JP2009253174A - Impurity analysis method and impurity analysis device of semiconductor substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for simply analyzing impurity existing on an outer circumferential surface of a semiconductor substrate. <P>SOLUTION: The semiconductor substrate 4 for measurement target is sandwiched by a stage 2 of divided structure, and a flat part F centering around the outer circumferential surface of the semiconductor substrate 4 is formed by the outer circumferential surface of the semiconductor substrate 4 and the outer circumferential surface of the stage 2. The flat part F formed by the outer circumferential surface of the semiconductor substrate 4 and the outer circumferential surface of the stage 2 is irradiated with X-ray under total reflection conditions to detect fluorescent X-ray of the impurity generated from the outer circumferential surface of the semiconductor substrate 4. A contamination state by the impurity on the outer circumferential surface of the semiconductor substrate 4 is evaluated on the basis of a detection result of the florescent X-ray. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and apparatus for analyzing impurities on an outer peripheral surface of a semiconductor substrate.

  For analyzing impurities on the surface of a semiconductor substrate, a total reflection fluorescent X-ray analyzer is used as a highly sensitive and simple apparatus. The total reflection X-ray fluorescence analyzer is incorporated in a semiconductor device production line, for example, and is used for analysis and evaluation of a contamination state due to impurities of a semiconductor substrate that adversely affects device characteristics. Concerning contamination by impurities, not only the surface of the semiconductor substrate (device forming surface and its back surface) but also contamination from the transport system is localized on the outer peripheral surface including the bevel portion (chamfered portion) of the semiconductor substrate. The necessity of analyzing impurities on the outer peripheral surface is increasing.

  On the other hand, a general total reflection fluorescent X-ray analyzer uses an optical system in which the irradiated X-ray has a sheet-like spread, and therefore, the flat surface of the semiconductor substrate can be analyzed well. However, it is considered difficult to analyze the outer peripheral surface including the bevel portion (chamfered portion). As a method for analyzing the outer peripheral surface of a semiconductor substrate, the outer peripheral portion of the semiconductor substrate is brought into contact with a chemical solution to recover impurities, and the recovered impurities are analyzed with an ICP mass spectrometer or an atomic absorption spectrometer (see Patent Document 1). ) After the liquid droplet of the chemical liquid brought into contact with the outer peripheral portion of the semiconductor substrate is moved on the surface of the semiconductor substrate, the impurities collected in the liquid droplet are analyzed with a total reflection X-ray fluorescence spectrometer (Patent Document) 2) is known. A hydrofluoric acid solution or its vapor is used as a chemical solution for collecting impurities, and is also used for surface analysis of a semiconductor substrate (see Patent Document 3).

The method of collecting and analyzing impurities in a chemical solution such as a hydrofluoric acid solution is a factor that increases the analysis cost of the semiconductor substrate because it takes time to collect the impurities. Furthermore, the analysis of impurities in a chemical solution requires an ICP mass spectrometer, an atomic absorption spectrometer, and the like separately from the total reflection X-ray fluorescence analyzer used for analysis of a flat surface, which increases the apparatus cost. If the droplets collected from the outer periphery of the semiconductor substrate are moved over the surface of the semiconductor substrate, the impurities present on the surface can be recovered, but other than the impurities attached to the outer periphery and the surface. In addition, only an analysis result including impurities in the oxide film and nitride film formed on the surface of the semiconductor substrate can be obtained, and the contamination status of the semiconductor substrate cannot be accurately evaluated.
JP-A-11-204604 JP 2005-109292 A Republished patent WO2005 / 073692

  An object of the present invention is to provide an impurity analysis method and an impurity analysis apparatus for a semiconductor substrate, which can easily analyze impurities existing on the outer peripheral surface of the semiconductor substrate.

  An impurity analysis method for a semiconductor substrate according to one embodiment of the present invention includes sandwiching a semiconductor substrate with a stage having a divided structure, and the outer peripheral surface of the semiconductor substrate and the outer peripheral surface of the stage are centered on the outer peripheral surface of the semiconductor substrate. An impurity generated from the outer peripheral surface of the semiconductor substrate by irradiating the flat portion formed by the step of forming a flat portion and the outer peripheral surface of the semiconductor substrate and the outer peripheral surface of the stage under total reflection conditions. And a step of evaluating the contamination state of the outer peripheral surface of the semiconductor substrate by the impurities based on the detection result of the fluorescent X-rays.

