Manufacturing method and setup method

Abstract

This reduces the possibility that thin-walled portions separated from the thinned wafer may remain on the protective material. [Solution] A manufacturing method for producing a second substrate by separating a part of the thin-walled portion of a first substrate, which has a protrusion formed along its outer edge and a thin-walled portion whose outside is surrounded by the protrusion, and to which a protective member is fixed on one surface, as a second substrate, comprising: setting the inner edge of a removal region that defines the outer shape of the second substrate in the thin-walled portion located inside the outer edge of the holding surface; setting the outer edge of the removal region on the first substrate such that, in the radial direction of the first substrate, the outer edge of the removal region is located at or outside the midpoint of the inner edge of the removal region and the outer edge of the holding surface; separating the second substrate from the first substrate by removing the removal region in the thickness direction of the first substrate; and peeling off the protrusion, the outer edge of the removal region and the thin-walled portion between the protrusion from the protective member.

Description

Technical Field

[0001] The present invention relates to a manufacturing method for manufacturing a second substrate by separating a part of a thin portion of a first substrate, which has a protruding portion formed along an outer peripheral edge and a thin portion surrounded by the protruding portion, and to which a protective member is fixed on one surface, from the first substrate, a manufacturing method for manufacturing a plurality of chips from the first substrate, and a setting method for setting a removal region on the first substrate in order to separate a part of the thin portion of the first substrate as the second substrate.

Background Art

[0002] In order to ensure the rigidity of a wafer in a manufacturing process, it has been proposed to thin the central portion of the wafer without thinning the outer peripheral portion of the wafer, thereby forming an annular protruding portion (i.e., a ring-shaped reinforcing portion) and a thin portion surrounded by the protruding portion on the wafer, and then performing processing on this wafer (see, for example, Patent Document 1).

[0003] In this wafer, the thin portion and the annular protruding portion define a concave portion located at the central portion of the back surface of the wafer. Note that, in the central portion of the surface of the wafer, which is located on the center side of the protruding portion in the radial direction of the wafer, a plurality of devices are usually provided regularly.

[0004] Before finally dividing this wafer into a plurality of devices, the protruding portion is separated from the wafer (separation step). In order to perform the separation step, first, the central portion of a thin resin protective member is attached to the back surface of the wafer, and a metal ring frame is attached to the outer peripheral portion of the protective member. At this time, the protective member is attached following the concave portion of the wafer.

[0005] Next, for example, the separation step is performed using a laser processing apparatus. In the separation step, a wafer unit in which the wafer and the ring frame are integrated through the protective member is sucked and held by a holding plate of the laser processing apparatus so that the surface of the wafer is exposed.

[0006] Furthermore, since the diameter of the holding surface of the holding plate is smaller than the diameter of the recess, when the wafer is held by suction with the holding plate, the holding surface positioned within the recess suction-holds the thin portion of the wafer via the protective member. At this time, the protruding portion of the wafer is positioned on the radially outer side of the holding surface.

[0007] Then, by irradiating the outer periphery of the thin-walled portion with a laser beam having a wavelength absorbed by the wafer, laser-processed grooves are formed in the thin-walled portion by ablation so as to penetrate the thin-walled portion in the thickness direction of the wafer.

[0008] Next, the adhesive force of the protective member is reduced in the annular region located radially outside the holding plate, and the protruding portion is removed from the protective member to obtain a thinned wafer that is smaller in diameter than the original wafer and corresponds to the central part of the thin-walled section. After the separation process, the thinned wafer is divided into device units using a dicing device to manufacture multiple device chips.

[0009] Incidentally, the size of the thinned wafer is adjusted as appropriate according to the area in which multiple devices are installed (i.e., the size of the device area), so the diameter of the thinned wafer may be smaller than the outer diameter of the holding plate of the laser processing machine.

[0010] Therefore, when laser-cut grooves are formed along the outer edge of the device region, an annular thin-walled portion may remain separated from the thinned wafer, overlapping with the holding surface in the wafer thickness direction. The outer periphery of this remaining annular thin-walled portion remains connected to the wafer's protrusions.

