JP2024065440A - Detection method and processing device - Google Patents

Abstract

[Problem] To detect the front and back sides of a wafer carried into a processing device. [Solution] A detection method for detecting the front and back sides of a wafer having a first orientation flat and a second orientation flat adjacent to each other and different in length on its outer periphery, the outer periphery of the wafer is imaged by an imaging unit, the outer shape of the wafer is detected, and the front and back sides of the wafer are determined based on the detected outer shape of the wafer. When the first orientation flat is located adjacent to the second orientation flat in the clockwise direction in a specific field of view, it is determined that one of the front and back sides of the wafer faces upward, and when the first orientation flat is located adjacent to the second orientation flat in the counterclockwise direction in the specific field of view, it is determined that the other of the front and back sides of the wafer faces upward. [Selected Figure] Figure 5

Description

The present invention relates to a processing device that performs a series of steps from unloading each wafer from a cassette that contains multiple wafers, processing them, and then storing them back in the cassette. The present invention relates to a detection method for detecting the front and back sides of each wafer before processing, and the processing device.

In the manufacturing process of device chips used in electronic devices such as mobile phones and computers, first, multiple devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed on the surface of a semiconductor wafer. Next, the wafer is ground from the back side to thin it to a specified thickness, the back side is polished, and the wafer is divided for each device to form individual device chips.

Wafer grinding, polishing, division, and other processing are performed by various types of processing equipment that includes a chuck table that holds the wafers and a processing unit that processes the wafers held by the chuck table. The wafers are stored in a cassette before being carried into the processing equipment. Then, a cassette containing multiple wafers is carried into the processing equipment. An automatic processing program is registered in the control unit of the processing equipment, which executes a series of steps to sequentially remove the wafers stored in the cassette, process them, and return them to the cassette.

The wafers processed by the processing device have an approximately circular outer shape. The outer periphery of the wafer is formed with cutouts such as orientation flats and notches that indicate the crystal orientation of the wafer. Processing devices are known that identify the outer shape of the wafer and use the outer shape to determine the position of the center and the cutouts (see Patent Document 1).

JP 2011-40637 A

Disc-shaped wafers made of compound semiconductors such as SiC (silicon carbide) and GaN (gallium nitride) can have different processability on the front and back sides. Normally, the wafers are stored in a cassette in an orientation suitable for processing in the processing equipment. That is, the wafers are stored in the cassette with the side that should face upwards during processing in the processing equipment facing upwards, and the side that should face downwards during processing facing downwards. The processing equipment then processes the wafers removed from the cassette in that orientation.

However, not all wafers stored in a cassette are necessarily oriented in the specified direction. For example, an operator may place wafers in a cassette in an incorrect direction. In this case, the processing equipment processes wafers that are oriented in the incorrect direction, and the specified processing results are not obtained.

Furthermore, a protective tape is attached to the front side of the wafer that is ground from the back side by the grinding device in advance. If the wafer with the protective tape attached is stored in the cassette in the wrong orientation, when the grinding device removes the wafer from the cassette and grinds it, the grinding device will process the protective tape attached to the wafer. In this case, not only will the wafer be damaged, but the grinding wheel of the grinding device will become unusable and will need to be replaced. The damage caused by this is enormous.

Conventionally, processing equipment that can identify the notch formed on the outer periphery of a wafer or the center of the wafer could not determine the front and back of the wafer. As a result, such problems could not be avoided.

The present invention was made in consideration of these problems, and its purpose is to provide a detection method for detecting the front and back sides of a wafer that has been brought into a processing device, and a processing device that can detect the front and back sides of a wafer.

According to one aspect of the present invention, there is provided a detection method for detecting the front and back sides of a wafer having a first orientation flat and a second orientation flat adjacent to each other and having different lengths on its outer periphery, the detection method comprising: an outer shape detection step for capturing an image of the outer periphery of the wafer with an imaging unit and detecting the outer shape of the wafer; and a determination step for determining the front and back sides of the wafer based on the outer shape of the wafer detected in the outer shape detection step, in which the determination step determines that one of the front and back sides of the wafer faces upward when the first orientation flat is located adjacent to the second orientation flat in the clockwise direction in a specific field of view, and determines that the other of the front and back sides of the wafer faces upward when the first orientation flat is located adjacent to the second orientation flat in the counterclockwise direction in the specific field of view.

According to another aspect of the present invention, a processing device for processing a wafer having a first orientation flat and a second orientation flat on the outer periphery that are adjacent to each other and have different lengths is provided, the processing device comprising: a holding table that can rotate while holding the wafer; a processing unit that processes the wafer; an imaging unit that can image the wafer held by the holding table; and a control unit, the control unit rotates the holding table that holds the wafer, causes the imaging unit to image the outer periphery of the wafer, identifies the outer shape of the wafer from the obtained image, and determines that one of the front and back surfaces of the wafer faces upward when the first orientation flat is located adjacent to the second orientation flat in the clockwise direction in a specific field of view, and determines that the other of the front and back surfaces of the wafer faces upward when the first orientation flat is located adjacent to the second orientation flat in the counterclockwise direction in the specific field of view.

