JP7166722B2 - Wafer processing method - Google Patents

Description

The present invention relates to a wafer processing method for dividing a wafer, in which a plurality of devices are formed in respective regions of a surface partitioned by dividing lines, into individual device chips.

2. Description of the Related Art In the manufacturing process of device chips used in electronic devices such as mobile phones and personal computers, first, a plurality of intersecting dividing lines (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), LEDs (Light Emitting Diodes), etc. are formed in the regions defined by the division lines.

After that, an adhesive tape called a dicing tape, which is attached to an annular frame having an opening so as to close the opening, is attached to the back surface of the wafer, and the wafer, the adhesive tape, and the annular frame are integrated. form a frame unit. Then, by processing and dividing the wafer contained in the frame unit along the planned division lines, individual device chips are formed.

A laser processing apparatus, for example, is used to divide the wafer (see Patent Document 1). A laser processing apparatus includes a chuck table that holds a 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, the frame unit is placed on the chuck table, and the wafer is held by the chuck table via the adhesive tape. Then, the wafer is irradiated with the laser beam from the laser processing unit while relatively moving the chuck table and the laser processing unit along the direction parallel to the upper surface of the chuck table. When the laser beam is irradiated, a dividing groove is formed in the wafer along each dividing line by ablation, and the wafer is divided.

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

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

The adhesive tape includes, for example, a base layer made of a vinyl chloride sheet or the like, and an adhesive layer provided on the base layer. In order to reliably divide the wafer by ablation, the laser processing apparatus irradiates the wafer with a laser beam under conditions that ensure the formation of dividing grooves extending from the front surface to the back surface of the wafer. Therefore, under and around the formed dividing groove, the adhesive layer of the adhesive tape is melted due to the thermal effect of the laser beam irradiation, and part of the adhesive layer is formed on the back side of the device chip formed from the wafer. Stick.

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

The present invention has been made in view of such problems, and its object is to prevent the glue layer from adhering to the back side of the device chip to be formed, and to improve the quality derived from the adhesion of the glue layer to the device chip. An object of the present invention is to provide a wafer processing method that does not cause deterioration.

According to one aspect of the present invention, there is provided a wafer processing method for dividing a wafer in which a plurality of devices are formed in respective regions of a front surface partitioned by dividing lines into individual device chips, comprising: A polyester-based sheet disposing step of disposing a polyester-based sheet having no adhesive layer, and applying hot air to the polyester-based sheet to heat the polyester-based sheet to integrate the wafer and the polyester-based sheet. an integration step, before or after the integration step, an inner frame having an opening large enough to accommodate the wafer, and an outer frame having an opening with a diameter corresponding to the outer diameter of the inner frame. frame support for supporting the polyester-based sheet with the frame by sandwiching the outer periphery of the polyester-based 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 that is absorptive to the wafer along the dividing lines to form dividing grooves to divide the wafer into individual device chips; and a pick-up step of picking up the individual device chips from the polyester-based sheet.

Preferably, in the pick-up step, the polyester sheet is expanded to widen the space between the device chips, and the device chips are pushed up from the polyester sheet side.

Also 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 250° C. to 270° C. when the polyester sheet is the polyethylene naphthalate sheet. The temperature is between 160°C and 180°C.

Also preferably, the wafer is made of Si, GaN, GaAs, or glass.

In the wafer processing method according to one aspect of the present invention, the frame unit and the wafer are integrated 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 achieved by applying hot air to the polyester sheet.

In a wafer processing method according to an aspect of the present invention, a frame is 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. 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. can support the polyester sheet with a 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 integrating step and the frame supporting step. .

Thereafter, the wafer is irradiated with a laser beam having a wavelength that is absorptive to the wafer, and the wafer is divided by forming dividing grooves along the dividing lines by ablation. After that, 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 the wafer is ablated, heat generated by laser beam irradiation is transferred to the polyester sheet below and near the dividing grooves. However, since the polyester sheet does not have an adhesive layer, the adhesive layer does not melt and adhere to the back side of the device chip.

That is, according to one aspect of the present invention, since the frame unit can be formed using a polyester sheet that does not have a glue layer, an adhesive tape that has a glue layer is not required, and as a result, the device caused by the adhesion of the glue layer Chip quality does not deteriorate.

