阅读说明：本技术 一种用于扫描电镜观察背散射电子像的装置和方法 (Device and method for observing backscattered electron image by scanning electron microscope ) 是由 周固 李崧 于 2020-06-16 设计创作，主要内容包括：本发明属于材料微观测试领域,目的在于提供一个使用扫描电镜样品室内己有的E.T.检测器观察背散射电子像的装置和方法。该装置由高角度样品预倾斜放置面和背散射电子反射板组成。与原有的用扫描电镜E.T.检测器接收背散射电子成像的技术相比可以收到样品更多的背散射电子,提高检测效率,得到更好原子序数分辨的背散射电子像。本发明的观察装置具有结构简单,性能可靠,便于操作的特点,可以方便地对各种材料样品进行背散射电子图像观察,还可以记录材料的微观成分相,具有直观的检测特性,便于结合X射线能谱选点和面分布进一步对应分析,为新材料的检测和开发提供可靠的性能参数。(The invention belongs to the field of microscopic testing of materials, and aims to provide a device and a method for observing a backscattered electron image by using an existing E.T. detector in a scanning electron microscope sample chamber. The device consists of a pre-inclined placing surface of a high-angle sample and a back scattering electron reflection plate. Compared with the original technology of receiving back scattered electron imaging by using a scanning electron microscope E.T. detector, more back scattered electrons of a sample can be received, the detection efficiency is improved, and a back scattered electron image with better atomic number resolution is obtained. The observation device has the characteristics of simple structure, reliable performance and convenient operation, can conveniently observe back scattering electron images of various material samples, can record the micro component phase of the material, has intuitive detection characteristics, is convenient to combine X-ray energy spectrum point selection and surface distribution for further corresponding analysis, and provides reliable performance parameters for the detection and development of new materials.)

1. The device for observing the backscattered electron image by the scanning electron microscope is characterized by consisting of a pre-inclined placing surface of a high-angle sample and a backscattered electron reflecting plate.

2. The apparatus for scanning electron microscopy observation of backscattered electron images according to claim 1, wherein the sample is tilted at high angle and the electron beam of the scanning electron microscopy is incident at high angle on the sample.

3. The apparatus for sem observation of backscattered electron images according to claim 1, wherein the sample is oriented towards the e.t. detector in the sem chamber and the backscattered electrons exiting from the sample are guaranteed to enter the e.t. detector at high angles to the reflector plate and the backscattered electrons reflected by the reflector plate.

4. The apparatus for scanning electron microscopy observation of a backscattered electron image according to claim 1, wherein the high angle incident backscattered electron reflection plate is used multiple times or multiple orientations to improve the efficiency of receiving backscattered electrons.

5. The measurement method of an apparatus for scanning electron microscopy for observing an image of backscattered electrons according to claim 1, wherein the position and orientation of the sample and the reflecting plate are chosen appropriately to obtain the maximum detection efficiency for collecting backscattered electrons.

6. The measurement method of an apparatus for sem observation of backscattered electron images according to claim 1, carried out in e.t. detector imaging mode inside sem specimen chamber, wherein scintillator high voltage of e.t. detector is turned off during the test, and backscattered electron image is received.

7. The method of claim 1, wherein the back-scattered electrons are collected and detected only when the E.T. detector collects a bias voltage selected from a range of negative bias voltages of 50V to 100V, and mixed images of the back-scattered electrons and the secondary electrons in different proportions are obtained when the E.T. detector collects any bias voltage selected from a range of negative bias voltages of 50V to 100V to a range of positive bias voltages of +250V to + 300V.

The technical field is as follows:

the invention relates to a device and a method for observing back scattering electron images of various solid materials in a scanning electron microscope, which can distinguish different phases of the solid materials through the atomic number contrast of the back scattering electron images and directly correspond the atomic number contrast and the micro-morphology of the materials, and belongs to the field of micro-testing of the materials.

Background

There are many methods for detecting backscattered electrons on a scanning electron microscope and imaging, and a backscattered electron detector is usually required to be equipped for the scanning electron microscope, and a scintillator-photomultiplier detector configured for detecting secondary electrons, which is already in a sample chamber of the scanning electron microscope, can also be used for imaging.

