Crack detection device and method for controlling the crack detection device

Abstract

To provide a crack detection device capable of automatically determining a detection position capable of accurately detecting a crack position and a control method for the same.SOLUTION: A crack detection device (20) is for detecting a crack formed inside a wafer along a street of the wafer, on the basis of detection signals (sg1, sg2) obtained by irradiating a wafer (W) with detection light (L1) and detecting reflected light (L2) of the detection light reflected on the wafer. The crack detection device (20) includes a photographing unit (46) for photographing a street on which one or more patterns are formed and a detection position determining unit (56) that determines a detection position for detecting a crack on the basis of a reflectance of reflected light on the basis of a captured image (47) taken by the photographing unit.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a crack detection device that detects cracks formed inside a wafer and a control method for the crack detection device. [Background technology]

[0002] Conventionally, there is known a laser processing device that irradiates a laser beam along streets (also called lines to be cut or lines to be divided) by focusing the beam inside a wafer such as silicon, and forms a laser processing area that serves as a starting point for cutting inside the wafer along the streets. The wafer with the laser processing area formed therein is then cleaved along the streets by a cleaving process such as expanding or breaking, and divided into individual chips.

[0003] Incidentally, when a laser processing area is formed on a wafer by a laser processing device, a crack propagates from the laser processing area in the thickness direction of the wafer. Then, by detecting the crack position (crack depth) of the crack formed inside the wafer, it is possible to accurately predict whether the laser processing area, which is the starting point when dividing the wafer, has been properly formed, that is, whether the division into chips will be successful (see Patent Document 1).

[0004] Patent document 1 discloses a crack detection device that aligns a focusing lens with the street of a wafer, focuses detection light inside the wafer through the focusing lens, detects the reflected light of the detection light reflected by the wafer, and detects the crack position of a crack formed inside the wafer based on the detection result of this reflected light. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-133997 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, various patterns are formed on the street of the wafer. Therefore, when the detection light is focused from the street to the inside of the wafer using the crack detection device described in Patent Document 1, the reflectance of the reflected light differs between the area where the pattern is formed on the street and the area where the pattern is not formed. In addition, the reflectance of the reflected light differs depending on the type of pattern. Therefore, when the detection light is focused inside the wafer across multiple areas with different reflectances of the reflected light, the difference in reflectance is superimposed on the detection result of the reflected light, so that the detection accuracy of the crack position is reduced. For this reason, in the past, the operator visually determined the detection position for detecting the crack position, or compared the detection results of the crack position at multiple points to thin out the influence of the difference in reflectance from the detection result.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a crack detection device and a control method for a crack detection device that can automatically determine a detection position at which a crack position can be detected with high accuracy. [Means for solving the problem]

[0008] A crack detection device for achieving the object of the present invention focuses detection light inside a wafer through a focusing lens and detects cracks formed inside a wafer along the streets of the wafer based on a detection signal detecting the reflected light of the detection light reflected by the wafer, and includes an imaging unit that photographs a street on which one or more patterns are formed, and a detection position determination unit that determines a detection position for detecting a crack from the reflectance of the reflected light based on the image photographed by the imaging unit.

[0009] According to this crack detection device, a detection position suitable for detecting a crack can be automatically determined.

[0010] In another aspect of the present invention, the crack detection device includes an imaging control unit that causes the imaging unit to capture images of multiple imaging areas along the street individually while moving the imaging unit relative to the wafer along the street, and a detection position determination unit that determines a detection position based on the captured images captured by the imaging unit for each imaging area. This makes it possible to automatically determine a detection position suitable for detecting cracks based on the captured images obtained by dividing and photographing the street.

[0011] A crack detection device according to another aspect of the present invention includes a detection optical system that detects reflected light through a condenser lens and outputs a detection signal, a scan control unit that moves the condenser lens relative to the wafer along the street while continuously irradiating the street with detection light from the condenser lens and detecting the reflected light by the detection optical system, and an imaging area determination unit that determines an imaging area based on the detection signal output from the detection optical system during the relative movement of the condenser lens, and the imaging control unit causes the imaging unit to capture an image of the imaging area determined by the imaging area determination unit. As a result, the detection position is determined based only on the captured image of the imaging area that is likely to include the detection position, so that the detection position can be determined efficiently in a short time.

[0012] In a crack detection device according to another aspect of the present invention, when the detection position determination unit determines the detection position, the alignment control unit moves the condenser lens relative to the wafer to align the condenser lens with the detection position, and when the condenser lens is aligned with the detection position, the crack is detected. This makes it possible to detect the crack position with high accuracy.

[0013] In another aspect of the present invention, the crack detection device includes a position information storage unit that stores detection position information indicating the relative position of the detection position with respect to a specific pattern repeatedly formed on the street when the detection position determination unit determines the detection position, and an alignment control unit aligns the focusing lens with the detection position based on the position of the known specific pattern and the detection position information stored in the position information storage unit. This makes it possible to determine the detection position based on the position of the known specific pattern, so that even if there are multiple detection positions, the detection position only needs to be determined once.

[0014] In a crack detection device according to another aspect of the present invention, the photographing unit photographs the street through a condenser lens. This makes it possible to obtain a photographed image through the condenser lens that emits detection light, and therefore it is possible to determine a detection position suitable for detecting cracks.

[0015] In another aspect of the present invention, the crack detection device includes an illumination light source that illuminates the street with illumination light in the same wavelength range as the detection light, and an image capturing unit captures an image of the street illuminated by the illumination light. This allows a correlation to be established between the reflection of the illumination light and the reflection of the detection light in the image capturing area, making it possible to determine a detection position suitable for detecting cracks.

