Manufacturing method of chip

Abstract

To provide a manufacturing method of a chip, capable of preventing a part having a shape like a fang at an end part of a bottom of a processing groove when forming the processing groove by radiating a laser beam along a schedule division line of a substrate in which a film is provided on a front surface.SOLUTION: A manufacturing method of a chip comprises: a first processing groove formation step of forming a first processing groove having a first width in a direction of a width of a schedule division line by radiating a first laser beam along the schedule division line; a second processing groove formation step of forming a second processing groove having a second width that is different from the first width in a direction of the width of the schedule division line by radiating a second laser beam along the schedule division line after the first processing groove formation step; and a division step of forming a plurality of chips by dividing a substrate along a bottom of the processing groove.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a chip.

Background Art

[0002] In a method for manufacturing a device chip used in an electronic device or the like, for example, devices such as integrated circuits are formed in each of a plurality of regions partitioned by division planned lines set in a grid pattern on the surface of a substrate (wafer). Then, the substrate is cut along the division planned lines by a cutting device or the like and divided, whereby a plurality of device chips each having a device are manufactured.

[0003] By the way, for example, when a substrate provided with a film such as a low dielectric constant insulating film (Low-k film) is cut with a cutting blade, the film may peel off from the substrate due to contact between the film and the cutting blade. When the peeling of the film reaches the device, there is a problem of damaging the device.

[0004] In order to solve this problem, for example, in Patent Document 1, a technique has been proposed in which a plurality of processing grooves along the division planned lines are formed by irradiating the division planned lines with a laser beam. By cutting a cutting blade along the formed processing grooves, contact between the film and the cutting blade is avoided, and peeling of the film from the substrate is prevented.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the technology proposed in Patent Document 1, the depth of the end portion near the side wall at the bottom of the processing groove becomes deeper than the depth of other portions at the bottom of the processing groove, and a groove having a portion with a cross-sectional shape like a sharp tooth at the end may be formed. When such a groove is formed, there are problems such as a decrease in the fracture strength of the chip or the occurrence of cracks in the chip.

[0007] Therefore, an object of the present invention is to provide a method for manufacturing a chip that can prevent a portion having a tooth-like shape from being formed at the end of the bottom of a processing groove when a laser beam is irradiated along a planned division line of a substrate provided with a film on its surface to form the processing groove.

Means for Solving the Problems

[0008] According to one aspect of the present invention, there is provided a method for manufacturing a chip for manufacturing a plurality of chips by dividing a substrate provided with a film on its surface along a planned division line having a predetermined width, the method including: a processing groove forming step of forming a processing groove by removing a part of the film along the planned division line; and a dividing step of forming a plurality of chips by dividing the substrate along the bottom of the processing groove after the processing groove forming step. The processing groove forming step includes: a first processing groove forming step of forming a first processing groove having a first width in the width direction by irradiating a first laser beam along the planned division line; and a second processing groove forming step of forming a second processing groove having a second width different from the first width in the width direction by irradiating a second laser beam along the planned division line after the first processing groove forming step.

[0009] In one aspect of the present invention, the second width may be smaller than the first width. In this case, preferably, the second width is 30% or more and 80% or less of the first width.

[0010] Also, in one aspect of the present invention, the second width may be larger than the first width.

[0011] Preferably, the first beam width in the width direction of the first laser beam at the irradiation position irradiated on the film is different from the second beam width in the width direction of the second laser beam at the irradiation position irradiated on the film or the substrate.

Advantages of the Invention

[0012] In the method for manufacturing a chip according to one aspect of the present invention, when forming a processing groove in a division planned line of a substrate provided with a film on its surface by irradiating a laser beam along the division planned line, after forming a first processing groove having a first width, a second processing groove having a second width different from the first width is formed. Thus, by forming a processing groove including the first processing groove and the second processing groove having different widths, it is possible to prevent a tooth-like portion from being formed at the end of the bottom of the processing groove.

Brief Description of the Drawings

[0013]

Figure 1

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Figure 12

Mode for Carrying Out the Invention

[0014] Hereinafter, a method for manufacturing a chip according to an embodiment of the present invention will be described with reference to the accompanying drawings. First, a substrate and the like used in the method for manufacturing a chip according to the present embodiment will be described. FIG. 1 is a perspective view of a substrate 11 and the like, and FIG. 2 is a cross-sectional view of the substrate 11 and the like.

[0015] As shown in FIG. 1, the substrate 11 is, for example, a disk-shaped wafer made of a semiconductor material such as silicon. That is, the substrate 11 is configured in a substantially disk shape having a substantially circular first surface 11a and a substantially circular second surface 11b on the side opposite to the first surface 11a. A notch 11c for indicating the crystal orientation of the substrate 11 is formed in a part of the outer peripheral portion (peripheral portion) of the substrate 11.

[0016] The diameter of the substrate 11 (the width of the first surface 11a or the second surface 11b) is, for example, 100 mm or more and 450 mm or less, and typically 300 mm. The thickness of the substrate 11 is, for example, 100 μm or more and 2000 μm or less, and typically 775 μm. Note that the material, shape, diameter (width of the first surface 11a or the second surface 11b), and thickness of the substrate 11 are not limited to these. Further, an orientation flat may be formed on the substrate 11 instead of the notch 11c. Furthermore, the substrate 11 may not have the notch 11c or the orientation flat formed thereon.

