Method for processing plate-shaped objects

Abstract

To provide a plate-like object processing method capable of solving a problem of damage or breakage when cutting a warped plate-like object to divide the object into individual chips.SOLUTION: A plate-like object processing method includes a laying step of laying a liquid resin that is solidified by irradiation with ultraviolet rays on the upper and lower surfaces of a plate-like object such that at least the liquid resin on the lower surface is flattened, a resin coating step of irradiating the liquid resin with ultraviolet rays to solidify and coat the plate-like object with the resin, and a dividing step of holding the lower surface of the resin-coated plate-like object on a chuck table of a cutting device, cutting the plate-like object together with the coated resin, and dividing the plate-like object into individual chips.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for processing a plate-like object by dividing a warped plate-like object into individual chips. [Background technology]

[0002] Wafers on which ICs, LSIs, and other devices are formed on their surfaces, partitioned by dividing lines, are separated into individual device chips by a dicing machine and used in electrical equipment such as mobile phones and personal computers.

[0003] A dicing device is also used when dividing a two-layer wafer, in which a polycrystalline wafer is stacked on the upper surface of a single crystal wafer, into individual chips (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-050214 Summary of the Invention [Problem to be solved by the invention]

[0005] Two-layer wafers, such as those described above, in which the crystal structures of the first and second layers are different, tend to warp relatively significantly. When such a two-layer wafer is attached to a dicing tape and held by suction on the chuck table of a dicing machine, the warp is corrected by the suction force of the chuck table. However, the correction places a strong stress on the wafer, which can damage or break chips during cutting.

[0006] Furthermore, in order to reduce the influence of the suction force of the chuck table as described above, it is conceivable to fix a warped wafer to a substrate via wax, but since the wax is heated to melt or soften it before use, the wax contracts as it cools, which results in deformation stress being applied to the wafer, and this can also cause the problem of chip damage or breakage during cutting. Note that the above-mentioned problem is not necessarily limited to two-layer wafers, and similar problems occur when cutting a warped plate-like object.

[0007] The present invention has been made in consideration of the above facts, and its main technical object is to provide a method for processing plate-like objects that can solve the problem of damage or breakage when cutting a warped plate-like object and dividing it into individual chips. [Means for solving the problem]

[0008] In order to solve the above-mentioned main technical problem, 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, the method comprising the steps of: a laying step of laying a liquid resin that is solidified by irradiation with ultraviolet light on the upper and lower surfaces of the plate-like object to make at least the liquid resin on the lower surface flat; a resin coating step of irradiating the liquid resin with ultraviolet light to solidify it and coat the plate-like object with the resin; and a dividing step of holding the lower 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 divide it into individual chips. 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. A method for processing a plate-like object is provided.

[0009] In the laying process 、 Preferably, a recess for accommodating a plate-like object is formed in the center of the substrate. Also, it is preferable that the substrate is supported via adhesive tape on a frame having an opening in the center for accommodating the substrate.

[0010] Applicable 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. [Effects of the Invention]

[0011] The method for processing a plate-like object of the present invention includes a laying step of laying a liquid resin that solidifies when irradiated with ultraviolet light on 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 of irradiating the liquid resin with ultraviolet light to solidify it and coat the plate-like object with the resin; and a dividing step of holding the lower 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 divide it into individual chips. 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. Therefore, the plate-like object can be coated with resin without applying stress to the plate-like object, and even if a warped plate-like object is sucked onto the chuck table, no excessive external force is applied to the plate-like object, thereby eliminating the problem of the tip being damaged or broken during cutting. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is an overall perspective view of the cutting device. [Figure 2] 2 is a perspective view of a two-layer wafer cut by the cutting device shown in FIG. 1. FIG. [Figure 3] FIG. 2 is a perspective view of a substrate and an ultraviolet curable resin supply means. [Figure 4] FIG. 10 is a perspective view showing an embodiment of the laying process. [Figure 5] FIG. 10 is a perspective view showing an embodiment of a resin coating step. [Figure 6] 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. [Figure 7] FIG. 10 is a perspective view showing an embodiment of a dividing step. [Figure 8] FIG. 10 is a perspective view showing a mode in which the ultraviolet curable resin is removed from the two-layer wafer after the dividing step is performed. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for processing a plate-like object according to the present invention will be described in detail below with reference to the accompanying drawings.