[0016] A control method for a crack detection device for achieving the object of the present invention is a control method for a crack detection device that focuses detection light inside a wafer through a focusing lens and detects cracks formed inside a wafer along the streets of the wafer based on a detection signal detecting the reflected light of the detection light reflected by the wafer, the control method including an imaging step of photographing a street on which one or more patterns are formed, and a detection position determination step of determining a detection position for detecting a crack from the reflectance of the reflected light based on the captured image photographed in the imaging step. Effect of the Invention

[0017] The present invention can automatically determine a detection position where a crack position can be detected with high accuracy. [Brief description of the drawings]

[0018] [Figure 1] 1 is a configuration diagram showing an outline of a crack detection device according to a first embodiment. [Diagram 2] 1 is an enlarged view of a street of a wafer on which a crack position is to be detected by a crack detection device. [Diagram 3] 4 is an explanatory diagram for explaining the operation of each part of the crack detection optical system. FIG. [Figure 4] 4 is an explanatory diagram for explaining the operation of each part of the crack detection optical system. FIG. [Diagram 5] 4A to 4C are explanatory diagrams for explaining the operation of each part of the wafer observation optical system. [Figure 6] FIG. 11 is an explanatory diagram for explaining a flow of a photographed image acquisition process. [Figure 7] FIG. 11 is an explanatory diagram for explaining a flow of a detection position determination process. [Figure 8] 11 is an explanatory diagram for explaining determination of a detection position by a detection position determination unit; FIG. [Figure 9] FIG. 11 is an explanatory diagram for explaining a flow of a crack detection process for each detection position. [Figure 10] 4 is a flowchart showing a flow of a photographed image acquisition process and a detection position determination process performed by the crack detection device of the first embodiment. [Figure 11] 4 is a flowchart showing a flow of a crack detection process performed by the crack detection device of the first embodiment. [Figure 12] 13 is an explanatory diagram for explaining a photographing area detection process by the crack detection device of the second embodiment. FIG. [Figure 13] FIG. 11 is an explanatory diagram for explaining a flow of a photographing area determination process. [Figure 14] 13 is a flowchart showing a flow of a photographing area determination process and a photographed image acquisition process performed by a crack detection device of a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [Overall configuration of the crack detection device according to the first embodiment] Fig. 1 is a schematic diagram showing a configuration of a crack detection device 10 according to a first embodiment. Fig. 2 is an enlarged view of a street C of a wafer W that is a target for detecting crack positions by the crack detection device 10. Note that the X, Y and Z directions in the figure are mutually orthogonal, and among these, the X and Y directions are horizontal directions, and the Z direction is a vertical direction.

[0020] As shown in Figures 1 and 2, the crack detection device 10 detects the crack position (crack depth) of a crack formed inside the wafer W by irradiating detection light L1 along a street C onto a wafer W having a known laser processed area and a crack formed therein, and detecting reflected light L2 from the wafer W.

[0021] The crack detection device 10 is combined with a laser processing device (not shown) that forms a laser processed area inside the wafer W, but only the crack detection device 10 is shown here to avoid complicating the drawings. In addition, the crack position (crack depth) of a crack in this embodiment will be described as indicating the distance from the back surface of the wafer W to the bottom end position or top end position of the crack, but it may also be the distance from the front surface (detection light irradiation surface) of the wafer W.

[0022] The detection of the crack position by the crack detection device 10 is performed for each of a plurality of predetermined detection areas AR of the wafer W. Each detection area AR is set on a street C.

[0023] A group of patterns of various known shapes are formed on the street C (see FIG. 2). Before detecting the crack position in each detection area AR, the crack detection device 10 individually (sequentially) photographs a plurality of photographing areas BR along the street C in any detection area AR, and determines one or more detection positions Q suitable for detecting the crack position within this detection area AR, i.e., detection positions Q at which the crack position can be detected with high accuracy (see FIG. 2).

[0024] The detection area AR in this embodiment is, for example, an area where a group of patterns of the same shape are repeatedly formed on the street C, and is an area between a characteristic specific pattern P and the next specific pattern P. Note that, although a cross pattern is given as an example of the specific pattern P in this embodiment, the shape of the specific pattern P is not particularly limited. Also, although the streets C in the detection area AR are parallel to the X direction in this embodiment, they may be parallel to the Y direction.

[0025] The crack detection device 10 includes a movable stage 12 that holds a wafer W, an apparatus main body 14 (also called a measurement head), and a control device 16.

[0026] The movable stage 12 constitutes a relative movement mechanism for moving the apparatus main body 14 (the condenser lens 24, the camera 46, etc.) relative to the wafer W, and adsorbs and holds the wafer W from its back side. The movable stage 12 moves in the XY directions (corresponding to the vertical direction of the present invention) under the control of a control device 16 (stage control unit 50) described below. This allows each part of the apparatus main body 14 (the condenser lens 24, the camera 46, etc.) to be moved in the XY directions relative to the wafer W.

[0027] [Device body] The device body 14 includes a crack detection optical system 20 used to detect the crack position of a crack, and a wafer observation optical system 40 used to determine a detection position Q where the crack position is detected.

[0028] <Crack detection optical system> 3 and 4 are explanatory diagrams for explaining the operation of each part of the crack detection optical system 20. As shown in Fig. 3 and Fig. 4 and the above-mentioned Fig. 1, the crack detection optical system 20 includes a light source unit 21, a first illumination optical system 22, a half mirror 23, a condenser lens 24, an alignment mechanism 25, and a detection optical system 26.

[0029] The light source unit 21 includes a light source 28, a lens 29, and a limiting member 30. The light source 28 is activated when detecting the position of a crack, and emits detection light L1 (see FIGS. 3 and 4) used to detect the position of the crack. The lens 29 converts the detection light L1 emitted from the light source 28 into a parallel beam parallel to a main optical axis OP2 that is coaxial with the lens optical axis OP1 of the condenser lens 24.

[0030] The limiting member 30 is a light-shielding plate having openings 30a, 30b that can be opened and closed at a position eccentric in one direction from the main optical axis OP2 (see FIG. 3) and a position eccentric in the other direction (see FIG. 4). When detecting a crack position, the limiting member 30 selectively opens (closes) the openings 30a, 30b under the control of the control device 16 (device body control unit 52). This allows the detection light L1 to be selectively emitted along the main optical axis OP2 from the two openings 30a, 30b eccentric from the main optical axis OP2 (see FIG. 3 and FIG. 4). That is, emission of the detection light L1 along the main optical axis OP2 from a position eccentric in one direction from the main optical axis OP2 (see FIG. 3) and emission of the detection light L1 along the main optical axis OP2 from a position eccentric in the other direction from the main optical axis OP2 (see FIG. 4) are selectively performed.

[0031] The first illumination optical system 22 includes a relay lens 32, half mirrors 33 and 34, and a relay lens 35.

[0032] The half mirror 33 is disposed at the intersection of the main optical axis OP2 and an illumination axis OP4 of a second illumination optical system 41 described later. This half mirror 33 transmits part of the detection light L1 incident from the relay lens 32 and emits it toward the half mirror 34 when detecting a crack position, and reflects part of the illumination light L3 (see FIG. 5) incident from the second illumination optical system 41 toward the half mirror 34 when determining a detection position Q.

