Determination device and determination method for wafer
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SUMCO CORP
- Filing Date
- 2026-01-05
- Publication Date
- 2026-08-06
Smart Images
Figure JP2026000074_06082026_PF_FP_ABST
Abstract
Description
Wafer Determination Device and Determination Method
[0001] The present disclosure relates to a wafer determination device and a determination method.
[0002] As described in Patent Document 1, a method for detecting the presence or absence of specific defects in a wafer is known.
[0003] Japanese Patent Application Laid-Open No. 2017-106776
[0004] It is necessary to check the defect detection result of the wafer and determine whether the wafer is acceptable or not. When determining whether the wafer is acceptable or not by human visual inspection, the quality of the wafer may become unstable due to variations in the determination. In addition, the man-hours for visual determination increase. Stabilization of the quality of the wafer and reduction of the determination man-hours are required.
[0005] Therefore, an object of the present disclosure is to propose a wafer determination device and a determination method that can achieve stabilization of the quality of the wafer and reduction of the determination man-hours.
[0006] An embodiment of the present disclosure that solves the above problems is as follows: [1] A determination device comprising: an acquisition unit that acquires the location of defects detected from each of a plurality of wafers; and a determination unit that determines an abnormal pattern common to the plurality of wafers based on the location of the defects, wherein the determination unit generates a defect map by superimposing the locations of defects on the plurality of wafers, extracts unit sections containing defects at a density of a density threshold or higher from a plurality of unit sections set in the defect map as defect concentration sections, and determines the abnormal pattern based on the distribution of the defect concentration sections. [2] The determination device according to [1] above, wherein the determination unit divides the wafer into a plurality of rings in the radial direction and further divides each ring in the circumferential direction to set the plurality of unit sections, and determines whether the abnormal pattern includes a ring pattern based on a ring ratio which is the ratio of the number of defect concentration sections to the total number of unit sections in the same ring. [3] The determination device according to [2] above, wherein the determination unit determines whether the abnormal pattern is a ring pattern based on an adjacent ring ratio which is the ratio of the number of defect concentration sections to the total number of unit sections in at least two radially adjacent rings. [4] The determination device according to any one of [1] to [3] above, wherein the determination unit sets the plurality of unit sections by dividing the wafer into a grid, and determines that the abnormal pattern includes a concentration pattern when the number of connected defect concentration sections is equal to or greater than a set threshold. [5] The determination device according to any one of [1] to [4] above, wherein the determination unit sets the plurality of unit sections by dividing the wafer into a grid, and determines that the abnormal pattern includes a line pattern when the number of connected defect concentration sections along the axis of the grid is equal to or greater than a line threshold.[6] A determination method comprising: obtaining the location of defects detected from each of a plurality of wafers; generating a defect map by superimposing the defect locations of the plurality of wafers; extracting unit sections containing defects at a density equal to or greater than a density threshold from among a plurality of unit sections set in the defect map as defect concentration sections; and determining an abnormal pattern common to the plurality of wafers based on the distribution of the defect concentration sections.
[0007] According to the wafer determination apparatus and determination method described herein, stable wafer quality and a reduction in determination man-hours can be achieved.
[0008] This is a block diagram showing an example configuration of the judgment system according to this disclosure. This is a diagram showing an example of a defect pattern detected from a wafer. This is a diagram showing an example of a unit section set by dividing a wafer into rings. This is a diagram explaining the ring ratio. This is a diagram showing an example configuration of a handler. This is a diagram showing an example of the relationship between the suction pads of the handler in Figure 5 and the unit sections of the wafer. This is a diagram showing an example of a defect caused by the suction pads of the handler in Figure 5. This is a diagram showing an example of the relationship between defects in each wafer stacked in Figure 7A and the unit sections of the wafer. This is a diagram explaining the adjacent ring ratio. This is a diagram showing an example configuration of a handler with twice the number of suction pads. This is a diagram showing an example of the relationship between the suction pads of the handler in Figure 9 and the unit sections of the wafer. This is a diagram showing an example of a defect caused by the suction pads of the handler in Figure 9. This is a diagram showing an example of the relationship between defects in each wafer stacked in Figure 11A and the unit sections of the wafer. This is a diagram showing an example of a unit section set by dividing a wafer into a grid. This is a diagram explaining the number of connections of defect concentration sections. This is a diagram explaining the number of connections of defect concentration sections in the grid axis direction. This is a flowchart showing an example procedure of the judgment method according to this disclosure. This is a flowchart showing an example procedure for determining an abnormal pattern in a ring-shaped unit section. This is a flowchart showing an example procedure for determining an abnormal pattern in a grid-shaped unit section.
[0009] (Overview of Wafer Determination System 1) The wafer determination system 1 and determination apparatus 10 (see Figure 1) and determination method according to this disclosure detect the location of defects on the surface of a wafer, create a defect map by superimposing the locations of defects on the surfaces of multiple wafers, and detect abnormal patterns common to multiple wafers from the defect map. Hereinafter, the wafer determination system 1 and determination apparatus 10 according to one embodiment of this disclosure will be described with reference to the drawings.
[0010] (Example of the configuration of wafer determination system 1) As shown in Figure 1, wafer determination system 1 comprises a determination device 10, an inspection device 20, and a storage device 30. The inspection device 20 or the storage device 30 may be included in the determination device 10. The determination device 10, the inspection device 20, and the storage device 30 are connected in a communicative manner. Communication between the devices may be performed via a network or directly without a network.
