Device chip manufacturing method

Abstract

To provide a method for manufacturing a device chip that allows appropriate division of a workpiece.SOLUTION: A method for manufacturing a device chip is to manufacture device chips by dividing a workpiece including, on its front side, a laminate that forms devices provided in a plurality of areas partitioned by a plurality of intersecting division scheduled lines, and the method includes: a processing groove forming step of irradiating the laminate with a laser beam with a wavelength having absorbency from the front side of the workpiece along the division scheduled line to form processing grooves for dividing the laminate along the division scheduled lines; a resin layer forming step of forming a resin layer on the front side of the workpiece after the processing groove forming step; and a division step of dividing the workpiece and the resin layer along the division scheduled line after the resin layer forming step.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing device chips by dividing a workpiece. [Background technology]

[0002] The device chip manufacturing process uses a wafer in which devices are formed in multiple regions defined by multiple intersecting dividing lines (streets). By dividing the wafer along the dividing lines, multiple device chips, each equipped with a device, are obtained. The device chips are incorporated into various electronic devices, such as mobile phones and personal computers.

[0003] A cutting device is used to divide the wafer. The cutting device is equipped with a chuck table that holds the workpiece and a cutting unit that cuts the workpiece. The cutting unit has a built-in spindle, and an annular cutting blade is attached to the tip of the spindle. The wafer is held on the chuck table, and the cutting blade is rotated and cuts into the wafer, cutting the wafer along the planned division lines and dividing it into multiple device chips.

[0004] In recent years, developments have also been made in processes for dividing wafers using laser processing. For example, a laser beam with a wavelength that is transparent to the wafer is focused inside the wafer and scanned along the planned dividing line, thereby forming a modified layer inside the wafer along the planned dividing line. The area of the wafer where the modified layer is formed becomes more fragile than other areas. Therefore, when an external force is applied to a wafer with a modified layer formed thereon, the modified layer functions as a dividing starting point, dividing the wafer along the planned dividing line.

[0005] The device chips obtained by dividing the wafer are mounted by various mounting methods such as wire bonding mounting, flip-chip mounting, etc. For example, the device chips are bonded to a mounting substrate or other device chips via a film-like resin layer (adhesive film) that seals the device (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-92188 Summary of the Invention [Problem to be solved by the invention]

[0007] A laminate is formed on the surface of a workpiece (such as a wafer) used to manufacture device chips, with various thin films stacked on top of each other, such as a conductive film that functions as an electrode and an insulating film (e.g., a low-k film) that functions as an interlayer insulating film. This laminate forms devices and TEGs (Test Element Groups) for testing devices. Then, by forming a resin layer that seals the devices on the workpiece and then dividing the workpiece, device chips with resin bonding materials are obtained.

[0008] The laminate is also formed on the planned division line on the outside of the device. When dividing the workpiece into multiple device chips, the laminate remaining on the planned division line may hinder proper division of the workpiece. For example, when cutting the workpiece with a cutting blade, thin films contained in the laminate on the planned division line may be caught in the rotation of the cutting blade and peeled off, which may cause damage to the device or peeling of the resin layer. Furthermore, when dividing the workpiece by applying an external force to a workpiece on which a modified layer has been formed, the functional layer present on the planned division line may not be properly divided along with the workpiece, resulting in peeling of the laminate.

[0009] The present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing device chips that enables appropriate division of a workpiece. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided a method for manufacturing device chips by dividing a workpiece having, on its surface side, a laminate that constitutes devices provided in a plurality of regions partitioned by a plurality of intersecting planned division lines, the method comprising the steps of: a groove forming step of irradiating a laser beam having a wavelength that is absorbable by the laminate from the surface side of the workpiece along the planned division lines to form grooves that divide the laminate along the planned division lines; a resin layer forming step of forming a resin layer on the surface side of the workpiece after the groove forming step; and a resin layer forming step of forming a resin layer on the surface side of the workpiece after the resin layer forming step. The workpiece and the resin layer are processed along the planned dividing line, and a dividing step of dividing the workpiece and the resin layer along the planned dividing lines.

[0011] According to another aspect of the present invention, there is provided a method for manufacturing device chips by dividing a workpiece having, on its surface side, a laminate that constitutes devices provided in a plurality of regions partitioned by a plurality of intersecting planned dividing lines, to manufacture device chips, the method including: a processing groove forming step of irradiating, from the surface side of the workpiece along the planned dividing lines, a laser beam having a wavelength that is absorbed by the laminate to form processing grooves that divide the laminate along the planned dividing lines; a support member fixing step of fixing a support member to the surface side of the workpiece after the processing groove forming step; a backside grinding step of grinding the backside side of the workpiece after the support member fixing step; a support member removing step of removing the support member from the surface side of the workpiece after the backside grinding step; a resin layer forming step of forming a resin layer on the surface side of the workpiece after the support member removing step; and a dividing step of dividing the workpiece and the resin layer along the planned dividing lines after the resin layer forming step.

[0012] Preferably, the method for manufacturing a device chip further includes a backside pattern forming step of forming a pattern on the backside of the workpiece after the backside grinding step. Also, preferably, the method for manufacturing a device chip further includes a protective film forming step of forming a protective film on the frontside of the workpiece before the groove forming step. Also, preferably, the method for manufacturing a device chip further includes a plasma etching step of supplying an etching gas in a plasma state from the frontside of the workpiece after the groove forming step to remove processing strain or foreign matter remaining in the workpiece or the laminate.

[0013] Preferably, in the dividing step, a cutting blade is brought into contact with the workpiece and the resin layer while rotating, and the workpiece and the resin layer are cut along the planned dividing line. Preferably, the method for manufacturing a device chip further includes, before the dividing step, an expandable sheet adhering step of adhering an extensible expandable sheet to the workpiece, and the dividing step includes a modified layer forming step of forming a modified layer on the workpiece along the planned dividing line by irradiating the workpiece with a laser beam of a wavelength that is transparent to the workpiece, with the focal point of the laser beam positioned inside the workpiece, and an expanding step of expanding the expandable sheet after the modified layer forming step. [Effects of the Invention]

[0014] In a method for manufacturing a device chip according to one aspect of the present invention, a groove for dividing the laminate is formed along the planned dividing line before dividing the workpiece, thereby preventing peeling of the laminate when dividing the workpiece, and preventing damage to the device and peeling of the resin layer. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1(A) is a perspective view showing a workpiece, and FIG. 1(B) is a cross-sectional view showing a part of the workpiece. [Figure 2] FIG. 2 is a perspective view showing a workpiece supported by an annular frame. [Figure 3] FIG. 3(A) is a cross-sectional view showing the workpiece in the protective film forming step, and FIG. 3(B) is a cross-sectional view showing a part of the workpiece after the protective film forming step. [Figure 4] FIG. 4(A) is a cross-sectional view showing the workpiece in the groove forming step, and FIG. 4(B) is a cross-sectional view showing a part of the workpiece after the groove forming step. [Figure 5] 1 is a cross-sectional view showing a workpiece in a plasma etching step. [Figure 6] FIG. 6(A) is a perspective view showing the workpiece in the support member fixing step, and FIG. 6(B) is a cross-sectional view showing a part of the workpiece after the support member fixing step. [Figure 7] FIG. 7(A) is a perspective view showing the workpiece in the back grinding step, and FIG. 7(B) is a cross-sectional view showing a part of the workpiece after the back grinding step. [Figure 8] FIG. 2 is a cross-sectional view showing a portion of a workpiece on which a pattern layer is formed. [Figure 9] FIG. 10 is a perspective view showing the workpiece in a support member removing step. [Figure 10] FIG. 10 is a perspective view showing a workpiece in a resin layer forming step. [Figure 11] Figure 11(A) is a cross-sectional view showing the workpiece in the dividing step, Figure 11(B) is a cross-sectional view showing a portion of the workpiece in which a kerf is formed inside the machined groove, and Figure 11(C) is a cross-sectional view showing a portion of the workpiece in which a kerf is formed between a pair of machined grooves. [Figure 12] FIG. 12(A) is a cross-sectional view showing the workpiece in the modified layer forming step, and FIG. 12(B) is a cross-sectional view showing a part of the workpiece after the modified layer forming step. [Figure 13] FIG. 13(A) is a cross-sectional view showing the workpiece in the expanding step, and FIG. 13(B) is a cross-sectional view showing a part of the workpiece after the expanding step. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. First, an example of the structure of a workpiece that can be used in the method for manufacturing a device chip according to this embodiment will be described. Figure 1(A) is a perspective view showing a workpiece 11.

