阅读说明：本技术 带电粒子射线装置和试样的厚度测定方法
(Charged particle beam device and method for measuring thickness of sample
) 是由 佐藤高广
野间口恒典 于 2017-06-13 设计创作，主要内容包括：一种带电粒子射线装置,具备：存储部,其存储有显示前述带电粒子射线照射于配置在试样上的层时得到的带电粒子信号的强度或强度比与前述层的厚度的关系的关系信息；以及运算部,其使用前述关系信息与前述带电粒子信号的强度或强度比,算出前述层的厚度作为前述试样的厚度。(A charged particle beam device is provided with: a storage unit that stores relationship information showing a relationship between an intensity or an intensity ratio of a charged particle signal obtained when the charged particle beam is irradiated to a layer disposed on a sample and a thickness of the layer; and a calculation unit that calculates the thickness of the layer as the thickness of the sample using the relationship information and the intensity or intensity ratio of the charged particle signal.)
1. A charged particle beam device is provided with:
a charged particle beam column that irradiates a charged particle beam;
a sample support mechanism for supporting a sample to be measured;
a detector for detecting a charged particle signal obtained when the charged particle beam is irradiated on the sample;
a storage unit that stores relationship information indicating a relationship between an intensity or an intensity ratio of a charged particle signal obtained when a layer disposed on the sample is irradiated with the charged particle beam and a thickness of the layer; and
and a calculation unit that calculates the thickness of the layer as the thickness of the sample using the relationship information and the intensity or intensity ratio of the charged particle signal.
2. A charged-particle beam apparatus according to claim 1, wherein the intensity ratio of the charged-particle signal is a value obtained by dividing each signal intensity value by a signal intensity value in a range in which the signal intensity is constant.
3. The charged-particle beam apparatus as set forth in claim 1 wherein said layer is carbon, tungsten, platinum or an oxide film.
4. The charged-particle beam apparatus according to claim 1, wherein the storage unit stores the relationship information in accordance with an energy of the charged-particle beam.
5. The charged-particle beam apparatus according to claim 1, wherein the storage unit stores the relationship information for each incident angle of the charged-particle beam.
6. The charged-particle beam apparatus according to claim 1, wherein the storage unit stores the relationship information for each type of the charged-particle beam.
7. The charged-particle beam apparatus according to claim 1, wherein the storage unit stores the relationship information for each signal type of the detection target obtained by the detector.
8. The charged-particle beam apparatus according to claim 1, wherein the storage unit stores the relationship information in accordance with a method of manufacturing the layer, a composition of the layer, or crystallinity of the layer.
9. The charged-particle beam device according to claim 1, further comprising a functional member for forming the layer on the surface of the sample using the charged-particle beam and a compound gas.
10. The charged-particle beam apparatus according to claim 1, wherein the sample has:
a shape having a uniform thickness in a direction parallel to the longitudinal direction of the sample,
A shape in which the thickness changes continuously or discontinuously in a direction parallel to the longitudinal direction of the specimen, or
A shape in which the thickness changes continuously or discontinuously in a direction parallel to the short side direction of the sample.
11. The charged-particle beam apparatus as claimed in claim 1, wherein the charged-particle signal is a signal for detecting (1) transmitted electrons, (2) reflected electrons, (3) secondary charged particles, or (4) tertiary charged particles caused by the transmitted electrons, the reflected electrons, or the secondary charged particles.
12. A composite charged particle beam device is provided with:
an ion beam column for irradiating an ion beam;
an electron beam column for irradiating an electron beam;
a sample support mechanism for supporting a sample;
a detector for detecting a charged particle signal obtained when the sample is irradiated with the electron beam;
a functional member that forms a layer on the surface of the sample using the ion beam or the electron beam and a compound gas;
a storage unit that stores relationship information indicating a relationship between an intensity or an intensity ratio of a charged particle signal obtained when the layer is irradiated with the electron beam and a thickness of the layer; and
and a calculation unit that calculates the thickness of the layer as the thickness of the sample using the relationship information and the intensity or intensity ratio of the charged particle signal.
