JP2020064957A - Wafer processing method - Google Patents

Abstract

To form a device chip without deteriorating quality.SOLUTION: A wafer processing method for dividing a wafer in which a plurality of devices are formed in each region on a surface partitioned by division schedule lines into individual device chips comprises a polyolefin-based sheet arranging step, an integrating step, a dividing step, and a picking-up step. The polyolefin-based sheet arranging step positions the wafer in an opening of a frame and arranges a polyolefin-based sheet in a rear surface of the wafer and an outer periphery of the frame, the opening housing the wafer. The integrating step heats the polyolefin-based sheet by applying hot air to the sheet and integrates the wafer and the frame via the polyolefin-based sheet. The dividing step forms a division groove by irradiating the wafer with a laser beam of a wavelength having absorbability to the wafer along the division schedule lines and divides the wafer into individual device chips. The picking-up step picks up individual device chips from the polyolefin-based sheet.SELECTED DRAWING: Figure 4

Description

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

  In the manufacturing process of device chips used in electronic devices such as mobile phones and personal computers, first, a plurality of planned dividing 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), LSIs (Large-Scale Integrated circuits), and LEDs (Light Emitting Diodes) are formed in the respective areas divided by the planned dividing lines.

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

  A laser processing device is used for dividing the wafer, for example (see Patent Document 1). The laser processing apparatus includes a chuck table that holds the wafer via an adhesive tape, and a laser processing unit that irradiates the wafer with a laser beam having a wavelength having an absorptivity for the wafer.

  When dividing the wafer, a frame unit is placed on the chuck table and the wafer is held on the chuck table via an adhesive tape. Then, while the chuck table and the laser processing unit are relatively moved along a direction parallel to the upper surface of the chuck table, the laser processing unit irradiates the wafer with the laser beam. When the laser beam is irradiated, a dividing groove is formed in the wafer along each dividing line by ablation, and the wafer is divided.

  After that, the frame unit is carried out from the laser processing apparatus, and the adhesive tape is subjected to a treatment such as irradiation with ultraviolet rays to reduce the adhesive force of the adhesive tape, and the device chip is picked up. As a processing device with high production efficiency of device chips, a processing device is known that can divide a wafer and irradiate an ultraviolet ray to an adhesive tape continuously by one device (see Patent Document 2). The device chip picked up from the adhesive tape is mounted on a predetermined wiring board or the like.

JP, 10-305420, A Japanese Patent No. 3076179

  The adhesive tape includes, for example, a base material layer formed of a vinyl chloride sheet or the like and a glue layer disposed on the base material layer. In the laser processing apparatus, in order to surely divide the wafer by ablation processing, the wafer is irradiated with the laser beam under the condition that the dividing groove from the front surface to the back surface of the wafer can be surely formed. Therefore, below or around the formed dividing groove, the glue layer of the adhesive tape is melted by the thermal effect of laser beam irradiation, and a part of the glue layer is formed on the back surface side of the device chip formed from the wafer. Stick to it.

  In this case, when the device tape is picked up from the adhesive tape, even if a treatment such as irradiating the adhesive tape with ultraviolet rays is performed, the part of the glue layer remains on the back surface side of the picked-up device chip. . Therefore, the deterioration of the quality of the device chip becomes a problem.

  The present invention has been made in view of the above problems, and an object thereof is that the adhesive layer does not adhere to the back surface side of the device chip to be formed, and the quality derived from the adhesion of the adhesive layer to the device chip is improved. It is an object of the present invention to provide a wafer processing method that does not cause deterioration.

  According to one aspect of the present invention, there is provided a wafer processing method in which a plurality of devices divides a wafer formed in each region of a surface divided by a dividing line into individual device chips, and the wafer is accommodated. Positioning a wafer in the opening of a frame having an opening, and arranging a polyolefin sheet on the back surface of the wafer and the outer periphery of the frame, a polyolefin sheet arranging step; A step of heating the system sheet to integrate the wafer and the frame through the polyolefin sheet; and a laser beam having a wavelength having an absorptivity for the wafer along the dividing line. Irradiating the wafer to form a dividing groove and dividing the wafer into individual device chips; A pickup step for picking up the individual the device chip from olefin-based sheet, the processing method of the wafer, characterized in that it comprises a are provided.