[0033] The half mirror 34 is disposed at the intersection of the lens optical axis OP1 and the main optical axis OP2. The half mirror 34 reflects a part of the detection light L1 incident from the half mirror 33 to the relay lens 35 when detecting the crack position, and reflects a part of the illumination light L3 incident from the half mirror 33 to the relay lens 35 when determining the detection position Q. The half mirror 34 also transmits a part of the reflected light L4 (see FIG. 5) of the illumination light L3 incident from the half mirror 23 described later, and emits it toward the photographing optical system 42.

[0034] The half mirror 23 is disposed between the relay lens 35 and the condenser lens 24 and at the intersection of the lens optical axis OP1 and the main optical axis OP3 of the detection optical system 26. The half mirror 23 transmits a part of the detection light L1 incident from the relay lens 35 and outputs it toward the condenser lens 24, and reflects a part of the reflected light L2 of the detection light L1 incident from the condenser lens 24 toward the detection optical system 26. In addition, as shown in FIG. 5 described later, the half mirror 23 transmits a part of the illumination light L3 incident from the relay lens 35 and outputs it toward the condenser lens 24, and transmits a part of the reflected light L4 incident from the condenser lens 24 and outputs it toward the photographing optical system 42.

[0035] The condenser lens 24 is provided at a position facing the wafer W. When detecting a crack position, the condenser lens 24 condenses the detection light L1 incident from the half mirror 23 inside the wafer W and emits reflected light L2 of the detection light L1 from the wafer W toward the half mirror 23. When determining a detection position Q, the condenser lens 24 condenses the illumination light L3 incident from the half mirror 23 onto the street C of the wafer W and emits reflected light L4 of the illumination light L3 from the wafer W toward the half mirror 23.

[0036] The alignment mechanism 25 is a known actuator that adjusts the Z-direction position (height position) of the condenser lens 24. When detecting the crack position, the alignment mechanism 25 scans the condenser lens 24 in the Z direction to scan the focal point of the detection light L1 that is focused inside the wafer W in the Z direction. In addition, when determining the detection position Q, the alignment mechanism 25 adjusts the Z-direction position of the condenser lens 24 so that the illumination light L3 is focused (imaged) on the street C.

[0037] The detection optical system 26 is disposed on a main optical axis OP3 branched from the lens optical axis OP1 by the half mirror 23, and includes a pair of relay lenses 37A, 37B, a half mirror 38, a pair of photodetectors 39A, 39B, and pinholes HA, HB.

[0038] The half mirror 38 transmits a part of the reflected light L2 incident from the relay lenses 37A and 37B and reflects the rest of the reflected light L2. Specifically, the half mirror 38 transmits a part of the reflected light L2 incident along a path eccentric to one side (the lower side in the figure) with respect to the main optical axis OP3 and outputs the part toward the photodetector 39A (see FIG. 3). The half mirror 38 also reflects a part of the reflected light L2 incident along a path eccentric to the other side (the upper side in the figure) with respect to the main optical axis OP3 toward the photodetector 39B (see FIG. 4).

[0039] The photodetectors 39A and 39B detect the reflected light L2 incident on the half mirror 38 along the main optical axis OP 3The light is received through pinholes HA and HB arranged at positions shifted from the main optical axis OP2 of the condenser lens 24. Specifically, the photodetectors 39A and 39B receive the reflected light L2 that has passed through different regions (see Patent Document 1) in the lens pupil region of the condenser lens 24 through the pinholes HA and HB. The photodetectors 39A and 39B then output detection signals sg1 and sg2 corresponding to the amount of reflected light L2 received to the control device 16. The magnitudes of the detection signals sg1 and sg2 output from the photodetectors 39A and 39B (the amount of reflected light L2 incident on each of them) change depending on the eccentric direction of the detection light L1 from the main optical axis OP2 and the presence or absence of a crack at the focusing point of the detection light L1 focused by the condenser lens 24, as described in Patent Document 1.

[0040] The configuration of each part of the crack detection optical system 20 is not particularly limited to that shown in FIG. 1, and for example, the configurations disclosed in Patent Document 1 may be used as appropriate.

[0041] <Wafer observation optical system> 5 is an explanatory diagram for explaining the operation of each part of the wafer observation optical system 40. As shown in FIG. 5 and the already-described FIG. 1, the wafer observation optical system 40 includes a second illumination optical system 41 and an imaging optical system 42.

[0042] The second illumination optical system 41 has an illumination axis OP4 that is perpendicular to the main optical axis OP2 and is combined with the main optical axis OP2 by the half mirror 33. The second illumination optical system 41 shares the half mirror 33 with the first illumination optical system 22, and includes an illumination light source 44 and a lens 45.

[0043] The illumination light source 44 emits illumination light L3 toward the half mirror 33 through a lens 45. For this illumination light L3, light in the same wavelength range (including approximately the same wavelength range) as that of the detection light L1 is selected in order to evaluate the reflectance of the detection light L1 (reflected light L2) when detecting the crack position.

[0044] The photographing optical system 42 shares the relay lens 35 and the half mirror 34 with the first illumination optical system 22 , and includes a camera 46 .

[0045] The relay lens 35 emits the reflected light L4 incident from the half mirror 23 toward the half mirror 34. The half mirror 34 transmits a portion of the reflected light L4 incident from the relay lens 35 and emits it toward the camera 46. The camera 46 is a known electronic camera that corresponds to the photographing unit of the present invention, and captures the reflected light L4, i.e., photographs each photographing area BR, when the detection position Q is determined, and outputs the photographed image 47 (image data) for each photographing area BR to the image storage unit 54 of the control device 16.

[0046] [Control device] 1 and 3 to 5, the control device 16 is configured by a calculation device such as a personal computer, and includes a calculation circuit configured by various processors and memories, etc. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., simple programmable logic devices (SPLD), complex programmable logic devices (CPLD), and field programmable gate arrays (FPGA)). The various functions of the control device 16 may be realized by one processor, or may be realized by multiple processors of the same type or different types.

[0047] The control device 16 executes a control program (not shown) to function as a stage control unit 50, an apparatus main body control unit 52, an image storage unit 54, a detection position determination unit 56, a position information storage unit 58, and a main control unit 60. Note that what is described as a "unit" of the control device 16 may also be a "circuit", a "device", or a "equipment". In other words, what is described as a "unit" may be composed of firmware, software, hardware, or a combination of these.

[0048] The stage control unit 50 controls the movement of the movable stage 12 in the XY directions (directions perpendicular to the lens optical axis OP1) under the control of the main control unit 60. This allows the device body 14 (the condenser lens 24, the camera 46, etc.) to move relative to the wafer W in the XY directions.

