Wafer division method

Abstract

To effectively and efficiently remove fluoride products adhering to a mask. [Solution] By irradiating the mask with oxygen-containing plasma P in the removal step, the fluorination products D adhering to the mask 17 in the division step can be removed. Therefore, by spraying cleaning water onto the surface 11 of the wafer 10 in the cleaning step, the mask 17 can be effectively removed and the surface 11 can be effectively cleaned. Furthermore, when fluoride plasma generated by the reaction between the oxygen-containing plasma and the fluorination products D is no longer detected, it is determined that the fluorination products D have been removed from the mask 17, and the removal step is terminated. This allows the removal step to be terminated at an appropriate timing. Therefore, the fluorination products D adhering to the mask 17 can be effectively and efficiently removed.

Description

[Technical Field]

[0001] The present invention relates to a method for dividing a wafer. [Background technology]

[0002] Patent Documents 1 and 2 disclose methods for dividing a wafer using plasma. In these methods, when the wafer is plasma diced, a protective film (mask) made of a water-soluble resin is formed on the surface of the wafer to protect the device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-103330 [Patent Document 2] Japanese Patent Application Publication No. 2018-041935 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, when a wafer is plasma diced, fluoride products adhere to the surface of the mask. Because these fluoride products are insoluble in cleaning water, it is difficult to remove the mask with the fluoride products adhered to it and clean the surface of the wafer simply by spraying cleaning water.

[0005] Therefore, an object of the present invention is to remove fluoride products adhering to a mask during plasma dicing, thereby removing the mask with cleaning water and effectively cleaning the surface of the wafer. [Means for solving the problem]

[0006] The wafer dividing method of the present invention (the present dividing method) is a wafer dividing method in which a wafer having devices formed in areas partitioned by streets is irradiated with an etching plasma containing a plasmatized fluorine-based gas to divide the wafer along the streets, and includes the following steps: a supporting step in which a supporting member is attached to the surface of the wafer opposite to the surface on which the streets are formed, thereby supporting the wafer with the supporting member; a mask forming step in which a water-soluble liquid resin is applied to the devices and dried to form a mask on the surface of the devices and expose the streets; and after the mask forming step: The method includes a dividing step of forming dividing grooves along the streets by irradiating the mask side of the wafer with the etching plasma, a removal step of removing fluoride products adhered to the surface of the mask in the dividing step by irradiating the surface of the mask with oxygen-containing plasma, and a cleaning step of, after the removal step, cleaning the upper surface of the wafer while removing the mask by spraying cleaning water onto the upper surface of the wafer, and includes a recognition step of recognizing that the fluoride products have been removed when fluoride plasma generated by a reaction between the oxygen-containing plasma and the fluoride products is not detected in the removal step. [Effects of the Invention]

[0007] In this dividing method, the fluoride products adhering to the mask in the dividing step can be effectively removed by irradiating the mask with oxygen-containing plasma in the removing step. Therefore, by spraying cleaning water onto the surface of the wafer in the cleaning step, the mask can be effectively removed and the surface of the wafer can be effectively cleaned.

[0008] Furthermore, in this dividing method, in the recognition step of the removal step, it is recognized that the fluoride products have been removed from the mask when fluoride plasma generated by the reaction between the oxygen-containing plasma and the fluoride products is no longer detected. Therefore, since it is possible to appropriately recognize that the fluoride products have been removed from the mask, the removal step can be terminated at an appropriate time. This effectively prevents the removal step from being terminated while the fluoride products remain on the mask, and prevents the removal step from being continued even though the fluoride products have been removed from the mask. Therefore, in this dividing method, it is possible to effectively and efficiently remove the fluorination products that have adhered to the mask during the dividing step. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. [Figure 2] FIG. 10 is an explanatory view showing a resin application step in the mask formation step. [Figure 3] FIG. 10 is an explanatory diagram showing a laser irradiation step in the mask formation step. [Figure 4] FIG. 1 is an overall schematic view of an etching apparatus. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1, a wafer 10 according to this embodiment is, for example, a disk-shaped or rectangular plate-shaped semiconductor wafer, and has a front surface 11 and a back surface 12. A grid-like street 14 is formed on the front surface 11 of the wafer 10, and devices 15 are formed in areas defined by the streets 14.

