JP2014207354A - Edge detection apparatus - Google Patents

Abstract

An edge detection device capable of clearly recognizing a boundary portion between a kerf region and a laser groove region. An edge detection device includes a laser groove formed by irradiating a laser beam along a planned division line and a laser formed by grinding along the laser groove with a grinding blade SP1. The semiconductor wafer 10 having the kerf 24 deeper than the groove 22 is arranged between the CCD 40 that images the division line 16, the laser groove 22, and the kerf 24 from above, and the division line 16 and the CCD 40. An objective lens 30 having a depth of field shallower than that of the kerf 24; a first illumination device 50 that irradiates the objective lens 30 with light from the same direction as the observation optical axis connecting the objective lens 30 and the CCD 40; And a second illumination device 58 that irradiates the semiconductor wafer 10 with light from an oblique direction. [Selection] Figure 7

Description

  The present invention relates to an edge detection apparatus for performing a kerf check with respect to an edge detection apparatus.

  A structure in which a low dielectric constant insulating film (Low-k film) using a low dielectric constant (Low-k) material is formed as an interlayer insulating film on the surface of a semiconductor substrate in order to increase the processing capability of a semiconductor device such as an IC or LSI. There are known semiconductor wafers. However, since the low dielectric constant insulating film has low mechanical strength, there is a problem that the low dielectric constant insulating film peels off when the semiconductor wafer is diced with a grinding blade.

  In order to solve this problem, the low dielectric constant insulating film is removed by irradiating the laser beam to the division line without using the grinding blade, and then the grinding blade is positioned in the laser groove formed by the laser light. A method of cutting and dividing a wafer is employed.

  Even in the method of dividing a semiconductor wafer with a laser beam and a grinding blade, a kerf check is required to confirm the situation such as a positional deviation between a groove (kerf) cut by the grinding blade and a division planned line. Proposals have been made to check the kerf in the laser groove.

  In Patent Document 1, the amount of light is set so that the kerf portion formed by the grinding blade is white and the surrounding laser grooving portion is black, and the division line after dicing by the grinding blade is imaged by the imaging means, and the captured image The edge position of the laser grooving area and the edge position of the kerf area are extracted by edge recognition processing for the image, and a histogram is created regarding the luminance distribution of the image data of each pixel in the laser grooving area of the predetermined range where the edge position is extracted. The brightest first peak region is extracted from the laser grooving region in a predetermined range based on the luminance distribution in the created histogram, and the portion that continues to the edge position of the kerf region in the extracted first peak region is chipped A chipping detection device that is recognized as a region is described.

  In Patent Document 2, the amount of light is set so that the kerf portion formed by the grinding blade is white and the surrounding laser grooving portion is black, and the division planned line after dicing by the grinding blade is imaged by the imaging means, and the captured image A candidate line as a grooving edge line or a kerf edge line is extracted by edge recognition processing for, and the nature of each extracted candidate line is determined based on information of the original image, and a plurality of candidate lines are determined as grooving edge lines according to the determination result, Cases are divided into combination candidate lines that form a set of kerf edge lines, kerf edge lines, and grooving edge lines, and the difference in physical characteristics between the laser grooving part and the kerf part is determined as a judgment factor from among the combination candidate lines that are divided into cases Probable one based on the information of the original image Determining the combination candidate line describes an edge detection device to identify the kerf edge line from the candidate line.

JP 2009-021375 A JP 2010-010445 A

  In the techniques described in Patent Documents 1 and 2, the amount of light is set so that the kerf region formed by the grinding blade is white and the surrounding laser grooving region is black.

  However, the state of the bottom surface of the kerf formed on the semiconductor wafer differs depending on the use situation of the grinding blade. Therefore, even if the light amount is adjusted, the kerf region may not be uniform white, and the contrast at the boundary between the kerf region and the laser grooving region may be unclear. Even if image processing is performed using unclear image data, an appropriate detection result cannot be obtained.

  In addition, when a semiconductor wafer having a laser grooving region is ground with a grinding blade, there are a half cut in which semiconductor wear is ground halfway and a full cut in which all semiconductor wear is ground.

  In the case of half cut, the bottom surface of the kerf is formed in the semiconductor wafer. If the techniques described in Patent Documents 1 and 2 are applied to a half-cut semiconductor wafer, the kerf region formed by the grinding blade is whitened by adjusting the amount of light, and the surrounding laser grooving region is It can be blackened.

  On the other hand, in the case of full cut, the bottom surface of the kerf is not formed in the semiconductor wafer. Therefore, even if the amount of light is adjusted, there is no reflected light from the bottom surface of the kerf, so the kerf region becomes black. The surrounding laser grooving area is also black. Therefore, even if the techniques described in Patent Documents 1 and 2 are applied, the boundary between the kerf region and the laser grooving region cannot be recognized. Therefore, an appropriate detection result cannot be obtained even if image processing is performed based on the obtained image data.

  In order to solve such a problem, an object of the present invention is to provide an edge detection device capable of clearly recognizing a boundary portion between a kerf region and a laser groove region.

  An edge detection apparatus according to an aspect of the present invention includes a laser groove formed by irradiating a laser beam along a predetermined division line, and the laser groove formed by grinding with a grinding blade along the laser groove. A semiconductor wafer having a deeper kerf is disposed between an imaging means for imaging the division line, the laser groove, and the kerf from above, and between the division line and the imaging means. An objective lens having a depth of field shallower than the depth of the kerf, a first illumination device that irradiates the objective lens with light from a direction coaxial with an observation optical axis connecting the objective lens and the imaging means, and the observation optical axis With respect to the second illumination device for irradiating the semiconductor wafer with light from an oblique direction.

  Preferably, the objective lens is arranged so that a central axis of the objective lens is located at a center in a width direction of the kerf.

  Preferably, the amount of light from the oblique direction with respect to the planned division line is larger than that from the direction perpendicular to the planned division line in the second illumination device.

  Preferably, the second illumination device is configured by an illumination device arranged in a ring shape surrounding the observation optical axis.

  Preferably, the objective lens has a depth of field of 2 to 10 μm.

  Preferably, a light amount control unit that controls a light amount of the first illumination device and a light amount of the second illumination device, an area of the kerf from an image obtained by the imaging unit, an area of the laser groove, And an image processing unit for detecting a region of the planned division line.

  It should be noted that the light / dark recognition of the kerf, the groove, and the line to be divided can be detected by using an image recognition means by CCD or an image processing means.

  The edge detection apparatus of the present invention can clearly recognize the boundary between the kerf region and the laser groove region.

