Measuring device, ion implantation device, measuring method, and ion implantation method

Abstract

This ion implantation device (1) carries out ion implantation on a semiconductor wafer (50) and comprises: a chamber (2); a transmitted light optical system that provides and measures a transmitted light (14) and that has, in the indicated sequence, a laser light source (3), a polarizer (4), a rotation and angle measurement means (6), a first analyzer (7a), and a transmitted light detector (8); and an ion beam source (12). The chamber incorporates therewithin the rotation and angle measurement means and has an optical window (5a, 5c) between the polarizer (4) and the rotation and angle measurement means and between the rotation and angle measurement means and the first analyzer. The rotation and angle measurement means supports a semiconductor wafer and can rotate centered on at least the [11-20] direction and [1-100] direction of the semiconductor wafer. The polarization plane of the first analyzer is disposed orthogonal to the polarizer.

Description

【Technical Field】 【0001】 The present disclosure relates to a measuring device, an ion implantation device, a measuring method, and an ion implantation method. 【Background Art】 【0002】 Particularly, in ion implantation into a silicon carbide semiconductor wafer or a gallium nitride semiconductor wafer, precise setting of the wafer angle is essential to realize a deep implantation profile using the channeling phenomenon. 【0003】 Patent Document 1 describes a method for measuring the plane orientation of a single crystal substrate made of a uniaxial crystal. When light is incident on the single crystal substrate made of a uniaxial crystal from an arbitrary direction, the refractive index of the light becomes a composite value of the refractive indices inherent to the crystal principal axis and becomes a function of the light incident direction. Using this, the measurement of the tilt orientation of the crystal principal axis with respect to the orifla orientation of the substrate and the measurement of the tilt angle of the crystal principal axis with respect to the normal direction of the substrate are performed in two steps. 【0004】 Patent Document 2 describes a method for forming a semiconductor structure including steps of preparing a silicon carbide layer having a crystal axis, heating the silicon carbide layer to a temperature of about 300°C or higher, and injecting dopant ions at an injection angle of less than about 2° between the injection direction and the crystal axis into the heated silicon carbide layer. 【0005】 Patent Document 3 describes an n-type substrate made of SiC and having an off-angle with a main surface inclined at a predetermined tilt angle with respect to the (0001) plane, a JFET portion having an off-angle formed thereon with an epitaxial growth film, and an electric field blocking layer formed at a desired position and composed of an ion implantation layer. With the direction having the off-angle as the off direction, a silicon carbide semiconductor device is described in which the boundary line between the JFET portion and the electric field blocking layer along the depth direction inclines in the direction of

[0001] with respect to the normal direction of the main surface. + 【0006】 Traditionally, Rutherford backscattering was used to detect the wafer angle suitable for channeling. However, Rutherford backscattering requires irradiation with ions different from those used for ion implantation, which has the drawback of being a time-consuming process and requiring complex ion implantation equipment. [Prior art documents] [Patent Documents] 【0007】 [Patent Document 1] Japanese Patent Application Publication No. 2014-194352 [Patent Document 2] Japan Special Publication No. 2016-530712 [Patent Document 3] Japanese Patent Publication No. 2022-93100 [Overview of the Initiative] [Problems that the invention aims to solve] 【0008】 The objective of this disclosure is to provide a measuring device, an ion implantation device, a measuring method, and an ion implantation method that enable faster angle detection of semiconductor wafers, reduced process costs, and reduced equipment introduction costs compared to conventional methods. [Means for solving the problem] 【0009】 An ion implantation apparatus according to one aspect of the present disclosure is an ion implantation apparatus for a semiconductor wafer, comprising: a chamber; a transmitted light optical system having, in this order, a laser light source, a polarizer, a rotating and angle measuring means, a first analyzer, and a transmitted light detector, for providing and measuring transmitted light of the laser; and an ion beam source, wherein the chamber incorporates the rotating and angle measuring means, and has optical windows between the polarizer and the rotating and angle measuring means, and between the rotating and angle measuring means and the first analyzer, the rotating and angle measuring means supports the semiconductor wafer and is rotatable about at least the [11-20] direction and the [1-100] direction of the semiconductor wafer, and the polarization plane of the first analyzer is set perpendicular to the polarizer. [Effects of the Invention] 【0010】 According to this disclosure, it is possible to provide a measuring device, an ion implanter, a measuring method, and an ion implantation method that enable faster angle detection of semiconductor wafers, reduced process costs, and reduced equipment introduction costs compared to conventional methods. [Brief explanation of the drawing] 【0011】 [Figure 1] This figure shows the configuration of an ion implantation apparatus for semiconductor wafers, which is one embodiment of the present disclosure. [Figure 2] This figure shows the incident angle, incident light, and reflected light when a laser beam travels in the c-axis direction within 4H-SiC with a 4° off-angle, based on theoretical calculations. [Figure 3] This figure shows the Δk at which the light intensity is minimized, obtained by an experiment in which a 4H-SiC sample with a 4° off-angle was rotated around the [1-100] direction. [Figure 4] This figure shows Δk' at which the light intensity is minimized, obtained by an experiment in which a 4H-SiC sample with a 4° off-angle was rotated around the [11-20] direction. [Figure 5] This figure shows the Δk at which the light intensity is minimized, obtained by an experiment in which a 0° off-angle 4H-SiC sample was rotated around the [1-100] direction. [Figure 6] This figure shows Δk' at which the light intensity is minimal, obtained by an experiment in which a 0° off-angle 4H-SiC sample was rotated around the [11-20] direction. [Figure 7] This figure shows the Δk at which the light intensity is minimized, as experimentally determined for a GaN sample with a 0° off-angle. [Figure 8] This figure shows the observation results for a 4H-SiC sample with a 4° off-angle, rotated from the vertical around the [1-100] direction of the sample, at the channeling position with the smallest RBS yield. [Figure 9]This is a diagram showing a 4H-SiC sample after RBS measurement by He ion and N ion irradiation at a 4° off-angle. [Figure 10] This is a schematic diagram showing the general configuration of a development device used in an embodiment of the present disclosure. [Figure 11] This is a diagram showing the configuration of an ion implantation system, which is another embodiment of the present disclosure. 