Division method of wafer

Abstract

To provide a division method of a wafer, capable of preventing deterioration of an etching rate when dividing the wafer with plasma etching.SOLUTION: A division method for dividing a wafer W which has a metal member M formed onto a front surface along lattice-like streets L1 and L2 executes: a first protection film formation step of forming a first protection film F1 that protects a front surface whole surface of the wafer W; a first groove formation step of forming a first groove G1 by cutting the metal member M while removing the first protection film F1 along the streets L1 and L2 by irradiating the front surface of the wafer W with a laser light beam along the streets L1 and L2; a second protection film formation step of forming a second groove G2 which has a width narrower than that of the first groove G1 by forming a second protection film F2 on at least side surface of the first groove G1; and a division step of dividing the wafer W into a plurality of chips C by performing plasma etching of the second groove G2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a wafer dividing method for dividing a wafer along grid-like streets (planned dividing lines). [Background technology]

[0002] For example, in the manufacturing process of semiconductor devices, the surface of a disk-shaped semiconductor wafer (hereinafter simply referred to as a "wafer") is divided into multiple device regions by streets (planned division lines) formed in a grid pattern, and devices such as ICs and LSIs are formed in each device region. Then, the wafer on which many devices are formed in this way is divided along the streets to obtain multiple chips.

[0003] Here, known methods for dividing a wafer along the streets include blade dicing, which involves cutting the wafer along the streets with a cutting blade to form kerfs, plasma dicing, which involves forming grooves in the wafer along the streets by plasma etching under vacuum (see, for example, Patent Document 1), and laser ablation, which involves irradiating the wafer surface with laser light to form grooves in the wafer along the streets. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-041935 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, some wafers on which multiple devices are formed have test metal members (TEG (Test Element Group)) formed along the streets. When such a wafer is divided into multiple chips by plasma dicing, the protective film formed on the top surface of the wafer is removed by laser ablation processing along the streets. During this process, some of the materials that make up the metal members and substrate formed on the wafer become debris and accumulate on the protective film. Then, the metal members are exposed on the side of the grooves where the protective film has been removed.

[0006] As described above, when the protective film that protects the top surface of the wafer is removed, a portion of the metal member is exposed on the side of the groove, which may result in a decrease in the etching rate when plasma etching the wafer.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a wafer dividing method that can prevent a decrease in the etching rate when dividing a wafer by plasma etching. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a wafer dividing method for dividing a wafer having metal members formed on its surface along grid-like streets into a plurality of chips, the method comprising: a first protective film forming step of applying a first liquid resin to the surface of the wafer to form a first protective film that protects the entire surface of the wafer; a first groove forming step of irradiating the surface of the wafer with a laser beam along the streets to remove the first protective film along the streets and cut the metal member, thereby forming a first groove; a second protective film forming step of applying a second liquid resin to at least the side surface of the first groove to form a second protective film, thereby forming a second groove narrower than the first groove; and a dividing step of dividing the wafer into a plurality of chips by plasma etching the second groove. [Effects of the Invention]

