Wafer processing method and package device manufacturing method

Abstract

To improve adhesion between the surface of a wafer and a sealing resin.SOLUTION: A method for processing a wafer in which devices are formed in each of a plurality of regions partitioned by a plurality of division schedule lines includes: a protective film covering step of applying a protective film agent onto the surface of the wafer, then drying the protective film agent and forming a protective film, and covering the surface of the wafer with the protective film; a laser processing step of emitting a laser beam having a wavelength absorbed in the wafer along each division schedule line on the surface of the wafer, and forming a plurality of laser processing grooves; a protective film removal step of cleaning and removing the protective film; a residual organic matter removal step of irradiating the surface of the wafer with ultraviolet, and removing an organic matter which remains on the surface of the wafer and is derived from the protective film; and a covering step of a covering region which is positioned on the surface of the wafer and corresponds to each of the devices with a sealing resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for processing a wafer on which a plurality of devices are formed, and a method for manufacturing a packaged device, which manufactures a plurality of packaged devices from the wafer. [Background technology]

[0002] Device chips are mounted on electronic devices such as mobile phones, personal computers, etc. When manufacturing device chips, for example, first, a plurality of planned division lines are set in a grid pattern on the surface of a silicon wafer (hereinafter simply referred to as a wafer), and devices such as ICs (Integrated Circuits) are formed in each of the areas partitioned by the plurality of planned division lines.

[0003] Next, a laser beam irradiation device is used to irradiate the front side of the wafer with a pulsed laser beam having a wavelength that is absorbed by the wafer, forming grooves of a predetermined depth on the front side along each of the planned division lines, and then a cutting device is used to further cut each groove, dividing the wafer into each device chip.

[0004] However, when forming a groove on the front surface of a wafer using the above-mentioned laser beam, there is a problem that the melted material (i.e., debris) generated during the laser processing scatters and adheres to the surface of the wafer, thereby degrading the quality of the device chip. To address this problem, a technique is known in which the surface of the wafer is coated with a protective film containing a water-soluble resin before laser processing (see, for example, Patent Document 1).

[0005] If laser processing is performed on a wafer whose surface is covered with a protective film, debris will adhere to the protective film, so if the surface is washed with pure water after laser processing, the debris can be removed along with the protective film, thereby preventing debris from adhering to the wafer surface.

[0006] However, it has been found that when the front surface of the wafer is covered with a sealing resin after the protective film and debris have been removed by cleaning, the adhesion between the front surface of the wafer and the sealing resin may not be sufficient. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-140311 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in view of the above problems, and has as its object to improve the adhesion between the surface of the wafer and the sealing resin. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a method for processing a wafer having a surface on which a plurality of planned dividing lines are set so as to intersect, and having devices formed in each of a plurality of regions partitioned by the plurality of planned dividing lines, the method comprising: a protective film coating step of applying a protective film agent to the surface of the wafer, drying the protective film agent to form a protective film, and covering the surface with the protective film; a laser processing step of irradiating the surface of the wafer with a laser beam having a wavelength absorbed by the wafer along each of the planned dividing lines after the protective film coating step, to form a plurality of laser-processed grooves; a protective film removal step of cleaning and removing the protective film after the laser processing step; a residual organic matter removal step of irradiating the surface of the wafer with ultraviolet light after the protective film removal step, to remove organic matter derived from the protective film remaining on the surface of the wafer; and a sealing resin coating step of covering, with a sealing resin, the regions of the surface of the wafer corresponding to each device.

[0010] The organic matter remaining on the surface of the wafer after the protective film removal step and before the remaining organic matter removal step includes a compound containing a nitrogen atom. Each laser-processed groove formed in the laser processing step has a predetermined depth that does not reach the back surface of the wafer located opposite the front surface of the wafer, and the wafer processing method may further include a cutting step of cutting the wafer sealed with the sealing resin and the sealing resin along each planned division line to divide them into a plurality of device chips.

[0011] According to another aspect of the present invention, there is provided a method for manufacturing a package device, which manufactures a plurality of package devices from a wafer having a surface on which a plurality of planned dividing lines are set so as to intersect, and on which devices are formed in each of a plurality of regions partitioned by the plurality of planned dividing lines, the method comprising: a protective film coating step of applying a protective film agent to the surface of the wafer, drying the protective film agent to form a protective film, and covering the surface with the protective film; a laser processing step of irradiating the surface of the wafer with a laser beam having a wavelength absorbed by the wafer along each of the planned dividing lines, thereby forming a plurality of laser-processed grooves; a protective film removal step of cleaning and removing the protective film, after the laser processing step; a residual organic matter removal step of irradiating the surface of the wafer with ultraviolet light, after the protective film removal step, to remove organic matter remaining on the surface of the wafer and derived from the protective film; and a package device forming step of forming a plurality of package devices, each of which has a covering region located on the surface of the wafer and corresponding to each device, covered with a sealing resin, after the residual organic matter removal step. [Effects of the Invention]

[0012] A wafer processing method according to one aspect of the present invention includes a protective film removal step in which the protective film is cleaned and removed, followed by a residual organic matter removal step in which ultraviolet light is irradiated onto the surface of the wafer to remove organic matter originating from the protective film remaining on the surface of the wafer.