[0017] As shown in FIG. 2, a film 13 is provided on the first surface 11a of the substrate 11. The film 13 is configured in a film shape having a substantially circular first surface 13a having substantially the same diameter (width) as the first surface 11a and the second surface 11b of the substrate 11, and a substantially circular second surface 13b on the side opposite to the first surface 13a. That is, the shape of the film 13 is also substantially disk-shaped.

[0018] The film 13 includes, for example, a plurality of films such as a metal film for wiring that constitutes the circuit of the device 17 described later, and a low dielectric constant insulating film (Low-k film) provided as an interlayer insulating film. The thickness of the film 13 is, for example, 1 μm or more and 50 μm or less, and typically 10 μm or more and 20 μm or less. Note that the film 13 may be composed of a single film instead of a plurality of films.

[0019] Each film constituting the film 13 is formed, for example, by methods such as CVD (Chemical Vapor Deposition), thermal oxidation, and coating. However, the shape, thickness, material, and formation method of the film 13 (and the films constituting it) are not limited to these, and are appropriately selected according to the performance required for the chip, etc.

[0020] As shown in FIGS. 1 and 2, a plurality of linear division planned lines 15 (streets) having a predetermined width are set in a grid pattern on the first surface 13a of the film 13. By these division planned lines 15, the first surface 13a of the film 13 is divided into a plurality of regions. Devices 17 such as integrated circuits are provided in the portions of the substrate 11 and the film 13 corresponding to each of the plurality of regions.

[0021] That is, each of the devices 17 arranged in each of the plurality of regions is configured to include the substrate 11 and the film 13. Then, by dividing the substrate 11 and the film 13 along the division planned lines 15, a plurality of chips each including the device 17 are manufactured. The width of the division planned lines 15 is, for example, 10 μm or more and 500 μm or less, and typically 60 μm or more and 80 μm or less.

[0022] As shown in FIG. 1, when processing the substrate 11 and the film 13, for the convenience of handling (transporting, holding, etc.) the substrate 11, the substrate 11 is supported by an annular frame 21 via a tape 19. The frame 21 is made of a metal such as SUS (stainless steel), for example, and a circular opening 21a penetrating the frame 21 in the thickness direction is provided at the central portion of the frame 21. Note that the diameter of the opening 21a is larger than the diameter of the substrate 11 (the width of the first surface 11a or the second surface 11b).

[0023] A circular tape 19 is fixed to the substrate 11 and the frame 21. For example, the tape 19 includes a film-like base material and an adhesive layer (paste layer) provided on the base material. The base material is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive, etc. Note that the adhesive layer may be made of an ultraviolet curable resin that cures by irradiation with ultraviolet rays.

[0024] With the substrate 11 disposed inside the opening 21a of the frame 21, the central portion of the tape 19 is attached to the second surface 11b side of the substrate 11, and the outer peripheral portion of the tape 19 is attached to the frame 21. Thereby, the substrate 11 is supported by the frame 21 via the tape 19, and a frame unit 23 in which the substrate 11, the frame 21, and the tape 19 are integrated is configured. However, the substrate 11 does not necessarily have to be supported by the frame 21.

[0025] Next, a method for manufacturing a chip using the above-described substrate 11 will be described. FIG. 3 is a flowchart of the method for manufacturing a chip according to the present embodiment. As shown in FIG. 3, the method for manufacturing a chip according to the present embodiment includes a first processing groove forming step S1, a second processing groove forming step S2, and a dividing step S3.

[0026] In the first processing groove forming step S1, a first processing groove is formed by irradiating the film 13 with a laser beam along the planned division line 15. FIG. 4 is a perspective view of the substrate 11, the laser processing apparatus 2, etc. in the first processing groove forming step S1. In FIG. 4, some components of the laser processing apparatus 2 are represented by functional blocks.

[0027] Also, the first direction (the direction along the X axis, the processing feed direction), the second direction (the direction along the Y axis, the indexing feed direction), and the third direction (the direction along the Z axis, the vertical direction) used in the following descriptions of the first processing groove forming step S1 and the second processing groove forming step S2 are perpendicular to each other.

[0028] As shown in FIG. 4, the laser processing apparatus 2 has a holding unit 4 for holding the frame unit 23. The holding unit 4 includes a chuck table (not shown). The chuck table includes, for example, a disk-shaped frame body (not shown) formed of a metal typified by stainless steel. On the upper surface side of the frame body, a recess with an upper end opening in a circular shape is formed. A disk-shaped holding plate (not shown) that matches the shape of the recess is fitted into the recess. Note that the width (diameter) of the frame body of the chuck table is slightly smaller than the width (diameter) of the opening 21a of the frame 21.

