Defect inspection device and defect inspection method

Abstract

Provided are a defect inspection device and a defect inspection method with which it is possible, when detecting a defect in a rectangular element chip, to more accurately detect the defect. Specifically, a defect inspection device comprises: an imaging unit that captures an image of a rectangular element chip 83; and a control unit that detects a defect in a peripheral region 83b of the element chip 83 by acquiring an outer peripheral line L1 and assessment lines L2 and L3 on the basis of a captured image 60 of the element chip 83 captured by the imaging unit. On the basis of a corner region C that is set at a corner of the rectangular element chip 83, the control unit sets the assessment line L3 inside the corner region C by connecting intersections of a boundary line of the corner region C and each of a pair of assessment lines L2 extending along adjacent sides of the element chip 83 such that the intersections are connected closer to an element-formation-region 83a side than in cases where each of the pair of assessment lines L2 is extended.

Description

Defect inspection device and defect inspection method

[0001] The present invention relates to a defect inspection device and a defect inspection method, and particularly to a defect inspection device and a defect inspection method for detecting defects in element chips.

[0002] Conventionally, a defect inspection device that detects defects in element chips by image processing is known (see, for example, Patent Documents 1 and 2).

[0003] Patent Document 1 describes a defect inspection device that detects defects in element chips formed by cutting a substrate. This defect inspection device detects defects in an inspection area that includes an effective area where elements are formed in the element chip and a peripheral area provided at the periphery of the effective area, based on an image of the captured element chip. The defect inspection device described in Patent Document 1 detects defects in the element chip by comparing an image corresponding to the inspection area of the element chip with an image of a non-defective element chip stored in advance.

[0004] Further, Patent Document 2 describes a processing device that divides a workpiece including a semiconductor wafer into individual chips. This processing device performs a kerf check to confirm whether there are any abnormalities such as chips in the machining marks from an image of the planned division line after cutting. In the processing device described in Patent Document 2, after the cutting process for dividing the chips is performed, a kerf check is performed by determining whether the cutting groove fits within the width of the set planned division line based on an image of the cutting groove.

[0005] Japanese Patent No. 6752593 Japanese Unexamined Patent Application Publication No. 2021 - 30323

[0006] Here, as described in Patent Documents 1 and 2 above, when detecting defects in an element chip based on an image of the element chip, it is conceivable to image the element chip after it has been divided into rectangles and to detect defects such as chips that are occurring from the outer edge of the element chip toward the interior based on a predetermined judgment line. In this case, it is conceivable that over-detection may occur at the corners of the rectangular element chip, where defects are detected more than necessary. Specifically, when linear judgment lines are set along each side of the rectangular element chip and defects that reach from the outer edge of the element chip to the judgment line are detected, the positions of the intersections of the judgment lines at the four corners of the element chip are located diagonally, further away from the effective region (element formation region) where the element is formed, compared to the positions on the judgment line in the middle of each side. Therefore, at the corners of the four corners of the element chip, the detection target region becomes one where defects are detected at a distance greater than the distance required for defect detection from the element formation region, resulting in over-detection of defects. Therefore, it is desirable to detect defects in rectangular element chips with greater accuracy by appropriately setting the judgment lines at the four corners of the element chip.

[0007] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a defect inspection device and defect inspection method that can detect defects in rectangular element chips with greater accuracy.

[0008] To achieve the above objective, the defect inspection apparatus according to the first aspect of the present invention includes an imaging unit that images a rectangular element chip including an element formation region on which an element is formed and a surrounding region provided around the element formation region, and a control unit that detects defects in the surrounding region of an element chip by acquiring outer perimeter lines arranged along the outer perimeter of the surrounding region along each side of the rectangular element chip and determination lines arranged outside the element formation region and inside the outer perimeter lines, respectively, based on the image of the element chip captured by the imaging unit, wherein the control unit sets determination lines inside the corner region by connecting the intersection points of the boundary line of the corner region and each of the pair of determination lines along each adjacent side of the element chip, bringing them closer to the element formation region than if each of the pair of determination lines were extended.

[0009] In this first-phase defect inspection device, as described above, the control unit sets the judgment lines within the corner region by connecting the intersection points of the boundary line of the corner region and each of the pair of judgment lines along each adjacent side of the element chip, based on the corner region set at the corner of the rectangular element chip, and bringing them closer to the element formation area than if each of the pair of judgment lines were extended. As a result, in the corner regions set at the four corners of the rectangular element chip, the judgment lines are set closer to the element formation area than if each of the pair of judgment lines were extended. Therefore, the judgment lines within the corner region can be appropriately set by bringing them closer to the element formation area to suppress over-detection of defects. Consequently, the judgment lines at the four corners of the element chip can be appropriately set, and defects can be detected with greater accuracy when detecting defects in the rectangular element chip.

[0010] In the defect inspection apparatus according to the first aspect described above, preferably, the control unit sets a curved or straight judgment line within the corner region. With this configuration, the shape of the judgment line within the corner region can be set more appropriately to match the shape of the corner of the element formation region where the element is formed. As a result, the judgment lines at the four corners of the element chip can be set more appropriately, and defects can be detected with greater accuracy when detecting defects in rectangular element chips.

[0011] In this case, preferably, the system further includes an operating unit that receives input from an operator, and the control unit sets a circular or elliptical arc-shaped determination line within the corner region and adjusts the curvature of the arc-shaped determination line based on the input received by the operating unit. With this configuration, the curvature of the arc-shaped determination line can be easily adjusted by the operator's input. As a result, the shape of the determination line within the corner region can be set more appropriately, and defects in rectangular element chips can be detected with greater accuracy.

