JP7039135B2 - Wafer processing method - Google Patents

Description

The present invention relates to a method for processing a wafer in which a wafer formed in each region of a surface in which a plurality of devices are partitioned by a planned division line is divided 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 planned division lines (streets) 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 Integrated Circuits) are formed in each area partitioned by the planned division line.

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

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

When cutting a wafer, the frame unit is placed on the chuck table, the wafer is held on the chuck table via adhesive tape, and the cutting blade is rotated by rotating the spindle to raise the cutting unit to a predetermined height. Lower to position. Then, the chuck table and the cutting unit are relatively moved along the direction parallel to the upper surface of the chuck table, and the cutting blade is made to cut the wafer along the planned division line. Then, the wafer is divided.

After that, the frame unit is taken out from the cutting device, and the adhesive tape is subjected to a treatment such as irradiating the adhesive tape with ultraviolet rays to reduce the adhesive strength of the adhesive tape and pick up the device chip. As a processing device having high production efficiency of device chips, a cutting device capable of continuously performing wafer division and irradiation of an adhesive tape with ultraviolet rays by one device is known (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 material layer and a glue layer disposed on the base material layer. In the cutting device, the cutting unit is positioned at a predetermined height so that the lower end of the cutting blade reaches a position lower than the lower surface of the wafer in order to reliably divide the wafer. Therefore, the cutting blade that cuts the wafer also cuts the glue layer of the adhesive tape. Therefore, when cutting the wafer, cutting chips derived from the glue layer as well as cutting chips derived from the wafer are generated.

When cutting a wafer, cutting fluid is supplied to the wafer and cutting blades, and the cutting chips generated by cutting are taken into the cutting fluid and diffused on the surface of the wafer. Here, the cutting chips derived from the glue layer are likely to reattach to the surface of the device, and are not easy to remove in the subsequent wafer cleaning step or the like. Therefore, if cutting chips derived from the glue layer adhere to the device chip, the quality of the device chip deteriorates.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a wafer processing method in which cutting chips are less likely to adhere to the surface of a device and deterioration of the quality of the device chip is suppressed. That is.

According to one aspect of the present invention, a plurality of devices are a method for processing a wafer in which a wafer formed in each region of a surface partitioned by a planned division line is divided into individual device chips, and the back surface of the wafer is formed. A polyolefin-based sheet arranging step of arranging a polyolefin-based sheet, and an integration step of applying hot air to the polyolefin-based sheet to heat the polyolefin-based sheet and integrating the wafer and the polyolefin-based sheet. Before or after the integration step, a first frame having an opening large enough to accommodate the wafer and having a plurality of magnets and a second frame having an opening large enough to accommodate the wafer. Using a frame composed of, the polyolefin-based sheet is sandwiched between the first frame and the second frame by the magnetic force generated by the magnet. A frame support process in which the wafer is supported by the frame, a division process in which the wafer is cut along a planned division line using a cutting device equipped with a rotatable cutting blade, and the wafer is divided into individual device chips. Provided is a wafer processing method comprising a pickup step of individually pushing up a device chip by blowing air from the polyolefin-based sheet side and picking up the device chip from the polyolefin-based sheet.

Also, preferably, in the pickup step, the polyolefin-based sheet is expanded to widen the space between each device chip.

Further, preferably, the polyolefin-based sheet is any one of a polyethylene sheet, a polypropylene sheet, and a polystyrene sheet.

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

Further, preferably, the wafer is composed of any of Si, GaN, GaAs, and glass.

In the wafer processing method according to one aspect of the present invention, the frame and the wafer are integrated by using a polyolefin-based sheet without a glue layer without using an adhesive tape having a glue layer in the frame unit. The integration step of integrating the polyolefin-based sheet and the wafer is realized by applying hot air to the polyolefin-based sheet.