[0011] <Inspection device 20> The inspection device 20 is configured to detect defects on the surface of a wafer. The wafer may include silicon wafers, etc. The wafer may also include polished wafers or epitaxial wafers, etc.
[0012] The inspection device 20 may be configured to detect defects on the wafer surface as bright spots by irradiating the wafer surface with light. The inspection device 20 may be configured to detect wafer defects and their in-plane distribution as bright spots by irradiating the wafer surface with light, detecting the reflected light from the wafer with an image sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) image sensor, and processing the difference in brightness detected by each pixel of the image sensor.
[0013] The inspection device 20 may be a laser scattering type surface inspection device. The laser scattering type surface inspection device may be configured to detect defects as bright spots by irradiating the surface of the wafer with a laser and detecting the scattered light from the surface of the wafer.
[0014] The inspection apparatus 20 generates a bright spot map for each wafer, representing the locations of bright spots detected as defects on the surface. The bright spot map may be information that represents the locations of bright spots within the wafer plane using wafer in-plane coordinates. The wafer in-plane coordinates are determined, for example, based on the location of a notch or orientation flat. The bright spot map may also be an image representing the distribution of bright spots detected as defects on the wafer surface.
[0015] The inspection device 20 may inspect all wafers included in one lot manufactured by the same wafer manufacturing device and generate a bright spot map for each wafer. One lot may consist of, for example, 200 wafers. The inspection device may also inspect all wafers included in one hoop and generate a bright spot map for each wafer. One hoop may contain 25 wafers.
[0016] <Storage device 30> The storage device 30 stores the detection results of defects on the surface of the wafer. The storage device 30 may also store a bright spot map of the wafer. The storage device 30 may be configured to include an electromagnetic storage medium such as a magnetic disk, or it may be configured to include a memory such as a semiconductor memory or magnetic memory.
[0017] <Determination device 10> The determination device 10 comprises an acquisition unit 12, a determination unit 14, and an output unit 16.
[0018] The acquisition unit 12 may include a communication device for sending and receiving information or data to and from other devices such as the inspection device 20 or the storage device 30. The communication device may be connected to other devices via a network to enable communication. The communication device may be connected to other devices via wired or wireless communication. The communication device may include a communication module that connects to a network or other devices. The communication module may include a communication interface such as a LAN (Local Area Network). The communication module may include a communication interface for contactless communication such as infrared communication or NFC (Near Field Communication). The communication module may implement communication using various communication methods such as 4G or 5G. The communication method implemented by the communication device is not limited to the examples described above and may include various other methods.
[0019] The determination unit 14 may include at least one processor. The processor may be a CPU (Central Processing Unit) or the like. The processor can execute programs that realize various functions of the determination unit 14. The processor may be implemented as a single integrated circuit. An integrated circuit is also called an IC (Integrated Circuit). The processor may be implemented as a plurality of communicably connected integrated circuits and discrete circuits. The processor may be implemented based on various other known technologies.
[0020] The determination unit 14 may further include a storage unit. The storage unit stores various information and programs executed by the determination unit 14. The storage unit may function as the work memory of the determination unit 14. The storage unit may store the detection results of wafer defects acquired by the acquisition unit 12, or the determination results by the determination unit 14. The storage unit may include an electromagnetic storage medium such as a magnetic disk, or a memory such as a semiconductor memory or magnetic memory. The storage unit may include a non-temporary computer-readable medium. At least a part of the storage unit may be configured separately from the determination unit 14.
[0021] The output unit 16 may include, for example, a display device that outputs visual information such as images, characters, or figures. The display device may include, for example, an LCD (Liquid Crystal Display), an organic EL (Electro-Luminescence) display, an inorganic EL display, or a PDP (Plasma Display Panel). The display device is not limited to these displays and may include various other types of displays. The display device may include a light-emitting device such as an LED (Light Emitting Diode) or an LD (Laser Diode). The display device may include various other devices. The output unit 16 may also include an audio output device such as a speaker.
[0022] The determination device 10 may include an input device that receives information or data from the user. The input device may include, for example, a touch panel or touch sensor, or a pointing device such as a mouse. The input device may also include physical keys. The input device may also include an audio input device such as a microphone.
[0023] (Example of operation of the determination device 10) In the determination device 10, the acquisition unit 12 acquires a bright spot map of defects on the surface of multiple wafers from the inspection device 20 or the storage device 30. The acquisition unit 12 may acquire the bright spot map directly from the inspection device 20, or it may acquire the bright spot map stored in the storage device 30 from the inspection device 20. In this example of operation, the acquisition unit 12 acquires the bright spot maps of multiple wafers included in the same lot or hoop as the bright spot maps of multiple wafers.
[0024] The determination unit 14 generates a defect map for each lot or hoop by superimposing the bright spot maps of multiple wafers included in the same lot or hoop. The determination unit 14 may accept input from the input device of the determination apparatus 10 specifying the wafers for which defect maps are to be created. The wafer specification may be accepted on a lot or hoop basis. The determination unit 14 may select wafers for which bright spot maps are to be superimposed according to the lot or hoop specification.
[0025] The defect map includes information on the locations of all bright spots detected on the surface of each of the multiple wafers. The defect map may also include information that identifies the location of the bright spots in wafer in-plane coordinates. The defect map may be displayed as an image plotting the distribution of defects 50 in the plane of wafer 40, as illustrated in Figure 2.