[0012] In a defect inspection device that sets curved or straight judgment lines as described above, preferably, the device further includes an operation unit that receives input operations from an operator, and the control unit sets a rectangular corner area based on the input operations received by the operation unit. With this configuration, the rectangular corner area can be set by input operations from an operator, making it easier to set the appropriate position and size of the corner area. Therefore, since the appropriate corner area can be set more easily based on input operations from an operator, the judgment lines at the four corners of the element chip can be set more easily. As a result, when detecting defects in a rectangular element chip, defects can be detected more easily and accurately.

[0013] In the defect inspection apparatus according to the first aspect described above, preferably, a display unit is further provided to display the detection results of defects in the peripheral region of the element chip by the control unit, and the control unit displays the detection results on the display unit in such a way that defects detected in the corner region and defects detected outside the corner region can be distinguished. With this configuration, by visually recognizing the detection results displayed on the display unit, defects detected in the corner region and outside the corner region can be easily distinguished. Therefore, by visually recognizing the detection results, it is easy to recognize which region of the rectangular element chip a defect has been detected in.

[0014] A defect inspection method according to a second aspect of this invention includes the steps of: acquiring an image of a rectangular element chip including an element formation region on which an element is formed and a surrounding region provided around the element formation region; acquiring an outer perimeter line arranged on the outer perimeter of the surrounding region along each side of the rectangular element chip based on the image; acquiring a determination line arranged along the outer perimeter line, outside the element formation region and inside the outer perimeter line, based on the image; and detecting a defect in the surrounding region of the element chip based on the outer perimeter line and the determination line, wherein the step of acquiring the determination line includes setting a determination line inside the corner region by connecting the intersection points of the boundary line of the corner region and each of a pair of determination lines along each adjacent side of the element chip, based on a corner region set at the corner of the rectangular element chip, so that the intersection points are closer to the element formation region than when each of the pair of determination lines is extended.

[0015] In this second phase of defect inspection, as described above, the step of acquiring a judgment line includes setting a judgment line within a corner region by connecting the intersection points of the boundary line of the corner region and each of the pair of judgment lines along each adjacent side of the element chip, based on the corner region set at the corner of the rectangular element chip, and bringing them closer to the element formation area than if each of the pair of judgment lines were extended. As a result, in the corner regions set at the four corners of the rectangular element chip, the judgment lines are set closer to the element formation area than if each of the pair of judgment lines were extended. Therefore, the judgment line within the corner region can be appropriately set by bringing it closer to the element formation area to suppress over-detection of defects. Thus, since the judgment lines at the four corners of the element chip can be appropriately set, a defect inspection method can be provided that can detect defects in rectangular element chips with greater accuracy.

[0016] As described above, the defect inspection apparatus and defect inspection method of the present invention can detect defects in rectangular element chips with greater accuracy.

[0017] This is a schematic diagram showing the overall configuration of a defect inspection device according to one embodiment of the present invention. This is a schematic plan view showing the configuration of the unit under inspection. This is a plan view showing the element chip. This is a diagram for explaining the operation of the imaging unit. This is a diagram showing an example of an image captured from an image of the element chip. This is a diagram for explaining the outer perimeter line and the judgment line. This is a flowchart for explaining a defect inspection method according to one embodiment of the present invention. This is a diagram for explaining the setting of the judgment line in the corner region. This is a diagram for explaining the adjustment of the curvature of the judgment line curve in the corner region. This is a diagram showing an example of the display of the setting screen. This is a diagram showing an example of the display of the detection result. This is a diagram showing a judgment line according to a modified example of one embodiment of the present invention.

[0018] The following describes embodiments of the present invention based on the drawings.

[0019] (Configuration of the defect inspection device) The configuration of the defect inspection device 100 according to one embodiment of the present invention will be described with reference to Figures 1 to 6.

[0020] As shown in Figure 1, the defect inspection device 100 is a device for inspecting defects 90 (see Figure 5) in element chips 83 (see Figure 2) contained in a unit to be inspected 80 after dicing. The defect inspection device 100 comprises a moving stage 10, a base unit 20, a mounting table 30, an imaging unit 40, a control unit 50, a storage unit 51, a display unit 52, and an operation unit 53. The moving stage 10 includes an X-axis slider 11 and a Y-axis slider 12. The X-axis slider 11 is positioned on the base unit 20 and is configured to move the Y-axis slider 12, positioned above it, in the left-right direction (X direction) in Figure 1. The Y-axis slider 12 is positioned on the X-axis slider 11 and is configured to move the mounting table 30, positioned above it, in the depth direction (Y direction) in Figure 1. In the following description, one side of the X direction will be referred to as the X1 direction and the other side as the X2 direction. Furthermore, in Figure 1, the far side in the Y direction will be referred to as the Y1 direction, and the near side as the Y2 direction. Also, in Figure 1, the height direction will be referred to as the Z direction, and in the Z direction, the direction in which the height increases will be referred to as the Z1 direction, and the direction in which the height decreases will be referred to as the Z2 direction.

[0021] The mounting table 30 is positioned on the Y-axis slider 12. The mounting table 30 is configured to be moved in the X and Y directions by the moving stage 10. The mounting table 30 is configured to have the unit to be inspected 80 placed on its upper surface (Z1 side).