The wafer processing method according to one aspect of the present invention includes a first frame having an opening large enough to accommodate the wafer and a second frame having an opening large enough to accommodate the wafer. Frame is used. The first frame comprises a plurality of magnets, and the first frame and the second frame are attracted to each other by the magnetic force generated by the magnets.

Then, in the frame support step, a polyolefin-based sheet is arranged between the first frame and the second frame, and the polyolefin-based sheet is sandwiched between the first frame and the second frame. The polyolefin sheet can be supported by the frame.

That is, even if the polyolefin-based sheet does not have a glue layer, the wafer, the polyolefin-based sheet, and the frame can be integrated to form a frame unit by carrying out the integration step and the frame support step. ..

After that, the wafer is cut by a cutting blade to divide the wafer into individual device chips, and the device chips are individually pushed up by blowing air from the polyolefin-based sheet side, and the device chips are picked up from the polyolefin-based sheet. Each of the picked up device chips is mounted on a predetermined mounting target. If the device chip is pushed up by air at the time of pickup, the load applied to the device chip when peeling from the polyolefin sheet can be reduced.

When cutting a wafer, the cutting blade also cuts into the polyolefin-based sheet under the wafer, so cutting chips derived from the polyolefin-based sheet are generated. However, since the polyolefin-based sheet does not have a glue layer, even if the cutting chips are taken into the cutting water and diffused on the surface of the wafer, the cutting chips are relatively difficult to adhere to the wafer. Further, even if cutting chips adhere to the wafer, they are easily removed by a subsequent cleaning step or the like.

That is, according to one aspect of the present invention, it is possible to form a frame unit using a polyolefin-based sheet without a glue layer, and no cutting chips having high adhesive strength are generated when cutting a wafer, and the device chip is made of the cutting chips. Quality deterioration is suppressed.

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

It is a perspective view which shows the wafer schematically. It is a perspective view which shows the state of positioning a wafer on the holding surface of a chuck table schematically. It is a perspective view which shows typically the polyolefin-based sheet arrangement process. It is a perspective view which shows an example of the integration process schematically. FIG. 5A is a perspective view schematically showing the frame support process, and FIG. 5B is a perspective view schematically showing the formed frame unit. It is a perspective view which shows typically the division process. It is a perspective view which shows typically the carrying-in of a frame unit into a pickup device. FIG. 8A is a cross-sectional view schematically showing a frame unit fixed on a frame support base, and FIG. 8B is a cross-sectional view schematically showing a pickup process.

An embodiment 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 the present embodiment will be described. FIG. 1 is a perspective view schematically showing the wafer 1. Wafer 1 is made of, for example, a material such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor, or a material such as sapphire, glass, or quartz. It is a substantially disk-shaped substrate or the like.

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

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

The annular frame 7 (see FIGS. 5A and 5B, etc.) has, for example, a first frame 7a made of a material such as metal and having an opening 7b large enough to accommodate the wafer 1. , A second frame 7f having an opening 7g large enough to accommodate the wafer 1, and two members. For example, the first frame 7a and the second frame 7f have substantially the same shape.

The first frame 7a includes a plurality of pins 7d on the upper surface 7c. Further, a plurality of magnets 7e are embedded and arranged in the upper surface 7c of the first frame 7a. The second frame 7f is provided with a plurality of through holes 7i penetrating in the thickness direction. The through hole of the second frame 7f so that the pin 7d of the first frame 7a is fitted into the through hole 7i when the first frame 7a and the second frame 7f are overlapped with each other. The 7i is formed by the number, position and size corresponding to the pins 7d of the first frame 7a.

The polyolefin-based sheet 9 (see FIG. 3 and the like) is a flexible resin-based sheet, and the front and back surfaces are flat. The frame 7 has a diameter larger than the diameter of the opening 7b of the first frame 7a and the opening 7g of the second frame 7f, and does not have a glue layer. The polyolefin-based sheet 9 is a polymer sheet synthesized using an alkene as a monomer, and is, for example, a polyethylene sheet, a polypropylene sheet, a polystyrene sheet, or the like, which is transparent or translucent to visible light. However, the polyolefin-based sheet 9 is not limited to this, and may be opaque.