[0009] According to the present invention, in the first groove forming step, the first groove is formed by cutting the metal member while removing the first protective film along the streets. At least the side surfaces of the first groove are protected by the second protective film in the subsequent second protective film forming step, and the metal member is not exposed on the side surfaces. Therefore, a decrease in the etching rate when dividing the wafer by plasma etching in the dividing step is prevented, and the wafer is divided efficiently by plasma etching. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a perspective view of a work set including a wafer to be divided. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] 1 is a block diagram showing a wafer dividing method according to the present invention in the order of steps; [Figure 4] FIG. 1 is a perspective view of a laser processing device. [Figure 5] FIG. 1 is a perspective view of a protective film forming / removing device. [Figure 6] 10 is a side cross-sectional view of a work set illustrating a first protective film forming step in the wafer dividing method according to the present invention. FIG. [Figure 7] 10 is a side cross-sectional view of a work set showing a first groove forming step in the wafer dividing method according to the present invention. FIG. [Figure 8] FIG. 8 is an enlarged detailed view of part B in FIG. 7. [Figure 9] 10 is a side cross-sectional view of a work set showing a second protective film forming step in the wafer dividing method according to the present invention. FIG. [Figure 10] FIG. 10 is an enlarged detailed view of part C in FIG. 9. [Figure 11] 10 is a side cross-sectional view of a work set showing a second groove forming step in the wafer dividing method according to the present invention. FIG. [Figure 12] FIG. 12 is an enlarged detailed view of part D in FIG. [Figure 13] FIG. 1 is a vertical cross-sectional view of a plasma etching apparatus. [Figure 14] 1A and 1B are cross-sectional side views of a work set showing a dividing step in a wafer dividing method according to the present invention. [Figure 15] 10 is a side cross-sectional view of a work set showing a protective film removing step in the wafer dividing method according to the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] As shown in FIG. 1, the wafer W to be divided by the dividing method according to the present invention is, for example, a thin, disk-shaped member made of single-crystal silicon (Si), and its surface (top surface in FIG. 1) is partitioned into a plurality of rectangular regions by mutually orthogonal streets (planned dividing lines) L1, L2 arranged in a grid pattern, and a device D such as an IC or LSI is formed in each rectangular region.

[0013] 2, test metal members (TEG) M are formed in a grid pattern along streets L1 and L2 on the surface of the wafer W. The wafer W having a large number of devices D and metal members M formed on its surface is incorporated into a work set WS, and the dividing method according to the present invention is carried out on the wafer W. Note that, as the material of the wafer W, silicon carbide (SiC), glass, ceramics, sapphire, etc. may be used in addition to silicon (Si).

[0014] 1 and 2, the work set WS is configured by adhering the back surface (bottom surface in FIG. 2) of a disk-shaped wafer W to heat-shrinkable tape T, which is attached to cover the circular opening of a ring-shaped ring frame F, thereby supporting the wafer W on the ring frame F via the tape T and integrating the wafer W, ring frame F, and tape T. The material of the tape T is not particularly limited as long as it is both stretchable and heat-shrinkable. For example, a two-layer structure in which an adhesive layer is laminated on a base layer made of polyolefin, polyvinyl chloride, polypropylene, or the like is used. Here, the tape T has an outer diameter at least larger than the diameter of the wafer W.

[0015] Therefore, the method for dividing a wafer W according to the present invention is as follows, as shown in FIG. 1) First protective film formation process 2) First groove forming process 3) Second protective film formation process (second groove formation process) 4)Dividing process 5) Protective film removal process The above steps are carried out in this order to divide the wafer W (see FIGS. 1 and 2) into a plurality of chips C (see FIGS. 14(b) and 15). Each step will be described below.

[0016] 1) First protective film formation process: The first protective film forming step is a step of applying a first liquid resin to the surface of the wafer W to form a first protective film F1 (see FIG. 6) that protects the entire surface of the wafer W, and the first protective film F1 is formed over the entire surface of the wafer W by a protective film forming / removing device 50 provided in the laser processing device 1 shown in FIG. 4. Here, the configurations of the laser processing device 1 shown in FIG. 4 and the protective film forming / removing device 50 shown in FIG. 5 will be described.

[0017] (Configuration of laser processing equipment) 4, the laser processing apparatus 1 includes, as its main components, a chuck table 10 that holds a work set WS, a laser beam application unit 20 that irradiates a laser beam onto a wafer W included in the work set WS held on the chuck table 10, a first transfer means 30 and a second transfer means 40 that transfer the work set WS, and a protective film forming / removing device 50. In addition, the laser processing apparatus 1 includes a cassette 2 placed on a cassette elevator (not shown), a temporary placement section 3 that is arranged near the cassette 2, and a transfer means 4 that transfers the work set WS into and out of the cassette 2.

[0018] Here, the chuck table 10 is a disk-shaped member that can be moved along the X-axis direction by an X-axis moving means (not shown) and can be moved along the Y-axis direction by a Y-axis moving means (not shown). The chuck table 10 is supported so as to be rotatable about a vertical axis. Four clamps 11 are arranged around the periphery of the chuck table 10 at equal angular intervals (90° pitch), and the chuck table 10 can be rotated about a vertical central axis by a rotation mechanism (not shown).

