JP2008021967A - Inspection method and inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method capable of more easily identifying a facility in question.
(A) For each of a plurality of manufacturing facilities for processing a substrate to be processed, a pattern of a region in which the manufacturing facility exerts a mechanical action or an electrical action on the back surface of the substrate to be processed is referred to as the manufacturing equipment. Correspondingly, it is prepared in advance as a back surface action pattern. (B) A distribution pattern of defects generated on the back surface of the substrate to be processed processed by at least some of the plurality of manufacturing facilities is acquired. (C) By collating the defect distribution pattern acquired in step b with the back-surface action pattern prepared in advance, the manufacturing facility that caused the defect is specified.
[Selection] Figure 6

Description

  The present invention relates to an inspection method and an inspection apparatus that can easily identify an apparatus in which a problem has occurred in a production line including a plurality of facilities for processing a substrate to be processed.

  Semiconductor wafers, liquid crystal panels, and the like are manufactured through a number of processing steps. Each process is executed by a plurality of facilities. The product is inspected for each of a plurality of series of processes. In this inspection, if an abnormality is detected, it is necessary to identify the equipment that caused the abnormality and take measures such as removing the equipment from the production line.

  Patent Document 1 below discloses a method for specifying a process that causes an abnormality when a product abnormality is detected. Hereinafter, a method for identifying this problem process will be described.

  The processed semiconductor wafer is inspected by an in-line inspection apparatus. Moreover, a manufacturing apparatus is evaluated for every apparatus by a faceplate inspection apparatus. Product inspection information obtained by the in-line inspection device and manufacturing device evaluation information obtained by the face plate inspection device are transferred to the upper database and stored for a certain period.

  When an abnormality of the product wafer is detected by the in-line inspection apparatus, information necessary for identifying the problem process is downloaded from the upper database. Using the downloaded information, a problem process is specified by performing any one of the apparatus evaluation information collation analysis, common path analysis, machine difference analysis, apparatus log correlation analysis, or a combination thereof.

  The host database includes device evaluation information, product inspection information, manufacturing route information, and device log / maintenance information. The apparatus evaluation information includes defect appearance information of the face plate wafer and defect composition information obtained by Auger analysis or the like. The product inspection information includes position information such as pattern defects, scratches, and foreign matters acquired by the appearance inspection apparatus.

  Next, the problem process identification method disclosed in Patent Document 2 below will be described. When an abnormality is detected in a product, the product having the same problem and the product in which the same problem has not occurred are searched from the product inspection information for a predetermined period in the same inspection process as that product. . A device that processes a product having the same problem in common and does not process a product having no problem is extracted as a candidate for the problem device.

JP 2004-253603 A JP 2005-197629 A

  An object of the present invention is to provide an inspection method that can more easily identify a facility in question. Another object of the present invention is to provide an inspection apparatus used in this method.

According to one aspect of the invention,
(A) For each of a plurality of manufacturing facilities for processing a substrate to be processed, a pattern of a region in which the manufacturing facility exerts a mechanical action or an electrical action on the back surface of the substrate to be processed is associated with the manufacturing facility, A step of preparing as a backside action pattern in advance;
(B) obtaining a distribution pattern of defects generated on the back surface of the processing target substrate processed by at least some of the plurality of manufacturing facilities;
(C) a step of identifying the manufacturing facility that caused the defect by collating the defect distribution pattern acquired in the step (b) with the back surface action pattern prepared in advance; An inspection method is provided.

According to another aspect of the invention,
For each of the plurality of manufacturing facilities for processing the substrate to be processed, back surface action pattern storage means for storing a pattern of a region in which the manufacturing facility exerts a mechanical action or an electrical action on the back surface of the processing target substrate;
A defect distribution pattern detecting means for acquiring a distribution pattern of defects generated on the back surface of the substrate to be processed processed by at least some of the plurality of manufacturing facilities;
The defect distribution pattern detected by the defect distribution pattern detection means is compared with the back face action pattern stored in the back face action pattern storage means, and the defect is caused based on the check result. There is provided an inspection apparatus having collation means for specifying a manufacturing facility.

  The distribution pattern of defects generated on the back surface of the substrate to be processed is unique to the equipment. For this reason, it is possible to easily identify the equipment that caused the defect by preparing a pattern unique to the equipment as a back-surface action pattern and comparing the actual defect distribution pattern with the back-surface action pattern. Can do.

