Wafer processing method and protective film agent

Abstract

To suppress peeling when a mask is formed.SOLUTION: A wafer processing method is a processing method of a wafer in which devices are formed in each region on surfaces partitioned by a plurality of crossing scheduled dividing lines, and includes: a protective film formation step 1001 of coating the surface of the wafer with a non-polymerization resin, and forming a protective film composed of the non-polymerization resin; a mask formation step 1002 for emitting a laser beam, forming an opening in the protective film, and forming a mask, after execution of the protective film formation step 1001; and an etching step 1003 for subjecting the wafer to etching through the mask, after execution of the mask formation step 1002.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] The present invention relates to a method for processing a wafer and a protective film agent in which devices are respectively formed in each region of a surface partitioned by a plurality of intersecting planned division lines.

Background Art

[0002] Semiconductor devices are formed by dividing a wafer on which a plurality of semiconductor devices are formed, and the wafer is divided using a cutting device equipped with a cutting blade or a laser processing device. In recent years, so-called plasma dicing in which a wafer is divided by irradiating the wafer with a plasmaized gas and etching only the region along the planned division line has also been performed.

[0003] In plasma dicing, a mask exposing only the planned division line is formed on the wafer. In order to facilitate removal of the mask after plasma etching, a method of forming the mask with a water-soluble resin is used (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0007] To solve the above-mentioned problems and achieve the objective, the present invention provides a wafer processing method in which a device is formed in each region of the surface partitioned by a plurality of intersecting division lines, wherein the surface of the wafer is coated with a nonpolymerized resin. A protective film agent comprising a solvent that dissolves the resin. Cover with, The protective film agent is dried, A protective film forming step of forming a protective film made of the nonpolymerized resin, and after performing the protective film forming step, irradiating the protective film with a laser beam. Expose the line to be divided. A mask forming step involves forming an opening to create a mask, and after performing the mask forming step, etching is performed on the wafer through the mask. Then, the surface of the line to be divided is etched to divide the wafer into chips. It is characterized by comprising an etching step.

[0008] In the wafer processing method described above, the etching step may involve plasma etching of the wafer through the mask.

[0009] The wafer processing method may also include a mask removal step in which, after performing the etching step, the mask of the wafer is covered with the resin to form a release resin layer on the mask, and then the release resin layer is peeled off the wafer to remove the mask together with the release resin layer.

[0010] The protective film agent of the present invention is A wafer processing method in which devices are formed in each region of a surface partitioned by a plurality of intersecting division lines, comprising: a protective film forming step of covering the surface of the wafer with a nonpolymerized resin to form a protective film made of the nonpolymerized resin; a mask forming step of irradiating the protective film with a laser beam after performing the protective film forming step to form an opening in the protective film and form a mask; and an etching step of etching the wafer through the mask after performing the mask forming step. A protective film agent used in a wafer processing method, characterized by comprising a non-polymerized resin, a solvent for dissolving the resin, and a light-absorbing material having absorption properties with respect to the wavelength of the laser beam.

[0011] In the protective film agent, the resin may be a terpene resin. [Effects of the Invention]

[0012] This invention has the effect of suppressing peeling during the formation of a mask. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a perspective view showing an example of a workpiece to be processed in the wafer processing method according to Embodiment 1. [Figure 2] Figure 2 is a flowchart showing the flow of the wafer processing method according to Embodiment 1. [Figure 3] Figure 3 is a schematic perspective view showing the protective film formation step of the wafer processing method shown in Figure 2, where tape is attached to the back surface of the wafer and a frame is attached to the outer edge of the tape. [Figure 4] Figure 4 is a schematic side view showing, in a partial cross-section, the state in which a protective film agent is applied to the entire surface of the wafer during the protective film formation step of the wafer processing method shown in Figure 2. [Figure 5] Figure 5 is a perspective view showing a wafer with a protective film formed on its surface during the protective film formation step of the wafer processing method shown in Figure 2. [Figure 6] Figure 6 is a schematic side view showing a partial cross-section of the mask formation step of the wafer processing method shown in Figure 2. [Figure 7] Figure 7 is a schematic cross-sectional view showing the wafer after the mask formation step of the wafer processing method shown in Figure 2. [Figure 8] Figure 8 is a schematic cross-sectional view showing an example of the configuration of an etching apparatus that performs the etching step of the wafer processing method shown in Figure 2. [Figure 9] Figure 9 is a schematic cross-sectional view showing the wafer after the etching step of the wafer processing method shown in Figure 2. [Figure 10] Figure 10 is a schematic cross-sectional view showing the state in which a release resin layer has been formed on the mask during the mask removal step of the wafer processing method shown in Figure 2. [Figure 11] Figure 11 is a schematic cross-sectional view showing the state in which peel tape is attached to the release resin layer formed on the mask during the mask removal step of the wafer processing method shown in Figure 2.