13. A method for measuring the thickness of a sample, comprising:
a step of forming a layer on the surface of the sample,
a step of processing the sample using an ion beam,
a step of irradiating the processed sample with an electron beam,
a step of detecting a charged particle signal when the layer is irradiated with the electron beam, and
and calculating the thickness of the processed sample using relationship information indicating a relationship between the intensity or intensity ratio of the charged particle signal and the thickness of the layer.
14. The method for measuring the thickness of a sample according to claim 13, wherein the processed sample has:
a shape having a uniform thickness in a direction parallel to the longitudinal direction of the sample,
A shape in which the thickness changes continuously or discontinuously in a direction parallel to the longitudinal direction of the specimen, or
A shape in which the thickness changes continuously or discontinuously in a direction parallel to the short side direction of the sample.
Technical Field
The present invention relates to a charged particle beam apparatus and a method for measuring a thickness of a sample.
Background
A Focused Ion Beam (FIB) device, which is one type of charged particle Beam device, performs micromachining by utilizing a sputtering phenomenon of target constituent atoms generated when a sample is irradiated with a Focused Ion Beam. Recently, a device in which a Scanning Electron Microscope (SEM) or a Scanning Transmission Electron Microscope (STEM) is combined with an FIB device has been manufactured. These apparatuses are designed so that the FIB irradiation axis and the electron beam irradiation axis intersect at the same point in the apparatus, and have an advantage that SEM observation of the FIB-processed cross section can be performed without moving the sample.
The FIB device is used for cross-sectional processing for SEM observation, and for sample preparation for STEM and Transmission Electron Microscope (TEM) observation. The TEM method and the STEM method are methods for observing the internal structure of a thin film sample by irradiating the thin film sample with high-speed electron beams and imaging the transmitted electron beams. In these methods, since transmission electrons are used for imaging, a thin film is used as an observation sample. The generally recommended sample thickness is 100nm or less at an acceleration voltage of 200 kV. However, in the production of semiconductor thin film samples, miniaturization of device structures is advancing year by year, and therefore, it is sometimes necessary to process the thin film thickness to about several tens of nm. In the preparation of samples for TEM and STEM observation, a technique for measuring the thickness of a thin film sample with high accuracy in FIB processing is required.
The secondary electrons generated in FIB milling have information reflecting the surface structure of the sample. An image in which the signal intensity of secondary electrons is two-dimensionally displayed simultaneously with FIB Scanning is called a Scanning Ion Microscope (SIM) image. The conventional method for measuring the thickness of a sample is to measure the thickness of the sample by SIM observation of a thin film sample from above. However, since the sample is observed from directly above, it is difficult to obtain information in the depth direction of the sample, and it is difficult to accurately measure the length of the target position. The lower resolution of the SIM image than the SEM image is also a cause of the decrease in measurement accuracy. A film thickness measurement method using electron beams is disclosed in patent document 1. Patent document 1 discloses a method for measuring a film thickness by calculating an intensity ratio of reflected electrons in a film thickness measurement region and a reference sample.
Disclosure of Invention
Problems to be solved by the invention
The method of patent document 1 requires a reference sample to be prepared in addition to the sample to be measured for film thickness, and has some problems in order to be carried out. First, the reference sample must be of the same material and composition as the film thickness measurement region, and have a known thickness. When the sample has a single structure or a single composition, the method of patent document 1 can be applied. However, when the structure or composition inside the sample is not uniform, the electron beam intensity varies from observation region to observation region, and therefore the method of patent document 1 cannot be applied. Second, in order to improve the film thickness measurement accuracy, it is necessary to prepare 2 or more reference samples having different thicknesses. Since the semiconductor sample has only 1 defective portion, a plurality of reference samples cannot be prepared.
Therefore, hereinafter, a technique capable of measuring the thickness of a sample without preparing a reference sample is disclosed.