  FIG. 1 shows an example of a block diagram of a production line. For example, a certain semiconductor wafer is passed to the next process through the process A, the process B, and the process C. In step A, the semiconductor wafer is processed in turn by four facilities A1 to A4. In the process B, the semiconductor wafer is processed in order by four equipments of equipments B1 to B4. Examples of the processes A and B include a chemical vapor deposition (CVD) process, an etching process, a lithography process, an ion implantation process, and a chemical mechanical polishing (CMP) process. For example, the equipment for performing the etching process includes an etching apparatus, an ashing apparatus, a wet cleaning apparatus, and the like.

  The semiconductor wafer that has completed the process B is delivered to the inspection apparatus 10. The inspection device 10 includes a defect distribution pattern detection device 1, a verification device 2, and a back surface action pattern storage device 3. The semiconductor wafer inspected by the inspection apparatus 10 is delivered to the next process C.

  With reference to FIG. 2A, FIG. 2B, and FIG. 3, the production | generation method of the back surface action pattern which should be memorize | stored in the back surface action pattern memory | storage device 3 is demonstrated.

  FIG. 2A shows an example of a state in which the semiconductor wafer 30 is held by a robot arm. Two pins 26 are fixed to the upper surface of the support plate 25. Two movable arms 21 are arranged on both sides of the support plate 25. A pin 22 is fixed to the upper surface of each distal end of the movable arm 21. The semiconductor wafer 30 is placed on the upper surface of the support plate 25 so that the two pins 26 are in contact with the edge of the semiconductor wafer 30. When the two movable arms 21 are closed, the pin 22 at the tip thereof contacts the edge of the semiconductor wafer 30 and the position of the semiconductor wafer 30 is restrained.

  The semiconductor wafer 30 is provided with a notch 31 for indicating the position in the rotational direction within the surface. When the transfer in the robot arm is already completed, the notch 31 is always arranged at the same position with respect to the robot arm. When the alignment in the rotational direction is not completed, or when it is not necessary to perform the alignment in the rotational direction, the position of the notch 31 is indefinite.

  FIG. 2B shows a state of foreign matter (particles) adhering to the back surface of the semiconductor wafer 30 after being transferred by the robot arm of FIG. 2A. Foreign matter concentrates on and adheres to the portion of the back surface of the semiconductor wafer 30 that has received a mechanical action from the robot arm and the vicinity thereof. In the example shown in FIG. 2B, foreign substances are locally attached to the region 35 where the support plate 25 is in contact, the region 32 where the pin 22 is contacted, and the region 36 where the pin 26 is contacted. On the contrary, it is possible to know which part of the semiconductor wafer 30 has been subjected to the mechanical action from the distribution of the foreign matter.

  The back surface action pattern indicates a pattern corresponding to a portion where each device has applied a mechanical action to the semiconductor wafer. Therefore, the back surface action pattern can be generated based on the pattern to which foreign matter is attached.

  FIG. 3 shows an example of a foreign matter adhesion pattern on the back surface after processing a semiconductor wafer with various apparatuses. The foreign matter adhesion pattern is acquired by actually processing the evaluation wafer and then observing scattered light from the back surface of the evaluation substrate using a dark field observation apparatus. It can be seen that the part to which foreign matter is attached and the pattern to which it is attached differ depending on the apparatus. Based on this foreign substance adhesion pattern, a back surface action pattern is generated for each apparatus.

  The generated back surface action pattern is stored in the back surface action pattern storage device shown in FIG. 1 in association with the manufacturing facility that caused the back surface action pattern. The back surface action pattern is stored together with fixed / undefined identification information for distinguishing whether the relative positional relationship with the notch 31 is fixed or undefined.

  Equipment for the backside action pattern creation can contact the backside of semiconductor wafers, including not only equipment used in each manufacturing process of semiconductor devices, but also defect inspection equipment, film thickness measurement equipment, wafer transfer equipment, etc. This includes all facilities that have sex.

  The action applied to the back surface of the semiconductor wafer is not only mechanical. For example, an electrical action may be applied.

