JP7739058B2 - Method for processing plate-shaped objects - Google Patents

Description

The present invention relates to a method for processing a plate-like object by dividing a warped plate-like object into individual chips.

Wafer surfaces with ICs, LSIs, and other devices formed on them are divided by planned division lines, and then separated into individual device chips by a dicing machine for use in electronic devices such as mobile phones and personal computers.

Dicing machines are also used to divide two-layer wafers, in which a polycrystalline wafer is stacked on top of a single crystal wafer, into individual chips (see, for example, Patent Document 1).

JP 2010-050214 A

Two-layer wafers, such as those described above, in which the first and second layers have different crystal structures, tend to warp relatively significantly. When such a two-layer wafer is attached to dicing tape and held by suction on the chuck table of a dicing machine, the suction force of the chuck table corrects the warp, but the strong stresses imposed on the wafer as a result of this correction can result in damage or breakage of the chips during the cutting process.

In addition, in order to reduce the effects of the suction force of the chuck table, it is possible to fix a warped wafer to the substrate via wax. However, this fixation requires heating the wax to melt or soften it, which causes the wax to shrink as it cools. This results in deformation stress being applied to the wafer, which can again lead to problems such as chip damage or breakage during cutting. The above-mentioned problems are not necessarily limited to two-layer wafers; similar problems can occur when cutting warped plate-like objects.

The present invention was developed in consideration of the above-mentioned circumstances, and its main technical objective is to provide a method for processing plate-like objects that can eliminate the problem of damage or breakage when cutting a warped plate-like object and dividing it into individual chips.

In order to solve the above-mentioned main technical problems, according to the present invention, there is provided a method for processing a plate-like object by dividing a warped plate-like object into individual chips, comprising the steps of: a laying step in which a liquid resin that solidifies when irradiated with ultraviolet light is applied to the upper and lower surfaces of the plate-like object to flatten at least the liquid resin on the lower surface; a resin coating step in which the liquid resin is irradiated with ultraviolet light to solidify and coat the plate-like object with the resin; and a dividing step in which the lower surface of the resin-coated plate-like object is held on a chuck table of a cutting device, and the plate-like object is cut together with the coated resin to divide it into individual chips; and in the laying step, a method for processing a plate-like object is provided in which the liquid resin is applied to the upper surface of a substrate and the lower surface of the plate-like object is supported by the substrate .

In the laying step , a recess for accommodating a plate-like object is preferably formed in the center of the substrate, and the substrate is preferably supported via adhesive tape on a frame having an opening in the center for accommodating the substrate.

The warped plate- like object may be a wafer having a two-layer structure in which a polycrystalline wafer is stacked on the upper surface of a single crystal wafer.

The method for processing plate-like objects of the present invention includes the steps of: applying a liquid resin, which solidifies when irradiated with ultraviolet light, to the top and bottom surfaces of the plate-like object to flatten at least the liquid resin on the bottom surface; applying ultraviolet light to the liquid resin to solidify it and coat the plate-like object with the resin; and holding the bottom surface of the resin-coated plate-like object on a chuck table of a cutting device and cutting the plate-like object together with the coated resin to separate it into individual chips . In the applying step, the liquid resin is applied to the top surface and the bottom surface of the plate-like object, and the plate-like object is supported by the substrate. This means that the plate-like object can be coated with resin without applying stress to it, and even if a warped plate-like object is sucked into the chuck table, no undue external force is applied to the plate-like object, eliminating the problem of chip damage or breakage during cutting.

FIG. 2 is an overall perspective view of the cutting device. 2 is a perspective view of a two-layer wafer cut by the cutting device shown in FIG. 1. FIG. FIG. 2 is a perspective view of a substrate and an ultraviolet curable resin supply means. FIG. 10 is a perspective view showing an embodiment of the laying process. FIG. 10 is a perspective view showing an embodiment of a resin coating step. FIG. 10 is a perspective view showing an embodiment in which a substrate is supported via adhesive tape on a frame having an opening in the center for accommodating the substrate. FIG. 10 is a perspective view showing an embodiment of a dividing step. FIG. 10 is a perspective view showing an aspect of removing the ultraviolet curable resin from the two-layer wafer after performing the dividing step.

Below, an embodiment of a plate-shaped object processing method constructed based on the present invention will be described in detail with reference to the attached drawings.

