CN219285073U

CN219285073U - Photoelectric detector

Info

Publication number: CN219285073U
Application number: CN202223536046.4U
Authority: CN
Inventors: 何伟; 胡继闯; 陈志明; 张景龙; 张子豪; 牛辉
Original assignee: Nak Microbeam Beijing Co ltd
Current assignee: Nak Microbeam Beijing Co ltd
Priority date: 2022-12-27
Filing date: 2022-12-27
Publication date: 2023-06-30
Anticipated expiration: 2032-12-27

Abstract

The utility model relates to a photoelectric detector, which belongs to the technical field of photoelectric detectors, can realize the simultaneous detection of cathode fluorescent signals and electronic signals, and greatly improves the collection efficiency of fluorescent signals; the photoelectric detector comprises an electron source, an accelerating electrode, an objective lens, a reflection grating, a CL fluorescence detector and a BSE detector; the electron source is arranged in the center of the top to generate an electron beam; the accelerating electrode is arranged below the electron source; the objective lens is arranged below the accelerating electrode; the BSE detector is arranged below the objective lens; the sample to be scanned is arranged at the bottommost part; the accelerating electrode, the objective lens and the BSE detector are coaxially arranged, and the electron beam sequentially passes through the accelerating electrode, the objective lens and the BSE detector and irradiates the surface of the sample; the BSE detector receives the backscattered electrons reflected by the sample; the reflection grating and the CL fluorescence detector are both arranged on the periphery of the BSE detector, and photons transmitted from the upper surface of the sample are reflected to the CL fluorescence detector.

Description

Photoelectric detector

Technical Field

The utility model relates to the technical field of photoelectric detectors, in particular to a photoelectric detector.

Background

The cathode fluorescence spectrum analysis technique is a technique of irradiating ultraviolet, visible or infrared light by causing electron transition in a band gap or a defect position after bombarding a sample material with an electron beam. When the cathode fluorescence spectrum (CL) is combined with an electron microscope, electron beam spots are extremely small, so that the nm-level spatial resolution can be realized, and the method has great advantages for researching the sub-nanometer-level defect distribution, carrier dynamics, interface contrast analysis, stress strain and energy band structure in the material. Thus, the physical properties of the material itself can be analyzed and reflected by the cathode fluorescence spectrum (CL).

Detection of electron beam excited cathode fluorescent signals and simultaneous scanning electron microscope imaging are currently difficult, and if simultaneous imaging is performed, defects on the surface of a sample are easier to detect. Currently, the cathode fluorescence detection is realized by a side cathode fluorescence detector, and the defects of the mode include:

1. the side type cathode fluorescence detector has smaller space angle and low collection efficiency;

2. the side type cathode fluorescence detector occupies a large space, and shields paths of reflected electrons such as secondary electrons, back scattered electrons and the like, so that a scanning electron microscope cannot detect cathode fluorescence and signal electrons at the same time;

3. the traditional use mode is flat insertion, and the collection efficiency is only 20%;

4. the flat side insertion mode used in chinese patent CN113675060a, but uses a PD mirror as a reflecting mirror, mainly two types of ellipsoidal mirrors and edge polishing mirrors, which has the disadvantages of heavy weight, difficult polishing, large installation difficulty, large occupied space, single fixed angle and insufficient reflection efficiency.

Accordingly, there is a need to develop a photodetector that addresses the deficiencies of the prior art to solve or mitigate one or more of the problems described above.

Disclosure of Invention

In view of the above, the present utility model provides a photodetector, which can realize simultaneous detection of a cathode fluorescent signal and an electronic signal, and greatly improve the collection efficiency of the fluorescent signal.

The utility model provides a photoelectric detector, which comprises an electron source, an accelerating electrode, an objective lens, a reflection grating, a CL fluorescence detector and a BSE detector;

the electron source is arranged in the center of the top and generates a vertical electron beam; the accelerating electrode is arranged below the electron source; the objective lens is arranged below the accelerating electrode; the BSE detector is arranged below the objective lens; the sample to be scanned is arranged at the bottommost part;

the accelerating electrode, the objective lens and the BSE detector are coaxially arranged, and the electron beam sequentially passes through the accelerating electrode, the objective lens and the BSE detector and irradiates the surface of the sample;

the BSE detector receives the backscattered electrons reflected by the sample;

the reflection grating and the CL fluorescence detector are both arranged on the periphery of the BSE detector, and photons transmitted from the upper surface of the sample are reflected to the CL fluorescence detector.

In aspects and any one of the possible implementations described above, there is further provided an implementation in which the reflection grating is disposed below the objective lens and above the BSE detector; the CL fluorescence detector is arranged below the reflection grating.