Mode for Carrying Out the Invention

[0014] The mode (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and substantially identical ones. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0015] 〔Embodiment 1〕 The wafer processing method and the protective film agent according to Embodiment 1 of the present invention will be described based on the drawings. FIG. 1 is a perspective view showing an example of a workpiece to be processed in the wafer processing method according to Embodiment 1. FIG. 2 is a flowchart showing the flow of the wafer processing method according to Embodiment 1.

[0016] (Wafer) The wafer processing method according to Embodiment 1 is the processing method of the wafer 1 shown in FIG. 1. In Embodiment 1, the wafer 1 is a wafer such as a semiconductor wafer having silicon or the like as a substrate 2 and a device layer 3 formed on the substrate 2. As shown in FIG. 1, devices 6 are formed in each region of the surface 4 of the wafer 1 partitioned in a lattice pattern by a plurality of division planned lines 5 intersecting each other.

[0017] The device 6 is, for example, an integrated circuit such as an IC (Integrated Circuit) or LSI (Large Scale Integration), or a memory (semiconductor memory device). The device layer 3 includes an inorganic film such as SiOF or BSG (SiOB), an organic film such as a polyimide film or a parylene film, or a low dielectric constant insulator film made of carbon-containing silicon oxide (SiOCH) (hereinafter referred to as a Low-k film), and a circuit layer including a conductive metal pattern and a metal film.

[0018] The low-k film is stacked with the circuit layer to form device 6. The circuit layer constitutes the circuit of device 6. For this reason, device 6 is composed of low-k films stacked on top of each other on the substrate 2, and circuit layers stacked between the low-k films. In the planned division line 5, the device layer 3 is composed of low-k films stacked on the substrate 2, except for the TEG (Test Elementary G group).

[0019] In this invention, the material of the substrate 2 of the wafer 1 and the type of device 6 are not limited to those described in Embodiment 1.

[0020] (Wafer processing method) The wafer processing method according to Embodiment 1 is a method of dividing a wafer 1 into individual chips 10 along a planned division line 5. The chip 10 includes a part of the substrate 2 and a device 6 on the substrate 2. The wafer processing method according to Embodiment 1 is also a method of dividing the wafer 1 into chips 10 by plasma etching, or so-called plasma dicing. As shown in Figure 2, the wafer processing method comprises a protective film formation step 1001, a mask formation step 1002, an etching step 1003, and a mask removal step 1004.

[0021] (Protective film formation step) Figure 3 is a schematic perspective view showing the protective film formation step of the wafer processing method shown in Figure 2, where tape is attached to the back surface of the wafer and a frame is attached to the outer edge of the tape. Figure 4 is a schematic side view showing a partial cross-section of the protective film agent being applied to the entire surface of the wafer in the protective film formation step of the wafer processing method shown in Figure 2. Figure 5 is a perspective view showing a wafer with a protective film formed on its surface in the protective film formation step of the wafer processing method shown in Figure 2. Note that the device layer 3 is omitted in Figures 3 and 4.