【Embodiments for Carrying Out the Invention】 【0012】 Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and modifications, corrections, and improvements can be made without departing from the scope of the disclosure. 【0013】 (Embodiment 1) When using RBS (Rutherford backscattering) to measure the crystal axis, an additional ion beam source and scattered ion detector are required, which increases the device cost. Also, since it takes time to switch the ion beam source, the process cost also increases. Therefore, it is desirable to optically measure the crystal axis. Thus, the following principles are used in the present disclosure. · SiC, which is a uniaxial optical crystal, has different refractive indices of light in the c-axis direction and other directions. · Therefore, light traveling in a direction other than the c-axis inside SiC is affected by the anisotropy of the refractive index, and the polarization direction rotates. · On the other hand, light traveling in a direction parallel to the c-axis has an isotropic refractive index situation, so the polarization direction does not change. · If linearly polarized light is incident parallel to the c-axis of SiC and the transmitted light is observed through a polarizer orthogonal to the linearly polarized light, the light intensity becomes extremely small. · By changing the angle of SiC, the point where the light intensity becomes extremely small is the c-axis. 【0014】 As shown in FIG. 1, an ion implantation apparatus 1 for implanting ions into a semiconductor wafer 50 includes a chamber 2 having optical windows 5a, 5b, and 5c, a measurement stage 6 installed inside the chamber 2, a transmitted light optical system installed outside the chamber 2 and configured in combination with the chamber 2, and a reflected light optical system configured in combination with the chamber 2. Hereinafter, in the first embodiment, a 4° off-angle SiC wafer will be described as an example of the semiconductor wafer 50. However, the present disclosure is not limited to the semiconductor wafer 50 being a 4° off-angle SiC wafer. 【0015】 The transmitted light optical system is an optical system that irradiates the semiconductor wafer 50 with transmitted light 14 that is laser light and measures the transmitted light 14 that has passed through the semiconductor wafer 50. The transmitted light optical system includes a laser light source 3, a polarizer 4, an optical window 5a, a measurement stage 6, an optical window 5c, a first analyzer 7a, and a transmitted light detector 8 in this order, and the transmitted light 14 irradiated from the laser light source 3 reaches the transmitted light detector 8. The polarization plane of the first analyzer 7a is installed orthogonally to the polarization plane of the polarizer 4. 【0016】 More specifically, the state where the polarization planes of the polarizer 4 and the first analyzer 7a are orthogonal means that the polarization plane created by the polarizer 4 and the direction of the polarization plane allowed by the first analyzer 7a intersect at an angle of 90°. In this arrangement, most, ideally all, of the transmitted light 14 that has passed through the polarizer 4 is blocked by the first analyzer 7a. 【0017】 Therefore, when the transmitted light measurement is performed by the transmitted light detector 8, since the polarization plane of the first analyzer 7a is installed orthogonally to the polarization plane of the polarizer 4, the transmitted light 14 does not reach the transmitted light detector 8 unless a birefringence phenomenon occurs in the semiconductor wafer 50. 【0018】 The above-described reflected light optical system is an optical system for measuring reflected light 15, which is transmitted light 14 reflected by the semiconductor wafer 50. The above-described reflected light optical system has an optical window 5b, a second analyzer 7b, and a reflected light detector 9, which are located outside the chamber 2, in that order. The reflected light 15 from the semiconductor wafer 50 relative to the transmitted light 14 reaches the reflected light detector 9 via the optical window 5b and the second analyzer 7b. 【0019】 The polarization plane of the second analyzer 7b is positioned perpendicular to the polarization plane of the polarizer 4. 【0020】 More specifically, the state in which the polarization planes of polarizer 4 and second analyzer 7b are orthogonal means that the direction of the polarization plane created by polarizer 4 and the direction of the polarization plane allowed by second analyzer 7b intersect each other at an angle of 90°. In this configuration, most, ideally all, of the reflected light 15 reflected by the semiconductor wafer 50 is blocked by the second analyzer 7b. 【0021】 Therefore, when reflected light is measured by the reflected light detector 9, the polarization plane of the second analyzer 7b is positioned perpendicular to the polarization plane of the polarizer 4. As a result, unless birefringence occurs in the semiconductor wafer 50, the reflected light 15 will not reach the reflected light detector 9. 【0022】 Optical windows 5a, 5b, and 5c can be appropriately selected from known materials such as quartz windows, glass windows, sapphire windows, crystal windows, and lead glass, depending on the type and intensity of transmitted light 14, the semiconductor wafer 50, and the ion implantation conditions. For the chamber 2, any known material can be used that can achieve and maintain a vacuum level inside the chamber suitable for ion implantation. Its shape can be retrofitted to a known ion implantation apparatus, or it can be designed to accommodate the ion implantation apparatus 1 from the design stage. The appropriate selection can be made considering process costs and other factors. 【0023】 The laser light source 3 can be, for example, a continuous-wave semiconductor laser, and visible light with a wavelength of 380-780 nm is preferred from the viewpoint of being visible. 【0024】 The polarizer 4 can be a known type capable of polarizing transmitted light 14 from the laser light source 3, but one suitable for polarizing a continuous wave semiconductor laser is preferred. The first analyzer 7a and the second analyzer 7b can be known types, but one suitable for detecting a continuous wave semiconductor laser is preferred. Both the transmitted light detector 8 and the reflected light detector 9 can be known types capable of detecting light quantity as signal intensity. 【0025】 The measurement stage 6 comprises a partially transparent stage 10 and a goniometer 11 mounted on the partially transparent stage 10, the partially transparent stage 10 having a transparent portion 10a. The semiconductor wafer 50 to be processed is supported and fixed on the mounting surface of the partially transparent stage 10. When transmitted light 14 is irradiated onto the semiconductor wafer 50 supported and fixed on the partially transparent stage 10, the transmitted light 14 that has passed through the semiconductor wafer 50 passes through the transparent portion 10a. Furthermore, a known goniometer 11 used in conjunction with the partially transparent stage 10 can be used. 