Aspects and any one of the possible implementations as set forth above, further providing an implementation in which the reflection grating is disposed below the BSE detector, above the sample; the CL fluorescence detector is arranged above the reflection grating.

In the aspects and any possible implementation manner described above, there is further provided an implementation manner, where the reflecting surface of the reflection grating is provided with a plurality of arc surfaces.

In the aspect and any possible implementation manner described above, there is further provided an implementation manner, where the arc surface of the reflection grating is covered with SiO ₂ And (3) a film.

In the aspect and any possible implementation manner as described above, there is further provided an implementation manner, where a fluorescent reflective film is covered at a lower end of the BSE detector;

the upper surface of the sample, the fluorescent reflecting film and the CL fluorescence detector are sequentially and optically connected.

In the aspect and any possible implementation manner described above, there is further provided an implementation manner, where the fluorescent reflective film is a metal film, an aluminum film or a silver film.

In aspects and any one of the possible implementations as described above, there is further provided an implementation, the CL fluorescence detector is a CL color fluorescence detector; the CL color fluorescence detector comprises a plurality of PMT electron multipliers and a color filter arranged at the front end of the PMT electron multipliers.

In the aspect and any possible implementation manner described above, there is further provided an implementation manner, the reflection grating is annular, and a longitudinal section of the annular is triangular or plate-like.

In the aspect and any possible implementation manner described above, there is further provided an implementation manner, where an included angle between a reflective surface of the reflection grating and a horizontal plane is not more than 60 °.

Compared with the prior art, one of the technical schemes has the following advantages or beneficial effects: the setting angle of the reflection grating can be adjusted according to the situation, and the reflection grating is provided with a plurality of arc-shaped reflecting surfaces, so that photons with different angles around a sample can be reflected to the detector, the photons can be collected in a large range, the collection efficiency of the photoelectric detector is improved, and the collection efficiency can reach 85%.

Of course, it is not necessary for any of the products embodying the utility model to achieve all of the technical effects described above at the same time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic overall structure of a first embodiment of a photodetector of the present utility model;

FIG. 2 is a schematic overall structure of a second embodiment of the photodetector of the present utility model;

FIG. 3 is a schematic overall structure of a third embodiment of the photodetector of the present utility model;

FIG. 4 is a schematic overall structure of a fourth embodiment of the photodetector of the present utility model;

FIG. 5 is a schematic diagram of several reflection grating structures provided by the present utility model;

FIG. 6 is a top view of a photodetector provided by one embodiment of the utility model;

fig. 7 is a top view of a photodetector according to another embodiment of the present utility model.

Wherein, in the figure:

1. an electron source; 2. an accelerating electrode; 3. an electron beam; 4. an objective lens; 5. a reflection grating; 6. CL fluorescence detector; 7. a BSE detector; 8. a sample; 9.CL color fluorescence detector; 10. a color filter; 11. and a deflection device.

Detailed Description

For a better understanding of the technical solution of the present utility model, the following detailed description of the embodiments of the present utility model refers to the accompanying drawings.

It should be understood that the described embodiments are merely some, but not all, embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In order to overcome the defects of the prior art, the utility model provides the photoelectric detector, wherein a plurality of gratings which are polished into arc shapes are combined into the reflection grating with adjustable angles, photons with different angles around a sample are reflected onto the photon detector by the reflection grating, so that the photons are collected in a large range, and the collection efficiency of the photoelectric detector is very high.

The photodetector includes:

an electron source for generating an electron beam;

an acceleration electrode for accelerating an electron beam emitted from the electron source;

an objective lens for focusing the electron beam;

a Back Scattered Electron (BSE) detector for receiving electrons generated by the electron beam acting on the sample;

a CL fluorescence detector for receiving photons generated by the electron beam acting on the sample;

and the reflection grating is arranged below the Back Scattered Electron (BSE) detector and above the CL fluorescence detector, and can also be arranged below the Back Scattered Electron (BSE) detector and the CL fluorescence detector and used for reflecting photons generated on the sample to the CL fluorescence detector.

The CL fluorescence detector may be a CL color fluorescence detector for detecting light of a specific color, thereby obtaining CL of a color. The CL color fluorescence detector can be realized by adopting a mode of assembling a color filter at the front end of the CL fluorescence detector, filtering out other electrons and making the CL color fluorescence detector into color CL. The CL fluorescence detector may also be replaced by other detectors, such as a secondary electron detector.