[0022] The imaging unit 40 is configured to image a rectangular element chip 83 (see Figures 2 and 3) which includes an element formation region 83a on which elements (patterns) are formed and a peripheral region 83b around the element formation region 83a on which no elements are formed. The imaging unit 40 includes a lens barrel 41, a half mirror 42, an objective lens 43, and an imaging camera 44. The imaging camera 44 includes a light-receiving element 44a. The light-receiving element 44a includes, for example, an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The imaging camera 44 is configured to output the imaged image 60 (see Figure 5) of the imaged element chip 83 to a control unit 50, which will be described later.

[0023] Furthermore, as shown in Figure 4, the imaging unit 40 is configured to sequentially image a plurality of element chips 83 that move relative to the imaging unit 40. Specifically, the element chips 83 are moved relative to the imaging unit 40 by the moving stage 10.

[0024] As shown in Figure 1, the control unit 50 controls the operation of each part of the defect inspection device 100. The control unit 50 is also configured to inspect defects 90 (see Figure 5) based on the captured image 60 (see Figure 5), which is an image of the element chip 83 captured by the imaging unit 40. In this embodiment, the control unit 50 is configured to detect defects 90 in the surrounding region 83b of the element chip 83 based on the captured image 60 captured by the imaging unit 40. The storage unit 51 is configured to store data sent from the control unit 50. The storage unit 51 is a storage medium that stores programs and parameters for operating the control unit 50. The control unit 50 performs control using the programs and parameters stored in the storage unit 51. The control unit 50 is, for example, one or more computers having an arithmetic unit such as a CPU (Central Processing Unit). The control unit 50 may be composed of hardware such as a personal computer, processor, or circuit. The storage unit 51 includes storage devices such as flash memory and HDD (Hard Disk Drive). The detailed operation of the control unit 50 and the storage unit 51 will be described later.

[0025] The display unit 52 displays images and character information generated by the control unit 50. For example, the display unit 52 displays the captured image 60 (see Figure 5) and the setting screen 61 (see Figure 10) generated by the control unit 50. The display unit 52 also displays the detection result 62 (see Figure 11) of defects 90 in the element chip 83 by the control unit 50. The display unit 52 includes, for example, a display monitor. The operation unit 53 receives input operations from the operator. The operation unit 53 also outputs a signal to the control unit 50 indicating the received input operation. The operation unit 53 includes, for example, a keyboard and a pointing device such as a mouse.

[0026] (Configuration of the Unit Under Inspection) As shown in Figure 2, the unit under inspection 80 includes a frame 81, a sheet member 82, and an element chip 83. The frame 81 and the element chip 83 are arranged on the surface (Z1 side) of the sheet member 82. The element chip 83 is a semiconductor wafer divided by a dicing area DA shown by a dashed line. The dicing area DA is a region cut by a blade or laser during the dicing process. The sheet member 82 is a flexible sheet that expands the spacing between multiple element chips 83 by being stretched in a post-dicing process. The lower surfaces (Z2 side) of the multiple element chips 83 and the upper surface (Z1 side) of the sheet member 82 are fixed together, for example, by adhesive. The frame 81 is made of SUS or the like, which has relatively high hardness, in order to improve the transportability of the unit under inspection 80. The frame 81 also has a ring shape.

[0027] As shown in Figure 3, the element chip 83 includes an element formation region 83a and a surrounding region 83b. The surrounding region 83b is provided around the element formation region 83a and is larger than the element formation region 83a. Multiple element chips 83 are arranged in a matrix on the surface of the sheet member 82, with the dicing area DA in between. The element chip 83 has a rectangular shape, and the element formation region 83a also has a rectangular shape. The element chip 83 is a semiconductor chip in which a semiconductor element is formed in the element formation region 83a.

[0028] (Captured Image) As shown in Figure 5, the captured image 60 shows the sheet member 82 (dicing area DA) and the element chip 83. In addition, during the dicing process, defects 90 may occur that extend from the outer edge (end) of the element chip 83 (outer region 83b) toward the element formation region 83a, which is the inside, due to the surrounding region 83b being cut by a blade or the like.

[0029] As shown in Figure 6, in this embodiment, the control unit 50 acquires, based on the captured image 60 captured by the imaging unit 40, an outer peripheral line L1 arranged along each side of the rectangular element chip 83 on the outer periphery of the surrounding region 83b, and determination lines L2 and L3 arranged along the outer peripheral line L1, outside the element formation region 83a and inside the outer peripheral line L1. The control unit 50 is configured to detect defects 90 in the surrounding region 83b of the element chip 83 by acquiring the outer peripheral line L1 and the determination lines L2 and L3 based on the captured image 60. Specifically, the control unit 50 sets a rectangular outer peripheral line L1 that follows the outer shape of the element chip 83, a determination line L2 formed by a straight line portion, and a determination line L3 in a corner region C that connects the two straight determination lines L2. Based on the outer peripheral line L1 and the determination lines L2 and L3, the control unit 50 detects defects 90 that are in contact with the outer peripheral line L1 and at least one of the determination lines L2 and L3.