[0017] For example, the workpiece 11 is a disk-shaped wafer (substrate) made of a semiconductor such as silicon, and has a front surface (first surface) 11a and a back surface (second surface) 11b that are generally parallel to each other. However, there are no limitations on the material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a substrate made of a semiconductor other than silicon (GaAs, SiC, InP, GaN, etc.), sapphire, glass, ceramics, resin, metal, etc.

[0018] A laminate 13 including a plurality of stacked thin films is provided on the front surface 11a side of the workpiece 11. The laminate 13 includes various thin films such as conductive films that function as electrodes, wiring, terminals, etc., and insulating films that function as interlayer insulating films (for example, low-dielectric-constant insulating films (Low-k films)), and is formed over the entire front surface 11a side of the workpiece 11.

[0019] The workpiece 11 is divided into a plurality of rectangular regions by a plurality of planned division lines (streets) 15 arranged in a grid pattern so as to intersect with one another. Devices 17 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed in each of the plurality of regions divided by the planned division lines 15. However, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 17.

[0020] The device 17 is provided with a plurality of connection electrodes (bumps) 19 that protrude from the surface of the device 17. For example, the connection electrodes 19 are spherical electrodes made of a metal material such as solder, and are connected to other electrodes included in the device 17.

[0021] 1(B) is a cross-sectional view showing a part of the workpiece 11. A plurality of regions of the laminate 13 surrounded by the planned dividing lines 15 each constitute a device 17. For example, a semiconductor element is formed by the front surface 11a side of the workpiece 11 and a thin film included in the laminate 13. Furthermore, a part of the thin film (such as a low-k film) included in the laminate 13 is also formed on the planned dividing lines 15. Note that the part of the laminate 13 formed on the planned dividing lines 15 may constitute a TEG or the like used for inspecting the device 17.

[0022] A plurality of electrodes (buried electrodes, through electrodes) 21 are buried inside each of a plurality of regions defined by the dividing lines 15 of the workpiece 11. The electrodes 21 are formed in a columnar shape along the thickness direction of the workpiece 11 and are connected to the device 17. There are no limitations on the material of the electrodes 21, and metals such as copper, tungsten, and aluminum can be used, for example.

[0023] The electrodes 21 are each formed from the device 17 toward the back surface 11b of the workpiece 11, and the length (height) of the electrodes 21 is less than the thickness of the workpiece 11. Therefore, the electrodes 21 are not exposed on the back surface 11b of the workpiece 11, but are buried inside the workpiece 11. In addition, an insulating layer (not shown) is provided between the workpiece 11 and the electrodes 21 to insulate the workpiece 11 from the electrodes 21.

[0024] By subjecting the workpiece 11 to various processes such as cutting and laser processing, the workpiece 11 is divided along the planned division lines 15 to produce a plurality of device chips each including a device 17. When processing the workpiece 11, the workpiece 11 is supported by an annular frame for ease of handling.

[0025] 2 is a perspective view showing workpiece 11 supported by an annular frame 23. Frame 23 is an annular member made of metal such as SUS (stainless steel), and has a circular opening 23a at the center thereof that penetrates frame 23 in the thickness direction. The diameter of opening 23a is larger than the diameter of workpiece 11.

[0026] A circular tape 25 having a diameter larger than that of the workpiece 11 is attached to the rear surface 11b of the workpiece 11. For example, the tape 25 includes a circular film-like substrate and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. The adhesive layer may be an ultraviolet-curable resin that hardens when exposed to ultraviolet light.

[0027] With the workpiece 11 placed inside the opening 23a of the frame 23, the central portion of the tape 25 is stuck to the back surface 11b of the workpiece 11, and the outer periphery of the tape 25 is stuck to the frame 23. In this way, the workpiece 11 is supported by the frame 23 via the tape 25.

[0028] Next, a specific example of a method for manufacturing device chips will be described, in which device chips are manufactured by dividing the workpiece 11. In this embodiment, a groove for dividing the laminate 13 is formed along the dividing lines 15, a resin layer is formed on the front surface 11a of the workpiece 11, and then the workpiece 11 and the resin layer are divided along the dividing lines 15, thereby manufacturing device chips.

[0029] First, a protective film is formed on the surface 11a side (the laminate 13 side) of the workpiece 11 (protective film forming step). Fig. 3(A) is a cross-sectional view showing the workpiece 11 in the protective film forming step. For example, in the protective film forming step, a protective film is formed on the workpiece 11 by a spin coater 2.

[0030] The spin coater 2 includes a spinner table (chuck table) 4 that holds the workpiece 11. The upper surface of the spinner table 4 forms a flat holding surface 4a that holds the workpiece 11. The holding surface 4a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve, etc. formed inside the spinner table 4.

[0031] A rotation drive source (not shown), such as a motor, is connected to the spinner table 4 to rotate the spinner table 4 around a rotation axis that is roughly parallel to the vertical direction (height direction, up-down direction). In addition, a plurality of clamps 6 are provided around the periphery of the spinner table 4 to grip and fix the frame 23.

[0032] A protective film material supply unit 8 that supplies protective film material 10, which is the raw material for the protective film, is provided above the spinner table 4. For example, the protective film material supply unit 8 includes a nozzle that drops the protective film material 10 onto the workpiece 11 held by the spinner table 4.

[0033] In the protective film forming step, first, workpiece 11 is held by spinner table 4. Specifically, workpiece 11 is placed on spinner table 4 so that front surface 11a (laminate 13 side) faces upward and back surface 11b (tape 25 side) faces holding surface 4a. In addition, frame 23 is fixed by multiple clamps 6. In this state, when suction force (negative pressure) of a suction source is applied to holding surface 4a, workpiece 11 is suction-held by spinner table 4 via tape 25.

[0034] Next, while the spinner table 4 is being rotated, the protective film material 10 is supplied from the nozzle of the protective film material supply unit 8 toward the workpiece 11. As a result, the surface 11a side of the workpiece 11 is covered with the protective film material 10. Thereafter, the protective film material 10 applied to the workpiece 11 is dried and hardened, thereby forming a protective film on the surface 11a side of the workpiece 11.

[0035] 3B is a cross-sectional view showing a part of the workpiece 11 after the protective film forming step. A protective film 27 is formed on the front surface 11a side of the workpiece 11 so as to cover the laminate 13 and the connection electrodes 19.

[0036] There is no limitation on the material of the protective film 27. For example, a water-soluble resin such as PVA (polyvinyl alcohol), PEG (polyethylene glycol), PEO (polyethylene oxide), or PVP (polyvinylpyrrolidone) can be used as the protective film material 10 (see FIG. 3(A)). In this case, the protective film 27 is made of a water-soluble resin. Alternatively, a resin tape may be attached to the surface 11a of the workpiece 11 as the protective film 27.

[0037] Next, a laser beam having a wavelength that is absorbable by the laminate 13 is irradiated from the front surface 11a side of the workpiece 11 along the intended dividing lines 15 to form grooves that divide the laminate 13 along the intended dividing lines 15 (groove forming step). Fig. 4(A) is a cross-sectional view showing the workpiece 11 in the groove forming step.

[0038] In the machining groove forming step, laser machining is performed on the workpiece 11 by the laser machining device 20. The X-axis direction (machining feed direction, first horizontal direction) and the Y-axis direction (indexing feed direction, second horizontal direction) are perpendicular to each other. The Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0039] The laser processing device 20 includes a chuck table (holding table) 22 that holds the workpiece 11. The upper surface of the chuck table 22 is a circular flat surface that is approximately parallel to the horizontal direction (XY plane direction), and constitutes a holding surface 22a that holds the workpiece 11. The holding surface 22a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like that are formed inside the chuck table 22.

[0040] A ball screw type moving mechanism (not shown) that moves the chuck table 22 along the X-axis and Y-axis directions is connected to the chuck table 22. A rotation drive source (not shown) such as a motor that rotates the chuck table 22 around a rotation axis that is approximately perpendicular to the holding surface 22a is also connected to the chuck table 22. Furthermore, a plurality of clamps 24 that grip and fix the frame 23 are provided around the periphery of the chuck table 22.