【0026】 In the example shown in Figure 1, the transparent portion 10a is depicted as being approximately the same size as the semiconductor wafer 50 placed on the partially transparent stage 10 in a top view. However, this embodiment 1 is not limited to a configuration in which the semiconductor wafer 50 and the transparent portion 10a are approximately the same size. For example, based on the arrangement of the laser light source 3, the partially transparent stage 10, and the transmitted light detector 8, a transparent portion 10a of approximately the same size as the area through which transmitted light 14 from the laser light source 3 is expected to pass can be provided in a top view of the partially transparent stage 10. 【0027】 More specifically, the measurement stage 6 is attached to the drive unit 17. The drive unit 17 is configured to allow the mounting surface of the measurement stage 6 to rotate in any direction with respect to the transmitted light 14. The goniometer 11 measures the angle of the mounting surface of the measurement stage 6, in other words, the angle of the semiconductor wafer 50. That is, the measurement stage 6 can be described as a rotation and angle measuring means that is capable of rotating the semiconductor wafer 50 supported and fixed on the mounting surface described above, and is also capable of measuring the angle of the semiconductor wafer 50. 【0028】 Although the ion implantation apparatus 1 shown in Figure 1 includes both the transmitted light optical system and the reflected light optical system, this disclosure is not limited to a configuration that includes both the transmitted light optical system and the reflected light optical system. 【0029】 For example, the ion implantation apparatus according to this disclosure may not include the above-mentioned reflected light optical system, i.e., the optical window 5b, the second analyzer 7b, and the reflected light detector 9 shown in Figure 1. This ion implantation apparatus will be referred to as "Ion Implantation Apparatus A". 【0030】 Furthermore, the ion implantation apparatus according to this disclosure may have a configuration that does not include a part of the transmitted light optical system, namely the optical window 5c, the first analyzer 7a, and the transmitted light detector 8 shown in Figure 1. This ion implantation apparatus will be referred to as "ion implantation apparatus B." This is because the angle (θ, see Figure 2) of ion implantation on the semiconductor wafer 50 can be determined even without the optical window 5c, the first analyzer 7a, and the transmitted light detector 8. On the other hand, by including the reflected light optical system, the angle (θ, see Figure 2) of ion implantation can be measured and confirmed by the reflected light 15. 【0031】 Furthermore, in the ion implantation apparatus B described above, the partially transparent stage 10 does not need to have a transparent portion 10a. The ion implantation apparatus B described above is a device that measures reflected light 15 reflected by the semiconductor wafer 50 without measuring the transmitted light intensity of the transmitted light 14 that passes through the semiconductor wafer 50. Therefore, it is not necessary to pass the transmitted light 14 that has passed through the semiconductor wafer 50 further through the partially transparent stage 10. In other words, Embodiment 1 is not limited to a configuration in which the partially transparent stage 10 has a transparent portion 10a, and the transparent portion 10a is not an essential component of Embodiment 1. 【0032】 Ion implantation into the semiconductor wafer 50 is performed by an ion beam 13 emitted from an ion beam source 12 onto the semiconductor wafer 50 under vacuum. The ion beam source 12 and the ion beam 13 can be appropriately selected from known technologies depending on the purpose and application of ion implantation into the semiconductor wafer 50. The vacuum conditions can also be similarly selected. 【0033】 The semiconductor wafer 50 supported by the measurement stage 6 can be, depending on its crystal structure, a SiC wafer or a GaN wafer, for example, in which the transmitted light intensity can be measured by the transmitted light detector 8, or a bonded SiC wafer, for example, in which the transmitted light intensity cannot be measured. 【0034】 For SiC wafers, the transmitted light intensity can be measured, and the typical setting is 4° off. For GaN wafers, the transmitted light intensity can be measured, and the typical setting is 0° off. Therefore, ion implantation apparatus 1 shown in Figure 1, or ion implantation apparatus A described above, can be applied. On the other hand, for bonded SiC wafers, etc., where the transmitted light intensity cannot be measured, ion implantation apparatus 1 shown in Figure 1, or ion implantation apparatus B described above, can be applied. 【0035】 As shown in Figure 2, for a 4H-SiC sample 52 (hereinafter sometimes referred to as "4H-SiC52") with an off-angle of 4°, the c-axis 46 of 4H-SiC52 is 4° with respect to the direction H perpendicular to the surface 44 (SiC surface 44) of 4H-SiC52 (hereinafter sometimes referred to as "perpendicular direction H"). The incident angle θ is the angle between the incident light 43 and the direction H perpendicular to the incident light in the [11-20] direction of 4H-SiC52. The incident light 43 corresponds to the transmitted light 14 shown in Figure 1. The incident angle θ of the incident light 43 is measured by the goniometer 11 shown in Figure 1. The drive unit 17 shown in Figure 1 changes the incident angle θ by rotating the measurement stage 6 in an arbitrary direction relative to the incident light 43. 【0036】 Since the refraction angles of normal light and extraordinary light are approximately equal, the refractive index of normal light (hereinafter sometimes referred to as "normal light refractive index") ω was used as the refractive index of 4H-SiC52. Using a normal light refractive index ω of 2.71 to 2.83 for 4H-SiC52, and using Snell's law expressed in equation (1), the incident angle k when the laser light from the interior 45 of 4H-SiC52 (hereinafter sometimes referred to as "SiC interior 45") propagates in the direction of the c-axis 46 is found to be approximately 11.0° to 11.5°. Note that the direction of the c-axis 46 is the direction of

[0001] . 【0037】 【number】 In other words, when the incident angle k of the laser light incident on 4H-SiC52 is approximately 11.0° to 11.5°, that is, when the laser light is incident light 42, the incident light 42 travels through the interior 45 of 4H-SiC52 (interior SiC 45) in the direction of the c-axis 46. The incident light 43 travels in the direction of the arrow labeled 49 in Figure 2. The incident light 42 corresponds to the transmitted light 14 shown in Figure 1. Since the incident light 42 travels in the direction of the c-axis 46 (the direction of the arrow labeled 48 in Figure 2), birefringence does not occur, and the light intensity measured by the transmitted light detector 8 shown in Figure 1 becomes minimal. The incident light 42 becomes the transmitted light 14, and the light intensity of the transmitted light 14 can be measured by the transmitted light detector 8. As a result, ion implantation can be performed in the direction of the c-axis 46. On the other hand, in Figure 2, Δk represents the angular deviation from the minimum value (the angular deviation between the incident light 42 and the incident light 43). 【0038】 Regarding the reflected light 47, the angle between the reflected light 47 and the perpendicular direction H in the [11-20] direction of 4H-SiC52 is also θ. Therefore, the light intensity of the reflected light 47 can be measured by the reflected light detector 9 instead of the transmitted light 14. As a result, ion implantation can be performed in the c-axis direction 46 in the same manner as when measuring the light intensity of the transmitted light 14. 