[0030] For example, Figure 6 shows examples where defect candidates 90a, 90b, and 90c occur as candidates for a defect 90 extending from the left side (X1 side) of the element chip 83. In the following explanation, the left side (X1 side) of the element chip 83 and the element formation region 83a will be referred to as the left side, the lower side (Y2 side) as the bottom side, the right side (X2 side) as the right side, and the upper side (Y1 side) as the top side. Defect candidate 90a is an example of a defect extending from the upper end (corner) of the left side of the element chip 83. Defect candidate 90b is an example of a relatively large defect extending from the left side of the element chip 83 toward the left side of the element formation region 83a. Defect candidate 90c is an example of a relatively small defect extending from the left side of the element chip 83 toward the left side of the element formation region 83a. The control unit 50 is configured to detect a plurality of defect candidates 90a, 90b, and 90c based on the captured image 60, and to detect a defect 90 from among the detected plurality of defect candidates 90a, 90b, and 90c using the outer edge line L1 and the determination lines L2 and L3. In the example of Figure 6, the control unit 50 detects defect candidate 90b as defect 90.

[0031] (Control Processing for Defect Inspection Method) Now, with reference to Figures 7 to 11, a defect inspection method for an element chip 83 according to one embodiment of the present invention will be described. Note that the control processing from step S1 to step S8 is performed by the control unit 50. The defect inspection method in this embodiment is performed on a unit to be inspected 80 which includes an element chip 83 that has been divided into rectangles by a dicing process.

[0032] As shown in Figure 7, the defect inspection method according to this embodiment includes the steps of: acquiring an image 60 in step S1; acquiring an outer perimeter line L1 in step S2; acquiring a judgment line L2 in a straight section in step S3; setting a corner region C in step S4; setting a judgment line L3 in the corner region C in step S5; detecting defect candidates 90a to 90c in step S6; detecting a defect 90 in step S7; and displaying the detection result 62 in step S8.

[0033] First, in step S1 (see Figure 7), an image 60 of the element chip 83 is acquired. The image 60 may be an image of each element chip 83 individually, or it may be an image of each element chip 83 magnified and captured corner by corner. For example, the control unit 50 moves the unit under inspection 80, on which multiple element chips 83 are arranged, using the moving stage 10, and controls the operation of the imaging unit 40 to acquire multiple image 60 of each element chip 83 individually. The control unit 50 acquires the acquired image 60 from the imaging unit 40 and stores it in the storage unit 51.

[0034] Next, in step S2 (see Figure 7), the outer perimeter line L1 is acquired in the captured image 60. The control unit 50 performs edge extraction image processing on the captured image 60, for example as shown in Figure 8, and acquires the outer perimeter line L1 by approximating the edges extracted in the outer perimeter of the element chip 83 with straight lines. The outer perimeter line L1 is acquired as a straight line indicating the boundary between the outer perimeter of the element chip 83 (surrounding region 83b) and the dicing area DA. That is, the outer perimeter line L1 is set as a straight line along each side at the edge of the outer perimeter of the rectangular element chip 83. Therefore, in the captured image 60, four outer perimeter lines L1 are set in a rectangular shape, each along one of the four sides of the rectangular element chip 83. For example, the control unit 50 performs edge extraction by detecting parts in the captured image 60 where the pixel values ​​change significantly. When setting the outer perimeter line L1 on the left side, the control unit 50 scans the brightness value of each pixel in the captured image 60 in the left-right direction (X direction) and detects the vicinity of pixels where the brightness value changes abruptly on the left side of the element chip 83 as the left edge of the element chip 83. The control unit 50 then sets the approximate straight line of the detected left edge of the element chip 83 as the outer perimeter line L1. The setting of the outer perimeter line L1 on the right side of the element chip 83 is done in the same way. Furthermore, when setting the outer perimeter line L1 on the bottom or top side of the element chip 83, the brightness value of each pixel in the captured image 60 is scanned in the up-down direction (Y direction).

[0035] Next, in step S3 (see Figure 7), a determination line L2 in the straight portion is acquired. For example, as shown in Figure 8, the control unit 50 detects the peripheral edge 84a of the element formation region 83a based on the captured image 60, and sets a straight determination line L2 along the peripheral edge 84a of the element formation region 83a. For example, the control unit 50 detects straight lines corresponding to each side of the peripheral edge 84a of the rectangular element formation region 83a by performing edge extraction image processing on the captured image 60. Then, the control unit 50 sets the determination line L2 at a position offset by α from each side of the detected peripheral edge 84a of the element formation region 83a toward the end of the element chip 83, using a preset offset value α. When setting the determination line L2 on the left side, the control unit 50 scans the brightness value of each pixel in the captured image 60 in the left-right direction (X direction) and detects the vicinity of pixels where the brightness value changes abruptly on the left side of the element formation region 83a as the left edge (periphery 84a) of the element formation region 83a. Then, it approximates the detected edge with a straight line and sets the determination line L2 offset by an offset value α to the outside or inside of the element formation region 83a. The offset value α is a value set in advance by the user and stored in the storage unit 51, and is read by the control unit 50. The same procedure is followed for setting the determination line L2 on the right side of the element formation region 83a. Furthermore, when setting the determination line L2 on the bottom or top side of the element formation region 83a, the brightness value of each pixel in the captured image 60 is scanned in the up-down direction (Y direction).

