TW201818066A - Scratch detection method enabling to differentiate scribe lines from scratches and detect scratches appropriately - Google Patents

Abstract

To differentiate scribe lines from scratches and detect scratches appropriately. The scratch detection method according to the present invention includes: a processing groove forming step of forming a dividing groove on the front surface of a wafer; a grinding step of grinding the wafer from the back surface to expose the processing groove; and an image capturing step of photographing the ground surface of the wafer after it is grinded; an editing step of performing coordinate transformation on the captured image of the wafer and editing it into a strip image; a removing step of removing lines equivalent to the dividing groove from the strip image; and a step of determining the presence or absence of scratches according to the strip image after the removal of the lines.

Description

Scratch detection method

FIELD OF THE INVENTION The present invention relates to a scratch detection method for detecting scratches formed on the surface of a wafer after grinding.

BACKGROUND OF THE INVENTION When infeed grinding a wafer with a grinding device, a saw mark is formed as a grinding mark on a grinding surface of the wafer. The knife marks are formed radially from the center of the wafer toward the outer periphery. Among the knife marks, there are cases in which so-called scratches are caused by the abrasive grains falling off the grinding stone contacting the ground surface of the wafer during processing and causing damage. Since this scratch affects the components formed on the wafer, it is necessary to confirm the presence of the scratch at the end of grinding.

Therefore, there has been proposed a grinding device that detects a scratch of a wafer after a grinding process (see, for example, Patent Document 1). In Patent Document 1, a polished surface of a processed wafer is irradiated with a light beam, and the presence or absence of scratches is determined based on the amount of reflected light. Prior Art Literature Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2009-95903

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, in the DBG (Dicing Before Grinding) program, which performs a half-cut of a wafer along a predetermined division line before grinding, the wafer is divided by performing grinding processing. Into wafers. Therefore, not only the above-mentioned scratches but also the dividing lines appear on the ground surface of the wafer after grinding.

In this case, when scratch detection is performed by the grinding device of Patent Document 1, not only scratches but also division lines can be detected. Therefore, it is conceivable that a scratch cannot be distinguished from a dividing line, and a scratch cannot be detected properly.

The present invention has been made in view of the problems described above, and one of its objects is to provide a scratch detection method capable of distinguishing a dividing line from a scratch and appropriately detecting the scratch. Means to solve the problem

The scratch detection method of one aspect of the present invention is to detect the presence or absence of scratches during wafer division, wherein the wafer division is formed on a wafer on the front side where a component is formed by dividing a predetermined line division, and the After the division groove is formed with a depth of incomplete cutting from the front side toward the division division line, the back surface is ground with a grindstone to expose the division groove on the back side to divide the wafer. The scratch detection method is based on imaging. The mechanism captures the ground surface of the back surface of the wafer that has been ground by the grinding stone to detect the presence or absence of scratches. The imaging mechanism includes a linear sensor that captures the ground surface extending in the radial direction of the wafer. And a light source extending parallel to the linear sensor and illuminating the ground surface, the scratch detection method includes the following steps: an imaging step, positioning the imaging mechanism in the radius of the wafer parallel to the radial direction to extend , And the holding table holding the wafer is rotated around the center of the wafer, so that the imaged mechanism photographs the ground surface in a ring shape to obtain the scattered light scattered by the light from the light source in the dividing grooves and scratches. The resulting shot A removal step, which removes a grid-like straight line corresponding to the dividing groove from the captured image captured in the imaging step; and a determination step, which includes a circular arc of a predetermined width or more in the image after the removal step When it is a straight line, it is judged that there are scratches.

According to this configuration, it is possible to obtain a photographed image of the ground surface of the wafer by rotating the holding table while the linear sensor photographs a radius portion of the wafer. Since the radius portion of the wafer is illuminated by a light source during shooting, it is possible to recognize scratches and the grid-like straight lines (dividing lines) corresponding to the dividing grooves from the brightness of the captured image. In particular, a scratch image can be represented by a straight line with regularity by editing a captured image into a band image. On the other hand, the division line is displayed on the band-shaped image as a line (for example, a curve) different from a scratch. Therefore, it is possible to distinguish a scratch from a dividing line. In addition, the presence or absence of scratches is determined based on the strip-shaped image from which the dividing lines have been removed, whereby the scratches can be appropriately detected.

