Wafer processing method
The wafer processing method forms half-cut grooves, applies a protective member, and uses a cleaning device with oscillating nozzles to inject bubble-containing cleaning water, effectively removing debris and ensuring high-quality chip production.
Patent Information
- Application Number
- JP2024097233
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-06-17
- Publication Date
- 2026-01-05
AI Technical Summary
Processing debris generated during the division of wafers into individual device chips often remains in the division grooves, making it difficult to clean and can degrade the quality of electronic components when the chips are bonded to a wiring substrate.
A wafer processing method involving half-cut groove formation, protective member application, grinding and polishing, followed by a cleaning process using a cleaning device with a rotatable spinner table and a cleaning nozzle that oscillates in synchronization with the table's rotation to inject bubble-containing cleaning water into the division grooves.
Effectively removes processing debris from the division grooves, preventing it from falling off and degrading the quality of electronic components during chip bonding.
Smart Images
Figure 2026000095000001_ABST
Abstract
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 from 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 when, for example, the device chips are picked up and bonded to a wiring substrate, degrading the quality of the electronic components.
[0007] Furthermore, when the back surface of the wafer is polished (especially by dry polishing) to remove the grinding marks and increase the bending strength after grinding, there is a problem that 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 washing step, a preparation step of preparing a cleaning device including a rotatable spinner table and a cleaning nozzle that swings so that an ejection port for ejecting cleaning water passes through the center of rotation of the spinner table; a placing step of placing the protection member side on the spinner table; a cleaning step of positioning the injection port of the cleaning nozzle at the start point of the division groove, oscillating the cleaning nozzle in synchronization with the rotation of the spinner table, moving the injection port along the division groove so that the injection port reaches the end point of the division groove, and injecting cleaning water in which bubbles have been generated from the injection port to cause the water to penetrate into the division groove and remove processing debris from the division groove.
[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 device preferably includes a bubble generating section that generates bubbles in the cleaning water and a pressurizing section that pressurizes the cleaning water in which bubbles have been generated, and sprays the pressurized cleaning water onto the wafer from the spray nozzle.
[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 washing step, a preparation step of preparing a cleaning device including a rotatable spinner table and a cleaning nozzle that swings so that an ejection port for ejecting cleaning water passes through the center of rotation of the spinner table; a placing step of placing the protection member side on the spinner table; and a cleaning step in which the nozzle of the cleaning nozzle is positioned at the start point of the dividing groove, the cleaning nozzle is oscillated in synchronization with the rotation of the spinner table, the nozzle is moved along the dividing groove so that the nozzle reaches the end point of the dividing groove, and cleaning water in which bubbles are generated is sprayed from the nozzle to penetrate into the dividing groove and remove machining debris from the dividing groove, so that no machining debris remains in the dividing groove. [Brief explanation of the drawings]
[0015] [Figure 1] FIG. [Figure 2] FIG. 2(a) is a schematic diagram showing how half-cut grooves are formed using a cutting blade, and FIG. 2(b) is a partial cross-sectional view of a wafer on which half-cut grooves have 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 carried out using the cleaning device shown in FIG. 8. [Figure 10] 9 is a schematic diagram (t0 to t3) showing a state in which a cleaning step is performed using the cleaning device shown in FIG. 8. FIG. [Figure 11] 9 is a schematic diagram (t4 to t7) showing a state in which a cleaning step is performed using the cleaning device shown in FIG. 8. FIG. [Figure 12] 9 is a schematic diagram (t8 to t10) showing a state in which a cleaning step is performed using the cleaning device shown in FIG. 8. FIG. [Figure 13] FIG. 10 is a perspective view of a wafer that has been divided into individual chips and then transferred from the protective member 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) FIG. 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 wafer 2 has dimensions of, 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. In addition, a notch 7 indicating the crystal orientation is formed on the outer periphery of the wafer 2.
[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] (Half-cut groove forming process using a cutting device) The half-cut groove forming process can be performed using, for example, a cutting device 8 shown in FIG. 2(a). The cutting device 8 includes a chuck table 10 that suction-holds the wafer 2 and a cutting means 12 that cuts the wafer 2 held by suction on the chuck table 10. The chuck table 10 suction-holds the wafer 2 on its upper surface. The chuck table 10 is configured to be rotatable about its axis in the vertical direction and to be movable in the X-axis direction indicated by the arrow X in FIG. 2(a). The cutting means 12 includes a spindle 14 that is rotatable about its axis in the Y-axis direction (the direction indicated by the arrow Y in FIG. 2(a)) that is 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 (e.g., approximately 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 and Y-axis directions is substantially horizontal.