  With reference to FIGS. 4A to 4D, a procedure for loading a semiconductor wafer into a plasma processing apparatus such as plasma CVD or reactive ion etching will be described as an example of a process in which an electrical action is applied to the semiconductor wafer.

  As shown in FIG. 4A, a wafer holder 50 is disposed in the vacuum chamber. Electrostatic chuck electrodes 51 are embedded in the surface layer portion of the wafer holder 50. A plurality of pins 52 for supporting the wafer and raising and lowering it are loaded in a hole penetrating the wafer holding table 50 in the thickness direction. The robot arm 55 holds the semiconductor wafer 30 on the holding surface and transports the semiconductor wafer 30 to above the wafer holding table 50.

  As shown in FIG. 4B, the pin 52 is raised. The tips of the pins 52 come into contact with the back surface of the semiconductor wafer 30, and the semiconductor wafer 30 rises while being supported by the pins 52. As a result, the semiconductor wafer 30 is separated from the holding surface of the robot arm 55. The robot arm 55 has a planar shape that does not interfere with the pin 52 when the pin 52 is raised.

  As shown in FIG. 4C, the robot arm 55 is retracted from above the wafer holding table 50. As shown in FIG. 4D, the pins 52 are lowered to bring the semiconductor wafer 30 into contact with the upper surface of the wafer holder 50. In this state, the semiconductor wafer 30 is fixed to the upper surface of the wafer holder 50 by applying a voltage to the electrode 51 of the electrostatic chuck.

  In the process shown in FIG. 4B, when the potential difference between the semiconductor wafer 30 and the pin 52 is large, when the pin 52 is brought close to the semiconductor wafer 30, spark discharge may occur between the two. When spark discharge occurs, defects such as recesses occur on the back surface of the semiconductor wafer 30. The position of this defect corresponds to the position of the pin 52.

  5A to 5F show examples of pin positions of various plasma apparatuses. In the example shown in FIG. 5A, a pin 52 is arranged at the apex of an equilateral triangle. The center of this equilateral triangle coincides with the center of the semiconductor wafer 30, and one vertex is located on an imaginary straight line passing through the center of the semiconductor wafer 30 and the notch 31. In the example shown in FIG. 5B, the pin 52 is arranged at the apex of an equilateral triangle larger than the equilateral triangle shown in FIG. 5A. In the example shown in FIG. 5C, the pin 52 is arranged at the apex of the equilateral triangle obtained by rotating the equilateral triangle shown in FIG. 5A by 180 degrees. In the example shown in FIG. 5D, two pins 52 are arranged in the vicinity of the apex of the regular triangle.

  In the example shown in FIG. 5E, the pin 52 is arranged at the apex of the regular hexagon. The center of this regular hexagon coincides with the center of the semiconductor wafer 30, and two vertices are located on a virtual straight line passing through the center of the semiconductor wafer 30 and the notch 31. In the example shown in FIG. 5F, the pin 52 is arranged at the apex of the regular hexagon obtained by rotating the regular hexagon shown in FIG. 5E by a certain angle.

  5A to 5F show the case where the positional relationship between the notch 31 and the pin 52 of the semiconductor wafer 30 is fixed, but the two are not fixed to each other, and the position of the pin 52 in the rotation direction is the same. It may be indefinite.

  As described above, the arrangement of the pins 52 is different for each plasma processing apparatus. The arrangement of the pins corresponds to the position of a defect that may occur on the back surface of the semiconductor wafer 30 due to an electrical action such as generation of a spark discharge. Therefore, the back surface action pattern may be generated based on the arrangement of the pins 52. The generated back surface action pattern is stored in the back surface action pattern storage device shown in FIG. 1 in association with a manufacturing facility having a pin arrangement corresponding to the back surface action pattern. The back surface action pattern is stored together with fixed / indefinite identification information for distinguishing whether the relative positional relationship with the notch 31 is fixed or indefinite.

  FIG. 6 shows a flowchart of the inspection method according to the embodiment. In step S1, a semiconductor wafer that has completed a process on the production line, for example, process B shown in FIG. 1, is taken into the defect distribution pattern detection apparatus 1 of the inspection apparatus 10, and the back surface thereof is observed to detect defects on the back surface. Get the distribution pattern. This defect distribution can be acquired by, for example, an optical microscope. The acquisition of the defect distribution pattern may be performed for all semiconductor wafers, or may be performed only for the semiconductor wafers extracted by sampling.

