IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
UP-0169423
(2005-06-29)
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등록번호 |
US-7616312
(2009-11-23)
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발명자
/ 주소 |
- Kasapi, Steven
- Wilsher, Kenneth
- Woods, Gary
- Lo, William
- Ispasoiu, Radu
- Nataraj, Nagamani
- Boiadjieva, Nina
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
6 인용 특허 :
49 |
초록
▼
An apparatus and method for laser probing of a DUT at very high temporal resolution is disclosed. The system includes a CW laser source, a beam optics designed to point two orthogonally polarized beams at the same location on the DUT, optical detectors for detecting the reflected beams, collection e
An apparatus and method for laser probing of a DUT at very high temporal resolution is disclosed. The system includes a CW laser source, a beam optics designed to point two orthogonally polarized beams at the same location on the DUT, optical detectors for detecting the reflected beams, collection electronics, and an oscilloscope. The beam optics defines a common-path polarization differential probing (PDP) optics. The common-path PDP optics divides the laser beam into two beams of orthogonal polarization. Due to the intrinsic asymmetry of a CMOS transistor, the interaction of the beams with the DUT result in different phase modulation in each beam. This difference can be investigated to study the response of the DUT to the stimulus signal.
대표청구항
▼
What is claimed is: 1. A system for testing an integrated circuit microchip including a plurality of devices using laser probing, comprising: a laser source providing a laser beam; a beam optics wherein the beam optics comprises a Faraday rotator that rotates a polarization direction of an incident
What is claimed is: 1. A system for testing an integrated circuit microchip including a plurality of devices using laser probing, comprising: a laser source providing a laser beam; a beam optics wherein the beam optics comprises a Faraday rotator that rotates a polarization direction of an incident beam to define a rotated beam, the rotated beam comprising two mutually orthogonally polarized components that are aligned respectively with a length direction and a width direction of a device located at a selected spot, and a variable retarder having a fast axis and a slow axis, the fast and slow axes aligned with respective ones of the two mutually orthogonally polarized components, the variable retarder phase shifting one beam component relative to the other beam component, and an objective lens to direct the beam to the selected spot; a first photodetector receiving reflected laser light that is reflected from said microchip and providing an electrical signal; collection electronics receiving the electrical signal from said first photodetector and providing an output signal; and an analysis system receiving and analyzing said output signal. 2. The system of claim 1, wherein said laser source is a CW laser. 3. The system of claim 1, wherein said laser source is a pulsed laser. 4. The system of claim 1, further comprising a second photodetector, and wherein said first photodetector receives part of said reflected laser light and the second photodetector receives the remaining part of said reflected laser light. 5. The system of claim 1, wherein said beam optics further comprises a polarizing beam splitter positioned between said Faraday rotator and said variable retarder, wherein the polarizing beam splitter transmits the rotated beam. 6. The system of claim 5, further comprising a second photodetector, wherein said first photodetector receives part of said reflected laser light and the second photodetector receives the remaining part of said reflected laser light, and wherein said first photodetector and said second photodetector comprise a first and second avalanche photodiodes (APD). 7. The system of claim 6, wherein said collection electronics comprises a differential amplifier. 8. The system of claim 6, wherein said collection electronics comprises a balanced receiver. 9. The system of claim 6, wherein said analysis system comprises an oscilloscope. 10. The system of claim 6, wherein said analysis system comprises a spectrum analyzer. 11. The system of claim 6, wherein said laser source is a CW laser. 12. The system of claim 11, wherein said beam optics further comprises a first polarizing beam splitter positioned upstream of said Faraday rotator. 13. The system of claim 12, wherein said beam optics further comprises an objective lens. 14. The system of claim 13, wherein said beam optics further comprises a solid immersion lens in between the objective lens and the microchip. 15. The system of claim 13, wherein said beam optics comprises a beam pointing optics including a beam scanning mechanism. 16. The system of claim 15, wherein said beam pointing optics and said beam scanning mechanism comprise laser scanning microscope. 17. The system of claim 16, wherein said first and second APDs are coupled to a controllable variable power supply. 18. The system of claim 17, further comprising a first and second current monitors coupled to said first and second APDs, respectively. 19. The system of claim 18, further comprising a video amplifier coupled to at least one of said first and second APDs. 20. The system of claim 19, further comprising a signal amplifier system coupled to said first and second APDs and providing an amplified electrical signal corresponding to output signals of said first and second APDs. 21. The system of claim 6, further comprising a signal amplifier system coupled to said first and second avalanche photodiodes APDs and providing an amplified electrical signal corresponding to output signals of said first and second APDs. 22. The system of claim 21, wherein said signal amplifier system comprises a differential amplifier. 23. The system of claim 21, wherein said signal amplifier system comprises a first amplifier coupled to said first APD and a second amplifier coupled to said second APD. 24. The system of claim 12, further comprising: a monitoring photodetector; a second polarizing beam splitter positioned downstream of said laser light source between the first polarlizing beam splitter and the Faraday rotator, and deflecting part of said laser beam towards said monitoring photodetector; and, wherein the output of said monitoring photodetector is used to monitor the performance of said laser source. 