[0029] The holding plate is configured in a substantially disk shape having a substantially circular first surface (not shown) and a substantially circular second surface (not shown) on the side opposite to the first surface. This holding plate is configured in a porous plate shape. Specifically, the holding plate is configured in a porous shape using ceramics such as alumina (Al2O3) or silica (SiO2), and has a plurality of pores connected to each other so that air can flow between the first surface and the second surface.

[0030] Inside the frame body, a flow path (not shown) with one end connected to the second surface side of the holding plate is provided. The other end of the flow path is connected to a suction source (not shown) via piping or the like. By operating the suction source with the frame unit 23 (tape 19) in contact with the first surface of the holding plate, the negative pressure generated from the suction source acts on the first surface via the piping, the flow path of the frame body, and the holes of the holding plate, and a part of the frame unit 23 is sucked to the first surface. That is, a part of the frame unit 23 is sucked and held by the chuck table of the holding unit 4.

[0031] Around the chuck table of the holding unit 4, four clamps (not shown) for fixing the frame 21 constituting the frame unit 23 are provided. That is, the holding unit 4 includes four clamps. Further, the holding unit 4 includes a rotational drive source (not shown) such as a motor connected to the chuck table. The chuck table of the holding unit 4 obtains a rotational driving force from the rotational drive source and rotates around a rotation axis substantially perpendicular to the first surface of the chuck table.

[0032] Further, the holding unit 4 is supported by a ball screw type holding unit moving mechanism (not shown) having a ball screw for converting the rotational driving force of a motor or the like into a linear driving force. The holding unit 4 moves along a first direction (a direction along the X axis in FIG. 4) and a second direction (a direction along the Y axis in FIG. 4) substantially parallel to the first surface of the chuck table by the linear driving force of this holding unit moving mechanism.

[0033] The laser processing apparatus 2 has a laser irradiation unit 6. The laser irradiation unit 6 includes a laser oscillator (not shown) that generates a laser beam by laser oscillation. The laser oscillator typically includes a laser medium such as Nd:YAG suitable for laser oscillation and generates a pulsed laser beam having a wavelength absorbed by the film 13.

[0034] The laser irradiation unit 6 includes an irradiation head 8 that is provided on the downstream side of the laser oscillator along the traveling direction of the laser beam and stores optical elements such as a condenser (condensing lens, not shown) that condenses the laser beam. The laser beam condensed through the condenser in the irradiation head 8 is radiated from the irradiation head 8 toward the first surface (lower side) of the chuck table of the holding unit 4. Thereby, the film 13 of the frame unit 23 held by the chuck table of the holding unit 4 is irradiated with the laser beam.

[0035] A camera 10 is provided in a region adjacent to the irradiation head 8 in the direction along the X axis. The camera 10 is configured to be able to image a region above the holding unit 4. For example, a region including a portion of the film 13 held by the holding unit 4 that is irradiated with the laser beam is imaged by this camera 10.

[0036] For example, the irradiation head 8 and the camera 10 are supported by a ball screw type laser irradiation unit moving mechanism (not shown) including a ball screw for converting a rotational driving force of a motor or the like into a linear driving force. By this laser irradiation unit moving mechanism, the positions of the irradiation head 8 and the camera 10 in the third direction (the direction along the Z axis in FIG. 4) can be adjusted.

[0037] The laser processing apparatus 2 has one or a plurality of transfer mechanisms (not shown) that can transfer the above-described frame unit 23 to the holding unit 4 or the like. The transfer mechanism is, for example, a robot arm. The frame unit 23 is carried into the chuck table of the holding unit 4 by this transfer mechanism so that the first surface 13a side of the film 13 is exposed. Further, the frame unit 23 is carried out of the holding unit 4 to the outside of the holding unit 4 by the transfer mechanism.

[0038] The controller 12 is connected to various components of the above-described laser processing apparatus 2. The operations of the respective components of the laser processing apparatus 2 are controlled by this controller 12. The controller 12 is constituted by a computer including, for example, a processing device 14 such as a CPU (Central Processing Unit), and a storage device 16 that is a main storage device such as a DRAM (Dynamic Random Access Memory) and / or an auxiliary storage device such as a hard disk drive or a flash memory.

[0039] The functions of the controller 12 are realized by the operation of the processing device 14 in accordance with a program (software) stored in the storage device 16. However, the controller 12 may be realized only by hardware. The more specific functions of this controller 12 will be described in the specific explanations of the following respective steps.

[0040] In the first processing groove formation step S1, under the control of the controller 12, the laser irradiation unit 6 irradiates the film 13 with a laser beam (first laser beam) along the division planned line 15. First, the frame unit 23 is held by the holding unit 4.

[0041] Specifically, the frame unit 23 is carried in from the outside of the holding unit 4 by the above-described transport mechanism, and a portion corresponding to the substrate 11 of the frame unit 23 is placed on the first surface of the holding plate of the chuck table. As described above, in the present embodiment, the substrate 11 is placed on the first surface of the holding plate of the chuck table via the tape 19 so that the first surface 13a of the film 13 is exposed upward.

[0042] Thereafter, when a negative pressure of a suction source is applied to the first surface under the control of the controller 12, a portion corresponding to the substrate 11 of the frame unit 23 is sucked by the chuck table. That is, the frame unit 23 is held by the holding unit 4. Note that the substrate 11 may be manually placed on the chuck table of the holding unit 4 by an operator or the like.