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

It is a perspective view which shows a wafer typically. FIG. 4 is a perspective view schematically showing how the wafer is positioned on the holding surface of the chuck table; It is a perspective view which shows typically a polyester-type sheet arrangement|positioning process. It is a perspective view which shows an example of an integration process typically. FIG. 5A is a perspective view schematically showing the frame supporting process, and FIG. 5B is a perspective view schematically showing the formed frame unit. It is a perspective view which shows a division process typically. FIG. 10 is a perspective view schematically showing loading of the frame unit into the pickup device; FIG. 8A is a cross-sectional view schematically showing the frame unit fixed on the frame support, and FIG. 8B is a cross-sectional view schematically showing the pickup process.

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

The wafer 1 is made of materials such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductors, or materials such as sapphire, glass, or quartz. It is a substantially disc-shaped substrate or the like made of. Examples of the glass include alkali glass, alkali-free glass, soda-lime glass, lead glass, borosilicate glass, and quartz glass.

The front surface 1a of the wafer 1 is partitioned by a plurality of dividing lines 3 arranged in a lattice. Further, devices 5 such as ICs, LSIs, and LEDs are formed in respective regions defined by dividing lines 3 on the front surface 1a of the wafer 1 . In the method of processing the wafer 1 according to the present embodiment, dividing grooves are formed in the wafer 1 along the dividing lines 3 by ablation processing to divide the wafer 1 into individual device chips.

Before the wafer 1 is loaded into the laser processing device 6 (see FIG. 6) where the ablation process is performed, the wafer 1, the polyester-based sheet, and the frame are integrated to form a frame unit. The wafer 1 is loaded into a laser processing apparatus in the state of a frame unit and processed. Each formed device chip is supported by a polyester sheet. After that, the distance between the device chips is widened by expanding the polyester sheet, and the device chips are picked up by a pick-up device.

The annular frame 7 (see FIG. 5(A), etc.) is formed of a material such as metal, for example, 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 with a diameter equal to that of the outer frame 7a. The inner frame 7c and the outer frame 7a have substantially the same height.

The polyester-based sheet 9 (see FIG. 3, etc.) is a resin-based sheet having flexibility, 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 have a glue layer. The polyester-based sheet 9 is a polymer sheet synthesized using a dicarboxylic acid (a compound having two carboxyl groups) and a diol (a compound having two hydroxyl groups) as monomers, such as a polyethylene terephthalate sheet, or , polyethylene naphthalate sheet, etc., which are transparent or translucent to visible light. However, the polyester sheet 9 is not limited to this, and may be opaque.

The polyester-based sheet 9 cannot be adhered to the wafer 1 at room temperature because it does not have adhesiveness. However, since the polyester-based sheet 9 has thermoplasticity, it can be partially melted and adhered to the wafer 1 by heating 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 connected to the outer peripheral wall 7e of the inner frame 7c and the outer frame 7a. and the inner peripheral wall 7b of the frame unit.

Next, each step of the method for processing the wafer 1 according to this embodiment will be described. First, in preparation for integrating the wafer 1 and the polyester-based sheet 9, a polyester-based sheet disposing step is carried out. 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. As shown in FIG. 2, the process of arranging the polyester-based sheet is performed on a chuck table 2 having a holding surface 2a on its top.

The chuck table 2 has a porous member with a diameter larger than the outer diameter of the wafer 1 in the upper center. The upper surface of the porous member serves as the holding surface 2a of the chuck table 2. As shown in FIG. As shown in FIG. 3, the chuck table 2 has therein an exhaust path, one end of which communicates with the porous member, and a suction source 2b is arranged on the other end of the exhaust path. The exhaust path is provided with a switching portion 2c for switching between a connected state and a disconnected state. Pressure is applied, and the object to be held is held by suction on the chuck table 2 .

In the process of arranging the polyester sheet, 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 of the wafer 1 faces downward. Next, a polyester sheet 9 is arranged on the back surface 1b of the wafer 1. As shown in FIG. FIG. 3 is a perspective view schematically showing a step of disposing a polyester-based sheet. As shown in FIG. 3, a polyester sheet 9 is placed on the wafer 1 so as to cover the wafer 1 .

In addition, in the polyester-based sheet disposing step, a chuck table 2 having a holding surface 2a with a smaller diameter than the diameter of the polyester-based sheet 9 is used. When applying the negative pressure to the polyester sheet 9 by the chuck table 2 in the integration process to be performed later, if the entire holding surface 2a is not covered with the polyester sheet 9, the negative pressure will leak through the gap. , the pressure cannot be appropriately applied to the polyester sheet 9 .