[0013] By removing organic matter derived from the protective film through the residual organic matter removal process, the amount of organic matter remaining on the surface of the wafer can be reduced to the same level as when the surface of the wafer is not covered with a protective film, thereby improving the adhesion between the surface of the wafer and the encapsulation resin compared to when the residual organic matter removal process is not performed. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a flow diagram of a method for manufacturing a packaged device. [Figure 2] FIG. 2 is a perspective view of the laser processing device. [Figure 3] FIG. 2 is a perspective view of a wafer unit. [Figure 4] FIG. 2 is a perspective view of the coating / cleaning unit. [Figure 5] FIG. [Figure 6] FIG. 1 is a cross-sectional view of a portion of a wafer coated with a protective film. [Figure 7] 1A to 1C are diagrams illustrating a laser processing step. [Figure 8] 10A to 10C are diagrams illustrating a protective film removal step. [Figure 9] FIG. 10 is a cross-sectional view of a portion of the wafer after a protective film removal step. [Figure 10] FIG. 10 is a diagram showing a remaining organic matter removal step. [Figure 11] FIG. 2 is a cross-sectional view of a portion of a wafer covered with a sealing resin. [Figure 12] FIG. [Figure 13] FIG. 10 is a flow diagram of a method for manufacturing a packaged device according to a second embodiment. [Figure 14] FIG. 14(A) is a partially cross-sectional side view showing a plurality of device chips, and FIG. 14(B) is a cross-sectional view of the packaged device. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a flow diagram of a method for manufacturing a packaged device 31 (see Fig. 12) according to a first embodiment. As shown in Fig. 1, the method for manufacturing the packaged device 31 includes a protective film coating step S10, a laser processing step S20, a protective film removing step S30, a remaining organic matter removing step S40, a sealing resin coating step S52, and a cutting step S54.

[0016] In this specification, some of the steps in the method for manufacturing the package device 31 may be referred to as a method for processing the wafer 11. In addition, in the first embodiment, the sealing resin coating step S52 and the cutting step S54 are collectively referred to as a package device formation step S50.

[0017] The packaged device 31 manufactured in the first embodiment is called a WL-CSP (Wafer Level Chip Size (Scale) Package). Each step will be described below according to the flow chart of FIG.

[0018] 2 is a perspective view of the laser processing device 2 used in each of the steps from the protective film coating step S10 to the remaining organic matter removal step S40. The X-axis, Y-axis, and Z-axis directions shown in Fig. 2 are perpendicular to one another. For example, the XY plane corresponds to the horizontal plane, and the Z-axis direction corresponds to the vertical direction.

[0019] The laser processing device 2 has a base 4 that supports or houses the components of the laser processing device 2. A rectangular plate-shaped cassette table 8 on which a cassette 6 is placed is provided at a corner on the front side (one side in the Y-axis direction) of the base 4.

[0020] An elevator (not shown) that raises and lowers the cassette table 8 along the Z-axis direction is provided below the cassette table 8. The cassette 6 contains a plurality of wafer units 21, each having a disk-shaped wafer 11 made of silicon or the like.

[0021] The configuration of the wafer unit 21 will now be described with reference to Fig. 3. Fig. 3 is a perspective view of the wafer unit 21. The wafer unit 21 has a disk-shaped wafer 11 made primarily of a semiconductor material such as silicon.

[0022] A circuit layer 11c including a low dielectric constant interlayer insulating film material (so-called low-k material) and a metallization layer is formed on the front surface 11a of the wafer 11. A plurality of linear dividing lines (streets) 13 are set in a lattice pattern (intersecting each other) on the front surface 11a of the wafer 11.

[0023] A device 15 such as an IC is formed in each of the rectangular areas partitioned by the plurality of planned division lines 13. As shown in Fig. 6, the rectangular areas in which the devices 15 are formed are slightly thicker than the areas in which the planned division lines 13 are set.

[0024] A central portion of a dicing tape 17 having a diameter larger than that of the wafer 11 is attached to the back surface 11b of the wafer 11. The dicing tape 17 has a laminated structure of, for example, a base layer and an adhesive layer (glue layer). In one example, the base layer is made of a resin such as polyolefin, and the adhesive layer is made of an adhesive resin such as an uncured ultraviolet-curable resin.

[0025] One surface of an annular frame 19 having an opening with a larger diameter than the wafer 11 is attached to the outer periphery of the dicing tape 17. In this manner, the wafer 11 is supported by the frame 19 via the dicing tape 17.

[0026] Returning to Figure 2, other components of the laser processing apparatus 2 will be described. A push-pull arm 10 is provided behind the cassette table 8 (on the other side in the Y-axis direction). The push-pull arm 10 carries the wafer unit 21 out of the cassette 6 onto a pair of guide rails 12 while holding a frame 19.

[0027] The pair of guide rails 12 are arranged on both sides of the movement path of the push-pull arm 10, and have the function of adjusting the position in the X-axis direction of the wafer unit 21. A first transport unit 14 is provided near the pair of guide rails 12 to transport the wafer unit 21 between the pair of guide rails 12.

[0028] The first transport unit 14 has an arm that is substantially L-shaped when viewed from above. A suction mechanism for suctioning the frame 19 is provided at the tip of the arm. A rotation mechanism including a motor (not shown) for rotating the arm around a predetermined rotation axis is provided at the base end of the arm.

