Single crystal semiconductor wafer measuring system and method

Abstract

The invention discloses a single crystal semiconductor wafer measurement system and method, and the system comprises a first light source system, a multi-degree-of-freedom positioning platform, and a first detection system, and the first light source system emits a first X-ray which irradiates a measurement point of a sample on the multi-degree-of-freedom positioning platform; the first light source system is used for emitting first X-rays, the first detection system is used for detecting a scattering image formed by the first X-rays penetrating through the sample, the second light source system is used for emitting second X-rays from a plurality of angles, and focus points of the second X-rays at the plurality of angles coincide with measurement points on the sample; the second detection system is used for receiving diffracted X-rays formed by irradiating the sample with the second X-rays and identifying the drop point positions of the diffracted X-rays; and the calculation module is used for analyzing the position of the drop point based on the Bragg diffraction principle to obtain direction information of the plane where the measurement point is located. According to the invention, when CD-SAXS measurement is carried out, measurement in the direction of the plane where the wafer measurement point is located is carried out synchronously, and the efficiency is higher.

Description

Technical Field

[0001] The present application relates to the technical field of critical dimension measurement of nano-gratings or nano-field effect transistors, and in particular to a single crystal semiconductor wafer measurement system and method. Background Art

[0002] With the development of semiconductor manufacturing technology, the line width of the etched structure in semiconductor devices has become smaller and smaller, and the etching depth has become larger and larger, thus forming a unique high aspect ratio structure (HAR). Etching of high aspect ratio structures is a very critical and very challenging process step in the semiconductor device manufacturing process, which will significantly affect the performance and yield of the device. For example, for the manufacturing process of modern memory devices 3D NAND, with the continuous vertical scaling of the 3D-NAND structure, the aspect ratio of its memory hole structure in the most advanced manufacturing process in the industry is greater than 50:1 (the aspect ratio is the ratio of height to diameter). Therefore, accurately characterizing the etching process and quality during the development of semiconductor devices and monitoring it during the manufacturing process are becoming increasingly difficult, but also increasingly important.

[0003] Small-angle X-ray scattering (SAXS) is an X-ray metrology technique that can be used to measure structural features on the scale of 1-100 nanometers. It has the potential to measure complex periodic nanostructures, such as high-aspect-ratio etched structures in finFETs and 3D NAND cells. Among these, critical dimension small-angle X-ray scattering (CD-SAXS) is a transmission-type, variable-angle SAXS measurement technique and a non-destructive metrology method. Due to the short wavelength and deep penetration of high-energy X-rays, CD-SAXS exploits the scattering of X-rays by periodic nanomaterials to simultaneously measure critical dimensions in both the lateral and depth directions of HAR structures in semiconductor devices. Furthermore, as the number of stacked layers in semiconductor devices (such as 3D-NAND) increases, the CD-SAXS measurement signal strength increases accordingly, further enhancing measurement capabilities. This is a feature not available in other metrology methods, such as optical optical density device (OCD). Therefore, CD-SAXS offers unique advantages for the precise measurement of HAR structures.

[0004] In CD-SAXS, a high-energy X-ray beam passes through a semiconductor wafer and is scattered from a periodic nanostructure. The angular distribution of the scattered intensity is measured by a two-dimensional array detector. The wafer is then deflected so that the crystal plane normal is at a series of different angles with the incident beam, allowing the X-ray beam to pass through the sample at a series of different incident angles. Scattering images at these different incident angles are then collected to determine the angular dependence of the scattering pattern. Therefore, for CD-SAXS equipment, the wafer sample to be tested can only be placed on a hollow sample stage so that the sample stage does not block the X-rays scattered by the HAR structure from being received by the CD-SAXS detection equipment. The wafer sample to be tested can only be fixed by edge clamping, such as Figure 1 As shown. Although this clamping method can ensure that every point on the wafer to be tested can be measured, the uneven force on the wafer to be tested caused by its hollow structure and edge clamping inevitably causes surface changes such as wafer bending and warping. Therefore, the surface direction of each local area on the wafer to be tested is different. The CD-SAXS measurement signal is highly angle-dependent. The measurement accuracy of the angular relationship between the scattered signal and the sample surface direction directly determines the accuracy of the CD-SAXS device in measuring the key dimensions of the nano-etched structure of the semiconductor wafer. Therefore, in addition to measuring the X-ray scattering signal of the nano-etched structure of the wafer to be tested in the CD-SAXS device, it is also crucial to measure the surface direction at the measurement point of the wafer.