[0019] A support table 6 is erected on the left end (-X axis direction end) of the base 5, and a laser beam application unit 20 is supported on this support table 6. This laser beam application unit 20 includes an oscillator 21 that oscillates a laser beam, a frequency setting unit 22 that sets the repetition frequency of the laser beam, an output adjustment unit 23 that adjusts the output of the laser beam, and a laser head 24 that focuses and emits the laser beam oscillated by the oscillator 21. The laser head 24 is provided so as to be movable in the vertical direction (Z axis direction) relative to the surface of the wafer W held on the chuck table 10.

[0020] (Configuration of protective film forming / removal device) 5, the protective film forming / removing device 50 provided in the laser processing apparatus 1 includes a disk-shaped spinner table 52 disposed inside a drum-shaped container 51 that is open at the top, an electric motor 53 for driving the spinner table 52 to rotate around a vertical axis at a predetermined speed, and a protective film solution supply nozzle 54 and a cleaning liquid spray nozzle 55 that are disposed so as to be horizontally rotatable inside the container 51. The upper surface of the spinner table 52 forms an adsorption surface, which is selectively connected to a suction source (not shown).

[0021] 1 and 2 is placed with the tape T facing downward on the suction surface of a spinner table 52 of a protective film forming / removing device 50 shown in FIG. 5, and the suction surface of the spinner table 52 is then connected to a suction source (not shown). This generates a negative pressure on the suction surface of the spinner table 52, and the work set WS is attracted to this negative pressure and held on the suction surface. Once the work set WS is held on the suction surface of the spinner table 52 in this manner, the protective film solution supply nozzle 54 rotates horizontally, and the opening at its end opens above the center of the wafer W. From this state, a predetermined amount of first liquid resin is dripped onto the center of the top surface of the wafer W.

[0022] As described above, when a predetermined amount of first liquid resin is dropped onto the center of the top surface of the wafer W held together with the work set WS on the suction surface of the spinner table 52, the spinner table 52 and the work set WS held thereon are rotated around the axis by the electric motor 53 at a predetermined speed. Then, the first liquid resin dropped onto the center of the top surface of the wafer W spreads toward the outer periphery of the wafer W due to centrifugal force, and a first protective film F1 of a predetermined thickness is uniformly formed over the entire top surface of the wafer W, as shown in Fig. 6. The entire surface of the wafer W is protected by this first protective film F1. The first liquid resin constituting the first protective film F1 is a water-soluble resin such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP).

[0023] 2) First groove forming process: The first groove forming process is a process of irradiating the surface of the wafer W with a laser beam along streets L1 and L2 (see FIG. 1 ) to remove the first protective film F1 along the streets L1 and L2 while cutting the metal member M to form a first groove G1. Specifically, the position of the chuck table 10 in the Y-axis direction is set by a Y-axis moving means (not shown) so that the laser head 24 is positioned above one of the streets L1 of the wafer W held together with a work set WS on the chuck table 10 of the laser processing apparatus 1 shown in FIG. 4 . From this state, as shown in FIG. 7 , while irradiating the wafer W with a laser beam from the laser head 24 along one street L1 in one direction, the chuck table 10 and the wafer W held thereon are moved in the X-axis direction by an X-axis moving means (not shown). Then, as shown in FIGS. 7 and 8 , the first protective film F1 protecting the top surface of the wafer W is removed along the street L1, and the metal member M is cut, forming a first groove G1 along the street L1.

[0024] By performing the above operation along all the streets L1 in one direction, first grooves G1 are formed on the surface of the wafer W along all the streets L1 in one direction. Then, the chuck table 10 is rotated by an angle of 90° using a rotation mechanism (not shown), and the same operation is repeated to form first grooves G1 on the surface of the wafer W along all the streets L2 in the other direction that are perpendicular to the streets L1 in one direction.

[0025] 3) Second protective film formation process: The second protective film forming process is a process of forming second grooves G2 narrower than the first grooves G1 on the wafer W by applying a second liquid resin to at least the side surfaces of each of the multiple first grooves G1 formed on the surface of the wafer W to form a second protective film F2, as shown in Figures 9 and 10, and includes a second groove forming process of forming the second grooves G2.

