Device chip manufacturing method

Abstract

To provide a device chip manufacturing method for manufacturing device chips by forming a modified layer and dividing a wafer, which can divide the wafer well without increasing the number of manufacturing steps.SOLUTION: A device chip manufacturing method includes a first tape application step S11 of applying an adhesive layer 32 of a holding tape 30 having a substrate 31 with an uneven surface 31a to a wafer 10, a second tape application step S12 of applying an adhesive layer 42 of a second tape 40 having a substrate 41 with a flat surface 41a and lower hardness than the substrate 31 of the holding tape 30 to the uneven surface 31a of the holding tape 30, a modified layer formation step S13 of forming a modified layer 14 inside the wafer 10, and a division step S15 of dividing the wafer 10 starting from the modified layer 14 by expanding the holding tape 30.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] A known method for dividing multiple devices formed on the surface of a plate-like wafer into device chips is to form a modified layer inside the wafer by irradiating it with a focused laser beam, and then divide the wafer by applying an external force to this modified layer.

[0003] When a laser beam is irradiated from the surface of a wafer such as a MEMS (Micro Electro Mechanical Systems) wafer with an uneven surface, a metal film, or a TEG (Test Element Group) formed on the planned dividing line, the laser beam may not reach the inside of the wafer due to the influence of the uneven surface, metal film, or TEG, and a sufficient modified layer may not be formed.

[0004] For such wafers, a method is employed in which a modified layer is formed inside the wafer by irradiating a laser beam from the backside of the wafer through tape attached to the backside, as described in Patent Document 1, for example. After the modified layer is formed, the tape is expanded in the planar direction, and the wafer is divided starting from the modified layer. Generally, the tape attached to the wafer has high elasticity to prevent damage to the wafer while sufficiently widening the gap between devices. In addition, the surface of the tape onto which the laser beam is incident is made flat so that the laser beam is sufficiently focused inside the wafer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-29927 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been an increasing demand for processing wafers made of hard and brittle materials. When the above-mentioned tape is applied to such wafers and expanded in the planar direction, the high elasticity of the tape prevents the external force required for dividing the wafers made of hard and brittle materials from being applied to the modified layer, resulting in insufficient division. This requires a process of dividing the wafers by, for example, pressing a breaking blade against the wafers with the modified layer, which reduces productivity.

[0007] The present invention provides a method for manufacturing device chips by forming a modified layer and dividing a wafer, which method can effectively divide a wafer without increasing the number of manufacturing steps. [Means for solving the problem]

[0008] The present invention provides A method for manufacturing device chips by dividing a wafer, on which devices are formed in a plurality of regions defined by a plurality of intersecting planned dividing lines, along the planned dividing lines to manufacture device chips, comprising: a first tape adhering step of adhering a first adhesive layer of a first tape having a first substrate with a surface having an unevenness and a first adhesive layer laminated on a back surface of the first substrate to the wafer; a second tape adhering step of adhering a second adhesive layer of a second tape having a second substrate with a flat surface and a lower hardness than the first substrate and a second adhesive layer laminated on the back surface of the second substrate to the uneven surface of the first tape; a modified layer forming step of irradiating a laser beam onto the wafer from the front surface side of the second tape to form a modified layer inside the wafer along the planned dividing line after the first tape applying step and the second tape applying step; After the modified layer forming step, the method includes a dividing step of dividing the wafer starting from the modified layer by expanding the first tape.

[0009] The present invention also provides A method for manufacturing device chips by dividing a wafer, on which devices are formed in a plurality of regions defined by a plurality of intersecting planned dividing lines, along the planned dividing lines to manufacture device chips, comprising: a first tape adhering step of adhering a first adhesive layer of a first tape to the wafer, the first adhesive layer comprising a first substrate containing any one of polyolefin, polyethylene, and polyethylene terephthalate and having an uneven surface, and a first adhesive layer laminated on the back surface of the first substrate; a second tape adhering step of adhering a second adhesive layer of a second tape having a second substrate with a flat surface and a second adhesive layer laminated on the back surface of the second substrate to the uneven surface of the first tape; a modified layer forming step of irradiating a laser beam onto the wafer from the front surface side of the second tape to form a modified layer inside the wafer along the planned dividing line after the first tape applying step and the second tape applying step; After the modified layer forming step, the method includes a dividing step of dividing the wafer starting from the modified layer by expanding the first tape. [Effects of the Invention]