[0022] The protective film formation step 1001 is a step in which the entire surface 4 of the wafer 1 is covered with a non-polymerized resin, and a protective film 12 made of the non-polymerized resin is formed on the entire surface 4 of the wafer 1. In Embodiment 1, in the protective film formation step 1001, first, as shown in Figure 3, the central part of a disc-shaped tape 8 with a larger diameter than the wafer 1 is attached to the back surface 7 of the wafer 1, and an annular frame 9 with an inner diameter larger than the outer diameter of the wafer 1 is attached to the outer edge of the tape 8. In Embodiment 1, the tape 8 is an adhesive tape comprising a base material made of a resin having non-adhesive and flexible properties, and an adhesive layer laminated on the base material and made of a resin having adhesive and flexible properties, with the adhesive layer being attached to the wafer 1 and the frame 9, or a sheet consisting only of a base material made of a thermoplastic resin without an adhesive layer and which is heat-pressed to the wafer 1 and the frame 9.

[0023] In Embodiment 1, in the protective film formation step 1001, the protective film coating apparatus 60 shown in Figure 4 places the back surface 7 of the wafer 1 on the holding surface 62 of the spinner table 61 via tape 8, holds the back surface 7 of the wafer 1 on the holding surface 62 via tape 8, and clamps the frame 9 with clamp parts 63 provided around the spinner table 61. In Embodiment 1, in the protective film formation step 1001, as shown in Figure 4, the protective film coating apparatus 60 applies a liquid protective film agent 11 from an application nozzle 64 above the wafer 1 to the center of the surface 4 of the wafer 1 while rotating the spinner table 61 around its axis. The protective film agent 11 applied to the surface 4 of the wafer 1 is then spread to the outer edge of the wafer 1 by the centrifugal force generated by the rotation of the spinner table 61, covering the entire surface 4 of the wafer 1.

[0024] Thus, in Embodiment 1, in the protective film formation step 1001, the protective film agent 11 is supplied to and applied to the wafer 1 held on a spinner table 61 that rotates around its axis, in a so-called spin coating manner. In Embodiment 1, in the protective film formation step 1001, the protective film agent 11 is dried to form a protective film 12 that covers the entire surface 4 of the wafer 1, as shown in Figure 5.

[0025] In Embodiment 1, the protective film agent 11 includes a non-polymerized resin, a solvent for dissolving the non-polymerized resin, and a light-absorbing material that absorbs the wavelength of the laser beam 36 (shown in Figure 6) used in the mask formation step 1002. The non-polymerized resin is composed of, for example, a terpene resin or a rosin-based resin that is non-polymerized and resistant to the plasma-formed etching gas used in the etching step 1003. The solvent is used to adjust the viscosity of the protective film agent 11 and is added to form it to a viscosity that allows the protective film agent to be applied. The light-absorbing material is one that absorbs the laser beam 36 with a wavelength of, for example, 355 nm used in the mask formation step 1002, and for example, carbon black or phthalocyanine is used.

[0026] In Embodiment 1, the protective film agent 11 includes a terpene resin as a non-polymerized resin, propylene glycol monomethyl ether acetate (commonly known as PGMEA) as a solvent, and carbon black as a light absorber. Furthermore, the protective film 12 formed on the entire surface 4 of the wafer 1 after the protective film agent 11 dries contains the aforementioned resin, and is therefore composed of a material that is resistant to the plasma-formed etching gas used in the etching step 1003, and is formed to a uniform thickness that is resistant to the etching gas.

[0027] (Mask formation step) Figure 6 is a schematic side view showing a partial cross-section of the mask formation step of the wafer processing method shown in Figure 2. Figure 7 is a schematic cross-sectional view showing the wafer after the mask formation step of the wafer processing method shown in Figure 2. Note that the device layer 3 is omitted in Figures 6 and 7. The mask formation step 1002 is a step in which, after performing the protective film formation step 1001, a laser beam 36 (shown in Figure 6) is irradiated along the division line 5 to form an opening 131 (shown in Figure 7) in the protective film 12 along the division line 5, thereby forming a mask 13 (shown in Figure 7).

[0028] In Embodiment 1, during the mask formation step 1002, the laser processing apparatus 30 shown in Figure 6 holds the back surface 7 of the wafer 1 to the holding surface 32 of the chuck table 31 via tape 8, and clamps the frame 9 with clamps 37 provided around the chuck table 31. In Embodiment 1, during the mask formation step 1002, the laser processing apparatus 30 images the surface 4 of the wafer 1 with an imaging camera and performs alignment to align the wafer 1 with the focusing lens 34 of the laser beam irradiation unit 33.