[0049] The device body control unit 52 controls the operation of each unit of the device body 14 under the control of the main control unit 60. For example, when determining the detection position Q, the device body control unit 52 controls the operation of the alignment mechanism 25, the illumination light source 44, and the camera 46. In addition, when detecting the crack position, the device body control unit 52 controls the operation of the alignment mechanism 25, the light source 28, the lens 29, the limiting member 30, and the photodetectors 39A and 39B.

[0050] The image storage unit 54, under the control of the main control unit 60, stores the captured image 47 output from the camera 46 when the detection position Q is determined. The detection position determination unit 56, under the control of the main control unit 60, determines the detection position Q (to be described in detail later), and outputs detection position information 62 indicating the detection position Q to the position information storage unit 58. The position information storage unit 58 stores the detection position information 62 input from the detection position determination unit 56.

[0051] The main control unit 60 comprehensively controls the operation of each unit of the crack detection device 10, and executes a photographed image acquisition process, a detection position determination process, and a crack detection process. In the photographed image acquisition process, the camera 46 individually photographs a plurality of photographed areas BR along a street C in any detection area AR to obtain photographed images 47. In the detection position determination process, a detection position Q in each detection area AR is determined based on the photographed image 47 of each photographed area BR. In the crack detection process, a crack position (such as the depth position of the bottom end of the crack) is detected at the detection position Q determined in the detection position determination process for each detection area AR.

[0052] [Image acquisition processing] 6 is an explanatory diagram for explaining the flow of the photographed image acquisition process. Note that a known alignment detection process is performed before the photographed image acquisition process, and the positional relationship between the camera 46 (lens optical axis OP1) and each part of the wafer W (detection area AR and specific pattern P) is known. Also, during the photographed image acquisition process, the illumination light source 44 is always turned on (it may be turned on in accordance with a photographed image acquisition instruction C(4) described later). Furthermore, it is assumed that the focal position of the condenser lens 24 is adjusted to be on the front surface (street C) of the wafer W.

[0053] As shown in FIG. 6 and already described FIG. 5, the main control unit 60 outputs to the stage control unit 50 an imaging area designation instruction C(1) that designates the first imaging area BR within an arbitrary detection area AR to the stage control unit 50.

[0054] Here, the position information of each detection area AR on the wafer W and the position coordinates of the specific pattern P in each detection area AR are known. In addition, since the size of each shooting area BR is determined by the angle of view of the camera 46, the number and positions of the shooting areas BR included in each detection area AR on the wafer W are also known. For this reason, the main control unit 60 outputs position information (position coordinates, etc.) of the first shooting area BR in any detection area AR to the stage control unit 50 as a shooting area designation instruction C(1).

[0055] When the stage control unit 50 receives the imaging area designation instruction C(1), it outputs a drive command C(2) to the movable stage 12. In response to this drive command C(2), the movable stage 12 moves in the XY directions, thereby aligning the first imaging area BR with the camera 46 (lens optical axis OP1). After completing the above-mentioned alignment, the stage control unit 50 outputs a movement completion notification C(3) to the main control unit 60.

[0056] Upon receiving the movement completion notification C(3), the main control unit 60 outputs a captured image acquisition instruction C(4) to the camera 46 and the image storage unit .

[0057] Upon receiving the photographed image acquisition instruction C(4), the camera 46 captures an image of the first photographing area BR on the street C through the condenser lens 24 and outputs the photographed image 47. Furthermore, upon receiving the photographed image acquisition instruction C(4), the image storage unit 54 executes a photographed image acquisition operation C(5) for acquiring the photographed image 47 from the camera 46, and then stores the acquired photographed image 47. Upon completing storage of the photographed image 47, the image storage unit 54 outputs an image storage completion notification C(6) to the main control unit 60.

[0058] When the main control unit 60 receives the image storage completion notification C(6), it outputs an image capture area designation instruction C(7) to the stage control unit 50 to designate the next image capture area BR in the detection area AR. This next image capture area BR is adjacent to the image capture area BR captured immediately before (see FIG. 2). Note that adjacent image capture areas BR in the detection area AR may partially overlap each other.

[0059] In response to the output of the photographing area designation instruction C(7), the output of the drive command C(2), the output of the movement completion notification C(3), the output of the photographed image acquisition instruction C(4), the output of the photographed image acquisition operation C(5), and the output of the image storage completion notification C(6) are executed. As a result, the alignment of the camera 46 with respect to the next photographing area BR, the photographing of the next photographing area BR by the camera 46, and the storage of the photographed image 47 in the image storage unit 54 are repeatedly executed. In this case, the stage control unit 50, the apparatus body control unit 52, and the main control unit 60 function as the photographing control unit of the present invention.

[0060] Thereafter, the above-described series of processes are repeatedly executed for each remaining photographing area BR in the detection area AR. As a result, photographing of each photographing area BR in the detection area AR is executed, that is, the detection area AR is divided and photographed along the street C. This completes the photographed image acquisition process.

[0061] [Detection position determination process] 7 is an explanatory diagram for explaining the flow of the detection position determination process. As shown in FIG. 7, when the photographed image acquisition process is completed, the main control unit 60 outputs a detection position determination instruction C(11) to the image storage unit 54 and the detection position determination unit 56.

[0062] Upon receiving the detection position determination instruction C(11), the image storage unit 54 executes an image output process C(12) for outputting the photographed image 47 for each photographing area BR to the detection position determination unit 56. Then, upon receiving the detection position determination instruction C(11), the detection position determination unit 56 determines one or more detection positions Q within the detection area AR based on each photographed image 47 input from the image storage unit 54.

[0063] 8 is an explanatory diagram for explaining the determination of the detection position Q by the detection position determination unit 56. Note that, the symbol Δd in the drawing indicates the width of the street C.

[0064] 8, the detection position determination unit 56 performs image analysis on the captured image 47 for each capturing area BR. Specifically, the detection position determination unit 56 repeatedly performs, for each captured image 47, a process of dividing the captured image 47 into a plurality of small regions SR along the street C (X direction) and a process of detecting a distribution of the reflectance of the illumination light L3 (reflected light L4) along the width direction (Y direction) of the street C for each small region SR.