[0041] The laser processing apparatus 20 also includes a laser irradiation unit 26. The laser irradiation unit 26 includes a laser oscillator (not shown) such as a YAG laser, YVO4 laser, or YLF laser, and a laser processing head 28 arranged above the chuck table 22. The laser processing head 28 has a built-in optical system that guides a pulsed laser beam emitted from the laser oscillator to the workpiece 11, and the optical system includes optical elements such as a condenser lens that condenses the laser beam. The laminate 13 is processed by a laser beam 30 irradiated from the laser irradiation unit 26.

[0042] In the machined groove forming step, first, the workpiece 11 is held by the chuck table 22. Specifically, the workpiece 11 is placed on the chuck table 22 so that the front surface 11a side (the laminate 13 side) faces upward and the back surface 11b side (the tape 25 side) faces the holding surface 22a. In addition, the frame 23 is fixed by a plurality of clamps 24. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 22a, the workpiece 11 is suction-held by the chuck table 22 via the tape 25.

[0043] Next, the chuck table 22 is rotated to align the length direction of the predetermined dividing line 15 with the processing feed direction (X-axis direction). Also, the position of the chuck table 22 in the indexing feed direction (Y-axis direction) is adjusted so that the position in the Y-axis direction of the area irradiated with the laser beam 30 coincides with the position in the Y-axis direction of the inner areas at both ends of the dividing line 15 in the width direction (for example, the center in the width direction of the dividing line 15). Furthermore, the position of the laser processing head 28 and the arrangement of the optical system are adjusted so that the focal point of the laser beam 30 is positioned at the same height (position in the Z-axis direction) as the surface or interior of the laminate 13.

[0044] Then, while irradiating the laser beam 30 from the laser processing head 28, the chuck table 22 is moved along the processing feed direction (X-axis direction). As a result, the chuck table 22 and the laser beam 30 move relatively along the processing feed direction (X-axis direction) at a predetermined speed (processing feed speed). As a result, the laser beam 30 is irradiated along the intended division line 15 from the front surface 11a side (laminate 13 side) of the workpiece 11.

[0045] The irradiation conditions of the laser beam 30 are set so that ablation processing is performed on the laminate 13. Specifically, the wavelength of the laser beam 30 is set so that at least a portion of the laser beam 30 is absorbed by the laminate 13. In other words, the laser beam 30 is a laser beam with a wavelength that is absorbed by the laminate 13. Other irradiation conditions of the laser beam 30 are also set appropriately so that ablation processing is appropriately performed on the laminate 13. For example, the irradiation conditions of the laser beam 30 can be set as follows. Wavelength: 355nm Average output: 2W Repetition frequency: 200kHz Processing feed rate: 400mm / s

[0046] When the laser beam 30 is irradiated onto the laminate 13 along the intended dividing lines 15, the region of the laminate 13 irradiated with the laser beam 30 is removed by ablation. As a result, a linear processed groove 29 is formed along the intended dividing lines 15 on the front surface 11a side of the workpiece 11.

[0047] The grooves 29 are formed so that their depth is equal to or greater than the thickness of the laminate 13. Therefore, when the grooves 29 are formed, the laminate 13 is divided along the planned division lines 15, and the surface 11a side of the workpiece 11 is exposed inside the grooves 29. Depending on the irradiation conditions of the laser beam 30, a small portion of the surface 11a side of the workpiece 11 may also be removed, forming grooves 29 with a depth greater than the thickness of the laminate 13.

[0048] In the groove forming step, grooves 29 of a desired depth may be formed by irradiating the laser beam 30 multiple times on the same region on each of the planned division lines 15. In this case, it is possible to form deep grooves 29 while suppressing the average output of the laser beam 30.

[0049] The laser beam 30 may be shaped so that the region of the laminate 13 to be irradiated with the laser beam 30 (irradiated region) is linear or rectangular. In this case, the laser beam 30 is irradiated onto the laminate 13 so that the length direction (longitudinal direction) of the irradiated region is aligned with the width direction of the planned division line 15, and a wide processed groove 29 is formed.

[0050] Furthermore, a plurality of grooves 29 may be formed inside each of the division lines 15. For example, a pair of grooves 29 that are generally parallel to each other may be formed at one end and the other end of the division line 15 in the width direction (see FIG. 11(C)). In this case, a laser beam 30 is irradiated onto one end of the division line 15 to form one groove 29, and then a laser beam 30 is irradiated onto the other end of the division line 15 to form the other groove 29. Alternatively, a pair of grooves 29 may be formed simultaneously by scanning the laser beam 30 along the division line 15 while branching it so that it is focused at two points.

[0051] When the workpiece 11 or the laminate 13 is subjected to ablation processing, melted material (debris) of the workpiece 11 or the laminate 13 is generated and scattered. However, if a protective film 27 is formed on the surface 11a side of the workpiece 11, the debris is less likely to adhere to the workpiece 11 or the laminate 13, and contamination of the workpiece 11 and the device 17 is prevented.

[0052] Thereafter, the same procedure is repeated to irradiate the laser beam 30 along the other division lines 15. As a result, grooves 29 are formed in a lattice pattern along all of the division lines 15.

[0053] 4(B) is a cross-sectional view showing a part of the workpiece 11 after the groove forming step. By performing the groove forming step, grooves 29 are formed along the planned dividing lines 15, dividing the laminate 13 and reaching the surface 11a of the workpiece 11.

[0054] When the machining groove formation step is completed, the protective film 27 is removed. As a result, foreign matter such as debris adhering to the protective film 27 is removed together with the protective film 27. If the protective film 27 is made of a water-soluble resin, the protective film 27 can be easily removed simply by supplying a cleaning liquid such as pure water to the workpiece 11, and the process of removing the protective film 27 is simplified.

[0055] The protective film forming step can be omitted if the amount of debris generated in the groove forming step is small or if scattering of debris is not a problem, etc. In this case, the step of removing the protective film 27 after the groove forming step is also omitted.

[0056] Next, a plasma-state etching gas is supplied from the surface 11a side of the workpiece 11 to remove processing damage or foreign matter remaining in the workpiece 11 or the laminate 13 (plasma etching step). FIG. 5 is a cross-sectional view showing the workpiece 11 in the plasma etching step. In the plasma etching step, plasma etching is performed on the workpiece 11 and the laminate 13 by the plasma processing device 40. Note that in the plasma etching step, the workpiece 11 does not have to be supported by the frame 23.

[0057] The plasma processing apparatus 40 includes a chamber 42. The interior of the chamber 42 corresponds to a processing space where plasma processing is performed. An opening 42b is provided in a sidewall 42a of the chamber 42, through which the workpiece 11 passes when the workpiece 11 is loaded and unloaded.

[0058] A gate 44 that opens and closes the opening 42b is provided on the outside of the side wall 42a. An opening / closing unit 46 such as an air cylinder is connected to the gate 44. The opening / closing unit 46 moves the gate 44 downward to expose the opening 42b, allowing the workpiece 11 to be carried into and out of the processing space. The opening / closing unit 46 moves the gate 44 upward to close the opening 42b, thereby sealing the processing space.

[0059] A piping 48 such as a pipe is connected to the bottom wall 42c of the chamber 42, and a decompression unit 50 such as an exhaust pump is connected to the piping 48. When the decompression unit 50 is operated with the opening 42b closed by the gate 44, the inside of the chamber 42 is evacuated and reduced in pressure.

[0060] A table base 52 is provided inside the chamber 42. The table base 52 includes a cylindrical holding portion 54 and a cylindrical support portion 56 connected to the holding portion 54. The diameter of the support portion 56 is smaller than the diameter of the holding portion 54, and the support portion 56 is formed downward from the center of the lower surface of the holding portion 54.

[0061] A chuck table (holding table) 58 for holding the workpiece 11 is provided on the upper surface of the holding part 54. The chuck table 58 has a disk-shaped main body 60 made of an insulating material, and a plurality of electrodes 62 are embedded inside the main body 60. Each of the plurality of electrodes 62 is connected to a DC power supply 64 capable of applying a predetermined voltage (for example, a high voltage of about 5 kV) to the electrode 62.

