JP7458695B2 - Wafer processing method - Google Patents

Description

The present invention relates to a wafer processing method for dividing a wafer, in which a plurality of devices are formed in each region of a surface divided by dividing lines, into individual devices.

In the manufacturing process of device chips used in electronic devices such as mobile phones and personal computers, first, a plurality of intersecting dividing lines (street) are set on the surface of a wafer made of a material such as a semiconductor. Then, devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integrations) are formed in each area partitioned by the planned dividing line.

After that, an adhesive tape called dicing tape, which is attached to an annular frame having an opening so as to close the opening, is attached to the back side of the wafer, and the wafer, adhesive tape, and annular frame are integrated. form a frame unit. Then, the wafer included in the frame unit is processed and divided along the dividing line to form individual device chips.

For example, a cutting device is used to divide the wafer. The cutting device includes a chuck table that holds the wafer via an adhesive tape, a cutting unit that cuts the wafer, and the like. The cutting unit includes a cutting blade including an annular grindstone portion, and a spindle that is passed through a central through hole of the cutting blade and rotates the cutting blade.

When cutting a wafer, place the frame unit on the chuck table, hold the wafer on the chuck table via adhesive tape, rotate the spindle to rotate the cutting blade, and raise the cutting unit to a predetermined height. lower into position. Then, the chuck table and the cutting unit are moved relative to each other in a direction parallel to the upper surface of the chuck table, and the cutting blade is caused to cut the wafer along the planned dividing line. The wafer is then divided.

After that, the frame unit is taken out from the cutting device, the adhesive tape is subjected to treatment such as irradiation with ultraviolet rays to reduce the adhesive strength of the adhesive tape, and the device chip is picked up. As a processing apparatus with high production efficiency for device chips, a cutting apparatus is known that can divide a wafer and irradiate an adhesive tape with ultraviolet rays in succession with one apparatus (see Patent Document 1). The device chip picked up from the adhesive tape is mounted on a predetermined wiring board or the like.

Japanese Patent No. 3076179

The adhesive tape includes a base layer and an adhesive layer disposed on the base layer. In the cutting apparatus, in order to reliably divide the wafer, the cutting unit is positioned at a predetermined height such that the lower end of the cutting blade reaches a position lower than the lower surface of the wafer. Therefore, the cutting blade that cuts the wafer also cuts the adhesive layer of the adhesive tape. Therefore, when cutting a wafer, cutting debris originating from the glue layer is generated together with cutting debris originating from the wafer.

When cutting a wafer, a cutting fluid is supplied to the wafer and a cutting blade, and the cutting debris generated by cutting is taken into the cutting fluid and diffused onto the surface of the wafer. Here, the cutting debris originating from the adhesive layer tends to re-adhere to the surface of the device, and is also difficult to remove in a subsequent wafer cleaning step or the like. Therefore, if cutting debris originating from the glue layer adheres, the quality of the device chip will deteriorate.

The present invention has been made in view of such problems, and its purpose is to provide a wafer processing method in which cutting debris is less likely to adhere to the surface of a device and deterioration in the quality of device chips is suppressed. That's true.

According to one aspect of the present invention, there is provided a wafer processing method for dividing a wafer having a plurality of devices formed in each area of the surface partitioned by a planned division line into individual device chips, the method comprising: a polyolefin-based sheet disposing step of positioning the wafer within an opening of a frame having an opening for accommodating the wafer, and disposing a polyolefin-based sheet having no adhesive layer on the back surface of the wafer and the outer periphery of the frame; an integration step of applying hot air to the polyolefin-based sheet to heat the polyolefin-based sheet and integrating the wafer and the frame via the polyolefin-based sheet by thermocompression bonding; a dividing step of cutting the wafer along the planned division line using a cutting device equipped with a rotatable cutting blade to divide the wafer into individual device chips; and a picking up step of picking up individual device chips from the polyolefin-based sheet, wherein the polyolefin-based sheet cannot be integrated with the wafer and the frame unless it is heated .

Preferably, in the integration step, after the integration is performed, the polyolefin sheet protruding from the outer periphery of the frame is removed.

