Management method of surface defect inspection device and standard wafer

Abstract

The present invention is a method for managing a surface defect inspection device on which a high-low angle scattering detector is mounted, the method comprising steps of: preparing, as a standard wafer, a semiconductor Si wafer in which a plurality of defects having a convex or concave shape in which the dimension in the direction parallel to the surface is larger than the dimension in the vertical direction and having known coordinates and sizes are formed on the outermost surface; with a device to be managed, detecting by a detector scattered light from defects of the standard wafer; acquiring the coordinates and size of the defects; for defects of the same coordinates, calculating for each detector a detected size difference, which is the difference between the known size of a standard wafer and the detected size; acquiring the absolute value of the most frequent value for each detector; and when the absolute value of the most frequent value of the detection size difference of a high-angle scattering detector is larger than that of a low-angle scattering detector, performing inspection and calibration of the optical system of the device. Thus, it is possible to provide a management method for a surface defect inspection device capable of detecting an abnormality only in the high-angle scattering detector of the surface defect inspection device and calibrating the device in which the abnormality has been detected.

Description

Surface defect inspection equipment management method and standard wafer

[0001] The present invention relates to a method for managing a surface defect inspection apparatus and a standard wafer.

[0002] Semiconductor silicon wafers are used in a variety of semiconductor devices, and it is necessary to deliver substrates that meet the requirements of device manufacturers. During the wafer manufacturing process, defective products that do not meet customer requirements may occur. To prevent defective products from being delivered to customers, wafer manufacturers use a variety of inspection equipment to perform shipping inspections. For this reason, inspection equipment must always be in good working order, and any abnormalities that occur must be detected promptly and corrected to a normal state.

[0003] Patent Document 1 discloses a technology for generating a difference value between a signal obtained from an image of a measurement object and a signal obtained from a reference image, as well as a frequency distribution of the difference values, and determining whether the frequency distribution satisfies predetermined conditions.

[0004] Patent Document 2 discloses a technology in which one or more micro-pits of approximately the same size, with a scattered light intensity equivalent to the scattered light intensity of a standard particle with a specified particle size, are generated in a certain micro-region on the oxide film of a silicon wafer, to prepare a calibration reference wafer on which a group of micro-pits is formed, and the calibration reference wafer is irradiated with laser light from a particle counter and the particle counter is calibrated based on the measurement results of the scattered light.

[0005] JP2016-173252A JP11-014534A

[0006] Surface defect inspection is an important inspection required by wafer manufacturers. Surface defect inspection equipment (particle counters) are typically used to inspect wafer surfaces for surface defects. Particle counters are calibrated to ensure that the same defect is detected at the same size regardless of the equipment used. Standard wafers coated with silica of known sizes are used to inspect and calibrate each piece of equipment. This ensures that specific scattered light intensities are correctly converted to known sizes. If necessary, standard wafers can be used for daily inspections, and if an abnormality is detected during measurements during daily inspections, the equipment can be inspected. However, in particle counters equipped with multiple detectors, even if an optical system abnormality that adversely affects only the high-angle scattering detector occurs, the abnormality may not be detected during daily inspections using standard silica-coated wafers.

[0007] Patent Document 1 describes a technology for determining whether to adjust the device based on the frequency distribution of difference values ​​obtained from an acquired image and a reference image, but does not describe a means for observing abnormalities in the optical system that have a negative effect only on the high-angle scattering detector. Patent Document 2 also discloses a technology for forming pits on the oxide film of a silicon wafer that have a scattered light intensity equivalent to that of scattered light generated by standard particles of a known size, and calibrating a particle counter using the measurement results of that wafer, but does not describe a means for detecting abnormalities in the optical system that have a negative effect only on the high-angle scattering detector.

[0008] The present invention has been made to solve the above problems, and aims to provide a method for managing surface defect inspection devices that can detect abnormalities in the optical system that have a negative effect only on the high-angle scattering detector of the surface defect inspection device, and can perform calibration on the device in which an abnormality is detected.

