Lithographic apparatus and device manufacturing method

• US 20050118528A1
• Filed: 10/26/2004
• Published: 06/02/2005
• Est. Priority Date: 11/07/2003
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Bleeker, Arno Jan
• Granted Patent: US 7,196,772 B2
• Time in Patent Office: Days
• US Class Current: 430/270.100
• CPC Class Codes: G02F 1/03 based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect G02F1/061 takes precedence
• CPC Class Codes: G02F 2203/12 spatial light modulator
• 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

Abstract

An array of individually controllable elements is comprised of elements, each formed of a stack of layers of dielectric material. At least one layer is an electro-optical material. The at least one layer'"'"'s refractive index for radiation that is plane polarized in a given direction can be changed by application of a voltage in order to change the reflection/transmission characteristic of the boundary between this layer and the adjacent layer.

Claims

1. A lithographic apparatus, comprising:

an illumination system that produces a beam of radiation;

an array of individually controllable elements that patterns the beam; and

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

wherein each element in the array of individually controllable elements comprises a stack of top, middle, and bottom dielectric layers, at least the middle dielectric layer comprising a solid state electro-optical material,

whereby on application of a control signal the element is selectively changed between a first state and a second state, such that proportions of the radiation that are transmitted and reflected, respectively, at a boundary between the middle dielectric layer and at least one of the top or bottom dielectric layers are different in the first and second states.

2. The lithographic apparatus of claim 1, wherein:

during the first state there is a first difference value in refractive index for one polarization state between the middle dielectric layer and the top and bottom dielectric layer; and

during the second state there is a second difference value, which is smaller than the first difference value, in the refractive index for the one polarization state.

3. The lithographic apparatus of claim 1, wherein the stack further comprises:

additional layers of dielectric material, wherein at least one of the additional layers is formed from electro-optical material,

whereby a refractive index of the at least one additional layer for one polarization state is changed by applying a control signal to the middle dielectric layer of electro-optical material.

4. The lithographic apparatus of claim 3, wherein:

alternate dielectric layers of the stack are formed from material with a fixed refractive index; and

respective other layers are formed from an electro-optical material having a refractive index for a given respective polarization state that is changed by applying the control signal to each of the respective other layers.

5. The lithographic apparatus of claim 4, further comprising:

electrodes that are configured to apply a common control signal to the dielectric layers formed from the electro-optical material that have substantially mutually parallel extraordinary axes.

6. The lithographic apparatus of claim 3, wherein the layers of electro-optical material are arranged such that their respective extraordinary axes are substantially mutually parallel.

7. The lithographic apparatus of claim 3, wherein at least two layers of electro-optical material are arranged such that their extraordinary axes are substantially mutually perpendicular.

8. The lithographic apparatus of claim 3, further comprising:

electrodes that apply an independently controllable control voltage to each layer of the electro-optical material within the stack.

9. The lithographic apparatus of claim 3, further comprising:

electrodes that apply a common control voltage to two or more layers of the electro-optical material within the stack.

10. The lithographic apparatus of claim 1, wherein each of the elements in the array of individually controllable elements controls a propagation of the radiation that is plane polarized in a first direction and, independently, a propagation of the radiation that is plane polarized in a second direction and substantially orthogonal to the first direction.

11. The lithographic apparatus of claim 10, wherein the illumination system has a secondary source plane and generates a beam having four poles in the secondary source plane.

12. The lithographic apparatus of claim 11, wherein:

the four poles are arranged in first and second pairs;

a first line joining centers of the first pair is orthogonal to a second line joining centers of the second pair poles; and

the first and second lines intersect substantially at an optical axis of the illumination system.

13. The lithographic apparatus of claim 12, wherein:

the radiation of the first pair is plane polarized in the first direction; and

the radiation of the second pair is plane polarized in the second direction.

14. An array of individually controllable elements that pattern a beam of radiation, wherein each element in the array of individually controllable elements comprises:

top, middle, and bottom dielectric layers, at least the middle dielectric layer being formed of a solid state electro-optical material,

wherein on application of a control signal the element is selectively changed between a first state and a second state, such that proportions of the radiation that are transmitted and reflected, respectively, at a boundary between the middle dielectric layer and at least one of the top or bottom dielectric layers are different in the first and second states.

15. The element of claim 14, wherein:

during the first state there is a first difference value in refractive index for one polarization state between the middle dielectric layer and the top and bottom dielectric layers; and

during the second state there is a second difference value, which is smaller than the first difference value, in the refractive index for the one polarization state.

16. A device manufacturing method, comprising:

forming each element in an array of individually controllable elements from top, middle, and bottom dielectric layers;

forming at least the middle dielectric layer from a solid state electro-optical material;

patterning a beam of radiation from an illumination source using the array of individually controllable elements; and

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

17. The method of claim 16, further comprising:

applying a control signal to each the elements to selectively switch the element between a first state and a second state, such that proportions of the radiation that are transmitted and reflected, respectively, at a boundary between the middle dielectric layer and at least one of the top or bottom dielectric layers are different in the first and second states.

18. The method of claim 17, further comprising:

during the first state there is a first difference value in refractive index for one polarization state between the middle dielectric layer and the top and bottom dielectric layers; and

during the second state there is a second difference value, which is smaller than the first difference value, in the refractive index for the one polarization state.