Preferably, in the pickup step, the polyolefin sheet is expanded to widen the distance between the device chips, and the device chips are pushed up from the polyolefin sheet side.

Moreover, preferably, the polyolefin sheet is a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet.

Further preferably, in the integration step, the heating temperature is 120°C to 140°C when the polyolefin sheet is the polyethylene sheet, and the heating temperature is 160°C when the polyolefin sheet is the polypropylene sheet. °C to 180 °C, and when the polyolefin sheet is the polystyrene sheet, the heating temperature is 220 °C to 240 °C.

Further, preferably, the wafer is made of Si, GaN, GaAs, or glass.

In the wafer processing method according to one embodiment of the present invention, when forming the frame unit, a polyolefin sheet without an adhesive layer is used to form the frame and the wafer without using an adhesive tape having an adhesive layer. Unify. The step of integrating the frame and the wafer through the polyolefin sheet is achieved by applying hot air to the polyolefin sheet.

After performing the integration process, the wafer is cut into individual device chips by cutting with a cutting blade, and the device chips are picked up from the polyolefin sheet. The picked up device chips are each mounted on a predetermined mounting target.

When cutting a wafer, the cutting blade also cuts into the polyolefin sheet beneath the wafer, which generates cutting debris originating from the polyolefin sheet. However, since the polyolefin sheet does not include an adhesive layer, the cutting waste is relatively difficult to adhere to the wafer even if the cutting waste is taken into the cutting water and spread over the surface of the wafer. Furthermore, even if cutting debris adheres to the wafer, it is easily removed by a subsequent cleaning process or the like.

That is, according to one aspect of the present invention, it is possible to form a frame unit using a polyolefin sheet without an adhesive layer by thermocompression bonding, and cutting debris with high adhesive strength is not generated when cutting a wafer, and the cutting debris can be easily removed. This suppresses deterioration in device chip quality due to

Therefore, according to one aspect of the present invention, a wafer processing method is provided in which cutting debris is less likely to adhere to the surface of a device and deterioration in the quality of device chips is suppressed.

FIG. 2 is a perspective view schematically showing a wafer. 10 is a perspective view showing a schematic view of how a wafer and a frame are positioned on a holding surface of a chuck table; FIG. FIG. 2 is a perspective view schematically showing a polyolefin sheet disposing step. FIG. 3 is a perspective view schematically showing an example of an integration process. FIG. 5(A) is a perspective view schematically showing how the polyolefin sheet is cut, and FIG. 5(B) is a perspective view schematically showing the formed frame unit. FIG. 3 is a perspective view schematically showing a dividing step. FIG. 3 is a perspective view schematically showing how the frame unit is carried into the pickup device. FIG. 8(A) is a cross-sectional view schematically showing a frame unit fixed on a frame support, and FIG. 8(B) is a cross-sectional view schematically showing a pickup process.

Embodiments according to one aspect of the present invention will be described with reference to the accompanying drawings. First, a wafer processed by the processing method according to this embodiment will be described. FIG. 1 is a perspective view schematically showing a wafer 1. As shown in FIG. The wafer 1 is made of, for example, a material such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductors, or a material such as sapphire, glass, or quartz. It is a substantially disk-shaped substrate, etc.

The surface 1a of the wafer 1 is divided by a plurality of dividing lines 3 arranged in a grid pattern. Furthermore, devices 5 such as ICs (Integrated Circuits) and LEDs (Light Emitting Diodes) are formed in each area divided by the planned dividing lines 3 on the front surface 1a of the wafer 1. In the method for processing a wafer 1 according to the present embodiment, the wafer 1 is cut and divided along the planned dividing line 3 to form individual device chips.

The wafer 1 is cut by a cutting device. Before carrying the wafer 1 into the cutting apparatus, the wafer 1, the polyolefin sheet, and the frame are integrated to form a frame unit. The wafer 1 is carried into a cutting device in the form of a frame unit, and is cut. The individual device chips formed are supported by a polyolefin sheet. Thereafter, the space between the device chips is widened by expanding the polyolefin sheet, and the device chips are picked up by a pickup device.