[0029] In Embodiment 1, in the mask formation step 1002, the laser processing apparatus 30 moves the chuck table 31 and the laser beam irradiation unit 33 relative to each other along the division line 5, as shown in Figure 7, and irradiates the protective film 12 on each division line 5 with a laser beam 36 of a wavelength (for example, 355 nm) that is absorbed by the protective film 12 oscillated by the oscillator 35, thereby removing the protective film 12 on each division line 5. In Embodiment 1, in the mask formation step 1002, the laser processing apparatus 30 forms an opening 131 along the division line 5 over the entire length of each division line 5, and forms the protective film 12 on the mask 13 with the opening 131 formed as shown in Figure 7. The opening 131 exposes the division line 5 at the bottom.

[0030] (Etching equipment) Next, the etching apparatus 50 that performs the etching step 1003 will be described based on the drawings. Figure 8 is a schematic cross-sectional view showing an example of the configuration of an etching apparatus that performs the etching step of the wafer processing method shown in Figure 2. As shown in Figure 8, the etching apparatus 50 comprises a rectangular parallelepiped chamber 51, a holding unit 52, an upper electrode 53, and a control unit 55.

[0031] Chamber 51 has a processing space 511 formed inside where plasma etching is performed. Chamber 51 has an opening 513 for loading and unloading wafers 1 and an opening / closing door 514 on one side wall 512 that opens and closes the opening 513. The opening / closing door 514 opens and closes the opening 513 by moving up and down with an opening / closing mechanism 515 consisting of an air cylinder or the like.

[0032] Furthermore, the chamber 51 has an exhaust port 517 formed in its bottom wall 516, which connects the inside and outside of the chamber 51. An exhaust mechanism 510, such as a vacuum pump, is connected to the exhaust port 517.

[0033] The holding unit 52 and the upper electrode 53 are positioned facing each other in the processing space 511 of the chamber 51. The upper surface of the holding unit 52 is a holding surface 524 that holds the wafer 1 via the tape 8. The holding unit 52 is also made of a conductive material and functions as a lower electrode.

[0034] The holding unit 52 includes a disc-shaped holding portion 521 and a cylindrical support portion 520 that protrudes downward from the center of the lower surface of the holding portion 521. The support portion 520 is inserted into an opening 522 formed in the bottom wall 516 of the chamber 51. Within the opening 522, an annular insulating member 523 is placed between the bottom wall 516 and the support portion 520, electrically insulating the chamber 51 and the holding unit 52. The holding unit 52 is also connected to a high-frequency power supply 56 outside the chamber 51.

[0035] The holding portion 521 of the holding unit 52 is provided with an electrode 526 connected to a high-frequency power supply (not shown). When power is applied to the electrode 526 from the high-frequency power supply, the holding unit 52 generates a dielectric polarization phenomenon between the holding surface 524 and the wafer 1, and the wafer 1 is held and attracted onto the holding surface 524 by the electrostatic attraction force due to the polarization of the charge.

[0036] Furthermore, cooling channels 527 are formed inside the holding portion 521 and the support portion 520 of the holding unit 52, through which a cooling fluid flows to cool the holding unit 52. Both ends of the cooling channels 527 are connected to a refrigerant circulation mechanism 528. When the refrigerant circulation mechanism 528 is activated, a cooling fluid such as water circulates through the cooling channels 527, cooling the holding unit 52.

[0037] The upper electrode 53 is made of a conductive material and includes a disc-shaped gas ejection portion 531 and a cylindrical support portion 530 that protrudes upward from the center of the upper surface of the gas ejection portion 531. The support portion 530 is inserted into an opening 532 formed in the upper wall 518 of the chamber 51. Within the opening 532, an annular insulating member 533 is placed between the upper wall 518 and the support portion 530, thereby electrically insulating the chamber 51 from the upper electrode 53.

[0038] The upper electrode 53 is connected to the high-frequency power supply 57 outside the chamber 51. A support arm for the lifting mechanism 534 is attached to the upper end of the support portion 530. The upper electrode 53 moves up and down by the lifting mechanism 534.

