JP7366637B2 - Workpiece confirmation method and processing method - Google Patents

Description

The present invention relates to a confirmation method for checking the back side of a workpiece whose back side is fixed to a tape and whose front side is exposed and divided.

In a pre-cutting process before dicing a semiconductor wafer, which is a plate-shaped workpiece, it is known to determine whether the conditioning of the cutting blade is sufficient based on the state of backside chipping.

In order to make this determination, the workpiece for pre-cutting is carried out once from the processing device and the back side of the workpiece is observed, but methods that omit carrying out and observation are also known.

In Patent Document 1, based on the fact that there is a positive correlation between the back side chipping state of the workpiece and the machining load that the chuck table receives from the cutting blade, that is, the larger the machining load is, the greater the back side chipping is. By measuring the machining load acting on the chuck table during pre-cutting, the backside chipping state at the time of pre-cutting can be appropriately grasped from the measured machining load.

Japanese Patent Application Publication No. 2006-303367

On the other hand, the workpiece after dicing is observed under a microscope to measure the size of chips and cracks, and to control processing quality, but improvements to the conventional method are desperately needed.

In other words, in order to measure chipping and cracking on the back side, transfer work (reapplying the tape) is performed once, or the chip is picked up by extraction, the front side of the chip is pasted on tape, and the back side is measured. It was necessary to expose the object before observing it, which made the work complicated.

Therefore, a method can be considered in which a workpiece that has been attached to a tape and divided is imaged with a camera through the tape from the back side and observed.

However, unlike the front side, the back side is different from the front side, and even if minute chips or cracks occur on the back side, they will not clearly appear on the captured image because they are attached to the tape. In this regard, although it is not impossible to identify chippings and cracks by visual observation, there is a problem in that it is difficult to automatically identify chippings and cracks by processing the captured image.

In view of the above, the present invention proposes a new technique for reliably automatically determining chipping or cracking on the back side of a workpiece based on a captured image of the back side of the workpiece.

According to one aspect of the present invention, there is provided a workpiece confirmation method in which the back side of a workpiece is fixed to a tape and the front side is exposed and the workpiece is divided. A method for checking a workpiece, comprising: an imaging step of capturing an image with an infrared camera to form a captured image; and a detection step of detecting chipping and/or cracks occurring on the back surface from the captured image formed in the imaging step. shall be.

In the imaging step, the infrared camera takes an image with its focus positioned on the surface of the workpiece.

Further, the workpiece processing method includes an attaching step of attaching the back side of the workpiece to a tape to expose the front surface of the workpiece, and a dividing step of dividing the workpiece to which the tape is attached. An imaging step of imaging the workpiece from the back side of the workpiece through the tape to form a captured image; and/or a detection step of detecting cracks.

According to the present invention, the state of the back surface of the workpiece can be confirmed based on an image taken by an infrared camera from the back side through the tape, and it is possible to reduce the number of work steps and time. Furthermore, by using an infrared camera, chipping and cracks on the back side can be reliably detected, increasing the reliability of the inspection.

In addition, defective locations such as chippings and cracks appear black with low brightness on the captured image, and based on this, it becomes possible to detect and measure the size of chippings and cracks. Specifically, the captured image is subjected to multi-value processing, and edges detected by edge detection processing are used as a reference, and areas with brightness within a predetermined range are detected as areas where cracks or chipping have occurred. Furthermore, the size of cracks and chipping can be measured based on the number of pixels in the area.

In addition, a series of steps from dividing the workpiece to detecting chipping and/or cracks on the back side can be carried out in a short time, and since the detection accuracy is high, the reliability of the inspection can be improved.

FIG. 2 is a perspective view schematically showing an object to be inspected. FIG. 2 is a perspective view schematically showing an object to be inspected divided into devices. FIG. 1 is a perspective view schematically showing a processing device including an inspection device. FIG. 2 is a top view schematically showing a processing device including an inspection device. FIG. 2 is a perspective view schematically showing an inspection device. FIG. 6(A) is a perspective view schematically showing the inspection object holding mechanism, and FIG. 6(B) is a perspective view schematically showing the imaging mechanism. FIG. 7(A) is a top view schematically showing the mounting section, and FIG. 7(B) is a cross-sectional view schematically showing the mounting section. FIG. 2 is a cross-sectional view schematically showing the positional relationship among the object holding mechanism, the imaging mechanism, and the object when inspecting the object. FIG. 3 is a schematic diagram of a second imaging unit composed of an infrared camera. FIG. 2 is a schematic diagram of an object to be inspected viewed from the side. FIG. 11A is a diagram illustrating an example of a captured image. FIG. 11B is a diagram schematically showing the shape of chipping as seen from the side of the device.

