Method for determining defect regions in a silicon single-crystal substrate
Patent Information
- Application Number
- KR1020267022382
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-01-18
- Filing Date
- 2024-12-26
- Publication Date
- 2026-09-21
Smart Images
Figure PCT00001_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to a method for determining a defect region of a silicon single-crystal substrate. Background Technology
[0002] Recently, with the advancement of devices, the high-precision control and evaluation of defect regions in semiconductor substrates have become increasingly important. If the defect regions of a semiconductor substrate differ from the desired defect regions, it becomes a cause of device failure. Such defect regions include, for example, regions with an excess of interstitial silicon (hereinafter referred to as "I-rich regions"), regions prone to the formation of cavities where vacancies are aggregated (hereinafter referred to as "V-rich regions"), regions prone to the formation of oxygen precipitates (OSF regions), and regions with few defects (N regions); the types of defects present vary depending on the defect region. It is known that the specific defect regions a substrate contains vary depending on the manufacturing conditions of the single crystal and the location of the single crystal. Therefore, during the substrate manufacturing stage, it is required to determine the defect regions of the substrate and, if undesirable crystal defects are present, to promptly feed back to the single crystal manufacturing process to prevent such defect regions from occurring.
[0003] As a technique for determining a defect area, for example, Patent Document 1 discloses a technique for evaluating crystal defects of a semiconductor substrate by performing heat treatment on the semiconductor substrate and polishing it, and then inspecting the polished substrate with a surface inspection device.
[0004] Patent Document 2 discloses a technology for evaluating crystal defects of a semiconductor substrate by applying an impurity metal to the semiconductor substrate, performing heat treatment, and then polishing it and inspecting it with a surface inspection device.
[0005] Patent Document 3 discloses a technology for measuring the number of defects and / or defect density on the surface of a silicon single-crystal substrate by a surface inspection device, and determining the defect region of the silicon single-crystal substrate from the number of defects and / or defect density. Prior art literature
[0006] Japanese Patent Publication No. 2017-220587 Japanese Patent Publication No. 2021-172573 Japanese Patent Publication No. 2017-092400 The problem to be solved
[0007] The method for manifesting defect regions caused by heat treatment or metal contamination, represented by Patent Documents 1 and 2, is a destructive inspection. Therefore, generally, a portion of the substrate cut from the crystal is extracted and inspected. However, in this method, most of the defect regions of the crystal are unclear. Consequently, there was a problem that if undesirable defect regions exist only in a part of the crystal, there is a risk that a substrate containing undesirable crystal defects will be shipped as a product.
[0008] In addition, as a result of a detailed investigation into the technology described in Patent Document 3, it was found that there is a problem in that it is not possible to determine the case for a silicon single-crystal substrate containing an I-rich region.
[0009] The present invention is made to solve the above problem and aims to provide a method for non-destructively and conveniently determining the presence or absence of an I-rich region in a semiconductor substrate. means of solving the problem
[0010] The present invention, made to achieve the above objective, is a method for determining a defect region of a silicon single crystal substrate with a mirror-polished surface orientation (100) using a laser scattering type surface inspection device equipped with a rotating stage, wherein the crystal orientation of the main surface of the silicon single crystal substrate is <010> Area including direction and <011> Crystal defects existing in a region including a direction are measured by the oblique incidence mode of the surface inspection device to obtain the number of defects or defect density of the crystal defects, and the crystal orientation <010> The number of defects or defect density of the crystal defects existing in a region including the direction, and the crystal orientation <011> A method for determining a defect region of a silicon single crystal substrate is provided, characterized by determining whether the silicon single crystal substrate contains an I-rich region based on the difference between the number of defects or the defect density of the crystal defects existing in a region including a direction.
[0011] According to the method for determining defect regions of such silicon single crystal substrates, it is possible to easily and non-destructively determine whether a silicon single crystal substrate of plane orientation (100) includes an I-rich region.
[0012] At this time, the region for measuring the crystal defect is the crystal orientation of the main surface of the silicon single crystal substrate. <010> Direction and <011> With the axis of direction as the centerline, it can be set to an arbitrary angle range within ±22.5° from this centerline.
[0013] By making the measurement area such a range, a sufficient number of determination defects can be included in the area including each direction when determining the defect area.
