CN114002251B - Characterization method of nanoscale double-layer material based on scanning electron microscope - Google Patents
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- 238000012512 characterization method Methods 0.000 title claims abstract description 47
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- 238000004364 calculation method Methods 0.000 claims description 23
- 238000012360 testing method Methods 0.000 claims description 19
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- 238000012216 screening Methods 0.000 claims description 4
- 239000010949 copper Substances 0.000 description 46
- 229910052802 copper Inorganic materials 0.000 description 24
- 229910021392 nanocarbon Inorganic materials 0.000 description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 11
- 229910052799 carbon Inorganic materials 0.000 description 11
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
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- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000001350 scanning transmission electron microscopy Methods 0.000 description 1
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N23/225—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion
- G01N23/2251—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion using incident electron beams, e.g. scanning electron microscopy [SEM]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/07—Investigating materials by wave or particle radiation secondary emission
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/10—Different kinds of radiation or particles
- G01N2223/102—Different kinds of radiation or particles beta or electrons
Abstract
The invention discloses a characterization method of a nanoscale double-layer material based on a scanning electron microscope, and belongs to the field of microscopic characterization of scanning electron microscopes. The method uses Monte Carlo simulation to simulate and calculate the interaction between the incident electron and the nano-scale double-layer material to be tested, and obtains the excitation depth of the back scattering electron; and carrying out scanning electron microscope characterization observation on the experimental sample to be tested, and obtaining a back scattering electron image under the corresponding voltage condition. The method provided by the invention can be directly applied to microcosmic characterization of the nano-scale double-layer material by any scanning electron microscope, is simple to operate and high in repeatability, and can provide technical support for microcosmic characterization of the nano-scale double-layer material.
Description
Technical Field
The invention belongs to the field of microscopic characterization of scanning electron microscopes, and particularly relates to a characterization method of a nanoscale double-layer material based on a scanning electron microscope.
Background
The scanning electron microscope (Scanning Electron Microscope; SEM) is one of important characterization means of material micro-area element analysis, and has the advantages of high image resolution (3 nm-0.6 nm), large depth of field (10 times of an optical electron microscope), nondestructive analysis, simple sample preparation and the like, and the sample can be a natural surface, a fracture, a block, a reflective light sheet, a light-transmitting light sheet and the like.
Secondary Electron (SE) imaging and Back Scattered Electron (BSE) imaging are the two most common imaging modes in scanning electron microscopes. Secondary electron imaging is used for sample topography characterization, and contrast in the image is mainly due to sample surface topography differences. Back-scattered electron imaging is used for differential characterization of sample surface composition, and contrast in images is mainly due to differences in elemental content in microscopic phase compositions.
The Monte Carlo simulation calculation is widely applied to the development of advanced electron microscope characterization technology, and can carry out feasibility analysis and result prediction for experiments through theoretical calculation of interaction between high-energy electron beams and solid samples, thereby providing theoretical support for actual characterization detection work.
Microscopic characterization of nanobilayer materials requires characterization means with resolution up to the nanometer level, typically by scanning electron microscopy and transmission electron microscopy. The existing characterization method based on the scanning electron microscope is only limited to characterization of the section or the section of the double-layer sample, and the surface characteristics of each layer of sample cannot be observed. Secondly, the characterization method based on the transmission electron microscope has the limiting factors of high sample preparation difficulty, complex operation, limited observation area and the like, so that the detection cost of related experiments is high, the efficiency is low, and the method cannot be widely used in industrial production.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a characterization method of a nanoscale double-layer material based on a scanning electron microscope, which combines a conventional scanning electron microscope back-scattering electron characterization technology with Monte Carlo simulation calculation, realizes the layer-by-layer characterization of the nanoscale double-layer material by changing voltage parameters, and calculates the thickness of each layer of material.
