JP2019201019A - Processing method of wafer - Google Patents

Abstract

To form a device chip without degrading the quality.SOLUTION: A processing method of wafer for dividing a wafer, where a plurality of devices are formed on the surface, into individual device chips comprises a polyolefin sheet disposition step for disposing a polyolefin sheet on the reverse face of the wafer, an integration step of heating the polyolefin sheet, and integrating the wafer and the polyolefin sheet by thermal compression bonding, a frame support step of supporting the polyolefin sheet by the frame, by sandwiching the outer boundary of the polyolefin sheet between the outer peripheral wall of an inner frame and the inner peripheral wall of an outer frame, by using a frame constituted of the inner frame having an opening large enough to receive the wafer, and an outer frame having an opening of such a diameter as corresponding to the outer diameter of the inner frame, a splitting step of splitting the wafer into individual device chips by cutting the wafer by using a cutting device, and a pickup process for picking up the individual 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 defined by a plurality of devices by dividing lines into individual devices.

  In the 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 division 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 Integration) is formed in each region partitioned by the division lines.

  Thereafter, an adhesive tape called a dicing tape attached to 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 planned dividing lines, individual device chips are formed.

  For example, a cutting device is used for dividing the wafer. The cutting apparatus includes a chuck table that holds a 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 pierced through a central through hole of the cutting blade and rotates the cutting blade.

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

  Thereafter, the frame unit is taken out from the cutting device, and the adhesive tape is subjected to a process such as irradiating ultraviolet rays to reduce the adhesive force of the adhesive tape, and the device chip is picked up. As a processing apparatus with high device chip production efficiency, there is known a cutting apparatus capable of continuously performing wafer division and ultraviolet irradiation on an adhesive tape with one apparatus (see Patent Document 1). The device chip picked up from the adhesive tape is mounted on a predetermined wiring board or the like.

Japanese Patent No. 3076179

  An adhesive tape contains a base material layer and the paste layer arrange | positioned on this base material layer. In the cutting apparatus, in order to reliably divide the wafer, 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. Therefore, the cutting blade for cutting the wafer also cuts the adhesive layer of the adhesive tape. Accordingly, when cutting the wafer, cutting waste derived from the glue layer is generated together with cutting waste derived from the wafer.

  When the wafer is cut, cutting fluid is supplied to the wafer and the cutting blade, but the cutting waste generated by the cutting is taken into the cutting fluid and diffused on the surface of the wafer. Here, the cutting waste derived from the glue layer is easily reattached to the surface of the device, and it is not easy to remove in a subsequent wafer cleaning process or the like. Therefore, when the cutting waste derived from the glue layer adheres, the deterioration of the quality of the device chip becomes a problem.

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

  According to one aspect of the present invention, there is provided a wafer processing method in which a plurality of devices divide a wafer formed in each region of a surface partitioned by a predetermined division line into individual device chips, on the back surface of the wafer. A polyolefin-based sheet disposing step of disposing a polyolefin-based sheet, an integration step of heating the polyolefin-based sheet, and integrating the wafer and the polyolefin-based sheet by thermocompression bonding, and Using a frame comprising an inner frame having an opening large enough to accommodate a wafer and an outer frame having an opening having a diameter corresponding to the outer diameter of the inner frame. A frame supporting step of supporting the polyolefin-based sheet with the frame by sandwiching the outer periphery of the polyolefin-based sheet between the outer peripheral wall and the inner peripheral wall of the outer frame; A dividing step of cutting the wafer along a predetermined dividing line by using a cutting device having a cutting blade rotatably, and dividing the wafer into individual device chips, and picking up the individual device chips from the polyolefin-based sheet And a picking-up process. A wafer processing method is provided.

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

  Preferably, in the pickup process, the polyolefin sheet is expanded to widen the space between the device chips, and the device chip is pushed up from the polyolefin sheet side.

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

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

  Preferably, the wafer is made of any one 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 polyolefin-based sheet that does not use an adhesive tape having a glue layer in the frame unit and does not have a glue layer. The integration process for integrating the polyolefin-based sheet and the wafer is realized by thermocompression bonding.

