Determination method for defect region of silicon single-crystal substrate

Abstract

To provide a method for I-rich determination of a defect region of a semiconductor substrate easily without destruction.SOLUTION: In a determination method for a defect region of a silicon single-crystal substrate, by which a defect region of a silicon single-crystal substrate of an orientation (100) subjected to mirror polishing using a laser scattering surface inspection device including a rotary stage, crystal defects present in a region whose crystal orientation includes <010> direction and a region whose crystal orientation includes <011> direction on a main surface of the silicon single-crystal substrate are measured by an oblique incidence mode of the surface inspection device, the number of defects or the density of defects of the crystal defects is obtained, and based on a difference between the number of defects or the density of defects of the crystal defects present in the region whose crystal orientation includes <010> direction and the number of defects or the density of defects of the crystal defects present in the region whose crystal orientation includes <011> direction, whether or not an I-rich region is included in the silicon single-crystal substrate is determined.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for determining a defective region of a silicon single crystal substrate.

Background Art

[0002] In recent years, with the sophistication of devices, high-precision control and evaluation of defective regions of semiconductor substrates have become more important. The fact that the defective region of a semiconductor substrate is different from the desired defective region causes device failures. Such defective regions include, for example, regions where the interstitial silicon is excessive (hereinafter referred to as "I-rich regions"), regions where cavities formed by aggregated vacancies are likely to be generated (hereinafter referred to as "V-rich regions"), regions where oxygen precipitates are likely to be generated (OSF regions), regions with few defects (N regions), etc., and the types of defects present vary depending on the defective region. It is known that which defective regions the substrate contains varies depending on the manufacturing conditions of the single crystal and the position of the single crystal. Therefore, at the manufacturing stage of the substrate, it is required to determine the defective region of the substrate and, if it contains undesirable crystal defects, quickly feedback to the manufacturing process of the single crystal so that such defective regions do not occur.

[0003] As a technique for determining a defective region, for example, Patent Document 1 discloses a technique for evaluating crystal defects of a semiconductor substrate by subjecting the semiconductor substrate to heat treatment, polishing it, and then inspecting it with a surface inspection apparatus.

[0004] Patent Document 2 discloses a technique for evaluating crystal defects of a semiconductor substrate by applying an impurity metal to the semiconductor substrate, then subjecting it to heat treatment, polishing it, and then inspecting it with a surface inspection apparatus.

[0005] Patent Document 3 discloses a technique for measuring the number and / or density of defects on the surface of a silicon single crystal substrate with a surface inspection apparatus and determining the defective region of the silicon single crystal substrate from the number and / or density of the defects.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] The method for visualizing defective regions due to heat treatment or metal contamination, represented by Patent Documents 1 and 2, is a destructive inspection. Therefore, generally, a part of a substrate cut out from a crystal is extracted for inspection. However, with this method, most of the defective regions of the crystal are unknown. Therefore, when undesirable defective regions exist only in a part of the crystal, there is a problem that a substrate containing undesirable crystal defects may be shipped as a product.

[0008] Also, as a result of a detailed investigation of the technology described in Patent Document 3, it was found that there is a problem that it may not be possible to make a determination for a silicon single crystal substrate containing an I-rich region.

[0009] The present invention has been made to solve the above problems, and an object thereof is to provide a method for non-destructively and simply determining the presence or absence of an I-rich region in a semiconductor substrate.

Means for Solving the Problems

[0010] The present invention is made to achieve the above object, and is a method for determining a defective region of a silicon single crystal substrate that polishes a mirror surface using a laser scattering type surface inspection apparatus equipped with a rotating stage, and determines a defective region of a silicon single crystal substrate having a plane orientation (100). In the method, crystal defects existing in regions of the main surface of the silicon single crystal substrate that include the <010> direction and the <011> direction in the crystal orientation are measured by the oblique incidence mode of the surface inspection apparatus, the number or density of the crystal defects is obtained, and based on the difference between the number or density of the crystal defects existing in the region where the crystal orientation includes the <010> direction and the number or density of the crystal defects existing in the region where the crystal orientation includes the <011> direction, it is determined whether or not the silicon single crystal substrate contains an I-rich region, thereby providing a method for determining a defective region of a silicon single crystal substrate.

