Wafer processing method

Abstract

To provide a wafer processing method in which no processing debris remains in dividing grooves.SOLUTION: A wafer processing method includes: a half-cut groove forming step of forming half-cut grooves on the surface of a wafer 2 corresponding to chips to be formed; a protective member disposing step of disposing a protective member 34 on the surface of the wafer 2 on which the half-cut grooves have been formed; a dividing step of grinding a back surface 2b of the wafer 2 to expose the half-cut grooves on the back surface 2b of the wafer 2 to form dividing grooves to divide the wafer 2 into individual chips; and a washing step of washing the wafer 2 on which the dividing grooves have been formed. In the washing step, bubbles are generated in washing water and allowed to penetrate into the dividing grooves to remove processing debris from the dividing grooves.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] Wafers, on the surface of which multiple devices such as ICs and LSIs are formed along planned dividing lines, are divided into individual device chips using cutting equipment, plasma equipment, etc., and each of the divided device chips is used in electrical equipment such as mobile phones and personal computers.

[0003] The cutting device includes a holding means for holding a wafer, a cutting means having a rotatable cutting blade for cutting the wafer held by the holding means, a feeding means for feeding the holding means and the cutting means relatively for processing, and an alignment means for taking an image of the wafer held by the holding means and detecting the planned dividing lines along which the wafer should be cut, and can divide the wafer into individual device chips with high precision (see, for example, Patent Document 1).

[0004] The present applicant has also proposed a technology in which half-cut grooves are formed along the intended dividing lines using a cutting blade or a laser beam, and then the back surface of the wafer is ground to expose the half-cut grooves on the back surface of the wafer, thereby dividing the wafer into individual device chips (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-078942 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-226982 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the back surface of the wafer is ground to expose the half-cut grooves on the back surface and form the division grooves, processing debris generated when dividing the wafer into individual device chips may remain in the division grooves. In such cases, even if two-fluid cleaning is performed by spraying cleaning water with high-pressure air, it is difficult to sufficiently remove the processing debris remaining in the division grooves. Furthermore, if processing debris remains in the division grooves, a problem occurs in that the processing debris remaining in the division grooves falls off, degrading the quality of the electronic components, for example, when the device chips are picked up and bonded to a wiring substrate.

[0007] Furthermore, when the back surface of the wafer is ground and then polished to remove the grinding marks and increase the bending strength, processing debris generated by the polishing gets into the dividing grooves, making it even more difficult to remove the processing debris. This problem becomes particularly noticeable when forming half-cut grooves with narrow groove widths by plasma etching.

[0008] An object of the present invention is to provide a wafer processing method in which no processing debris remains in the division grooves. [Means for solving the problem]

[0009] According to the present invention, there is provided the following wafer processing method that solves the above-mentioned problems. "A wafer processing method for dividing a wafer into individual chips, a half-cut groove forming step of forming half-cut grooves on the surface of the wafer corresponding to the chips to be formed; a protective member providing step of providing a protective member on the surface of the wafer on which the half-cut groove is formed; a dividing step of grinding the back surface of the wafer to expose the half-cut grooves on the back surface of the wafer and form dividing grooves to divide the wafer into individual chips; a cleaning step of cleaning the wafer in which the division grooves are formed, In the cleaning step, bubbles are generated in the cleaning water and made to penetrate into the division grooves, thereby removing processing debris from the division grooves.

[0010] Preferably, in the dividing step, grinding the back surface of the wafer includes grinding the back surface of the wafer with a grinding wheel having a circular grinding stone, and then polishing the ground back surface of the wafer with a polishing pad to remove grinding marks.

[0011] The half-cut groove forming step preferably includes forming the half-cut groove using a cutting blade, forming the half-cut groove using a laser beam, or forming the half-cut groove by plasma etching.

