System and method for modulation mapping

• US 20070046301A1
• Filed: 05/18/2006
• Published: 03/01/2007
• Est. Priority Date: 08/26/2005
• Status: Active Grant

• Current Assignee: DCG Systems Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Credence Systems Corporation (COHU Incorporated)
• Inventors: Kasapi, Steven
• Granted Patent: US 7,733,100 B2
• Time in Patent Office: Days
• US Class Current: 324/754.220
• CPC Class Codes: G01R 31/2851 Testing of integrated circuits [IC] G01R31/317 takes precedence; testing individual devices G01R31/26; testing printed circuits G01R31/2801
• CPC Class Codes: G01R 31/308 using non-ionising electromagnetic radiation, e.g. optical radiation investigating or analysing materials by the use of optical means G01N21/00; image analysis G06T7/00
• CPC Class Codes: G01R 31/311 of integrated circuits G01R31/31728 takes precedence

Abstract

An apparatus for providing modulation mapping is disclosed. The apparatus includes a laser source, a motion mechanism providing relative motion between the laser beam and the DUT, signal collection mechanism, which include a photodetector and appropriate electronics for collecting modulated laser light reflected from the DUT, and a display mechanism for displaying a spatial modulation map which consists of the collected modulated laser light over a selected time period and a selected area of the IC.

Claims

1. A system for testing an integrated circuit microchip using laser probing, comprising:

a laser source providing a laser beam;

a beam optics receiving said laser beam and focusing said laser beam onto a selected spot on said microchip;

a photosensor receiving reflected laser light that is reflected from said microchip and providing an electrical signal;

collection electronics receiving the electrical signal from said photosensor and providing an output signal;

an analysis system receiving said output signal and providing a total power signal.

2. The system of claim 1, wherein said analysis system comprises a selector, enabling selection of a frequency or a band of frequencies, and wherein said total power signal reflects total power at a selected frequency or a band of frequencies.

3. The system of claim 2, wherein said analysis system is a spectrum analyzer.

4. The system of claim 1, wherein said analyzer is a lock-in amplifier.

5. The system of claim 4, further comprising a reference signal generator providing a reference signal, said reference signal having a frequency similar to that of said output signal, and having a different phase from that of said output signal.

6. The system of claim 3, further comprising a scanner for scanning the laser beam and a frame grabber receiving said total power signal.

7. The system of claim 5, further comprising a frame grabber receiving said total power signal.

8. The system of claim 3, further comprising a digital signal processor receiving said total power signal.

9. The system of claim 5, further comprising a digital signal processor receiving said total power signal.

10. The system of claim 2, further comprising:

a scanner for scanning the laser beam;

a frame grabber receiving said total power signal; and

,

a computer, said computer generating a spatial modulation map indicating total power value for various locations on said integrated circuit.

11. The system of claim 4, further comprising:

a scanner for scanning the laser beam;

a frame grabber receiving said total power signal; and

,

a computer, said computer generating a spatial modulation map indicating total power value for various locations on said integrated circuit.

12. The system of claim 1, wherein said beam optics further comprises phase to amplitude converter.

13. The system of claim 12, wherein said beam optics further comprises a beam scanner.

14. The system of claim 13, further comprising a computer, said computer generating a spatial modulation map indicating total power value for various locations on said integrated circuit.

15. The system of claim 14, wherein said phase to amplitude converter comprises a polarization differential probing (PDP) arrangement.

16. The system of claim 15, wherein said beam scanner comprises a laser scanning microscope (LSM).

17. The system of claim 15, further comprising a second photosensor receiving part of the reflected laser light.

18. The system of claim 14, further comprising a video amplifier.

19. A method for probing an integrated circuit (IC), comprising:

stimulating said IC with a test signal;

illuminating said IC with a laser beam;

collecting beam reflection from said IC;

converting said beam reflection to an electrical probing signal;

selecting a frequency or a band of frequencies of said probing signal;

calculating at least one of a total amplitude, a total intensity, and a phase of said probing signal at the selected frequency or band of frequencies.

20. The method of claim 19, further comprising generating a spatial map of one of said total amplitude, total intensity, and phase, for various locations over a selected area of said IC.

21. The method of claim 19, further comprising providing a reference signal and wherein said calculating comprises multiplying said probing signal with the reference signal to thereby provide a product signal, and integrating said product signal.

22. The method of claim 21, wherein said reference signal is of frequency similar to that of said probing signal.

23. The method of claim 20, wherein said calculating comprises calculating total power at the selected frequency or band of frequencies, and said generating a spatial map comprises generating a spatial map of total power for various locations over a selected area of said IC.

24. The method of claim 19, wherein said illuminating comprises scanning the laser beam over a selected area of said IC.

25. The method of claim 19, wherein said collecting beam reflection further comprises converting beam reflection phase into beam reflection amplitude.

26. The method of claim 20, further comprising generating an optical image of said selected area of the IC.

27. The method of claim 24, wherein said collecting comprises collecting beam reflection from said scanning and further comprising generating an optical image of said selected area from said beam reflection.

28. The method of claim 19, wherein said calculating comprises calculating a total amplitude of said probing signal at the selected frequency or band of frequencies.

29. The method of claim 19, wherein said calculating comprises calculating a total intensity of said probing signal at the selected frequency or band of frequencies.

30. The method of claim 19, wherein said calculating comprises calculating a phase of said probing signal at the selected frequency or band of frequencies.