[0036] Next, in step S4 (see Figure 7), a corner region C (see Figure 8) is set. As shown in Figure 8, in this embodiment, the control unit 50 sets a corner region C at each of the four corners of the rectangular element chip 83. Specifically, the control unit 50 sets a corner region C that includes the intersection of a pair of determination lines L2 corresponding to the outer peripheral line L1 along each adjacent side of the element chip 83. Since a rectangular element formation region 83a is formed in the rectangular element chip 83, the linear determination lines L2 along each side of the element formation region 83a are arranged to follow the outer peripheral line L1. The control unit 50 sets the corner region C to include the position of the intersection of the straight lines obtained by extending the determination lines L2 along the outer peripheral line L1 corresponding to the outer perimeter of the rectangular element chip 83. The corner region C is set, for example, in the surrounding region 83b outside the element formation region 83a.

[0037] In this embodiment, the control unit 50 sets a rectangular corner region C based on an input operation received by the operation unit 53. For example, the control unit 50 displays the captured image 60, or an image of the corners of the captured image 60 enlarged, on the display unit 52 so that it can be seen by the operator. The control unit 50 sets the corner region C based on an input operation by the operator who has seen the captured image 60 and specified the region. For example, the control unit 50 receives an input operation such as a drag operation using a pointing device such as a mouse as the operation unit 53, which allows the operation to specify the diagonal of the rectangular corner region C.

[0038] Next, in step S5 (see Figure 7), the determination line L3 in the corner region C is acquired. As shown in Figure 8, in this embodiment, the control unit 50 sets the determination line L3 inside the corner region C by connecting the intersection points Pa and Pb of the boundary line of the corner region C, shown by the dashed-dotted line, and each of the pair of determination lines L2 along each adjacent side of the element chip 83, so that they are closer to the element formation region 83a than if each of the pair of determination lines L2 were simply extended. In this embodiment, the control unit 50 sets a curved determination line L3 inside the corner region C. In this embodiment, the control unit 50 sets a circular or elliptical arc-shaped determination line L3 inside the corner region C. That is, the control unit 50 sets the determination line L3 inside the corner region C so that it is positioned closer to the element formation region 83a than if the straight determination lines L2 were simply extended and intersected. In the example shown in Figure 8, the defect candidate 90a, which would have been detected as defect 90 if the linear judgment line L2 had been extended, is not detected as defect 90 because it does not touch the judgment line L3.

[0039] For example, based on the set corner region C, the control unit 50 obtains a perfect circle centered at point Po, which passes through intersections Pa and Pb and is located at the corner of the corner region C, or an ellipse with point Po, located at the corner of the corner region C, as its focus. The control unit then sets the portion of the obtained perfect circle or ellipse that is included in the corner region C as a curved determination line L3. For example, if the coordinates of intersection Pa are (xa, ya) and the coordinates of intersection Pb are (xb, yb), then the coordinates of point Po at the corner are expressed as (xb, ya). The control unit 50 sets the determination line L3 by calculating a circle centered at point Po(xb, ya) and passing through intersections Pa(xa, ya) and Pb(xb, yb), or an ellipse with point Po(xb, ya) as its focus and passing through intersections Pa(xa, ya) and Pb(xb, yb).

[0040] In this embodiment, the control unit 50 sets the determination lines L2 and L3 so that the determination lines L2 along each side of the rectangular element chip 83 and the determination lines L3 in the corner region C are continuously connected to each other. The control unit 50 sets the determination lines L2 and L3 so that they surround the element formation region 83a around its entire circumference by connecting the determination lines L2 and L3 to each other. As described above, the control unit 50 sets the linear determination lines L2 along each of the four sides of the element formation region 83a, and then sets the corner region C so that the determination lines L2 connect to each other, thereby setting the determination lines L3 at each of the four corners of the element chip 83.

[0041] <Adjustment of the Judgment Line> In this embodiment, as shown in Figure 9, the control unit 50 is configured to adjust the curvature of the arc-shaped judgment line L3 based on the input operation received by the operation unit 53. The control unit 50 changes the curvature of the arc-shaped judgment line L3 based on the input operation. For example, the control unit 50 changes the position of point Po for setting the judgment line L3 based on the input operation to the operation unit 53. Based on the input operation, the control unit 50 obtains the amount of movement to move point Po from its position at the vertex of the corner of the corner region C toward the interior of the corner region C. For example, if the coordinates of point Po before adjustment are (xb, ya) and the amount of movement obtained by the input operation is δ, the coordinates of point Po after adjustment will be (xb-δ, ya-δ). The control unit 50 moves point Po based on the acquired amount of movement, and acquires an adjusted determination line L3 based on the moved point Po by acquiring a perfect circle centered on the moved point Po and passing through intersections Pa and Pb, or an ellipse with the moved point Po as its focus and passing through intersections Pa and Pb. The adjusted determination line L3 is the portion included in the corner region C of either a perfect circle centered on the moved point Po and passing through intersections Pa and Pb, or an ellipse with the moved point Po as its focus and passing through intersections Pa and Pb. In other words, the control unit 50 adjusts the curvature of the determination line L3 while maintaining a connection with the determination line L2. In the example in Figure 9, the determination line L3 before adjustment is shown as a dotted line, and the determination line L3 after adjustment is shown as a dashed line.

[0042] As shown in Figure 10, the control unit 50 displays a setting screen 61 for adjusting the curvature of the judgment line L3 on the display unit 52. Based on input operations by the operator who has viewed the setting screen 61 displayed on the display unit 52, the control unit 50 sets the amount of movement of point Po in adjusting the curvature. For example, the control unit 50 accepts an operation to set the amount of movement by receiving input operations using a keyboard as the operation unit 53. The control unit 50 may also accept the setting of parameters for image processing of edge extraction in setting the outer perimeter line L1 or the judgment line L2 of the straight portion by displaying the setting screen 61 on the display unit 52.