The scintillator-photomultiplier detector is also known as the Everhart Thornley detector and is hereinafter referred to as the e.t. detector.

The original technology of realizing the back scattering electron image by using the E.T. detector in the scanning electron microscope sample chamber is that the sample is flatly placed and not inclined under the general condition, at the moment, the back scattering electrons are less produced, the emergent angle of the back scattering electrons is small, and the solid angle effectively received by the E.T. detector is small, so the signal-to-noise ratio of the formed back scattering electron image is poor, and some surface information is easy to lose. Its advantages are high effect to secondary electron detector, and low cost.

The e.t. detector is mainly used for detecting secondary electrons. However, switching off the scintillator high voltage of the e.t. detector prevents secondary electron signals from entering, i.e. the e.t. detector receives essentially backscattered electrons in case of scintillator high voltage switching off. When the positive bias (+250V to +300V) of the collector of the e.t. detector is changed to the negative bias (50V to 100V), the low-energy secondary electrons are repelled by the negative electric field and cannot enter the detector, and only the high-energy backscattered electrons can be collected and detected.

The biasing effect of the e.t. detector collector is negligible for backscattered electrons, regardless of whether the bias of the e.t. detector collector is positive or negative. However, the bias effect of the e.t. detector collector at high scintillator voltage turn-on for secondary electrons cannot be neglected, so that varying the bias can yield different proportions of backscattered and secondary electron mixed images.

The sample tilt angle θ (the angle between the incident direction of the electron beam and the normal direction of the sample surface) also has an effect on the yield η of backscattered electrons. When the sample is tilted, the backscattered electron angular distribution is significantly skewed forward, forming a forward peak, with an emission extremum resembling the reflection. The yield η of backscattered electrons increases even close to 1 when the angle θ is greater than 50 °. The low detection angle is chosen to be most efficient for collecting backscattered electrons.

However, the e.t. detector is generally not directed directly towards the forward peak of the backscattered electrons and the efficiency of detection of backscattered electrons is still not high.

Disclosure of Invention

The invention aims to provide a device and a method for receiving a backscattered electron image by using an E.T. detector in a scanning electron microscope sample chamber, and the backscattered electron detection efficiency is improved.

In order to achieve the above object, the present invention provides a back-scattered electron image device for scanning electron microscope observation, as shown in fig. 1, characterized in that the device is composed of a pre-tilted sample placement surface (2) and a reflecting plate (7).

In order to improve the receiving rate of the backscattered electrons, the invention utilizes the principle that the backscattered electrons form a forward peak when the electron beam obliquely enters relative to a sample at a high angle and have an emission extreme value similar to reflection. The technical scheme is as follows:

and a reflecting plate (7) for placing the backscattered electrons is designed between the sample (3) of the scanning electron microscope and the E.T. detector (8) in the sample chamber. The backscattered electrons (5) excited by the scanning electron microscope electron beam (4) high-angle incident sample (3) are received by the E.T. detector (8) through the high-angle incident reflecting plate (7), and the positions and angles of the sample and the reflecting plate are reasonably selected to collect the backscattered electrons, so that the maximum detection efficiency is obtained.

Compared with the prior art, the invention has the following advantages and prominent effects: the invention arranges a reflecting plate at a proper position between the sample and the E.T. detector, the reflecting plate reflects the back scattering signal electrons with high angle incidence to the E.T. detector, and the back scattering electron collection with a proper detection angle has maximum detection efficiency. The observation device for the backscattered electron image of the scanning electron microscope has reasonable application principle, simple structure and reliable performance, and utilizes the existing E.T. secondary electron detector in the scanning electron microscope to observe the backscattered electron image without changing the electron optical system and adding the detector. Has the characteristic of simple and convenient operation. The application range is wide, various material samples can be observed, microscopic component phases of the materials can be recorded, different component areas in a mixture sample can be identified, and the visual detection characteristic is realized. The element identification and positioning can be effectively carried out by matching with the X-ray micro-area analysis, the X-ray energy spectrum surface distribution analysis is further convenient to carry out, and reliable performance parameters are provided for the detection and development of new materials.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic structural diagram and a test experiment optical path of a device for observing backscattered electron images by a scanning electron microscope according to the present invention. In the figure, (1) is a front view of the structure of embodiment 1 of the device;