[0009] In order to achieve the above object, the present invention provides a method for managing a surface defect inspection device that is equipped with a high-angle scattering detector and a low-angle scattering detector having a detection angle lower than that of the high-angle scattering detector as detectors and that inspects surface defects of semiconductor silicon wafers, comprising: a standard wafer preparation step of preparing, as a standard wafer for managing the surface defect inspection device, a semiconductor silicon wafer that has a convex or concave shape whose dimension parallel to the wafer surface is greater than the dimension perpendicular to the wafer surface and has a plurality of defects with known coordinates and sizes formed on its outermost surface; a defect detection step of using the surface defect inspection device to be managed to irradiate the surface of the standard wafer with a laser, detect scattered light generated by the defects present on the outermost surface of the standard wafer with the detector, and obtain the coordinates and sizes of the defects; a size shift calculation step of comparing the known coordinates of the defects on the standard wafer with the coordinates of the defects detected in the defect detection step, and calculating, for defects at the same coordinates, a detected size difference, which is the difference between the known size on the standard wafer and the size detected in the defect detection step, for each detector; A method for managing a surface defect inspection device is provided, comprising: a mode acquisition step of acquiring, for each detector, the absolute value of the mode of the detected size difference from the calculated detected size difference; and an inspection and calibration step of inspecting and calibrating the optical system of the surface defect inspection device when the absolute value of the mode of the detected size difference in the high-angle scattering detector is greater than the absolute value of the mode of the detected size difference in the low-angle scattering detector.

[0010] In the present invention, a standard wafer is used that contains defects of the above dimensions, in other words, defects with low defect heights or defects with shallow defect depths. Therefore, the high-angle scattering component of the scattered light during laser irradiation can be increased. Therefore, abnormalities in the high-angle scattering detector can be easily detected. Furthermore, by performing the above steps, an abnormality in the optical system that adversely affects only the high-angle scattering detector of the surface defect inspection device (hereinafter simply referred to as an abnormality in the high-angle scattering detector only) can be quickly detected, allowing inspection and calibration of the optical system of the device.

[0011] Furthermore, in the mode obtaining step, when obtaining the absolute value of the mode of the detected size difference, the mode can be obtained by creating a frequency distribution curve of the detected size difference.

[0012] In this way, the absolute value of the most frequent value of the detected size difference can be obtained more easily.

[0013] In addition, in the standard wafer preparation step, when preparing the standard wafer, a semiconductor silicon wafer having pits or PIDs formed as the defects can be prepared.

[0014] Such pits and PID defects can be formed relatively easily and conveniently.

[0015] In addition, when preparing the standard wafer in the standard wafer preparation step, a semiconductor silicon wafer in which defects having a size of 100 nm or less are formed can be prepared.

[0016] The smaller the detected defect size, the smaller the sizing error tends to be. Therefore, it is preferable to prepare a standard wafer with defects of 100 nm or less. This is because it is effective in suppressing the difference in detected size caused by errors and in more accurately calculating the difference in detected size caused by anomalies in the high-angle scattering detector alone.

[0017] The present invention also provides a standard wafer for controlling a surface defect inspection device, characterized in that the standard wafer is a semiconductor silicon wafer having, on its outermost surface, a plurality of convex or concave defects whose dimension parallel to the wafer surface is greater than the dimension perpendicular to the wafer surface.

[0018] In the case of such a standard wafer of the present invention, the defects formed thereon are low in height or shallow in depth, as described above, and therefore the high-angle scattering component can be increased in the scattered light during laser irradiation, making it possible to easily detect abnormalities in the high-angle scattering detector.

[0019] The defect may be a pit or a PID.

[0020] Such pits and PID defects can be formed relatively easily and can be easily prepared.

[0021] The defects may be 100 nm or less in size.

[0022] Such a configuration is effective in suppressing the difference in detected size caused by errors and more accurately calculating the difference in detected size caused by an abnormality in only the high-angle scattering detector.

[0023] The method for managing a surface defect inspection device of the present invention allows for the rapid detection of an abnormality in the optical system that adversely affects only the high-angle scattering detector, and for the inspection and calibration of the optical system of the device. Furthermore, the standard wafer of the present invention can increase the high-angle scattering component in the scattered light during laser irradiation, making it easy to detect an abnormality in the high-angle scattering detector.