The technical scheme of the invention is as follows:
a characterization method of a nanoscale double-layer material based on a scanning electron microscope comprises the following steps:
1) Simulating and calculating the interaction between an electron beam and a nanoscale double-layer sample to be tested in a scanning electron microscope test by using Monte Carlo simulation, acquiring the excitation depth of back scattering electrons under the condition of continuous voltage parameters, and judging the source of back scattering electron signals;
2) Selecting a plurality of experimental test voltages from the continuous voltage parameters in the step 1), and carrying out scanning electron microscope characterization on a sample to be tested to obtain a back scattering electron image under the corresponding voltage condition;
3) Observing the change of the back scattering electron image obtained in the step 2) along with the reduction of the experimental test voltage, screening out an image with obvious characteristic change, and taking the voltage value of the image as V point ；
4) At slightly lower than V point Voltage parameter V of (2) 1 Acquiring a back scattering electron image under the condition, and observing whether obvious characteristic changes exist or not: if at the voltage parameter V 1 No obvious characteristic change exists in the back scattering electron image obtained under the condition, and the upper material of the experimental sample has the optimal characterization voltage V optimum ＝V point The method comprises the steps of carrying out a first treatment on the surface of the If at the voltage parameter V 1 If obvious characteristic change exists in the back scattering electron image obtained under the condition, V is taken point ＝V 1 Repeating step 4) until the voltage parameter V is reached 1 No obvious characteristic change exists in the back scattering electron image obtained under the condition;
5) Retrieving V from the depth of excitation of backscattered electrons under the continuous voltage parameter conditions obtained in step 1) optimum Corresponding back scattered electron excitation depth D optimum Taking the value as the estimated thickness of the upper material of the sample to be measured, adjusting the thickness of the upper material in Monte Carlo simulation calculation, and carrying out V-shaped simulation on the electron beam and the sample to be measured optimum Performing calculation verification on interaction under the condition;
6) At the optimum voltage parameter V optimum And under the condition, carrying out experimental characterization verification on the nanoscale double-layer sample to be detected by using a scanning electron microscope.
Setting initial values of components and thicknesses of each layer of the sample to be tested when performing simulation calculation in the step 1).
The continuous voltage parameter in the step 1) is in the range of 1kV-30 kV.
And 3) reducing the excitation depth of the back-scattered electron signals along with the reduction of the experimental test voltage, and converting the imaging signals of the back-scattered electron images from the lower layer material to the upper layer material.
The distinct feature change in step 3) refers to imaging of the backscattered electron signals from the different layer materials.
Slightly below V in said step 4) point Voltage V of (2) 1 Refers to adjustable V in experiment point Is a next-gear voltage parameter value.
V in the step 4) 1 The absence of significant feature changes in the backscattered electron images acquired under condition V 1 And V point And acquiring back scattering electronic signal imaging of the same-layer material under the condition.
The said step 5) of computing the verification method is that in V optimum Simulation calculation of upper layer material thickness D under the condition optimum A depth of excitation of the backscattered electrons of less than or equal to D optimum When the thickness value of the upper layer of the sample to be measured is D optimum 。
And step 6), experimental characterization verification is performed by acquiring images under different fields of view by adopting a back scattering electron imaging mode and a secondary electron imaging mode.
The invention has the advantages and beneficial effects that:
1) Compared with the existing method for representing the nano-scale double-layer material based on the scanning electron microscope, the method is not limited to representing the section or the section of the double-layer sample, but can realize the layer-by-layer representation of the nano-scale double-layer material and calculate the thickness of each layer.
2) Compared with the existing method for representing the nano-scale double-layer material based on the transmission electron microscope, the method has the advantages of being applicable to various samples, simple in sample preparation method and experimental operation, high in experimental efficiency, convenient, economical and efficient. In addition, the representation view field of the transmission electron microscope is too limited, and compared with the representation view field of the transmission electron microscope, the method can perform multi-view field representation in a larger range under the scanning electron microscope, and has more statistical significance.
