Data acquisition device, data correction device, data correction method, program, and recording medium

Abstract

To provide a technique for acquiring information not only on changes in the surface of a crystal but also on changes in its interior in the unit of seconds.SOLUTION: A data acquisition device (30) includes an acquisition part (31) for acquiring first measurement data which are time-lapse measurement data obtained with an X-ray crystal truncation rod scattering measurement device concurrently with second measurement data which are time-lapse measurement data obtained with a reflection high-speed electron diffraction device, and a correction part (32) for time-correcting the first measurement data using the second measurement data.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a data acquisition device, a data correction device, a data correction method, a program, and a recording medium.

Background Art

[0002] Examining the state of crystal growth of a semiconductor thin film or the like is not only useful for elucidating the mechanism involved in thin film growth, but also an indispensable technique for precisely controlling the quality of the thin film. As a method for examining the state of crystal growth, for example, synchrotron radiation crystal truncation rod scattering described in Non-Patent Document 1 and reflection high energy electron diffraction described in Non-Patent Document 2 are known as conventional techniques.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The method using crystal truncation rod scattering has the feature that not only information on the thin film growth surface can be obtained at the atomic scale, but also information such as the atomic positions inside the thin film growth surface can be obtained simultaneously. However, since it takes more than 10 minutes for measurement, it is difficult to observe in situ the thin film growth surface that changes every moment. On the other hand, the method using reflection high energy electron diffraction can measure the changes in the thin film growth surface at a high speed on a time scale of seconds, but the information obtained is limited to the vicinity of the surface such as the unevenness of the growth surface.

[0005] One aspect of the present invention aims to provide a technique for acquiring information on internal changes as well as changes on the surface of a crystal in seconds.

Means for Solving the Problems

[0006] In order to solve the above problems, a data acquisition device according to one aspect of the present invention includes an acquisition unit that acquires in parallel first measurement data that is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device and second measurement data that is time-series measurement data obtained by a reflection high energy electron diffraction device, and a correction unit that corrects the first measurement data in terms of time using the second measurement data.

[0007] In order to solve the above problems, a data correction method according to one aspect of the present invention includes a first acquisition step of acquiring first measurement data that is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device, a second acquisition step of acquiring second measurement data that is time-series measurement data obtained by a reflection high energy electron diffraction device and that is data acquired in parallel with the first measurement data, and a correction step of correcting the first measurement data in terms of time using the second measurement data.

[0008] A data correction device according to one aspect of the present invention includes: a data acquisition unit that acquires first measurement data which is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device, and second measurement data which is data acquired in parallel with the first measurement data and is time-series measurement data obtained by a reflection high-energy electron diffraction device; and a data correction unit that corrects the first measurement data in terms of time using the second measurement data.

[0009] A data acquisition device according to one aspect of the present invention may be realized by a computer. In this case, a control program for realizing the data acquisition device by operating a computer as each part (software element) included in the data acquisition device, and a computer-readable recording medium on which the program is recorded also fall within the scope of the present invention.

Advantages of the Invention

[0010] According to one aspect of the present invention, it is possible to provide a technique for acquiring information on changes not only on the surface of a crystal but also inside the crystal in units of seconds.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

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Figure 7

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Figure 10

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Figure 12

Figure 13

Mode for Carrying Out the Invention

[0012] 〔Embodiment 1〕 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Before that, the problems of the prior art will be described in detail. FIG. 13 is an example of a graph showing the surface index L-dependence of synchrotron radiation crystal truncation rod scattering (hereinafter, also simply referred to as "CTR"). The vertical axis of the graph is the intensity of scattering (the unit is arbitrary), and the horizontal axis indicates the surface index L. The circles in the figure are measured values, and the solid line is a line obtained by fitting the measured values with X-ray scattering theory.

[0013] Here, the plane indices L used in this specification will be described. The plane indices are indices indicating the incident angle of the radiation (X-rays) (the cross-sectional direction of the crystal), and in the case of a cubic crystal, etc., they are usually represented by three indices (HKL). In this specification, a cross-section represented by the plane indices (00L) is also referred to as the plane index L. As L increases, the spacing between crystal planes becomes narrower. This means that as L is larger, the atomic arrangement in a minute region can be examined. In other words, the plane index L indicates the index in the thickness direction of the crystal, L1 corresponds to the basic unit of the crystal, L2 corresponds to dividing L1 into two in the thickness direction of the crystal, and Ln corresponds to dividing L1 into n in the thickness direction of the crystal. Note that in the case of a hexagonal crystal, it may be represented by four indices such as (HKIL), but in this specification, even for a hexagonal crystal, it is described as (HKL).

