Lithographic apparatus and device manufacturing method

• US 20060055905A1
• Filed: 09/14/2004
• Published: 03/16/2006
• Est. Priority Date: 09/14/2004
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Baselmans, Johannes Jacobus Matheus, Vink, Henri Johannes Petrus, De Jager, Pieter Willem Herman, Bruinsma, Anastasius Jacobus Anicetus
• Granted Patent: US 7,079,225 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70583 Speckle reduction, e.g. coherence control or amplitude/wavefront splitting

Abstract

Use of a refraction grating to divide a beam of radiation into a plurality of sub-beams that are each directed onto an array of individually controllable elements, modulated thereby and projected onto a substrate as an array of spots.

Claims

1. A lithographic apparatus, comprising:

an illumination system that supplies a beam of radiation;

a refraction grating that divides the beam into a plurality of sub-beams;

an array of individually controllable elements being configured such that the plurality of said sub-beams of radiation are directed onto associated individually controllable elements in said array of individually controllable elements to pattern the beam; and

a projection system that projects the patterned beam onto a target portion of a substrate.

2. The lithographic apparatus of claim 1, wherein said refraction grating comprises:

first and second arrays of elongate lenses,

wherein the beam passes consecutively through the first and second arrays of elongate lenses;

wherein each of the lenses has a constant cross-section perpendicular to its elongate axis,

wherein the lenses of the first array of elongate lenses are arranged such that their elongate axes are mutually parallel, and

wherein the lenses of the second array of elongate lenses are arranged such that their elongate axes are perpendicular to those of the first array of elongate lenses.

3. The lithographic apparatus of claim 2, wherein said cross-section of at least one of the elongate lenses comprises a portion that is substantially at least a part of a circle.

4. The lithographic apparatus of claim 2, wherein the cross-sections of the elongate lenses in at least one of the first and second arrays of elongate lenses are substantially the same.

5. The lithographic apparatus of claim 2, wherein a distribution of intensities of the sub-beams of radiation is provided by at least one of:

a shape of the lenses in at least one of the first or second array of elongate lenses;

a width of at least one of the first or the second array of elongate lenses;

a separation between the elongate lenses in at least one of the first and second arrays of elongate lenses;

cross-sections of the lenses varying across at least one of the first or the second array of elongate lenses;

a radiation intensity profile of the beam of radiation incident on the refraction grating; and

one or more attenuators located between the refraction grating and the array of individually controllable elements.

6. The lithographic apparatus of claim 1, wherein each sub-beam is focused onto one or more of the individually controllable elements.

7. The lithographic apparatus of claim 1, wherein a single lens or lens group is used to focus all of the sub-beams onto the array of individually controllable elements.

8. The lithographic apparatus of claim 7, further comprising:

an array of focusing elements that focus the radiation from the array of individually controllable elements onto a plurality of spots on the substrate.

9. The lithographic apparatus of claim 8, wherein said single lens or lens group further directs the radiation from the arrays of individually controllable elements onto the array of the focusing elements.

10. The lithographic apparatus of claim 1, wherein:

the illumination system provides at least a further beam of radiation, and

the beam and the at least a further beam are directed onto the refraction grating and each divided into sub-beams.

11. The lithographic apparatus of claim 10, wherein the beam and the at least a further beam are directed onto the refraction grating at an angle relative to each other, such that at least one of the sub-beams derived from each beam coincides.

12. The lithographic apparatus of claim 11, wherein the beam and the at least a further beam provided by the illumination system are parallel to each other and are directed onto the refraction grating at relative angles by a lens or lens group.

13. A device manufacturing method, comprising:

dividing a beam of radiation into a plurality of sub-beams using a refraction grating;

directing the plurality of said sub-beams of radiation onto associated individually controllable elements in an array of individually controllable elements;

using said array of individually controllable elements to pattern each respective one of the plurality of said sub-beams; and

projecting the patterned beams onto a target portion of a substrate.