  In the wafer processing method according to one aspect of the present invention, a frame configured by an inner frame having an opening large enough to accommodate a wafer and an outer frame having an opening having a diameter corresponding to the outer diameter of the inner frame. Is used. In the frame supporting step, the inner frame is inserted into the opening of the outer frame, and at this time, a polyolefin sheet is sandwiched between the outer peripheral wall of the inner frame and the inner peripheral wall of the outer frame. The polyolefin sheet can be supported by a frame.

  That is, even if the polyolefin-based sheet is not provided with a glue layer, the frame unit can be formed by integrating the wafer, the polyolefin-based sheet, and the frame by performing the integration step and the frame supporting step. .

  Thereafter, the wafer is cut by a cutting blade to divide the wafer into individual device chips, and the device chips are picked up from the polyolefin-based sheet. Each picked-up device chip is mounted on a predetermined mounting target.

  When the wafer is cut, the cutting blade also cuts into the polyolefin sheet under the wafer, so that cutting waste derived from the polyolefin sheet is generated. However, since the polyolefin-based sheet does not have a glue layer, even if the cutting waste is taken into the cutting water and diffused on the surface of the wafer, the cutting waste is relatively difficult to adhere to the wafer. Moreover, even if cutting waste 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-based sheet that does not have an adhesive layer, and no cutting chips with high adhesive force are generated when a wafer is cut. The deterioration of quality is suppressed.

  Therefore, according to one aspect of the present invention, there is provided a wafer processing method in which cutting scraps are less likely to adhere to the surface of a device, and degradation 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 typically a polyolefin-type sheet | seat arrangement | positioning process. 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 the frame supporting step, and FIG. 7B is a perspective view schematically showing the 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 the frame unit to a pick-up apparatus. FIG. 10A is a cross-sectional view schematically showing the frame unit fixed on the frame support, and FIG. 10B is a cross-sectional view schematically showing the 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 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. A substantially disk-shaped substrate.

  The surface 1a of the wafer 1 is partitioned by a plurality of division lines 3 arranged in a lattice pattern. In addition, a device 5 such as an IC (Integrated Circuit) or an LED (Light Emitting Diode) is formed in each region partitioned by the division lines 3 on the surface 1a of the wafer 1. In the processing method of the wafer 1 according to the present embodiment, individual device chips are formed by cutting the wafer 1 along the division line 3 and dividing it.

  The wafer 1 is cut by a cutting device. Before the wafer 1 is carried into the cutting device, the wafer 1, the polyolefin-based sheet, and the frame are integrated to form a frame unit. The wafer 1 is carried into a cutting device in the state of a frame unit and cut. Each formed device chip is supported by a polyolefin-based sheet. Thereafter, the space between the device chips is expanded by expanding the polyolefin-based sheet, and the device chips are picked up by the pickup device.

  The annular frame 7 (see FIG. 7A, for example) is formed of a material such as metal, and corresponds to an inner frame 7c having an opening large enough to accommodate the wafer 1, and an outer diameter of the inner frame 7c. And an outer frame 7a having an opening having a diameter as described above. The inner frame 7c and the outer frame 7a have substantially the same height.

  The polyolefin-based sheet 9 (see FIG. 3 etc.) is a resin-based sheet having flexibility, and the front and back surfaces are flat. And it has a diameter larger than the outer diameter of the inner frame 7c of the frame 7, and does not have a glue layer. The polyolefin-based sheet 9 is a polymer sheet synthesized using an alkene as a monomer, and is, for example, a 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-based sheet 9 does not have adhesiveness, it cannot be attached to the wafer 1 at room temperature. However, since the polyolefin-based sheet 9 has thermoplasticity, it can be partially melted and bonded to the wafer 1 when heated to a temperature close to the melting point while being bonded to the wafer 1 while applying a predetermined pressure.

  In the processing method of the wafer 1 according to the present embodiment, the polyolefin-based sheet 9 is bonded to the back surface 1b side of the wafer 1 by thermocompression bonding, and the outer peripheral portion of the polyolefin-based sheet 9 is connected to the outer peripheral wall 7e of the inner frame 7c and the outer frame. A frame unit is formed by being sandwiched between the inner peripheral wall 7b of 7a.