[0014] The graph in Fig. 13 shows the data obtained by measuring the CTR while changing the plane index L while irradiating the substrate with the raw material. The plane index L is changed from 0.5 to 3. To acquire the CTR data, since a measurement time of at least about 1 second is required for one plane index L, when measuring by changing the plane index L from 0.5 to 3 in steps of 0.1, it takes about 10 minutes including the time for changing the incident angle of the radiation of the measuring device to change the plane index. In Fig. 13, four groups of measurement data are shown, and these are, in order from the bottom, data indicating the average surface state between 0 and 10 minutes, data indicating the average surface state between 10 and 20 minutes, data indicating the average surface state between 20 and 30 minutes, and data indicating the average surface state between 30 and 40 minutes. Thus, in the case of the CTR, the data of the surface state including the state inside near the surface is only acquired as average data between several minutes and about ten-odd minutes, and the state of crystal growth progressing in seconds cannot be examined.

[0015] (Surface state measurement system 1) Hereinafter, the surface state measurement system 1, data acquisition method M1, and data correction method M2 according to Embodiment 1 for solving the above-described problems will be described. FIG. 1 is a block diagram showing the configuration of the surface state measurement system 1 according to the present embodiment. As shown in FIG. 1, the surface state measurement system 1 includes a synchrotron radiation crystal truncation rod scattering measurement apparatus (hereinafter referred to as the "CTR measurement apparatus") 10, a reflection high energy electron diffraction measurement apparatus (hereinafter referred to as the "RHEED measurement apparatus") 20, and a data acquisition apparatus 30. The CTR measurement apparatus 10 is an apparatus that irradiates a crystal to be measured with X-rays having a relatively high energy (about several tens of KeV) and high intensity (about 10 12 photons / s) and measures the scattered light (scattered image). Note that it is preferable for the CTR measurement apparatus to use X-rays having a relatively high energy (about several tens of KeV) and high intensity (about 10 12 photons / s). Therefore, in the following embodiments, an example using a synchrotron radiation CTR measurement apparatus will be described, but an X-ray CTR measurement apparatus may also be used. The RHEED measurement apparatus 20 is an apparatus that irradiates a crystal to be measured with an electron beam and measures the diffraction line (diffraction image).

[0016] The data acquisition apparatus 30 includes an acquisition unit 31, a correction unit 32, an apparatus control unit 33, a processor 34, and a memory 35. The acquisition unit 31 acquires time-series measurement data from the CTR measurement apparatus 10. Specifically, the acquisition unit 31 acquires measurement data from the CTR measurement apparatus 10 for a continuous predetermined time. Further, the acquisition unit 31 acquires time-series measurement data from the RHEED measurement apparatus 20. Specifically, the acquisition unit 31 acquires measurement data from the RHEED measurement apparatus 20 for a continuous predetermined time. The acquisition unit 31 acquires the measurement data from the CTR measurement apparatus 10 and the measurement data from the RHEED measurement apparatus 20 in parallel in terms of time. Note that the measurement data from the CTR measurement apparatus 10 is also referred to as "first measurement data", and the measurement data from the RHEED measurement apparatus 20 is also referred to as "second measurement data".

[0017] The correction unit 32 corrects the first measurement data in terms of time using the second measurement data. Specifically, the correction unit 32 detects the time position of a specific point in the second measurement data, and corrects the first measurement data in terms of time based on the time position of the specific point. The time correction is for arranging a plurality of data measured at different measurement angles on a common time axis. The specific method of the time correction executed by the correction unit 32 will be described later, including the details of the specific point.

[0018] The apparatus control unit 33 controls the synchrotron radiation crystal truncation rod scattering measurement apparatus (CTR measurement apparatus) 10 and the reflection high-energy electron diffraction apparatus (RHEED measurement apparatus) 20. Specifically, the apparatus control unit 33 controls to change the position (orientation) of the measurement target, or change the synchrotron radiation incident angle of the CTR measurement apparatus 10, and change the position of the scattered light detector. Also, the apparatus control unit 33 controls to change the position (orientation) of the measurement target, or change the electron beam incident angle of the RHEED measurement apparatus 20. Note that, if necessary, the position of the diffraction image detector may be changed. Further, the apparatus control unit 33 controls to irradiate the raw material from the raw material irradiation apparatus 53 described later.

[0019] The memory 35 is composed of various volatile or non-volatile ROMs (Read Only Memories) or RAMs (Random Access Memories) and the like. Various programs are stored in the ROM. The various programs are, for example, a data acquisition program, a correction program, a control program for the CTR measurement apparatus 10, and a control program for the RHEED measurement apparatus 20.

[0020] The processor 34 realizes the functions as the acquisition unit 31, the correction unit 32, and the device control unit 33 by expanding and executing various programs stored in the ROM of the memory 35 in the RAM. The processor 34 can be configured using a general-purpose processor such as an MPU (Micro Processing Unit) or a CPU (Central Processing Unit). Further, the processor 34 may include a dedicated processor such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a PLD (Programmable Logic Device).

[0021] Note that the data acquisition device 30 may include an output unit (not shown) that outputs the corrected data to the outside. In that case, the output unit outputs the corrected data to a display or a personal computer via an output interface.