According to yet another aspect of the present invention, a processing device for processing a wafer having a first orientation flat and a second orientation flat adjacent to each other and having different lengths on the outer periphery includes a cassette placement stage on which a cassette containing the wafer is placed, a holding table that can rotate around an axis perpendicular to the upper surface while holding the wafer and can move in a direction parallel to the upper surface, a transport robot that removes the wafer from the cassette placed on the cassette placement stage and transports the wafer onto the holding table, an imaging unit that can image the wafer held on the holding table, a chuck table that can hold the wafer by suction, a transport unit that can remove the wafer from the holding table and transport the wafer to the chuck table, a processing unit that processes the wafer held by suction on the chuck table, and a control unit, and the control unit is configured to determine the appropriate front and back sides of the wafer to be processed by the processing unit. A processing device is provided that includes a memory unit that stores the wafer, a contour specifying unit that rotates the holding table that holds the wafer and causes the imaging unit to capture an image of the outer periphery of the wafer and specifies the contour of the wafer from the captured image, a front/back specifying unit that specifies the front/back of the wafer from the positional relationship between the first orientation flat and the second orientation flat in the contour of the wafer specified by the contour specifying unit, and a judgment unit that reads the appropriate front/back stored in the memory unit and judges whether the front/back of the wafer specified by the front/back specifying unit matches the appropriate front/back. If the judgment unit judges that the front/back of the wafer matches the appropriate front/back, the transport unit is controlled to transport the wafer from the holding table to the chuck table, and a normal processing operation is performed to have the processing unit process the wafer. If the judgment unit judges that the front/back of the wafer does not match the appropriate front/back, the processing device does not perform the normal processing operation.

In one aspect of the present invention, a detection method and processing device detect the outer shape of a wafer that has a first orientation flat and a second orientation flat on its outer periphery that are adjacent to each other and have different lengths. Then, the front and back of the wafer are determined based on the detected outer shape of the wafer.

More specifically, when the second orientation flat is adjacent to the first orientation flat in a clockwise direction in a particular field of view, it is determined that the wafer has one of its front and back sides facing upward. On the other hand, when the second orientation flat is adjacent to the first orientation flat in a counterclockwise direction in this particular field of view, it is determined that the wafer has the other of its front and back sides facing upward.

In this way, the front and back sides of the wafer can be determined based on the relative positions of the first orientation flat and the second orientation flat. If the processing device can determine the front and back sides of the wafer before processing the wafer, it can be confirmed whether the wafer to be processed has the correct front and back sides. If it is confirmed that the wafer does not have the correct front and back sides, damage to the processing device and the wafer can be prevented by not processing the wafer.

Therefore, one aspect of the present invention provides a detection method for detecting the front and back sides of a wafer that has been brought into a processing device, and a processing device that can detect the front and back sides of a wafer.

FIG. 2 is a perspective view illustrating a wafer. FIG. 2 is a perspective view showing a schematic configuration of a processing device. FIG. 2 is a perspective view showing a schematic view of a holding table and an imaging unit. FIG. 4A is a side view that typically shows the holding table, the auxiliary table, and the imaging unit, and FIG. 4B is a side view that typically shows the operation of detecting the outer shape of the wafer. 2 is a flowchart showing a flow of each step of a processing method for processing a wafer.

An embodiment of the present invention will be described with reference to the drawings. A processing device in which the detection method according to this embodiment is implemented is, for example, a processing device that processes wafers made of compound semiconductors such as SiC and GaN. FIG. 1 is a perspective view that shows a typical wafer 1. Wafer 1 is, for example, a hexagonal single crystal SiC wafer.

The wafer 1 has a substantially circular planar shape. That is, the wafer 1 has a substantially circular front surface 1a and back surface 1b, and the outer periphery 1c is substantially arc-shaped. A rectangular first orientation flat 3a and a second orientation flat 3b indicating the crystal orientation are formed on the outer periphery 1c of the wafer 1.

For example, the length of the second orientation flat 3b is shorter than the length of the first orientation flat 3a. Also, the first orientation flat 3a and the second orientation flat 3b are perpendicular to each other.

In the case of a wafer 1 made of a material such as a compound semiconductor, the front surface 1a and the back surface 1b may have different processability, so when processing the wafer 1, it is advisable to adjust the front and back surfaces of the wafer 1 so that a predetermined surface of the front surface 1a or the back surface 1b of the wafer 1 is exposed upward. An operator looking at the wafer 1 can identify the front surface 1a and the back surface 1b of the wafer 1 from the relative positions of the two orientation flats 3a, 3b.

