System and method for modulation mapping

• US 8,686,748 B2
• Filed: 04/27/2011
• Issued: 04/01/2014
• Est. Priority Date: 08/26/2005
• Status: Active Grant

• Current Assignee: DCG Systems Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: DCG Systems Incorporated (Thermo Fisher Scientific Incorporated)
• Inventors: Kasapi, Steven
• Primary Examiner(s): BENITEZ ROSARIO, JOSHUA
• Application Number:
  US13/095,831
• Publication Number:
  US 20110199110A1
• Time in Patent Office: 1,070 Days
• Field of Search: 32475421-75431, 250/338.1, 250/340, 250/341.2, 250/341.4, 250/341.8, 250/370.01, 250/492.2
• US Class Current: 324/754.23
• 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 method for probing an integrated circuit (IC), comprising:

stimulating said IC with a test signal;

illuminating a selected area of said IC with a laser beam;

collecting beam reflection from said IC;

converting said beam reflection to an electrical probing signal;

separating the electrical probing signal into a DC component and an AC component;

selecting a frequency or a band of frequencies of said AC component;

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

generating a spatial map of one of said total amplitude, total intensity, polarization rotation, and phase, for various locations over a selected area of said IC; and

displaying the spatial map on a monitor.

2. The method of claim 1, further comprising generating an optical image of said selected area of the IC from the DC component.

3. The method of claim 1, further comprising normalizing the spatial map using the DC component.

4. The method of claim 1, wherein:

collecting beam reflection comprises separating the beam into a vertically polarized component and horizontally polarized component; and

,

converting said beam comprises using a first photodetector to convert the vertically polarized component to generate vertically polarized part of said AC component and using a second photodetector to convert the horizontally polarized component to generate horizontally polarized part of said AC component.

5. The method of claim 4, further comprising mutually dividing or substracting the vertically polarized part of said AC component and the horizontally polarized part of said AC component.

6. The method of claim 5, further comprising positively biasing one of the first or second photodetector while negatively biasing the other of the first or second photodetector.

7. The method of claim 4, further comprising:

using the signal from the first photodetector to generate a spatial map of one of said total amplitude, total intensity, polarization rotation, and phase; and

using the signal from the second photodetector to generate a spatial map of a different one of said total amplitude, total intensity, polarization rotation, and phase.

8. The method of claim 1, further comprising demodulating the in-phase and quadrature components of the AC component.

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

stimulating said IC with a test signal;

illuminating a selected area of said IC with a laser beam;

collecting beam reflection from said IC;

converting said beam reflection to an electrical probing signal;

extracting an RF component from the electrical probing signal;

demodulating the in-phase and quadrature components of the RF component;

selecting a frequency or a band of frequencies of said RF component;

calculating RF power the selected frequency or band of frequencies;

displaying the RF power for a fixed position on the DUT or for a selected area of the DUT.

10. The method of claim 9, further comprising power filtering the RF component.

11. The method of claim 10, further comprising extracting a DC component from the electrical probing signal and using the DC component to generate an optical image of the DUT.

12. The method of claim 10, further comprising extracting a DC component from the electrical probing signal and using the DC component to normalize the RF power.

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

stimulating said IC with a plurality of test signals;

for each test signal of the plurality of test signals;

illuminating a selected area of said IC with a laser beam;

collecting beam reflection from said IC;

converting said beam reflection to an electrical probing signal;

extracting an AC component from the electrical probing signal;

selecting a frequency or a band of frequencies of said AC component;

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

generating a spatial map of one of said total amplitude, total intensity, polarization rotation, and phase, for various locations over a selected area of said IC;

displaying on a monitor a plot of the spatial maps generated for all of the test signals.

14. The method of claim 13, further comprising generating a cross-section of the plot.

15. The method of claim 13, 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.

16. The method of claim 15, wherein said reference signal is of frequency similar to that of said probing signal, but is shifted in phase.

17. The method of claim 13, further comprising obtaining a sync signal and illuminating a selected area of said IC with a laser beam according to the sync signal.

18. The method of claim 13, wherein illuminating a selected area of said IC with a laser beam further comprises splitting the laser beam into a vertically polarized component and a horizontally polarized component prior to the beam reaching the IC.

19. The method of claim 18, wherein converting said beam comprises using a first photodetector to convert the vertically polarized component to generate vertically polarized part of said AC component and using a second photodetector to convert the horizontally polarized component to generate horizontally polarized part of said AC component.