【0039】 More specifically, the measurement stage 6 is rotated in an arbitrary direction relative to the incident light 43, that is, the incident angle θ is changed, and at each incident angle θ, the light intensity of the transmitted light 14 is measured by the transmitted light detector 8, or the light intensity of the reflected light 47 is measured by the reflected light detector 9, as described above. Then, the rotation of the measurement stage 6 is stopped at the incident angle θ where the measurement result is minimal. The incident angle θ at the time the rotation of the measurement stage 6 is stopped is the incident angle k described above, i.e., approximately 11.0° to 11.5°. The c-axis 46 direction of the semiconductor wafer 50 (in this case, 4H-SiC 52) placed on the stopped measurement stage 6 coincides with the direction in which the ion beam source 12 is positioned as seen from the 4H-SiC 52. The ion beam 13 emitted from the ion beam source 12 is incident on the 4H-SiC 52 in the c-axis 46 direction. 【0040】 In this embodiment 1, a 4° off-angle SiC wafer (particularly 4H-SiC) is used as an example of the semiconductor wafer 50 for explanation. However, as stated at the beginning of this embodiment 1, this disclosure is not limited to a 4° off-angle SiC wafer for the semiconductor wafer 50. That is, the semiconductor wafer 50 may be a SiC wafer with a different off-angle than the 4° off-angle SiC wafer, or a SiC wafer of a different polytype than the 4H-SiC wafer. Furthermore, the semiconductor wafer 50 may be a sapphire wafer or a gallium nitride wafer. It goes without saying that sapphire wafers and gallium nitride wafers are available in a variety of off-angles. Moreover, it is clear that different types of semiconductor wafers 50 usually have different refractive indices. 【0041】 The ion implanter 1 is compatible with various types of semiconductor wafers 50. The ion implanter 1 is equipped with an adjustment mechanism that adjusts the direction of transmitted light 14 from the laser light source 3 toward the measurement stage 6 so that it can be applied to multiple types of wafers, including 4° off-angle SiC wafers. This adjustment mechanism appropriately adjusts the emission direction of the transmitted light 14 emitted from the laser light source 3 according to the type of semiconductor wafer 50. For example, if the semiconductor wafer 50 is a 0° off-angle SiC wafer, it is not necessary to consider the 4° off-angle, and therefore adjustment of the emission direction of the transmitted light 14 is necessary. In this way, this embodiment 1 enables efficient and accurate optical intensity measurement even for semiconductor wafers 50 with different off-angles. Similarly, it enables efficient and accurate optical intensity measurement for semiconductor wafers 50 with different polytypes and semiconductor wafers 50 made of different materials. 【0042】 In general ion implantation equipment, a single-wafer method is used, where wafers are processed one at a time. When processing multiple wafers continuously, for each wafer, As described above, the incident angle θ that minimizes the measurement result of the light intensity measurement should be determined. Furthermore, if the multiple wafers to be processed sequentially are of the same type, for example, if all wafers are 4H-SiC with a 4° off-angle, the incident angle θ should be determined only for the first wafer to be processed among the multiple wafers to be processed sequentially. For subsequent wafers, the incident angle θ determined for the first wafer should be used, and this incident angle θ should be set to the measurement stage 6. 【0043】 According to the ion implantation apparatus of this disclosure, in channeling ion implantation, wafer angle detection can be performed solely by detecting light intensity, resulting in high speed and reduced process costs. Furthermore, since ion implantation equipment for Rutherford backscattering is not required, equipment introduction costs can also be reduced. 【0044】 (Embodiment 2) The following describes Embodiment 2 of this disclosure. In Embodiment 1 described above, both the measurement of transmitted or reflected light intensity and the subsequent ion implantation were performed in the chamber 2 shown in Figure 1. That is, the light intensity measurement and ion implantation were performed in the same chamber, and the device for performing the light intensity measurement and the device for performing the ion implantation were integrated. 【0045】 In contrast, in this second embodiment, the device for measuring light intensity and the device for ion implantation are not integrated; the two devices are separate entities. This is a major difference between this second embodiment and the first embodiment described above. 【0046】 Figure 11 is a diagram showing the configuration of the ion implantation system according to this second embodiment. The ion implantation system shown in Figure 11 comprises a measuring device 200, an ion implantation device 300, and a transport device 400. 【0047】 First, let me explain the measuring device 200. 【0048】 The measuring device 200 includes a chamber 2X having optical windows 5X and 5cX, a measuring stage 6X, a laser light source 3X that emits transmitted light 14X which is laser light, a polarizer 4X, a first analyzer 7aX, a transmitted light detector 8X, a second analyzer 7bX, and a reflected light detector 9X. 【0049】 The measurement stage 6X comprises a partially transparent stage 10X and a goniometer 11X mounted on the partially transparent stage 10X, the partially transparent stage 10X having a transparent portion 10aX. The semiconductor wafer 50X to be processed is supported and fixed on the mounting surface of the partially transparent stage 10X. The measurement stage 6X is also attached to the drive unit 17X. 【0050】 The laser light source 3X, polarizer 4X, optical window 5X, first analyzer 7aX, and transmitted light detector 8X are arranged in this order to constitute a transmitted light optical system. This transmitted light optical system has the same configuration and function as the transmitted light optical system of Embodiment 1 described above. 【0051】 The optical window 5X, the second analyzer 7bX, and the reflected light detector 9X are arranged in this order to constitute a reflected light optical system. This reflected light optical system has the same configuration and function as the reflected light optical system of Embodiment 1 described above. 【0052】 Here, since the components shown in Figure 11 and the components shown in Figure 1, which are assigned component numbers with the letter "X" removed from the end of the component numbers, have the same configuration and function, their descriptions will not be repeated. However, the optical window 5X shown in Figure 11 also serves as the optical windows 5a and 5b shown in Figure 1. 【0053】 The chamber 2X of the measuring device 200 is further equipped with an opening / closing door 2X-OUT that connects the inside and outside of the chamber 2X. The opening / closing door 2X-OUT will be described later. 【0054】 Next, the ion implantation apparatus 300 will be described. 