[0043] Next, the positional relationship between the irradiation head 8 of the laser processing apparatus 2 and the frame unit 23 held by the holding unit 4 is adjusted in the first direction (the direction along the X-axis). Specifically, the rotation drive source rotates the holding unit 4 so that any one of the plurality of planned division lines 15 provided on the first surface 13a of the film 13 (the first planned division line 15 to be processed first) is parallel to the first direction (the direction along the X-axis).

[0044] Also, the holding unit moving mechanism adjusts the positions of the holding unit 4 in the first direction (the direction along the X-axis) and the second direction (the direction along the Y-axis) so that a part of the optical path of the laser beam (the first laser beam) emitted from the irradiation head 8 overlaps with the extension line of the first planned division line 15 to be processed first.

[0045] Thereafter, for example, while the laser oscillator generates a laser beam having a wavelength absorbed by the film 13, the holding unit moving mechanism moves the holding unit 4 in the first direction (the direction along the X-axis). Note that the position of the condensing point of the laser beam in the third direction (the position of the condensing point in the direction along the Z-axis of the condensing point, the height of the condensing point) is appropriately adjusted by the laser irradiation unit moving mechanism and the optical element included in the irradiation head 8 so that a first processing groove 25 having an appropriate shape is formed.

[0046] FIG. 5 is a top view of the film 13 and the like in the first processing groove forming step S1, and FIG. 6 is a cross-sectional view of the substrate 11, the film 13, and the like in the first processing groove forming step S1. As shown in FIG. 5, in the present embodiment, a laser beam (the first laser beam) 40 having a rectangular shape of the beam spot 18 on the first surface 13a of the film 13 is irradiated onto the film 13.

[0047] Here, the width in the width direction of the planned division line 15 of the laser beam 40 at the irradiation position irradiated onto the film 13 (the first beam width, the length of the long side of the beam spot 18) is a, which is smaller than the width of the planned division line 15. This a is typically set to be 15 μm smaller than the width of the planned division line 15.

[0048] Further, the profile of the laser beam 40 (spatial distribution of the intensity of the laser beam) is a top-hat type in which the uniformity of the intensity of the laser beam is high over a wider range compared to the Gaussian type. Note that the shape, width a, and intensity distribution of the beam spot 18 can be adjusted by a beam shaper, a beam expander, or the like.

[0049] As shown in FIGS. 5 and 6, by scanning such a laser beam 40 on the planned division line 15, a region from the first surface 13a of the film 13 to a predetermined depth is removed along the planned division line 15, and the first processing groove 25 is formed. The width of the first processing groove 25 is substantially the same width (first width) a as the width of the beam spot 18.

[0050] Also, the depth b of the first processing groove 25 is adjusted to be smaller than the thickness of the film 13. That is, conditions such as the intensity of the laser beam 40 are set so that the bottom of the first processing groove 25 does not reach the first surface 11a of the substrate 11.

[0051] After the laser beam 40 is irradiated along the first planned division line 15, for example, the holding unit moving mechanism moves the holding unit 4 in the direction along the Y axis, so that a part of the optical path of the laser beam 40 is overlapped with the extension line of the adjacent planned division line 15. Then, by repeating the same operation, the laser beam 40 is irradiated along the adjacent planned division line 15, and a similar first processing groove 25 is also formed in the adjacent planned division line 15.

[0052] Furthermore, the same procedure is repeated for the third and subsequent planned division lines 15, and the first processing grooves 25 are formed in all the planned division lines 15 (a total of 11 planned division lines 15 in FIG. 4) along the same direction as the first planned division line 15.

[0053] Next, along the planned division line 15 that intersects the planned division line 15 where the first processing groove 25 was formed in the above-described procedure, the first processing groove 25 is formed. Specifically, the rotation drive source rotates the holding unit 4 by 90 degrees. Also, the holding unit moving mechanism adjusts the positions of the holding unit 4 in the first direction (the direction along the X-axis) and the second direction (the direction along the Y-axis) so that a part of the optical path of the laser beam 40 emitted from the irradiation head 8 overlaps with the extension line of the planned division line 15 to be processed next.

[0054] Then, in the same procedure as when processing the first planned division line 15 and the like described above, the first processing groove 25 is formed in this planned division line 15. When the first processing groove 25 is formed in all the planned division lines 15 (a total of 11 planned division lines 15 in FIG. 4) along the direction intersecting the first planned division line 15 described above, the first processing groove forming step S1 ends.

[0055] Here, for example, the wavelength of the laser beam 40 is set to be 266 nm or more and 1064 nm or less, typically 355 nm, the repetition frequency is set to be 50 kHz or more and 5000 kHz or less, typically 1000 kHz, the average output is set to be 0.1 W or more and 100 W or less, typically 10 W, and the feed rate of the substrate 11 is set to be 10 mm / s or more and 1000 mm / s or less, typically 500 mm / s, respectively. However, the conditions when irradiating the laser beam 40 can be changed within the range where the first processing groove 25 is appropriately formed in the film 13.