[0062] Furthermore, the main body 60 of the chuck table 58 is provided with a plurality of suction paths 60a that open on the upper surface of the main body 60. The suction paths 60a are connected to a suction pump 66 via suction paths 52a formed inside the table base 52.

[0063] When holding the workpiece 11 by the chuck table 58, first, the workpiece 11 is placed on the chuck table 58 and the suction pump 66 is operated. As a result, the workpiece 11 is attracted to the upper surface of the chuck table 58 by the suction force of the suction pump 66. In this state, when a voltage is applied to the multiple electrodes 62 by the DC power supply 64 to generate a potential difference between the electrodes 62, the workpiece 11 is attracted and held by electrostatic force. This makes it possible to hold the workpiece 11 on the chuck table 58 even when the inside of the chamber 42 is decompressed.

[0064] Furthermore, a flow path 52b is formed inside the table base 52. Both ends of the flow path 52b are connected to a circulation unit 68 that circulates a refrigerant. When the circulation unit 68 is operated, the refrigerant flows from one end of the flow path 52b to the other end, and the table base 52 is cooled.

[0065] A gas supply unit 70 that supplies an etching gas is connected to the top of the chamber 42. The gas supply unit 70 converts the etching gas into plasma outside the chamber 42 and supplies the plasma-state etching gas into the chamber 42.

[0066] Specifically, the gas supply unit 70 includes a metal supply pipe 72 through which an etching gas flows and is supplied to the chamber 42. One end (downstream side) of the supply pipe 72 is connected to the interior of the chamber 42 via an upper wall 42d of the chamber 42. The other end (upstream side) of the supply pipe 72 is connected to a gas supply source 80a via a valve 74a, a flow rate controller 76a, and a valve 78a, to a gas supply source 80b via a valve 74b, a flow rate controller 76b, and a valve 78b, and to a gas supply source 80c via a valve 74c, a flow rate controller 76c, and a valve 78c.

[0067] When predetermined gases are supplied from gas supply sources 80a, 80b, and 80c at predetermined flow rates, a mixed gas is generated in supply pipe 72. This mixed gas serves as the etching gas used to etch workpiece 11. For example, gas supply source 80a supplies a fluorine-based gas such as SF6, gas supply source 80b supplies oxygen gas (O2 gas), and gas supply source 80c supplies an inert gas such as He. However, the components, flow rate ratios, and the like of the gases supplied from gas supply sources 80a, 80b, and 80c can be changed as desired depending on the material of the workpiece and the processing conditions.

[0068] The gas supply unit 70 also includes an electrode 82 that applies a high-frequency voltage to the etching gas generated in the supply pipe 72. The electrode 82 is provided in the midstream portion of the supply pipe 72 so as to surround the supply pipe 72, and a high-frequency power supply 84 is connected to the electrode 82. The high-frequency power supply 84 applies a high-frequency voltage to the electrode 82, for example, with a voltage value of 0.5 kV or more and 5 kV or less and a frequency of 450 kHz or more and 2.45 GHz or less.

[0069] When a high-frequency voltage is applied to the etching gas flowing through the supply pipe 72 using the electrode 82 and the high-frequency power supply 84, the etching gas changes to a plasma state containing ions and radicals. The plasma-state etching gas is then supplied into the chamber 42 from a supply port 72a that opens at the downstream end of the supply pipe 72. In this way, the etching gas that has been converted into plasma outside the chamber 42 is supplied into the chamber 42.

[0070] A dispersion member 86 is attached to the inside of the upper wall 42d of the chamber 42 so as to cover the supply port 72a. The etching gas in a plasma state that flows into the chamber 42 from the supply pipe 72 is dispersed above the chuck table 58 by the dispersion member 86.

[0071] Furthermore, piping 88 such as a pipe is connected to the sidewall 42a of the chamber 42, and an inert gas supply source (not shown) that supplies inert gas is connected to the piping 88. When inert gas is supplied from the inert gas supply source to the chamber 42 via the piping 88, the interior of the chamber 42 is filled with inert gas (inner gas). Note that the piping 88 may be connected to a gas supply source 80c via a valve (not shown), a flow rate controller (not shown), or the like. In this case, the inert gas is supplied from the gas supply source 80c to the interior of the chamber 42 via the piping 88.

[0072] The etching gas supplied from the gas supply unit 70 is dispersed by a dispersion member 86 provided below the supply port 72a and supplied to the entire workpiece 11 held by the chuck table 58. The plasmatized etching gas then acts on the workpiece 11 and the laminate 13 (see FIG. 4(B)), and the workpiece 11 and the laminate 13 are subjected to plasma etching.

[0073] When the gas in a plasma state is supplied to the workpiece 11 and the laminate 13 after the groove formation step, processing strain (processing marks) formed inside the groove 29 and around the groove 29 by laser processing is removed. In addition, foreign matter such as debris adhering to the workpiece 11 and the laminate 13 is removed. This prevents a decrease in the flexural strength and quality of the device chips finally obtained by dividing the workpiece 11.

[0074] When the etching gas that has been converted into plasma outside the chamber 42 passes through the metal supply pipe 72, ions contained in the etching gas are adsorbed to the inner wall of the supply pipe 72, making it difficult for them to reach the inside of the chamber 42. As a result, an etching gas with a high ratio of radicals is introduced into the chamber 42 and supplied to the workpiece 11 and the laminate 13. The etching gas with a high ratio of radicals easily penetrates into the narrow regions inside the workpiece 11 and the laminate 13, making it easier for the etching gas to etch the inside of the groove 29 (see FIG. 4(B)).

[0075] When carrying out the above-described plasma etching, a mask layer may be formed on the laminate 13. For example, the mask layer is patterned so that the areas of the workpiece 11 or the laminate 13 that overlap with the planned dividing lines 15 are exposed. By supplying an etching gas in a plasma state through this mask layer, the areas of the workpiece 11 and the laminate 13 that have been subjected to laser processing are partially etched.

[0076] There are no limitations on the material or method of forming the mask layer. For example, the mask layer can be formed from a resist made of a photosensitive resin. Furthermore, the protective film 27 (see FIG. 4(B)) can be used as the mask layer without being removed after the groove formation step. In this case, the protective film 27 is removed after the plasma etching step.

[0077] The plasma etching step may be omitted if the workpiece 11 or the laminate 13 is processed under processing conditions that make it difficult for processing distortion or debris to occur in the processing groove formation step, if debris is reliably removed by cleaning after the processing groove formation step, or if processing distortion or debris remaining in the workpiece 11 or the laminate 13 does not affect the operation or quality of the device chip.

[0078] Next, a support member is fixed to the front surface 11a side of the workpiece 11 (support member fixing step). Fig. 6(A) is a perspective view showing the workpiece 11 in the support member fixing step.

[0079] The support member 31 is a member that supports the workpiece 11 in the back grinding step (see FIG. 7(A)) described later. For example, a disk-shaped substrate (support substrate) made of glass, silicon, resin, ceramics, or the like is used as the support member 31. The support member 31 is bonded to the front surface 11a side (the laminate 13 side) of the workpiece 11 via an adhesive layer 33. The adhesive layer 33 may be made of an epoxy-based, acrylic-based, or rubber-based adhesive, an ultraviolet-curing resin, or the like.

[0080] 6(B) is a cross-sectional view showing a portion of the workpiece 11 after the support member fixing step. When the support member 31 is fixed to the workpiece 11, the workpiece 11 is supported by the support member 31. Note that a flexible sheet-like member can also be used as the support member 31. For example, a support tape having the same material and structure as the tape 25 (see FIG. 2) can be attached to the workpiece 11 as the support member 31.

[0081] Next, the back surface 11b side of the workpiece 11 is ground (back surface grinding step). Fig. 7(A) is a perspective view showing the workpiece 11 in the back surface grinding step. In the back surface grinding step, the workpiece 11 is ground by a grinding apparatus 100.

[0082] The grinding apparatus 100 includes a chuck table (holding table) 102 that holds the workpiece 11. The upper surface of the chuck table 102 is a circular, flat surface that is roughly parallel to the horizontal direction, and constitutes a holding surface 102a that holds the workpiece 11. The holding surface 102a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like that are formed inside the chuck table 102.