[0022] Figure 2 is a conceptual diagram of a method for measuring the surface state of a measurement target using the CTR measurement device 10 and the RHEED measurement device 20. Hereinafter, a method for acquiring data according to this embodiment will be described with reference to Figure 2.

[0023] As shown in FIG. 2, the measurement target 51 is, for example, gallium nitride (GaN) with its (0001) plane exposed on the surface. Gallium (Ga), which is the raw material, is irradiated in a gaseous state from the raw material irradiation device 53 in a relative position relationship facing the measurement target 51. In FIG. 2, the measurement target 51 and the raw material irradiation device 53 are arranged opposite to each other in the vertical direction, but the arrangement relationship between the two is not limited to this. For example, the measurement target 51 and the raw material irradiation device 53 may be arranged opposite to each other in the horizontal direction. The measurement target 51 is heated to a temperature of several hundred degrees and placed in a high-vacuum chamber. When gallium is irradiated onto the measurement target 51 in such an environment, the gallium irradiated in a gaseous state deposits on the surface of the measurement target 51 as crystals of gallium nitride or liquid gallium, and a growth layer (deposited layer) 52 is formed. In the case of this embodiment, the data acquired using the CTR measurement device 10 and the RHEED measurement device 20 is the measurement data of this growth layer 52. The method for acquiring the data is as follows.

[0024] Toward this growth layer 52, high-energy X-rays 56 (such as synchrotron radiation) are irradiated from the CTR measurement device 10, and the scattered light 57 is measured by a detector at predetermined time intervals. That is, for example, the measured value of the scattered light 57 for 1 second is accumulated to obtain one piece of scattered image data, and the measured value of the scattered light 57 for the next 1 second is accumulated to obtain the next piece of scattered image data. This is continued for a desired time.

[0025] The desired time is the time until the deposition amount of the raw material on the surface of the measurement target reaches a desired amount. That is, the desired time can be appropriately set according to the extent of the deposition amount to be analyzed. For example, the desired time may be the time until a plurality of atomic layers of the raw material are deposited on the surface of the measurement target 51. That is, the acquisition unit 31 continuously acquires the first measurement data and the second measurement data in parallel until a plurality of atomic layers are stacked on the surface of the measurement target 51 for each predetermined measurement angle.

[0026] In parallel with this acquisition of the CTR data, an electron beam 54 is irradiated from the RHEED measuring apparatus 20, and its diffraction line 55 is measured by a detector at predetermined time intervals. That is, for example, the measured values of the diffraction line 55 for one second are accumulated to obtain one piece of diffraction image data, and the measured values of the diffraction line 55 for the next one second are accumulated to obtain the next piece of diffraction image data. This is continued for a desired period of time. The predetermined time (for example, one second) in this case is preferably made the same as the predetermined time (for example, one second) used in the acquisition of the CTR data.

[0027] Note that the predetermined time does not have to be one second. As an example, the predetermined time can be selected in the range of about 0.1 second to several seconds. If this time is short, the accuracy of the information acquired during that time decreases, but the deposition state of the raw material can be examined with that short time resolution. If the predetermined time is lengthened, the accuracy of the information acquired during that time improves, but since it becomes average data, the time resolution deteriorates. By increasing the amount of information acquired per unit time, the predetermined time for obtaining a sufficient amount of information can be made shorter, and data can be acquired with a shorter (higher) time resolution.

[0028] The above measurements are continued for a desired period of time until the measurement for one plane index L (angle of incidence) is completed. Next, the plane index L is changed and the same measurement is repeated. By measuring all the desired plane indices L, CTR data (first measurement data) and RHEED data (second measurement data) can be obtained. After obtaining the CTR data and the RHEED data, the CTR data is corrected for time using the RHEED data.

[0029] (Data acquisition method M1) The above data acquisition method will be described with reference to FIG. 3. FIG. 3 is a flowchart showing the flow of the data acquisition method M1 in which the data acquisition apparatus 30 according to the present embodiment acquires measurement data and performs time correction. As shown in FIG. 3, the data acquisition method M1 includes steps S11 to S15.

[0030] In step S11, the apparatus control unit 33 sets the measurement angle of the measurement target. The measurement angle is associated with the above-described plane index L. As a method for setting the measurement angle, the orientation of the measurement target may be changed, or the X-ray emission angle of the CTR measurement apparatus 10 and the electron beam emission angle of the RHEED measurement apparatus 20 with respect to the measurement target may be changed. Additionally, if necessary, the position of the diffraction image detector may be changed.