  Next, each process of the processing method of the wafer 1 which concerns on this embodiment is demonstrated. First, in order to prepare for integrating the wafer 1 and the polyolefin-based sheet 9, a polyolefin-based sheet disposing step is performed. FIG. 2 is a perspective view schematically showing how the wafer 1 is positioned on the holding surface 2 a of the chuck table 2. As shown in FIG. 2, the polyolefin-based sheet disposing step is performed on the chuck table 2 having the 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 2 a of the chuck table 2. As shown in FIG. 3, the chuck table 2 has an exhaust passage having one end communicating with the porous member, and a suction source 2b is disposed on the other end side of the exhaust passage. The exhaust path is provided with a switching unit 2c that switches between a communication state and a disconnected state. When the switching unit 2c is in a communication state, negative pressure generated by the suction source 2b on an object to be held placed on the holding surface 2a. The pressure acts, and the object to be held is sucked and held on the chuck table 2.

  In the polyolefin-based 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 front surface 1a side of the wafer 1 is directed downward. Next, a polyolefin sheet 9 is disposed on the back surface 1 b of the wafer 1. FIG. 3 is a perspective view schematically showing a polyolefin-based sheet disposing step. As shown in FIG. 3, a polyolefin-based sheet 9 is disposed on the wafer 1 so as to cover the wafer 1.

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

  In the processing method of the wafer 1 according to the present embodiment, next, an integration step of heating the polyolefin sheet 9 and integrating the wafer 1 and the polyolefin sheet 9 by thermocompression is performed. FIG. 4 is a perspective view schematically showing an example of the integration process. In FIG. 4, what can be visually recognized through the polyolefin-type sheet | seat 9 which is transparent or semi-transparent with respect to visible light is shown with a broken line.

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

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

  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 thermocompression bonded to the wafer 1.

  The heating of the polyolefin-based sheet 9 may be performed by other methods. FIG. 5 is a perspective view schematically showing another example of the integration step. In FIG. 5, what can be visually recognized through the polyolefin-type sheet | seat 9 which is transparent or semi-transparent with respect to visible light is shown with a broken line. 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 heating means such as a heating wire and a blowing mechanism such as a fan inside, and can heat and inject air. When a negative pressure from the suction source 2b is applied to the polyolefin sheet 9, hot air 6a is supplied from the upper surface to the polyolefin sheet 9 by the heat gun 6, and the polyolefin sheet 9 is heated to a predetermined temperature. It is thermocompression bonded to.

  The polyolefin sheet 9 may be heated 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 step. In FIG. 6, what can be visually recognized through the polyolefin-type sheet | seat 9 which is transparent or semi-transparent with respect to visible light is shown with a broken line.

  In the integration process shown in FIG. 6, for example, a heat roller 8 having a heat source therein is used. Also in the integration step shown in FIG. 6, first, the negative pressure by the suction source 2b is applied to the polyolefin-based sheet 9, and the polyolefin-based 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 the heat roller 8 is placed on one end of the holding surface 2 a 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 the one end to the other end. Then, the polyolefin sheet 9 is thermocompression bonded to the wafer 1. At this time, when a force is applied in a direction in which the polyolefin-based sheet 9 is pushed down by the heat roller 8, thermocompression bonding is performed at a pressure larger than atmospheric pressure. In addition, it is preferable to coat the surface of the heat roller 8 with a fluororesin.

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

  When the polyolefin sheet 9 is heated to a temperature near its melting point by any method, the polyolefin sheet 9 is thermocompression bonded to the wafer 1. After thermocompression bonding of the polyolefin-based sheet 9, the switching portion 2c is operated to disconnect 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 implementing thermocompression bonding, the polyolefin-type sheet | seat 9 is preferably heated to the temperature below the melting | fusing point. This is because if the heating temperature exceeds the melting point, the polyolefin sheet 9 may be dissolved and the sheet shape may not be maintained. The polyolefin-based sheet 9 is preferably heated to a temperature equal to or higher than its softening point. This is because thermocompression bonding cannot be performed properly unless the heating temperature reaches the softening point. That is, the polyolefin sheet 9 is preferably heated to a temperature not lower than its softening point and not higher than its melting point.

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

  For example, when the polyolefin-type sheet | seat 9 is a polyethylene sheet, heating temperature shall be 120 to 140 degreeC. Moreover, when this polyolefin-type sheet | seat 9 is a polypropylene sheet, heating temperature shall be 160 to 180 degreeC. Furthermore, when the polyolefin-type sheet | seat 9 is a polystyrene sheet, heating temperature shall be 220 to 240 degreeC.