[0026] The determination unit 14 generates a defect map by superimposing the bright spot maps of multiple wafers with their in-plane coordinates aligned, that is, with the positions of notches or orientation flats aligned. The determination unit 14 may generate a defect map by superimposing the bright spot maps of all wafers included in one lot or one hoop.
[0027] As illustrated in Figure 2, defects 50 may be distributed in a specific pattern in the defect map. A pattern in which defects 50 are concentrated in one location is also called a concentrated pattern 51. A pattern in which defects 50 are arranged in a ring shape in the circumferential direction of the wafer is also called a ring pattern 52. A pattern in which defects 50 are arranged in a line is also called a line pattern 53. The concentrated pattern 51, ring pattern 52, and line pattern 53 are collectively referred to as abnormal patterns. Abnormal patterns are not limited to the patterns illustrated in Figure 2 and may include various other patterns.
[0028] The determination unit 14 determines the presence or absence of abnormal patterns from the defect map. In this disclosure, the determination unit 14 sets unit sections in the defect map in order to determine the presence or absence of abnormal patterns from the defect map. Unit sections are set by dividing the wafer area in the defect map. The determination unit 14 may set, for example, ring-shaped unit sections (see Figure 3) or grid-shaped unit sections (see Figure 12).
[0029] The determination unit 14 calculates the density of defects 50 in a unit section and extracts unit sections containing defects at a density above a density threshold as defect-concentrated sections. The density threshold is a value that can be set as appropriate, and may be set by, for example, the user of the determination system 1. The determination unit 14 may calculate the density of defects 50 in a unit section for the entire unit section, or it may calculate it for parts of the unit section where defects 50 are locally concentrated. In another embodiment, the determination unit 14 may calculate the number of defects 50 in a unit section and extract unit sections containing a number of defects above a defect count threshold as defect-concentrated sections. The defect count threshold is a value that can be set as appropriate, and may be set by, for example, the user of the determination system 1. The determination unit 14 is not limited to these examples and may extract defect-concentrated sections under various conditions.
[0030] The determination unit 14 determines the presence or absence of an abnormal pattern based on the extraction results of defect concentration areas in the defect map. The determination unit 14 may determine the presence or absence of an abnormal pattern based on the number of defect concentration areas extracted from the defect map, the ratio of the number of defect concentration areas to the total number of unit areas, or the location or arrangement of the defect concentration areas.
[0031] The determination unit 14 may estimate the cause of an abnormal pattern if one is found. The cause of the abnormal pattern may be an abnormality in the wafer manufacturing equipment or noise in the inspection device 20. The wafer manufacturing equipment includes wafer cleaning equipment, polishing equipment, or furnaces. An abnormality in the wafer manufacturing equipment includes equipment failure or contamination.
[0032] The output unit 16 outputs the result of the determination unit 14's determination of whether or not an abnormal pattern is present. The output unit 16 may display the result of whether or not an abnormal pattern was found in the defect map as text or an image. The output unit 16 may also superimpose text, graphics, images, characters, or symbols indicating the abnormal pattern onto the defect map. The output unit 16 may notify whether or not an abnormal pattern was found in the defect map by lighting a lamp or outputting sound.
[0033] The following describes in detail the operation of the determination unit 14 in determining abnormal patterns, divided into cases where the unit section is set in a ring shape and cases where it is set in a grid shape.
[0034] <Determination using ring-shaped unit sections> In this example of operation, the determination unit 14 divides the surface of the wafer 40 into ring shapes and sets up unit sections, as illustrated in Figure 3.
[0035] The determination unit 14 first divides the wafer 40 into five rings in the radial direction in order to set up ring-shaped unit sections. The number of rings to be divided into is not limited to five; it may be four or fewer, or six or more. In this example of operation, the five rings are divided by the same length in the radial direction, but the radial lengths of some of the rings may differ.
[0036] The determination unit 14 divides each ring in the circumferential direction. In the example in Figure 3, the outermost ring is divided into 16 unit sections 41A to 41P. The ring one position inward from the outermost ring, i.e., the second ring, is divided into 12 unit sections 42A to 42L. The ring two positions inward from the outermost ring, i.e., the third ring, is divided into 8 unit sections 43A to 43H. The ring three positions inward from the outermost ring, i.e., the fourth ring, is divided into 4 unit sections 44A to 44D. The ring four positions inward from the outermost ring, i.e., the central ring, is one unit section 45. When the ring is divided in the circumferential direction, it may be divided such that the inscribed angles of each section are equal. The ring may also be divided such that the inscribed angles of some sections are different.
[0037] The determination unit 14 extracts defect-concentrated areas from the ring-shaped unit sections set in the defect map. For example, as shown in Figure 4, the unit sections 42E to 42H in the second cycle and the unit sections 44A to 44C in the fourth cycle are extracted as defect-concentrated areas.
[0038] <<Determination by Ring Ratio>> The determination unit 14 calculates a ring ratio that represents the proportion of the inscribed angle occupied by the defect concentration area in one ring. In the example in Figure 4, the ring ratio for the second rotation is calculated as 33% by calculating 120 degrees / 360 degrees. The ring ratio for the fourth rotation is calculated as 75% by calculating 270 degrees / 360 degrees. The determination unit 14 may also calculate the ring ratio as the ratio of the number of defect concentration areas to the number of unit areas in one ring. If the inscribed angles of the unit areas divided in the circumferential direction of the ring are equal, the ring ratio calculated as the proportion of the number of defect concentration areas will match the ring ratio calculated as the proportion of the inscribed angles. In the example in Figure 4, the ring ratio for the second rotation is calculated as 33% by calculating 4 / 12. The ring ratio for the fourth rotation is calculated as 75% by calculating 3 / 4.