Figure 1 shows a cutting device 1 suitable for carrying out the method for processing plate-like objects according to this embodiment. The cutting device 1 comprises a roughly rectangular parallelepiped housing 2, a chuck table mechanism 3 equipped with a chuck table 3a for holding a two-layer wafer 10, which is the workpiece, and cutting means 4 equipped with a cutting blade 41 for cutting the two-layer wafer 10 held on the chuck table 3a. As will be explained later, the plate-like object processed according to this embodiment is the two-layer wafer 10, which is supported by a substrate 20 and is supported via adhesive tape T on a frame F having a central opening for accommodating the substrate 20.

The cutting device 1 further includes a cassette 5 (shown by a two-dot chain line) that stores multiple double-layer wafers 10, a temporary storage table 6 that transports and temporarily stores the double-layer wafers 10 stored in the cassette 5, a transport means 7 that transports the double-layer wafers 10 to the temporary storage table 6, a transport means 8 that rotates and transports the double-layer wafers 10 transported to the temporary storage table 6 onto the chuck table 3a of the chuck table mechanism 3, a cleaning means 9 (details omitted) that cleans the double-layer wafers 10 that have been cut by the cutting means 4, a cleaning and transport means 11 that transports the cut double-layer wafers 10 from the chuck table 3a to the cleaning means 9, an imaging means 12 that images the double-layer wafers 10 held on the chuck table 3a, and a control means (not shown). The cassette 5 is placed on a cassette table 5a that can be moved up and down by an elevator (not shown), and when the two-layer wafer 10 is transferred from the cassette 5 by the transfer means 7, the height of the cassette 5 is adjusted appropriately.

A processing feed means (not shown) is provided within the device housing 2 to move the chuck table 3a in the X-axis direction indicated by the arrow X as a means for relatively feeding the chuck table 3a and the cutting means 4.

Figure 2 shows a two-layer wafer 10 processed by the plate-like object processing method of this embodiment. The two-layer wafer 10 has, for example, a diameter of 100 mm and a thickness of 0.8 mm. The two-layer wafer 10 is formed by stacking a polycrystalline wafer 10B on the upper surface of a single crystal wafer 10A. The single crystal wafer 10A is, for example, a single crystal garnet, and the polycrystalline wafer 10B is, for example, a polycrystalline garnet. A notch N indicating the crystal orientation is formed on the outer periphery of the two-layer wafer 10. The two-layer wafer 10 has a warp, and the total thickness including the warp is approximately 1.0 mm.

The cutting device 1 has a configuration generally as described above, and the method for processing the two-layer wafer 10 of this embodiment, which is carried out using the cutting device 1, is described below.

In carrying out the method for processing the plate-like object, i.e., the two-layer wafer 10, in this embodiment, a laying step is carried out in which a liquid resin that solidifies when irradiated with ultraviolet light is laid on the top and bottom surfaces of the two-layer wafer 10, making at least the resin on the bottom surface flat. This laying step can be carried out, for example, by the following procedure.

When carrying out the above-mentioned installation process, a substrate 20 as shown in Figure 3 is prepared. The substrate 20 is, for example, approximately 2.0 mm thick and made of a material that transmits ultraviolet light, such as glass. In the center of the top surface of the substrate 20, an open recess 22 is formed, which is a recess that is surrounded by an annular frame 21 and can accommodate a two-layer wafer 10, and the open recess 22 has a flat bottom 23. The frame 21 has a linear portion 24 for determining the crystal orientation of the accommodated two-layer wafer 10. The open recess 22 is formed to a depth that can accommodate the entire two-layer wafer 10 therein, for example, a depth of approximately 1.5 mm.

Once the substrate 20 is prepared, as shown in Figure 3, the supply nozzle 32 of the UV-curable resin supply means 30 is positioned above the recessed opening 22, and a predetermined amount of liquid UV-curable resin 36 is supplied from the supply port 34 of the supply nozzle 32. The UV-curable resin 36 can be any known resin, but for example, an acrylic resin that hardens when exposed to UV light can be used.

As described above, once the liquid UV-curable resin 36 has been supplied to the open recess 22 of the substrate 20, the laying process described below is carried out. More specifically, as shown in FIG. 4, the single crystal wafer 10A constituting the lower surface of the two-layer wafer 10 is placed in the open recess 22 into which the liquid UV-curable resin 36 has been supplied, with the side facing downward. The lower and upper surfaces of the two-layer wafer 10 are covered with the UV-curable resin 36. Because the bottom 23 of the open recess 22 is flat, the resin on the lower surface side is also flat (laying process). In this embodiment, when carrying out this laying process, the notch N of the two-layer wafer 10 is positioned on the straight portion 24 of the substrate 20, so that the crystal orientation of the two-layer wafer 10 can be determined by the straight portion 24.