【0055】 The ion implantation apparatus 300 comprises an ion beam source 301 that emits an ion beam 302, a chamber 303, a platen 304 on which a semiconductor wafer (not shown) is supported and fixed, a goniometer 305, a drive unit 306, and an opening / closing door 303-IN connecting the inside and outside of the chamber 303. The ion beam source 301, goniometer 305, and drive unit 306 have the same configuration and function as the ion beam source 12, goniometer 11, and drive unit 17 that constitute the ion implantation apparatus 1 shown in Figure 1. The chamber 303 differs from chamber 2 shown in Figure 1 only in that it is provided with an opening / closing door 303-IN. The platen 304 also differs from the partially transparent stage 10 shown in Figure 1 only in that it does not have a transparent portion 10a. However, since the ion implantation process involves high energy, the platen 304 may also have a heating function. The platen 304 may also have a cooling function. Furthermore, the platen 304 may be electrically tuned to match the characteristics of the ion beam 302. For example, a specific voltage may be applied to the platen 304 to improve the efficiency of ion implantation into the semiconductor wafer 50X. 【0056】 Finally, I will explain the conveying device 400. 【0057】 The transport device 400 includes a chamber 500, a transport stage 501, a goniometer 502, a drive unit 503, a movable part 504, an opening / closing door 500-IN, and an opening / closing door 500-OUT. The transport stage 501, the goniometer 502, the drive unit 503, and the movable part 504 constitute a transport robot that transfers semiconductor wafers 50X from the chamber 2X of the measuring device 200 to the chamber 303 of the ion implanter 300. Note that the configuration of the transport robot shown in Figure 11 is an example, and this disclosure is not limited to this configuration. 【0058】 The transport stage 501 is attached to the movable part 504, and the transport stage 501 moves as the movable part 504 expands, contracts, and bends. The transport stage 501 moves the semiconductor wafer 50X between the chamber 2X of the measuring device 200 and the chamber 303 of the ion implanter 300. During this movement, the transport stage 501 receives the semiconductor wafer 50X from the partially transparent stage 10X in the chamber 2X and passes the semiconductor wafer 50X to the platen 304 in the chamber 303. The operation of the movable part 504 is controlled by the drive unit 503. The angle of the transport stage 501 is measured by the goniometer 502 and set to the angle of the transport stage 501 when receiving the semiconductor wafer 50X from the partially transparent stage 10X in the chamber 2X. 【0059】 Next, the differences between the ion implantation system according to this second embodiment and the ion implantation apparatus 1 according to the first embodiment described above will be explained in detail with reference to Figure 11. 【0060】 The measuring device 200 and the ion implanter 300 are positioned close to each other for the purpose of ion implantation of the semiconductor wafer 50X. A transport device 400 for efficiently moving the semiconductor wafer 50X is installed between the measuring device 200 and the ion implanter 300, and a transport robot is positioned inside the transport device 400. 【0061】 Chamber 2X of the measuring device 200 and chamber 500 of the transport device 400 are connected via openable doors, namely door 2X-OUT and door 500-IN. When both doors 2X-OUT and 500-IN are open, chamber 2X of the measuring device 200 and chamber 500 of the measuring device 200 become continuous. In this state, the transport robot receives the semiconductor wafer 50X located inside chamber 500 of the measuring device 200. 【0062】 Similarly, the chamber 303 of the ion implanter 300 and the chamber 500 of the transport device 400 are connected by opening and closing doors, namely, opening and closing door 303-IN and opening and closing door 500-OUT. When both opening and closing doors 303-IN and 500-OUT are open, the transport robot transfers the semiconductor wafer 50X into the chamber 303 of the ion implanter 300. Through this coordination, the semiconductor wafer 50X is moved efficiently and accurately from the measuring device 200 to the ion implanter 300. 【0063】 The measuring stage 6X of the measuring device 200, the transport stage 501 of the transport device 400, and the platen 304 of the ion implanter 300 are designed to move synchronously, thereby ensuring that the semiconductor wafer 50X is always held at the correct angle. More specifically, the drive units 17X, 503, and 306 are all connected to the control unit 600, which controls the drive units 17X, 503, and 306 to move the measuring stage 6X, the transport stage 501, and the platen 304 synchronously. This synchronized movement is important for improving the uniformity and accuracy of ion implantation. The measuring stage 6X, the transport stage 501, and the platen 304 support and fix the semiconductor wafer 50X using methods such as vacuum chucks, and are designed to minimize the angular difference between the semiconductor wafer 50X and each of the measuring stage 6X, transport stage 501, and platen 304. This minimized angular difference has a significant impact on the ion implantation depth and distribution during channeling, particularly when ion implantation is performed on the semiconductor wafer 50X on the platen 304 in the ion implantation apparatus 300. 【0064】 To ensure reliable channeling ion implantation, the angular difference between the platen 304 and the semiconductor wafer 50X must be 0.1° or less. This precision requirement is crucial for significantly improving the performance of semiconductor devices, and its importance is also highlighted in the research by "A. Inoue et al., 83rd JSAP Autumn Meeting (Sendai), 2022, 22a-B204-7; 19th Int. Conf. on Silicon Carbide and Related Materials (Davos), 2022, paper Fr-2-B.2". 【0065】 The measuring device 200, the transport device 400, and the ion implanter 300 are installed in a clean environment to prevent an increase in angular difference caused by dust and other fine particles getting trapped between the measuring stage 6X, the transport stage 501, and the platen 304 and the semiconductor wafer 50X. Such an environment is essential to minimize contamination during the manufacturing process and maintain product quality. 【0066】 Thus, the collaboration between the measuring device 200 and the ion implanter 300 enables accurate angle detection and ion implantation of the semiconductor wafer 50X in the manufacturing of semiconductor devices, resulting in a significant improvement in quality and performance. 【0067】 (Embodiment 3) The following describes Embodiment 3 of this disclosure. Embodiment 3 is an embodiment relating to a method for selecting semiconductor wafers 50 and 50X whose off-angles deviate from 4° in Embodiments 1 and 2 above, and for correcting the appropriate ion implantation angle. 【0068】 Hereinafter, Embodiment 3 will be described using the ion implantation system according to Embodiment 2 as an example. It is also possible to similarly describe Embodiment 3 using the ion implantation apparatus 1 according to Embodiment 1 as an example. 