The annular frame 7 (see FIG. 2, etc.) is made of, for example, a material such as metal, and includes an opening 7a having a diameter larger than the diameter of the wafer 1. When forming the frame unit, the wafer 1 is positioned within the opening 7a of the frame 7 and accommodated in the opening 7a.

The polyolefin sheet 9 (see FIG. 3, etc.) is a flexible resin sheet, and has flat front and back surfaces. It has a diameter larger than the outer diameter of the frame 7 and is not provided with an adhesive layer. The polyolefin sheet 9 is a polymer sheet synthesized using an alkene as a monomer, and is, for example, a sheet transparent or translucent to visible light, such as a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet. However, the polyolefin sheet 9 is not limited to this, and may be opaque.

The polyolefin sheet 9 does not have adhesive properties and therefore cannot be attached to the wafer 1 and frame 7 at room temperature. However, since the polyolefin sheet 9 has thermoplastic properties, when it is heated to a temperature close to its melting point while being joined to the wafer 1 and frame 7 under application of a certain pressure, it partially melts and can be bonded to the wafer 1 and frame 7. Therefore, in the processing method for the wafer 1 according to this embodiment, the wafer 1, frame 7, and polyolefin sheet 9 are integrated by heating in the manner described above to form a frame unit.

Next, each step of the method for processing the wafer 1 according to this embodiment will be explained. First, in preparation for integrating the wafer 1, the polyolefin sheet 9, and the frame 7, a polyolefin sheet disposing step is performed. FIG. 2 is a perspective view schematically showing how the wafer 1 and frame 7 are positioned on the holding surface 2a of the chuck table 2. As shown in FIG. 2, the polyolefin sheet disposing process is carried out on a chuck table 2 having a holding surface 2a on the top.

The chuck table 2 is provided with a porous member in the upper center, the diameter of which is larger than the outer diameter of the frame 7. The upper surface of the porous member becomes the holding surface 2a of the chuck table 2. As shown in FIG. 3, the chuck table 2 has an exhaust passage inside, one end of which is connected to the porous member, and a suction source 2b is disposed on the other end of the exhaust passage. A switching unit 2c is disposed in the exhaust passage, which switches between a connected state and a cut state. When the switching unit 2c is in the connected state, the negative pressure generated by the suction source 2b acts on the held object placed on the holding surface 2a, and the held object is sucked and held by the chuck table 2.

In the polyolefin sheet disposing process, first, as shown in FIG. 2, the wafer 1 and the frame 7 are placed on the holding surface 2a of the chuck table 2. At this time, the wafer 1 is positioned within the opening 7a of the frame 7 with the front surface 1a of the wafer 1 facing downward. Next, a polyolefin sheet 9 is provided on the back surface 1b of the wafer 1 and on the outer periphery of the frame 7. FIG. 3 is a perspective view schematically showing a polyolefin sheet disposing process. As shown in FIG. 3, a polyolefin sheet 9 is placed on the wafer 1 and the frame 7 so as to cover them.

Note that in the polyolefin sheet disposing step, a polyolefin sheet 9 having a diameter larger than the holding surface 2a of the chuck table 2 is used. When applying negative pressure from the chuck table 2 to the polyolefin sheet 9 in the later integration process, if the entire holding surface 2a is not covered by the polyolefin sheet 9, the negative pressure will leak from the gap. This is because pressure cannot be applied appropriately to the polyolefin sheet 9.

In the method for processing the wafer 1 according to the present embodiment, next, hot air is applied to the polyolefin sheet 9 to heat the polyolefin sheet 9, and the wafer 1 and the frame 7 are integrated via the polyolefin sheet 9. Implement the integration process. FIG. 4 is a perspective view schematically showing an example of the integration process. In FIG. 4, broken lines indicate what is visible through the polyolefin sheet 9, which is transparent or translucent to visible light.