Embodiments according to one aspect of the present invention will be described with reference to the accompanying drawings. The inspection device according to the present embodiment is capable of inspecting, for example, a workpiece (workpiece) processed by a processing device as an object to be inspected, by simultaneously imaging the object to be inspected from the upper surface and the lower surface.

First, the object to be inspected will be explained. The object to be inspected is, for example, a substantially disk-shaped wafer made of a material such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductors. . Alternatively, the object to be inspected is a substrate made of a material such as sapphire, glass, or quartz. Further, the object to be inspected may be a package substrate or the like that includes a plurality of device chips sealed with a mold resin or the like.

FIG. 1 is a perspective view schematically showing a wafer, which is an example of the object to be inspected 1. As shown in FIG. The surface 1a of the object to be inspected 1 is divided, for example, by a plurality of division lines called streets 3 that intersect with each other. Devices 5 such as ICs (Integrated Circuits) and LSIs (Large-Scale Integrated Circuits) are formed in each area defined by streets 3 on the front surface 1a of a wafer, which is the object 1 to be inspected. Dividing the wafer along streets 3 allows the formation of individual device chips.

To divide the inspection object 1, for example, a laser processing device is used which irradiates the inspection object 1 with a laser beam along the streets 3 and processes the inspection object 1 with a laser beam. Alternatively, a cutting device capable of cutting the object to be inspected 1 along the streets 3 with an annular cutting blade is used.

Before carrying the inspected object 1 into a processing device such as a cutting device or a laser processing device, as shown in FIG. The frame unit 11 is formed by integrating the tape 7 and the frame unit 11. The object 1 to be inspected, to which the tape 7 is attached and mounted on the frame 9 via the tape 7, is transported in this state to a processing device and processed.

FIG. 2 shows the state of the inspected object 1 after it has been processed by a processing device and divided into devices 5, 5, and this example shows a case where cutting has been performed by blade dicing.

In order to confirm that the inspected object 1 has been appropriately processed along the streets 3, the inspection apparatus according to the present embodiment images the processed portion of the inspected object 1 and inspects the inspected object 1. In this inspection device, for example, the inspected object 1 is inspected along the street 3, and the position where machining marks are formed, the shape and size of chips called chipping formed on the inspected object 1 along the machining marks, Distribution, cracks, etc. will be investigated. Further, the size of the device chip formed by dividing the inspection object 1 is confirmed. However, the usage of the inspection device is not limited to this.

The present embodiment will be described below using an example in which the object 1 to be inspected is a wafer on which a plurality of devices 5 are formed and divided along the streets 3, but the object 1 to be inspected is not limited to this. The inspected object 1 inspected by the inspection apparatus according to this embodiment does not need to be processed by a processing apparatus or the like.

The inspection device according to the present embodiment is used, for example, by being incorporated into a processing device that includes a processing unit that processes an object to be inspected 1 as a workpiece. However, the inspection device does not need to be incorporated into the processing device, and may be independent. FIG. 3 is a perspective view schematically showing a processing device 2 incorporating an inspection device according to the present embodiment.

The processing device 2 includes a base 4 that supports each component. A cassette support base 6 that can be raised and lowered is provided at the front corner of the base 4. A cassette that accommodates a plurality of frame units 11 is placed on the upper surface of the cassette support base 6.

A rectangular opening 10 that is long in the X-axis direction (processing feed direction) is formed at a position adjacent to the cassette support 6 on the upper surface of the base 4. The opening 10 includes a workpiece holding unit 14, an X-axis movement mechanism (not shown) for moving the moving table 12 on which the workpiece holding unit 14 is placed in the X-axis direction, and the X-axis movement mechanism. A dust-proof and drip-proof cover 10a is provided.