The reflection grating is annular (the overlook structure of the reflection grating is shown in fig. 6 and 7), a plurality of reflection cambered surfaces are arranged on the reflection surface, and the reflection cambered surfaces can be obtained through polishing or etching. The reflecting cambered surfaces of the reflecting gratings are covered with SiO ₂ And the film is used for intercepting electron reflection photons, so that electrons cannot penetrate through the oxide layer and no new electronic signal is generated. The reflection grating can have a certain thickness, such as three reflection grating structures shown in fig. 5, wherein the upper group and the lower group are respectively reflection grating structures with certain thickness and triangular longitudinal sections; the middle is a plate-like reflection grating structure without thickness. The reflecting surface of the reflection grating may be a plurality of cambered surfaces as described above, or may be stepped as shown in the bottom group of fig. 5. The whole thickness of the reflection grating can be determined according to actual conditions, can be made to be thin, occupies small space, is easy to operate, and is not easy to collide with other detectors. The included angle between the reflecting surface of the reflection grating and the horizontal line can be determined according to practical conditions and can be any angle. When in use, the reflection grating is inserted in the sample, the angle is adjustable, and collision with the sample is avoided when the reflection grating is close. An included angle of not more than 60 degrees is formed between the outer side direction of the whole reflection surface of the reflection grating and the horizontal plane.

The reflection grating inclined reflection structure with a plurality of reflection cambered surfaces can reflect photons with different angles to the CL fluorescence detector, so that the collection efficiency is increased.

Example 1:

as shown in fig. 1 and 2, two types of photodetectors provided in this embodiment are provided.

In this embodiment, the electron source 1 is arranged centrally on top, generating a vertically directed electron beam 3. The accelerating electrode 2 is arranged below the electron source 1. The objective lens 4 is provided below the accelerating electrode 2. The BSE detector 7 is disposed below the objective lens 4. Sample 8 was placed in the very bottom centre. The accelerating electrode 2, the objective lens 4 and the BSE detector 7 are coaxially arranged, and the electron beam 3 sequentially passes through the accelerating electrode 2, the objective lens 4 and the BSE detector 7 and irradiates the surface of the sample 8, and the back-scattered electrons reflected by the sample 8 are received by the BSE detector 7 to realize back-scattered electron detection.

The periphery of the BSE detector 7 is provided with a reflection grating 5, and a CL fluorescence detector 6 is arranged below the reflection grating 5. The reflection grating 5 reflects photons generated on the sample 8 to the CL fluorescence detector 6 for detection by the CL fluorescence detector 6.

The BSE detector 7 is circular, the CL fluorescence detector 6 is circular, and the reflection grating 5 is circular. The BSE detector 7 and the reflection grating 5 and the CL fluorescence detector 6 are coaxial, and the axis is the center of the main optical axis of the electron beam generated by the electron source 1.

According to the embodiment, photons around the sample 8 are reflected to the CL fluorescence detector 6 by arranging the reflection grating 5 consisting of a plurality of cambered surface circular rings above the periphery of the sample, so that the photons are collected in a large range, and the receiving efficiency of the CL fluorescence detector 6 is high. And SiO is covered on the lower surface of the reflection grating ₂ The film intercepts electrons, cannot penetrate through the oxide layer, and cannot generate new electronic signals, so that the quality of received signals is affected. The CL fluorescence detector 6 is annular, the CL fluorescence detector 6 can be annular formed by connecting a plurality of sub-photon detectors, the sub-photon detectors are sequentially connected to form the annular CL fluorescence detector 6 with a through hole in the middle, and the through hole in the middle is used for the electron beam to pass through so as to irradiate the sample.

In this embodiment, the CL fluorescence detector 6 is located between the electron source 1 and the sample 8, specifically, the CL fluorescence detector 6 is located below the BSE detector 7 and above the sample, and the CL fluorescence detector 6 is horizontally disposed and is disposed below the reflection grating 5, so as to just receive the photons reflected by the reflection grating 5 to realize detection. The reflection grating 5 in fig. 1 has a structure having a cross section like a triangle and having a plurality of circular arc-shaped reflection surfaces, and the reflection grating 5 in fig. 2 has a structure like a plate and having a plurality of circular arc-shaped reflection surfaces. When the cross section is the reflection grating preparation of class triangle-shaped, the reflection grating body of cuboid is polished out an inclined plane with the polisher earlier, then polishes out two at least arcwall faces on this inclined plane, and the arcwall face is whole to be annular, and the arcwall face can reflect the photon that each angle was incident to increase CL fluorescence detector 6 and collect the photon's scope, improve receiving efficiency.

The electron source 1 is divided into a field emission source and a thermal emission source, the field emission source is divided into a thermal field and a cold field, and the thermal emission source is divided into tungsten filament, lanthanum hexaboride and the like. The electron source 1 in the present utility model may be any electron source 1 for generating an electron beam. The electron beam 3 acts on the sample 8 to generate secondary electrons, back scattered electrons, auger electrons, cathode fluorescence, X-rays, and the like. The CL fluorescence detector 6 is configured to receive cathode fluorescence generated by the electron beam acting on the sample.