[0011] According to such a method for determining a defective region of a silicon single crystal substrate, it is possible to nondestructively and simply determine whether or not a silicon single crystal substrate having a plane orientation (100) contains an I-rich region.

[0012] At this time, the region for measuring the crystal defects can be set to an arbitrary angular range within ±22.5° from the center line with the axes of the <010> direction and the <011> direction in the crystal orientation as the center lines on the main surface of the silicon single crystal substrate.

[0013] By setting the measurement region within such a range, a sufficient number of crystal defects for determining the defective region can be included in the regions including the respective directions.

[0014] At this time, the region for measuring the crystal defects can be set to a region outside a radius of 10 mm from the center of the main surface of the silicon single crystal substrate.

[0015] By setting the measurement region within such a range, it is possible to reduce the measurement error of crystal defects that may occur at the center of the main surface of the silicon single crystal substrate.

[0016] In addition, when measuring the crystal defects, the detection size of the crystal defects is also acquired, and the determination can be made based on the number of defects or the defect density of the crystal defects within a detection size range of a part of the measured crystal defects.

[0017] Thereby, even when there is a difference in the number of defects or the defect density existing in the region including the <010> direction and the region including the <011> direction of the silicon single crystal substrate only within a specific detection size range, the defect region can be determined with high accuracy.

[0018] At this time, the measurement results for a plurality of the silicon single crystal substrates having the crystal defects of the same level of size and density can be accumulated to obtain the number of defects or the defect density of the crystal defects.

[0019] Thereby, even when the number of defects per silicon single crystal substrate is small, the defect region can be determined with high accuracy.

[0020] At this time, the main surface of the silicon single crystal substrate can be re-polished and / or cleaned before the measurement.

[0021] Thereby, since the defects and particles caused by processing existing on the main surface of the silicon single crystal substrate are removed, the determination accuracy of the defect region of the silicon single crystal substrate is further improved.

Advantages of the Invention

[0022] As described above, according to the method for determining the defect region of the silicon single crystal substrate of the present invention, it is possible to nondestructively and simply determine whether the silicon single crystal substrate with the plane orientation (100) includes an I-rich region.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

[0011] direction existing in the

[0010] direction of the substrate and the incident surface of the laser of the surface inspection apparatus.

Figure 8

[0011] direction existing in the

[0011] direction of the substrate and the incident surface of the laser of the surface inspection apparatus.

Mode for Carrying Out the Invention

[0024] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0025] As described above, there has been a demand for a method for non-destructively and simply determining the presence or absence of the I-rich region in a silicon single crystal substrate.

[0026] As a result of intensive studies on the above problems, the present inventors have found that a method for determining a defective region of a silicon single crystal substrate (hereinafter also simply referred to as "substrate") having a (100) plane orientation polished by a mirror, which uses a laser scattering type surface inspection apparatus equipped with a rotating stage, measures crystal defects existing in regions including the <010> direction (hereinafter also simply referred to as the "<010> direction"; the same applies to other orientations) and regions including the <011> direction on the main surface of the silicon single crystal substrate by the oblique incidence mode of the surface inspection apparatus, obtains the number of defects or defect density of the crystal defects, and based on the difference between the number of defects or defect density of the crystal defects existing in the region including the <010> direction (hereinafter also simply referred to as "defects / number of defects / defect density in the <010> direction"; the same applies to other orientations) and the number of defects or defect density of the crystal defects existing in the region including the <011> direction, determines whether or not the silicon single crystal substrate contains an I-rich region, and has completed the present invention, finding that it is possible to non-destructively and simply determine whether or not a silicon single crystal substrate having a (100) plane orientation contains an I-rich region.

[0027] The method for determining a defective region of a silicon single crystal substrate of the present invention (hereinafter also simply referred to as "the determination method of the present invention") can be rephrased as follows: a first step of measuring defects on the main surface of a substrate having a (100) surface in the oblique incidence mode of a surface inspection apparatus equipped with a rotating stage; and a second step of deriving the number of defects or defect density in the <010> direction and the <011> direction of the substrate based on information such as defect positions obtained in the first step, and determining whether or not the substrate contains an I-rich region based on the difference between the two. FIG. 1 shows an example of the process flow of the determination method of the present invention.