In the scratch detection method according to one aspect of the present invention, the brightness of the light source is adjusted so that the imaging mechanism cannot capture the brightness of the grinding mark formed on the wafer by the grinding stone. Invention effect

According to the present invention, it is possible to distinguish a dividing line from a scratch and detect the scratch appropriately.

Form for Carrying Out the Invention In the past, when a wafer was subjected to lateral feed grinding by a grinding device, grinding marks (knife marks) including scratches were sometimes formed on the grinding surface of the wafer. An example of the scratch is an arc-shaped pattern (grinding mark) formed regularly from the center of the wafer toward the outer periphery. In addition, there may be cases where scratches are caused by the abrasive grains falling off the grinding stone contacting the surface to be polished of the wafer during processing. This scratch is not ideal because it affects the components formed on the wafer.

For example, it is conceivable to perform a grinding process by supplying a large amount of grinding water to the upper surface of the wafer so as to remove the abrasive grains that have fallen off from the grinding surface of the wafer, thereby making it difficult to form scratches. However, increasing the supply of grinding water is not economical. In addition, a large amount of grinding water is the main cause, which causes the force of the grinding stone to attach to the wafer, that is, the bite of the abrasive particles becomes weak. As a result, there is a possibility that the grinding efficiency may deteriorate.

In this way, although the generation of scratches can be suppressed by increasing the amount of grinding water, it is difficult to achieve a balance between grinding efficiency. Therefore, the presence or absence of scratches must be confirmed at the end of grinding. Therefore, in the past, there has been proposed a grinding device including a scratch detection mechanism. The scratch detection mechanism irradiates a light beam on a ground surface of a processed wafer, and according to the light amount of the reflected light. To determine the presence of scratches.

However, as a method of processing a wafer, there is a method called a DBG (Dicing Before Grinding) program. In the DBG program, a half cut is performed from the front side of the wafer along a predetermined division line, and a division groove having a depth corresponding to the thickness of the finished product of the element is formed on the wafer. Then, the wafer is ground from the back side of the wafer to expose the division grooves from the back surface and penetrate the division grooves in the thickness direction to divide the wafer into individual elements.

When scratch detection is performed on a wafer that has been ground by such a DBG program by the above-mentioned scratch detection mechanism, not only scratches but also division lines (division grooves) can be detected. That is, the dividing line is misidentified as a scratch. As described above, the conventional scratch detection mechanism cannot distinguish between the scratch and the dividing line, and there is a possibility that the scratch cannot be properly detected.

Therefore, the inventor of the present invention conceived a method of distinguishing a dividing line from a scratch in a DBG program to appropriately detect the scratch.

Hereinafter, a scratch detection method according to this embodiment will be described with reference to FIGS. 1 to 6. FIG. 1 is a schematic diagram showing an example of a processing groove forming step according to this embodiment. FIG. 2 is a schematic diagram showing an example of a grinding step in the present embodiment. FIG. 2A shows a state before grinding, and FIG. 2B shows a state during grinding. FIG. 3 is a schematic diagram showing an example of an imaging procedure in this embodiment. 3A is a side view of the holding table viewed from a predetermined direction, and FIG. 3B is a side view of the holding table viewed from a direction of an arrow A in FIG. 3A. FIG. 3C is a top view of the ground wafer, and FIG. 3D is a captured image. FIG. 4 is a schematic diagram showing an example of an editing procedure in the present embodiment. FIG. 5 is a schematic diagram showing an example of a removal step in the present embodiment. FIG. 6 is a schematic diagram showing an example of a judging procedure in this embodiment. In addition, each of the following steps may be implemented by a separate processing device, or all steps may be implemented by a single processing device.

The scratch detection method of this embodiment is implemented by the following steps: a processing groove forming step, forming a processing groove (dividing groove) on the front surface of the wafer (see FIG. 1); a grinding step, grinding the wafer from the back surface To expose the processing groove (refer to FIG. 2); an imaging step to photograph the ground surface (back surface) of the wafer after grinding (refer to FIG. 3); an editing step to perform coordinate conversion on the photographed image of the wafer for editing A strip image (see FIG. 4); a removal step, which removes a line corresponding to a dividing groove from the strip image (see FIG. 5); and a determination step, which determines the presence or absence of scratches based on the removed strip image (See Figure 6).