3) The invention provides the Monte Carlo simulation to carry out theoretical calculation on the interaction between the high-energy electron beam and the solid sample, can provide theoretical basis for the selection of experimental parameters, carries out feasibility analysis and result prediction on the experiment, and has wide applicability in the field of electron microscope characterization.
Drawings
FIG. 1 is an overall flow chart of a characterization method of a nanoscale bilayer material based on a scanning electron microscope;
FIG. 2 is a back-scattered electron image of a carbon nano-film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 20 kV;
FIG. 3 is a back-scattered electron image of a carbon nano-film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 5 kV;
FIG. 4 is a back-scattered electron image of a carbon nano-film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 2 kV;
FIG. 5 is a back-scattered electron image of a carbon nano-film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 1 kV;
FIG. 6 is a back-scattered electron image of other fields of view of a carbon nano-film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 2 kV;
FIG. 7 is a secondary electron image of other fields of view of a carbon nanocarbon film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 2kV.
Detailed Description
In order to solve the technical problems, referring to fig. 1, the characterization method of the nanoscale double-layer material based on the scanning electron microscope of the invention comprises the following steps:
1) Simulating and calculating the interaction between an electron beam and a nanoscale double-layer sample to be tested in a scanning electron microscope test by using Monte Carlo simulation, acquiring the excitation depth of back scattering electrons under the condition of continuous voltage parameters, and judging the source of back scattering electron signals;
2) Selecting a plurality of experimental test voltages from the continuous voltage parameters in the step 1), and carrying out scanning electron microscope characterization on a sample to be tested to obtain a back scattering electron image under the corresponding voltage condition;
3) Observing the change of the back scattering electron image obtained in the step 2) along with the reduction of the experimental test voltage, screening out an image with obvious characteristic change, and taking the voltage value of the image as V point ；
4) At slightly lower than V point Voltage parameter V of (2) 1 Acquiring a back scattering electron image under the condition, and observing whether obvious characteristic changes exist or not: if at the voltage parameter V 1 No obvious characteristic change exists in the back scattering electron image obtained under the condition, and the upper material of the experimental sample has the optimal characterization voltage V optimum ＝V point The method comprises the steps of carrying out a first treatment on the surface of the If at the voltage parameter V 1 If obvious characteristic change exists in the back scattering electron image obtained under the condition, V is taken point ＝V 1 Repeating step 4) until the voltage parameter V is reached 1 No obvious characteristic change exists in the back scattering electron image obtained under the condition;
5) Retrieving V from the depth of excitation of backscattered electrons under the continuous voltage parameter conditions obtained in step 1) optimum Corresponding back scattered electron excitation depth D optimum Taking the value as the estimated thickness of the upper material of the sample to be measured, adjusting the thickness of the upper material in Monte Carlo simulation calculation, and carrying out V-shaped simulation on the electron beam and the sample to be measured optimum Performing calculation verification on interaction under the condition;
6) At the optimum voltage parameter V optimum And under the condition, carrying out experimental characterization verification on the nanoscale double-layer sample to be detected by using a scanning electron microscope.
Setting initial values of components and thicknesses of layers of a sample to be tested when performing simulation calculation in the step 1), wherein the thicknesses of the layers are estimated values, and the materials of the layers are assumed to be ideal homogeneous materials with uniform thicknesses.
The continuous voltage parameter in the step 1) is in the range of 1kV-30kV, and the voltage range is a conventional test voltage range characterized by a scanning electron microscope so as to provide theoretical data for subsequent experimental detection.
In the step 3), the excitation depth of the back-scattered electronic signals becomes shallow along with the reduction of the experimental test voltage, the imaging signals of the back-scattered electronic images are converted from the lower layer material to the upper layer material, and the aim of the step is to screen out conversion voltage values for obtaining the back-scattered electronic signals of different layer materials.
The distinct feature change in step 3) refers to imaging of the backscattered electron signals from the different layer materials.
Slightly below V in said step 4) point Voltage V of (2) 1 Refers to adjustable V in experiment point Is used for checking the next voltage parameter value of V point Whether the optimal characterization voltage of the upper layer material of the sample to be detected is obtained.