[0043] The control unit 50 may, for example, accept input operations for setting the corner region C in step S4 and for adjusting the determination line L3 in step S5 for each of the four corners of the element chip 83. Alternatively, the control unit 50 may accept input operations for setting the corner region C in step S4 and for adjusting the determination line L3 in step S5 for one of the four corners of the element chip 83, and then apply the corner region C and determination line L3 set at one corner to the remaining corners to set the corner region C and determination line L3 at each of the four corners of one element chip 83. The control unit 50 may, for example, determine that the setting of determination lines L2 and L3 has been completed based on input operations that complete the setting of the corner region C and determination line L3. The steps for acquiring determination lines L2 and L3 are performed by executing the setting of determination line L2 in step S2, the setting of corner region C in step S3, and the setting of determination line L3 in step S4.

[0044] Next, in step S6 (see FIG. 7), defect candidates 90a to 90c are detected. The control unit 50 detects the defect candidates 90a to 90c, for example, by executing edge extraction image processing on the captured image 60. Specifically, the control unit 50 scans the luminance value of each pixel of the captured image 60 in at least one of the left-right direction (X direction) or the up-down direction (Y direction), and detects, as a defect candidate, a portion surrounded by pixels in which the luminance value has changed abruptly. For example, as shown in FIG. 6, a plurality of defect candidates 90a, a defect candidate 90b, and a defect candidate 90c are detected from the captured image 60. Note that the control process for detecting defect candidates in step S6 may be performed before steps S2 to S5, or may be performed during steps S2 to S5. For example, edge extraction image processing may be performed on the captured image 60, and based on the result of the edge extraction, the setting of the outer peripheral line L1 in step S2, the setting of the determination line L2 in step S3, and the detection of the defect candidates 90a to 90c in step S6 may be performed.

[0045] Next, in step S7 (see FIG. 7), a defect 90 is detected. As shown in FIG. 6, the control unit 50 determines, as a defect 90, a defect candidate that reaches at least one of the determination lines L2 and L3 based on the outer peripheral line L1 among the defect candidates 90a, 90b, and 9cc detected in step S6. For example, the control unit 50 detects the defect candidate 90b as the defect 90 among the defect candidates 90a, 90b, and 90c. The defect candidates 90a and 90c are in contact with the outer peripheral line L1 but not in contact with either of the determination lines L2 and L3, and thus are not detected as the defect 90. The control unit 50 detects the defect 90 on each side of the element chip 83 based on the captured image 60. Further, in the present embodiment, the control unit 50 acquires position information indicating the position of the detected defect 90. For example, the control unit SO acquires the coordinates of the detected defect 90 in the captured image 60 as the position information. The control unit 50 stores the acquired position information in the storage unit 51.

[0046] Steps S2 to S7 are repeated for each element chip 83 included in the unit under inspection 80. Alternatively, the settings for the corner region C in step S4 and the judgment line L3 in step S5 may be performed on one of the multiple element chips 83, thereby allowing the other element chips 83 to use common settings. That is, the settings for the corner region C in step S4 and the judgment line L3 in step S5 may be performed on one element chip 83 by accepting input operations for setting the corner region C and adjusting the judgment line L3, while the settings for steps S4 and S5 may be made common to the other element chips 83 without accepting any input operations.

[0047] Next, in step S8 (see Figure 7), the detection result 62 (see Figure 11) is displayed on the display unit 52. As shown in Figure 11, the control unit 50 causes the display unit 52 to display the detection result 62 of defects 90 in the surrounding region 83b of the element chip 83. The control unit 50 displays the defect 90 detected in step S7 and the location information of the defect 90 on the display unit 52. That is, in this embodiment, the control unit 50 displays the detection result 62 on the display unit 52 in such a way that it can distinguish between defects 90 detected in the corner region C and defects 90 detected outside the corner region C. For example, the control unit 50 displays the "defect ID" indicating the number of the defect 90, the "chip address X" and "chip address Y" indicating which of the multiple element chips 83 it is, and the "X coordinate" and "Y coordinate" indicating the location of the detected defect 90 side by side on the display unit 52. The detection result 62 may also include information indicating the type, size, length, or width of the defect 90.

[0048] As described above, by acquiring the captured image 60, the control unit 50 automatically sets the outer peripheral line L1 and the determination line L2 based on the set parameters, and sets the determination line L3 by receiving an input operation for setting the corner region C and an input operation for adjusting the determination line L3. Then, the control unit 50 detects the defect 90 from the captured image 60 based on the set outer peripheral line L1, determination line L2, and determination line L3. Note that by configuring the control unit 50 with a plurality of computers, a main computer and a computer for image processing may be provided separately, and the control process for the overall operation of the defect inspection device 100 and image processing such as edge extraction may be executed by different computers. Also, by configuring the control unit 50 with one computer, the control process up to steps S1 to S8 may be executed by one computer.

[0049] (Effect of the present embodiment) Next, the effect of the present embodiment will be described.