  An impurity analysis apparatus for a semiconductor substrate according to another aspect of the present invention includes a stage having a split structure capable of sandwiching a semiconductor substrate, and the semiconductor substrate includes an outer peripheral surface of the semiconductor substrate and an outer peripheral surface of the stage. A X-ray is applied to the flat portion formed by the stage portion that forms a flat portion centered on the outer peripheral surface of the semiconductor substrate and the outer peripheral surface of the semiconductor substrate sandwiched between the stages and the outer peripheral surface of the stage under a total reflection condition. An X-ray irradiation unit for irradiation and a fluorescent X-ray detection unit for detecting fluorescent X-rays of impurities generated from the outer peripheral surface of the semiconductor substrate based on the X-ray irradiation are provided.

  According to the impurity analysis method and the impurity analysis apparatus for a semiconductor substrate according to the aspect of the present invention, impurities existing on the outer peripheral surface of the semiconductor substrate can be easily analyzed. Therefore, it is possible to reduce the cost and labor required for analyzing the outer peripheral surface of the semiconductor substrate.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a semiconductor substrate impurity analyzing apparatus according to an embodiment of the present invention. 2 and 3 are diagrams showing a first embodiment to which the impurity analyzer shown in FIG. 1 is applied, and FIGS. 4 and 5 are diagrams showing a second embodiment to which the impurity analyzer shown in FIG. 1 is applied. is there. First, a first embodiment will be described with reference to FIGS. 1 to 3.

  The impurity analysis apparatus 1 for a semiconductor substrate shown in FIGS. 1 to 3 includes a stage unit 3 having a stage 2 having a divided structure. The stage 2 is divided into two so that a disk-shaped semiconductor substrate (semiconductor wafer) 4 to be measured can be sandwiched. Specifically, the stage 2 has a first stage 2A and a second stage 2B. is doing. When the disc-shaped semiconductor substrate 4 is sandwiched between the first and second stages 2A and 2B, a flat portion F can be formed by the outer peripheral surface (end surface) of the semiconductor substrate 4 and the outer peripheral surfaces of the stages 2A and 2B. It has such a shape. The flat portion F is formed in the thickness direction of the semiconductor substrate 4 sandwiched between the stages 2A and 2B.

  Specifically, the stage 2 having a divided structure includes a first stage 2A and a second stage 2B having the same diameter as the disk-shaped semiconductor substrate 4. For example, when the diameter of the semiconductor substrate 4 is 300 mm, a resin disc having a diameter of 300 mm, such as a disc made of acrylic resin or polycarbonate resin, is used for the first and second stages 2A and 2B. It is preferable that the resin disk constituting each stage 2A, 2B has a small amount of impurities on the outer peripheral surface. The thicknesses of the stages 2A and 2B are not particularly limited as long as the flat portions F that totally reflect the irradiated X-rays can be formed.

  The first and second stages 2A and 2B have the same diameter as the semiconductor substrate 4, and their outer peripheral portions are optically flattened in the thickness direction. Therefore, when the semiconductor substrate 4 is sandwiched between the first and second stages 2 </ b> A and 2 </ b> B, the flat portion F centering on the outer peripheral surface of the semiconductor substrate 4 can be formed. That is, the flat part F centering on the outer peripheral surface of the semiconductor substrate 4 is formed by the outer peripheral surface of the semiconductor substrate 4 and the outer peripheral surfaces of the stages 2A and 2B. Here, the flat portion F may be a portion that is flat with respect to the irradiated X-ray and can totally reflect the irradiated X-ray, and does not mean a flat shape.

  The first and second stages 2A and 2B are provided with rotating shafts 5A and 5B at positions corresponding to the center of the semiconductor substrate 4 sandwiched between them. The stage 2 is configured to rotate the semiconductor substrate 4 sandwiched between the first and second stages 2A and 2B by rotationally driving the rotation shafts 5A and 5B with a rotation mechanism (not shown). That is, the stage 2 has a divided structure that can sandwich the semiconductor substrate 4 and a rotating structure that can rotate the sandwiched semiconductor substrate 4. Stage 2 is a rotary stage.