The perspective view of a semiconductor wafer. The fragmentary sectional view of a semiconductor wafer. The fragmentary sectional view of the semiconductor wafer in which the laser groove was formed. The fragmentary sectional view of the semiconductor wafer half-cut. The fragmentary sectional view of the semiconductor wafer cut full. The fragmentary sectional view of another semiconductor wafer by which full cut was carried out. The schematic block diagram of an edge detection apparatus. Schematic which shows the relationship between the depth of field of an objective lens, and the laser groove and kerf depth of a half-cut semiconductor wafer. Explanatory drawing which shows the result of having imaged the imaging area by the imaging means. Schematic which shows the relationship between the depth of field of an objective lens, and the laser groove and kerf depth of a half-cut semiconductor wafer. Explanatory drawing which shows the result of having imaged the imaging area by the imaging means. Explanatory drawing which shows the result of having imaged the imaging area | region of the semiconductor wafer fully cut by the imaging means. The schematic block diagram which shows the positional relationship of a 2nd illuminating device and a fully cut semiconductor wafer. Explanatory drawing which shows the result of having imaged the imaging area by the imaging means. The schematic block diagram which shows the positional relationship of a 2nd illuminating device and a half-cut semiconductor wafer. Explanatory drawing which shows the result of having imaged the imaging area by the imaging means. The schematic block diagram which shows the positional relationship of a 2nd illuminating device and a half-cut semiconductor wafer. Explanatory drawing which shows the result of having imaged the imaging area by the imaging means. The schematic block diagram which shows the positional relationship of a 2nd illuminating device and a half-cut semiconductor wafer. The schematic block diagram of the dicing apparatus with which the edge detection apparatus was attached. A flow showing a sequence of image processing. The flow which shows the sequence of the 1st image processing. The flow which shows the sequence of the 2nd image processing. 10 is a flow showing a third image processing sequence. 10 is a flow showing a fourth image processing sequence. The flow which shows the sequence of 5th image processing.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Here, in the drawing, portions indicated by the same symbols are similar elements having similar functions.

  In addition, since dicing is performed on the wafer in which the laser groove is formed by laser processing, and in addition to this, the street is covered with a low-reflectance material. Be targeted.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Here, in the drawing, portions indicated by the same symbols are similar elements having similar functions.

  The basic concept of the edge detection apparatus of this embodiment will be described with reference to the drawings. FIG. 1 is a perspective view showing the appearance of the semiconductor wafer 10. A semiconductor wafer 10 shown in FIG. 1 includes a substrate 12 made of Si, an element region 14 formed two-dimensionally on the substrate 12, and a division line 16 formed to cut the element region 14 into chips. Consists of. A dicing tape 18 is attached to the back surface of the semiconductor wafer 10.

  FIG. 2 is a partially enlarged view of the semiconductor wafer 10. As shown in FIG. 2, a low dielectric constant insulating film (Low-k film) 20 is formed on the surface of the substrate 12. In the element region 14, metal wiring is formed using the semiconductor element and the low dielectric constant insulating film 20 as an interlayer insulating film. The semiconductor wafer 10 shown in FIG. 2 is irradiated with laser light along the planned division line 16.

  As shown in FIG. 3, the low dielectric constant insulating film 20 is dissolved and vaporized by the heat of the laser beam, and the low dielectric constant insulating film 20 in the region of the division planned line 16 is removed. By irradiating the laser beam, a laser groove 22 is formed on the surface of the division line 16 of the substrate 12. Since the surface of the laser groove 22 is melted by the heat of the laser light, the surface of the laser groove 22 is in a rough state compared to the surface of the scheduled division line 16. The depth of the laser groove 22 is about 5 to 15 μm from the surface of the substrate 12. The semiconductor wafer 10 is irradiated with laser light by a laser processing machine or the like.

  As shown in FIG. 4, the semiconductor wafer 10 on which the laser groove 22 is formed is half-cut (step cut) by the grinding blade SP1 along the scheduled division line 16. The grinding blade SP1 is aligned with the region of the laser groove 22, and the grinding blade SP1 grinds the substrate 12 from the surface of the substrate 12 to a predetermined depth deeper than the depth of the laser groove 22. A kerf 24 is formed on the substrate 12. The depth of the kerf 24 is generally about 40 to 50 μm or about 1/2 to 1/3 of the thickness of the substrate 12.

  As shown in FIG. 5, the semiconductor wafer 10 on which the kerf 24 is formed is fully cut by the grinding blade SP2 having a thickness smaller than the grinding blade SP1 along the kerf 24 of the division line 16. The grinding blade SP2 is aligned with the region of the kerf 24, and the grinding blade SP2 grinds the substrate 12 until it reaches the dicing tape 18 on the back surface. A kerf 29 is further formed on the substrate 12.

  In the aspect of FIG. 5, the half-cut semiconductor wafer 10 is fully cut, but the semiconductor wafer 10 may be fully cut without being half-cut.

  As shown in FIG. 6, the semiconductor wafer 10 on which the laser groove 22 is formed is fully cut by the grinding blade SP2 along the scheduled division line 16. The grinding blade SP2 is aligned with the approximate center of the division line 16. The grinding blade SP2 grinds the substrate 12 until it reaches the dicing tape 18 on the back surface, whereby a kerf 29 is formed on the substrate 12.

  Next, the edge detection apparatus according to the present embodiment will be described with reference to FIG. The edge detection apparatus 1 illuminates an imaging area, an objective lens 30 that is disposed opposite to the division line 16 of the semiconductor wafer 10 that is an imaging area, a CCD 40 that is an imaging means for imaging the imaging area via the objective lens 30, and the imaging area. The first lighting device 50 and the second lighting device 58 are provided.

  The observation optical axis indicated by a two-dot difference line connecting the objective lens 30 and the CCD 40 is substantially perpendicular to the planned division line 16 that is the imaging region. That is, the division line 16 is observed from directly above.

  The light emitted from the first illumination device 50 passes through the illumination lens 52 and is reflected by the mirror 54. Further, the light is reflected toward the objective lens 30 by the half mirror 56 disposed at an inclination of about 45 ° with respect to the observation optical axis. That is, the light from the first illumination device 50 is irradiated to the objective lens 30 from the coaxial direction with respect to the observation optical axis connecting the objective lens 30 and the CCD 40. The light from the first lighting device 50 is irradiated from the vertical direction to the imaging region.