The processing device 2 is provided with a transport unit 16 that transports the frame unit 11 housed in a cassette placed on the cassette support stand 6 in and out. The transport unit 16 has a pair of guide rails 18 arranged in front of the upright portion of the base 4 and parallel to the Y-axis direction. A moving body 20 is slidably attached to the pair of guide rails 18. A nut portion (not shown) is provided on the rear side of the movable body 20, and a ball screw 22 parallel to the guide rail 18 is screwed into this nut portion.

A pulse motor 24 is connected to one end of the ball screw 22 . When the ball screw 22 is rotated by the pulse motor 24, the movable body 20 moves in the Y-axis direction along the guide rail 18. An arm portion 26 extending along the X-axis direction is connected to the lower end of the movable body 20 via a lifting mechanism. A plurality of suction parts 28 are arranged on the lower surface of the arm part 26 and are arranged in correspondence with the size of the frame 9. Furthermore, a push-pull mechanism 30 facing the cassette support base 6 is disposed at the center of the arm portion 26 .

Furthermore, a pair of transport rails 8 are provided on the upper surface of the base 4 so as to straddle the opening 10 . The pair of transport rails 8 are spaced apart from each other with a width smaller than the diameter of the frame 9, but are movable in directions away from each other.

The transport unit 16 can move in the Y-axis direction, insert the tip of the push-pull mechanism 30 into the cassette placed on the cassette support base 6, and grip the frame 9 of the frame unit 11 accommodated in the cassette. When the frame 9 is gripped by the push-pull mechanism 30 and the arm portion 26 is moved in the opposite direction along the Y-axis direction, the frame unit 11 can be pulled out onto the pair of transport rails 8.

Thereafter, the grip of the frame 9 by the push-pull mechanism 30 is released, the suction section 28 of the transport unit 16 is brought into contact with the frame 9 from above, and the frame 9 is suction-held by the suction section 28 . Then, by lifting the frame unit 11 upward from the transport rail 8, widening the interval between the pair of transport rails 8, and lowering the frame unit 11, the frame unit 11 can be transported onto the workpiece holding unit 14.

The workpiece holding unit 14 is, for example, a chuck table that holds the test object 1 (wafer). A porous member is disposed on the upper surface of the workpiece holding unit 14, and the upper surface of the porous member serves as a holding surface for holding the frame unit 11. The porous member is connected to a suction source (not shown) via a suction path (not shown) formed inside the workpiece holding unit 14. The workpiece holding unit 14 can hold the frame unit 11 by suction.

FIG. 4 is a top view schematically showing the configuration of the processing device 2. As shown in FIG. The processing device 2 includes a processing unit 32 that processes the inspection object 1 as a workpiece. The processing unit 32 includes, for example, an annular cutting blade 34, a spindle housing 36 that accommodates a spindle that is inserted into a through hole of the cutting blade 34 and serves as a rotation axis when rotating the cutting blade 34, and the spindle. This is a cutting unit that includes a motor (not shown) that rotates the. When the rotating cutting blade 34 cuts into the workpiece held by the workpiece holding unit 14, the workpiece is cut.

However, although the processing apparatus 2 shown in FIG. 4 is equipped with two processing units 32 that cut the object 1 to be inspected, the processing apparatus 2 is not limited to this. For example, the processing device 2 may include only one processing unit 32. Further, the processing unit 32 may be a laser processing unit that processes the inspection object 1 with a laser beam.

As shown in FIGS. 3 and 4, the processing device 2 has an opening 38 at a position adjacent to the opening 10 on the upper surface of the base 4. As shown in FIGS. A cleaning device 40 that can clean the inspected object 1 processed by the processing unit 32 is disposed inside the opening 38 . The processed object 1 is transported onto the cleaning table of the cleaning device 40 by the transport unit 16 or the like, and high pressure is applied to the object 1 from a nozzle (not shown) while rotating the cleaning table on which the object 1 is placed at high speed. The object to be inspected 1 can be washed by jetting the washing water.

Note that the inspection object 1 may be carried into the cleaning device 40 by the transport unit 42. The transport unit 42 has a pair of guide rails 44 arranged in front of the upright portion of the base 4 and parallel to the Y-axis direction. A moving body 46 is slidably attached to the pair of guide rails 44 . A nut portion (not shown) is provided on the rear side of the movable body 46, and a ball screw 48 parallel to the guide rail 44 is screwed into this nut portion.