[0039] Multiple nozzles 535 are provided on the lower side of the gas ejection section 531. The nozzles 535 are connected to a first etching gas supply source 58 and a second etching gas supply source 59 via a flow path 536 formed in the gas ejection section 531 and the support section 530. The first etching gas supply source 58 supplies a first etching gas into the chamber 51 from the nozzles 535 through the flow path 536. In Embodiment 1, when the substrate 2 of the wafer 1 is made of silicon, the first etching gas supply source 58 supplies a fluorine-based gas into the chamber 51 as the first etching gas. The second etching gas supply source 59 supplies a second etching gas into the chamber 51 from the nozzles 535 through the flow path 536. In Embodiment 1, the second etching gas supply source 59 supplies an oxygen-based gas into the chamber 51 as the second etching gas.

[0040] The control unit 55 controls each component of the etching apparatus 50 to cause the etching apparatus 50 to perform plasma etching on the wafer 1. The control unit 55 is a computer having an arithmetic processing unit with a microprocessor such as a CPU (central processing unit), a storage device with memory such as ROM (read-only memory) or RAM (random access memory), and an input / output interface device. The arithmetic processing unit of the control unit 55 performs calculations according to the computer program stored in the storage device and outputs control signals for controlling the etching apparatus 50 to each component of the etching apparatus 50 via the input / output interface device.

[0041] Furthermore, the control unit 55 is connected to a display unit, which consists of a liquid crystal display device that displays various information and images, and an input unit used by the operator to register processing content information. The input unit consists of at least one of the following: a touch panel provided on the display unit and an external input device such as a keyboard.

[0042] (Etching step) Figure 9 is a schematic cross-sectional view showing the wafer after the etching step of the wafer processing method shown in Figure 2. Note that the device layer 3 is omitted in Figure 9. The etching step 1003 is a step in which the wafer 1 is etched through the mask 13 after the mask formation step 1002 has been performed.

[0043] In Embodiment 1, during the etching step 1003, the etching apparatus 50 raises the upper electrode 53 by the lifting mechanism 534, raises the frame clamping plate 542 by the lifting mechanism, and then lowers the opening / closing door 514 by the opening / closing mechanism 515 to open the opening 513.

[0044] In etching step 1003, the etching apparatus 50 receives the wafer 1, on which the mask 13 has been formed over the entire back surface 7 in mask formation step 1002, into the processing space 511 via a transport unit (not shown), and places the wafer 1 on the holding surface 524 of the holding unit 52 via tape 8. In etching step 1003, the etching apparatus 50 applies power from a high-frequency power supply to the electrode 526 to adsorb and hold the surface 4 of the wafer 1 on the holding surface 524 via tape 8.

[0045] In etching step 1003, the etching apparatus 50 raises the opening / closing door 514 using the opening / closing mechanism 515 to close the opening 513, activates the exhaust mechanism 510 to reduce the pressure inside the chamber 51, creating a vacuum (low pressure) state in the processing space 511, and activates the refrigerant circulation mechanism 528 to circulate a cooling fluid such as water in the cooling channel 527 to suppress abnormal temperature rise of the holding unit 52. In etching step 1003, the etching apparatus 50 lowers the upper electrode 53 using the lifting mechanism 534, positioning the distance between the lower surface of the upper electrode 53 and the wafer 1 held by the holding unit 52 that constitutes the lower electrode to a predetermined electrode distance suitable for plasma etching.

[0046] In etching step 1003, the etching apparatus 50 supplies a first etching gas from a first etching gas supply source 58 at a predetermined flow rate and ejects it from multiple nozzles 535 of the gas ejection section 531 toward the wafer 1 held on the holding unit 52. In etching step 1003, while supplying the first etching gas from the first etching gas supply source 58, the etching apparatus 50 applies high-frequency power from a high-frequency power supply 57 to the upper electrode 53 to create and maintain plasma, and applies high-frequency power from a high-frequency power supply 56 to the lower electrode, the holding unit 52, to draw in ions.