[0083] A moving mechanism (not shown) that moves the chuck table 102 in the horizontal direction is connected to the chuck table 102. In addition, a rotation drive source such as a motor that rotates the chuck table 102 around a rotation axis that is approximately parallel to the vertical direction is connected to the chuck table 102.

[0084] A grinding unit 104 is provided above the chuck table 102. The grinding unit 104 includes a cylindrical spindle 106 arranged in the vertical direction. A disk-shaped mount 108 made of metal or the like is fixed to the tip end (lower end) of the spindle 106. A rotation drive source (not shown), such as a motor, that rotates the spindle 106 is connected to the base end (upper end) of the spindle 106.

[0085] An annular grinding wheel 110 is attached to the mount 108. The grinding wheel 110 is a processing tool that grinds the workpiece 11, and is fixed to the underside of the mount 108 with fasteners such as bolts. The grinding wheel 110 rotates around a rotation axis that is approximately parallel to the vertical direction by power transmitted from a rotation drive source via the spindle 106 and the mount 108.

[0086] The grinding wheel 110 includes an annular base 112. The base 112 is made of a metal such as aluminum or stainless steel, and is formed to have approximately the same diameter as the mount 108. A plurality of grinding stones 114 are fixed to the underside of the base 112. For example, the plurality of grinding stones 114 are formed in a rectangular parallelepiped shape, and are arranged in a ring shape at approximately equal intervals along the circumferential direction of the base 112.

[0087] The grinding wheel 114 includes abrasive grains made of diamond, cBN (cubic boron nitride), or the like, and a binder (bond material) that secures the abrasive grains. Bond materials such as metal bonds, resin bonds, and vitrified bonds are used. However, there are no limitations on the material, shape, structure, size, etc., of the grinding wheel 114. The number of grinding wheels 114 can also be set arbitrarily.

[0088] In the backside grinding step, first, the workpiece 11 is held by the chuck table 102. Specifically, the workpiece 11 is placed on the chuck table 102 so that the front surface 11a side (the laminate 13 side, the support member 31 side) faces the holding surface 102a and the back surface 11b side is exposed upward. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 102a, the workpiece 11 is suction-held by the chuck table 102 via the support member 31.

[0089] Next, the chuck table 102 is moved, and the workpiece 11 is placed below the grinding unit 104. At this time, the positional relationship between the chuck table 102 and the grinding unit 104 is adjusted so that the rotation axis of the chuck table 102 (the center of the workpiece 11) and the orbit (rotation path) of the grinding wheel 114 overlap.

[0090] Then, while rotating the chuck table 102 and the grinding wheel 110, the grinding wheel 110 is lowered and the rotating grinding stones 114 are brought into contact with the back surface 11b of the workpiece 11. As a result, the back surface 11b of the workpiece 11 is ground, and the workpiece 11 is thinned.

[0091] 7(B) is a cross-sectional view showing a part of the workpiece 11 after the backside grinding step. Grinding of the workpiece 11 continues until the electrode 21 embedded in the workpiece 11 is exposed on the backside 11b of the workpiece 11. As a result, a through electrode that penetrates the workpiece 11 in the thickness direction is formed.

[0092] Note that the electrode 21 may be exposed on the back surface 11b of the workpiece 11 by performing another process after grinding the workpiece 11. For example, in the back surface grinding step, the workpiece 11 may be ground until just before the electrode 21 is exposed on the back surface 11b of the workpiece 11, and then the back surface 11b of the workpiece 11 may be subjected to a process such as dry etching, wet etching, or polishing to expose the electrode 21 on the back surface 11b of the workpiece 11. In this case, it is possible to prevent the grinding wheel 114 from coming into contact with the electrode 21 and causing the metal contained in the electrode 21 to scatter.

[0093] Next, a pattern is formed on the rear surface 11b of the workpiece 11 (rear surface pattern forming step). Figure 8 is a cross-sectional view showing a part of the workpiece 11 on which the pattern layer 35 has been formed.

[0094] The pattern layer 35 is a functional layer having a predetermined function similar to the laminate 13, and includes an insulating film, a conductive film, or a pattern of a laminate thereof. For example, the pattern layer 35 includes connection electrodes connected to the electrodes 21, an insulating layer that insulates the connection electrodes from each other, wiring, terminals, elements, etc. connected to the connection electrodes.

[0095] The pattern layer 35 is designed appropriately depending on the structure and function of the device chip obtained by dividing the workpiece 11, the structure and function of the device chip to be mounted, etc. Furthermore, if the formation of the pattern layer 35 is not required, the back surface pattern formation step can be omitted.

[0096] Next, the support member 31 is removed from the front surface 11a side of the workpiece 11 (support member removing step). Fig. 9 is a perspective view showing the workpiece 11 in the support member removing step.

[0097] In the support member removal step, first, tape 39 is adhered to the back surface 11b of workpiece 11. Specifically, with workpiece 11 placed inside opening 37a of annular frame 37, the central portion of tape 39 is adhered to the back surface 11b of workpiece 11, and the outer periphery of tape 39 is adhered to frame 37. In this way, workpiece 11 is supported by frame 37 via tape 39.

[0098] The configuration, material, etc. of frame 37 and tape 39 are the same as those of frame 23 and tape 25 (see FIG. 2), respectively. As will be described later, tape 39 may be an extensible sheet (expandable sheet).

[0099] Next, while holding the workpiece 11, the support member 31 is moved in a direction away from the workpiece 11, thereby peeling the support member 31 off from the workpiece 11. As a result, the support member 31 is removed from the workpiece 11.

[0100] When peeling off the support member 31, the adhesive layer 33 may be subjected to a predetermined treatment in advance to reduce the adhesive strength of the adhesive layer 33. This makes it easier to separate the support member 31 from the workpiece 11. For example, if the adhesive layer 33 is made of an ultraviolet-curing resin, the adhesive layer 33 is irradiated with ultraviolet light and then the support member 31 is removed. Furthermore, if the adhesive layer 33 remains on the workpiece 11 after removing the support member 31, the workpiece 11 may be subjected to a cleaning treatment.

[0101] Next, a resin layer is formed on the surface 11a side of the workpiece 11 (resin layer forming step). Fig. 10 is a perspective view showing the workpiece 11 in the resin layer forming step.

[0102] The resin layer 41 corresponds to an underfill material used when mounting device chips obtained by dividing the workpiece 11. For example, an NCF (Non Conductive Film) is used as the resin layer 41. The NCF is a film obtained by forming a resin into a sheet, and has adhesive and insulating properties.

[0103] The resin layer 41 (NCF) is formed to have approximately the same diameter as the workpiece 11, and is attached to the surface 11a side of the workpiece 11 so as to cover the entire laminate 13. As a result, the resin layer 41 is formed on the surface 11a side of the workpiece 11, and the device 17 and the connection electrodes 19 are sealed by the resin layer 41.

[0104] However, there is no limitation on the type of resin layer 41. For example, the resin layer 41 may be formed by applying NCP (Non Conductive Paste) to the surface 11a side of the workpiece 11. There is also no limitation on the material of the resin layer 41. For example, the resin layer 41 may contain, as a main component, an epoxy resin, an acrylic resin, a urethane resin, a silicone resin, a polyimide resin, or the like. Furthermore, the resin layer 41 may contain various additives such as an oxidizing agent and a filler.

[0105] Through the above steps, a wafer (grooved wafer) is obtained, which includes the workpiece 11, the laminate 13, and the resin layer 41, and in which grooves 29 for dividing the laminate 13 are provided along the intended dividing lines 15. That is, the above steps correspond to a method for manufacturing a grooved wafer.

[0106] Next, the workpiece 11 and the resin layer 41 are divided along the planned dividing lines 15 (dividing step). Fig. 11(A) is a cross-sectional view showing the workpiece 11 in the dividing step. For example, in the dividing step, the workpiece 11 and the resin layer 41 are cut by a cutting device 120.

[0107] The cutting device 120 includes a chuck table (holding table) 122 that holds the workpiece 11. The upper surface of the chuck table 122 is a circular flat surface that is roughly parallel to the horizontal direction (XY plane direction), and constitutes a holding surface 122a that holds the workpiece 11. The holding surface 122a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like that are formed inside the chuck table 122.

