Illumination subsystems of a metrology system, metrology systems, and methods for illuminating a specimen for metrology measurements
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G01N-021/55
G01N-021/95
G01N-021/47
출원번호
US-0061936
(2009-09-29)
등록번호
US-9080990
(2015-07-14)
국제출원번호
PCT/US2009/058819
(2009-09-29)
§371/§102 date
20110730
(20110730)
국제공개번호
WO2010/037106
(2010-04-01)
발명자
/ 주소
Chuang, Yung-Ho (Alex)
Levinski, Vladimir
Liu, Xuefeng
출원인 / 주소
KLA-Tencor Corp.
대리인 / 주소
Mewherter, Ann Marie
인용정보
피인용 횟수 :
0인용 특허 :
10
초록▼
Illumination subsystems of a metrology system, metrology systems, and methods for illuminating a specimen for metrology measurements are provided. One illumination subsystem includes a light source configured to generate coherent pulses of light and a dispersive element positioned in the path of the
Illumination subsystems of a metrology system, metrology systems, and methods for illuminating a specimen for metrology measurements are provided. One illumination subsystem includes a light source configured to generate coherent pulses of light and a dispersive element positioned in the path of the coherent pulses of light, which is configured to reduce coherence of the pulses of light by mixing spatial and temporal characteristics of light distribution in the pulses of light. The illumination subsystem also includes an electro-optic modulator positioned in the path of the pulses of light exiting the dispersive element and which is configured to reduce the coherence of the pulses of light by temporally modulating the light distribution in the pulses of light. The illumination subsystem is configured to direct the pulses of light from the electro-optic modulator to a specimen positioned in the metrology system.
대표청구항▼
1. An illumination subsystem of a metrology system, comprising: a light source configured to generate coherent pulses of light;a dispersive element positioned in the path of the coherent pulses of light, wherein the dispersive element is configured to reduce coherence of the pulses of light by mixin
1. An illumination subsystem of a metrology system, comprising: a light source configured to generate coherent pulses of light;a dispersive element positioned in the path of the coherent pulses of light, wherein the dispersive element is configured to reduce coherence of the pulses of light by mixing spatial and temporal characteristics of light distribution in the pulses of light; andan electro-optic modulator positioned in the path of the pulses of light exiting the dispersive element, wherein the electro-optic modulator is configured to reduce the coherence of the pulses of light by temporally modulating the light distribution in the pulses of light, wherein the electro-optic modulator is further configured to have an amplitude that provides about 103 aperiodic samples on each period thereby providing a de-coherence time of about 10−13 seconds, and wherein the illumination subsystem is configured to direct the pulses of light from the electro-optic modulator to a specimen positioned in the metrology system. 2. The illumination subsystem of claim 1, wherein a duration of the pulses of light generated by the light source is less than 10 nanoseconds. 3. The illumination subsystem of claim 1, wherein the light source is a laser light source. 4. The illumination subsystem of claim 1, wherein the dispersive element is a prism. 5. The illumination subsystem of claim 1, wherein the dispersive element is a diffraction grating. 6. The illumination subsystem of claim 1, further comprising an additional dispersive element positioned in the path of the pulses of light exiting the electro-optic modulator, wherein the additional dispersive element is configured to reduce the coherence of the pulses of light by mixing the spatial and temporal characteristics of the light distribution in the pulses of light. 7. The illumination subsystem of claim 6, wherein the illumination subsystem is further configured to direct the pulses of light from the additional dispersive element to the specimen. 8. The illumination subsystem of claim 6, further comprising refractive optics positioned between the electro-optic modulator and the additional dispersive element. 9. The illumination subsystem of claim 6, further comprising a reflective element positioned in the path of the pulses of light exiting the additional dispersive element, wherein the reflective element is configured to direct the pulses of light exiting the additional dispersive element back through the additional dispersive element, the electro-optic modulator, and the dispersive element, and wherein the illumination subsystem is further configured to direct the pulses of light from the dispersive element to the specimen. 10. The illumination subsystem of claim 1, further comprising a reflective element positioned in the path of the pulses of light exiting the electro-optic modulator, wherein the reflective element is configured to direct the pulses of light exiting the electro-optic modulator back through the electro-optic modulator and the dispersive element, and wherein the illumination subsystem is further configured to direct the pulses of light from the dispersive element to the specimen. 11. The illumination subsystem of claim 1, wherein the electro-optic modulator is further configured to change the temporal modulation of the light distribution in the pulses of light at tenth picosecond time intervals. 