[0024] It is an explanatory diagram showing an example of a reference for coordinates of defects.It is a schematic diagram showing an example of a standard wafer of the present invention.It is a flowchart showing an example of a process of a surface defect inspection device management method of the present invention.It is a schematic diagram showing an example of a conventional standard wafer.It is an explanatory diagram showing an example of a reference for coordinates of defects.

[0025] The present invention will be described in detail below with reference to the drawings as an example of an embodiment, but the present invention is not limited to this. As mentioned above, there has been a need for a method of managing a surface defect inspection device that can detect an abnormality in the optical system that adversely affects only the high-angle scattering detector of the surface defect inspection device and can calibrate the device in which an abnormality has been detected. Therefore, the present inventors have conducted extensive research into a method of managing such a surface defect inspection device.

[0026] The present inventors have also devised a method for managing a surface defect inspection device that is equipped with a high-angle scattering detector and a low-angle scattering detector having a detection angle lower than that of the high-angle scattering detector as detectors and that inspects surface defects of semiconductor silicon wafers, the method comprising the steps of: a standard wafer preparation step (preparing, as a standard wafer for managing the surface defect inspection device, a semiconductor silicon wafer that has a convex or concave shape whose dimension parallel to the wafer surface is greater than the dimension perpendicular to the wafer surface and that has a plurality of defects formed on its outermost surface whose coordinates and sizes are known); a defect detection step (using the surface defect inspection device to be managed, irradiating a laser onto the surface of the standard wafer, detecting scattered light generated by the defects present on the outermost surface of the standard wafer with the detector, and obtaining the coordinates and sizes of the defects); and a size shift calculation step (preparing the standard wafer for managing the standard wafer, the present inventors have found that a method for managing a surface defect inspection device comprising the steps of: comparing known coordinates of defects in the high-angle scattering detector with coordinates of defects detected in the defect detection step, and calculating, for each detector, a detected size difference, which is the difference between the known size on the standard wafer and the size detected in the defect detection step, for defects at the same coordinates; a mode acquisition step (obtaining, for each detector, the absolute value of the mode of the detected size difference from the calculated detected size difference); and an inspection and calibration step (inspecting and calibrating the optical system of the surface defect inspection device if the absolute value of the mode of the detected size difference in the high-angle scattering detector is greater than the absolute value of the mode of the detected size difference in the low-angle scattering detector), can quickly detect abnormalities in only the high-angle scattering detector as described above, and can properly inspect and calibrate the optical system of the device, thereby completing the present invention.

[0027] Furthermore, the inventors have found that a standard wafer for controlling a surface defect inspection device, which is a semiconductor silicon wafer having a plurality of convex or concave defects formed on its outermost surface, the dimension parallel to the wafer surface being greater than the dimension perpendicular to the wafer surface, has a large amount of high-angle scattered components in the scattered light when irradiated with a laser, and is therefore suitable for detecting abnormalities with a high-angle scattering detector, thereby completing the present invention.

[0028] An example of a standard wafer according to the present invention is shown in Figure 1. This is a standard wafer (semiconductor silicon wafer) for managing a surface defect inspection device, and as shown in Figure 1, multiple defects exist on its outermost surface. It is sufficient for the number of defects to be multiple. The greater the number of defects, the greater the number of detection samples, allowing for the calculation of a larger number of detected size differences (described below), which is preferable for obtaining the absolute value of the most frequent detected size differences. From this perspective, the greater the number of defects, the better, and although there is no set upper limit, taking into account factors such as the time required for detection, a number of 50,000 defects would be efficient.

[0029] The defect shape may be either convex or concave relative to the wafer surface. However, when comparing the dimension parallel to the wafer surface with the dimension perpendicular to the wafer surface, the defect shape is larger in the former direction than in the latter direction. In other words, the defect height is low or the defect depth is shallow.