[0028] [First Step] Fig. 2 shows an example of a laser scattering type surface inspection apparatus equipped with a rotary stage, which is used to implement the determination method of the present invention. As shown in Fig. 2, the surface inspection apparatus 1 may include a laser light irradiation means 11 that obliquely irradiates the surface of the substrate W to be evaluated with laser light, a detector 12 for detecting scattered light in which the irradiated laser light is scattered by defects D, etc. on the substrate surface, and a rotary R-θ stage 13 for scanning the substrate W with the laser light. As such a surface inspection apparatus 1, for example, Surfscan SP7XP manufactured by KLA Corporation can be mentioned.

[0029] First, prepare a single-crystalline silicon substrate having a surface for determining a defect region (100). The surface of the substrate is polished to a mirror surface by mirror polishing.

[0030] At this time, if there are defects caused by processing on the substrate surface, the processing-induced defects may be removed by re-polishing before measurement. Since the processing-induced defects do not depend on the defect region derived from the crystal, removing the processing-induced defects improves the determination accuracy of the I-rich region by the determination method of the present invention. Note that the polishing method for re-polishing may be a known method.

[0031] After the substrate is mirror-polished, cleaning may be performed. By performing cleaning before measurement, particles adhering to the substrate surface can be removed. Since the adhesion of particles does not depend on the defect region derived from the crystal, removing the particles further improves the determination accuracy of the I-rich region by the determination method of the present invention. Note that the cleaning may be performed by a known method.

[0032] Next, measure the substrate in the oblique incidence mode of the surface inspection apparatus 1 having a rotary R-θ stage 13, and acquire the positions of the defects on the substrate.

[0033] The surface inspection apparatus 1 irradiates the substrate with a laser and detects foreign matters such as defects by detecting scattering by foreign matters. Here, in addition to defects, particles can be detected as foreign matters. However, as described above, particles can be sufficiently reduced by cleaning.

[0034] The surface inspection apparatus 1 scans the entire measurement surface of the substrate with a laser by moving the irradiation position of the substrate or the laser in the radial direction while rotating the substrate by a rotating stage. The position information of the defect on the substrate is acquired from the irradiation position of the laser on the substrate when the defect is detected.

[0035] The substrate on the rotating stage is measured in an oblique incidence mode. At this time, when an anisotropic defect with a distinction between the major axis and the minor axis is detected, the direction of the major axis of the defect with respect to the incident light depends not only on the direction of the major axis of the defect on the substrate but also on the circumferential position of the defect on the substrate.

[0036] For example, when the installation direction of the laser light irradiation means 11 in the surface inspection apparatus 1 as shown in FIG. 2 is set to the 9 o'clock direction, consider the case of measuring a silicon single crystal substrate in the (100) plane orientation in an oblique incidence mode by the surface inspection apparatus 1 equipped with a rotating stage and detecting a defect in the 9 o'clock direction.

[0037] When detecting a defect whose major axis is along the

[0011] direction and exists in the

[0010] direction of the substrate, the defect is detected when the

[0010] direction of the substrate becomes the 9 o'clock direction of the apparatus, and the direction of the major axis at that time is the 7:30 direction of the apparatus. As shown in FIG. 7, the defect is oblique with respect to the incident direction of the laser.

[0038] On the other hand, when detecting a defect whose major axis is along the

[0011] direction and exists in the

[0011] direction of the substrate, the defect is detected when the

[0011] direction of the substrate becomes the 9 o'clock direction of the apparatus, and the direction of the major axis at that time is the 9 o'clock direction of the apparatus. As shown in FIG. 8, the defect is parallel to the incident direction of the laser.

[0039] Thus, even when the major axis of the defect is along a specific orientation of the substrate, the direction of the major axis of the defect with respect to the incident light when detected changes depending on the circumferential position of the defect on the substrate.

[0040] The surface inspection apparatus can obtain the detection size of a foreign object based on the scattered light intensity caused by the foreign object. Here, the detection size is defined from the relationship between the size and the scattered light intensity of standard particles whose sizes are known in advance by measuring the scattered light intensity caused by the standard particles. Therefore, depending on the actual shape, orientation, and composition of the foreign object, the actual size of the foreign object and the detection size do not always match.

[0041] Generally, the surface inspection apparatus determines whether the detected scattered light is a foreign object based on some threshold value. Here, the threshold value can be, for example, the actual scattered light intensity, or can be the detection lower limit size. However, in the case of a commercially available surface inspection apparatus, the threshold value can be set based on the specifications of each apparatus.