V in the step 4) 1 The absence of significant feature changes in the backscattered electron images acquired under condition V 1 And V point And acquiring back scattering electronic signal imaging of the same-layer material under the condition.
The said step 5) of computing the verification method is that in V optimum Simulation calculation of upper layer material thickness D under the condition optimum A depth of excitation of the backscattered electrons of less than or equal to D optimum When the thickness value of the upper layer of the sample to be measured is D optimum 。
And step 6), experimental characterization verification is performed by acquiring images under different fields of view by adopting a back scattering electron imaging mode and a secondary electron imaging mode.
The invention will be further described with reference to the accompanying drawings and the following embodiments, it being understood that the drawings and the following embodiments are only for illustrating the invention, not for limiting the invention. The same or corresponding reference numerals in the drawings denote the same parts, and a repetitive description thereof will be omitted.
Examples:
the embodiment provides a characterization method of a nano carbon film-copper mesh (C-Cu) double-layer material based on a scanning electron microscope, which comprises the following steps:
step 1), simulating and calculating the interaction between an electron beam and a nanoscale double-layer sample to be tested in a scanning electron microscope test by using Monte Carlo simulation, obtaining the excitation depth of back scattering electrons under the condition of continuous voltage parameters, and judging the source of back scattering electron signals; setting initial values of components and thicknesses of each layer of a sample to be tested during analog calculation; the continuous voltage parameter is in the range of 1kV-30 kV.
In the embodiment of the invention, initial values of the components and the thicknesses of all layers of the sample to be detected are set during analog calculation, wherein the thickness of each layer is an estimated value, and the materials of all layers are assumed to be ideal homogeneous materials with uniform thickness. In the embodiment, the initial thickness of the upper C layer in the C-Cu double-layer sample to be detected is 50nm, the lower Cu layer is a matrix, the thickness is not limited, and the C layer and the Cu layer are ideal homogeneous materials.
In the embodiment of the invention, the continuous voltage parameter is in the range of 1kV-30kV, and the voltage range is a conventional test voltage range characterized by a scanning electron microscope so as to provide theoretical data for subsequent experimental detection. The voltage range used in this example is 1kV-20kV, and the depth of excitation of the backscattered electrons obtained in this voltage range is shown in Table 1.
TABLE 1
In this example, the excitation depth of the backscattered electrons was at the interface of the upper C layer and the lower copper layer when the voltage parameter was in the range of 2kV-5kV, according to the excitation depths of the backscattered electrons at different voltages shown in table 1.
And 2) selecting a plurality of experimental test voltages from the continuous voltage parameters in the step 1), and carrying out scanning electron microscope characterization on a sample to be tested to obtain a back scattering electron image under the corresponding voltage condition.
In the embodiment, scanning electron microscope characterization is performed on a nano carbon film-copper mesh (C-Cu) sample to be detected under the voltage parameters of 20kV,5kV and 2kV, and a back scattering electron image under the corresponding voltage conditions is obtained, as shown in fig. 2, 3 and 4.
FIG. 2 is a back-scattered electron image of a carbon nano-film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 20 kV. Only the features of the underlying copper mesh are shown in fig. 2.
FIG. 3 is a back-scattered electron image of a carbon nanocarbon film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 5 kV. Features at the interface of the upper nanocarbon film and the lower copper mesh (circles) are shown in fig. 3.
FIG. 4 is a back-scattered electron image of a carbon nanocarbon film-copper mesh (C-Cu) sample to be tested with a voltage parameter of 2kV. Almost only the features of the upper nanocarbon film are shown in fig. 4, as well as a small amount of features at the interface of the upper nanocarbon film and the lower copper mesh (circles).
Step 3) observing the change of the back-scattered electron image obtained in the step 2) along with the reduction of the experimental test voltage, screening out an image with obvious characteristic change, and taking the voltage value of the image as Vpoint; the back scattering electronic signal excitation depth becomes shallow along with the reduction of the experimental test voltage, and the imaging signal of the back scattering electronic image is converted from a lower layer material to an upper layer material; obvious feature changes refer to imaging of backscattered electronic signals from different layer materials.