In the integration process, first, the switching part 2c of the chuck table 2 is activated to establish communication, and the suction source 2b is connected to the porous member on the upper part of the chuck table 2, and the negative pressure from the suction source 2b is applied to the polyolefin sheet 9. Let it work. Then, the polyolefin sheet 9 is brought into close contact with the wafer 1 and the frame 7 due to atmospheric pressure.

Next, the polyolefin sheet 9 is heated while being sucked by the suction source 2b. The polyolefin sheet 9 is heated, for example, by a heat gun 4 disposed above the chuck table 2, as shown in FIG.

The heat gun 4 includes a heating means such as a heating wire and a blowing mechanism such as a fan, and can heat and spray air. While applying negative pressure to the polyolefin sheet 9, the heat gun 4 supplies hot air 4a to the polyolefin sheet 9 from above to heat the polyolefin sheet 9 to a predetermined temperature. Bonded with heat and pressure.

After thermocompression-bonding the polyolefin sheet 9, the switching part 2c is operated to separate the porous member of the chuck table 2 from the suction source 2b, and the suction by the chuck table 2 is released.

Next, the polyolefin sheet 9 protruding from the outer periphery of the frame 7 is cut and removed. FIG. 5(A) is a perspective view schematically showing how the polyolefin sheet 9 is cut. For cutting, an annular cutter 6 is used, as shown in FIG. 5(A). The cutter 6 has a through hole and is rotatable around a rotating shaft passed through the through hole.

First, the annular cutter 6 is positioned above the frame 7. At this time, the rotation axis of the cutter 6 is aligned with the radial direction of the chuck table 2. Next, the cutter 6 is lowered and the polyolefin sheet 9 is sandwiched between the frame 7 and the cutter 6, and the polyolefin sheet 9 is cut. Then, cutting marks 9a are formed on the polyolefin sheet 9.

Further, the cutter 6 is moved around the opening 7a of the frame 7 along the frame 7, and a predetermined area of the polyolefin sheet 9 is surrounded by the cut mark 9a. Then, the polyolefin sheet 9 in the area on the outer peripheral side of the cutting marks 9a is removed so as to leave this area of the polyolefin sheet 9. Then, unnecessary portions of the polyolefin sheet 9 including the area protruding from the outer periphery of the frame 7 can be removed.

An ultrasonic cutter may be used to cut the polyolefin sheet, and a vibration source that vibrates the annular cutter 6 at an ultrasonic frequency may be connected to the cutter 6. When cutting the polyolefin sheet 9, the polyolefin sheet 9 may be cooled and hardened to facilitate cutting. In this manner, a frame unit 11 is formed in which the wafer 1 and the frame 7 are integrated via the polyolefin sheet 9. Figure 5(B) is a perspective view that shows a schematic view of the formed frame unit 11.

When carrying out the integration process, the polyolefin sheet 9 is preferably heated to a temperature below its melting point. If the heating temperature exceeds the melting point, the polyolefin sheet 9 may melt and be unable to maintain the shape of the sheet. Furthermore, the polyolefin sheet 9 is preferably heated to a temperature above its softening point. If the heating temperature does not reach the softening point, the integration process cannot be carried out properly. In other words, the polyolefin sheet 9 is preferably heated to a temperature above its softening point and below its melting point.

Furthermore, some polyolefin sheets 9 may not have a clear softening point. Therefore, when carrying out the integration step, the polyolefin sheet 9 is preferably heated to a temperature that is 20° C. lower than its melting point or higher and lower than its melting point.

Further, for example, when the polyolefin sheet 9 is a polyethylene sheet, the heating temperature is 120°C to 140°C. Further, when the polyolefin sheet 9 is a polypropylene sheet, the heating temperature is 160°C to 180°C. Further, when the polyolefin sheet 9 is a polystyrene sheet, the heating temperature is 220°C to 240°C.

Here, the heating temperature refers to the temperature of the polyolefin sheet 9 when performing the integration step. For example, a heat source such as a heat gun 4 has a model in which the output temperature can be set. In some cases, the output temperature may not be reached. Therefore, in order to heat the polyolefin sheet 9 to a predetermined temperature, the output temperature of the heat source may be set higher than the melting point of the polyolefin sheet 9.