[0012] The cleaning process can be performed by a cleaning device that includes a rotatable spinner table that holds a wafer and a cleaning water spraying means that sprays cleaning water onto the wafer held on the spinner table, and the cleaning water spraying means includes a bubble generating section that generates bubbles in the cleaning water, a pressurizing section that pressurizes the cleaning water in which bubbles have been generated, and a nozzle section that sprays the pressurized cleaning water onto the wafer.

[0013] The pressurizing unit can pressurize the cleaning water with air, and the diameter of the air bubbles is preferably 1 μm or less. [Effects of the Invention]

[0014] The wafer processing method of the present invention includes: A wafer processing method for dividing a wafer into individual chips, comprising: a half-cut groove forming step of forming half-cut grooves on the surface of the wafer corresponding to the chips to be formed; a protective member providing step of providing a protective member on the surface of the wafer on which the half-cut groove is formed; a dividing step of grinding the back surface of the wafer to expose the half-cut grooves on the back surface of the wafer and form dividing grooves to divide the wafer into individual chips; a cleaning step of cleaning the wafer in which the division grooves are formed, In the cleaning step, bubbles are generated in the cleaning water and made to penetrate into the dividing grooves to remove the processing debris from the dividing grooves, so that no processing debris remains in the dividing grooves. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. [Figure 2] FIG. 1A is a schematic diagram showing how a half-cut groove is formed using a cutting blade, and FIG. 1B is a partial cross-sectional view of a wafer on which a half-cut groove has been formed. [Figure 3] FIG. 1(a) is a schematic diagram showing how a half-cut groove is formed using a laser beam, and FIG. 1(b) is a partial cross-sectional view of a wafer on which a modified layer serving as a half-cut groove has been formed. [Figure 4] FIG. 10 is a schematic diagram showing a state in which a half-cut groove is formed by plasma etching. [Figure 5] Schematic diagram showing a protective member disposing step. [Figure 6] FIG. 10 is a schematic diagram showing a state in which the back surface of the wafer is being ground in the dividing step. [Figure 7] FIG. 10 is a schematic diagram showing a state in which the back surface of the wafer is being polished in the dividing step. [Figure 8] FIG. [Figure 9] FIG. 9 is a schematic diagram showing a state in which a cleaning process is performed using the cleaning device shown in FIG. 8. [Figure 10] FIG. 10 is a perspective view of a wafer that has been divided into individual chips and then transferred from the protective tape to a dicing tape. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, preferred embodiments of the wafer processing method according to the present invention will be described with reference to the drawings.

[0017] (Wafer 2) 1 shows a disk-shaped wafer 2 that can be processed by the method of the present invention. The wafer 2 can be made of an appropriate semiconductor material, such as silicon. The dimensions of the wafer 2 are, for example, a diameter of 300 mm and a thickness of approximately 400 μm. The surface 2a of the wafer 2 is partitioned into a plurality of rectangular regions by grid-like dividing lines 4. A device 6, such as an IC or LSI, is formed in each of the rectangular regions.

[0018] (Half-cut groove forming process) In this embodiment, first, a half-cut groove forming step is carried out in which half-cut grooves are formed on the front surface 2a of the wafer 2 in correspondence with the chips to be formed.

[0019] (Dicing equipment 8) The half-cut groove forming step can be performed using, for example, a dicing device 8 shown in Fig. 2(a). The dicing device 8 includes a chuck table 10 that holds the wafer 2 by suction, and cutting means 12 that cuts the wafer 2 held by suction on the chuck table 10.

[0020] The chuck table 10 is configured to suction-hold the wafer 2 on its upper surface. The chuck table 10 is configured to be rotatable about an axis extending in the vertical direction, and also to be movable in the X-axis direction indicated by the arrow X in FIG. 2(a).