[0047] In etching step 1003, the etching apparatus 50 plasmaizes the first etching gas in the space between the holding unit 52 and the upper electrode 53. This plasmaized first etching gas is drawn towards the wafer 1 and etches (so-called plasma etching) the surface 4 of the division line 5 exposed through the opening 131 of the mask 13 of the wafer 1, forming an etching groove 14 (shown in Figure 9) on the surface 4 of the division line 5, and the etching groove 14 advances toward the back surface 7 of the wafer 1. Thus, in Embodiment 1, plasma etching is performed on the wafer 1 via the mask 13 in etching step 1003.

[0048] In Embodiment 1, when the substrate 2 is made of silicon, a fluorine-based gas such as SF6, C4F8, or CF4 is used as the first etching gas, but the first etching gas is not limited to these. Also, in Embodiment 1, in etching step 1003, the etching apparatus 50 plasma etches the wafer 1 by the Bosch method, which alternately repeats plasma etching by supplying SF6 and protective film deposition on the inner surface of the etching groove 14 by supplying C4F8, but in the present invention, plasma etching may be performed by supplying a single etching gas.

[0049] In etching step 1003, the etching apparatus 50 has a predetermined time set for plasma etching the substrate 2 of the wafer 1 according to the thickness of the substrate 2 of the wafer 1. In etching step 1003, the etching apparatus 50 applies high-frequency power to the holding unit 52 and the upper electrode 53 while supplying the first etching gas for a predetermined time, completely removing the division lines 5 exposed from the opening 131 of the mask 13, as shown in Figure 9, and dividing the wafer 1 along the opening 131 into individual chips 10. That is, in etching step 1003, etching grooves 14 are made to penetrate the wafer 1 along the entire length of each division line 5.

[0050] (Mask removal step) Figure 10 is a schematic cross-sectional view showing the state in which a release resin layer has been formed on the mask during the mask removal step of the wafer processing method shown in Figure 2. Figure 11 is a schematic cross-sectional view showing the state in which peel tape has been attached to the release resin layer formed on the mask during the mask removal step of the wafer processing method shown in Figure 2. Note that the same reference numerals are used for the same parts as in Embodiment 1 in Figures 10 and 11, and their descriptions are omitted.

[0051] The mask removal step 1004 is a step in which, after performing the etching step 1003, the mask 13 of the wafer 1 is covered with a non-polymerized resin to form a release resin layer 16 on the mask 13, and then the mask 13 is removed from the wafer 1 together with the release resin layer 16.

[0052] In Embodiment 1, in the mask removal step 1004, after performing the etching step 1003, the entire mask 13 on the surface 4 of the wafer 1 is covered with the protective film agent 11, as shown in Figure 10. In Embodiment 1, when covering the entire mask 13 with the protective film agent 11 in the mask removal step 1004, the procedure is carried out in the same manner as in the protective film formation step 1001.

[0053] In Embodiment 1, in the mask removal step 1004, the protective film agent 11 on the mask 13 is dried to form a release resin layer 16 (shown in Figure 10) on the mask 13. Next, in Embodiment 1, in the mask removal step 1004, one end of a strip-shaped peel tape 17 is attached to one end of the release resin layer 16. In Embodiment 1, the peel tape 17 is an adhesive tape comprising a base material made of a resin having non-adhesive and flexible properties, and an adhesive layer laminated on the base material and made of a resin having adhesive and flexible properties, with the adhesive layer being attached to the release resin layer 16. Furthermore, the adhesive force of the adhesive layer of the peel tape 17 to the release resin layer 16 and the adhesive force of the release resin layer 16 to the mask 13 are stronger than the adhesive force of the mask 13 to the surface 4 of the wafer 1.

[0054] In Embodiment 1, in the mask removal step 1004, as shown in Figure 11, the other end of the peel tape 17 is moved along the surface 4 of the wafer 1 so that it passes through the center of the wafer 1 and then toward the other end of the release resin layer 16. As a result, the mask 13 peels off from the surface 4 of the wafer 1 together with the peel tape 17 and the release resin layer 16, and the mask 13 is removed from the wafer 1 together with the release resin layer 16. The thus separated chip 10 is picked up from the tape 8.

