JP7204295B2 - 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 polyolefin-based sheet disposing step of disposing a polyolefin-based sheet having no adhesive layer, and heating the polyolefin-based sheet by applying hot air to the polyolefin-based sheet to integrate the wafer and the polyolefin-based sheet. before or after the integration step, a first frame having an opening sized to accommodate the wafer and having a plurality of magnets; and an opening sized to accommodate the wafer. and a second frame having a frame supporting step of supporting the polyolefin-based sheet with the frame; and irradiating the wafer with a laser beam having a wavelength that is absorptive to the wafer along the dividing lines to form dividing grooves. A wafer processing method is provided, comprising: a dividing step of dividing a wafer into individual device chips; and a picking up step of picking up the individual device chips from the polyolefin-based sheet.

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

Moreover, preferably, the polyolefin-based sheet is a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet.

Further preferably, in the integration step, the heating temperature is 120° C. to 140° C. when the polyolefin sheet is the polyethylene sheet, and the heating temperature is 160° C. when the polyolefin sheet is the polypropylene sheet. °C to 180°C, and when the polyolefin sheet is the polystyrene sheet, the heating temperature is 220°C to 240°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 polyolefin-based sheet having no glue layer, without using an adhesive tape having a glue layer in the frame unit. The integration step of integrating the polyolefin-based sheet and the wafer is achieved by applying hot air to the polyolefin-based sheet.

A wafer processing method according to an aspect of the present invention comprises a first frame having an opening large enough to accommodate the wafer, and a second frame having an opening large enough to accommodate the wafer. frame is used. The first frame has a plurality of magnets, and the first frame and the second frame are attracted to each other by magnetic forces generated by the magnets.

In the frame supporting step, a polyolefin sheet is placed between the first frame and the second frame, and sandwiched between the first frame and the second frame. A polyolefin sheet can be supported by a frame.

That is, even if the polyolefin-based sheet does not have a glue layer, the wafer, the polyolefin-based sheet, and the frame can be integrated to form a frame unit by performing the integration 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 polyolefin-based sheet. Each of the picked-up device chips is mounted on a predetermined mounting target.

When a wafer is ablated, heat generated by laser beam irradiation is transferred to the polyolefin-based sheet below and in the vicinity of the dividing grooves. However, since the polyolefin-based 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 polyolefin-based 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; FIG. 4 is a perspective view schematically showing a polyolefin-based sheet disposing step; 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.

The wafer 1, the polyolefin-based sheet, and the frame are integrated to form a frame unit before the wafer 1 is carried into the laser processing device 6 (see FIG. 6) where the ablation processing is performed. 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 polyolefin sheet. After that, the polyolefin-based sheet is expanded to widen the space between the device chips, and the device chips are picked up by a pick-up device.

The annular frame 7 (see FIGS. 5(A) and 5(B), etc.) is formed of a material such as metal, for example, and includes a first frame 7a having an opening 7b large enough to accommodate the wafer 1, and a first frame 7a. , a second frame 7 f having an opening 7 g large enough to accommodate the wafer 1 . For example, the first frame 7a and the second frame 7f have substantially the same shape.

The first frame 7a has a plurality of pins 7d on its upper surface 7c. A plurality of magnets 7e are embedded in the upper surface 7c of the first frame 7a. The second frame 7f is provided with a plurality of through holes 7i passing through in the thickness direction. The through holes of the second frame 7f are formed such that the pins 7d of the first frame 7a are fitted into the through holes 7i when the first frame 7a and the second frame 7f are superimposed on each other. 7i are formed in a number, position and size corresponding to the pins 7d of the first frame 7a.

The polyolefin-based sheet 9 (see FIG. 3, etc.) is a flexible resin-based sheet having flat front and back surfaces. The polyolefin sheet 9 has a diameter larger than that of the opening 7b of the first frame 7a and the opening 7g of the second frame 7f, which constitute the frame 7, and does not have a glue layer. The polyolefin-based sheet 9 is a polymer sheet synthesized using alkene as a monomer, and is, for example, a transparent or translucent sheet to visible light, such as a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet. However, the polyolefin-based sheet 9 is not limited to this, and may be opaque.

The polyolefin-based sheet 9 cannot be adhered to the wafer 1 at room temperature because it does not have adhesiveness. However, since the polyolefin-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 of processing the wafer 1 according to the present embodiment, the polyolefin sheet 9 is adhered to the back surface 1b side of the wafer 1 by heating, and the outer peripheral portion of the polyolefin sheet 9 is formed into the first frame 7a and the second frame 7f. , to form a frame unit.

