CN113008170A - Thickness measurement method and system - Google Patents

Thickness measurement method and system Download PDF

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Publication number
CN113008170A
CN113008170A CN202110295161.8A CN202110295161A CN113008170A CN 113008170 A CN113008170 A CN 113008170A CN 202110295161 A CN202110295161 A CN 202110295161A CN 113008170 A CN113008170 A CN 113008170A
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thickness
sample
calibration sample
directional line
absorptivity
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CN113008170B (en
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李国梁
张笑
魏强民
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Yangtze Memory Technologies Co Ltd
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Yangtze Memory Technologies Co Ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B15/00Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
    • G01B15/02Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons for measuring thickness
    • G01B15/025Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons for measuring thickness by measuring absorption

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  • General Physics & Mathematics (AREA)
  • Length-Measuring Devices Using Wave Or Particle Radiation (AREA)

Abstract

The embodiment of the application discloses a thickness measuring method and a system, wherein the method comprises the following steps: acquiring a TEM image of a calibration sample output by a transmission electron microscope; obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample; measuring the thickness of the calibration sample by a preset measuring method; obtaining an absorptivity-thickness relation curve according to the absorptivity and the thickness of the calibration sample; acquiring the absorption rate of a sample to be detected; and calculating to obtain the thickness of the sample to be detected according to the absorption rate-thickness relation curve and the absorption rate of the sample to be detected.

Description

Thickness measurement method and system
Technical Field
The embodiment of the application relates to the field of semiconductor manufacturing, in particular to a thickness measuring method and system.
Background
A Transmission Electron Microscope (TEM) is a widely used instrument for testing semiconductor structures. In the transmission Electron microscope, the thickness of the sample is measured by a Convergent Beam Electron Diffraction (CBED) measurement method, an Electron Energy Loss Spectroscopy (EELS) measurement method, and the like. The convergent-beam electron diffraction method needs to tilt a transmission electron microscope sample to a double-beam condition, has high requirements on the level of a transmission electron microscope operator, is very complicated in measurement process, and can only measure the thickness of a crystalline sample; the electron energy loss spectroscopy method calculates the thickness of a sample according to the intensity change of a zero peak and a plasma peak, and although the operation is simple, the transmission electron microscope used must be equipped with an expensive electron energy loss spectroscopy instrument.
Therefore, further improvements in the thickness measurement method are desired to improve the measurement efficiency, measurement range, and measurement accuracy.
Disclosure of Invention
In view of the above, embodiments of the present application provide a thickness measuring method and system to solve at least one problem in the prior art.
In order to achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:
in a first aspect, an embodiment of the present application provides a thickness measurement method, where the method includes:
acquiring a TEM image of a calibration sample output by a transmission electron microscope;
obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample;
measuring the thickness of the calibration sample by a preset measuring method;
obtaining an absorptivity-thickness relation curve according to the absorptivity and the thickness of the calibration sample;
acquiring the absorption rate of a sample to be detected;
and calculating to obtain the thickness of the sample to be detected according to the absorption rate-thickness relation curve and the absorption rate of the sample to be detected.
In an alternative embodiment, the obtaining the absorbance of the calibration sample according to the gray-scale value of the TEM image of the calibration sample includes:
performing directional line scanning on the TEM image of the calibration sample to obtain a gray value corresponding to a directional line scanning path;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the gray value corresponding to the directional line scanning path and the gray value at the vacuum.
In an alternative embodiment, the obtaining the absorbance of the calibration sample corresponding to the directional line scan path according to the gray-scale value corresponding to the directional line scan path and the gray-scale value at the vacuum includes:
obtaining the transmissivity of the calibration sample corresponding to the directional line scanning path according to the ratio of the gray value corresponding to the directional line scanning path to the gray value at the vacuum position;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the transmissivity.
In an alternative embodiment, the preset measurement method includes an electron energy loss spectrum measurement method and a TEM cross-sectional image measurement method.
