Optical isolation module

Patent metadata

Field	Value
Publication number	US-9832855-B2
Application number	US-201514970402-A
Country	US
Kind code	B2
Filing date	Dec 15, 2015
Priority date	Oct 1, 2015
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

An optical source for a photolithography tool includes a source configured to emit a first beam of light and a second beam of light, the first beam of light having a first wavelength, and the second beam of light having a second wavelength, the first and second wavelengths being different; an amplifier configured to amplify the first beam of light and the second beam of light to produce, respectively, a first amplified light beam and a second amplified light beam; and an optical isolator between the source and the amplifier, the optical isolator including: a plurality of dichroic optical elements, and an optical modulator between two of the dichroic optical elements.

First claim

What is claimed is:

1. An extreme ultraviolet (EUV) optical source comprising:
a light-generation module comprising a first optical source configured to emit a first beam of light, and a second optical source configured to emit a second beam of light, the first beam of light having a first wavelength, and the second beam of light having a second wavelength, the first and second wavelengths being different;
an optical amplifier comprising a gain medium, the gain medium of the optical amplifier configured to amplify the first beam of light and the second beam of light to produce, respectively, a first amplified light beam and a second amplified light beam, wherein the first amplified light beam has an energy sufficient to deform target material in a target material droplet into a modified target, the modified target comprising target material in a geometric distribution that is different than a distribution of the target material in the target material droplet, the target material comprising material that emits EUV light when in a plasma state, and the second amplified light beam has an energy sufficient to convert at least some of the target material in the modified target to the plasma that emits EUV light; and
an optical isolator between the light-generation module and the optical amplifier, the optical isolator comprising:
a plurality of dichroic optical elements, the plurality of dichroic optical elements comprising a first dichroic optical element positioned to receive the first light beam and the second light beam from the light-generation module, and a second dichroic optical element positioned to direct the first light beam and the second light beam toward the optical amplifier,
a plurality of optical elements on a first beam path between the first dichroic optical element and the second dichroic optical element, the optical elements positioned to interact with light reflected from one or more of the first dichroic optical element and the second dichroic optical element, and
an optical modulator on the first beam path between the first dichroic optical element and the second dichroic optical element.

2. The optical source of claim 1 , wherein the optical modulator comprises an acousto-optic modulator.

3. The optical source of claim 2 , wherein
the acousto-optic modulator is configured to receive a trigger signal, and
the acousto-optic modulator deflects received light from the first beam path in response to receiving the trigger signal, and otherwise transmits received light onto the first beam path.

4. The optical source of claim 1 , wherein the first beam of light is a pulsed beam of light, and the second beam of light is a pulsed beam of light.

5. The optical source of claim 4 , wherein an energy of the first amplified light beam is less than an energy of the second amplified light beam.

6. The optical source of claim 1 , wherein the optical isolator further comprises a second optical modulator between the light-generation module and the optical amplifier.

7. The optical source of claim 6 , wherein the second optical modulator is between the first and second dichroic optical elements, and the second optical modulator is on a second beam path, the second beam path being different than the first beam path.

8. The optical source of claim 1 , wherein the light-generation module comprises a plurality of different kinds of lasers, the first light beam being produced by one of the types of lasers, and the second light beam being produced by another one of the types of lasers.

9. The optical source of claim 8 , wherein the optical amplifier is an optical amplifier system comprising a first optical amplifier and a second optical amplifier, the first optical amplifier configured to amplify the first light beam and the second optical amplifier configured to amplify the second light beam.

10. The optical source of claim 1 , wherein the light-generation module further comprises one or more pre-amplifiers, and an optical beam combiner, the optical beam combiner comprising one or more optical elements positioned to interact with one or more of the first and second light beams and the optical beam combiner being configured to direct the first light beam and the second light beam toward the first dichroic optical element of the optical isolator.

11. The optical source of claim 1 , wherein
the plurality of optical elements of the optical isolator comprises a plurality of reflective optical elements, and
the plurality of reflective optical elements, the first dichroic optical element, and the second dichroic optical element define the first beam path.

12. The optical source of claim 11 , wherein the optical modulator comprises an acousto-optic modulator.

13. The optical source of claim 12 , wherein the optical isolator comprises more than one acousto-optic modulator.

14. The optical source of claim 13 , wherein a first acousto-optic modulator is on the first beam path, and a second acousto-optic modulator is on a second beam path between the first and second dichroic optical elements, the first and second beam paths being spatially distinct paths in the optical isolator.

15. The optical source of claim 14 , wherein the first dichroic optical element is configured to direct the first beam of light onto the first beam path and the second beam of light onto the second beam path.

16. The optical source of claim 15 , wherein the second dichroic optical element is configured to direct the first beam of light onto a primary beam path and to direct the second beam of light onto the primary beam path.

17. The optical source of claim 16 , wherein the second dichroic optical element is configured to direct a reflection of the first beam of light onto the first beam path and to direct a reflection of the second beam of light onto the second beam path.

18. The optical source of claim 16 , wherein to direct the first beam of light onto the primary beam path, the second dichroic optical element transmits the first beam of light onto the primary beam path.

19. The optical source of claim 12 , wherein the plurality of optical elements of the optical isolator further comprises a first optical arrangement on the first beam path, wherein the first optical arrangement is between the first dichroic optical element and the acousto-optic modulator, and the first optical arrangement is configured to reduce a beam diameter of the first beam of light.

20. The optical source of claim 19 , wherein the plurality of optical elements of the optical isolator further comprises a second optical arrangement on the first beam path, wherein the second optical arrangement is between the second dichroic optical element and the acousto-optic modulator, and the second optical arrangement is configured to enlarge the beam diameter of the first beam of light.

21. The optical source of claim 19 , further comprising a polarization-based optical isolator between the optical isolator and the optical amplifier.

22. The optical source of claim 1 , wherein the optical modulator comprises one or more of an acousto-optic modulator, an electro-optic modulator, and a Faraday rotator.

23. The optical source of claim 1 , wherein the optical modulator comprises an acousto-optic modulator, the acousto-optic modulator being associated with a first state and a second state, the acousto-optic modulator deflecting incident light from an initial beam path in the first state and transmitting incident light onto the initial beam pa

Assignees

• Asml Netherlands Bv

Inventors

• Tao Yezheng
• Brown Daniel John William
• Schafgans Alexander Anthony
• Das Palash Parijat

Classifications

• H01S3/2391

  emitting at different wavelengths · CPC title

• H01S3/2308

  Amplifier arrangements, e.g. MOPA · CPC title

• H01S3/2232

  Carbon dioxide (CO2) or monoxide [CO] · CPC title

• H01S3/0064

  Anti-reflection devices, e.g. optical isolaters (absorbing layers for marking or protecting purposes in laser working B23K26/50; magneto-optical non-reciprocal devices G02F1/093, G02F1/0955) · CPC title

• H05G2/0035

  the material containing metals as principal radiation-generating components · CPC title