Next, each step of the method for processing the wafer 1 according to this embodiment will be described. First, in preparation for integrating the wafer 1 and the polyolefin sheet 9, a polyolefin sheet disposing step is performed. FIG. 2 is a perspective view schematically showing how the wafer 1 is positioned on the holding surface 2a of the chuck table 2. As shown in FIG. As shown in FIG. 2, the polyolefin-based sheet placement process 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 polyolefin sheet placement 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 of the wafer 1 faces downward. Next, a polyolefin-based 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 polyolefin-based sheet disposing step. As shown in FIG. 3, a polyolefin-based sheet 9 is placed on the wafer 1 so as to cover the wafer 1 .

In addition, in the polyolefin-based sheet arranging step, a chuck table 2 having a holding surface 2a with a smaller diameter than the diameter of the polyolefin-based sheet 9 is used. When the chuck table 2 applies negative pressure to the polyolefin-based sheet 9 in the subsequent integration process, the negative pressure will leak through the gaps unless the entire holding surface 2a is covered with the polyolefin-based sheet 9. , the pressure cannot be appropriately applied to the polyolefin-based sheet 9 .

In the method for processing the wafer 1 according to the present embodiment, next, hot air is applied to the polyolefin-based sheet 9 to heat the polyolefin-based sheet 9, and the wafer 1 and the polyolefin-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 polyolefin-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 polyolefin sheet 9. act. Then, the polyolefin-based sheet 9 is brought into close contact with the wafer 1 by the atmospheric pressure.

Next, the polyolefin sheet 9 is heated while being sucked by the suction source 2b. Heating of the polyolefin-based 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 from the suction source 2b to the polyolefin sheet 9, hot air 4a is supplied from the upper surface of the polyolefin sheet 9 by the heat gun 4 to heat the polyolefin sheet 9 to a predetermined temperature. It is thermocompression bonded to.

After the polyolefin-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.

It should be noted that the polyolefin sheet 9 is preferably heated to a temperature below its melting point when the thermocompression bonding is performed. This is because if the heating temperature exceeds the melting point, the polyolefin-based sheet 9 may melt and become unable to maintain the shape of the sheet. Also, the polyolefin-based sheet 9 is preferably heated to a temperature above its softening point. This is because thermocompression bonding cannot be properly performed unless the heating temperature reaches the softening point. That is, the polyolefin sheet 9 is preferably heated to a temperature above its softening point and below its melting point.

Furthermore, some polyolefin-based sheets 9 may not have a definite softening point. Therefore, the polyolefin 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 performing thermocompression bonding.

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

Here, the heating temperature refers to the temperature of the polyolefin-based sheet 9 during the integration step. For example, a heat source such as a heat gun 4 has been put into practical use with a model whose output temperature can be set. In some cases, the output temperature is not reached. Therefore, in order to heat the polyolefin sheet 9 to a predetermined temperature, the output temperature of the heat source may be set higher than the melting point of the polyolefin sheet 9 .

In the method for processing the wafer 1 according to the present embodiment, a frame supporting step of supporting the polyolefin-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 polyolefin sheet 9 is supported by the frame 7 by sandwiching the outer peripheral portion of the polyolefin sheet 9 between the first frame 7a and the second frame 7f.

First, the polyolefin sheet 9 is placed on the upper surface 7c of the first frame 7a. At this time, the position of the polyolefin sheet 9 is determined so as to block all the openings 7b of the first frame 7a. Next, the second frame 7f is placed on the polyolefin sheet 9 with the lower surface 7h facing downward. At this time, the position of the second frame 7f is determined so that the through holes 7i of the second frame 7f are fitted into the pins 7d of the first frame 7a.

When the first frame 7a and the second frame 7f are overlapped, the magnetic force generated by the plurality of magnets 7e provided in the first frame 7a acts to attract both frames to each other, and the outer peripheral portion of the polyolefin sheet 9 is pulled. sandwiched between the two frames. Therefore, the polyolefin-based sheet 9 is supported by the frame 7 . At this time, since the pins 7d of the first frame 7a are fitted into the through holes 7i of the second frame 7f, the first frame 7a and the second frame 7f are not horizontally displaced from each other.

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 outer periphery of the polyolefin sheet 9 is adhered to the first frame 7a and the second frame 7f by heating in the integration process, and the polyolefin sheet 9 is supported by the frame 7 with a stronger force.

