NL2022755B1 - Method for inspecting a sample in a charged particle microscope - Google Patents

Method for inspecting a sample in a charged particle microscope Download PDF

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Publication number
NL2022755B1
NL2022755B1 NL2022755A NL2022755A NL2022755B1 NL 2022755 B1 NL2022755 B1 NL 2022755B1 NL 2022755 A NL2022755 A NL 2022755A NL 2022755 A NL2022755 A NL 2022755A NL 2022755 B1 NL2022755 B1 NL 2022755B1
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Netherlands
Prior art keywords
scintillator
sample
charged particle
photons
particle beam
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NL2022755A
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Dutch (nl)
Inventor
Zuidema Wilco
Pieter Hoogenboom Jacob
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Univ Delft Tech
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Publication of NL2022755B1 publication Critical patent/NL2022755B1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
    • H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/20—Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/22—Optical, image processing or photographic arrangements associated with the tube
    • H01J37/226—Optical arrangements for illuminating the object; optical arrangements for collecting light from the object
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2443—Scintillation detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/24455—Transmitted particle detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/26—Electron or ion microscopes
    • H01J2237/28—Scanning microscopes
    • H01J2237/2802—Transmission microscopes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/26—Electron or ion microscopes
    • H01J2237/28—Scanning microscopes
    • H01J2237/2803—Scanning microscopes characterised by the imaging method
    • H01J2237/2808—Cathodoluminescence

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

The invention relates to an apparatus and a method for inspecting a sample arranged on a top surface of a scintillator. The method comprises the steps of: directing' a beanl of charged. particles onto the sample, wherein a part of the charged particles pass through the sample and enter the scintillator, wherein at least a part of the charged particles which enter the scintillator is converted into photons, collecting at least a part of the photons by an optical assembly, which optical assembly is configured to image a focus plane onto a photon detector, and using a spatial characteristics of scattering of charged particles to collect and detect photons which originate predominantly fronl charged. particles which. have been scattered in the sample.

Description

No. NLP204040A Method for inspecting a sample in a charged particle microscope
BACKGROUND The invention relates to a method for inspecting a sample in a charged particle microscope. In particular the invention relates to a method for detection of charged particles after transmission through a sample using a scintillator. The invention may be applied to charged particles of any type, such as electrons, positrons, ions and others. The International Patent Application published under WO 2015/170969 discloses an apparatus and method for inspecting a sample using a plurality of charged particle beams. The apparatus comprises a sample holder for holding the sample, a multi beam charged particle generator for generating an array of primary charged particle beams, an electro-magnetic lens system for directing said array of primary charged particle beams into an array of separate focused primary charged particle beams at the sample holder, a multi-pixel photon detector arranged for detecting photons created by said focused primary charged particle beams when said primary charged particle beams impinge on the sample or after transmission of said primary charged particle beams through the sample, an optical assembly for conveying photons created by at least two adjacent focused primary charged particle beams of said array of separate focused primary charged particle beams to distinct and/or separate pixels or to distinct and/or separate groups of pixels of the multi-pixel photon detector, and a layer of luminescent material. The sample holder is arranged to position the sample between the electro-magnetic lens system and the layer of luminescent material, such that the charged particles impinge on the layer of luminescent material after transmission through said sample.
When the charged particles which have passed through the sample, impinge on the layer of luminescent material, photons are created by said charged particles. Said photons are directed to a photon detector. The detected photon intensity serves as a measure for the amount of transmitted charged particles. Accordingly, the detected photon intensity can be used to establish a transmission image of the sample.
In order to allow the detection of charged particles after transmission through a sample, the sample needs to be a very thin sample, usually less than 100 nm. Such samples are usually arranged on top of a sample grid, also denoted as a TEM grid, for supporting the thin sample. However, only that part of the sample which is arranged on an aperture in the grid can be imaged. The part of the sample which arranged directly above the bars of the grid cannot be imaged, since the bars block the transmitted charged particles. An advantage of the use of the layer of luminescent material is, that the sample can be arranged on top of the layer of luminescent material and that a sample grid, also denoted as a TEM grid, for supporting the sample is not necessary.
SUMMARY OF THE INVENTION The transmission image establish according to the prior art is predominantly provided by charged particles which are not scattered in the sample. The inventors have realized that a setup where the sample is arranged on top of a layer of luminescent material, can be operated to also detect other signals, preferably additional to signals from the non-scattered charged particles.
It is an object of the present invention to provide a method and/or apparatus which allows to obtain additional information from a sample which is arranged on top of a layer of luminescent material.
According to a first aspect, the invention pertains to a method for inspecting a sample arranged on a top surface of a scintillator, wherein the method comprises the steps of: directing a beam of charged particles onto the sample, wherein a part of the charged particles pass through the sample and enter the scintillator, wherein at least a part of the charged particles which enter the scintillator is converted into photons, collecting at least a part of the photons by an optical assembly, which optical assembly is configured to image a focus plane onto a photon detector, and using a spatial characteristics of scattering of charged particles to collect and detect photons which originate predominantly from charged particles which have been scattered in the sample.
The inventors have realized that the transmission image of the prior art provides an image which predominantly provided by charged particles which are not scattered in the sample. In analogy with optical microscopy, this image predominantly provided by non-scattered charged particles is denoted as ‘bright field image’.
The inventors have further realized that a scattering in the sample gives rise to charged particles which deviate from their original trajectory. Accordingly, the spatial characteristic from scattered charged particles deviate from non-scattered charged particles. According to the present invention, this difference in spatial characteristics can be used to collect and detect photons which, at least to a large extend, originate from charged particles which have been scattered in the sample, even in case the sample is arranged on the top surface of the scintillator. In analogy with optical microscopy, this image predominantly provided by scattered charged particles is denoted as ‘dark field image’. This dark field image provides information about the charged particles which have been scattered in the sample arranged on the top surface of the scintillator, which information is additional to the information from the bright field image that originated predominantly from the charged particles which have not been scattered in the sample.
In a first embodiment of the method according to the present invention, the focus plane of the optical assembly can be arranged at a first position below the top surface of the scintillator where a maximum signal of the bright field image originates, wherein the method comprises the step of: positioning the focus plane of the optical assembly at a second position, wherein the second position is arranged in between the first position and the top surface of the scintillator, in order to detect photons from charged particles which have been scattered in the sample.