Next, a processing device for processing the wafer 1 will be described. The processing device for processing the wafer 1 is, for example, a grinding device that grinds the wafer 1 from the back surface 1b side, or a polishing device that polishes the wafer 1. The processing device may be a cutting device that cuts and divides the wafer 1, or a laser processing device that laser processes the wafer 1. Below, an example will be described in which the processing device is a grinding device, but the processing device is not limited to a grinding device. Figure 2 is a perspective view that shows a schematic view of the processing device (grinding device) 2.

The processing device (grinding device) 2 has a base 4 that supports each component. A disk-shaped turntable 6 is provided on the base 4 so that it can rotate in a horizontal plane. Three chuck tables 8 are provided on the upper surface of the turntable 6, spaced 120 degrees apart in the circumferential direction, and by rotating the turntable 6, each chuck table 8 can be positioned in the wafer loading/unloading area, the rough grinding area, and the finish grinding area.

In the wafer loading/unloading area, the wafer 1 before processing is placed on the chuck table 8, and after processing, the wafer 1 is removed from the chuck table 8. In the rough grinding area, a processing unit (grinding unit) 10a is used to perform rough grinding, which grinds the wafer 1 at a high processing feed rate. In the finish grinding area, a processing unit (grinding unit) 10b is used to perform finish grinding, which results in a higher flatness of the ground surface after grinding than after the rough grinding.

The chuck table 8 has an internal suction path (not shown) with one end connected to a suction source (not shown), and the other end of the suction path connected to a holding surface 8a on the upper surface of the chuck table 8. The holding surface 8a is made of a porous material, and when a negative pressure generated by the suction source is applied through the porous material to the wafer 1 placed on the holding surface 8a, the wafer 1 can be held by suction on the chuck table 8.

The processing device (grinding device) 2 includes processing units (grinding units) 10a, 10b that process the wafer 1 held by suction on the chuck table 8. Columns 22a, 22b are erected at the rear of the base 4, and processing units 10a, 10b are provided on the columns 22a, 22b, respectively. The processing units 10a, 10b include spindles 14a, 14b that extend vertically and are rotated by the spindle motors 12a, 12b at their upper ends.

Wheel mounts 16a, 16b are provided at the lower ends of the spindles 14a, 14b, respectively, and grinding wheels 18a, 18b are attached to the undersides of the wheel mounts 16a, 16b, respectively. The grinding wheels 18a, 18b are provided with grinding stones 20a, 20b arranged in an annular shape on their undersides, and grind the wafer 1 held by the chuck table 8. The processing units 10a, 10b are configured to be moved up and down by processing feed units 24a, 24b, respectively.

The front part of the base 4 is one step higher than the part where the turntable 6 is provided, and cassette placement tables (cassette placement areas) 26a, 26b are fixed to the front end of the base 4. Cassettes 28a, 28b containing multiple wafers 1 are placed on the cassette placement tables 26a, 26b. In the grinding device (processing device) 2, the wafers 1 contained in the cassettes 28a, 28b are transported out of the cassettes 28a, 28b one after another, processed by the processing feed units 24a, 24b, and returned to the cassettes 28a, 28b.

A transfer robot 30 is installed on the base 4 adjacent to the cassette placement tables 26a and 26b. The front portion of the base 4 is further provided with a holding table 32, an imaging unit 40, a transfer unit (loading arm) 34, an unloading unit (unloading arm) 36, and a spinner cleaning device 38 that cleans and spin-dries the ground wafer 1.

Unprocessed wafers 1 are carried out by a transport robot 30 from cassettes 28a, 28b placed on cassette mounting tables 26a, 26b. The transport robot 30 has multiple arms rotatably connected to each other at their ends, and has a holding part at the tip that holds the wafer 1. The cassette mounting tables 26a, 26b are capable of rising and lowering, and are raised and lowered so that the height of the target wafer 1 matches the height of the holding part of the transport robot 30. The transport robot 30 may also be capable of rising and lowering.

Then, the transfer robot 30 transfers the wafer 1 to the holding table 32. FIG. 3 includes a perspective view showing the holding table 32, and FIG. 4(A) and FIG. 4(B) include a side view showing the holding table 32. The holding table 32 has an upper surface 32a that serves as a suction surface, and can hold the wafer 1 placed on the upper surface 32a by suction.

The diameter of the upper surface 32a of the holding table 32 is smaller than the diameter of the wafer 1. Therefore, when the wafer 1 is suction-held on the holding table 32, the lower surface of the wafer 1 is exposed outside the upper surface 32a of the holding table 32.

