JP2020077704A - 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 by applying hot air to the sheet, and integrates the wafer and the polyester-based sheet. The frame supporting step supports the polyester-based sheet by a frame composed of an inner frame including an opening having a size enough to house the wafer and an outer frame including an opening with a diameter corresponding to an outer diameter of the inner frame by holding an outer periphery of the polyester-based sheet between an outer peripheral wall of the inner frame and an inner peripheral wall of the outer frame using the frame. The dividing step divides the wafer into individual device chips. The picking-up step pushes up the device chip by spraying air and picks up the device chip.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 for 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.

  For example, a laser processing device is used for dividing the wafer (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 that is absorptive to 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 in 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 division groove is formed in the wafer along each division line by ablation, and the wafer is divided.

  After that, the frame unit is carried out from the laser processing apparatus, 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 device chip production efficiency, there is known a processing device capable of continuously dividing a wafer and irradiating the adhesive tape with ultraviolet rays 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 the 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. It sticks.

  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 a glue layer does not adhere to the back surface side of a device chip to be formed, and a quality derived from the adhesion of the glue layer to the device chip is obtained. It is an object of the present invention to provide a wafer processing method that does not cause a decrease.

  According to one aspect of the present invention, a plurality of devices is a wafer processing method for dividing a wafer formed in each region of the front surface partitioned by a dividing line into individual device chips, and A polyester sheet arranging step of arranging the polyester sheet, and an integration step of heating the polyester sheet by applying hot air to the polyester sheet to integrate the wafer and the polyester sheet. Before or after the integration step, a frame composed of an inner frame having an opening that can accommodate the wafer and an outer frame having an opening having a diameter corresponding to the outer diameter of the inner frame is used. Then, a frame supporting step of supporting the polyester sheet by the frame by sandwiching the outer periphery of the polyester sheet between the outer peripheral wall of the inner frame and the inner peripheral wall of the outer frame, and the wafer. A step of irradiating the wafer with a laser beam having a wavelength having absorptivity to the wafer along the dividing line to form dividing grooves and dividing the wafer into individual device chips; and the polyester sheet side And a pick-up step of picking up the device chips from the polyester sheet by individually pushing up the device chips by blowing air from the wafer.

  Further, preferably, in the pick-up step, the polyester sheet is expanded to widen the intervals between the device chips.

  Further, preferably, the polyester sheet is either a polyethylene terephthalate sheet or a polyethylene naphthalate sheet.

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

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

  In the wafer processing method according to one aspect of the present invention, the frame and the wafer are integrated with each other by using a polyester-based sheet having no adhesive layer, without using an adhesive tape having an adhesive layer in the frame unit. The integration step of integrating the polyester sheet and the wafer is realized by applying hot air to the polyester sheet.

  In a wafer processing method according to one aspect of the present invention, a frame including an inner frame having an opening having a size capable of accommodating a wafer and an outer frame having an opening having a diameter corresponding to an outer diameter of the inner frame. Is used. Then, in the frame supporting step, the inner frame is inserted into the opening of the outer frame, and at this time, a polyester sheet is sandwiched between the outer peripheral wall of the inner frame and the inner peripheral wall of the outer frame. Thus, the polyester sheet can be supported by the frame.

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

  After that, the wafer is divided by irradiating the wafer with a laser beam having a wavelength having an absorptivity with respect to the wafer and forming a dividing groove along the planned dividing line by ablation. After that, the device chips are individually pushed up by blowing air from the polyester sheet side, and the device chips are picked up from the polyester sheet. The picked-up device chips are respectively mounted on predetermined mounting targets. If the device chip is pushed up by air during pick-up, the load on the device chip when peeled from the polyester sheet can be reduced.

  When the ablation process is performed on the wafer, the heat generated by the irradiation of the laser beam is transferred to the polyester sheet below and in the vicinity of the dividing groove. However, since the polyester 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 by using the polyester-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 of 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 is positioned on the holding surface of a chuck table. It is a perspective view which shows the polyester sheet | seat arrangement process typically. It is a perspective view which shows an example of an integrated process typically. FIG. 5A is a perspective view schematically showing the frame supporting step, and FIG. 5B 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 pickup device. FIG. 8A is a sectional view schematically showing the frame unit fixed on the frame support base, and FIG. 8B is a sectional view schematically showing the pickup step.