[0039] The determination unit 14 may determine that there is an abnormal ring pattern in a ring whose ring ratio is equal to or greater than the ring threshold. The ring threshold is a value that can be set as appropriate, and may be set, for example, by the user of the determination system 1. If the ring threshold is set to 30%, the determination unit 14 will determine from the extraction results of the defect concentration areas illustrated in Figure 4 that there is an abnormal ring pattern in both the second and fourth rings. If the ring threshold is set to 40%, the determination unit 14 will determine from the extraction results of the defect concentration areas illustrated in Figure 4 that there is no abnormal pattern in the second ring, and that there is an abnormal ring pattern in the fourth ring.
[0040] Ring patterns can appear as a common abnormal pattern in wafers within the same lot or hoop processed by the same wafer manufacturing equipment when wafers are processed in a circumferentially rotated position in wafer manufacturing equipment, i.e., when the position of the wafer's notch or orientation flat is uncertain.
[0041] For example, as shown in Figure 5, if a handler 60 for transporting wafers in a wafer manufacturing apparatus has suction pads 61 to 64, defects may occur on the wafer surface in areas where the suction pads 61 to 64 come into contact. For example, as shown in Figure 6, the areas in contact with the suction pads 61 to 64 correspond to unit sections 42B, 42E, 42H, and 42K of the second ring. If defects occur in all areas in contact with the suction pads 61 to 64, unit sections 42B, 42E, 42H, and 42K of the second ring are extracted as defect-concentrated areas. In this case, the ring ratio for the second ring is calculated as 33% by calculating 120 degrees / 360 degrees. The determination unit 14 can determine the defects caused by contact with the suction pads 61 to 64 as a ring pattern by setting the ring threshold to, for example, 30%.
[0042] If the position of the wafer's notch or orientation flat is uncertain, the position of the defect concentration area caused by contact with the suction pads 61-64 rotates in the circumferential direction. Therefore, if the determination unit 14 simply designates an area corresponding to the portion of the wafer that the suction pads 61-64 contact, and attempts to detect defects caused by the suction pads 61-64 on the condition that the designated area is a defect concentration area, defects that occur on the wafer that come into contact with the suction pads 61-64 while the notch or orientation flat is rotated will not be detected. In this disclosure, by using the ring ratio for determination, it becomes easier to determine abnormal patterns that include defects that can move in the circumferential direction due to the rotation of the wafer's notch or orientation flat.
[0043] As shown in FIGS. 7A and 7B, a defect map was created by overlapping the positions of defects 50 that occurred on each of the four wafers 40 adsorbed by the handler 60 of the same wafer manufacturing apparatus. FIG. 7A is a diagram showing the positions of defects 50 in each of the four wafers 40 before overlapping. FIG. 7B is a defect map obtained by overlapping the positions of defects 50 in each of the four wafers 40 of FIG. 7A. In the examples of FIGS. 7A and 7B, it is assumed that the defect 50 occurred only in a portion corresponding to one of the adsorption pads 61 to 64. In the defect map, the defect 50 is located in the unit sections 42D, 42E, 42G, and 42I of the second ring. In this case, the ring ratio is calculated as 120 degrees / 360 degrees and is calculated to be 33%. If the abnormal pattern is determined only from the position of the defect 50 that occurred in one wafer 40, since the defect 50 occurred only in the portion where one of the adsorption pads 61 to 64 contacted, the ring ratio is calculated as a small value, and it is difficult to determine whether there is a ring pattern due to the contact of the adsorption pads 61 to 64. However, by calculating the ring ratio of the defect map obtained by overlapping the positions of the defects 50 of a plurality of wafers 40, even if the defect 50 occurred only in the portion where one of the adsorption pads 61 to 64 contacted, it can be determined whether the defect 50 is caused by the contact of any of the adsorption pads 61 to 64.
[0044] <<Determination by Adjacent Ring Ratio>> The determination unit 14 calculates an adjacent ring ratio that represents the ratio of the circumferential angle occupied by the defect concentration section in two or more adjacent rings. For example, as shown in FIG. 8, it is assumed that the unit sections 42D, 42F, and 42G of the second ring, and the unit sections 43B and 43D of the third ring are extracted as the defect concentration sections. In this case, the angle occupied by the defect concentration section is calculated by referring to Table 1 below.
[0045]
[0046] In Table 1, "Ring 1" corresponds to the second ring, and "Ring 2" corresponds to the third ring. Numbers 1 to 12 in the "Section Number" of "Ring 1" correspond to unit sections 42A to 42L of the second ring. Numbers 1 to 8 in the "Section Number" of "Ring 2" correspond to unit sections 43A to 43H of the third ring. Cells in the "Defect" row of "Ring 1" and "Ring 2" are painted black to indicate that the unit section corresponding to that cell is a defect concentration section. "Angle" represents the angular range in the circumferential direction occupied by each unit section, with the circumferential angle at the boundary between unit sections 42A and 42L being set as 0 degrees.