[0005] There are three main methods currently used in CD-SAXS measurement systems to determine the surface orientation of the wafer at the measurement point:

[0006] The first method is to use an optical distance sensor to measure the vertical distances of three points near the measurement point relative to the optical sensor, and use the plane determined by these three points to approximate the plane at the measurement point. Then, the direction of the plane determined by the three points is calculated based on the geometric relationship through the change in the vertical distance of the three points relative to the optical sensor. This direction is considered to be the direction of the sample surface at the measurement point. However, this method has limitations: first, the accuracy of the surface direction at the wafer measurement point is very dependent on the position selection of the optical sensor measurement point, and is also affected by the parallelism of the moving platform's motion axis and motion vibration when measuring the three points; second, because measuring three points requires moving the wafer or the optical distance sensor, it is impossible to measure the surface direction at the wafer measurement point while performing CD-SAXS measurement, which will greatly increase the overall measurement time and greatly reduce the measurement throughput of the CD-SAXS measurement equipment;

[0007] The second method for determining the surface orientation at a measurement point on a wafer utilizes the principle of optical reflection. The surface orientation at the measurement point is calculated based on the location of the reflected laser beam from the laser beam passing through the measurement point on an optical detector. However, since this method reflects the laser beam from the sample surface, it is significantly affected by the sample surface morphology (such as surface roughness and etching patterns), which greatly affects the determination of the sample surface orientation at the measurement point.

[0008] The third approach is to determine crystal orientation using X-ray diffraction techniques. However, these methods use linear X-rays, scan the sample surface with an angle meter, and then determine the crystal orientation based on the rocking curve. While these methods can accurately determine the sample's plane orientation, the required angle scanning requires a very long measurement time. Summary of the Invention

[0009] In view of this, the present application provides a single crystal semiconductor wafer measurement system and method to solve the problem of low efficiency of existing single crystal semiconductor wafer measurement methods.

[0010] To solve the above technical problems, a technical solution adopted in the present application is: providing a single crystal semiconductor wafer measurement system, which includes a first light source system, a multi-degree-of-freedom positioning platform, and a first detection system arranged in sequence, wherein the first light source system emits a first X-ray to irradiate a measurement point of a sample on the multi-degree-of-freedom positioning platform, and the first detection system detects a scattered image formed by the first X-ray passing through the sample. The system also includes: a second light source system, whose relative spatial position with respect to the optical path formed by the first X-ray is preset, and is used to emit second X-rays from multiple angles, and the focal points of the second X-rays at multiple angles coincide with the measurement point on the sample; a second detection system, whose relative spatial position with respect to the optical path formed by the first X-ray is preset, and is used to receive diffracted X-rays formed by the second X-ray irradiating the sample and identify the landing point position of the diffracted X-rays; and a calculation module, which is electrically connected to the second detection system and is used to analyze the landing point position based on the Bragg diffraction principle to obtain directional information of the plane in which the measurement point is located.

[0011] As a further improvement of the present application, the second light source system emits cone-beam X-rays, and the focus point of the cone-beam X-rays coincides with the measurement point on the sample.

[0012] As a further improvement of the present application, the second detection system includes a two-dimensional array X-ray detector, which includes multiple pixel points, and the line between each pixel point and the measurement point is at a specific angle to the optical path formed by the first X-ray.

[0013] As a further improvement of the present application, the calculation module is used to confirm the target pixel point where the diffracted X-ray lands according to the landing position of the diffracted X-ray, and calculate the diffraction angle of the diffracted X-ray based on the Bragg diffraction law, and then calculate the angle between the normal of the plane where the measurement point is located and the optical path according to the diffraction angle and the target specific angle corresponding to the target pixel point.

[0014] As a further improvement of this application, the calculation process of the angle is expressed as:

[0015]

[0016] Where β represents the angle between the normal of the plane where the measurement point is located and the optical path, θ represents the diffraction angle, Indicates the specific angle between the line connecting the target pixel and the measurement point and the optical path.