  Here, the heating temperature refers to the temperature of the polyolefin-based sheet 9 when performing the integration step. For example, a heat source such as an infrared lamp 4, a heat gun 6, a heat roller 8, etc. is available for practical use in which the output temperature can be set. Even if the polyolefin sheet 9 is heated using the heat source, the polyolefin sheet In some cases, the temperature of 9 does not reach the set output temperature. Therefore, the output temperature of the heat source may be set higher than the melting point of the polyolefin sheet 9 in order to heat the polyolefin sheet 9 to a predetermined temperature.

  In the processing method of the wafer 1 according to the present embodiment, a frame support step of supporting the polyolefin-based sheet 9 with the frame 7 is performed before or after the integration step. FIG. 7A is a perspective view schematically showing the frame supporting step. In the frame supporting step, the polyolefin sheet 9 is held between the outer peripheral wall 7e of the inner frame 7c of the frame 7 and the outer peripheral wall 7b of the outer frame 7a of the frame 7 by sandwiching the outer periphery of the polyolefin sheet 9. 7 to support.

  First, the polyolefin sheet 9 is placed on the inner frame 7c. At this time, the position of the polyolefin sheet 9 is determined so that the entire area of the upper surface of the inner frame 7 c is covered with the polyolefin sheet 9. Next, the outer frame 7 a is placed above the polyolefin-based sheet 9. At this time, the position of the outer frame 7a is determined so that the outer peripheral wall 7e of the inner frame 7c and the inner peripheral wall 7b of the outer frame 7a substantially overlap.

  Thereafter, the outer frame 7a placed above the polyolefin sheet 9 is pushed downward to accommodate the inner frame 7c in the opening of the outer frame 7a. At this time, the outer peripheral portion of the polyolefin-based sheet 9 is bent by the outer frame 7a, and is sandwiched between the outer peripheral wall 7e of the inner frame 7c and the inner peripheral wall 7b of the outer frame 7a. Then, as shown in FIG. 7B, a frame unit 11 is formed in which the wafer 1, the polyolefin sheet 9, and the frame 7 are integrated. In the frame unit 11, a polyolefin sheet 9 is disposed on the upper surface of the inner frame 7 c of the frame 7.

  In addition, although the case where a frame support process is implemented after an integration process was demonstrated, the wafer processing method which concerns on this embodiment is not limited to this. For example, the integration step may be performed after the frame support step. In this case, the portion sandwiched between the inner frame 7c and the outer frame 7a of the frame 7 of the polyolefin-based sheet 9 by heating in the integration step is the outer peripheral wall 7e of the inner frame 7c, the inner peripheral wall 7b of the outer frame 7a, The polyolefin-based sheet 9 is supported on the frame 7 with a stronger force.

  Further, the case where the polyolefin sheet 9 is arranged on the inner frame 7c of the frame 7 and the outer frame 7a is arranged thereon to perform the frame supporting process has been described. The wafer processing method according to the present embodiment Then, the inner frame 7c and the outer frame 7a may be interchanged.

  That is, the polyolefin sheet 9 may be disposed on the outer frame 7a, the inner frame 7c may be disposed thereon, and the inner frame 7c may be pressed from above to be accommodated in the opening of the outer frame 7a. In this case, in the formed frame unit, the polyolefin-based sheet 9 is in contact with the lower surface of the inner frame 7c, and the wafer 1 is disposed in the opening surrounded by the inner peripheral wall 7d of the inner frame 7c.

  Next, in the processing method of 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 by a cutting blade and divided. The dividing step is performed, for example, with a cutting apparatus shown in FIG. FIG. 8 is a perspective view schematically showing the dividing step.

  The cutting apparatus 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, and a spindle (not shown) that rotates the cutting blade 16 with its distal end passing through a central through-hole of the cutting blade 16. The cutting blade 16 includes, for example, an annular base having the through-hole at the center, and an annular grindstone portion disposed on the outer periphery of the annular base.

  The base end side of the spindle is connected to a spindle motor (not shown) housed in the 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 by friction between the cutting blade 16 and the workpiece. Further, when the workpiece is cut, cutting waste is generated from the workpiece. Therefore, in order to remove the heat and cutting waste 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 or the like on the 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 polyolefin-based sheet 9. Then, the chuck table is rotated to align the division 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 extended line of the 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 a cutting mark 3 a along the scheduled division line 3 is formed on the wafer 1 and the polyolefin sheet 9.