[0014] At this time, the area for measuring the crystal defect may be an area extending more than 10 mm outward from the center of the main surface of the silicon single crystal substrate.
[0015] By making the measurement area within this range, the measurement error of crystal defects that may occur at the center of the main surface of a silicon single-crystal substrate can be reduced.
[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 defect density of some of the crystal defects within the detection size range of the measured crystal defects.
[0017] Accordingly, silicon single-crystal substrates only within a specific detection size range <010> Area including direction and <011> Even if a difference is recognized in the number of defects or defect density existing in an area including a direction, the defect area can be determined with high precision.
[0018] At this time, the number of defects or the defect density of the crystal defects can be obtained by accumulating the measurement results for multiple silicon single-crystal substrates having the same level of size and density of the crystal defects.
[0019] Accordingly, even when the number of defects per silicon single crystal substrate is small, the defect area can be determined with high precision.
[0020] At this time, the main surface of the silicon single-crystal substrate may be re-polished and / or cleaned before the above measurement.
[0021] Accordingly, since processing-induced defects and particles present on the main surface of the silicon single-crystal substrate are removed, the precision of determining defect areas on the silicon single-crystal substrate is further improved. Effects of the invention
[0022] As described above, according to the method for determining a defect region of a silicon single crystal substrate of the present invention, it is possible to determine whether a silicon single crystal substrate of plane orientation (100) includes an I-rich region in a non-destructive and convenient manner. Brief explanation of the drawing
[0023] FIG. 1 is a flowchart illustrating an example of an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of a surface inspection device for carrying out an embodiment of the present invention. FIG. 3 is a schematic diagram showing the distribution of defects with a detection size of 13 nm or larger on substrate C containing an I-rich region measured in Example 2. Figure 4 is a schematic diagram showing the distribution of defects with a detection size of 13 nm or larger on substrate B, which does not include an I-rich region measured in Example 2. Figure 5 is a schematic diagram showing the defect distribution of substrate C including an I-rich region. Figure 6 is a schematic diagram showing the defect distribution of substrate B that does not include an I-rich region. FIG. 7 is a schematic diagram showing an example of the relationship between a defect in the
[0010] direction of a substrate, where the major axis follows the
[0011] direction, and the incident plane of a laser of a surface inspection device. FIG. 8 is a schematic diagram showing an example of the relationship between a defect with a long axis along the
[0011] direction existing in the
[0011] direction of a substrate and the incident plane of a laser of a surface inspection device. Specific details for implementing the invention
[0024] The present invention will be described in detail below, but the invention is not limited to these.
[0025] As described above, there was a need for a method to non-destructively and conveniently determine the presence or absence of I-rich regions in a silicon single-crystal substrate.
[0026] As a result of repeated careful consideration of the above problem, the inventors have determined a defect region of a silicon single crystal substrate (hereinafter simply referred to as "substrate") by using a laser scattering type surface inspection device equipped with a rotating stage to determine the defect region of a silicon single crystal substrate with a mirror-polished surface orientation (100), wherein the crystal orientation of the main surface of the silicon single crystal substrate <010> Direction (hereinafter simply " <010> It is also called "direction." The same shall apply to other directions) and the area including <011> Crystal defects existing in a region including a direction are measured by the four-directional incidence mode of the surface inspection device to obtain the number of defects or defect density of the crystal defects, and the crystal orientation <010> The number of defects or defect density of the above-mentioned crystal defects existing in a region including the direction (hereinafter simply " <010> It is also referred to as "defects / number of defects / defect density of the direction." The same shall be applied to other orientations) and the above crystal orientation <011> The present invention was completed by discovering that the determination of whether the silicon single crystal substrate has an I-rich region can be made non-destructively and easily by making a determination based on the difference between the number of defects or the defect density of the crystal defects existing in the region including the direction.
[0027] The method for determining a defect region of a silicon single crystal substrate of the present invention (hereinafter also simply referred to as the “determination method of the present invention”) comprises, in other words, a first process of measuring a defect on the main surface of a substrate having a (100) surface in a four-directional incidence mode of a surface inspection device equipped with a rotating stage, and based on information such as the defect location obtained in the first process, the substrate <010> Direction and <011> A determination method comprising a second process of deriving the number of defects or defect density in a direction and determining whether an I-rich region is included in the substrate based on the difference between the two. Figure 1 shows an example of the process flow of the determination method of the present invention.