[0014] 1 shows a cutting apparatus 1 suitable for carrying out the method for processing a plate-like object according to this embodiment. The cutting apparatus 1 includes a roughly rectangular parallelepiped apparatus 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 supported via adhesive tape T on a frame F having a central opening for accommodating the substrate 20.

[0015] Furthermore, the cutting device 1 is equipped with a cassette 5 (shown by a two-dot chain line) that stores a plurality of 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 is arranged so that it can be moved up and down by a lifting means (not shown), and when the two-layer wafer 10 is transferred out of the cassette 5 by the transfer means 7, the height of the cassette 5 is adjusted appropriately.

[0016] A processing feed means (not shown) is arranged within the device housing 2 as a means for processing and feeding the chuck table 3a and the cutting means 4 relative to each other, and moves the chuck table 3a in the X-axis direction indicated by the arrow X.

[0017] FIG. 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 warpage, and the total thickness including the warpage is approximately 1.0 mm.

[0018] The cutting device 1 has roughly the configuration 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, will be described below.

[0019] 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 upper and lower surfaces of the two-layer wafer 10 to make at least the resin on the lower surface flat. The laying step can be carried out, for example, by the following procedure.

[0020] To carry out the above-described laying step, a substrate 20 as shown in FIG. 3 is prepared. The substrate 20 has a thickness of, for example, about 2.0 mm and is made of a material that transmits ultraviolet light, such as glass. An open recess 22 is formed in the center of the upper surface of the substrate 20. The open recess 22 is surrounded by an annular frame 21 and is a recess capable of accommodating 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 capable of accommodating the entire two-layer wafer 10 therein, for example, a depth of about 1.5 mm.

[0021] Once the substrate 20 is prepared, as shown in Figure 3, a supply nozzle 32 of an ultraviolet curable resin supply means 30 is positioned above the recessed opening 22, and a predetermined amount of liquid ultraviolet curable resin 36 is supplied from a supply port 34 of the supply nozzle 32. The ultraviolet curable resin 36 may be any known resin, such as an acrylic resin that hardens when irradiated with ultraviolet light.

[0022] As described above, once the liquid ultraviolet curable resin 36 has been supplied to the open recess 22 of the substrate 20, the laying step 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 ultraviolet curable resin 36 has been supplied, with the side facing downward, and the lower and upper surfaces of the two-layer wafer 10 are covered with the ultraviolet curable resin 36. Since the bottom 23 of the open recess 22 is a flat surface, the resin on the lower surface side is made flat (laying step). In this embodiment, when carrying out this laying step, 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.

[0023] Next, the substrate 20 is placed in an ultraviolet irradiation device (not shown) in which ultraviolet irradiation means are arranged above and below, and a resin coating step is performed in which ultraviolet rays UV are irradiated onto the ultraviolet curing resin 36 from above and below, as shown in Fig. 5. As a result, the liquid ultraviolet curing resin 36 laid on the two-layer wafer 10 solidifies, and the two-layer wafer 10 becomes coated with the ultraviolet curing resin 36.

[0024] Furthermore, in this embodiment, after the above-mentioned resin coating process is performed, a ring-shaped frame F having an opening Fa in the center capable of accommodating the substrate 20 is prepared as shown in FIG. 6, and a frame support process is performed in which the substrate 20 is supported via adhesive tape T.

[0025] Next, the underside coated with the ultraviolet curing resin 36 is held on the chuck table 3a of the cutting device 1, and a dividing process is carried out in which the two-layer wafer 10 is cut together with the ultraviolet curing resin 36 that has coated it and divided into individual chips.