  In step S2, it is determined whether or not the semiconductor wafer from which the defect distribution pattern has been acquired is abnormal. If it is not abnormal, the semiconductor wafer is handed over to the next process and the problem facility specifying process is terminated.

  If it is determined in step S2 that there is an abnormality, the defect distribution pattern is compared with the back surface action pattern stored in the back surface action pattern storage device 3 in step S3. When the back surface action pattern to be collated is fixed with respect to the rotation direction, the relative position in both the rotation directions is fixed, and collation is performed in a state where the positions corresponding to the notches are matched. When the back surface action pattern to be collated is indefinite with respect to the rotation direction, collation is performed while relatively rotating the defect distribution pattern of the semiconductor wafer and the back surface action pattern.

  In step S4, it is determined whether there is a back surface action pattern similar to the defect distribution pattern.

  FIG. 7 shows an example of the defect distribution pattern. It can be seen that two scratches 40 are formed on the back surface of the semiconductor wafer 30. The scratches 40 are arranged in parallel to each other with the center of the semiconductor wafer 30 in between, and the two strings separated by about 4/7 of the radius from the center toward the center of the strings from the opposite ends. Extend. The pattern of the scratch 40 is compared with the plurality of back surface action patterns shown in FIG. It can be seen that the defect distribution pattern shown in FIG. 7 approximates the back surface action pattern of the facility B3 shown in FIG.

  In the example of FIG. 7, it is determined in step S4 that a similar back surface action pattern exists. In this case, the problem facility is identified in step S5. In the example of FIG. 7, it can be estimated that the scratch 40 is caused by the facility B3. That is, it is estimated that there is a problem with the facility B3.

  FIG. 8A shows a micrograph of one defect generated by spark discharge, and FIG. 8B shows a distribution pattern of defects generated in the semiconductor wafer. The distribution pattern shown in FIG. 8B is obtained by superimposing the distribution patterns of defects generated in a plurality of semiconductor wafers. This superposition is performed by the collation device 2 shown in FIG. When only one defect is generated in one semiconductor wafer, it may be difficult to specify the back surface action pattern corresponding to the distribution of the defect. As shown in FIG. 8B, when the distribution patterns of defects generated on a plurality of semiconductor wafers are overlapped, it can be seen that defects are concentrated on the vertices of an equilateral triangle. By collating the overlapped defect distribution pattern with the back surface action pattern, it becomes easy to specify a similar back surface action pattern. In the example shown in FIG. 8B, it can be seen that the distribution of defects is similar to the back surface action pattern shown in FIG. 5A.

  In step S6, a countermeasure is implemented. For example, when the defect shown in FIG. 7 is detected, the equipment B3 shown in FIG. 3 is switched to a spare equipment and the equipment B3 is repaired. In addition, when multiple systems that perform the same processing as the system including the equipment B3, for example, 3 systems are prepared, the use of one system including the equipment B3 is prohibited, and the production line is operated in the other two systems. To do.

  When the defect shown in FIG. 8B is detected, the plasma processing apparatus having the pin arrangement shown in FIG. 5A is inspected and adjusted. For example, the spark discharge is less likely to occur by slowing the rising speed of the pin. Further, by re-adjusting the pressure in the chamber when raising the pin, even if a discharge occurs, a glow discharge can be generated instead of a spark discharge.

  If no similar pattern is found in step S4, the problem is solved by another method in step S7.

  In the said Example, the installation which became a problem can be identified quickly based on the defect distribution pattern of the back surface of a semiconductor wafer. Thereby, stable operation of the production line and early recovery can be enabled. Compared with the case where a problem process or equipment is specified by inspecting a circuit pattern or the like on the surface on which the electronic circuit element is formed, pattern matching can be easily performed and the problem equipment can be specified.

  In some cases, scratches on the back surface that do not directly affect the surface on which the electronic circuit element is formed may occur. In such a case, only the surface inspection cannot identify the equipment that caused the scratch. If the operation of the equipment causing the scratch is continued, the semiconductor wafer may be cracked. By performing an inspection using the defect distribution pattern on the back surface, it is possible to prevent such cracks from occurring.