Means for solving the problems
For example, in order to solve the above problems, the structure described in the claims is adopted. The present application includes a plurality of methods for solving the above-described problems, and provides, for example, a charged particle beam apparatus including: a charged particle beam column that irradiates a charged particle beam; a sample support mechanism for supporting a sample to be measured; a detector for detecting a charged particle signal obtained when the charged particle beam is irradiated on the sample; a storage unit that stores relationship information indicating a relationship between an intensity or an intensity ratio of a charged particle signal obtained when a layer disposed on the sample is irradiated with the charged particle beam and a thickness of the layer; and a calculation unit that calculates the thickness of the layer as the thickness of the sample using the relationship information and the intensity or intensity ratio of the charged particle signal.
In addition, according to another example, there is provided a composite charged particle beam device including: an ion beam column for irradiating an ion beam; an electron beam column for irradiating an electron beam; a sample support mechanism for supporting a sample; a detector for detecting a charged particle signal obtained when the sample is irradiated with the electron beam; a functional member for forming a layer on the surface of the sample using the ion beam or the electron beam and a compound gas; a storage unit that stores relationship information indicating a relationship between an intensity or an intensity ratio of a charged particle signal obtained when the layer is irradiated with the electron beam and a thickness of the layer; and a calculation unit that calculates the thickness of the layer as the thickness of the sample using the relationship information and the intensity or intensity ratio of the charged particle signal.
Further, according to another example, there is provided a method of measuring a thickness of a sample, including: forming a layer on the surface of the sample; processing the sample by using an ion beam; irradiating the processed sample with an electron beam; detecting a charged particle signal when the layer is irradiated with the electron beam; and calculating the thickness of the processed sample using relationship information indicating a relationship between the intensity or intensity ratio of the charged particle signal and the thickness of the layer.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to measure the thickness of a sample without preparing a reference sample. Further features of the present invention will be described with reference to the description and drawings. Problems, configurations, and effects other than those described above will be apparent from the following description of embodiments.
Drawings
Fig. 1 is a schematic diagram showing a configuration of a charged particle beam apparatus according to an embodiment.
FIG. 2A is a diagram showing a sample and a deposited film on the sample according to an example.
FIG. 2B is a diagram showing a sample and a deposited film on the sample according to an embodiment.
FIG. 2C is a diagram showing a sample and a deposited film on the sample according to an example.
FIG. 2D is a diagram showing a sample and a deposited film on the sample according to an example.
FIG. 3A is a cross-sectional charged particle beam image of a sample having a deposited film according to an embodiment.
FIG. 3B is a flat charged particle beam image of a sample having a deposited film according to one embodiment.
FIG. 3C is a line profile of signal intensity extracted from the direction of the arrow in the deposited film of FIG. 3A.
Fig. 4A is a diagram illustrating a method of measuring the thickness of a sample according to an embodiment.
Fig. 4B is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
Fig. 4C is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
Fig. 4D is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
FIG. 4E is a line profile of signal strength for one embodiment.
FIG. 4F is a line profile of signal strength ratios for one embodiment.
Fig. 5 is a diagram showing relationship information according to an embodiment.
Fig. 6A is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
Fig. 6B is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
Fig. 6C is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
Fig. 7 is a schematic diagram showing a configuration of a charged particle beam apparatus according to an embodiment.
Fig. 8 is a schematic diagram showing a configuration of a composite charged particle beam device according to an embodiment.
Fig. 9A is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
Fig. 9B is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
Fig. 9C is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
Fig. 9D is a diagram illustrating a method for measuring the thickness of a sample according to an embodiment.
FIG. 10A is a view showing a sample and a deposited film on the sample according to an example.
FIG. 10B is a diagram showing a sample and a deposited film on the sample according to an example.
FIG. 10C is a view showing a sample and a deposited film on the sample according to an example.
FIG. 10D is a view showing a sample and a deposited film on the sample according to an example.
Fig. 11 is a diagram showing relationship information according to an embodiment.
Fig. 12 is a diagram showing relationship information according to an embodiment.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings. It is to be noted, however, that the appended drawings illustrate specific embodiments in accordance with the principles of the invention and are therefore to be considered illustrative of the invention and not restrictive.
