JP2021194715A - Processing method - Google Patents

Abstract

To process a wafer without bringing up and conveying an annular region.SOLUTION: A processing method which processes a disk-like wafer having, on a rear surface side, a circular region and an annular region surrounding the circular region and thicker than the circular region, comprises: a wafer unit forming step of bonding the circular region and the annular region to an adhesive tape bonded to an annular frame; a first holding step of making a first holding table having a holding surface which is smaller in diameter than the circular region hold the circular region of the wafer through the adhesive tape; a separating step of separating the annular region by cutting the wafer along an outer periphery part of the circular region of the wafer held by the first holding table; a bringing-down step of making a second holding table having a holding surface which is larger in diameter than the wafer bring down the circular region, after the separating step; and a cutting step of making a second cutting blade cut a part or the whole of the annular region after the bringing-down step.SELECTED DRAWING: Figure 4

Description

The present invention is composed of a circular region located on the back surface side of the disk-shaped wafer, an annular region surrounding the circular region and having a thickness larger than the thickness of the wafer in the circular region, and a circular region and an annular region. The present invention relates to a processing method for processing a wafer having a disk-shaped recess.

A wafer in which a plurality of scheduled division lines are set on the surface and devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed on the surface side of each region partitioned by the plurality of scheduled division lines is, for example, a wafer. After the entire back surface side is thinned by the grinding device, it is cut by the cutting device along each scheduled division line and divided into individual device chips.

A wafer whose entire back surface is ground and thinned to a predetermined thickness has lower rigidity than before grinding and is liable to crack. Therefore, of the back surface side of the wafer, the region corresponding to the device region on the front surface side where a plurality of devices are formed is ground with a grinding wheel to form a disk-shaped recess on the back surface side, thereby forming an outer peripheral portion of the recess. There is a method of forming a thick annular region (so-called TAIKO grinding).

By forming the thick annular region, the rigidity of the wafer is improved as compared with the case where the entire back surface side is thinned, so that the wafer is less likely to crack during handling. When a wafer having an annular region is divided into individual device chips, a circular region located inside the annular region is cut, but at this time, the annular region hinders cutting of the circular region.

Therefore, a method has been proposed in which a dividing groove is formed at the boundary between the circular region and the annular region, and the annular region is lifted and removed from the wafer (see, for example, Patent Document 1). Specifically, a claw assembly having a plurality of claw portions is used to lift and transport an annular region separated from the wafer with a dividing groove as a boundary.

Japanese Unexamined Patent Publication No. 2011-61137

However, it takes time to lift and transport the annular region because the claw assembly needs to be operated very carefully. Further, during lifting and transporting, debris generated by damaging the annular region may fall to the surface side of the wafer and damage the device.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for processing a wafer in which a wafer can be divided into individual device chips without lifting and transporting an annular region.

According to one aspect of the present invention, a circular region located on the back surface side of the disk-shaped wafer, an annular region surrounding the circular region and having a thickness larger than the thickness of the wafer in the circular region, and the like. A processing method for processing the wafer having a circular region and a disk-shaped recess formed by the annular region, and an adhesive tape attached to the frame so as to close an opening in the center of the annular frame. By affixing the circular region and the annular region on the back surface side thereof, a wafer unit in which the frame, the adhesive tape, and the wafer are integrated is formed so that the adhesive tape imitates the recess. The first holding table having a wafer unit forming step and a holding surface having a smaller diameter than the circular region sucks and holds the region corresponding to the circular region of the adhesive tape, thereby holding the first through the adhesive tape. The first holding step of holding the wafer on the holding table and the circular shape of the wafer held on the first holding table by cutting the first cutting blade on the front side of the wafer located on the opposite side of the back surface. The adhesive tape is placed on a separation step that cuts the wafer along the outer periphery of the region and separates the annular region, and after the separation step on a second holding table that has a holding surface with a larger diameter than the wafer. A machining method comprising a pulling step of pulling down the circular region by suction and a cutting step of cutting a part or all of the annular region with a second cutting blade after the pulling step is provided.