[0029] A coating / cleaning unit 16 is provided near the first transfer unit 14, and the first transfer unit 14 transfers the wafer unit 21 to the coating / cleaning unit 16. The coating / cleaning unit 16 will now be described with reference to Figure 4 and other figures. Figure 4 is a perspective view of the coating / cleaning unit 16.

[0030] The coating / cleaning unit 16 forms a protective film 23a (see FIG. 6) on the surface 11a, and then cleans the wafer 11 that has been subjected to laser processing while the surface 11a is covered with the protective film 23a. The coating / cleaning unit 16 has a disk-shaped spinner table 18.

[0031] The spinner table 18 has a disk-shaped frame made of metal. A disk-shaped recess (not shown) is formed on the upper surface of the frame, and a disk-shaped porous plate is fixed in this recess. Negative pressure is transmitted to the porous plate from a suction source (not shown), such as an ejector, via a flow path (not shown) formed in the frame.

[0032] The upper surface of the frame and the upper surface of the porous plate are formed to be substantially flush with each other, forming a substantially flat holding surface 18a. A plurality of pendulum-type clamp units 18b are provided on the outer periphery of the spinner table 18.

[0033] A first drive source 20 such as a motor that rotates the spinner table 18 at high speed around a predetermined rotation axis along the Z-axis direction is provided below the spinner table 18. A plurality of air cylinders 22 that extend and retract along the Z-axis direction are provided on the side of the first drive source 20.

[0034] The spinner table 18 and the first drive source 20 move along the Z-axis direction by the operation of each air cylinder 22. Specifically, they move between a relatively high loading / unloading position (see FIG. 4) and a relatively low working position (see FIGS. 5, 8, and 10).

[0035] A cylindrical container 24 with a bottom and an inner diameter larger than the outer diameter of the spinner table 18 is provided on the side and bottom of the spinner table 18. The container 24 functions as a drainage receiver. The container 24 is supported by a plurality of legs 26.

[0036] A through opening for passing the output shaft of first drive source 20 is formed in the bottom wall of container 24, and a cylindrical cover is provided on the through opening (see FIG. 5). An application unit 30 for applying liquid protective film agent 23 (see FIG. 5) is provided in an annular gap 28 between container 24 and spinner table 18.

[0037] The coating unit 30 has a first nozzle 32 that supplies the protective film agent 23 to the front surface 11a of the wafer 11 held by suction on the holding surface 18a. The first nozzle 32 is fixed to the tip of a first arm 34. A protective film agent supply source (not shown) is connected to the first nozzle 32 via a predetermined flow path (not shown) provided in the first arm 34.

[0038] The protective film agent supply source includes a tank (not shown) that stores the protective film agent 23, and a pump (not shown) for supplying the protective film agent 23 from the tank to the first nozzle 32. The protective film agent 23 includes pure water used as a solvent, a water-soluble resin, a light absorbing agent, and an organic solvent.

[0039] An example of the water-soluble resin is polyvinylpyrrolidone. However, other water-soluble resins such as poly-N-vinylacetamide, polyoxazoline, and copolymers of polymer compounds (such as vinyl acetate-vinylpyrrolidone copolymers) may be used instead of polyvinylpyrrolidone, or multiple types of water-soluble resins may be used in combination.

[0040] Examples of light absorbers include cinnamic acid derivatives such as ferulic acid and caffeic acid, benzophenone derivatives such as polyhydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, flavones such as glycosyl rutin and glycosyl hesperidin, flavonoids, and flavonol derivatives.

[0041] Examples of the organic solvent include propylene glycol monomethyl ether (PGME), methanol, ethanol, isopropanol, acetone, and tetrahydrofuran.

[0042] A motor 36 (see FIG. 5) that can rotate forward and backward is provided at the base end of the first arm 34. The motor 36 moves the first arm 34 between a predetermined position (see FIG. 5) above the holding surface 18a where the first nozzle 32 applies the protective film agent 23, and a retracted position (see FIG. 4) where the first nozzle 32 is retracted from above the holding surface 18a.

[0043] A cleaning unit 38 is provided in the gap 28 on the opposite side of the coating unit 30 in the radial direction of the spinner table 18. The cleaning unit 38 has a second nozzle 40 that supplies cleaning water 25 (see FIG. 8), such as pure water, to the front surface 11a of the wafer 11 held by suction on the holding surface 18a.

[0044] The second nozzle 40 is fixed to the tip of the second arm 42. A cleaning water supply source (not shown) is connected to the second nozzle 40 via a predetermined flow path (not shown) provided in the second arm 42.

[0045] The cleaning water supply source includes a tank (not shown) in which cleaning water 25 is stored, and a pump (not shown) for supplying cleaning water 25 from the tank to the second nozzle 40. In addition, a motor 44 (see FIG. 5) that can rotate forward and backward is provided at the base end of the second arm 42.

[0046] The motor 44 moves the second arm 42 to a predetermined area above the holding surface 18a (see FIG. 8) and to a retracted position (see FIG. 4) where the second nozzle 40 is retracted from above the holding surface 18a. In the predetermined area above the holding surface 18a, the motor 44 swings the second arm 42 within a predetermined angle range, thereby swinging the second nozzle 40 that supplies cleaning water 25.