[0010] According to the present invention, the wafer can be divided well without increasing the number of manufacturing steps. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of a wafer 10 on which devices 15 are formed in multiple regions. [Figure 2] 1 is a perspective view of a wafer 10 supported in an opening 21 of a ring frame 20 via a holding tape 30. FIG. [Figure 3]1 is a perspective view schematically showing how a wafer 10 is processed by a laser processing device 1. FIG. [Figure 4] 1 is a flowchart of a method for manufacturing a device chip according to an embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view of the wafer 10 for explaining the first tape attaching step S11. [Figure 6] FIG. 10 is a cross-sectional view of the wafer 10 for explaining the second tape attaching step S12. [Figure 7] FIG. 10 is a cross-sectional view of the wafer 10 for explaining the modified layer forming step S13. [Figure 8] FIG. 10 is a cross-sectional view of the wafer 10 for explaining the peeling step S14. [Figure 9] FIG. 10 is a schematic diagram for explaining the division step S15. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, one embodiment of the device chip manufacturing method of the present invention will be described with reference to the accompanying drawings. Prior to the detailed description of the device chip manufacturing method, a wafer having devices formed in a plurality of regions and a laser processing apparatus used in the device chip manufacturing method will be described with reference to FIGS.

[0013] FIG. 1 is a perspective view of a wafer 10. The wafer 10 is a substrate having a substantially circular shape and is made of, for example, a semiconductor material or an inorganic material. Examples of semiconductor materials include silicon (Si), silicon carbide (SiC), gallium nitride (GaN), and gallium arsenide (GaAs). Examples of inorganic materials include sapphire, glass, and ceramics. The wafer 10 may also be made of a metal material, a resin material, or the like.

[0014] The surface 11 of the wafer 10 has a plurality of regions defined by a plurality of intersecting division lines L (dash-dotted lines), and devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), and MEMS are formed in each region. The division lines L include a plurality of division lines Lx extending in the X direction in the figure and a division line Ly extending in the Y direction (a direction perpendicular to the X direction) in the figure and intersecting the division lines Lx. The division lines Lx and Ly define a grid pattern of the plurality of regions. By dividing the wafer 10 along the division lines L, the devices 15 formed on the wafer 10 are divided into device chips 15C (see FIG. 9).

[0015] 2 is a perspective view of the wafer 10 supported in the opening 21 of the ring frame 20 via the holding tape 30. The holding tape 30 is attached to the back surface 12 of the wafer 10, i.e., the surface opposite to the front surface 11 on which the devices 15 are formed.

[0016] Fig. 3 is a perspective view that schematically shows how the wafer 10 is processed by the laser processing apparatus 1. Note that the reference numeral 40 in Fig. 3 denotes a second tape 40 that is attached to the holding tape 30 in this embodiment, and details will be described later.

[0017] The laser processing apparatus 1 includes a holding table 2 that holds a wafer 10 supported by a ring frame 20, an imaging unit 3 that images the wafer 10, and a laser irradiation unit 4 that focuses and irradiates a laser beam along a planned dividing line L of the wafer 10 to form a modified layer 14 inside the wafer 10. Although not shown, the laser processing apparatus 1 further includes a moving unit that moves the relative positions of the laser irradiation unit 4 and the wafer 10 in the horizontal and vertical directions.

[0018] The wafer 10 is placed upside down on the holding table 2 so that the laser beam is incident on the back surface 12 of the wafer 10. The holding table 2 has a circular holding surface, on which a porous member is exposed. A suction path is formed inside the holding table 2, which communicates with the porous member and is connected to suction means such as an ejector. The holding table 2 fixes the ring frame 20 to the holding surface with a clamp, and the wafer 10 supported by the ring frame 20 is suction-held by the suction means.

[0019] The imaging unit 3 is provided to face the wafer 10 placed on the holding table 2, and captures an image of the wafer 10. Specifically, the imaging unit 3 is a microscope camera unit including a condenser lens, an image sensor, and the like.