[0050] In the present embodiment, as described above, based on the corner region C set at the corner of the rectangular element chip 83, the control unit 50 connects the intersections Pa and Pb between the boundary line of the corner region C and each of the pair of determination lines L2 along the adjacent sides of the element chip 83 closer to the element formation region 83a side than when each of the pair of determination lines L2 is extended, thereby setting the determination line L3 inside the corner region C. As a result, in the corner region C set at the four corners of the rectangular element chip 83, the determination line L3 is set closer to the element formation region 83a side than when each of the pair of determination lines L2 is extended. Therefore, the determination line L3 inside the corner region C can be appropriately set by moving it closer to the element formation region 83a side so as to suppress over-detection of the defect 90. Therefore, the determination line L3 at the four corners of the element chip 83 can be appropriately set, so that when detecting the defect 90 of the rectangular element chip 83, the defect 90 can be detected with higher accuracy.

[0051] Furthermore, in this embodiment, since the determination line L3 inside the corner region C is set by connecting the intersection points Pa and Pb of the boundary line of the corner region C and each of the pair of determination lines L2, it is possible to suppress the interruption of the determination lines L2 and L3 between the parts outside the corner region C and the parts inside the corner region C. As a result, it is possible to effectively suppress the failure to detect defects 90 in both the corners and the parts other than the corners of the rectangular element chip 83.

[0052] Furthermore, in this embodiment, as described above, the control unit 50 sets a curved judgment line L3 inside the corner region C. This allows the shape of the judgment line L3 inside the corner region C to be set more appropriately to match the shape of the corner of the element formation region 83a where the element is formed. As a result, the judgment line L3 at the four corners of the element chip 83 can be set more appropriately, so when detecting defects 90 in a rectangular element chip 83, the defects 90 can be detected with greater accuracy.

[0053] Furthermore, in this embodiment, as described above, the defect inspection device 100 includes an operation unit 53 that receives input operations from an operator. The control unit 50 sets a circular or elliptical arc-shaped determination line L3 within the corner region C. The control unit 50 then adjusts the curvature of the arc-shaped determination line L3 based on the input operations received by the operation unit 53. This allows the operator to easily adjust the curvature of the arc-shaped determination line L3 through input operations. As a result, the shape of the determination line L3 within the corner region C can be set more appropriately, and when detecting defects 90 in the rectangular element chip 83, the defects 90 can be detected with greater accuracy.

[0054] Furthermore, in this embodiment, as described above, the defect inspection device 100 includes an operation unit 53 that receives input operations from an operator. The control unit 50 sets a rectangular corner area C based on the input operations received by the operation unit 53. As a result, the rectangular corner area C can be set by an input operation from an operator, making it easier to set the appropriate position and size of the corner area C. Therefore, as the appropriate corner area C can be set more easily based on an input operation from an operator, the judgment line L3 at the four corners of the element chip 83 can be set more easily. As a result, when detecting defects 90 in the rectangular element chip 83, the defects 90 can be detected more easily and accurately.

[0055] Furthermore, in this embodiment, as described above, the defect inspection device 100 includes a display unit 52 that displays the detection results 62 of defects 90 in the surrounding region 83b of the element chip 83 by the control unit 50. The control unit 50 displays the detection results 62 on the display unit 52 so that it is possible to distinguish between defects 90 detected in the corner region C and defects 90 detected outside the corner region C. As a result, by visually recognizing the detection results 62 displayed on the display unit 52, it is possible to easily distinguish between defects 90 detected in the corner region C and outside the corner region C. Therefore, by visually recognizing the detection results 62, it is possible to easily recognize which region of the rectangular element chip 83 has a defect 90.

[0056] [Modifications] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and further includes all modifications (modifications) within the meaning and scope equivalent to the claims.

[0057] For example, in the above embodiment, the control unit 50 is shown to set a curved determination line L3 which is a perfect circle or an elliptical arc within the corner region C, but the present invention is not limited to this. In the present invention, the determination line within the corner region may be set by a curve other than a perfect circle or an ellipse. For example, the determination line within the corner region may be a hyperbola, a parabola, or a spline curve.

[0058] Furthermore, as shown in the modified example of the determination line L203 in Figure 12, the control unit 50 may set a straight determination line L203 inside the corner region C. For example, a straight determination line L203, such as a bent straight line, may be set inside the corner region C. Alternatively, the determination line in the corner region C may be set so that the intersection points Pa and Pb of the boundary line of the corner region C and each of the pair of determination lines L2 are connected by a single straight line. By configuring the control unit 50 to set a straight determination line L203 inside the corner region C in this way, the shape of the determination line L203 inside the corner region C can be set more appropriately to match the shape of the corner of the element formation region 83a where the element is formed. As a result, the determination lines L203 at the four corners of the element chip 83 can be set more appropriately, so that when detecting defects 90 in a rectangular element chip 83, the defects 90 can be detected with greater accuracy. Furthermore, compared to extending the determination lines along the straight portion of the rectangular element chip 83 and directly connecting them to each other, it is preferable that the determination lines in the corner region be shorter in length and positioned closer to the element formation region.

[0059] Furthermore, while the above embodiment shows an example in which the curvature of the circular or elliptical arc-shaped determination line L3 is adjusted by changing the curvature based on the input operation, the present invention is not limited to this. In the present invention, the curvature of the curve of the determination line in the corner region may be changed by deforming it to be closer to a straight line, rather than changing the curvature. Also, even when the determination line in the corner region is straight, the shape of the determination line may be adjusted based on the input operation. In addition, the shape of the determination line inside the corner region may be adjusted by changing the size, position, or shape of the corner region.