The following examples relate to a charged particle beam apparatus having a function of measuring the thickness of a sample for observation. The charged particle beam device is a device using charged particles secondarily generated by scanning a charged particle beam on a surface of a sample. Examples of the charged particle beam device include an electron microscope, an electron beam plotter, an ion processing device, and an ion microscope. The following embodiments can be applied to the charged particle beam device described above.
Fig. 1 is a schematic diagram showing a configuration of a charged particle beam apparatus according to an embodiment. A charged particle beam device is provided with: a charged particle beam column 1; a sample support mechanism 3 for supporting the sample 2; a detector 6 for detecting a charged particle signal 5 obtained when the sample 2 is irradiated with the charged particle beam 4; a storage unit 8 for storing the intensity or intensity ratio of the charged particle signal 5 obtained when the charged particle beam 4 is irradiated to a layer (e.g., a deposited film) 7 disposed on the sample 2 to be measured, for each thickness of the layer 7; and a calculation unit 9 for calculating the thickness of the layer 7 as the thickness of the sample 2 using the information in the storage unit 8 and the charged particle signal detected by the detector 6.
The charged particle beam column 1 comprises charged particle beam optics. As one example, the charged particle beam optical system includes a charged particle beam source that emits a charged particle beam, and an extraction electrode, a condenser lens, a deflection electrode, an objective lens, and the like. The charged particle beam column 1 may include other lenses, electrodes, and detectors, and may be partially different from the above, and the configuration of the charged particle beam optical system is not limited to this.
The arithmetic unit 9 may be implemented by a general-purpose computer, or may be implemented as a function of a program running on the computer. That is, the processing of the arithmetic Unit 9 may be realized by storing the program codes in a memory and executing the program codes by a processor such as a CPU (central processing Unit).
In this example, a layer 7 for thickness measurement is disposed on a sample 2 to be measured. Hereinafter, the layer 7 will be referred to as a deposited film, but any layer for measuring the thickness may be formed on the sample 2 to be measured. The charged particle beam apparatus of the present embodiment can calculate the thickness of the deposited film 7 to determine the thickness of the sample 2.
In this embodiment, the deposition film 7 is deposited outside the charged particle beam device. The deposition film 7 may be deposited in the charged particle beam device, and this configuration will be described below. Fig. 2A to 2D are schematic diagrams of a sample 2 and a deposition film 7 disposed on the sample 2. The deposited film 7 is a carbon, tungsten, platinum, or oxide film. The deposited film 7 is not limited to the above-described material, as long as it is a conductive material or an insulating material.
The deposition film 7 may be disposed at any position with respect to the sample 2. In fig. 2A, the deposited film 7 is disposed on the XY plane of the upper portion 2A of the sample 2. In fig. 2A, for example, the charged particle ray 4 is incident from the XZ plane. The incident angle 10 of the charged particle beam 4 with respect to the XZ plane is arbitrary. In fig. 2B, the deposited film 7 is disposed on the XY plane of the lower portion 2B of the sample 2. In fig. 2C, the deposited film 7 is disposed on the YZ plane of the left side surface 2C of the sample 2. In fig. 2D, the deposited film 7 is disposed on the YZ plane of the right side surface 2D of the sample 2.
The concept of measuring the thickness of sample 2 will be described with reference to fig. 3A to 3C. Fig. 3A is a cross-sectional charged particle beam image of the sample 2 having the deposited film 7, and fig. 3B is a planar charged particle beam image of the sample 2. In this example, the thickness of sample 2 gradually becomes thinner from the left side to the right side on the drawing. The direction of change in thickness is not limited thereto. In fig. 3A, the contrast of the deposited film 7 is dark on the left side and lighter toward the right side. The brighter the contrast, the thinner the thickness of the deposited film 7.
Fig. 3C is a line profile 11 of the signal intensity extracted in the direction of the arrow (see fig. 3A) for the deposited film 7. In the line profile 11, the vertical axis represents the signal intensity (brightness), and the horizontal axis represents the change in signal intensity when the distance from the left end of fig. 3A and 3B (with the left end as the origin) is taken. There is a region of constant luminance on the left side of fig. 3C, and the luminance is increased toward the right side. In this embodiment, the thickness of the sample 2 is measured by using the property that the brightness of the charged particle beam image changes depending on the thickness of the deposited film 7. With this configuration, the thickness can be measured without depending on the composition, material, and the like of the sample 2. Further, since the deposited film 7 on the sample 2 is used, it is not necessary to prepare a reference sample different from the sample 2 to measure the thickness of the sample 2.