[0020] When performing the half-cut groove forming step using the cutting 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 imaging means (not shown) of the cutting device 8 images the wafer 2 from above, 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 is to be cut. This allows half-cut grooves 18 of a predetermined depth to be formed along the division lines 4 (see FIG. 2(b)).
[0021] Next, the cutting blade 16 is fed in the Y-axis direction by the interval in the Y-axis direction of the planned division line 4. Then, by alternately repeating the formation of the half-cut groove 18 and the indexing feed, the half-cut groove 18 is formed along all of the planned division lines 4 aligned in the X-axis direction. Further, after rotating the chuck table 10 by 90 degrees, the formation of the half-cut groove 18 and the indexing feed are alternately repeated. As a result, the half-cut groove 18 is formed along all of the planned division lines 4 orthogonal to the planned division lines 4 where the half-cut groove 18 was previously formed. In this way, the half-cut groove 18 is formed in a lattice pattern on the surface 2a of the wafer 2 along the lattice-shaped planned division lines 4.
[0022] (Half-Cut Groove Forming Step Using a Laser Processing Apparatus) Also, the half-cut groove forming step can be carried out using the laser processing apparatus 20 shown in Fig. 3(a). The laser processing apparatus 20 includes a chuck table 22 that sucks and holds 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.
[0023] When carrying out the half-cut groove forming step 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 an imaging means (not shown) of the laser processing apparatus 20, and the planned division line 4 is aligned in the X-axis direction based on the image of the wafer 2 imaged by the imaging means. Next, the aiming of the laser beam LB is aligned with the planned division line 4 aligned in the X-axis direction, and 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.
[0024] Then, while the chuck table 22 is being processed and fed in the X-axis direction, the wafer 2 is irradiated from the condenser 24 with a laser beam LB having a wavelength that is absorbable by the wafer 2. This performs ablation processing on the front surface 2a of the wafer 2, and half-cut grooves 18 of a predetermined depth can be formed along the intended dividing lines 4. Furthermore, similar to the case of forming the half-cut grooves 18 using the cutting device 8, irradiation of the laser beam LB and indexing feed are alternately repeated, and the half-cut grooves 18 are formed in a grid pattern on the front surface 2a of the wafer 2 along the grid-like intended dividing lines 4.
[0025] When forming half-cut grooves using a laser processing apparatus 20, a modified layer 26 may be formed on the front surface 2a side 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. That is, 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 when the dividing step is performed. Note that 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.
[0026] (Half-cut groove formation process using a plasma etching device) Furthermore, the half-cut groove forming step may 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 is 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.
[0027] When forming half-cut grooves 18 using a 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-shaped intended dividing lines 4.
[0028] Thus, the half-cut groove forming process includes (1) forming the half-cut groove 18 using a cutting blade 16, (2) forming the half-cut groove 18 (including the modified layer 26) using a laser beam LB, and (3) forming the half-cut groove 18 by plasma etching.
[0029] (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 (for example, polyolefin resin), which softens or melts and exhibits adhesive strength when heated to a temperature near its melting point.
[0030] (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.
[0031] (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.
[0032] In the dividing process, first, the back surface 2b of the wafer 2 is placed facing upward and suction-held on the upper surface of the chuck table 38. 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.
[0033] 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 center of the wafer 2 have been generated on the back surface 2b of the wafer 2 by grinding using the grinding device 36.
[0034] 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.
[0035] (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.
[0036] 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.
[0037] In this embodiment, the wafer 2 is not divided into device chips 72 by grinding using the grinding apparatus 36, but is divided into device chips 72 by polishing using the polishing apparatus 54 after grinding using the grinding apparatus 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 form dividing 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 apparatus 36, and polishing using the polishing apparatus 54 may be omitted. Alternatively, 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.
[0038] 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.
[0039] 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.
[0040] (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.
[0041] (Preparation step for cleaning process) In the cleaning process, first, a preparation step is carried out to prepare a cleaning device including a rotatable spinner table and a cleaning nozzle that swings so that an ejection port for ejecting cleaning water passes through the center of rotation of the spinner table.
