JP2020043148A - 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 on a surface into individual device chips comprises a polyester-based sheet arranging step, an integrating step, a frame supporting step, a dividing step, and a picking-up step. The polyester-based sheet arranging step arranges a polyester-based sheet on a rear surface of the wafer. The integrating step heats the polyester-based sheet and integrates the wafer and the polyester-based sheet by thermal compression bond. The frame supporting step supports the polyester-based sheet by a frame composed of a first frame including an opening and a plurality of magnets and a second frame including an opening by holding an outer periphery of the polyester-based sheet between the first frame and the second frame by a magnetic force using the frame. The dividing step divides the wafer into individual device chips by cutting the wafer. The picking-up step applies ultrasonic waves to the polyester-based sheet and pushes up the device chip.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a wafer processing method that divides a wafer formed in each region of a surface where a plurality of devices are partitioned by a planned dividing line into individual devices.

  In a manufacturing process of a device chip used for an electronic device such as a mobile phone or a personal computer, first, a plurality of intersecting dividing lines (streets) are set on the surface of a wafer made of a material such as a semiconductor. Then, a device such as an IC (Integrated Circuit) or an LSI (Large-scale Integrated circuit) is formed in each area partitioned by the planned dividing line.

  Thereafter, an adhesive tape called dicing tape, which is attached to an annular frame having an opening to cover the opening, is attached to the back surface of the wafer, and the wafer, the adhesive tape, and the annular frame are integrally formed. To form a frame unit. Then, when the wafer included in the frame unit is processed and divided along the dividing line, individual device chips are formed.

  For dividing the wafer, for example, a cutting device is used. 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 having an annular grindstone portion, and a spindle that is inserted into 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 cutting blade by rotating the spindle, and raise the cutting unit to a predetermined height. Lower to position. Then, the chuck table and the cutting unit are relatively moved along a direction parallel to the upper surface of the chuck table, and the cutting blade cuts the wafer along the dividing line. Then, the wafer is divided.

  Thereafter, the frame unit is carried out of the cutting device, and a process such as irradiating the adhesive tape with ultraviolet light is performed to reduce the adhesive force of the adhesive tape, and a device chip is picked up. As a processing device having a high production efficiency of device chips, a cutting device capable of continuously performing wafer division and irradiation of an adhesive tape with ultraviolet light 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 layer and a glue layer disposed on the base layer. In the cutting apparatus, 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 to surely divide the wafer. Therefore, the cutting blade for cutting the wafer also cuts the adhesive layer of the adhesive tape. Therefore, when cutting the wafer, cutting chips derived from the glue layer are generated together with cutting chips derived from the wafer.

  When cutting the wafer, a cutting fluid is supplied to the wafer and the cutting blade, and the cutting chips generated by the cutting are taken into the cutting fluid and diffused to the surface of the wafer. Here, the cutting debris derived from the glue layer easily adheres to the surface of the device, and is not easy to remove in a subsequent wafer cleaning step or the like. For this reason, if cutting chips derived from the glue layer adhere, there is a problem that the quality of the device chip deteriorates.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a method of processing a wafer in which cutting chips do not adhere to the surface of a device and a decrease in device chip quality is suppressed. That is.

  According to one aspect of the present invention, there is provided a method of processing a wafer in which a plurality of devices divides a wafer formed in each region of a surface divided by a division line into individual device chips, A polyester sheet arranging step of arranging a polyester sheet, an integrating step of heating the polyester sheet, and integrating the wafer and the polyester sheet by thermocompression bonding; and Before or after, 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 are configured. Using a frame, an outer peripheral portion of the polyester-based sheet is held between the first frame and the second frame by a magnetic force generated by the magnet. A frame supporting step of supporting the polyester-based sheet with the frame, and cutting the wafer along a predetermined dividing line using a cutting device rotatably provided with a cutting blade to divide the wafer into individual device chips. The dividing step and applying ultrasonic waves to the polyester sheet in individual regions corresponding to each device chip of the polyester sheet, pushing up the device chip from the polyester sheet side, and And a pickup step of picking up a device chip.

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

  Also, preferably, in the pickup step, the polyester-based sheet is expanded to increase the interval between each device chip.

  Preferably, the polyester-based sheet is either a polyethylene terephthalate sheet or a polyethylene naphthalate sheet.