Preferably, in the wafer unit forming step, a circular sticking area to which the adhesive tape is stuck and a non-sticking area surrounding the sticking area are formed in the circular region due to the step of the recess. The separation step consists of a first separation step of cutting the outer peripheral portion of the pasted area along the circumferential direction of the wafer and a second separation step of cutting the non-attached region along the circumferential direction of the wafer. And, including.

Further, preferably, in the wafer unit forming step, due to the step of the recess, the circular region has a circular sticking region to which the adhesive tape is stuck and a non-stick region surrounding the sticking region. The first cutting blade has a blade thickness corresponding to the length from the first position on the outer peripheral portion of the pasted area to the second position of the non-attached area in the radial direction of the wafer. Then, in the separation step, the annular region of the wafer corresponding to the first position to the second position is cut by the first cutting blade.

Further, preferably, the cutting step cuts the surface side of the wafer including the annular region with the second cutting blade so as to be equal to or less than the thickness of the circular region.

In the processing method according to one aspect of the present invention, first, a region corresponding to the circular region of the adhesive tape is sucked and held by a first holding table having a holding surface having a diameter smaller than that of the circular region (first holding step). Next, the first cutting blade is cut on the surface side of the wafer, the wafer is cut along the outer peripheral portion of the circular region of the wafer held by the first holding table, and the annular region is separated (separation step).

After the separation step, the circular region is pulled down by sucking the adhesive tape on a second holding table having a holding surface larger in diameter than the wafer (pulling step). The second cutting blade then cuts part or all of the annular region (cutting step). Since the annular region is cut in this way, the wafer can be divided into individual device chips without lifting and transporting the annular region.

FIG. 1A is a perspective view of a wafer or the like, and FIG. 1B is a cross-sectional view of the wafer or the like. It is a figure which shows the outline of a cutting apparatus. FIG. 3A is a diagram showing a first holding step, and FIG. 3B is a diagram showing a separation step. FIG. 4A is a diagram showing a pulling down step, and FIG. 4B is a diagram showing a cutting step. It is a flow chart of the processing method of a wafer. It is a figure which shows the state just before the sticking area is pulled down. FIG. 7A is a diagram showing a first separation step, and FIG. 7B is a diagram showing a second separation step. FIG. 8A is a diagram showing a pulling down step, and FIG. 8B is a diagram showing a cutting step. It is a flow chart of the processing method of a wafer. 10 (A) is a diagram showing a separation step, FIG. 10 (B) is a diagram showing a pulling down step, and FIG. 10 (C) is a diagram showing a cutting step.

An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. First, a disk-shaped wafer 11 or the like to be processed will be described. 1 (A) is a perspective view of the wafer 11 and the like, and FIG. 1 (B) is a cross-sectional view of the wafer 11 and the like.

The wafer 11 is made of a semiconductor material such as silicon and has a diameter of 300 mm. On the surface 11a of the wafer 11, a plurality of scheduled division lines (streets) 13 are set so as to intersect each other.

Devices 15 such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed in each region on the surface 11a side partitioned by a plurality of scheduled division lines 13. On the surface 11a side, around the device region 17a on which the plurality of devices 15 are formed, the device 15 is not provided and a substantially flat outer peripheral surplus region 17b is provided.

There are no restrictions on the material, shape, structure, size, etc. of the wafer 11. For example, the wafer 11 may be made of a material other than silicon, such as a semiconductor, ceramics, resin, or metal. Similarly, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device 15.

As shown in FIG. 1B, a circular region 19a having a diameter smaller than the diameter of the wafer 11 exists on the back surface 11b side located on the side opposite to the front surface 11a. The circular region 19a is a region on the back surface 11b side that substantially corresponds to the device region 17a on the front surface 11a side.

An annular region 19b thicker than the thickness of the wafer 11 in the circular region 19a is formed so as to surround the circumference of the circular region 19a. The annular region 19b is a region on the back surface 11b side that substantially corresponds to the outer peripheral surplus region 17b on the front surface 11a side.

