Protective Cap for Extreme Ultraviolet Lithography Masks

• US 20120141923A1
• Filed: 12/02/2010
• Published: 06/07/2012
• Est. Priority Date: 12/02/2010
• Status: Active Grant

• Current Assignee: Intermolecular Incorporated (Merck & Co., Inc.)
• Original Assignee: Intermolecular Incorporated (Merck & Co., Inc.)
• Inventors: Deweerd, Wim Yves
• Granted Patent: US 8,475,977 B2
• Time in Patent Office: Days
• US Class Current: 430/5
• CPC Class Codes: G03F 1/48 Protective coatings

Abstract

An extreme ultraviolet (EUV) lithography mask is provided. The EUV lithography mask includes a reflective layer and an absorptive layer deposited over the reflective layer. The absorptive layer is patterned so as to define absorptive regions of the mask for absorbing EUV radiation and reflective regions of the mask for reflecting EUV radiation. The EUV lithography mask further includes a protective capping layer which is deposited over both the absorptive regions and the reflective regions of the mask.

Claims

1. An extreme ultraviolet (EUV) lithography mask, comprising:

a reflective layer;

an absorptive layer deposited over the reflective layer, the absorptive layer being patterned so as to define absorptive regions of the mask for absorbing EUV radiation and reflective regions of the mask for reflecting EUV radiation; and

a protective capping layer, the protective capping layer being conformally deposited over both the absorptive regions and the reflective regions of the mask.

2. The EUV lithography mask of claim 1, wherein the protective capping layer is a continuous and homogeneous layer.

3. The EUV lithography mask of claim 1, wherein the protective capping layer has a thickness of less than about one nanometer.

4. The EUV lithography mask of claim 1, wherein the protective capping layer is substantially transparent to radiation having a wavelength of about 10 to 20 nanometers.

5. The EUV lithography mask of claim 1, wherein the protective capping layer includes a material selected from the group consisting of SiO₂, SiN, SiC, SiB, GeO₂, TiO2, HfO₂, ZrO₂, Al₂O₃, mixtures thereof.

6. The EUV lithography mask of claim 1, wherein the protective capping layer is deposited by an atomic layer deposition process.

7. An EUV lithography mask, comprising:

a top portion having absorptive regions for absorbing EUV radiation and reflective regions for reflecting EUV radiation;

a transparent passivation layer deposited over said top portion, the transparent passivation layer protecting the absorptive regions and the reflective regions of the top portion; and

a bottom portion including a reflective layer for reflecting EUV radiation.

8. The EUV lithography mask of claim 7, wherein the transparent passivation layer has a thickness of less than about one nanometer.

9. The EUV lithography mask of claim 8, wherein the transparent passivation layer is a material selected from the group consisting of SiO₂, SiN, SiC, SiB, GeO₂, TiO2, HfO₂, ZrO₂, Al₂O₃, mixtures thereof.

10. The EUV lithography mask of claim 7, wherein the reflective layer of the bottom portion is defined by a Bragg reflector.

11. The EUV lithography mask of claim 7, wherein the transparent passivation layer is substantially transparent to radiation having a wavelength of about 10 to 20 nanometers.

12. The EUV lithography mask of claim 7, wherein the transparent passivation layer is deposited by an atomic layer deposition process.

13. The EUV lithography mask of claim 7, wherein the transparent passivation layer is deposited over at least two different layer surfaces of the top portion.

14. The EUV lithography mask of claim 13, wherein the different layer surfaces are selected from the group consisting of an absorber layer, a buffer layer, and a capping layer.

15. A method for evaluating materials, unit processes, and process sequences for manufacturing an EUV lithography mask, comprising:

processing a first substrate having a first layer of material deposited over a second layer of material, the first and second layers representing a top portion of the EUV lithography mask;

testing the first substrate for adherence properties between the layers;

processing regions on a second substrate in a combinatorial manner by varying one of materials, unit processes or process sequences based on results from the testing of the first substrate, the regions on the second substrate representing a barrier layer deposited over the top portion of the EUV lithography mask; and

testing the processed regions on the second substrate for optical properties.

16. The method of claim 15, wherein the material for the first layer of the first substrate comprises a protective barrier layer material.

17. The method of claim 15, wherein the material for the second layer of the first substrate is selected from the group consisting of an absorber layer material, a buffer layer material, and a capping layer material.

18. The method of claim 15, wherein the top portion of the EUV lithography mask includes materials selected from the group consisting of an absorber layer material, a buffer layer material, and a capping layer material.

19. The method of claim 15, further comprising:

processing a third substrate utilizing the EUV lithography mask, wherein the EUV lithography mask is manufactured based on results from the testing of the first and the second substrates.