  Further, preferably, in the integration step, after the integration is carried out, the polyolefin sheet protruding from the outer periphery of the frame is removed.

  Further, preferably, in the pickup step, the polyolefin-based sheet is expanded to widen the gap between the device chips, and the device chip is pushed up from the polyolefin-based sheet side.

  Further, preferably, the polyolefin-based sheet is any 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 sheet is the polyethylene sheet, and the heating temperature is 160 when the polyolefin sheet is the polypropylene sheet. C. to 180.degree. C., and the heating temperature is 220.degree. C. to 240.degree. C. when the polyolefin sheet is the polystyrene sheet.

  Also, preferably, the wafer is made of any one of Si, GaN, GaAs, and glass.

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

  After the integration step is performed, the wafer is divided by irradiating the wafer with a laser beam having a wavelength having an absorptivity for the wafer and forming a division groove along the division line by ablation. Then, the device chip is picked up from the polyolefin sheet. The picked-up device chips are respectively mounted on predetermined mounting targets.

  When the ablation process is performed on the wafer, heat generated by the irradiation of the laser beam is transferred to the polyolefin sheet below and near the dividing groove. However, since the polyolefin sheet does not have a glue layer, the glue layer does not melt and stick to the back surface side of the device chip.

  That is, according to one aspect of the present invention, since the frame unit can be formed using the polyolefin-based sheet that does not have a glue layer, an adhesive tape having a glue layer is unnecessary, and as a result, a device caused by the adhesion of the glue layer No deterioration of chip quality occurs.

  Therefore, according to one aspect of the present invention, there is provided a wafer processing method in which the glue layer does not adhere to the back surface side of the device chip to be formed, and the deterioration in quality due to the adhesion of the glue layer to the device chip does not occur. .

It is a perspective view which shows a wafer typically. It is a perspective view which shows typically a mode that a wafer and a frame are positioned on the holding surface of a chuck table. It is a perspective view which shows the polyolefin sheet | seat arrangement process typically. It is a perspective view which shows an example of an integrated process typically. 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. It is a perspective view which shows a dividing process typically. It is a perspective view which shows typically the carrying in of the frame unit to a pick-up apparatus. FIG. 8A is a cross-sectional view schematically showing the frame unit fixed on the frame support base, and FIG. 8B is a cross-sectional view schematically showing the pickup process.

  An embodiment according to an aspect of the present invention will be described with reference to the accompanying drawings. First, a wafer processed by the wafer processing method according to this embodiment will be described. FIG. 1 is a perspective view schematically showing the wafer 1.

  The wafer 1 is made of, for example, Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor material, or sapphire, glass, quartz, or other material. The substrate is a substantially disk-shaped substrate or the like. The glass is, for example, alkali glass, non-alkali glass, soda-lime glass, lead glass, borosilicate glass, quartz glass, or the like.

  The front surface 1a of the wafer 1 is partitioned by a plurality of planned dividing lines 3 arranged in a grid pattern. In addition, devices 5 such as ICs, LSIs, LEDs, etc. are formed in each area of the front surface 1a of the wafer 1 divided by the planned dividing line 3. In the method of processing the wafer 1 according to the present embodiment, a dividing groove is formed in the wafer 1 along the dividing line 3 by ablation processing to divide the wafer 1 to form individual device chips.

  Before loading the wafer 1 into the laser processing apparatus 8 (see FIG. 6) in which ablation processing is performed, the wafer 1, the polyolefin-based sheet, and the frame are integrated to form a frame unit. The wafer 1 is carried into the laser processing apparatus in the state of the frame unit and processed. The formed individual device chips are supported by the polyolefin sheet. Then, the polyolefin-based sheet is expanded to widen the space between the device chips, and the device chips are picked up by a pickup device.