In an alternative embodiment, in the case that the preset measurement method is an electron energy loss spectroscopy measurement method, the measuring the thickness of the calibration sample by the preset measurement method includes:
acquiring an electron energy loss spectrum of the calibration sample corresponding to a directional line scanning path along the directional line scanning direction;
and calculating the thickness of the calibration sample corresponding to the directional line scanning path according to the electron energy loss spectrum.
In an alternative embodiment, the obtaining an absorbance-thickness relationship curve from the absorbance and the thickness of the calibration sample comprises:
and fitting the absorptivity and the thickness of the calibration sample to obtain a relation curve of absorptivity and thickness.
In an alternative embodiment, the acquiring the absorbance of the sample to be tested includes:
acquiring a TEM image of a sample to be detected output by a transmission electron microscope;
and obtaining the absorption rate of the sample to be detected according to the gray value of the TEM image of the sample to be detected.
In a second aspect, an embodiment of the present application provides a thickness measurement system, including:
the acquisition module is used for acquiring a TEM image of the calibration sample output by the transmission electron microscope; obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample;
the preset measuring module is used for measuring the thickness of the calibration sample by a preset measuring method;
the function generation module is used for obtaining an absorptivity-thickness relation curve according to the absorptivity and the thickness of the calibration sample;
the acquisition module is also used for acquiring the absorptivity of the sample to be detected;
and the calculation module is used for calculating the thickness of the sample to be detected according to the absorption rate-thickness relation curve and the absorption rate of the sample to be detected.
In an optional embodiment, the acquiring module is specifically configured to perform directional line scanning on a TEM image of a calibration sample to obtain a gray value corresponding to a directional line scanning path;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the gray value corresponding to the directional line scanning path and the gray value at the vacuum.
In an optional embodiment, the obtaining module is specifically configured to obtain, according to a ratio of a gray value corresponding to the directional line scanning path to a gray value at a vacuum, a transmittance of the calibration sample corresponding to the directional line scanning path;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the transmissivity.
In an alternative embodiment, the preset measurement method includes an electron energy loss spectrum measurement method and a TEM cross-sectional image measurement method.
In an optional implementation manner, in a case that the preset measurement method is an electron energy loss spectrum measurement method, the preset measurement module is specifically configured to obtain an electron energy loss spectrum of the calibration sample corresponding to a directional line scanning path along the directional line scanning direction;
and calculating the thickness of the calibration sample corresponding to the directional line scanning path according to the electron energy loss spectrum.
In an optional embodiment, the function generating module is specifically configured to fit the absorbance and the thickness of the calibration sample to obtain an absorbance-thickness relationship curve.
In an optional embodiment, the acquiring module is specifically configured to acquire a TEM image of a sample to be detected output by a transmission electron microscope;
and obtaining the absorption rate of the sample to be detected according to the gray value of the TEM image of the sample to be detected.
The embodiment of the application discloses a thickness measuring method and a system, wherein the method comprises the following steps: acquiring a TEM image of a calibration sample output by a transmission electron microscope; obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample; measuring the thickness of the calibration sample by a preset measuring method; obtaining an absorptivity-thickness relation curve according to the absorptivity and the thickness of the calibration sample; acquiring the absorption rate of a sample to be detected; and calculating to obtain the thickness of the sample to be detected according to the absorption rate-thickness relation curve and the absorption rate of the sample to be detected. The thickness of the sample can be calculated according to the absorption rate by establishing the corresponding relation between the absorption rate and the thickness. According to the thickness measuring method, the thickness of the sample can be measured quickly and accurately without additional equipment. And the measuring process is convenient and quick, and the sample thickness can be calculated according to the corresponding relation between the absorption rate and the thickness only by carrying out TEM image acquisition, so that the measuring period is short.