[0011] The wafer dividing method in this embodiment is a method of dividing the wafer 10 along the streets 14 by irradiating the wafer 10 with etching plasma containing a plasmatized fluorine-based gas. This dividing method includes a supporting step, a mask forming step, a dividing step, a removing step, and a cleaning step, and the removing step further includes a recognition step.

[0012] [Support process] In the dividing method of this embodiment, a supporting step is first carried out. In this step, a supporting member is attached to the back surface 12 of the wafer 10, which is the surface opposite to the front surface 11 on which the streets 14 are formed, and the wafer 10 is supported by the supporting member.

[0013] 1, a wafer 10 and an annular ring frame 22 having a diameter larger than that of the wafer 10 are placed on a predetermined table (not shown). Then, a sheet-like support member 20 is attached to the back surface 12 of the wafer 10 and the back surface 23 of the ring frame 22.

[0014] The support member 20 is, for example, a dicing tape having an adhesive layer. The support member 20 has an area larger than the back surface 12 of the wafer 10, and is attached across the wafer 10 and the ring frame 22. As a result, a processing target unit (work set) 25 is formed in which the wafer 10, support member 20, and ring frame 22 are integrated, and the wafer 10 is supported by the support member 20 and ring frame 22.

[0015] The support member 20 may be a sheet that melts when heated to a predetermined temperature or higher and is thermally welded to the object. When such a sheet is used, the support member 20 is attached to the wafer 10 and the ring frame 22 by thermal welding.

[0016] [Mask formation process] After the supporting step, a mask forming step is performed. In this step, a water-soluble liquid resin is applied to the devices 15 on the wafer 10 and dried to form a mask on the surface of the devices 15 and expose the streets 14. This mask forming step includes a resin application step and a laser irradiation step.

[0017] (Resin application process) 2, in the resin application process, first, an operator or a conveying device (not shown) places the processed unit 25 on the holding surface 32 of the holding table 30 of the film forming and cleaning apparatus 1 so that the front surface 11 of the wafer 10 faces upward. Thereafter, the control unit 33 of the film forming and cleaning apparatus 1 connects the holding surface 32 to a suction source (not shown), whereby the wafer 10 is suction-held on the holding surface 32 via the support member 20.

[0018] Next, the control unit 33 positions the resin supply nozzle 35 connected to the liquid resin supply source 31 above the holding table 30 and supplies liquid resin 34 from the resin supply nozzle 35 near the center of the surface 11 of the wafer 10.

[0019] After a predetermined amount of liquid resin 34 has been supplied to the front surface 11 of the wafer 10, the control unit 33 rotates the holding table 30 about a central axis parallel to the vertical direction, causing the liquid resin 34 to spread toward the periphery of the front surface 11 due to centrifugal force, and to be applied to the entire surface 11, including the surfaces of the devices 15.

[0020] After the liquid resin 34 has been applied, the control unit 33 positions the air nozzle 37 connected to the air source 36 above the holding table 30. Then, the control unit 33 blows air from the air nozzle 37 toward the liquid resin 34 applied to the front surface 11 of the wafer 10 held on the rotating holding table 30. This dries the liquid resin 34, forming the protective film 16 shown in FIG.

[0021] Here, examples of the liquid resin 34 that is a water-soluble resin include polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG).

[0022] (Laser irradiation process) After the resin application step, the laser irradiation step is carried out. In this step, as shown in Fig. 3, an operator or a transfer device (not shown) places the processed unit 25 that has been subjected to the resin application step on the holding surface 42 of the chuck table 40 of the laser processing device 2 with the front surface 11 of the wafer 10 facing upward. Thereafter, the control unit 45 of the laser processing device 2 connects the holding surface 42 to a suction source (not shown), whereby the wafer 10 is suction-held on the holding surface 42 via the support member 20.

[0023] Next, the control unit 45 places the laser irradiation unit 41 above the chuck table 40. In the laser processing device 2, the chuck table 40 and the laser irradiation unit 41 are provided so as to be relatively movable in the horizontal direction. In this embodiment, the chuck table 40 is movable in the X-axis direction and rotatable in the horizontal direction by a table movement mechanism 43. Furthermore, the laser irradiation unit 41 is movable in the Y-axis direction by a laser movement mechanism 44.