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

  The polyolefin-based sheet 9 (see FIG. 3 and the like) is a flexible resin-based sheet and has flat front and back surfaces. The polyolefin-based sheet 9 has a diameter larger than the outer diameter of the frame 7 and does not include a glue layer. The polyolefin sheet 9 is a sheet of a polymer synthesized by using an alkene as a monomer, and is a sheet which is 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 adhesiveness, it cannot be attached to the wafer 1 and the frame 7 at room temperature. However, since the polyolefin-based sheet 9 has thermoplasticity, when it is heated to a temperature near the melting point while being bonded to the wafer 1 and the frame 7 while applying a predetermined pressure, it partially melts and the wafer 1 and the frame 7 are melted. Can be glued to. Therefore, in the method for processing the wafer 1 according to the present embodiment, the wafer 1, the frame 7, and the polyolefin-based sheet 9 are integrated by heating as described above to form a frame unit.

  Next, each step of the method for processing the wafer 1 according to this embodiment will be described. First, in order to prepare to integrate the wafer 1, the polyolefin-based sheet 9 and the frame 7, a polyolefin-based sheet disposing step is performed. FIG. 2 is a perspective view schematically showing how the wafer 1 and the frame 7 are positioned on the holding surface 2 a of the chuck table 2. As shown in FIG. 2, the polyolefin sheet arranging step is performed on the chuck table 2 having the holding surface 2a on the upper portion.

  The chuck table 2 includes a porous member having a diameter larger than the outer diameter of the frame 7 at the center of the upper portion. The upper surface of the porous member serves as 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 communicates with the porous member, and a suction source 2b is arranged on the other end side of the exhaust passage. A switching unit 2c for switching between a communication state and a disconnection state is arranged in the exhaust passage, and when the switching unit 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. The pressure acts and the held object is suction-held on the chuck table 2.

  In the polyolefin sheet arranging step, 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 in the opening 7 a of the frame 7 with the front surface 1 a side of the wafer 1 facing downward. Next, the polyolefin sheet 9 is provided on the back surface 1b of the wafer 1 and the outer periphery of the frame 7. FIG. 3 is a perspective view schematically showing the polyolefin sheet arranging step. As shown in FIG. 3, a polyolefin-based sheet 9 is provided on both the wafer 1 and the frame 7 so as to cover them.

  In the polyolefin sheet arranging step, the polyolefin sheet 9 having a diameter larger than that of the holding surface 2a of the chuck table 2 is used. When the negative pressure by the chuck table 2 is applied to the polyolefin-based sheet 9 in the integration step to be performed later, the negative pressure will leak from the gap unless the entire holding surface 2a is covered with the polyolefin-based sheet 9. This is because pressure cannot be applied to the polyolefin sheet 9 properly.

  In the method for processing the wafer 1 according to the present embodiment, next, the polyolefin sheet 9 is heated by applying hot air to the polyolefin sheet 9, and the wafer 1 and the frame 7 are integrated via the polyolefin sheet 9. The integration process is performed. FIG. 4 is a perspective view schematically showing an example of the integration process. In FIG. 4, what is visible through the polyolefin-based sheet 9 that is transparent or translucent 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 in which the suction source 2b is connected to the porous member above the chuck table 2, and the negative pressure by 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 by the atmospheric pressure.

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

  The heat gun 4 includes a heating unit such as a heating wire and a blower mechanism such as a fan inside, and can heat and inject air. While applying a negative pressure to the polyolefin-based sheet 9, the heat gun 4 supplies hot air 4a from the upper surface to the polyolefin-based sheet 9 to heat the polyolefin-based sheet 9 to a predetermined temperature. It is thermocompression bonded.

  After thermocompression-bonding the polyolefin-based sheet 9, the switching portion 2c is operated to release the communication state between the porous member of the chuck table 2 and the suction source 2b, and the adsorption 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. 5A 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. The cutter 6 is provided with a through hole and is rotatable about a rotation shaft that is penetrated by the through hole.

  First, the annular cutter 6 is positioned above the frame 7. At this time, the rotating shaft of the cutter 6 is aligned with the radial direction of the chuck table 2. Next, the cutter 6 is lowered to sandwich the polyolefin sheet 9 between the frame 7 and the cutter 6, and the polyolefin sheet 9 is cut. Then, a cut mark 9a is formed on the polyolefin sheet 9.

