positions on the substrate;
- a detector configured to detect radiation reflected from each of the targets;
- and
- a data handling unit configured to calculate overlay error on the basis of the radiation reflected from the plurality of targets assuming that the overlay error deriving from a parameter is constant for the plurality of targets.
Dependencies are inferred from the claim text.