[0021] The cutting means 12 includes a spindle 14 configured to be rotatable about an axis in the Y-axis direction (the direction indicated by the arrow Y in FIG. 2(a)) perpendicular to the X-axis direction, and an annular cutting blade 16 fixed to the tip of the spindle 14. The cutting edge of the cutting blade 16 is formed to a predetermined thickness (for example, about 5 to 10 μm) from abrasive grains such as diamond and a binder such as metal or resin. The XY plane defined by the X-axis direction and the Y-axis direction is substantially horizontal.

[0022] When performing the half-cut groove forming step using a dicing device 8, first, the wafer 2 is suction-held on the upper surface of the chuck table 10 with the front surface 2a of the wafer 2 facing upward. Next, an image of the wafer 2 is captured from above by an imaging means (not shown) of the dicing device 8, and the division lines 4 are aligned in the X-axis direction based on the image of the wafer 2 captured by the imaging means. Next, the cutting edge of a cutting blade 16 rotated at high speed in the direction indicated by arrow R1 in FIG. 2(a) is cut into the division lines 4 aligned in the X-axis direction from the front surface 2a to a predetermined depth (e.g., 100 μm), and the chuck table 10 is moved in the X-axis direction while supplying cutting water to the portion where the cutting edge of the cutting blade 16 will cut. This allows half-cut grooves 18 of a predetermined depth to be formed along the division lines 4 (see FIG. 2(b)).

[0023] Next, the cutting blade 16 is indexed in the Y-axis direction by an amount corresponding to the spacing in the Y-axis direction of the planned division lines 4. Then, by alternately repeating the formation of half-cut grooves 18 and indexing, half-cut grooves 18 are formed along all of the planned division lines 4 aligned in the X-axis direction.

[0024] Furthermore, the chuck table 10 is rotated 90 degrees, and the formation of half-cut grooves 18 and the indexing feed are alternately repeated. In this way, half-cut grooves 18 are formed along all of the dividing lines 4 that are perpendicular to the dividing lines 4 along which the half-cut grooves 18 were previously formed. In this way, half-cut grooves 18 are formed in a grid pattern on the front surface 2a of the wafer 2 along the grid-like dividing lines 4.

[0025] (Laser processing equipment 20) Also, the half-cut groove forming process can also be carried out using the laser processing apparatus 20 shown in Fig. 3(a). The laser processing apparatus 20 includes a chuck table 22 for sucking and holding the wafer 2, an oscillator (not shown) that oscillates a pulsed laser beam LB having a wavelength that is absorbable by the wafer 2, and a condenser 24 that condenses the pulsed laser beam LB oscillated by the oscillator and irradiates the wafer 2 sucked and held by the chuck table 22.

[0026] When carrying out the half-cut groove forming process using the laser processing apparatus 20, first, with the surface 2a of the wafer 2 facing upward, the wafer 2 is sucked and held on the upper surface of the chuck table 22. Next, the wafer 2 is imaged from above by the imaging means (not shown) of the laser processing apparatus 20, and based on the image of the wafer 2 imaged by the imaging means, the planned division line 4 is aligned in the X-axis direction. Also, while aligning the aiming of the laser beam LB with the planned division line 4 aligned in the X-axis direction, the condensing point of the laser beam LB is positioned on the surface 2a of the wafer 2. It is preferable to previously coat the surface 2a with a protective film such as a water-soluble resin so that debris does not adhere to the surface 2a of the wafer 2.

[0027] Then, while the chuck table 22 is being processed and fed in the X-axis direction, the laser beam LB having a wavelength that is absorbable by the wafer 2 is irradiated from the condenser 24 onto the wafer 2. As a result, ablation processing is performed on the surface 2a of the wafer 2, and a half-cut groove 18 having a predetermined depth can be formed along the planned division line 4. Also, similar to the case of forming the half-cut groove 18 using the dicing apparatus 8, the irradiation of the laser beam LB and the indexing feed are alternately repeated, and the half-cut grooves 18 are formed in a lattice pattern on the surface 2a of the wafer 2 along the lattice-shaped planned division line 4.