  Further, the cutter 6 is made to go around the opening 7a of the frame 7 along the frame 7, and a predetermined area of the polyolefin sheet 9 is surrounded by a cutting mark 9a. Then, the polyolefin sheet 9 in the region on the outer peripheral side of the cut mark 9a is removed so that the region of the polyolefin sheet 9 is left. Then, an unnecessary portion of the polyolefin-based 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 for vibrating the annular cutter 6 at the ultrasonic band frequency may be connected to the cutter 6. When the polyolefin-based sheet 9 is cut, the polyolefin-based sheet 9 may be cooled and cured to facilitate the cutting. As described above, the frame unit 11 in which the wafer 1 and the frame 7 are integrated via the polyolefin sheet 9 is formed. FIG. 5B is a perspective view schematically showing the formed frame unit 11.

  When carrying out the integration step, 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-based sheet 9 may melt and the sheet shape may not be maintained. The polyolefin sheet 9 is preferably heated to a temperature equal to or higher than its softening point. This is because the integration process cannot be properly performed unless the heating temperature reaches the softening point. That is, it is preferable that the polyolefin sheet 9 is heated to a temperature equal to or higher than its softening point and equal to or lower than its melting point.

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

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

  Here, the heating temperature refers to the temperature of the polyolefin-based sheet 9 when performing the integration step. For example, as a heat source such as a heat gun 4, a model capable of setting an output temperature has been put into practical use. 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 wafer processing method according to the present embodiment, the wafer 1 in the state of the frame unit 11 is subjected to ablation processing to form a division groove along the division line 3 to divide the wafer 1. Carry out the process. The dividing step is performed by, for example, the laser processing apparatus shown in FIG. FIG. 6 is a perspective view schematically showing the dividing step.

  The laser processing device 8 includes a laser processing unit 10 that ablates the wafer 1, and a chuck table (not shown) that holds the wafer 1. The laser processing unit 10 includes a laser oscillator (not shown) that can oscillate a laser, and can emit a laser beam 12 having a wavelength that has an absorptivity for the wafer 1 (a wavelength that the wafer 1 can absorb). The chuck table can be moved (working feed) along a direction parallel to the upper surface.

  The laser processing unit 10 irradiates the wafer 1 held on the chuck table with a laser beam 12 emitted from the laser oscillator. The processing head 10 a included in the laser processing unit 10 has a mechanism for focusing the laser beam 12 on the wafer 1 at a predetermined height position.

  When the wafer 1 is ablated, 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 planned dividing line 3 of the wafer 1 with the processing feed direction of the laser processing device 8. Further, the relative positions of the chuck table and the laser processing unit 10 are adjusted so that the processing head 10a is arranged above the extension line of the planned dividing line 3.

  Next, while irradiating the laser beam 12 onto the wafer 1 from the laser processing unit 10, the chuck table and the laser processing unit 10 are relatively moved along a processing feed direction parallel to the upper surface of the chuck table. Then, the wafer 1 is irradiated with the laser beam 12 along the planned dividing line 3, and the dividing groove 3 a along the planned dividing line 3 is formed in the wafer 1 by ablation.

The irradiation conditions of the laser beam 12 in the dividing step are set as follows, for example. However, the irradiation condition of the laser beam 12 is not limited to this.
Wavelength: 355nm
Repetition frequency: 50kHz
Average output: 5W
Feed rate: 200 mm / sec

  After performing the ablation process along one planned dividing line 3, the chuck table and the laser processing unit 10 are moved relatively in the indexing feeding direction perpendicular to the machining feeding direction, and along the other planned dividing line 3. Similarly, the ablation process of the wafer 1 is performed. After forming the dividing grooves 3a along all the dividing lines 3 along one direction, the chuck table is rotated around an axis perpendicular to the holding surface, and along the dividing lines 3 along the other direction. Then, the wafer 1 is similarly ablated.