[0047] In the second ring, that is, "Ring 1", unit section 42D occupies the range from 90 degrees to 120 degrees, and unit sections 42F and 42G occupy the range from 150 degrees to 210 degrees. In the third ring, that is, "Ring 2", unit section 43B occupies the range from 45 degrees to 90 degrees, and unit section 43D occupies the range from 135 degrees to 180 degrees.
[0048] The determination unit 14 calculates the ratio of the circumferential angle occupied by the defect concentration section in adjacent second and third rings as the adjacent ring ratio. Specifically, in the second ring, that is, "Ring 1", the angular range occupied by the defect concentration section corresponding to the cell represented by black painting in the "Defect" row is the range from 45 degrees to 120 degrees. Also, in the third ring, that is, "Ring 2", the angular range occupied by the defect concentration section corresponding to the cell represented by black painting in the "Defect" row is the range from 135 degrees to 210 degrees. Therefore, in the example of FIG. 8 and Table 1, the adjacent ring ratio of the second and third rings is calculated as {(120 degrees - 45 degrees) + (210 degrees - 135 degrees)} / 360 degrees and is determined to be 41.7%.
[0049] The determination unit 14 may determine that there is an abnormal pattern in the ring pattern for a ring where the adjacent ring ratio is equal to or greater than the adjacent ring threshold. The adjacent ring threshold is a value set as appropriate and may be set by the user of the determination system 1, for example. If the adjacent ring threshold is set to 30%, the determination unit 14 determines that there is an abnormal pattern in the ring pattern for the second and third rings based on the extraction result of the defect concentration section illustrated in FIG. 8.
[0050] If the ring ratio were calculated independently for each of the second and third rings, the ring ratios for the second and third rings would be 25%, meaning that a ring pattern would not be detected when the ring threshold is set to 30%. If the ring threshold were lowered to a lower value to detect a ring pattern based on the distribution of defect concentration areas in Figure 8, the likelihood of misidentifying a ring pattern would increase. By using the adjacent ring ratio, the accuracy of ring pattern detection can be improved without affecting the determination based on the ring ratio.
[0051] For example, as shown in Figure 9, if a wafer handling device has outer suction pads 61-64 and inner suction pads 65-68, defects may occur on the wafer surface in areas where the suction pads 61-68 are in contact. For example, as shown in Figure 10, the areas in contact with suction pads 61 and 63 correspond to unit sections 42B and 42H of the second ring, and the areas in contact with suction pads 66 and 68 correspond to unit sections 43C and 43G of the third ring. If defects occur in areas where suction pads 61, 63, 66, and 68 are in contact, unit sections 42B and 42H of the second ring, and unit sections 43C and 43G of the third ring are identified as defect-concentrated areas. In this case, the adjacent ring ratio of the second and third rings is calculated as 41.7% by calculating (30 degrees + 45 degrees + 30 degrees + 45 degrees) / 360 degrees. The determination unit 14 can determine that there is an abnormal ring pattern in the second and third rings.
[0052] Let's assume that when a defect occurs in the area where the suction pads 61, 63, 66, and 68 make contact, the abnormal pattern is determined solely by the ring ratio. In this case, the ring ratio for the second pass is calculated as 16.7% by (30 degrees + 30 degrees) / 360 degrees. Similarly, the ring ratio for the third pass is calculated as 25% by (45 degrees + 45 degrees) / 360 degrees. If the ring threshold is set to 30%, it will be determined that there is no ring pattern in either the second or third pass. As demonstrated in this example, by using the adjacent ring ratio, it becomes possible to determine the presence of a ring pattern without changing the ring threshold.
[0053] As shown in Figures 11A and 11B, a defect map was created by superimposing the locations of defects 50 that occurred on each of the four wafers 40 that were adsorbed onto the handler 60 of the same wafer manufacturing apparatus. Figure 11A is a diagram showing the locations of defects 50 on each of the four wafers 40 before superimposition. Figure 11B is a defect map superimposed on the locations of defects 50 on each of the four wafers 40 in Figure 11A. In the example of Figures 11A and 11B, it is assumed that the defects 50 occurred in the part corresponding to only one of the adsorption pads 61 to 68. In the defect map, the defects 50 are located in the unit sections 42E and 42G of the second ring, and in the unit sections 43B and 43F of the third ring. In this case, the adjacent ring ratio is calculated as 41.7% by calculating (30 degrees + 30 degrees + 45 degrees + 45 degrees) / 36 degrees. If the ring ratio for the second and third passes were calculated separately, the calculated ring ratio would be small, making it difficult to determine whether there is a ring pattern caused by contact between the suction pads 61-68. However, by calculating the adjacent ring ratio of a defect map created by superimposing the locations of defects 50 on multiple wafers 40, it is possible to determine whether the defect 50 is caused by contact between any of the suction pads 61-68, even if the defect 50 occurs only in the area where one of the suction pads 61-68 has made contact.
[0054] <<Summary of determination using ring-shaped unit sections>> As described above, the determination unit 14 can determine the presence or absence of a ring pattern using ring-shaped unit sections. The determination unit 14 can also determine the presence or absence of an abnormal pattern using the ring ratio. By using the ring ratio, equipment-related defects can be detected even when the wafer rotates in the circumferential direction. The determination unit 14 can also determine the presence or absence of an abnormal pattern using the adjacent ring ratio. By using the adjacent ring ratio, the radial division width when setting the ring-shaped unit sections can be reduced while determining the presence or absence of an abnormal pattern distributed over a wide area in the radial direction.