The annular region 19b protrudes from the circular region 19a in the thickness direction of the wafer 11. A disk-shaped recess 19c is formed on the back surface 11b side by the inner peripheral side surface of the annular region 19b and the circular region 19a.

An adhesive tape (dicing tape) 21 having a diameter larger than that of the wafer 11 is attached to the circular region 19a and the annular region 19b. The adhesive tape 21 has, for example, a laminated structure of a resin base material layer and an adhesive layer (glue layer) provided on one surface of the base material layer.

As shown in FIG. 1A, the glue layer side of the adhesive tape 21 is attached to the frame 23 so as to close the opening 23a located at the center of the annular frame 23 made of metal. Further, one surface of the frame 23 is attached to the outer peripheral portion of the adhesive tape 21 on the glue layer side.

As shown in FIG. 1 (B), the central portion of the adhesive tape 21 is attached to the inner peripheral side surface of the annular region 19b and the circular region 19a so as to follow the recess 19c, whereby the wafer unit is attached. 25 is formed.

In addition, in this specification, the fact that the adhesive tape 21 imitates the recess 19c does not mean that it completely imitates the shape of the recess 19c. For example, there is a region to which the adhesive tape 21 is not attached at the corner portion composed of the circular region 19a and the inner peripheral side surface of the annular region 19b.

In the circular region 19a of the present embodiment, a circular sticking region 19a ₁ to which the adhesive tape 21 is stuck and an annular non-sticking region 19a ₂ surrounding the sticking region 19a ₁ are formed. The non-sticking region 19a ₂ is an annular region having a predetermined width from the outermost circumference of the sticking region 19a _{1 to the outermost circumference of the circular region 19a.}

The non-attached region 19a ₂ has a predetermined width (for example, 0.7 mm) when the diameter of the wafer 11 is 300 mm. As described above, in the present embodiment _{, the annular gap 27 is formed by the non-sticking region 19a 2} , the inner peripheral side surface of the annular region 19b, and the adhesive tape 21 due to the step of the recess 19c.

When the adhesive tape 21 is attached to the wafer 11 so as to follow the recess 19c, for example, a bonding device (not shown) is used. The laminating device comprises a vacuum chamber (not shown) having a concave upper body with an opening at the bottom and a concave lower body with an opening at the top.

Each opening of the upper body and the lower body is substantially circular, has an outer diameter smaller than the opening 23a, and has a larger outer diameter than the wafer 11. The upper body can be moved in the vertical direction relative to the lower body, and when the upper body and the lower body are overlapped so that the opening of the upper body and the opening of the lower body face each other, the upper body and the lower body are overlapped. A predetermined space is formed by the main body.

A first suction source (not shown) such as a vacuum pump is connected to the internal space of the upper body via a first suction path (not shown). Further, one end of the air supply passage (not shown) is connected to the internal space of the upper body. The other end of the air supply path is open to the atmosphere, and a solenoid valve (not shown) is provided between one end and the other end.

A second suction source (not shown) such as a vacuum pump is connected to the internal space of the lower body via a second suction path (not shown). Further, a chuck table (not shown) is arranged in the internal space of the lower body.

When the adhesive tape 21 is attached to the back surface 11b side, first, the front surface 11a side is sucked and held by a chuck table so that the back surface 11b side faces upward. Next, a frame unit (not shown) having the adhesive tape 21 attached to the frame 23 is placed on the opening of the lower body. At this time, the adhesive layer side of the adhesive tape 21 is made to face the back surface 11b.

Then, the upper main body is moved downward, and the adhesive tape 21 is sandwiched between the opening of the upper main body and the opening of the lower main body in the thickness direction of the adhesive tape 21. Next, after closing the solenoid valve, the first and second suction sources are operated to form a first space defined by the adhesive tape 21 and the lower main body, and a first space defined by the adhesive tape 21 and the upper main body. Each of the two spaces is set to a low pressure state (for example, 50 Pa).

After that, the solenoid valve is opened, the second space is opened to the atmosphere, and the adhesive tape 21 is attached to the back surface 11b side of the wafer 11 by utilizing the pressure difference between the first space and the second space. In this way, the frame 23, the adhesive tape 21, and the wafer 11 are integrated, and the wafer unit 25 whose back surface 11b side is supported by the frame 23 via the adhesive tape 21 is formed.