[0042] (Cleaning device 74) In the preparation step for the cleaning process, for example, cleaning device 74 shown in Figures 8 and 9 can be prepared. Cleaning device 74 includes a rotatable spinner table 76 and cleaning nozzle 78 that swings so that injection port 78a, which injects cleaning water, passes through center of rotation C of spinner table 76.
[0043] (Spinner table 76 of cleaning device 74) As shown in Fig. 8, a circular suction chuck 80 is disposed on 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.
[0044] A rotation shaft 82a of a motor 82 (e.g., a pulse motor) that rotates the spinner table 76 is connected to the center of the spinner table 76. The motor 82 rotates the spinner table 76 with an axis (rotation center C) that is in the vertical direction. The motor 82 is provided with a rotary encoder (not shown) that detects the rotation angle and rotation speed of the motor 82. 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.
[0045] (Cleaning nozzle 78 of cleaning device 74) A swing motor 86 (see FIG. 9) that swings the cleaning nozzle 78 is attached to the cleaning nozzle 78. The swing motor 86 swings the cleaning nozzle 78, so that the jet nozzle 78a of the cleaning nozzle 78 is positioned at a standby position (position shown in FIG. 8) spaced apart from directly above the spinner table 76, or at the rotation center C of the spinner table 76 (position shown in FIG. 9). In other words, the swing motor 86 swings the cleaning nozzle 78 so that the jet nozzle 78a passes through the rotation center C of the spinner table 76. The swing motor 86 is provided with a rotary encoder (not shown) that detects the rotation angle and rotation speed of the swing motor 86.
[0046] As shown in FIG. 9, the cleaning device 74 includes a bubble generating unit 88 that generates bubbles in the cleaning water, and a pressurizing unit 90 that pressurizes the cleaning water in which bubbles have been generated. The bubble generating unit 88 generates fine bubbles in cleaning water (e.g., pure water) supplied from a cleaning water supply source 92 at a predetermined pressure (e.g., 0.2 MPa). The diameter of the bubbles generated in the cleaning water by the bubble generating unit 88 is preferably 1 μm or less, and more preferably 0.1 μm or less. Note that the bubble generating unit 88 may be a known bubble generating means, and therefore a description of its configuration will be omitted. The pressurizing unit 90 pressurizes the cleaning water in which bubbles have been generated with high-pressure air. The pressurizing unit 90 is provided downstream of the bubble generating unit 88, and high-pressure air (e.g., air at 0.4 MPa) is supplied to the pressurizing unit 90 from a high-pressure air source 94. Then, cleaning water pressurized by the pressurizing section 90 is sent to the cleaning nozzle 78, and bubble-containing cleaning water and air (two fluids) are sprayed from the nozzle 78a of the cleaning nozzle 78 toward the wafer 2 held on the spinner table 76.
[0047] 8 and 9, the cleaning device 74 further includes an air nozzle 96 that sprays dry air onto the wafers 2 held on the spinner table 76, a swing motor 98 (see FIG. 9) that swings the air nozzle 96, a drain pan 100 that receives the cleaning water sprayed from the cleaning nozzle 78, and a drain hose 102 (see FIG. 8) that discharges the cleaning water received in the drain pan 100. When the air nozzle 98 is swung by the swing motor 98, the nozzle 96a of the air nozzle 96 is positioned at a standby position (position shown in FIG. 8) spaced apart from directly above the spinner table 76, at the center of rotation C of the spinner table 76, or the like.
[0048] (Placement step of cleaning process) After the preparation step in the cleaning process, a placing step is performed in which the protective member 34 side is placed on the spinner table 76. In the placing step, the wafer 2 is placed on the upper surface of the spinner table 76 with the protective member 34 facing downward, with the rotation center C of the spinner table 76 and the center of the wafer 2 aligned. During the placing step, the spinner table 76 is positioned in the raised position shown in Fig. 8, and the cleaning nozzle 78 and the air nozzle 96 are positioned in the standby position shown in Fig. 8. After the wafer 2 is placed on the spinner table 76, a suction force is generated in the vacuum chuck 80 by the suction means, and the protective member 34 side is suction-held on the upper surface of the spinner table 76.
[0049] (Cleaning step of the cleaning process) After the placing step in the cleaning process, a cleaning step is performed in which the nozzle 78a of the cleaning nozzle 78 is positioned at the starting point of the dividing groove 70, the cleaning nozzle 78 is oscillated in synchronization with the rotation of the spinner table 76, and the nozzle 78a is moved along the dividing groove 70 so that it reaches the end point of the dividing groove 70, and cleaning water that has generated bubbles is sprayed from the nozzle 78a to penetrate into the dividing groove 70 and remove processing debris from the dividing groove 70.