An example of measuring the thickness of sample 2 is shown with reference to fig. 4A to 4F. As shown in fig. 4A, the sample 2 having a wedge shape is used here, and the deposition film 7 is disposed on the XY plane of the upper portion 2a of the sample 2.
As shown in fig. 4B, the sample 2 is rotated about the Z axis, and the surface S1 of the sample 2 is observed from the X axis direction using the charged particle beam 4, whereby the length L1 is measured. The incident angle of the charged particle beam 4 to the ZY plane is arbitrary. As another example, the charged particle beam 4 may be used as viewed from the-Z direction.
Next, as shown in fig. 4C, the sample 2 is rotated around the Z axis, and the surface S2 of the sample 2 is observed using the charged particle beam 4, whereby the length L2 is measured. The incident angle of the charged particle beam 4 to the ZY plane is arbitrary. As another example, the charged particle beam 4 may be used as viewed from the-Z direction.
Next, as shown in fig. 4D, the sample 2 is rotated around the Z axis, and the surface S3 of the sample 2 is observed using the charged particle beam 4. The arithmetic unit 9 calculates a line profile 11 of the signal intensity in the X direction (arrow direction) with respect to the deposited film 7 of the charged particle radiation image obtained here.
Fig. 4E shows an example of the line profile 11 of the signal intensity. In the spectral line profile 11 of fig. 4E, the vertical axis represents the signal intensity of the charged particle beam image on the deposited film 7, and the horizontal axis represents the distance from the left end of the sample 2 (left end of fig. 4D). Since the thickness at the left end was L1 and the thickness at the right end corresponded to L2, the signal intensity in the charged particle beam image corresponding to each thickness of the sample 2 was known.
The computing unit 9 may also use a range (W) in which the signal intensity does not change1) The intensity values of (a) normalize the line profile 11. Fig. 4F is an example of a line profile 11 of signal intensity ratios. In the line profile 11 of FIG. 4F, the vertical axis is the division of the respective signal intensity values by W1The horizontal axis of the intensity ratio obtained by the signal intensity values in the range is the distance from the left end (left end in fig. 4D) of the sample 2. From the line profile 11, the intensity ratio corresponding to each thickness of the sample 2 is known. In observation using a charged particle beam apparatus, the absolute value of the obtained signal intensity changes with the lapse of time. Therefore, it is preferable to use information indicating the relative intensity such as the signal intensity ratio.
The calculation unit 9 stores relationship information indicating a relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 in the storage unit 8. Fig. 5 is an example of a table showing a relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7. The above-described relationship information is expressed by a table structure, but may not be expressed by a data structure based on a table. Hereinafter, the relationship information is simply referred to as "relationship information" to indicate independence from the data structure.
Fig. 6A to 6C are diagrams illustrating a method of measuring the thickness of the sample 2 using the previously prepared relationship information as described above. Here, a case will be described in which the storage unit 8 stores relationship information indicating a relationship between the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7.
As shown in fig. 6A, the sample 2 to be measured is disposed on the sample support mechanism 3. The structure of the sample support mechanism 3 is not limited to this as long as it can support the sample 2. The sample 2 may be a parallel flat plate or a wedge, and in this embodiment, a wedge-shaped sample 2 is used.
Next, as shown in fig. 6B, the arithmetic unit 9 obtains a charged particle radiation image of the surface S3 of the sample 2 from the charged particle signal 5 obtained when the sample 2 is irradiated with the charged particle radiation 4.
Then, as shown in fig. 6C, the arithmetic unit 9 obtains the signal intensity (I) of the deposited film 7 in the vicinity of the region where the thickness is to be measured, using the obtained charged particle beam imagea) And the signal intensity (I) of the deposited film 7 from the region where the signal intensity is constantb) Determining the intensity ratio (I)a/Ib). The computing unit 9 calculates the intensity ratio (I) from the relationship information stored in the storage unit 8 in advancea/Ib) The thickness of the corresponding deposited film 7 was defined as the thickness of the sample 2.