[0017] As a further improvement of the present application, it also includes a vacuum collimation system, which is arranged between the first light source system and the multi-degree-of-freedom positioning platform. The first slit, the second slit and the third slit are arranged in sequence in the vacuum collimation system. The first slit and the second slit are in a vacuum environment. The light path formed by the first X-ray passes through the first slit, the second slit and the third slit in sequence and irradiates the sample.

[0018] As a further improvement of the present application, it also includes a vacuum scattering system, which is arranged between the multi-degree-of-freedom positioning platform and the first detection system. The vacuum scattering system includes a high vacuum cavity for transmitting the scattering image to the first detection system.

[0019] To solve the above technical problems, another technical solution adopted in the present application is: providing a single crystal semiconductor wafer measurement method, which is applied to one of the above-mentioned single crystal semiconductor wafer measurement systems; the method includes: S1, controlling the multi-degree-of-freedom positioning platform to rotate so that the sample is at a preset angle; S2, controlling the first light source system and the second light source system to start working, so that the first light source system emits a first X-ray and the second light source system emits a second X-ray at multiple angles, both of which irradiate the measurement point of the sample; S3, using the first detector to collect a scattered image formed by the measurement point of the sample under the irradiation of the first X-ray, and at the same time controlling the second detector to collect diffracted X-rays formed by the measurement point of the sample under the irradiation of the second X-ray, and identifying the landing position of the diffracted X-rays; S4, using a calculation module to analyze the landing position based on the Bragg diffraction principle to obtain directional information of the plane in which the measurement point is located; controlling the multi-degree-of-freedom positioning platform to rotate to different preset angles, and repeating steps S2 to S4 until the measurement is completed.

[0020] As a further improvement of the present application, the second detection system includes a two-dimensional array X-ray detector, which includes multiple pixel points, and the line between each pixel point and the measurement point is at a specific angle to the optical path formed by the first X-ray; the calculation module is used to analyze the landing point position based on the Bragg diffraction principle to obtain the direction information of the plane where the measurement point is located, including: the calculation module confirms the target pixel point where the diffracted X-ray lands according to the landing point position of the diffracted X-ray; the calculation module calculates the diffraction angle of the diffracted X-ray based on the Bragg diffraction law; the calculation module calculates the angle between the normal of the plane where the measurement point is located and the optical path based on the diffraction angle and the target specific angle corresponding to the target pixel point.

[0021] As a further improvement of this application, the calculation process of the angle is expressed as:

[0022]

[0023] Where β represents the angle between the normal of the plane where the measurement point is located and the optical path, θ represents the diffraction angle, Indicates the specific angle between the line connecting the target pixel and the measurement point and the optical path.

[0024] The beneficial effects of the present application are as follows: the single crystal semiconductor wafer measurement system of the present application utilizes the strong penetrating properties of X-rays and the Bragg diffraction effect of the single crystal silicon substrate of the semiconductor. The X-ray beam emitted by the second light source system contains rays with multiple incident angles, and only the ray beam with an incident angle that meets the Bragg diffraction condition of the single crystal silicon substrate can be received by the second detection system through diffraction of the single crystal silicon substrate. The diffraction direction of the diffracted X-ray can be calculated according to the landing position of the diffracted X-ray on the second detection system, and thus the crystal plane direction at the measurement point can be calculated according to the angular relationship of the Bragg diffraction. This enables CD-SAXS measurement and crystal plane direction measurement of the sample at the measurement point to be carried out simultaneously, without the need for fine angle scanning, greatly reducing the time required for measurement, improving measurement efficiency, and not being affected by the surface morphology of the sample (such as surface roughness, etching pattern, etc.), and the measurement result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of a sample fixing method of an existing small-angle X-ray scattering measurement device;

[0026] Figure 2 1 is a schematic structural diagram of a single crystal semiconductor wafer measurement system according to an embodiment of the present invention;

[0027] Figure 3 1 is a schematic diagram of the optical path structure when the crystal plane normal of the sample is parallel to the optical path axis in the single crystal semiconductor wafer measurement system according to an embodiment of the present invention;

[0028] Figure 4 1 is a schematic diagram of the optical path structure when the crystal plane normal of the sample in the single crystal semiconductor wafer measurement system according to an embodiment of the present invention is deflected by a negative angle relative to the optical path axis;