[0028] [Process 1]
[0029] FIG. 2 illustrates an example of a laser scattering type surface inspection device equipped with a rotary stage used to implement the determination method of the present invention. As shown in FIG. 2, the surface inspection device (1) may be equipped with a laser light irradiation means (11) for irradiating laser light in all directions onto the surface of a substrate (W) to be evaluated, a detector (12) for detecting scattered light that is scattered by defects (D) on the surface of the substrate, etc., of the irradiated laser light, and a rotary R-θ stage (13) for scanning the substrate (W) with laser light. As such a surface inspection device (1), for example, the KLA Surfscan SP7XP may be cited.
[0030] First, a silicon single-crystal substrate having a (100) surface for determining defect regions is prepared. The surface of the substrate is made mirror-like by mirror polishing.
[0031] In this case, if processing-induced defects exist on the substrate surface, the processing-induced defects may be removed by regrinding prior to measurement. Since processing-induced defects do not depend on crystal-derived defect regions, removing processing-induced defects improves the determination accuracy of I-rich regions by the determination method of the present invention. Meanwhile, the regrinding method can be performed using known methods.
[0032] After mirror polishing the substrate, cleaning may be performed. By performing cleaning before measurement, particles attached to the surface of the substrate can be removed. Since the attachment of particles does not depend on crystal-derived defect regions, removing the particles further improves the accuracy of determining I-rich regions by the determination method of the present invention. Meanwhile, cleaning can be performed by known methods.
[0033] Next, the substrate is measured in a four-directional incidence mode of the surface inspection device (1) having a rotary R-θ stage (13), and the location of the defect on the substrate is obtained.
[0034] The surface inspection device (1) irradiates a laser onto a substrate and detects foreign substances, such as defects, by detecting scattering caused by foreign substances. Here, in addition to defects, particles may be detected as foreign substances. However, as described above, particles can be sufficiently reduced by cleaning.
[0035] The surface inspection device (1) rotates the substrate by a rotating stage and then moves the irradiation position of the substrate or the laser in the radial direction to irradiate the entire measurement surface of the substrate. Location information of the defect on the substrate is obtained from the irradiation position of the laser on the substrate when a defect is detected.
[0036] The substrate on the rotating stage is measured in an all-directional incidence mode. In this case, when an anisotropic defect with a distinction between a major and minor axis is detected, the direction of the major axis of the defect relative 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.
[0037] For example, consider a case where, in a surface inspection device (1) as shown in FIG. 2, the installation direction of the laser light irradiation means (11) is set to the 9 o'clock direction, and a silicon single crystal substrate of the surface orientation (100) is measured in a four-directional incidence mode by a surface inspection device (1) equipped with a rotating stage, and a defect in the 9 o'clock direction is detected.
[0038] When detecting a defect that exists in the
[0010] direction of the substrate and whose major axis follows the
[0011] direction, the defect is detected when the
[0010] direction of the substrate becomes the 9 o'clock direction of the device, and the direction of the major axis at that time is the 7:30 direction of the device, and as shown in FIG. 7, the defect becomes oblique with respect to the incident direction of the laser.
[0039] Meanwhile, when detecting a defect in the
[0011] direction of the substrate, where the major axis follows the
[0011] direction, the defect is detected when the
[0011] direction of the substrate becomes the 9 o'clock direction of the device, and at that time the direction of the major axis is the 9 o'clock direction of the device, and as shown in FIG. 8, the defect becomes parallel to the incident direction of the laser.
[0040] As such, even when the major axis of a defect follows a specific orientation of the substrate, the direction of the major axis of the defect relative to the incident light at the time of detection changes depending on the perimeter position of the defect on the substrate.
[0041] A surface inspection device can determine the detection size of a foreign object based on the intensity of scattered light caused by the foreign object. Here, the detection size is determined by measuring the intensity of scattered light caused by a standard particle of a known size and the relationship between the size of the standard particle and the intensity of the scattered light. Therefore, depending on the shape, orientation, and composition of the actual foreign object, the actual size of the foreign object and the detected size may not necessarily coincide.
[0042] Generally, a surface inspection device determines whether the detected scattered light is a foreign substance based on a threshold value. Here, the threshold value can be, for example, the actual scattered light intensity or the detection lower limit size; however, for commercially available surface inspection devices, the threshold value can be set based on the specifications of each device.