  The light is irradiated onto the imaging region through the objective lens 30, and the light reflected by the imaging region passes through the objective lens 30 again, then passes through the half mirror 56, and is imaged by the CCD 40. The image picked up by the CCD 40 is output to the monitor 60. The operator can observe the state of the captured division line 16 from the image output to the monitor 60.

  The edge detection apparatus 1 according to the present embodiment includes an objective lens 30 having a depth of field DOF 2 that is shallower than the depth of the kerf 24. As will be described later, the boundary between the region of the kerf 24 and the region of the laser groove 22 can be observed.

  The second illumination device 58 irradiates the semiconductor wafer 10 with light from an oblique direction with respect to the observation optical axis connecting the objective lens 30 and the CCD 40. As the second illumination device 58, for example, ring illumination, illumination in which a plurality of light sources are arranged in a ring shape, or the like can be used. As will be described later, the boundary between the regions of the kerfs 24 and 29 and the region of the laser groove 22 can be observed.

  The light emitted from the second illumination device 58 to the imaging area is reflected by the imaging area, passes through the objective lens 30, and is then imaged by the CCD 40. The image picked up by the CCD 40 is output to the monitor 60. The operator can observe the state of the captured division line 16 from the image output to the monitor 60.

  The edge detection apparatus 1 further includes a control unit 80, and the control unit 80 includes an image processing unit 82 and a light amount control unit 84. The image processing unit 82 performs kerf edge detection processing from the captured image data. The light quantity control unit 84 controls the intensity (light quantity) of light emitted from the first illumination device 50 and the intensity (light quantity) of light emitted from the second illumination apparatus 58. The first illumination device 50 and the second illumination device 58 are selectively used according to the state of the imaging region of the semiconductor wafer 10.

  In the edge detection apparatus 1 of the present embodiment, a diaphragm 32 is further installed between the half mirror 56 and the objective lens 30. The depth of field can be changed by changing the aperture 32. By opening the aperture 32, the depth of field can be reduced.

  Next, the detection of the kerf edge of the half-cut semiconductor wafer 10 shown in FIG. 4 will be described. A semiconductor having a laser groove 22 formed by irradiating laser light along the division line 16 and a kerf 24 deeper than the laser groove 22 formed by grinding along the laser groove 22 with the grinding blade SP1. The kerf edge is detected for the wafer 10.

  The inventor has intensively studied a method for detecting the edge of the kerf 24 formed in the laser groove 22 by irradiating light from the illumination device in the vertical direction to the imaging region. As a result, even if the amount of light is adjusted depending on the state of the bottom surface of the kerf 24, the region of the kerf 24 does not become a uniform white color, and the contrast at the boundary between the region of the kerf 24 and the region of the laser groove 22 is unclear. I found out that it might be.

  A general objective lens used for kerf check and arranged in an imaging region will be described. FIG. 8 shows the relationship between the depth of field of the objective lens 130 and the depths of the laser groove 22 and the kerf 24. In order to clearly observe the laser groove 22 and the kerf 24, the objective lens 130 has a deep depth of field DOF1. That is, the depth of field DOF1 of the objective lens 130 is set in a range including the laser groove 22 and the bottom surface of the kerf 24. The light emitted from the illumination device 150 passes through the illumination lens 152 and is reflected by the mirror 154. Further, the light is reflected toward the objective lens 130 by the half mirror 156 disposed at an inclination of about 45 ° with respect to the observation optical axis.

  Light is applied to the imaging region from the illumination device 150 via the objective lens 130, and the reflected light is observed by the imaging device. The surface of the laser groove 22 is rough. Therefore, the irradiated light is irregularly reflected, so that the region of the laser groove 22 is observed as black. On the other hand, the surface (bottom surface) of the region of the kerf 24 is a smooth surface 26. For this reason, the irradiated light is uniformly reflected, and the area of the kerf 24 is observed as white.

  However, in the region of the kerf 24 formed by grinding of the grinding blade, a non-smooth surface, that is, a so-called saw mark 28 may be formed on the bottom surface of the kerf 24 depending on the use situation of the grinding blade. The saw mark 28 is a cutting mark formed on the bottom surface of the kerf 24 along the longitudinal direction of the kerf 24, and is a horizontally long protrusion or groove. At the saw mark 28, the irradiated light is irregularly reflected.

  When the objective lens 130 described above is used, light is emitted from the illumination device 150 to the imaging region, and a part of the planned division line 16 is imaged by the imaging means, the result shown in FIG. 9 is obtained. Even when focusing on the edge of the kerf 24, the objective lens 130 has the deep depth of field DOF1, so the saw mark 28 on the bottom surface of the kerf 24 is also within the range of the depth of field DOF1. As a result, as shown in FIG. 9, the kerf 24 including the laser groove 22, the smooth surface 26, and the saw mark 28 is clearly observed.

  In FIG. 9, the laser groove 22 and the saw mark 28 are illustrated in different colors in order to explain. However, since the region of the laser groove 22 and the saw mark 28 in the kerf 24 become black of the same color, it is difficult to specify the image by processing the boundary between the laser groove 22 and the kerf 24.

  Therefore, the inventor has found that the above-described problem can be solved by using the objective lens 30 having the depth of field DOF2 shallower than the depth of the kerf 24. FIG. 10 shows the relationship between the depth of field of the objective lens 30 and the depth of the laser groove 22 and the kerf 24. The depth of field DOF2 of the objective lens 30 is set so as to be a range in which the laser groove 22 is included and the bottom surface of the kerf 24 is not included.

  When the objective lens 30 described above is used, the imaging area is irradiated with light from the first illumination device 50, and a part of the planned division line 16 is imaged by the imaging means, the result shown in FIG. 11 is obtained. The saw mark 28 and the smooth surface 26 in the kerf 24 are outside the range of the depth of field DOF2 of the objective lens 30. Therefore, a focus shift occurs on the bottom surface of the kerf 24. That is, the bottom surface of the kerf 24 is not clearly imaged. Therefore, the area of the saw mark 28 that looks black and the area of the smooth surface 26 that looks white are averaged and visually recognized. As a result, the entire area of the kerf 24 is visible with a uniform light gray. Since the area of the black laser groove 22 is dark and the area of the gray kerf 24 is viewed brightly, the boundary between the area of the laser groove 22 and the area of the kerf 24 can be clearly viewed. Further, by increasing the amount of light of the first illumination device 50, the luminance value of the kerf 24 region itself is shifted to the white side as compared with the laser groove 22. Therefore, the boundary between the laser groove 22 and the kerf 24 can be made clearer.