Since the polyolefin-based sheet 9 does not have adhesiveness, it cannot be attached to the wafer 1 at room temperature. However, since the polyolefin-based sheet 9 has thermoplasticity, when it is heated to a temperature near the melting point in a state where it is bonded to the wafer 1 while applying a predetermined pressure, it can be partially melted and adhered to the wafer 1.

In the processing method of the wafer 1 according to the present embodiment, the polyolefin-based sheet 9 is adhered to the back surface 1b side of the wafer 1 by heating, and the outer peripheral portion of the polyolefin-based sheet 9 is formed by the first frame 7a and the second frame 7f. It is sandwiched between, to form a frame unit.

Next, each step of the processing method of the wafer 1 according to the present embodiment will be described. First, a polyolefin-based sheet arranging step is carried out in preparation for integrating the wafer 1 and the polyolefin-based sheet 9. FIG. 2 is a perspective view schematically showing how the wafer 1 is positioned on the holding surface 2a of the chuck table 2. As shown in FIG. 2, the polyolefin-based sheet arranging step is carried out on a chuck table 2 having a holding surface 2a on the upper portion.

The chuck table 2 is provided with a porous member having a diameter larger than the outer diameter of the wafer 1 in the center of the upper portion. The upper surface of the porous member is the holding surface 2a of the chuck table 2. As shown in FIG. 3, the chuck table 2 has an exhaust passage inside which one end leads to the porous member, and a suction source 2b is arranged on the other end side of the exhaust passage. A switching portion 2c for switching between a communication state and a disconnection state is provided in the exhaust passage, and when the switching portion 2c is in the communication state, a negative force generated by the suction source 2b is generated on the held object placed on the holding surface 2a. Pressure acts and the object to be held is sucked and held in the chuck table 2.

In the polyolefin-based sheet arrangement step, first, as shown in FIG. 2, the wafer 1 is placed on the holding surface 2a of the chuck table 2. At this time, the surface 1a side of the wafer 1 is directed downward. Next, the polyolefin-based sheet 9 is arranged on the back surface 1b of the wafer 1. FIG. 3 is a perspective view schematically showing the polyolefin-based sheet arrangement process. As shown in FIG. 3, the polyolefin-based sheet 9 is arranged on the wafer 1 so as to cover the wafer 1.

In the polyolefin-based sheet disposing step, a chuck table 2 having a holding surface 2a having a diameter smaller than the diameter of the polyolefin-based sheet 9 is used. When the negative pressure of the chuck table 2 is applied to the polyolefin sheet 9 in the integration step to be performed later, if the entire holding surface 2a is not covered by the polyolefin sheet 9, the negative pressure leaks from the gap. This is because the pressure cannot be appropriately applied to the polyolefin sheet 9.

In the processing method of the wafer 1 according to the present embodiment, next, hot air is blown to the polyolefin-based sheet 9 to heat the polyolefin-based sheet 9, and the wafer 1 and the polyolefin-based sheet 9 are integrated. To carry out. FIG. 4 is a perspective view schematically showing an example of the integration process. In FIG. 4, what can be visually recognized through the polyolefin-based sheet 9 which is transparent or translucent with respect to visible light is shown by a broken line.

In the integration step, first, the switching portion 2c of the chuck table 2 is operated to establish a communication state, the suction source 2b is connected to the porous member on the upper part of the chuck table 2, and the negative pressure by the suction source 2b is applied to the polyolefin sheet 9. Make it work. Then, the polyolefin-based sheet 9 comes into close contact with the wafer 1 due to the atmospheric pressure.

Next, the polyolefin sheet 9 is heated while sucking the polyolefin sheet 9 by the suction source 2b. Heating of the polyolefin-based sheet 9 is performed, for example, by a heat gun 4 arranged above the chuck table 2 as shown in FIG.