[0043] By setting a threshold value, it is possible to prevent the misdetection of scattered light caused by substrate surface roughness as scattered light caused by foreign matter. On the other hand, if the intensity of scattered light from foreign matter is lower than the threshold value—such as when the actual size is small or the orientation of the foreign matter relative to the incident light is inappropriate—the detection accuracy of the foreign matter may decrease.
[0044] When measuring a substrate by a surface inspection device (1), not only the location of defects on the substrate but also the detection size of the defects can be obtained. By obtaining the detection size, the detection size can be limited to a specific range when deriving the number of defects or defect density, and the defect area can be determined with higher precision.
[0045] [Process 2]
[0046] Next, based on the location information of defects on the substrate obtained in the first process, the crystal orientation of the substrate is <010> Whether it exists in an area that includes direction, <011> Classifies whether it exists in an area including the direction or in an area other than that.
[0047] Here, of the substrate <010> Direction refers to the total of four equivalent orientations
[0010] ,
[0001] , [0-10], and [00-1] with respect to the center of the substrate, and <011> Directions represent the four equivalent orientations
[0011] , [0-11], [0-1-1], and [01-1] with respect to the center of the substrate.
[0048] substrate <010> Direction and substrate <011> Instead of the above, one of the equivalent directions (e.g.,
[0010] and
[0011] ) may be used as a representative direction.
[0049] of the main surface of a substrate, measuring defects <010> Area including direction and <011> The area including the direction is, strictly speaking <010> Direction and <011> In addition to the axis corresponding to the direction, the range can be any angle within ±22.5° from the centerline using the said axis as the reference centerline. By adopting such a range, a sufficient number of defects can be included in the area encompassing each direction when determining the defect area.
[0050] Here, of the substrate <010> region including direction and substrate <011> In the case where both sides of the region including the direction are each set within a range of ±22.5° from the centerline, strictly excluding defects located at the center of the substrate surface, all defects are of the substrate <010> Area including direction or <011> It is included in the area that includes the direction.
[0051] The area of the substrate for measuring defects may be a range in a specific radial direction. For example, such a radial range may be outward from the center of the main surface of the substrate by a radius of 10 mm or more, but is not particularly limited. The area near the center of the substrate is <010> Direction and <011> Because the distance in the direction is short, an error may occur in which the defect is calculated in an area that includes a direction different from the actual one due to a slight misalignment of the defect location on the substrate measured by the surface inspection device, but the error can be reduced by making the measurement area such a range.
[0052] In addition, the above specific diameter range may be a range excluding the outermost region of the substrate. Since the outer edge of the substrate is susceptible to changes in shape due to chamfering or particles that were not completely removed by cleaning, excluding the outermost region of the substrate can further reduce judgment errors. As for such a diameter range, for example, it may be inward from the outer edge by 2 mm, but is not particularly limited.
[0053] Continuing, the substrate's <010> The number of defects classified as existing in the region including the direction, and the substrate's <011> Compare the number of defects classified as existing in the area including the direction.
[0054] In the determination method of the present invention, the substrate <010> Direction and <011> Based on the difference in the number of defects in each direction, it is possible to determine whether the substrate contains an I-rich region.
[0055] As a result of the investigation, it was found that on the surface of the substrate of the plane orientation (100) of a silicon single crystal containing an I-rich region, there are multiple types of high-aspect-ratio anisotropic defects in which the length of the major axis to the length of the minor axis exceeds 1 to 20, and that the major axis follows a specific orientation for each type of defect (hereinafter, the above high-aspect-ratio anisotropic defects are collectively referred to as "I-rich linear defects"). Furthermore, at least one type of I-rich linear defect is of the substrate <010> Direction and <011> It was found that depending on which direction it is located, there is a difference in the detection rate when measured in the four-directional incidence mode of a surface inspection device having a rotating stage.
[0056] Even when the major axis of a defect follows a specific orientation of the substrate, the direction of the defect's major axis relative to the incident light at the time of detection changes depending on the perimeter position of the defect on the substrate. Due to this, certain types of I-rich linear defects, of the substrate <010> Direction and <011> It is thought that depending on which direction it exists, the scattered light intensity changes and the detection rate changes.