  After cutting along one division line 3, the chuck table and the cutting unit 12 are moved in the indexing feed direction perpendicular to the machining feed direction, and the wafer 1 is similarly cut along the other division line 3. Perform cutting. After cutting along all the division lines 3 along one direction, the chuck table is rotated around an axis perpendicular to the holding surface, and along the division lines 3 along the other direction. Then, the wafer 1 is cut. When the wafer 1 is cut along all the planned dividing lines 3 of the wafer 1, the dividing step is completed.

  The cutting apparatus 10 may include a cleaning unit (not shown) in the vicinity of 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 a cleaning liquid such as pure water is supplied from the cleaning water supply nozzle to the wafer 1, and the cleaning water supply nozzle is reciprocated along a path passing above the center of the holding surface. When moved, the surface 1a side of the wafer 1 can be cleaned.

  When the dividing step is performed, the wafer 1 is divided into individual device chips. The formed device chip is supported by the polyolefin-based sheet 9. When cutting the wafer 1, in order to divide the wafer 1 reliably, the cutting unit 12 is set to a predetermined height so that the height position of the lower end of the cutting blade 16 is lower than the back surface 1b of the wafer 1. Positioned. Therefore, when the wafer 1 is cut, the polyolefin sheet 9 is also cut, and cutting waste derived from the polyolefin sheet 9 is generated.

  When an adhesive tape is used instead of the polyolefin-based sheet 9 for the frame unit 11, cutting waste derived from the adhesive layer of the adhesive tape is generated. In this case, the cutting waste is taken into the cutting water sprayed from the cutting water supply nozzle 18 and diffused on the surface 1 a of the wafer 1. The cutting waste derived from the glue layer easily adheres to the surface of the device 5 and is not easy to remove in a cleaning step of the wafer 1 performed after cutting. When the cutting waste derived from the glue layer adheres, the quality of the device chip to be formed becomes a problem.

  On the other hand, in the processing method of the wafer 1 according to the present embodiment, not the pressure-sensitive adhesive tape having the glue layer on the frame unit 11 but the polyolefin-based sheet 9 having no glue layer is used. Even if cutting waste derived from the polyolefin-based sheet 9 is generated, taken into cutting water and diffused on the surface of the wafer, the cutting waste is relatively difficult to adhere to the wafer 1. Further, even if cutting waste adheres to the wafer 1, it is easily removed by a subsequent cleaning process or the like. Therefore, the quality degradation of the device chip due to the cutting waste is suppressed.

  In the processing method of the wafer 1 according to the present embodiment, next, a pickup process for picking up each device chip from the polyolefin-based 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 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 includes 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. Enclose from. Further, the frame support 26 has an outer diameter corresponding to the diameter of the opening of the inner frame 7 c constituting the frame 7 of the frame unit 11.

  In addition, for example, a plurality of suction holes 26 a are provided on the outer peripheral wall of the frame support 26. The frame support 26 can apply a negative pressure to the inner frame 7c of the frame 7 positioned on the outer peripheral side of the frame support 26 through the suction hole 26a. When the frame unit 11 is placed on the frame support 26 and a negative pressure is applied to the inner frame 7 c of the frame 7, the frame unit 11 is fixed to the frame support 26.

  The frame support 26 is supported by a plurality of rods 28 that extend in the vertical direction, and an air cylinder 30 that raises and lowers the rods 28 is disposed at the lower end of each rod 28. The plurality of air cylinders 30 are supported by a disk-shaped base 32. When each air cylinder 30 is operated, the frame support 26 is pulled down with respect to the drum 22.

  Inside the drum 22, a push-up mechanism 34 that pushes up a device chip supported by the polyolefin-based sheet 9 from below is disposed. Further, a collet 36 (see FIG. 10B) capable of sucking and holding the device chip is disposed above the drum 22. The push-up mechanism 34 and the collet 36 are movable in the horizontal direction along the upper surface of the frame support 26. The collet 36 is connected to the suction source 36a (see FIG. 10B) via the switching unit 36b (see FIG. 10B).