Next, the substrate 20 is placed in an ultraviolet irradiation device (not shown) with ultraviolet irradiation means arranged above and below, and a resin coating process is carried out in which ultraviolet rays UV are irradiated onto the ultraviolet-curable resin 36 from above and below, as shown in Figure 5. This solidifies the liquid ultraviolet-curable resin 36 applied to the two-layer wafer 10, leaving the two-layer wafer 10 coated with the ultraviolet-curable resin 36.

Furthermore, in this embodiment, after the above-mentioned resin coating process is performed, a frame support process is performed in which an annular frame F having a central opening Fa capable of accommodating the substrate 20 is prepared, as shown in Figure 6, and the substrate 20 is supported via adhesive tape T.

Next, the underside coated with the UV-curable resin 36 is held on the chuck table 3a of the cutting device 1, and the two-layer wafer 10 is cut together with the UV-curable resin 36 that coats it, and a dividing process is carried out to divide it into individual chips.

The above-described dividing process is performed, for example, by the following procedure. More specifically, multiple two-layer wafers 10 coated with UV-curable resin 36 and held in frames F as described above are placed in cassettes 5 as described with reference to FIG. 1 and then loaded into the cutting device 1. The two-layer wafers 10 loaded into the cutting device 1 are transferred from the cassettes 5 to the temporary placement table 7 by the loading/unloading means 7, and then transported and placed on the chuck table 3a by the transport means 8, where they are held by suction. The two-layer wafers 10 held by suction on the chuck table 3a are moved by a processing feed means (not shown), imaged by the imaging means 12, and the rotational direction of the chuck table 3a is adjusted to align the planned dividing line (not shown) of the two-layer wafer 10 in the X-axis direction. The chuck table 3a is then positioned in the processing area directly below the cutting means 4.

As shown in Figure 7, the cutting means 4 includes a spindle unit 42. The spindle unit 42 includes a rotating spindle 44 to which the cutting blade 41 is fixed at its tip, and a blade cover 43 that protects the cutting blade 41. The cutting blade 41 is configured to be rotatable together with the rotating spindle 44 in the direction indicated by arrow R1. The cutting blade 41 is selected to have, for example, a diameter of 50 mm, a cutting edge extension of 2.5 mm, and a thickness of 300 μm. A cutting water supply means 45 that supplies cutting water to the cutting position is disposed adjacent to the cutting blade 41 on the blade cover 43, and cutting water is supplied from the top surface of the blade cover 43.

Once the two-layer wafer 10 has been moved to the processing area, the cutting blade 41 is rotated and positioned over a predetermined dividing line (not shown) on the two-layer wafer 10. Cutting water is supplied from the cutting water supply means 45, and the cutting blade 41 is fed to cut the two-layer wafer 10 while moving it together with the chuck table 3a in the X-axis direction indicated by the arrow X in Figure 7, thereby cutting the wafer and forming the cut groove 100. The processing conditions for the cutting process are set, for example, as follows:

Cutting blade rotation speed: 20,000 rpm
Machining feed rate: 3.0 mm/sec. Cutting water supply rate: 1.0 liters/min.

Once the cutting groove 100 has been formed as described above, a new cutting groove 100 is formed by indexing and feeding a predetermined distance (the dimension of one side of the chip to be formed, for example, 12 mm) in the Y-axis direction, as indicated by the arrow Y in the figure. By repeating this process, cutting grooves 100 are formed along all of the planned division lines along the X-axis direction. The depth of the cutting groove 100 is set to a depth that completely divides the two-layer wafer 10 held in the open recess 22 of the substrate 20, but does not completely divide the substrate 20.

Once the cutting grooves 100 have been formed along all of the planned division lines along the X-axis direction as described above, the chuck table 3a is rotated 90 degrees, and the direction perpendicular to the previously formed cutting grooves 100 is positioned in the X-axis direction. Similarly, multiple cutting grooves 100 are formed along the planned division lines set at predetermined intervals (12 mm) in the same manner as described above (see FIG. 8), completing the division process. As shown in FIG. 8, after the division process is completed, the nozzle 52 of the hot water supply means 50 is positioned above the bilayer wafer 10 to remove the UV-curable resin 36. Hot water W is supplied from the nozzle 54 of the nozzle 52 to the bilayer wafer 10 to remove the UV-curable resin 36, thereby removing the UV-curable resin 36 that covers the top and bottom surfaces of the bilayer wafer 10. Through the above process, individual chips C, as shown on the right side of FIG. 8, can be obtained from the bilayer wafer 10.