[0028] When forming half-cut grooves using a laser processing apparatus 20, a modified layer 26 may be formed on the front surface 2a of the wafer 2 as half-cut grooves 18, as shown in FIG. 3(b). Even when the modified layer 26 is formed, cracks can extend from the modified layer 26 to divide the wafer 2 into individual chips by performing the dividing step described below. In other words, the half-cut groove 18 in this specification may be any groove that can serve as a starting point for dividing the wafer 2 into individual chips by performing the dividing step. When forming the modified layer 26 as half-cut grooves 18, the focal point of a laser beam having a wavelength that is transparent to the wafer 2 is positioned inside the wafer 2, and the laser beam is irradiated onto the wafer 2.

[0029] (Plasma etching equipment) Furthermore, the half-cut groove forming step can also be performed using a plasma device 28 shown in Fig. 4. The plasma device 28 includes a chamber (not shown) that forms an enclosed space, an upper electrode and a lower electrode (neither of which are shown) that are arranged at a distance from each other in the vertical direction within the chamber, and a gas ejection means 30 that ejects an etching gas into the chamber.

[0030] When forming half-cut grooves 18 using the plasma device 28, first, a required mask is formed on the front surface 2a of the wafer 2 by photolithography. Next, the wafer 2 is set in the chamber with the front surface 2a on which the mask is formed facing upward. Then, an etching gas (e.g., a fluorine-based gas) is supplied into the chamber from the gas ejection means 30, and high-frequency power that generates plasma is applied to the upper electrode. This generates plasmatized etching gas 32 between the upper electrode and the lower electrode, and the plasmatized etching gas 32 is supplied to the front surface 2a of the wafer 2. As a result, half-cut grooves 18 can be formed in a grid pattern on the front surface 2a of the wafer 2 along the grid-like intended dividing lines 4.

[0031] Thus, the half-cut groove forming process can include (1) forming the half-cut groove 18 using a cutting blade 16, (2) forming the half-cut groove 18 using a laser beam LB, and (3) forming the half-cut groove 18 by plasma etching.

[0032] (Protective member installation process) After the half-cut groove forming step is performed, a protective member providing step is performed in which a protective member 34 is provided on the front surface 2a of the wafer 2 in which the half-cut grooves 18 are formed, as shown in Fig. 5. The protective member 34 may be a circular adhesive tape or a thermocompression sheet having approximately the same diameter as the diameter of the wafer 2. The thermocompression sheet is a sheet of thermoplastic synthetic resin (e.g., polyolefin resin) that softens or melts and exhibits adhesive strength when heated to a temperature near its melting point.

[0033] (splitting process) After the protective member placement process is performed, a dividing process is performed in which the back surface 2b of the wafer 2 is ground to expose the half-cut grooves 18 on the back surface 2b of the wafer 2, forming dividing grooves and dividing the wafer 2 into individual chips.

[0034] (Grinding equipment 36) The dividing step can be performed using, for example, a grinding device 36 shown in Fig. 6. The grinding device 36 includes a chuck table 38 that holds the wafer 2 by suction, and grinding means 40 that grinds the wafer 2 held by suction on the chuck table 38. The grinding means 40 includes a spindle 42 that extends in the vertical direction, and a disk-shaped wheel mount 44 fixed to the lower end of the spindle 42. An annular grinding wheel 48 is fastened to the lower surface of the wheel mount 44 by bolts 46. A plurality of grinding stones 50 are fixed to the outer periphery of the lower surface of the grinding wheel 48, and are arranged in an annular shape at intervals in the circumferential direction.