  The semiconductor substrate 4 is disposed in a measurement chamber (not shown) while being sandwiched between the first and second stages 2A and 2B. In the measurement chamber, the rotation shafts 5A and 5B of the first and second stages 2A and 2B are connected to a rotation mechanism (not shown). Thereby, the semiconductor substrate 4 sandwiched between the first and second stages 2A and 2B can be rotated in the circumferential direction. The analysis of the semiconductor substrate 4 can be performed in either a state where the stages 2A and 2B are rotated or a state where the stage is stationary without rotating.

  An X-ray irradiation unit having an X-ray generation source (X-ray tube or the like) 6, a spectroscope (not shown) or the like is disposed outside the measurement chamber. X-rays (incident X-rays) 7 emitted from the X-ray generation source 6 pass through a spectroscope (not shown), and are then measured from the same direction as the rotation direction of the stage 2 (circumferential direction of the semiconductor substrate 4). Is incident on the inside. Incident X-rays 7 are applied to a flat portion F formed by the outer peripheral surface of the semiconductor substrate 4 and the outer peripheral surfaces of the stages 2A and 2B so that the outer peripheral surface (end surface / bevel portion) of the semiconductor substrate 4 is at the center. The Incident X-rays 7 are irradiated to the flat portion F under total reflection conditions. X-rays (reflected X-rays) 8 totally reflected by the flat portion F are absorbed by the inner wall of the measurement chamber.

  Incident X-rays 7 are irradiated from the circumferential direction of the semiconductor substrate 4 to the flat portion F including the outer peripheral surface of the semiconductor substrate 4. At this time, the incident X-ray 7 is reflected under the total reflection condition by controlling the incident angle of the incident X-ray 7 with respect to the flat portion F. For example, the incident X-ray 7 is totally reflected in the irradiation region A by adjusting the incident angle θ with respect to the irradiation region A including the flat portion F centering on the outer peripheral surface of the semiconductor substrate 4 on the low incident angle side. The X-ray generation source 6 has a mechanism for adjusting the incident angle of the incident X-ray 7 with respect to the flat portion F. The incident angle may be adjusted on the stage 2 side.

  Immediately above the irradiation area A of the incident X-ray 7, the fluorescence of impurities generated from the outer peripheral surface of the semiconductor substrate 4 when the flat portion F including the outer peripheral surface of the semiconductor substrate 4 is irradiated with the X-ray 7 under the total reflection condition. An X-ray detector 9 for detecting X-rays is arranged as a fluorescent X-ray detector. When the irradiation region A including the flat part F is irradiated with the X-rays 7 under the total reflection condition, fluorescent X-rays are generated from the outer peripheral surface of the semiconductor substrate 4 located at the center of the flat part F. The fluorescent X-rays generated from the irradiation region A include fluorescent X-rays caused by impurities existing on the outer peripheral surface of the semiconductor substrate 4. Therefore, by detecting the fluorescent X-rays generated from the irradiation region A with the X-ray detector 9, the type and amount of impurity elements present on the outer peripheral surface of the semiconductor substrate 4 are evaluated from the detection result (fluorescent X-ray spectrum). can do.

  A semiconductor detector (SSD) is preferably used as the X-ray detector 9. The irradiation region A of the incident X-ray 7 has a depth parallel to the irradiation direction with respect to the circumferential direction of the semiconductor substrate 4 and a width perpendicular to the irradiation direction with respect to the thickness direction of the semiconductor substrate 4. Accordingly, fluorescent X-rays of impurities existing on the surface of the stage 2 are also generated. On the other hand, since the sensitivity distribution of the semiconductor detector 9 is about several millimeters in diameter at the center, the sensitivity distribution of the semiconductor detector 9 occurs from the outer peripheral surface of the semiconductor substrate 4 having a thickness of about 1 mm at the center of the sensitivity distribution of the semiconductor detector 9. The semiconductor detector 9 is arranged so as to detect the fluorescent X-rays. Thereby, the detection sensitivity of the fluorescent X-rays from the semiconductor substrate 4 is improved. That is, it becomes possible to improve the analysis accuracy of impurities existing on the outer peripheral surface of the semiconductor substrate 4.

