Burls with altered surface topography for holding an object in lithography applications

Patent metadata

Field	Value
Publication number	US-11270906-B2
Application number	US-201816756907-A
Country	US
Kind code	B2
Filing date	Oct 4, 2018
Priority date	Oct 27, 2017
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

Various burl designs for holding an object in a lithographic apparatus are described. A lithographic apparatus includes an illumination system, a first support structure, a second support structure, and a projection system. The illumination system is designed to receive radiation and to direct the radiation towards a patterning device that forms patterned radiation. The first support structure is designed to support the patterning device on the first support structure. The second support structure has a plurality of burls and is designed to support the substrate on the plurality of burls. A topography of a top surface of each of the plurality of burls is not substantially flat, such that a contact area between the substrate and each of the plurality of burls is reduced. The projection system is designed to receive the patterned radiation and to direct the patterned radiation towards the substrate.

First claim

What is claimed is:

1. A support structure having a plurality of burls and configured to support a substrate or a patterning device on the plurality of burls,
wherein a topography of a top surface of each of the plurality of burls is such that a contact area between the substrate or patterning device and each of the plurality of burls is reduced by at least 50% compared to a contact area of a flat topography at least when the substrate or patterning device is an unclamped state on the support structure, and
wherein one or more of the plurality of burls has a top surface topography that comprises a central protruding portion surrounded by a recess portion and the central protruding portion and the recess portion are surrounded by peripheral protruding portion.

2. The support structure of claim 1 , wherein the central protruding portion includes a central substantially flat portion surrounded by a sloped portion.

3. The support structure of claim 1 , wherein the central protruding portion has a cross-sectional dimension between 1 μm and 200 μm.

4. The support structure of claim 2 , wherein the sloped portion extends in a radial direction from the central substantially flat portion at a distance between 75 μm and 175 μm.

5. The support structure of claim 4 , wherein the sloped portion has a height between 50 nm and 1000 nm.

6. The support structure of claim 1 , wherein one or more of the plurality of burls has a top surface topography that includes a central non-ablated portion surrounded by an ablated portion that extends radially from the central non-ablated portion.

7. A support configured for use within a lithographic apparatus, the support comprising:
a base structure; and
a plurality of burls extending above a top surface of the base structure,
wherein a topography of a top surface of each of the plurality of burls reduces a contact area between a substrate or patterning device placed on the plurality of burls and each of the plurality of burls by at least 50% compared to a contact area of a flat topography at least when the substrate or patterning device is an unclamped state on the support structure, and
wherein one or more of the plurality of burls has a top surface topography that includes a central substantially flat portion surrounded by a sloped portion,
wherein the sloped portion extends in a radial direction from the central substantially flat portion at a distance between 75 μm and 175 μm.

8. The support of claim 7 , wherein the central substantially flat portion has a cross-sectional dimension between 1 μm and 200 μm.

9. The support of claim 7 , wherein the sloped portion has a height between 50 nm and 1000 nm.

10. The support of claim 7 , wherein one or more of the plurality of burls has a top surface topography that includes a rounded surface.

11. The support of claim 7 , wherein one or more of the plurality of burls has a top surface topography that includes a central non-ablated portion surrounded by an ablated portion that extends radially from the central non-ablated portion.

12. A support structure configured to support a substrate or a patterning device, the support structure includes a plurality of burls,
wherein a topography of a top surface of each of the plurality of burls is such that a contact area between the substrate or patterning device and each of the plurality of burls on the support structure is reduced by at least 50% compared to a contact area of a flat topography at least when the substrate or patterning device is an unclamped state on the support structure, and
wherein one or more of the plurality of burls has a top surface topography that comprises a convex rounded surface facing toward the substrate or patterning device and extending from a central portion of each respective top surface to the periphery of the respective top surface,
wherein the rounded surface has a radius of curvature between about 0.015 m and about 0.305 m.

13. The support structure of claim 12 , wherein the height of the rounded surface is between about 50 nm and about 1000 nm.

14. The support structure of claim 12 , wherein each of the burls have a total height between about 10 μm and about 150 μm.

15. The support structure of claim 12 , wherein one or more burls of the plurality of burls has a different top surface topography design than one or more other burls of the plurality of burls.

16. The support structure of claim 12 , wherein a first plurality of burls of the plurality of burls has a first top surface topography design and a second plurality of burls of the plurality of burls has a second different top surface topography design, the first plurality surrounding the second plurality.

17. A lithographic apparatus, comprising:
the support structure of claim 12 configured to hold a patterning device or substrate in the lithographic apparatus; and
a projection system configured to receive a patterned radiation and to direct the patterned radiation towards a substrate.

18. A lithographic apparatus, comprising:
the support structure of claim 1 configured to hold a patterning device or substrate in the lithographic apparatus; and
a projection system configured to receive a patterned radiation and to direct the patterned radiation towards a substrate.

19. A lithographic apparatus, comprising:
the support structure of claim 7 configured to hold a patterning device or substrate in the lithographic apparatus; and
a projection system configured to receive a patterned radiation and to direct the patterned radiation towards a substrate.

Assignees

• Asml Holding Nv

Inventors

• Akbas Mehmet Ali
• Peterson David Hart
• Uitterdijk Tammo
• Perry Michael
• Lewis Richard Bryan
• Sigal Iliya

Classifications

• H10P72/7614 Primary

  characterised by a plurality of individual support members, e.g. support posts or protrusions · CPC title

• H10P72/7616

  characterised by a coating, a hardness or a material · CPC title

• G03F7/70783

  Handling stress or warp of chucks, masks or workpieces, e.g. to compensate for imaging errors or considerations related to warpage of masks or workpieces due to their own weight · CPC title

• G03F7/707 Primary

  Chucks, e.g. chucking or un-chucking operations or structural details · CPC title

• G03F7/70708

  being electrostatic; Electrostatically deformable vacuum chucks · CPC title