The heat gun 4 is provided with a heating means such as a heating wire and a blowing mechanism such as a fan inside, and can heat and inject air. When the hot air 4a is supplied from the upper surface to the polyolefin sheet 9 by the heat gun 4 while the negative pressure from the suction source 2b is applied to the polyolefin sheet 9 and the polyolefin sheet 9 is heated to a predetermined temperature, the polyolefin sheet 9 becomes the wafer 1. Is thermocompression bonded to.

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

When thermocompression bonding is performed, the polyolefin-based sheet 9 is preferably heated to a temperature equal to or lower than its melting point. This is because if the heating temperature exceeds the melting point, the polyolefin-based sheet 9 may be melted and the shape of the sheet may not be maintained. Further, the polyolefin-based sheet 9 is preferably heated to a temperature equal to or higher than its softening point. This is because thermocompression bonding cannot be performed properly unless the heating temperature reaches the softening point. That is, it is preferable that the polyolefin-based sheet 9 is heated to a temperature equal to or higher than its softening point and lower than its melting point.

Furthermore, some polyolefin-based sheets 9 may not have a clear softening point. Therefore, when thermocompression bonding is performed, the polyolefin-based sheet 9 is preferably heated to a temperature 20 ° C. lower than its melting point and lower than its melting point.

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

Here, the heating temperature refers to the temperature of the polyolefin-based sheet 9 when the integration step is carried out. For example, in a heat source such as a heat gun 4, a model capable of setting an output temperature is put into practical use, but even if the polyolefin-based sheet 9 is heated using the heat source, the temperature of the polyolefin-based sheet 9 is set. It may not reach the output temperature. Therefore, in order to heat the polyolefin-based sheet 9 to a predetermined temperature, the output temperature of the heat source may be set higher than the melting point of the polyolefin-based sheet 9.

In the processing method of the wafer 1 according to the present embodiment, the frame support step of supporting the polyolefin-based sheet 9 with the frame 7 is carried out before or after the integration step. FIG. 5A is a perspective view schematically showing the frame support process. In the frame support step, the outer peripheral portion of the polyolefin-based sheet 9 is sandwiched between the first frame 7a and the second frame 7f, and the polyolefin-based sheet 9 is supported by the frame 7.

First, the polyolefin-based sheet 9 is placed on the upper surface 7c of the first frame 7a. At this time, the position of the polyolefin-based sheet 9 is determined so as to close all the openings 7b of the first frame 7a. Next, the second frame 7f is placed on the polyolefin-based sheet 9 with the lower surface 7h facing downward. At this time, the position of the second frame 7f is determined so that the through hole 7i of the second frame 7f is fitted into the pin 7d of the first frame 7a.

When the first frame 7a and the second frame 7f are overlapped with each other, the magnetic force generated by the plurality of magnets 7e included in the first frame 7a acts to attract the two frames to each other, and the outer peripheral portion of the polyolefin sheet 9 is formed. It is sandwiched between both frames. Therefore, the polyolefin-based sheet 9 is supported by the frame 7. At this time, since the pin 7d of the first frame 7a is fitted into the through hole 7i of the second frame 7f, the first frame 7a and the second frame 7f do not shift horizontally from each other.

Although the case where the frame support process is performed after the integration process has been described, the wafer processing method according to the present embodiment is not limited to this. For example, the integration step may be carried out after the frame support step. In this case, the outer peripheral portion of the polyolefin-based sheet 9 is adhered to the first frame 7a and the second frame 7f by heating in the integration step, and the polyolefin-based sheet 9 is supported by the frame 7 with a stronger force.

Next, in the wafer 1 processing method according to the present embodiment, a division step of cutting the wafer 1 in the state of the frame unit 11 with a cutting blade and dividing the wafer 1 is performed. The dividing step is carried out, for example, by the cutting apparatus shown in FIG. FIG. 6 is a perspective view schematically showing the division process.