[0056] Next, the second processing groove forming step S2 is executed. In the second processing groove forming step S2, a second processing groove is formed by irradiating the bottom of the first processing groove 25 with a laser beam (second laser beam). The operation of the laser processing apparatus 2 is the same as that in the first processing groove forming step S1.

[0057] However, the width of the beam spot of the laser beam used in the second groove forming step S2 and the irradiation conditions of the laser beam are different from the width a of the beam spot 18 of the laser beam 40 used in the first groove forming step S1 and the irradiation conditions of the laser beam 40. Note that the height of the focal point is appropriately adjusted by the laser irradiation unit moving mechanism and the optical element of the irradiation head 8 so that a second groove having an appropriate shape is formed.

[0058] FIG. 7 is a top view of the film 13 and the like in the second groove forming step S2, and FIG. 8 is a cross-sectional view of the film 13 and the like in the second groove forming step S2. As shown in FIG. 7, in the present embodiment, a laser beam (second laser beam) 42 whose beam spot 20 at the bottom of the first groove 25 has a rectangular shape is irradiated onto the bottom of the first groove 25.

[0059] Here, the width (second beam width, length of the long side of the beam spot 20) in the width direction of the division planned line 15 of the laser beam 42 at the irradiation position of the film 13 is c, which is smaller than the width a of the first groove 25. Specifically, c is set to a value of 30% or more and 80% or less of the width of the first groove 25. For example, c is set to be smaller than the width of the first groove 25 in the range of 1 μm or more and 40 μm or less, and typically, c is set to be 10 μm smaller than the width of the first groove 25.

[0060] Also, the profile of the laser beam 42 is a top hat type. Note that the shape, width c, and intensity distribution of the beam spot 20 can be adjusted by a beam shaper, a beam expander, or the like.

[0061] As shown in FIGS. 7 and 8, by scanning such a laser beam 42 on the first groove 25, a region from the bottom of the first groove 25 of the film 13 to a predetermined depth is removed along the first groove 25, and the second groove 27 is formed. When the second groove 27 is formed at the bottom of the first groove 25 provided in all the division planned lines 15, the second groove forming step S2 ends.

[0062] Here, the width of the second processing groove 27 is substantially the same width (second width) c as the width of the beam spot 20. Also, the depth d of the second processing groove 27 is typically set such that the film 13 is removed and the first surface 11a side of the substrate 11 is exposed. That is, the sum of the depth b of the first processing groove 25 and the depth d of the second processing groove 27 is set to be equal to or greater than the thickness of the film 13. However, when forming the second processing groove 27, it is not necessarily required that the first surface 11a side of the substrate 11 be exposed.

[0063] The irradiation conditions of the laser beam 42 for forming the above-described second processing groove 27 may be the same as the irradiation conditions of the laser beam 40 when forming the first processing groove 25, except for the width (length of the long side) of the beam spot 20. However, the conditions when irradiating the laser beam 42 and the like can be changed within the range where the second processing groove 27 is appropriately formed at the bottom of the first processing groove 25.

[0064] Next, the dividing step S3 is executed. FIG. 9 is a perspective view of the substrate 11 and the cutting device 22 and the like in the dividing step S3. In FIG. 9, some components of the cutting device 22 are represented by functional blocks.

[0065] Also, the first direction (direction along the X axis, processing feed direction), the second direction (direction along the Y axis, indexing feed direction), and the third direction (direction along the Z axis, vertical direction) used in the following description of the dividing step S3 are perpendicular to each other. However, each direction used in the description of this dividing step S3 is independent of each direction used in the description of the first processing groove forming step S1 and the second processing groove forming step S2.

[0066] As shown in FIG. 9, the cutting device 22 includes a holding unit 24. The holding unit 24 includes a chuck table including a disk-shaped holding plate and a frame having the same configuration as the holding unit 4 of the laser processing device 2, and a clamp. Further, the holding unit 24 includes a rotational drive source (not shown) such as a motor connected to the chuck table of the holding unit 24. The chuck table of the holding unit 24 obtains a rotational driving force from the rotational drive source and rotates around a rotation axis substantially perpendicular to the first surface of the chuck table of the holding unit 24. However, the configuration of the holding unit 24 may be different from the configuration of the holding unit 4.

[0067] This holding unit 24 is supported by a ball screw type holding unit moving mechanism (not shown) including a ball screw for converting a rotational driving force such as a motor into a linear driving force. The holding unit 24 moves along a first direction (a direction along the X axis in FIG. 9) substantially parallel to the first surface of the chuck table of the holding unit 24 by the linear driving force of this holding unit moving mechanism.

[0068] The cutting device 22 has a cutting unit 26 disposed above the holding unit 4. The cutting unit 26 includes a spindle 28 and a cutting blade 30 attached to the tip of the spindle 28. The spindle 28 is connected to a rotational drive source (not shown) such as a motor and rotates by the rotational driving force obtained from the rotational drive source. Together with this spindle 28, the cutting blade 30 attached to the spindle 28 also rotates.