[0060] Furthermore, although the above embodiment shows an example in which a rectangular corner region C is set based on input operations, the present invention is not limited thereto. In the present invention, the shape of the corner region may be other than rectangular. In that case, a corner region of a shape other than rectangular may be set based on input operations by the operator. Alternatively, the corner region may be set automatically by detecting the corners of the element chip or the corners of the element formation area by image processing, rather than by input operations.

[0061] Furthermore, although the above embodiment shows an example in which the detection result 62 is displayed on the display unit 52, the present invention is not limited to this. In the present invention, it is not necessary to display the detection result on the display unit. For example, in cases where the defect inspection device is not equipped with a display unit, the acquired detection result may be output to an external source by communication or the like.

[0062] Furthermore, although the above embodiment shows an example in which a semiconductor is used as the element of the element chip 83, the present invention is not limited to this. In the present invention, materials other than semiconductors, such as simple wiring, may be used as the elements of the element chip.

[0063] Furthermore, in the above embodiment, an example was shown in which the outer perimeter line L1 is detected by scanning the brightness value of each pixel in the captured image 60 in at least one of the left-right direction (X direction) or the up-down direction (Y direction) using edge extraction image processing, and detecting the vicinity of pixels where the brightness value changes abruptly. However, the present invention is not limited to this. In the present invention, the outer perimeter line may be detected by binarizing the captured image. Alternatively, the outer perimeter line may be set based on input operations by the operator.

[0064] Furthermore, in the above embodiment, an example was shown in which the brightness value of each pixel of the captured image 60 is scanned in at least one of the left-right direction (X direction) or up-down direction (Y direction) by edge extraction image processing to detect the vicinity of pixels where the brightness value changes abruptly, thereby detecting the peripheral edge 84a of the element formation region 83a, and setting a determination line L2 that is offset to the outside or inside of the element formation region 83a by an offset value α, but the present invention is not limited to this. In the present invention, a linear determination line in a linear portion may be set at a position offset toward the element formation region by a predetermined offset value from the outer peripheral line. That is, a determination line in a linear portion may be set without detecting the peripheral edge of the element formation region.

[0065] Furthermore, in the above embodiment, an example was shown in which the brightness value of each pixel in the captured image 60 is scanned in at least one of the left-right direction (X direction) or the up-down direction (Y direction) by edge extraction image processing, and the portion surrounded by pixels where the brightness value changes abruptly is detected as defect candidates 90a to 90c. However, the present invention is not limited to this. In the present invention, defect candidates may be detected by binarizing the image based on whether or not the brightness value of each pixel in the captured image exceeds a predetermined threshold.

[0066] Furthermore, in the above embodiment, the outer peripheral line L1 is shown as an example of an approximate straight line of the outer edge of the element chip 83, but the present invention is not limited to this. In the present invention, the outer peripheral line may be an approximate straight line of the outer edge of the element chip offset inward by a predetermined amount.

[0067] 40 Imaging unit 50 Control unit 52 Display unit 53 Operation unit 60 Captured image 62 Detection result 83 Element chip 83a Element formation area 83b Surrounding area 90 Defect 100 Defect inspection device C Corner area DA Dicing area L1 Outer perimeter line L2, L3 Judgment line

Claims

1. A defect inspection device comprising: an imaging unit that images a rectangular element chip including an element formation region on which an element is formed and a surrounding region provided around the element formation region; and a control unit that detects defects in the surrounding region of the element chip by acquiring, based on the image of the element chip captured by the imaging unit, an outer peripheral line arranged along each side of the rectangular element chip on the outer periphery of the surrounding region, and a determination line arranged outside the element formation region and inside the outer peripheral line, along the outer peripheral line, wherein the control unit sets the determination line inside the corner region by connecting the intersections of the boundary line of the corner region and each of the pair of determination lines along each adjacent side of the element chip, with the intersections brought closer to the element formation region than when each of the pair of determination lines is extended.

2. The defect inspection apparatus according to claim 1, wherein the control unit sets the curved or straight determination line within the corner region.

3. The defect inspection apparatus according to claim 2, further comprising an operating unit for receiving input operations from an operator, wherein the control unit sets the circular or elliptical arc-shaped determination line within the corner region, and adjusts the curvature of the arc-shaped determination line based on the input operations received by the operating unit.

4. The defect inspection apparatus according to claim 2, further comprising an operating unit for receiving input operations from an operator, wherein the control unit sets the rectangular corner area based on the input operations received by the operating unit.

5. The defect inspection apparatus according to any one of claims 1 to 4, further comprising a display unit for displaying the detection results of defects in the surrounding region of the element chip by the control unit, wherein the control unit causes the display unit to display the detection results in such a way that it can distinguish between defects detected in the corner region and defects detected outside the corner region.

6. A defect inspection method comprising: acquiring an image of a rectangular element chip including an element formation region on which an element is formed and a surrounding region provided around the element formation region; acquiring an outer perimeter line arranged on the outer perimeter of the surrounding region along each side of the rectangular element chip based on the image; acquiring a determination line arranged on the outer perimeter line, outside the element formation region and inside the outer perimeter line, based on the image; and detecting a defect in the surrounding region of the element chip based on the outer perimeter line and the determination line, wherein the step of acquiring the determination line includes setting the determination line inside the corner region by connecting the intersection points of the boundary line of the corner region and each of the pair of determination lines along each adjacent side of the element chip, based on a corner region set at the corner of the rectangular element chip, so that the intersection points are closer to the element formation region than when each of the pair of determination lines is extended.

Images