Spatial light modulator, method of spatially modulating a radiation beam, lithographic apparatus and device manufacturing method

• US 20050007671A1
• Filed: 06/16/2004
• Published: 01/13/2005
• Est. Priority Date: 06/20/2003
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Onvlee, Johannes
• Granted Patent: US 7,630,118 B2
• Time in Patent Office: Days
• US Class Current: 359/626
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

Each pixel of a spatial light modulator comprises a movable mirror, a light sensitive element and control circuitry to drive an actuator set the movable mirror to a state determined by a signal received by the light sensitive element.

Claims

1. A spatial light modulator comprising an array of pixels disposed on a support, each pixel comprising:

a movable mirror that is movable between at least two positions in which an incident radiation beam of a first wavelength is reflected into, respectively, different return paths;

an actuator arranged to move said movable mirror between the at least two positions;

a light sensitive element that receives a programming beam of a second wavelength and generates a control signal in response thereto; and

controller that controls said actuator to set said movable mirror to a selected position according to the control signal generated by said light sensitive element.

2. The spatial light modulator of claim 1, wherein said movable mirror and said light sensitive element are disposed on a same side of said support.

3. The spatial light modulator of claim 2, wherein said movable mirror is disposed over said light sensitive element and said light sensitive element is substantially transparent to radiation of said second wavelength.

4. The spatial light modulator of claim 2, wherein said support is substantially transparent to radiation of said second wavelength.

5. The spatial light modulator of claim 1, wherein said light moveable mirror and said light sensitive element are disposed on opposite sides of said support.

6. The spatial light modulator of claim 1, further comprising:

a beam scanner that scans at least one programming beam across said array of pixels.

7. The spatial light modulator of claim 6, wherein:

said array of pixels is a two dimensional array having a plurality of rows and a plurality of columns; and

said beam scanner scans a plurality of programming beams equal in number to said plurality of columns along respective ones of said columns.

8. The spatial light modulator of claim 7, wherein said beam scanner comprises:

a prism having reflective surfaces and disposed with its axis perpendicular to said columns; and

a device that rotates said prism about said axis.

9. The spatial light modulator of claim 7, wherein said beam scanner comprises:

a plurality of independently controllable light sources corresponding in number to said plurality of beams.

10. The spatial light modulator of claim 1, wherein:

said light sensitive element comprises a photodiode; and

said actuator comprises a capacitor connected to said photodiode, so as to be charged by current generated in said photodiode by said programming beam when incident thereon.

11. The spatial light modulator of claim 10, wherein said controller further comprises:

an amplifier for amplifying the current generated in said photodiode.

12. A method of spatially modulating a radiation beam according to a pattern using a spatial light modulator comprising an array of pixels disposed on a support, comprising:

(a) modulating at least one programming beam according to the pattern;

(b) scanning the at least one programming beam across the array of pixels in synchronism with step (a), so as to irradiate a light sensitive element in the array of pixels, thereby setting a state of a moveable mirror corresponding to the light sensitive element; and

(c) directing the radiation beam onto the spatial light modulator so that the radiation beam is modulated according to the states of the movable mirror.

13. The method according to claim 12, further comprising:

pulsing the radiation beam and performing steps (a) and (b) between pulses of the radiation beam.

14. A lithographic projection apparatus, comprising:

an illumination system for providing a projection beam of radiation;

a programmable patterning device including a spatial light modulator having an array of pixels disposed on a support, the programming patterning device patterning the projection beam;

a projection system for projecting the patterned beam onto a target portion of a support, wherein each pixel comprises;

a movable mirror that is movable between at least two positions in which an incident radiation beam of a first wavelength is reflected into, respectively, different return paths;

an actuator arranged to move said movable mirror between the at least two positions;

a light sensitive element that receives a programming beam of a second wavelength and generates a control signal in response thereto; and

controller that controls said actuator to set said movable mirror to a selected position according to the control signal generated by said light sensitive element.

15. The lithographic projection apparatus of claim 14, wherein said movable mirror and said light sensitive element are disposed on a same side of said support.

16. The spatial light modulator of claim 15, wherein said movable mirror is disposed over said light sensitive element and said light sensitive element is substantially transparent to radiation of said second wavelength.

17. The spatial light modulator of claim 15, wherein said support is substantially transparent to radiation of said second wavelength.

18. The lithographic projection apparatus of claim 14, wherein said light moveable mirror and said light sensitive element are disposed on opposite sides of said support.

19. The lithographic projection apparatus of claim 14, further comprising:

a beam scanner that scans at least one programming beam across said array of pixels.

20. The spatial light modulator of claim 19, wherein:

said array of pixels is a two dimensional array having a plurality of rows and a plurality of columns; and

said beam scanner scans a plurality of programming beams equal in number to said plurality of columns along respective ones of said columns.

21. The spatial light modulator of claim 19, wherein said beam scanner comprises:

a prism having reflective surfaces and disposed with its axis perpendicular to said columns;

a device that rotates said prism about said axis.

22. The spatial light modulator of claim 19, wherein said beam scanner comprises:

a plurality of independently controllable light sources corresponding in number to said plurality of beams.

23. The lithographic projection apparatus of claim 14, wherein:

said light sensitive element comprises a photodiode; and

said actuator comprises a capacitor connected to said photodiode, so as to be charged by current generated in said photodiode by said programming beam when incident thereon.

24. The lithographic projection apparatus of claim 23, wherein said control circuitry further comprises:

an amplifier for amplifying the current generated in said photodiode.