[0065] The reflectance of the illumination light L3 is proportional to the pixel value (grayscale pixel value of a monochrome image) of the captured image 47. If a pattern is present at the irradiation position of the illumination light L3, the reflectance of the illumination light L3 will be high, and the pixel value will be high, and conversely, if no pattern is present, the reflectance of the illumination light L3 will be low, and the pixel value will be low. Also, as described above, since the illumination light L3 is light in the same wavelength range as the detection light L1, the distribution of the reflectance of the illumination light L3 essentially shows the distribution of the reflectance of the detection light L1.

[0066] As shown by reference symbol VIIIA in Fig. 8, when a region in which a pattern is formed and a region in which a pattern is not formed are mixed in the small region SR, the change (unevenness) in reflectance along the width direction of the street C and its gradient become large. Conversely, as shown by reference symbol VIIIB in Fig. 8, when the small region SR is composed only of a region in which a pattern is not formed or a region in which the same type of pattern is formed, the change (unevenness) in reflectance along the width direction of the street C and its gradient become small. As described above, when the detection light L1 is irradiated onto the small region SR in which regions with different reflectances of the detection light L1 are mixed, the detection light L1 is focused inside the wafer W across these multiple regions, which reduces the detection accuracy of the crack position.

[0067] Therefore, based on the distribution of reflectance for each small region SR in each captured image 47 (each captured area BR), the detection position determination unit 56 determines, as the detection position Q, a small region SR where the change in reflectance and its gradient along the width direction of the street C are small, i.e., a small region SR where the distribution of reflectance is approximately flat. For example, the detection position determination unit 56 determines, as the detection position Q, one or more small regions SR where the change in reflectance along the width direction of the street C (excluding both ends in the width direction) is equal to or less than a predetermined reference value (e.g., 10%) among each small region SR. Alternatively, the detection position determination unit 56 determines, as the detection position Q, a small region SR where the change in reflectance along the width direction of the street C is the smallest among each small region SR.

[0068] 7, the detection position determination unit 56 obtains detection position information 62 indicating the relative position of the detection position Q with respect to the specific pattern P as information indicating the position of the specific pattern P within the detection area AR, and executes a position information output process C(13) to output the detection position information 62 to the position information storage unit 58. As a result, the position information storage unit 58 stores the detection position information 62. Then, the detection position determination unit 56 outputs a determination completion notification C(14) of the detection position Q to the main control unit 60.

[0069] In this embodiment, a group of patterns of the same shape including the specific pattern P is formed in each detection area AR. Therefore, the positional relationship between the specific pattern P and the detection position Q is common in each detection area AR, so that common detection position information 62 can be used in the crack detection process for each detection area AR. Therefore, it is sufficient to perform the photographed image acquisition process and the detection position determination process only once each.

[0070] In addition, when a different pattern group is formed for each detection area AR, the photographed image acquisition process and the detection position determination process are repeatedly executed for each detection area AR to determine and store detection position information 62 indicating the position of the detection position Q (such as the position coordinates on the wafer W) for each detection area AR.

[0071] [Crack detection processing] Fig. 9 is an explanatory diagram for explaining the flow of the crack detection process for each detection position Q. As shown in Fig. 9, when the detection position determination process is completed, the main control unit 60 outputs an alignment instruction C (21) to the stage control unit 50 to align the lens optical axis OP1 of the condenser lens 24 with the detection position Q in the detection area AR. The alignment instruction C (21) includes known position coordinates of the specific pattern P in the detection area AR of the detection target.

[0072] When the stage control unit 50 receives an alignment instruction C(21), it outputs a detection position information delivery request C(22) to the position information storage unit 58, and executes a detection position information acquisition process C(23) to acquire the detection position information 62 output from the position information storage unit 58 in response to this detection position information delivery request C(22).

[0073] Next, the stage control unit 50 outputs a drive command C (24) to the movable stage 12 based on the detection position information 62 acquired from the position information storage unit 58 and the position of the specific pattern P in the detection area AR. In response to this drive command C (24), the movable stage 12 moves in the XY directions, thereby aligning the lens optical axis OP1 of the condenser lens 24 with the detection position Q. Then, the stage control unit 50 outputs a movement completion notification C (25) to the main control unit 60. In this case, the stage control unit 50 and the main control unit 60 function as the alignment control unit of the present invention.

[0074] When the main control unit 60 receives the movement completion notification C(25), it outputs a crack position detection instruction C(26) to the device body control unit 52. In response to this crack position detection instruction C(26), the device body control unit 52 drives each unit of the device body 14 to start a crack position detection operation C(27). In this case, the device body control unit 52 and the main control unit 60 function as an execution control unit that executes the detection operation C(27).

[0075] The device body control unit 52 turns on the light source 28, opens the opening 30a of the limiting member 30, and closes the opening 30b. The device body control unit 52 also operates the photodetectors 39A and 39B. As a result, as shown in FIG. 3, the detection light L1 emitted from the light source 28 is emitted along the main optical axis OP2 from a position eccentric in one direction with respect to the main optical axis OP2, passes through the first illumination optical system 22, etc., and is collected by the condenser lens 24 inside the detection position Q of the wafer W. Then, the reflected light L2 from the wafer W enters the detection optical system 26 via the condenser lens 24 and the half mirror 23, and is detected by the photodetectors 39A and 39B.

[0076] Next, the apparatus body control unit 52 drives the alignment mechanism 25 to scan the condenser lens 24 in the Z direction, thereby scanning in the Z direction the focal point of the detection light L1 that is focused inside the wafer W. As a result, detection of the reflected light L2 is performed by the photodetectors 39A and 39B for each scanning position of the focal point of the detection light L1, and detection signals sg1 and sg2 are output from the photodetectors 39A and 39B to the apparatus body control unit 52.

[0077] When the scanning of the focal point of the detection light L1 in the Z direction is completed, the apparatus body control unit 52 closes the opening 30a and opens the opening 30b of the limiting member 30. As a result, as shown in Fig. 4, the detection light L1 emitted from the light source 28 is emitted along the main optical axis OP2 from a position eccentric in the other direction with respect to the main optical axis OP2, passes through the first illumination optical system 22, etc., and is focused inside the detection position Q of the wafer W by the focusing lens 24. Then, the reflected light L2 from the wafer W is incident on the detection optical system 26 via the focusing lens 24 and the half mirror 23, and is detected by the photodetectors 39A and 39B.

[0078] Then, the apparatus body control unit 52 drives the alignment mechanism 25 to scan the condenser lens 24 in the Z direction, thereby scanning in the Z direction the focal point of the detection light L1 that is focused inside the wafer W. This causes the photodetectors 39A, 39B to detect the reflected light L2 for each scanning position of the focal point of the detection light L1, and the photodetectors 39A, 39B output detection signals sg1, sg2 to the apparatus body control unit 52. This completes the detection operation C (27).