The non-scattered charged particles penetrate in the scintillator and are converted into photons. This conversion reaches a maximum at a certain depth in the scintillator. Positioning the focus plane of the optical assembly at a first position which substantially corresponds to the position of maximum conversion of the non-scattered charged particles, provides a maximum signal of the bright field image.
However, a scattering in the sample gives rise to scattered charged particles, which may have a lower energy than the non-scattered charged particles. In addition, the scattering in the sample also results in a divergence or diffusion of the scattered charged particles. These scattered charged particles penetrate less deep into the scintillator than non-scattered charged particles and/or these diverged or diffused scattered charged particles penetrate into the scintillator also sideways around the position where the non-scattered charged particles penetrate inte the scintillator. The conversion of scattered charged particles into photons occurs predominantly less deep in the 5 scintillator than the conversion of non-scattered charged particles.
By positioning the focus plane of the optical assembly at a second position in between the first position for obtaining the bright field image and the top surface of the scintillator, photons from charged particles which have been scattered in the sample can be obtained to provide a dark field image. This dark field image provides information about the charged particles which have been scattered in the sample arranged on the top surface of the scintillator, which information is additional to the information from the bright field image that originated predominantly from the charged particles which have not been scattered in the sample.
In an embodiment, the optical assembly comprises a confocal arrangement which uses a spatial pinhole to at least partially block out-of-focus light to reach the photon detector. When arranging the focus plane at the second position, the first position will be out-of-focus. Accordingly the spatial pinhole allows to at least partially block photons which originate from the non-scattered charged particles.
In an embodiment, the optical assembly comprises an objective lens for collecting photons from the scintillator, wherein the objective lens is moveable in a direction towards or away from the top surface of the scintillator, preferably wherein the objective lens is moveable in a direction substantially perpendicular to the top surface of the scintillator. By changing the focus position in a direction towards or away from the top surface of the scintillator, one can switch between a bright field imaging mode and a dark field imaging mode.
In an embodiment, a spacer layer is arranged in between the scintillator and the sample, wherein the spacer layer comprises a material with a low atom number.
In an embodiment, the spacer layer comprises a material with an atom number below 15, preferably a material with an atom number below 7. In an embodiment, the spacer layer comprises Boron or Carbon.
The inventors have found that, when such a spacer layer is present, a difference in penetration depth between the non-scattered and the scattered charged particles increases.
Accordingly, a distance between the first position for observing predominantly non-scattered charged particles, and the second position for observing predominantly scattered charged particles, increases.
This increase in the distance between the first and second position can provide a better separation between photons which originate from non-scattered charged particles and photons which originate from scattered charged particles, thus between of the bright field and the dark field signals.
In an embodiment, the layer has a thickness of at least 50 nm, preferably at least 100 nm.
The inventors have found that a thicker spacer layer provides a larger separation between the first position and the second position.
The more the second position is spaced apart from the first position, the better separation between the bright field and dark field can be obtained.
However, a thicker spacer layer also reduces the number of charged particles which pass through said spacer layer.
Accordingly, in an embodiment, the layer has a thickness smaller than 1000 mm, preferably smaller than 500 nm.
It is noted, that the number of charged particles which pass through a spacer layer of a certain thickness also depends on the energy of said charged particles.
Accordingly, an energy dependent optimal thickness of the spacer layer can be established which provides an increased separation of the first and second position without loss of too much signal.
For example, when using 5 keV electrons as charged particles, an optimal thickness of the spacer layer is approximately 120 nm.
In an embodiment, the spacer layer is provided at a side of the sample which is configured to face the surface of the scintillator. An advantage of providing the spacer layer to the sample is, that the thickness of the spacer layer can be adapted to the energy of the charged particles which is expected to be used for studying the sample.
In a preferred embodiment, the spacer layer is provided on the scintillator, in particular the spacer layer is arranged on the top surface of the scintillator. Preferably, the spacer layer is configured to position the sample on a surface of the spacer layer facing away from the scintillator. An advantage of providing the spacer layer on the scintillator is, that the sample can be positioned straight onto the spacer layer, In a second embodiment of the method according to the present invention, the scintillator comprises a saturation threshold above which an increase in the intensity of the charged particle beam does not lead to an increase in converted photons, wherein intensity of the charged particle beam is configured to a value above the saturation threshold of the scintillator. Preferably, the intensity of the charged particle beam is selected such that the intensity of the part of the charged particle beam that is transmitted through the sample has a value above the saturation threshold of the scintillator. Accordingly, in this embodiment, the scintillator is used above its saturation threshold. In this situation, an increase in transmitted charged particles does not lead to an increase in photon output anymore. Because the scintillator according to this embodiment operates above its saturation threshold, the photon intensity depends at least substantially on the scattering volume of the charged particles which enter the scintillator. A stronger scattering of the charged particles in the sample increases the scattering volume of the charged particles in the scintillator, leading to a higher light intensity output.
By operating the scintillator above the saturation threshold, variations in the intensity of the light from the scintillator is at least substantially dependent of the amount of scattered charged particles. Accordingly the contrast in the image obtained by operating the scintillator above the saturation threshold depends on the amount of scattered charged particles, just as in a dark field image. In an embodiment, the scintillator comprises a material with a low saturation threshold. Preferably, the scintillator is configured such that the saturation threshold is reached with at most 90% of the maximum intensity of the charged particle beam used for studying the sample. Preferably, the scintillator is configured such that the saturation threshold is reached with at least 5% of the maximum intensity of the charged particle beam. Preferably, the saturation threshold is reached with at most 90 & and/or at least 5% of the maximum intensity of the charged particle beam with a charged particle energy of approximately 15 keV.
Preferably the scintillator comprises an organic scintillator which has been bleached prior to use in the method according to the invention. In an embodiment, said organic scintillator comprises a plastic scintillator paint or an organic light-emitting polymer. An example of such a plastic scintillator paint is EJ-296 from Eljen Technology.
By providing this organic scintillator and subjecting the organic scintillator to a bleaching process and using the remaining, stable emission centers, a scintillator with a low saturation threshold can be obtained. In an embodiment, the bleaching process comprises the steps of directing a beam of charged particles onto the scintillator and monitoring the intensity of the emitted light from the scintillator, at least until a substantially constant light intensity is obtained. From the first instance that the beam of charged particles impinge on the scintillator, the light intensity decreases rapidly due to the bleaching to a substantially stable lower level,
yielding a bleached scintillator with a low saturation threshold. In addition or alternatively, the bleaching process may also be performed by illuminating the scintillator with particles or charged particles, such as for example electrons, protons, neutrons, ions, or by illuminating the scintillator with electromagnetic radiation, such as for example UV light or visible light with high intensity.