[0042] By setting the threshold value, it is possible to prevent misdetection of the scattered light caused by the roughness of the substrate surface as the scattered light caused by a foreign object. On the other hand, when the actual size is small, or when the orientation of the foreign object with respect to the incident light is not appropriate, etc., when the scattered light intensity from the foreign object is lower than the threshold value, the detection accuracy of that foreign object may decrease.

[0043] When measuring the substrate by the surface inspection apparatus 1, not only the position information of the defect on the substrate but also the detection size of the defect may be obtained. By obtaining the detection size, the detection size can be limited to a specific range when deriving the number of defects or the defect density, and the defect region can be determined with higher accuracy.

[0044] [Second step] Next, based on the position information of the defect on the substrate obtained in the first step, it is classified whether it exists in a region including the <010> direction of the crystal orientation of the substrate, in a region including the <011> direction, or in other regions.

[0045] Here, the <010> direction of the substrate represents the entire four equivalent orientations of

[0010] ,

[0001] , [0-10], [00-1] with respect to the center of the substrate, and the <011> direction represents the entire four equivalent orientations of

[0011] , [0-11], [0-1-1], [01-1] with respect to the center of the substrate.

[0046] Instead of the <010> direction and <011> direction of the substrate, one of the equivalent orientations (for example,

[0010] and

[0011] ) can be used to represent each respectively.

[0047] The regions including the <010> direction and the <011> direction of the main surface of the substrate for measuring defects can be not only on the axes corresponding exactly to the <010> direction and <011> direction, but also within the range of any angle within ±22.5° from the center line with the axis as the reference center line. By taking such a range, a sufficient number of defects for determining the defect region can be included in the regions including each direction.

[0048] Here, when both the region including the <010> direction of the substrate and the region including the <011> direction of the substrate are within the range of ±22.5° from the center line respectively, excluding the defects exactly at the center of the substrate surface, all defects are included in the region including the <010> direction of the substrate or the region including the <011> direction of the substrate.

[0049] The region of the substrate for measuring defects may be a specific radial range. For example, such a radial range can be outside a radius of 10 mm from the center of the main surface of the substrate, but it is not particularly limited. Since the distance between the <010> direction and <011> direction is close near the substrate center, due to a slight deviation of the defect position on the substrate measured by the surface inspection device, an error may occur where the defect is counted in a region including a direction different from the actual one. However, by setting the measurement region within such a range, the error can be reduced.

[0050] Also, the specific radial range can be a range excluding the outermost peripheral region of the substrate. Since the outer periphery of the substrate is susceptible to shape changes due to chamfering and the influence of particles that could not be completely removed by cleaning, excluding the outermost peripheral region of the substrate can further reduce the determination error. Such a radial range can be, for example, inside 2 mm from the outer periphery, but it is not particularly limited.

[0051] Subsequently, compare the number of defects classified as existing in the region including the <010> direction of the substrate with the number of defects classified as existing in the region including the <011> direction of the substrate.

[0052] In the determination method of the present invention, based on the difference in the number of defects in the <010> direction and the <011> direction of the substrate, it is possible to determine whether the substrate contains an I-rich region.

[0053] As a result of the investigation, on the surface of a substrate with a (100) plane orientation of a silicon single crystal containing an I-rich region, there are multiple types of anisotropic defects with a high aspect ratio where the ratio of the length of the major axis to the length of the minor axis exceeds 1 to 20, and it was found that the major axis is along a specific orientation for each type of defect (hereinafter, the anisotropic defects with the high aspect ratio may be collectively referred to as "I-rich linear defects"). Furthermore, it was found that for at least some types of I-rich linear defects, there is a difference in the detection rate when measured in the oblique incidence mode of a surface inspection apparatus having a rotation stage depending on whether they are present in the <010> direction or the <011> direction of the substrate.

[0054] Even when the major axis of the defect is along a specific orientation of the substrate, the direction of the major axis of the defect with respect to the incident light at the time of detection changes depending on the circumferential position of the defect on the substrate. Due to this, it is considered that for some types of I-rich linear defects, the scattered light intensity changes and the detection rate changes depending on whether they are present in the <010> direction or the <011> direction of the substrate.