  Next, the analysis process of the semiconductor substrate 4 using the impurity analyzer 1 according to the first embodiment will be described. First, a disk-shaped semiconductor substrate (semiconductor wafer) 4 to be measured is sandwiched between the first stage 2A and the second stage 2B, and is set in the measurement chamber in this state. In the measurement chamber, the semiconductor substrate 4 sandwiched between the stages 2A and 2B is rotatable. Next, after adjusting the incident angle of the incident X-ray 7 to the total reflection condition, the outer peripheral surface of the semiconductor substrate 4 is rotated while rotating the semiconductor substrate 4 in the same direction as the irradiation direction of the incident X-ray 7 or in the direction toward the irradiation direction. The incident X-rays 7 are irradiated to the irradiation region A including the flat portion F centered at the center.

  The X-ray detector 9 detects the fluorescent X-rays generated from the irradiation region A based on the irradiation of the incident X-ray 7 under the total reflection condition. Based on the detection result of the fluorescent X-rays by the X-ray detector 9, the type and amount of impurity elements (such as heavy metal elements) present on the outer peripheral surface of the semiconductor substrate 4 are evaluated. For the sensitivity required for measuring the contamination concentration (impurity element amount) on the outer peripheral surface of the semiconductor substrate 4, the background of impurities from the stage 2 and the shape of the outer peripheral surface of the semiconductor substrate 4 (the shape of the chamfered end face (bevel portion)) ) Scattering background is sufficiently low. Therefore, the contamination state of the outer peripheral surface of the semiconductor substrate 4 is evaluated by detecting fluorescent X-rays from the irradiation region A including the flat portion F formed by the outer peripheral surface of the semiconductor substrate 4 and the outer peripheral surface of the stage 2. be able to.

  Further, by irradiating the incident X-ray 7 while continuously rotating the semiconductor substrate 4, the detection result of the impurity by the fluorescent X-ray is obtained as an integration result. Therefore, the analysis accuracy of impurities existing on the outer peripheral surface of the semiconductor substrate 4 can be increased. The analysis of the outer peripheral surface of the semiconductor substrate 4 can be performed by partially irradiating the incident X-rays 7 on a specific portion of the outer peripheral surface without rotating the semiconductor substrate 4. By irradiating the incident X-rays 7 without rotating the semiconductor substrate 4, the impurity distribution and the like on the outer peripheral surface of the semiconductor substrate 4 can be evaluated.

  In addition, when the shape (bevel shape) of the outer peripheral surface of the semiconductor substrate 4 is extreme, or when there is a possibility that the outer peripheral surface may be worn in the device manufacturing process, the total reflection condition of the incident X-ray 7 may be lowered. Conceivable. For such a point, a total reflection fluorescent X-ray analysis is performed using a semiconductor substrate 4 that has not been contaminated in advance, and an analysis result as a blank is obtained. And the total reflection fluorescent X-ray analysis of the semiconductor substrate 4 conveyed by an actual device manufacturing process is implemented, and the contamination state by the impurity of the outer peripheral surface of the semiconductor substrate 4 is evaluated by comparing the analysis result with a blank. be able to. Thus, the impurity analysis on the outer peripheral surface of the semiconductor substrate 4 can be performed not only as an evaluation by quantifying the amount of impurities but also as a comparative evaluation.

  Next, a second embodiment will be described with reference to FIG. 1, FIG. 4, and FIG. The impurity analyzer 1 according to the second embodiment has the same configuration as that of the first embodiment except that the irradiation direction of the incident X-ray 7 with respect to the flat end F is different. That is, in the impurity analyzer 1 according to the second embodiment, the incident X-rays 7 emitted from the X-ray generation source are in the thickness direction of the semiconductor substrate 4 with respect to the flat portion F including the outer peripheral surface of the semiconductor substrate 4. In other words, irradiation is performed from a direction perpendicular to the rotation direction of the stage 2. Also in the second embodiment, by controlling the incident angle of the X-ray 7 with respect to the irradiation region A including the flat portion F, the incident X-ray 7 is reflected under the total reflection condition.