[0020] The laser irradiation unit 4 emits a pulsed laser beam of a predetermined wavelength that passes through the wafer 10 and the holding tape 30. The laser irradiation unit 4 has a condenser 4a disposed opposite the wafer 10 placed on the holding table 2, and is configured to be able to focus and irradiate the laser beam at a desired position inside the wafer 10. The laser irradiation unit 4 positions a focusing point inside the wafer 10, and focuses and irradiates the laser beam along the planned dividing line L while moving the focusing point and the wafer 10 relatively, thereby forming a modified layer 14 along the planned dividing line L.

[0021] The wafer 10 is divided starting from the modified layer 14 by applying an external force to the modified layer 14. Specifically, the wafer 10 is divided starting from the modified layer 14 by expanding the holding tape 30 attached to the back surface 12 in the planar direction, thereby applying an external force to the modified layer 14. As a result, the multiple devices 15 formed on the wafer 10 are divided into individual pieces, and multiple device chips 15C are manufactured.

[0022] Next, the method for manufacturing the device chip of the present invention will be described in detail.

[0023] Generally, the holding tape attached to the wafer 10 is made of a low-hardness material and has high elasticity in order to prevent damage to the wafer 10 when it expands in the planar direction and to increase the spacing between the devices 15 formed on the wafer 10. An example of a low-hardness material is vinyl chloride.

[0024] However, in recent years, there has been an increasing demand for processing wafers 10 formed from hard and brittle materials (hereinafter also referred to as hard and brittle materials), such as glass, sapphire, and gallium nitride. When a highly elastic holding tape is attached to a wafer 10 formed from a hard and brittle material and the wafer is expanded in the planar direction, the high elasticity of the holding tape prevents the external force required to divide the wafer 10 from being applied to the modified layer 14, and the division may not be sufficient. This requires a step of pressing a breaking blade, for example, against the wafer 10 on which the modified layer 14 has been formed to divide the wafer 10, which poses a problem of reduced productivity.

[0025] To improve the divisibility of the wafer 10 by expanding the holding tape, it is conceivable to form the holding tape from a hard material. However, holding tapes with high hardness usually have an uneven surface. Because the refractive index of the laser beam differs between air and the holding tape, the laser beam is refracted on the surface of the holding tape when it enters the holding tape from the air. However, if the holding tape has an uneven surface, the refracted laser beam may not be sufficiently focused inside the wafer 10, and the modified layer 14 may not be formed.

[0026] Therefore, in this embodiment, a holding tape 30 having a high hardness and an uneven surface 31a is attached to the wafer 10, and a second tape 40 having a flat surface 41a is attached to the uneven surface 31a of the holding tape 30. Hereinafter, each step of the method for manufacturing the device chip 15C will be described with reference to FIGS.

[0027] 4 is a flowchart of a method for manufacturing the device chip 15C. The method for manufacturing the device chip 15C includes a first tape application step S11, a second tape application step S12, a modified layer formation step S13, a peeling step S14, and a dividing step S15.

[0028] 5 is a cross-sectional view of the wafer 10 for explaining the first tape application step S11. In the first tape application step S11, a holding tape 30 is applied to the back surface 12 of the wafer 10. The wafer 10 is formed of a hard and brittle material, such as glass, sapphire, or GaN.

[0029] The holding tape 30 has a substrate 31 and an adhesive layer 32. The substrate 31 is made of a material that is harder and less flexible than commonly used vinyl chloride substrates. For example, the substrate 31 is made of a material containing any of polyolefin (PO), polyethylene (PE), and polyethylene terephthalate (PET).

[0030] The surface 31a of the base material 31 is provided with minute irregularities. The irregularities on the surface 31a prevent the holding tape 30 from sticking to the holding table 2 of the laser processing device 1 when the wafer 10 is placed on the holding table 2. While the holding tape 30 has a thickness of several tens of μm, the irregularities on the surface 31a have a height of, for example, about 1.0 μm to several μm. In addition, an adhesive layer 32 is laminated on the back surface 31b of the base material 31, and the adhesive layer 32 is attached to the back surface 12 of the wafer 10 and the ring frame 20.

[0031] 6 is a cross-sectional view of the wafer 10 for explaining the second tape applying step S12. In the second tape applying step S12, the second tape 40 is applied to the surface 31a of the holding tape 30 on which the concave and convex portions are formed.

[0032] The second tape 40 has a substrate 41 and an adhesive layer 42. The substrate 41 is formed of a material that is lower in hardness than the substrate 31 of the holding tape 30. For example, the substrate 41 is formed of a material that contains vinyl chloride.