[0035] In the dividing process, first, the wafer 2 is suction-held on the upper surface of the chuck table 38 with the back surface 2b of the wafer 2 facing upward. Next, the chuck table 38 is rotated in the direction indicated by arrow R2 in FIG. 6 at a predetermined rotational speed (e.g., 300 rpm). The spindle 42 is also rotated in the direction indicated by arrow R3 at a predetermined rotational speed (e.g., 6000 rpm). Next, the spindle 42 is lowered to bring the grinding wheel 50 into contact with the back surface 2b of the wafer 2, and grinding water is supplied to the portion of the back surface 2b where the grinding wheel 50 is in contact. Thereafter, the spindle 42 is lowered at a predetermined grinding feed rate (e.g., 1.0 μm / s). This grinds the back surface 2b of the wafer 2, thinning the wafer 2 to a predetermined thickness.

[0036] In the dividing step, grinding may be performed with the grinding wheel 50 of the grinding device 36 until the half-cut grooves 18 are exposed on the back surface 2b of the wafer 2, but in this embodiment, grinding is performed with the grinding device 36 to the extent that the half-cut grooves 18 are not exposed on the back surface 2b of the wafer 2. Therefore, when grinding by the grinding device 36 is completed, the wafer 2 has not yet been divided into individual chips. Note that Fig. 6 shows a state in which a plurality of arc-shaped grinding marks 52 extending radially from the radial center of the wafer 2 have been generated on the back surface 2b of the wafer 2 by grinding using the grinding device 36.

[0037] In the dividing process of this embodiment, after grinding is performed by the grinding device 36, the back surface 2b of the wafer 2 is polished to expose the half-cut grooves 18 on the back surface 2b of the wafer 2, thereby forming dividing grooves and dividing the wafer 2 into individual chips.

[0038] (polishing device 54) The back surface 2b of the wafer 2 can be polished using, for example, a polishing apparatus 54 shown in FIG. 7. The polishing apparatus 54 includes a chuck table 56 that holds the wafer 2 by suction, and a polishing means 58 that polishes the wafer 2 held by suction on the chuck table 56. The polishing means 58 includes a spindle 60 that extends vertically, and a disk-shaped mount 62 fixed to the lower end of the spindle 60. A disk-shaped base 66 is fastened to the lower surface of the mount 62 by bolts 64. A disk-shaped polishing pad 68 is fixed to the lower surface of the base 66. The polishing pad 68 can be made of a synthetic resin such as polyurethane containing abrasive grains, or a nonwoven fabric such as felt containing abrasive grains.

[0039] When polishing the back surface 2b of the wafer 2 in the dividing step, first, the wafer 2 is suction-held on the upper surface of the chuck table 56 with the back surface 2b of the wafer 2 facing upward. Next, the chuck table 56 is rotated at a predetermined rotational speed (e.g., 500 rpm) in the direction indicated by arrow R4 in FIG. 7 . The spindle 60 is also rotated at a predetermined rotational speed (e.g., 500 rpm) in the direction indicated by arrow R5. Next, the spindle 60 is lowered, and the lower surface of the polishing pad 68 is pressed against the back surface 2b of the wafer 2 to polish the back surface 2b of the wafer 2. This exposes the half-cut grooves 18 on the back surface 2b of the wafer 2, forming dividing grooves 70 and dividing the wafer 2 into individual device chips 72. Furthermore, the grinding marks 52 are removed from the back surface 2b of the wafer 2.

[0040] In this embodiment, the wafer 2 is not divided into device chips 72 by grinding using the grinding device 36, but is divided into device chips 72 by polishing using the polishing device 54 after grinding using the grinding device 36. That is, in the "dividing step of grinding the back surface 2b of the wafer 2 to expose the half-cut grooves 18 on the back surface 2b of the wafer 2 and forming division grooves 70 to divide the wafer 2 into individual chips," "grinding the back surface 2b of the wafer 2" includes grinding the back surface 2b of the wafer 2 with a grinding wheel 48 having annular grinding stones 50, and then polishing the ground back surface 2b of the wafer 2 with a polishing pad 68 to remove grinding marks 52. However, in the dividing step, the wafer 2 may be divided into device chips 72 by grinding using the grinding device 36, and polishing using the polishing device 54 may be omitted, or the wafer 2 may be divided into device chips 72 by grinding using the grinding device 36, and then polished using the polishing device 54.