  When irradiating the incident X-rays 7 in the thickness direction of the semiconductor substrate 4, the irradiation region A has a depth parallel to the irradiation direction with respect to the thickness direction of the semiconductor substrate 4 and an irradiation direction with respect to the circumferential direction of the semiconductor substrate 4. And a width orthogonal to each other. Accordingly, fluorescent X-rays of impurities existing on the surface of the stage 2 are also generated. With respect to such a point, as described above, the semiconductor detector 9 is arranged so as to detect fluorescent X-rays generated from the outer peripheral surface of the semiconductor substrate 4 at the center of its sensitivity distribution, whereby fluorescence from the semiconductor substrate 4 is detected. X-ray detection sensitivity can be improved.

  The analysis process of the semiconductor substrate 4 using the impurity analysis apparatus 1 according to the second embodiment is performed as follows. First, a disk-shaped semiconductor substrate (semiconductor wafer) 4 to be measured is sandwiched between the first stage 2A and the second stage 2B, and is set in the measurement chamber in this state. Next, after adjusting the incident angle of the incident X-ray 7 to the total reflection condition, the flat portion centered on the outer peripheral surface of the semiconductor substrate 4 while rotating the semiconductor substrate 4 in a direction orthogonal to the irradiation direction of the incident X-ray 7. The incident X-ray 7 is irradiated to the irradiation area A including F.

  The X-ray detector 9 detects the fluorescent X-rays generated from the irradiation region A based on the irradiation of the incident X-ray 7 under the total reflection condition. Based on the detection result of the fluorescent X-rays by the X-ray detector 9, the type and amount of impurity elements (such as heavy metal elements) present on the outer peripheral surface of the semiconductor substrate 4 are evaluated. Also in the second embodiment, with respect to the sensitivity necessary for measuring the contamination concentration (impurity element amount) on the outer peripheral surface of the semiconductor substrate 4, the background of the impurities from the stage 2 and the shape (chamfered) of the outer peripheral surface of the semiconductor substrate 4. Scattering background due to the shape of the end face (bevel portion) is sufficiently low. Therefore, the contamination state of the outer peripheral surface of the semiconductor substrate 4 can be evaluated by detecting fluorescent X-rays from the irradiation region A including the flat portion F.

  Further, by irradiating the incident X-ray 7 while continuously rotating the semiconductor substrate 4, the detection result of the impurity by the fluorescent X-ray is obtained as an integration result. Therefore, the analysis accuracy of impurities existing on the outer peripheral surface of the semiconductor substrate 4 can be increased. The analysis of the outer peripheral surface of the semiconductor substrate 4 can be performed by partially irradiating the incident X-rays 7 on a specific portion of the outer peripheral surface without rotating the semiconductor substrate 4. By irradiating the incident X-rays 7 without rotating the semiconductor substrate 4, the impurity distribution and the like on the outer peripheral surface of the semiconductor substrate 4 can be evaluated. Also in the second embodiment, it is possible to evaluate the contamination state of the outer peripheral surface of the semiconductor substrate 4 by comparing the total reflection fluorescent X-ray analysis result of the semiconductor substrate 4 with the blank as in the first embodiment. is there.

  According to the impurity analysis method for the outer peripheral surface of the semiconductor substrate 4 and the impurity analysis apparatus 1 used therefor according to the above-described embodiment, the flat portion F centered on the outer peripheral surface of the semiconductor substrate 4 using the stage 2 having the two-part structure. The X-ray 7 can be irradiated on the outer peripheral surface of the semiconductor substrate 4 under the total reflection condition. As a result, it is possible to detect fluorescent X-rays from the outer peripheral surface of the semiconductor substrate 4 which has been difficult with the conventional total reflection X-ray fluorescence analyzer, and the contamination state due to impurities on the outer peripheral surface of the semiconductor substrate 4 is relatively simple. It becomes possible to evaluate. This leads to a reduction in labor and cost required for impurity analysis on the outer peripheral surface of the semiconductor substrate 4.

  The impurity analyzer 1 of the semiconductor substrate 4 of this embodiment is typically used by being incorporated in a semiconductor device production line. At this time, the impurity analyzer (total reflection X-ray fluorescence analyzer) 1 is used for measuring a flat surface (front surface or back surface) of the semiconductor substrate 4 in addition to the stage 2 used for measuring the outer peripheral surface of the semiconductor substrate 4. A normal stage can be provided. By using a combination of a normal flat surface stage and an outer peripheral surface stage 2, it is possible to perform an impurity analysis on the flat surface and an impurity analysis on the outer peripheral surface while suppressing an increase in apparatus cost and the like. Become.