[0033] The surface 41a of the substrate 41 is flat. Here, "flat" means that the degree of unevenness is less than that of the surface 31a of the holding tape 30. Specifically, even if the surface 41a of the substrate 41 has unevenness, the degree of unevenness is sufficiently smaller than that of the surface 31a of the holding tape 30 (for example, the height of the uneven portion is less than 0.5 μm). In addition, an adhesive layer 42 is laminated on the back surface 41b of the substrate 41, and the adhesive layer 42 is attached to the surface 31a of the holding tape 30, which has unevenness.

[0034] The second tape 40 has the same size as the wafer 10 or a size larger than the wafer 10. Furthermore, the second tape 40 preferably has a size smaller than the holding tape 30. This makes it easier to peel the second tape 40 from the holding tape 30 in the peeling step S14 described below, improving the workability of the peeling step S14. Furthermore, the amount of second tape 40 consumed can be reduced. The second tape 40 may have the same size as the holding tape 30 or a size larger than the holding tape 30. Furthermore, the second tape 40 may be attached to the ring frame 20 in addition to the holding tape 30.

[0035] In the second tape application step S12, it is preferable to heat the second tape 40 in advance to soften the adhesive layer 42. This can improve the adhesiveness of the second tape 40.

[0036] 6, in the second tape attachment step S12, the adhesive layer 42 of the second tape 40 is attached to the uneven surface 31a of the holding tape 30 in a state where it is attached to the wafer 10. This allows the second tape 40 to be attached so as to overlap the entire wafer 10 reliably, thereby preventing the second tape 40 from shifting in position relative to the wafer 10.

[0037] In the second tape application step S12, the adhesive layer 42 of the second tape 40 may be applied to the uneven surface 31a of the holding tape 30 before it is applied to the wafer 10. In other words, in the first tape application step S11, the holding tape 30 to which the second tape 40 has been applied may be applied to the back surface 12 of the wafer 10. This reduces the number of steps required for the step of applying the tape to the wafer 10.

[0038] 7 is a cross-sectional view of the wafer 10 illustrating the modified layer forming step S13. In the modified layer forming step S13, after the first tape applying step S11 and the second tape applying step S12, a laser beam is irradiated onto the wafer 10 from the surface 41a side of the second tape 40 to form a modified layer 14 inside the wafer 10 along the planned division line L (see FIG. 1).

[0039] Since the surface 41a of the second tape 40 onto which the laser beam is incident is flat, the laser beam can be sufficiently focused inside the wafer 10 through the second tape 40 and the holding tape 30, and a modified layer 14 can be reliably formed inside the wafer 10.

[0040] 8 is a cross-sectional view of the wafer 10 for explaining the peeling step S14. In the peeling step S14, the second tape 40 is peeled off from the holding tape 30 before the dividing step S15.

[0041] If the second tape 40 remains attached to the holding tape 30 when the tape is thermally shrunk after the dividing step S15, the difference in the thermal shrinkage rates of the two tapes may cause slack. In this embodiment, the second tape 40 is separated from the holding tape 30 in the peeling step S14, preventing such slack. Furthermore, when grip rings (inner ring and outer ring) (not shown) are fitted to the wafer 10 after the dividing step S15, the thickness of the sandwiched tape is reduced by performing the peeling step S14, which makes it easier to remove the grip rings.

[0042] To improve the workability of the peeling step S14, the adhesive layer 42 of the second tape 40 may be formed of an ultraviolet curing resin. In this case, the adhesive strength of the adhesive layer 42 can be reduced by irradiating the second tape 40 with ultraviolet light before the peeling step S14.

[0043] 9 is a schematic diagram for explaining the dividing step S15. In the dividing step S15, the wafer 10 is divided starting from the modified layer 14 by expanding the holding tape 30. The upper diagram in FIG. 9 shows the state of the holding tape 30 before expansion, and the lower diagram shows the state of the holding tape 30 after expansion.

[0044] The tape expansion device 90 used in the division step S15 comprises a support base 91 having an approximately cylindrical shape that supports the wafer 10 having the holding tape 30 attached thereto from below, a frame holding portion 92 that is provided radially outside the support base 91 and holds the ring frame 20, and a piston 93 that is connected to the lower portion of the frame holding portion 92 and moves up and down by a cylinder not shown.