  In addition, by controlling the intensity of light emitted from the first illumination device 50 by the light quantity control unit 84, the region of the laser groove 22 can be made black and the region of the kerf 24 can be made light gray.

  The objective lens 30 preferably has a depth of field DOF2 that is about 1/10 of the depth of cut into the semiconductor wafer 10, that is, about 1/10 of the depth of the kerf 24. Generally, about 1/10 of the depth of the kerf 24 is about 2 to 15 μm. The reason for setting the depth of field DOF2 in the above-described range is that when the depth of field DOF2 is too shallow, unevenness of several microns is present microscopically on the table surface on which the workpiece is mounted. Although these irregularities are subjected to surface correction, in the case of DOF2 less than the correction capability (generally about 2 μm), focus blurring occurs due to variations in correction capability, and the effect of the correction itself cannot be obtained, and the depth of field DOF2 This is because it is difficult to obtain a predetermined contrast when the depth is increased.

  Next, detection of the kerf edge of the fully cut semiconductor wafer 10 shown in FIG. 6 will be described. The kerf edge is detected for the semiconductor wafer 10 having the laser groove 22 formed along the planned division line 16 and the kerf 29 formed by full-cut grinding along the laser groove 22.

  The inventor has intensively studied the detection of the edge of the fully cut kerf 29 in the region of the laser groove 22. For example, as shown in FIG. 8, when light is irradiated from the illumination device 150 to the imaging region from the vertical direction, there is no reflected light from the bottom surface of the full-cut kerf 29 even if the light amount is adjusted. The area turns black. As a result, it has been found that the contrast at the boundary between the kerf 29 region and the laser groove 22 region may be unclear.

  FIG. 12 shows the result of imaging the laser groove 22 and the kerf 29 by the imaging means by irradiating light perpendicular to the imaging region, that is, parallel to the observation optical axis. The surface of the laser groove 22 is rough. Therefore, the irradiated light is irregularly reflected, so that the region of the laser groove 22 is observed as black. Since the bottom surface of the kerf 29 is the dicing tape 18, no light is reflected, and the region of the kerf 29 is observed as black.

  In FIG. 12, the laser groove 22 and the kerf 29 are shown in different colors for the purpose of explanation. However, since the region of the laser groove 22 and the region of the kerf 29 are black of the same color, it is difficult to specify the image by processing the boundary between the laser groove 22 and the kerf 29.

  Therefore, the inventor has found that the boundary between the laser groove 22 and the fully cut kerf 29 can be clearly recognized by irradiating the imaging region with light from an oblique direction with respect to the observation optical axis. FIG. 13 shows the positional relationship between the second illumination device 58 and the fully-cut semiconductor wafer 10. FIG. 13A is a cross-sectional view seen from the longitudinal direction of the planned dividing line 16, and FIG. 13B is a plan view.

  Light is irradiated from the second illumination device 58 to the observation region (the region of the division planned line 16, the laser groove 22, and the kerf 29) of the semiconductor wafer 10 from a direction oblique to the observation optical axis. The surface of the planned dividing line 16 is substantially a mirror surface. Therefore, the area of the planned dividing line 16 reflects substantially all the light irradiated from the oblique direction, and the reflected light travels in the oblique direction with respect to the observation optical axis. The surface of the laser groove 22 is rough. Therefore, the region of the laser groove 22 irregularly reflects the light irradiated from the oblique direction, and a part of the light travels parallel to the observation optical axis. A groove is formed in the region of the kerf 29. Therefore, substantially all of the light irradiated to the area of the kerf 29 from an oblique direction repeats reflection inside the kerf 29, and the light is not reflected outside the kerf 29.

  When the second illumination device 58 described above is used to irradiate the imaging area and the imaging area is imaged by the imaging means, the result shown in FIG. 14 is obtained. Since all reflected light from the surface of the planned division line 16 does not travel in parallel with the observation optical axis, the area of the planned division line 16 is visually recognized as black (dark). Reflected light from the surface of the region of the laser groove 22 is irregularly reflected and part of the light travels parallel to the observation optical axis, so that the region of the laser groove 22 is visually recognized as white (brighter) as a whole. Since practically all reflected light from the area of the kerf 29 does not reach the imaging means, the area of the kerf 29 is visually recognized as black (dark). Therefore, the boundary between the laser groove 22 and the kerf 29 can be made clear.

  In addition, by controlling the light from the second illumination device 58, the region of the laser groove 22 can be made white (brighter) and the region of the kerf 29 can be made black (darker).

  Although the edge detection of the fully cut kerf 29 has been described, the edge detection apparatus 1 can also be used for edge detection of the half cut kerf 24. The edge detection of the half cut kerf 24 will be described.

  FIG. 15 shows the positional relationship between the second illumination device 58 and the half-cut semiconductor wafer 10. FIG. 15A is a cross-sectional view seen from the longitudinal direction of the planned dividing line 16, and FIG. 15B is a plan view.

  Light is irradiated from the second illumination device 58 to the observation region (the region of the division planned line 16, the laser groove 22, and the kerf 24) of the semiconductor wafer 10 from an oblique direction with respect to the observation optical axis. Similarly to the case described with reference to FIG. 13, the division line 16 substantially reflects all the light irradiated from the oblique direction, and the region of the laser groove 22 irregularly reflects the light irradiated from the oblique direction. A groove is formed in the region of the kerf 24. Therefore, substantially all of the light irradiated to the area of the kerf 24 from an oblique direction is repeatedly reflected inside the kerf 24, and the light is not reflected outside the kerf 24.

  When the second illumination device 58 described above is used to irradiate the imaging region and the imaging region is imaged by the imaging means, the result shown in FIG. 16 is obtained. As described with reference to FIG. 14, the area of the division planned line 16 is visually recognized as black (dark). The region of the laser groove 22 is visually recognized as white (brighter) as a whole. Since practically all reflected light from the area of the kerf 24 does not reach the imaging means, the area of the kerf 24 is visually recognized as black (dark). Therefore, the boundary between the laser groove 22 and the kerf 24 can be made clear.

  Next, another aspect of the edge detection of the half cut kerf 24 will be described. FIG. 17 shows the positional relationship between the second illumination device 58 and the half-cut semiconductor wafer 10. FIG. 17A is a cross-sectional view as viewed from the longitudinal direction of the planned dividing line 16, and FIG. 17B is a plan view. As described with reference to FIG. 4, the kerf 24 is formed on the substrate 12 by being half-cut by the grinding blade SP <b> 1. Depending on the usage of the grinding blade, a so-called saw mark 28 may be formed on the bottom surface of the kerf 24 in addition to the smooth surface 26. The saw mark 28 is a cutting mark formed on the bottom surface of the kerf 24 along the longitudinal direction of the kerf 24, and is a horizontally long protrusion or groove.