Next, a cutting device 2 for cutting the wafer 11 will be described with reference to FIG. FIG. 2 is a top view of the cutting device 2 showing an outline of the cutting device 2. The X-axis direction (machining feed direction), Y-axis direction (indexing feed direction), and Z-axis direction (cutting feed direction, vertical direction) shown in FIG. 2 are orthogonal to each other.

The cutting device 2 includes a base 4 that supports each component. An opening 4a is provided at the front corner of the base 4. An elevating mechanism 6 is provided in the opening 4a. An elevating table is arranged on the upper part of the elevating mechanism 6, and a cassette 8 containing a plurality of wafer units 25 is placed on the elevating table.

Behind the opening 4a, a rectangular opening 4b having a longitudinal portion along the X-axis direction is formed. A flat plate-shaped table cover (not shown) is arranged in the opening 4b. Bellows-shaped dust-proof and drip-proof covers (not shown) are arranged on both sides of the table cover in the X-axis direction so as to cover the openings 4b.

A chuck table (first holding table) 10 is provided on the table cover. A rotation drive source (not shown) such as a motor is connected to the lower portion of the chuck table 10, and the chuck table 10 can rotate around a rotation axis substantially parallel to the Z-axis direction.

A ball screw type first X-axis moving mechanism (machining feed unit) (not shown) is arranged below the rotary drive source, and when the first X-axis moving mechanism is operated, the chuck table 10 is moved. It moves in the X-axis direction together with the table cover and the like.

The chuck table 10 has a disk-shaped frame made of a metal such as stainless steel. A disk-shaped porous plate made of a porous member is fixed to the upper part of the frame. A suction source (not shown) such as an ejector is connected to the porous plate via a predetermined flow path. When the suction source is operated, a negative pressure is generated on the upper surface of the porous plate.

The upper surface of the frame and the upper surface of the porous plate function as a holding surface 10a for sucking and holding the wafer 11 and the like. The holding surface 10a has a diameter smaller than that of the circular region 19a of the wafer 11. Around the chuck table 10, four clamps 10b for fixing the frame 23 from all sides are provided.

A pair of guide rails (not shown) substantially parallel to the Y-axis direction are arranged behind the cassette 8 and above the opening 4b. The pair of guide rails adjust the position of the wafer unit 25 taken out from the cassette 8 in the X-axis direction, for example.

Behind the opening 4b, a rectangular opening 4c having a longitudinal portion along the X-axis direction is formed. Similar to the opening 4b, a table cover and a dust-proof / drip-proof cover (both not shown) are arranged in the opening 4c. Further, a ball screw type second X-axis moving mechanism (machining feed unit) (not shown) is arranged below the table cover.

A chuck table (second holding table) 12 is provided on the table cover. Similar to the chuck table 10, a rotation drive source (not shown) such as a motor is connected to the lower portion of the chuck table 12, and can rotate around a rotation axis substantially parallel to the Z-axis direction.

A ball screw type second X-axis moving mechanism (machining feed unit) (not shown) is arranged below the rotary drive source, and when the second X-axis moving mechanism is operated, the chuck table 12 is moved. It moves in the X-axis direction together with the table cover and the like.

The chuck table 12 also has a disk-shaped frame and a porous plate, respectively. A suction source (not shown) such as a vacuum pump is connected to the porous plate via a predetermined flow path, and the upper surface of the frame and the upper surface of the porous plate are holding surfaces for sucking and holding the wafer 11 and the like. Functions as 12a.

The holding surface 12a has a diameter larger than that of the holding surface 10a, and more specifically, a diameter larger than the diameter of the wafer 11 to be handled. Also around the chuck table 12, four clamps 12b for fixing the frame 23 from all sides are provided.

Above the opening 4b on the side opposite to the pair of guide rails in the X-axis direction, a portal-shaped first support (not shown) is provided so as to straddle the opening 4b and the opening 4c in the Y-axis direction. .. The first support is provided with a lower arm unit 14 and an upper arm unit 16 for conveying the wafer units 25, respectively.