  More preferably, in the integration step, when the polyester-based sheet is the polyethylene terephthalate sheet, the heating temperature is 250 ° C. to 270 ° C., and when the polyester-based sheet is the polyethylene naphthalate sheet, heating is performed. The temperature is between 160C and 180C.

  Preferably, the wafer is made of any of Si, GaN, GaAs, and glass.

  In the wafer processing method according to one embodiment of the present invention, the frame and the wafer are integrated using a polyester-based sheet having no adhesive layer without using an adhesive tape having an adhesive layer in a frame unit. The integration step for integrating the polyester sheet and the wafer is realized by thermocompression bonding.

  The method for processing a wafer according to one embodiment of the present invention includes a first frame having an opening large enough to accommodate a wafer, and a second frame having an opening large enough to accommodate a 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 a magnetic force generated by the magnet.

  Then, in the frame supporting step, a polyester-based sheet is disposed between the first frame and the second frame, and is sandwiched between the first frame and the second frame. The polyester sheet can be supported by the frame.

  That is, even if the polyester sheet does not include the glue layer, by performing the integration step and the frame supporting step, the wafer, the polyester sheet, and the frame can be integrated to form a frame unit. .

  Thereafter, the wafer is cut by a cutting blade to divide the wafer into individual device chips. Thereafter, in each area of the polyester sheet corresponding to each device chip, ultrasonic waves are applied to the polyester sheet, the device chip is pushed up from the polyester sheet side, and the device chip is picked up from the polyester sheet. Each of the picked-up device chips is mounted on a predetermined mounting target. When ultrasonic waves are applied to the polyester-based sheet at the time of pickup, the polyester-based sheet is easily peeled off, so that the load on the device chip can be reduced.

  When the wafer is cut, the cutting blade cuts into the polyester sheet below the wafer, so that cutting chips derived from the polyester sheet are generated. However, since the polyester-based sheet does not have a glue layer, even if the cutting chips are taken up by the cutting water and diffused on the surface of the wafer, the cutting chips do not adhere to the wafer, and after a subsequent cleaning step, etc. Removed reliably.

  That is, according to one aspect of the present invention, it is possible to form a frame unit using a polyester-based sheet having no glue layer. Is suppressed.

  Therefore, according to one embodiment of the present invention, there is provided a method of processing a wafer in which cutting chips do not adhere to the surface of a device and deterioration of device chip quality is suppressed.

It is a perspective view which shows a wafer typically. It is a perspective view which shows typically a mode that a wafer is positioned on the holding surface of a chuck table. It is a perspective view which shows the polyester type | system | group sheet installation process typically. It is a perspective view which shows an example of an integration process typically. It is a perspective view which shows an example of an integration process typically. It is a perspective view which shows an example of an integration process typically. FIG. 7A is a perspective view schematically showing a frame supporting step, and FIG. 7B is a perspective view schematically showing a formed frame unit. It is a perspective view which shows a division | segmentation process typically. It is a perspective view which shows typically carrying in of a frame unit to a pickup apparatus. FIG. 10A is a cross-sectional view schematically illustrating a frame unit fixed on a frame support, and FIG. 10B is a cross-sectional view schematically illustrating 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. The wafer 1 is made of, for example, a material such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or another semiconductor, or a material such as sapphire, glass, or quartz. And a substantially disk-shaped substrate.

  The surface 1a of the wafer 1 is divided by a plurality of scheduled dividing lines 3 arranged in a lattice. Further, devices 5 such as an IC (Integrated Circuit) and an LED (Light Emitting Diode) are formed in each area of the front surface 1a of the wafer 1 divided by the dividing lines 3. In the method for processing the wafer 1 according to the present embodiment, individual device chips are formed by cutting and dividing the wafer 1 along the planned dividing line 3.

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

  The annular frame 7 (see FIGS. 7A and 7B) includes, for example, a first frame 7a formed of a material such as a metal and 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 an upper surface 7c. Also, a plurality of magnets 7e are embedded and disposed on 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. When the first frame 7a and the second frame 7f are overlapped with each other, the pin 7d of the first frame 7a is fitted into the through hole 7i so that the through-hole of the second frame 7f can be fitted. 7i is formed with the number, position and size corresponding to the pins 7d of the first frame 7a.