[0047] An air spray unit 46 is provided in the region of the gap 28 between the coating unit 30 and the cleaning unit 38. The air spray unit 46 has a third nozzle 48 that supplies air (not shown), such as dry air, to the front surface 11a of the wafer 11 held by suction on the holding surface 18a.

[0048] The third nozzle 48 is fixed to the tip of the third arm 50. An air supply source (not shown) is connected to the third nozzle 48 via a predetermined flow path (not shown) provided in the third arm 50.

[0049] The air supply source includes an air compressor (not shown) and a tank (not shown) that stores air. In addition, a motor (not shown) that can rotate forward and backward is provided at the base end of the third arm 50.

[0050] The motor moves the third arm 50 to a predetermined area (not shown) above the holding surface 18a and to a retracted position (see FIG. 4) where the third nozzle 48 is retracted from above the holding surface 18a. In the predetermined area above the holding surface 18a, the motor swings the third arm 50 within a predetermined angle range, thereby swinging the third nozzle 48 that supplies air.

[0051] 2, a rectangular opening 4a with its longitudinal side aligned along the X-axis direction is formed in front of the coating / cleaning unit 16. A disk-shaped chuck table 52 is provided in the opening 4a. The chuck table 52 has a disk-shaped frame made of metal.

[0052] A recess (not shown) is formed on the top surface of the frame, and a circular porous plate is fixed in this recess. Negative pressure is transmitted to the porous plate from a suction source (not shown), such as an ejector, via a flow path (not shown) formed in the frame.

[0053] The upper surface of the frame and the upper surface of the porous plate are formed to be substantially flush with each other, forming a substantially flat holding surface 52a. A plurality of clamp units 52b, each driven by an air actuator (not shown), are provided on the outer periphery of the chuck table 52.

[0054] Each clamp unit 52b clamps the frame 19 of the wafer unit 21 held by suction on the holding surface 52a. A second drive source (not shown), such as a motor, that rotates the chuck table 52 around a predetermined rotation axis along the Z-axis direction is provided below the chuck table 52.

[0055] The second drive source is supported by an X-axis direction moving plate (not shown). The X-axis direction moving plate is slidably supported on a pair of guide rails (not shown) arranged along the X-axis direction. A nut portion (not shown) is provided on the underside of the X-axis direction moving plate.

[0056] A screw shaft (not shown) is rotatably connected to the nut portion and is disposed along the X-axis direction between the pair of guide rails. A third drive source (not shown), such as a stepping motor, that rotates the screw shaft is provided at one end of the screw shaft.

[0057] The X-axis moving plate, a pair of guide rails, a nut portion, a screw shaft, a third drive source, etc. constitute a ball screw type processing feed unit (not shown) that moves the chuck table 52 and the second drive source along the X-axis direction.

[0058] By operating the processing feed unit, the chuck table 52 moves between the loading / unloading area A1 near the cassette table 8 and the processing area A2. During laser processing, the chuck table 52 moves back and forth within the processing area A2.

[0059] An imaging unit 54 is provided above the movement path of the chuck table 52. The imaging unit 54 has a camera including an objective lens and an imaging element such as a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor.

[0060] Based on an image obtained by imaging the front surface 11a of the wafer 11 with the imaging unit 54, the chuck table 52 is rotated around the Z-axis direction so that the planned dividing line 13 is approximately parallel to the X-axis direction.

[0061] In the X-axis direction, a laser beam irradiation unit 56 is provided closer to the processing area A2 than the imaging unit 54. The laser beam irradiation unit 56 has a cylindrical casing 58 whose longitudinal portion is arranged along the Y-axis direction, a condenser 60 including a condensing lens, and the like.

[0062] A laser oscillator (not shown) having a laser medium made of Nd:YAG, Nd:YVO4, or the like is provided in the casing 58. The laser oscillator is provided with a light source (not shown) such as a laser diode that irradiates the laser medium with excitation light.

[0063] A pulse generator (not shown) for controlling the operation of the light source is connected to the light source. The pulse generator controls pulse characteristics such as the pulse width and repetition frequency of the laser beam L (see FIG. 7). Casing 58 is also provided with a wavelength conversion unit (not shown) having a nonlinear optical crystal for generating harmonics.

[0064] The laser beam L is emitted from a laser oscillator and then converted in a wavelength conversion section to have a main peak at a predetermined wavelength (for example, 355 nm, which is the wavelength absorbed by the wafer 11), and is then irradiated from the condenser 60 toward the holding surface 52a of the chuck table 52 arranged in the processing area A2.

[0065] A ball screw type first Y-axis direction moving unit (not shown) is connected to the casing 58. The first Y-axis direction moving unit is used to index and feed the condenser 60 along the Y-axis direction.

[0066] After laser processing of the wafer 11 in the processing area A2, the chuck table 52 returns to the load-in / load-out area A1. A second transport unit 62 is provided on the rear side of the load-in / load-out area A1 to transport the wafer unit 21 from the chuck table 52 disposed in the load-in / load-out area A1 to the coating / cleaning unit 16.

[0067] The second transport unit 62 has an arm with a lifting mechanism such as an air cylinder at its tip. A suction mechanism for adsorbing the frame 19 is provided at the bottom end of the lifting mechanism. A ball screw-type second Y-axis direction movement unit (not shown) that moves the arm along the Y-axis direction is connected to the base end of the arm.