[0079] When the detection work C(27) is completed, the device main body control unit 52 outputs a completion notification C(28A) of the crack detection process C(27) to the main control unit 60, and also executes a detection signal output process C(28B) to output detection signals sg1, sg2, which are detection data from the detection work C(27), to the main control unit 60.

[0080] The main control unit 60 receives the completion notification C (28A) from the device body control unit 52 and the detection signals sg1 and sg2, and executes detection of the crack position based on these detection signals sg1 and sg2. detection Since this method is a known technique (see Patent Document 1), a detailed description will be omitted here. With the above, the crack detection process at one detection position Q is completed.

[0081] Next, the main control unit 60 outputs an alignment instruction C (29) to align the lens optical axis OP1 of the condenser lens 24 with another detection position Q in the same detection area AR, or with a detection position Q in the next detection area AR. The above-mentioned series of processes are repeatedly executed in response to the output of this alignment instruction C (29), thereby detecting the crack position at the other detection position Q in the same detection area AR, or at the detection position Q in the next detection area AR. Thereafter, detection of the crack position is repeatedly executed for each detection position Q.

[0082] [Function of the crack detection device of the first embodiment] FIG. 10 is a flowchart showing the flow of the captured image acquisition process and the detection position determination process by the crack detection device 10 of the first embodiment (corresponding to a control method for the crack detection device of the present invention).

[0083] As shown in Fig. 10, when the wafer W is held on the movable stage 12 and the known alignment detection is completed, the main control unit 60 starts the photographed image acquisition process (step S1). As a result, as explained in Fig. 6, the following steps are repeatedly executed (step S6): specifying the photographed area BR in the detection area AR (step S2), aligning the camera 46 with the photographed area BR (step S3), photographing the photographed area BR by the camera 46 (step S4), and storing the photographed image 47 by the image storage unit 54 (step S5). As a result, the photographed image 47 of each photographed area BR in the detection area AR is stored in the image storage unit 54, and the photographed image acquisition process is completed. Note that step S4 corresponds to the photographing step of the present invention.

[0084] When the photographed image acquisition process is completed, the main control unit 60 starts the detection position determination process (step S7). As a result, as already explained in Fig. 7 and Fig. 8, the detection position determination unit 56 determines the detection position Q (detection position information 62) based on the photographed image 47 for each photographed area BR, and the position information storage unit 58 stores the detection position information 62 (step S8, which corresponds to the detection position determination step of the present invention). This completes the detection position determination process.

[0085] Fig. 11 is a flowchart showing the flow of the crack detection process by the crack detection device 10 of the first embodiment. As shown in Fig. 11, when the detection position determination process is completed, the main control unit 60 starts the crack detection process (step S11). As a result, as already described in Fig. 9, the following are repeatedly executed (step S16): specifying the detection position Q (step S12), obtaining the detection position information 62 (step S13), aligning the lens optical axis OP1 with the detection position Q (step S14), and detecting the crack position (step S15). As a result, the crack position is detected at one or more detection positions Q for each detection area AR. This completes the crack detection process.

[0086] [Effects of the first embodiment] As described above, in the crack detection device 10 of the first embodiment, based on the captured images 47 captured within the detection area AR for each capturing area BR, an area within the detection area AR where there is little change in the reflectance of the illumination light L3 (detection light L1), i.e., an area where the crack position can be detected with high accuracy, can be automatically determined as the detection position Q. Furthermore, by making the illumination light L3 light of the same wavelength range as the detection light L1, it is possible to create a correlation between the reflection of the illumination light L3 during the captured image acquisition process and the reflection of the detection light L1 during the crack detection process, so that a detection position Q more suitable for the crack detection process can be determined.

[0087] [Second embodiment] 12 is an explanatory diagram for explaining the photographing area detection process by the crack detection device 10 of the second embodiment. In the photographing image acquisition process of the first embodiment, all of the photographing areas BR within the detection area AR are photographed by the camera 46. In contrast, the crack detection device 10 of the second embodiment executes a photographing area determination process that determines in advance the photographing area BR within the detection area AR that is likely to include the detection position Q, and executes the photographing image acquisition process only in the photographing area BR determined in this photographing area determination process.

[0088] The crack detection device 10 of the second embodiment has basically the same configuration as the crack detection device 10 of the first embodiment, except that the photographing area determination process is executed before the photographed image acquisition process and the control device 16 also functions as the photographing area storage unit 70 (see FIG. 13). Therefore, the same reference numerals are used for components that are the same in function or configuration as those of the first embodiment, and their description will be omitted.

[0089] 12, in the photographing area determination process, under the control of the main control unit 60, the detection area AR is scanned along a scanning line SL parallel to the street C by the detection light L1 emitted from the condenser lens 24, while the reflected light L2 is detected by the detection optical system 26 (photodetectors 39A, 39B). As a result, the signal intensity distribution of the reflected light L2 along the scanning line SL is obtained.

[0090] Next, the main control unit 60 determines an imaging area BR that is likely to include the detection position Q based on the signal intensity distribution of the reflected light L2. For example, the main control unit 60 determines an area in the signal intensity distribution of the reflected light L2 where the signal intensity is low and the signal intensity gradient is small (area where the signal intensity is approximately flat) as the imaging area BR. In this case, the main control unit 60 functions as an imaging area determination unit of the present invention. Note that an area with a high signal intensity may be determined as the imaging area BR if the signal intensity gradient is small. This makes it possible to avoid a mixed area in the detection area AR where multiple areas with different reflectances of the detection light L1 are mixed, and to determine an area where the change in reflectance of the detection light L1 is small, i.e., an area where the detection position Q is likely to be included, as the imaging area BR.

[0091] Then, the main control unit 60 causes the photographing area storage unit 70 to store photographing area information 72 (scanning position information of the condenser lens 24, etc.) indicating the position of the determined photographing area BR, as shown in FIG. 13 described later.

[0092] 13 is an explanatory diagram for explaining the flow of the photographing area determination process. Note that a known alignment detection process is performed before the photographing area determination process, and the positional relationship between the condenser lens 24 (lens optical axis OP1) and each part (detection area AR) of the wafer W is known. Also, during the photographing area determination process, the focal position of the condenser lens 24 is adjusted to be on the front surface (street C) of the wafer W.

