Lithographic apparatus, alignment method and device manufacturing method
AssigneeASML Netherlands B.V.
InventorsKeith Frank Best, Alexander Friz, Joseph J. Consolini, Henricus Wilhelmus Maria Van Buel, Cheng-Qun Gui
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Abstract
To align between layers having a large Z separation, an alignment system which illuminates reference markers with normally incident radiation is used. The alignment system has an illumination system that is telecentric on the substrate side.
Claims14
A lithographic projection apparatus, comprising:
- a radiation system constructed and arranged to provide a projection beam of radiation;
- a support structure constructed and arranged to support a patterning device, the patterning device constructed and arranged to pattern the projection beam according to a desired pattern;
- a substrate table constructed and arranged to hold a substrate;
- a projection system constructed and arranged to project the patterned beam onto a target portion of the substrate;
- and
- an alignment system constructed and arranged to detect alignment between a reference mark and an alignment mark provided on the substrate, the alignment system comprising an optical system constructed and arranged to illuminate the alignment mark with an alignment beam, wherein the optical system is adapted to direct the alignment beam so as to be substantially normal to the substrate on the alignment mark.
A method of alignment to first and second alignment marks provided on respective first and second layers in a device formed on a substrate, the first and second layers having a large separation in the direction normal to the substrate, and the second layer having been formed after the first layer, the method comprising:
- deep trench etching layers of the device covering the first layer to reveal the first alignment mark;
- performing an alignment to the first alignment mark using an alignment system that illuminates the first alignment mark with an alignment beam that is substantially normal to the substrate;
- and
- performing an alignment to the second alignment mark using the alignment system.
Dependencies are inferred from the claim text.