A pulse motor 50 is connected to one end of the ball screw 48 . When the ball screw 48 is rotated by the pulse motor 50, the moving body 46 moves in the Y-axis direction along the guide rail 44. An arm portion 52 is connected to the lower end of the movable body 46 via a lifting mechanism. The arm portion 52 is provided with a holding mechanism 54 in which a plurality of suction portions (not shown) are provided corresponding to the size of the frame 9.

For example, a plurality of devices 5 are formed on the surface of an object to be inspected 1, and when the object to be inspected 1 is divided into devices 5 by the processing unit 32 of the processing apparatus 2, individual device chips are formed. In order to confirm that the inspected object 1 has been properly processed, the inspected object 1 after processing is inspected by the inspection device 56 according to this embodiment.

After the cleaning device 40 completes cleaning of the test object 1, the holding mechanism 54 holds the test object 1, and the transport unit 42 transports the test object 1 to the test device 56. Note that the object to be inspected 1 may be transported to the inspection device 56 by the transport unit 16 instead of the transport unit 42. Here, if the direction of the cleaning table is adjusted in advance before the transport units 16 and 42 hold the object 1 to be inspected, the direction of the object 1 to be inspected carried into the inspection device 56 can be adjusted to a predetermined orientation.

For example, in the inspection device 56, the inspected object 1 is inspected along dividing grooves formed in the inspected object 1, and the shape and size of chips called chippings formed on the inspected object 1 along the dividing grooves. The cracks, distribution, cracks, etc. will be investigated. Further, the size of the device chip formed by dividing the inspection object 1 is confirmed.

The inspection device 56 is an inspection device that can simultaneously observe the same position of the object 1 to be inspected from both the upper surface side (front surface 1a side) and the lower surface side (back surface 1b side). The inspection device 56 is incorporated into the processing device 2, as shown in FIG. 3, etc., and can immediately inspect the inspected object 1 after processing. Next, the inspection device 56 according to the present embodiment will be described using an example in which the inspection device 56 is incorporated in the processing device 2, but the inspection device 56 is not limited to this.

FIG. 5 is a perspective view schematically showing the inspection device 56. As shown in FIG. The inspection device 56 includes a base 60 that supports each component of the inspection device 56. An opening 62 is formed in the base 60 along the X-axis direction. The inspection device 56 includes an inspection object holding mechanism 58 that is arranged so as to straddle the opening 62 of the base 60 and can hold the inspection object 1, and an image of the inspection object 1 held by the inspection object holding mechanism 58. An imaging mechanism 82 is provided.

The inspection device 56 includes an X-axis movement unit 64a that can relatively move the inspection object holding mechanism 58 and the imaging mechanism 82 along the X-axis direction, and a Y-axis movement unit 64a that can relatively move the inspection object holding mechanism 58 and the imaging mechanism 82 along the Y-axis direction. A moving unit 64b is provided. FIG. 6A schematically shows a perspective view of the X-axis moving unit 64a of the inspection device 56 and the inspection object holding mechanism 58. FIG. 6(B) schematically shows a perspective view of the imaging mechanism 82.

The X-axis moving unit 64a includes a guide rail 66a extending along the X-axis direction on the side of the opening 62 on the top surface of the base 60. Furthermore, a guide rail 66b extending parallel to the guide rail 66a is provided on the upper surface of the base 60 on the side of the opening 62 on the side opposite to the guide rail 66a. A movable body 68a is slidably mounted on the guide rail 66a, and a movable body 68b is slidably mounted on the guide rail 66b.

A bridge-like support structure 74 is disposed above the movable body 68a and the movable body 68b so as to straddle both the movable bodies 68a and 68b. Further, a nut portion (not shown) is provided at the lower end of one of the movable bodies 68a and the movable body 68b, and a ball screw 70 parallel to the guide rails 66a and 66b is screwed into this nut portion.

A pulse motor 72 is connected to one end of the ball screw 70. When the ball screw 70 is rotated by the pulse motor 72, the movable bodies 68a and 68b move in the X-axis direction along the guide rails 66a and 66b, and the bridge-like support structure 74 moves in the X-axis direction. The inspection object holding mechanism 58 is supported by the support structure 74 at a position overlapping with the opening 62 of the base 60 . The X-axis moving unit 64a can move the inspection object holding mechanism 58 along the X-axis direction by moving the support structure 74 along the X-axis direction.