[0030] Here, the significance of the above-described defect shapes will be explained. First, FIG. 3 shows an example of a conventional standard wafer, i.e., a standard wafer with defects dominated by spheres, such as a silica-coated semiconductor silicon wafer. When the conventional standard wafer shown in FIG. 3 is irradiated with a laser from the detector of a surface defect inspection system, the high-angle scattering component is small, making it difficult for the high-angle scattering detector to detect abnormalities. On the other hand, defects with low defect heights or shallow defect depths in the standard wafer of the present invention shown in FIG. 1 have many high-angle scattering components, making it easy to detect abnormalities with the high-angle scattering detector. Therefore, this defect shape is extremely useful for detecting abnormalities with the high-angle scattering detector.

[0031] Furthermore, the size and type of the defect are not particularly limited. Since the smaller the detection size, the smaller the sizing error tends to be, it is more preferable to use a defect with a size of 100 nm or less. Note that the size here refers to the diameter of a sphere when the defect is assumed to have a spherical shape. The lower limit of the defect size is sufficient as long as it is larger than 0 nm and can be detected by a high-angle scattering detector.

[0032] Furthermore, if the defects are pits or PIDs, they can be formed relatively easily. Therefore, it becomes a standard wafer that can be easily prepared. For example, a semiconductor silicon wafer with many pits may be produced by producing a crystal under conditions in which vacancy formation is dominant, and then processing the wafer using a general method. Furthermore, a semiconductor silicon wafer with many PIDs may be produced by spin-coating a Ni standard solution on the wafer, followed by a diffusion heat treatment, and then polishing. The concentration of the Ni standard solution is not particularly limited, but the lower the concentration, the more likely it is that PIDs with a smaller detectable size will be formed. Preferably, the concentration on the wafer surface is 1×10 １１ atoms / cm ２ The temperature and time of the diffusion heat treatment may be set to less than 800°C for 5 hours, provided that the temperature and time are sufficient for Ni to reach the rear surface. The polishing depth is not particularly limited, but may be set to 250 nm, for example. This allows scratches and particles introduced during the intentional contamination process to be efficiently removed.

[0033] As mentioned above, the defects in the standard wafer of the present invention are not limited to pits and PIDs, but may have the above-mentioned shape (i.e., a shape whose dimensions in the directions parallel and perpendicular to the wafer surface satisfy the above-mentioned magnitude relationship). The wafer may have a plurality of defects on its outermost surface that satisfy this relationship, and the manufacturing process is not limited. It may be manufactured by a general method, or may be manufactured by special processing.

[0034] Next, a method for managing a surface defect inspection device according to the present invention will be described. Figure 2 shows an example of the steps of the management method according to the present invention. Overall, the method comprises steps S1: standard wafer preparation step, S2: defect detection step, S3: size shift calculation step, S4: mode value acquisition step, and S5: inspection and calibration step. Each step will be described in detail below.

[0035] (S1: Standard Wafer Preparation Step) As a standard wafer for managing a surface defect inspection device, a semiconductor silicon wafer is prepared, the semiconductor silicon wafer having a convex or concave shape whose dimension parallel to the wafer surface is greater than the dimension perpendicular to the wafer surface, and having a plurality of defects with known coordinates and sizes formed on its outermost surface. Specifically, first, a semiconductor silicon wafer is prepared in which defects such as those shown in FIG. 1 are formed on its outermost surface. If the coordinates and sizes of the defects on this semiconductor silicon wafer are already known, the wafer is used as is as a standard wafer. On the other hand, if the coordinates and sizes are not yet known, the coordinates and sizes of the defects are obtained, for example, using a normal surface defect inspection device. That is, a laser is irradiated onto the surface of the semiconductor silicon wafer, and scattered light generated by the defects is detected with detectors (a high-angle scattering detector and a low-angle scattering detector (a detector having a detection angle lower than that of the high-angle scattering detector)), and the coordinates and sizes of the defects are obtained. In this way, a standard wafer with known defect coordinates and sizes can be prepared. The reference (setting of coordinate axes) for the coordinates of the known defects is not particularly limited, but can be set as shown in FIG. 4. In the case of Figure 4, the origin is set at the lower left position of the wafer in a planar view. That is, the origin is set at the intersection of the tangent to the left end of the wafer outer periphery and the tangent to the bottom end in a planar view. For example, for a wafer with a diameter of 300 mm, the coordinates (X, Y) of the wafer center are (150 mm, 150 mm). Of course, this is not limited to this, and the coordinate axis setting can be determined appropriately. Furthermore, the sizes of known defects are assumed to be the sizes acquired by the high-angle scattering detector and the low-angle scattering detector. Even when the same defect is detected, there is usually a difference in the size detected by the high-angle scattering detector and the low-angle scattering detector, and also, in a later process, the sizes acquired by both detectors of the surface defect inspection device to be managed will be compared for each detector.