[0045] The wafer 10 is placed on the support table 91 so that it is positioned above the holding tape 30. When the support table 91 and the frame holding part 92 are moved relative to each other in the vertical direction and the ring frame 20 held by the frame holding part 92 is lowered relative to the support table 91, the holding tape 30 expands in the planar direction and a horizontal external force is applied to the modified layer 14. As a result, the wafer 10 is broken along the intended division lines L starting from the modified layer 14, and is divided into individual devices 15, thereby manufacturing device chips 15C.

[0046] As explained above, the base material 31 of the holding tape 30 attached to the wafer 10 has high hardness, so when the holding tape 30 is expanded in the dividing step S15, an external force of a magnitude sufficient for dividing is applied to the modified layer 14 of the wafer 10, reducing the occurrence of undivided wafers 10. Therefore, in the dividing step S15, for example, a step of pressing a breaking blade against the wafer 10 is not necessary, and the wafer 10 can be divided well without increasing the manufacturing process for the device chips 15C.

[0047] Furthermore, although the surface 31a of the holding tape 30 is uneven, a flat second tape 40 is attached to the surface 31a of the holding tape 30, and the laser beam is irradiated onto the flat surface of the second tape 40, so that the laser beam refracted at the incident surface can be sufficiently focused at the desired position on the wafer 10, and a modified layer can be reliably formed inside the wafer 10.

[0048] Although one embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiment may be combined in any manner without departing from the spirit of the invention.

[0049] For example, in the above-described embodiment, the method for manufacturing a device chip was applied to a wafer 10 formed from a hard and brittle material including glass, sapphire, or GaN, but is not limited to this and can also be applied to a wafer 10 formed from a material other than a hard and brittle material.

[0050] Furthermore, in the above-described embodiment, the substrate 41 of the second tape 40 is formed from a material having a lower hardness than the substrate 31 of the holding tape 30, but this is not limited to this, and the substrate 41 may be formed from a material having a higher hardness as long as the surface 41a is flat.

[0051] This specification describes at least the following: In parentheses, components corresponding to those in the above-described embodiments are shown as examples, but the present invention is not limited to these.

[0052] (1) A method for manufacturing a device chip, in which a wafer (wafer 10) on which devices (devices 15) are formed in a plurality of regions defined by a plurality of intersecting planned dividing lines (planned dividing lines L) is divided along the planned dividing lines to manufacture device chips (device chips 15C), A first tape (holding tape 30) has a first substrate (substrate 31) having an uneven surface (surface 31a) and a first adhesive layer (adhesive layer 32) laminated on a back surface (back surface 31b) of the first substrate. The first adhesive layer of the first tape (holding tape 30) is attached to the wafer. A first tape attaching step (first tape attaching step S11) a second tape (second tape 40) having a second substrate (substrate 41) with a flat surface (surface 41a) and a lower hardness than the first substrate, and a second adhesive layer (adhesive layer 42) laminated on a back surface (back surface 41b) of the second substrate, the second adhesive layer being attached to the uneven surface of the first tape; and a second tape attaching step (second tape attaching step S12) After the first tape attaching step and the second tape attaching step, a modified layer forming step (modified layer forming step S13) is performed in which a laser beam is irradiated onto the wafer from the surface side of the second tape to form a modified layer (modified layer 14) inside the wafer along the planned dividing line; and a dividing step (dividing step S15) of dividing the wafer starting from the modified layer by expanding the first tape after the modified layer forming step. A method for manufacturing a device chip.

[0053] According to (1), the first substrate of the first tape attached to the wafer has high hardness, so when the first tape is expanded in the dividing step, an external force of sufficient magnitude required for dividing the wafer is applied to the modified layer, reducing the occurrence of undivided wafers. Therefore, the dividing step does not require a process of pressing a breaking blade against the wafer, for example, and the wafer can be divided successfully without increasing the number of device chip manufacturing processes. Furthermore, although the surface of the first tape is uneven, a flat second tape is attached to the surface of the first tape, and the laser beam is irradiated onto the flat surface of the second tape. Therefore, the laser beam refracted at the incident surface can be sufficiently focused at the desired position on the wafer, reliably forming a modified layer inside the wafer.