[0068] An ultraviolet irradiation unit 64 is provided below the arm of the second transport unit 62. The ultraviolet irradiation unit 64 has a linear arm. A disk-shaped head portion 66 having approximately the same outer diameter as the outer diameter of the container 24 is provided at the tip of the arm.

[0069] A disk-shaped recess is formed in the head portion 66 so as to be exposed downward. A plurality of cylindrical ultraviolet lamps 68 (see FIG. 10) are disposed in this recess. The ultraviolet lamps 68 are, for example, low-pressure mercury lamps.

[0070] Ultraviolet (UV) rays 68a emitted from the ultraviolet lamp 68 include wavelengths of 185 nm and 254 nm. The ultraviolet rays 68a are emitted from the head portion 66 toward substantially the entire holding surface 18a.

[0071] A ball screw-type third Y-axis direction moving unit (not shown) that moves the arm along the Y-axis direction is provided at the base end of the arm. The third Y-axis direction moving unit moves the head part 66 between an irradiation position B1 that covers the coating / cleaning unit 16 and a retracted position B2 behind the irradiation position B1.

[0072] The wafer 11, which has been cleaned and dried in the coating / cleaning unit 16 and then irradiated with ultraviolet light 68a by the ultraviolet light irradiation unit 64, is then loaded into the cassette 6 using the first transport unit 14, a pair of guide rails 12, and the push-pull arm 10.

[0073] An operation panel 70 for inputting commands from an operator to the laser processing device 2 is provided on one side of the housing of the laser processing device 2. The operation panel 70 is a push-button type user interface.

[0074] The laser processing device 2 is also provided with a display device 72 such as a liquid crystal display. The display device 72 displays processing conditions input by the operator via the operation panel 70, images acquired by the imaging unit 54, and the like.

[0075] The display device 72 may be a touch panel that functions as a display and an input device. In this case, the operation panel 70 is omitted. Each component of the laser processing device 2 is controlled by a control unit (not shown).

[0076] The control unit is configured by a computer including, for example, a processor (processing device) represented by a CPU (Central Processing Unit), a main storage device such as a DRAM (Dynamic Random Access Memory), and an auxiliary storage device such as a flash memory.

[0077] The auxiliary storage device stores software including a predetermined program. The functions of the control unit are realized by operating the processor and the like in accordance with this software.

[0078] Next, we will explain the method for processing the wafer 11 using the laser processing device 2. First, the wafer unit 21 is transferred from the cassette 6 to the coating / cleaning unit 16, and the surface 11a of the wafer 11 is coated with a protective film 23a (protective film coating step S10).

[0079] Fig. 5 is a diagram showing the protective film coating step S10. Note that the air injection unit 46 is omitted in Fig. 5. Similarly, the air injection unit 46 is omitted in Figs. 8 and 10.

[0080] In the protective film coating step S10, first, the back surface 11b side is suction-held by the holding surface 18a via the dicing tape 17 so that the front surface 11a is exposed upward. Next, the spinner table 18 is rotated at a predetermined speed (for example, a predetermined value between 10 rpm and 100 rpm).

[0081] Furthermore, a first nozzle 32 is positioned above the central region of the holding surface 18a, and the first nozzle 32 applies the protective film agent 23 to the surface 11a. The applied protective film agent 23 spreads over the entire surface 11a due to centrifugal force. Thereafter, the application of the protective film agent 23 from the first nozzle 32 is stopped, and the rotation of the spinner table 18 is continued, thereby drying the protective film agent 23.

[0082] As a result, a protective film 23a having a substantially uniform thickness (for example, a predetermined value of 0.5 μm to 10 μm) is formed on the surface 11a. Figure 6 is a cross-sectional view of a portion of the wafer 11 covered with the protective film 23a.

[0083] After the protective film coating step S10, the wafer unit 21 is transported to the chuck table 52 and suction-held by the holding surface 52a. Then, an image of the surface 11a is acquired by the imaging unit 54, and alignment is performed by performing pattern matching or the like based on the image.

[0084] Based on the alignment result, the chuck table 52 is rotated slightly so that one planned dividing line 13 is approximately parallel to the X-axis direction. Thereafter, the chuck table 52 is moved to the processing area A2 and placed directly below the laser beam irradiation unit 56.

[0085] Then, the focal point of the laser beam L is positioned at one end of one of the division lines 13 on the surface 11a, and the chuck table 52 is moved along the X-axis direction to irradiate the laser beam L onto the surface 11a along the one of the division lines 13 (laser processing step S20). Fig. 7 is a diagram showing the laser processing step S20.

[0086] When the wafer 11 is subjected to ablation processing by irradiation with the laser beam L, the protective film 23a and the circuit layer 11c are partially removed along the one planned dividing line 13, and a laser processed groove 11d of a predetermined depth is formed in the semiconductor substrate of the wafer 11. Processing conditions are, for example, as follows.

[0087] Laser medium: Nd:YAG Wavelength: 355nm Average power: 0.1W to 100W (typically 0.5W to 15W) Repetition rate: 20kHz to 50,000kHz Focused spot diameter: 1.0 μm to 100 μm (typically 30 μm to 60 μm) Pulse width: 10fs to 500ns Machining feed rate: 20mm / s to 5000mm / s (typically 100mm / s to 1000mm / s)

[0088] After irradiating one planned dividing line 13 from one end to the other along the X-axis direction with the laser beam L, the condenser 60 is indexed and moved a predetermined length along the Y-axis direction, and the laser beam L is similarly irradiated along another planned dividing line 13 adjacent to the one planned dividing line 13 in the Y-axis direction.