[0024] The control unit 45 then confirms the position of the street 14 through the transparent protective film 16 using the camera 46, and adjusts the positions of the laser irradiation unit 41 and the chuck table 40 using the table movement mechanism 43 and the laser movement mechanism 44, thereby positioning the processing start position of one street 14 on the wafer 10 held on the chuck table 40 directly below the laser irradiation unit 41. The control unit 45 also adjusts the focus of the laser irradiation unit 41 so that the focus of the laser beam LB emitted from the laser irradiation unit 41 is positioned near the front surface 11 of the wafer 10.

[0025] Next, the control unit 45 causes the laser irradiation unit 41 to irradiate the laser beam LB, and also causes the focal point of the laser beam LB and the wafer 10 to move relatively along the street 14. In this embodiment, the control unit 45 causes the table movement mechanism 43 to process and feed the wafer 10 in the X-axis direction, thereby moving the wafer 10 along the street 14 relative to the focal point of the laser beam LB. As a result, the laser beam LB is irradiated onto the entire area of ​​one street 14.

[0026] Thereafter, the control unit 45 controls the table moving mechanism 43 and the laser moving mechanism 44 to position the processing start position of another street 14 on the wafer 10 directly below the laser irradiation unit 41, and irradiates the laser beam LB onto this street 14. In this way, the control unit 45 irradiates all the streets 14 on the front surface 11 of the wafer 10 with the laser beam LB.

[0027] Here, the laser beam LB has a wavelength that is absorbed by the protective film 16 and the wafer 10. Therefore, when the laser beam LB is irradiated onto the wafer 10, ablation occurs in the protective film 16 and the surface 11 of the wafer 10, and these are partially etched. As a result, the protective film 16 is removed along the streets 14 of the wafer 10, and the streets 14 are exposed. In other words, the protective film 16 that is not removed forms a mask 17 that covers the surfaces of the devices 15 and protects the devices 15. The mask 17 may be formed by applying a water-soluble liquid resin only to the surface of the device 15 using an inkjet method or a stamp method, etc. In this case, the laser irradiation step is not required.

[0028] [Dividing process] After the mask formation step, a division step is performed using an etching apparatus 50 shown in FIG.

[0029] First, we will explain the configuration of the etching apparatus 50. The etching apparatus 50 has a chamber 51, and a lower electrode unit 60 and an upper electrode unit 70 that form an electric field.

[0030] A loading / unloading port 53 for loading and unloading the processing unit 25 is formed in a side wall 52 of the chamber 51. In addition, a shutter mechanism 55 for opening and closing the loading / unloading port 53 is attached to the outer wall surface of the side wall 52.

[0031] The shutter mechanism 55 includes a cylinder 56 and a shutter 57 connected to the upper end of the cylinder 56. In the shutter mechanism 55, the cylinder 56 moves the shutter 57 up and down along the side wall 52, thereby opening and closing the loading / unloading opening 53. When the loading / unloading opening 53 is closed by the shutter 57, an airtight space is formed within the chamber 51.

[0032] The lower electrode unit 60 and the upper electrode unit 70 are disposed in the chamber 51 so as to face each other in the vertical direction.

[0033] The lower electrode unit 60 includes a conductive support column 62 that penetrates the bottom wall 54 of the chamber 51, and a dielectric holding table 63 that is provided on the upper end of the support column 62. The upper surface of the holding table 63 serves as a holding surface 631 for holding the machined unit 25. A plurality of suction ports 64 are formed in the holding surface 631. The suction ports 64 are connected to a suction source 66 via suction paths 65 in the holding table 63 and the support column 62. The suction ports 64 are connected to the suction source 66, so that the machined unit 25 is sucked and held by the holding surface 631 that includes the suction ports 64.

[0034] An internal electrode 69 is embedded in the holding table 63. When a voltage is applied to the internal electrode 69, static electricity is generated on a holding surface 631 of the holding table 63, and the wafer 10 is electrostatically attracted to the holding surface 631. In other words, the holding surface 631 of the holding table 63 also functions as a holding surface of an electrostatic chuck.