[0057] Meanwhile, in defect regions other than the I-rich region, crystal defects with an aspect ratio exceeding 1 to 20 are not detected, and therefore the substrate's <010> Direction and <011> It was acknowledged that there was no difference in the number of defects and defect density in the direction. Therefore, the substrate <010> Direction and <011> By comparing the number of defects or defect density in a direction, if there is a difference in the number of defects or defect density, it can be determined that the substrate contains an I-rich region.
[0058] Instead of comparing the number of all defects classified in each direction, the detection size of the defects in the first process may also be acquired, and the determination of the defect area may be performed based on the number of defects within a detection size range of some of the measured defects. By limiting the detection size, the substrate's <010> Direction and <011> Even if a difference in the number of defects in the direction is recognized, it is possible to determine with high precision whether an I-rich region is included.
[0059] The above specific range of detection sizes, for a substrate actually including an I-rich region, <010> The number of defects of a detection size within a certain range existing in the direction, and <011> The number of defects of the same range of detection sizes existing in a direction can be compared, and the difference can be set to any range of detection sizes. The range of detection sizes determined in this way can also be applied to other substrates where the level outside the defect area can be considered to be generally the same.
[0060] As a method for comparing the number of defects, for example, a schematic diagram plotting the defect locations on a substrate, as shown in FIG. 3, is prepared, and the substrate <010> The number of defects in the direction, and <011> The number of defects in the direction is compared. In this case, if there is a significant difference between the two, they can be compared visually. In the case of Fig. 3, it is visually evident, <010> Rather than the number of defects in the direction <011> Since the number of defects in the direction is higher, the difference is recognized. Therefore, it is determined that the above substrate includes an I-rich region.
[0061] In addition, instead of the above comparison method, a specific threshold value regarding the difference in the number of defects can be determined to determine whether the substrate contains an I-rich region. It is also possible to make a determination based on the presence or absence of a statistically significant difference. Furthermore, regarding a substrate that actually contains an I-rich region and a substrate that does not contain an I-rich region, <010> Regarding the number of defects a in the direction, <011> By referring to the ratio b / a of the number of defects b in the direction, a threshold value (both cases where b / a is greater than 1 and where it is less than 1) can be determined.
[0062] For example, the threshold value for cases where b / a is greater than 1 can be set to b / a ≥ 1.1, but it is not specifically limited and can be set appropriately depending on the purpose of judgment or the total number of defects in the substrate.
[0063] For example, if one wishes to determine that all substrates containing I-rich regions are substrates containing I-rich regions, it is desirable to make the threshold value closer to 1 (e.g., b / a ≥ 1.05). Accordingly, even for substrates where the ratio of other regions to I-rich regions is large, it is possible to determine with higher precision that they contain I-rich regions.
[0064] Conversely, for a substrate that does not contain an I-rich region, if the intention is to reduce the possibility of misjudging that it contains an I-rich region due to deviations in the number of defects in each direction, it is preferable to use a threshold greater than 1.1 (e.g., b / a ≥ 1.2). In particular, since the number of defects is small and susceptible to deviations, it is more preferable to use a threshold greater than 1.1.
[0065] Likewise, the threshold value for the case where b / a is less than 1 can be set to b / a ≤ 0.9, but it is not specifically limited and can be set appropriately depending on the purpose of judgment or the total number of defects in the substrate.
[0066] For example, if one wishes to determine that all substrates containing I-rich regions are substrates containing I-rich regions, it is desirable to make the threshold value closer to 1 (e.g., b / a ≤ 0.95). Accordingly, even for substrates where the ratio of other regions to I-rich regions is large, it is possible to determine with higher precision that they contain I-rich regions.
[0067] Conversely, for a substrate that does not contain an I-rich region, if the intention is to reduce the possibility of misjudging that it contains an I-rich region due to deviations in the number of defects in each direction, it is preferable to use a threshold value smaller than 0.9 (e.g., b / a ≤ 0.8). In particular, since the number of defects is small and susceptible to deviations, it is more preferable to use a threshold value smaller than 0.9.
[0068] Instead of the number of defects, of the substrate <010> Direction and <011> If a difference in the defect density of the direction is recognized, it may be determined that the substrate includes an I-rich region. Accordingly, <010> Area including direction and <011> Even if the range of angles of the area including the direction is different, the defect area can be accurately determined.