  The polyester-based sheet 9 (see FIG. 3 and the like) is a flexible resin-based sheet and has flat front and back surfaces. And it has a diameter larger than the outer diameter of the frame 7 and does not have a glue layer. The polyester sheet 9 is a polymer sheet synthesized using dicarboxylic acid (a compound having two carboxyl groups) and a diol (a compound having two hydroxyl groups) as monomers. For example, a polyethylene terephthalate sheet or And a sheet transparent or translucent to visible light, such as a polyethylene naphthalate sheet. However, the polyester sheet 9 is not limited to this, and may be opaque.

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

  In the method for processing the wafer 1 according to the present embodiment, the polyester sheet 9 is bonded to the back surface 1b side of the wafer 1 by thermocompression bonding, and the outer periphery of the polyester sheet 9 is bonded to the first frame 7a and the second frame 7f. To form a frame unit.

  Next, each step of the method for processing the wafer 1 according to the present embodiment will be described. First, in preparation for integrating the wafer 1 and the polyester sheet 9, a polyester 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 polyester sheet arranging step is performed on the chuck table 2 having the holding surface 2a on the upper side.

  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 exhaust passage inside at one end communicating 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 unit 2c for switching between a communicating state and a disconnected state. When the switching unit 2c is in the communicating state, a negative force generated by the suction source 2b on the held object placed on the holding surface 2a. The pressure acts, and the object to be held is suction-held on the chuck table 2.

  In the polyester sheet disposing step, first, the wafer 1 is placed on the holding surface 2a of the chuck table 2 as shown in FIG. At this time, the surface 1a side of the wafer 1 is turned downward. Next, the polyester sheet 9 is disposed on the back surface 1b of the wafer 1. FIG. 3 is a perspective view schematically showing a polyester sheet disposing step. As shown in FIG. 3, a polyester sheet 9 is disposed on the wafer 1 so as to cover the wafer 1.

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

  In the method for processing the wafer 1 according to the present embodiment, next, an integration step of heating the polyester sheet 9 and integrating the wafer 1 and the polyester sheet 9 by thermocompression bonding is performed. FIG. 4 is a perspective view schematically showing an example of the integration step. In FIG. 4, what can be visually recognized through a polyester sheet 9 that is transparent or translucent to visible light is indicated by broken lines.

  In the integration step, first, the switching unit 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 from the suction source 2b is applied to the polyester-based sheet 9. Let it work. Then, the polyester sheet 9 comes into close contact with the wafer 1 due to the atmospheric pressure.

  Next, the polyester sheet 9 is heated while sucking the polyester sheet 9 by the suction source 2b, and thermocompression bonding is performed. For heating the polyester sheet 9, for example, as shown in FIG. 4, an infrared lamp 4 arranged above the chuck table 2 is used. The infrared lamp 4 is capable of irradiating infrared rays 4a having a wavelength at which the material of the polyester sheet 9 has absorptivity.

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

  The heating of the polyester-based sheet 9 may be performed by another method. FIG. 5 is a perspective view schematically showing another example of the integration process. In FIG. 5, what can be visually recognized through a polyester sheet 9 that is transparent or translucent to visible light is indicated by broken lines. The integration process shown in FIG. 5 is performed by the heat gun 6 disposed above the chuck table 2.

  The heat gun 6 includes a heating means such as a heating wire and a blower mechanism such as a fan therein, and can heat and jet air. While applying a negative pressure from the suction source 2 b to the polyester sheet 9, hot air 6 a is supplied to the polyester sheet 9 from the upper surface by the heat gun 6 and the polyester sheet 9 is heated to a predetermined temperature. Thermocompression bonding.

  The heating of the polyester-based sheet 9 may be performed by 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, what can be visually recognized through the polyester sheet 9 that is transparent or translucent to visible light is indicated by broken lines.

  In the integration step shown in FIG. 6, for example, a heat roller 8 having a heat source inside is used. In the integration step shown in FIG. 6 as well, first, a negative pressure from the suction source 2b is applied to the polyester sheet 9 to bring the polyester sheet 9 into close contact with the wafer 1 by atmospheric pressure.

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

  Alternatively, the polyester sheet 9 may be thermocompression-bonded by using an iron-shaped pressing member having a heat source therein and having a flat bottom plate in place of the heat roller 8. In this case, the pressing member is heated to a predetermined temperature to form a hot plate, and the polyester sheet 9 held on the chuck table 2 is pressed from above by the pressing member.

  When the polyester sheet 9 is heated to a temperature near its melting point by any method, the polyester sheet 9 is thermocompression-bonded to the wafer 1. After thermocompression bonding of the polyester sheet 9, the switching member 2c is operated to separate the porous member of the chuck table 2 from the suction source 2b and release the suction by the chuck table 2.