[0093] As shown in FIG. 13, before the captured image acquisition process, the main control unit 60 outputs a scan start position instruction C (31) to the stage control unit 50, which instructs the scan start position (position coordinates, etc.) of the detection light L1 in the detection area AR.

[0094] When the stage control unit 50 receives the scan start position instruction C (31), it outputs a drive command C (32) to the movable stage 12. In response to this drive command C (32), the movable stage 12 moves in the XY directions, thereby aligning the scan start position in the detection area AR with the lens optical axis OP1 of the condenser lens 24. Then, the stage control unit 50 outputs a movement completion notification C (33) to the main control unit 60.

[0095] When the main control unit 60 receives the movement completion notification C (33), it outputs a scan preparation instruction C (34) to the device body control unit 52. The device body control unit 52 that has received the scan preparation instruction C (34) executes the following: turning on the light source 28, opening one of the openings 30a, 30b of the limiting member 30, and operating the photodetectors 39A, 39B. As a result, the detection light L1 emitted from the light source 28 passes through the first illumination optical system 22 and the like and is condensed by the condenser lens 24 at the scan start position in the detection area AR. In addition, the reflected light L2 reflected at the scan start position enters the detection optical system 26 via the condenser lens 24 and the half mirror 23, and is detected by the photodetectors 39A, 39B. Then, the photodetectors 39A, 39B execute a signal output process C (35) that outputs detection signals sg1, sg2 to the device body control unit 52.

[0096] Next, the apparatus body control unit 52 executes a scan preparation completion notification C (36) to the main control unit 60 and a signal intensity value output process C (37) for outputting the signal intensity value of the reflected light L2 based on the detection signals sg1 and sg2.

[0097] Upon receiving the scan preparation completion notification C (36), the main control unit 60 outputs a scan end position instruction C (38) to the stage control unit 50 that indicates the scan end position (position coordinates, etc.) of the detection light L1 within the detection area AR.

[0098] When the stage control unit 50 receives the scan end position instruction C (38), it outputs a drive command C (39) to the movable stage 12. When the movable stage 12 receives this drive command C (39) and moves in the X direction, the focal point of the detection light L1, which is focused at the scan start position by the focusing lens 24, moves along the street C (scanning line SL) toward the scan end position. As a result, while scanning the detection light L1 along the street C in the detection area AR, the detection of the reflected light L2 by the photodetectors 39A and 39B and the signal output process C (35) and the signal intensity value output process C (37) by the device body control unit 52 are continuously executed. In this case, the stage control unit 50, the device body control unit 52, and the main control unit 60 function as the scan control unit of the present invention.

[0099] Then, when the focal point of the detection light L1 reaches the scan end position, the stage control unit 50 outputs a movement completion notification C(40) to the main control unit 60. In response to this movement completion notification C(40), the main control unit 60 outputs a scan end instruction C(41) to the apparatus body control unit 52.

[0100] Upon receiving the scan end instruction C (41), the device body control unit 52 turns off the light source 28 and stops the operation of the photodetectors 39A and 39B. Thereafter, the device body control unit 52 outputs a scan end notification C (42) to the main control unit 60.

[0101] Upon receiving the scan end notification C (42), the main control unit 60 calculates the signal intensity distribution of the reflected light L2 as shown in FIG. 12, based on the signal intensity values ​​of the reflected light L2 continuously input from the device body control unit 52 during scanning with the detection light L1. Next, the main control unit 60 determines one or more shooting areas BR based on the signal intensity distribution of the reflected light L2, and generates shooting area information 72 indicating the positions of the shooting areas BR. Then, the main control unit 60 executes a shooting area information output process C (43) that outputs the shooting area information 72 to the shooting area storage unit 70. As a result, the shooting area information 72 is stored in the shooting area storage unit 70.

[0102] The photographed image acquisition process of the second embodiment is basically the same as the photographed image acquisition process of the first embodiment shown in Fig. 6. However, in the photographed image acquisition process of the second embodiment, the main control unit 60 issues photographing area designation instructions C(1), C(7) based on the photographing area information 72 acquired from the photographing area storage unit 70. As a result, in the photographed image acquisition process of the second embodiment, only the photographing area BR determined in the photographing area determination process is photographed by the camera 46.

[0103] It should be noted that the detection position determination process and the crack detection process in the second embodiment are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0104] [Function of the crack detection device of the second embodiment] FIG. 14 is a flowchart showing the flow of the photographing area determination process and the photographed image acquisition process performed by the crack detection device 10 of the second embodiment.

[0105] As shown in Fig. 14, when the wafer W is held on the movable stage 12 and known alignment detection and the like are completed, the main control unit 60 starts the imaging area determination process (step S21). This starts the alignment of the condenser lens 24 with respect to the scanning start position in the detection area AR (step S22), the emission of the detection light L1 from the condenser lens 24 to the scanning start position, and the detection of the reflected light L2 by the photodetectors 39A and 39B (step S23), as described above in Fig. 13. Next, the scanning of the detection light L1 along the street C in the detection area AR is started (step S24, NO in step S25).

[0106] When the scanning of the detection light L1 is completed (YES in step S25), the main control unit 60 determines the photographing area BR, and the photographing area storage unit 70 stores the photographing area information 72 (step S26). This completes the photographing area determination process.

[0107] When the photographing area determination process is completed, the main control unit 60 starts the photographed image acquisition process (step S27). The main control unit 60 acquires the photographing area information 72 from the photographing area storage unit 70 and determines the photographing area BR in which the photographed image acquisition process is performed (step S28).

[0108] Thereafter, the following steps are repeatedly executed (step S33): specifying the photographing area BR based on the photographing area information 72 (step S29), aligning the camera 46 with respect to the photographing area BR (step S30), photographing the photographing area BR by the camera 46 (step S31), and storing the photographed image 47 by the image storage unit 54 (step S32). As a result, only the photographed image 47 of the photographing area BR determined in the photographing area determination process is stored in the image storage unit 54. This makes it possible to reduce the number of photographing areas BR compared to the first embodiment. As a result, the number of cycles of a series of photographing processes consisting of relative movement, stopping, and photographing of the camera 46 in the photographed image acquisition process can be reduced, thereby shortening the time required for the photographed image acquisition process.

[0109] Although not shown in the figures, when the photographed image acquisition process is completed, the detection position determination process and the crack detection process are executed in the same manner as in the first embodiment. Here, in the detection position determination process of the second embodiment, the detection position Q is determined based only on the photographed image 47 that captures the photographed area BR that is highly likely to include the detection position Q, so that the detection position Q can be determined more quickly and efficiently than in the first embodiment.