When the storage unit 8 stores information on the relationship between the signal intensity and the thickness of the deposited film 7, the calculation unit 9 can calculate the signal intensity (I) in the vicinity of the region where the thickness is measureda) The thickness of the corresponding deposited film 7 was defined as the thickness of the sample 2.
The charged particle beam apparatus of the above embodiment includes: a charged particle beam column 1 that irradiates a charged particle beam 4; a sample support mechanism 3 for supporting a sample 2 to be measured; a detector 6 for detecting a charged particle signal 5 obtained when the sample 2 is irradiated with the charged particle beam 4; a storage unit 8 that stores relationship information indicating a relationship between the intensity or intensity ratio of the charged particle signal 5 obtained when the charged particle beam 4 is irradiated to the deposited film 7 disposed on the sample 2 and the thickness of the deposited film 7; and a calculation unit 9 for calculating the thickness of the deposited film 7 as the thickness of the sample 2, using the relationship information and the signal intensity of the charged particle signal 5 detected by the detector 6. According to this configuration, since the deposited film 7 disposed on the sample 2 is used as a layer for measuring the thickness, it is not necessary to prepare a reference sample different from the sample 2 for measuring the thickness of the sample 2.
Fig. 7 is a schematic diagram showing a configuration of a charged particle beam apparatus according to an embodiment. The charged particle beam apparatus of the present embodiment includes a deposited film forming functional member 12 for forming a deposited film 7 on a sample 2. By spraying the compound gas near the charged particle beam irradiation region on the surface of the sample 2, the deposited film 7 can be formed on the sample 2. When the sample 2 is irradiated with the primary charged particle beam 4, secondary charged particles are generated. The secondary charged particles contribute to decomposition of the compound gas, and the compound gas is separated into a gas component and a solid component. The gas component is evacuated. The solid matter is deposited on the surface of the sample 2 to form a deposited film 7. The deposited film forming function member 12 is, for example, a compound gas supply device that supplies a compound gas as a raw material of the deposited film 7 to the periphery of the charged particle beam irradiation region. The deposited film 7 is a carbon, tungsten, platinum, or oxide film. The deposited film 7 is not limited to the above-described material, as long as it is a conductive material or an insulating material.
Fig. 8 is a schematic diagram showing a configuration of a composite charged particle beam device according to an embodiment. The composite charged particle beam device of the present embodiment includes: an ion beam column 13 for irradiating an ion beam 14; an electron beam column 15 for irradiating an electron beam 16; a deposited film forming function part 12 for forming a deposited film 7 on the sample 2 by using an ion beam 14 irradiated from an ion beam column 13 or an electron beam 16 irradiated from an electron beam column 15; the other constitution is the same as that of fig. 1.
In this embodiment, the electron beam column 15 is disposed in a direction perpendicular to a surface of the sample support mechanism 3 on which the sample 2 is disposed (hereinafter, the disposition surface of the sample 2), and the ion beam column 13 is disposed in a direction inclined with respect to the disposition surface of the sample 2. The electron beam column 15 may be arranged in a direction inclined with respect to the arrangement plane of the sample 2, and the ion beam column 13 may be arranged in a direction perpendicular to the arrangement plane of the sample 2. The angle formed by the two columns 13, 15 is greater than 0 degrees and less than 180 degrees.
Fig. 9A to 9D are diagrams illustrating a method of processing and measuring a thickness of a sample 2 using a composite charged particle beam device. Fig. 9A shows a measurement target sample 2. As shown in fig. 9B, the deposition film 7 is formed on the sample 2 using the ion beam 14 or the electron beam 16 and the compound gas. Next, as shown in fig. 9C, the sample 2 is processed by the ion beam 14 to thin the sample 2. Next, as shown in fig. 9D, the deposition film 7 is irradiated with an electron beam 16. Then, the calculation unit 9 calculates the thickness of the deposited film 7 as the thickness of the sample 2 from the relationship information stored in advance in the storage unit 8, using the obtained signal intensity. The process of fig. 9C and 9D is repeated until the target specimen thickness is reached. According to this configuration, the sample 2 can be processed by the ion beam 14 while measuring the thickness of the sample 2.