[0026] In this second protective film forming process, similarly to the first protective film forming process, the work set WS shown in FIGS. 1 and 2 is placed with the tape T facing downward on the suction surface of the spinner table 52 of the protective film forming / removing device 50 shown in FIG. 5, and from this state, the suction surface of the spinner table 52 is connected to a suction source (not shown). This generates negative pressure on the suction surface of the spinner table 52, and the work set WS is attracted and held on the suction surface by this negative pressure. Then, with the work set WS held on the suction surface of the spinner table 52 in this manner, the protective film solution supply nozzle 54 rotates horizontally, and the opening at its end opens above the center of the wafer W. From this state, a predetermined amount of second liquid resin is dripped onto the center of the surface of the wafer W.

[0027] As described above, when a predetermined amount of the second liquid resin is dropped onto the center of the surface of the wafer W held together with the work set WS on the suction surface of the spinner table 52, the spinner table 52 and the work set WS held thereon are rotated around the axis by the electric motor 53 at a predetermined speed. Then, the second liquid resin dropped onto the center of the surface of the wafer W spreads toward the outer periphery of the surface of the wafer W by centrifugal force. As a result, a second protective film F2 of a predetermined thickness is uniformly formed on the side and bottom surfaces of the first groove G1 on the top surface of the wafer W and on the surface of the first protective film F1 other than the first groove G1, thereby forming a second groove G2 narrower than the first groove G1 on the wafer W. In this case, as shown in detail in FIG. 10, because the side and bottom surfaces of the first groove G1 are protected by the second protective film F2, a portion of the metal member M1 remaining after being cut in the first groove forming process is not exposed to the second groove G2. The second liquid resin constituting the second protective film F2 is a water-soluble resin such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP), similar to the first liquid resin, but this second liquid resin contains a light-absorbing agent.

[0028] The light-absorbing agent absorbs light having a wavelength of 250 nm or more and 400 nm or less, which is the wavelength that is absorbed by the wafer. The light-absorbing agent has the ability to sufficiently absorb light having a wavelength of 355 nm in particular. The light-absorbing agent is, for example, a water-soluble compound having a flavone structure, a flavonol structure, or an isoflavone structure.

[0029] As described above, once the second protective film F2 is formed on the surface of the wafer W except for the side and bottom surfaces of the first grooves G1 and the second grooves G2 of the first protective film F1, as shown in Fig. 11, the second protective film F2 covering the bottom surfaces of the first grooves G1 formed in a grid pattern on the surface of the wafer W is removed by irradiating the second protective film F2 covering the bottom surfaces of the first grooves G1 with a laser beam from the laser head 24 along the street L1. That is, the position of the chuck table 10 in the Y-axis direction is set by a Y-axis moving means (not shown) so that the laser head 24 is positioned above one of the streets L1 (see Fig. 1) of the wafer W held together with the work set WS on the chuck table 10 of the laser processing apparatus 1 shown in Fig. 4. Then, from this state, the chuck table 10 and the wafer W held thereon are moved in the X-axis direction by an X-axis moving means (not shown) while irradiating the laser beam from the laser head 24 along one of the second grooves G2 in one direction of the wafer W. As a result, as shown in FIGS. 11 and 12, the second protective film F2 protecting the bottom surface of the first groove G1 of the wafer W is removed along the street L1.

[0030] By performing the above operation along all the streets L1 in one direction, the second protective film F2 protecting the bottom surface of the first groove G1 formed on the surface of the wafer W is removed along all the streets L1 in one direction. Then, the chuck table 10 of the laser processing apparatus 1 shown in FIG. 4 is rotated by an angle of 90°, and the same operation is repeated to remove the second protective film F2 protecting the bottom surface of the first groove G1 formed on the surface of the wafer W along all the streets L2 in the other direction perpendicular to the streets L1 in one direction.

[0031] In the above-mentioned second protective film forming process, the grid-shaped second grooves G2 are formed on the surface of the wafer W, and the second protective film F2 protecting the bottom surfaces of the first grooves G1 is removed, and then the next dividing process is carried out.

