Lithographic apparatus and device manufacturing method

• US 7,826,035 B2
• Filed: 03/20/2007
• Issued: 11/02/2010
• Est. Priority Date: 11/07/2003
• Status: Expired due to Fees

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Bleeker, Arno Jan
• Primary Examiner(s): Nguyen; Hung Henry
• Assistant Examiner(s): Asfaw; Mesfin T
• Application Number:
  US11/725,499
• Publication Number:
  US 20070165203A1
• Time in Patent Office: 1,323 Days
• Field of Search: 355/53, 355/67, 355/77
• US Class Current: 355/67
• 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 includes 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 configured to produce a beam of radiation;

an array of individually controllable elements configured to pattern the beam; and

a projection system configured to project 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 that is plane polarized in an extraordinary axis,

wherein the middle dielectric layer of each element is configured to receive a respective control signal that has a first state and a second state,

wherein a portion of incident radiation having a first polarization state that is reflected by each element when the respective control signal is in the first and second states is different, and

wherein a portion of incident radiation having a second polarization state that is reflected by each element is substantially the same when the respective control signal is 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 the first 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 first 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 the first polarization state is changed by applying a control signal to the at least one additional 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 foil led 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 configured to 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 configured to 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 is configured to control 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 is configured to generate 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 that is plane polarized in an extraordinary axis,

wherein the middle dielectric layer of each element is configured to receive a respective control signal that has a first state and a second state,

wherein a portion of incident radiation having a first polarization state that is reflected by each element when the respective control signal is in the first and second states is different, and

wherein a portion of incident radiation having a second polarization state that is reflected by each element is substantially the same when the respective control signal is 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 the first 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 first polarization state.

16. A lithographic 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 that is plane polarized in an extraordinary axis, such that;

the middle dielectric layer of each element is configured to receive a control signal that has a first state and a second state,

a portion of incident radiation having a first polarization state that is reflected by the element is different when the control signal is in the first and second states, and

a portion of incident radiation having a second polarization state that is reflected by the element is substantially the same when the control signal is in the first and second states.

17. A device manufacturing method, comprising:

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

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 that is plane polarized in an extraordinary axis,

wherein the middle dielectric layer of each element is configured to receive a respective control signal that has a first state and a second state,

wherein a portion of incident radiation having a first polarization state that is reflected by each element when the respective control signal is in the first and second states is different, and

wherein a portion of incident radiation having a second polarization state that is reflected by each element is substantially the same when the respective control signal is in the first and second states; and

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

18. The method of claim 17, wherein the patterning comprises applying the respective control signal to each of the elements to selectively switch the element between a first state and a second state based on whether the applied respective control signal is in first state or in the second state.

19. The method of claim 18, wherein:

during the first state there is a first difference value in refractive index for the first 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 first polarization state.