The cutting device 6 includes a cutting unit 8 for cutting the workpiece and a chuck table (not shown) for holding the workpiece. The cutting unit 8 includes a cutting blade 12 having an annular grindstone portion, and a spindle (not shown) whose tip end side is pierced through a through hole in the center of the cutting blade 12 to rotate the cutting blade 12. The cutting blade 12 includes, for example, an annular base having the through hole in the center and an annular grindstone portion arranged on the outer peripheral portion of the annular base.

The base end side of the spindle is connected to a spindle motor (not shown) housed inside the spindle housing 10, and the cutting blade 12 can be rotated by operating the spindle motor.

When the workpiece is cut by the cutting blade 12, heat is generated due to the friction between the cutting blade 12 and the workpiece. Further, when the workpiece is cut, cutting chips are generated from the workpiece. Therefore, in order to remove heat and cutting chips generated by cutting, cutting water such as pure water is supplied to the cutting blade 12 and the workpiece while the workpiece is being cut. The cutting unit 8 is provided with, for example, a cutting water supply nozzle 14 for supplying cutting water to the cutting blade 12 or the like on the side of the cutting blade 12.

When cutting the wafer 1, the frame unit 11 is placed on the chuck table, and the wafer 1 is held by the chuck table via the polyolefin-based sheet 9. Then, the chuck table is rotated to align the planned division line 3 of the wafer 1 with the machining feed direction of the cutting device 6. Further, the relative positions of the chuck table and the cutting unit 8 are adjusted so that the cutting blade 12 is arranged above the extension line of the scheduled division line 3.

Next, the cutting blade 12 is rotated by rotating the spindle. Then, the cutting unit 8 is lowered to a predetermined height position, and the chuck table and the cutting unit 8 are relatively moved along a direction parallel to the upper surface of the chuck table. Then, the grindstone portion of the rotating cutting blade 12 comes into contact with the wafer 1, the wafer 1 is cut, and a cutting mark 3a along the scheduled division line 3 is formed on the wafer 1 and the polyolefin-based sheet 9.

After cutting along one scheduled division line 3, the chuck table and the cutting unit 8 are moved in the indexing feed direction perpendicular to the machining feed direction, and the wafer 1 is similarly moved along the other scheduled division lines 3. Perform cutting. After cutting along all scheduled split lines 3 along one direction, the chuck table is rotated around an axis perpendicular to the holding surface and similarly along the scheduled split lines 3 along the other direction. The wafer 1 is cut. Cutting the wafer 1 along all the scheduled division lines 3 of the wafer 1 completes the division step.

The cutting device 6 may include a cleaning unit (not shown) in the vicinity of the cutting unit 8. The wafer 1 cut by the cutting unit 8 may be conveyed 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 reciprocate above the frame unit 11.

The cleaning table is rotated around an axis perpendicular to the holding surface, and the cleaning water supply nozzle reciprocates along a path passing above the center of the holding surface while supplying cleaning liquid such as pure water to the wafer 1 from the cleaning water supply nozzle. When it is moved, the surface 1a side of the wafer 1 can be cleaned.

When the division step is performed, the wafer 1 is divided into individual device chips. The formed device chip is supported by the polyolefin-based sheet 9. When cutting the wafer 1, in order to divide the wafer 1 reliably, the cutting unit 8 has a predetermined height so that the height position of the lower end of the cutting blade 12 is lower than the back surface 1b of the wafer 1. It is positioned in the sword. Therefore, when the wafer 1 is cut, the polyolefin-based sheet 9 is also cut, and cutting chips derived from the polyolefin-based sheet 9 are generated.

When an adhesive tape is used for the frame unit 11 instead of the polyolefin-based sheet 9, cutting chips derived from the glue layer of the adhesive tape are generated. In this case, the cutting chips are taken into the cutting water ejected from the cutting water supply nozzle 14 and diffused onto the surface 1a of the wafer 1. Cutting debris derived from the glue layer is likely to reattach to the surface of the device 5, and is not easy to remove in a cleaning step of the wafer 1 performed after cutting. When cutting chips derived from the glue layer adhere, the quality of the formed device chip deteriorates.