As a preferred embodiment, the lower end of the BSE detector 7 is covered with a thin film capable of reflecting fluorescence, such as a metal film, an aluminum film, a silver film, etc., and photons incident on the lower surface of the BSE detector 7 are reflected to the CL fluorescence detector 6 through the above-mentioned reflective film, thereby increasing the receiving efficiency of the CL fluorescence detector 6.

The accelerating electrode 2 is an anode, and is used for forming an electric field along the emission direction of the electron beam so as to increase the movement speed of the electron beam. The objective lens 4 is used for controlling the beam size and the electron beam advancing direction of the electron beam emitted from the electron source 1. The objective lens 4 focuses the electron beam onto the sample and scans it. The objective lens can be a magnetic lens, an electric lens or an electromagnetic compound lens.

The photodetector of the present utility model is further provided with a deflection device 11 for changing the direction of movement of the electron beam before it is incident on the sample, and capable of generating a scanning field in an arbitrary deflection direction. The deflection means 11 may be magnetic deflection means or electrical deflection means.

Example 2:

this embodiment differs from embodiment 1 in the arrangement positions of the CL fluorescence detector 6 and the reflection grating 5. In this embodiment, as shown in fig. 3, the CL fluorescence detector 6 is located below the objective lens 4 and above the BSE detector 7, and the CL fluorescence detector 6 is horizontally in a positional relationship with the BSE detector 7: the CL fluorescence detector 6 is located outside the BSE detector 7. The reflection grating 5 is positioned below the CL fluorescence detector and the BSE detector 7, and an included angle of not more than 60 degrees is formed between the whole reflection surface and the horizontal plane.

Example 3:

this embodiment differs from embodiment 1 in that the CL fluorescence detector 6 is replaced with a CL color fluorescence detector 9. The CL color fluorescence detector 9 is implemented by providing a color filter 10 at the front end of the existing PMT electron multiplier, as shown in fig. 4. Because the front end of the PMT electron multiplier is provided with a layer of glass, the effect of filtering electrons can be achieved, only photons are collected, and the collection quality of fluorescent images is improved. In this embodiment, the number of PMT electron multipliers may be plural, and the color filters 10 at the front ends of different PMT electron multipliers are of different colors, so that the plurality of PMT electron multipliers can respectively detect light of different colors, thereby increasing the collection efficiency and improving the image resolution.

The above describes a photodetector provided in the embodiments of the present application in detail. The above description of embodiments is only for aiding in understanding the method of the present application and its core ideas; meanwhile, as those skilled in the art will have modifications in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a product or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such product or system. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a commodity or system comprising such elements. By "substantially" is meant that within an acceptable error range, a person skilled in the art is able to solve the technical problem within a certain error range, substantially achieving the technical effect.

The terminology used in the embodiments of the utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. In the present application, the terms "upper", "lower", "left", "right", "inner", "outer", "horizontal", "vertical", and the like indicate an azimuth or a positional relationship based on that shown in the drawings. In addition to the above terms may be used to denote orientation or positional relationships, other meanings may be used, such as the term "upper" may also be used in some cases to denote some sort of attachment or connection. The specific meaning of these terms in this application will be understood by those of ordinary skill in the art as appropriate. The term "and/or" as used herein is merely one association relationship describing the associated object, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

Claims

1. A photodetector, wherein the photodetector comprises an electron source, an accelerating electrode, an objective lens, a reflection grating, a CL fluorescence detector and a BSE detector;

the BSE detector receives the backscattered electrons reflected by the sample;

2. The photodetector of claim 1, wherein the reflection grating is disposed below the objective lens and above the BSE detector; the CL fluorescence detector is arranged below the reflection grating.

3. The photodetector of claim 1, wherein the reflection grating is disposed below the BSE detector, above the sample; the CL fluorescence detector is arranged above the reflection grating.

4. The photodetector of claim 1 wherein the reflective surface of the reflective grating is provided with arcuate surfaces.

5. The photodetector of claim 4, wherein said reflective grating arcuate surface is coated with SiO ₂ And (3) a film.

6. The photodetector of claim 1, wherein a lower end of the BSE detector is covered with a fluorescent reflective film;

7. The photodetector of claim 6 wherein said fluorescent reflective film is a metal film, an aluminum film or a silver film.

8. The photodetector of claim 1, wherein the CL fluorescence detector is a CL color fluorescence detector; the CL color fluorescence detector comprises a plurality of PMT electron multipliers and a color filter arranged at the front end of the PMT electron multipliers.

9. The photodetector of claim 1 wherein the reflective grating is annular, the longitudinal cross-section of the annular being triangular-like or plate-like.

10. The photodetector of claim 4, wherein the angle between the reflective surface of the reflective grating and the horizontal is no more than 60 °.