In the embodiment of the invention, as the experimental test voltage is reduced, the excitation depth of the back-scattered electronic signals becomes shallow, the imaging signals of the back-scattered electronic images are converted from the lower layer material to the upper layer material, and the aim of the step is to screen out and obtain the conversion voltage values of the back-scattered electronic signals of different layer materials. In this embodiment, according to fig. 2, 3 and 4, a back-scattered electron image of a nano carbon film-copper mesh (C-Cu) sample to be measured is obtained under a voltage parameter of 20kV,5kV and 2kV, and as the voltage decreases, an imaging signal of the back-scattered electron image is converted from a lower Cu layer to an upper C layer, and the converted voltage value is 2kV.
In embodiments of the present invention, significant feature variations refer to imaging of backscattered electronic signals from different layer materials. In this embodiment, the backscattering signal obtained when the voltage parameter is 2kV is mainly from the upper carbon layer, but not the lower copper layer, so Vpoint is taken to be 2kV.
Step 4) acquiring a back-scattered electron image under the condition of a voltage parameter V1 slightly lower than Vpoint, and observing whether obvious characteristic changes exist or not: if no obvious characteristic change exists in the back-scattered electron image obtained under the condition of the voltage parameter V1, the upper material of the experimental sample optimally represents the voltage Voptimum=Vpoint; if the back-scattered electron image acquired under the condition of the voltage parameter V1 has obvious characteristic change, taking Vpoint=V1, and repeating the step 4) until the back-scattered electron image acquired under the condition of the voltage parameter V1 has no obvious characteristic change; wherein, the voltage V1 slightly lower than the Vpoint refers to the next-gear voltage parameter value which is adjustable in the experiment and lower than the Vpoint; the absence of significant feature changes in the backscattered electron image acquired under the V1 condition means acquiring backscattered electron signal imaging of the same layer material under the conditions V1 and Vpoint.
In the embodiment of the invention, the voltage V1 slightly lower than the Vpoint refers to the next-gear voltage parameter value which is adjustable in the experiment and lower than the Vpoint, and the purpose of the step is to check whether the Vpoint is the optimal characterization voltage of the upper material of the sample to be tested. In this embodiment, the voltage parameter V1 takes a value of 1kV, and an obtained back-scattered electron image of a nano carbon film-copper mesh (C-Cu) sample to be measured is shown in fig. 5.
In the embodiment of the invention, no obvious characteristic change in the back-scattered electron image obtained under the condition V1 means that back-scattered electron signal imaging of the same-layer material is obtained under the conditions V1 and Vpoint. In this embodiment, the back-scattering electron image with the voltage parameter of 1kV shown in fig. 5 is similar to the back-scattering electron image with the voltage parameter of 2kV shown in fig. 4, and is the back-scattering electron signal imaging of the upper carbon layer, and almost has no characteristic of the lower copper layer, so that the optimal characterization voltage Voptimum of the nano carbon film-copper network (C-Cu) sample to be measured is 2kV.
Step 5) searching the back scattering electron excitation depth Doptimum corresponding to the Voptimum in the back scattering electron excitation depth under the continuous voltage parameter condition obtained in the step 1), taking the value as the estimated thickness of the upper material of the sample to be detected, adjusting the thickness of the upper material in Monte Carlo simulation calculation, and carrying out calculation verification on the interaction of the electron beam and the sample to be detected under the Voptimum condition; the calculation verification method is to simulate and calculate the back scattering electron excitation depth when the thickness of the upper layer material is Doptimum under the condition of Voptimum, and to obtain the upper layer thickness value of the sample to be detected as Doptimum when the thickness is smaller than or equal to Doptimum.