[0032] 4) Splitting process: The dividing step is a step of dividing the wafer W into a plurality of chips C (see FIGS. 14(b) and 15) by plasma etching second grooves G2 in a grid pattern formed on the surface of the wafer W, and a plasma etching apparatus 60 shown in FIG. 13 is used for the plasma etching. Here, the configuration of the plasma etching apparatus 60 will be described below with reference to FIG. 13.

[0033] (Configuration of plasma etching equipment) 13 includes a sealed container-shaped housing 61, and a reduced pressure chamber S formed within the housing 61 accommodates an electrostatic chuck table 62 and a lower electrode 63. A pair of electrodes 64, 65 for electrostatic attraction are embedded in the electrostatic chuck table 62, and DC power supplies 66, 67 are electrically connected to the electrodes 64, 65, respectively. The application of DC voltages from the DC power supplies 66, 67 to the electrodes 64, 65 is controlled on / off by switches SW1, SW2, respectively. A high-frequency power supply 68 is connected to the lower electrode 63, and the application of high-frequency power from the high-frequency power supply 68 to the lower electrode 63 is controlled on / off by switch SW3.

[0034] Furthermore, an upper electrode 69 is provided on the top of the housing 61, and a high-frequency power supply 71 is electrically connected to this upper electrode 69 via a matching box 70. Here, a gas inlet chamber SG is formed inside the upper electrode 69, and this gas inlet chamber SG communicates with the decompression chamber S via a plurality of gas outlets 69a formed in the lower part of the upper electrode 69. A pipe 73 extending from a gas supply means 72 is connected to the gas inlet chamber SG.

[0035] A loading / unloading port 61a is formed on the side of the housing 61 for loading / unloading the work set WS into / from the decompression chamber S, and this loading / unloading port 61a is opened / closed by a gate valve 74. Furthermore, an exhaust port 61b opens at the bottom of the housing 61, and the decompression chamber S inside the housing 61 is connected to an exhaust device 76 via a pipe 75 connected to the exhaust port 61b.

[0036] In the dividing step, the lattice-shaped second grooves G2 (see FIGS. 11 and 12) formed on the surface of the wafer W are plasma etched by the plasma etching apparatus 60 shown in FIG. 13, thereby dividing the wafer W into a plurality of chips C (see FIGS. 14(b) and 15). That is, in the plasma etching apparatus 60 shown in FIG. 13, the gate valve 74 is opened and the work set WS is loaded into the reduced pressure chamber S through the loading / unloading port 61a of the housing 61.

[0037] As described above, the workpiece set WS is carried into the decompression chamber S in the housing 61 and placed with the tape T facing down on the holding surface of the electrostatic chuck table 62 housed in the decompression chamber S. When DC voltages are applied from DC power supplies 66 and 67 to a pair of electrostatic attraction electrodes 64 and 65 provided on the electrostatic chuck table 62, respectively, an electrostatic attraction force is generated on the holding surface of the electrostatic chuck table 62, and the workpiece set WS is attracted and held on the holding surface of the electrostatic chuck table 62 by this electrostatic attraction force.

[0038] In the above state, the pressure in the decompression chamber S is reduced, and while the electrostatic chuck table 62 is cooled by a cooling unit (not shown), the atmosphere in the decompression chamber S is exhausted through a pipe 75 by the exhaust device 76 to evacuate the decompression chamber S, and plasma gas is supplied from the gas supply means 72 through a pipe 73 to the gas inlet chamber SG of the upper electrode 69. Then, the plasma gas is ejected from a plurality of ejection ports 69a opening at the bottom of the upper electrode 69 toward the surface of the wafer W in the decompression chamber S. At this time, the pressure in the decompression chamber S is reduced to a predetermined pressure. Note that, for example, SF6 (a fluorine-based gas) is used as the plasma gas.