Fig. 10A to 10D show examples of the sample 2 and the deposited film 7. In fig. 10A, sample 2 is a flat plate shape having a uniform thickness in a direction parallel to the longitudinal direction of sample 2. The deposited film 7 is deposited on the upper portion 2a of the sample 2. In this configuration, the storage unit 8 stores information on the relationship between the signal intensity and the thickness of the deposited film 7, and the calculation unit 9 may calculate the thickness of the deposited film 7 corresponding to the signal intensity of the deposited film 7 as the thickness of the sample 2 from the relationship information.
In fig. 10B, sample 2 has a wedge shape in which the thickness continuously changes in a direction parallel to the longitudinal direction of sample 2. The deposited film 7 is deposited on the upper portion 2a of the sample 2. With this configuration, the thickness of sample 2 can be obtained by the method described with reference to fig. 6A to 6C.
In fig. 10C, sample 2 has a shape in which the thickness is discontinuous in a direction parallel to the longitudinal direction of sample 2. Specifically, sample 2 has a 1 st portion 21 and a 2 nd portion 22 having a thickness greater than that of the 1 st portion 21. The deposited film 7 is deposited on the upper portion 2a of the sample 2. The thickness of the deposited film 7 deposited on the 2 nd part 22 of the sample 2 is within a range where the signal intensity is constant (i.e., W in FIG. 4E)1) Is measured. In this configuration, the storage unit 8 stores information on the relationship between the signal intensity ratio and the thickness of the deposited film 7, and the calculation unit 9 can calculate the thickness of the 1 st portion 21 of the sample 2 from the intensity ratio between the signal intensity of the deposited film 7 on the 2 nd portion 22 and the signal intensity of the deposited film 7 on the 1 st portion 21. The calculation unit 9 may calculate the thickness of the 1 st portion 21 of the sample 2 from the information on the relationship between the signal intensity and the thickness of the deposited film 7.
In fig. 10D, sample 2 has a wedge-shaped current state in which the thickness continuously changes in a direction parallel to the short side direction of sample 2. The deposited film 7 is deposited on the upper portion 2a of the sample 2. In this configuration, for example, the calculation unit 9 may calculate the thickness of the sample 2 from the intensity ratio of the signal intensity at the lower end 7b of the deposited film 7 to the signal intensity at the upper end 7a of the deposited film 7. The calculation unit 9 may calculate the thickness of the sample 2 from the relationship between the signal intensity and the thickness of the deposited film 7. Further, the sample 2 may have a shape in which the thickness discontinuously changes in the direction parallel to the short side direction of the sample 2.
Fig. 11 shows an example of the relationship information stored in the storage unit 8. The storage unit 8 may store the relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 for each energy of the charged particle beam 4. The energy of the charged particle beam 4 is, for example, an acceleration voltage. Since the extraction rate of the charged particle signal 5 changes depending on the acceleration voltage, the contrast of the deposited film 7 varies even with the same sample thickness. The calculation unit 9 stores in advance, in the storage unit 8, relationship information indicating a relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 for a plurality of different acceleration voltages. The calculation unit 9 can select the relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 from the relationship information based on the set acceleration voltage, and calculate the thickness of the deposited film 7 as the thickness of the sample 2.
Fig. 12 shows an example of the relationship information stored in the storage unit 8. The storage unit 8 may store the relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 at the angle of incidence of the charged particle beam 4. If the incident angle 10 of the charged particle beam 4 to the deposited film 7 changes, the relative thickness of the deposited film 7 changes, and therefore the contrast of the deposited film 7 becomes different. The calculation unit 9 stores in advance, in the storage unit 8, relationship information indicating a relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 at a plurality of different incidence angles. The calculation unit 9 can select the relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 from the relationship information based on the incident angle, and calculate the thickness of the deposited film 7 as the thickness of the sample 2. In the example of fig. 12, the storage unit 8 stores the relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 for each of the energy (acceleration voltage) of the charged particle beam 4 and the incident angle of the charged particle beam 4.