[0029] Figure 5 1 is a schematic diagram of the optical path structure when the crystal plane normal of the sample in the single crystal semiconductor wafer measurement system according to an embodiment of the present invention is deflected by a positive angle relative to the optical path axis;

[0030] Figure 6 1 is a schematic diagram of calculating the angle between the plane where the measurement point is located and the optical path in the single crystal semiconductor wafer measurement system according to an embodiment of the present invention;

[0031] Figure 7 4 is a flow chart of a single crystal semiconductor wafer measurement method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0033] The terms "first", "second" and "third" in this application are used only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second" or "third" may explicitly or implicitly include at least one of such features. In the description of this application, "multiple" means at least two, for example, two, three, etc., unless otherwise specifically defined. All directional indications in the embodiments of this application (such as up, down, left, right, front, back...) are only used to explain the relative spatial position, movement, etc. between the components under a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally also include steps or units that are not listed, or may optionally also include other steps or units inherent to these processes, methods, products or devices.

[0034] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] Figure 2 FIG. 1 is a schematic diagram of the structure of a single crystal semiconductor wafer measurement system according to an embodiment of the present invention. Figure 2 As shown, the single crystal semiconductor wafer measurement system includes: a first light source system 1, a multi-degree-of-freedom positioning platform 2, a first detection system 3, a second light source system 4, a second detection system 5, and a computing module (not shown in the figure). The first light source system 1, the multi-degree-of-freedom positioning platform 2, and the first detection system 3 are arranged in sequence.

[0036] The first light source system 1 includes an X-ray light source and a collimating monochromator. The X-ray light source is used to generate a point-divergent X-ray beam. The function of the collimating monochromator is to convert the point-divergent complex X-ray beam generated by the X-ray light source into a quasi-monochromatic and quasi-parallel X-ray beam, i.e., the first X-ray.

[0037] The multi-degree-of-freedom positioning platform 2 is used to achieve precise positioning of any point on the sample (i.e., it includes a high-precision XYZ motion axis), so that the optical path formed by the first X-ray can accurately irradiate the measurement point on the sample. At the same time, it can realize the angular deflection scanning control of the sample relative to the axis of the optical path, so that the first X-ray is projected through the sample at a series of different incident angles, forming a series of scattering images with different incident angles.

[0038] The first detection system 3 is used to detect a scattered image formed by the first X-ray passing through the sample, so as to determine the angle dependence of the scattering pattern.

[0039] The relative spatial position of the second light source system 4 and the optical path formed by the first X-ray is pre-set, and is used to emit the second X-ray from multiple angles, and the focusing points of the second X-rays at multiple angles coincide with the measurement points on the sample.

[0040] The relative spatial position of the second detection system 5 and the optical path formed by the first X-ray is preset, and is used to receive the diffracted X-rays formed by the second X-ray irradiating the sample and identify the landing point position of the diffracted X-rays.

[0041] It should be understood that in this embodiment, the relative spatial positions between the second light source system 4, the second detection system 5, and the optical path formed by the first X-rays are pre-set, and the focal point of the second X-rays emitted at multiple angles by the second light source system 4 is located at the measurement point of the sample on the multi-degree-of-freedom positioning platform 2. That is, this focal point also coincides with the point where the first X-rays irradiate the sample. For multiple measurement points on the sample, after completing the measurement of one measurement point, the multi-degree-of-freedom positioning platform 2 moves the sample so that the next measurement point is located at the position where the first X-ray optical path penetrates the sample, i.e., the location of the focal point of the second X-rays.

[0042] The calculation module is electrically connected to the second detection system 5 and is used to analyze the landing point position and obtain the direction information of the plane where the measurement point is located.

[0043] It should be noted that the single-crystal semiconductor wafer measurement system of this embodiment is designed to measure single-crystal semiconductor wafers with a well-defined single-crystal structure and composition. For single-crystal samples, when irradiated with X-rays, only X-rays whose incident angles satisfy the Bragg diffraction principle are diffracted by the single-crystal silicon at the sample's base. Other X-rays that do not conform to the Bragg diffraction principle do not diffract. Consequently, there is no need to adjust the incident angle of the second X-rays emitted by the second light source system 4. Fine-grained angular scanning control is not required to measure the crystal plane orientation at the sample's measurement point, and the measurement is unaffected by the sample's surface morphology (such as surface roughness, etched patterns, etc.).