On the other hand, in the processing method of the wafer 1 according to the present embodiment, the polyolefin-based sheet 9 having no glue layer is used instead of the adhesive tape having the glue layer on the frame unit 11. Even if cutting chips derived from the polyolefin-based sheet 9 are generated, taken into cutting water and diffused on the surface of the wafer, the cutting chips are relatively difficult to adhere to the wafer 1. Further, even if cutting chips adhere to the wafer 1, they are easily removed by a subsequent cleaning step or the like. Therefore, the deterioration of the quality of the device chip due to the cutting chips is suppressed.

In the processing method of the wafer 1 according to the present embodiment, next, a pick-up step of picking up the individual device chips from the polyolefin-based sheet 9 is carried out. In the pickup process, the pickup device 16 shown in the lower part of FIG. 7 is used. FIG. 7 is a perspective view schematically showing the loading of the frame unit 11 into the pickup device 16.

The pickup device 16 includes a cylindrical drum 18 having a diameter larger than the diameter of the wafer 1 and a frame holding unit 20 including a frame support base 22. The frame support base 22 of the frame holding unit 20 has an opening having a diameter larger than the diameter of the drum 18, is arranged at the same height as the upper end of the drum 18, and the upper end of the drum 18 is on the outer peripheral side. Surround from.

A clamp 24 is arranged on the outer peripheral side of the frame support base 22. When the frame unit 11 is placed on the frame support base 22 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 base 22.

The frame support base 22 is supported by a plurality of rods 26 extending in the vertical direction, and an air cylinder 28 for raising and lowering the rods 26 is arranged at the lower end of each rod 26. The plurality of air cylinders 28 are supported by a disk-shaped base 30. When each air cylinder 28 is operated, the frame support base 22 is pulled down with respect to the drum 18.

Inside the drum 18, a push-up mechanism 32 that pushes up the device chip supported by the polyolefin-based sheet 9 from below is disposed. The push-up mechanism 32 has a function of blowing out air 32a upward. Further, above the drum 18, a collet 34 (see FIG. 8B) capable of sucking and holding the device chip is arranged. The push-up mechanism 32 and the collet 34 can move horizontally along the upper surface of the frame support base 22. Further, the collet 34 is connected to the suction source 34a (see FIG. 8B) via the switching portion 34b (see FIG. 8B).

In the pickup process, first, the air cylinder 28 is operated to adjust the height of the frame support 22 so that the height of the upper end of the drum 18 of the pickup device 16 and the height of the upper surface of the frame support 22 substantially match. Adjust. For example, the height position of the upper surface of the frame support base 22 may be positioned at a height position lower than the upper end of the drum 18 by the thickness of the first frame 7a. Next, the frame unit 11 carried out from the cutting device 6 is placed on the drum 18 of the pickup device 16.

After that, the frame 7 of the frame unit 11 is fixed on the frame support base 22 by the clamp 24. FIG. 8A is a cross-sectional view schematically showing the frame unit 11 fixed on the frame support base 22. Cutting marks 3a are formed and divided on the wafer 1 by the dividing step.

Next, the air cylinder 28 is operated to pull down the frame support base 22 of the frame holding unit 20 with respect to the drum 18. Then, as shown in FIG. 8B, the polyolefin-based sheet 9 is expanded in the outer peripheral direction. FIG. 8B is a cross-sectional view schematically showing the pickup process.

When the polyolefin-based sheet 9 is expanded in the outer peripheral direction, the distance between the device chips 1c supported by the polyolefin-based sheet 9 is widened. Then, it becomes difficult for the device chips 1c to come into contact with each other, and it becomes easy to pick up the individual device chips 1c. Then, the device chip 1c to be picked up is determined, the push-up mechanism 32 is moved below the device chip 1c, and the collet 34 is moved above the device chip 1c.