Next, in the method for processing the wafer 1 according to this embodiment, a dividing step is carried out in which the wafer 1 in the frame unit 11 state is cut and divided by a cutting blade. The dividing step is carried out, for example, by a cutting device shown in FIG. 6. FIG. 6 is a perspective view that shows the dividing step.

The cutting device 8 includes a cutting unit 10 that cuts a workpiece, and a chuck table (not shown) that holds the workpiece. The cutting unit 10 includes a cutting blade 14 having an annular grindstone portion, and a spindle (not shown) whose tip end is penetrated through a central through hole of the cutting blade 14 and rotates the cutting blade 14. The cutting blade 14 includes, for example, an annular base having the through hole in the center, and an annular grindstone portion disposed on the outer periphery of the annular base.

The proximal end of the spindle is connected to a spindle motor (not shown) housed inside the spindle housing 12, and when the spindle motor is operated, the cutting blade 14 can be rotated.

When a workpiece is cut by the cutting blade 14, heat is generated due to friction between the cutting blade 14 and the workpiece. Furthermore, when the workpiece is cut, cutting waste is generated from the workpiece. Therefore, in order to remove heat and cutting debris generated by cutting, cutting water such as pure water is supplied to the cutting blade 14 and the workpiece while cutting the workpiece. The cutting unit 10 includes, for example, a cutting water supply nozzle 16 on the side of the cutting blade 14 for supplying cutting water to the cutting blade 14 and the like.

When cutting the wafer 1, the frame unit 11 is placed on the chuck table, and the wafer 1 is held on the chuck table via the polyolefin sheet 9. The chuck table is then rotated to align the planned dividing line 3 of the wafer 1 with the processing feed direction of the cutting device 8. The relative positions of the chuck table and the cutting unit 10 are also adjusted so that the cutting blade 14 is positioned above the extension of the planned dividing line 3.

Next, the cutting blade 14 is rotated by rotating the spindle. Then, the cutting unit 10 is lowered to a predetermined height position, and the chuck table and the cutting unit 10 are moved relative to each other along a direction parallel to the upper surface of the chuck table. Then, the grindstone portion of the rotating cutting blade 14 comes into contact with the wafer 1 and cuts the wafer 1, and cutting marks 3a along the planned dividing line 3 are formed on the wafer 1 and the polyolefin sheet 9.

After performing cutting along one dividing line 3, the chuck table and cutting unit 10 are moved in the index feed direction perpendicular to the processing feed direction, and the wafer 1 is similarly cut along the other dividing line 3. Carry out cutting. After performing cutting along all the planned dividing lines 3 along one direction, the chuck table is rotated around an axis perpendicular to the holding surface, and the cutting is performed along all the planned dividing lines 3 along the other direction. The wafer 1 is cut using the following steps. When the wafer 1 is cut along all the planned dividing lines 3 of the wafer 1, the dividing step is completed.

The cutting device 8 may include a cleaning unit (not shown) near the cutting unit 10. The wafer 1 cut by the cutting unit 10 may be transported to the cleaning unit and cleaned by the cleaning unit. For example, the cleaning unit includes a cleaning table that holds the frame unit 11 and a cleaning water supply nozzle that can move back and forth above the frame unit 11.

The cleaning table is rotated around an axis perpendicular to the holding surface, and while supplying cleaning liquid such as pure water from the cleaning water supply nozzle to the wafer 1, the cleaning water supply nozzle is reciprocated in a path passing above the center of the holding surface. By moving the wafer 1, the front surface 1a side of the wafer 1 can be cleaned.

When performing the dividing step, the wafer 1 is divided into individual device chips. The formed device chip is supported by a polyolefin sheet 9. When cutting the wafer 1, in order to reliably divide the wafer 1, the cutting unit 10 is set at a predetermined height so that the lower end of the cutting blade 14 is at a lower height than the back surface 1b of the wafer 1. It is positioned in the right direction. Therefore, when the wafer 1 is cut, the polyolefin sheet 9 is also cut, and cutting waste originating from the polyolefin sheet 9 is generated.