According to a second aspect the invention provides a method for inspecting a sample arranged on a top surface of a scintillator, wherein the method comprises the steps of: directing a beam of charged particles onto the sample, wherein a part of the charged particles pass through the sample and enter the scintillator, wherein at least a part of the charged particles which enter the scintillator converted into photons, collecting at least a part of the photons by an optical assembly, which optical assembly is configured to image a focus plane onto a photon detector, wherein the scintillator is at least substantially transparent for light in a wavelength range in the visual spectrum, in particular in a wavelength range outside a photo-excitation and/or photo-emission wavelength bands of the scintillator, wherein the method comprises the step of observing the sample by a light optical microscope through the scintillator material.
Accordingly, the sample can be observed by a light optical microscope through the scintillator material. Preferably the sample is observed using light with a wavelength substantially outside the photo-excitation and/or photo-emission wavelength bands of the scintillator. This allows to study, position and select an area of the sample using the light optical microscope before using the charged particle exposure system for creating a high resolution bright field and/or dark field image of said area.
Accordingly, this embodiment allows to use light optical microscopy to obtain additional information from a sample which is arranged on top of a layer of luminescent material.
In an embodiment, the scintillator comprises a material with a narrow photo-excitation and/or photo- emission wavelength bands, in particular wherein the photo- excitation and/or photo-emigsion wavelength bands are narrower than 100 nm, preferably narrower than 50 nm, more preferably narrower than 20 nm.
Preferably, the method also comprises the step of using a spatial characteristics of scattering of charged particles to collect and detect photons which originate predominantly from charged particles which have been scattered in the sample.
According to a third aspect, the present invention provides an apparatus for inspecting a sample, wherein the apparatus comprises: a sample holder for holding the sample, a charged particle beam generator for generating a charged particle beam, a charged particle optical lens system for directing said charged particle beam towards said sample holder, a scintillator which is arranged in order to position the sample between the charged particle optical lens system and the scintillator, such that at least a part of the charged particles which pass through the sample, enter the scintillator, wherein the scintillator is configured for converting at least a part of the charged particles which enter the scintillator into photons, a light optical assembly for collecting at least a part of the photons created in the scintillator, and directing these photons to a photon detector, wherein the scintillator comprises a spacer layer, wherein the spacer layer is arranged on the top surface of the scintillator, wherein the spacer layer has a thickness of at least 50 nm, preferably at least 100 nm. Preferably, the spacer layer is configured to position the sample on a surface of the spacer layer facing away from the scintillator.
In an embodiment, the spacer layer comprises a material with a low atom number. Preferably, the spacer layer comprises a material with an atom number below 15, preferably a material with an atom number below 7. In an embodiment, the spacer layer comprises Boron or Carbon.
In an embodiment, the layer has a thickness smaller than 1000 nm, preferably smaller than 500 nm.
According to a fourth aspect, the present invention provides an apparatus for inspecting a sample, wherein the apparatus comprises: a sample holder for holding the sample, a charged particle beam generator for generating a charged particle beam, a charged particle optical lens system for directing said charged particle beam towards said sample holder, a scintillator which is arranged in order to position the sample between the charged particle optical lens system and the scintillator, such that at least a part of the charged particles which pass through the sample, enter the scintillator, wherein the scintillator is configured for converting at least a part of the charged particles which enter the scintillator into photons, a light optical assembly for collecting at least a part of the photons created in the scintillator, and directing these photons to a photon detector, wherein scintillator comprises a saturation threshold above which an increase in the intensity of the charged particle beam does not lead to an increase in converted photons, in particular wherein the scintillator is configured such that the saturation threshold is reached with at most 90% of the maximum intensity of the charged particle beam from the charged particle beam generator. Preferably, the scintillator is configured such that the saturation threshold is reached with at least 5% of the maximum intensity of the charged particle beam of the charged particle beam generator. Preferably, the saturation threshold an reached with at most 90 % and/or at least 5% of the maximum intensity of the charged particle beam with a charged particle energy of approximately 15 keV.
In an embodiment, the sample holder comprises said scintillator. In an embodiment, the scintillator comprises a top surface, wherein the top surface is configured for arranging the sample on the top surface of the scintillator. An advantage of the use of the top layer of the scintillator for carrying the sample is that a sample grid, also denoted as a TEM grid, for supporting the sample is not necessary.
In an embodiment, the scintillator is at least substantially transparent, preferably the scintillator is substantially transparent for light in a wavelength range in the visual spectrum. Accordingly, the sample can be observed by a light optical microscope through the scintillator material. This allows to study, position and select an area of the sample using the light optical microscope before using the charged particle exposure system for creating a high resolution bright field and/or dark field image of said area. Accordingly, this embodiment allows to use light optical microscopy to obtain additional information from a sample which is arranged on top of a layer of luminescent material.
In an embodiment, the scintillator comprises a material with a narrow photo-excitation and/or photo- emission wavelength bands. By selecting a scintillator with appropriate and narrow photo-excitation and/or photo- emission wavelength bands, correlative fluorescence microscopy can be performed on the sample through the scintillator. Preferably the correlative fluorescence microscopy can be performed using at least part of the same optical assembly for collecting at least a part of the photons created in the scintillator by the transmitted charged particles.
According to a Fifth aspect, the present invention provides an apparatus for inspecting a sample, wherein the apparatus comprises: a sample holder for holding the sample, a charged particle beam generator for generating a charged particle beam, a charged particle optical lens system for directing said charged particle beam towards said sample holder, a scintillator which is arranged in order to position the sample between the charged particle optical lens system and the scintillator, such that at least a part of the charged particles which pass through the sample, enter the scintillator, wherein the scintillator is configured for converting at least a part of the charged particles which enter the scintillator into photons, a light optical assembly for collecting at least a part of the photons created in the scintillator, and directing these photons to a photon detector, wherein the scintillator is at least substantially transparent for light in a wavelength range in the visual spectrum, in particular in a wavelength range outside a photo-excitation and/or photo-emission wavelength bands of the scintillator.