Drawings
Fig. 1 is a schematic flow chart illustrating an implementation of a transmission electron microscope inspection method according to an embodiment of the present disclosure;
FIG. 2 is a diagram of a transmission electron microscope imaging process provided by an embodiment of the present application;
FIG. 3 is a diffraction spectrum of a transmission electron microscope provided in an embodiment of the present application;
FIG. 4 is a TEM image of a calibration sample provided by an embodiment of the present application;
FIG. 5 is a distance versus gray level curve provided in accordance with an embodiment of the present application;
FIG. 6 is a distance versus transmittance curve provided in accordance with an embodiment of the present application;
FIG. 7 is a distance-absorbance curve provided in accordance with an embodiment of the present application;
FIG. 8 is a distance-thickness curve provided in accordance with an embodiment of the present application;
FIG. 9 is a schematic diagram illustrating a data point selection method according to an embodiment of the present application;
FIG. 10 is an absorbance versus thickness curve provided by an embodiment of the present application;
FIG. 11 is a graph illustrating a comparison of distance-thickness curves provided in accordance with an embodiment of the present application;
fig. 12 is a schematic structural diagram of a thickness measurement system according to an embodiment of the present disclosure.
Detailed Description
Exemplary embodiments disclosed in the present application will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art, that the present application may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the present application; that is, not all features of an actual embodiment are described herein, and well-known functions and structures are not described in detail.
In the drawings, the size of layers, regions, elements, and relative sizes may be exaggerated for clarity. Like reference numerals refer to like elements throughout.
It will be appreciated that spatial relationship terms, such as "under … …," "under … …," "under … …," "over … …," "over," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below … …" and "below … …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
An embodiment of the present application provides a thickness measurement method, and fig. 1 is a schematic view illustrating an implementation flow of the thickness measurement method provided in the embodiment of the present application, where as shown in fig. 1, the method mainly includes the following steps:
and step 110, acquiring a TEM image of the calibration sample output by the transmission electron microscope.
In an embodiment of the present application, the calibration sample includes a thin film layer, and the TEM image of the calibration sample includes the thin film layer. The thickness measurement method provided by the embodiment of the application can be a thickness measurement method for a thin film layer. In some embodiments, the thin film layer may be a silicon oxide thin film layer.
In the present example, TEM images of the calibration sample were acquired by transmission electron microscopy. Before transmission electron microscopic shooting, an incident light spot is uniformly irradiated on a sample area, and an objective lens diaphragm is inserted into the back focal plane of an objective lens of a transmission electron microscope and aligned. FIG. 2 is a diagram of a transmission electron microscope imaging process, as shown in FIG. 2, when a parallel electron beam generated in a transmission electron microscope passes through a sample (e.g., a crystal), the parallel electron beam is scattered by a periodic structure (crystal plane) inside the sample, and is split into multiple diffraction orders, and a diffraction spectrum is formed on a back focal plane (at an objective lens diaphragm) of the transmission electron microscope; and the diffraction spots of each level on the diffraction spectrum interfere with each other in the subsequent propagation process and are converged and imaged on the image plane of the objective lens again. In practical application, the size of the objective aperture is not fixed, and different aperture sizes correspond to different absorptances. The small-size diaphragm has high image contrast and high corresponding absorptivity contrast, but the signal is weaker, and the large-size diaphragm has weak image contrast and strong signal, so that the size of the objective lens diaphragm can be selected according to actual requirements in practical application. FIG. 3 shows a typical single crystal diffraction spectrum obtained by transmission electron microscopy, as shown in FIG. 3, the objective stop in the present example is preferably 50 μm in size, equivalent to screening 0-15mrad of scattered electrons at the back focal plane of the objective for imaging.
And step 120, obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample.
In the embodiment of the present application, fig. 4 is a TEM image of a calibration sample provided in the embodiment of the present application, and as shown in fig. 4, a directional line scan is performed on the TEM image of the calibration sample along a direction shown by a dotted line in fig. 4 to obtain a gray value corresponding to a directional line scan path; obtaining the transmissivity of the calibration sample corresponding to the directional line scanning path according to the ratio of the gray value corresponding to the directional line scanning path to the gray value at the vacuum position; and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the transmissivity. Here, the absorbance of the calibration sample corresponding to the directional line scan path is obtained by subtracting the transmittance by 1.