[0036] Note that a normal surface defect inspection device here refers to a surface defect inspection device in a state where there are no problems with the device, where a specific scattered light intensity can be correctly converted to a predetermined detection size, and where, if the device is the same model, it can detect the same defect as the same size. Furthermore, the normal device and the device to be managed, which will be described later, do not necessarily have to be the same device, but can be another device of the same model. Since the same model has the same optical system, any device in a normal state can be adjusted so that all defects are detected at the same size. Of course, the coordinates and sizes detected using the same device when it was in a normal state can also be used as known coordinates and sizes.

[0037] (S2: Defect Detection Step) Using a surface defect inspection device to be managed, a laser is irradiated onto the surface of a standard wafer, and scattered light generated by defects present on the outermost surface of the standard wafer is detected with a detector, and the coordinates and size of the defects are obtained. This surface defect inspection device to be managed is equipped with a high-angle scattering detector and a low-angle scattering detector (a detector with a detection angle lower than that of the high-angle scattering detector), and is the device to be inspected for abnormalities occurring only in the high-angle scattering detector. The coordinates and size of the defects are obtained using both the low-angle scattering detector and the high-angle scattering detector.

[0038] (S3: Size shift calculation process) The known coordinates of defects on the standard wafer are compared with the coordinates of defects detected in the defect detection process. Then, for defects with the same coordinates, the detected size difference, which is the difference between the known size on the standard wafer and the size detected in the defect detection process, is calculated for each detector. That is, the following calculation formula can be used for both detectors. <In the case of a low-angle scattering detector: Calculation formula L> [Detected size difference (low-angle scattering detector version)] = [Known size (low-angle scattering detector version)] - [Detected size in the defect detection process (low-angle scattering detector version)] <In the case of a high-angle scattering detector: Calculation formula H> [Detected size difference (high-angle scattering detector version)] = [Known size (high-angle scattering detector version)] - [Detected size in the defect detection process (high-angle scattering detector version)]

[0039] For example, suppose there is a defect that is normally (detected by a properly functioning surface defect inspection device) (step S1) detected as 30 nm by the low-angle scattering detector and 40 nm by the high-angle scattering detector. Then, suppose that in step S2, the surface defect inspection device to be managed has an abnormality in the optical system of only the high-angle scattering detector, causing only the detected size to be smaller, resulting in the defect being detected as 30 nm by the low-angle scattering detector and 35 nm by the high-angle scattering detector. In this case, the difference in detected size in step S3 is 0 nm by the low-angle scattering detector and 5 nm by the high-angle scattering detector.

[0040] (S4: Mode Acquisition Step) From the calculated detected size difference, the absolute value of the mode of the detected size difference is acquired for each detector. At this time, it is preferable to create a frequency distribution curve of the detected size difference, as this allows for easy acquisition. As in the above example, when an abnormality occurs in the optical system of the detector, the detected size generally tends to be smaller than the known size. Therefore, in the calculation formulas L and H that subtract from the known size, the detected size difference is usually a positive value. Therefore, the mode of the detected size difference is also a positive value. On the other hand, unlike the calculation formulas L and H, in the calculation formula that subtracts from the detected size in the defect detection process, the detected size difference and its mode are negative values. However, since the present invention specifies the absolute value of the mode of the detected size difference, both types of calculation formulas can be used.