[0050] In the cleaning step, first, the nozzle 78a of the cleaning nozzle 78 is positioned directly above the starting point of the division groove 70. At this time, the wafer 2 is imaged from above using an imaging means (not shown) of the cleaning device 74, and the position of the division groove 70 is detected from the image of the wafer 2 captured by the imaging means. Next, the spinner table 76 is positioned in a lowered position, and based on the detected position of the division groove 70, the nozzle 78a of the cleaning nozzle 78 is positioned directly above the starting point 70a (first end of the division groove 70) of the division groove 70 to be cleaned first, as shown at time t0 in FIG. 10 . The end point of the division groove 70 (second end of the division groove 70) is indicated by reference symbol 70b.
[0051] Once the nozzle 78a of the cleaning nozzle 78 is positioned directly above the starting point 70a of the dividing groove 70, cleaning water is sprayed from the nozzle 78a while the nozzle 78a is moved along the dividing groove 70 to clean the dividing groove 70. That is, while the spinner table 76 is rotated in a fixed direction, the cleaning nozzle 78 is oscillated back and forth once in synchronization with the rotation of the spinner table 76, so that the nozzle 78a is moved along the same dividing groove 70 from directly above the starting point 70a of the dividing groove 70 to directly above the end point 70b of the dividing groove 70, and cleaning water is sprayed from the nozzle 78a to clean the dividing groove 70.
[0052] 10 to 12, the movement of the jet nozzle 78a along the same dividing groove 70 will be described. In the cleaning step, the spinner table 76 is rotated in the direction indicated by arrow R6. Meanwhile, in the schematic diagrams shown in FIGS. 10 to 12, the cleaning nozzle 78 is oscillated in the direction indicated by arrow R7 from time t0 to time t5, and in the direction indicated by arrow R8 (the opposite direction to the direction indicated by arrow R7) from time t6 to time t10. By oscillating the cleaning nozzle 78 back and forth in this manner in synchronization with the rotation of the spinner table 76, the jet nozzle 78a moves along the dividing groove 70 from the starting point 70a to the ending point 70b of the same dividing groove 70. In FIGS. 10 to 12, the portion of the dividing groove 70 through which the jet nozzle 78a of the cleaning nozzle 78 passed (i.e., the portion of the dividing groove 70 through which cleaning water was sprayed) is indicated by a bold line. The center of oscillation of the cleaning nozzle 78 is indicated by symbol 78b.
[0053] Thus, in the cleaning step, cleaning water is sprayed from the nozzle 78a to clean the dividing groove 70 while the nozzle 78a is moved along the same dividing groove 70 from directly above the starting point 70a of the dividing groove 70 to directly above the ending point 70b of the dividing groove 70. In other words, cleaning water is sprayed from directly above the dividing groove 70 onto the entire area of the dividing groove 70, so the dividing groove 70 can be cleaned effectively.
[0054] In the cleaning step, a predetermined amount (for example, 0.2 L / min) of bubble-containing cleaning water and air (two fluids) is sprayed from the nozzle 78a of the cleaning nozzle 78. That is, cleaning water is supplied from the cleaning water supply source 92 to the bubble generation unit 88, which generates bubbles in the cleaning water, and the bubble-containing cleaning water is pressurized in the pressurizing unit 90 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 78a of the cleaning nozzle 78.
[0055] As a result, air bubbles contained in the cleaning water are pushed into the dividing groove 70 by the air. As a result, the air bubbles enter the dividing groove 70 and capture the machining debris inside the dividing groove 70. The machining debris captured by the air bubbles rises to the top of the dividing groove 70 together with the air bubbles and is removed from the dividing groove 70 by the cleaning water and air sprayed from the spray port 78a.
[0056] This cleaning step is performed on all of the dividing grooves 70. This makes it possible to remove processing debris from all of the dividing grooves 70. Therefore, according to this embodiment, processing debris does not remain in the dividing grooves 70, and the problem of processing debris remaining in the dividing grooves 70 falling off and degrading the quality of the electronic component when the device chips 72 are picked up and bonded to a wiring substrate is eliminated.