  Light is irradiated from the second illumination device 58 to the observation region (the region of the division planned line 16, the laser groove 22, and the kerf 24) of the semiconductor wafer 10 from an oblique direction with respect to the observation optical axis. Similarly to the case described with reference to FIG. 13, the division line 16 substantially reflects all the light irradiated from the oblique direction, and the region of the laser groove 22 irregularly reflects the light irradiated from the oblique direction.

  The area of the kerf 24 is irradiated with light from an oblique direction. In the case where the saw mark 28 is formed on the bottom surface of the kerf 24, the kerf 24 is irradiated perpendicularly to the scheduled division line 16 in a plan view and obliquely with respect to the observation optical axis, and the light is irradiated perpendicularly to the saw mark 28. The light applied to the saw mark 28 may reflect the light in a direction parallel to the observation optical axis.

  When the second illumination device 58 described above is used to irradiate the imaging region and the imaging region is imaged by the imaging means, the result shown in FIG. 18 is obtained. Similarly to the description with reference to FIG. 16, the area of the planned division line 16 is visually recognized as black (dark). The region of the laser groove 22 is visually recognized as white (brighter) as a whole. Unlike FIG. 16, because of the reflected light from the saw mark 28, a part of the area of the kerf 24 is visually recognized as a white (bright) band.

  It becomes difficult to distinguish the white band-shaped light caused by the saw mark 28 and the white light in the region of the laser groove 22, and the white band-shaped light becomes a factor that hinders detection of the boundary between the laser groove 22 and the kerf 24. Since it is difficult to visually separate with the monitor 60, it may cause a displacement of the processing position during operation by the operator.

  Therefore, as shown in FIG. 19, the amount of light from the oblique direction with respect to the planned division line 16 is made larger than the amount of light from the direction perpendicular to the planned division line 16 in plan view. In FIG. 19, the light amount from the vertical direction is set to 0, but the light amount from the oblique direction may be larger than the light amount from the vertical direction.

  In plan view, light in an oblique direction is applied to the saw mark 28 and reflected by the saw mark 28. However, the oblique light is reflected in a direction not parallel to the observation optical axis, and the reflected light does not reach the imaging means. As a result, reflected light from the saw mark 28 formed inside the kerf 24 can be suppressed.

  The light from the oblique direction means light having an angle α with respect to a virtual line drawn at an angle of 45 ° between the X axis and the Y axis with the center of the imaging region as the origin within 15 °. Most preferred is light in an oblique direction with an angle α of 0 °.

  Even if the amount of light from the vertical direction is reduced, the reflected light (diffuse reflection) from the surface of the region of the laser groove 22 is visually recognized as white (bright), and the region of the kerf 24 is visually recognized as black (dark). The contrast between the kerf 24 and the laser groove 22 can be secured. As a result, an image similar to that in FIG. 16 can be obtained.

  In the present embodiment, it is generally preferable that the illumination lens 52 has a depth of field of about 15 to 30 μm. As shown in FIG. 7, the illumination lens 52 having a deep depth of field is used, and the mounting position of the first illumination device 50 is adjusted, so that light is captured from a wide range of the first illumination device 50. . As a result, the illumination range and the illumination angle to the inside of the kerf 24 are expanded by the objective lens 30 having a shallow depth of field and the illumination lens 52 having a deep depth of field. As a result, a large amount of light diffusely reflected by the saw mark 28 inside the kerf 24 can be secured, and shading due to insufficient light quantity at the edge portion of the kerf 24 can be suppressed.

  The objective lens 30 of the present embodiment has a large radius of curvature on the surface side facing the CCD 40. Internal reflection can be suppressed as much as possible by increasing the radius of curvature.

  Next, a dicing apparatus in which the edge detection apparatus 1 is incorporated will be described.

  FIG. 20 is a perspective view showing an external configuration of a dicing apparatus in which the edge detection device 1 is incorporated. As shown in the figure, the dicing apparatus 110 of the present embodiment includes a supply / recovery unit 112 for supplying / recovering the semiconductor wafer 10 on which the laser groove 22 is formed, a processing unit 114 for processing the semiconductor wafer 10, A cleaning unit 116 that cleans the processed semiconductor wafer 10, a transport unit 118 that transports the semiconductor wafer 10, an operation panel 120 that performs various operations, the edge detection device 1, and a control unit that controls the overall operation (FIG. Not shown).

  The supply / recovery unit 112 for supplying / recovering the semiconductor wafer 10 includes a load port 122, and a cassette (not shown) in which a large number of semiconductor wafers 10 are stored is set in the load port 122. The semiconductor wafer 10 to be processed is stored in a cassette in a state of being mounted on a predetermined frame F via a dicing tape 18.

  The processing unit 114 that processes the semiconductor wafer 10 includes a work table 124 that holds the semiconductor wafer 10 by suction, a pair of grinding blades SP1 and SP2 that cut the semiconductor wafer 10 held on the work table 124, and a grinding blade SP1. The spindles 128A and 128B to which the SP2 is attached and the edge detection device 1 that detects the kerf edge of the surface of the semiconductor wafer 10 held on the work table 124.

  The work table 124 is provided on an X-axis table (not shown) and a θ-axis table (not shown) installed horizontally, and is driven by the θ-axis table to be centered (θ-axis, not shown). ) Rotate around. As the X-axis table slides on an X-axis guide (not shown), the work table 124 is moved horizontally in the X direction in the figure.

  The grinding blades SP1 and SP2 are constituted by a diamond blade or CBN abrasive electrode formed in a thin disc shape, an electrodeposition blade obtained by electrodeposition with nickel, a resin blade bonded by a resin, or the like. The grinding blade SP1 half-cuts the semiconductor wafer 10, and the grinding blade SP1 fully cuts the semiconductor wafer 10. The grinding blades SP1 and SP2 are attached to the tips of the spindles 128A and 128B so that the cutting direction thereof is parallel to the movement direction of the work table 124 (X direction in the figure). The spindles 128A and 128B are driven to rotate. A cutting nozzle (not shown) is provided in the vicinity of the grinding blades SP1 and SP2, and cutting water is supplied from the nozzle to the processing point.

  The spindles 128 </ b> A and 128 </ b> B are arranged opposite to each other above the work table 124 so that the rotation axis is orthogonal to the moving direction of the work table 124, and are rotated at a high speed of 30,000 rpm to 80,000 rpm.