[0035] Furthermore, a cooling path 68 is formed inside the holding table 63 to pass cooling water sent out from the cooling unit 67. During etching, heat generated in the holding table 63 is transferred to the cooling water, preventing the temperature of the holding table 63 from rising abnormally.

[0036] The upper electrode unit 70 includes a conductive support 72 that penetrates the top wall 58 of the chamber 51, and a conductive jet table 73 that is provided at the lower end of the support 72. The jet table 73 introduces gas into the chamber 51, and has a plurality of gas jet ports 74 formed on its lower surface.

[0037] The gas outlet 74 is connected to a reactive gas supply source 81, an inert gas supply source 82, and an oxygen gas supply source 83 via gas flow paths 75 provided inside the ejection table 73 and the support 72. Supply valves 84 to 86 are provided in the pipelines of the reactive gas supply source 81, the inert gas supply source 82, and the oxygen gas supply source 83, respectively. By controlling the opening and closing of the supply valves 84 to 86, the gas supply source (gas supplier) connected to the gas outlet 74 can be switched. Note that the gas supply sources 81 to 83 may be configured to supply gas into the chamber 51 via different pipelines.

[0038] The reactive gas from the reactive gas supply source 81 may be a stable fluorine-based gas containing fluorine, such as sulfur hexafluoride (SF), tetrafluoromethane (CF), or nitrogen trifluoride (NF). The inert gas from the inert gas supply source 82 may be, for example, nitrogen (N), helium (He), or argon (Ar).

[0039] The upper end side of the support column 72 is connected to a ball screw type lifting drive mechanism 59. The lifting drive mechanism 59 is provided on the upper wall 58 of the chamber 51 and protrudes upward from the chamber 51. By driving the lifting drive mechanism 59, the upper electrode unit 70 is moved closer to or farther from the lower electrode unit 60. This adjusts the height of the jet table 73 to an appropriate position relative to the wafer 10 on the holding table 63.

[0040] An exhaust port 541 is formed below the holding table 63 on the bottom wall 54 of the chamber 51, and a vacuum pump 542 is connected to this exhaust port 541 via piping. The vacuum pump 542 is used to reduce the pressure inside the chamber 51 to a negative pressure by sucking in the air and / or plasma gas inside the chamber 51. A pressure gauge 543 that detects the pressure inside the chamber 51 is provided in the piping between the exhaust port 541 and the vacuum pump 542.

[0041] The etching apparatus 50 also has a power supply control unit 87 electrically connected to the lower electrode unit 60. The power supply control unit 87 has a high-frequency power supply 88 and a frequency switching unit 89. The high-frequency power supply 88 is used to apply a high-frequency voltage between the lower electrode unit 60 and the upper electrode unit 70. The frequency switching unit 89 controls the supply and stop of high-frequency power from the high-frequency power supply 88. The upper electrode unit 70, which is disposed opposite the lower electrode unit 60, is grounded.

[0042] The etching apparatus 50 also has a fluoride plasma detection sensor 76 at a location on the sidewall 52 of the chamber 51 facing the loading / unloading port 53. The fluoride plasma detection sensor 76 detects fluoride plasma formed by a reaction between oxygen-containing plasma and a fluoride product (polymer). For details of the fluoride plasma detection sensor 76, see, for example, Japanese Patent Application Laid-Open No. 2012-222225.

[0043] The etching apparatus 50 further includes a control unit 77. The control unit 77 includes a CPU that performs calculations according to a program, a storage medium such as a memory, etc. The control unit 77 controls the components of the etching apparatus 50 described above to perform the dividing step and the cleaning step on the wafer 10.

[0044] The following describes the dividing step controlled by the control unit 77. In this step, dividing grooves are formed along the streets 14 by irradiating the mask 17 side of the wafer 10 with etching plasma.

[0045] Specifically, first, before the wafer 10 is loaded into the chamber 51, the control unit 77 opens the supply valve 85 of the inert gas supply source 82 to supply the inert gas from the upper electrode unit 70 into the sealed chamber 51.

[0046] Next, the control unit 77 opens the shutter 57, and uses a transfer device (not shown) to load the processed unit 25 that has undergone the mask formation process into the chamber 51, and holds the wafer 10 on the holding table 63 of the lower electrode unit 60 so that the front surface 11 of the wafer 10 faces upward, as shown in Fig. 4. Thereafter, the control unit 77 closes the loading / unloading port 53 with the shutter 57, thereby sealing the chamber 51. Furthermore, the control unit 77 closes the supply valve 85 to stop the supply of inert gas.

