JP7365760B2 - 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.

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 in which a plurality of devices are formed on each region of a front surface partitioned by dividing lines and is divided into individual device chips, the method comprising: a polyolefin sheet disposing step of disposing a polyolefin sheet without an adhesive layer ; an integrating step of heating the polyolefin sheet and integrating the wafer and the polyolefin sheet by thermocompression bonding; Before or after the integration step, a first frame having an opening large enough to accommodate the wafer and including a plurality of magnets, and a second frame having an opening large enough to accommodate the wafer, The polyolefin sheet is supported by the frame by using a frame constructed by the above-mentioned method, with the outer periphery of the polyolefin sheet being sandwiched between the first frame and the second frame by the magnetic force generated by the magnet. a frame supporting process for cutting the wafer into individual device chips by cutting the wafer along the dividing line using a cutting device equipped with a rotatable cutting blade; A wafer processing method is provided, which comprises a pickup step of picking up individual device chips.

Preferably, in the integration step, the thermocompression bonding is performed by irradiation with infrared rays.

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.

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 a wafer processing method according to one aspect of the present invention, a frame unit and a wafer are integrated using a polyolefin sheet without an adhesive layer without using an adhesive tape having an adhesive layer in the frame unit. The integration step of integrating the polyolefin sheet and the wafer is achieved by thermocompression bonding.

A 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 includes 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.

In the frame supporting step, a polyolefin sheet is placed between the first frame and the second frame, and is sandwiched between the first frame and the second frame. Polyolefin sheets can be supported by a frame.

That is, even if the polyolefin sheet does not have an adhesive layer, by performing the integration step and the frame support step, the wafer, the polyolefin sheet, and the frame can be integrated to form a frame unit. .

Thereafter, the wafer is cut with a cutting blade to divide the wafer into individual device chips, 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, and highly adhesive cutting debris is not generated when cutting a wafer, and device chips due to the cutting debris are not generated. quality deterioration is suppressed.

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. FIG. 3 is a perspective view schematically showing how the wafer is positioned on the holding surface of the chuck table. 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. 3 is a perspective view schematically showing an example of an integration process. FIG. 3 is a perspective view schematically showing an example of an integration process. FIG. 7(A) is a perspective view schematically showing a frame supporting step, and FIG. 7(B) is a perspective view schematically showing a 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. 10(A) is a cross-sectional view schematically showing a frame unit fixed on a frame support, and FIG. 10(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 FIGS. 7(A) and 7(B), etc.) is made of a material such as metal, and includes a first frame 7a having an opening 7b large enough to accommodate the wafer 1. , and a second frame 7f having an opening 7g large enough to accommodate the wafer 1. 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 that penetrate in the thickness direction. The through-hole of the second frame 7f is arranged such that when the first frame 7a and the second frame 7f are overlapped, the pin 7d of the first frame 7a is fitted into the through-hole 7i. 7i are formed in number, position and size corresponding to the pins 7d of the first frame 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 diameter of the opening 7b of the first frame 7a and the opening 7g of the second frame 7f that constitute the frame 7, and does not include 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.

Since the polyolefin sheet 9 does not have adhesive properties, it cannot be attached to the wafer 1 at room temperature. However, since the polyolefin sheet 9 has thermoplasticity, when it is heated to a temperature close to its melting point while being bonded to the wafer 1 while applying a predetermined pressure, it can be partially melted and bonded to the wafer 1.

In the method for processing a wafer 1 according to this embodiment, a polyolefin sheet 9 is bonded to the back surface 1b of the wafer 1 by thermocompression bonding, and the outer peripheral portion of the polyolefin sheet 9 is attached to a first frame 7a and a second frame 7f. A frame unit is formed by sandwiching between the two.

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 and the polyolefin sheet 9, a polyolefin sheet disposing step is performed. 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 sheet disposing process is carried out on a chuck table 2 having a holding surface 2a on the top.

The chuck table 2 includes a porous member having a diameter larger than the outer diameter of the wafer 1 at the upper center. 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 internal exhaust passage whose one end communicates with the porous member, and a suction source 2b is disposed at the other end of the exhaust passage. The exhaust path is provided with a switching part 2c that switches between a communication state and a disconnection state, and when the switching part 2c is in the communication state, the vacuum generated by the suction source 2b is applied to the object placed on the holding surface 2a. Pressure is applied, and the object to be held is suctioned and held on the chuck table 2.