[0039] Then, with etching gas supplied to the reduced pressure chamber S in the housing 61 as described above, when high-frequency power is supplied from the high-frequency power supply 71 to the upper electrode 69 via the matching box 70 and from the high-frequency power supply 68 to the lower electrode 63, plasma is generated between the upper electrode 69 and the lower electrode 63 as shown in FIG. 14(a), and the portion of the wafer W not covered by the second protective film F2 (the bottom surface of the second groove G2) is exposed to highly reactive particles in the plasma gas. As shown in FIG. 14(b), this portion is etched, and grid-like grooves G are formed in the wafer W along the streets L1 and L2 (see FIG. 1) over the entire height of the wafer W from the front surface to the back surface. By forming the grid-like grooves G in the wafer W in this way, the wafer W is divided along the grooves G, and a plurality of chips C, each with a device D mounted thereon, are obtained. As shown in FIG. 14(b), the surface of each chip C is covered with the first protective film F1 and the second protective film F2.

[0040] Therefore, when the grid-shaped second grooves G2 (see FIGS. 11, 12, and 14(a)) formed on the surface of the wafer W are plasma-etched using the plasma etching apparatus 60 shown in FIG. 13 in the dividing step, the side surfaces of each first groove G1 are covered with the second protective film F2, as shown in detail in FIG. 12. This prevents metal members M (partial metal members remaining on the wafer W in the second groove forming step) from being exposed in each second groove G2. Therefore, when the second grooves G2 are formed by irradiating the laser beam from the laser head 24 in the second groove forming step, the metal members M do not become debris and adhere to and accumulate on the second protective film F2. As a result, a decrease in the etching rate when dividing the wafer W by plasma etching in the dividing step is prevented, and the wafer W is efficiently divided by plasma etching. Alternatively, the second protective film F2 may be formed by applying a second liquid resin to the side surfaces of the first grooves G1 by inkjet printing, thereby eliminating the need for laser beam irradiation.

[0041] 5) Protective film removal process: The protective film removal process is a process of removing the first protective film F1 and the second protective film F2 remaining on the multiple chips C shown in Figure 14(b) obtained by dividing the wafer W in the division process, and the first protective film F1 and the second protective film F2 remaining on each chip C are removed, for example, in a protective film formation / removal apparatus 50 shown in Figure 5.

[0042] 5, when a work set WS, on which a plurality of divided chips C are held by a tape T, is set on a spinner table 52 with the tape T facing downward, the suction surface of the spinner table 52 is connected to a suction source (not shown). This generates a negative pressure on the suction surface of the spinner table 52, and the work set WS is attracted by this negative pressure and held by suction on the suction surface of the spinner table 52.

[0043] From the above state, the cleaning liquid spray nozzle 55 is rotated horizontally until the nozzle at its end is positioned above the center of the wafer W. Then, the electric motor 53 rotates the spinner table 52 and the work set WS held thereon at a predetermined speed about a vertical central axis, while pure water, which serves as a cleaning liquid, is sprayed from the cleaning liquid spray nozzle 55 toward the chips C held on the work set WS. Here, the first protective film F1 and the second protective film F2 remaining on each chip C are made of a water-soluble resin as described above, and are therefore dissolved and removed by the pure water, finally obtaining the chips C as products shown in FIG. 15. The protective film removal step may also be performed by immersing the wafer W in pure water stored in a water tank to dissolve and remove the protective films.

[0044] 7, when a lattice-shaped first groove G1 is formed on the surface of the wafer W by irradiating the wafer W with a laser beam from the laser head 24, part of the material constituting the substrate of the wafer W becomes debris and adheres to and accumulates on the first protective film F1 due to the irradiation of the wafer W with the laser beam. Also, when a lattice-shaped second groove G2 is formed on the surface of the wafer W by irradiating the wafer W with a laser beam from the laser head 24 in the second groove forming step shown in FIG. 11, when a lattice-shaped second groove G2 is formed on the surface of the wafer W by irradiating the wafer W with a laser beam from the laser head 24, the second protective film F2 containing a light absorbent is removed by irradiating the laser beam onto the second protective film F2.

[0045] As described above, the debris that adheres to and accumulates on the first protective film F1 in the first groove formation process and the debris that adheres to and accumulates on the second protective film F2 in the second groove formation process are removed from the first protective film F1 and the second protective film F2 in the protective film removal process, so no debris remains on each chip C as a product shown in Figure 15, and performance degradation of the chip C due to remaining debris is reliably prevented.