[0044] Specifically, see Figure 3 、 Figure 4 and Figure 5 As shown, Figure 3 This is a schematic diagram of the optical path structure when the crystal plane normal of the sample is parallel to the optical path axis. Figure 4 This is a schematic diagram of the optical path structure when the crystal plane normal of the sample is deflected by a negative angle relative to the optical path axis. Figure 5 The optical path structure diagram is shown when the crystal plane normal of the sample is deflected by a positive angle relative to the optical path axis. The process of measuring the sample by the single crystal semiconductor wafer measurement system is as follows: First, the multi-degree-of-freedom positioning platform 2 is controlled to rotate so that the sample is at a preset angle (such as Figure 3As shown); then, the first light source system 1 and the second light source system 4 are controlled to start working, the first light source system 1 emits the first X-ray and the second light source system 4 emits the second X-ray at multiple angles, all of which are irradiated to the measuring point of the sample; then the first detector is used to collect the scattered image formed by the measuring point of the sample under the irradiation of the first X-ray, and the second detector is controlled to collect the diffracted X-ray formed by the measuring point of the sample under the irradiation of the second X-ray, and the landing position of the diffracted X-ray is identified; finally, the landing position is analyzed by the calculation module to obtain the direction information of the plane where the measuring point is located. By controlling the multi-degree-of-freedom positioning platform 2 to rotate to different preset angles (such as Figure 4 and Figure 5 As shown), the above process is repeated to collect a series of scattering images at different incident angles, and then the angular dependence of the scattering pattern of the single crystal semiconductor is determined by analyzing the series of scattering images.

[0045] The single crystal semiconductor wafer measurement system of the present application utilizes the strong penetrating properties of X-rays and the Bragg diffraction effect of the silicon substrate of the single crystal semiconductor. The X-ray beam emitted by the second light source system 4 contains rays with multiple incident angles, and only the ray beam with an incident angle that meets the Bragg diffraction condition of the single crystal silicon substrate can be received by the second detection system 5 through diffraction of the single crystal silicon substrate. The diffraction direction of the diffracted X-ray can be calculated based on the landing position of the diffracted X-ray on the second detection system 5, and thus the crystal plane direction at the measurement point can be calculated based on the angular relationship of the Bragg diffraction. This allows the CD-SAXS measurement and the crystal plane direction measurement of the sample at the measurement point to be carried out simultaneously without the need for a fine angle scanning process, greatly reducing the time required for measurement and improving measurement efficiency. It will not be affected by the surface morphology of the sample (such as surface roughness, etching pattern, etc.), and the measurement results are more accurate.

[0046] Furthermore, in some embodiments, the second light source system 4 emits cone-beam X-rays, and the focus of the cone-beam X-rays coincides with the measurement point on the sample.

[0047] Specifically, the incident cone beam X-ray beam contains X-rays at a series of incident angles (relative to the normal direction of the sample surface) to ensure that there are X-rays that can satisfy the Bragg diffraction principle among the X-rays at the series of incident angles.

[0048] Furthermore, the second detection system 5 includes a two-dimensional array X-ray detector, which includes a plurality of pixels, and the line between each pixel and the measurement point forms a specific angle with the optical path formed by the first X-ray.

[0049] It should be noted that the relative spatial position between the second detection system 5 and the optical path formed by the first X-ray is pre-set, so that the line between each pixel point and the measurement point in the two-dimensional array X-ray detector is at a specific angle to the optical path formed by the first X-ray, and the specific angle is known in advance.

[0050] Specifically, the second light source system 4 emits a plurality of second X-rays at different angles. When the second X-rays at different incident angles are diffracted at the measurement point of the sample, their diffraction angles are also different. Therefore, the second detection system 5 of this embodiment adopts a two-dimensional array X-ray detector to ensure that the diffracted X-rays of the second X-rays at different incident angles can all be detected.

[0051] Furthermore, the calculation module is used to confirm the target pixel point where the diffracted X-ray lands according to the landing position of the diffracted X-ray, and calculate the diffraction angle of the diffracted X-ray based on the Bragg diffraction law, and then calculate the angle between the normal of the plane where the measurement point is located and the optical path according to the diffraction angle and the target specific angle corresponding to the target pixel point.