Accordingly, the sample can be observed by a light optical microscope through the scintillator material. In particular, the sample can be observed in the wavelength range of the visual spectrum where the scintillator is at least substantially transparent and using light with a wavelength substantially outside the photo-excitation and/or photo-emission wavelength bands of the scintillator. This allows to study, position and select an area of the sample using the light optical microscope before using the charged particle exposure system for creating a high resolution bright field and/or dark field image of said area. Accordingly, this embodiment allows to use light optical microscopy to obtain additional information from a sample which is arranged on top of a layer of luminescent material. In an embodiment, the scintillator comprises a material with a narrow photo-excitation and/or photo- emission wavelength bands, in particular wherein the photo- excitation and/or photo-emission wavelength bands are narrower than 100 nm, preferably narrower than 50 nm, more preferably narrower than 20 nm. By selecting a scintillator with appropriate and narrow photo-excitation and/or photo- emission wavelength bands, correlative fluorescence microscopy can be performed on the sample through the scintillator. Preferably the correlative fluorescence microscopy can be performed using at least part of the same optical assembly for collecting at least a part of the photons created in the scintillator by the transmitted charged particles.
The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which: Figure 1 schematically shows an example of a Multi-Beam Scanning Electron Microscope (MBSEM), Figure 2 schematically shows a first example of a detection arrangement according to the invention,
Figure 3 shows a SEM \‘dark-field’ image of pancreatic tissue generated by the arrangement of figure 2, Figure 4 schematically shows a second example of a detection arrangement according to the invention Figure 5A and 5B schematically show a third example of a detection arrangement according to the invention, Figure 6 shows a SEM ‘dark-field’ image of brain tissue generated by the arrangement of figure 5A and 5B, and Figure 7 schematically shows a fourth example of a detection arrangement according to the invention.
DETAILED DESCRIPTION OF THE INVENTION Figure 1 schematically shows a first example of a transmission electron detection system in a Scanning Electron Microscope 1 (SEM). The SEM 1 comprises an electron-optical column 2 which is provided with an electron source 15 and electron-optics for projecting, focusing and/or scanning a electron beam 3 onto and over a sample 4. The SEM 1 is usually provided with an electron detector 6 for detecting secondary electrons 7 created by said electron beam when said electron beam 3 impinges on the sample 4.
As schematically shown in figure 1, the sample 4 is arranged on a top surface of a scintillator 5. Preferably the scintillator 5 is part of a sample holder (not shown) which is configured for positioning and/or moving the sample with respect to the electron beam 3. Preferably the sample 4 is a thin sample with a thickness which allows at least part of the electrons to travel through the sample 4 and reach the scintillator 5. Such thin samples are for example known in the art for use in Transmission Electron Microscopes (TEM).
The transmitted electrons which reach the scintillator 5 generate luminescence light 8. As schematically shown in figure 1, the assembly as shown is provided with a light optical objective lens 9 for collecting the luminescence light 8, which luminescence light 8 is directed to a light detector 10, for example a CCD detector, using a mirror 11.
As shown in figure 1, the transmission electron detection system is arranged at least partially in a vacuum chamber 12 comprising an outlet 13 for coupling to a vacuum pump for reducing the pressure inside the vacuum chamber 12. As also shown in figure 1, the detector is preferably arranged outside the vacuum chamber 12, and the luminescence light 8 is directed through an optical window 14 in a wall of the vacuum chamber 13 towards the light detector 10. An advantage of such a setup is, that the light detector 10 does not need to be vacuum compatible, When studying a sample 4 on the scintillator 5 using this transmission electron detection system, the intensity of the luminescence light 8 as detected by the light detector 10 serves as a measure for the transmission of electrons through the sample 4. This kind of detection provides a ‘bright-field’ image of the sample 4.
However, the transmitted electrons also comprise electrons which have been scattered in the sample 4, These scattered electrons may provide additional information about the sample 4. Since the transmitted electrons predominantly comprise non-scattered charged particles, the detection of other signals, preferably additional to signals from the non-scattered charged particles, is very difficult.
A first example for detecting other signals is schematically shown in figure 2. Figure 2 shows a detail of a sample 24 arranged on top of a scintillator 25. When a beam of electrons 23 impinges on the sample 24, the non- scattered electrons which are transmitted through the sample 24 arrive in the scintillator 25. The transmitted electrons are scattered 21 in the scintillator 25. As schematically indicated in figure 2, the maximum signal originates from a certain position below the surface 30. Accordingly, the focus plane of the optical assembly, in particular the microscope objective 29 can be arranged at a first position 26 below the top surface 30 of the scintillator 25 where a maximum signal of the bright field image originates.
Scattering of electrons 23 in de sample 24 gives rise to scattered electrons that penetrate less deep in the scintillator 25. These scattered electrons are also scattered 22 in the scintillator and penetrate less deep in the scintillator 25 as schematically indicated in figure 2.
By positioning the focus plane of the optical assembly, in particular the microscope objective 29 at a second position 27, wherein the second position 27 is arranged in between the first position 26 and the top surface 30 of the scintillator 25, photons which originate from charged particles which have been scattered in the sample 24 can be detected. As schematically indicated in figure 2, at the second position 27 the signal of the bright field image from the electrons 21 which were not scattered in the sample 24 is lower, and the signal of the electrons 22 which were scattered in the sample 24 is relatively large. Accordingly, collecting at least a part of the photons which originate from the second position 27 allows to construct an image comprising information from the electrons which have been scattered in the sample 24. An image of electrons which have been scattered in the sample 24 is also referred to as a ‘dark-field’ image. The microscope objective 29 for collecting photons from the scintillator 25 is moveable in a direction Z towards or away from the top surface 30 of the scintillater 25. Thus according to the example of a method according to the present invention, by moving the focus position of the light objective lens 29 from the first position 26 to the second position 27 over a distance Al, one can switch between a bright-field and a dark-field imaging mode.
In the example shown in figure 2, the photons created in the scintillator 25 are collected by the microscope objective 29 and directed onto a detector 33 using optical lenses 31, 32. In particular, the optical assembly 29, 31, 32 is configured to image a focus plane onto the detector 33. In order to at least partially block out-of-focus light to reach the detector 33, the optical assembly may comprise a confocal arrangement which uses a spatial pinhole 34 to block out-of-focus light.
When arranging the focus plane at the second position 27, the first position 26 will be out-of-focus.