[0108] A ball screw type moving mechanism (not shown) that moves the chuck table 122 along the X-axis direction is connected to the chuck table 122. A rotation drive source (not shown) such as a motor that rotates the chuck table 122 around a rotation axis that is approximately perpendicular to the holding surface 122a is also connected to the chuck table 122. Furthermore, a plurality of clamps 124 that grip and fix the frame 37 are provided around the periphery of the chuck table 122.

[0109] A cutting unit 126 is provided above the chuck table 122. The cutting unit 126 includes a cylindrical housing 128. The housing 128 accommodates a columnar spindle 130 arranged along the Y-axis direction. A tip end (one end) of the spindle 130 is exposed to the outside of the housing 128, and a base end (other end) of the spindle 130 is connected to a rotation drive source such as a motor.

[0110] An annular cutting blade 132 is attached to the tip of the spindle 130. The cutting blade 132 rotates around a rotation axis that is roughly parallel to the Y-axis direction by power transmitted from a rotary drive source via the spindle.

[0111] The cutting blade 132 may be, for example, a hub-type cutting blade (hub blade). A hub blade is formed by integrating an annular base made of metal or the like with an annular cutting edge formed along the outer periphery of the base. The cutting edge of the hub blade is formed by an electroformed grinding stone containing abrasive grains made of diamond or the like and a binder such as a nickel-plated layer that secures the abrasive grains in place. However, a washer-type cutting blade (washer blade) may also be used as the cutting blade 132. A washer blade is formed only by an annular cutting edge that contains abrasive grains and a binder made of metal, ceramics, resin, or the like that secures the abrasive grains in place.

[0112] A ball screw type movement mechanism (not shown) is connected to the cutting unit 126. This movement mechanism moves the cutting unit 126 along the Y-axis direction and raises and lowers it along the Z-axis direction.

[0113] In the dividing step, first, the workpiece 11 is held by the chuck table 122. Specifically, the workpiece 11 is placed on the chuck table 122 so that the front surface 11a side (the laminate 13 side, the resin layer 41 side) faces upward and the back surface 11b side (the tape 25 side) faces the holding surface 122a. In addition, the frame 37 is fixed by a plurality of clamps 124. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 122a, the workpiece 11 is held by the chuck table 122 via the tape 39.

[0114] Next, the chuck table 122 is rotated to align the length direction of the predetermined dividing line 15 with the processing feed direction (X-axis direction). Furthermore, the position of the cutting unit 126 in the indexing feed direction (Y-axis direction) is adjusted so that the cutting blade 132 is positioned on an extension of the predetermined dividing line 15. Furthermore, the height of the cutting unit 126 is adjusted so that the lower end of the cutting blade 132 is positioned below the upper surface of the tape 39. The difference in height between the upper surface of the resin layer 41 and the lower end of the cutting blade 132 at this time corresponds to the cutting depth of the cutting blade 132.

[0115] Then, while rotating the cutting blade 132, the chuck table 122 is moved along the X-axis direction. As a result, the chuck table 122 and the cutting blade 132 move relatively along the X-axis direction (processing feed), and the cutting blade 132 cuts into the workpiece 11, the pattern layer 35, and the resin layer 41 along the planned dividing lines 15. As a result, the workpiece 11, the pattern layer 35, and the resin layer 41 are divided along the planned dividing lines 15. Thereafter, the same procedure is repeated until the workpiece 11, the pattern layer 35, and the resin layer 41 are cut along all of the planned dividing lines 15.

[0116] 11(B) is a cross-sectional view showing a part of the workpiece 11 in which kerfs (cut edges) 43 are formed inside the machined groove 29. After cutting, the workpiece 11, pattern layer 35, and resin layer 41 have kerfs 43 formed in a grid pattern along the planned dividing lines 15, extending from the upper surface of the resin layer 41 to the lower surface of the pattern layer 35. As a result, a plurality of device chips 45 are manufactured, each including a device 17 and individual pieces of the pattern layer 35 and the resin layer 41.

[0117] In the dividing step, the positional relationship between the chuck table 122 and the cutting blade 132 is adjusted so that the cutting blade 132 cuts into the inside of the groove 29 (between both ends in the width direction of the groove 29) corresponding to the area from which the laminate 13 has been removed. Therefore, the cutting blade 132 cuts the workpiece 11, etc., without coming into contact with the laminate 13. This makes it possible to prevent the rotating cutting blade from coming into contact with the laminate 13 and causing film peeling in the laminate 13, and prevents damage to the device 17, peeling of the resin layer 41, etc.

[0118] 11(C) is a cross-sectional view showing a part of the workpiece 11 in which a kerf 43 is formed between a pair of grooves 29. When a pair of grooves 29 is formed in the workpiece 11 and the laminate 13, the positional relationship between the chuck table 122 and the cutting blade 132 is adjusted so that the cutting blade 132 cuts between the pair of grooves 29. This makes it possible to prevent film peeling of the laminate 13 from spreading to the region corresponding to the device 17.

[0119] Pieces of the resin layer 41 are attached to the device chips 45 obtained by dividing the workpiece 11, etc. The device chips 45 are then mounted on a mounting substrate or other device chips via the pieces of the resin layer 41. That is, the pieces of the resin layer 41 function as an underfill material.

[0120] The workpiece 11, the pattern layer 35, and the resin layer 41 may be cut simultaneously with the other layers, or may be cut separately. For example, the resin layer 41 may be cut with a first cutting blade, and then the workpiece 11 and the pattern layer 35 may be cut with a second cutting blade. In this case, the first cutting blade and the second cutting blade may be the same cutting blade or different cutting blades.

[0121] If the resin layer 41 is formed before the grooves 29 are formed, and the laser beam 30 (see FIG. 4A) for forming the grooves 29 is irradiated onto the laminate 13 through the resin layer 41, the resin layer 41 may be altered and hardened due to heat and debris generated by the irradiation of the laser beam 30, causing the resin layer 41 to lose its flexibility. In this case, the individual pieces of the resin layer 41 may be less likely to deform when the device chip 45 is mounted, and there is a risk that the connection between the connection electrodes 19 of the device chip 45 and the electrodes on the mounting surface may not be possible or may be incomplete.

[0122] However, in this embodiment, the step of forming the resin layer 41 (see FIG. 10) is carried out after the step of forming the groove 29 by irradiating the laser beam 30 (see FIG. 4(A)). This makes it possible to avoid alteration of the resin layer 41 due to the irradiation of the laser beam and to prevent bonding defects of the device chip 45.

[0123] Although the above description has been given of an embodiment in which the workpiece 11 or the like is cut and divided by the cutting blade 132, the dividing method is not limited to cutting. For example, if the pattern layer 35 is not formed on the rear surface 11b of the workpiece 11, the workpiece 11 or the like can also be divided using cutting and grinding.

[0124] Specifically, instead of forming the kerfs 43, first, the workpiece 11 and the resin layer 41 are cut with the cutting blade 132 to form cut grooves along the planned dividing lines 15. At this time, the cutting depth of the cutting blade 132 is adjusted so that the lower end of the cutting blade 132 is positioned below the front surface 11a of the workpiece 11 and above the back surface 11b. As a result, cut grooves that divide the resin layer 41 and reach the inside of the workpiece 11 are formed along each planned dividing line 15.

[0125] Next, the back surface 11b side of the workpiece 11 is ground to thin it. For example, a grinding device 100 (see FIG. 7(A)) is used to grind the workpiece 11. When the workpiece 11 is ground until the cut grooves are exposed on the back surface 11b side of the workpiece 11, the workpiece 11 is divided into a plurality of device chips 45. As a result, device chips 45 to which individual pieces of the resin layer 41 are attached are manufactured.

[0126] The above-mentioned cutting grooves can also be formed before the resin layer 41 is formed. Specifically, first, the workpiece 11 (see FIG. 4(B)) on which the cutting grooves 29 have been formed is subjected to the above-mentioned cutting process, and cutting grooves reaching the inside of the workpiece 11 are formed along each of the planned division lines 15. Next, the resin layer 41 is formed on the front surface 11a side of the workpiece 11 (see FIG. 10). Thereafter, the workpiece 11 is ground until the cutting grooves are exposed on the back surface 11b side of the workpiece 11, and the workpiece 11 is divided into a plurality of device chips 45.