  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, 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. It 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, and LEDs are formed in each area of the front surface 1a of the wafer 1 which is 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 planned dividing line 3 by ablation processing, the wafer 1 is divided, and individual device chips are formed.

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

  The annular frame 7 (see FIG. 5A, etc.) is formed of, for example, a material such as a metal, and corresponds to an inner frame 7c having an opening having a size capable of accommodating the wafer 1, and an outer diameter of the inner frame 7c. And an outer frame 7a having an opening of the same diameter. The inner frame 7c and the outer frame 7a have substantially the same height.

  The polyester-based sheet 9 (see FIG. 3 and the like) is a flexible resin-based sheet and has flat front and back surfaces. The polyester sheet 9 has a diameter larger than the outer diameter of the inner frame 7c of the frame 7 and does not include a glue layer. The polyester sheet 9 is a polymer sheet synthesized by using dicarboxylic acid (compound having two carboxyl groups) and diol (compound having two hydroxyl groups) as monomers, for example, polyethylene terephthalate sheet, or , A sheet such as a polyethylene naphthalate sheet that is transparent or translucent to visible light. 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, it can be partially melted and adhered to the wafer 1 when heated to a temperature near the melting point while being bonded to the wafer 1 while applying a predetermined pressure.

  In the method for processing the wafer 1 according to the present embodiment, the polyester sheet 9 is adhered to the back surface 1b side of the wafer 1 by heating, and the outer peripheral portion of the polyester sheet 9 is provided with the outer peripheral wall 7e of the inner frame 7c and the outer frame 7a. It is sandwiched between the inner peripheral wall 7b and the inner peripheral wall 7b 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 the wafer 1 and the polyester sheet 9 to be integrated with each other, a polyester sheet arranging 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 polyester 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 wafer 1 at the center of the upper portion. 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 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 polyester sheet arranging step, first, as shown in FIG. 2, the wafer 1 is placed on the holding surface 2 a of the chuck table 2. At this time, the front surface 1a side of the wafer 1 is turned downward. Next, the polyester sheet 9 is provided on the back surface 1b of the wafer 1. FIG. 3 is a perspective view schematically showing the polyester sheet arranging step. As shown in FIG. 3, a polyester sheet 9 is provided on the wafer 1 so as to cover the wafer 1.

  In the polyester sheet arranging step, the chuck table 2 including the holding surface 2a having a diameter smaller than that of the polyester sheet 9 is used. When the negative pressure by the chuck table 2 is applied to the polyester 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 polyester sheet 9. This is because the pressure cannot be properly applied to the polyester sheet 9.

  In the method for processing a wafer 1 according to the present embodiment, next, an integrated step of applying hot air to the polyester sheet 9 to heat the polyester sheet 9 to integrate the wafer 1 with the polyester sheet 9 Carry out. FIG. 4 is a perspective view schematically showing an example of the integration process. In FIG. 4, what is visible through the polyester sheet 9 that is transparent or translucent to visible light is indicated by a broken line.

  In the integration step, first, the switching unit 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 polyester sheet 9. Let it work. Then, the polyester sheet 9 is brought into close contact with the wafer 1 by the atmospheric pressure.

  Next, the polyester sheet 9 is heated while sucking the polyester sheet 9 by the suction source 2b. The polyester 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 has a heating unit such as a heating wire and a blowing mechanism such as a fan inside, and can heat and inject air. When the hot gun 4 supplies hot air 4a from the upper surface to the polyester sheet 9 while applying a negative pressure from the suction source 2b to the polyester sheet 9, the polyester sheet 9 is heated to a predetermined temperature. It is thermocompression bonded to.

  After thermocompression-bonding the polyester-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 suction by the chuck table 2 is released.

