Lithographic apparatus and device manufacturing method utilizing a MEMS mirror with large deflection using a non-linear spring arrangement

• US 20070236675A1
• Filed: 04/06/2006
• Published: 10/11/2007
• Est. Priority Date: 04/06/2006
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Venema, Willem
• Granted Patent: US 7,528,933 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• 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 for a lithographic apparatus comprise reflectors that can be actuated by an actuator and are biased to return to a given position by a force that varies non-linearly with the displacement of the reflector from that position.

Claims

1. An array of individually controllable elements, adapted to modulate a beam of radiation, the individually controllable elements comprising:

a reflector movably mounted to each individually controllable element in the array of individually controllable elements, such that the reflector is biased away from a first position towards a second position; and

an actuator capable of exerting a force on the reflector in order to move the reflector away from the second position towards the first position;

wherein a force exerted on the reflector in order to move the reflector away from the first position towards the second position is non-linearly related to a displacement of the reflector from the second position.

2. The array of individually controllable elements of claim 1, wherein the individually controllable elements comprise:

a hinge coupled to the substrate to support the reflector, the hinge being arranged to deform when the actuator exerts a force on the reflector, such that the reflector rotates relative to the array away from the second position towards the first position; and

wherein the deformation of the hinge provides at least a component of the force exerted on the reflector in order to bias the reflector away from the first position towards the second position.

3. The array of individually controllable elements of claim 2, wherein:

the individually controllable elements comprise a restrictor that exerts an additional force on the reflector in order to bias the reflector away from the first position towards the second position; and

the additional force is non-linearly related to the displacement of the reflector from the second position.

4. The array of individually controllable elements of claim 3, wherein:

the restrictor comprises a resilient element that extends between a part of the array of individually controllable elements that is fixed within the array of individually controllable elements and a part of the reflector; and

as the reflector rotates away from the second position towards the first position, the resilient element is stretched and, consequently, exerts the additional force on the reflector.

5. The array of individually controllable elements of claim 4, wherein:

the resilient element is configured such that as the reflector rotates, the angle at which the resilient element exerts the additional force on the reflector, relative to the plane of the reflector, changes.

6. The array of individually controllable elements of claim 2, wherein the individually controllable elements comprise:

an interceptor that, for a first portion of the displacement of the reflector from the first position towards the second position, does not interfere with the reflector and, for at least a second portion of the displacement of the reflector from the first position towards the second position, exerts an additional force on the reflector.

7. The array of individually controllable elements of claim 6, wherein the interceptor comprises:

a resilient member extending from the reflector that, after the first portion of the displacement of the reflector from the first position towards the second position, intercepts a part of the array that is fixed within the array; and

wherein the resilient member is configured such that as the reflector is displaced further, the resilient member is deformed.

8. The array of individually controllable elements of claim 6, wherein the interceptor comprises:

a resilient member that extends from a part of the array of individually controllable elements that is fixed within the array of individually controllable elements, which, after the first portion of the displacement of the reflector from the first position towards the second position, intercepts the reflector; and

the resilient member is configured such that as the reflector is displaced further, the resilient member is deformed.

9. The array of individually controllable elements of claim 6, further comprising:

at least a second interceptor that, for the first and second portions of the displacement of the reflector from the first position to the second position, does not interfere with the reflector and, for at least a third portion of the displacement of the reflector from the first position towards the second position, exerts an additional force on the reflector.

10. The array of individually controllable elements of claim 2, wherein the hinge includes a constraint that is configured such that, as the reflector is displaced from the second position to the first position, a stiffness of the hinge increases.

11. The array of individually controllable elements of claim 10, wherein the constraint increases the stiffness of the hinge by restricting the portion of the hinge that deforms a subsequent displacement of the reflector.

12. The array of individually controllable elements of claim 11, wherein:

the hinge is mounted to a support fixed within the array of individually controllable elements;

a first part of the hinge is fixed to the support and at least a second part of the hinge is configured such that the hinge deforms for a given rotation of the reflector relative to the array of individually controllable elements until the second part of the hinge is in contact with the support, whereupon the hinge deforms no further.

13. The array of individually controllable elements of claim 12, wherein the individually controllable element further comprises:

a restraint that is mounted to the hinge on an opposite side of the hinge to the support; and

wherein the restraint is configured such that a third part of the hinge deforms for a given rotation of the reflector relative to the array until the third part of the hinge is in contact with the restraint, whereupon the hinge deforms no further.

14. A lithographic apparatus, comprising an array of individually controllable elements that is configured to modulate a beam of radiation before it is projected onto a substrate, wherein the individually controllable elements comprise:

a reflector that is movably mounted to the array of individually controllable elements, such that the reflector is biased away from a first position towards a second position; and

an actuator that is capable of exerting a force on the reflector in order to bias the reflector away from the second position towards the first position;

wherein a force exerted on the reflector in order to bias the reflector away from the first position towards the second position is non-linearly related to a displacement of the reflector from the second position.

15. A device manufacturing method, comprising:

modulating a beam of radiation using an array of individually controllable elements, the modulating being performed through,

moveably mounting a reflector to the array of individually controllable elements, such that the reflector is biased away from a first position towards a second position,

exerting a force on the reflector using an actuator in order to bias the reflector away from the second position towards the first position, the exerted force being non-linearly related to a displacement of the reflector from the second position, and

sending control signals to the actuators of the individually controllable elements in order to set the reflectors to desired displacements; and

projecting the modulated beam of radiation onto a substrate.

16. An integrated circuit device manufactured according to the method of claim 15.

17. A flat panel display manufactured according to the method of claim 15.