[0127] Next, the resin layer 41 is divided along the planned division lines 15. There is no limitation on the method for dividing the resin layer 41, and the resin layer 41 can be divided, for example, by cutting using a cutting blade or ablation processing using laser beam irradiation. Alternatively, the resin layer 41 may be divided by applying an external force caused by expanding an expand sheet, as described below. As a result, a device chip 45 is manufactured in which individual pieces of the resin layer 41 are attached.

[0128] Also, for example, in the dividing step, the workpiece 11, etc. may be divided by forming a dividing starting point (a trigger for dividing) in the workpiece 11 and then applying an external force to the workpiece 11. Below, a specific example of a method for dividing the workpiece 11, etc. by forming a dividing starting point and applying an external force will be described.

[0129] First, before the dividing step, an extensible sheet (expandable sheet) is attached to the workpiece 11 (expandable sheet attachment step). For example, an expandable sheet that can be expanded by applying an external force is used as tape 39 (see FIG. 9). In this case, the workpiece 11 is supported by a frame 37 via the expandable sheet. It is preferable to use a resin such as polyolefin or polyvinyl chloride, which has high extensibility, as the base material of the expandable sheet.

[0130] However, the expandable sheet may be a sheet separate from the tape 39. For example, the tape 39 may be peeled off from the workpiece 11 before the dividing step, and a separate expandable sheet may be attached to the workpiece 11.

[0131] Next, a dividing step is carried out. In the dividing step, a laser beam is first irradiated onto the workpiece 11 to form a modified layer on the workpiece 11 along the intended dividing lines 15 (modified layer forming step). Fig. 12(A) is a cross-sectional view showing the workpiece 11 in the modified layer forming step.

[0132] In the modified layer forming step, laser processing is performed on the workpiece 11 by a laser processing device 140. The configuration of the laser processing device 140 is similar to that of the laser processing device 20 (see FIG. 4(A)). Specifically, the laser processing device 140 includes a chuck table (holding table) 142, a plurality of clamps 144, and a laser irradiation unit 146. The chuck table 142 includes a holding surface 142a that holds the workpiece 11, and the laser irradiation unit 146 includes a laser oscillator (not shown) and a laser processing head 148. Note that the laser processing device 20 (see FIG. 4(A)) can also be used in the modified layer forming step.

[0133] In the modified layer forming step, first, the workpiece 11 is held by the chuck table 142. Specifically, the workpiece 11 is placed on the chuck table 142 so that the front surface 11a side (the laminate 13 side, the resin layer 41 side) faces the holding surface 142a and the back surface 11b side (the tape 39 side) faces upward. In addition, the frame 37 is fixed by a plurality of clamps 144. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 142a, the workpiece 11 is suction-held by the chuck table 142 via the resin layer 41.

[0134] The resin layer 41 may be provided with a protective member that protects the surface of the resin layer 41. In this case, the workpiece 11 is held by the chuck table 142 via the resin layer 41 and the protective member. This makes it possible to prevent contact between the resin layer 41 and the holding surface 142a of the chuck table 142. Examples of materials for the protective member are the same as those for the support member 31 (see FIG. 9).

[0135] Next, the chuck table 142 is rotated to align the length direction of the predetermined dividing line 15 with the processing feed direction (X-axis direction). Also, the position of the chuck table 142 in the indexing feed direction (Y-axis direction) is adjusted so that the position in the Y-axis direction of the area irradiated with the laser beam 150 coincides with the position in the Y-axis direction of the inner areas at both ends of the dividing line 15 in the width direction (for example, the center in the width direction of the processed groove 29). Furthermore, the position of the laser processing head 148 and the arrangement of the optical system are adjusted so that the focal point of the laser beam 150 is positioned at the same height as the interior of the workpiece 11.

[0136] Then, while irradiating the laser beam 150 from the laser processing head 148, the chuck table 142 is moved along the processing feed direction (X-axis direction). As a result, the chuck table 142 and the laser beam 150 move relatively along the processing feed direction (X-axis direction) at a predetermined speed (processing feed speed). As a result, the laser beam 150 is irradiated from the back surface 11b side of the workpiece 11 along the planned dividing line 15, with the focal point positioned inside the workpiece 11.

[0137] The irradiation conditions of the laser beam 150 are set so that the area of the workpiece 11 irradiated with the laser beam 150 is modified and altered by multiphoton absorption. Specifically, the wavelength of the laser beam 150 is set so that at least a portion of the laser beam 150 passes through the workpiece 11. In other words, the laser beam 150 is a laser beam with a wavelength that is transparent to the workpiece 11. The irradiation conditions of the other laser beams 150 are also set so that the workpiece 11 is appropriately modified. For example, when the workpiece 11 is a silicon wafer, the irradiation conditions of the laser beam 150 are set as follows: Wavelength: 1064nm Average power: 1W Repetition frequency: 100kHz Processing feed rate: 800mm / s

[0138] When the laser beam 150 is irradiated onto the workpiece 11, the inside of the workpiece 11 is modified and altered by multiphoton absorption, and modified layers (degraded layers) 47 are formed inside the workpiece 11 along the planned dividing lines 15 and the processed grooves 29. Thereafter, by repeating the same procedure, the laser beam 150 is irradiated along the other planned dividing lines 15 and the processed grooves 29. As a result, a lattice-shaped modified layer 47 is formed inside the workpiece 11.

[0139] Note that the modified layer 47 may be formed in multiple layers in the thickness direction of the workpiece 11. For example, if the workpiece 11 is a silicon wafer or the like having a thickness of 200 μm or more, forming two or more modified layers 47 makes it easier to properly divide the workpiece 11. When forming multiple modified layers 47, the laser beam 150 is irradiated multiple times along each of the planned division lines 15 while changing the focal point of the laser beam 150 in the thickness direction of the workpiece 11.

[0140] 12(B) is a cross-sectional view showing a part of the workpiece 11 after the modified layer forming step. The modified layer 47 is formed along the intended dividing lines 15 and the processed grooves 29 in the area inside the workpiece 11 where the laser beam 150 (see FIG. 12(A)) is focused or in the vicinity thereof. Furthermore, when the modified layer 47 is formed, cracks 49 occur in the modified layer 47 and propagate from the modified layer 47 toward the front surface 11a and the back surface 11b of the workpiece 11.

[0141] The region of the workpiece 11 where the modified layer 47 and the crack 49 are formed becomes more fragile than other regions of the workpiece 11. Therefore, when an external force is applied to the workpiece 11, the workpiece 11 is divided along the intended division line 15 and the processed groove 29, starting from the modified layer 47 and the crack 49. In other words, the modified layer 47 and the crack 49 function as division starting points.

[0142] However, depending on the irradiation conditions of the laser beam 150, the thickness of the workpiece 11, etc., the crack 49 may reach the front surface 11a and the back surface 11b of the workpiece 11. In this case, the workpiece 11 is divided along the intended dividing line 15 in the modified layer forming step.

[0143] Next, the tape 39 (expanding sheet) is expanded (expanding step). Figure 13(A) is a cross-sectional view showing the workpiece 11 in the expanding step.

[0144] In the expansion step, the tape 39 is expanded by being pulled radially outward, which applies an external force to the workpiece 11, the pattern layer 35, and the resin layer 41, causing the workpiece 11, the pattern layer 35, and the resin layer 41 to be divided along the planned dividing lines 15.

[0145] The tape 39 may be expanded manually by an operator or automatically using a dedicated expansion device. Fig. 13(A) shows an example in which the tape 39 is expanded by an expansion device 160.

[0146] The expansion device 160 has a drum 162 formed in a hollow cylindrical shape. At the upper end of the drum 162, a plurality of rollers 164 are arranged along the circumferential direction of the drum 162. In addition, a plurality of columnar support members 166 are arranged on the outside of the drum 162. At the lower end of each of the support members 166, an air cylinder (not shown) is connected which moves (raises and lowers) the support member 166 in the vertical direction.

[0147] An annular table 168 is fixed to the upper ends of the multiple support members 166. A circular opening is provided in the center of the table 168, penetrating the table 168 in the thickness direction. The diameter of the opening in the table 168 is larger than the diameter of the drum 162, so that the upper end of the drum 162 can be inserted into the opening in the table 168. Additionally, multiple clamps 170 that grip and secure the frame 37 are arranged on the outer periphery of the table 168.