[0031] Next, in step S12, the apparatus control unit 33 performs, in parallel in time, a measurement step of continuously measuring the RHEED diffraction line while irradiating the measurement target with the raw material and a measurement step of continuously measuring the CTR scattered light. That is, a first measurement step of acquiring first measurement data, which is time-series measurement data obtained by the synchrotron radiation crystal truncation rod scattering measurement apparatus, is performed. Also, a second measurement step of acquiring second measurement data, which is data acquired in parallel with the first measurement data and is time-series measurement data obtained by the reflection high energy electron diffraction apparatus, is performed. The measured data is acquired by the acquisition unit 31 and recorded in the memory 35. The measurement of the RHEED diffraction line and the CTR scattered light is executed by the apparatus control unit 33 controlling the CTR measurement apparatus 10 and the RHEED measurement apparatus 20.

[0032] Next, in step S13, the data acquisition device 30 determines whether all of the predetermined measurement angles have been measured. In step S13, if it is determined that all of the predetermined measurement angles have been measured (step S13: YES), the flow proceeds to step S14.

[0033] In step S14, the correction unit 32 time-corrects the CTR scattered light measurement data (first measurement data) using the RHEED diffraction line measurement data (second measurement data). The correction unit 32 records the corrected data in the memory 35. The detailed content and necessity of step S14 will be described later.

[0034] On the other hand, if it is determined in step S13 that not all predetermined measurement angles have been measured (step S13: NO), the process proceeds to step S15. In step S15, the raw material irradiation is stopped and the process waits until the surface of the substrate (measurement target) returns to the state before the raw material irradiation, and then returns to step S11.

[0035] The stop of the raw material irradiation is executed by the apparatus control unit 33 controlling the raw material irradiation device 53. By stopping the raw material irradiation, the raw material deposited on the substrate placed under high temperature and high vacuum vaporizes (desorbs) from the substrate, so that the surface of the substrate returns to the state before the raw material irradiation.

[0036] (Data correction method M2) The above step S14 is a step of time-correcting the CTR data. An explanation will be given as to why such correction is necessary. In the above-described data acquisition method M1, the CTR data is acquired while depositing the raw material on the substrate for each measurement angle. At each measurement angle, the raw material is first irradiated and deposited on a substrate in a state where nothing is deposited. Therefore, it may be considered that by performing such measurements at each measurement angle and integrating all the measurement results, the temporal changes in the deposition status on the surface and inside can be understood. However, even if the raw material irradiation conditions are kept constant, the flow of the raw material reaching the substrate is not necessarily constant, so the deposition status also varies. Therefore, the data at different measurement angles cannot be arranged on the same time axis. Therefore, it is necessary to correct the time of the data at each measurement angle according to the deposition status of the raw material so that they can be arranged on a common time axis.

[0037] Hereinafter, step S14 of acquiring the time-corrected data will be described in detail. FIG. 4 is a flowchart showing the flow of the data correction method M2 for time-correcting the data, which is executed by the correction unit 32. As shown in FIG. 4, the data correction method M2 includes steps S21 to S23.

[0038] First, in step S21, the correction unit 32 acquires (first acquisition step) the CTR data (first measurement data), which is the time-series measurement data obtained by the synchrotron radiation crystal truncation rod scattering measurement apparatus, from the memory 35. Further, the correction unit 32 acquires (second acquisition step) the RHEED data (second measurement data), which is the time-series measurement data obtained by the reflection high energy electron diffraction apparatus and is data acquired in parallel with the first measurement data, from the memory 35. Note that there is no particular precedence relationship between the first acquisition step and the second acquisition step, and either may be performed first or they may be performed in parallel. Next, the correction unit 32 time-corrects (correction step) the first measurement data using the second measurement data. This time correction is specifically executed by the following steps S22 and S23.

[0039] In step S22, the correction unit 32 detects the time position of a specific point of the RHEED data. Specifically, the correction unit 32 detects the time position of a specific point of the RHEED data for each measurement angle.

[0040] In step S23, the correction unit 32 time-corrects the CTR data using the RHEED data. Specifically, the correction unit 32 time-corrects the CTR data based on the time position of the specific point. More specifically, the correction unit 32 time-corrects the CTR data for each measurement angle based on the time position of the specific point. Thus, the data correction method M2 ends, and the data acquisition method M1 also ends. By the above data correction process, it becomes possible to arrange a plurality of data at different measurement angles on a common time axis.

[0041] Here, specific points of the RHEED data will be described. Fig. 5 is a graph showing the CTR data and the RHEED data. 501 in Fig. 5 is a graph of the CTR data and the RHEED data when the plane index L is 0.7, and 502 in Fig. 5 is a graph of the CTR data and the RHEED data when the plane index L is 1.3. For each, the CTR data is placed on the upper side and the RHEED data is placed on the lower side along the same time axis (horizontal axis t). The vertical axis in both cases indicates the intensity (unit is arbitrary).