  The spindles 128A and 128B are each attached to a blade Z-axis table (not shown) installed vertically. The blade Z-axis table slides on the blade Z-axis guide (not shown) in the Z direction (direction perpendicular to the XY plane), so that the grinding blades SP1 and SP2 move vertically in the Z direction. Then, it moves forward and backward vertically with respect to the work table 124.

  The cleaning unit 116 includes a spin cleaning device 116A, and the processed semiconductor wafer 10 is spin cleaned by the spin cleaning device 116A.

  The transfer unit 118 includes a handling robot 118A, and the handling robot 118A transfers the semiconductor wafer 10 between the units. That is, by the handling robot 118A, the semiconductor wafer 10 is taken out from the cassette of the supply / recovery unit 112 and transferred to the processing unit 114, and the semiconductor wafer 10 processed by the processing unit 114 is recovered from the processing unit 114. Transport to cleaning unit 116. Further, the semiconductor wafer 10 cleaned by the cleaning unit 116 is recovered from the cleaning unit 116, transported to the supply / recovery unit 112, and stored in the cassette of the supply / recovery unit 112.

  The edge detection device 1 detects the position of the kerf 24 formed by the grinding blade SP1 or the kerf 29 formed by the grinding blade SP2 in the region of the laser groove 22. A deviation between the planned processing position and the actual position of the kerf 24 is obtained from this information data, and the semiconductor wafer 10 is half-cut by the grinding blade SP1 while correcting the positional deviation. Further, a deviation between the planned processing position and the actual position of the kerf 29 is obtained from this information data, and the semiconductor wafer 10 is fully cut by the grinding blade SP2 while correcting the positional deviation.

  The edge detection device 1 and the imaging region of the semiconductor wafer 10 are aligned. The edge detection apparatus 1 is positioned in an imaging region including the kerfs 24 and 29 of the semiconductor wafer 10, the laser groove 22, and the division planned line 16. In particular, the objective lens 30 is preferably arranged so that the central axis of the objective lens 30 is positioned at the center in the width direction of the kerfs 24 and 29. The reason is to eliminate information similar to the kerfs 24 and 29 inside the semiconductor wafer 10 as much as possible.

  Next, detection of the kerfs 24 and 29 and detection of the laser groove 22 will be described. In this embodiment, image processing means is applied.

<Detection of kerf>
(When the kerf is white and visible)
The kerf 24 is detected by binarization processing or edge detection. When the color of the kerf 24 is visually recognized in light gray (white), it is processed as a white object detection algorithm by data setting. Further, since the width of the kerf 24 can be estimated with reference to the width of the grinding blade SP1, the region of the kerf 24 can be roughly specified. The distribution tendency (for example, the average value) of the luminance of the specified kerf 24 region is white, and automatic detection of the color to be detected using this characteristic is also possible.

(Binarization processing)
When white object detection is performed by binarization processing, use a data setting or a known automatic threshold setting algorithm (eg, Otsu's automatic threshold determination method) to extract and extract white objects. The resulting contour can be kerf 24.

(Edge detection)
When performing edge detection, a change point that changes from white to black toward the outside of the kerf 24 region is detected with reference to the center of the whitest region in the inspection window. The edge of the kerf 24 (boundary with the laser groove 22) is calculated in sub-pixel coordinates by adopting a second-order differential zero cross obtained by further differentiating the edge intensity that is the changing point.

  Further, the processing speed can be improved by calculating a rough contour position by binarization processing as preprocessing of the edge detection processing and performing edge detection in the vicinity of the contour position.

(When the kerf is black and visible)
The kerfs 24 and 29 are detected by binarization processing or edge detection.

  In the case of visibility where the colors of the kerfs 24 and 29 appear black, they are processed as a black object detection algorithm by data setting. Since the size of the kerfs 24 and 29 can be estimated with reference to the blade data, an area considered to be the kerfs 24 and 29 can be roughly specified. The luminance distribution tendency (for example, the average value) of the specified area is black, and automatic detection of the color to be detected using this characteristic is also possible.

(Binarization processing)
When black object detection is performed by binarization processing, black objects are extracted and extracted using data setting or a known automatic threshold setting algorithm (eg, Otsu's automatic threshold determination method). The resulting contours are kerfs 24 and 29.

(Edge detection)
When edge detection is performed, a change point that changes from black to white toward the outside of the kerf is detected based on the center of the blackest area in the detection window. The edges of the kerfs 24 and 29 are calculated in sub-pixel coordinates by adopting a second derivative zero cross obtained by further differentiating the edge intensity at the changing point. Further, the processing speed can be improved by calculating a rough contour position by binarization processing as preprocessing of the edge detection processing and performing edge detection in the vicinity of the contour position.

<Laser groove detection>
(When the laser groove is visible as black)
The laser groove 22 is detected by binarization processing or edge detection. When the color of the laser groove 22 is visually recognized as black, it is processed as a black object detection algorithm by data setting. Further, since the width of the laser groove 22 can be estimated from the data setting and the width of the kerf 24 region can be estimated with reference to the width of the grinding blade SP1, the luminance distribution tendency of the region excluding the width of the kerf 24 from the width of the laser groove 22 For example, the average value) is black, and automatic determination using this characteristic is also possible.

(Binarization processing)
When black object detection is performed by binarization, data setting or an existing automatic threshold setting algorithm (eg, Otsu's automatic threshold determination method) is used to threshold the black object from the image. Extract by value processing. The contour coordinates of the extraction result can be grasped by accessing the pixel, and this contour can be recognized as the laser groove 22. Here, since the laser groove 22 may be divided by the white kerf 24, it is excluded at the time of detection. Extraction is performed separately in the upper and lower parts of the detection window, or the black area in the detection window is extracted by painting the center part black or by not accessing the pixels with the kerf 24 area outside the detection target range.

(Edge detection)
When performing edge detection, from the center of the objective lens 30, from the outside of the approximate kerf 24 region, or from the outside when there is already a detection result of the kerf 24, the laser groove 22 is directed to the outside. Change point that changes from white to white is detected. The edge of the kerf 24 region is calculated in sub-pixel coordinates by adopting a zero-order of the second derivative of luminance obtained by further differentiating the edge intensity at the changing point.

  Alternatively, the processing speed can be improved by calculating an approximate contour position by binarization processing as preprocessing of the edge detection processing and performing edge detection in the vicinity of the contour position.

  Since the color of the planned division line 16 is visually recognized as white, the planned division line 16 can be detected by the same detection method as that for the kerf 24 region.