When adhesive tape is used for the frame unit 11 instead of the polyolefin sheet 9, cutting chips originating from the adhesive layer of the adhesive tape are generated. In this case, the cutting chips are taken up by the cutting water sprayed from the cutting water supply nozzle 16 and spread over the surface 1a of the wafer 1. The cutting chips originating from the adhesive layer tend to reattach to the surface of the device 5, and are not easy to remove during the cleaning process of the wafer 1 performed after cutting. When cutting chips originating from the adhesive layer adhere, the quality of the device chips that are formed decreases, which is a problem.

In contrast, in the method for processing the wafer 1 according to the present embodiment, the frame unit 11 uses a polyolefin sheet 9 without a glue layer, instead of an adhesive tape with a glue layer. Even if cutting debris originating from the polyolefin sheet 9 is generated, taken into the cutting water, and spread over the surface of the wafer, the cutting debris is relatively difficult to adhere to the wafer 1. Further, even if cutting debris adheres to the wafer 1, it is easily removed by a subsequent cleaning process or the like. Therefore, deterioration in the quality of the device chip due to the cutting waste is suppressed.

In the method for processing the wafer 1 according to the present embodiment, next, a pick-up step of picking up the individual device chips from the polyolefin sheet 9 is performed. In the pick-up process, a pick-up device 18 shown in the lower part of FIG. 7 is used. FIG. 7 is a perspective view schematically showing how the frame unit 11 is carried into the pickup device 18.

The pickup device 18 includes a cylindrical drum 20 having a diameter larger than the diameter of the wafer 1 and a frame holding unit 22 including a frame support 26 . The frame support stand 26 of the frame holding unit 22 is provided with an opening having a diameter larger than the diameter of the drum 20, is arranged at the same height as the upper end of the drum 20, and is arranged so that the upper end of the drum 20 is placed on the outer peripheral side. Surround from.

A clamp 24 is disposed on the outer peripheral side of the frame support stand 26. When the frame unit 11 is placed on the frame support stand 26 and the frame 7 of the frame unit 11 is gripped by the clamp 24, the frame unit 11 is fixed to the frame support stand 26.

The frame support stand 26 is supported by a plurality of rods 28 extending in the vertical direction, and an air cylinder 30 for raising and lowering the rods 28 is disposed at the lower end of each rod 28. The plurality of air cylinders 30 are supported by a disc-shaped base 32. Activation of each air cylinder 30 pulls the frame support 26 down relative to the drum 20.

A push-up mechanism 34 for pushing up the device chip supported by the polyolefin sheet 9 from below is provided inside the drum 20. Further, above the drum 20, a collet 36 (see FIG. 8(B)) that can suck and hold a device chip is provided. The push-up mechanism 34 and collet 36 are movable in the horizontal direction along the upper surface of the frame support 26. Further, the collet 36 is connected to a suction source 36a (see FIG. 8(B)) via a switching portion 36b (see FIG. 8(B)).

In the pickup process, first, the height of the frame support 26 is adjusted by operating the air cylinder 30 so that the height of the upper end of the drum 20 of the pickup device 18 and the height of the upper surface of the frame support 26 match. do. Next, the frame unit 11 carried out from the cutting device 8 is placed on the drum 20 and frame support stand 26 of the pickup device 18.

Then, the frame 7 of the frame unit 11 is fixed onto the frame support stand 26 by the clamp 24. FIG. 8(A) is a cross-sectional view showing the frame unit 11 fixed onto the frame support stand 26. The wafer 1 is divided by the dividing step, leaving cutting marks 3a.

Next, the air cylinder 30 is operated to lower the frame support stand 26 of the frame holding unit 22 with respect to the drum 20. Then, as shown in FIG. 8(B), the polyolefin sheet 9 is expanded in the outer circumferential direction. FIG. 8(B) is a cross-sectional view schematically showing the pickup process.