[0055] The wafer processing method and protective film agent 11 according to Embodiment 1 described above form a protective film 12 with a non-polymerized resin. In the wafer processing method and protective film agent 11 according to Embodiment 1, the resin constituting the protective film 12 consists of only a single compound and is not in a polymerized state. Therefore, in the mask formation step 1002, when the laser beam 36 is irradiated, the entire protective film 12 does not attempt to peel off, but rather the area irradiated by the laser beam 36 peels off locally from the surface 4 of the wafer 1. As a result, in the mask formation step 1002, in which an opening 131 is formed in the protective film 12 and the protective film 12 is formed into a mask, the mask 13 is less likely to peel off from the surface 4 of the wafer 1, and peeling when forming the mask 13 can be suppressed more effectively than when the protective film is formed with a polymerized resin.

[0056] Next, the inventors of the present invention confirmed the effects of the present invention. For this confirmation, they examined the peeling condition from the surface 4 of the wafer 1 after irradiating the protective film 12 of the present invention and the comparative example with a laser beam 36 to form an aperture 131. The results are shown in Table 1 below.

[0057] [Table 1]

[0058] In the present invention, an aperture 131 was formed by irradiating a protective film 12 made of a non-polymerized resin formed on the surface 4 of the wafer 1 with a laser beam 36. In Comparative Example 1, an ultraviolet-curable resin consisting of acrylate, a photopolymerizing agent, and a solvent was coated on the surface 4 of the wafer 1, and an aperture 131 was formed by irradiating the protective film, which was cured (polymerized) by ultraviolet light, with a laser beam 36. In Comparative Example 2, a water-soluble liquid resin made of polyvinyl alcohol (PVA), which is polymerized on the surface 4 of the wafer 1, was coated by spin coating, and an aperture 131 was formed by irradiating the protective film, which was dried and cured, with a laser beam 36.

[0059] According to Table 1, in Comparative Examples 1 and 2, the edges of the opening 131 peeled off from the surface 4 of the wafer 1, whereas in the present invention, the edges of the opening 131 did not peel off from the surface 4 of the wafer 1. Therefore, according to Table 1, it is clear that by forming the protective film 12 with a non-polymerized resin, peeling during the formation of the mask 13 can be suppressed more effectively than when the protective film is formed with a polymerized resin.

[0060] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the present invention. [Explanation of symbols]

[0061] 1 wafer 4 surface Planned division lines (5 divisions) 6 devices 7 Back side 11 Protective film agent 12 Protective film 13 masks 16. Release resin layer 36 laser beams 131 Aperture 1001 Protective film formation step 1002 Mask Forming Step 1003 Etching Step 1004 Mask removal step

Claims

1. A wafer processing method in which devices are formed in each region of the surface partitioned by multiple intersecting division lines, A protective film forming step involves coating the surface of the wafer with a protective film agent containing a nonpolymerized resin and a solvent that dissolves the resin, and drying the protective film agent to form a protective film made of the nonpolymerized resin. After performing the protective film formation step, a mask formation step is performed in which a laser beam is irradiated to form an opening in the protective film that exposes the planned division line, thereby forming a mask. A wafer processing method comprising: performing the mask formation step, followed by an etching step of etching the wafer through the mask to etch the surface of the lines to be divided, thereby dividing the wafer into chips.

2. The wafer processing method according to claim 1, wherein the etching step involves performing plasma etching on the wafer through the mask.

3. A wafer processing method according to claim 1 or 2, further comprising a mask removal step of performing the etching step, covering the mask of the wafer with the resin to form a release resin layer on the mask, and then removing the release resin layer from the wafer to remove the mask together with the release resin layer.

4. A wafer processing method in which devices are formed in each region of a surface partitioned by a plurality of intersecting division lines, comprising: a protective film forming step of coating the surface of the wafer with a nonpolymerized resin to form a protective film made of the nonpolymerized resin; a mask forming step of irradiating the protective film with a laser beam after performing the protective film forming step to form an opening in the protective film to form a mask; and an etching step of etching the wafer through the mask after performing the mask forming step, the protective film agent used in the wafer processing method, Non-polymerized resins, A solvent for dissolving the resin, A protective film agent comprising a light-absorbing material that absorbs the wavelength of the laser beam.

5. The protective film agent according to claim 4, wherein the resin is a terpene resin.

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