Induced stress for EUV pellicle tensioning

Patent metadata

Field	Value
Publication number	US-11163229-B2
Application number	US-201916674582-A
Country	US
Kind code	B2
Filing date	Nov 5, 2019
Priority date	Dec 20, 2018
Publication date	Nov 2, 2021
Grant date	Nov 2, 2021

Abstract

A method for protecting a photomask comprises: (i) providing the photomask, (ii) providing a border, (iii) depositing at least two electrical contacts on the border, (iv) mounting a film comprising carbon nanotubes on the border such that the film comprises a free-standing part, wherein after the mounting and depositing steps, the electrical contacts are in contact with the film, (v) inducing a current through the free-standing part of the film by biasing at least one pair of the electrical contacts, and (vi) mounting the border on at least one side of the photomask with the free-standing part of the film above the photomask.

First claim

What is claimed is:

1. A method for protecting a photomask, the method comprising:
providing the photomask;
providing a border;
depositing at least two electrical contacts on the border;
mounting a film comprising carbon nanotubes on the border such that the film comprises a free-standing part, wherein after the mounting and depositing steps, the electrical contacts are in contact with the film;
inducing a current through the free-standing part of the film by biasing at least one pair of the electrical contacts; and
mounting the border on at least one side of the photomask with the free-standing part of the film above the photomask.

2. The method according to claim 1 , wherein inducing the current through the free-standing part of the film comprises inducing the current through at least two pairs of the electrical contacts.

3. The method according to claim 1 , wherein inducing the current through the free-standing part of the film comprises inducing a single current pulse through the free-standing part of the film.

4. The method according to claim 1 , wherein inducing the current through the free-standing part of the film comprises inducing a current pulse train with a predefined duty cycle through the free-standing part of the film.

5. The method according to claim 1 , wherein providing the border comprises providing a silicon border.

6. The method according to claim 5 , wherein providing the border comprises providing a silicon-based material and partially removing the silicon-based material.

7. The method according to claim 1 , wherein depositing the at least two electrical contacts comprises depositing a titanium seed layer followed by depositing palladium.

8. The method according to claim 1 , further comprising preparing the film by (i) dry transfer of carbon nanotubes or (ii) by extraction from a solution using vacuum filtration onto a filter paper.

9. The method according to claim 1 , further comprising applying isopropyl alcohol on the film after mounting the film.

10. The method according to claim 1 , further comprising providing a coating on the film.

11. The method according to claim 10 , wherein providing the coating comprises providing a partial coating on the film.

12. The method according to claim 10 , wherein providing the coating comprises providing a complete coating on the film.

13. The method according to claim 1 , further comprising applying a lithography step on the photomask, wherein the photomask is protected by the mounted film comprising carbon nanotubes.

14. A method for protecting a photomask, the method comprising:
providing the photomask;
providing a border;
mounting a film comprising carbon nanotubes on the border such that the film comprises a free-standing part;
inducing a current through the free-standing part of the film by applying a changing magnetic field in the free-standing part of the film; and
mounting the border on at least one side of the photomask with the free-standing part of the film above the photomask.

15. The method according to claim 14 , wherein inducing the current through the free-standing part of the film comprises inducing a single current pulse through the free-standing part of the film.

16. The method according to claim 14 , wherein inducing the current through the free-standing part of the film comprises inducing a current pulse train with a predefined duty cycle through the free-standing part of the film.

17. The method according to claim 14 , wherein providing the border comprises providing a silicon border.

18. The method according to claim 17 , wherein providing the border comprises providing a silicon-based material and partially removing the silicon-based material.

19. The method according to claim 14 , further comprising preparing the film by (i) dry transfer of carbon nanotubes or (ii) by extraction from a solution using vacuum filtration onto a filter paper.

20. The method according to claim 14 , further comprising applying isopropyl alcohol on the film after mounting the film.

Assignees

• Imec Vzw
• Univ Leuven Kath

Inventors

• Mariano Juste Marina
• Timmermans Marina
• Pollentier Ivan
• Huyghebaert Cedric
• Gallagher Emily

Classifications

• G03F1/62 Primary

  Pellicles, e.g. pellicle assemblies, e.g. having membrane on support frame; Preparation thereof · CPC title

• G03F1/64 Primary

  characterised by the frames, e.g. structure or material, including bonding means therefor · CPC title

• G03F7/70983

  Optical system protection, e.g. pellicles or removable covers for protection of mask · CPC title

• G03F1/40

  Electrostatic discharge [ESD] related features, e.g. antistatic coatings or a conductive metal layer around the periphery of the mask substrate · 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