  When performing the thermocompression bonding, the polyester-based sheet 9 is preferably heated to a temperature equal to or lower than its melting point. If the heating temperature exceeds the melting point, the polyester sheet 9 may be melted and the shape of the sheet may not be maintained. Further, the polyester-based sheet 9 is preferably heated to a temperature higher than its softening point. This is because thermocompression bonding cannot be properly performed unless the heating temperature has reached the softening point. That is, the polyester sheet 9 is preferably heated to a temperature higher than its softening point and lower than its melting point.

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

  Further, for example, when the polyester-based sheet 9 is a polyethylene terephthalate sheet, the heating temperature is set to 250 ° C to 270 ° C. When the polyester sheet 9 is a polyethylene naphthalate sheet, the heating temperature is set to 160 ° C to 180 ° C.

  Here, the heating temperature refers to the temperature of the polyester sheet 9 at the time of performing the integration step. For example, in the heat sources such as the infrared lamp 4, the heat gun 6, the heat roller 8, etc., models capable of setting the output temperature are practically used. However, even if the polyester sheet 9 is heated using the heat source, the polyester sheet may be heated. 9 may not reach the set output temperature. Then, in order to heat the polyester sheet 9 to a predetermined temperature, the output temperature of the heat source may be set higher than the melting point of the polyester sheet 9.

  In the method for processing the wafer 1 according to the present embodiment, before or after the integration step, a frame supporting step of supporting the polyester sheet 9 with the frame 7 is performed. FIG. 7A is a perspective view schematically showing a frame supporting step. In the frame supporting step, the outer periphery of the polyester-based sheet 9 is sandwiched between the first frame 7a and the second frame 7f, and the polyester-based sheet 9 is supported by the frame 7.

  First, the polyester sheet 9 is placed on the upper surface 7c of the first frame 7a. At this time, the position of the polyester sheet 9 is determined so as to cover all the openings 7b of the first frame 7a. Next, the second frame 7f is placed on the polyester 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 holes 7i of the second frame 7f are fitted into the pins 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 provided in the first frame 7a acts to draw the two frames together, so that the outer peripheral portion of the polyester-based sheet 9 It is sandwiched between both frames. Therefore, the polyester sheet 9 is supported by the frame 7. At this time, since the pins 7d of the first frame 7a are fitted into the through holes 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 the case where the frame supporting step is performed after the integration step has been described, the method of processing a wafer according to the present embodiment is not limited to this. For example, the integration step may be performed after the frame supporting step. In this case, the outer periphery of the polyester sheet 9 is adhered to the first frame 7a and the second frame 7f by the heating in the integration step, and the polyester sheet 9 is supported by the frame 7 with a stronger force.

  Next, in the method for processing the wafer 1 according to the present embodiment, a dividing 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 performed by, for example, a cutting device shown in FIG. FIG. 8 is a perspective view schematically showing the dividing step.

  The cutting device 10 includes a cutting unit 12 for cutting a workpiece, and a chuck table (not shown) for holding the workpiece. The cutting unit 12 includes a cutting blade 16 having an annular grindstone portion, and a spindle (not shown) for rotating the cutting blade 16 by penetrating the tip side through a central through hole of the cutting blade 16. The cutting blade 16 includes, for example, an annular base provided with the through hole at the center, and an annular grindstone portion provided on the outer peripheral portion of the annular base.

  The proximal end side of the spindle is connected to a spindle motor (not shown) housed inside a spindle housing 14, and the cutting blade 16 can be rotated by operating the spindle motor.

  When the workpiece is cut by the cutting blade 16, heat is generated due to friction between the cutting blade 16 and the workpiece. When the workpiece is cut, cutting chips are generated from the workpiece. Therefore, in order to remove heat and cutting chips generated by the 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 that supplies cutting water to the cutting blade 16 and the like on a side of the cutting blade 16.

  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 polyester sheet 9. Then, the chuck table is rotated so that the dividing line 3 of the wafer 1 is aligned 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 of the planned division 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 the cutting unit 12 are relatively moved 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 the wafer 1 is cut, and cutting marks 3 a along the dividing lines 3 are formed on the wafer 1 and the polyester sheet 9.