In the method for processing the wafer 1 according to the present embodiment, next, hot air is applied to the polyester-based sheet 9 to heat the polyester-based sheet 9, and the wafer 1 and the polyester-based sheet 9 are integrated. to implement. FIG. 4 is a perspective view schematically showing an example of the integration process. In FIG. 4, the dashed lines indicate what can be seen through the polyester-based sheet 9, which is transparent or translucent to visible light.

In the integration step, first, the switching portion 2c of the chuck table 2 is operated to bring the suction source 2b into a communication state in which it is connected to the porous member above the chuck table 2, and the negative pressure from the suction source 2b is applied to the polyester sheet 9. act. 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 being sucked by the suction source 2b. Heating of the polyester sheet 9 is performed, for example, by a heat gun 4 arranged above the chuck table 2 as shown in FIG.

The heat gun 4 includes a heating means such as a heating wire and a blowing mechanism such as a fan, and can heat and jet air. While applying a negative pressure to the polyester sheet 9 from the suction source 2b, hot air 4a is supplied from the upper surface of the polyester sheet 9 by the heat gun 4 to heat the polyester sheet 9 to a predetermined temperature. It is thermocompression bonded to.

After the polyester-based sheet 9 is thermocompressed, the switching portion 2c is actuated to release the state of communication between the porous member of the chuck table 2 and the suction source 2b, thereby releasing the suction by the chuck table 2. FIG.

It should be noted that the polyester sheet 9 is preferably heated to a temperature below its melting point when the thermocompression bonding is carried out. This is because if the heating temperature exceeds the melting point, the polyester-based sheet 9 may melt and become unable to maintain the shape of the sheet. Moreover, the polyester-based 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 above its softening point and below its melting point.

Furthermore, some polyester sheets 9 may not have a definite softening point. Therefore, the polyester sheet 9 is preferably heated to a temperature higher than or equal to 20° C. lower than its melting point and lower than its melting point when thermocompression bonding is performed.

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

Here, the heating temperature refers to the temperature of the polyester-based sheet 9 during the integration step. For example, in the heat source such as the heat gun 4, a model capable of setting the output temperature has been put into practical use. In some cases, the output temperature is not 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 the present embodiment, a frame supporting step of supporting the polyester-based sheet 9 with the frame 7 is performed before or after the integrating step. FIG. 5A is a perspective view schematically showing the frame supporting process. 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, thereby supporting the polyester sheet 9 with the frame. Support with 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 so that the entire area of the upper surface of the inner frame 7 c is covered with the polyester sheet 9 . Next, the outer frame 7a is placed above the polyester sheet 9. As shown in FIG. 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 each other.

After that, the outer frame 7a placed on the polyester 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 polyester sheet 9 is folded by the outer frame 7a and 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 is formed in which the wafer 1, the polyester sheet 9, and the frame 7 are integrated. In the frame unit 11, a polyester sheet 9 is arranged on the upper surface of the inner frame 7c of the frame 7. As shown in FIG.

Although the case where the frame supporting process is performed after the integration process has been described, the wafer processing method according to this embodiment is not limited to this. For example, the integration process may be performed after the frame support process. In this case, the part sandwiched between the inner frame 7c and the outer frame 7a of the frame 7 of the polyester sheet 9 by heating in the integration process is the outer peripheral wall 7e of the inner frame 7c, the inner peripheral wall 7b of the outer frame 7a, , and the polyester sheet 9 is supported by the frame 7 with a stronger force.

Moreover, 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 thereon to carry out the frame supporting step has been described, but 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 polyester sheet 9 may be placed on the outer frame 7a, the inner frame 7c may be placed thereon, and the inner frame 7c may be accommodated in the opening of the outer frame 7a by pressing the inner frame 7c from above. In this case, in the formed frame unit, the polyester-based 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 for processing the wafer 1 according to the present embodiment, the wafer 1 in the state of the frame unit 11 is ablated to form dividing grooves along the dividing lines 3 to divide the wafer 1. A division step is performed. The dividing step is performed, for example, by a laser processing apparatus shown in FIG. FIG. 6 is a perspective view schematically showing the dividing step.