The holding table 32 is connected to a rotary drive source 32d such as a motor, and can rotate around a rotary shaft 32b that passes vertically through the center of the top surface 32a. The holding table 32 is supported by a moving table 32e, and can move in a direction parallel to the top surface 32a. As shown in FIG. 4(A), the moving mechanism that moves the moving table 32e and the rotary drive source 32d are housed in the base 4. As shown in FIG. 3, the top surface of the base 4 is provided with an elongated hole 32c that allows the support shaft that supports the holding table 32 to move.

The processing device 2 is provided with an auxiliary table 42 near the holding table 32 on the base 4. The auxiliary table 42 is disposed at a position a predetermined distance away from the holding table 32 along the movement direction of the holding table 32. The upper surface 42a of the auxiliary table 42 serves as a suction surface. The upper surface 42a of the auxiliary table 42 is at the same height as the upper surface 32a of the holding table 32.

When the portion of the underside of the wafer 1 placed on the holding table 32 that is exposed to the outside of the holding table 32 faces the upper surface 42a of the auxiliary table 42, the auxiliary table 42 can hold the wafer 1 by suction.

When the wafer 1 is held by suction on the auxiliary table 42, the position of the wafer 1 relative to the holding table 32 can be adjusted by releasing the suction hold of the wafer 1 by the holding table 32 and moving the holding table 32. In addition, by rotating the holding table 32 around the rotation axis 32b, the direction of movement of the wafer 1 relative to the holding table 32 using the auxiliary table 42 can be changed. Therefore, the position of the wafer 1 relative to the holding table 32 can be freely adjusted.

An imaging unit 40 that captures an image of the outer periphery of the wafer 1 is disposed above the auxiliary table 42. The imaging unit 40 has a camera equipped with a CCD sensor or a CMOS sensor, and may further include an illumination light source.

The imaging unit 40 is supported by a support structure 41 that stands on the base 4 on the opposite side of the holding table 32, with the auxiliary table 42 in between. By repeatedly imaging the outer periphery of the wafer 1 with the imaging unit 40 while rotating the holding table 32 that holds the wafer 1 by suction, the entire outer periphery of the wafer 1 can be imaged.

The holding table 32, auxiliary table 42, and imaging unit 40 are used to align the wafer 1 removed from the cassettes 28a and 28b. That is, the holding table 32, auxiliary table 42, and imaging unit 40 constitute a position adjustment unit 44. The outer periphery of the wafer 1 is imaged by the imaging unit 40 to identify the position of the outer periphery, and the center 1d of the wafer 1 is detected based on the position of the outer periphery. The position of the wafer 1 can be adjusted by moving the wafer 1 so that the center 1d of the wafer 1 is positioned at a predetermined position.

The wafer loading mechanism (loading arm) 34 includes, for example, an axis portion that can rotate around an axis fixed to the base 4, an arm portion that extends horizontally from the upper end of the axis portion, and a holding portion that is provided at the tip of the arm portion and sucks and holds the wafer 1 from above. The wafer loading mechanism 34 holds the wafer 1, whose position has been adjusted by the position adjustment unit 44, from above with the holding portion and transports it to the chuck table 8 arranged in the wafer loading/unloading area.

In this way, the wafer loading mechanism (loading arm) 34 functions as a transport unit that can transport the wafer 1 from the holding table 32 of the position adjustment unit 44 and transport the wafer 1 to the chuck table 8.

Next, the control unit (controller) 50 provided in the processing device (grinding device) 2 will be described. The control unit (controller) 50 is connected to each component of the processing device 2 and has the function of controlling each component. The control unit (controller) 50 is composed of a computer including, for example, a processing device such as a CPU (Central Processing Unit), a main storage device such as a DRAM (Dynamic Random Access Memory), and an auxiliary storage device such as a flash memory. The functions of the control unit (controller) 50 are realized by operating the processing device etc. according to software stored in the auxiliary storage device.

The control unit (controller) 50 includes a memory section 52 in which processing conditions for processing the wafer 1 to be processed are input and registered in advance. The memory section 52 stores information, programs, software, etc. for controlling each component of the processing device 2. The control unit (controller) 50 then controls each component in accordance with the processing conditions.

The processing conditions are set appropriately according to the type of wafer 1 and the desired processing results. The optimal processing conditions vary depending on, for example, the diameter, thickness, material, and other types of wafer 1. The processing conditions include various setting conditions such as the finished thickness of wafer 1 after processing (grinding), the rotation speed of the grinding wheel, the rotation speed of the chuck table 8, and the processing feed speed.

The processing conditions also include reference information for determining whether the wafer 1 removed from the cassette 28a, 28b and transferred to the chuck table 8 is the target for processing. For example, the external shape of the wafer 1 to be processed by the processing units 10a, 10b, the size and diameter of the wafer 1, or the surface to be processed of the wafer 1 to be processed are stored in the memory unit 52. The memory unit 52 also stores the appropriate front and back sides of the wafer 1 to be processed by the processing units 10a, 10b as part of the processing conditions.