[0046] As is clear from the above explanation, according to the method for dividing a wafer W according to the present invention, in the first groove forming step, the first groove G1 is formed by cutting the metal member M while removing the first protective film F1 along the streets L1, L2. At least the side surfaces of the first groove G1 are protected by the second protective film F2 in the subsequent second protective film forming step, and the metal member M is not exposed on the side surfaces. Therefore, when the second groove G2 is formed by irradiating a laser beam, the metal member M does not become debris and adhere to and accumulate on the second protective film F2. Therefore, a decrease in the etching rate when dividing the wafer W by plasma etching in the dividing step is prevented, and the effect of being able to divide the wafer W efficiently by plasma etching is obtained.

[0047] In the above embodiment, the first protective film F1 and the second protective film F2 remaining on the multiple chips C obtained by dividing the wafer W in the dividing process are simultaneously removed in the protective film removal process performed after the dividing process. However, the first protective film removal process may be performed between the first protective film formation process shown in FIG. 6 and the first groove formation process shown in FIG. 7, and the first protective film F1 formed on the surface of the wafer W in the first protective film formation process may be removed.

[0048] Furthermore, the present invention is not limited to the application of the above-described embodiments, and it goes without saying that various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0049] 1: laser processing device, 2: cassette, 3: temporary storage section, 4: carrying-in / out means, 5: base, 6: Support table, 10: Chuck table, 11: Clamp, 20: laser beam irradiation unit, 21: oscillation unit, 22: frequency setting unit, 23: output adjustment unit, 24: laser head, 30: first conveying means, 40: second conveying means, 50: protective film forming / removing device, 51: container, 52: spinner table, 53: electric motor, 54: protective film solution supply nozzle, 55: cleaning solution spray nozzle, 60: plasma etching device, 61: housing, 61a: loading / unloading entrance, 61b: exhaust port, 62: electrostatic chuck table, 63: lower electrode, 64, 65: electrodes, 66,67: DC power supply, 68: High frequency power supply, 69: Upper electrode, 69a: Jet nozzle, 70: Matching box, 71: High frequency power supply, 72: Gas supply means, 73: Pipe, 74: Gate valve, 75: Piping, 74: Exhaust device, C: Chip, D: Device, F: Ring frame, F1: First protective film, F2: Second protective film G: groove, G1: first groove, G2: second groove, L1, L2: street, M: metal member, S: Decompression chamber, SG: Gas inlet chamber, SW1, SW2: Switch, W: Wafer, WS: Workset

Claims

1. A wafer dividing method for dividing a wafer, which has metal members formed on a surface along grid-like streets, into a plurality of chips along the streets, comprising the steps of: a first protective film forming step of applying a first liquid resin onto a surface of the wafer to form a first protective film for protecting the entire surface of the wafer; a first groove forming step of irradiating a laser beam along the streets onto the surface of the wafer to cut the metal member while removing the first protective film along the streets, thereby forming first grooves; a second protective film forming step of forming a second groove narrower than the first groove by applying a second liquid resin to at least a side surface of the first groove to form a second protective film; dividing the wafer into a plurality of chips by plasma etching the second grooves; A method for dividing a wafer, comprising the steps of:

2. The second protective film forming step includes:

2. The method for dividing a wafer according to claim 1, further comprising a second groove forming step of forming the second protective film also on a bottom surface of the first groove, and forming the second groove in which the second protective film formed on the bottom surface of the first groove has been removed by irradiating a laser beam along the first groove between the second protective film forming step and the dividing step.

3. 2. The method for dividing a wafer according to claim 1, wherein the second protective film contains a light absorbing agent.

4. 2. The wafer dividing method according to claim 1, further comprising the step of: after said dividing step, performing a protective film removing step of removing said first protective film and said second protective film formed on said upper surface of said wafer.

5. a first protective film removing step of removing the first protective film is carried out between the first protective film forming step and the first groove forming step; 2. The wafer dividing method according to claim 1, wherein the second protective film forming step forms the second protective film on at least the side surface of the first groove and on the front surface of the wafer.

Images