[0148] When dividing the workpiece 11, first, the support member 166 is moved by an air cylinder (not shown) so that the upper ends of the rollers 164 and the upper surface of the table 168 are positioned at approximately the same height. Then, the frame 37 is placed on the table 168 and fixed with a plurality of clamps 170. At this time, the workpiece 11 is positioned so as to overlap the inner region of the drum 162.

[0149] Next, the support member 166 is lowered by an air cylinder (not shown), and the table 168 is pulled down. As a result, the tape 39 is pulled radially outward while being supported by the rollers 164. As a result, the tape 39 is expanded radially.

[0150] 13(B) is a cross-sectional view showing a portion of the workpiece 11 after the expansion step. When the tape 39 is expanded, an external force is applied to the workpiece 11 to which the tape 39 is attached. As a result, the modified layer 47 or the cracks 49 (see FIG. 12(B)) function as division starting points, and the workpiece 11 is divided along the planned division lines 15. In addition, the pattern layer 35 and the resin layer 41 formed on the workpiece 11 are also divided along the planned division lines 15 together with the workpiece 11.

[0151] The region of the laminate 13 that overlaps with the modified layer 47 is removed in the groove formation step (see FIGS. 4(A) and 4(B)). Therefore, when the workpiece 11 is divided, the phenomenon of peeling off of the thin films included in the laminate 13 due to the fracture of the laminate 13 is unlikely to occur, and damage to the device 17 is prevented.

[0152] When the workpiece 11 or the like is divided along the planned division lines 15, a plurality of device chips 45 are manufactured in which the devices 17 are sealed with individual pieces of the resin layer 41. Furthermore, the expansion of the tape 39 forms gaps between the device chips 45. The device chips 45 are then peeled off from the tape 39, picked up, and mounted on a mounting board or another device chip.

[0153] If the cracks 49 (see FIG. 12(B)) reach the front surface 11a and the back surface 11b of the workpiece 11 when the modified layer 47 is formed, the workpiece 11 is already divided along the planned division lines 15 before the expansion step is performed. In this case, the resin layer 41 is divided along the planned division lines 15 by the expansion of the tape 39, and gaps are formed between the device chips 45.

[0154] As described above, in the method for manufacturing a device chip according to this embodiment, before dividing the workpiece 11, the processing grooves 29 for dividing the laminate 13 are formed along the dividing lines 15. This prevents the laminate 13 from peeling when dividing the workpiece 11, and prevents damage to the device 17 and peeling of the resin layer 41.

[0155] Furthermore, in the method for manufacturing a device chip according to this embodiment, after the processing grooves 29 that divide the laminate 13 are formed along the intended dividing lines 15 by irradiation with the laser beam 30, a resin layer 41 is formed on the front surface 11a side of the workpiece 11. This makes it possible to avoid the resin layer 41 being altered by irradiation with the laser beam 30 for forming the processing grooves 29, and prevents bonding defects when mounting a device chip 45 via an individual piece of the resin layer 41.

[0156] Furthermore, in the device chip manufacturing method according to this embodiment, the processing groove 29 is formed by irradiating the workpiece 11 with the laser beam 30 before the rigidity of the workpiece 11 is reduced by grinding and thinning the workpiece 11. As a result, deformation (deflection) and breakage of the workpiece 11 are less likely to occur when performing laser processing to form the processing groove 29, and handling of the workpiece 11 becomes easier.

[0157] The structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0158] 11 Workpiece 11a Surface (first side) 11b Back side (2nd side) 13 Laminate 15 Planned division line (street) 17 devices 19 Connection electrode (bump) 21 Electrodes (buried electrodes, through electrodes) 23 frames 23a opening 25 Tape 27 Protective film 29 Machining groove 31 Support member 33 Adhesive layer 35 pattern layers 37 frames 37a aperture 39 Tape 41 Resin layer 43 Calf (cut) 45 Device Chips 47 Modified layer (degenerated layer) 49 Crack 2 Spin coater 4 Spinner table (chuck table) 4a Holding surface 6 Clamp 8 Protective film supply unit 10 Protective film material 20 Laser processing equipment 22 Chuck table (holding table) 22a Holding surface 24 Clamp 26 Laser irradiation unit 28 Laser processing head 30 Laser Beam 40 Plasma processing equipment 42 Chambers 42a side wall 42b opening 42c bottom wall 42d upper wall Gate 44 46 Opening and closing unit 48 Piping 50 Decompression Unit 52 Table Base 52a Suction channel 52b Flow path 54 Holding part 56 Support part 58 Chuck table (holding table) 60 Main body 60a Suction path 62 electrodes 64 DC power supply 66 Suction pump 68 Circulation Unit 70 Gas supply unit 72 Supply pipe 72a Supply port 74a, 74b, 74c valves 76a, 76b, 76c Flow Controller 78a, 78b, 78c valves 80a, 80b, 80c gas supply source 82 electrode 84 High frequency power supply 86 Dispersion member 88 Piping 100 Grinding equipment 102 Chuck table (holding table) 102a Holding surface 104 Grinding Unit 106 Spindle 108 Mount 110 Grinding Wheel 112 Foundation 114 Grinding Wheel 120 Cutting equipment 122 Chuck table (holding table) 122a Holding surface 124 Clamp 126 Cutting Unit 128 Housing 130 Spindle 132 Cutting blade 140 Laser processing equipment 142 Chuck table (holding table) 142a Retaining surface 144 Clamp 146 Laser irradiation unit 148 Laser processing head 150 Laser Beam 160 Expansion Unit 162 Drums 164 Coro 166 Support member 168 tables 170 Clamp

Claims

1. A method for manufacturing device chips by dividing a workpiece having, on a front surface side, a laminate constituting devices provided in a plurality of regions partitioned by a plurality of intersecting planned division lines, the workpiece comprising: a groove forming step of irradiating a laser beam having a wavelength absorbable by the laminate from the front surface side of the workpiece along the planned dividing lines to form grooves that divide the laminate along the planned dividing lines; a resin layer forming step of forming a resin layer on the surface side of the workpiece after the processing groove forming step; a dividing step of dividing the workpiece and the resin layer along the planned dividing lines by processing the workpiece and the resin layer along the planned dividing lines after the resin layer forming step.

2. A method for manufacturing device chips by dividing a workpiece having, on a front surface side, a laminate constituting devices provided in a plurality of regions partitioned by a plurality of intersecting planned division lines, the workpiece comprising: a groove forming step of irradiating a laser beam having a wavelength absorbable by the laminate from the front surface side of the workpiece along the planned dividing lines to form grooves that divide the laminate along the planned dividing lines; a support member fixing step of fixing a support member to the front surface side of the workpiece after the processing groove forming step; a back grinding step of grinding a back surface side of the workpiece after the support member fixing step; a support member removing step of removing the support member from the front surface side of the workpiece after the back surface grinding step; a resin layer forming step of forming a resin layer on the surface side of the workpiece after the support member removing step; a dividing step of dividing the workpiece and the resin layer along the planned dividing lines after the resin layer forming step.

3. 3. The method for manufacturing a device chip according to claim 2, further comprising a backside pattern forming step of forming a pattern on the backside of the workpiece after the backside grinding step.

4. 4. The method for manufacturing a device chip according to claim 1, further comprising a protective film forming step of forming a protective film on the front surface side of the workpiece before the processing groove forming step.

5. 5. The method for manufacturing a device chip according to claim 1, further comprising a plasma etching step of supplying an etching gas in a plasma state from the surface side of the workpiece after the processing groove forming step, and removing processing strain or foreign matter remaining in the workpiece or the laminate.

6. 6. The method for manufacturing a device chip according to claim 1, wherein in the dividing step, the workpiece and the resin layer are cut along the planned dividing lines with a cutting blade.

7. The method further includes, before the dividing step, an expandable sheet attaching step of attaching an expandable sheet to the workpiece, The division step comprises: a modified layer forming step of forming a modified layer on the workpiece along the planned dividing line by irradiating the workpiece with a laser beam having a wavelength that is transparent to the workpiece and positioning a focal point of the laser beam inside the workpiece; 6. The method for manufacturing a device chip according to claim 1, further comprising, after the modified layer forming step, an expanding step of expanding the expand sheet.

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