[0052] Specifically, after receiving the diffracted X-rays, the second detection system 5 determines all the pixels irradiated by the diffracted X-rays, and then determines the pixel with the largest intensity in the diffraction spot as the target pixel. The measurement point and the target pixel are connected to form a line. The angle between the line and the plane where the measurement point is located is the diffraction angle. The diffraction angle can be calculated using the Bragg diffraction formula, as follows:

[0053] 2dsinθ=nλ;

[0054] Where d is the interplanar spacing of the sample's single-crystal silicon substrate, λ is the wavelength of the monochromatic X-ray beam, θ is the diffraction angle, and n is the diffraction order. The interplanar spacing of the sample's single-crystal silicon substrate, the wavelength of the monochromatic X-ray beam, and the diffraction order are all known in advance, allowing the diffraction angle to be calculated.

[0055] The specific angle between the line connecting each pixel point and the measurement point and the optical path is known in advance. By combining the diffraction angle and the target specific angle, the angle between the normal of the plane where the measurement point is located and the optical path can be calculated.

[0056] The calculation process of the angle is expressed as:

[0057]

[0058] Where β represents the angle between the normal of the plane where the measurement point is located and the optical path, θ represents the diffraction angle, Indicates the specific angle between the line connecting the target pixel and the measurement point and the optical path.

[0059] Specifically, see Figure 6As shown, Figure 6 (a) and (b) show the angle between the normal of the plane where the measurement point is located and the optical path in two different situations. The plane where the measurement point is located and the normal of the plane where the measurement point is located are perpendicular to each other. Figure 6 As shown in (a), from Figure 6 As shown in (b), Therefore, the calculation process of the angle is expressed as In addition, when the normal direction of the plane where the measuring point is located coincides with the optical path, the angle between the normal direction of the plane where the measuring point is located and the optical path is 0.

[0060] For further information, see Figure 2 The single crystal semiconductor wafer measurement system also includes a vacuum collimation system 6, which is arranged between the first light source system 1 and the multi-degree-of-freedom positioning platform 2. A first slit 61, a second slit 62 and a third slit 63 are sequentially arranged in the vacuum collimation system 6. The first slit 61 and the second slit 62 are in a vacuum environment. The light path formed by the first X-ray passes through the first slit 61, the second slit 62 and the third slit 63 in sequence and irradiates the sample.

[0061] Specifically, the first slit 61 and the second slit 62 are in a vacuum environment, so that the optical path formed by the first X-ray between the first slit 61 and the second slit 62 is in a vacuum environment to reduce the attenuation effect of air on the X-ray beam. Therefore, the first slit 61 should be set close to the first light source system 1, and the second slit 62 should be set close to the multi-degree-of-freedom positioning platform 2.

[0062] For further information, see Figure 2 The single crystal semiconductor wafer measurement system also includes a vacuum scattering system 7, which is arranged between the multi-degree-of-freedom positioning platform 2 and the first detection system 3. The vacuum scattering system 7 includes a high vacuum cavity for transmitting the scattering image to the first detection system 3.

[0063] Specifically, the vacuum scattering system 7 includes a high vacuum cavity for transmitting the scattering image to the first detection system 3, which can reduce the attenuation of the scattering signal by air during the transmission process.

[0064] Figure 7 1 is a flow chart of a single crystal semiconductor wafer measurement method according to an embodiment of the present invention. The single crystal semiconductor wafer measurement method is applied to a single crystal semiconductor wafer measurement system according to any one of the above embodiments. The single crystal semiconductor wafer measurement system includes a first light source system, a multi-degree-of-freedom positioning platform, a first detection system, a second light source system, a second detection system, and a computing module. The single crystal semiconductor wafer measurement method includes:

[0065] Step S1, controlling the multi-degree-of-freedom positioning platform to rotate so that the sample is at a preset angle.

[0066] Specifically, the preset angle is pre-set. In this embodiment, multiple angles are pre-set, and the multi-degree-of-freedom positioning platform rotates so that the sample is respectively at each preset angle for measurement, so as to obtain a series of scattering images at different angles.

[0067] Step S2: Control the first light source system and the second light source system to start working, the first light source system emits first X-rays and the second light source system emits second X-rays at multiple angles, both of which irradiate the measurement point of the sample.