As shown in fig. 4, the calibration sample includes a silicon oxide thin film layer and a metal structure, and when the thickness of the calibration sample is measured, the thickness of the silicon oxide thin film layer in the calibration sample is measured. Here, the material of the metal structure is tungsten.
In the embodiment of the present application, the calibration sample includes a silicon monoxide thin film layer for illustration, fig. 5 is a distance-grayscale curve provided in a specific embodiment of the present application, as shown in fig. 5, a TEM image of the calibration sample is subjected to directional line scanning to obtain a grayscale value corresponding to a directional line scanning path, in practical application, the directional line scanning is that the scanning electron microscope emits an electron beam edge to the calibration sample along a set direction, that is, the directional line scanning is that the electron beam edge is emitted to the calibration sample along a line scanning path, then the grayscale value corresponding to the directional line scanning path is the distance-grayscale curve as shown in fig. 5, where the distance is a distance between any point on the directional line scanning path and a start point of the directional line scanning; the gray scale is the gray scale value of the TEM image corresponding to the point on the directional line scan path.
Fig. 6 is a distance-transmittance curve provided in an embodiment of the present application, and as shown in fig. 6, a distance-transmittance curve of the calibration sample is obtained according to a ratio of the distance-grayscale curve to a grayscale value at a vacuum, where the distance is a distance between any point on a scan path of the directional line and a start point of the scan of the directional line; the transmission is the transmission of the TEM image corresponding to that point on the directional line scan path. In some embodiments, the gray value at vacuum may be an average gray value at vacuum, where the average gray value at vacuum is 4559.223.
Fig. 7 is a distance-absorbance curve provided by an embodiment of the present application, and as shown in fig. 7, the distance is a distance between any point on the directional line scanning path and the start point of the directional line scanning, where the transmittance in the distance-transmittance curve is subtracted from 1 to obtain a distance-absorbance curve of the calibration sample; the absorption is the absorption of the TEM image corresponding to that point on the directional line scan path.
It should be noted that, since the calibration sample includes a metal structure, when performing the directional line scan, the directional line scan path covers the metal structure, and therefore, the distance-grayscale curve shown in fig. 5 includes the grayscale of the metal structure in addition to the grayscale of the silicon oxide thin film layer. The graphs illustrated in fig. 6-7 each include data for a metal structure. However, in the present embodiment, only data of the silicon oxide thin film layer is focused, and data of the metal structure is not focused.
Step 130, measuring the thickness of the calibration sample by a preset measuring method.
In the embodiment of the application, the preset measurement method comprises an electron energy loss spectrum measurement method and a TEM sectional image measurement method. The TEM cross-section image measuring method is to cut the calibration sample along the directional line scanning direction shown in fig. 5, obtain the cross-section of the calibration sample along the directional line scanning direction, take the TEM image of the cross-section, and directly measure the actual thickness of the cross-section in the TEM image to obtain the thickness of the calibration sample. In the embodiment of the present application, the preset measurement method is taken as an example of an electron energy loss spectrum measurement method, and an electron energy loss spectrum of the calibration sample corresponding to a directional line scanning path is obtained along a directional line scanning direction; and calculating the thickness of the calibration sample corresponding to the directional line scanning path according to the electron energy loss spectrum.
Fig. 8 is a distance-thickness curve provided in an embodiment of the present application, as shown in fig. 8, an electron energy loss spectrum of the calibration sample corresponding to the directional line scan path is obtained along the directional line scan direction shown in fig. 5; and calculating to obtain a distance-thickness curve of the calibration sample according to the electron energy loss spectrum. Wherein, the distance is the distance between any point on the directional line scanning path and the directional line scanning starting point; the thickness is the thickness of the calibration sample corresponding to the point on the directional line scan path.