The control unit (controller) 50 uses the imaging unit 40 to identify the outer shape of the wafer 1, and identifies the front and back sides of the wafer 1 from the identified outer shape of the wafer 1. It then determines whether the front and back sides of the wafer 1 removed from the cassettes 28a and 28b are appropriate for processing the wafer 1. Below, we will continue to explain the processing device 2, focusing on the configuration that contributes to this determination.

The control unit (controller) 50 rotates the holding table 32 that holds the wafer 1, and has the imaging unit 40 capture an image of the outer periphery of the wafer 1, and includes an outer shape identification section 54 that identifies the outer shape of the wafer 1 from the captured image. The outer shape identification section 54 performs an operation to identify the outer shape of the wafer 1 when the wafer 1 is pulled out of the cassettes 28a, 28b by the transport robot 30 and transported to the holding table 32, and the wafer 1 is suction-held on the holding table 32.

More specifically, the imaging unit 40 captures an image of the outer periphery of the wafer 1 held by suction on the holding table 32, that part overlapping with the auxiliary table 42. The outer shape specification unit 54 then detects the outer periphery of the wafer 1 from the captured image and specifies the position of the outer periphery. At this time, the captured image may be subjected to a predetermined image processing or the like so that the outer periphery can be easily detected.

Next, the holding table 32 is rotated around the rotation axis 32b by a predetermined rotation angle, and another part of the outer periphery of the wafer 1 is positioned in the field of view of the imaging unit 40. The outer periphery of the wafer 1 is then similarly imaged by the imaging unit 40, and the position of the outer periphery of the wafer 1 is identified from the obtained image. In this way, the rotation of the holding table 32 and the imaging of the outer periphery of the wafer 1 are repeated to identify the position of the outer periphery of the wafer 1, and the external shape of the wafer 1 is identified.

The control unit (controller) 50 may determine the position of the center 1d of the wafer 1 by referring to the position of the outer periphery of the wafer 1 determined by the outer shape determination unit 54, and adjust the position of the wafer 1 so that the wafer 1 is transported to a predetermined position on the chuck table 8. That is, the control unit 50 can use the position of the outer periphery of the wafer 1 determined by the outer shape determination unit 54 to operate the position adjustment unit 44 to align the wafer 1.

The control unit (controller) 50 includes a front/back identifying section 56 that identifies the front/back of the wafer 1 held by suction on the holding table 32. The outer shape of the wafer 1 identified by the outer shape identifying section 54 includes the first orientation flat 3a and the second orientation flat 3b of the wafer 1 shown in FIG. 1. The front/back identifying section 56 then identifies the positional relationship between the first orientation flat 3a and the second orientation flat 3b in the outer shape of the wafer 1 identified by the outer shape identifying section 54, and identifies the front/back of the wafer 1 from this positional relationship.

When the first orientation flat 3a is located adjacent to the second orientation flat 3b in the clockwise direction in the field of view seen from above, the front/back identification unit 56 determines that one of the front surface 1a and back surface 1b of the wafer 1 faces upward. On the other hand, when the first orientation flat 3a is located adjacent to the second orientation flat 3b in the counterclockwise direction in the same field of view, the front/back identification unit 56 determines that the other of the front surface 1a and back surface 1b of the wafer 1 faces upward.

In this way, the front/back identification unit 56 can determine whether the front side 1a or the back side 1b of the wafer 1 faces upward from the positional relationship between the first orientation flat 3a and the second orientation flat 3b on the outer shape of the wafer 1. In other words, the front/back identification unit 56 can determine the front/back side of the wafer 1 held on the holding table 32.

The control unit (controller) 50 further includes a determination unit 58 that determines whether the front and back sides of the wafer 1 are oriented in a manner suitable for processing by the processing units 10a and 10b. The determination unit 58 reads out the appropriate front and back sides stored in the memory unit 52, and determines whether the front and back sides of the wafer 1 identified by the front and back side identification unit 56 match the appropriate front and back sides.

As a result, if the determination unit 58 determines that the front and back sides of the wafer 1 match the correct front and back sides, the control unit (controller) 50 causes the transport unit (loading arm) 34 to transport the wafer 1 from the holding table 32 to the chuck table 8. Then, the control unit (controller) 50 controls each component according to the processing conditions stored in the memory unit 52, and performs normal processing operations to have the processing units 10a and 10b process the wafer 1.

On the other hand, if the determination unit 58 determines that the front and back sides of the wafer 1 do not match the correct front and back sides, the control unit (controller) 50 does not perform the normal processing operation of the wafer 1. This is because if the wafer 1 is processed as is, the surface of the wafer 1 that should be processed will not be processed, and the expected processing results will not be obtained.

