Illumination Device for optimizing polarization in an illumination pupil

• US 20130148359A1
• Filed: 10/26/2012
• Published: 06/13/2013
• Est. Priority Date: 10/28/2011
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Smith, Daniel Gene, Sogard, Michael
• Granted Patent: US 9,732,934 B2
• Time in Patent Office: Days
• US Class Current: 362/283
• CPC Class Codes: F21V 7/0033 with successive reflections from one reflector to the next or following
• CPC Class Codes: G03F 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/70566 Polarisation control

Abstract

A new and useful illumination device, e.g. for a lithographic optical imaging system, is provided, and comprises a mirror array located between a radiation source and an illumination pupil. Each mirror element of the mirror array is individually steerable (controllable), and the polarization state of light from each mirror element of the mirror array can be selectively controlled, so that the illumination pupil can be filled with a distribution of light that is selectively controlled.

Claims

1. An illumination device comprising a mirror array including an array of mirror elements located between a radiation source and an illumination pupil, and each mirror element of the mirror array is individually steerable (controllable), and where the polarization state of light from each mirror element of the micromirror array can be selectively controlled, so that the illumination pupil can be filled with a distribution of light that is selectively controlled.

2. The illumination device of claim 1, wherein a retarder coating is applied to selected mirror elements of the mirror array to control the polarization state of light reflected from the mirror array.

3. The illumination device of claim 2, wherein a wave plate is provided before the mirror array to set the incident polarization, and thereby making the polarization of the mirror array switchable.

4. The illumination device of claim 1, further including an additional mirror array between the mirror array and the illumination pupil, where the additional mirror array receives radiation from the mirror array and directs the radiation to the illumination pupil.

5. The illumination device of claim 4, wherein the additional mirror array is conjugate to the mirror array.

6. The illumination device of claim 5, wherein an intervening relay system is located between the mirror array and the additional mirror array.

7. The illumination device of claim 5, wherein an array of polarization filters (or retarders) are located between the mirror array and the additional micromirror array.

8. The illumination device of claim 5, wherein a wedge of optically active material is located between the mirror array and the additional mirror array, such that the orientation of linear polarization leaving the wedge depends continuously on the position of the beam in the wedge.

9. An illumination device comprising:

a mirror array including an array of minor elements located between a radiation source and an illumination pupil,

wherein each mirror element of the mirror array is individually steerable, and has a coating on the reflective surface of the minor element,

wherein the coating has a retardance that depends on an angle of incidence,

the device further comprising;

a controller connected with the minor array that controls posture of each mirror element of the mirror array so as to fill the illumination pupil with a desired polarization distribution.

10. An illumination device comprising:

a first mirror array including an array of mirror elements located between a radiation source and an illumination pupil;

a second minor array including an array of mirror elements located between the first mirror array and the illumination pupil; and

a relay system between the first and second minor arrays,

wherein each mirror element of the first and second mirror arrays is individually steerable,

the device further comprising;

a controller connected with the mirror array that controls posture of each mirror element of the mirror array so as to fill the illumination pupil with a desired polarization distribution.

11. The illumination device of claim 10, wherein each mirror element of the mirror array has a coating on the reflective surface of the mirror element, and wherein the coating has a retardance that depends on an angle of incidence.

12. The illumination device of claim 10, further comprising a polarization member disposed in the relay system.

13. The illuminagtion device of claim 12, the polarization member comprising an array of polarization element.