The lower arm unit 14 is provided with a gripping mechanism 14a used when pulling out the wafer unit 25 from the cassette 8 to the pair of guide rails. The gripping mechanism 14a has a function of sandwiching a part of the frame 23 in the thickness direction of the frame 23.

A gate-shaped second support (not shown) is provided on the side opposite to the pair of guide rails with respect to the first support. The second support is provided with a pair of processing unit moving mechanisms (indexing feed unit, cutting feed unit).

Each machining unit moving mechanism has a Y-axis moving plate (not shown) that can slide in the Y-axis direction. A Z-axis moving plate (not shown) is attached to the Y-axis moving plate so as to be slidable in the Z-axis direction.

A cutting unit for cutting the wafer 11 is provided at the lower part of the Z-axis moving plate. In this example, a pair of cutting units (first cutting unit 18, second cutting unit 20) are arranged so as to face each other along the Y-axis direction.

The first cutting unit 18 has a cylindrical spindle housing 18a whose longitudinal portion is arranged along the Y-axis direction. The spindle housing 18a rotatably supports a cylindrical spindle 18b having a rotation axis parallel to the Y-axis direction.

One end of the spindle 18b protrudes from the spindle housing 18a, and a cutting blade 18c having an annular cutting edge is attached to the one end. The cutting blade 18c has a cutting blade having a relatively thin blade thickness.

The cutting edge thickness of the cutting blade 18c is, for example, a predetermined value in the range of 0.03 mm or more and 0.3 mm or less. A rotary drive source (not shown) such as a motor is connected to the other end of the spindle 18b.

The second cutting unit 20 also has a spindle housing 20a and a spindle 20b, like the first cutting unit 18. A cutting blade 20c is attached to one end of the spindle 20b.

The cutting edge thickness of the cutting blade 20c is, for example, a predetermined value in the range of 1.0 mm or more and 5.0 mm or less. A rotary drive source (not shown) such as a motor is connected to the other end of the spindle 20b.

An imaging unit (not shown) used for positioning the wafer 11 is arranged in the vicinity of each of the first cutting unit 18 and the second cutting unit 20. The image pickup unit is a camera having a lighting device, an optical lens, an image pickup element, and the like.

A circular opening 4d is provided behind the opening 4c. A cleaning unit 22 for cleaning the wafer 11 and the like after cutting is arranged in the opening 4d. The cleaning unit 22 includes a spinner table that sucks and holds the wafer unit 25, and a nozzle that injects a gas-liquid mixed fluid in which air and pure water are mixed toward the holding surface of the spinner table.

The cutting device 2 further includes a control unit (not shown) that controls the operation of each component. The control unit includes an elevating mechanism 6, first and second X-axis moving mechanisms, a pair of machining unit moving mechanisms, a lower arm unit 14, an upper arm unit 16, a first cutting unit 18, a second cutting unit 20, and an imaging unit. It controls the operation of the cleaning unit 22 and the like.

The control unit is, for example, a processor (processing device) represented by a CPU (Central Processing Unit) and a main storage device such as a DRAM (Dynamic Random Access Memory), a SRAM (Static Random Access Memory), and a ROM (Read Only Memory). It is composed of a computer including a flash memory, a hard disk drive, an auxiliary storage device such as a solid state drive, and the like.

Software including a predetermined program is stored in the auxiliary storage device. By operating the processing device or the like according to this software, the function of the control unit is realized. Next, a method for processing the wafer 11 according to the first embodiment will be described with reference to FIGS. 1 (A) to 4 (B) and FIG. Note that FIG. 5 is a flow chart of a processing method for the wafer 11.

First, as shown in FIGS. 1 (A) and 1 (B), a plurality of wafer units 25 in which the frame 23, the adhesive tape 21 and the wafer 11 are integrated are formed by using the above-mentioned bonding device (wafer). Unit formation step S10).