The laser processing apparatus 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) capable of oscillating a laser, and can emit a laser beam 10 having a wavelength that is absorptive to the wafer 1 (a wavelength that can be absorbed by the wafer 1). The chuck table can move (process feed) along a direction parallel to the upper surface.

A laser processing unit 8 irradiates the wafer 1 held on the chuck table with a laser beam 10 emitted from the laser oscillator. A processing head 8 a provided in the laser processing unit 8 has a mechanism for condensing the laser beam 10 to a predetermined height position on the wafer 1 .

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 with the polyester sheet 9 interposed therebetween. Then, the chuck table is rotated to align the dividing line 3 of the wafer 1 with the processing feed direction of the laser processing device 6 . Also, 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. FIG.

Next, while irradiating the laser beam 10 from the laser processing unit 8 to the wafer 1, the chuck table and the laser processing unit 8 are relatively moved along the 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 planned dividing line 3, and the dividing grooves 3a along the planned dividing line 3 are 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 conditions of the laser beam 10 are not limited to this.
Wavelength: 355nm
Repetition frequency: 50 kHz
Average output: 5W
Feeding speed: 200mm/sec

After performing ablation along one of the planned division lines 3, the chuck table and the laser processing unit 8 are relatively moved in the index feed direction perpendicular to the processing feed direction, and along the other planned division lines 3 Similarly, the wafer 1 is ablated. After forming the dividing grooves 3a along all the dividing lines 3 along one direction, the chuck table is rotated around the axis perpendicular to the holding surface, and along the dividing lines 3 along the other direction. Then, the wafer 1 is similarly ablated.

When the wafer 1 has been ablated along all the dividing lines 3 of the wafer 1, the dividing step is completed. When the dividing step is completed and dividing grooves 3a extending from the front surface 1a to the back surface 1b along all the dividing lines 3 are formed in the wafer 1, the wafer 1 is divided to form individual device chips.

When the laser processing unit 8 performs ablation processing on the wafer 1, processing debris originating from the wafer 1 is generated from the irradiated location of the laser beam 10, and the processing debris scatters around the irradiated location to cause damage to the wafer 1. It adheres to the surface 1a. Even if the front surface 1a of the wafer 1 is cleaned by a cleaning unit described later after the wafer 1 is ablated, it is not easy to completely remove the adhered processing debris. If the processing waste remains on the device chips formed from the wafer 1, the quality of the device chips will be degraded.

Therefore, the surface 1a of the wafer 1 to be ablated by the laser processing device 6 may be coated in advance with a water-soluble liquid resin that functions as a protective film to protect the surface 1a of the wafer 1. FIG. When the liquid resin is applied to the surface 1a of the wafer 1, processing debris scattered during the ablation process adheres to the upper surface of the liquid resin, so the processing debris does not directly adhere to the surface 1a of the wafer 1. . Then, the processing waste is removed together with the liquid resin by a cleaning unit to be described below.

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 transported to the cleaning unit and cleaned by the cleaning unit. For example, the cleaning unit includes a cleaning table that holds the frame unit 11 and a cleaning water supply nozzle that can reciprocate above the frame unit 11 .

The cleaning table is rotated around an axis perpendicular to the holding surface, and while a cleaning liquid such as pure water is supplied 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. The front surface 1a side of the wafer 1 can be cleaned by reciprocating in the direction.

In the method for processing the wafer 1 according to the present embodiment, next, a pick-up step of picking up the individual device chips from the polyester-based sheet 9 is performed. In the pick-up process, a pick-up device 12 shown in the lower part of FIG. 7 is used. FIG. 7 is a perspective view schematically showing loading of the frame unit 11 into the pickup device 12. As shown in FIG.

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 has an opening with a diameter larger than the diameter of the drum 14 and is arranged at the same height as the upper end of the drum 14 so that the upper end of the drum 14 faces the outer circumference. surround from Further, the frame support 18 has an outer diameter corresponding to the diameter of the opening of the inner frame 7c forming the frame 7 of the frame unit 11. As shown in FIG.

In addition, for example, a plurality of suction holes 18a are provided on the outer peripheral wall of the frame support 18 . The frame supporter 18 can apply negative pressure to the inner frame 7c of the frame 7 positioned on the outer peripheral side of the frame supporter 18 through the suction holes 18a. The frame unit 11 is fixed to the frame support base 18 by placing the frame unit 11 on the frame support base 18 and applying negative pressure to the inner frame 7c of the frame 7 .

