DICHROIC MIRROR, METHOD FOR MANUFACTURING A DICHROIC MIRROR, LITHOGRAPHIC APPARATUS, SEMICONDUCTOR DEVICE AND METHOD OF MANUFACTURING THEREFOR

• US 20090284728A1
• Filed: 05/01/2009
• Published: 11/19/2009
• Est. Priority Date: 05/02/2008
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: VAN EMPEL, Tjarko Adriaan Rudolf
• Granted Patent: US 8,451,429 B2
• Time in Patent Office: Days
• US Class Current: 355/71
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G02B 27/1073 characterized by manufacturing or alignment methods
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G02B 27/142 Coating structures, e.g. thin films multilayers
• CPC Class Codes: G02B 5/0816 Multilayer mirrors, i.e. having two or more reflecting layers G02B5/0883, G02B5/0891 take precedence
• CPC Class Codes: G02B 5/0891 Ultraviolet [UV] mirrors apparatus for microlithography exposure G03F7/70; X-ray multilayer structures G21K1/06
• CPC Class Codes: G03B 27/72 Controlling or varying light intensity, spectral composition, or exposure time in photographic printing apparatus
• CPC Class Codes: G03F 7/7015 Details of optical elements
• CPC Class Codes: G03F 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• CPC Class Codes: G03F 7/70308 Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift
• CPC Class Codes: G03F 7/70575 Wavelength control, e.g. control of bandwidth, multiple wavelength, selection of wavelength or matching of optical components to wavelength
• CPC Class Codes: G03F 7/70958 Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties
• CPC Class Codes: G21K 1/062 Devices having a multilayer structure

Abstract

A dichroic mirror configured to separate a first type of radiation in a first wavelength range having an upper boundary from a second type of radiation in a second wavelength range having a lower boundary greater than the upper boundary of the first wavelength. The mirror includes a substrate, and a stack having a reflective surface facing away from the substrate and a width that increases stepwise in a direction towards the substrate. The stack is formed by alternating layers of first and second materials on the substrate. The reflective surface has steps with a width greater than the upper boundary of the first wavelength and less than the lower boundary of the second wavelength.

Claims

1. A dichroic mirror configured to separate a first type of radiation in a first wavelength range having an upper boundary from a second type of radiation in a second wavelength range having a lower boundary greater than the upper boundary of the first wavelength, the mirror comprising:

a substrate; and

a stack having a reflective surface facing away from the substrate and a width that increases stepwise in a direction towards the substrate, the stack being formed by alternating layers of first and second materials on the substrate, the reflective surface having steps with a width greater than the upper boundary of the first wavelength and less than the lower boundary of the second wavelength.

2. The dichroic mirror according to claim 1, wherein a surface of the stack, facing away from the substrate is provided with a reflecting coating, and wherein the reflecting coating has an outer contour that substantially matches a relief profile formed by the at least one stack.

3. The dichroic mirror according to claim 2, wherein the reflecting coating comprises a reflecting layer.

4. The dichroic mirror according to claim 2, wherein the reflecting coating comprises a Bragg-reflector.

5. The dichroic mirror according to claim 1, wherein the first type of radiation is extreme ultraviolet radiation, and the second type of radiation is infrared radiation.

6. The dichroic mirror according to claim 1, wherein the mirror comprises a plurality of stacks, wherein each stack has a reflective surface facing away from the substrate and a width that increases stepwise in the direction towards the substrate, and wherein each stack is formed by alternating layers of the first and second materials on the substrate, the reflective surfaces having steps with widths greater than the upper boundary of the first wavelength and less than the lower boundary of the second wavelength.