【0069】 In this third embodiment, the above-described transmission optical system and measurement stage 6X are pre-fixed in the measuring device 200 so that the light intensity of the transmitted light 14 is minimized when using a semiconductor wafer 50X having an ideal 4° off-angle. If a semiconductor wafer 50X with an off-angle deviating from 4° is placed on the measurement stage 6X fixed in this manner, the light intensity of the transmitted light 14 will not be minimized. Here, the above-described transmission optical system is used as an example. A similar explanation can be given even if the above-described reflected light optical system is used. 【0070】 Next, the measuring device 200 measures the transmitted light intensity of the transmitted light 14 that passes through the semiconductor wafer 50X, which is the target of ion implantation. The semiconductor wafer 50X that shows the minimum or close to the minimum transmitted light intensity is considered a good product, and the semiconductor wafer 50X is moved to the ion implantation device 300 by the transport device 400. In the ion implantation device 300, ion implantation is performed on the semiconductor wafer 50X that was transported by the transport device 400. 【0071】 On the other hand, in the measuring device 200, semiconductor wafers 50X with a strong transmitted light intensity measurement result of transmitted light 14 are considered defective. These semiconductor wafers 50X are not moved from the measuring device 200 to the ion implantation device 300. However, it is also possible to move semiconductor wafers 50X with a strong measurement result to the ion implantation device 300 without considering them defective, and then correct the ion implantation angle in the ion implantation device 300. 【0072】 Wafer manufacturers typically measure the off-angle of semiconductor wafers manufactured using X-rays, but this measurement is not a 100% inspection, and the tolerance for the off-angle is quite large, at 4°±0.5°. Therefore, the receiving end of the semiconductor wafers needs to inspect the off-angle. 【0073】 This third embodiment enables accurate selection of 4° off-angle SiC wafers and appropriate ion implantation in such situations. 【0074】 This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure. [Examples] 【0075】 One embodiment of this disclosure is described below. 【0076】 As the ion implantation apparatus, we assumed the ion implantation apparatus 1 shown in Figure 1. More specifically, we used the development apparatus 100 shown in Figure 10. The development apparatus 100 was assembled by arranging a laser light source (not shown), a polarizer 22, a goniometer-equipped goniometer stage 51, an analyzer 23, and a photodiode (not shown) in this order. The laser light source shown in Figure 10 corresponds to the laser light source 3 shown in Figure 1, the polarizer 22 corresponds to the polarizer 4, the goniometer stage 51 corresponds to the measurement stage 6, the analyzer 23 corresponds to the first analyzer 7a or the second analyzer 7b, and the photodiode corresponds to the transmitted light detector 8 or the reflected light detector 9. When the analyzer 23 was assigned to the first analyzer 7a and the photodiode to the transmitted light detector 8, the transmitted light intensity was as follows. 【0077】 The laser light source was a 405 nm probe laser with a laser intensity of 50 mW, and the incident angle θ at which the light intensity was minimized was determined for each sample. Figures 3 and 4 show the results when the semiconductor wafer sample was 4H-SiC with a 4° off-angle (Measurement Example 1), Figures 5 and 6 show the results when the sample was 4H-SiC with a 0° off-angle (Measurement Example 2), Figure 7 shows the results when the sample was GaN with a 0° off-angle (Measurement Example 3), and Figures 8 and 9 show the results when the sample was 4H-SiC with a 4° off-angle (Measurement Example 4, Reference Example 1). 【0078】 The method for finding the angles of incidence θ and θ' is as follows: 【0079】 (1) After supporting and fixing the sample on the goniometer stage 51, align the [11-20] direction of the sample with the rotation direction of the goniometer stage 51. 【0080】 (2) The laser 21 emitted from the laser light source is used to irradiate a sample supported and fixed on the goniometer stage 51, and the transmitted light intensity is measured using a photodiode. 【0081】 (3) By rotating the goniometer stage 51, the sample is rotated around the [1-100] direction to find the incident angle θ at which the transmitted light intensity measured by the photodiode is minimized. 【0082】 (4) By rotating the goniometer stage 51, the sample is rotated around the [11-20] direction, and the incident angle θ' at which the transmitted light intensity measured by the photodiode is further reduced is found. 【0083】 (5) Then, the sample is rotated slightly again around the [1-100] and [11-20] directions to adjust it to the angle that minimizes the transmitted light intensity. 【0084】 When the sample was a 4H-SiC with a 4° off-angle, the rotation direction was centered in the [1-100] direction, the photodiode current value without the sample was 4.9 nA, and the resolution of the multimeter measuring the photodiode current value was 20 pA, the relationship between Δk(°), which is the angular deviation from the minimum value in the rotation direction, and the photodiode current value was as shown in Figure 3. As a result, since Δk has an accuracy of ±0.1°, the transmitted light intensity is minimal when Δk=0°, and the incident angle θ at which the light intensity is minimal, as determined experimentally, was 9.88° (Measurement Example 1: Procedures 1 and 2). 【0085】 Next, with the rotation direction centered in the [11-20] direction, the deviation of the angle in the rotation direction from the minimum value, Δk'(°), was as shown in Figure 4. As a result, Δk' has an accuracy of ±0.1°, so when Δk'=0° the transmitted light intensity is minimal, and the incident angle θ' at which the light intensity is minimal, as determined by experiment, was 9.88° (Measurement Example 1: Procedure 3). Determined by experiment means that the incident angle was determined by measuring and adjusting the angle using the goniometer provided on the goniometer stage 51. 【0086】 When the sample was a 4H-SiC with a 4° off-angle, the rotation direction was centered in the [1-100] direction, the photodiode current without the sample was 2.9 nA, and the multimeter resolution was 20 pA, the deviation of the rotation angle from the minimum value, Δk(°), was as shown in Figure 5. Based on this, the incident angle θ at which the light intensity was minimum, as determined experimentally, was 0.09° (Measurement Example 2: Procedures 1 and 2). 【0087】 On the other hand, theoretical calculations show that when laser light travels in 4H-SiC with a 0° off-angle in the c-axis direction, the incident angle k is 0°. 【0088】 Next, with the rotation direction centered in the [11-20] direction, the deviation of the angle from the minimum value in the rotation direction, Δk', was as shown in Figure 6. Thus, the incident angle θ' at which the light intensity was minimal, as determined experimentally, was 0.09° (Measurement Example 2: Procedure 3). Note that the method for determining θ and θ' is the same as in Measurement Example 1. 【0089】 On the other hand, theoretical calculations show that when laser light travels in 4H-SiC with a 0° off-angle along the c-axis, the incident angle k is 0°. 【0090】 When the sample was a GaN with a 0° off-angle, the photodiode current value without the sample was 4.9 nA, and the multimeter resolution was 20 pA, the angle deviation Δk in the rotational direction from the minimum value was as shown in Figure 7. This indicates that the incident angle θ at which the light intensity was minimum, as determined experimentally, was 0° (Measurement Example 3). The method for determining θ is the same as in Measurement Example 1. 【0091】 Figure 9 shows a 4H-SiC sample with a 4° off-angle after Rutherford backscattering (RBS) measurement by irradiation with He and N ions. Angle-dependent RBS measurement was performed on SiC sample 53, and N ion channeling implantation was performed from a direction parallel to the