The inspection object holding mechanism 58 has a mounting section 76 having a transparent body exposed at the top and bottom. The transparent body is made of a material such as glass or resin, for example. The upper surface of the transparent body becomes a mounting surface 76a on which the object to be inspected 1 is mounted via the tape 7. The inspection object holding mechanism 58 can support the inspection object 1 placed on the mounting surface 76a.

FIG. 7(A) is a top view schematically showing the inspected object holding mechanism 58, and FIG. 7(B) is a sectional view schematically showing the inspected object holding mechanism 58. Since the transparent body is also exposed on the back side opposite to the mounting surface 76a, the object to be inspected 1 placed on the mounting surface 76a can be observed from the lower surface side.

The inspection object holding mechanism 58 includes a tape holding section 78 having a tape suction holding surface 78b on the outer peripheral side of the mounting section 76. The tape holding section 78 has a suction groove 78a formed in a tape suction holding surface 78b. A suction source (not shown) is connected to the suction groove 78a via a suction path (not shown). The inspection object holding mechanism 58 further includes an annular frame support part 80 that is arranged around the tape holding part 78 and can support the frame 9 of the frame unit 11.

When the frame unit 11 is placed on the inspection object holding mechanism 58 so that the frame support part 80 and the frame 9 overlap, and the suction source is activated, the object is attached to the inspection object holding mechanism 58 via the tape 7. The test object 1 is held under suction. At this time, the space between the inspection object holding mechanism 58 and the tape 7 is sucked and the tape 7 comes into close contact with the entire surface of the mounting surface 76a, so that the inspection object 1 held by the inspection object holding mechanism 58 is It will not shift during the inspection.

For example, even when the inspection object 1 is a warped wafer or the like, when the inspection object holding mechanism 58 holds the inspection object 1, the tape 7 comes into close contact with the entire mounting surface 76a. Therefore, the object to be inspected 1 is suction-held by the object-to-be-inspected holding mechanism 58 in a state where the warpage is alleviated. When the warpage of the inspected object 1 held by the inspected object holding mechanism 58 is alleviated, the focus of the imaging unit becomes difficult to shift from the inspected object 1 when each region of the inspected object 1 is imaged one after another. Therefore, the inspected object 1 can be imaged more clearly. In particular, in the configuration of the present application, when an infrared camera is disposed on the back side and images are taken with the focus positioned on the front surface, it is effective to reduce the warpage of the object to be inspected 1.

Here, the height of the mounting surface 76a of the mounting section 76 may be lower than the height of the tape suction holding surface 78b of the tape holding section 78. Further, the suction groove 78a formed in the tape suction holding surface 78b may reach the mounting portion 76, as shown in FIG. 7(A). In this case, when the frame unit 11 is placed on the inspection object holding mechanism 58, a gap is formed between the tape 7 and the mounting surface 76a, and the suction source connected to the suction groove 78a is activated. When the tape 7 overlaps the inspection object 1 through the gap, the area of the tape 7 that overlaps the inspected object 1 is quickly sucked.

Specifically, the height of the mounting surface 76a of the mounting section 76 may be about 1 mm lower than the height of the tape suction and holding surface 78b of the tape holding section 78.

FIG. 8 schematically shows a cross-sectional view of the frame unit 11 and the test object holding mechanism 58 when the test object 1 is suction-held by the test object holding mechanism 58. As shown in FIG. 8, when the suction source is activated, the gap between the tape 7 and the mounting surface 76a is evacuated, and the tape 7 and the mounting surface 76a are brought into close contact with each other.

Note that after the inspection of the inspection object 1 is completed, when the suction source is stopped and the frame unit 11 is taken out from the inspection object holding mechanism 58, the tape 7 is easily peeled off from the mounting surface 76a. For example, the mounting surface 76a may be coated with fluororesin.

Next, the imaging mechanism 82 will be explained. As shown in FIG. 5, the imaging mechanism 82 includes, for example, a gate-shaped support structure 84 disposed on the base 60 so as to straddle the opening 62, the X-axis moving unit 64a, and the inspection object holding mechanism 58. Supported. A Y-axis moving unit 64b that moves the imaging mechanism 82 along the Y-axis direction is disposed on the support structure 84.