[0069] At this time, as a specific threshold value regarding the difference in defect density for determining that the substrate includes an I-rich region, for a substrate that actually includes an I-rich region and a substrate that does not include an I-rich region, <010> Regarding the defect density a' in the direction, <011> A threshold value (both cases where b' / a' is greater than 1 and less than 1) can be determined by referring to the ratio of the defect density b' in the direction b' / a'.
[0070] For example, the same value as the threshold value obtained from the above number of defects can be used as the threshold value for the difference in defect density.
[0071] In addition, the number of defects or defect density can be obtained by accumulating measurement results for multiple substrates having defects of the same level of size and density. By making a determination based on the measurement results of multiple substrates of the same level, it becomes possible to determine the defect area with high precision even when the number of defects per substrate is small.
[0072] Examples
[0073] The present invention will be described in detail below with reference to examples, but this does not limit the invention.
[0074] (Example 1)
[0075] First, two cleaned silicon single crystal substrates with a diameter of 300 mm and a mirror-polished surface orientation (100), manufactured using the Czochralski method under different conditions, were prepared and designated as substrate A and substrate B, respectively.
[0076] Next, foreign matter present on the main surface of substrates A and B was measured by a surface inspection device equipped with a rotary stage (SP7XP, Oblique mode (directional incidence), 11 nm up).
[0077] Continuing, with respect to substrates A and B, of the substrate <010> Area including direction and <011> The number of defects present in the area including the direction was investigated.
[0078] Here, of the substrate <010> The region including the orientation was defined as the four equivalent orientations
[0010] ,
[0001] , [0-10], and [00-1] with respect to the center of the substrate, and a range of ±22.5° from thereon. Likewise, the substrate's <011> The area including the direction was defined as the four equivalent orientations
[0011] , [0-11], [0-1-1], and [01-1] with respect to the center of the substrate, and a range of ±22.5° from them.
[0079] At this time, the substrate that determines to include an I-rich region <010> Area including direction and <011> The threshold values for the difference in the number of defects or defect density existing in the region including the direction are set to 0.9 and 1.1, and the substrate's <010> Regarding the number of defects or defect density of a substrate existing in a region including a direction <011> If the value of the ratio of the number of defects or defect density in the region including the direction is less than 0.9 or greater than 1.1, it was determined that the substrate includes an I-rich region.
[0080] As a result, substrate A is of the substrate <010> While the number of defects in the area including the direction was 707, <011> The number of defects in the region including the orientation was 379. Therefore, the substrate's <010> Regarding the number of defects in the direction <011> Since the ratio of the number of defects in each direction was 379 / 707 ≈ 0.536 < 0.9, it was determined that substrate A contains an I-rich region.
[0081] Substrate B is <010> While the number of defects in the area including direction was 23,029, <011> The number of defects in the region including the orientation was 23,575. Therefore, the substrate's <010> Regarding the number of defects existing in the area including the direction <011> The ratio of the number of defects in the region including the direction was 23575 / 23029 ≈ 1.024, and since 0.9 < 1.024 < 1.1, it was determined that substrate B does not contain an I-rich region.
[0082] As a result of determining the defect region for each adjacent substrate using a known etching method, it was confirmed that substrate A contains an I-rich region and substrate B is a full V-rich region and does not contain an I-rich region, and it was confirmed that the defect region was correctly evaluated.
[0083] From the above results, it was shown that the determination of an I-rich region by the method for determining a defect region of a silicon single-crystal substrate according to the present invention is effective.
[0084] (Example 2)
[0085] One mirror-polished silicon single crystal substrate with a diameter of 300 mm, manufactured using the Czochralski method, was prepared and cleaned, and designated as substrate C.
[0086] Next, defects present on the main surface of substrate C and substrate B of Example 1 were measured by a surface inspection device equipped with a rotary stage (SP7XP, Oblique mode (low angle incidence), 11 nm up). The distribution of defects on substrate C is shown in FIG. 5, and the distribution of defects on substrate B is shown in FIG. 6.
[0087] Next, for substrates B and C, a schematic diagram plotting the defect locations for defects with a detection size of 13 nm or larger is prepared, and the substrate's <010> The number of defects existing in the region including the direction and <011> The number of defects present in the area including the direction was visually compared.