[0047] Next, the control unit 77 adjusts the inter-electrode distance by moving the upper electrode unit 70 closer to the lower electrode unit 60 using the lifting drive mechanism 59. The control unit 77 also drives the vacuum pump 542 to reduce the pressure inside the chamber 51 (to a negative pressure state). Thereafter, the control unit 77 opens the supply valve 84 of the reactive gas supply source 81 to irradiate the reactive gas onto the mask 17 side (front surface 11 side) of the wafer 10 from the gas outlets 74 of the upper electrode unit 70. The control unit 77 also controls the high-frequency power supply 88 to apply a high-frequency voltage between the upper electrode unit 70 and the lower electrode unit 60 during irradiation of the reactive gas.

[0048] As a result, the reactive gas is converted into plasma (radicalized) by the high-frequency voltage, generating an etching plasma EP containing a fluorine-based gas, which is irradiated onto the mask 17 side of the wafer 10, as shown in FIG. 5. As a result, exposed streets 14, which are regions of the surface 11 of the wafer 10 where the mask 17 is not formed, are irradiated with the etching plasma EP and dry-etched by a radical chain reaction. As a result, division grooves 18 are formed along the streets 14 to a depth sufficient to cut the wafer 10. As a result, multiple chips each having one device 15 are formed. After the division grooves 18 are formed, the control unit 77 closes the supply valve 84 of the reactive gas supply source 81, thereby completing the division process.

[0049] In this manner, in the dividing step, plasma dicing is performed to divide the wafer 10 along the streets 14. In the dividing step, the surface of the mask 17 (for example, the edge portion and the upper surface of the mask 17) may be altered by a reaction caused by the plasma dicing, and a fluoride product D (see FIG. 5) may adhere to the surface of the mask 17. In this embodiment, in order to remove the fluoride product D thus adhered to the surface of the mask 17 from the mask 17, a removing step is carried out after the dividing step.

[0050] [Removal process] In the removal step carried out after the dividing step, the surface of the mask 17 is irradiated with oxygen-containing plasma to remove the fluorination product D that has adhered to the surface of the mask 17 in the dividing step.

[0051] Specifically, after the dividing step, the control unit 77 opens the supply valve 86 of the oxygen gas supply source 83 in the etching apparatus 50 shown in Fig. 4 to irradiate oxygen gas from the upper electrode unit 70 toward the processed unit 25 (wafer 10) held on the holding table 63. The oxygen gas is converted into plasma by a high-frequency voltage applied between the upper electrode unit 70 and the lower electrode unit 60 by a high-frequency power supply 88.

[0052] As a result, as shown in FIG. 6, the mask 17 of the wafer 10 is irradiated with the plasma P containing oxygen, and the fluorination products D adhering to the surface of the mask 17 are removed by oxygen plasma ashing.

[0053] In this oxygen plasma ashing, fluoride plasma is generated by a reaction between the oxygen-containing plasma P and the fluoride product D. In this embodiment, the control unit 77 uses this fluoride plasma to perform the recognition step in the removal step.

[0054] In this recognition step, the control unit 77 recognizes that the fluoride product D has been removed by not detecting the fluoride plasma generated by the reaction between the oxygen-containing plasma P and the fluoride product D.

[0055] Specifically, in the removal step, the control unit 77 uses the fluoride plasma detection sensor 76 shown in Fig. 4 to intermittently or continuously detect the presence or absence of fluoride plasma in the chamber 51 (for example, the concentration of fluoride plasma). When the fluoride plasma is no longer detected in the chamber 51 (for example, when the concentration of fluoride plasma in the chamber 51 becomes equal to or lower than a threshold value), the control unit 77 recognizes that the reaction between the oxygen-containing plasma P and the fluoride product D has ceased, i.e., that the fluoride product D has been removed from the mask 17. In response to this recognition result, the control unit 77 closes the supply valve 86 to stop the irradiation of oxygen gas and also stops the application of the high-frequency voltage by the high-frequency power supply 88, thereby terminating the removal step including the recognition step.