It should be noted that the calibration sample includes a metal structure, and when the thickness of the calibration sample is measured by a predetermined measurement method, the distance-thickness curve shown in fig. 8 includes the thickness of the metal structure in addition to the thickness of the silicon oxide thin film layer because the directional line scanning path covers the metal structure. However, in the present embodiment, only data of the silicon oxide thin film layer is focused, and data of the metal structure is not focused.
And 140, obtaining an absorptivity-thickness relation curve according to the absorptivity and the thickness of the calibration sample.
In the embodiment of the application, the distance-absorbance curve and the distance-thickness curve of the calibration sample are fitted to obtain an absorbance-thickness relation curve. The absorbance-thickness relationship curve obtained by fitting is a functional relationship between the absorbance and the thickness, in other words, the thickness of the sample corresponding to the absorbance can be calculated from the functional relationship between the absorbance and the thickness by the absorbance.
In some embodiments, the method may further include selecting data points from the distance-absorbance curve and the distance-thickness curve according to a predetermined distance step, generating absorbance-thickness data points according to the selected data points, and generating an absorbance-thickness relationship curve according to the absorbance-thickness data points. Here, the preset distance step may be 0.5 μm, 1 μm, 1.5 μm, or the like.
In the embodiment of the application, in the process of selecting the data points, an equidistant step length selecting mode can be adopted, and an unequal step length selecting mode can also be adopted.
Fig. 9 is a schematic diagram of a data point selection method provided in an embodiment of the present application, and as shown in fig. 9, data points (e.g., data points pointed by a triangle in fig. 9) are respectively selected from a distance-absorbance curve and a distance-thickness curve by using a selection method with unequal distance step sizes, absorbance-thickness data points are generated according to the selected data points, an absorbance-thickness relation curve is generated according to the absorbance-thickness data points, and the generated absorbance-thickness relation curve is as shown in fig. 10.
As shown in fig. 10, for the silicon oxide thin film layer with a thickness of less than 100nm, the absorption rate of the TEM image and the thickness of the thin film layer are in a linear relationship, and the absorption rate of the TEM image can be directly linearly converted into the thickness of the thin film layer, with a linear conversion coefficient of 250. For the silicon oxide thin film layer larger than 100nm, although the absorption rate of the TEM image and the thickness of the thin film layer do not follow a linear relation any more, the linear conversion coefficient is increased, a corresponding nonlinear conversion coefficient can be obtained through fitting, and the absorption rate of the TEM image can be directly linearly converted into the thickness of the thin film layer based on the nonlinear conversion coefficient.
Fig. 11 is a comparison schematic diagram of a distance-thickness curve provided in an embodiment of the present application, and as shown in fig. 11, a dotted line in the diagram is a distance-thickness curve measured by an electron energy loss spectroscopy measurement method, and a solid line in the diagram is a distance-thickness curve measured by a thickness measurement method provided in an embodiment of the present application. It should be noted that the distance-thickness curve measured by the thickness measurement method provided in the embodiment of the present application is calculated by the linear transformation coefficient 250 obtained in fig. 10. As shown in fig. 11, in the case that the thickness is less than 100nm, the distance-thickness curve (dotted line) measured by the electron energy loss spectroscopy method and the distance-thickness curve (solid line) measured by the thickness measurement method provided in the embodiment of the present application substantially coincide, which indicates that the accuracy of the thickness measured by the thickness measurement method provided in the embodiment of the present application is extremely high.
The thickness measuring method provided by the embodiment of the application can cover a large thickness range, and through the relation curve of the absorption rate and the thickness, the thickness of the sample can be calculated conveniently and rapidly according to the absorption rate of the TEM image by shooting the TEM image of the sample, and no additional equipment is required to be configured and no other thickness measuring methods are required to be introduced.
And 150, acquiring the absorption rate of the sample to be detected.