  Furthermore, by analyzing the analysis result of the flat surface of the semiconductor substrate by the total reflection X-ray fluorescence analysis and the analysis result of the outer peripheral surface, it is possible to more accurately determine the behavior of impurity contamination and the contamination source in the manufacturing process of various semiconductor devices. It becomes possible to grasp. By utilizing such analysis results and analysis results of contamination status and behavior based on the analysis results, it is possible to carry out countermeasures against contamination of the semiconductor substrate more accurately and in detail. This greatly contributes to the improvement of the yield and productivity of semiconductor devices.

  The impurity analysis method and impurity analysis apparatus for a semiconductor substrate of the present invention are not limited to the above-described embodiments, but analysis and evaluation of impurities existing on the outer peripheral surface (end face) of various semiconductor substrates, that is, various semiconductor substrates It can be applied to the evaluation of the contamination state due to impurities on the outer peripheral surface. The specific structure of the impurity analyzer of the present invention can be variously modified as long as it satisfies the basic configuration of the present invention. Furthermore, the embodiments can be expanded or modified within the scope of the technical idea of the present invention, and the expanded and modified embodiments are also included in the technical scope of the present invention.

1 is a perspective view showing an impurity analysis apparatus for a semiconductor substrate according to an embodiment of the present invention. It is a top view of 1st Embodiment to which the impurity analyzer shown in FIG. 1 is applied. It is a front view of 1st Embodiment to which the impurity analyzer shown in FIG. 1 is applied. It is a top view of 2nd Embodiment to which the impurity analyzer shown in FIG. 1 is applied. It is a front view of 2nd Embodiment to which the impurity analyzer shown in FIG. 1 is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate impurity analysis apparatus, 2 ... Stage having divided structure, 2A ... First stage, 2B ... Second stage, 3 ... Stage part, 4 ... Semiconductor substrate (semiconductor wafer), 5A, 5B ... Rotation Axis, 6 ... X-ray generation source, 7 ... Incident X-ray, 8 ... Reflected X-ray, 9 ... X-ray detector, A ... X-ray irradiation region, F ... Flat part.

Claims (5)

Sandwiching a semiconductor substrate with a stage having a divided structure, and forming a flat portion centered on the outer peripheral surface of the semiconductor substrate between the outer peripheral surface of the semiconductor substrate and the outer peripheral surface of the stage;
Irradiating the flat portion formed by the outer peripheral surface of the semiconductor substrate and the outer peripheral surface of the stage under total reflection conditions to detect fluorescent X-rays of impurities generated from the outer peripheral surface of the semiconductor substrate; ,
And a step of evaluating a contamination state of the outer peripheral surface of the semiconductor substrate due to the impurities based on the detection result of the fluorescent X-rays. The impurity analysis method for a semiconductor substrate according to claim 1,
An impurity of a semiconductor substrate, wherein a rotary stage having the same diameter as the semiconductor substrate is used as the stage, and the flat portion is irradiated with the X-rays while rotating the semiconductor substrate held by the rotary stage. Analysis method. A stage portion including a stage having a split structure capable of sandwiching a semiconductor substrate, and forming a flat portion centering on the outer peripheral surface of the semiconductor substrate between the outer peripheral surface of the semiconductor substrate and the outer peripheral surface of the stage;
An X-ray irradiation unit that irradiates the flat part formed by the outer peripheral surface of the semiconductor substrate sandwiched between the stages and the outer peripheral surface of the stage under total reflection conditions;
And a fluorescent X-ray detector for detecting fluorescent X-rays of impurities generated from the outer peripheral surface of the semiconductor substrate based on the X-ray irradiation. The impurity analysis apparatus for a semiconductor substrate according to claim 3,
The stage unit includes a rotary stage having the same diameter as the semiconductor substrate as the stage, and the X-ray irradiation unit transmits the X-rays to the flat part while rotating the semiconductor substrate sandwiched by the rotary stage. Irradiation apparatus for semiconductor substrate impurity irradiation. In the impurity analysis apparatus of the semiconductor substrate of Claim 3 or Claim 4,
The X-ray detection unit is arranged to detect fluorescent X-rays generated from the outer peripheral surface of the semiconductor substrate at the center of its sensitivity distribution.

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