[0042] As shown in the graph of the RHEED data, the intensity of diffraction decreases from the start of raw material irradiation (t = 0), reverses at a certain point in time to form a valley (the time position indicated by t1), and then starts to increase. The time position indicated by t1 is called the valley point. After that, it reverses again to form a peak (the time position indicated by t2) and then decreases. The time position indicated by t2 is called the peak point. This characteristic appears commonly both when the plane index L is 0.7 and when the plane index L is 1.3. In Fig. 5, the time position of the valley when the plane index L is 0.7 is indicated by t1(0.7), and the time position of the valley when the plane index L is 1.3 is indicated by t1(1.3). The time positions of the peaks are shown in the same way.

[0043] Such points are considered to be caused by changes in the deposition status of the raw material substance deposited on the substrate surface, and it is considered that the deposition status of the raw material on the substrate surface at each point in time is the same even when the plane index L is different. Therefore, the time point (time position) of each point can be used as a specific point, and time correction can be performed based on the specific point. As the specific point, at least one of the above-mentioned valley point, peak point, or initial point (the time point when raw material irradiation starts, that is, the time point when t = 0) can be used.

[0044] In the CTR data of Fig. 5, the data before time correction is shown as black circles (●), and the data after time correction using the specific points t1 and t2 is shown as white triangles (△) and is displayed together. The CTR data in Fig. 5 is the data corrected using the correction formula shown below.

[0045] Time correction can use, for example, the following correction formula. [Number]

[0046] In the above correction formula, the meanings of the symbols are as follows. t Corrected (L): The time of the corrected CTR data at a certain L. t Raw (L): The time of the uncorrected CTR data at a certain L. t1(L): The time of the valley point of the RHEED data at a certain L. t2(L): The time of the peak point of the RHEED data at a certain L. t1(0.5): The time of the valley point of the RHEED data at L = 0.5. t2(0.5): The time of the peak point of the RHEED data at L = 0.5. Note that the method of correcting the CTR data is not limited to the above formula, and any method that can temporally correct the data measured at multiple measurement angles and arrange them on a common time axis is acceptable.

[0047] Figure 6 is a graph showing the time-corrected CTR data with the plane index L on the horizontal axis. The vertical axis is the measurement intensity (unit is arbitrary). The data group in the vertical column enclosed by the dotted line on the far left of the graph is the data group obtained from a single measurement with the plane index L = 0.5 set. Figure 6 is a compilation of such data groups obtained by changing the plane index L in one graph.

[0048] The numerical values described on the right side of the graph indicate the measurement time (raw material irradiation time). That is, the bottommost data group marked with "0s" is the CTR data at the start of raw material irradiation (when the raw material has not been deposited). The data group marked with "1.6s" above it is the cumulative measurement data from the start of raw material irradiation to 1.6 seconds later. Further above, the data group marked with "3.2s" is the cumulative measurement data from the start of raw material irradiation to 3.2 seconds later, and so on. Since the data with different plane indices L have been corrected for the aforementioned time, they can be summarized as one graph in this way.

[0049] Note that the data correction method M2 has been described by taking the example of the correction unit 32 of the data acquisition device 30 of the surface state measurement system 1 described above. However, this data correction method M2 may also be executed using the data correction device 2 described below.

[0050] FIG. 12 is a block diagram showing the configuration of the data correction device 2 according to the present embodiment. The data correction device 2 includes a data acquisition unit 21, a data correction unit 22, a processor 23, a memory 24, and an input / output interface 25. The data correction device 2 is communicably connected to a database 50 via an information communication network N such as the Internet.

[0051] The database 50 records, as a set, first measurement data that is time-series measurement data obtained by a synchrotron crystal truncation rod scattering measurement device, and second measurement data that is data obtained in parallel with the first measurement data and is time-series measurement data obtained by a reflection high-energy electron diffraction device.

[0052] The data acquisition unit 21 acquires the first measurement data and the second measurement data from the database 50 via the information communication network N. The data correction unit 22 corrects the first measurement data in terms of time using the second measurement data.

[0053] The memory 24 is composed of various volatile or non-volatile ROM (Read Only Memory) or RAM (Random Access Memory), etc. Various programs are stored in the ROM. The various programs are, for example, a data acquisition program, a data correction program, etc.

[0054] The processor 23 realizes the functions as the data acquisition unit 21 and the data correction unit 22 by expanding and executing various programs stored in the ROM of the memory 24 in the RAM. The processor 23 has the same configuration as the processor 34 of the data acquisition device 30.

[0055] The data correction device 2 may output the corrected data to the display device 26 or a personal computer (not shown) etc. via the input / output interface 25.

[0056] By using the above-described data correction device 2, it is not necessary for the analyst to obtain the first measurement data and the second measurement data by experiment himself / herself. The analyst uses the data correction device 2 to obtain the first measurement data and the second measurement data when various elements are deposited on various substrates, which are recorded in the database 50, corrects them to obtain corrected data, and further analyzes the corrected data, whereby not only the change on the surface of the crystal formed on the substrate but also the information on the internal change can be obtained in seconds.