[0054] (2) A method for manufacturing the device chip according to (1), The method further includes a peeling step (peeling step S14) of peeling the second tape from the first tape before the dividing step. A method for manufacturing a device chip.

[0055] When the tape is heat-shrunk after the dividing step, if the second tape is attached to the first tape, the difference in the thermal shrinkage rate of the two tapes may cause slack. According to (2), the second tape is peeled off from the first tape before the dividing step, so the occurrence of such slack can be prevented. Furthermore, when grip rings (inner ring and outer ring) are fitted to the wafer after the dividing step, the thickness of the sandwiching tape is reduced, so the grip rings can be easily removed.

[0056] (3) A method for manufacturing the device chip according to (1) or (2), The second tape applying step applies the second adhesive layer of the second tape, which has been softened by heating, to the uneven surface of the first tape. A method for manufacturing a device chip.

[0057] According to (3), the adhesiveness of the second tape can be improved.

[0058] (4) A method for producing a device chip according to any one of (1) to (3), The wafer includes any one of glass, sapphire, and gallium nitride. A method for manufacturing a device chip.

[0059] According to (4), even when a wafer containing a hard and brittle material is divided by expanding the first tape, the first base material of the first tape has high hardness, so that the wafer can be divided well.

[0060] (5) A method for producing a device chip according to any one of (1) to (4), The first substrate of the first tape contains any one of polyolefin, polyethylene, and polyethylene terephthalate. A method for manufacturing a device chip.

[0061] According to (5), the first base material of the first tape is made of a material with high hardness, so that the wafer can be easily divided.

[0062] (6) A method for producing a device chip according to any one of (1) to (5), the second tape attaching step attaches the second adhesive layer of the second tape to the uneven surface of the first tape in a state where the first tape is attached to the wafer; A method for manufacturing a device chip.

[0063] According to (6), it is possible to suppress the second tape from being misaligned with respect to the wafer.

[0064] (7) A method for producing a device chip according to any one of (1) to (5), The second tape attaching step includes attaching the second adhesive layer of the second tape to the uneven surface of the first tape before attaching it to the wafer. A method for manufacturing a device chip.

[0065] According to (7), the number of steps required to attach the tape to the wafer can be reduced.

[0066] (8) A method for manufacturing the device chip according to (2), the second tape is smaller than the first tape; A method for manufacturing a device chip.

[0067] According to (8), the second tape can be easily peeled off from the first tape, improving the workability of the peeling step and reducing the consumption of the second tape.

[0068] (9) A method for manufacturing a device chip, in which a wafer (wafer 10) on which devices (devices 15) are formed in a plurality of regions defined by a plurality of intersecting planned dividing lines (planned dividing lines L) is divided along the planned dividing lines to manufacture device chips (device chips 15C), a first tape (holding tape 30) including a first substrate (substrate 31) containing any one of polyolefin, polyethylene, and polyethylene terephthalate and having an uneven surface (surface 31a) and a first adhesive layer (adhesive layer 32) laminated on a back surface (back surface 31b) of the first substrate; and a first tape adhering step (first tape adhering step S11) of adhering the first adhesive layer to the wafer; a second tape (second tape 40) having a second substrate (substrate 41) with a flat surface (surface 41a) and a second adhesive layer (adhesive layer 42) laminated on a back surface (back surface 41b) of the second substrate, the second adhesive layer being attached to the uneven surface of the first tape; After the first tape attaching step and the second tape attaching step, a modified layer forming step (modified layer forming step S13) is performed in which a laser beam is irradiated onto the wafer from the surface side of the second tape to form a modified layer (modified layer 14) inside the wafer along the planned dividing line; and a dividing step (dividing step S15) of dividing the wafer starting from the modified layer by expanding the first tape after the modified layer forming step. A method for manufacturing a device chip.

[0069] According to (9), the first substrate of the first tape attached to the wafer is formed of a high-hardness material. Therefore, when the first tape is expanded in the dividing step, a sufficient external force is applied to the modified layer of the wafer for dividing, reducing the occurrence of undivided wafers. Therefore, the dividing step does not require a process of pressing a breaking blade against the wafer, for example, and the wafer can be divided successfully without increasing the number of device chip manufacturing processes. Furthermore, although the surface of the first tape is uneven, a flat second tape is attached to the surface of the first tape, and the laser beam is irradiated onto the flat surface of the second tape. Therefore, the laser beam refracted at the incident surface can be sufficiently focused at the desired position on the wafer, reliably forming a modified layer inside the wafer.