When the polyolefin sheet 9 is expanded in the outer circumferential direction, the intervals between the device chips 1c supported by the polyolefin sheet 9 are widened. This makes it difficult for the device chips 1c to come into contact with each other, making it easier to pick up the individual Debye chips 1c. Then, the device chip 1c to be picked up is determined, the push-up mechanism 34 is moved below the device chip 1c, and the collet 36 is moved above the device chip 1c.

Thereafter, the push-up mechanism 34 is operated to push up the device chip 1c from the polyolefin sheet 9 side. Then, the switching section 36b is operated to communicate the collet 36 with the suction source 36a. Then, the device chip 1c is sucked and held by the collet 36, and the device chip 1c is picked up from the polyolefin sheet 9. The picked up individual device chips 1c are then mounted on a predetermined wiring board or the like and used.

As described above, according to the wafer processing method according to the present embodiment, the frame unit 11 including the wafer 1 can be formed without using an adhesive tape. Therefore, even when the wafer 1 is cut, no cutting debris originating from the glue layer of the adhesive tape is generated, and the cutting debris does not adhere to the device chip 1c. Therefore, the quality of the device chip 1c is not degraded.

Note that the present invention is not limited to the description of the above embodiments, and can be implemented with various modifications. For example, in the embodiment described above, the polyolefin sheet 9 is, for example, a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet, but one embodiment of the present invention is not limited thereto. For example, the polyolefin sheet may be made of other materials, such as a copolymer of propylene and ethylene, or an olefin elastomer.

In addition, the structure, method, etc. according to the above embodiments can be modified and implemented as appropriate without departing from the scope of the objective of the present invention.

1 Wafer 1a Front surface 1b Back surface 3 Planned dividing line 3a Cutting marks 5 Device 7 Frame 7a Opening 9 Polyolefin sheet 9a Cutting marks 11 Frame unit 2 Chuck table 2a Holding surface 2b, 36a Suction source 2c, 36b Switching part 4 Heat gun 4a Hot air 6 Cutter 8 Cutting device 10 Cutting unit 12 Spindle housing 14 Cutting blade 16 Cutting water supply nozzle 18 Pick-up device 20 Drum 22 Frame holding unit 24 Clamp 26 Frame support 28 Rod 30 Air cylinder 32 Base 34 Push-up mechanism 36 Collet

Claims (6)

A wafer processing method for dividing a wafer having a plurality of devices formed in each area of a surface defined by division lines into individual device chips, comprising the steps of:
a polyolefin-based sheet disposing step of positioning a wafer in an opening of a frame having an opening for accommodating the wafer, and disposing a polyolefin-based sheet not including a glue layer on the back surface of the wafer and on the outer periphery of the frame;
an integration step of applying hot air to the polyolefin-based sheet to heat the polyolefin-based sheet and integrating the wafer and the frame via the polyolefin-based sheet by thermocompression bonding;
a dividing step of dividing the wafer into individual device chips by cutting the wafer along division lines using a cutting device equipped with a rotatable cutting blade;
a pick-up step of picking up individual device chips from the polyolefin sheet;
Equipped with
The method for processing a wafer is characterized in that the polyolefin sheet cannot be integrated with the wafer and the frame unless it is heated . 2. The method of processing a wafer according to claim 1, wherein in the integration step, after the integration is performed, the polyolefin sheet protruding from the outer periphery of the frame is removed. The wafer processing method according to claim 1, characterized in that in the pick-up step, the polyolefin sheet is expanded to widen the gap between each device chip, and the device chip is pushed up from the polyolefin sheet side. 2. The wafer processing method according to claim 1, wherein the polyolefin sheet is one of a polyethylene sheet, a polypropylene sheet, and a polystyrene sheet. In the integration step, when the polyolefin sheet is the polyethylene sheet, the heating temperature is 120°C to 140°C, and when the polyolefin sheet is the polypropylene sheet, the heating temperature is 160°C to 180°C. 5. The method for processing a wafer according to claim 4, wherein the heating temperature is 220° C. to 240° C. when the polyolefin sheet is the polystyrene sheet. 2. The method of processing a wafer according to claim 1, wherein the wafer is made of one of Si, GaN, GaAs, and glass.