  After cutting along one planned dividing line 3, the chuck table and the cutting unit 12 are moved in an indexing feed direction perpendicular to the processing feed direction, and the wafer 1 is similarly moved along the other planned dividing line 3. Carry out cutting. After 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 similarly along the planned dividing line 3 along the other direction. To cut the wafer 1. When the wafer 1 is cut along all the division lines 3 of the wafer 1, the division 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 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 the cleaning liquid such as pure water is supplied to the wafer 1 from the cleaning water supply nozzle, the cleaning water supply nozzle reciprocates along a path passing above the center of the holding surface. By moving, 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 polyester sheet 9. When cutting the wafer 1, the cutting unit 12 is set at a predetermined height so that the height position of the lower end of the cutting blade 16 is lower than the back surface 1 b of the wafer 1 in order to surely divide the wafer 1. Is positioned. Therefore, when the wafer 1 is cut, the polyester sheet 9 is also cut, and cutting chips originating from the polyester sheet 9 are generated.

  When an adhesive tape is used for the frame unit 11 instead of the polyester-based sheet 9, cutting chips originating from the adhesive layer of the adhesive tape are generated. In this case, the cutting chips are taken into the cutting water jetted from the cutting water supply nozzle 18 and diffused on the surface 1 a of the wafer 1. The cutting debris derived from the glue layer easily adheres to the surface of the device 5 and is not easily removed in a cleaning step of the wafer 1 performed after the cutting. When the cutting chips derived from the glue layer adhere, there is a problem that the quality of the formed device chip deteriorates.

  On the other hand, in the method for processing the wafer 1 according to the present embodiment, a polyester-based sheet 9 having no glue layer is used instead of the adhesive tape having the glue layer in the frame unit 11. Even if cutting chips originating from the polyester-based sheet 9 are generated and taken in the cutting water and diffused on the surface of the wafer, the cutting chips do not adhere to the wafer 1 and are more reliably removed in a subsequent cleaning step or the like. Is done. Therefore, a decrease in the quality of the device chip due to the cutting chips is suppressed.

  Next, in the processing method of the wafer 1 according to the present embodiment, a pickup step of picking up each device chip from the polyester-based sheet 9 is performed. In the pickup step, a pickup device 20 shown in the lower part of FIG. 9 is used. FIG. 9 is a perspective view schematically showing the loading of the frame unit 11 into the pickup device 20.

  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 26 of the frame holding unit 24 has an opening having a diameter larger than the diameter of the drum 22 and is disposed at the same height as the upper end of the drum 22. Surround from

  A clamp 28 is provided on the outer peripheral side of the frame support 26. When the frame unit 11 is placed on the frame support 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 26.

  The frame support 26 is supported by a plurality of rods 30 extending in the vertical direction. At the lower end of each rod 30, an air cylinder 32 for raising and lowering the rod 30 is provided. The plurality of air cylinders 32 are supported by a disk-shaped base 34. When each air cylinder 32 is operated, the frame support 26 is pulled down with respect to the drum 22.

  A push-up mechanism 36 that pushes up the device chips supported by the polyester-based sheet 9 from below is disposed inside the drum 22. The push-up mechanism 36 is provided at its upper end with an ultrasonic vibrator 36a composed of, for example, piezoelectric ceramics such as lead zirconate titanate (PZT), barium titanate, and lead titanate, or a quartz vibrator. A collet 38 (see FIG. 10B) that can hold the device chip by suction is provided above the drum 22. The push-up mechanism 36 and the collet 38 are movable in the horizontal direction along the upper surface of the frame support 26. The collet 38 is connected to a suction source 38a (see FIG. 10B) via a switching unit 38b (see FIG. 10B).

  In the pickup step, first, the air cylinder 32 is operated to lower the height of the frame support 26 so that the height of the upper end of the drum 22 of the pickup device 20 substantially matches the height of the upper surface of the frame support 26. Adjust. For example, the height position of the upper surface of the frame support 26 may be positioned lower than the upper end of the drum 22 by the thickness of the first frame 7a. Next, the frame unit 11 carried out of 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 on the frame support 26 by the clamp 28. FIG. 10A is a cross-sectional view schematically illustrating the frame unit 11 fixed on the frame support 26. The wafer 1 is divided by the cutting step 3a formed by the dividing step.

  Next, the air cylinder 32 is operated to lower the frame support 26 of the frame holding unit 24 with respect to the drum 22. Then, as shown in FIG. 10B, the polyester sheet 9 is expanded in the outer peripheral direction. FIG. 10B is a cross-sectional view schematically showing a pickup step.