In the wafer unit forming step S10, the adhesive tape 21 is attached so as to follow the recess 19c, and the affixed region 19a ₁ and the non-attached region 19a ₂ are formed in the circular region 19a as described above. The plurality of wafer units 25 are conveyed to the cutting device 2 in a state of being housed in the cassette 8.

Then, using the lower arm unit 14 and a pair of guide rails (not shown), one wafer unit 25 is conveyed to the chuck table 10 arranged in the attachment / detachment region located behind the cassette 8. The chuck table 10 located in the attachment / detachment region is shown by a two-dot chain line in FIG.

Next, as shown in FIG. 3A, the chuck table 10 sucks and holds the region of the adhesive tape 21 corresponding to the circular region 19a. In the present embodiment, _{the size of the sticking area 19a 1} located inside the gap 27 corresponds to the size of the holding surface 10a.

In this way, the wafer 11 is held by the holding surface 10a via the adhesive tape 21 (first holding step S20). FIG. 3A is a diagram showing the first holding step S20. After the first holding step S20, the chuck table 10 is arranged in the cutting region located below the first cutting unit 18.

The chuck table 10 located in the cutting region is shown by a solid line in FIG. In the present embodiment, the annular region 19b is separated by cutting the wafer 11 with a cutting blade 18c (first cutting blade) having a relatively thin blade thickness (separation step S30).

FIG. 3B is a diagram showing a separation step S30. In the separation step S30, the chuck table 10 is rotated with the cutting blade 18c cut into the surface 11a side located slightly inside the outermost circumference of the _{attachment region 19a 1.}

As a result, the wafer 11 is cut along the outer peripheral portion of _{the attachment region 19a 1} of the wafer 11 held by the chuck table 10 to separate the annular region 19b from the wafer 11. After the separation step S30, the chuck table 10 is moved to the attachment / detachment region.

Next, using the upper arm unit 16, the wafer unit 25 is conveyed from the chuck table 10 arranged in the attachment / detachment region to the chuck table 12 arranged in the attachment / detachment region located in front of the cleaning unit 22 in the opening 4c. .. In FIG. 2, the chuck table 12 located in the detachable region is shown by a two-dot chain line.

Next, the wafer unit 25 is sucked by the chuck table 12. As described above, the holding surface 12a has a diameter larger than that of the wafer 11, and when the adhesive tape 21 is sucked by the holding surface 12a, the sticking region 19a ₁ of the circular region 19a can be pulled down (pulling step S40). ..

FIG. 4A is a diagram showing a pulling down step S40. When the sticking area 19a ₁ is held by the holding surface 12a, wrinkles may be formed in the portion of the adhesive tape 21 where the gap 27 is formed. However, in FIG. 4A, wrinkles are formed. Is omitted.

After the pulling down step S40, a part or all of the annular region 19b is cut and removed by the cutting blade 20c (cutting step S50). FIG. 4B is a diagram showing a cutting step S50.

In the cutting step S50, the chuck table 12 is rotated with the cutting blade 20c (second cutting blade) having a relatively thick blade cut on the surface 11a side of the annular region 19b.

As a result, the surface 11a side of the wafer 11 including the annular region 19b is cut by the cutting blade 20c so as to be equal to or less than the thickness of the wafer 11 in _{the pasting region 19a 1.} In the cutting step S50 of the present embodiment, the lower end of the cutting blade 20c is positioned at the height of the back surface 11b, and the entire outer peripheral portion of the wafer 11 including the annular region 19b separated in the separation step S30 is ground and deleted.

However, instead of this, by setting the lower end of the cutting blade 20c at a position higher than the back surface 11b of the annular region 19b, the outer peripheral portion of the wafer 11 including the annular region 19b is not completely removed, and a slight thickness is obtained. You may leave that much. As a result, it is possible to prevent the cutting blade 20c from coming into contact with the adhesive tape 21, and thus it is possible to prevent the condition of the cutting blade 20c from deteriorating.

After the cutting step S50, the machining unit moving mechanism is operated to move the first cutting unit 18 onto the chuck table 12. Then, the wafer 11 is cut along each scheduled division line 13 by the cutting blade 18c, and the wafer 11 is divided into a plurality of device chips (not shown) (division step S60).