  In the above-described embodiment, the semiconductor wafer production line has been described as an example. However, the inspection method and apparatus according to the above-described embodiment may be applied to other plate-like processing objects, for example, a liquid crystal panel production line. Is possible.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  The invention shown in the following supplementary notes is derived from the above-described embodiments.

(Appendix 1)
(A) For each of a plurality of manufacturing facilities for processing a substrate to be processed, a pattern of a region in which the manufacturing facility exerts a mechanical action or an electrical action on the back surface of the substrate to be processed is associated with the manufacturing facility, A step of preparing as a backside action pattern in advance;
(B) obtaining a distribution pattern of defects generated on the back surface of the processing target substrate processed by at least some of the plurality of manufacturing facilities;
(C) a step of identifying the manufacturing facility that caused the defect by collating the defect distribution pattern acquired in the step (b) with the back surface action pattern prepared in advance; Inspection method having

(Appendix 2)
The step (a)
A step of processing an evaluation substrate in each of the manufacturing facilities;
The inspection method according to appendix 1, including a step of observing the back surface of the evaluation substrate after processing and generating the back surface action pattern based on a pattern on which foreign matter is adhered.

(Appendix 3)
The step (a)
The inspection method according to claim 1 or 2, further comprising a step of generating the back surface action pattern based on an arrangement of pins that are provided on a processing target substrate holding table of a manufacturing facility and raise and lower the processing target substrate.

(Appendix 4)
In the step (a), preparing the back surface action pattern so that the back surface action pattern in which the position in the rotation direction within the surface of the processing target substrate is fixed and the back surface action pattern not fixed can be distinguished,
In the step (c), when collating with the back surface action pattern in which the position in the plane of the substrate to be processed is fixed, it relates to the rotation direction of the defect distribution pattern acquired in the step (b). In the case where the position is fixed and collation is performed and collation is performed with the back surface action pattern in which the position in the rotation direction in the surface of the processing target substrate is not fixed, the defect distribution pattern obtained in the step (b) The inspection method according to any one of supplementary notes 1 to 3, wherein collation is performed while changing a position related to a rotation direction.

(Appendix 5)
The inspection according to any one of appendices 1 to 4, wherein in the step (c), a distribution pattern obtained by superimposing distribution patterns of defects on each of a plurality of substrates to be processed is compared with the back surface action pattern. Method.

(Appendix 6)
For each of the plurality of manufacturing facilities for processing the substrate to be processed, back surface action pattern storage means for storing a pattern of a region in which the manufacturing facility exerts a mechanical action or an electrical action on the back surface of the processing target substrate;
A defect distribution pattern detecting means for acquiring a distribution pattern of defects generated on the back surface of the substrate to be processed processed by at least some of the plurality of manufacturing facilities;
The defect distribution pattern detected by the defect distribution pattern detection means is compared with the back face action pattern stored in the back face action pattern storage means, and the defect is caused based on the check result. An inspection apparatus having verification means for specifying a manufacturing facility.

(Appendix 7)
The back surface action pattern storage means stores the back surface action pattern so that a back surface action pattern in which a position in the rotation direction within the surface of the processing target substrate is fixed can be distinguished from an unfixed back surface action pattern. ,
The collating means, when collating the defect distribution pattern acquired by the defect distribution pattern detecting means with the back surface action pattern stored in the back surface action pattern storage means, in the in-plane rotation direction of the processing target substrate The position of the defect distribution pattern acquired by the defect distribution pattern detecting means is fixed and the position of the defect distribution pattern is compared and fixed in the plane of the substrate to be processed. In the case of collating with the back-surface action pattern whose position in the rotation direction is not fixed, the collation is performed while changing the position in the rotation direction of the defect distribution pattern acquired by the defect distribution pattern detecting means. The inspection device described.

(Appendix 8)
The collating means includes a distribution pattern obtained by superimposing the defect distribution patterns of the plurality of processing target substrates acquired by the defect distribution pattern detecting means, and a back face action pattern stored in the back face action pattern storage means. The inspection apparatus according to appendix 6 or 7, wherein the verification is performed.