The frame support base 18 is supported by a plurality of rods 20 extending along the vertical direction, and an air cylinder 22 for raising and lowering the rods 20 is provided at the lower end of each rod 20 . A plurality of air cylinders 22 are supported by a disk-shaped base 24 . Actuation of each air cylinder 22 causes the frame support 18 to be lowered relative to the drum 14 .

Inside the drum 14, a push-up mechanism 26 is arranged to push up the device chip supported by the polyester sheet 9 from below. 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 collet 28 are horizontally movable along the upper surface of the frame support 18 . Also, the collet 28 is connected to a suction source 28a (see FIG. 8B) via a switching portion 28b (see FIG. 8B).

In the pickup process, first, the air cylinder 22 is operated to adjust the height of the frame support 18 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. do. Next, the frame unit 11 carried out from the laser processing device 6 is placed on the drum 14 of the pickup device 12 . At this time, the frame support 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 18. As shown in FIG.

Thereafter, negative pressure is applied to the inner frame 7c of the frame 7 through the suction holes 18a of the frame support 18 to fix the frame 7 of the frame unit 11 on the frame support 18. As shown in FIG. FIG. 8A is a cross-sectional view schematically showing the frame unit 11 fixed on the frame support 18. FIG. The wafer 1 is divided by forming dividing grooves 3a by a dividing step.

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

When the polyester-based sheet 9 is expanded in the outer peripheral direction, the intervals between the device chips 1c supported by the polyester-based sheet 9 are widened. As a result, the device chips 1c are less likely to come into contact with each other, making it easier to pick up the individual device chips 1c. 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.

Thereafter, the push-up mechanism 26 is operated to push up the device chip 1c from the polyester sheet 9 side. Then, the switching portion 28b is operated to connect the collet 28 to the suction source 28a. Then, the device chip 1c is held by suction by the collet 28, and the device chip 1c is picked up from the polyester sheet 9. As shown in FIG. The individual device chips 1c picked up are then mounted on a predetermined wiring board or the like for use.

For example, when forming the frame unit 11 using an adhesive tape, the heat generated by the irradiation of the laser beam 10 in the division process is transmitted to the adhesive tape, and the glue layer of the adhesive tape melts and adheres to the back side of the device chip. do. Then, there is a problem that the quality of the device chip is deteriorated due to adhesion of the adhesive layer.

On the other hand, according to the wafer processing method according to the present embodiment, it is possible to form a frame unit using a polyester sheet that does not have a glue layer by thermocompression bonding, so adhesive tape with a glue layer is unnecessary. is. As a result, the quality of the device chip does not deteriorate due to adhesion of the glue layer to the back surface.

It should be noted that the present invention is not limited to the description of the above embodiments, and can be implemented with various modifications. For example, in the 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 aspect of the present invention is not limited to this. For example, other materials may be used for the polyester-based sheet, such as 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 modified as appropriate without departing from the scope of the present invention.

REFERENCE SIGNS LIST 1 wafer 1a front surface 1b back surface 3 division line 3a division 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 28 collet

Claims (5)

A wafer processing method for dividing a wafer in which a plurality of devices are formed in respective regions of a surface partitioned by dividing lines into individual device chips,
A polyester-based sheet disposing step of disposing a polyester-based sheet having no adhesive layer on the back surface of the wafer;
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 is used which is composed of an inner frame having an opening large enough to accommodate the 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 polyester-based sheet with the frame by sandwiching the outer periphery of the polyester-based 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 that is absorptive to the wafer along the dividing lines to form dividing grooves to divide the wafer into individual device chips;
a picking up step of picking up the individual device chips from the polyester sheet;
A wafer processing method comprising: 2. The method of processing a wafer according to claim 1, wherein in said pick-up step, said polyester sheet is expanded to widen the space between the device chips, and said device chips are pushed up from said polyester sheet side. 2. The wafer processing method according to claim 1, wherein said 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. to 160° C. when the polyester sheet is the polyethylene naphthalate sheet. 4. The method of processing a wafer according to claim 3, wherein the temperature is 180.degree. 2. The method of processing a wafer according to claim 1, wherein said wafer is made of any one of Si, GaN, GaAs and glass.

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