[0055] <Determination using a grid-like unit section> In this example of operation, the determination unit 14 divides the surface of the wafer 40 into a grid and sets up unit sections 46, as illustrated in Figure 12. In this example of operation, the axes of the grid are set to be orthogonal, but they may also be set to intersect at an angle of less than 90 degrees. In this example of operation, the surface of the wafer 40 is divided into 10 grids vertically and 10 grids horizontally. The number of vertical divisions and the number of horizontal divisions may be different. The number of grid divisions is not limited to 10; it may be 9 or less, or 11 or more.
[0056] The determination unit 14 extracts defect concentration areas from the grid-like unit areas set in the defect map. For example, as shown in Figure 13, let's assume that unit areas 46A to 46G are extracted as defect concentration areas.
[0057] The determination unit 14 treats multiple defect concentration areas as a single set when they are connected. For example, in Figure 13, unit areas 46B to 46D and unit areas 46E to 46G are each treated as a single set. In this example of operation, defect concentration areas are also considered connected if they are connected diagonally. In another embodiment, areas may be considered connected only if they are adjacent vertically or horizontally.
[0058] The determination unit 14 may determine that an abnormal pattern of the set exists in a set whose number of connected sets is equal to or greater than the set threshold. The number of connected sets is the number of defect concentration areas included in one set. The set threshold is a value that is set as appropriate, and may be set, for example, by the user of the determination system 1. If the set threshold is set to 3, the determination unit 14 will determine that there is an abnormal pattern of the set in each of the unit areas 46B to 46D and unit areas 46E to 46G as illustrated in Figure 13.
[0059] The determination unit 14 may determine that there is an abnormal line pattern in a set whose number of connections in the axial direction of the set is equal to or greater than the line threshold. The number of connections in the axial direction of the set is the number of defect concentration areas connected in the direction along the axis of the grid used to set the grid-like unit area 46. The line threshold is a value that is set as appropriate, and may be set, for example, by the user of the determination system 1.
[0060] For example, suppose that unit sections 46H to 46N are extracted as defect-concentrated sections, as shown in Figure 14. In the example in Figure 14, unit sections 46H to 46K and unit sections 46L to 46N are each treated as a single set. The set containing unit sections 46H to 46K has 3 connections in the vertical direction and 2 connections in the horizontal direction. The set containing unit sections 46L to 46N also has 2 connections in the vertical direction and 2 connections in the horizontal direction. If the line threshold is set to 3, the determination unit 14 determines that there is an abnormal line pattern in unit sections 46H to 46K as illustrated in Figure 14.
[0061] The determination unit 14 may determine abnormal patterns for both the group pattern and the line pattern. For example, in Figure 14, the determination unit 14 may determine that the group containing the unit sections 46H to 46K has abnormal patterns for both the group pattern and the line pattern.
[0062] <<Summary of determination using grid-like unit sections>> As described above, the determination unit 14 can determine the presence or absence of cluster patterns and line patterns using grid-like unit sections.
[0063] <Use of the results of the determination of the presence or absence of abnormal patterns> The results of the determination of the presence or absence of abnormal patterns may be used to determine whether the wafers contained in a lot or hoop are acceptable or unacceptable. A lot or hoop containing abnormal patterns may be determined to be unacceptable. Even if abnormal patterns are present, a lot or hoop may be determined to be acceptable or unacceptable depending on the type of abnormal pattern.
[0064] The results of the determination of whether or not abnormal patterns are present may be used to determine maintenance of the wafer manufacturing equipment. If it is determined that there are abnormal patterns caused by a malfunction in the wafer manufacturing equipment, maintenance of the wafer manufacturing equipment suspected to be the cause of those abnormal patterns may be determined.
[0065] If the determination unit 14 determines that an abnormal pattern exists, it may estimate the cause of the abnormal pattern. For example, the determination unit 14 may estimate whether the cassette is the cause of the concentrated pattern by associating the position of the support part of the cassette that houses the wafer with the position of the concentrated pattern. The determination unit 14 may estimate whether the furnace is the cause of the concentrated pattern by associating the position of the gas inlet and outlet of the furnace with the position of the concentrated pattern. The determination unit 14 may estimate whether the grinding device is the cause of the ring pattern by associating the position of the grinding wheel of the grinding device with the position of the ring pattern. The determination unit 14 may estimate whether the hand is the cause of the ring pattern by associating the position where the wafer is picked up by a hand when transporting the wafer with a polishing device or grinding device, etc., with the position of the ring pattern. The determination unit 14 may estimate whether the hand of the device is the cause of the line pattern by associating the position where the hand of the device moves linearly with the position of the line pattern.
[0066] The determination unit 14 may estimate the cause of an abnormal pattern from its location using a table that associates the location of the abnormal pattern with the cause of the abnormal pattern. Alternatively, the determination unit 14 may estimate the cause of an abnormal pattern using a trained model generated by performing training using training data that associates the location of the abnormal pattern with the cause of the abnormal pattern.
[0067] <Example of a determination method procedure> The determination unit 14 of the determination device 10 may execute a determination method that includes the procedure of the flowchart illustrated in Figure 15. The determination method may be implemented as a determination program to be executed by the processor constituting the determination unit 14. The determination program may be stored in a non-temporary computer-readable medium.