In the polyolefin sheet disposing process, 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 front surface 1a side of the wafer 1 is directed downward. Next, a polyolefin sheet 9 is placed on the back surface 1b of the wafer 1. 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 so as to cover the wafer 1.

In the polyolefin sheet disposing process, a chuck table 2 having a holding surface 2a having a diameter smaller than the diameter of the polyolefin sheet 9 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 this embodiment, next, an integration step is performed in which the polyolefin sheet 9 is heated and the wafer 1 and the polyolefin sheet 9 are integrated by thermocompression bonding. 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 due to atmospheric pressure.

Next, the polyolefin sheet 9 is heated while being suctioned by the suction source 2b to carry out thermocompression bonding. For heating the polyolefin sheet 9, for example, as shown in FIG. 4, an infrared lamp 4 disposed above the chuck table 2 is used. The infrared lamp 4 is capable of emitting at least infrared rays 4a of a wavelength that is absorbed by the material of the polyolefin sheet 9.

The infrared lamp 4 is operated to irradiate the polyolefin sheet 9 with infrared rays 4a to heat the polyolefin sheet 9. Then, the polyolefin sheet 9 is bonded to the wafer 1 by thermocompression.

Heating of the polyolefin sheet 9 may be performed by other methods. FIG. 5 is a perspective view schematically showing another example of the integration process. In FIG. 5, broken lines indicate what is visible through the polyolefin sheet 9, which is transparent or translucent to visible light. The integration process shown in FIG. 5 is performed by a heat gun 6 disposed above the chuck table 2.

The heat gun 6 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 from the suction source 2b to the polyolefin sheet 9, hot air 6a is supplied from above to the polyolefin sheet 9 using the heat gun 6 to heat the polyolefin sheet 9 to a predetermined temperature. is heat-compressed.

Further, the heating of the polyolefin sheet 9 may be carried out by still another method, for example, by pressing the wafer 1 from above with a member heated to a predetermined temperature. FIG. 6 is a perspective view schematically showing another example of the integration process. In FIG. 6, broken lines indicate what is visible through the polyolefin sheet 9, which is transparent or translucent to visible light.

In the integration step shown in FIG. 6, for example, a heat roller 8 having an internal heat source is used. In the integration step shown in FIG. 6, first, negative pressure from the suction source 2b is applied to the polyolefin sheet 9, and the polyolefin sheet 9 is brought into close contact with the wafer 1 by atmospheric pressure.

Thereafter, the heat roller 8 is heated to a predetermined temperature and placed on one end of the holding surface 2a of the chuck table 2. Then, the heat roller 8 is rotated and rolled on the chuck table 2 from the one end to the other end. Then, the polyolefin sheet 9 is bonded to the wafer 1 by thermocompression. At this time, when a force is applied in a direction to push down the polyolefin sheet 9 using the heat roller 8, thermocompression bonding is performed at a pressure higher than atmospheric pressure. Note that it is preferable that the surface of the heat roller 8 be coated with a fluororesin.

Alternatively, the heat roller 8 may be replaced with an iron-like pressing member that is equipped with an internal heat source and has a flat bottom plate to carry out thermocompression bonding of the polyolefin sheet 9. In this case, the pressing member is heated to a predetermined temperature to serve as a hot plate, and the pressing member presses the polyolefin sheet 9 held on the chuck table 2 from above.

When the polyolefin sheet 9 is heated to a temperature close to its melting point by any method, the polyolefin sheet 9 is bonded to the wafer 1 by thermocompression. 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.

In addition, when carrying out thermocompression bonding, the polyolefin sheet 9 is preferably heated to a temperature below its melting point. This is because if the heating temperature exceeds the melting point, the polyolefin sheet 9 may melt and become unable to maintain its shape. Further, the polyolefin sheet 9 is preferably heated to a temperature equal to or higher than its softening point. This is because thermocompression bonding cannot be properly performed unless the heating temperature reaches the softening point. That is, 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 thermocompression bonding is carried out, the polyolefin sheet 9 is preferably heated to a temperature that is 20° C. lower than its melting point 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, heat sources such as an infrared lamp 4, a heat gun 6, a heat roller 8, etc., have models that can set the output temperature, but even if the heat source is used to heat the polyolefin sheet 9, the polyolefin sheet In some cases, the temperature of No. 9 does not reach the set output temperature. 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.