The Y-axis moving unit 64b includes a pair of guide rails 86 arranged along the Y-axis direction on the upper surface of the support structure 84. A moving body 88 that supports the imaging mechanism 82 is slidably mounted on the pair of guide rails 86 . A nut portion (not shown) is provided on the lower surface of the movable body 88, and a ball screw 90 parallel to the pair of guide rails 86 is screwed into this nut portion.

A pulse motor 92 is connected to one end of the ball screw 90. When the ball screw 90 is rotated by the pulse motor 92, the moving body 88 moves in the Y-axis direction along the guide rail 86, and the imaging mechanism 82 moves in the Y-axis direction. The X-axis moving unit 64a and the Y-axis moving unit 64b cooperate to function as a moving unit that can relatively move the inspection object holding mechanism 58 and the imaging mechanism 82 in a direction parallel to the mounting surface 76a.

The imaging mechanism 82 includes a first imaging unit 106a disposed above the placement section 76 of the inspection object holding mechanism 58, a second imaging unit 106b disposed below the placement section 76, and a second imaging unit 106b disposed below the placement section 76. and. As shown in FIG. 6(B), the imaging mechanism 82 further includes a connecting portion 108 that connects the first imaging unit 106a and the second imaging unit 106b.

The first imaging unit 106a is supported by a columnar support structure 94a. An elevating mechanism 96a for elevating and lowering the first imaging unit 106a is disposed on the front surface of the columnar support structure 94a. The lifting mechanism 96a is screwed into a pair of guide rails 98a along the Z-axis direction, a moving body 100a slidably attached to the guide rails 98a, and a nut provided on the rear surface of the moving body 100a. and a ball screw 102a.

A first imaging unit 106a is fixed to the front of the moving body 100a. A pulse motor 104a is connected to one end of the ball screw 102a. When the ball screw 102a is rotated by the pulse motor 104a, the movable body 100a moves in the Z-axis direction along the guide rail 98a, and the first imaging unit 106a fixed to the movable body 100a moves up and down.

The upper end of the connecting portion 108 is connected, for example, to the lower end on the rear side of the support structure 94a, and the lower end of the connecting portion 108 is connected to the upper end on the rear side of the columnar support structure 94b that supports the second imaging unit 106b. connected to the section. A lifting mechanism 96b configured in the same manner as the lifting mechanism 96a provided on the supporting structure 94a is provided on the front surface of the supporting structure 94b.

The lifting mechanism 96b is screwed into a pair of guide rails 98b along the Z-axis direction, a moving body 100b slidably attached to the guide rails 98b, and a nut provided on the rear surface of the moving body 100b. and a ball screw 102b. A pulse motor 104b is connected to one end of the ball screw 102b. When the ball screw 102b is rotated by the pulse motor 104b, the second imaging unit 106b fixed to the front surface of the moving body 100b moves up and down.

The first imaging unit 106a faces downward and can image the object 1 placed on the upper surface of the object holding mechanism 58 from above. Further, the second imaging unit 106b faces upward, and can image the object 1 to be inspected from below through the tape 7 and the mounting section 76 made of a transparent body. The first imaging unit 106a and the second imaging unit 106b are, for example, an area camera, a line camera, a 3D camera, an infrared camera, or the like.

In the imaging mechanism 82, the first imaging unit 106a and the second imaging unit 106b are connected to each other by the connecting portion 108 so that their positions in the direction parallel to the mounting surface 76a are approximately the same. That is, the same position on the upper surface side and the lower surface side of the object to be inspected 1 can be imaged. The connecting portion 108 has a shape that does not interfere with the object holding mechanism 58 no matter which part of the object 1 is used as the imaging point.

Next, an embodiment of imaging and inspection by the imaging unit will be described.
In FIG. 8, the surface of the inspection object 1 located on the upper side is imaged by a first imaging unit 106a composed of a visible light camera.

The surface of the object to be inspected 1 is exposed, and a clear image is captured by the first imaging unit 106a composed of a visible light camera, and chipping that has occurred on the surface of the object to be inspected is detected based on the captured image. Automatic detection of cracks and cracks becomes possible.

On the other hand, the back surface of the inspection object 1 located on the lower side and attached to the tape 7 is imaged by a second imaging unit 106b composed of an infrared camera.