[0070] (10) A method for manufacturing the device chip according to (9), the first substrate of the first tape has a higher hardness than the second substrate of the second tape; A method for manufacturing a device chip.

[0071] According to (10), the occurrence of undivided wafers can be reduced. [Explanation of symbols]

[0072] 10 wafers 14 Modified layer 15 devices 15C device chip 30 Retaining tape (first tape) 31 Base material (first base material) 31a surface 31b back side 32 glue layer (first glue layer) 41 Base material 41a surface 41b back side 42 Glue layer L planned division line S11 First tape application step S12 Second tape application step S13 Modified layer formation step S14 Peeling step S15 Division Step

Claims

1. A method for manufacturing device chips by dividing a wafer, on which devices are formed in a plurality of regions defined by a plurality of intersecting planned dividing lines, along the planned dividing lines to manufacture device chips, comprising: a first tape adhering step of adhering a first adhesive layer of a first tape having a first substrate with a surface having an unevenness and a first adhesive layer laminated on a back surface of the first substrate to the wafer; a second tape adhering step of adhering a second adhesive layer of a second tape having a second substrate with a flat surface and a lower hardness than the first substrate and a second adhesive layer laminated on the back surface of the second substrate to the uneven surface of the first tape; a modified layer forming step of irradiating a laser beam onto the wafer from the front surface side of the second tape to form a modified layer inside the wafer along the planned dividing line after the first tape applying step and the second tape applying step; and a dividing step of dividing the wafer starting from the modified layer by expanding the first tape after the modified layer forming step. A method for manufacturing a device chip.

2. 2. A method for manufacturing a device chip according to claim 1, comprising: The method further includes a peeling step of peeling the second tape from the first tape before the dividing step. A method for manufacturing a device chip.

3. 3. A method for manufacturing the device chip according to claim 1 or 2, The second tape applying step applies the second adhesive layer of the second tape, which has been softened by heating, to the uneven surface of the first tape. A method for manufacturing a device chip.

4. 3. A method for manufacturing the device chip according to claim 1 or 2, The wafer includes any one of glass, sapphire, and gallium nitride. A method for manufacturing a device chip.

5. 3. A method for manufacturing the device chip according to claim 1 or 2, The first substrate of the first tape contains any one of polyolefin, polyethylene, and polyethylene terephthalate. A method for manufacturing a device chip.

6. 3. A method for manufacturing the device chip according to claim 1 or 2, the second tape attaching step attaches the second adhesive layer of the second tape to the uneven surface of the first tape in a state where the first tape is attached to the wafer; A method for manufacturing a device chip.

7. 3. A method for manufacturing the device chip according to claim 1 or 2, The second tape attaching step includes attaching the second adhesive layer of the second tape to the uneven surface of the first tape before attaching it to the wafer. A method for manufacturing a device chip.

8. 3. A method for manufacturing a device chip according to claim 2, comprising: the second tape is smaller than the first tape; A method for manufacturing a device chip.

9. A method for manufacturing device chips by dividing a wafer, on which devices are formed in a plurality of regions defined by a plurality of intersecting planned dividing lines, along the planned dividing lines to manufacture device chips, comprising: a first tape adhering step of adhering a first adhesive layer of a first tape, the first adhesive layer comprising a first substrate containing any one of polyolefin, polyethylene, and polyethylene terephthalate and having an uneven surface, and a first adhesive layer laminated on a rear surface of the first substrate, to the wafer; a second tape adhering step of adhering a second adhesive layer of a second tape having a second substrate with a flat surface and a second adhesive layer laminated on the back surface of the second substrate to the uneven surface of the first tape; a modified layer forming step of irradiating a laser beam onto the wafer from the front surface side of the second tape to form a modified layer inside the wafer along the planned dividing line after the first tape applying step and the second tape applying step; and a dividing step of dividing the wafer starting from the modified layer by expanding the first tape after the modified layer forming step. A method for manufacturing a device chip.

10. 10. A method for manufacturing a device chip according to claim 9, comprising: the first substrate of the first tape has a higher hardness than the second substrate of the second tape; A method for manufacturing a device chip.

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