  When the thermocompression bonding is performed, the polyester sheet 9 is preferably heated to a temperature below its melting point. This is because if the heating temperature exceeds the melting point, the polyester sheet 9 may melt and the sheet shape may not be maintained. Further, the polyester sheet 9 is preferably heated to a temperature equal to or higher than its softening point. This is because thermocompression bonding cannot be properly performed unless the heating temperature reaches the softening point. That is, the polyester sheet 9 is preferably heated to a temperature equal to or higher than its softening point and equal to or lower than its melting point.

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

  When the polyester sheet 9 is a polyethylene terephthalate sheet, the heating temperature is preferably 250 ° C to 270 ° C. When the polyester sheet 9 is a polyethylene naphthalate sheet, the heating temperature is preferably 160 ° C to 180 ° C.

  Here, the heating temperature refers to the temperature of the polyester sheet 9 when the integration step is performed. For example, although a model capable of setting the output temperature is practically used as a heat source such as the heat gun 4, even if the polyester sheet 9 is heated by using the heat source, the temperature of the polyester sheet 9 is set. The output temperature may not be reached. Therefore, 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 this embodiment, a frame supporting step of supporting the polyester sheet 9 with the frame 7 is performed before or after the integration step. FIG. 5A is a perspective view schematically showing the frame supporting step. In the frame supporting step, the outer periphery of the polyester sheet 9 is sandwiched between the outer peripheral wall 7e of the inner frame 7c of the frame 7 and the inner peripheral wall 7b of the outer frame 7a of the frame 7 so that the polyester sheet 9 is retained in the frame. Support at 7.

  First, the polyester sheet 9 is placed on the inner frame 7c. At this time, the position of the polyester sheet 9 is determined such that the entire area of the upper surface of the inner frame 7c is covered with the polyester sheet 9. Next, the outer frame 7a is placed above the polyester 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 with each other.

  After that, the outer frame 7a that is placed above the polyester sheet 9 is pushed down to accommodate the inner frame 7c in the opening of the outer frame 7a. At this time, the outer peripheral portion of the polyester 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. 5B, a frame unit 11 in which the wafer 1, the polyester sheet 9, and the frame 7 are integrated is formed. In the frame unit 11, the polyester sheet 9 is arranged on the upper surface of the inner frame 7c of the frame 7.

  Although the case where the frame supporting step is performed after the integration step has been described, the wafer processing method 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 portion sandwiched between the inner frame 7c and the outer frame 7a of the frame 7 of the polyester sheet 9 by the 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 polyester sheet 9 is bonded to the frame 7 and is supported by the frame 7 with a stronger force.

  Further, the case where the polyester sheet 9 is placed on the inner frame 7c of the frame 7 and the outer frame 7a is placed on the polyester sheet 9 to perform the frame supporting step has been described, but the wafer processing method according to the present embodiment is described. Then, the inner frame 7c and the outer frame 7a may be replaced with each other.

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

  Next, in the method of processing a wafer 1 according to the present embodiment, the wafer 1 in the state of the frame unit 11 is ablated to form a dividing groove along the dividing line 3 to divide the wafer 1. Carry out the dividing step. 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 6 includes a laser processing unit 8 that ablates the wafer 1, and a chuck table (not shown) that holds the wafer 1. The laser processing unit 8 includes a laser oscillator (not shown) that can oscillate a laser, and can emit a laser beam 10 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 8 irradiates the laser beam 10 emitted from the laser oscillator onto the wafer 1 held on the chuck table. The processing head 8 a included in the laser processing unit 8 has a mechanism that focuses the laser beam 10 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 polyester 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 6. Further, the relative positions of the chuck table and the laser processing unit 8 are adjusted so that the processing head 8a is arranged above the extension line of the planned dividing line 3.

  Next, while irradiating the wafer 1 with the laser beam 10 from the laser processing unit 8, the chuck table and the laser processing unit 8 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 10 along the dividing line 3 and the dividing groove 3a along the dividing line 3 is formed in the wafer 1 by ablation.

