Apparatus and method for detecting photon emissions from transistors

• US 6,891,363 B2
• Filed: 09/03/2002
• Issued: 05/10/2005
• Est. Priority Date: 09/03/2002
• Status: Expired due to Term

• Current Assignee: DCG Systems Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Credence Systems Corporation (COHU Incorporated)
• Inventors: Coupanec, Patricia Le, Kasapi, Steven, Perdu, Philippe, Lo, William K., Desplats, Romain
• Primary Examiner(s): Zarneke, David
• Assistant Examiner(s): KOBERT, RUSSELL MARC
• Application Number:
  US10/234,231
• Publication Number:
  US 20040041575A1
• Time in Patent Office: 980 Days
• Field of Search: 324/158.1, 324/537, 324/764, 324/765, 324/768, 324/769, 382278-281
• US Class Current: 324/762.09
• CPC Class Codes: G01R 31/2656 using non-ionising electromagnetic radiation, e.g. optical radiation
• CPC Class Codes: G01R 31/311 of integrated circuits G01R31/31728 takes precedence

Abstract

A system, apparatus, and method for analyzing photon emission data to discriminate between photons emitted by transistors and photons emitted by background sources. The analysis involves spatial and/or temporal correlation of photon emissions. After correlation, the analysis may further involve obtaining a likelihood that the correlated photons were emitted by a transistor. After correlation, the analysis may also further involve assigning a weight to individual photon emissions as a function of the correlation. The weight, in some instances, reflecting a likelihood that the photons were emitted by a transistor. The analysis may further involve automatically identifying transistors in a photon emission image.

Claims

1. A method for analyzing photon emission data to discriminate between photons emitted from a transistor and noise, the photon emission data comprising a first photon emission and at least one second photon emission, each photon emission comprising characteristics including a spatial component corresponding with the space where each photon was detected and a temporal component corresponding with the time when each photon was detected, the method comprising:

receiving the first photon emission and the at least one second photon emission; and

determining whether at least one characteristic of the first photon emission correlates with at least one characteristic of the second photo emission;

wherein the first photon emission and the second photon emission are attributed to a transistor rather than noise when at least one characteristic of the first photon emission correlates with at least one characteristic of the second photon emission.

2. The method of claim 1 further comprising the operation of assigning a weight the first photon emission as a function of the operation of determining.

3. The method of claim 2 wherein the operation of determining comprises comparing the spatial component of the first photon emission with the spatial component of the at least one second photon emission.

4. The method of claim 3 wherein the spatial component of the first photon emission comprises a first x-value and a first y-value, and wherein the spatial component of the at least one second photon emission comprises at least one second x-value and at least one second y-value.

5. The method of claim 3 wherein the operation of comparing further comprises determining if the first x-value is within a x-range of the at least one second x-value.

6. The method of claim 5 wherein the operation of comparing further comprises determining if the first y-value is within a y-range of the at least one second y-value.

7. The method of claim 6 wherein the operation of assigning a weight to the first photon emission comprises assigning one weight value for each of the at least one second photon emissions having the at least one second x-value within the x-range and the at least one second y-value within the y-range.

8. The method of claim 3 further comprising:

comparing the temporal component of the first photon emission with the temporal component of the at least one second photon emission.

9. The method of claim 8 wherein the temporal component of the first photon emission comprises a first time value, and where the temporal component of the at least one second photon emission comprises at least one second time value.

10. The method of claim 9 wherein the operation of comparing further comprises determining if the first time value is within a time range of the at least one second time value.

11. The method of claim 10 wherein the operation of assigning a weight to the first photon emission comprises assigning one weight value for each of the at least one second time value within the time range.

12. The method of claim 10 wherein the operation of assigning a weight to the first photon emission comprises assigning one weight value for each of the at least one second photon emissions having the at least one second x-value within the x-range, the at least one second y-value within the y-range, and the at least one second time value within the time range.

13. The method of claim 3 wherein the spatial component of the first photon emission is the same as the spatial component of the at least one second photon emission.

14. The method of claim 1 wherein the operation of determining the first photon emission with the at least one second photon emission further comprises:

processing the first photon emission and the at least one second photon emission to provide at least one temporal subgroup of photons having similar temporal characteristics; and

determining a likelihood that photons within the temporal subgroup were emitted by a transistor.

15. The method of claim 14 wherein the operation of processing further comprises defining a plurality of time bins, each time bin defining a temporal range.

16. The method of claim 15 further comprising aggregating all photons within the temporal range.

17. The method of claim 16 wherein the first photon emission and the at least one second photon emission are collected from a transistor using a detector having a transit time spread, and further comprising setting the temporal range as the transit time spread.

18. The method of claim 14 wherein the operation of processing further comprises, for each photon within the temporal group, summing the number of photons within a set temporal range.

19. The method of claim 18 further comprising setting the temporal range as a transit time spread of a detector configured to detect the first photon emission and the at least one second photon emission.

20. The method of claim 1 further comprising

comparing the temporal component of the first photon emission with the temporal component of the at least one second photon emission.

21. The method of claim 20 wherein the temporal component of the first photon emission comprises a first time value, and where the temporal component of the at least one second photon emission comprises at least one second time value.

22. The method of claim 21 wherein the operation of comparing further comprises determining if the first time value is within a time range of the at least one second time value.

23. The method of claim 22 further comprising the operation of assigning a weight to the first photon emission as a function of the operation of correlating and wherein the operation of assigning a weight to the first photon emission comprises assigning one weight value for each of the at least one second time value within the time range.