[0057] Regarding the cleaning step, in this embodiment, an example has been described in which the dividing grooves 70 are cleaned one by one, but when the spacing between the dividing grooves 70 is relatively narrow (for example, when the spacing between the dividing grooves 70 is about 1 mm), multiple dividing grooves 70 may be cleaned simultaneously.
[0058] Furthermore, in this embodiment, an example in which the cleaning step is performed after the placing step has been described. However, a spinner cleaning step may be performed after the placing step and before the cleaning step, in which cleaning water is sprayed from the nozzle 78a of the cleaning nozzle 78 to clean the wafer 2 while the spinner table 76 is rotating at high speed. In the spinner cleaning step, the spinner table 76 is positioned in a lowered position, and then the nozzle 78a of the cleaning nozzle 78 is positioned above the center of the wafer 2, as shown in FIG. 9 . Then, while the spinner table 76 is rotating at high speed (e.g., 400 rpm), bubble-containing cleaning water and air (two fluids) are sprayed from the nozzle 78a of the cleaning nozzle 78 to clean the wafer 2. The cleaning nozzle 78 may be swung as appropriate while the wafer 2 is being cleaned.
[0059] (Drying step in the cleaning process) After the cleaning step is performed in the cleaning process, a drying step is performed in which dry air is sprayed toward the wafer 2 to dry the wafer 2. In the drying step, first, the cleaning nozzle 78 is swung to the standby position. Next, the air nozzle 96 is swung to position the nozzle 96a of the air nozzle 96 above the center of the wafer 2. Then, while the spinner table 76 is rotating at a predetermined rotation speed (for example, 2000 rpm), dry air is sprayed from the nozzle 96a of the air nozzle 96 to dry the wafer 2. While the wafer 2 is drying, the air nozzle 96 may be swung as needed.
[0060] As shown in FIG. 12 , 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 104. That is, the back surface 2b of the wafer 2 may be attached to a circular dicing tape 104 whose periphery is fixed to an annular frame 106, 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 104, the spacing between the division grooves 70 may be widened by applying radial tension to the dicing tape 104 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.
[0061] As described above, in the wafer processing method of this embodiment, in the cleaning step, the nozzle 78a of the cleaning nozzle 78 is positioned at the starting point 70a of the division groove 70, and the cleaning nozzle 78 is oscillated in synchronization with the rotation of the spinner table 76, moving the nozzle 78a along the division groove 70 so that the nozzle 78a reaches the end point of the division groove 70. Cleaning water containing bubbles is sprayed from the nozzle 78a, which penetrates the division groove 70 and removes processing debris from the division groove 70. Therefore, according to this embodiment, cleaning water is sprayed from directly above the division groove 70 over the entire area of the division groove 70, so that the division groove 70 can be effectively cleaned. As a result, no processing debris remains in the division groove 70, and the problem of processing debris remaining in the division groove 70 falling off and degrading the quality of electronic components when the device chip 72 is picked up and bonded to a wiring substrate is solved. [Explanation of symbols]
[0062] 2: Wafer 2a: Surface of wafer 2b: Backside of wafer 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 70a: Starting point (first end) of dividing groove 70b: End point (second end) of dividing groove 72: Device chip 74: Cleaning equipment 76: Spinner table C: Rotation center of the spinner table 78: Cleaning nozzle 78a: Cleaning nozzle nozzle 88: Bubble generating section 90: Pressure section
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 washing step, a preparation step of preparing a cleaning device including a rotatable spinner table and a cleaning nozzle that swings so that an ejection port for ejecting cleaning water passes through the center of rotation of the spinner table; a placing step of placing the protection member side on the spinner table; a cleaning step of positioning the nozzle of the cleaning nozzle at the start point of the division groove, oscillating the cleaning nozzle in synchronization with the rotation of the spinner table, moving the nozzle along the division groove so that the nozzle reaches the end point of the division groove, and spraying cleaning water in which bubbles have been generated from the nozzle to cause the water to penetrate into the division groove and remove processing debris from the division groove.
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 wafer processing method according to claim 1, wherein the cleaning device comprises a bubble generating unit that generates bubbles in the cleaning water and a pressurizing unit that pressurizes the cleaning water in which bubbles have been generated, and the pressurized cleaning water is sprayed onto the wafer from the spray nozzle.
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.
Citation Information
Patent Citations
Manufacturing method of device
JP2008226982A
Processing method and dicing device
JP2023078942A
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