  When the polyester sheet 9 is expanded in the outer peripheral direction, the distance between the device chips 1c supported by the polyester sheet 9 is increased. This makes it difficult for the device chips 1c to come into contact with each other, and facilitates pickup of the individual device 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 ultrasonic vibrator 36a is operated to generate vibration having a frequency in the ultrasonic band, and the ultrasonic vibrator 36a is brought into contact with a region of the polyester-based sheet 9 corresponding to the device chip 1c, and an ultrasonic wave is applied to the region. Is given. Further, the push-up mechanism 36 is operated to push up the device chip 1c from the polyester sheet 9 side. Then, the switching unit 38b is operated to allow the collet 38 to communicate with the suction source 38a. Then, the device chip 1 c is sucked and held by the collet 38, and the device chip 1 c is picked up from the polyester sheet 9. The individual device chips 1c thus picked up are then mounted on a predetermined wiring board and used.

  When ultrasonic waves are applied to the area of the polyester-based sheet 9 by the ultrasonic vibrator 36a, the polyester-based sheet 9 can be easily separated. Therefore, the load applied to the device chip when peeled from the polyester-based sheet 9 is reduced.

  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 chips originating from the adhesive layer of the adhesive tape are generated, and the cutting chips do not adhere to the device chip 1c. Therefore, the quality of the device chip 1c does not deteriorate.

  The present invention is not limited to the description of the above embodiment, and can be implemented with various modifications. For example, in the above embodiment, the case where the polyester-based sheet 9 is, for example, a polyethylene terephthalate sheet or a polyethylene naphthalate sheet has been described, but one embodiment of the present invention is not limited to this. For example, another material may be used for the polyester sheet, and a polytrimethylene terephthalate sheet, a polybutylene terephthalate sheet, a polybutylene naphthalate, 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 without departing from the scope of the object of the present invention.

DESCRIPTION OF SYMBOLS 1 Wafer 1a Front surface 1b Back surface 3 Expected division line 3a Cutting mark 5 Device 7, 7a, 7f Frame 7b, 7g Opening 7c Upper surface 7d Pin 7e Magnet 7h Lower surface 7i Through hole 9 Polyester sheet 11 Frame unit 2 Chuck table 2a Holding surface 2b, 38a Suction source 2c, 38b Switching unit 4 Infrared lamp 4a Infrared 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 Pickup device 22 Drum 24 Frame holding unit 26 Frame Support base 28 Clamp 30 Rod 32 Air cylinder 34 Base 36 Push-up mechanism 36a Ultrasonic vibrator 38 Collet

Claims (6)

A plurality of devices, a wafer processing method for dividing the wafer formed in each region of the surface divided by the dividing line into individual device chips,
A polyester sheet arranging step of arranging a polyester sheet on the back surface of the wafer,
Heating the polyester-based sheet, the wafer by thermocompression bonding, an integration step of integrating the polyester-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. And the outer peripheral portion of the polyester-based sheet is sandwiched between the first frame and the second frame by a magnetic force generated by the magnet, and the polyester-based sheet is A frame supporting step of supporting the frame,
A dividing step of cutting the wafer along a planned dividing line by using a cutting device rotatably equipped with a cutting blade to divide the wafer into individual device chips,
In each area corresponding to each device chip of the polyester sheet, ultrasonic waves are applied to the polyester sheet, the device chip is pushed up from the polyester sheet side, and the device chip is picked up from the polyester sheet. Pick-up process,
A method of processing a wafer, comprising:   2. The wafer processing method according to claim 1, wherein the thermocompression bonding is performed by irradiating infrared rays in the integration step.   2. The wafer processing method according to claim 1, wherein, in the pickup step, the polyester-based sheet is expanded to increase an interval between device chips.   2. The method according to claim 1, wherein the polyester sheet is any one of a polyethylene terephthalate sheet and a polyethylene naphthalate sheet.   In the integration step, when the polyester-based sheet is the polyethylene terephthalate sheet, the heating temperature is 250 ° C to 270 ° C, and when the polyester-based sheet is the polyethylene naphthalate sheet, the heating temperature is 160 ° C to The method according to claim 4, wherein the temperature is 180 ° C.   2. The method according to claim 1, wherein the wafer is made of any one of Si, GaN, GaAs, and glass.