When the wafer 11 is divided in the division step S60, the annular region 19b has already been cut, so that the cutting of the device region 17a is not hindered. Therefore, the wafer 11 can be divided into individual device chips without lifting and transporting the annular region 19b.

After the division, the wafer unit 25 is conveyed from the chuck table 10 to the cleaning unit 22 by the upper arm unit 16. After cleaning each device chip with the cleaning unit 22, the wafer unit 25 is transferred from the cleaning unit 22 to the cassette 8 by using the lower arm unit 14 or the like.

In the first holding step S20 of the present embodiment, the convex chuck table normally used when processing the so-called TAIKO ground wafer 11 becomes unnecessary. When a convex chuck table is used, a thin ring-shaped spacer is arranged around the convex portion in order to adjust the height of the convex portion according to the depth of the concave portion 19c of the wafer 11. Then, there is an advantage that the height adjustment itself using a spacer is unnecessary.

By the way, in the pulling down step S40 described above, stress is applied _{to the sticking region 19a 1} located outside the cutting groove 11c formed in the separation step S30, and the wafer 11 is formed at the boundary between _{the sticking region 19a 1} and the non-sticking region 19a _2. May crack (see region 24 in FIG. 6).

FIG. 6 is a diagram showing a state immediately before the _{pasting area 19a 1 is pulled down.} Fragments generated by cracking of the wafer 11 may scatter and damage the device 15 and the like, so it is preferable to prevent cracking of the wafer 11.

Therefore, in the separation step S30 of the second embodiment, first, the cutting blade 18c (first cutting blade) is used to form _{an outer peripheral portion of the attachment region 19a 1} (for example, an annular region located on the frame of the chuck table 10). , Cutting along the circumferential direction of the wafer 11 (first separation step S32). FIG. 7A is a diagram showing a first separation step S32 according to the second embodiment.

After the first separation step S32, the non-attached region 19a ₂ is cut along the circumferential direction of the wafer 11 with the cutting blade 18c (first cutting blade) (second separation step S34). FIG. 7B is a diagram showing a second separation step S34 according to the second embodiment. After the second separation step S34, the pulling down step S40 is performed.

FIG. 8A is a diagram showing a lowering step S40 according to the second embodiment. _{In the second embodiment, since the sticking area 19a 1} located outside the cutting groove 11c formed in the first separation step S32 is separated from the non-sticking area 19a ₂ , the sticking area 19a ₁ and the non-sticking area 19a 1 are separated. It is possible to prevent the wafer 11 from cracking at the boundary with _{19a 2.}

FIG. 8B is a diagram showing a cutting step S50 according to the second embodiment. In the cutting step S50, as in the first embodiment, pasting area 19a as the less the thickness of the _first wafer 11, the cutting blade 20c (second cutting blade surface 11a of the wafer 11 including the annular region 19b ) To cut. FIG. 9 is a flow chart of a processing method for the wafer 11 according to the second embodiment.

Next, a third embodiment will be described with reference to FIGS. 10 (A) to 10 (C). In the third embodiment, the wafer 11 is processed in the same procedure as in the first embodiment. However, in the separation step S30, a cutting blade 20c (first cutting blade) having a relatively thick cutting edge is used. This point is different from the first embodiment.

As shown in FIG. 10A, the blade thickness of the cutting blade 20c used in the separation step S30 of the third embodiment is the first position located on the outer peripheral portion _{of the attachment region 19a 1 in the radial direction of the wafer 11.} Corresponds to the length from 26 to the second position 28 in the non-paste area 19a _2. FIG. 10A is a diagram showing a separation step S30 according to the third embodiment.

In the separation step S30 according to the third embodiment, the outer peripheral portion (that is, the first position 26 to the second position) of the circular region 19a of the wafer 11 held by the holding surface 10a of the chuck table 10 by using the cutting blade 20c. The annular region up to 28) is cut.