Accordingly the spatial pinhole 34 allows to at least partially block photons which originate from the electrons which have not be scattered in the sample 24. Figure 3 shows a SEM \‘dark-field’ image of pancreatic tissue generated by arranging the focus plane of the optical assembly at the second position 27 arranged in between the first position 26 and the top surface 30 of the scintillator 25. A second example for detecting other signals is schematically shown in figure 4. Figure 4 shows a detail of a sample 24 arranged on top of a scintillator 25. The arrangement according to this second example differs from the arrangement according to the first example by a spacer layer 35 which 1s arranged in between the scintillator 25 and the sample 24. Due to the spacer layer 35, a difference in penetration depth between the non-scattered charged particles 21 and the scattered charged particles 22 increases as schematically indicated in figure 4. Accordingly, the distance between the first position 26 for observing predominantly non-scattered charged particles, and the second position 27 for observing predominantly scattered charged particles, increases to a distance A2. This increase in the distance between the first and second position provides a better separation between photons which originate from non-scattered charged particles 21 and photons which originate from scattered charged particles 22, thus between of the bright field and the dark field signals.
Preferably, the layer 35 has a thickness d of at least 50 nm, preferably at least 100 nm.
It is noted that in general a thicker spacer layer 35 provides a larger separation A2 between the first position 26 and the second position 27. However, a thicker spacer layer 35 also absorbs more charged particles and thus reduces the number of charged particles which reach the scintillator 25 and are converted into photons.
Accordingly, it is preferred that the layer 35 has a thickness d smaller than 1000 mm, preferably smaller than 500 nm.
It is noted, that the number of charged particles which pass through a spacer layer 35 of a certain thickness d also depends on the energy of said charged particles.
Accordingly, an energy dependent optimal thickness d of the spacer layer 35 can be established which provides an increased separation A2 of the first and second position without loss of too much signal.
For example, when using 5 keV electrons as charged particles, an optimal thickness d of the spacer layer 35 is approximately 120 nm.
It is noted that the spacer layer 35 is arranged in between the sample 24 and the scintillator 25. Although the spacer layer may be provided on the sample 24, in particular at a side of the sample 24 which is configured to face the top surface 30 of the scintillator 24, it is preferred that the spacer layer 35 is provided on the top surface 30 of the scintillator 25. As schematically indicated in figure 4, the spacer layer 35 is configured to enable positioning the sample 35 on a top surface 36 of the spacer layer 35, which top surface 36 is arranged at a side of the spacer layer 35 facing away from the scintillator 25,
Another example of a way of obtaining information additional to a ‘bright-f£ield’ image is by using the scintillator in saturation.
Such a method of obtaining additional information uses a scintillator which comprises a saturation threshold a above which an increase in the intensity of the charged particle beam does not lead to an increase in converted photons.
Figure 5A schematically shows a detail of a sample 44 arranged on top of a scintillator 45. When a beam of electrons 43 impinges on the sample 44, the electrons which are not scattered in the sample 44 are transmitted through the sample 44 and arrive in the scintillator 45. These transmitted electrons are scattered in the scintillator 45 and spread over a first scattering volume 41 where these electrons are converted into light 49. At least part of the light 49 is collected by the optical assembly comprising a microscope objective 46 and an imaging lens 47, and is projected onto a detector 48.
Usually, the intensity of the luminescence light 49 as detected by the detector 48 serves as a measure for the transmission of electrons through the sample 44. As previously presented, this kind of detection provides a ‘bright-field’ image of the sample 44.
However, when the intensity of the electrons transmitted through the sample 44 is above the saturation threshold of the scintillator 45, a small variation in the number of transmitted electrons does not result in a variation in the intensity of the luminescence light 49. Accordingly, when the scintillator 45 is operated above the saturation threshold, a changed in transmission of the electrons through the sample 44 will not yield a contrast in an image produced from the converted light 49.
Figure 5B schematically shows a detail of a sample 44’ arranged on top of the scintillator 45, which sample 44’ provides a scattering of the beam of electrons
43. When the electrons 43 which have been scattered in the sample 44° are transmitted through the sample 44’ and arrive in the scintillator 45, these transmitted electrons are scattered over a second scattering volume 42 in the scintillator 45 and are converted into light 49. Due to the scattering in the sample 44’, the transmitted electrons are already spread before they enter the scintillator 45 and according the second scattering volume 42 is larger than the first scattering volume 41 (compare figure 4A and 4B).
Because the scintillator 45 is saturated, the intensity of the light 49 only depends on the scattering volume in the scintillator 45, which corresponds to a light emission volume in the scintillator 45. Stronger scattering in the sample 44’ increases this volume, which leads to a higher light intensity output towards the microscope objective 46. Accordingly, the intensity of the luminescence light 49 as detected by the detector 48 serves as a measure for the scattering of electrons in the sample 44’. An image of electrons which have been scattered in the sample 44' is also referred to as a ‘dark-field’ image.
Figure 6 shows a SEM ‘dark-field’ image of brain tissue generated by using a the scintillator above its saturation threshold.
Figure 7 schematically shows a second example of a transmission electron detection system in a Scanning Electron Microscope 51 (SEM). The SEM 51 comprises an electron-optical column 52 which is provided with an electron source 58 and electron-optics for projecting, focusing and/or scanning a electron beam 53 onto and over a sample 54. The SEM 51 is usually provided with an electron detector 56 for detecting secondary electrons 57 created by said electron beam when said electron beam 53 impinges on the sample 54.
As schematically shown in figure 7, the sample 54 is arranged on a top surface of a scintillator 55. Preferably the scintillator 55 is part of a sample holder {not shown} which is configured for positioning and/or moving the sample 54 with respect to the electron beam 53. In particular, the sample 54 is a thin sample with a thickness which allows at least part of the electrons to travel through the sample 54 and reach the scintillator 55. Such thin samples are for example known in the art for use in Transmission Electron Microscopes (TEM).
The transmitted electrons which reach the scintillator 55 generate luminescence light 59. As schematically shown in figure 7, the assembly as shown is provided with a light optical objective lens 60 for collecting the luminescence light 59, which luminescence light 59 is directed to a light detector 61, for example a CCD detector, using a mirror 62.
The transmission electron detection system 51 is arranged at least partially in a vacuum chamber 63 comprising an outlet 64 for coupling to a vacuum pump for reducing the pressure inside the vacuum chamber 63. Again, the light detector 61 is preferably arranged outside the vacuum chamber 63, and the luminescence light 59 is directed through an optical window 65 in a wall of the vacuum chamber 63 towards the light detector 61.