[0068] Step S3: Use the first detector to collect the scattered image formed by the measuring point of the sample under the first X-ray irradiation, and at the same time control the second detector to collect the diffracted X-ray formed by the measuring point of the sample under the second X-ray irradiation, and identify the landing position of the diffracted X-ray.

[0069] Step S4: Analyze the landing point position using the calculation module to obtain the direction information of the plane where the measurement point is located.

[0070] The multi-degree-of-freedom positioning platform is controlled to rotate to different preset angles, and steps S2 to S4 are repeated until the measurement is completed.

[0071] It should be noted that, for details of the specific implementation process of the above steps S1 to S4, please refer to the content described in the embodiment of the single crystal semiconductor wafer measurement system, which will not be repeated here.

[0072] The single crystal semiconductor wafer measurement method of this embodiment utilizes the strong penetrating properties of X-rays and the Bragg diffraction effect of the silicon substrate of the single crystal semiconductor. The X-ray beam emitted by the second light source system contains rays with multiple incident angles, and only the ray beam with an incident angle that meets the Bragg diffraction condition of the single crystal silicon substrate can be received by the second detection system through diffraction of the single crystal silicon substrate. The diffraction direction of the diffracted X-ray can be calculated based on the landing position of the diffracted X-ray on the second detection system, and thus the crystal plane direction at the measurement point can be calculated based on the angular relationship of the Bragg diffraction. This allows the CD-SAXS measurement and the crystal plane direction measurement of the sample at the measurement point to be carried out simultaneously without the need for a fine angle scanning process, greatly reducing the time required for measurement and improving measurement efficiency. It is also not affected by the surface morphology of the sample (such as surface roughness, etching pattern, etc.), and the measurement results are more accurate.

[0073] Furthermore, the second detection system includes a two-dimensional array X-ray detector, which includes a plurality of pixels, and a line between each pixel and the measurement point forms a specific angle with the optical path formed by the first X-ray.

[0074] Therefore, step S4 specifically includes:

[0075] 1. The calculation module determines the target pixel point where the diffracted X-ray lands according to the landing point position of the diffracted X-ray.

[0076] 2. The calculation module calculates the diffraction angle of the diffracted X-ray based on the Bragg diffraction law.

[0077] Specifically, after receiving the diffracted X-ray, all the pixels irradiated by the diffracted X-ray are determined, and then the pixel with the largest intensity in the diffraction spot is determined as the target pixel. The measurement point and the target pixel are connected to form a line. The angle between the line and the plane where the measurement point is located is the diffraction angle. The diffraction angle can be calculated using the Bragg diffraction formula as follows:

[0078] 2dsinθ=nλ;

[0079] Where d is the interplanar spacing of the sample's single-crystal silicon substrate, λ is the wavelength of the monochromatic X-ray beam, θ is the diffraction angle, and n is the diffraction order. The interplanar spacing of the sample's single-crystal silicon substrate, the wavelength of the monochromatic X-ray beam, and the diffraction order are all known in advance, allowing the diffraction angle to be calculated.

[0080] 3. The calculation module calculates the angle between the normal of the plane where the measurement point is located and the optical path based on the diffraction angle and the target specific angle corresponding to the target pixel point.

[0081] The calculation process of the angle is expressed as:

[0082]

[0083] Where β represents the angle between the normal of the plane where the measurement point is located and the optical path, θ represents the diffraction angle, Indicates the specific angle between the line connecting the target pixel and the measurement point and the optical path.

[0084] The above is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A single crystal semiconductor wafer measurement system, comprising a first light source system, a multi-degree-of-freedom positioning platform, and a first detection system arranged in sequence, wherein the first light source system emits a first X-ray to irradiate a measurement point of a sample on the multi-degree-of-freedom positioning platform, and the first detection system detects a scattered image formed by the first X-ray passing through the sample, characterized in that: It also includes: A second light source system, the relative spatial position of which is set in advance with respect to the optical path formed by the first X-ray, is used to emit second X-rays from multiple angles, and the focus points of the second X-rays at multiple angles coincide with the measurement points on the sample; A second detection system, the relative spatial position of which to the optical path formed by the first X-ray is preset, is used to receive the diffracted X-rays formed by the second X-ray irradiating the sample and identify the landing point position of the diffracted X-rays; The calculation module is electrically connected to the second detection system and is used to analyze the landing point position based on the Bragg diffraction principle to obtain the direction information of the plane where the measurement point is located.