In the embodiment of the application, a TEM image of a sample to be detected output by a transmission electron microscope is obtained; and obtaining the absorption rate of the sample to be detected according to the gray value of the TEM image of the sample to be detected.
In the embodiment of the application, the calibration sample and the sample to be detected are the same type of sample, and the calibration sample and the sample to be detected are the same in material. For example, the structure of the sample to be measured is that a silicon oxide film layer is arranged on a substrate, and then the structure of the calibration sample is also that a silicon oxide film layer is arranged on a substrate. The calibration sample and the sample to be tested both comprise a thin film layer. Here, the calibration sample and the sample to be measured only need to include the thin film layers of the same material, and the structures of the calibration sample and the sample to be measured are not limited. The thickness of the thin film layer of the calibration sample and the thickness of the thin film layer of the sample to be measured can be the same or different. Further, one sample among samples to be measured may be selected as the calibration sample so that the calibration sample has a referential property.
The thickness measuring method provided by the embodiment of the application can be suitable for various thin film layer materials, and is wide in application range.
And 160, calculating to obtain the thickness of the sample to be detected according to the absorption rate-thickness relation curve and the absorption rate of the sample to be detected.
In the embodiment of the application, the thickness of the sample to be measured can be calculated by bringing the absorption rate of the sample to be measured into the absorption rate-thickness relation curve. The absorbance-thickness relationship here is the absorbance as a function of thickness. As shown in fig. 10, for example, when the absorption rate of the TEM image and the thickness of the sample are linearly related, the absorption rate of the TEM image can be directly linearly converted into the thickness of the sample according to the linear function of the absorption rate-thickness. When the absorptivity of the TEM image is in a nonlinear relation with the thickness of the sample, the absorptivity of the TEM image can be directly converted into the thickness of the sample linearly according to a nonlinear function relation of absorptivity and thickness.
It should be noted that, if the thickness of the calibration sample is measured by an electron energy loss spectrum measurement method, a transmission electron microscope with an electron energy loss spectrometer is required to be used when establishing the corresponding relationship between the absorption rate and the thickness, and in the subsequent measurement process of the sample to be measured, the absorption rate-thickness relationship curve can be used by only taking a TEM image of the sample to be measured by a general transmission electron microscope without using the transmission electron microscope with the electron energy loss spectrometer, so as to calculate the thickness of the sample to be measured.
It should be further noted that, if the thickness of the calibration sample is measured by the TEM cross-sectional image measurement method, the transmission electron microscope does not need to configure additional equipment (e.g., an electron energy loss spectrometer) and introduce other thickness measurement methods, the corresponding relationship between the absorption rate and the thickness can be established only by shooting the TEM image of the calibration sample with a general transmission electron microscope, and the thickness of the sample to be measured can be calculated by using the absorption rate-thickness relationship curve only by shooting the TEM image with the transmission electron microscope during the subsequent thickness measurement process of the sample to be measured.
The embodiment of the application discloses a thickness measuring method, which comprises the following steps: acquiring a TEM image of a calibration sample output by a transmission electron microscope; obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample; measuring the thickness of the calibration sample by a preset measuring method; obtaining an absorptivity-thickness relation curve according to the absorptivity and the thickness of the calibration sample; acquiring the absorption rate of a sample to be detected; and calculating to obtain the thickness of the sample to be detected according to the absorption rate-thickness relation curve and the absorption rate of the sample to be detected. The thickness of the sample can be calculated according to the absorptivity of the sample by establishing the corresponding relation between the absorptivity and the thickness of the sample. According to the thickness measuring method, the thickness of the sample can be measured quickly and accurately without additional equipment. And the measuring process is convenient and quick, and the sample thickness can be calculated according to the corresponding relation between the absorption rate and the thickness only by carrying out TEM image acquisition, so that the measuring period is short.