After that, the pulling down step S40, the cutting step S50, and the dividing step S60 are sequentially performed. FIG. 10B is a diagram showing the pulling down step S40 according to the third embodiment, and FIG. 10C is a diagram showing the cutting step S50 according to the third embodiment.

In the cutting step S50 of the third embodiment, the cutting blade 20c (the second cutting blade, that is, in the third embodiment, the first cutting blade and the second cutting blade are the same) is used again. .. Then, the division step S60 is performed using the cutting blade 18c having a relatively thin blade thickness.

In the third embodiment, since the sticking area 19a ₁ is separated from the non-sticking area 19a ₂ in the separation step S30, in the pulling down step S40, the wafer 11 at the boundary between _{the sticking area 19a 1} and the non-sticking area 19a ₂ Can prevent cracking.

In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

2: Cutting device 4: Base, 4a, 4b, 4c, 4d: Opening 6: Elevating mechanism, 8: Cassette 10: Chuck table, 10a: Holding surface, 10b: Clamp 11: Wafer, 11a: Front surface, 11b: Back surface , 11c: Cutting groove 12: Chuck table, 12a: Holding surface, 12b: Clamp 13: Scheduled division line 14: Lower arm unit, 14a: Gripping mechanism 15: Device 16: Upper arm unit 17a: Device area, 17b: Outer peripheral surplus area 18: 1st cutting unit 18a: spindle housing, 18b: spindle, 18c: cutting blade 19a: circular area, 19a ₁ : pasting area, 19a ₂ : non-sticking area 19b: annular area, 19c: recess 20: second cutting unit 20a: Spindle housing, 20b: Spindle, 20c: Cutting blade 21: Adhesive tape 22: Cleaning unit 23: Frame, 23a: Opening 24: Area 25: Wafer unit 26: 1st position, 27: Gap, 28: 2nd position

Claims (4)

It is composed of a circular region located on the back surface side of the disk-shaped wafer, an annular region surrounding the circular region and having a thickness larger than the thickness of the wafer in the circular region, and the circular region and the annular region. A processing method for processing the wafer having a disk-shaped recess.
By attaching the circular region and the annular region on the back surface side to the adhesive tape attached to the frame so as to close the opening at the center of the annular frame, the adhesive tape imitates the concave portion. In addition, a wafer unit forming step of forming a wafer unit in which the frame, the adhesive tape, and the wafer are integrated,
By sucking and holding the region corresponding to the circular region of the adhesive tape on the first holding table having a holding surface having a smaller diameter than the circular region, the wafer is held on the first holding table via the adhesive tape. The first holding step to hold and
The first cutting blade is cut in the front surface side of the wafer located on the opposite side of the back surface, and the wafer is cut along the outer peripheral portion of the circular region of the wafer held by the first holding table. A separation step that separates the annular region,
After the separation step, a pull-down step of pulling down the circular region by sucking the adhesive tape on a second holding table having a holding surface having a diameter larger than that of the wafer.
A machining method comprising: after the pulling step, a cutting step of cutting a part or all of the annular region with a second cutting blade. In the wafer unit forming step, a circular sticking area to which the adhesive tape is stuck and a non-sticking area surrounding the sticking area are formed in the circular region due to the step of the recess. ,
The separation step
A first separation step of cutting the outer peripheral portion of the pasting region along the circumferential direction of the wafer, and
A second separation step of cutting the non-attached area along the circumferential direction of the wafer,
The processing method according to claim 1, wherein the processing method comprises. In the wafer unit forming step, a circular sticking area to which the adhesive tape is stuck and a non-sticking area surrounding the sticking area are formed in the circular region due to the step of the recess. ,
The first cutting blade has a blade thickness corresponding to the length from the first position on the outer peripheral portion of the pasted area to the second position of the non-attached area in the radial direction of the wafer.
The processing method according to claim 1, wherein in the separation step, an annular region of the wafer corresponding to the first position to the second position is cut by the first cutting blade. The cutting step is
The processing method according to any one of claims 1 to 3, wherein the surface side of the wafer including the annular region is cut by the second cutting blade so as to be equal to or less than the thickness of the circular region. ..

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