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

First, the polyolefin sheet 9 is placed on the upper surface 7c of the first frame 7a. At this time, the polyolefin sheet 9 is positioned so as to completely close the opening 7b of the first frame 7a. Next, the second frame 7f is placed on the polyolefin sheet 9 with the lower surface 7h facing downward. At this time, the second frame 7f is positioned 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, the magnetic force generated by the plurality of magnets 7e included in the first frame 7a acts to draw both frames together, and the outer peripheral portion of the polyolefin sheet 9 It is held between both frames. Therefore, the polyolefin 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 from each other in the horizontal direction.

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

Next, in the method for processing the wafer 1 according to the present embodiment, a dividing step is performed in which the wafer 1 in the state of the frame unit 11 is cut and divided using a cutting blade. The dividing step is performed using, for example, a cutting device shown in FIG. 8 . FIG. 8 is a perspective view schematically showing the dividing process.

The cutting device 10 includes a cutting unit 12 that cuts a workpiece, and a chuck table (not shown) that holds the workpiece. The cutting unit 12 includes a cutting blade 16 having an annular grindstone portion, and a spindle (not shown) whose tip end is penetrated through a central through hole of the cutting blade 16 and rotates the cutting blade 16. The cutting blade 16 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 14, and when the spindle motor is operated, the cutting blade 16 can be rotated.

When a workpiece is cut by the cutting blade 16, heat is generated due to friction between the cutting blade 16 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 16 and the workpiece while cutting the workpiece. The cutting unit 12 includes, for example, a cutting water supply nozzle 18 on the side of the cutting blade 16 for supplying cutting water to the cutting blade 16 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. Then, the chuck table is rotated to align the scheduled dividing line 3 of the wafer 1 with the processing feed direction of the cutting device 10. Further, the relative positions of the chuck table and the cutting unit 12 are adjusted so that the cutting blade 16 is disposed above the extension line of the scheduled dividing line 3.

Next, the cutting blade 16 is rotated by rotating the spindle. Then, the cutting unit 12 is lowered to a predetermined height position, and the chuck table and cutting unit 12 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 16 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 planned dividing line 3, the chuck table and cutting unit 12 are moved in the index feed direction perpendicular to the processing feed direction, and the wafer 1 is similarly cut along the other planned 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 10 may include a cleaning unit (not shown) near the cutting unit 12. The wafer 1 cut by the cutting unit 12 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 reciprocate 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 12 is set at a predetermined height so that the lower end of the cutting blade 16 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 an adhesive tape is used for the frame unit 11 instead of the polyolefin sheet 9, cutting debris originating from the adhesive layer of the adhesive tape is generated. In this case, the cutting waste is taken in by the cutting water sprayed from the cutting water supply nozzle 18 and spread onto the surface 1a of the wafer 1. Cutting debris originating from the glue layer is likely to re-adhere to the surface of the device 5, and is also difficult to remove in a cleaning process of the wafer 1 after cutting. If cutting debris originating from the glue layer adheres, the quality of the formed device chip will deteriorate, which poses 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 pickup process, a pickup device 20 shown in the lower part of FIG. 9 is used. FIG. 9 is a perspective view schematically showing how the frame unit 11 is carried into the pickup device 20. As shown in FIG.

The pickup device 20 includes a cylindrical drum 22 having a diameter larger than the diameter of the wafer 1 and a frame holding unit 24 including a frame support 26 . The frame support stand 26 of the frame holding unit 24 is provided with an opening having a diameter larger than the diameter of the drum 22, is arranged at the same height as the upper end of the drum 22, and has the upper end of the drum 22 on the outer circumferential side. Surround from.

A clamp 28 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 28, the frame unit 11 is fixed to the frame support stand 26.