[0068] The determination unit 14 obtains the inspection results for wafer defects from the acquisition unit 12 (step S1). The determination unit 14 may obtain a bright spot map for each wafer as an inspection result for wafer defects. The determination unit 14 may obtain the bright spot map from the inspection device 20 or from the bright spot map stored in the storage device 30. The determination unit 14 selects the wafer on which to superimpose the defects (step S2). The determination unit 14 generates a defect map by superimposing the bright spot maps of the selected wafers (step S3).
[0069] The determination unit 14 sets unit sections in the defect map and extracts defect concentration areas (step S4). The determination unit 14 determines an abnormal pattern based on the extraction results of defect concentration areas (step S5). In steps S4 and S5, the determination unit 14 may set ring-shaped unit sections in the defect map and determine whether there is a ring pattern abnormality, or it may set grid-shaped unit sections in the defect map and determine whether there is a cluster pattern and a line pattern abnormality. The determination unit 14 may perform both the process of setting ring-shaped unit sections and determining whether there is an abnormal pattern, and the process of setting grid-shaped unit sections and determining whether there is an abnormal pattern.
[0070] The determination unit 14 outputs a determination result of whether there is an abnormal pattern in the defect map via the output unit 16 (step S6). The output unit 16 may display the presence or absence of an abnormal pattern superimposed on the defect map. The output unit 16 may display the presence or absence of an abnormal pattern alone. The output unit 16 may output the presence or absence of an abnormal pattern by lighting a lamp or by sound. After executing the procedure in step S6, the determination unit 14 terminates the execution of the flowchart in Figure 15.
[0071] When the determination unit 14 sets a ring-shaped unit section in steps S4 and S5 of Figure 15 and determines whether or not there is an abnormal pattern, it may execute a determination method that includes the steps of the flowchart illustrated in Figure 16.
[0072] The determination unit 14 sets a ring-shaped unit section in the defect map (step S11). The determination unit 14 extracts defect concentration areas from the ring-shaped unit section (step S12).
[0073] The determination unit 14 calculates the ring ratio for each of the multiple rings in the defect map and determines whether the ring ratio is equal to or greater than the ring threshold (step S13). If the determination unit 14 determines that the ring ratio is equal to or greater than the ring threshold (step S13: YES), it proceeds to step S15.
[0074] If the ring ratio is not equal to or greater than the ring threshold (step S13: NO), that is, if the ring ratio is less than the ring threshold, the determination unit 14 calculates the adjacent ring ratio and determines whether the adjacent ring ratio is equal to or greater than the adjacent ring threshold (step S14).
[0075] If the adjacent ring ratio is not equal to or greater than the adjacent ring threshold (step S14: NO), that is, if the adjacent ring ratio is less than the adjacent ring threshold, the determination unit 14 does not determine that there is a ring pattern and terminates the procedure in the flowchart of Figure 16. The determination unit 14 may determine that there is no abnormal ring pattern if both the ring ratio being less than the ring threshold and the adjacent ring ratio being less than the adjacent ring threshold are met. The determination unit 14 may also determine that there is no abnormal ring pattern if at least one of the following is met: the ring ratio is equal to or greater than the ring threshold, or the adjacent ring ratio is equal to or greater than the adjacent ring threshold.
[0076] The determination unit 14 determines that there is an abnormal ring pattern in the defect map (step S15) if the ring ratio is greater than or equal to the ring threshold (step S13: YES), or if the adjacent ring ratio is greater than or equal to the adjacent ring threshold (step S14: YES). The determination unit 14 may determine that there is an abnormal ring pattern if at least one of the following conditions is met: the ring ratio is greater than or equal to the ring threshold, or the adjacent ring ratio is greater than or equal to the adjacent ring threshold. The determination unit 14 may also determine that there is an abnormal ring pattern if both the ring ratio is greater than or equal to the ring threshold and the adjacent ring ratio is greater than or equal to the adjacent ring threshold are met. After executing the procedure in step S15, the determination unit 14 terminates the execution of the flowchart in Figure 16.
[0077] The determination unit 14 may execute the determination procedure of step S13 first and then the determination procedure of step S14, or it may execute the determination procedure of step S14 first and then the determination procedure of step S13. In other words, the order in which the determination unit 14 executes steps S13 and S14 may be changed as appropriate.
[0078] The determination unit 14 does not have to perform the procedure in step S14 regardless of the determination result of the procedure in step S13. In other words, the determination unit 14 may determine whether or not there is an abnormal ring pattern by only performing the determination of whether the ring ratio is less than the ring threshold, without performing the determination of whether the adjacent ring ratio is less than the adjacent ring threshold.
[0079] The determination unit 14 does not have to perform the procedure in step S13 regardless of the determination result of the procedure in step S14. In other words, the determination unit 14 may determine whether or not there is an abnormal ring pattern by only performing a determination of whether the adjacent ring ratio is less than the adjacent ring threshold, without performing a determination of whether the ring ratio is less than the ring threshold.
[0080] When the determination unit 14 sets up a grid-like unit section in steps S4 and S5 of Figure 15 and determines whether or not there is an abnormal pattern, it may execute a determination method that includes the steps of the flowchart illustrated in Figure 17.
[0081] The determination unit 14 sets up a grid-like unit area in the defect map (step S21). The determination unit 14 extracts defect concentration areas from the grid-like unit area (step S22).