As another example, the relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 may be changed depending on the type of the charged particle beam 4. For example, the charged particle ray 4 is a beam of one selected from gallium, gold, silicon, hydrogen, helium, neon, argon, xenon, oxygen, nitrogen, or carbon. The signal strength of the charged particle signal 5 may vary depending on the kind of beam. Therefore, the storage unit 8 may store the relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 for each type of the charged particle beam 4.
The charged particle signal 5 may be a signal for detecting (1) transmitted electrons, (2) reflected electrons, (3) secondary charged particles, or (4) tertiary charged particles caused by the transmitted electrons, the reflected electrons, or the secondary charged particles. The relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 may vary depending on the type of the signal to be detected obtained by the detector 6. Therefore, the storage unit 8 may store the relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 for each type of signal to be detected.
The relationship between the signal intensity or the signal intensity ratio of the charged particle signal 5 and the thickness of the deposited film 7 may vary depending on the method of manufacturing the deposited film 7, the composition of the deposited film 7, the crystallinity of the deposited film 7, and the like. For example, the signal intensity of the charged particle signal 5 can be changed by the deposition of the deposition film 7 by the deposition film forming functional member 12 or by the deposition of the deposition film on the sample 2 outside the charged particle beam device. The signal intensity of the charged particle signal 5 also varies depending on the composition of the deposited film 7, the crystallinity of the deposited film 7, and the like. Therefore, the storage unit 8 may store the relationship between the signal intensity or the signal intensity ratio of the charged-particle signal 5 and the thickness of the deposited film 7 for each method of manufacturing the deposited film 7, the composition of the deposited film 7, or the crystallinity of the deposited film 7.
The embodiments of fig. 11 and 12 can be applied to both the charged particle beam device of fig. 7 and the composite charged particle beam device of fig. 8.
As described above, in the above embodiment, the relationship between the contrast of the deposited film 7 in the charged particle beam image and the thickness of the deposited film 7 on the sample 2 is made into a database, and the database is stored in the storage unit 8. The calculation unit 9 can calculate the thickness of the sample 2 from the database. The charged particle beam apparatus can measure the thickness of the target sample 2 with high accuracy from the relationship between the thickness of the sample 2 and the signal intensity or signal intensity ratio of the charged particle signal 5 obtained when the charged particle beam 4 is irradiated onto the deposition film 7. This makes it possible to provide a thin film sample suitable for TEM and STEM observation.
The present invention is not limited to the above-described embodiments, and various modifications are also included. The above-described embodiments are examples explained in detail for the purpose of facilitating understanding of the present invention, and are not limited to having all of the described configurations. Further, a part of the configuration of one embodiment may be replaced with the configuration of another embodiment. In addition, the configuration of another embodiment may be added to the configuration of one embodiment. Further, other configurations may be added, removed, and replaced with a part of the configurations of the embodiments.
The functions of the arithmetic unit 9 may be implemented by hardware by designing a part or all of the functions in an integrated circuit, for example. The above-described configurations, functions, and the like may be realized by software by interpreting and operating a program for realizing each function by a processor. Information of programs, tables, files, and the like that implement the functions may be stored in various types of non-transitory computer readable media. As the non-transitory computer-readable medium, for example, a flexible disk, a CD-ROM, a DVD-ROM, a hard disk, an optical disk, a magneto-optical disk, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
In the above embodiments, the control lines and the information lines are assumed to be necessary for the description, and not all the control lines and the information lines are necessarily displayed on the product. All the components may be connected to each other.
Description of the symbols
1 charged particle beam column
2 test piece
3 sample supporting mechanism
4 charged particle beam
5 charged particle signal
6 Detector
7 layers (Stacking film)
8 storage part
9 arithmetic unit
10 incident angle
11 line profile
12 deposition film-forming functional member
13 ion beam column
14 ion beam
15 electron beam column
16 electron beams.