Based on the same technical concept of the foregoing thickness measurement method, an embodiment of the present application provides a thickness measurement system, and in some embodiments, the thickness measurement system may be implemented in a software module, and fig. 12 is a schematic structural diagram of a thickness measurement system provided in an embodiment of the present application, and referring to fig. 12, a thickness measurement system 1200 provided in an embodiment of the present application includes:
an obtaining module 1201, configured to obtain a TEM image of a calibration sample output by the transmission electron microscope; obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample;
a preset measurement module 1202 for measuring the thickness of the calibration sample by a preset measurement method;
a function generating module 1203, configured to obtain an absorbance-thickness relation curve according to the absorbance and the thickness of the calibration sample;
the obtaining module 1201 is further configured to obtain an absorption rate of the sample to be measured;
and the calculating module 1204 is configured to calculate the thickness of the sample to be measured according to the absorption rate-thickness relation curve and the absorption rate of the sample to be measured.
In other embodiments, the obtaining module 1201 is specifically configured to perform directional line scanning on a TEM image of a calibration sample to obtain a gray value corresponding to a directional line scanning path;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the gray value corresponding to the directional line scanning path and the gray value at the vacuum.
In other embodiments, the obtaining module 1201 is specifically configured to obtain the transmittance of the calibration sample corresponding to the directional line scanning path according to a ratio of the gray value corresponding to the directional line scanning path to the gray value at the vacuum;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the transmissivity.
In other embodiments, the preset measurement method includes an electron energy loss spectrum measurement method and a TEM cross-sectional image measurement method.
In other embodiments, in the case that the preset measurement method is an electron energy loss spectrum measurement method, the preset measurement module 1202 is specifically configured to obtain an electron energy loss spectrum of the calibration sample corresponding to an oriented line scanning path along the oriented line scanning direction;
and calculating the thickness of the calibration sample corresponding to the directional line scanning path according to the electron energy loss spectrum.
In other embodiments, the function generating module 1203 is specifically configured to fit the absorbance and the thickness of the calibration sample to obtain an absorbance-thickness relationship curve.
In other embodiments, the calibration sample is the same material as the sample to be tested.
In other embodiments, the calibration sample and the test sample each comprise a thin film layer of the same material.
In other embodiments, the obtaining module 1201 is specifically configured to obtain a TEM image of a sample to be detected output by a transmission electron microscope;
and obtaining the absorption rate of the sample to be detected according to the gray value of the TEM image of the sample to be detected.
In other embodiments, an objective stop is inserted into the transmission electron microscope.
The components in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware or a form of a software functional module.
Based on the understanding that the technical solution of the embodiments of the present application, or a part thereof contributing to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a device having a processor function (such as a transmission electron microscope) to execute all or part of the steps of the method of the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
It is to be understood that the embodiments described herein may be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the Processing units may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), general purpose processors, controllers, micro-controllers, microprocessors, other electronic units configured to perform the functions described herein, or a combination thereof.
For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory and executed by a processor. The memory may be implemented within the processor or external to the processor.
It should be appreciated that reference throughout this specification to "an embodiment" or "some embodiments" means that a particular feature, structure or characteristic described in connection with the embodiments is included in at least one embodiment of the present application. Thus, the appearances of the phrases "in embodiments of the present application" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiments. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
It should be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.
The methods disclosed in the several method embodiments provided in the present application may be combined arbitrarily without conflict to obtain new method embodiments.
The features disclosed in the several apparatus embodiments provided in the present application may be combined in any combination to arrive at new apparatus embodiments without conflict.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (14)

1. A method of thickness measurement, the method comprising:
acquiring a TEM image of a calibration sample output by a transmission electron microscope;
obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample;
measuring the thickness of the calibration sample by a preset measuring method;
obtaining an absorptivity-thickness relation curve according to the absorptivity and the thickness of the calibration sample;
acquiring the absorption rate of a sample to be detected;
and calculating to obtain the thickness of the sample to be detected according to the absorption rate-thickness relation curve and the absorption rate of the sample to be detected.