[0041] In discovering the present invention, the inventors also considered other possible criteria, such as average and maximum values, which are other statistical values. However, when a large particle is reduced in size by laser irradiation, the size shift (detected size difference) becomes significantly larger, which has a greater impact on the results than the size shift due to detector abnormalities. Therefore, average and maximum values ​​are not suitable as criteria. Because the size shift follows a normal distribution, the mode, which can exclude outliers, is more suitable.

[0042] (S5: Inspection and calibration step) When the absolute value of the most frequent value of the detected size difference in the high-angle scattering detector is greater than the absolute value of the most frequent value of the detected size difference in the low-angle scattering detector, the optical system of the surface defect inspection device is inspected and calibrated.

[0043] In rare cases, both conventional silica-coated standard wafers and the standard wafers of the present invention may experience a shift in detected size due to deterioration of the standard wafer. In such cases, the shift tends to be roughly the same across all detectors. On the other hand, abnormalities specific to the high-angle scatter detector are observed as changes in the detected size only by the high-angle scatter detector. Therefore, to confirm that the observed size shift is specific to the high-angle scatter detector, the present invention uses a system equipped with not only a high-angle scatter detector but also a low-angle scatter detector, and compares the absolute values ​​of the most frequent detected size differences as described above. This allows for the rapid detection of optical system abnormalities that adversely affect only the high-angle scatter detector, allowing for appropriate inspection and calibration of the system's optical system. Inspection and calibration of the high-angle scatter detector's optical system can be performed, for example, by adjusting the optical axis.

[0044] The present invention will be described in more detail below with reference to examples of the present invention, but the present invention is not limited to these. (Example) First, a silicon single crystal was produced as a standard semiconductor silicon wafer under conditions in which vacancy formation was dominant, and the wafer was processed using conventional techniques (slicing, lapping / grinding, etching, and polishing) to produce a mirror-finished silicon wafer with a diameter of 300 mm and a large number (26,000) of pits (defects) with a detectable size of at least 15 to 100 nm. These pits were confirmed to have a larger dimension parallel to the wafer surface than perpendicular to it, and to have shallow defect depths. Next, a particle counter (normal surface defect inspection device) equipped with a low-angle scattering detector and a high-angle scattering detector, manufactured by KLA, was used, which was confirmed to be in a normal state in which all defects could be detected at the same size as other models. ＸＰThe measurement was performed in oblique mode at 15 nm up using a standard wafer, and scattered light generated by defects present on the outermost surface of the standard wafer was detected by detectors (a low-angle scattering detector and a high-angle scattering detector), and the coordinates and sizes of the defects were obtained. That is, a standard wafer of the present invention was prepared (step S1).

[0045] Next, as the particle counter to be managed, the normal SP7 used in the S1 process was used. ＸＰ Different from SP7 ＸＰ Measurement was performed in oblique mode / 15 nm up using a microscope, and scattered light generated by defects present on the outermost surface of the standard wafer was detected by detectors (a low-angle scattering detector and a high-angle scattering detector), and the coordinates and sizes of the defects were obtained (step S2).

[0046] Next, the coordinates of the defects detected in steps S1 and S2 were compared, and the detected size difference (values ​​calculated using calculation formulas L and H) between defects detected at the same coordinates was calculated for each detector (step S3). A frequency distribution curve was then created for the numerous detected size differences thus obtained, and the absolute value of the mode was obtained for each detector (step S4). The absolute value of the mode of size difference for the low-angle scattering detector was 0 nm, while the absolute value of the mode of size difference for the high-angle scattering detector was 4 nm. Since the absolute value of the mode of size difference for the low-angle detector was greater than the absolute value of the mode of size difference for the high-angle scattering detector, it was determined that there was an abnormality in the optical system. An inspection of the device revealed a malfunction in the optical system of the high-angle scattering detector. Therefore, the optical system of this high-angle scattering detector was calibrated (step S5).

[0047] For confirmation, the optical system of the low-angle scattering detector was also inspected, but no defects were found. In this way, the management method of the present invention was able to detect an abnormality only in the high-angle scattering detector.