(When the laser groove is white and visible)
In the case of the visibility in which the color of the laser groove 22 appears white, it is processed as a white object detection algorithm by data setting. The approximate size of the laser groove 22 can be estimated from the data setting, and the sizes of the kerfs 24 and 29 can be estimated from the blade data. The luminance distribution tendency (for example, the average value) in the region excluding the widths of the kerfs 24 and 29 from the width of the laser groove 22 is white, and automatic detection of a job to be detected using this characteristic is also possible.

(Binarization detection)
When detecting a white object (laser groove 22) by binarization, use a data setting or an existing automatic threshold setting algorithm (eg Otsu's automatic threshold determination method) An object is extracted from an image by threshold processing. The contour coordinates of the extraction result can be grasped by accessing the pixel, and this contour is recognized as the laser groove 22. Since the laser groove 22 may be divided by the black kerfs 24 and 29, it is excluded during detection. Extraction is performed separately on the top and bottom of the detection window. Or paint the center part white. Alternatively, the area of the kerfs 24 and 29 is outside the detection target range, and the pixel is not accessed. Accordingly, the outline of the white laser groove 22 can be detected by extracting a white region in the detection window.

(Edge detection)
When performing edge detection, from the center of the microscope, from the outside of the approximate kerfs 24 and 29, or from the outside when there is already a detection result of the kerfs 24 and 29, the laser groove 22 is directed to the outside and white to black. The change point which changes to is detected. The edges of the kerfs 24 and 29 are calculated in sub-pixel coordinates by adopting a second-order derivative zero cross of luminance obtained by further differentiating the edge intensity at the changing point. Alternatively, the processing speed can be improved by calculating an approximate contour position by binarization processing as preprocessing of the edge detection processing and performing edge detection in the vicinity of the contour position.

  A case has been described in which image processing means is used to detect the light and dark recognition of the laser groove 22, the kerf 24, and the planned division line 16. However, the present invention is not limited to this, and detection can be performed using an image recognition means using a CCD. An image recognition means using a three-dimensional sensor, an area sensor, a line sensor can be used by using an image recognition means using a CCD.

  Next, an image processing sequence will be described with reference to the flow shown in FIG. The sequence of image processing includes sections of process A: groove detection, process B: kerf detection, and process C: result drawing. Between START and END of the image processing sequence, processing A: groove detection, processing B: kerf detection, and processing C: result drawing are executed. Process C: Process A: groove detection and process B: kerf detection are basically executed before the result drawing is executed. Regarding the order of process A: groove detection, process B: kerf detection, depending on the situation, process A: groove detection, process B: kerf detection, or process B: kerf detection, process A: groove detection are executed in this order. .

  A case where the groove is detected before the kerf 24 is formed, that is, before processing is described. First, the semiconductor wafer 10 on which the laser groove 22 is formed is prepared (SATAR). When the groove before processing is detected (Yes), process A: groove detection is executed. The microscope is moved to the position of the laser groove 22. As a method of detecting the groove, the light from the first illumination device 50 is irradiated onto the imaging region through the objective lens 30, and the entire laser groove 22 is displayed in black as compared with the planned division line 16, whereby the laser groove 22 is displayed. Can be detected. Further, the laser groove 22 can be detected by irradiating the imaging region with the light from the second illumination device 58 through the objective lens 30 and displaying the entire laser groove 22 in white as compared with the division line 16. In the groove optical control, the first illumination device 50 or the second illumination device 58 is controlled based on a result of adjustment according to the object.

  Process A in groove detection before processing: When the groove detection is completed, a kerf 24 is formed in the laser groove 22 (processing). In the case of pre-processing groove detection, when the laser groove 22 is not detected (Yes), the process A: groove detection is executed until the detection of the laser groove 22 is completed.

  When the kerf 24 is formed in the laser groove 22, the process B: kerf detection is executed. The microscope is moved to the position of the kerf 24. As a method of kerf detection, the kerf 24 is detected by irradiating the imaging region with light from the first illumination device 50 through the objective lens 30 and displaying the entire kerf 24 in white compared to the laser groove 22. be able to. In addition, the laser groove 22 can be detected by irradiating the imaging region with light from the second illumination device 58 through the objective lens 30 and displaying the entire kerf 24 in black compared to the laser groove 22. In the kerf optical control, control is performed based on the result of adjusting the first illumination device 50 or the second illumination device 58 according to the object.

  When there is an undetected laser groove 22 or kerf 24 (Yes), the process B: kerf detection is executed until the detection of the kerf 24 is finished.

  Next, process C: result drawing is executed. Process C: In the result drawing, the groove / kerf detection results are combined and displayed on the apparatus screen. The position of the kerf 24 in the laser groove 22 can be grasped by processing C: result drawing, and the amount of deviation of the processing position can be obtained. The processing position of the kerf 24 is adjusted based on the amount of deviation.

  Process C: Result drawing will be briefly described. Process A: The contour information of the laser groove 22 detected by the groove detection is stored as coordinate data or image information in a memory or a storage medium. Process B: The contour information of the kerf 24 detected by the kerf detection is stored as coordinate data or image information in a memory or a storage medium. The coordinate data of the laser groove 22 is drawn on the image memory, or the pixel indicating the outline color of the laser groove 22 is drawn on the memory from the image information, and the coordinate data of the kerf 24 is drawn on the image memory, or the kerf 24 is read from the image information. A pixel indicating the contour color is drawn on the memory. The drawing on the memory generated by the detection of the laser groove 22 or the kerf 24 is overlaid on the image when the laser groove 22 is detected. Alternatively, an overlay display is performed on the image when the kerf 24 is detected. The optical condition of the image used for display can be changed by data setting.

  If there is an unexecuted SP (spindle) after execution of the process C: result drawing (Yes), the image processing sequence is not terminated and the process returns to the process B: kerf detection in a loop. Groove detection and kerf check are performed on each spindle.

  Next, a case where the groove before processing is not detected will be described. First, the semiconductor wafer 10 on which the laser groove 22 is formed is prepared (SATAR). A kerf 24 is formed in the laser groove 22 (processing). When the microscope position is closer to the undetected laser groove 22 than the kerf 24 (Yes), process A: groove detection is executed. If there is an undetected laser groove 22 or kerf 24 (Yes), process B: kerf detection is executed. If the groove detection after processing is set and the groove has been detected (Yes), then process C: result drawing is executed.