When studying a sample 54 on the scintillator 55 using this transmission electron detection system, the intensity of the luminescence light 59 as detected by the light detector 61 serves as a measure for the transmission of electrons through the sample 54. This kind of detection provides a ‘bright-field’ image of the sample 54. In addition, the light detector 61 can also provide a ‘dark- field’ image by repositioning the focus position of the light optical objective lens 60 as described above with reference to figures 2 and 4, or by using the scintillator 55 above its saturation threshold as described above with reference to figures 5A and 5B.
A further way of obtaining additional information from the sample 54 is to use a scintillator 55 which is at least substantially transparent for light in a wavelength range in the visual spectrum, in particular in a wavelength range outside a photo-excitation and/or photo-emission wavelength bands of the scintillator 55. When using such a scintillator 55, the sample can also be observed through the scintillator 55 by means of a light microscope.
Accordingly, the detection system 1s provided with a switchable mirror 62 which is configured to switch the light beam path from a first configuration, where mirror
62 reflects light from the light optical objective lens 60 towards the light detector 61, to a second configuration, where the mirror 62’ reflects light 66 between the light optical objective lens 60 and the microscope optics 68. Preferably, the microscope optics 68 are arranged outside the vacuum chamber 63, and the light optical path between the light optical objective lens 60 and the microscope optics 68 is directed through an optical window 67 in a wall of the vacuum chamber 63. Accordingly the microscope optics 68 do not need to be vacuum compatible.
The microscope optics 68 comprises a light source for directing light along the optical path comprising the microscope optics 60, via the window 67, the mirror 627, the light optical objective lens 60, and the scintillator 55, for illuminating the sample 54. Reflected light and/or fluorescence light from the sample 54 can be collected by the light optical objective lens 60 and is directed back along the optical path to the microscope optics 68, where the collected reflected light and/or fluorescence light is directed onto a light detector, for example a CCD detector, to obtain a light optical image and/or a fluorescence image.
It is noted that due to the switchable mirror 62, the detection system uses either the light detector 61 or the microscope optics 68. As a first alternative to the switchable mirror 62, also a beam splitter can be used, for example a 50/50 beam splitter. This allows to use both detection systems at the same time and/or without the need of switching the switchable mirror 62. As a second alternative to the switchable mirror 62, also a dichroic mirror can be used, which dichroic mirror is configured for reflecting electroluminescence light from the sample to the light detector 61, and which is configured to reflect light of another wavelength range along the optical path of the microscope optics 68.
It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention.
From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the spirit and scope of the present invention.

Claims (23)

CONCLUSIESCONCLUSIONS 1. Werkwijze voor het inspecteren van een sample geplaatst op een bovenvlak van een scintillator, waarbij de werkwijze de stappen omvat van: het sturen van een bundel van geladen deeltjes naar het sample, waarbij een deel van de geladen deeltjes door het sample heengaan en bij de scintillator naar binnengaan, waar- bij tenminste een deel van de geladen deeltjes die bij de scintillator naar binnengaan wordt omgezet in fotonen, het verzamelen van tenminste een gedeelte van de fotonen door een optisch samenstel, waarbij dit optische sa- menstel is geconfigureerd om een focusvlak af te beelden op een fotondetector, en gekenmerkt door het gebruiken van de ruimtelijke karakteristieken van het verstrooien van de geladen deeltjes om zo de fotonen te verzamelen en te detecteren die van oor- sprong hoofdzakelijk afkomstig zijn van geladen deeltjes die in het sample verstrooid zijn.A method of inspecting a sample placed on a top surface of a scintillator, the method comprising the steps of: sending a beam of charged particles to the sample, with some of the charged particles passing through the sample and entering the scintillator, where at least a portion of the charged particles entering the scintillator are converted into photons, collecting at least a portion of the photons by an optical assembly, this optical assembly being configured to have a focal plane on a photon detector, and characterized by using the spatial characteristics of the scattering of the charged particles to collect and detect the photons originating mainly from charged particles scattered in the sample . 2. Werkwijze volgens conclusie 1, waarbij het fo- cusvlak van het optische samenstel geplaatst is op een eerste positie onder het bovenvlak van de scintillator waar het maximale signaal van het helder-veld beeld ontstaat, en waar- bij de werkwijze stappen omvat van: het positioneren van het focusvlak van het optische samenstel op een tweede positie, waarbij de tweede positie is geplaatst tussen de eerste positie en het bovenvlak van de scintillator, om zo fotonen te detecteren van de geladen deeltjes die in het sample zijn verstrooid,The method of claim 1, wherein the focus plane of the optical assembly is disposed at a first position below the top surface of the scintillator where the maximum signal of the bright field image is generated, and wherein the method comprises steps of: positioning the focal plane of the optical assembly at a second position, the second position being interposed between the first position and the top surface of the scintillator, so as to detect photons of the charged particles scattered in the sample, 3. Werkwijze volgens conclusie 1 of 2, waarbij het optische samenstel een confocale opstelling omvat die een ruimtelijke pin-hole gebruikt om licht afkomstig van buiten het focusvlak tenminste gedeeltelijk te blokkeren om de fo- tondetector te bereiken.The method of claim 1 or 2, wherein the optical assembly comprises a confocal arrangement that uses a spatial pin-hole to at least partially block light from outside the plane of focus to reach the photon detector. 4. Werkwijze volgens conclusie 1, 2 of 3, waarbij het optische samenstel een objectief-lens omvat voor het ver- zamelen van fotonen van de scintillator, waarbij de objec- tief-lens beweegbaar is in de richting naar of weg van het bovenvlak van de scintillator.The method of claim 1, 2 or 3, wherein the optical assembly comprises an objective lens for collecting photons from the scintillator, the objective lens being movable in the direction towards or away from the top surface of the the scintillator. 