FIG. 9 is a schematic diagram of the second imaging unit 106b configured with an infrared camera, and includes an objective lens unit 201 whose focal length is adjustable and an infrared CCD 202. The light source 203 may be provided integrally with the objective lens unit 201, or may be provided separately. Further, the specific configuration of the second imaging unit 106b is not particularly limited.

FIG. 10 is a schematic diagram of the inspected object 1 viewed from the side, and the devices 5 attached to the tape 7 are arranged on the upper surface of the transparent mounting section 76 of the inspected object holding mechanism 58. There is. Machining marks 3a are formed between each device 5, and chipping 5c appears on the back surface 5b of the device 5.

When the second imaging unit 106b focuses the image on the surface 5a of the device 5, the infrared light R1 at the chipping 5c is emitted from the surface because an interface is formed at the chipping 5c due to a fracture or the like. 5a (patterned surface), and the amount of reflection from the surface 5a decreases. As a result, an area with lower brightness compared to other parts is formed in the captured image (imaged as black).

On the other hand, since the infrared light R2 at the location where there is no chipping 5c reaches the surface 5a, an area with higher brightness compared to the location where the chipping 5c exists is defined in the captured image.

FIG. 11A is an example of a captured image, and shows a case where chipping 5c that is long in the X direction occurs in area M1 on the back surface 5b of the device 5. At a location corresponding to this area M1, as shown in FIG. 11(B), chipping 5c occurs in the lateral direction on the back surface side. The area of this chipping 5c is defined on the captured image as an area with different brightness from other parts of the device 5 and the processing marks 3a.

More specifically, in area M1 on the captured image, an area is defined that is brighter than the processing marks 3a and darker than the back surface 5b of the device. Then, it is possible to detect an area where the brightness is within a predetermined range as an area where chipping 5c has occurred, and it is also possible to easily measure the size etc. of the area based on the number of pixels of the area.

Similarly, in another area M2, a semicircular chipping 5c occurs, thereby defining a region having a brightness different from other parts of the device 5 and the processing marks 3a. Then, it is possible to detect an area where the brightness is within a predetermined range as an area where chipping has occurred, and it is also possible to easily measure the size, etc. of the area based on the number of pixels in the area.

Similarly, in another area M3, a linear crack 5d is generated, thereby forming a linear line with low brightness in the region of the device 5. Then, by using a line whose brightness falls within a predetermined range, it becomes possible to detect the line as an area where a crack (crack) 5d has occurred, and the size etc. of the line can also be easily measured based on the number of pixels of the line. It becomes possible. Note that even in the case of a linear crack (crack) 5d, an interface similar to the fracture interface shown in FIG. 10 is formed, so that it can be represented in an image as a linear line.

Next, each step carried out in the method for processing a workpiece and the method for inspecting an object to be inspected using the above-described apparatus configuration will be described.

<Application step>
This is a step of attaching the back side of the workpiece to tape to expose the front side of the workpiece.
FIG. 1 shows an example in which a wafer (inspection object 1) as a workpiece is attached to a tape 7 and the surface 1a is exposed.
The workpiece is, for example, a semiconductor wafer, and a wafer on which no pattern is formed is also assumed.
In addition to adhesion using a glue layer, adhesion is performed by pressure bonding of a tape with only a base material without a glue layer, thermocompression bonding, or the like.

<Dividing step>
This is the step of dividing the workpiece to which the tape is attached.
Dividing refers to dividing the workpiece into separate areas along dividing lines called streets, and in addition to blade dicing, which cuts and divides the workpiece with a blade, there is also a method that has absorbency for the workpiece. Laser dicing, which divides the workpiece by irradiating it with a laser beam of a certain wavelength, and tape expansion of a workpiece that has been subjected to SD processing (STEALTH DICING: registered trademark), which forms a modified layer with a laser beam of a wavelength that is transparent to the workpiece. The so-called DBG (Dicing Before Grinding) process involves forming half-cut grooves on the surface of the workpiece along the planned dividing line with a blade and then dividing the workpiece by back grinding, and grinding the back side of the workpiece after performing SD processing. SDBG (Stealth Dicing Before Grinding) processing, etc., in which the image is divided into two parts, can be used.
FIG. 2 shows the state of the wafer (inspection object 1) after being divided by blade dicing.