[0026] The above-described dividing step is performed, for example, by the following procedure. More specifically, a plurality of bilayer wafers 10 coated with the UV-curable resin 36 and held in the frame F as described above are placed in the cassette 5 described with reference to FIG. 1 and then loaded into the cutting device 1. The bilayer wafers 10 loaded into the cutting device 1 are transferred from the cassette 5 to the temporary placement table 7 by the loading / unloading means 7, and then transferred to the chuck table 3a by the transfer means 8, where they are placed and held by suction. The bilayer wafers 10 held by suction on the chuck table 3a are moved by a processing feed means (not shown), imaged by the image capture means 12, and the rotation direction of the chuck table 3a is adjusted to align the planned dividing line (not shown) of the bilayer wafer 10 in the X-axis direction. Next, the chuck table 3a is positioned in the processing area directly below the cutting means 4.

[0027] 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 a 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 introduced from the top surface of the blade cover 43.

[0028] Once the double-layer wafer 10 has been moved to the processing area, the cutting blade 41 is rotated and positioned on a predetermined dividing line (not shown) of the double-layer wafer 10, and cutting water is supplied from the cutting water supply means 45 to feed the cutting blade 41 for cutting, while moving the double-layer wafer 10 together with the chuck table 3a in the X-axis direction indicated by the arrow X in Fig. 7, thereby cutting the double-layer wafer 10 to form the cut groove 100. The processing conditions for the cutting process are set, for example, as follows:

[0029] Cutting blade rotation speed: 20,000 rpm Machining feed rate: 3.0 mm / sec Cutting water supply rate: 1.0 liters / minute

[0030] After the cut groove 100 is formed as described above, a new cut 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 indicated by the arrow Y in the figure. By repeating this process, cut grooves 100 are formed along all of the planned division lines along the X-axis direction. The depth of the cut 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.

[0031] After the kerfs 100 have been formed along all of the 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 kerfs 100 is positioned in the X-axis direction. Similarly, as described above, multiple kerfs 100 are formed along the division lines set at predetermined intervals (12 mm) (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 ultraviolet curable resin 36. Hot water W is supplied from the nozzle 54 of the nozzle 52 to the bilayer wafer 10 to remove the ultraviolet curable resin 36, thereby removing the ultraviolet curable resin 36 covering 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.

[0032] The size of the chip C formed as described above is 12 mm x 12 mm, and it is a two-layer chip consisting of a single crystal wafer 10A on the bottom surface and a polycrystalline wafer 10B on the top surface. By carrying out a processing method including at least the above-mentioned laying process, resin coating process, and dividing process, it is possible to coat the chip with resin so that undue stress is not applied during cutting. Furthermore, since the resin on the bottom surface of the two-layer wafer 10 is formed as a flat surface during cutting, undue external force is not applied to the two-layer wafer 10 even when it is sucked by the chuck table 3a, and the problem of the chip C being damaged or broken during cutting is eliminated.

[0033] In addition, 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 crystal 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 the substrate 20. For example, a frame F having an 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.

[0034] Furthermore, in the above-described embodiment, the substrate 20 containing the two-layer wafer 10 is held on 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, and the substrate 20 may be directly held by suction on the chuck table of the cutting device to divide the two-layer wafer 10 into individual chips C.

[0035] Furthermore, in the above embodiment, an example has been described in which the warped plate-like object is a two-layer wafer 10 in which a polycrystalline wafer 10B is 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 the same effect can be achieved with any plate-like object having a warp. [Explanation of symbols]

[0036] 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 table 7: Carrying in / out means 8: Means of transport 9: Cleaning method 10: 2-layer wafer 10A: Single crystal wafer 10B: Polycrystalline wafer 12: Imaging means 20: Substrate 21: Frame 22: Opening recess 23: Bottom 24: Straight section 30: Ultraviolet curing resin supply means 32: Supply nozzle 34: Supply port 36: Ultraviolet curing resin 50:Hot water supply means 52: Nozzle 54: Nozzle 100: Cutting groove F: Frame T: Adhesive tape W: Hot water UV: Ultraviolet light

Claims

1. 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. A method for processing a plate-like object as described in claim 1, wherein a recess for accommodating the plate-like object is formed in the center of the substrate.

3. A method for processing a plate-like object as described in claim 1 or 2, in which the substrate is supported via adhesive tape on a frame having an opening in the center to accommodate the substrate.

4. A method for processing a plate-like object according to any one of claims 1 to 3, wherein the warped plate-like object is a two-layer wafer in which a polycrystalline wafer is stacked on top of a single crystal wafer.

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