For example, if the front surface 1a of the wafer 1 is facing upward, when the wafer 1 is processed, the grinding wheel 20a of the processing unit 10a will come into contact with the protective tape that has been attached to the front surface 1a to protect it. In this case, not only will the wafer 1 not be processed correctly, but the wafer 1 may also be damaged. Furthermore, the grinding wheel 20a that has ground the protective tape cannot be used for subsequent grinding processes, so the damage is extremely severe. The processing device according to this embodiment can prevent such situations from occurring in advance.

If the determination unit 58 determines that the front and back sides of the wafer 1 do not match the correct front and back sides, the control unit 50 controls the transport robot 30 to transport the wafer 1 from the holding table 32 to the cassettes 28a and 28b. In other words, the processing device (grinding device) 2 performs a return operation without performing a normal processing operation.

The processing device (grinding device) 2 may also have a function of inverting the wafer 1. For example, the holding part of the transport robot 30 has a suction mechanism for suction-holding the wafer 1, and is rotatable around an axis of rotation along a direction from the base to the tip of the holding part. The transport robot 30 then suction-holds the wafer 1 placed on the holding table 32 with the holding part, lifts it off the holding table 32, rotates the holding part to invert the wafer 1 upside down, and returns it to the holding table 32.

However, the method of flipping the wafer 1 is not limited to this. For example, the transport unit (loading arm) 34 may be equipped with an inversion mechanism similar to that of the transport robot 30, and may be able to invert the wafer 1 upside down while transporting it from the holding table 32 to the chuck table 8. Furthermore, the processing device (grinding device) 2 may also use another method to flip the wafer 1 upside down. In any case, if the determination unit 58 determines that the front and back of the wafer 1 do not match the correct front and back, the control unit 50 does not perform the normal processing operation.

In addition, in the processing device (grinding device) 2 according to this embodiment, if the determination unit 58 determines that the front and back sides of the wafer 1 do not match the correct front and back sides, a warning may be issued to the user or manager of the processing device 2. For example, the processing device 2 is preferably equipped with a warning unit that issues various warnings to the user or manager.

For example, the processing device 2 may be provided with an alarm lamp 46 (see FIG. 2) capable of emitting light of multiple colors as an alarm unit. The control unit 50 controls the alarm lamp 46. If it is determined that the front and back of the wafer 1 are not correct, the control unit 50 controls the alarm lamp 46 to turn on a lamp that emits red light to indicate a warning. In addition, if the processing device 2 is provided with a buzzer capable of emitting an alarm sound as an alarm unit, the control unit 50 controls the buzzer to emit the alarm sound.

The above describes the processing device (grinding device) 2 according to this embodiment. Next, a detection method for detecting the front and back sides of the wafer 1 implemented by the processing device 2 or the like will be described. The detection method described below may be implemented by other devices or the like, or may be implemented by the processing device 2 described above. Therefore, the description of the detection method described below may be appropriately referenced as a description of the operation of the processing device 2 described above, and the description of the processing device 2 described above may be appropriately referenced as a description of the detection method described below.

The detection method according to this embodiment is a method for detecting the front and back of a wafer 1 (see FIG. 1) that has a first orientation flat 3a and a second orientation flat 3b on its outer periphery 1c, which are adjacent to each other and have different lengths. However, the detection method for detecting the front and back of the wafer 1 described below may be implemented as part of a processing method for processing the wafer 1 in the processing device 2.

Figure 5 is a flowchart showing the flow of a wafer processing method. The wafer processing method shown in the flowchart in Figure 5 includes each step performed in the detection method according to this embodiment. In this detection method, it is not necessary to perform all of the steps described below, and some of the steps may be performed. Below, the processing method for processing the wafer 1 will be explained step by step, and the detection method for detecting the front and back of the wafer 1 will be explained in detail step by step.

First, a carry-out step S10 is performed to carry out the wafer 1 from the cassettes 28a and 28b. For example, the wafer 1 is carried out by the transport robot 30 from the cassettes 28a and 28b. The transport robot 30 transports the wafer 1 to the holding table 32. At this time, the outer periphery 1c of the wafer 1 is positioned within the imaging field of the imaging unit 40.

Next, the outer periphery 1c of the wafer 1 is imaged by the imaging unit 40, and an outer shape detection step S20 is performed to detect the outer shape of the wafer 1. FIG. 4(B) is a side view that shows the wafer 1 and the imaging unit 40 during the outer shape detection step S20. In the outer shape detection step S20, for example, the outer periphery 1c of the wafer 1 is imaged by the imaging unit 40.

If it is not possible to capture the entire outer periphery 1c of the wafer 1 in one capture, the imaging unit 40 repeatedly captures images of the wafer 1 while switching the imaging position. For example, the imaging field of view of the imaging unit 40 may be switched by rotating the holding table 32 around the rotation axis 32b. Then, after capturing an image of the outer periphery 1c of the wafer 1 is completed, the positions of each point of the outer periphery 1c of the wafer 1 are identified from the one or more captured images obtained, and the outer shape of the wafer 1 is identified.