<Imaging step>
This is an imaging step in which an infrared camera images the workpiece from the back side of the workpiece through the tape to form a captured image.
As shown in FIGS. 7 and 10, a second imaging unit 106b constituting an infrared camera captures an image from the back surface 5b side of the workpiece. In this imaging, as shown in FIG. 10, by utilizing the difference in transmittance of infrared light R1 and R2 between the chipping 5c location and other locations, it is possible to make the brightness of both locations different in the captured image. It makes it possible.
Note that in this imaging step, the front side of the workpiece can be simultaneously imaged by the first imaging unit 106a constituted by a visible light camera.

<Detection step>
This is a detection step of detecting chipping or cracking that has occurred on the back surface based on the captured image formed in the imaging step.
As shown in FIG. 11A, parts with different brightness are formed on the captured image showing the back surface 5b of the device 5. Then, the captured image is subjected to multi-value processing, edge detection processing is performed, and an edge detected is used as a reference, and an area where the brightness falls within a predetermined range is detected as an area where cracks or chipping have occurred. Furthermore, the size of cracks and chippings is measured based on the number of pixels in the area.

The present invention can be implemented as described above.
That is, as shown in FIGS. 10 and 11(A), the workpiece confirmation method includes checking the backside 5b of the divided workpiece with the backside fixed to the tape 7 and the front side 5a exposed,
an imaging step of imaging the workpiece from the back side 5b side via the tape 7 with an infrared camera (second imaging unit 106b) to form a captured image;
The object of the present invention is to provide a workpiece confirmation method including a detection step of detecting chippings 5c and/or cracks 5d generated on the back surface 5n from the captured image formed in the imaging step.

As a result, the state of the back surface of the workpiece can be confirmed based on an image taken by an infrared camera from the back side through the tape, and it is possible to reduce the number of work steps and time. Furthermore, by using an infrared camera, chipping and cracks on the back side can be reliably detected, increasing the reliability of the inspection.

Further, as shown in FIGS. 10 and 11(A), in the imaging step, the focus of the infrared camera (second imaging unit 106b) is positioned on the surface of the workpiece and the image is taken.

This makes it possible to make defects such as chippings and cracks appear black (lower brightness) on the captured image, and based on this, it becomes possible to detect and measure the size of chippings and cracks.

Also, a method of processing a workpiece,
an attaching step of attaching the back side of the workpiece to the tape to expose the front side of the workpiece;
a dividing step of dividing the workpiece to which the tape is attached;
an imaging step of imaging the work with an infrared camera from the back side of the work through the tape to form a captured image;
a detection step of detecting chipping and/or cracks occurring on the back surface based on the captured image formed in the imaging step;
This is a method for processing a workpiece having the following characteristics.

As a result, a series of steps from dividing the workpiece to detecting chipping and/or cracks on the back side can be carried out in a short time, and since the detection accuracy is high, the reliability of the inspection can be increased.

1 Inspection object 1a Front side 1b Back side 2 Processing device 3 Street 3a Processing marks 4 Base 5 Device 5a Front side 5b Back side 5c Chipping 5d Crack 5n Back side 7 Tape 9 Frame 11 Frame unit 76 Placement section 76a Placement surface 78 Tape holding section 78a Suction groove 78b Tape suction holding surface 82 Imaging mechanism 84 Support structure 106a First imaging unit 106b Second imaging unit 201 Objective lens unit 202 Infrared CCD
203 Light source R1 Infrared light R2 Infrared light

Claims (2)

A workpiece confirmation method in which the back side of the workpiece is fixed to tape and the front side is exposed and the workpiece is divided.
an imaging step of imaging the workpiece from the back side through the tape with an infrared camera to form a captured image;
a detection step of detecting chipping and/or cracks occurring on the back surface from the captured image formed in the imaging step ;
In the imaging step, the workpiece is confirmed by imaging the workpiece while the focus of the infrared camera is positioned on the surface of the workpiece . A workpiece processing method,
an attaching step of attaching the back side of the workpiece to a tape to expose the front surface of the workpiece;
a dividing step of dividing the workpiece to which the tape is attached;
an imaging step of imaging the work with an infrared camera from the back side of the work through the tape to form a captured image;
a detection step of detecting chipping and/or cracks occurring on the back surface based on the captured image formed in the imaging step;
has
The method for processing a workpiece includes, in the imaging step, imaging the workpiece while the focus of the infrared camera is positioned on the surface of the workpiece .