As shown in FIG. 1, a protective tape T1 (for example, a dicing tape) is attached to the wafer W on the back surface, and the holding table 10 held by a cutting device (not shown) is sucked and held by the protective tape T1 on the back surface. on. The wafer W is formed into a substantially circular plate shape, and is divided into a plurality of regions by predetermined division lines (not shown) formed in a grid shape (for example, X direction and Y direction) formed on the front surface. Elements not shown are formed in each region. Furthermore, the wafer W may be a semiconductor wafer in which elements such as IC and LSI are formed on a semiconductor substrate such as silicon or gallium arsenide, or an LED may be formed on a substrate of ceramic, glass, or sapphire-based inorganic material. Optical element wafer for optical elements. The holding table 10 is configured to be rotatable around a central axis in the vertical direction by a rotation mechanism (not shown), and is moved in the horizontal direction by the cutting feed mechanism 11 (cutting feed).

In the processing groove forming step, the front surface of the wafer W is half-cut by the cutter 12 along a predetermined division line. That is, a division groove V having a depth that is not completely cut is formed on the front surface of the wafer W along a predetermined division line.

Specifically, the wafer W is sucked and held on the holding table 10 with the element surface facing upward, and the cutter 12 is positioned at a predetermined height along the planned division line near the outer periphery of the wafer W. At this time, the height of the cutting blade 12 is positioned so that the lower end portion of the cutting blade 12 does not completely cut the wafer W in the thickness direction.

Then, the holding table 10 is relatively cut and fed in the horizontal direction with respect to the cutting blade 12 rotating at a high speed. Thereby, the front surface of the wafer W is cut along a predetermined division line to form a division groove V having a depth corresponding to the thickness of the finished product of the element. When the cutting processing of one line is completed, the cutting blade 12 is fed in the direction of the rotation axis, and the division groove V is formed again along the adjacent predetermined division line.

After the division grooves V are formed in all the division dividing lines along one direction of the wafer W in this manner, the holding table 10 is rotated by 90 degrees. Then, by cutting and feeding the holding table 10 with respect to the cutting blade 12 again, a new division groove V is formed along another predetermined division line orthogonal to the division groove V previously cut. As described above, the grid-like divided grooves V can be formed on the front surface of the wafer W.

When the processing groove forming step is completed, the protective tape T1 attached to the back side of the wafer W can be peeled off, and this time a new protective tape T2 (for example, Back grind tape (see FIG. 2)). The peeling of the protective tape T1 and the application of the protective tape T2 may be performed manually by an operator, or may be performed by a predetermined peeling (or attaching) device (not shown).

Next, a grinding step is performed. As shown in FIG. 2, in the grinding step, the back surface side of the wafer W is ground by the grinding mechanism 30, and the previously formed division grooves V are exposed on the back surface side, thereby dividing the wafer W into individual pieces. Of wafers.

Specifically, as shown in FIG. 2A, the wafer W is transferred from the cutting device to the grinding device (not shown), and is placed on the holding table with the front side to which the protective tape T2 is attached facing downward. 20 on. The holding table 20 is constituted by a porous chuck in which a circular plate-shaped porous plate 21 is attached to a frame 22 as a main body. A holding surface 21 a that attracts and holds the wafer W is formed on the upper surface of the porous plate 21.

The holding surface 21 a has an inclined surface with the center of rotation of the holding table 20 (the center of the holding surface 21 a) as the apex and the outer periphery being slightly inclined and lowered. When the wafer W is attracted and held on the holding surface 21a inclined in a conical shape, the wafer W is deformed into a gently inclined conical shape along the shape of the holding surface 21a.

The holding table 20 is connected to the table rotation mechanism 23 and is configured to be rotatably pivoted about the center of the wafer W by driving of the table rotation mechanism 23. The holding table 10 is configured so that the inclination can be adjusted by an inclination adjusting mechanism (not shown).