[0048] (Comparative Example) A conventional standard wafer was used to verify whether anomalies could be detected only in the high-angle scattering detector of the particle counter (in the state before calibration in step S5 of the example) that was the object of control in the example. More specifically, the same steps as in the example were carried out as follows, except that a conventional standard wafer was used.

[0049] First, a silicon wafer coated with 32 to 100 nm of silica was prepared as a standard semiconductor silicon wafer. It was confirmed that this silica was spherical (a conventional standard wafer). Next, SP7 was used as a particle counter to check whether the device was working properly. ＸＰ Using a normal surface defect inspection device (that is, the same as that used in the examples), measurements were performed in oblique mode at 15 nm resolution, and scattered light generated by defects present on the outermost surface of the standard wafer was detected by detectors (a low-angle scattering detector and a high-angle scattering detector), and the coordinates and sizes of the defects were obtained (Step A: corresponds to Step S1 of the present invention, except that a conventional standard wafer was used).

[0050] Next, as a particle counter to be managed, SP7, which was evaluated in the example and found to have an abnormality in the optical system of the high-angle scattering detector, ＸＰ Measurement was performed in oblique mode / up to 15 nm using a standard wafer (before calibration in the examples), and scattered light generated by defects present on the outermost surface of the standard wafer was detected with detectors (a low-angle scattering detector and a high-angle scattering detector), and the coordinates and sizes of the defects were obtained (step B: corresponding to step S2 of the present invention).

[0051] Next, the coordinates of the defects detected in steps A and B were compared, and the difference in detected size between defects detected at the same coordinates was calculated for each detector (step C: corresponding to step S3 of the present invention). A frequency distribution curve was then created for the numerous detected size differences thus obtained, and the absolute value of the mode was obtained for each detector (step D: corresponding to step S4 of the present invention). The mode of detected size difference was 0 nm for all detectors. Therefore, although the particle counter actually had an abnormality only in the high-angle scattering detector, as verified in the example, the control method of this comparative example using a conventional standard wafer failed to detect an abnormality in the optical system because the detected size differences between the low-angle detector and the high-angle detector were equivalent (step E: corresponding to step S5 of the present invention).

[0052] Table 1 shows a summary of the absolute values ​​of the most frequent values ​​of the difference in detected size between the high-angle scattering detector and the low-angle scattering detector for the examples and comparative examples, as well as the magnitude relationship between them (absolute value of the difference in detected size in the high-angle scattering detector - absolute value of the difference in detected size in the low-angle scattering detector). As described above, in the examples embodying the present invention, an abnormality in only the high-angle scattering detector could be detected from the absolute value of the most frequent value of the difference in detected size, and appropriate inspection and calibration could be performed, but the conventional method using a standard wafer was unable to detect an abnormality in only the high-angle scattering detector.

[0053]

[0054] This specification includes the following aspects: [1]: A method for managing a surface defect inspection device that inspects surface defects on semiconductor silicon wafers, and that is equipped with a high-angle scattering detector and a low-angle scattering detector having a detection angle lower than that of the high-angle scattering detector as detectors, comprising: a standard wafer preparation step of preparing, as a standard wafer for managing the surface defect inspection device, a semiconductor silicon wafer that has a convex or concave shape whose dimension parallel to the wafer surface is greater than the dimension perpendicular to the wafer surface and that has a plurality of defects with known coordinates and sizes formed on its outermost surface; a defect detection step of using the surface defect inspection device to be managed to irradiate the surface of the standard wafer with a laser, detect scattered light generated by the defects present on the outermost surface of the standard wafer with the detector, and obtain the coordinates and sizes of the defects; and a size shift calculation step of comparing the known coordinates of the defects on the standard wafer with the coordinates of the defects detected in the defect detection step, and calculating, for defects with the same coordinates, a detected size difference, which is the difference between the known size on the standard wafer and the size detected in the defect detection step, for each detector. a mode acquisition step of acquiring, for each detector, the absolute value of the mode of the detected size difference from the calculated detected size difference, and an inspection and calibration step of inspecting and calibrating an optical system of the surface defect inspection device when the absolute value of the mode of the detected size difference in the high-angle scattering detector is greater than the absolute value of the mode of the detected size difference in the low-angle scattering detector. [2]: The surface defect inspection device management method according to [1] above, wherein, when acquiring the absolute value of the mode of the detected size difference in the mode acquisition step, a frequency distribution curve of the detected size difference is created and acquired. [3]: The surface defect inspection device management method according to [1] above, wherein, when preparing the standard wafer in the standard wafer preparation step, a semiconductor silicon wafer on which pits or PIDs are formed as the defects is prepared. [4]: A method for managing a surface defect inspection device according to any one of [1] to [3] above, wherein, in the standard wafer preparation step, when preparing the standard wafer, a semiconductor silicon wafer is prepared in which defects having a size of 100 nm or less are formed.[5]: A standard wafer for managing a surface defect inspection device, which is a semiconductor silicon wafer having a plurality of convex or concave defects formed on its outermost surface, the dimension parallel to the wafer surface being larger than the dimension perpendicular to the wafer surface. [6]: The standard wafer according to [5] above, wherein the defects are pits or PIDs. [7]: The standard wafer according to [5] or [6] above, wherein the defects are 100 nm or less in size.