[0069] The cutting blade 30 has, for example, an annular base (not shown) made of a metal such as stainless steel, and an annular cutting edge (not shown) provided at the peripheral edge of the annular base. The cutting edge is, for example, one in which abrasive grains made of diamond or the like are dispersed and fixed by a binder made of resin, metal, or the like. As this cutting edge, one having a thickness thinner than the width c of the second processing groove is used.

[0070] A pair of nozzles 32 are provided that can supply a processing liquid (processing fluid, grinding fluid) represented by water to the cutting blade 30 so as to sandwich the cutting blade 30 along the Y-axis. The cutting unit 26 is supported by a ball screw type cutting unit moving mechanism (not shown) provided with a ball screw for converting the rotational driving force of a motor or the like into a linear driving force. The cutting unit 26 can be moved along the second direction (the direction along the Y-axis) and the third direction (the direction along the Z-axis) by the cutting unit moving mechanism.

[0071] The cutting device 22 has one or a plurality of transfer mechanisms (not shown) that can transfer the above-described frame unit 23 to the holding unit 24 and the like. The transfer mechanism is, for example, a robot arm. The frame unit 23 is carried into the chuck table of the holding unit 24 by this transfer mechanism so that the first surface 13a side of the film 13 is exposed. Further, the frame unit 23 is carried out of the holding unit 24 to the outside of the holding unit 24 by the transfer mechanism.

[0072] A controller 34 is connected to various components of the above-described cutting device 22. The operations of the respective components of the cutting device 22 are controlled by this controller 34. The configuration of the controller 34 includes a processing device 36 and a storage device 38, similar to the configuration of the controller 12 provided in the laser processing device 2. However, the configuration of the controller 34 is not limited to this.

[0073] In the dividing step S3, under the control of the controller 34, the substrate 11 is divided by the cutting unit 26 along the bottom of the second processing groove 27. That is, the substrate 11 is divided along the division planned line 15. Specifically, first, the frame unit 23 is held by the holding unit 24.

[0074] More specifically, by the above-described transfer mechanism, the frame unit 23 is carried into the chuck table of the holding unit 24, and the portion corresponding to the substrate 11 of the frame unit 23 is placed on the first surface of the holding plate of the chuck table of the holding unit 24. As described above, in the present embodiment, the substrate 11 is placed on the first surface of the holding plate of the chuck table of the holding unit 24 via the tape 19 so that the first surface 13a of the film 13 is exposed upward.

[0075] Thereafter, when the negative pressure of the suction source is applied to the first surface of the holding plate under the control of the controller 34, the portion corresponding to the substrate 11 of the frame unit 23 is sucked by the chuck table. That is, the frame unit 23 is held by the holding unit 24. Note that the substrate 11 may be manually placed on the chuck table of the holding unit 24 by an operator or the like.

[0076] Next, alignment of the cutting blade 30 of the cutting unit 26 and the second processing groove 27 is performed. Specifically, for example, the holding unit 24 is rotated by a rotation drive source (not shown) so that any one of the plurality of second processing grooves 27 (the first second processing groove 27 to be processed first) is parallel to the first direction (the direction along the X axis).

[0077] Also, the positional relationship between the holding unit 24 and the cutting unit 26 in the first direction (the direction along the X axis) and the second direction (the direction along the Y axis) is adjusted by the holding unit movement mechanism and the cutting unit movement mechanism so that the cutting blade 30 is disposed above the extension line of the second processing groove 27. Further, the height of the cutting unit 26 is adjusted by the cutting unit movement mechanism so that the lower end of the cutting blade 30 is disposed below the second surface 11b of the substrate 11 by a predetermined distance.

[0078] Next, the machining fluid is supplied from the nozzle 32 toward the cutting blade 30. Then, while a motor (not shown), which is a rotational drive source, rotates the cutting blade 30 together with the spindle 28, the holding unit moving mechanism moves the holding unit 24 along the first direction (the direction along the X-axis). As a result, the cutting blade 30 and the holding unit 24 relatively move along the first direction (the direction along the X-axis) (machining feed), and the cutting blade 30 cuts into the substrate 11 along the second machining groove 27. Then, the substrate 11 is cut in the second machining groove 27.

[0079] FIG. 10 is a cross-sectional view of the substrate 11, the cutting blade 30, etc. in the dividing step S3. For example, the machining speed (the speed at which the holding unit 24 is fed in the X-axis direction) is set to 5 mm / sec or more and 100 mm / sec or less, typically 50 mm / sec, and the rotational speed of the spindle 28 is set to 500 rpm or more and 5000 rpm or less, typically 3000 rpm, respectively.

[0080] After the substrate 11 is cut along one second machining groove 27, for example, the cutting unit moving mechanism moves the cutting unit 26 in the third direction (the direction along the Z-axis) to move the cutting blade 30 away from the first surface 13a of the film 13. Also, the holding unit moving mechanism moves the holding unit 24 in the opposite direction along the X-axis by the amount by which the holding unit 24 was moved along the first direction (the direction along the X-axis) when machining the first second machining groove 27. Then, by repeating the same operation, the cutting blade 30 cuts along the second machining groove 27 adjacent to the first second machining groove 27, and the substrate 11 is similarly cut along the adjacent second machining groove 27.