[0089] After the laser beam L has been applied along all of the division lines 13 extending in one direction, the chuck table 52 is rotated by 90 degrees. Then, the laser beam L is applied in the same manner along all of the other division lines 13 that are perpendicular to the one direction. As a result, laser processed grooves 11d are formed along all of the division lines 13.

[0090] In the laser processing step S20, the melted material of the wafer 11 becomes debris 27, which scatters and adheres to the upper surface of the protective film 23a. After the laser processing step S20, the wafer unit 21 is transported to the coating / cleaning unit 16, where the protective film 23a is washed and removed with cleaning water 25 (protective film removing step S30). Figure 8 shows the protective film removing step S30.

[0091] In the protective film removal step S30, first, the back surface 11b side is suction-held by the holding surface 18a, and then, while the second nozzle 40 is oscillated within a predetermined angular range, cleaning water 25 is sprayed from the second nozzle 40 onto the front surface 11a, and the spinner table 18 is rotated at a predetermined speed (e.g., 300 rpm).

[0092] After the protective film 23a is dissolved in the cleaning water 25, it is removed from the surface 11a by centrifugal force. At this time, the debris 27 is also removed from the surface 11a together with the protective film 23a. After cleaning for a predetermined time, the spraying of the cleaning water 25 from the second nozzle 40 is stopped.

[0093] Then, the spinner table 18 is rotated at a predetermined speed (for example, 2000 rpm) for a predetermined time, thereby drying the wafer 11. Figure 9 is a cross-sectional view of a portion of the wafer 11 after the protective film removing step S30.

[0094] The protective film 23a and debris 27 are almost completely removed by the protective film removal step S30, but the applicant's thorough investigation revealed that organic matter of several nanometers to several tens of nanometers originating from the protective film 23a remains on the surface 11a after the protective film removal step S30.

[0095] Specifically, C4H8NO, C5H8NO, C7H10 NO, C8H 12 Compounds containing nitrogen atoms (N) and having a molecular formula such as NO remain on the surface 11a in thicknesses of several to several tens of nanometers. The compounds containing nitrogen atoms are thought to be derived from the above-mentioned polyvinylpyrrolidone or the like used as the water-soluble resin. In addition to the compounds containing nitrogen atoms, compounds having molecular formulas such as C2H3O and C4H5O also remain on the surface 11a.

[0096] The applicant has found that when organic matter containing nitrogen atoms originating from such protective film 23a remains on surface 11a to a thickness of several nanometers to several tens of nanometers, the adhesion between surface 11a and sealing resin 29 is insufficient compared to when such organic matter does not remain.

[0097] When the organic substance containing nitrogen atoms remains on the surface 11a, the contact angle of the sealing resin 29 with the surface 11a is thought to be relatively small compared to when the organic substance containing nitrogen atoms does not remain on the surface 11a.

[0098] However, the applicant has found that, despite the smaller contact angle, due to some interaction between the organic material containing nitrogen atoms and the sealing resin 29, the adhesion of the sealing resin 29 to the surface 11a is lower than when the organic material containing nitrogen atoms does not remain on the surface 11a.

[0099] Therefore, in this embodiment, in order to remove this organic matter, after the protective film removal step S30, ultraviolet light 68a is irradiated onto the surface 11a to remove the organic matter remaining on the surface 11a and originating from the protective film 23a (remaining organic matter removal step S40). Figure 10 is a diagram showing the remaining organic matter removal step S40.

[0100] In the remaining organic matter removal step S40, first, the head 66 of the ultraviolet irradiation unit 64 is placed at the irradiation position B1. Then, ultraviolet rays 68a are irradiated onto the entire front surface 11a of the wafer 11, the back surface 11b of which is suction-held by the stationary spinner table 18.

[0101] For example, if the illuminance of ultraviolet 68a is 50 (W / m 2 ) or more, and the exposure time is 30 (s) or more. In this embodiment, the illuminance is 50 (W / m 2 ) or more 70(W / m 2 ) and the exposure time is set to 120 (s). Also, the distance C from the ultraviolet lamp 68 to the surface 11a of the wafer 11 is set to about 2 cm.

[0102] To explain an example of the mechanism for removing remaining organic matter, first, ultraviolet light 68a is irradiated in a clean room atmosphere containing oxygen, and the ultraviolet light 68a with a wavelength of 185 nm reacts with oxygen molecules (O2), generating ozone (O3).

[0103] Furthermore, ultraviolet light 68a with a wavelength of 254 nm reacts with this ozone to generate active oxygen, which then decomposes organic matter composed of carbon (C), hydrogen (H), nitrogen (N), etc. into volatile substances such as carbon dioxide (CO2), carbon monoxide (CO), water (H2O), and nitrogen dioxide (NO2).

[0104] It should be noted that the ultraviolet light 68a with a wavelength of 254 nm may directly react with organic matter to decompose the organic matter into volatile substances, or other reaction processes may occur.

