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EP-4741921-A1 - ELECTROSTATIC OBJECT SUPPORT AND METHODS OF MANUFACTURE THEREOF

EP4741921A1EP 4741921 A1EP4741921 A1EP 4741921A1EP-4741921-A1

Abstract

Disclosed is an electrostatic object support for supporting an object. The electrostatic object support comprises a base layer; an electrode on said base layer and at least one dielectric layer extending fully over the electrode, wherein the at least one dielectric layer comprises a first coated dielectric sub-layer being comprised of a first dielectric material and a second coated dielectric sub-layer being comprised of a second dielectric material.

Inventors

  • SCHMIDT, VOLKER

Assignees

  • ASML Netherlands B.V.

Dates

Publication Date
20260513
Application Date
20241106

Claims (15)

  1. An electrostatic object support for supporting an object, the electrostatic object support comprising: a base layer; an electrode on said base layer; and at least one dielectric layer extending fully over the electrode, wherein the at least one dielectric layer comprises at least a first coated dielectric sub-layer being comprised of a first dielectric material and a second coated dielectric sub-layer being comprised of a second dielectric material, the second dielectric material being different from said first dielectric material.
  2. An electrostatic object support as claimed in claim 1, wherein the first coated dielectric sub-layer has been coated on the electrode and the second coated dielectric sub-layer has been coated on the first coated dielectric sub-layer.
  3. An electrostatic object support as claimed in claim 1 or 2, wherein the first coated dielectric sub-layer has been formed by a first coating process and the second coated dielectric sub-layer has been formed by a second coating process, being different to said first coating process.
  4. An electrostatic object support as claimed in claim 3, wherein the first coating process comprises a sputtering process and/or the second coating process comprises a chemical vapor deposition process.
  5. An electrostatic object support as claimed in any preceding claim, wherein the first dielectric material comprises silicon nitride; and/or wherein the second dielectric material comprises diamond.
  6. An electrostatic object support as claimed in any preceding claim, wherein the second dielectric material comprises microcrystalline diamond.
  7. An electrostatic object support as claimed in any preceding claim, wherein each of the first coated dielectric sub-layer and second coated dielectric sub-layer comprises a film layer.
  8. An electrostatic object support as claimed in any preceding claim, further comprising a plurality of burls for supporting the object thereon.
  9. An electrostatic object support as claimed in claim 8, wherein said electrode and the at least one dielectric layer extends over at least a portion of a respective top surface of at least some of said plurality of burls.
  10. An electrostatic object support as claimed in any preceding claim, wherein said electrode comprises at least a first electrode portion and a second electrode portion, each electrically insulated from the other.
  11. An electrostatic object support as claimed in any preceding claim, being configured for clamping a substrate thereto.
  12. A lithographic apparatus comprising: at least one of: an electrostatic object support as claimed in claim 11, being configured to retain a substrate to be patterned; and/or an electrostatic object support as claimed in any of claims 1 to 10, being configured to retain a patterning device for patterning a beam of radiation.
  13. A metrology and/or inspection apparatus, comprising: an electrostatic object support as claimed in claim 11, being configured to retain a substrate to be measured and/or inspected.
  14. A method of manufacturing an electrostatic object support, comprising: obtaining a base layer comprising an electrode; coating said electrode with a first dielectric material using a first coating process to obtain a first coated dielectric sub-layer; and coating said first coated dielectric sub-layer with a second dielectric material using a second coating process to obtain a second coated dielectric sub-layer; wherein said first dielectric material is different from said second dielectric material; and wherein said first coating process is different from said second coating process.
  15. A method as claimed in claim 14, wherein said electrostatic object support comprises the electrostatic object support of any of claims 1 to 11.

Description

FIELD The present invention relates to exposure apparatuses or lithographic apparatuses used in the manufacture of integrated circuits. In particular, the present invention relates to an electrostatic object support, such as an electrostatic reticle support or electrostatic substrate support for such apparatuses. More generally, the present invention relates to electrostatic object supports for supporting any object. BACKGROUND A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus may, for example, project a pattern at a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate. To project a pattern on a substrate a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features which can be formed on the substrate. A lithographic apparatus, which uses extreme ultraviolet (EUV) radiation, having a wavelength within the range 4-20 nm, for example 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than a lithographic apparatus which uses, for example, radiation with a wavelength of 193 nm. EUV lithographic devices use reflective optics to prevent the absorption of the EUV radiation by transmissive elements. These reflective optics include the patterning device, typically referred to as the "mask" or "reticle" (all three terms are synonymous), to pattern a radiation beam. The patterned radiation beam is then used to expose a portion of a substrate. Each of the patterning device and substrate is supported by a respective object support, i.e., a patterning device support and a substrate support. To prevent absorption of the EUV radiation used in an EUV lithographic device, the patterning device and substrate may be operated within a vacuum environment, making it impossible to use vacuum clamps for the object supports. As such, the clamping of each object to its respective support may be performed using an electrostatic object support, e.g., an electrostatic clamp. It would be desirable to improve on present electrostatic object supports. SUMMARY In a first aspect of the invention, there is provided an electrostatic object support for supporting an object, the electrostatic object support comprising: a base layer; an electrode on said base layer and at least one dielectric layer extending fully over the electrode, wherein the at least one dielectric layer comprises at least a first coated dielectric sub-layer being comprised of a first dielectric material and a second coated dielectric sub-layer being comprised of a second dielectric material, the second dielectric material being different from said first dielectric material. In a second aspect of the invention, there is provided a method of manufacturing an electrostatic object support, comprising: obtaining a base layer comprising an electrode; coating said electrode with a first dielectric material using a first coating process to obtain a first coated dielectric sub-layer; and coating said first coated dielectric sub-layer with a second dielectric material using a second coating process to obtain a second coated dielectric sub-layer; wherein said first dielectric material is different from said second dielectric material; and wherein said first coating process is different from said second coating process. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which: Figure 1 depicts a lithographic system comprising a lithographic apparatus and a radiation source;Figure 2(a) is a top view and Figure 2(b) is a side view schematic illustration of an electrostatic clamp;Figure 3 is a schematic illustration of a first electrostatic clamp according to concepts disclosed herein; andFigure 4 is a schematic illustration of a second electrostatic clamp according to concepts disclosed herein. DETAILED DESCRIPTION Figure 1 shows a lithographic system comprising a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and to supply the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure MT (or reticle stage) configured to support a patterning device MA (e.g., a mask), a projection system PS and a substrate table WT configured to support a substrate W. The illumination system IL is configured to condition the EUV radiation beam B before the EUV radiation beam B is incident upon the patterning device MA. Thereto, the illumination system IL may include a facetted field mirror device 10 and a facetted pupil mirror device 11. The faceted field mirror device 10 and faceted pupil mirror device 11 together pr