[0055] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and that provides similar effects is included within the technical scope of the present invention.

Claims

1. A method for managing a surface defect inspection device that inspects surface defects on semiconductor silicon wafers and is equipped with a high-angle scattering detector and a low-angle scattering detector having a detection angle lower than that of the high-angle scattering detector as detectors, comprising: a standard wafer preparation step of preparing, as a standard wafer for managing the surface defect inspection device, a semiconductor silicon wafer that has a convex or concave shape whose dimension parallel to the wafer surface is greater than the dimension perpendicular to the wafer surface and has a plurality of defects with known coordinates and sizes formed on its outermost surface; a defect detection step of using the surface defect inspection device to be managed to irradiate the surface of the standard wafer with a laser, detect scattered light generated by the defects present on the outermost surface of the standard wafer with the detector, and obtain the coordinates and sizes of the defects; and a size shift calculation step of comparing the known coordinates of the defects on the standard wafer with the coordinates of the defects detected in the defect detection step, and calculating, for defects with the same coordinates, a detected size difference, which is the difference between the known size on the standard wafer and the size detected in the defect detection step, for each detector. A method for managing a surface defect inspection device, comprising: a mode acquisition step of acquiring, for each detector, the absolute value of the mode of the detected size difference from the calculated detected size difference; and an inspection and calibration step of inspecting and calibrating the optical system of the surface defect inspection device when the absolute value of the mode of the detected size difference in the high-angle scattering detector is greater than the absolute value of the mode of the detected size difference in the low-angle scattering detector.

2. A method for managing a surface defect inspection device as described in claim 1, characterized in that, in the mode acquisition process, when acquiring the absolute value of the mode of the detected size difference, a frequency distribution curve of the detected size difference is created and acquired.

3. The method for managing a surface defect inspection device according to claim 1, wherein, in the standard wafer preparation step, when preparing the standard wafer, a semiconductor silicon wafer having pits or PIDs formed thereon as the defects is prepared.

4. The method for managing a surface defect inspection device according to claim 2, wherein in the standard wafer preparation step, when preparing the standard wafer, a semiconductor silicon wafer having pits or PIDs formed thereon as the defects is prepared.

5. A method for managing a surface defect inspection device as described in any one of claims 1 to 4, characterized in that, in the standard wafer preparation process, when preparing the standard wafer, a semiconductor silicon wafer is prepared in which defects having a size of 100 nm or less are formed.

6. A standard wafer for controlling a surface defect inspection device, characterized in that it is a semiconductor silicon wafer having a plurality of convex or concave defects formed on its outermost surface, the dimension parallel to the wafer surface being greater than the dimension perpendicular to the wafer surface.

7. The standard wafer according to claim 6, wherein the defect is a pit or a PID.

8. A standard wafer according to claim 6 or claim 7, characterized in that the defects have a size of 100 nm or less.

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