[0110] As described above, in the second embodiment, the shooting area determination process is executed before the shooting image acquisition process to narrow down in advance the shooting area BR that is likely to include the detection position Q, thereby making it possible to determine the detection position Q in a shorter time and more efficiently than in the first embodiment.

[0111] [others] In each of the above embodiments, the detection area AR is set to an area on the street C where a group of patterns of the same shape are repeatedly formed and between two specific patterns P, but the position and range of the detection area AR are not particularly limited as long as it is on the street C where a laser processing area is formed. The present invention can also be applied to cases where a group of patterns of the same shape are not repeatedly formed on the street C. In this case, the photographed image acquisition process (photographed area determination process) and the detection position determination process are repeatedly executed for each detection area AR to determine the detection position Q for each detection area AR.

[0112] In each of the above embodiments, the camera 46 (wafer observation optical system 40) photographs the shooting area BR through the focusing lens 24, but the wafer observation optical system 40 may be fixed to the outside of the device main body 14 or may be provided separately from the device main body 14.

[0113] In each of the above embodiments, the focusing lens 24, the camera 46, etc. are moved in the XY directions relative to the wafer W by moving the movable stage 12 in the XY directions, but instead of moving the movable stage 12 in the XY directions, the device main body 14 may be moved in the XY directions.

[0114] In each of the above embodiments, the second illumination optical system 41 is provided in the wafer observation optical system 40, but when the detection light L1 and the illumination light L3 are light in the same wavelength region, the imaging area BR may be illuminated using the light source 28 by providing a mechanism for retracting the limiting member 30 from the main optical axis OP2 or by providing an opening for illumination that can be opened and closed in the center of the limiting member 30. In this case, the second illumination optical system 41 can be omitted.

[0115] In the above embodiments, the detection area AR is photographed in parts, but the entire detection area AR may be photographed at once. That is, the number of photographing areas BR may be one. In this case, it is preferable to use a camera 46 with a wide angle of view and high resolution. In this case, the entire street C may be set as the detection area AR.

[0116] In each of the above embodiments, light in the same wavelength range as the detection light L1 is selected as the illumination light L3, but light in a wavelength range different from that of the detection light L1 may be used. Even in this case, it is preferable that the wavelength range of the illumination light L3 is within a range in which the reflectance of the detection light L1 can be regarded as having the same tendency (within a range that does not affect the crack detection process). [Explanation of symbols]

[0117] 10...crack detection device, 12...movable stage, 14...device body, 16...control device, 20...crack detection optical system, 21...light source unit, 22...first illumination optical system, 23...half mirror, 24...condenser lens, 25...alignment mechanism, 26...detection optical system, 28...light source, 29...lens, 30...limiting member, 32...relay lens, 33, 34...half mirror, 35...relay lens, 37A, 37B...relay lens, 38...half mirror, 39A...photodetector, 39B...photodetector, 40...wafer observation optical system, 41...second illumination optical system, 42...imaging optical system, 44...illumination light source, 45...lens , 46... camera, 47... captured image, 50... stage control section, 52... device main body control section, 54... image storage section, 56... detection position determination section, 58... position information storage section, 60... main control section, 62... detection position information, 70... shooting area storage section, 72... shooting area information, AR... detection area, BR... shooting area, HA, HB... pinhole, L1... detection light, L2... reflected light, L3... illumination light, L4... reflected light, OP1... lens optical axis, OP2, OP3... main optical axis, OP4... illumination axis, P... specific pattern, Q... detection position, SL... scanning line, SR... small area, W... wafer, sg1, sg2... detection signal

Claims

1. 1. A crack detection device for detecting a crack formed inside a wafer along a street of the wafer based on a detection signal obtained by irradiating a detection light onto the wafer and detecting a reflected light of the detection light reflected by the wafer, comprising: an image capturing unit that captures an image of the street on which one or more patterns are formed; a detection position determination unit that determines, based on the captured image captured by the image capture unit, a position where a change in reflectance of the reflected light in the width direction of the street is equal to or smaller than a predetermined reference value as a detection position for detecting the crack from the reflectance of the reflected light; A crack detection device comprising:

2. an imaging control unit that causes the imaging unit to individually capture images of a plurality of imaging areas along the street while moving the imaging unit along the street relative to the wafer; The crack detection device according to claim 1 , wherein the detection position determination unit determines the detection position based on an image captured by the photographing unit for each of the photographing areas.

3. a lens for irradiating the wafer with the detection light; a detection optical system that detects the reflected light and outputs a detection signal; a scan control unit that continuously performs, while moving the lens relative to the wafer along the street, irradiation of the detection light from the lens onto the street and detection of the reflected light by the detection optical system; an imaging area determination unit that determines the imaging area based on the detection signal output from the detection optical system during the relative movement of the lens; Equipped with The crack detection device according to claim 2 , wherein the photography control unit causes the photography unit to photograph the photography area determined by the photography area determination unit.

4. a lens for irradiating the wafer with the detection light; an alignment control unit that, when the detection position determination unit has determined the detection position, moves the lens relative to the wafer to align the lens with the detection position; Equipped with The crack detection device according to claim 1 , wherein the crack is detected when the lens is aligned with the detection position.

5. a position information storage unit configured to store, when the detection position determination unit has determined the detection position, detection position information indicating a relative position of the detection position with respect to a specific pattern repeatedly formed on the street, The crack detection device described in claim 4, wherein the alignment control unit aligns the lens with the detection position based on the known position of the specific pattern and the detection position information stored in the position information memory unit.

6. a lens for irradiating the wafer with the detection light; The crack detection device according to claim 1 , wherein the photographing unit photographs the street through the lens.

7. an illumination light source that illuminates the street with illumination light having the same wavelength range as the detection light; The crack detection device according to claim 1 , wherein the photographing unit photographs the street illuminated by the illumination light.

8. 1. A control method for a crack detection device for detecting a crack formed inside a wafer along a street of the wafer based on a detection signal obtained by irradiating a wafer with a detection light and detecting a reflected light of the detection light reflected by the wafer, comprising: an imaging step of imaging the street on which one or more patterns are formed; a detection position determination step of determining, based on the captured image captured in the photographing step, a position where a change in reflectance of the reflected light in the width direction of the street is equal to or less than a predetermined reference value as a detection position for detecting the crack from the reflectance of the reflected light; A method for controlling a crack detection device having the above structure.

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