FIG. 2 is a top view of the structure of example 1 of the present invention;

FIG. 3 is a front view and a schematic view of a test light path of the structure of example 2 of the present invention for observing a cross-sectional sample;

FIG. 4 is a top view of the structure of example 3 of the present invention;

fig. 5 is a backscattered electron image of a backscattered electron image standard sample obtained in example 1 of the present invention, which is taken by using an S-4800 cold field emission scanning electron microscope of hitachi corporation, when the scintillator high voltage of the e.t. detector is turned off, and 2 copper-zinc alloy phases having an average atomic number difference of 0.06 can be resolved from the backscattered electron image of fig. 5;

in the figure, 1 is a sample holder of the example, 2 is a pre-tilt mounting surface of the sample, 3 is the sample, 4 is an incident electron beam, 5 is backscattered electrons, 6 is backscattered electrons reflected by a reflector plate, 7 is the reflector plate, and 8 is an e.t. detector.

Detailed Description

Preferred embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

Example 1

The invention discloses a device and a method for observing a back scattering electron image by a scanning electron microscope, which are shown in figure 1: the device comprises a sample pre-inclination placing surface (2) on a sample seat (1) and a reflecting plate (7). Fig. 2 is a top view thereof.

The working process of the device is as follows:

in an imaging mode of an E.T. detector (8) in a scanning electron microscope sample chamber, the method comprises the steps of 1) adhering and fixing a sample (3) on a central position (2) of a sample seat (1), wherein the upper surface and the lower surface of the sample are required to be parallel and flat, so that the sample (3) keeps a high-angle pre-tilt and is in a state to be detected; 2) and putting the sample holder (1) loaded with the sample (3) and the back scattered electron reflection plate (7) into a scanning electron microscope sample vacuum chamber, and rotating the sample holder (1) to enable the sample (3) to be detected to be right opposite to the direction of the E.T. detector (8). And ensures that the backscattered electrons (5) enter the reflecting plate (7) at a high angle and the backscattered electrons (6) reflected by the reflecting plate enter the E.T. detector (8) in an optimal state. Adjusting imaging parameters of a scanning electron microscope to enable the sample to be in a clear state; 3) turn off the scintillator high voltage of the e.t. detector (8), when the e.t. detector (8) receives substantially backscattered electrons. The backscattered electron image of the sample (3) is recorded by a scanning electron microscope imaging system.

Example 2

The present embodiment 2 is different from embodiment 1 in that a sample holder (1) as shown in fig. 3 in a front view can be used in order to observe a cross section of a thin sample, facilitate adhesion of the thin sample, and make an image more stable. The scanning electron beam (4) of the electron microscope is incident on the cross section of the sample (3) at a high angle, the back scattering electrons emitted by the scanning electron beam are incident on the reflecting plate (7) at a high angle, and the back scattering electrons (6) emitted again enter the E.T. detector (8) for imaging.

Example 3

This embodiment 3 is different from embodiments 1 and 2 in that a square or rectangular sample holder as shown in fig. 4 in a plan view can be adopted for the convenience of mounting and observing a plurality of samples. Fig. 4 can be combined with fig. 1 and 3, respectively, and when fig. 4 is combined with fig. 3, the sample is stuck to the right side of (2) in fig. 4.

In the above embodiment test of the invention, the e.t. detector (8) collects the bias voltage to select the negative bias voltage (50V-100V), only collects and detects the backscattered electrons, or selects any bias voltage between the negative bias voltage (50V-100V) and the positive bias voltage (+ 250V- +300V), so as to obtain the mixed image of the backscattered electrons and the secondary electrons with different proportions.

So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.