[0001] direction (angle 0°). 2 MeV He ions were irradiated onto the n-type 4H-SiC epitaxial film sample while changing the sample angle. Here, the sample is a typical SiC product with a crystal plane that is 4° off-angle in the [11-20] direction from the (0001) plane. The angle at which channeling occurs was estimated by counting the number of ions returned from the sample due to the RBS phenomenon during ion irradiation. Subsequently, N ions were implanted into the sample at 2 MeV at the angle at which channeling was expected to occur. The beam diameter for both ions was 1.4 mm. 【0092】 Figure 8 shows the observation results for a 4H-SiC sample with a 4° off-angle, rotated from the vertical around the [1-100] direction, and the channeling position with a small RBS yield. 【0093】 As shown in Figure 8, the sample 53 was rotated vertically around the [1-100] direction, and the channeling position with a small RBS yield was observed. As a result, the RBS yield decreased significantly at the -4° and 13° positions corresponding to the

[0001] and [11-23] directions, confirming that channeling was occurring. Furthermore, to examine the angular margin of channeling, the full width at half maximum (FWHM) of the RBS yield dip was estimated. The FWHM was larger in the

[0001] direction than in the [11-23] direction, suggesting that channeling ion implantation can be performed more easily in the

[0001] direction (Measurement Example 4). 【0094】 Furthermore, N ions were implanted at an angular position in the

[0001] direction. The distribution of the implanted ions was evaluated by secondary ion mass spectrometry, and it was confirmed that N was implanted at a depth of approximately 2 microns. Figure 9 shows the sample 54 after the experiment. It can be seen that the portion 55 irradiated with He and N ions is discolored due to damage from ion implantation (Reference Example 1). The size of the SiC sample 53 was such that the length of the elliptical side of the portion 55 irradiated with He and N ions was 15 mm. 【0095】 On the other hand, with the ion implantation apparatus according to this disclosure, it is not necessary to measure the angle of the sample separately before ion implantation, and ion implantation can be performed immediately after the angle measurement, so the angle measurement does not cause discoloration damage to the sample. 【0096】 (summary) [1] An ion implantation apparatus for a semiconductor wafer, comprising a chamber, a transmitted light optical system that provides and measures transmitted light of a laser, having in this order a laser light source, a polarizer, a rotating and angle measuring means, a first analyzer and a transmitted light detector, and an ion beam source, wherein the chamber incorporates the rotating and angle measuring means, and has optical windows between the polarizer and the rotating and angle measuring means, and between the rotating and angle measuring means and the first analyzer, the rotating and angle measuring means supports the semiconductor wafer and is rotatable in at least the [11-20] direction and the [1-100] direction, and the polarization plane of the first analyzer is set perpendicular to the polarizer, characterized in that (hereinafter sometimes referred to as "ion implantation apparatus with a transmitted light optical system, etc."). 【0097】 [2] The ion implantation apparatus described in [1] further comprises a reflected light optical system that detects reflected light from a semiconductor wafer with respect to transmitted light, having a second analyzer and a reflected light detector in that order, wherein the polarization plane of the second analyzer is set perpendicular to the polarizer. 【0098】 The ion implantation apparatus for semiconductor wafers described in [3][2] is characterized in that it does not include a first analyzer, a transmitted photodetector, and an optical window between the rotating and angle measuring means and the first analyzer. 【0099】 The ion implantation method is characterized by comprising the steps of: using the ion implantation apparatus described in [4][1], supporting and fixing a semiconductor wafer to a rotating and angle measuring means, and irradiating the semiconductor wafer with transmitted laser light; rotating the semiconductor wafer in the [11-20] direction using the rotating and angle measuring means to find the angle at which the transmitted light intensity is minimized; and rotating the semiconductor wafer in the [1-100] direction using the rotating and angle measuring means to find the angle at which the transmitted light intensity further decreases and becomes minimized, wherein the semiconductor wafer after step 3 is irradiated with an ion beam from an ion beam source under vacuum. 【0100】 In other words, it is an ion implantation method using an ion implantation device equipped with a transmitted light optical system, etc. 【0101】 The ion implantation method is characterized by comprising the steps of: using the ion implantation apparatus described in [5][2], supporting and fixing a semiconductor wafer to a rotating and angle measuring means, and irradiating the semiconductor wafer with transmitted laser light; rotating the semiconductor wafer with the rotating and angle measuring means in the [11-20] direction to find the angle at which the transmitted light intensity is minimized; rotating the semiconductor wafer with the rotating and angle measuring means in the [1-100] direction to find the angle at which the transmitted light intensity further decreases and becomes minimized; and further measuring the reflected light intensity of the light reflected by the semiconductor wafer in steps 1 to 3, wherein the semiconductor wafer after step 3 is irradiated with an ion beam from an ion beam source under vacuum. 【0102】 The ion implantation method is characterized by the following steps: using the ion implantation apparatus described in [6][3], supporting and fixing a semiconductor wafer to a rotating and angle measuring means, and irradiating the semiconductor wafer with transmitted laser light; rotating the semiconductor wafer in the [11-20] direction using the rotating and angle measuring means to find the angle at which the reflected light intensity is minimized; and rotating the semiconductor wafer in the [1-100] direction using the rotating and angle measuring means to find the angle at which the reflected light intensity further decreases and becomes minimized, and irradiating the semiconductor wafer after step 3 with an ion beam from an ion beam source under vacuum. 【0103】 In other words, it is an ion implantation method using an ion implantation device equipped with a reflected light optical system, etc. 【0104】 The ion implantation method described in any one of [7], [4], to [6] is characterized by including a step of slightly rotating the semiconductor wafer again in the [11-20] direction and the [1-100] direction before irradiating with an ion beam after step 3 to set the angle at which the transmitted light intensity is minimized. [Explanation of symbols] 【0105】 1. 300 Ion implanter, 2. 2X, 303, 500 Chamber, 3. 3X Laser light source, 4. 4X, 22 Polarizer, 5a, 5b, 5c, 5cX, 5X Optical window, 2X-OUT, 303-IN, 500-IN, 500-OUT Opening / closing door, 6. 6X Measurement stage, 7a, 7aX First analyzer, 7b, 7bX Second analyzer, 8. 8X Transmitted light detector, 9. 9X Reflected light detector, 10. 10X Partially transparent stage, 10a, 10aX Transparent section, 11. 11X, 305, 502 Goniometer, 12. 301 Ion beam source, 13. 302 Ion beam, 14. 14X Transmitted light, 15. 47 Reflected light, 17. 17X, 306, 503 Drive unit, 21 Laser, 23 Analyzer, 42, 43 Incident light, 44 SiC surface, 45 SiC interior, 50, 50X Semiconductor wafer, 51 Goniometer stage, 100 Development equipment, 200 Measurement equipment, 304 Platen, 400 Transport equipment, 501 Transport stage, 504 Movable part