[0056] [Cleaning process] After the removal step, a cleaning step is carried out, in which cleaning water is sprayed onto the surface 11, which is the upper surface of the wafer 10, to clean the surface 11 of the wafer while removing the mask 17.

[0057] 7, an operator or a transport device (not shown) places the processed unit 25 that has undergone the removal process on the holding surface 32 of the holding table 30 of the film forming and cleaning apparatus 1, with the front surface 11 of the wafer 10 facing upward. Thereafter, the control unit 33 of the film forming and cleaning apparatus 1 connects the holding surface 32 to a suction source (not shown), whereby the wafer 10 is suction-held on the holding surface 32 via the support member 20.

[0058] Thereafter, the control unit 33 of the film forming and cleaning apparatus 1 rotates the holding table 30 about a rotation axis extending in the vertical direction. Furthermore, the control unit 33 positions a cleaning nozzle 39 connected to a cleaning water supply source 38 above the rotating holding table 30, and supplies cleaning water L from the cleaning nozzle 39 to the front surface 11 of the wafer 10. This cleaning water L can be pure water or a chemical liquid such as acetone.

[0059] As a result, the mask 17 on the wafer 10 is dissolved by the cleaning water L, and is removed (peeled) from the device 15 on the wafer 10 by the centrifugal force of the rotating holding table 30. The front surface 11, which is the upper surface of the wafer 10, is also cleaned by the cleaning water L. Thereafter, the control unit 33 blows air from the air nozzle 37 toward the wafer 10. As a result, the front surface 11 of the wafer 10 is dried.

[0060] As described above, in this embodiment, by irradiating the surface of the mask 17 with oxygen-containing plasma P in the removal step, the fluorination product D that adheres to the mask 17 in the division step can be effectively removed. Therefore, by spraying cleaning water L onto the surface 11 of the wafer 10 in the cleaning step, it is possible to effectively remove the mask 17 and effectively clean the surface 11 of the wafer 10 with the cleaning water.

[0061] Furthermore, in this embodiment, when the control unit 77 no longer detects the fluoride plasma generated by the reaction between the oxygen-containing plasma P and the fluoride product D in the recognition step of the removal step, it determines that the fluoride product D has been removed from the mask 17, and ends the removal step. This allows the removal step to be ended at an appropriate timing.

[0062] Therefore, in this embodiment, it is possible to effectively prevent the removal process from being terminated while the fluorination product D remains on the mask 17, and to prevent the removal process from being continued even though the fluorination product D has been removed from the mask 17.

[0063] In this manner, in this embodiment, the fluorination product D that has adhered to the mask 17 during the dividing step (plasma dicing) can be removed well and efficiently.

[0064] In the removal process, the control unit 77 may perform both continuous and pulse irradiation of the oxygen-containing plasma P. Continuous irradiation is plasma irradiation that maintains a constant electric field, while pulse irradiation is plasma irradiation that uses a time-modulated pulsed electric field. The frequency of the pulse irradiation is set to 0.5 Hz or higher and 5000 Hz or lower (e.g., 1 Hz to 2 Hz). The control unit 77 switches the frequency of the pulse irradiation, for example, by controlling the supply and stop of high-frequency power using the frequency switching unit 89 (see FIG. 4) of the power supply control unit 87. The frequency of the high-frequency power for generating plasma is, for example, 13.56 MHz.

[0065] This makes it possible to suppress thermal alteration of the mask 17 due to oxygen plasma ashing, compared to when only continuous irradiation of the oxygen-containing plasma P is performed. Furthermore, with pulse irradiation, while the oxygen-containing plasma P is stopped or reduced, thermal energy on the surface of the mask 17 is dispersed, thereby suppressing a temperature rise of the mask 17. This makes it possible to suppress thermal alteration of the mask 17. Therefore, the mask 17 can be successfully removed in the cleaning process, eliminating the need for a process of scraping off the mask 17 and improving productivity.

[0066] It is preferable that the irradiation time of pulsed irradiation is longer than that of continuous irradiation. As for the ratio, if the irradiation time of continuous irradiation is "1", the irradiation time of pulsed irradiation may be "9". This can more effectively suppress thermal deterioration of mask 17.