The grinding mechanism 30 is configured to rotate the grinding wheel 32 around the central axis with the main shaft 31. A grinding wheel 32 is mounted on a shaft end (lower end) of the main shaft 31 via a mounting base 33. A plurality of grinding stones 34 are arranged on the lower surface side of the grinding wheel 32 in a ring shape at intervals. The grinding stone 34 is composed of, for example, a diamond bond having a predetermined abrasive particle size with a ceramic bond. The grinding stone 34 is not limited to this, and may be formed by fixing diamond abrasive grains with a binder such as a metal binder or a resin binder. The grinding mechanism 30 is configured to be vertically movable by a grinding feed mechanism 35.

The holding table 20 that sucks and holds the front side of the wafer W is positioned below the grinding mechanism 30. At this time, the rotation axis of the holding table 20 is positioned at a position eccentric from the rotation axis of the grinding stone 34. In addition, the holding table 20 can adjust the inclination of the rotating shaft by the tilt adjustment mechanism so that the grinding surface 34a of the grinding stone 34 and the holding surface 21a are parallel.

Then, when the holding table 20 is rotated and the grinding mechanism 30 rotates the grinding wheel 32 (grinding grindstone 34) with the main shaft 31, the grinding feed mechanism 35 is lowered toward the holding surface 21a (grinding feed) ). The grinding surface 34 a of the grinding grindstone 34 is in an arc-like manner and comes into contact with a radius from the center of the wafer W to the outer periphery.

In this manner, the grinding mechanism 30 passes the grinding stone 34 through the center of the wafer W, and grinds the portion to be ground of the arc of the wafer W in a radius region between the center of the wafer W and the outer periphery. . By gradually grinding and feeding the grinding stone 34 in the Z-axis direction while the grinding grindstone 34 is in rotational contact with the wafer W, the wafer W can be ground and thinned in the thickness direction.

As shown in FIG. 2B, when the wafer W is thinned to a desired thickness, that is, the thickness of the finished product of the element, the divided grooves V are exposed from the back surface side of the wafer W to complete the grinding process. Thereby, the division groove V along the predetermined division line can be penetrated in the thickness direction of the wafer W, and the wafer W can be divided into individual elements (wafers). In addition, since each element is fixed by the protective tape T2, it is formed in the state which maintained the circular shape of the wafer W as a whole. In addition, since the dividing groove V is penetrated, the grid-shaped straight line formed on the wafer W is referred to as a "dividing line". In addition, the "dividing line" can also be called a curve.

Next, an imaging step is performed. In the imaging step, as shown in FIG. 3, the back surface (surface to be ground) of the wafer W is imaged by the imaging mechanism 41. Here, the structure of the scratch detection mechanism 40 which detects the scratch of the grinding | polishing surface formed on the wafer W is demonstrated. In the present embodiment, the case where the scratch detection mechanism 40 is provided in the grinding device has been described, but it is not limited to this configuration. The scratch detection mechanism 40 may also be provided in a separate device.

As shown in FIGS. 3A and 3B, the scratch detection mechanism 40 includes an imaging mechanism 41 that captures the ground surface of the wafer W, and a judgment to determine the presence or absence of scratches based on a captured image captured by the imaging mechanism 41. Agency 42. The imaging mechanism 41 includes a linear sensor 43 that photographs the ground surface of the wafer W from above, and a light source 44 that is disposed along the linear sensor 43.

The linear sensor 43 is configured by, for example, an image sensor. The linear sensor 43 extends in the radial direction of the wafer W, and has a length shorter than the radius portion. The linear sensor 43 can capture an area corresponding to a part of the radius of the wafer W. The light source 44 extends in the same direction (parallel) and the same length as the linear sensor 43 and irradiates light toward the grinding surface of the wafer W. Specifically, the light source 44 is the ground surface of the illumination wafer W to illuminate the imaging range of the linear sensor 43.

The judging mechanism 42 is incorporated in a control device that integrally controls the operation of the grinding device, and includes an editing unit 45 for editing a captured image and a judging unit 46 for determining the presence or absence of scratches based on the edited captured image.

In the imaging step, the wafer W after being ground is sucked and held on the holding table 20 as it is positioned below the imaging mechanism 41 as it is. In addition, the holding stage 20 adjusts the inclination of the rotation axis by a tilt adjustment mechanism so that the extending direction of the imaging mechanism 41 (the linear sensor 43) is parallel to the ground surface (holding surface 21a) of the wafer W. .