Next, a determination step S30 is performed to determine the front and back of the wafer 1 based on the outer shape of the wafer 1 detected in the outer shape detection step S20. In the determination step S30, the first orientation flat 3a and the second orientation flat 3b are identified from the outer shape of the wafer 1.

Of the outer periphery 1c of the wafer 1, which is formed in an arc shape, two shapes cut along a straight cutting line are detected as orientation flats. Then, by comparing the lengths of the two orientation flats, one can be identified as the first orientation flat 3a, and the other can be identified as the second orientation flat 3b.

Then, in the judgment step S30, when the first orientation flat 3a is located adjacent to the second orientation flat 3b in the clockwise direction in a specific field of view, it is judged that one of the front surface 1a and the back surface 1b of the wafer 1 faces upward. Also, when the first orientation flat 3a is located adjacent to the second orientation flat 3b in the counterclockwise direction in a specific field of view, it is judged that the other of the front surface 1a and the back surface 1b of the wafer 1 faces upward.

After the judgment step S30, a suitability judgment step S40 is performed to judge whether the front and back sides of the wafer 1 are suitable. For example, the correct front and back sides of the wafer 1 are stored in advance in the memory unit 52 of the control unit (controller) 50 of the processing device (grinding device) 2. Then, in the suitability judgment step S40, the correct front and back sides of the wafer 1 are read out from the memory unit 52 and compared with the judgment result of the judgment step S30.

If the front and back sides of the wafer 1 are judged to be appropriate as a result of the judgment in the suitability judgment step S40, the processing device 2 performs the processing step S50 to process the wafer 1. That is, the wafer 1 is transferred from the holding table 32 to the chuck table 8, and the wafer 1 is processed by the processing units 10a and 10b. More specifically, if it is confirmed that the back side 1b, which is the surface to be processed of the wafer 1, is exposed upward, the back side 1b of the wafer 1 is processed (grinded) as is.

On the other hand, if the result of the suitability determination step S40 is that the front and back sides of the wafer 1 are not suitable, the processing step S50 is not performed as is. In this case, it is advisable to perform the suitability step S60, in which the wafer 1 is turned upside down to suit the front and back sides of the wafer 1.

If the transfer robot 30 of the processing device 2 or the like is capable of flipping the wafer 1 upside down, the optimization step S60 may be performed by the transfer robot 30. Then, when the wafer 1 is flipped upside down by the optimization step S60 and the front and back sides of the wafer 1 are suitable for processing, the processing step S50 may be performed thereafter.

More specifically, when the wafer 1 is placed on the holding table 32, if the back surface 1b of the wafer 1, which is the surface to be processed, faces the upper surface 32a of the holding table 32, the wafer 1 is turned upside down so that the surface to be processed of the wafer 1 is exposed upward. The wafer 1 is then transported to the chuck table 8, and processing of the wafer 1 is carried out.

On the other hand, even if the result of the suitability determination step S40 indicates that the front and back sides of the wafer 1 are not suitable, the optimization step S60 does not have to be performed. If the processing device 2 does not have a mechanism for turning the wafer 1 upside down, or if it is suspected that the cassettes 28a and 28b contain wafers 1 that are not to be processed, the wafer 1 should not be processed. In this case, the optimization step S60 is not performed, and the wafer 1 is returned to the cassettes 28a and 28b.

As described above, the processing device and detection method (processing method) according to this embodiment detect the front and back sides of a wafer 1 having a first orientation flat 3a and a second orientation flat 3b on its outer periphery 1c. In particular, the front and back sides of the wafer 1 are determined from the positional relationship between the first orientation flat 3a and the second orientation flat 3b.

If the processing device 2 can determine the front and back sides of the wafer 1 before processing the wafer 1, it can confirm whether the wafer 1 to be processed has the correct front and back sides. If it is confirmed that the wafer 1 does not have the correct front and back sides, processing of the wafer 1 is not performed, thereby preventing damage to the processing device 2 and the wafer 1.

The present invention is not limited to the above embodiment, and can be modified in various ways. In the above embodiment, an image of the wafer 1 to be determined as to whether it is front or back is captured from above by the imaging unit 40, but the present invention is not limited to this.

That is, the imaging unit 40 may be positioned outside the auxiliary table 42 at a position lower than the top surface 42a, and may image the wafer 1 from below. Even in this case, it is possible to detect the outer shape of the wafer 1 based on the obtained captured image, and it is possible to determine the front and back of the wafer 1 from the positional relationship between the first orientation flat 3a and the second orientation flat 3b.