  When the microscope position is closer to the kerf 24 than the undetected laser groove 22, the process B: kerf detection is executed. Next, process A; groove detection is executed. When there is an undetected laser groove 22 or kerf 24 (Yes), process A: groove detection or process B: kerf detection is executed. When the groove detection after processing is set and the groove has been detected (Yes), the process C: result drawing is finally executed. If there is an unexecuted SP (spindle) after execution of the process C: result drawing (Yes), the image processing sequence is not terminated and the process returns to the process B: kerf detection in a loop. Groove detection and kerf check are performed on each spindle.

  As described above, in the case where only the groove is detected before one line processing and the kerf check is performed after the processing, it is possible to cope with both the case where the groove detection and the kerf check are performed after the one line processing. These can be switched by setting.

  Next, a specific image processing sequence will be described with reference to FIGS.

  In the image processing sequence of FIG. 22, the detection of the groove before processing is not executed. Process B: In the kerf detection, by using the first illumination device 50, the entire kerf 24 is displayed in white compared to the laser groove 22, and the kerf 24 is detected. In the process A: groove detection, the first illuminating device 50 is used and the entire kerf 24 is displayed in white as compared with the laser groove 22 in the same manner as the process B: kerf detection, and the laser groove 22 can be detected. Further, the light intensity of the first illumination device 50 can be reduced and the entire laser groove 22 can be adjusted to be black so that the laser groove 22 can be detected.

  In the simultaneous processing execution sequence of the image processing in FIG. 23, detection of the groove before processing is not executed. Process B: In the kerf detection, by using the second illumination device 58, the entire kerf 24 is displayed in black compared to the laser groove 22, and the kerf 24 is detected. Process A: In the groove detection, it is possible to detect the laser groove 22 by using the first illumination device 50 and displaying the entire kerf 24 in white compared to the laser groove 22. Further, the light intensity of the first illumination device 50 can be reduced and the entire laser groove 22 can be adjusted to be black so that the laser groove 22 can be detected.

  In the simultaneous processing execution sequence of the image processing in FIG. 24, detection of the groove before processing is not executed. Process B: In the kerf detection, by using the first illumination device 50, the entire kerf 24 is displayed in white compared to the laser groove 22, and the kerf 24 is detected. Process A: In the groove detection, by using the second illumination device 58, the entire laser groove 22 is displayed whiter than the planned division line 16, and the laser groove 22 is detected.

  In the simultaneous processing execution sequence of the image processing in FIG. 25, the detection of the groove before processing is not executed. Process B: In the kerf detection, by using the second illumination device 58, the entire kerf 24 is displayed in black compared to the laser groove 22, and the kerf 24 is detected. Process A: In the groove detection, by using the second illumination device 58, the entire laser groove 22 is displayed whiter than the planned division line 16, and the laser groove 22 is detected.

  In the image processing sequence of FIG. 26, the detection of the groove before processing is executed, and the detection of the groove is not executed after processing. By detecting the position of the laser groove 22 before processing and feeding it back to processing control, cutting with high accuracy becomes possible. Regarding the process A: groove detection and the process B: kerf detection, the detection methods of FIGS. 22 to 25 can be executed.

  In the present embodiment, illumination for detecting the laser groove 22 (first illumination device 50, second illumination device 58) and illumination for detecting the kerf 24 (first illumination device 50, second illumination device 58); By switching between, the laser groove 22 and the kerf 24 can be detected under optimum illumination conditions. Thereby, for example, in the case of full cut, the first illumination device 50 can be selected as the optimum illumination for detecting the laser groove 22, and the second illumination device can be selected for detecting the kerf 24.

  Further, even when a half cut at a step cut is formed in advance, the first illumination device 50 is darkened when the laser groove 22 is detected, and the first illumination device 50 is lighted brightly when the kerf 24 is detected. Optimal detection conditions can be created.

  Regarding the second illumination device 58, not only a ring-type incident light in which fibers are laid out over the entire circumference but also a spot-type illumination method in which the illumination direction is laid out at 45 ° is adopted. By adopting a spot type illumination system, the laser groove 22 can be made white and the kerf 24 can be made black.

  Since the first lighting device 50 and the second lighting device 58 can be individually controlled, a plurality of image processing sequences can be executed. Thereby, even if the laser groove 22 and the kerf 24 cannot be properly detected, it is possible to detect the retry by changing the illumination device.

  Further, by controlling the optical conditions separately for the laser groove 22 and for the kerf 24, the laser groove 22 is detected not only after the kerf 24 is processed but also before the process, and the blade is processed at this center position. It is also possible to realize pre-processing correction. Similarly, it can be realized simultaneously after processing.

  DESCRIPTION OF SYMBOLS 1 ... Edge detection apparatus, 10 ... Semiconductor wafer, 12 ... Board | substrate, 14 ... Element area | region, 16 ... Dividing line, 18 ... Dicing tape, 20 ... Low dielectric constant insulating film, 22 ... Laser groove, 24 ... Calf, 26 ... Smoothing unit, 28 ... saw mark, 30 ... objective lens, 40 ... CCD, 50 ... first illumination device, 52 ... illumination lens, 58 ... second illumination device, 60 ... monitor, 82 ... image processing unit, 84 ... light quantity control 110, dicing device

Claims (5)

For a semiconductor wafer having a laser groove formed by irradiating a laser beam along a division line and a kerf deeper than the laser groove formed by grinding with a grinding blade along the laser groove, Imaging means for imaging the division planned line, the laser groove, and the kerf from above;
An objective lens disposed between the planned division line and the imaging means, and a depth of field shallower than a depth of the kerf;
A first illumination device that irradiates the objective lens with light from a coaxial direction with respect to an observation optical axis connecting the objective lens and the imaging means;
A second illumination device for irradiating the semiconductor wafer with light from an oblique direction with respect to the observation optical axis;
An edge detection device comprising:   The edge detection device according to claim 1, wherein the objective lens is disposed such that a central axis of the objective lens is positioned at a center in a width direction of the kerf.   3. The edge detection device according to claim 1, wherein the second illumination device has a light amount from an oblique direction with respect to the planned division line larger than a light amount from a direction perpendicular to the planned division line in a plan view.   4. The edge detection device according to claim 1, wherein the second illumination device is configured by an illumination device arranged in a ring shape surrounding the observation optical axis. 5. A light amount control unit that controls the light amount of the first illumination device and the light amount of the second illumination device;
5. The image processing unit according to claim 1, further comprising: an image processing unit configured to detect the kerf region, the laser groove region, and the division-scheduled line region from the image obtained by the imaging unit. The edge detection apparatus described in 1.

Images