2. The thickness measurement method according to claim 1, wherein obtaining the absorbance of the calibration sample from the gray scale values of the TEM image of the calibration sample comprises:
performing directional line scanning on the TEM image of the calibration sample to obtain a gray value corresponding to a directional line scanning path;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the gray value corresponding to the directional line scanning path and the gray value at the vacuum.
3. The method of claim 2, wherein the obtaining the absorbance of the calibration sample corresponding to the directional line scan path from the grey value corresponding to the directional line scan path and the grey value at vacuum comprises:
obtaining the transmissivity of the calibration sample corresponding to the directional line scanning path according to the ratio of the gray value corresponding to the directional line scanning path to the gray value at the vacuum position;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the transmissivity.
4. The thickness measurement method according to claim 2,
the preset measurement method comprises an electron energy loss spectrum measurement method and a TEM section image measurement method.
5. The thickness measuring method according to claim 4, wherein in the case where the preset measuring method is an electron energy loss spectroscopy measuring method, the measuring the thickness of the calibration sample by the preset measuring method includes:
acquiring an electron energy loss spectrum of the calibration sample corresponding to a directional line scanning path along the directional line scanning direction;
and calculating the thickness of the calibration sample corresponding to the directional line scanning path according to the electron energy loss spectrum.
6. The method of claim 1, wherein obtaining an absorbance-thickness relationship curve from the absorbance and thickness of the calibration sample comprises:
and fitting the absorptivity and the thickness of the calibration sample to obtain a relation curve of absorptivity and thickness.
7. The method for measuring the thickness according to claim 1, wherein the obtaining of the absorption rate of the sample to be measured includes:
acquiring a TEM image of a sample to be detected output by a transmission electron microscope;
and obtaining the absorption rate of the sample to be detected according to the gray value of the TEM image of the sample to be detected.
8. A thickness measurement system, comprising:
the acquisition module is used for acquiring a TEM image of the calibration sample output by the transmission electron microscope; obtaining the absorptivity of the calibration sample according to the gray value of the TEM image of the calibration sample;
the preset measuring module is used for measuring the thickness of the calibration sample by a preset measuring method;
the function generation module is used for obtaining an absorptivity-thickness relation curve according to the absorptivity and the thickness of the calibration sample;
the acquisition module is also used for acquiring the absorptivity of the sample to be detected;
and the calculation module is used for calculating the thickness of the sample to be detected according to the absorption rate-thickness relation curve and the absorption rate of the sample to be detected.
9. The thickness measurement system of claim 8,
the acquisition module is specifically used for performing directional line scanning on the TEM image of the calibration sample to obtain a gray value corresponding to a directional line scanning path;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the gray value corresponding to the directional line scanning path and the gray value at the vacuum.
10. The thickness measurement system of claim 9,
the acquisition module is specifically used for obtaining the transmittance of the calibration sample corresponding to the directional line scanning path according to the ratio of the gray value corresponding to the directional line scanning path to the gray value at the vacuum position;
and obtaining the absorptivity of the calibration sample corresponding to the directional line scanning path according to the transmissivity.
11. The thickness measurement system of claim 9,
the preset measurement method comprises an electron energy loss spectrum measurement method and a TEM section image measurement method.
12. The thickness measurement system according to claim 11, wherein in a case that the preset measurement method is an electron energy loss spectrum measurement method, the preset measurement module is specifically configured to obtain an electron energy loss spectrum of the calibration sample corresponding to a scan path of the directional line along the scan direction of the directional line;
and calculating the thickness of the calibration sample corresponding to the directional line scanning path according to the electron energy loss spectrum.
13. The thickness measurement system of claim 8,
the function generation module is specifically used for fitting the absorptivity and the thickness of the calibration sample to obtain an absorptivity-thickness relation curve.
14. The thickness measurement system of claim 8,
the acquisition module is specifically used for acquiring a TEM image of a sample to be detected output by the transmission electron microscope;
and obtaining the absorption rate of the sample to be detected according to the gray value of the TEM image of the sample to be detected.
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