In this example, in table 1, the depth of excitation of the backscattered electrons Doptimum corresponding to Voptimum of 2kV was found to be 30nm, and therefore, the estimated thickness of the upper C layer of the nano carbon film-copper mesh (C-Cu) sample to be measured was taken to be 30nm.
In the embodiment of the invention, the calculation and verification method is to simulate and calculate the back scattering electron excitation depth when the thickness of the upper layer material is Doptimum under the condition of Voptimum, and take the upper layer thickness value of the sample to be measured as Doptimum when the thickness is smaller than or equal to Doptimum. And (3) adjusting the thickness of the upper C layer in Monte Carlo simulation calculation to be 30nm, calculating the excitation depth of scattered electrons when the thickness of the upper C layer is calculated to be 30nm under the condition that the voltage parameter is 2kV, wherein the excitation depth is about 24nm and is smaller than the Doptimum 30nm, and thus taking the upper layer thickness value of a nano carbon film-copper mesh (C-Cu) sample to be measured to be about 30nm.
Step 6) carrying out experimental characterization verification on the nanoscale double-layer sample to be tested by using a scanning electron microscope under the condition of the optimal voltage parameter Voptimum; the experimental characterization verification adopts a back scattering electron imaging mode and a secondary electron imaging mode to acquire images under different fields of view for verification.
In this embodiment, under the condition of the voltage parameter Voptimum 2kV, the image is acquired in other fields of view by adopting a back-scattered electron imaging mode and a secondary electron imaging mode for verification. Fig. 6 is a back-scattered electron image of other fields of view of a nano carbon film-copper mesh (C-Cu) sample to be measured at a voltage parameter of 2kV, and fig. 7 is a secondary electron image of other fields of view of a nano carbon film-copper mesh (C-Cu) sample to be measured at a voltage parameter of 2kV.
The above embodiments further describe the objects, technical solutions and advantageous effects of the present invention in detail, it should be understood that the above is only one embodiment of the present invention and is not limited to the scope of the present invention, and the present invention may be embodied in various forms without departing from the gist of the essential characteristics of the present invention, and thus the embodiments of the present invention are intended to be illustrative and not limiting, since the scope of the present invention is defined by the claims rather than the specification, and all changes falling within the scope defined by the claims or the equivalent scope of the scope defined by the claims should be construed to be included in the claims. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (1)
1. A characterization method of a nanoscale double-layer material based on a scanning electron microscope comprises the following steps:
1) Simulating and calculating the interaction between an electron beam and a nanoscale double-layer sample to be tested in a scanning electron microscope test by using Monte Carlo simulation, acquiring the excitation depth of back scattering electrons under the condition of continuous voltage parameters, and judging the source of back scattering electron signals;
2) Selecting a plurality of experimental test voltages from the continuous voltage parameters in the step 1), and carrying out scanning electron microscope characterization on a sample to be tested to obtain a back scattering electron image under the corresponding voltage condition;
3) Observing the change of the back scattering electron image obtained in the step 2) along with the reduction of the experimental test voltage, screening out an image with obvious characteristic change, and taking the voltage value of the image as V point ；
4) At slightly lower than V point Voltage parameter V of (2) 1 Acquiring a back scattering electron image under the condition, and observing whether obvious characteristic changes exist or not: if at the voltage parameter V 1 The upper layer material of the sample to be tested has the optimal characterization voltage V if no obvious characteristic change exists in the back scattering electron image obtained under the condition optimum ＝V point The method comprises the steps of carrying out a first treatment on the surface of the If at the voltage parameter V 1 If obvious characteristic change exists in the back scattering electron image obtained under the condition, V is taken point ＝V 1 Repeating step 4) until the voltage parameter V is reached 1 No obvious characteristic change exists in the back scattering electron image obtained under the condition;