[0105] In any case, by irradiating ultraviolet light 68a, the organic matter originating from protective film 23a remaining on surface 11a after protective film removal step S30 and before remaining organic matter removal step S40 can be reduced to the same extent as when surface 11a is not covered with protective film 23a.

[0106] After the remaining organic substance removal step S40, the wafer unit 21 is removed from the laser processing apparatus 2, and the coating region 15a (see FIG. 11) corresponding to the surface of each device 15 is coated with a sealing resin 29 (sealing resin coating step S52). The surfaces of the devices 15 are located on the surface 11a of the wafer 11.

[0107] In the sealing resin coating step S52, for example, a liquid sealing resin is supplied to the surface 11a from a dispenser (not shown). The liquid sealing resin may be, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a novolac type epoxy resin, an aliphatic type epoxy resin, or a glycidylamine type epoxy resin.

[0108] The liquid sealing resin supplied to the front surface 11a is pressed toward the front surface 11a to spread it over the entire front surface 11a, and then subjected to a thermal curing process to solidify it, thereby covering the front surface 11a with the sealing resin 29. Figure 11 is a cross-sectional view of a portion of the wafer 11 covered with the sealing resin 29.

[0109] When the surface 11a is sealed with the sealing resin 29, the sealing resin 29 also fills the circuit layer 11c and the laser-processed grooves 11d in addition to the surface of the device 15. Therefore, the device 15 is sealed with the sealing resin 29 not only on its surface but also on the four side surfaces surrounding the surface.

[0110] After the sealing resin coating step S52, the sealing resin 29 and the wafer 11 are cut along each of the planned dividing lines 13 using a cutting device 80 (see FIG. 12) (cutting step S54). FIG. 12 is a diagram showing the cutting step S54.

[0111] The cutting device 80 has a chuck table 82 that includes a holding surface that suction-holds the wafer unit 21. The chuck table 82 is movable along the X-axis direction by a ball screw type X-axis direction moving unit (not shown).

[0112] A cutting unit 84 is provided above the chuck table 82. The cutting unit 84 has a spindle housing 86 whose longitudinal portion is disposed along the Y-axis direction. A cylindrical spindle 88 is partially rotatably housed in the spindle housing 86.

[0113] A rotary drive source (not shown), such as a motor, is provided at the base end of the spindle 88. The tip of the spindle 88 protrudes from the spindle housing 86, and a cutting blade 90 having an annular cutting edge is attached to this tip.

[0114] In the cutting step S54, first, alignment is performed using an imaging unit (not shown) to position one planned division line 13 substantially parallel to the X-axis direction. Note that, since terminals and the like (not shown) that are in a predetermined positional relationship with the planned division line 13 are exposed on the upper surface of the sealing resin 29, the position of the planned division line 13 can be identified by imaging the upper surface of the sealing resin 29.

[0115] Next, the cutting blade 90 is rotated in the predetermined direction D, and the lower end of the rotating cutting blade 90 is positioned between the holding surface of the chuck table 82 and the dicing tape 17 .

[0116] Then, while supplying cutting water such as pure water to the cutting blade 90, the chuck table 82 is moved in a predetermined direction E so as to perform a down cut relative to the rotation direction of the cutting blade 90. In this manner, the wafer 11 and the sealing resin 29 are cut along each of the planned division lines 13 to divide the wafer 11 into a plurality of package devices 31.

[0117] In the first embodiment, the remaining organic matter removal process S40 removes organic matter derived from the protective film 23a, thereby reducing the amount of organic matter remaining on the surface 11a to the same extent as when the surface 11a is not covered with the protective film 23a.

[0118] This improves the adhesion between the surface 11a and the sealing resin 29 compared to when the remaining organic matter removal step S40 is not performed. Therefore, it is possible to prevent the debris 27 from adhering to the surface 11a and improve the adhesion between the surface 11a and the sealing resin 29 at the same time.

[0119] Next, a second embodiment will be described. Fig. 13 is a flow diagram of a method for manufacturing a packaged device 39 (see Fig. 14(B)) according to the second embodiment. The steps from the protective film coating step S10 to the remaining organic matter removal step S40 are the same as those in the first embodiment, and therefore the description will be omitted.

[0120] After the remaining organic substance removing step S40, the wafer 11 is divided into device chips 33 (see FIG. 14(A)) by a cutting device 80 (cutting step S56). FIG. 14(A) is a partial cross-sectional side view showing a plurality of device chips 33.

[0121] After the cutting step S56, the back surface side of one device chip 33 corresponding to the back surface 11b is placed on one surface of the wiring board 37, and further, the device 15 is electrically connected to the wiring board 37 by the metal wire 35.

[0122] Thereafter, the covered region 15a, the four side surfaces of the device 15, the metal wires 35, one surface of the wiring board 37, etc. are sealed with sealing resin 29 so that the other surface of the wiring board 37 is exposed (sealing resin coating step S58). In this manner, a packaged device 39 is formed.

[0123] 14(B) is a cross-sectional view of the packaged device 39. Packaged devices 39 are formed in the same manner for the other device chips 33. In the second embodiment, the cutting step S56 and the sealing resin coating step S58 are collectively referred to as a packaged device forming step S50.

[0124] In the second embodiment, the remaining organic matter removal process S40 removes organic matter derived from the protective film 23a, thereby reducing the amount of organic matter remaining on the surface 11a to the same extent as when the surface 11a is not covered with the protective film 23a.