The irradiation conditions of the laser beam 10 in the division step are set as follows, for example. However, the irradiation condition of the laser beam 10 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 dividing line 3, the chuck table and the laser processing unit 8 are moved relatively in the indexing feeding direction perpendicular to the machining feeding direction, and along the other 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. Similarly, the wafer 1 is 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 back surface 1b along all the planned dividing lines 3 are formed in the wafer 1, the wafer 1 is divided and individual device chips are formed.

  When the ablation process is performed on the wafer 1 by the laser processing unit 8, processing waste originating from the wafer 1 is generated from the irradiation target portion of the laser beam 10, 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 ablation process is performed on the wafer 1, 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, the surface 1a of the wafer 1 that is ablated by the laser processing apparatus 6 may be previously coated with a water-soluble liquid resin that functions as a protective film that protects the surface 1a of the wafer 1. 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 6 may include a cleaning unit (not shown). In this case, the wafer 1 ablated by the laser processing unit 8 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 about 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. By reciprocating in the direction, the front surface 1a side of the wafer 1 can be cleaned.

  In the method for processing the wafer 1 according to this embodiment, next, a pickup step of picking up the individual device chips from the polyester sheet 9 is carried out. In the pickup process, the pickup device 12 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 12.

  The pickup device 12 includes a cylindrical drum 14 having a diameter larger than that of the wafer 1, and a frame holding unit 16 including a frame support 18. The frame support base 18 of the frame holding unit 16 is provided with an opening having a diameter larger than that of the drum 14, and is arranged at the same height as the upper end portion of the drum 14, and the upper end portion of the drum 14 is located on the outer peripheral side. Surround from. Further, the frame support base 18 has an outer diameter of a size corresponding to the diameter of the opening of the inner frame 7c that constitutes the frame 7 of the frame unit 11.

  Further, on the outer peripheral wall of the frame support base 18, for example, a plurality of suction holes 18a are provided. The frame support base 18 can apply a negative pressure to the inner frame 7c of the frame 7 positioned on the outer peripheral side of the frame support base 18 through the suction holes 18a. When the frame unit 11 is placed on the frame support 18 and a negative pressure is applied to the inner frame 7c of the frame 7, the frame unit 11 is fixed to the frame support 18.

  The frame support base 18 is supported by a plurality of rods 20 extending in the vertical direction, and an air cylinder 22 for raising and lowering the rods 20 is arranged at the lower end of each rod 20. The plurality of air cylinders 22 are supported by a disc-shaped base 24. When each air cylinder 22 is operated, the frame support base 18 is pulled down with respect to the drum 14.

  Inside the drum 14, a push-up mechanism 26 that pushes up the device chip supported by the polyester sheet 9 from below is disposed. The push-up mechanism 26 has a function of blowing air 26a upward. Further, a collet 28 (see FIG. 8B) capable of sucking and holding the device chip is arranged above the drum 14. The push-up mechanism 26 and the collet 28 are movable in the horizontal direction along the upper surface of the frame support base 18. Further, the collet 28 is connected to the suction source 28a (see FIG. 8B) via the switching unit 28b (see FIG. 8B).

  In the pickup process, first, the height of the frame support 18 is adjusted by operating the air cylinder 22 so that the height of the upper end of the drum 14 of the pickup device 12 and the height of the upper surface of the frame support 18 match. To do. Next, the frame unit 11 delivered from the laser processing device 6 is placed on the drum 14 of the pickup device 12. At this time, the frame support base 18 is inserted into the opening of the inner frame 7c of the frame 7, and the inner peripheral wall 7d of the inner frame 7c faces the outer peripheral wall of the frame support base 18.

  Then, a negative pressure is applied to the inner frame 7c of the frame 7 from the suction holes 18a of the frame support 18 to fix the frame 7 of the frame unit 11 on the frame support 18. FIG. 8A is a sectional view schematically showing the frame unit 11 fixed on the frame support base 18. The wafer 1 is divided by forming a dividing groove 3a in the dividing step.