[0055] On the other hand, in the defect region other than the I-rich region, no crystal defects with an aspect ratio exceeding 1 to 20 were detected. Therefore, it was confirmed that there is no difference in the number of defects and the defect density in the <010> direction and the <011> direction of the substrate. Thus, by comparing the number of defects or the defect density in the <010> direction and the <011> direction of the substrate, if there is a difference in the number of defects or the defect density, it can be determined that the substrate contains an I-rich region.

[0056] Instead of comparing the total number of defects classified in each direction, the detection size of the defects may also be obtained in the first step, and the determination of the defective region may be made based on the number of defects within a detection size range of a part of the measured defects. By limiting the detection size, even when there is a difference in the number of defects in the <010> direction and the <011> direction of the substrate only within a specific detection size range, it is possible to accurately determine whether the I-rich region is included.

[0057] The detection size of the specific range is such that, for a substrate actually including an I-rich region, the number of defects within a certain range of detection sizes existing in the <010> direction is compared with the number of defects within the same range of detection sizes existing in the <011> direction, and it can be any range of detection sizes for which a difference is recognized. The range of detection sizes thus determined can also be applied to another substrate for which the levels outside the defective region can be regarded as generally the same.

[0058] As a method for comparing the number of defects, for example, a schematic diagram plotting the defect positions on the substrate as shown in FIG. 3 is prepared, and the number of defects in the <010> direction of the substrate is compared with the number of defects in the <011> direction. In this case, if there is a significant difference between the two, it can be visually compared. In the case of FIG. 3, it is visually obvious that the number of defects in the <011> direction is larger than the number of defects in the <010> direction, and a difference is recognized. Therefore, it is determined that the substrate includes an I-rich region.

[0059] Also, instead of the above comparison method, a specific threshold value related to the difference in the number of defects for determining that the substrate includes an I-rich region can be defined. It is also possible to determine based on the presence or absence of a statistically significant difference. Further, for a substrate actually including an I-rich region and a substrate not including an I-rich region, with reference to the ratio b / a of the number of defects b in the <011> direction to the number of defects a in the <010> direction, a threshold value (both when b / a is greater than 1 and when it is less than 1) can be defined.

[0060] For example, the threshold value when b / a is greater than 1 can be set as b / a ≧ 1.1, but it is not particularly limited and may be appropriately set according to the purpose of determination and the total number of defects of the substrate.

[0061] For example, when it is desired to determine that a substrate contains an I-rich region without missing such a substrate, it is preferable to make the threshold value closer to 1 (for example, b / a ≥ 1.05). Thereby, even for a substrate in which the ratio of other regions to the I-rich region is large, it is possible to determine with higher accuracy that the substrate contains an I-rich region.

[0062] Conversely, for a substrate that does not contain an I-rich region, when it is desired to reduce the possibility of misjudging that it contains an I-rich region, which may occur due to variations in the number of defects in each direction, it is preferable to set a threshold value greater than 1.1 (for example, b / a ≥ 1.2). In particular, when the number of defects is small, since it is more susceptible to the influence of variations, it is more preferable to set a threshold value greater than 1.1.

[0063] Similarly, as the threshold value when b / a is less than 1, b / a ≤ 0.9 can be used, but it is not particularly limited and may be appropriately set according to the purpose of the determination and the total number of defects of the substrate.

[0064] For example, when it is desired to determine that a substrate contains an I-rich region without missing such a substrate, it is preferable to make the threshold value closer to 1 (for example, b / a ≤ 0.95). Thereby, even for a substrate in which the ratio of other regions to the I-rich region is large, it is possible to determine with higher accuracy that the substrate contains an I-rich region.

[0065] Conversely, for a substrate that does not contain an I-rich region, when it is desired to reduce the possibility of misjudging that it contains an I-rich region, which may occur due to variations in the number of defects in each direction, it is preferable to set a threshold value less than 0.9 (for example, b / a ≤ 0.8). In particular, when the number of defects is small, since it is more susceptible to the influence of variations, it is more preferable to set a threshold value less than 0.9.

[0066] When a difference in defect density is observed between the <010> direction and the <011> direction of the substrate instead of the number of defects, it can also be determined that the substrate includes an I-rich region. Thereby, even when the angular ranges of the region including the <010> direction and the region including the <011> direction are different, the defective region can be accurately determined.