[0088] Here, of the substrate <010> The region including the orientation was defined as the total of four equivalent orientations
[0010] ,
[0001] , [0-10], and [00-1] with respect to the center of the substrate, and a range of ±10° from thereon. Likewise, the substrate's <011> The area including the direction was defined as the four equivalent orientations
[0011] , [0-11], [0-1-1], and [01-1] with respect to the center of the substrate, and a range of ±10° from them.
[0089] In addition, of a substrate that determines that the substrate includes an I-rich region <010> Area including direction and <011> The threshold values for the difference in the number of defects or defect density existing in the region including the direction are set to 0.9 and 1.1, and the substrate's <010> Regarding the number of defects or defect density of a substrate existing in a region including a direction <011> If the value of the ratio of the number of defects or defect density in the region including the direction is less than 0.9 or greater than 1.1, it was determined that the substrate includes an I-rich region.
[0090] The distribution of defects with a detection size of 13 nm or larger on substrate C is shown in Fig. 3. From Fig. 3, <010> More than the number of defects existing in the area including the direction <011> Substrate C was determined to contain an I-rich region because the number of defects present in the area including the direction was visually clearly greater and the difference was recognized.
[0091] If the defect density existing in the region including each direction is calculated, the substrate <010> The defect density in the region including the direction is 0.140 defects / cm² 2 , <011> The defect density in the region including the direction is 0.879 defects / cm² 2 and the substrate <010> Regarding the defect density existing in the region including the direction <011> Since the ratio of defect density in the region including the direction was 0.879 / 0.140=6.279>1.1, it was determined that substrate C contains an I-rich region.
[0092] In fact, regarding the adjacent substrate of substrate C, as a result of determining the defect area by a known etching method, it was confirmed that substrate C is a full I-rich area.
[0093] The distribution of defects with a detection size of 13 nm or larger on substrate B is shown in Fig. 4. From Fig. 4, <010> The number of defects existing in the region including the direction, and <011> No visually apparent difference was recognized between the number of defects present in the area including the direction.
[0094] If the defect density existing in the region including each direction is calculated, the substrate <010> The defect density in the region including the direction is 45.35 defects / cm² 2 , <011> The defect density in the region including the direction is 46.75 defects / cm² 2 and the substrate <010> Regarding the defect density existing in the region including the direction <011> The ratio of defect density in the region including the direction was 46.75 / 45.35=1.031, and since 0.9<1.031<1.1, it was determined that substrate B does not contain an I-rich region.
[0095] Meanwhile, in Example 1, it has been confirmed that substrate B is a full V-rich region and does not include an I-rich region by a known etching method.
[0096] From the above results, the substrate <010> Area including direction and <011> It has been shown that the presence or absence of an I-rich region can be determined based on the difference in defect density existing in a region including a direction, and that the determination of an I-rich region by the method for determining a defect region of a silicon single-crystal substrate according to the present invention is effective.
[0097] In addition, for substrates C and B, for all detected defects, of the substrate <010> Regarding the defect density existing in the region including the direction <011> The ratio of defect densities in the region including the direction was calculated. 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 contains an I-rich region and substrate B does not contain an I-rich region. In addition, the defect density ratio of substrate C was significantly larger than the threshold value when the detection size was limited, indicating that limiting the defect size is effective for determining the I-rich region. On the other hand, the magnitude of the defect density ratios of substrate C and substrate B was reversed between the case where the detection size was limited and the case where it was not, which is because there are two types of defects with large aspect ratios in substrate C, each having a different average size and major axis direction.
[0098] (Comparative Example)
[0099] Defects present on the main surfaces of substrate C and substrate B used in Example 2 were measured using a surface inspection device (SP7XP, Oblique mode, 11nmUp), and defect locations were plotted from the obtained location information. The distribution of defects on substrate C is shown in FIG. 5, and the distribution of defects on substrate B is shown in FIG. 6.
[0100] Regarding substrates B and C, an attempt was made to determine the defect area based on the technology described in Patent Document 3. Although the total number of defects differed, both were determined to be front V-rich areas in that defects existed on the entire surface of the substrates. Substrate B, which is front V-rich, was accurately determined, but for substrate C, which contains an I-rich area, the determination result was different from the actual result.
[0101] As described above, according to an embodiment of the present invention, it was possible to accurately determine whether a silicon single-crystal substrate includes an I-rich region.
[0102] The present specification includes the following aspects.