[0041] The polishing of the back surface 2b of the wafer 2 may be wet polishing in which polishing is performed while supplying a polishing liquid such as slurry or pure water between the back surface 2b of the wafer 2 and the polishing pad 68, or may be dry polishing in which polishing is performed without supplying a polishing liquid between the back surface 2b of the wafer 2 and the polishing pad 68. However, in dry polishing, processing debris tends to remain in the division grooves 70 more easily than in wet polishing.

[0042] Furthermore, when the modified layer 26 is formed as half-cut grooves 18, cracks extend from the modified layer 26 in the thickness direction of the wafer 2 due to the pressing force acting when the wafer 2 is ground or polished, forming dividing grooves 70. This causes the wafer 2 to be divided into individual device chips 72.

[0043] (Cleaning process) After the dividing step is performed, a cleaning step is performed to clean the wafer 2 in which the dividing grooves 70 are formed.

[0044] (Cleaning device 74) The cleaning step can be performed using, for example, a cleaning apparatus 74 shown in Figures 8 and 9. The cleaning apparatus 74 includes a spinner table 76 that can hold and rotate the wafer 2, and cleaning water spraying means 78 (see Figure 9) that sprays cleaning water onto the wafer 2 held on the spinner table 76.

[0045] (Spinner Table 76) A circular suction chuck 80 is disposed at the upper end portion of the spinner table 76. The suction chuck 80 is formed from a porous material such as porous ceramics. The suction chuck 80 is connected to a suction means (not shown). In the spinner table 76, the suction means generates a suction force on the upper surface of the suction chuck 80, thereby suction-holding the wafer 2 placed on the upper surface of the suction chuck 80.

[0046] A rotary shaft 82a of a motor 82 that rotates the spinner table 76 is connected to the center of the spinner table 76. The motor 82 rotates the spinner table 76 about an axis that is in the vertical direction. In addition, an elevating means 84 that can be composed of an actuator such as an air cylinder is attached to the outer circumferential surface of the motor 82. The elevating means 84 raises and lowers the spinner table 76 between an elevated position (position shown in FIG. 8) where the wafer 2 is loaded and unloaded, and a lowered position (position shown in FIG. 9) where the wafer 2 is cleaned.

[0047] (Cleaning water injection means 78) As shown in FIG. 9, the cleaning water spraying means 78 includes a bubble generating section 86 that generates bubbles in the cleaning water, a pressurizing section 88 that pressurizes the cleaning water in which bubbles have been generated, and a nozzle section 90 that sprays the pressurized cleaning water onto the wafer 2.

[0048] (Bubble generating unit 86) The bubble generating unit 86 generates fine bubbles in cleaning water (e.g., pure water) supplied at a predetermined pressure (e.g., 0.2 MPa) from the cleaning water supply source 92. The diameter of the bubbles generated in the cleaning water by the bubble generating unit 86 is preferably 1 μm or less, and more preferably 0.1 μm or less. Note that the bubble generating unit 86 may be any known bubble generating means, and therefore a description of its configuration will be omitted.

[0049] (Pressure unit 88) The pressurizing unit 88 pressurizes the cleaning water with bubbles generated with high-pressure air. The pressurizing unit 88 is provided downstream of the bubble generating unit 86, and is supplied with high-pressure air (for example, air of 0.4 MPa) from a high-pressure air source 94.