The chips C formed as described above are 12 mm x 12 mm in size and are two-layer chips consisting of a single crystal wafer 10A on the bottom surface and a polycrystalline wafer 10B on the top surface. By implementing a processing method that includes at least the above-described laying, resin coating, and dividing processes, it is possible to coat the chips with resin to prevent excessive stress from being applied during cutting. Furthermore, because the resin on the bottom surface of the two-layer wafer 10 is formed as a flat surface during cutting, excessive external force is not applied to the two-layer wafer 10 even when it is sucked by the chuck table 3a, eliminating the problem of chips C being damaged or broken during cutting.

The following embodiment is assumed as a reference example . For example, in the above embodiment, a substrate 20 that transmits ultraviolet light is prepared, ultraviolet-curable resin 36 is supplied into the open recess 22 of the substrate 20, and the ultraviolet-curable resin 36 is laid on the upper surface (polycrystalline wafer 10B) and lower surface (single-crystalline wafer 10A) of the two-layer wafer 10, thereby supporting the two-layer wafer 10 with the substrate 20. However, the ultraviolet-curable resin 36 may be laid on the upper and lower surfaces of the two-layer wafer 10 without using a substrate 20. For example, a frame F with adhesive tape T attached to its lower surface as shown in FIG. 6 may be prepared and placed on a flat table, and the ultraviolet-curable resin 36 may be supplied into the opening Fa of the frame F to accommodate the two-layer wafer 10, thereby laying the ultraviolet-curable resin 36 on the upper and lower surfaces of the two-layer wafer 10, so that the ultraviolet-curable resin 36 on the lower surface of the two-layer wafer 10 becomes a flat surface.

In addition, in the above embodiment, the substrate 20 containing the two-layer wafer 10 was held in an annular frame F via adhesive tape T and then held on the chuck table 3a of the cutting device 1 to carry out the dividing process, but the present invention is not necessarily limited to this. The substrate 20 may be held by suction directly on the chuck table of the cutting device, and the two-layer wafer 10 may be divided into individual chips C.

Furthermore, in the above embodiment, an example was described in which the warped plate-like object was a two-layer wafer 10 in which a polycrystalline wafer 10B was stacked on the upper surface of a single crystal wafer 10A. However, the plate-like object processed by the present invention is not limited to this two-layer wafer 10, and similar effects can be achieved with any plate-like object that has warpage.

1: Cutting device 2: Device housing 3: Chuck table mechanism 3a: Chuck table 4: Cutting means 41: Cutting blade 42: Spindle unit 43: Blade cover 44: Rotating spindle 45: Cutting water supply means 5: Cassette 6: Temporary placement table 7: Carrying in/out means 8: Transporting means 9: Cleaning means 10: Two-layer wafer 10A: Single crystal wafer 10B: Polycrystalline wafer 12: Imaging means 20: Substrate 21: Frame portion 22: Opening recess 23: Bottom portion 24: Straight portion 30: Ultraviolet curing resin supply means 32: Supply nozzle 34: Supply port 36: Ultraviolet curing resin 50: Hot water supply means 52: Nozzle 54: Jet port 100: Cutting groove F: Frame T: Adhesive tape W: Hot water UV: Ultraviolet light

Claims (4)

A method for processing a plate-like object by dividing a warped plate-like object into individual chips, comprising:
a laying step of laying a liquid resin that is solidified by irradiation with ultraviolet light on the upper and lower surfaces of a plate-like object, and flattening at least the lower surface of the liquid resin;
a resin coating step of irradiating the liquid resin with ultraviolet light to solidify it and coat the plate-like object with the resin;
a dividing step of holding the underside of the resin-coated plate-like object on a chuck table of a cutting device and cutting the plate-like object together with the resin coating to divide it into individual chips;
The present invention is configured to include
In the laying step, a liquid resin is laid on the upper surface of the substrate and the lower surface of the plate-like object, and the plate-like object is supported by the substrate . 2. The method for processing a plate-like object according to claim 1, wherein a recess for accommodating the plate-like object is formed in the center of the substrate . 3. The method for processing a plate-like object according to claim 1, wherein the substrate is supported via adhesive tape on a frame having an opening in the center for accommodating the substrate . 4. The method for processing a plate-like object according to claim 1, wherein the warped plate-like object is a wafer having a two-layer structure in which a polycrystalline wafer is laminated on the upper surface of a single crystal wafer .