[0057] According to the data acquisition device according to the above Embodiment 1, the acquisition unit acquires the CTR data obtained by the synchrotron radiation crystal truncation rod scattering measurement device and the RHEED data obtained by the reflection high energy electron diffraction device in parallel, and further the correction unit performs time correction on the CTR data using the RHEED data. By analyzing the data thus obtained in combination, not only the change on the surface of the crystal but also the information on the internal change can be obtained in seconds.

[0058] Further, according to the data acquisition method according to Embodiment 1, a step of acquiring CTR data obtained by a synchrotron radiation crystal truncation rod scattering measurement apparatus, a step of acquiring RHEED data obtained by a reflection high energy electron diffraction apparatus in parallel, and a step of time-correcting the CTR data using the RHEED data are included. By analyzing the corrected data in combination in this way, it is possible to acquire information on changes not only on the surface of the crystal but also inside the crystal in units of seconds.

Example

[0059] Next, an example of the present invention will be described. This example was carried out with the apparatus configuration shown in FIG. 2, and gallium nitride (GaN) with the (0001) plane exposed was used as the substrate to be measured. FIG. 7 is a graph showing the time changes in the intensity of CTR scattering and the intensity of RHEED diffraction using synchrotron radiation during and after the irradiation of the Ga raw material. The time change in the intensity of CTR scattering was acquired using software (spec, manufactured by Certified Scientific Software) for acquiring measurement data. The time change in the intensity of RHEED diffraction was acquired using software (manufactured by k-space) for acquiring measurement data. In FIG. 7, as an example, the results for the case of surface index L = 1.0 are shown at 701, the results for the case of L = 2.2 are shown at 702, and the results for the case of L = 3.0 are shown at 703. However, similar measurements were repeated at intervals of 0.1 from L = 0.5 to 3.0 (or 4.0).

[0060] As shown in the figure, the RHEED intensity decreases due to the irradiation of the Ga raw material on the GaN surface. However, once the irradiation is stopped, the deposited Ga atoms desorb from the surface, revealing the GaN surface and recovering the RHEED intensity. It can be seen that the intensity of the other CTR scattering depends greatly on the surface index L. In the parallel measurement at each surface index L, in order to correct the difference in the raw material irradiation rate, the measurement time of the CTR scattering was corrected by the above-described method.

[0061] Figure 8 is a graph showing the L-dependence of the synchrotron radiation CTR scattering during Ga raw material irradiation. As shown in Figure 8, the CTR scattering intensity at the same irradiation time for each L could be integrated with a time resolution of 1 second or less. 801 in the figure is the case of symmetric 00 reflection, which reflects the structure in the direction perpendicular to the surface of the liquid Ga formed on the GaN surface by Ga raw material irradiation. 802 in the figure is the case of asymmetric 01 reflection, which reflects the in-plane structure of the liquid Ga. Thus, by obtaining the L-dependence of the CTR scattering intensity during Ga irradiation for symmetric and asymmetric reflections respectively and performing data fitting based on X-ray scattering theory, the three-dimensional ordered structure formed by the liquid Ga on the GaN surface could be visualized at the atomic scale.

[0062] Figure 9 is a schematic diagram showing the formation process of the ordered structure formed by liquid Ga obtained by analyzing the data of the L-dependence of synchrotron radiation CTR scattering. Figure 9 is a schematic diagram showing the change over time of the ordered structure formed on the (0001) surface of GaN as the substrate. N Layer and Layer 0 in the figure indicate the layer of nitrogen atoms and the layer of Ga atoms of GaN. In the case shown in Figure 9, it was observed that Ga gradually formed layers on the substrate surface by Ga irradiation, and as a result, an ordered structure of two atomic layers (bilayer) was formed. Specifically, as shown from 901 (before Ga irradiation) to 902 (intermediate state) in Figure 9, when Ga was irradiated, the first layer of Ga (Layer 1) was formed, and then the second layer of Ga (Layer 2) was formed. However, as shown in 903 (after Ga irradiation) in Figure 9, it was found that even when more than two atomic layers of Ga were irradiated, Ga did not form layers, and dimeric Ga was deposited on the surface as disordered droplets. Note that the thick arrows in the figure indicate the direction of atomic movement and the ease of movement. The final coverage rates were ~0.9 ML for the first layer and ~0.9 ML for the second layer. These experimental results are in good agreement with the bilayer structure of Ga predicted by first-principles calculations in the past (J. Northrup et al., Phys. Rev. B 61, 9932 (2000)).

[0063] FIG. 10 is a schematic diagram showing the change over time of the ordered structure formed on the (000-1) surface of GaN, which is a substrate (where "-1" indicates one bar). The N Layer and Layer 0 in 1001 (before Ga irradiation) of FIG. 10 indicate the layer of nitrogen atoms and the layer of Ga atoms in GaN. As shown from 1002 (intermediate state) to 1003 (after Ga irradiation) in FIG. 10, when Ga irradiation is performed on the GaN (000-1) surface, it was found that a highly ordered structure observed on the GaN (0001) surface is not formed, but an incomplete structure with many vacancies is shown. In the figure, the vacancies are indicated by dotted circles. Also, the long thick arrow indicating the ease of movement of the atoms in the first layer (Layer 1) indicates that the atoms are more mobile. Thus, for the first time, it has become clear that by using this technology, the plane orientation of GaN affects the difference in the formation process of the ordered structure of Ga.