[0082] The determination unit 14 determines the sets of connected defect concentration areas and determines whether the number of connected sets is greater than or equal to the set threshold (step S23). If the number of connected sets is greater than or equal to the set threshold (step S23: YES), the determination unit 14 determines that there is an abnormal set pattern in the defect map (step S24) and proceeds to step S25. If the number of connected sets is not greater than or equal to the set threshold (step S23: NO), that is, if the number of connected sets is less than the set threshold, the determination unit 14 does not determine that there is an abnormal set pattern and proceeds to step S25.
[0083] The determination unit 14 determines whether the number of connections in the axial direction is equal to or greater than the line threshold (step S25). If the number of connections in the axial direction is equal to or greater than the line threshold (step S25: YES), the determination unit 14 determines that there is an abnormal line pattern in the defect map (step S26) and terminates the execution of the flowchart in Figure 17. If the number of connections in the axial direction is not equal to or greater than the line threshold (step S25: NO), that is, if the number of connections in the axial direction is less than the line threshold, the determination unit 14 terminates the execution of the flowchart in Figure 17 without determining that there is an abnormal line pattern.
[0084] (Summary) As described above, the determination system 1, determination device 10, and determination method relating to this disclosure determine whether or not there is an abnormal pattern in the defect map obtained by superimposing defects on the surfaces of multiple wafers. This reduces the man-hours required for human determination work. Furthermore, because the determination is performed by the device, the variability of the determination results is reduced compared to human determination. This reduction in variability of the determination results improves the accuracy of wafer pass / fail determination. As a result, wafer quality becomes more stable.
[0085] As described above, if the detection results of defects in workpieces such as wafers become stable, the quality of workpieces such as wafers will become stable, and the yield when manufacturing devices from workpieces such as wafers can be improved. Improved yield makes it possible to increase the manufacturing efficiency of semiconductor products and produce more high-quality products, thereby promoting technological innovation and contributing to the sustainable development of industry. Improved yield also contributes to the efficient use of resources by reducing the waste of materials consumed in the semiconductor product manufacturing process. Furthermore, improved yield reduces the waste of energy consumed in the semiconductor product manufacturing process, and as a result contributes to the reduction of greenhouse gas emissions. In other words, the judgment system 1, judgment device 10, and judgment method relating to this disclosure can contribute, for example, to Sustainable Development Goals (SDGs) "Goal 9: Build industry, innovation and infrastructure," "Goal 12: Ensure sustainable consumption and production," or "Goal 13: Address climate change."
[0086] While embodiments relating to this disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can make various modifications or alterations based on this disclosure. Therefore, it should be noted that these modifications or alterations are included within the scope of this disclosure. For example, the functions included in each component or step can be rearranged in a logically consistent manner, and multiple components or steps can be combined into one or divided. While embodiments relating to this disclosure have been described primarily in terms of apparatus, embodiments relating to this disclosure can also be realized as methods including steps performed by each component of the apparatus. Embodiments relating to this disclosure can also be realized as methods, programs, or storage media recording programs executed by a processor in the apparatus. It should be understood that these are also included within the scope of this disclosure.
[0087] According to the embodiments described herein, wafer quality stability and the amount of processing time required for evaluation are achieved.
[0088] 1. Judgment system (10: Judgment device, 12: Acquisition unit, 14: Judgment unit, 16: Output unit, 20: Inspection device, 30: Storage device) 40. Wafer (41A-41P: Outermost section, 42A-42L: Second section, 43A-43H: Third section, 44A-44D: Fourth section, 45: Central section, 46, 46A-46N: Grid-like section) 50. Defects (51: Concentrated pattern, 52: Ring pattern, 53: Line pattern) 60. Handler (61-68: Suction pads)
Claims
1. A determination device comprising: an acquisition unit that acquires the location of defects detected from each of a plurality of wafers; and a determination unit that determines an abnormal pattern common to the plurality of wafers based on the location of the defects, wherein the determination unit generates a defect map by superimposing the locations of the defects of the plurality of wafers, extracts unit sections containing defects at a density above a density threshold from among a plurality of unit sections set in the defect map as defect concentration sections, and determines the abnormal pattern based on the distribution of the defect concentration sections.
2. The determination device according to claim 1, wherein the determination unit divides the wafer into a plurality of rings in the radial direction, further divides each ring in the circumferential direction to set the plurality of unit sections, and determines whether the abnormal pattern includes a ring pattern based on the ring ratio, which is the ratio of the number of defect concentration sections to the total number of unit sections in the same ring.
3. The determination device according to claim 2, wherein the determination unit determines whether the abnormal pattern is a ring pattern based on the adjacent ring ratio, which is the ratio of the number of defect concentration areas to the total number of unit areas of at least two radially adjacent rings.
4. The determination device according to claim 1, wherein the determination unit sets the plurality of unit sections by dividing the wafer into a grid, and determines that the abnormal pattern includes a concentration pattern when the number of connected defect concentration sections is equal to or greater than a set threshold.
5. The determination device according to claim 1, wherein the determination unit sets the plurality of unit sections by dividing the wafer into a grid, and determines that the abnormal pattern includes a line pattern when the number of defect concentration sections connected along the grid axis is equal to or greater than a line threshold.
6. A determination method comprising: obtaining the location of defects detected from each of a plurality of wafers; generating a defect map by superimposing the defect locations of the plurality of wafers; extracting unit sections containing defects at a density equal to or greater than a density threshold from among a plurality of unit sections set in the defect map as defect concentration sections; and determining an abnormal pattern common to the plurality of wafers based on the distribution of the defect concentration sections.