[0067] At this time, as a specific threshold related to the difference in defect density for determining that the substrate includes an I-rich region, for a substrate actually including an I-rich region and a substrate not including an I-rich region, with respect to the defect density a' in the <010> direction, the ratio b' / a' of the defect density b' in the <011> direction is referred to, and thresholds (both when b' / a' is greater than 1 and when b' / a' is less than 1) can be determined. For example, the same value as the threshold obtained from the above number of defects can be used as the threshold related to the difference in defect density.

[0068] Further, measurement results for a plurality of substrates having defects of the same level of size and density may be accumulated to obtain the number of defects or the defect density. By making a determination based on the measurement results of a plurality of substrates at the same level, even when the number of defects per substrate is small, it is possible to accurately determine the defective region.

Example

[0069] Hereinafter, the present invention will be specifically described with reference to examples, which do not limit the present invention.

[0070] (Example 1) First, two polished silicon single crystal substrates with a diameter of 300 mm and a plane orientation of (100) manufactured by the Czochralski method under different conditions were prepared and designated as substrate A and substrate B, respectively.

[0071] Next, foreign substances present on the main surfaces of substrates A and B were measured using a surface inspection apparatus (SP7XP, Oblique mode (oblique incidence), 11 nm up) equipped with a rotation stage.

[0072] Subsequently, for substrates A and B, the number of defects present in the region including the <010> direction of the substrate and the region including the <011> direction of the substrate was examined.

[0073] Here, the region including the <010> direction of the substrate was defined as the entire four equivalent azimuths of

[0010] ,

[0001] , [0-10], [00-1] with respect to the center of the substrate, and the range of ±22.5° therefrom. Similarly, the region including the <011> direction of the substrate was defined as the entire four equivalent azimuths of

[0011] , [0-11], [0-1-1], [01-1] with respect to the center of the substrate, and the range of ±22.5° therefrom.

[0074] At this time, the thresholds related to the difference in the number of defects or defect density present in the region including the <010> direction of the substrate and the region including the <011> direction of the substrate for determining that the substrate includes an I-rich region were set to 0.9 and 1.1. When the value of the ratio of the number of defects or defect density present in the region including the <011> direction of the substrate to the number of defects or defect density present in the region including the <010> direction of the substrate was less than 0.9 or greater than 1.1, it was determined that the substrate included an I-rich region.

[0075] As a result, for substrate A, the number of defects present in the region including the <010> direction of the substrate was 707, while the number of defects present in the region including the <011> direction of the substrate was 379. Therefore, since the ratio of the number of defects in the <011> direction to the number of defects in the <010> direction of the substrate was 379 / 707 ≒ 0.536 < 0.9, substrate A was determined to include an I-rich region.

[0076] For substrate B, the number of defects present in the region including the <010> direction of the substrate was 23029, while the number of defects present in the region including the <011> direction of the substrate was 23575. Therefore, since the ratio of the number of defects present in the region including the <011> direction of the substrate to the number of defects present in the region including the <010> direction of the substrate was 23575 / 23029 ≒ 1.024 and 0.9 < 1.024 < 1.1, substrate B was determined not to include an I-rich region.

[0077] As a result of determining the defective regions for each adjacent substrate by a known manifestation etching method, it was confirmed that substrate A contained an I-rich region, substrate B was a V-rich region over the entire surface and did not contain an I-rich region, and that the defective regions had been correctly evaluated.

[0078] From the above results, it was shown that the determination of the I-rich region by the method for determining the defective region of the single-crystalline silicon substrate of the present invention is effective.

[0079] (Example 2) One mirror-polished single-crystalline silicon substrate with a diameter of 300 mm, manufactured using the Czochralski method, was washed and designated as substrate C.

[0080] Next, the defects present on the main surfaces of substrate C and substrate B of Example 1 were measured using a surface inspection apparatus (SP7XP, Oblique mode (low-angle incidence), 11 nm up) equipped with a rotating stage. The defect distribution of substrate C is shown in FIG. 5, and the defect distribution of substrate B is shown in FIG. 6.

[0081] Subsequently, for substrates B and C, for defects with a detection size of 13 nm or more, a schematic diagram plotting the defect positions was prepared, and the number of defects present in the region including the <010> direction of the substrate and the number of defects present in the region including the <011> direction of the substrate were visually compared.