[0064] FIG. 11 is a graph showing the substrate temperature dependence of the ordered structure formed by liquid Ga. In graph (a), the vertical axis is the lattice spacing (unit: angstrom) and the horizontal axis is the substrate temperature (°C). In graph (b), the vertical axis is the coverage rate (unit: ML (Monolayer): number of atomic layers) and the horizontal axis is the substrate temperature (°C). In graph (c), the vertical axis is the increase rate (%) of the total coverage rate and the horizontal axis is the substrate temperature (°C).

[0065] In the case of the GaN (0001) surface, as shown in (a), it was found that the lattice spacing of the bilayer after Ga irradiation (the distance between Layer 0 and Layer 1, and the distance between Layer 1 and Layer 2) does not change with respect to the substrate temperature. On the other hand, as shown in (b), the coverage rate of Ga atoms decreases as the substrate temperature decreases, and it was found that the higher the substrate temperature, the higher the integrity of the ordered structure. Furthermore, as shown in (c), in the case of the GaN (000-1) surface, regardless of the substrate temperature, it was found that liquid Ga is less likely to form an ordered structure on the surface compared to the GaN (0001) surface.

[0066] Generally, in the case of the GaN(0001) surface, it is known that growing a GaN thin film under conditions of a high substrate temperature results in better surface flatness of the GaN thin film. Furthermore, it is known that the surface flatness of the GaN(000-1) surface deteriorates compared to the GaN(0001) surface. From the above, this technology was able to show the possibility of a correlation between the ordered structure formed by liquid Ga on the surface and the surface flatness and quality of the GaN thin film. These results can be expected as findings contributing to the high performance of industrially important GaN-based semiconductor devices.

[0067] [Example of Realization by Software] The functions of the data acquisition device 30 (hereinafter referred to as the "device") can be realized by a program for causing a computer to function as the device, and by a program for causing a computer to function as each control block of the device (particularly each part included in the data acquisition device 30).

[0068] In this case, the above device includes a computer having at least one control device (for example, a processor) and at least one storage device (for example, a memory) as hardware for executing the above program. By executing the above program with this control device and storage device, each function described in the above embodiments is realized.

[0069] The above program may be recorded on one or more computer-readable recording media, not temporarily. This recording media may or may not be provided in the above device. In the latter case, the above program may be supplied to the above device via any wired or wireless transmission medium.

[0070] Also, part or all of the functions of each of the above control blocks can also be realized by a logic circuit. For example, an integrated circuit in which a logic circuit functioning as each of the above control blocks is formed is also included in the scope of the present invention. In addition to this, for example, it is also possible to realize the functions of each of the above control blocks by a quantum computer.

[0071] Summary A data acquisition device according to an aspect of the present invention includes an acquisition unit that acquires in parallel first measurement data that is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device and second measurement data that is time-series measurement data obtained by a reflection high-energy electron diffraction device, and a correction unit that corrects the first measurement data in terms of time using the second measurement data.

[0072] According to the above aspect, information on changes not only on the surface of the crystal but also inside the crystal can be acquired in units of seconds.

[0073] In the data acquisition device according to an aspect of the present invention, the correction unit detects the time position of a specific point in the second measurement data, and corrects the first measurement data in terms of time based on the time position of the specific point.

[0074] According to the above aspect, the time shift between the first measurement data and the second measurement data can be corrected using the specific point.

[0075] In the data acquisition device according to an aspect of the present invention, the specific point includes at least any one of an initial point, a valley point, and a peak point of the second measurement data.

[0076] According to the above aspect, the time shift between the first measurement data and the second measurement data can be corrected based on the measurement data.

[0077] In the data acquisition device according to an aspect of the present invention, the acquisition unit continuously acquires the first measurement data and the second measurement data in parallel until a plurality of atomic layers are stacked on the surface of the measurement target for each predetermined measurement angle.

[0078] According to the above aspect, the deposition state of atoms can be measured until a plurality of atomic layers are stacked.

[0079] The data acquisition device according to one aspect of the present invention further includes a device control unit that controls the X-ray crystal truncation rod scattering measurement device and the reflection high-energy electron diffraction device.

[0080] According to the above aspect, the X-ray crystal truncation rod scattering measurement device and the reflection high-energy electron diffraction device can be controlled by a program to acquire data.

[0081] A data correction method according to one aspect of the present invention includes: a first acquisition step of acquiring first measurement data that is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device; a second acquisition step of acquiring second measurement data that is data acquired in parallel with the first measurement data and is time-series measurement data obtained by a reflection high-energy electron diffraction device; and a correction step of performing time correction on the first measurement data using the second measurement data.