[0067] In this embodiment, the removal step is performed by an etching apparatus 50 shown in Fig. 4. This etching apparatus 50 is a capacitively coupled plasma etching apparatus (CCP: Capacitively Coupled Plasma). In this regard, the etching apparatus used to perform the removal step may be an inductively coupled plasma etching apparatus (ICP: Inductively Coupled Plasma) or an electron cyclotron resonance plasma etching apparatus (ECR: Electron Cyclotron Resonance).

[0068] The removal step may also be performed by an oxygen plasma irradiation device equipped with a nozzle (plasma irradiation nozzle) that irradiates oxygen-containing plasma. In this configuration, oxygen-containing plasma is irradiated from the plasma irradiation nozzle disposed above the wafer 10, while the plasma irradiation nozzle and the wafer 10 are moved relatively in the horizontal direction, so that the plasma is irradiated onto the entire surface 11 of the wafer 10. As a result, the fluorination product D on the mask 17 is removed by oxygen plasma ashing.

[0069] 5, in the dividing step, dividing grooves 18 having a depth sufficient to divide the wafer 10 are formed in the wafer 10. In this regard, in the dividing step, dividing grooves 18 having a depth sufficient not to divide the wafer 10 may be formed. In this case, for example, after the cleaning step, the wafer 10 can be divided along the dividing grooves 18 by expanding the support member 20 or grinding the back surface 12 of the wafer 10. [Explanation of symbols]

[0070] 1: Film forming and cleaning device, 2: Laser processing device, 10: Wafer, 11: Front surface, 12: Back surface, 14: Street, 15: Device, 16: Protective film, 17: Mask, 18: Dividing groove, 20: Support member, 22: Ring frame, 23: Back surface, 25: Processing target unit, 30: Holding table, 31: Liquid resin supply source, 32: Holding surface, 33: Control unit, 34: liquid resin, 35: resin supply nozzle, 36: air source, 37: air nozzle, 38: cleaning water supply source, 39: cleaning nozzle, 40: chuck table, 41: laser irradiation unit, 42: holding surface, 43: table movement mechanism, 44: laser movement mechanism, 45: Control unit, 50: Etching device, 51: Chamber, 52: Side wall, 53: Loading / unloading port, 54: Bottom wall, 55: shutter mechanism, 56: cylinder, 57: shutter, 58: upper wall, 59: lifting drive mechanism, 60: lower electrode unit, 62: support part, 63: holding table, 64: Suction port, 65: Suction path, 66: Suction source, 67: Cooling section, 68: Cooling path, 69: internal electrode, 70: upper electrode unit, 72: support part, 73: ejection table, 74: gas outlet, 75: gas flow path, 76: fluoride plasma detection sensor, 77: control unit, 81: reactive gas supply source, 82: inert gas supply source, 83: oxygen gas supply source, 84: supply valve, 85: supply valve, 86: supply valve, 87: power supply control unit, 88: High frequency power supply, 89: Frequency switching section, 541: Discharge port, 542: Vacuum pump, 543: pressure gauge, 631: holding surface, D: fluorination product, EP: etching plasma, L: cleaning water, LB: laser beam, P: plasma

Claims

[Claim 1] A wafer dividing method comprising: irradiating an etching plasma containing a fluorine-based gas in plasma onto a wafer having devices formed in areas defined by streets, thereby dividing the wafer along the streets, the method comprising: a supporting step of supporting the wafer with a support member by adhering the support member to a surface of the wafer opposite to the surface on which the streets are formed; a mask forming step of applying a water-soluble liquid resin to the device and drying the resin to form a mask on the surface of the device and expose the streets; a dividing step of forming dividing grooves along the streets by irradiating the etching plasma onto the mask side of the wafer after the mask forming step; a removing step of removing the fluorine product adhered to the surface of the mask in the dividing step by irradiating the surface of the mask with oxygen-containing plasma; a cleaning step of, after the removing step, spraying cleaning water onto the upper surface of the wafer to remove the mask and clean the upper surface of the wafer, the removal step includes a recognition step of recognizing that the fluoride product has been removed by detecting that fluoride plasma generated by the reaction between the oxygen-containing plasma and the fluoride product is not detected; Wafer division method.

Images