[0082] Here, the region including the <010> direction of the substrate was defined as the entire four equivalent azimuths of

[0010] ,

[0001] , [0-10], [00-1] and the range of ±10° therefrom with respect to the center of the substrate. Similarly, the region including the <011> direction of the substrate was defined as the entire four equivalent azimuths of

[0011] , [0-11], [0-1-1], [01-1] and the range of ±10° therefrom with respect to the center of the substrate.

[0083] In addition, when determining that the substrate includes an I-rich region, the threshold values related to the difference in the number or density of defects existing in the region including the <010> direction and the region including the <011> direction of the substrate are set to 0.9 and 1.1. When the value of the ratio of the number or density of defects existing in the region including the <011> direction of the substrate to the number or density of defects existing in the region including the <010> direction of the substrate is less than 0.9 or greater than 1.1, it is determined that the substrate includes an I-rich region.

[0084] The distribution of defects with a detection size of 13 nm or more on substrate C is shown in FIG. 3. From FIG. 3, it was visually clearly observed that the number of defects existing in the region including the <011> direction was significantly more than the number of defects existing in the region including the <010> direction, and a difference was recognized. Therefore, it was determined that substrate C includes an I-rich region.

[0085] When obtaining the defect density existing in the region including each direction, the defect density existing in the region including the <010> direction of the substrate is 0.140 pieces / cm 2 and the defect density existing in the region including the <011> direction of the substrate is 0.879 pieces / cm 2 Since the ratio of the defect density existing in the region including the <011> direction to the defect density existing in the region including the <010> direction of the substrate is 0.879 / 0.140 = 6.279 > 1.1, it was determined that substrate C includes an I-rich region.

[0086] Actually, as a result of determining the defect region of the adjacent substrate of substrate C by a known revelation etching method, it was confirmed that substrate C is an I-rich region over the entire surface.

[0087] The distribution of defects with a detection size of 13 nm or more on substrate B is shown in FIG. 4. From FIG. 4, no visually obvious difference was recognized between the number of defects existing in the region including the <010> direction and the number of defects existing in the region including the <011> direction.

[0088] When obtaining the defect density existing in the region including each direction, the defect density existing in the region including the <010> direction of the substrate is 45.35 pieces / cm 2, the defect density in the region including the <011> direction is 46.75 defects / cm 2 and the ratio of the defect density in the region including the <011> direction to the defect density in the region including the <010> direction of the substrate was 46.75 / 45.35 = 1.031, and since 0.9 < 1.031 < 1.1, substrate B was determined not to contain an I-rich region. In addition, in Example 1, it was confirmed that substrate B was a full-surface V-rich region and did not contain an I-rich region by a known visualization etching method. [[ID=*]]

[0089] From the above results, it was also possible to determine the presence or absence of an I-rich region based on the difference in defect density between the region including the <010> direction and the region including the <011> direction of the substrate, and it was shown that the determination of the I-rich region by the method for determining the defect region of the silicon single crystal substrate of the present invention was effective.

[0090] Also, for substrate C and substrate B, for all the detected defects, the ratio of the defect density in the region including the <011> direction to the defect density in the region including the <010> direction of the substrate was determined. As a result, the defect density ratio was 0.897 for substrate C and 1.018 for substrate B, and it was determined that substrate C contained an I-rich region and substrate B did not contain an I-rich region. Also, when the detection size was limited, the defect density ratio of substrate C was significantly larger than the threshold value, and it was shown that limiting the defect size was effective for the determination of the I-rich region. Although the magnitude relationship of the defect density ratios of substrate C and substrate B is reversed depending on whether the detection size is limited or not, this is because there are two types of defects with a large aspect ratio in substrate C, and each has a different average size and major axis direction.

[0091] (Comparative Example) The defects present on the main surfaces of substrate C and substrate B used in Example 2 were measured with a surface inspection apparatus (SP7XP, Oblique mode, 11 nm Up), and the defect positions were plotted from the obtained position information. The defect distribution of substrate C is shown in FIG. 5, and the defect distribution of substrate B is shown in FIG. 6.

[0092] Regarding substrates B and C, an attempt was made to determine the defective regions based on the technique described in Patent Document 3. Although the total number of defects was different, since defects were present over the entire surface of the substrates, both were determined to be entirely V-rich regions. Substrate B, which is entirely V-rich, was accurately determined, but for substrate C, which includes an I-rich region, a determination result different from the actual situation was obtained.