As shown in FIGS. 3A and 3B, the imaging area of the linear sensor 43 is a portion corresponding to a radius of the wafer W directly below the linear sensor 43. The light source 44 emits light toward the imaging area of the linear sensor 43. The imaging mechanism 41 captures a portion of the radius of the wafer W irradiated by the light from the light source 44 with a linear sensor 43 and rotates the wafer W on the holding table 20 by one turn to capture the wafer W. Grinded surface. In addition, the light irradiated by the light source 44 is a light having a wavelength reflected on the surface of the wafer W, and light having a wavelength that is transparent to the wafer W is not used.

As shown in FIG. 3C, on the to-be-ground surface of the wafer W after grinding, a grid-like dividing line L and an infinite number of regular circular arcs are formed from the center of the wafer W toward the outer periphery. Scratch S. When the to-be-ground surface of the wafer W is captured, a ring-shaped captured image can be obtained as shown in FIG. 3D.

In the captured image shown in FIG. 3D, light and darkness are generated by the scattered light scattered by the light from the light source 44 on the dividing line L (dividing groove) and the scratch S. Specifically, the reflected light of the imaging light is weakened (scattered) due to the fine unevenness formed on the wafer W, so that the scratch S and the dividing line L can be distinguished from the contrast between light and dark.

In particular, in the present embodiment, since the divided image L is included in the captured image, there is a possibility that the amount of data of the captured image will increase in response to this portion. Therefore, the imaging mechanism 41 is set shorter than the radius of the wafer W and the imaging range is set smaller. Thereby, a ring-shaped captured image shown in FIG. 3D can be obtained, and the amount of data of the captured image can be reduced compared to the case where the entire surface of the wafer W is captured. As a result, it becomes possible to reduce the processing load of the determination unit 42 in the subsequent steps.

In addition, the imaging mechanism 41 is arranged along the radial direction of the wafer W, and the holding table 20 holding the wafer W is rotated once to photograph the to-be-ground surface of the wafer W, so that light can be applied to the The exposure is often formed uniformly. As a result, the center of the wafer W is not shifted, and an appropriate captured image of the wafer W can be obtained.

Next, an editing step is performed. In the editing step, the captured image obtained in the image capturing step is subjected to coordinate conversion, and is edited into a band-shaped image as shown in FIG. 4. Specifically, the editing unit 45 (see FIG. 3) sets the radial direction (from the wafer center to the wafer periphery) of the captured image (see FIG. 3D) as the vertical axis, and sets the circumferential direction (from 0 ° to 360 °) is set as the horizontal axis to perform coordinate conversion. As shown in FIG. 4, the edited image obtained by coordinate conversion is represented by a rectangular image (strip image) that is longer in the circumferential direction.

For example, as shown in FIG. 3D parting line S L, and scratches in the band image of FIG. 4, respectively and the straight line curve L _A S _A represented. Note that the band-shaped image in FIG. 4 is extracted and displayed by extracting a part of the radial direction and the circumferential direction in FIG. 3D. In addition, in FIG. 4, for convenience of explanation, a curve L _A corresponding to a dividing line is shown by a broken line. Further, in FIG. 4, configuration is set to S _A S _B of the straight line in the width of the strip in a relatively thick visualized image has a plurality of straight lines.

Thus, with respect to the actual captured image, scratches arcuate curve S is displayed in the edited image strip, is having regular scratches S S _A straight line is displayed. Thereby, in the following determination step, the determination part 46 becomes easy to determine the presence or absence of a scratch. On the other hand, in the captured image of FIG. 3D, the division line L is displayed as a grid-like straight line with respect to the division line L. In the edited band image, the division line L is represented by an arc-shaped curve L _A display. In particular, with respect to the curve is a straight line L _A S _A cross, or the straight line S _A having regularity tends to different curves (curve having no regularity) of FIG. Therefore, the scratches S (straight line S _A ) and the dividing line L (curve L _A ) become easy to distinguish.

Next, a removal step is performed. In the removing step, a grid-shaped straight line (dividing line L) corresponding to the dividing groove is removed from the captured image captured in the imaging step. Specifically, the belt-shaped image is edited, the removal of the straight line S _A tendency different curves L _A. The editing unit 45 edits the captured image into a band image, distinguishes the scratches S from the division line L, and removes the curve L _A (the division line L) without regularity from the band image. In this case, since the straight line S _B are formed on the same regularity S _A straight line having a regular position and orientation, the editing unit 45 is not removed from the strip S _B linear image. As a result of this, a band-like image as shown in FIG. 5 can be obtained.