7. A lithographic apparatus, comprising:

a radiation source configured to provide a beam of radiation;

an illumination system configured to condition the beam of radiation;

a support configured to support a patterning device, the patterning device configured to impart the beam with a pattern in its cross-section;

a substrate support configured to hold a substrate;

a projection system configured to project the patterned beam onto a target portion of the substrate; and

a dichroic mirror arranged between the radiation source and the substrate, the dichroic mirror being configured to separate a first type of radiation in a first wavelength range having an upper boundary from a second type of radiation in a second wavelength range having a lower boundary greater than the upper boundary of the first wavelength, the dichroic mirror comprising

a mirror substrate, and

a stack having a reflective surface facing away from the mirror substrate and a width that increases stepwise in a direction towards the mirror substrate, the stack being formed by alternating layers of first and second materials on the mirror substrate, the reflective surface having steps with a width greater than the upper boundary of the first wavelength and less than the lower boundary of the second wavelength.

8. The lithographic apparatus according to claim 7, wherein a plane through the normal of the reflective surface of the dichroic mirror and the optical path of incident radiation on the reflective surface is oriented along a length direction of the steps.

9. The lithographic apparatus according to claim 7, wherein the dicbroic mirror comprises a plurality of stacks, wherein each stack has a reflective surface facing away from the substrate and a width that increases stepwise in the direction towards the substrate, and wherein each stack is formed by alternating layers of the first and second materials on the substrate, the reflective surfaces having steps with widths greater than the upper boundary of the first wavelength and less than the lower boundary of the second wavelength.

10. A method of manufacturing a dichroic mirror configured to separate a first type of radiation in a first wavelength range having an upper boundary from a second type of radiation in a second wavelength range having a lower boundary greater than the upper boundary of the first wavelength range, the method comprising:

(a) forming an etch stack comprising alternating layers of first and second materials on a substrate surface, the first and second materials being configured to provide relative etch selectivity; and

(b) creating a plurality of staircase patterns in the etch stack, wherein the staircase patterns have at least three levels and each level is formed by

(i) forming a resist film on top of the stack;

(ii) exposing respective patterned regions and developing to uncover regions of the stack;

(iii) etching one or more layers of the stack at an uncovered region of resist; and

(iv) repeating (i) through (iii), such that for a plurality of levels, a width of the uncovered region is decreased.

11. The method according to claim 10, further comprising coating a surface facing away from the substrate with a layer that substantially matches the staircase patterns and that is reflective for both the first type of radiation and for the second type of radiation.

12. The method according to claim 10, wherein the layers of the first material have a thickness that is substantially less than the layers of the second material and wherein the layers of the first material function as a hard mask for the layers of the second material.

13. The method according to claim 10, wherein the first material is a silicon nitride or a silicon carbide, and the second material is a phosphor silicate glass.

14. The method according to claim 10, further comprising applying a reflecting coating at a surface of the stack facing away from the substrate, wherein the reflecting coating has an outer contour that substantially matches that of the relief profile.

15. The method according to claim 10, further comprising forming a plurality of etch stacks comprising alternating layers of the first and second materials on the substrate surface.

16. A device manufacturing method, comprising:

providing a beam of radiation; and

removing a undesired radiation of the beam with a dichroic mirror to form a filtered beam of radiation, the dichroic mirror comprising

a substrate, and

a stack having a reflective surface facing away from the substrate and a width that increases stepwise in a direction towards the substrate, the stack being formed by alternating layers of first and second materials on the substrate, the reflective surface having steps with a width greater than an upper wavelength boundary of a desired radiation and less than a lower wavelength boundary of the undesired radiation;

patterning the filtered beam of radiation; and

projecting a patterned beam of radiation onto a target portion of a device substrate.

17. The device manufacturing method according to claim 16, wherein the dichroic mirror comprises a plurality of stacks, wherein each stack has a reflective surface facing away from the substrate and a width that increases stepwise in the direction towards the substrate, and wherein each stack is formed by alternating layers of the first and second materials on the substrate, the reflective surfaces having steps with widths greater than the upper wavelength boundary of the desired radiation and less than the lower wavelength boundary of the undesired radiation.

18. A device manufactured according to the method of claim 16.