More specifically, when the first orientation flat 3a is located adjacent to the second orientation flat 3b in the clockwise direction in the field of view when the wafer 1 is viewed from below, it can be determined that one of the front surface 1a and back surface 1b of the wafer 1 faces upward. Also, when the first orientation flat 3a is located adjacent to the second orientation flat 3b in the counterclockwise direction in the field of view when the wafer 1 is viewed from below, it can be determined that the other of the front surface 1a and back surface 1b of the wafer 1 faces upward.

In addition, the structures, methods, etc. relating to the above embodiments can be modified as appropriate without departing from the scope of the purpose of the present invention.

REFERENCE SIGNS LIST 1 wafer 1a front surface 1b back surface 1c outer periphery 1d center 3a, 3b orientation flat 2 processing device 4 base 6 turntable 8 chuck table 8a holding surface 10a, 10b processing unit (grinding unit)
12a, 12b Spindle motor 14a, 14b Spindle 16a, 16b Wheel mount 18a, 18b Grinding wheel 20a, 20b Grinding stone 22a, 22b Column 24a, 24b Processing feed unit 26a, 26b Cassette placement table (cassette placement area)
28a, 28b Cassette 30 Transport robot 32 Holding table 32a Top surface 32b Rotation shaft 32c Slot 32d Rotation drive source 32e Moving table 34 Wafer loading mechanism (loading arm)
36 Wafer unloading mechanism (unloading arm)
38 Spinner cleaning device 40 Imaging unit 41 Support structure 42 Auxiliary table 42a Upper surface 44 Position adjustment unit 46 Alarm lamp 50 Control unit 52 Memory unit 54 External shape determination unit 56 Front/rear determination unit 58 Determination unit

Claims (3)

A method for detecting the front and back of a wafer having a first orientation flat and a second orientation flat adjacent to each other and having different lengths on an outer periphery thereof, comprising the steps of:
an outer shape detection step of capturing an image of the outer periphery of the wafer with an imaging unit and detecting the outer shape of the wafer;
a determination step of determining the front and back sides of the wafer based on the outer shape of the wafer detected in the outer shape detection step,
In the determination step,
determining that the wafer is facing one of its front side and back side upward when the first orientation flat is located adjacent to the second orientation flat in a clockwise direction in a particular field of view;
a detection method for determining that the wafer is facing with the other of the front surface and the back surface facing upward when the first orientation flat is located adjacent to the second orientation flat in a counterclockwise direction in the specific field of view. A processing apparatus for processing a wafer having a first orientation flat and a second orientation flat adjacent to each other and having different lengths on an outer periphery thereof, comprising:
a holding table capable of rotating while holding the wafer;
a processing unit for processing the wafer;
an imaging unit capable of imaging the wafer held by the holding table;
A control unit,
the control unit rotates the holding table that holds the wafer, and causes the imaging unit to capture an image of the outer periphery of the wafer, and identifies an outer shape of the wafer from the captured image;
determining that the wafer is facing one of its front side and back side upward when the first orientation flat is located adjacent to the second orientation flat in a clockwise direction in a particular field of view;
A processing apparatus characterized in that when the first orientation flat is located adjacent to the second orientation flat in a counterclockwise direction in the specific field of view, it is determined that the wafer is facing with the other of the front surface and the back surface facing upward. A processing apparatus for processing a wafer having a first orientation flat and a second orientation flat adjacent to each other and having different lengths on an outer periphery thereof, comprising:
a cassette placement stage on which a cassette containing the wafers is placed;
a holding table that can rotate around an axis perpendicular to an upper surface while holding the wafer and can move in a direction parallel to the upper surface;
a transfer robot that takes out the wafer from the cassette placed on the cassette placement table and transfers the wafer onto the holding table;
an imaging unit capable of imaging the wafer held by the holding table;
a chuck table capable of suction-holding the wafer;
a transport unit capable of unloading the wafer from the holding table and transporting the wafer to the chuck table;
a processing unit that processes the wafer held by suction on the chuck table;
A control unit,
The control unit
A memory unit that stores the appropriate front and back sides of the wafer to be processed by the processing unit;
an outer shape specifying section that rotates the holding table that holds the wafer, causes the imaging unit to capture an image of the outer periphery of the wafer, and specifies the outer shape of the wafer from the captured image;
a front/back specifying unit that specifies the front/back of the wafer based on a positional relationship between the first orientation flat and the second orientation flat in the outer shape of the wafer specified by the outer shape specifying unit;
a determination unit that reads out the appropriate front and back sides stored in the memory unit and determines whether or not the front and back sides of the wafer identified by the front and back side identification unit match the appropriate front and back sides,
When the determination unit determines that the front and back sides of the wafer match the appropriate front and back sides, the transfer unit is controlled to transfer the wafer from the holding table to the chuck table, and a normal processing operation is performed to cause the processing unit to process the wafer;
The processing apparatus is characterized in that, when the determining unit determines that the front and back sides of the wafer do not match the appropriate front and back sides, the normal processing operation is not performed.

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