Claims

[Claim 1] An ion implantation apparatus for implanting ions into a semiconductor wafer, Chamber and A transmitted light optical system having, in this order, a laser light source, a polarizer, a rotating and angle measuring means, a first analyzer, and a transmitted light detector, which provides and measures transmitted light emitted from the laser light source, Ion beam source and Equipped with, The ion implantation apparatus is characterized in that the chamber incorporates the rotating and angle measuring means, has optical windows between the polarizer and the rotating and angle measuring means, and between the rotating and angle measuring means and the first analyzer, the rotating and angle measuring means supports the semiconductor wafer and is rotatable about at least the [11-20] direction and the [1-100] direction of the semiconductor wafer, and the polarization plane of the first analyzer is set perpendicular to the polarizer. [Claim 2] The ion implantation apparatus according to claim 1 further comprises a reflected light optical system that detects the reflected light from the semiconductor wafer with respect to the transmitted light, the second analyzer and the reflected light detector in that order, wherein the polarization plane of the second analyzer is set perpendicular to the polarizer. [Claim 3] The ion implantation apparatus according to claim 2, characterized in that it does not include the first analyzer, the transmitted light detector, and the optical window between the rotating and angle measuring means and the first analyzer. [Claim 4] An ion implantation method comprising: step 1 using the ion implantation apparatus described in claim 1, supporting and fixing the semiconductor wafer to the rotating and angle measuring means, and irradiating the semiconductor wafer with the transmitted light; step 2 rotating the rotating and angle measuring means supporting and fixing the semiconductor wafer about the [11-20] direction of the semiconductor wafer to find the angle at which the light intensity of the transmitted light is minimized; and step 3 rotating the rotating and angle measuring means supporting and fixing the semiconductor wafer about the [1-100] direction of the semiconductor wafer to find the angle at which the light intensity further decreases and becomes minimized, wherein the semiconductor wafer after step 3 is irradiated with an ion beam from an ion beam source under vacuum. [Claim 5] An ion implantation method comprising: step 1 using the ion implantation apparatus described in claim 2, supporting and fixing the semiconductor wafer to the rotating and angle measuring means, and irradiating the semiconductor wafer with the transmitted light; step 2 rotating the rotating and angle measuring means supporting and fixing the semiconductor wafer about the [11-20] direction of the semiconductor wafer to find the angle at which the light intensity of the reflected light is minimized; and step 3 rotating the rotating and angle measuring means supporting and fixing the semiconductor wafer about the [1-100] direction of the semiconductor wafer to find the angle at which the light intensity further decreases and becomes minimized, wherein the semiconductor wafer after step 3 is irradiated with an ion beam from the ion beam source under vacuum. [Claim 6] An ion implantation method comprising: step 1 using the ion implantation apparatus described in claim 3, supporting and fixing the semiconductor wafer to the rotating and angle measuring means, and irradiating the semiconductor wafer with the transmitted light; step 2 rotating the rotating and angle measuring means supporting and fixing the semiconductor wafer about the [11-20] direction of the semiconductor wafer to find the angle at which the light intensity of the reflected light is minimized; and step 3 rotating the rotating and angle measuring means supporting and fixing the semiconductor wafer about the [1-100] direction of the semiconductor wafer to find the angle at which the light intensity further decreases and becomes minimized, wherein the semiconductor wafer after step 3 is irradiated with an ion beam from the ion beam source under vacuum. [Claim 7] An ion implantation method according to any one of claims 4 to 6, characterized in that, after step 3 and before irradiating with the ion beam, the rotating and angle measuring means that supports and fixes the semiconductor wafer is again slightly rotated and adjusted about the [11-20] direction and [1-100] direction of the semiconductor wafer to set the angle to the minimum light intensity. [Claim 8] An ion implantation method according to claim 7, characterized in that when irradiating with an ion beam, the direction of emission of the ion beam emitted from the ion beam source is the [0001] direction of the semiconductor wafer. [Claim 9] A measuring device for detecting the angle of a semiconductor wafer, Chamber and A transmitted light optical system having, in this order, a laser light source, a polarizer, a rotating and angle measuring means, a first analyzer, and a transmitted light detector, which provides and measures transmitted light emitted from the laser light source. Equipped with, The measuring device is characterized in that the chamber incorporates the rotating and angle measuring means, has optical windows between the polarizer and the rotating and angle measuring means, and between the rotating and angle measuring means and the first analyzer, the rotating and angle measuring means supports the semiconductor wafer and is rotatable about at least the [11-20] direction and the [1-100] direction of the semiconductor wafer, and the polarization plane of the first analyzer is set perpendicular to the polarizer. [Claim 10] A measurement method characterized by comprising: step 1 using the measuring device described in claim 9, supporting and fixing the semiconductor wafer to the rotating and angle measuring means, and irradiating the semiconductor wafer with the transmitted light; step 2 rotating the rotating and angle measuring means supporting and fixing the semiconductor wafer about the [11-20] direction of the semiconductor wafer to find the angle at which the light intensity of the transmitted light is minimized; and step 3 rotating the rotating and angle measuring means supporting and fixing the semiconductor wafer about the [1-100] direction of the semiconductor wafer to find the angle at which the light intensity further decreases and becomes minimized.

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