[0050] (Nozzle part 90) Cleaning water pressurized by the pressurizing unit 88 is sent to the nozzle unit 90, and the bubble-containing cleaning water and air (two fluids) are sprayed from the nozzle port 90a of the nozzle unit 90 toward the wafer 2 held on the spinner table 76. As shown in FIGS. 8 and 9, the nozzle port 90a of the nozzle unit 90 is disposed above the wafer 2 held on the spinner table 76. A rotation motor 96 (see FIG. 9) is also attached to the nozzle unit 90. The nozzle unit 90 is rotated by the rotation motor 96 to be positioned between a standby position (position shown in FIG. 8) where the nozzle port 90a is spaced from directly above the spinner table 76, and a spraying position (position shown in FIG. 9) where the nozzle port 90a is located above the center of the spinner table 76.

[0051] 8 and 9, the cleaning device 74 includes an air nozzle 98 that sprays dry air onto the wafer 2 held on the spinner table 76, a swing motor 100 (see FIG. 9) that rotates the air nozzle 98, a drain pan 102 that receives the cleaning water sprayed from the nozzle unit 90, and a drain hose 104 (see FIG. 8) that discharges the cleaning water received in the drain pan 102. The air nozzle 98 is rotated by the swing motor 100 to be positioned at a standby position (position shown in FIG. 8) where the nozzle 98a is spaced from directly above the spinner table 76, and at a spray position where the nozzle 98a is located above the center of the spinner table 76.

[0052] In the cleaning process, first, the back surface 2b of the wafer 2 is faced upward and the wafer 2 is held by suction on the spinner table 76. At this time, the spinner table 76 is positioned in the raised position shown in Fig. 8, and the nozzle unit 90 and the air nozzle 98 are positioned in the standby position shown in Fig. 8.

[0053] After the wafer 2 is held by suction on the spinner table 76, cleaning water is sprayed toward the wafer 2 to clean the wafer 2. To do this, first, the spinner table 76 is positioned in the lowered position. Next, the nozzle unit 90 is rotated to the spray position, and the spray port 90a is positioned above the center of the wafer 2, as shown in Figure 9. Then, while the spinner table 76 is rotated in the direction indicated by arrow R6 in Figure 9 at a predetermined rotational speed (e.g., 400 rpm), a predetermined amount of cleaning water (e.g., 0.2 L / min) is sprayed from the spray port 90a of the nozzle unit 90 to clean the wafer 2.

[0054] When cleaning the wafer 2, bubble-containing cleaning water and air (two fluids) are sprayed from the nozzle 90a of the nozzle unit 90 onto the wafer 2 held on the spinner table 76. That is, cleaning water is supplied from the cleaning water supply source 92 to the bubble generation unit 86, which generates bubbles in the cleaning water. The bubble-containing cleaning water is pressurized in the pressurizing unit 88 with high-pressure air supplied from the high-pressure air source 94, and the bubble-containing cleaning water and air are sprayed from the nozzle 90a of the nozzle unit 90.

[0055] As a result, air bubbles contained in the cleaning water are pushed into the dividing grooves 70 by the air. As a result, the air bubbles enter the dividing grooves 70 and capture the processing debris inside the dividing grooves 70. The processing debris captured by the air bubbles rises to the top of the dividing grooves 70 together with the air bubbles and is removed from the wafer 2 by the cleaning water and air sprayed from the nozzle portion 90. Therefore, according to this embodiment, processing debris does not remain in the dividing grooves 70, and this solves the problem of processing debris remaining in the dividing grooves 70 falling off and degrading the quality of electronic components when the device chips 72 are picked up and bonded to a wiring board.

[0056] After the wafer 2 has been cleaned, dry air is sprayed toward the wafer 2 to dry it. At this time, the nozzle unit 90 is rotated to the standby position. The air nozzle 98 is also rotated to the spraying position, and the spray port 98a is positioned above the center of the wafer 2. Then, while the spinner table 76 is rotated in the direction indicated by arrow R6 in FIG. 9 at a predetermined rotational speed (for example, 2000 rpm), dry air is sprayed from the spray port 98a of the air nozzle 98 to dry the wafer 2.