5. Werkwijze volgens één van de voorgaande conclu- sies, waarbij een afstandslaag geplaatst is tussen de scin- tillator en het sample, waarbij de afstandslaag een materiaal met een laag atoomummer omvat, bij voorkeur een materiaal met een atoomnummer onder 15, en meer bij voorkeur een mate- riaal met een atoomnummer onder 7.A method according to any one of the preceding claims, wherein a spacer layer is placed between the scintillator and the sample, the spacer layer comprising a material with a low atomic number, preferably a material with an atomic number below 15, and more at preferably a material with an atomic number below 7. 6. Werkwijze volgens conclusie 5, waarbij de af- standslaag borium of koolstof omvat.The method of claim 5, wherein the spacer layer comprises boron or carbon. 7. Werkwijze volgens conclusie 5 of 6, waarbij de laag een dikte heeft van minstens 50 nm, bij voorkeur ten- minste 100 nm.Method according to claim 5 or 6, wherein the layer has a thickness of at least 50 nm, preferably at least 100 nm. 8. Werkwijze volgens conclusie 5, 6 of 7, waarbij de afstandslaag is geplaatst op het bovenvlak van de scin- tillator, bij voorkeur waarbij de afstandslaag zo geconfigu- reerd is dat het sample gepositioneerd is op een vlak van de afstandslaag die van de scintillator afgekeerd is.A method according to claim 5, 6 or 7, wherein the spacer layer is placed on the top surface of the scintillator, preferably the spacer layer is configured such that the sample is positioned on a plane of the spacer layer that of the scintillator turned away. 9. Werkwijze volgens één van de voorgaande conclu- sies, waarbij de scintillator een verzadigingsdrempel omvat waarboven een toename in de intensiteit van de geladen deel- tjesbundel niet leidt tot een toename in omgezette fotonen,A method according to any one of the preceding claims, wherein the scintillator comprises a saturation threshold above which an increase in charged particle beam intensity does not lead to an increase in converted photons, waarbij de intensiteit van de geladen deeltjesbundel is ge- configureerd op een waarde die boven de verzadigingsdrempel van de scintillator ligt,wherein the charged particle beam intensity is configured to a value above the saturation threshold of the scintillator, 10. Werkwijze volgens conclusie 9, waarbij de in- tenstiteit van de geladen deeltjesbundel zo geselecteerd is dat de intensiteit van het gedeelte van de geladen deeltjes- bundel die door het sample heengaat een waarde heeft die boven de verzadigingsdrempel van de scintillator ligt.The method of claim 9, wherein the intensity of the charged particle beam is selected such that the intensity of the portion of the charged particle beam passing through the sample is above the saturation threshold of the scintillator. 11. Werkwijze volgens conclusie 9 of 10, waarbij de scintillator een materiaal met een lage verzadigingsdrem- pel omvat, in het bijzonder waarbij de scintillator zo ge- configureerd is dat de verzadigingsdrempel is bereikt bij maximaal 90% van de maximale intensiteit van de geladen deel- tjesbundel die gebruikt wordt bij het bestuderen van het sample.A method according to claim 9 or 10, wherein the scintillator comprises a material with a low saturation threshold, in particular wherein the scintillator is configured such that the saturation threshold is reached at a maximum of 90% of the maximum intensity of the charged portion - bundle used to study the sample. 12. Werkwijze volgens conclusie 11, waarbij de scintillator zo geconfigureerd is dat de verzadigingsdrempel bereikt is bij tenminste 5% van de maximale intensiteit van de geladen deeltjesgenerator.A method according to claim 11, wherein the scintillator is configured such that the saturation threshold is reached at at least 5% of the maximum intensity of the charged particle generator. 13. Werkwijze volgens conclusie 9, 10, 11 of 12, waarbij de scintillator een organische scintillator omvat die gebleekt is voordat deze gebruikt wordt in de werkwijze vol- gens de uitvinding.The method of claim 9, 10, 11 or 12, wherein the scintillator comprises an organic scintillator that has been bleached before it is used in the method of the invention. 14. Werkwijze volgens tenminste de inleiding van conclusie 1 of één van de conclusies 2 — 13, waarbij de scintillator tenminste in hoofdzaak transparant is voor licht in een golflengtebereik in het zichtbare spectrum, in het bijzonder in een golflengtebereik buiten de foto-excitatie en/of foto-emissie golflengtebanden van de scintillator , waarbij de werkwijze de stap omvat om het sample te observeren met een licht optische microscoop door het scintillator ma- teriaal heen.A method according to at least the preamble of claim 1 or one of claims 2 - 13, wherein the scintillator is at least substantially transparent to light in a wavelength range in the visible spectrum, in particular in a wavelength range outside the photo-excitation and / or photo-emission wavelength bands of the scintillator, the method comprising the step of observing the sample with a light optical microscope through the scintillator material. 15. Inrichting voor het onderzoeken van een sample, waarbij de inrichting omvat: een samplehouder voor het houden van het sample, een geladen-deeltjes-bundel-generator voor het ge- nereren van een geladen-deeltjes-bundel, een geladen -deeltjes-optisch-lenssysteem voor het sturen van voornoemd geladen-deeltjes-bundel naar de voor- noemd samplehouder, een scintillator die ingericht is om het sample tussen het geladen-deeltjes-optische-systeem en de scintil- lator te plaatsen, zodanig dat tenminste een deel van de geladen deeltjes die door het sample heengaan, de scintilla- tor ingaan, waarbij de scintillator is geconfigureerd voor het omzetten van tenminste een deel van de geladen deeltjes die de scintillator ingaan in fotonen, een licht-optisch-samenstel voor het verzamelen van tenminste een deel van de fotonen die opgewekt zijn in de scintillator, en voor het sturen van deze fotonen naar een fotondetector, waarbij de scintillator een verzadigingsdrempel om- vat waarboven een toename in de intensiteit van de geladen- deeltjes-bundel niet leidt tot een toename in omgezette fo- tonen, in het bijzonder waarbij de verzadigingsdrempel van de scintillator zodanig is geconfigureerd dat de verzadi- gingsdrempel is bereikt bij maximaal 90% van de maximale in- tensiteit van de geladen-deeltjes-bundel van de geladen-deel- tjes-bundel-generator.An apparatus for examining a sample, the apparatus comprising: a sample holder for holding the sample, a charged particle beam generator for generating a charged particle beam, a charged particle beam. optical lens system for directing said charged particle beam to the said sample holder, a scintillator arranged to place the sample between the charged particle optical system and the scintillator such that at least a part of the charged particles passing through the sample enter the scintillator, the scintillator configured to convert at least a portion of the charged particles entering the scintillator into photons, a light-optical assembly for collecting at least part of the photons generated in the scintillator, and for sending these photons to a photon detector, the scintillator having a saturation threshold above which an increase in the intensity of the charged particle beam does not lead to an increase in converted photons, especially where the saturation threshold of the scintillator is configured such that the saturation threshold is reached at a maximum of 90% of the maximum intensity of the charged particle beam of the charged particle beam generator. 