Shear-Layer Chuck for Lithographic Apparatus

Abstract

A lithographic apparatus is described that comprises a support structure (300) to hold an object (210). The object may be a patterning device or a substrate to be exposed. The support structure comprises a chuck (321), on which the object is supported, and an array of shear-compliant elongated elements (325) normal to the chuck and the stage (230), such that first ends of the elongated elements contact a surface of the chuck and second ends of the elongated elements contact a stage. Through using the array of elongated elements, a transfer of stress between the stage and the chuck is substantially uniform, resulting in minimization of slippage of the object relative to the surface of the chuck during a deformation of the chuck due to the stress.

Description

BACKGROUND[0001]1. Field of the Invention[0002]The present invention relates to a lithographic apparatus and method of securely holding an object in the lithographic apparatus.[0003]2. Related Art[0004]A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g., comprising part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging the pattern using a UV radiation beam onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjac...

AI Technical Summary

Benefits of technology

[0011]It is desirable to design a chuck that provides a desired shear compliance to minimize slippage of a supported object under a condition of stress, but does not suffer from the limitations described above.

[0012]According to a first embodiment of the present invention, a system comprises a chuck and an array of elongated elements having first and second respective ends, such that the first ends contact the chuck and the second ends contact a stage. Through using the array of elongated elements, a transfer of stress between the stage and the chuck is rendered substantially uniform, resulting in minimization of slippage of an object relative to the first surface of the chuck during a movement of the chuck relative to the stage.

[0014]According to a further embodiment, a lithographic apparatus comprises an illumination system configured to produce a beam of radiation, a patterning device configured to pattern the beam of radiation, a projection system configured to project the patterned beam of radiation onto a substrate, and a support system. The support system comprises a chuck having a first surface and a second surface, and an array of elongated elements having first and second respective ends and having longitudinal axes, the longitudinal axes being normal to the second surface of the chuck, such that the first ends contact the second surface of the chuck and the second ends contact a stage. Through using the array of elongated elements, a transfer of stress between the stage and the chuck is substantially uniform, resulting in minimization of slippage of an object relative to the first surface of the chuck during a deformation of the chuck due to the stress. The pattering device or the substrate is configured to be the object mounted on the chuck.

[0015]According to yet another embodiment, a system supporting an object comprises a chuck having a first surface that supports the object; a stage that supports the chuck in one or more directions of translation or rotation; and an interface layer between the chuck and the stage with a relatively low stiffness in at least one direction of translation or rotation with respect to the other directions of translation or rotation, resulting in minimization of slippage of the object relative to the first surface of the chuck during deformation of the chuck due to a stress between the stage and the chuck.

Problems solved by technology

When acceleration is imparted to the stage during exposure or pre-exposure alignment, a stress is transferred from the stage to the chuck, and this stress may cause the chuck as well as the object to deform.

Typically the transfer of acceleration-induced stress from the stage to the chuck (as well as from the chuck to the object) is not uniform.

This gives rise to a potential for slip between the chuck and the object, especially in cases where the chuck deformation is large.

Chuck deformation may also be caused by temperature differences between the stage, the chuck, and / or the object, resulting in slippage of the object relative to the chuck.

However, kinematic mounts at a number of discrete locations may not uniformly distribute the transfer of stress.

Thus, it may be difficult to tailor burls 225 for a desired shear compliance in all directions of interest.

Burls 225 that directly contact object 210 typically have high compliance in normal direction as well, making it harder to optimize the overall shear compliance of the system.

Moreover, burls 225 with the desired shear compliance are typically long and slender, and their shape makes electrostatic clamping of the object quite challenging.

Additionally, planarity of object 210 may be compromised due to non-uniform stress distribution in burls 225.

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