  Next, the air cylinder 22 is operated to pull down the frame support base 18 of the frame holding unit 16 with respect to the drum 14. Then, as shown in FIG. 8B, the polyester sheet 9 is expanded in the outer peripheral direction. FIG. 8B is a sectional view schematically showing the pickup step.

  When the polyester sheet 9 is expanded in the outer peripheral direction, the intervals between the device chips 1c supported by the polyester 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 26 is moved below the device chip 1c, and the collet 28 is moved above the device chip 1c.

  Then, the push-up mechanism 26 is operated to blow air 26a from the polyester sheet 9 side to push up the device chip 1c. Then, the switching unit 28b is operated to communicate the collet 28 with the suction source 28a. Then, the device chip 1c is suction-held by the collet 28, and the device chip 1c is picked up from the polyester sheet 9. The individual device chips 1c thus picked up are then mounted on a predetermined wiring board or the like for use.

  When the device chip is picked up, air 26a is blown onto the device chip from the polyester sheet 9 side to push up the device chip, so that the load applied to the device chip when peeling the device chip from the polyester sheet 9 is reduced. To be done.

  For example, when the frame unit 11 is formed using an adhesive tape, heat generated by the irradiation of the laser beam 10 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 polyester-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 polyester sheet 9 is, for example, a polyethylene terephthalate sheet or a polyethylene naphthalate sheet has been described in the above embodiment, one aspect of the present invention is not limited thereto. For example, the polyester-based sheet may be made of another material, and may be a polytrimethylene terephthalate sheet, a polybutylene terephthalate sheet, a polybutylene naphthalate sheet, or the like.

  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 present invention.

1 wafer 1a front surface 1b back surface 3 planned dividing line 3a dividing groove 5 device 7 frame 7a outer frame 7b, 7d inner peripheral wall 7c inner frame 7e outer peripheral wall 9 polyester sheet 11 frame unit 2 chuck table 2a holding surface 2b, 28a suction source 2c , 28b Switching unit 4 Heat gun 4a Hot air 6 Laser processing device 8 Laser processing unit 8a Processing head 10 Laser beam 12 Pickup device 14 Drum 16 Frame holding unit 18 Frame support base 18a Suction hole 20 Rod 22 Air cylinder 24 Base 26 Push-up mechanism 26a Air 28 Collet

Claims (5)

A method for processing a wafer, wherein a plurality of devices divides a wafer formed in each region of the surface partitioned by a planned dividing line into individual device chips,
A polyester sheet arranging step of arranging a polyester sheet on the back surface of the wafer,
An integrated step of heating the polyester sheet by applying hot air to the polyester sheet to integrate the wafer and the polyester sheet,
Before or after the integration step, a frame composed of an inner frame having an opening having a size capable of accommodating the wafer and an outer frame having an opening having a diameter corresponding to the outer diameter of the inner frame is used. A frame supporting step of supporting the polyester sheet by the frame by sandwiching the outer periphery of the polyester sheet between the outer peripheral wall of the inner frame and the inner peripheral wall of the outer frame,
A dividing step of irradiating the wafer with a laser beam having a wavelength having an absorptivity for the wafer along the dividing line, forming dividing grooves, and dividing the wafer into individual device chips;
A pickup step of individually pushing up the device chips by blowing air from the polyester sheet side, and picking up the device chips from the polyester sheet;
A method of processing a wafer, comprising:   2. The wafer processing method according to claim 1, wherein, in the pick-up step, the polyester sheet is expanded to widen a space between the device chips.   2. The method for processing a wafer according to claim 1, wherein the polyester sheet is either a polyethylene terephthalate sheet or a polyethylene naphthalate sheet.   In the integration step, the heating temperature is 250 ° C. to 270 ° C. when the polyester sheet is the polyethylene terephthalate sheet, and the heating temperature is 160 ° C. when the polyester sheet is the polyethylene naphthalate sheet. The method for processing a wafer according to claim 3, wherein the temperature is 180 ° C.   The wafer processing method according to claim 1, wherein the wafer is made of any one of Si, GaN, GaAs, and glass.