System and method for reducing radiation-induced false counts in an inspection system

Patent metadata

Field	Value
Publication number	US-10241217-B2
Application number	US-201715795028-A
Country	US
Kind code	B2
Filing date	Oct 26, 2017
Priority date	May 14, 2015
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

An inspection system with radiation-induced false count mitigation includes a radiation count controller coupled to one or more radiation sensors positioned proximate to an illumination sensor oriented to detect illumination from a sample. The radiation count controller may identify a set of radiation detection events based on radiation signals received from the radiation sensors during operation of the illumination sensor. The inspection system may further include an inspection controller to identify a set of illumination detection events based on an illumination signal, identify one or more features on the sample based on the set of illumination detection events, receive the set of radiation detection events from the radiation count controller, compare the set of radiation detection events to the set of illumination detection events to identify a set of coincidence events, and refine the one or more identified features on the sample based on the set of coincidence events.

First claim

What is claimed is:

1. An inspection system with radiation-induced false count mitigation, comprising:
a radiation count controller communicatively coupled to one or more radiation sensors configured to detect particle radiation, wherein at least one radiation sensor of the one or more radiation sensors is positioned proximate to an illumination sensor oriented to detect illumination from a sample, wherein the radiation count controller includes one or more processors configured to execute instructions causing the one or more processors to identify a set of radiation detection events based on radiation signals received from the one or more radiation sensors during operation of the illumination sensor; and
an inspection controller communicatively coupled to the illumination sensor and the radiation count controller, the inspection controller including one or more processors configured to execute instructions causing the one or more processors to:
identify a set of illumination detection events based on an illumination signal received from the illumination sensor;
identify one or more features on the sample based on the set of illumination detection events;
receive the set of radiation detection events from the radiation count controller;
compare the set of radiation detection events to the set of illumination detection events to identify a set of coincidence events, wherein the set of coincidence events corresponds to simultaneous occurrences of radiation detection events and illumination detection events; and
refine the one or more identified features on the sample based on the set of coincidence events.

2. The system of claim 1 , wherein the one or more processors of the radiation count controller are different than the one or more processors of the inspection controller.

3. The system of claim 1 , wherein the radiation count controller includes a microprocessor.

4. The system of claim 1 , wherein the inspection controller is further communicatively coupled to one or more additional illumination sensors, the one or more additional illumination sensors each configured to detect illumination from the sample on a first side of each of the one or more additional illumination sensors, wherein the radiation count controller is further communicatively coupled to one or more additional radiation sensors, wherein at least one radiation sensor of the one or more radiation sensors is positioned on a second side of each of the one or more additional illumination sensors.

5. The system of claim 4 , wherein the one or more processors of the radiation count controller are further configured to execute instructions causing the one or more processors to identify an additional set of radiation detection events based on radiation signals received from the one or more additional radiation sensors during operation of the one or more additional illumination sensors, wherein the one or more processors of the inspection controller are further configured to execute instructions causing the one or more processors to:
generate one or more additional sets of identified features on the sample based on one or more signals received from the one or more additional illumination sensors;
compare the set of identified features on the sample to the one or more additional sets of identified features on the sample to generate a modified set of identified features on the sample, wherein the modified set of identified features on the sample corresponds to features identified by at least two illumination sensors;
receive the additional set of radiation detection events from the radiation count controller;
compare the additional set of radiation detection events to the modified set of illumination detection events to identify an additional set of coincidence events, wherein the additional set of coincidence events corresponds to simultaneous occurrences of radiation detection events and illumination detection events; and
refine the modified set of identified features on the sample based on the additional set of coincidence events.

6. The system of claim 1 , wherein the illumination sensor includes one or more radiation shields positioned around one or more surfaces of the illumination sensor to block radiation from reaching the illumination sensor, wherein the one or more radiation shields are open on the first side of the illumination sensor to allow illumination from the sample to pass to the illumination sensor.

7. The system of claim 6 , wherein the one or more radiation shields are formed from at least one of tungsten or lead.

8. The system of claim 6 , wherein at least a portion the one or more radiation shields is further configured as a heat sink.

9. The system of claim 1 , wherein the one or more illumination sensors comprise:
at least one of one or more single-pixel sensors or one or more multi-pixel sensors.

10. The system of claim 9 , wherein the one or more single-pixel sensors comprise:
at least one of one or more photomultiplier tubes (PMTs), one or more photodiodes, or one or more avalanche photodiode (APD) devices.

11. The system of claim 9 , wherein the one or more multi-pixel sensors comprise:
at least one of one or more charge-coupled devices (CCDs), or one or more complementary metal-oxide semiconductor (CMOS) devices.

12. The system of claim 1 , wherein the one or more first radiation sensors of a first detector are configured to have a larger active area than an active area of the illumination sensor of the first detector.

13. The system of claim 1 , wherein the illumination sensors are positioned vertically.

14. The system of claim 1 , wherein the one or more radiation sensors are configured to detect at least one of muons, alpha particles, beta particles, or gamma radiation.

15. The system of claim 1 , wherein the one or more radiation sensors include one or more scintillation sensors.

16. The system of claim 1 , wherein the set of identified features on the sample includes one or more defect sites.

17. An inspection system with radiation-induced false count mitigation, comprising:
one or more detector assemblies comprising:
an illumination sensor configured to detect illumination from a sample; and
one or more radiation sensors configured to detect particle radiation;

a radiation count controller communicatively coupled to the one or more radiation sensors of the one or more detector assemblies, the radiation count controller including one or more processors configured to execute instructions causing the one or more processors to identify a set of radiation detection events based on radiation signals received from the one or more radiation sensors of the one or more detector assemblies during operation of the illumination sensors of the one or more detector assemblies; and
an inspection controller communicatively coupled to the illumination sensors of the one or more detector assemblies and the radiation count controller, the inspection controller including one or more processors configured to execute instructions causing the one or more processors to:
identify a set of illumination detection events based on an illumination signal received from the illumination sensors of the one or more detector assemblies;
identify one or more features on the sample based on the set of illumination detection events;
receive the set of radiation detection events from the radiation count controller;
compare the set of radiation detection events to the set of illumination detection events to identify a set of coincidence events, wherein the set of coincidence events corresponds to simul

Assignees

• Kla Tencor Corp

Inventors

• Jiang Ximan
• Romanovsky Anatoly
• Wolters Christian
• Biellak Stephen
• Tatarkhanov Mous

Classifications

• G01N23/2273

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• G01N21/9501 Primary

  Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20) · CPC title

• G01N23/05 Primary

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• G01T1/24 Primary

  with semiconductor detectors · CPC title