Next, a judgment step is performed. In the determination step, the presence or absence of scratches is determined based on the band-shaped image obtained in the removal step. For example, the determination unit 46 (see FIG. 3) determines that scratches have occurred when there is an arc or a straight line having a predetermined width or more in the strip-shaped image after the removal step. Specifically, in the strip image shown in FIG. 5, if the width of the regular straight line is larger than the preset width, the determination unit 46 determines that there is a scratch. If the width is equal to or less than a predetermined width, it is determined that there is no scratch. The determination unit 46 also determines that there are scratches when a line other than a regular straight line appears in the band image.

As shown in FIG. 6, in the band-shaped image after the removal step, a relatively thick straight line S _B is displayed along a straight line S _A having regularity. The judging unit 46 detects the width D of the straight line S _B from the band image, and compares the width D with a preset straight line that serves as a reference for determining the presence or absence of scratches. As a result, when the width of the straight line S _B is large, the straight line S _{B is} recognized as a scratch S _B. That is, the determination unit 46 determines that there is a scratch. Further, even if the determination unit 46 detects the width _A of the straight line S, and the straight line width of a predetermined width is formed smaller than, nor will recognize _A straight line S is to be scratch removal.

As such, in the present embodiment, even if a scratch with a regularity such as a grinding mark is displayed in the captured image, a relatively large scratch can be detected from the band-shaped image after the removal step. Or there are no regular scratches. That is, scratches that may affect the subsequent steps or the elements formed on the wafer W can be selected and judged.

As described above, according to this embodiment, it is possible to obtain a photographed image of the ground surface of the wafer W by rotating the holding table 20 while imaging the radial portion of the wafer W with the linear sensor 43. Since the radius portion of the wafer W is illuminated by the light source 44 during imaging, the scratches S and the grid-like straight lines (dividing lines L) corresponding to the dividing grooves V can be recognized from the brightness of the captured image. In particular, the captured image can be edited by an image into a strip, and a straight line S _A regularity represented scratches S. On the other hand, the division line L is represented by a line (for example, a curve L _A ) different from a scratch on a band image. Therefore, it is possible to distinguish the scratches S from the dividing line L. In addition, the presence or absence of scratches can be determined based on the strip-shaped image from which the dividing line L has been removed, whereby the scratches can be appropriately detected.

In addition, in this embodiment, although the structure which provided the imaging | photography of the to-be-ground surface of the wafer W by rotating the holding table 20 by one rotation is provided, it is not limited to this structure. For example, the imaging mechanism 41 may be rotated around the center of the wafer W as an axis.

In the present embodiment, the imaging mechanism 41 is configured to extend by a length corresponding to a part of the radius of the wafer W, but it is not limited to this configuration. The imaging mechanism 41 (the linear sensor 43 and the light source 44) may have a length corresponding to a radius portion of the wafer W, or may be longer than that. By setting the imaging mechanism 41 to a length corresponding to a radius portion of the wafer W, the entire surface of the wafer W can be imaged.

In this embodiment, each of the above steps may be performed by a separate processing device, or all steps may be performed by a single processing device. For example, the grinding step to the judgment step may be performed by a single grinding device. With this, it is possible to dispense with the time required to transport the wafer W to another device for scratch detection or scratch removal.

Moreover, in this embodiment, it is also possible to adjust the development condition of the grinding marks in the captured image by adjusting the brightness of the light source 44 in the imaging step. For example, it is preferable that the brightness of the light source 44 is adjusted so that the grinding marks cannot be captured (not displayed in the captured image). Although there are numerous grinding marks between the regular arc-shaped scratches S and the adjacent scratches S, if all of them are captured, not only the amount of data of the captured image will increase, but also Doubts that it is difficult to judge the presence or absence of scratches.