2. The single crystal semiconductor wafer measurement system according to claim 1, characterized in that: The second light source system emits cone-beam X-rays, and a focus point of the cone-beam X-rays coincides with a measurement point on the sample.

3. The single crystal semiconductor wafer measurement system according to claim 1, wherein: The second detection system includes a two-dimensional array X-ray detector, which includes a plurality of pixel points. A line connecting each pixel point and the measurement point forms a specific angle with an optical path formed by the first X-ray.

4. The single crystal semiconductor wafer measurement system according to claim 3, characterized in that: The calculation module is used to confirm the target pixel point where the diffracted X-ray lands according to the landing position of the diffracted X-ray, calculate the diffraction angle of the diffracted X-ray based on the Bragg diffraction principle, and then calculate the angle between the normal of the plane where the measuring point is located and the optical path according to the diffraction angle and the target specific angle corresponding to the target pixel point.

5. The single crystal semiconductor wafer measurement system according to claim 4, characterized in that: The calculation process of the angle is expressed as: Wherein, β represents the angle between the normal of the plane where the measuring point is located and the optical path, θ represents the diffraction angle, Represents a specific angle between the line between the target pixel and the measurement point and the optical path.

6. The single crystal semiconductor wafer measurement system according to claim 1, wherein: It also includes a vacuum collimation system, which is arranged between the first light source system and the multi-degree-of-freedom positioning platform. A first slit, a second slit and a third slit are arranged in sequence in the vacuum collimation system. The first slit and the second slit are in a vacuum environment. The light path formed by the first X-ray passes through the first slit, the second slit and the third slit in sequence to irradiate the sample.

7. The single crystal semiconductor wafer measurement system according to claim 1, wherein: It also includes a vacuum scattering system, which is arranged between the multi-degree-of-freedom positioning platform and the first detection system. The vacuum scattering system includes a high vacuum cavity for transmitting the scattering image to the first detection system.

8. A method for measuring a single crystal semiconductor wafer, characterized in that: The method is applied to the single crystal semiconductor wafer measurement system according to any one of claims 1 to 7; the method comprises: S1, controlling the multi-degree-of-freedom positioning platform to rotate so that the sample is at a preset angle; S2, controlling the first light source system and the second light source system to start working, wherein the first light source system emits a first X-ray and the second light source system emits a second X-ray at multiple angles, both of which are irradiated to the measurement point of the sample; S3, using the first detector to collect a scattering image formed by the measuring point of the sample under the irradiation of the first X-ray, and controlling the second detector to collect a diffracted X-ray formed by the measuring point of the sample under the irradiation of the second X-ray, and identifying the landing position of the diffracted X-ray; S4, using a calculation module to analyze the landing point position based on the Bragg diffraction principle to obtain the direction information of the plane where the measurement point is located; The multi-degree-of-freedom positioning platform is controlled to rotate to different preset angles, and steps S2 to S4 are repeatedly performed until the measurement is completed.

9. The single crystal semiconductor wafer measurement method according to claim 8, characterized in that: The second detection system includes a two-dimensional array X-ray detector, the two-dimensional array X-ray detector includes a plurality of pixels, and a line between each pixel and the measurement point forms a specific angle with an optical path formed by the first X-ray; The using a calculation module to analyze the landing point position based on the Bragg diffraction principle to obtain the direction information of the plane where the measurement point is located includes: The calculation module determines the target pixel point where the diffracted X-ray lands according to the landing position of the diffracted X-ray; The calculation module calculates the diffraction angle of the diffracted X-ray based on the Bragg diffraction principle; The calculation module calculates the angle between the normal of the plane where the measuring point is located and the optical path according to the diffraction angle and the target specific angle corresponding to the target pixel point.

10. The single crystal semiconductor wafer measurement method according to claim 9, characterized in that: The calculation process of the angle is expressed as: Wherein, β represents the angle between the normal of the plane where the measuring point is located and the optical path, θ represents the diffraction angle, Represents a specific angle between the line between the target pixel and the measurement point and the optical path.

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