[0125] This improves the adhesion between the surface 11a and the sealing resin 29 compared to when the remaining organic matter removal step S40 is not performed. Therefore, it is possible to prevent the debris 27 from adhering to the surface 11a and improve the adhesion between the surface 11a and the sealing resin 29 at the same time.

[0126] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. For example, in the second embodiment, the surface of the device chip 33 and one surface of the wiring substrate 37 can be electrically connected by a conductive member such as a solder ball (not shown) without using the metal wire 35.

[0127] A sealing resin (also called underfill) such as epoxy resin is provided between the surface of the device chip 33 and one side of the wiring substrate 37. In this case, too, the amount of organic matter remaining on the surface side of the device chip 33 is reduced by the remaining organic matter removal step S40, so that the adhesion between the device chip 33 and the sealing resin can be improved. [Explanation of symbols]

[0128] 2: laser processing device, 4: base, 4a: opening, 6: cassette, 8: cassette table 10: Push-pull arm, 12: Guide rail, 14: First transport unit 11: wafer, 11a: front surface, 11b: back surface, 11c: circuit layer 11d: laser-processed groove, 13: planned division line, 15: device, 15a: coated area 16: Coating and cleaning unit 18: spinner table, 18a: holding surface, 18b: clamp unit 17: Dicing tape, 19: Frame, 21: Wafer unit 20: First driving source, 22: Air cylinder, 24: Container, 26: Leg, 28: Gap 23: protective film agent, 23a: protective film, 25: cleaning water, 27: debris, 29: sealing resin 30: application unit, 32: first nozzle, 34: first arm, 36: motor 31: Packaged device, 33: Device chip 35: Metal wire, 37: Wiring substrate, 39: Package device 38: cleaning unit, 40: second nozzle, 42: second arm, 44: motor 46: Air injection unit, 48: Third nozzle, 50: Third arm 52: chuck table, 52a: holding surface, 52b: clamp unit 54: Imaging unit 56: laser beam irradiation unit, 58: casing, 60: condenser 62: Second transport unit 64: ultraviolet irradiation unit, 66: head part, 68: ultraviolet lamp, 68a: ultraviolet light 70: Operation panel, 72: Display device 80: cutting device, 82: chuck table, 84: cutting unit 86: Spindle housing, 88: Spindle, 90: Cutting blade A1: Loading / unloading area, A2: Processing area, B1: Irradiation position, B2: Evacuation position C: distance, D, E: specified direction, L: laser beam S10: Protective film coating process, S20: Laser processing process, S30: Protective film removal process S40: Remaining organic matter removal process, S50: Package device formation process S52: Sealing resin coating process, S54: Cutting process S56: Cutting process, S58: Sealing resin coating process

Claims

1. A method for processing a wafer in which a plurality of planned dividing lines are set on a surface so as to intersect with each other, and in which devices are formed in each of a plurality of regions partitioned by the plurality of planned dividing lines, comprising: a protective film coating step of applying a protective film agent to the surface of the wafer and then drying the protective film agent to form a protective film, thereby covering the surface with the protective film; a laser processing step of irradiating a laser beam having a wavelength absorbed by the wafer along each of the planned dividing lines on the surface of the wafer after the protective film coating step, thereby forming a plurality of laser processed grooves; a protective film removal step of cleaning and removing the protective film after the laser processing step; a residual organic matter removal step of irradiating the surface of the wafer with ultraviolet light after the protective film removal step to remove organic matter derived from the protective film remaining on the surface of the wafer; a sealing resin coating step of coating a coating area corresponding to each device located on the surface of the wafer with a sealing resin after the remaining organic substance removal step; A wafer processing method comprising:

2. 2. The wafer processing method according to claim 1, wherein the organic matter remaining on the surface of the wafer after the protective film removal step and before the remaining organic matter removal step includes a compound containing a nitrogen atom.

3. Each laser-processed groove formed in the laser processing step has a predetermined depth that does not reach the back surface of the wafer located on the opposite side from the front surface of the wafer, 3. The wafer processing method according to claim 1, further comprising a cutting step of cutting the wafer sealed with the sealing resin and the sealing resin along each planned division line to divide the wafer into a plurality of device chips.

4. 1. A method for manufacturing a package device, comprising: manufacturing a plurality of package devices from a wafer having a surface on which a plurality of planned dividing lines are set so as to intersect, and having devices formed in each of a plurality of regions partitioned by the plurality of planned dividing lines, the method comprising: a protective film coating step of applying a protective film agent to the surface of the wafer and then drying the protective film agent to form a protective film, thereby covering the surface with the protective film; a laser processing step of irradiating a laser beam having a wavelength absorbed by the wafer along each of the planned dividing lines on the surface of the wafer after the protective film coating step, thereby forming a plurality of laser processed grooves; a protective film removal step of cleaning and removing the protective film after the laser processing step; a residual organic matter removal step of irradiating the surface of the wafer with ultraviolet light after the protective film removal step to remove organic matter derived from the protective film remaining on the surface of the wafer; a package device forming step of forming a plurality of package devices, each of which is located on the surface of the wafer and has a covering region corresponding to each device covered with a sealing resin, after the remaining organic substance removing step; A method for manufacturing a packaged device, comprising:

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