16. Inrichting volgens conclusie 15, waarbij de scintillator zodanig is geconfigureerd dat de verzadigings- drempel is bereikt bij tenminste 5% van de maximale intensi- teit van de geladen-deeltjes-bundel van de geladen-deeltjes- bundel-generator.The device of claim 15, wherein the scintillator is configured such that the saturation threshold is reached at at least 5% of the maximum charged particle beam intensity of the charged particle beam generator. 17. Inrichting voor het onderzoeken van een sample, waarbij de inrichting omvat: een samplehouder voor het houden van het sample,17. Device for examining a sample, the device comprising: a sample holder for holding the sample, een geladen-deeltjes-bundel-generator voor het ge- nereren van een geladen-deeltjes-bundel, een geladen-deeltjes-optisch-lenssysteem voor het sturen van voornoemd geladen-deeltjes-bundel naar de voor- noemd samplehouder, een scintillator die ingericht is om het sample tussen het geladen-deeltjes-optische-systeem en de scintil- lator te plaatsen, zodanig dat tenminste een deel van de geladen deeltjes die door het sample heengaan, de scintilla- tor ingaan, waarbij de scintillator is geconfigureerd voor het omzetten van tenminste een deel van de geladen-deeltjes die de scintillator ingaan in fotonen, een licht-optisch-samenstel voor het verzamelen van tenminste een deel van de fotonen die gecreëerd zijn in de scintillator, en voor het sturen van deze fotonen naar een fotondetector, waarbij de scintillator een afstandslaag omvat, waarbij de afstandslaag geplaatst is op het bovenvlak van de scintillator, waarbij de afstandslaag een dikte heeft van ten minste 50 nm, bij voorkeur voor ten minste 100 nm.a charged particle beam generator for generating a charged particle beam, a charged particle optical lens system for directing said charged particle beam to the said sample holder, a scintillator arranged is to place the sample between the charged particle optical system and the scintillator such that at least a portion of the charged particles passing through the sample enter the scintillator, with the scintillator configured to convert of at least some of the charged particles entering the scintillator into photons, a light-optical assembly for collecting at least some of the photons created in the scintillator, and sending these photons to a photon detector, wherein the scintillator comprises a spacer layer, the spacer layer being disposed on the top surface of the scintillator, the spacer layer having a thickness of at least 50 nm, preferably for at least min ste 100 nm. 18. Inrichting volgens conclusie 17, waarbij de afstandslaag is geconfigureerd om het sample te plaatsen op een oppervlak van de afstandslaag die van de scintillator afgekeerd is.The device of claim 17, wherein the spacer is configured to place the sample on a surface of the spacer facing away from the scintillator. 19, Inrichting volgens één van de conclusies 15 - 18, waarbij de samplehouder voornoemd scintillator omvat.Apparatus according to any of claims 15-18, wherein the sample holder comprises said scintillator. 20. Inrichting volgens conclusie 19, waarbij de scintillator een bovenvlak omvat, waarbij het bovenvlak is geconfigureerd om het sample op het bovenvlak van de scin- tillator te plaatsen,The device of claim 19, wherein the scintillator comprises a top surface, the top surface configured to place the sample on the top surface of the scintillator, 21. Inrichting volgens één van de conclusies 15 - 20, waarbij de scintillator tenminste in hoofdzaak transpa- rant is voor licht in een golflengtebereik in het zichtbare spectrum, in het bijzonder in een golflengtebereik buiten de foto-rexcitatie en/of foto-emissie golflengtebanden van de scintillator.Apparatus according to any of claims 15-20, wherein the scintillator is at least substantially transparent to light in a wavelength range in the visible spectrum, in particular in a wavelength range outside the photo-re-excitation and / or photo-emission wavelength bands of the scintillator. 22. Inrichting voor het onderzoeken van een sample, waarbij de inrichting omvat: een samplehouder voor het houden van het sample, een geladen-deeltjes-bundel-generator voor het ge- nereren van een geladen-deeltjes-bundel, een geladen-deeltjes-optisch-lenssysteem voor het sturen van voornoemd geladen-deeltjes-bundel naar voornoemd samplehouder, een scintillator die ingericht is om het sample tussen het geladen-deeltjes-optische-lenssysteem en de scin- tillator te plaatsen, zodanig dat tenminste een deel van de geladen deeltjes die door het sample heengaan, de scintilla- tor ingaan, waarbij de scintillator is geconfigureerd voor het omzetten van tenminste een deel van de geladen deeltjes die de scintillator ingaan in fotonen, een licht-optisch-samenstel voor het verzamelen van tenminste een deel van de fotonen die opgewekt zijn in de scintillator, en voor het sturen van deze fotonen naar een fotondetector, waarbij de scintillator tenminste in hoofdzaak transparant is voor licht in een golflengtebereik van het zichtbare spectrum, in het bijzonder in een golflengtebereik buiten foto-excitatie en/of foto-emissie golflengtebanden van de scintillator.22. Apparatus for examining a sample, the apparatus comprising: a sample holder for holding the sample, a charged particle beam generator for generating a charged particle beam, a charged particle beam generator. optical lens system for directing said charged particle beam to said sample holder, a scintillator arranged to place the sample between the charged particle optical lens system and the scintillator, such that at least a part of the charged particle particles passing through the sample enter the scintillator, the scintillator configured to convert at least a portion of the charged particles entering the scintillator into photons, a light-optical assembly for collecting at least a portion of the photons generated in the scintillator, and for sending these photons to a photon detector, the scintillator being at least substantially transparent to light in a go Length range of the visible spectrum, especially in a wavelength range outside photo-excitation and / or photo-emission wavelength bands of the scintillator. 23. Inrichting volgens conclusie 21 of 22, waarbij de scintillator een materiaal met een smalle foto-excitatie en/of een foto-emissie golflengteband omvat, in het bijzonder waarbij de foto-excitatie golflengteband smaller is dan 100 nm, bij voorkeur smaller dan 50 nm, en meer bij voorkeur smaller dan 20 nm.23. Device according to claim 21 or 22, wherein the scintillator comprises a material with a narrow photo-excitation and / or a photo-emission wavelength band, in particular wherein the photo-excitation wavelength band is smaller than 100 nm, preferably smaller than 50 nm. nm, and more preferably less than 20 nm.
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