After that, the push-up mechanism 32 is operated to blow air 32a from the polyolefin-based sheet 9 side to push up the device chip 1c. Then, the switching portion 34b is operated to communicate the collet 34 with the suction source 34a. Then, the device chip 1c is sucked and held by the collet 34, and the device chip 1c is picked up from the polyolefin-based sheet 9. The individual device chips 1c picked up are then mounted on a predetermined wiring board or the like for use.

When the device chip is picked up by blowing air 32a from the polyolefin-based sheet 9 side onto the device chip to push up the device chip, the load applied to the device chip when the device chip is peeled off from the polyolefin-based sheet 9 is reduced. Will be done.

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 the adhesive tape. Therefore, even if the wafer 1 is cut, cutting chips derived from the glue layer of the adhesive tape are not generated, and the cutting chips do not adhere to the device chip 1c. Therefore, the quality of the device chip 1c is not deteriorated.

The present invention is not limited to the description of the above embodiment, and can be modified in various ways. For example, in the above embodiment, the case where the polyolefin-based sheet 9 is, for example, a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet has been described, but one aspect of the present invention is not limited thereto. For example, as the polyolefin-based sheet, other materials may be used, and a copolymer of propylene and ethylene, an olefin-based elastomer, or the like may be used.

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.

1 Wafer 1a Front surface 1b Back surface 3 Scheduled division line 3a Cutting mark 5 Device 7,7a, 7f Frame 7b, 7g Opening 7c Top surface 7d Pin 7e Magnet 7h Bottom surface 7i Through hole 9 Polyethylene sheet 11 Frame unit 2 Chuck table 2a Holding surface 2b, 34a Suction source 2c, 34b Switching part 4 Heat gun 4a Hot air 6 Cutting device 8 Cutting unit 10 Spindle housing 12 Cutting blade 14 Cutting water supply nozzle 16 Pickup device 18 Drum 20 Frame holding unit 22 Frame support base 24 Clamp 26 Rod 28 Air Cylinder 30 Base 32 Push-up mechanism 32a Air 34 Collet

Claims (5)

A method of processing a wafer in which a plurality of devices divide a wafer formed in each region of a surface partitioned by a planned division line into individual device chips.
A polyolefin-based sheet arranging process for arranging a polyolefin-based sheet on the back surface of the wafer, and
An integration step of applying hot air to the polyolefin-based sheet to heat the polyolefin-based sheet and integrating the wafer and the polyolefin-based sheet.
Before or after the integration step, a first frame having an opening large enough to accommodate the wafer and having a plurality of magnets and a second frame having an opening large enough to accommodate the wafer. Using a frame composed of, the outer peripheral portion of the polyolefin-based sheet is sandwiched between the first frame and the second frame by the magnetic force generated by the magnet to hold the polyolefin-based sheet. The frame support process of supporting with the frame and
A dividing process in which the wafer is cut along a planned division line using a cutting device equipped with a cutting blade rotatably, and the wafer is divided into individual device chips.
A pickup process in which device chips are individually pushed up by blowing air from the polyolefin-based sheet side and the device chips are picked up from the polyolefin-based sheet.
A method for processing a wafer, which comprises. The wafer processing method according to claim 1, wherein in the pickup step, the polyolefin-based sheet is expanded to widen the distance between each device chip. The wafer processing method according to claim 1, wherein the polyolefin-based sheet is any one of a polyethylene sheet, a polypropylene sheet, and a polystyrene sheet. In the integration step, when the polyolefin-based sheet is the polyethylene sheet, the heating temperature is 120 ° C. to 140 ° C., and when the polyolefin-based sheet is the polypropylene sheet, the heating temperature is 160 ° C. to 180 ° C. The method for processing a wafer according to claim 3, wherein the heating temperature is 220 ° C. to 240 ° C. when the polyolefin-based sheet is the polystyrene sheet. The wafer processing method according to claim 1, wherein the wafer is composed of any of Si, GaN, GaAs, and glass.

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