Abstract:
An inspection system with radiation-induced false count mitigation includes an illumination source configured to illuminate a sample, a detector assembly comprising an illumination sensor configured to detect illumination from the sample, and one or more radiation sensors configured to detect particle radiation, and control circuitry communicatively coupled to the detector. The control circuitry is configured to perform the steps of determining a set of radiation detection events based on one or more radiation signals received from the radiation sensors, determining a set of imaging events based on the illumination signal received from the illumination sensor, comparing the set of radiation detection events to the set of imaging events to generate a set of coincidence events, wherein the set of coincidence events comprises simultaneous imaging and radiation detection events, and excluding the set of coincidence events from the set of imaging events to generate a set of identified defect sites.
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.
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.
Abstract:
An electron-bombarded detector for detecting low light signals includes a vacuum tube structure defining a cylindrical vacuum tube chamber, a photocathode disposed at a first end of the vacuum tube chamber, a sensor disposed at a second end of the vacuum tube chamber, ring electrodes disposed in the vacuum tube chamber for generating an electric field that accelerates emitted photoelectrons toward the sensor, and a magnetic field generator configured to generate a symmetric magnetic field that applies a focusing lens effect on the photoelectrons. The ring electrodes and magnetic field generator are operating using one of a reduced distance focusing approach and an acceleration/deceleration approach such that the photoelectrons have a landing energy below 2 keV. The use of reflective mode photocathodes is enabled using either multi-pole deflector coils, or ring electrodes formed by segmented circular electrode structures. Large angle deflections are achieved using magnetic or electrostatic deflectors.
Abstract:
The disclosure is directed to image intensifier tube designs for field curvature aberration correction and ion damage reduction. In some embodiments, electrodes defining an acceleration path from a photocathode to a scintillating screen are configured to provide higher acceleration for off-axis electrons along at least a portion of the acceleration path. Off-axis electrons and on-axis electrons are accordingly focused on the scintillating screen with substantial uniformity to prevent or reduce field curvature aberration. In some embodiments, the electrodes are configured to generate a repulsive electric field near the scintillating screen to prevent secondary electrons emitted or deflected by the scintillating screen from flowing towards the photocathode and forming damaging ions.
Abstract:
An inspection system with radiation-induced false count mitigation includes an illumination source configured to illuminate a sample, a detector assembly comprising an illumination sensor configured to detect illumination from the sample, and one or more radiation sensors configured to detect particle radiation, and control circuitry communicatively coupled to the detector. The control circuitry is configured to perform the steps of determining a set of radiation detection events based on one or more radiation signals received from the radiation sensors, determining a set of imaging events based on the illumination signal received from the illumination sensor, comparing the set of radiation detection events to the set of imaging events to generate a set of coincidence events, wherein the set of coincidence events comprises simultaneous imaging and radiation detection events, and excluding the set of coincidence events from the set of imaging events to generate a set of identified defect sites.
Abstract:
An electron-bombarded detector for detecting low light signals includes a vacuum tube structure defining a cylindrical vacuum tube chamber, a photocathode disposed at a first end of the vacuum tube chamber, a sensor disposed at a second end of the vacuum tube chamber, ring electrodes disposed in the vacuum tube chamber for generating an electric field that accelerates emitted photoelectrons toward the sensor, and a magnetic field generator configured to generate a symmetric magnetic field that applies a focusing lens effect on the photoelectrons. The ring electrodes and magnetic field generator are operating using one of a reduced distance focusing approach and an acceleration/deceleration approach such that the photoelectrons have a landing energy below 2 keV. The use of reflective mode photocathodes is enabled using either multi-pole deflector coils, or ring electrodes formed by segmented circular electrode structures. Large angle deflections are achieved using magnetic or electrostatic deflectors.
Abstract:
One embodiment relates to a method of detecting a buried defect in a target microscopic metal feature. An imaging apparatus is configured to impinge charged particles with a landing energy such that the charged particles, on average, reach a depth within the target microscopic metal feature. In addition, the imaging apparatus is configured to filter out secondary electrons and detect backscattered electrons. The imaging apparatus is then operated to collect the backscattered electrons emitted from the target microscopic metal feature due to impingement of the charged particles. A backscattered electron (BSE) image of the target microscopic metal feature is compared with the BSE image of a reference microscopic metal feature to detect and classify the buried defect. Other embodiments, aspects and features are also disclosed.
Abstract:
The disclosure is directed to image intensifier tube designs for field curvature aberration correction and ion damage reduction. In some embodiments, electrodes defining an acceleration path from a photocathode to a scintillating screen are configured to provide higher acceleration for off-axis electrons along at least a portion of the acceleration path. Off-axis electrons and on-axis electrons are accordingly focused on the scintillating screen with substantial uniformity to prevent or reduce field curvature aberration. In some embodiments, the electrodes are configured to generate a repulsive electric field near the scintillating screen to prevent secondary electrons emitted or deflected by the scintillating screen from flowing towards the photocathode and forming damaging ions.