[0093] As described above, according to the embodiments of the present invention, it was possible to accurately determine whether a silicon single crystal substrate includes an I-rich region.

[0094] This specification includes the following aspects. [1]: A method for determining a defective region of a silicon single crystal substrate, which determines a defective region of a mirror-polished (100)-oriented silicon single crystal substrate using a laser scattering type surface inspection apparatus equipped with a rotation stage, measures crystal defects present in regions of the main surface of the silicon single crystal substrate where the crystal orientation includes the <010> direction and the <011> direction by an oblique incidence mode of the surface inspection apparatus, obtains the number of defects or defect density of the crystal defects, and determines whether the silicon single crystal substrate includes an I-rich region based on the difference between the number of defects or defect density of the crystal defects present in the region where the crystal orientation includes the <010> direction and the number of defects or defect density of the crystal defects present in the region where the crystal orientation includes the <011> direction. [2]: The method for determining a defective region of a silicon single crystal substrate according to [1] above, wherein the region for measuring the crystal defects is an arbitrary angular range within ±22.5° from a center line along axes in the <010> direction and the <011> direction on the main surface of the silicon single crystal substrate. [3]: The method for determining a defective region of a silicon single crystal substrate according to [1] or [2] above, wherein the region for measuring the crystal defects is a region outside a radius of 10 mm from the center of the main surface of the silicon single crystal substrate. [4]: When measuring the crystal defects, the detection size of the crystal defects is also obtained, and the determination is made based on the number of defects or the defect density of the crystal defects within a partial detection size range among the measured crystal defects. The method for determining a defective region of a silicon single crystal substrate according to [1], [2], or [3] above. [5]: The method for determining a defective region of a silicon single crystal substrate according to [1], [2], [3], or [4] above, including accumulating the measurement results for a plurality of the silicon single crystal substrates having the crystal defects of the same level of size and density to obtain the number of defects or the defect density of the crystal defects. [6]: The method for determining a defective region of a silicon single crystal substrate according to [1], [2], [3], [4], or [5] above, including performing repolishing and / or cleaning of the main surface of the silicon single crystal substrate before the measurement.

[0095] Note that the present invention is not limited to the above embodiments. The above embodiments are examples, and any configuration that has a substantially identical configuration to the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Explanation of Reference Numerals

[0096] 1... Surface inspection device, 11... Laser light irradiation means, 12... Detector, 13... R-θ stage, D... Defect, W... Substrate.

Claims

1. A method for determining a defective region of a silicon single crystal substrate, which determines a defective region of a silicon single crystal substrate having a (100) plane orientation polished by a mirror finish using a laser scattering type surface inspection apparatus provided with a rotating stage, wherein crystal defects existing in regions of the main surface of the silicon single crystal substrate that include the <010> direction and the <011> direction of the crystal orientation are measured by an oblique incidence mode of the surface inspection apparatus, and the number or density of the crystal defects is obtained, and based on the difference between the number or density of the crystal defects existing in the region where the crystal orientation includes the <010> direction and the number or density of the crystal defects existing in the region where the crystal orientation includes the <011> direction, it is determined whether the silicon single crystal substrate includes an I-rich region. A method for determining a defective region of a silicon single crystal substrate, characterized by this.

2. The method for determining a defective region of a silicon single crystal substrate according to claim 1, wherein the region for measuring the crystal defects is an arbitrary angular range within ±22.5° from a center line with axes in the <010> direction and the <011> direction of the crystal orientation as the center line on the main surface of the silicon single crystal substrate.

3. The method for determining a defective region of a silicon single crystal substrate according to claim 1, wherein the region for measuring the crystal defects is a region outside a radius of 10 mm from the center of the main surface of the silicon single crystal substrate.

4. The method for determining a defective region of a silicon single crystal substrate according to claim 1, wherein when measuring the crystal defects, the detection size of the crystal defects is also acquired, and the determination is made based on the number or density of the crystal defects within a detection size range of a part of the measured crystal defects.

5. The method for determining a defective region of a silicon single crystal substrate according to claim 1, wherein the measurement results for a plurality of silicon single crystal substrates having the same level of size and density of the crystal defects are accumulated to obtain the number or density of the crystal defects.

6. The method for determining a defective region of a silicon single crystal substrate according to any one of claims 1 to 5, characterized in that the main surface of the silicon single crystal substrate is re-polished and / or washed before the measurement.

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