  In the pickup process, first, the air cylinder 30 is operated to adjust the height of the frame support 26 so that the height of the upper end of the drum 22 of the pickup device 20 matches the height of the upper surface of the frame support 26. To do. Next, the frame unit 11 carried out from the cutting device 10 is placed on the drum 22 of the pickup device 20. At this time, the frame support 26 is inserted into the opening of the inner frame 7 c of the frame 7, and the inner peripheral wall 7 d of the inner frame 7 c faces the outer peripheral wall of the frame support 26.

  Thereafter, negative pressure is applied to the inner frame 7 c of the frame 7 from the suction hole 26 a of the frame support 26 to fix the frame 7 of the frame unit 11 on the frame support 26. FIG. 10A is a cross-sectional view schematically showing the frame unit 11 fixed on the frame support base 26. On the wafer 1, cutting marks 3a are formed and divided by the dividing step.

  Next, the air cylinder 30 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. 10 (B), the polyolefin-based sheet 9 is expanded in the outer peripheral direction. FIG. 10B is a cross-sectional view schematically showing the pickup process.

  When the polyolefin-based sheet 9 is expanded in the outer peripheral direction, the distance between the device chips 1c supported by the polyolefin-based sheet 9 is increased. Then, it becomes difficult for the device chips 1c to come into contact with each other, and it becomes easy to pick up individual device chips 1c. Then, the device chip 1c to be picked up is determined, the push-up mechanism 34 is moved below the device chip 1c, and the collet 36 is moved above the device chip 1c.

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

  As described above, according to the wafer processing method of the present embodiment, the frame unit 11 including the wafer 1 can be formed without using an adhesive tape. Therefore, even if the wafer 1 is cut, cutting waste derived from the adhesive layer of the adhesive tape is not generated, and the cutting waste does not adhere to the device chip 1c. Therefore, the quality of the device chip 1c is not deteriorated.

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

  In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

DESCRIPTION OF SYMBOLS 1 Wafer 1a Front surface 1b Back surface 3 Scheduled division line 3a Cutting trace 5 Device 7 Frame 7a Outer frame 7b, 7d Inner wall 7c Inner frame 7e Outer wall 9 Polyolefin sheet 11 Frame unit 2 Chuck table 2a Holding surface 2b, 36a Suction source 2c , 36b 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 26a suction hole 28 Rod 30 Air cylinder 32 Base 34 Push-up mechanism 36 Collet

Claims (6)

A wafer processing method in which a plurality of devices divide a wafer formed in each region of a surface defined by division-scheduled lines into individual device chips,
A polyolefin sheet disposing step of disposing a polyolefin sheet on the back surface of the wafer;
An integration step of heating the polyolefin-based sheet and integrating the wafer and the polyolefin-based sheet by thermocompression bonding;
Before or after the integration step, using a frame composed of an inner frame having an opening large enough to accommodate a wafer and an outer frame having an opening having a diameter corresponding to the outer diameter of the inner frame A frame supporting step of supporting the polyolefin sheet with the frame by sandwiching the outer periphery of the polyolefin sheet between the outer peripheral wall of the inner frame and the inner peripheral wall of the outer frame;
A dividing step of cutting the wafer along a predetermined dividing line by using a cutting device having a cutting blade rotatably, and dividing the wafer into individual device chips;
A pickup step of picking up individual device chips from the polyolefin-based sheet;
A method for processing a wafer, comprising:   2. The wafer processing method according to claim 1, wherein, in the integration step, the thermocompression bonding is performed by infrared irradiation.   2. The wafer processing method according to claim 1, wherein, in the pick-up step, the polyolefin sheet is expanded to widen the space between the device chips, and the device chip is pushed up from the polyolefin sheet side.   2. The wafer processing method according to claim 1, wherein the polyolefin sheet is any one of a polyethylene sheet, a polypropylene sheet, and a polystyrene sheet.   In the integration step, when the polyolefin-based sheet is the polyethylene sheet, the heating temperature is 120 ° C to 140 ° C, and when the polyolefin-based sheet is the polypropylene sheet, the heating temperature is 160 ° C to 180 ° C. The method for processing a wafer according to claim 4, wherein when the polyolefin-based sheet is the polystyrene sheet, the heating temperature is 220 ° C to 240 ° C.   2. The wafer processing method according to claim 1, wherein the wafer is made of any one of Si, GaN, GaAs, and glass.