  When the wafer 1 is ablated along all the planned dividing lines 3 of the wafer 1, the dividing step is completed. When the dividing step is completed and the dividing grooves 3a extending from the front surface 1a to the rear surface 1b along all the planned dividing lines 3 are formed on the wafer 1, the wafer 1 is divided and individual device chips are formed.

  When the ablation processing is performed on the wafer 1 by the laser processing unit 10, processing waste derived from the wafer 1 is generated from the irradiation target portion of the laser beam 12, and the processing scrap is scattered around the irradiation target portion and the wafer 1 Adheres to the surface 1a. Even if the surface 1a of the wafer 1 is cleaned by the cleaning unit described below after the wafer 1 is subjected to the ablation process, it is not easy to completely remove the attached processing waste. If the processing waste remains on the device chip formed from the wafer 1, the quality of the device chip deteriorates.

  Therefore, a water-soluble liquid resin that functions as a protective film that protects the surface 1a of the wafer 1 may be previously applied to the surface 1a of the wafer 1 that is ablated by the laser processing device 8. When the liquid resin is applied to the front surface 1a of the wafer 1, the processing scraps scattered during the ablation process adhere to the upper surface of the liquid resin, so that the processing wastes do not directly adhere to the front surface 1a of the wafer 1. . Then, the processing waste is removed together with the liquid resin by the cleaning unit described next.

  The laser processing device 8 may include a cleaning unit (not shown). In this case, the wafer 1 ablated by the laser processing unit 10 is transferred 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 a cleaning liquid such as pure water from the cleaning water supply nozzle to the wafer 1, the cleaning water supply nozzle is horizontally moved along a path passing above the center of the holding surface. When the wafer 1 is reciprocally moved, the front surface 1a side of the wafer 1 can be cleaned.

  In the method for processing the wafer 1 according to the present embodiment, next, a pickup step of picking up the individual device chips from the polyolefin sheet 9 is carried out. In the pickup process, the pickup device 14 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 14.

  The pickup device 14 includes a cylindrical drum 16 having a diameter larger than the diameter of the wafer 1, and a frame holding unit 18 including a frame support base 22. The frame support base 22 of the frame holding unit 18 is provided with an opening having a diameter larger than the diameter of the drum 16, and is arranged at the same height as the upper end of the drum 16, and the upper end of the drum 16 is located on the outer peripheral side. Surround from.

  The clamp 20 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 clamp 7 holds the frame 7 of the frame unit 11, the frame unit 11 is fixed to the frame support base 22.

  The frame support base 22 is supported by a plurality of rods 24 extending in the vertical direction, and an air cylinder 26 for raising and lowering the rods 24 is arranged at the lower end of each rod 24. The plurality of air cylinders 26 are supported by a disc-shaped base 28. When each air cylinder 26 is operated, the frame support base 22 is pulled down with respect to the drum 16.

  Inside the drum 16, a push-up mechanism 30 that pushes up the device chip supported by the polyolefin sheet 9 from below is disposed. Further, a collet 32 (see FIG. 8B) capable of sucking and holding the device chip is arranged above the drum 16. The push-up mechanism 30 and the collet 32 are movable in the horizontal direction along the upper surface of the frame support base 22. Further, the collet 32 is connected to the suction source 32a (see FIG. 8B) via the switching unit 32b (see FIG. 8B).

  In the pickup process, first, the height of the frame support 22 is adjusted by operating the air cylinder 26 so that the height of the upper end of the drum 16 of the pickup device 14 and the height of the upper surface of the frame support 22 match. To do. Next, the frame unit 11 carried out from the laser processing device 8 is placed on the drum 16 and the frame support base 22 of the pickup device 14.

  Then, the frame 7 of the frame unit 11 is fixed onto the frame support base 22 by the clamp 20. FIG. 8A is a sectional view schematically showing the frame unit 11 fixed on the frame support base 22. The wafer 1 is divided by forming a dividing groove 3a in the dividing step.

  Next, the air cylinder 26 is operated to pull down the frame support base 22 of the frame holding unit 18 with respect to the drum 16. Then, as shown in FIG. 8B, the polyolefin sheet 9 is expanded in the outer peripheral direction. FIG. 8B is a cross-sectional view schematically showing the pickup process.

