System, apparatus and method for maskless lithography that emulates binary, attenuating phase-shift and alternating phase-shift masks

• US 20060132887A1
• Filed: 12/22/2004
• Published: 06/22/2006
• Est. Priority Date: 12/22/2004
• Status: Active Grant

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Bleeker, Arno, Baba-Ali, Nabila
• Granted Patent: US 7,274,502 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• 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

A tilting mirror design for maskless lithography is proposed. In this mirror, the tilting portion occupies about 60% of the entire element area. The surrounding space is made 100% reflective and out-of-phase with respect to the tilting portion. The ratio between the tilting portion of the mirror and the out-of-phase portion is optimized in order to result in equal positive and negative maximum amplitudes over a complete range of tilt angles.

Claims

1. A system, comprising:

an illumination system that supplies a beam of radiation;

an array of individually controllable elements that patterns the beam, wherein each of the elements in the array of individually controllable elements comprises a tilting portion and a non-tilting portion; and

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

2. The system of claim 1, wherein the system is at least one of a maskless lithography system, a projector, and a projection system.

3. The system of claim 1, wherein:

each of the non-tilting portions has a first reflective surface that is bounded by an inner periphery and outer periphery;

each of the tilting portions has a second reflective surface that is bounded by a periphery; and

each of the respective tilting portions is oriented with respect to the respective non-tilting portions so that the periphery of the respective tilting portions extends beyond the inner periphery of the respective non-tilting portions, but not beyond the outer periphery of the respective non-tilting portions.

4. The system of claim 3, wherein the first reflective surfaces of the respective non-tilting portions are sized to a predetermined percentage of an area of the respective elements so as to produce substantially equal positive and negative maximum amplitudes at the target portion over a complete range of tilt angles.

5. The system of claim 3, wherein the respective tilting portions tilt about a central axis shared by the respective tilting portions and respective non-tilting portions.

6. The system of claim 1, wherein each of the respective tilting portions can be tilted through a complete range of tilt angles to produce substantially equal positive and negative maximum amplitudes at the target portion over the complete range of tilt angles.

7. The system of claim 1, wherein each respective tilting portion one of tilts through a positive range of tilt angles and a negative range of tilt angles, wherein a zero tilt angle is such that a first reflective surface of the non-tilting portion is substantially parallel to a second reflective surface of the tilting portion.

8. The system of claim 7, wherein at the zero tilt angle radiation reflected from the non-tilting portion is out-of-phase with radiation reflected from the tilting portion.

9. The system of claim 1, wherein each one of the respective tilting portions is tilted to a respective tilt angle so that the array of individually controllable elements emulates at least one of a binary reticle, an attenuating phase shift reticle, and an alternating phase shift reticle.

10. The system of claim 1, wherein the object is at least one of a substrate and a display device.

11. The system of claim 10, wherein the substrate comprises at least one of glass, a polymer, and a semiconductor material.

12. A patterning device, comprising:

an array of first reflective portions, each of the first reflective portions having a first area;

an array of second reflective portions, each of the second reflective portions having a second area, wherein each of the second reflective portions can tilt through a predetermined range of tilt angles about an axis shared by the first reflective portions and second reflective portions, respectively; and

an array of controllers coupled to one of respective ones of the second reflective portions and subsets of the second reflective portions, each of the controllers controlling the tilt angle of one of the respective ones of the second reflective portions and subsets of the second reflective portions.

13. The patterning device of claim 12, wherein:

each of the first areas of the first reflective portions is bounded by an inner and outer periphery;

each of the second areas of the second reflective portions is bounded by a periphery; and

each of the respective second reflective portions is oriented with respect to the respective first reflective portions such that the periphery of the respective second reflective portion extends beyond the inner periphery of the respective first reflective portions, but not beyond the outer periphery of the respective first reflective portions.

14. The patterning device of claim 12, wherein a ratio of the area of the respective second reflective portions to the area of the respective first reflective portions produces substantially equal positive and negative maximum amplitudes of reflected light over a complete range of tilt angles.

15. The patterning device of claim 12, wherein each respective second reflective portion one of tilts through a positive range of tilt angles and a negative range of tilt angles, wherein a zero tilt angle is such that a second reflective surface of the respective second reflective portions is substantially parallel to a first reflective surface of the respective first reflective portions.

16. The patterning device of claim 12, wherein the axis shared by the respective first and second reflective portions is a central longitudinal axis that is substantially parallel to a reflective surface of the respective first reflective portions.

17. The patterning device of claim 13, wherein the axis shared by the respective first and second reflective portions is substantially parallel to a substrate that supports the array of first reflective portions.

18. The patterning device of claim 12, wherein if the respective tilt angle of the respective second reflective portion is equal to a default value, a first reflective surface of the respective first reflective portion is substantially parallel to a second reflective surface of the respective second reflective portion.

19. The patterning device of claim 12, wherein:

the first reflective portion is mounted on a substrate;

the second reflective portion is supported above the substrate such that a height measured from a first reflective surface of the first reflective portion to a second reflective surface of the second reflective portion is approximately λ

/4 when the second reflective portion is substantially parallel to the substrate, wherein λ

is a wavelength of a beam of radiation of an illumination system.

20. The patterning device of claim 12, wherein:

the first reflective portion is mounted on a substrate;

the second reflective portion is supported above the substrate such that a first reflective surface of the first reflective portion is above a second reflective surface of the second reflective portion and a height measured from the first reflective surface of the first reflective portion to the second reflective surface of the second reflective portion is approximately λ

/4when the second reflective surface is substantially parallel to the substrate, wherein λ

is a wavelength of a beam of radiation of an illumination system.

21. The patterning device of claim 12, wherein each of the respective second reflective portions is tilted to a respective predetermined tilt angle so that the patterning device emulates at least one of a binary reticle, an attenuating phase shift reticle, and an alternating phase shift reticle.

22. A method, comprising:

patterning a beam of radiation using an array of individually controllable elements, each of the individual elements in the array having a first reflective region that tilts and a second reflective region; and

projecting the patterned beam onto a target portion of an object, wherein each element produces substantially equal positive and negative maximum amplitudes of reflected light over a complete range of tilt angles.

23. The method of claim 22, further comprising emulating at least one of a binary reticle, an attenuating phase shift reticle, and an alternating phase shift reticle using the array of individually controllable elements.

24. The method of claim 22, wherein the projecting step comprises projecting the patterned beam onto a target portion of at least one of a substrate, a semiconductor substrate, a glass substrate, a polymer substrate, and a display device.