25. The system of claim 24, further comprising a controller coupled to said variable retarder, wherein said controller varies the setting of said variable retarder to control the intensity of light received by the first and second photodetectors. 26. The system of claim 24, further comprising a variable power supply coupled to said first and second photodetectors, wherein varying the settings of said power supply controls the gain of said first and second photodetectors. 27. The system of claim 1, further comprising imaging optics, wherein said imaging optics establish a light path for specimen imaging and said beam optics establish a light path for specimen probing. 28. The system of claim 27, further comprising imaging light source providing imaging illumination through said imaging optics. 29. The system of claim 28, further comprising a switching element for switching between said beam optics and said imaging optics. 30. A method of probing an integrated circuit microchip, comprising: generating a laser beam; transferring the laser beam through a beam optics to condition the beam, the conditioned beam having two mutually orthogonally polarized components that traverse a common optical path and are aligned, respectively, with a length direction and a width direction of a device included in the microchip, and are phase shifted relative to one another; pointing the two mutually orthogonally polarized components at a common selected area on the microchip including the device; and collecting and analyzing reflected light that is reflected from the selected area. 31. The method of claim 30, further comprising dividing the reflected light into a first reflection and a second reflection. 32. The method of claim 31, wherein said collecting comprises directing the first reflection onto a first photodetector and directing the second reflection onto a second photodetector. 33. The method of claim 32, further comprising applying output signals of said first and second photodetectors to a balanced receiver and obtaining a differential signal therefrom. 34. The method of claim 33, further comprising applying the differential signal onto an oscilloscope. 35. The method of claim 32, further comprising applying a variable power to said first and second photodetectors, and varying the power so as to balance said first and second photodetectors. 36. The method of claim 30, wherein said generating a laser beam comprises generating a CW laser beam. 37. The method of claim 36, wherein said analyzing comprises scanning said CW Laser beam over an area of said microchip so as to obtain an image of said area. 38. The method of claim 37, further comprising varying the phase shifting so as to control image intensity when said area includes high and low reflectance parts. 39. The method of claim 37, wherein said collecting comprises directing the reflected light onto a first and a second photodetectors. 40. The method of claim 39, further comprising balancing the first and second photodetectors by applying a variable power supply to said first and second photodetectors and varying the power applied to said first and second photodetectors so as to balance said first and second photodetectors. 41. The method of claim 30, further comprising illuminating a selected area of said microchip through an imaging path and obtaining an image of said selected area. 42. The method of claim 41, wherein said collecting comprises directing the reflected light onto at least one probing photodetector, and said obtaining an image comprises directing the reflected light onto an imaging photodetector. 43. An optical system comprising: a laser source providing a laser beam; a polarizer polarizing said laser beam; a Faraday rotator rotating the laser beam, such that a first polarization vector of a first beam component and a second polarization vector of a second beam component of the beam are configured to be aligned, respectively, with a length direction and a width direction of a device; an optical retarder phase shifting the first beam component and second beam component relative to one another, wherein the optical retarder is positioned between the Faraday rotator and an objective lens directing said beams directly onto a selected spot including said device; wherein said polarizer, Faraday rotator, optical retarder and objective lens define a beam path, said beam path further comprising a first beam splitter receiving a reflected beam reflected from said device and directing part of said reflected beam out of said beam path; and a first photodetector receiving said reflected beam from the first beam splitter. 44. The optical system of claim 43, wherein said beam path further comprises a second beam splitter directing the remainder of said reflected beam out of said beam path, after reflection by said first beam splitter. 45. The optical system of claim 44, further comprising a second photodetector receiving said reflected beam from said second beam splitter. 46. The optical system of claim 45, further comprising a receiver receiving output signals from said first and second photosensors and providing a differential signal therefrom. 47. The optical system of claim 46, further comprising a first amplifier coupled between said first photosensor and said receiver, and a second amplifier coupled between said second photosensor and said receiver. 48. The optical system of claim 45, wherein said laser source comprises a CW laser source. 49. The optical system of claim 48, further comprising a laser-monitoring module monitoring said laser beam. 50. The optical system of claim 49, wherein said laser-monitoring module comprises a third photodetector and a third beam splitter directing part of said laser beam onto said third photodetector. 51. The optical system of claim 43, wherein said laser source is a CW laser source. 52. The optical system of claim 43, wherein said laser source is a pulsed laser source. 53. The optical system of claim 43, wherein said optical retarder is a variable retarder having its fast and slow axis aligned respectively with the first polarization direction and the second polarization direction. 54. The optical system of claim 45, further comprising an optical amplifier receiving said reflected beam from said first and second beam splitters and directing said reflected beam to said first and second photodetectors. 55. The method of claim 30, wherein the method further comprises: phase shifting one of the two mutually orthogonally polarized components of the rotated beam.
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