[0082] According to the above aspect, not only information on changes in the surface of the crystal but also information on internal changes can be acquired in units of seconds.

[0083] In the data correction method according to one aspect of the present invention, the correction step is a step of detecting the time position of a specific point of the second measurement data and performing time correction on the first measurement data based on the time position of the specific point.

[0084] According to the above aspect, the time shift between the first measurement data and the second measurement data can be corrected using the specific point.

[0085] In the data correction method according to one aspect of the present invention, the specific point includes at least any one of an initial point, a valley point, and a peak point of the second measurement data.

[0086] According to the above aspect, the time shift between the first measurement data and the second measurement data can be corrected based on the measurement data.

[0087] In the data correction method according to one aspect of the present invention, in the first acquisition step and the second acquisition step, for each predetermined measurement angle, the first measurement data and the second measurement data are continuously acquired in parallel until a plurality of atomic layers are stacked on the surface of the measurement target.

[0088] According to the above aspect, the deposition state of atoms can be measured until a plurality of atomic layers are stacked.

[0089] A data correction device according to one aspect of the present invention includes: a data acquisition unit that acquires first measurement data, which is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device, and second measurement data, which is data acquired in parallel with the first measurement data and is time-series measurement data obtained by a reflection high-energy electron diffraction device; and a data correction unit that corrects the first measurement data in terms of time using the second measurement data.

[0090] A program according to one aspect of the present invention causes a computer to function as an acquisition unit that acquires in parallel first measurement data, which is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device, and second measurement data, which is time-series measurement data obtained by a reflection high-energy electron diffraction device, and a correction unit that corrects the first measurement data in terms of time using the second measurement data.

[0091] A recording medium according to one aspect of the present invention is a computer-readable non-transitory recording medium that records the above program.

[0092] 〔Supplementary Notes〕 The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope indicated by the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Explanation of Reference Numerals

[0093] 1…Surface state measurement system 10…CTR measurement device 20…RHEED measurement device 30…Data acquisition device 31…Acquisition unit 32…Correction unit 33…Device control unit 34…Processor 35…Memory

Claims

1. An acquisition unit that acquires in parallel first measurement data, which is time-series measurement data obtained by an X-ray crystallographic truncation rod scattering measurement device, and second measurement data, which is time-series measurement data obtained by a reflection high-energy electron diffraction device; A correction unit that corrects the first measurement data in terms of time using the second measurement data; A data acquisition device comprising the above.

2. The data acquisition device according to claim 1, wherein the correction unit detects the time position of a specific point in the second measurement data and corrects the first measurement data in terms of time based on the time position of the specific point.

3. The data acquisition device according to claim 2, wherein the specific point includes at least any one of an initial point, a valley point, and a peak point of the second measurement data.

4. The data acquisition device according to any one of claims 1 to 3, wherein the acquisition unit continuously acquires the first measurement data and the second measurement data in parallel until a plurality of atomic layers are stacked on the surface of the measurement target for each predetermined measurement angle.

5. The data acquisition device according to any one of claims 1 to 4, further comprising a device control unit that controls the X-ray crystallographic truncation rod scattering measurement device and the reflection high-energy electron diffraction device.

6. A first acquisition step of acquiring first measurement data, which is time-series measurement data obtained by an X-ray crystallographic truncation rod scattering measurement device; A second acquisition step of acquiring second measurement data, which is data acquired in parallel with the first measurement data and is time-series measurement data obtained by a reflection high-energy electron diffraction device; A correction step of correcting the first measurement data in terms of time using the second measurement data; A data correction method including the above.

7. The data correction method according to claim 6, wherein the correction step is a step of detecting the time position of a specific point in the second measurement data and correcting the first measurement data in terms of time based on the time position of the specific point.

8. The data correction method according to claim 7, wherein the specific point includes at least any one of an initial point, a valley point, and a peak point of the second measurement data.

9. The first acquisition step and the second acquisition step are steps of continuously acquiring the first measurement data and the second measurement data in parallel until a plurality of atomic layers are stacked on the surface of the measurement target for each predetermined measurement angle. The data correction method according to any one of claims 6 to 8.

10. A data acquisition unit that acquires first measurement data that is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device, and second measurement data that is data acquired in parallel with the first measurement data and is time-series measurement data obtained by a reflection high-energy electron diffraction device; A data correction device including a data correction unit that corrects the first measurement data in terms of time using the second measurement data.

11. A computer, An acquisition unit that acquires in parallel first measurement data that is time-series measurement data obtained by an X-ray crystal truncation rod scattering measurement device and second measurement data that is time-series measurement data obtained by a reflection high-energy electron diffraction device; A correction unit that corrects the first measurement data in terms of time using the second measurement data; A program for causing the computer to function as such.

12. A computer-readable non-transitory recording medium recording the program according to claim 11.

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