[0103] [1]: A method for determining a defect area of a silicon single crystal substrate with a mirror-polished surface orientation (100) using a laser scattering surface inspection device equipped with a rotating stage, wherein the crystal orientation of the main surface of the silicon single crystal substrate is <010> Area including direction and <011> Crystal defects existing in a region including a direction are measured by the four-directional incidence mode of the surface inspection device to obtain the number of defects or defect density of the crystal defects, and the crystal orientation <010> The number of defects or defect density of the crystal defects existing in a region including the direction, and the crystal orientation <011> A method for determining a defect region of a silicon single crystal substrate, comprising determining whether the silicon single crystal substrate contains an I-rich region based on the difference between the number of defects or the defect density of the crystal defects existing in a region including a direction.
[0104] [2]: The area for measuring the crystal defect above is the crystal orientation of the main surface of the silicon single crystal substrate. <010> Direction and <011> A method for determining a defect area of a silicon single crystal substrate of the above [1], comprising using the axis of direction as a centerline and having an arbitrary angle range within ±22.5° from this centerline.
[0105] [3]: A method for determining a defect area of a silicon single crystal substrate according to [1] or [2], wherein the area for measuring the crystal defect is an area extending more than 10 mm outward from the center of the main surface of the silicon single crystal substrate.
[0106] [4]: A method for determining a defect area of a silicon single crystal substrate according to [1], [2] or [3], comprising obtaining a detection size of the crystal defect when measuring the crystal defect, and making a determination based on the number of defects or defect density of some of the crystal defects within the detection size range of the measured crystal defects.
[0107] [5]: A method for determining the defect area of the silicon single crystal substrate of [1], [2], [3], or [4], comprising accumulating the measurement results for a plurality of silicon single crystal substrates having the same level of size and density of the crystal defects to obtain the number of defects or the defect density of the crystal defects.
[0108] [6]: A method for determining a defect area of the silicon single crystal substrate of [1], [2], [3], [4] or [5], comprising re-polishing and / or cleaning the main surface of the silicon single crystal substrate before the above measurement.
[0109] Meanwhile, the present invention is not limited to the above embodiments. The above embodiments are examples, and any configuration that is substantially identical to the technical concept described in the claims of the present invention and exhibits the same functional effect is included within the technical scope of the present invention.
Claims
Claim 1 A method for determining a defect region of a silicon single crystal substrate using a laser scattering type surface inspection device equipped with a rotating stage to determine a defect region of a silicon single crystal substrate with a mirror-polished surface orientation (100), wherein the crystal orientation of the main surface of the silicon single crystal substrate is <010> Area including direction and <011> Crystal defects existing in a region including a direction are measured by the oblique incidence mode of the surface inspection device to obtain the number of defects or defect density of the crystal defects, and the crystal orientation <010> The number of defects or defect density of the crystal defects existing in a region including the direction, and the crystal orientation <011> A method for determining a defect region of a silicon single crystal substrate, characterized by determining whether the silicon single crystal substrate contains an I-rich region based on the difference between the number of defects or the defect density of the crystal defects existing in a region including a direction. Claim 2 In claim 1, the region for measuring the crystal defect is the crystal orientation of the main surface of the silicon single crystal substrate. <010> Direction and <011> A method for determining a defect region of a silicon single crystal substrate, characterized by using a directional axis as a centerline and defining the range of any angle within ±22.5° from the centerline. Claim 3 A method for determining a defect area of a silicon single crystal substrate according to claim 1, characterized in that the area for measuring the crystal defect is an area extending more than 10 mm outward from the center of the main surface of the silicon single crystal substrate. Claim 4 A method for determining a defect region of a silicon single-crystal substrate according to claim 1, characterized in that when measuring the crystal defect, the detection size of the crystal defect is also obtained, and the determination is made based on the number of defects or defect density of crystal defects within the detection size range of some of the measured crystal defects. Claim 5 A method for determining a defect region of a silicon single-crystal substrate, characterized in that, in claim 1, the number of defects or defect density of the crystal defects is obtained by accumulating the measurement results for a plurality of silicon single-crystal substrates having crystal defects of the same level of size and density. Claim 6 A method for determining a defect area of a silicon single crystal substrate, characterized in that, in any one of claims 1 to 5, the main surface of the silicon single crystal substrate is re-polished and / or cleaned before the measurement.