Therefore, by adjusting the brightness of the light source 44 to intermittently remove the number of grinding marks displayed on the captured image, the amount of data of the captured image can be reduced, and the presence or absence of scratches can be easily judged. Specifically, the light amount of the scattered light is reduced by setting the light source 44 relatively dark (reducing the light amount), so that the number of grinding marks can be cut off in the middle of the captured image or the grinding marks can be prevented from being displayed. On the other hand, when the light source 44 is set to be relatively bright (increasing the light amount), the light amount of the scattered light becomes large, so that the grinding marks become easy to appear in the captured image.

In addition, by adjusting the brightness of the light source 44 in the imaging step, not only the development condition of the grinding marks in the captured image can be adjusted, but also the distance between the imaging mechanism 41 and the wafer W can be adjusted.

In addition, although the present embodiment and the modification have been described, as another embodiment of the present invention, a form in which the above-mentioned embodiment and the modification are combined in whole or in part may be used.

In addition, the embodiment of the present invention is not limited to the above-mentioned embodiment, and various changes, substitutions, and modifications can be made without departing from the gist of the technical idea of the present invention. In addition, if the technical idea of the present invention can be realized in other ways through technological progress or other derived technologies, this method can also be used for implementation. Therefore, the scope of the patent claim covers all embodiments that can be included in the scope of the technical idea of the present invention. Industrial availability

As described above, the present invention has the effect of being able to properly detect scratches by distinguishing the dividing line from scratches, and is particularly useful for a scratch detection method suitable for a DBG program.

10, 20‧‧‧ holding table

11‧‧‧ cutting feed mechanism

12‧‧‧ Cutter

21‧‧‧ multi-well plate

21a‧‧‧ keep face

22‧‧‧Frame

23‧‧‧table rotation mechanism

30‧‧‧Grinding mechanism

31‧‧‧ Spindle

32‧‧‧Grinding Wheel

33‧‧‧Mount

34‧‧‧ grinding stone

34a‧‧‧ ground

35‧‧‧Grinding feed mechanism

40‧‧‧Scratch detection agency

41‧‧‧camera

42‧‧‧ Judgment agency

43‧‧‧Linear Sensor

44‧‧‧light source

45‧‧‧ Editorial Department

46‧‧‧Judgment Department

A‧‧‧arrow

D‧‧‧Width

L‧‧‧ dividing line

L _A ‧‧‧ Curve

S‧‧‧ scratch

S _A , S _B ‧‧‧Straight

T1, T2‧‧‧protective tape

V‧‧‧ Divided trench

W‧‧‧ Wafer

FIG. 1 is a schematic diagram showing an example of a processing groove forming step according to this embodiment. 2A and 2B are schematic views showing an example of a grinding step in the present embodiment. 3A to 3D are schematic diagrams showing an example of an imaging procedure in this embodiment. FIG. 4 is a schematic diagram showing an example of an editing procedure in the present embodiment. FIG. 5 is a schematic diagram showing an example of a removal step in the present embodiment. FIG. 6 is a schematic diagram showing an example of a judging procedure in this embodiment.

Claims (2)

A scratch detection method is to detect the presence or absence of scratches in a wafer division. The wafer division is formed on a wafer on the front surface where a component is formed by dividing a predetermined line division. After dividing the predetermined line to form a division groove with a depth that is not completely cut, the back surface is ground with a grinding stone to expose the division groove to the back side and the wafer is divided. The presence or absence of scratches is detected by the ground surface of the back surface of the wafer ground by the grinding stone. The imaging mechanism includes a linear sensor that captures the ground surface extending in the radial direction of the wafer, and A light source extending parallel to the linear sensor and illuminating the surface to be ground, the scratch detection method includes the following steps: an imaging step, the imaging mechanism is arranged to extend the direction of the imaging mechanism parallel to the radial direction within the radius of the wafer Positioning, and rotating the holding table holding the wafer around the center of the wafer, so that the imaging mechanism annularly photographs the ground surface to obtain light from the light source in the dividing groove and the scraping Scattered light A formed photographic image; a removing step of removing a grid-like straight line corresponding to the dividing groove from the photographed image captured in the photographing step; and a judging step in the image after the removing step If there is an arc line or straight line with a predetermined width or more, it is judged that scratches have occurred. According to the scratch detection method of claim 1, wherein the brightness of the light source is adjusted so that the camera mechanism cannot capture the brightness of the grinding marks formed on the wafer by the grinding stone.