12. The illumination subsystem of claim 1, wherein the electro-optic modulator is further configured to operate in a traveling wave operation mode. 13. The illumination subsystem of claim 1, wherein the pulses of light generated by the light source comprise light having different wavelengths, and wherein the illumination subsystem is further configured to direct the light having the different wavelengths along different optical paths through the illumination subsystem. 14. The illumination subsystem of claim 1, wherein the illumination subsystem is not configured to reduce the coherence of the pulses of light using mechanical devices. 15. The illumination subsystem of claim 1, wherein the metrology system is configured to cause continuous relative movement between the specimen and a detection subsystem of the metrology system during measurements of the specimen performed by the metrology system. 16. A metrology system, comprising: an illumination subsystem, wherein the illumination subsystem comprises: a light source configured to generate coherent pulses of light;a dispersive element positioned in the path of the coherent pulses of light, wherein the dispersive element is configured to reduce coherence of the pulses of light by mixing spatial and temporal characteristics of light distribution in the pulses of light; andan electro-optic modulator positioned in the path of the pulses of light exiting the dispersive element, wherein the electro-optic modulator is configured to reduce the coherence of the pulses of light by temporally modulating the light distribution in the pulses of light, wherein the electro-optic modulator is further configured to have an amplitude that provides about 103 aperiodic samples on each period thereby providing a de-coherence time of about 10−13 seconds, and wherein the illumination subsystem is configured to direct the pulses of light from the electro-optic modulator to a specimen positioned in the metrology system;a detection subsystem configured to detect light from the specimen and to generate output responsive to the detected light; anda processor configured to determine one Or more characteristics of the specimen using the output. 17. The metrology system of claim 16, wherein the metrology system is further configured to cause continuous relative movement between the specimen and the detection subsystem during measurements of the specimen performed by the metrology system. 18. A method for illuminating a specimen for metrology measurements, comprising: generating coherent pulses of light;reducing coherence of the pulses of light by mixing spatial and temporal characteristics of light distribution in the pulses of light;reducing the coherence of the pulses of light by temporally modulating the light distribution in the pulses of light with an electro-optic modulator, wherein the electro-optic modulator is configured to have an amplitude that provides about 103 aperiodic samples on each period thereby providing a de-coherence time of about 10−13 seconds; andsubsequent to the reducing steps, directing the pulses of light to the specimen positioned in a metrology system. 19. The method of claim 18, wherein the reducing steps are performed without using mechanical devices. 20. An illumination subsystem, comprising: alight source configured to generate coherent pulses of light;a dispersive element positioned in the path of the coherent pulses of light, wherein the dispersive element is configured to reduce coherence of the pulses of light by mixing spatial and temporal characteristics of light distribution in the pulses of light; andan electro-optic modulator positioned in the path of the pulses of light exiting the dispersive element, wherein the electro-optic modulator is configured to reduce the coherence of the pulses of light by temporally modulating the light distribution in the pulses of light, wherein the electro-optic modulator is further configured an amplitude that provides about 103 aperiodic samples on each period thereby providing a de-coherence time of about 10−13 seconds, and wherein the illumination subsystem is configured to direct the pulses of light from the electro-optic modulator to a specimen. 21. The illumination subsystem of claim 20, wherein the light source is a pulsed laser light source, and wherein the illumination subsystem is included in a system configured to perform output acquisition for the specimen by image grabbing. 22. The illumination subsystem of claim 20, wherein the light source is a pulsed laser light source, and wherein the illumination subsystem is included in a system configured to cause continuous relative movement between the specimen and the illumination subsystem while measurements are being performed on the specimen. 23. The illumination subsystem of claim 20, wherein the light source is a pulsed laser light source, and wherein the illumination subsystem is included in a system configured to move the specimen along a serpentine path continuously with respect to the illumination subsystem while measurements are being performed on the specimen. 24. The illumination subsystem of claim 20, wherein the electro-optic modulator has a modulation frequency of about 1 GHz to about 10 GHz. 25. The illumination subsystem of claim 20, wherein the electro-optic modulator is further configured to operate in a traveling wave operation mode, and wherein the electro-optic modulator has a modulation frequency of about 1 GHz to about 10 GHz.
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