[0057] As shown in FIG. 10 , the cleaning process may be performed after transferring the wafer 2 with the division grooves 70 formed therein from the protective member 34 to a dicing tape 106. That is, the back surface 2b of the wafer 2 may be attached to a circular dicing tape 106 whose periphery is fixed to an annular frame 108, and then the protective member 34 may be peeled off from the front surface 2a of the wafer 2, followed by the cleaning process. Furthermore, after transferring the wafer 2 from the protective member 34 to the dicing tape 106, the spacing between the division grooves 70 may be widened by applying radial tension to the dicing tape 106 using a known expanding device (not shown), and then the cleaning process may be performed. This allows the interiors of the division grooves 70 to be cleaned more effectively. In particular, when the modified layer 26 is formed as the half-cut grooves 18 and the wafer 2 is divided into individual device chips 72, it is preferable to widen the spacing between the division grooves 70 before cleaning.

[0058] As described above, in the wafer processing method of this embodiment, bubble-containing cleaning water and air (two fluids) are sprayed toward the wafer 2 in the cleaning step, and the air pushes the air bubbles contained in the cleaning water into the division grooves 70. As a result, the air bubbles penetrate the division grooves 70 and capture the processing debris inside the division grooves 70, and the processing debris captured by the air rises to the top of the division grooves 70 together with the air bubbles and is removed from the wafer 2 by the cleaning water and air. Therefore, according to this embodiment, processing debris does not remain in the division grooves 70, and the problem of processing debris remaining in the division grooves 70 falling off and degrading the quality of electronic components when the device chips 72 are picked up and bonded to a wiring substrate is solved. [Explanation of symbols]

[0059] 2: Wafer 2a: Surface of wafer 2b: Backside of wafer 4: Planned division line 6: Device 16: Cutting blade 18: Half cut groove 34: Protective material 48: Grinding wheel 50: Grinding wheel 52: Grinding marks 68: Polishing pad 70: Dividing groove 72: Device chip 74: Cleaning equipment 76: Spinner table 78: Cleaning water injection means 86: Bubble generating section 88: Pressure section 90: Nozzle part 90a: nozzle outlet

Claims

1. A wafer processing method for dividing a wafer into individual chips, comprising: a half-cut groove forming step of forming half-cut grooves on the surface of the wafer corresponding to the chips to be formed; a protective member providing step of providing a protective member on the surface of the wafer on which the half-cut groove is formed; a dividing step of grinding the back surface of the wafer to expose the half-cut grooves on the back surface of the wafer and form dividing grooves to divide the wafer into individual chips; a cleaning step of cleaning the wafer in which the division grooves are formed, In the cleaning step, bubbles are generated in the cleaning water and made to penetrate into the division grooves, thereby removing processing debris from the division grooves.

2. In the dividing step, grinding the back surface of the wafer means 2. A wafer processing method according to claim 1, further comprising the step of grinding the back surface of the wafer with a grinding wheel having an annular grinding stone, and then polishing the ground back surface of the wafer with a polishing pad to remove grinding marks.

3. 2. The wafer processing method according to claim 1, wherein the half-cut groove forming step includes forming the half-cut groove using a cutting blade, forming the half-cut groove using a laser beam, and forming the half-cut groove by plasma etching.

4. The washing step comprises: a spinner table capable of holding and rotating a wafer; and cleaning water spraying means for spraying cleaning water onto the wafer held on the spinner table; 2. A wafer processing method as described in claim 1, wherein the cleaning water spraying means is performed by a cleaning device including a bubble generating unit that generates bubbles in the cleaning water, a pressurizing unit that pressurizes the cleaning water in which bubbles have been generated, and a nozzle unit that sprays the pressurized cleaning water onto the wafer.

5. 5. The wafer processing method according to claim 4, wherein the pressurizing unit pressurizes the cleaning water with air.

6. 2. The wafer processing method according to claim 1, wherein the bubbles have a diameter of 1 μm or less.

Images