  When the polyolefin sheet 9 is expanded in the outer peripheral direction, the intervals between the device chips 1c supported by the polyolefin sheet 9 are widened. Then, the device chips 1c are less likely to come into contact with each other, and the individual device chips 1c can be easily picked up. Then, the device chip 1c to be picked up is determined, the push-up mechanism 30 is moved below the device chip 1c, and the collet 32 is moved above the device chip 1c.

  Then, the push-up mechanism 30 is operated to push up the device chip 1c from the polyolefin sheet 9 side. Then, the switching unit 32b is operated to communicate the collet 32 with the suction source 32a. Then, the device chip 1c is suction-held by the collet 32, and the device chip 1c is picked up from the polyolefin sheet 9. The individual device chips 1c thus picked up are then mounted on a predetermined wiring board or the like for use.

  For example, when the frame unit 11 is formed using an adhesive tape, heat generated by irradiation of the laser beam 12 in the dividing step is transferred to the adhesive tape, and the glue layer of the adhesive tape is melted and fixed to the back surface side of the device chip. To do. Then, the deterioration of the quality of the device chip due to the adhesion of the glue layer becomes a problem.

  On the other hand, according to the wafer processing method of the present embodiment, it is possible to form a frame unit using a polyolefin-based sheet that does not have a glue layer by thermocompression bonding, and thus an adhesive tape having a glue layer is unnecessary. Is. As a result, the quality of the device chip does not deteriorate due to the adhesion of the glue layer on the back surface side.

  It should be noted that the present invention is not limited to the description of the above embodiment, and can be implemented with various modifications. For example, although the case where the polyolefin sheet 9 is, for example, a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet has been described in the above embodiment, one aspect of the present invention is not limited to this. For example, other materials may be used for the polyolefin sheet, and a copolymer of propylene and ethylene, an olefin elastomer, or the like may be used.

  In addition, the structures, methods, and the like according to the above-described embodiments can be appropriately modified and implemented without departing from the scope of the object of the invention.

1 Wafer 1a Front surface 1b Back surface 3 Divided line 3a Divided groove 5 Device 7 Frame 7a Opening 9 Polyolefin sheet 9a Cutting mark 11 Frame unit 2 Chuck table 2a Holding surface 2b, 32a Suction source 2c, 32b Switching part 4 Heat gun 4a Hot air 6 Cutter 8 Laser processing device 10 Laser processing unit 10a Processing head 12 Laser beam 14 Pickup device 16 Drum 18 Frame holding unit 20 Clamp 22 Frame support stand 24 Rod 26 Air cylinder 28 Base 30 Push up mechanism 32 Collet

Claims (6)

A method of processing a wafer, wherein a plurality of devices divides a wafer formed in each region of the surface divided by a dividing line into individual device chips,
Positioning the wafer in the opening of the frame having an opening to accommodate the wafer, a polyolefin-based sheet disposing step of disposing a polyolefin-based sheet on the back surface of the wafer and the outer periphery of the frame,
An integrated step of applying hot air to the polyolefin-based sheet to heat the polyolefin-based sheet to integrate the wafer and the frame via the polyolefin-based sheet;
A dividing step of irradiating the wafer with a laser beam having a wavelength having an absorptivity for the wafer along the dividing line to form dividing grooves and dividing the wafer into individual device chips;
A pickup step of picking up the individual device chips from the polyolefin sheet,
A method for processing a wafer, comprising:   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.   2. The method of processing a wafer according to claim 1, wherein, in the pick-up step, the polyolefin sheet is expanded to widen a space between the device chips, and the device chip is pushed up from the polyolefin sheet side.   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, the heating temperature is 120 ° C to 140 ° C when the polyolefin sheet is the polyethylene sheet, and the heating temperature is 160 ° C to 180 ° C when the polyolefin sheet is the polypropylene sheet. The wafer processing method according to claim 4, wherein the heating temperature is 220 ° C. to 240 ° C. when the polyolefin sheet is the polystyrene sheet.   The wafer processing method according to claim 1, wherein the wafer is made of any one of Si, GaN, GaAs, and glass.