Next, in the method for processing the wafer 1 according to the present embodiment, 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 polyolefin 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 polyolefin-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

A clamp 20 is arranged on the outer peripheral side of the frame support base 18 . The frame unit 11 is fixed to the frame support base 18 when the frame unit 11 is placed on the frame support base 18 and the frame 7 of the frame unit 11 is gripped by the clamp 20 .

The frame support base 18 is supported by a plurality of rods 22 extending along the vertical direction, and an air cylinder 24 for raising and lowering the rods 22 is provided at the lower end of each rod 22 . A plurality of air cylinders 24 are supported by a disk-shaped base 26 . Actuation of each air cylinder 24 lowers the frame support 18 relative to the drum 14 .

Inside the drum 14, a push-up mechanism 28 is arranged to push up the device chip supported by the polyolefin sheet 9 from below. A collet 30 (see FIG. 8B) capable of sucking and holding the device chip is arranged above the drum 14 . The push-up mechanism 28 and collet 30 are horizontally movable along the upper surface of the frame support 18 . Also, the collet 30 is connected to a suction source 30a (see FIG. 8B) via a switching portion 30b (see FIG. 8B).

In the pick-up process, first, the air cylinder 24 is actuated to raise 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 approximately match. Adjust. For example, the upper surface of the frame support 18 may be positioned lower than the upper end of the drum 14 by the thickness of the first frame 7a. Next, the frame unit 11 carried out from the laser processing device 6 is placed on the drum 14 of the pickup device 12 .

After that, the frame 7 of the frame unit 11 is fixed on the frame support base 18 by the clamps 20 . 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 24 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 polyolefin sheet 9 is expanded in the outer peripheral direction. FIG. 8B is a cross-sectional view schematically showing the pickup process.

When the polyolefin-based sheet 9 is expanded in the outer peripheral direction, the intervals between the device chips 1c supported by the polyolefin-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 28 is moved below the device chip 1c, and the collet 30 is moved above the device chip 1c.

Thereafter, the push-up mechanism 28 is operated to push up the device chip 1c from the polyolefin sheet 9 side. Then, the switching portion 30b is operated to connect the collet 30 to the suction source 30a. Then, the device chip 1c is held by suction by the collet 30, and the device chip 1c is picked up from the polyolefin-based 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.

In contrast, according to the wafer processing method according to the present embodiment, it is possible to form a frame unit using a polyolefin-based sheet that does not have an adhesive layer by thermocompression bonding, so adhesive tape with an adhesive 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 polyolefin sheet 9 is, for example, a polyethylene sheet, a polypropylene sheet, or a polystyrene sheet, but one aspect of the present invention is not limited to this. For example, other materials may be used for the polyolefin-based sheet, such as a copolymer of propylene and ethylene, or an olefin-based elastomer.

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 rear surface 3 division line 3a division groove 5 device 7, 7a, 7f frames 7b, 7g opening 7c upper surface 7d pin 7e magnet 7h lower surface 7i through hole 9 polyolefin sheet 11 frame unit 2 chuck table 2a holding surface 2b, 30a suction source 2c, 30b 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 20 clamp 22 rod 24 air cylinder 26 base 28 push-up mechanism 30 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 polyolefin-based sheet disposing step of disposing a polyolefin-based sheet having no glue layer on the back surface of the wafer;
an integration step of heating the polyolefin-based sheet by applying hot air to the polyolefin-based sheet to integrate the wafer and the polyolefin-based sheet;
Before or after the integration step, a first frame having an opening sized to accommodate the wafer and having a plurality of magnets, and a second frame having an opening sized to accommodate the wafer. , and the polyolefin sheet is sandwiched between the first frame and the second frame by the magnetic force generated by the magnet, thereby holding the polyolefin sheet. a frame supporting step of supporting with the 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 pick-up step of picking up the individual device chips from the polyolefin-based sheet;
A wafer processing method comprising: 2. The wafer processing method according to claim 1, wherein in said pick-up step, said polyolefin-based sheet is expanded to widen the space between the device chips, and said device chips are pushed up from said polyolefin-based sheet side. 2. The wafer processing method according to claim 1, wherein said polyolefin sheet is one of a polyethylene sheet, a polypropylene sheet and a polystyrene sheet. In the integration step, the heating temperature is 120° C. to 140° C. when the polyolefin sheet is the polyethylene sheet, and the heating temperature is 160° C. to 180° C. when the polyolefin sheet is the polypropylene sheet. 4. The method of processing a wafer according to claim 3, wherein the heating temperature is 220.degree. C. to 240.degree. C. when the polyolefin sheet is the polystyrene sheet. 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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