[0081] Furthermore, after the second machining groove 27 is formed along the second machining groove 27 adjacent to the first second machining groove 27, the same procedure is repeated for the third and subsequent second machining grooves 27, and the substrate 11 is cut along all the second machining grooves 27 (a total of 11 second machining grooves 27 in FIG. 9) along the same direction as the first second machining groove 27.

[0082] Next, the substrate 11 is cut along the second processing groove 27 that intersects the first-mentioned second processing groove 27. Specifically, the rotation drive source rotates the holding unit 24 by 90 degrees. Also, the positional relationship of the holding unit 24 and the cutting unit 26 in the first direction (the direction along the X-axis) and the second direction (the direction along the Y-axis) is adjusted by the holding unit moving mechanism and the cutting unit moving mechanism so that the lower end of the cutting blade 30 is disposed above the extension line of the second processing groove 27 to be cut next. Further, the height of the cutting unit 26 is adjusted by the cutting unit moving mechanism so that the lower end of the cutting blade 30 is disposed a predetermined distance below the second surface 11b of the substrate 11.

[0083] Then, by the same procedure, the substrate 11 is cut along all the second processing grooves 27 that intersect the first-mentioned second processing groove 27. Thereby, a plurality of regions partitioned by the plurality of division planned lines 15 are divided into individual chips.

[0084] FIG. 11 is a cross-sectional view showing a substrate 29, a film 31, and a laser beam 44 in a comparative example. In the comparative example shown in FIG. 11, a pulsed laser beam 44 is irradiated onto a substrate 29 and a film 31 having the same configuration as the substrate 11 and the film 13 according to the present embodiment. However, in this comparative example, the film 31 is removed so that a processing groove 37 having a depth that is the sum of the depth of the first processing groove 25 and the depth of the second processing groove 27 according to the present embodiment is formed by the irradiation of the laser beam 44. For this purpose, the laser beam 44 is irradiated two or more times (two passes or more) with respect to one processing groove 37.

[0085] As shown in FIG. 11, in this comparative example, first, a portion corresponding to a part of the side wall of the processing groove 37 is formed by the first-pass laser beam 44 irradiated when removing the film 31. Then, the laser beam 44 after the second pass is reflected at a portion corresponding to a part of this side wall. As a result, it is considered that the pulsed laser beam 44 is particularly concentrated and irradiated at the end of the bottom of the processing groove 37, and a portion 39 having a cross-sectional shape like teeth is formed.

[0086] FIG. 12 is a cross-sectional view of the substrate 11, the film 13, the first processing groove 25, and the second processing groove 27 according to the present embodiment. In FIG. 12, for convenience of explanation, the laser beam 40 forming the first processing groove 25 and the laser beam 42 forming the second processing groove 27 are shown together. In the present embodiment, as described above, after the first processing groove 25 having the first width a is formed by irradiating the laser beam 40, the second processing groove 27 having the second width c smaller than the first width a is formed by irradiating the laser beam 42.

[0087] Here, the width of the laser beam 42 used when forming the second processing groove 27 is narrower than the width of the first processing groove 25. Therefore, the laser beam 42 used when forming the second processing groove 27 is substantially not reflected by the side wall of the already formed first processing groove 25. Based on such a principle, in the present embodiment, the laser beam 42 does not concentrate on the bottom end portion (the first surface 11a of the substrate 11) of the second processing groove 27, and it is considered that it is difficult to form a portion having a tooth-like cross-sectional shape at the bottom end portion (the first surface 11a of the substrate 11) of the second processing groove 27.

[0088] As in this comparative example, if a portion 39 having a tooth-like cross-sectional shape is formed at the bottom end portion (the first surface 29a of the substrate 29) of the processing groove, the flexural strength of the chip may decrease or cracks may occur in the chip. However, in the present embodiment, it is difficult to form a portion having a tooth-like shape at the bottom end portion of the processing groove. Thereby, it is considered that a decrease in the flexural strength of the chip and the occurrence of cracks in the chip are prevented.

[0089] In the above-described embodiment, the width of the beam spot 20 of the laser beam 42 in the second processing groove forming step S2 is adjusted so that the width c of the second processing groove 27 is smaller than the width a of the first processing groove 25. However, the diameter of the beam spot 20 of the laser beam 42 in the second processing groove forming step S2 may be adjusted so that the width c of the second processing groove 27 is larger than the width a of the first processing groove 25. In this case, since the end portion of the first processing groove 25 is processed by the laser beam 42, it is considered that the flexural strength of the chip is increased.

[0090] Further, instead of the two processing grooves, i.e., the first processing groove 25 and the second processing groove 27, three or more processing grooves may be formed. In this case, it is desirable to form the processing grooves such that the width of the first-formed processing groove is the largest, and the width becomes smaller as the processing groove becomes deeper.

