Method to obtain a height map of a substrate having alignment marks, substrate alignment measuring apparatus and lithographic apparatus
AssigneeASML Netherlands B.V.
InventorsBram Van Hoof, Arjan Hölscher, Alex Pascal Ten Brink, Petrus Franciscus Van Gils
Life of this patent
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Abstract
The present invention provides a method to obtain a height map of a substrate having alignment marks, the method comprising the steps: determining a height of one or more locations or areas of the substrate, and determining the height map of the substrate on the basis of the determined height of the one or more locations or areas of the substrate and a shape model of the substrate.
Claims14
A method to obtain a height map of a substrate having alignment marks, the method comprising the steps of:
- determining a height of one or more locations or areas of the substrate;
- and
- determining the height map of the substrate based on the determined height of the one or more locations or areas of the substrate and a shape model of the substrate;
- wherein the shape model of the substrate is determined based on at least a single scan height map of the substrate by a level sensor, a low resolution height map of the substrate, and height measurements by a substrate stage position measurement system.
An alignment measuring apparatus to measure positions of multiple alignment marks on a substrate, comprising:
- a first station, comprising a first alignment sensor system to measure positions of one or more alignment marks at different tilted and/or offset positions of the substrate;
- and
- a processing unit to determine a height of the one or more alignment marks on the basis of the measured positions of the one or more alignment marks, and to determine the height map of the substrate on the basis of the determined height of the one or more alignment marks and a shape model of the substrate;
- wherein the shape model of the substrate is determined on the basis of a single scan height map of the substrate by a level sensor and/or a low resolution height map of the substrate.
A lithographic apparatus, comprising:
- a first station, comprising an alignment sensor system to measure positions of one or more alignment marks at different tilted and/or offset positions of the substrate;
- a processing unit to determine a height of the one or more alignment marks on the basis of the measured positions of the one or more alignment marks, and to determine the height map of the substrate on the basis of the determined height of the one or more alignment marks and a shape model of the substrate;
- and
- a second station, comprising a projection system to project successively a patterned radiation beam on multiple target portions of the substrate, wherein the lithographic apparatus is arranged to adapt, in the second station, for each target portion, a height and/or tilt position of the substrate on the basis of the height map provided by the processing unit.
Dependencies are inferred from the claim text.