5) Retrieving V from the depth of excitation of backscattered electrons under the continuous voltage parameter conditions obtained in step 1) optimum Corresponding backscattered electronsDepth of excitation D optimum Taking the value as the estimated thickness of the upper material of the sample to be measured, adjusting the thickness of the upper material in Monte Carlo simulation calculation, and carrying out V-shaped simulation on the electron beam and the sample to be measured optimum Performing calculation verification on interaction under the condition;
6) At the optimum voltage parameter V optimum Under the condition, using a scanning electron microscope to perform experimental characterization verification on the nanoscale double-layer sample to be detected;
setting initial values of components and thicknesses of each layer of a sample to be tested when performing simulation calculation in the step 1);
the continuous voltage parameter in the step 1) is in the range of 1kV-30 kV;
in the step 3), the excitation depth of the back scattering electronic signal becomes shallow along with the reduction of the experimental test voltage, and the imaging signal of the back scattering electronic image is converted from a lower layer material to an upper layer material;
the obvious characteristic change in the step 3) refers to the imaging of the back-scattered electronic signals from different layer materials;
the voltage V1 slightly lower than the Vpoint in the step 4) refers to a next-gear voltage parameter value which is adjustable in the experiment and lower than the Vpoint;
the fact that no obvious characteristic change exists in the back-scattered electron image obtained under the condition V1 in the step 4) means that back-scattered electron signal imaging of the same-layer material is obtained under the conditions V1 and Vpoint;
the calculation and verification method in the step 5) is to simulate and calculate the back scattering electron excitation depth when the thickness of the upper layer material is Doptimum under the condition of Voptimum, and to obtain the upper layer thickness value of the sample to be detected as Doptimum when the thickness is smaller than or equal to the Doptimum;
and step 6), experimental characterization verification is performed by acquiring images under different fields of view by adopting a back scattering electron imaging mode and a secondary electron imaging mode.
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| RU2453946C1 (en) * | 2010-12-27 | 2012-06-20 | Глеб Сергеевич Жданов | Method for tomographic sample analysis in scanning electron microscope |
| CN103344789A (en) * | 2013-07-05 | 2013-10-09 | 北京工业大学 | Thin sample transmission filtration-reflection receiving type contrast separation imaging method in scanning electron microscope |
| WO2018108912A1 (en) * | 2016-12-15 | 2018-06-21 | Commissariat A L'energie Atomique Et Aux Energies Alternatives | Method for implementing a cd-sem characterisation technique |
| WO2018108914A1 (en) * | 2016-12-15 | 2018-06-21 | Commissariat A L'energie Atomique Et Aux Energies Alternatives | Method for characterisation by cd-sem scanning electron microscopy |
| CN109300759A (en) * | 2017-11-21 | 2019-02-01 | 聚束科技（北京）有限公司 | Low energy scanning electron microscope system, scanning electron microscope system and sample detection method |
| CN112325810A (en) * | 2020-10-26 | 2021-02-05 | 无锡华鑫检测技术有限公司 | Method for measuring depth of electron beam spot of scanning electron microscope |
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| RU2453946C1 (en) * | 2010-12-27 | 2012-06-20 | Глеб Сергеевич Жданов | Method for tomographic sample analysis in scanning electron microscope |
| CN103344789A (en) * | 2013-07-05 | 2013-10-09 | 北京工业大学 | Thin sample transmission filtration-reflection receiving type contrast separation imaging method in scanning electron microscope |
| WO2018108912A1 (en) * | 2016-12-15 | 2018-06-21 | Commissariat A L'energie Atomique Et Aux Energies Alternatives | Method for implementing a cd-sem characterisation technique |
| WO2018108914A1 (en) * | 2016-12-15 | 2018-06-21 | Commissariat A L'energie Atomique Et Aux Energies Alternatives | Method for characterisation by cd-sem scanning electron microscopy |
| CN109300759A (en) * | 2017-11-21 | 2019-02-01 | 聚束科技（北京）有限公司 | Low energy scanning electron microscope system, scanning electron microscope system and sample detection method |
| CN112325810A (en) * | 2020-10-26 | 2021-02-05 | 无锡华鑫检测技术有限公司 | Method for measuring depth of electron beam spot of scanning electron microscope |
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