Lithographic apparatus and method

Patent metadata

Field	Value
Publication number	US-9519224-B2
Application number	US-201214351012-A
Country	US
Kind code	B2
Filing date	Sep 21, 2012
Priority date	Oct 20, 2011
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

A lithographic apparatus comprising a support structure constructed to support a patterning device, the patterning device being capable of imparting an EUV radiation beam with a grating in its cross-section to form a patterned EUV radiation beam, and a projection system configured to project the patterned EUV radiation beam onto a target portion of the substrate, wherein the support structure is provided with a grating comprising a series of first reflective portions which alternates with a series of second reflective portions, the second reflective portions having a reflectivity which is less than the reflectivity of at least part of the first reflective portions and which is greater than zero.

First claim

What is claimed is:

1. A lithographic apparatus comprising:
a support structure comprising first and second portions, wherein:
the first portion is different from the second portion;
the first portion is configured to support a patterning device,
the second portion comprises a grating,
the grating comprises first and second reflective portions,
the first and second reflective portions are positioned in an alternating pattern,
the second reflective portions have a first reflectivity smaller than a second reflectivity of at least sub-portions of the first reflective portions, the first reflectivity being greater than zero, and
the patterning device is configured to impart an EUV radiation beam with a pattern in its cross-section to form a patterned EUV radiation beam; and

a projection system configured to project the patterned EUV radiation beam onto a target portion of a substrate.

2. The lithographic apparatus of claim 1 , wherein the first and second reflective portions comprise unpatterned areas.

3. The lithographic apparatus of claim 2 , wherein the first and second reflective portions comprise rectangular shapes.

4. The lithographic apparatus of claim 1 , wherein:
each of the first reflective portions comprises a sub-grating having reflective lines and absorbing lines; and
each of the second reflective portions comprises an unpatterned area.

5. The lithographic apparatus of claim 4 , wherein the grating is configured such that the first reflectivity substantially matches a mean reflectivity of the reflective lines and the absorbing lines.

6. The lithographic apparatus of claim 1 , wherein the grating further comprises an absorbing portion located between a pair of first and second reflective portions from among the first and second reflective portions.

7. The lithographic apparatus of claim 1 , wherein the grating is configured such that a mean intensity of radiation reflected by the first reflective portions and received by the substrate is substantially equal to a mean intensity of radiation reflected by the second reflective portions and received by the substrate.

8. The lithographic apparatus of claim 1 , wherein:
each of the second reflective portions comprises a layer of absorbing material located over a mirror;
the layer of absorbing material is configured to allow transmission of at least a portion of the EUV radiation beam towards the mirror; and
the mirror is configured to reflect at least a sub-portion of the at least a portion of the EUV radiation beam towards the layer of absorbing material.

9. The lithographic apparatus of claim 1 , wherein the first reflectivity is half of the second reflectivity.

10. The lithographic apparatus of claim 1 , wherein the support structure further comprises a second grating having an opposite orientation to the grating.

11. The lithographic apparatus of claim 1 , wherein the support structure further comprises another grating extending in a transverse direction to the grating.

12. The lithographic apparatus of claim 1 , wherein the grating is configured such that a first radiation dose per unit area projected onto the substrate from the second reflective portions is substantially equal to a second radiation dose per unit area projected onto the substrate from the first reflective portions.

13. The lithographic apparatus of claim 1 , further comprising an alignment apparatus configured to:
measure a center of gravity of an image of the grating projected onto the substrate; and
measure a dose of the EUV radiation beam received by the substrate based on the center of gravity.

14. The lithographic apparatus of claim 1 , further comprising an alignment apparatus configured to:
measure a position of an image of the grating projected onto the substrate; and
determine a location of a focal plane of the projection system based on the position of the image of the grating.

15. The lithographic apparatus of claim 1 , wherein the support structure further comprises another grating having a pattern that is a mirror image of a pattern of the grating.

16. A patterning device comprising:
first and second reflective portions, wherein:
the second reflective portions have a first reflectivity smaller than a second reflectivity of at least sub-portions of the first reflective portions;
each of the first reflective portions comprises a sub-grating having reflective lines and absorbing lines;
the first reflectivity is greater than zero and substantially matches a mean reflectivity of the reflective lines and the absorbing lines; and
each of the second reflective portions comprises an unpatterned area.

17. The patterning device of claim 16 , wherein the patterning device further comprises an absorbing portion located between a pair of first and second reflective portions from among the first and second reflective portions.

18. A support structure of a lithography apparatus comprising:
first and second portions, wherein:
the first portion is different from the second portion;
the first portion is configured to support a patterning device;
the second portion comprises a grating;
the grating comprising first and second reflective portions;
the first and second reflective portions are positioned in an alternating pattern;
the second reflective portions have a first reflectivity smaller than a second reflectivity of at least sub-portions of the first reflective portions; and
the first reflectivity is greater than zero.

19. The support structure of claim 18 , wherein the grating further comprises an absorbing portion located between a pair of first and second reflective portions from among the first and second reflective portions.

Assignees

• Asml Netherlands Bv

Inventors

• Gijsbertsen Arjan
• Geraets Hubertus Antonius
• Segers Bart Peter Bert
• Davydova Natalia Viktorovna

Classifications

• G03F7/70641

  Focus · CPC title

• G03F7/702 Primary

  Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems · CPC title

• G03F9/7084

  Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels · CPC title

• G01T1/02

  Dosimeters (G01T1/15 takes precedence) · CPC title

• G03F7/70558 Primary

  Dose control, i.e. achievement of a desired dose · CPC title