It is a block diagram of the inspection apparatus by an Example. (2A) is a plan view showing a state in which the semiconductor wafer is held by the robot arm, and (2B) is a bottom view showing the distribution of the foreign matter adhering to the back surface of the semiconductor wafer after being held by the robot arm. is there. It is a figure which shows the distribution pattern of the foreign material adhering to the back surface of a semiconductor wafer after processing with various facilities. It is a schematic sectional drawing for demonstrating the procedure which mounts a semiconductor wafer on the wafer holding stand with a pin. It is a top view which shows the example of arrangement | positioning of the pin with which the wafer holding stand of the plasma processing apparatus is equipped. It is a flowchart which shows the inspection method by an Example. It is a bottom view which shows an example of the defect formed in the back surface of a semiconductor wafer. (8A) is a photomicrograph of defects on the backside of the semiconductor wafer generated by discharge, and (8B) is a diagram showing an example of defect distribution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Defect distribution pattern detection apparatus 2 Collation apparatus 3 Back surface action pattern memory | storage device 10 Inspection apparatus 21 Movable arm 22 Pin 25 Support board 26 Pin 30 Semiconductor wafer 31 Notch 32, 35, 36 The area | region where a foreign material is distributed intensively 40 Scratch 50 Wafer Holding stand 51 Electrode for electrostatic chuck 52 Pin 55 Robot arm

Claims (6)

(A) For each of a plurality of manufacturing facilities for processing a substrate to be processed, a pattern of a region in which the manufacturing facility exerts a mechanical action or an electrical action on the back surface of the substrate to be processed is associated with the manufacturing facility, A step of preparing as a backside action pattern in advance;
(B) obtaining a distribution pattern of defects generated on the back surface of the processing target substrate processed by at least some of the plurality of manufacturing facilities;
(C) a step of identifying the manufacturing facility that caused the defect by collating the defect distribution pattern acquired in the step (b) with the back surface action pattern prepared in advance; Inspection method having The step (a)
A step of processing an evaluation substrate in each of the manufacturing facilities;
The method according to claim 1, further comprising: observing a back surface of the evaluation substrate after processing and generating the back surface action pattern based on a pattern to which foreign matter is attached. The step (a)
The inspection method according to claim 1, further comprising a step of generating the back surface action pattern based on an arrangement of pins provided on a processing target substrate holding base of a manufacturing facility and moving the processing target substrate up and down. In the step (a), preparing the back surface action pattern so that the back surface action pattern in which the position in the rotation direction within the surface of the processing target substrate is fixed and the back surface action pattern not fixed can be distinguished,
In the step (c), when collating with the back surface action pattern in which the position in the plane of the substrate to be processed is fixed, it relates to the rotation direction of the defect distribution pattern acquired in the step (b). In the case where the position is fixed and collation is performed and collation is performed with the back surface action pattern in which the position in the rotation direction in the surface of the processing target substrate is not fixed, the defect distribution pattern obtained in the step (b) The inspection method according to any one of claims 1 to 3, wherein the collation is performed while changing the position in the rotation direction. For each of the plurality of manufacturing facilities for processing the substrate to be processed, back surface action pattern storage means for storing a pattern of a region in which the manufacturing facility exerts a mechanical action or an electrical action on the back surface of the processing target substrate;
A defect distribution pattern detecting means for acquiring a distribution pattern of defects generated on the back surface of the substrate to be processed processed by at least some of the plurality of manufacturing facilities;
The defect distribution pattern detected by the defect distribution pattern detection means is compared with the back face action pattern stored in the back face action pattern storage means, and the defect is caused based on the check result. An inspection apparatus having verification means for specifying a manufacturing facility. The back surface action pattern storage means stores the back surface action pattern so that a back surface action pattern in which a position in the rotation direction within the surface of the processing target substrate is fixed can be distinguished from an unfixed back surface action pattern. ,
The collating means, when collating the defect distribution pattern acquired by the defect distribution pattern detecting means with the back surface action pattern stored in the back surface action pattern storage means, in the in-plane rotation direction of the processing target substrate The position of the defect distribution pattern acquired by the defect distribution pattern detecting means is fixed and the position of the defect distribution pattern is compared and fixed in the plane of the substrate to be processed. 6. When collating with a back-surface action pattern whose position in the rotation direction is not fixed, the collation is performed while changing the position in the rotation direction of the defect distribution pattern acquired by the defect distribution pattern detecting means. The inspection device described in 1.