The frame support stand 26 is supported by a plurality of rods 30 extending in the vertical direction, and an air cylinder 32 for raising and lowering the rods 30 is disposed at the lower end of each rod 30. The plurality of air cylinders 32 are supported by a disc-shaped base 34. Activating each air cylinder 32 pulls the frame support 26 down relative to the drum 22 .

A push-up mechanism 36 is disposed inside the drum 22 to push up the device chip supported by the polyolefin sheet 9 from below. Moreover, a collet 38 (see FIG. 10(B)) that can suck and hold a device chip is provided above the drum 22. The push-up mechanism 36 and collet 38 are movable in the horizontal direction along the upper surface of the frame support 26. Further, the collet 38 is connected to a suction source 38a (see FIG. 10(B)) via a switching portion 38b (see FIG. 10(B)).

In the pickup process, first, the height of the frame support 26 is adjusted by operating the air cylinder 32 so that the height of the upper end of the drum 22 of the pickup device 20 and the height of the upper surface of the frame support 26 approximately match. Adjust. For example, the height position of the upper surface of the frame support stand 26 may be positioned at a height position lower than the upper end of the drum 22 by the thickness of the first frame 7a. Next, the frame unit 11 carried out from the cutting device 10 is placed on the drum 22 of the pickup device 20.

Thereafter, the frame 7 of the frame unit 11 is fixed onto the frame support stand 26 using the clamp 28. FIG. 10(A) is a cross-sectional view schematically showing the frame unit 11 fixed on the frame support 26. As shown in FIG. The wafer 1 is divided by cutting marks 3a formed in the dividing step.

Next, the air cylinder 32 is operated to lower the frame support base 26 of the frame holding unit 24 with respect to the drum 22. Then, as shown in FIG. 10(B), the polyolefin sheet 9 is expanded in the outer circumferential direction. FIG. 10(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 36 is moved below the device chip 1c, and the collet 38 is moved above the device chip 1c.

Thereafter, the push-up mechanism 36 is operated to push up the device chip 1c from the polyolefin sheet 9 side. Then, the switching section 38b is operated to communicate the collet 38 with the suction source 38a. Then, the device chip 1c is sucked and held by the collet 38, 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, 7a, 7f Frame 7b, 7g Opening 7c Top surface 7d Pin 7e Magnet 7h Bottom surface 7i Through hole 9 Polyolefin sheet 11 Frame unit 2 Chuck table 2a Holding surface 2b, 38a Suction source 2c, 38b Switching part 4 Infrared lamp 4a Infrared ray 6 Heat gun 6a Hot air 8 Heat roller 10 Cutting device 12 Cutting unit 14 Spindle housing 16 Cutting blade 18 Cutting water supply nozzle 20 Pick-up device 22 Drum 24 Frame holding unit 26 Frame Support stand 28 Clamp 30 Rod 32 Air cylinder 34 Base 36 Push-up mechanism 38 Collet

Claims (6)

A wafer processing method in which a wafer in which a plurality of devices are formed in each region of a surface partitioned by dividing lines is divided into individual device chips, the method comprising:
a polyolefin sheet disposing step of disposing a polyolefin sheet without an adhesive layer on the back side of the wafer;
an integration step of heating the polyolefin sheet and integrating the wafer and the polyolefin sheet by thermocompression bonding;
Before or after the integration step, a first frame having an opening large enough to accommodate the wafer and including a plurality of magnets, and a second frame having an opening large enough to accommodate the wafer, The polyolefin sheet is supported by the frame by using a frame constructed by the above-mentioned method, with the outer periphery of the polyolefin sheet being sandwiched between the first frame and the second frame by the magnetic force generated by the magnet. frame support process,
a dividing step of cutting the wafer along a dividing line using a cutting device rotatably equipped with a cutting blade to divide the wafer into individual device chips;
a pickup step of picking up individual device chips from the polyolefin sheet;
A wafer processing method comprising: 2. The wafer processing method according to claim 1, wherein the thermocompression bonding is performed by irradiating infrared rays in the integrating step. 2. The method for processing a wafer according to claim 1, wherein in the pickup step, the polyolefin sheet is expanded to widen the distance between each device chip, and the device chips are 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.