[0091] Also, in the above-described embodiment, in the dividing step S3, the substrate 11 is divided by cutting using the cutting device 22, but the method of dividing the substrate 11 is not limited to cutting. For example, the substrate 11 may be divided by plasma dicing using plasma. Further, by irradiating a laser beam having a wavelength that penetrates the substrate 11, a modified region is formed in a part of the substrate 11, and by applying a tensile stress to the substrate 11, stealth dicing (SD, registered trademark) that generates cracks from this modified region to divide the substrate 11 may be used.

[0092] Also, in the above-described second processing groove forming step S2, the laser beam 42 is irradiated onto the film 13 (the bottom of the first processing groove 25), but instead of the film 13, the film 13 is removed in the first processing groove forming step S1, and the laser beam 42 may be irradiated onto the removed portion (the first surface 11a of the substrate 11). That is, the first surface 11a of the substrate 11 may be exposed by the irradiation of the laser beam 40 in the first processing groove forming step S1. Also in this case, although not to the same extent as in the above-described embodiment, a certain effect of suppressing a decrease in the fracture strength of the chip and the generation of cracks in the chip can be obtained.

[0093] More specifically, in the first processing groove forming step S1, when the film 13 is removed until the first surface 11a of the substrate 11 is exposed, a tooth-like cross-sectional shape portion is formed at the bottom of the first processing groove (the first surface 11a of the substrate 11) in the same manner as in the above-described comparative example. Subsequently, in the second processing groove forming step S2 that is then performed, when the first surface 11a of the substrate 11 is irradiated with a laser beam, a portion from the first surface 11a of the substrate 11 to a predetermined depth is removed, and the second processing groove is formed. At this time, a part of the tooth-like cross-sectional shape portion formed in the first processing groove forming step is removed. As a result, the sharp portion of the tooth-like cross-sectional shape portion is reduced compared to the comparative example, and the effect of suppressing a decrease in the flexural strength of the chip and the occurrence of cracks in the chip can be obtained.

[0094] Also, when the substrate 11 is irradiated with a laser beam, debris (processing chips) is generated. If the debris remains on the first surface 11a of the substrate 11, for example, when the substrate 11 is a wafer having bumps, when joining the bumps and the electrodes, if debris larger than the bumps exists on the first surface 11a of the substrate 11, it may hinder the joining of the bumps and the electrodes and cause a joining defect.

[0095] As described above, when the second processing groove is formed in the substrate 11 in the second processing groove forming step S2, a stepped cross-sectional shape portion is formed on the first surface 1a side of the substrate 11. Debris is likely to be trapped in this stepped cross-sectional shape portion. Therefore, the debris remaining on the first surface 11a of the substrate 11 is reduced, and problems such as the above-described joining defect between the bumps and the electrodes are less likely to occur.

[0096] Furthermore, although the beam spot 18 of the laser beam 40 in the first processing groove forming step S1 and the beam spot 20 of the laser beam 42 in the second processing groove forming step S2 are rectangular, they may have other shapes as long as the first processing groove 25 and the second processing groove 27 having a desired width can be formed. For example, these may be circular.

[0097] In addition, the structures, methods, etc. according to the above-described embodiments and modifications can be implemented with changes as long as they do not depart from the scope of the object of the present invention.

Explanation of Reference Numerals

[0098] 11: Substrate 11a: First surface 11b: Second surface 11c: Notch 13: Film 13a: First surface 13b: Second surface 15: Predetermined division line 17: Device 19: Sheet 21: Frame 21a: Opening 23: Frame unit 25: First processing groove 27; Second processing groove 29: Substrate 31: Film 33: Device 35: Predetermined division line 37: Processing groove 39: Portion with a tooth-like cross-sectional shape 2: Laser processing apparatus 4: Holding unit 6: Laser irradiation unit 8: Irradiation head 10: Camera 12: Controller 14: Processing device 16: Storage device 18: First beam spot 20: Second beam spot 22: Cutting device 24: Holding unit 26: Cutting unit 28: Spindle 30: Cutting blade 32: Nozzle 34: Controller 36: Processing device 38: Storage device 40: Laser beam 42: Laser beam 44: Laser beam

Claims

1. A method for manufacturing chips by dividing a substrate with a film provided on its surface along a planned division line of a predetermined width to produce a plurality of chips, comprising: a processing groove forming step of forming a processing groove by removing a part of the film along the planned division line; a dividing step of forming a plurality of the chips by dividing the substrate along the bottom of the processing groove after the processing groove forming step. The processing groove forming step includes: a first processing groove forming step of forming a first processing groove having a first width in the width direction by irradiating a first laser beam along the planned division line; a second processing groove forming step of forming a second processing groove having a second width different from the first width in the width direction by irradiating a second laser beam along the planned division line after the first processing groove forming step.

2. The method for manufacturing chips according to Claim 1, wherein the second width is smaller than the first width.

3. The method for manufacturing chips according to Claim 2, wherein the second width is 30% or more and 80% or less of the first width.

4. The method for manufacturing chips according to Claim 1, wherein the second width is larger than the first width.

5. The method for manufacturing chips according to any one of Claims 1 to 4, wherein a first beam width of the first laser beam in the width direction at an irradiation position where the film is irradiated is different from a second beam width of the second laser beam in the width direction at an irradiation position where the film or the substrate is irradiated.

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