Apparatus and method for detecting photon emissions from transistors

• US 20050146321A1
• Filed: 01/20/2005
• Published: 07/07/2005
• Est. Priority Date: 09/03/2002
• Status: Active Grant

• Current Assignee: DCG Systems Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Credence Systems Corporation (COHU Incorporated)
• Inventors: Kasapi, Steven, Perdu, Philippe, Lo, William K., Desplats, Romain, Le Coupanec, Patricia
• Granted Patent: US 7,038,442 B2
• Time in Patent Office: Days
• US Class Current: 702/180
• 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 emissions to discriminate between photons emitted from a transistor and noise, the photon emissions collected from a transistor using a detector having a transit time spread, the collected photon emissions comprising a spatial component and a temporal component corresponding with the space where each photon was detected and the time when each photon was detected, the method comprising:

receiving an indication of a group of photon emission data, the group being a subset of the collected photon emission data;

processing the group of photon emission data 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.

2. The method of claim 1 wherein the group of photon emission data comprises a spatial subset of the collected photon emission data.

3. The method of claim 2 wherein the spatial subset of the collected photon emission data comprises each photon emission within a spatial range.

4. The method of claim 3 wherein the spatial component of the photon emission data comprises an x-value and a y-value, and wherein the spatial range comprises an x-range and a y-range.

5. The method of claim 1 wherein the operation of processing further comprises defining a plurality of time bins, each time bin defining a temporal range.

6. The method of claim 5 further comprising aggregating all photons within the temporal range.

7. The method of claim 5 wherein the temporal range is set as the transit time spread.

8. The method of claim 1 wherein the operation of processing further comprises, for each photon within the group, summing the number of photons within a set temporal range.

9. The method of claim 8 wherein the temporal range is set as the transit time spread.

10. A method for analyzing photon emissions collected from a transistor discriminate between photons emitted from a transistor and photons emitted from other sources, the collected photon emissions comprising a spatial component and a temporal component corresponding with the space where each photon was detected and the time when each photon was detected, the method comprising:

spatially correlating the collected photon emissions data;

temporally correlating the collected photon emission data;

determining a likelihood that all or a portion of the spatially correlated photon emission data originated from a transistor photon emission.

11. The method of claim 10 wherein the operation of spatially correlating the collected photon emission data comprises obtaining a first grouping of spatially similar photon emissions from the collected photon emission data.

12. The method of claim 10 wherein the collected photon emission data comprises at least a first photon emission having a first spatial component and a first temporal component and at least a second photon emission having a second spatial component a second temporal component, the operation of spatially correlating the collected photon emission data comprises determining if the first spatial component is within a spatial range of the second spatial component.

13. The method of claim 11 wherein the operation of temporally correlating the collected photon emission data comprises obtaining a second grouping of temporally similar photon emissions from the first grouping.

14. The method of claim 10 wherein the operation of temporally correlating the collected photon emission data comprises determining if the first temporal component is within a temporal range of the second temporal component.