[0011] If the protruding part is removed from the protective member while the annular thin-walled portion connected to the protruding part remains in place, a crack may occur at the boundary between the annular thin-walled portion and the protruding part. As a result, the annular thin-walled portion may separate from the protruding part and remain attached to the protective member instead of being removed together with the protruding part.

[0012] If the remaining thin portion located between the laser-cut groove and the protrusion in the radial direction of the wafer remains on the protective material along with the thinned wafer, an additional removal process is required to remove the remaining thin portion from the protective material, thus reducing productivity. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 2022-114113 [Overview of the Initiative] [Problems that the invention aims to solve]

[0014] This invention has been made in view of the aforementioned problems, and aims to reduce the possibility that thin-walled portions separated from the thinned wafer remain on the protective member. [Means for solving the problem]

[0015] According to one aspect of the present invention, a manufacturing method for producing a second substrate is provided, which involves separating a part of the thin-walled portion of a first substrate having a protrusion formed along its outer edge and a thin-walled portion whose outer side is surrounded by the protrusion, and having a protective member fixed to one surface of the first substrate, the method comprising: a holding step of holding the first substrate with the holding surface of a holding plate; a removal region inner edge setting step of setting the inner edge of a removal region that defines the outer shape of the second substrate in the thin-walled portion located inside the outer edge of the holding surface; and in the radial direction of the first substrate, the outer edge of the removal region A manufacturing method is provided, comprising: a removal area peripheral edge setting step of setting the peripheral edge of the removal area on the first substrate such that the edge is located at or outside the midpoint of the inner peripheral edge of the removal area and the peripheral edge of the holding surface; a separation step of separating the second substrate from the first substrate by removing the removal area in the thickness direction of the first substrate; and a protrusion peeling step of peeling the protrusion, the peripheral edge of the removal area and the thin portion between the protrusion and the protrusion from the protective member by moving the protrusion and the second substrate relative to each other after the separation step.

[0016] Preferably, in the step of setting the outer edge of the removal area, the outer edge of the removal area is set inward from the outer edge of the retaining surface such that the distance between the outer edge of the removal area and the outer edge of the retaining surface in the radial direction is 0.20 mm or less.

[0017] Preferably, in the step of setting the outer edge of the removal area, the outer edge of the removal area is set at a position corresponding to the outer edge of the retaining surface.

[0018] Preferably, in the step of setting the outer edge of the removal area, the outer edge of the removal area is set to be outside the outer edge of the retaining surface in the radial direction.

[0019] Preferably, in the protruding portion peeling step, a peeling member is inserted between the protective member and the region corresponding to one surface of the protruding portion to peel off the protruding portion, the outer edge of the removal region, and the thin portion between the protruding portion from the protective member.

[0020] According to another aspect of the present invention, a manufacturing method for manufacturing a plurality of chips from a first substrate having a projection formed along its outer edge and a thin-walled portion whose outer side is surrounded by the projection, and having a protective member fixed to one surface, comprising: a holding step of holding the first substrate with the holding surface of a holding plate; a removal region inner edge setting step of setting the inner edge of a removal region that defines the outer shape of a second substrate of a predetermined size in the thin-walled portion located inside the outer edge of the holding surface; and in the radial direction of the first substrate, the outer edge of the removal region and the inner edge of the removal region and the outer edge of the holding surface A manufacturing method is provided, comprising: a removal area peripheral edge setting step of setting the outer edge of the removal area on the first substrate so that it is located at or outside the midpoint of the removal area; a separation step of separating the second substrate from the first substrate by removing the removal area in the thickness direction of the first substrate; a protrusion peeling step of peeling the protrusion, the outer edge of the removal area and the thin portion between the protrusion and the second substrate from the protective member by moving the protrusion and the second substrate relative to each other after the separation step; and a division step of dividing the second substrate into a plurality of chips after the protrusion peeling step.

[0021] According to still another aspect of the present invention, there is provided a setting method for setting a removal region in a first substrate having a protruding portion formed along an outer peripheral edge and a thin portion surrounded by the protruding portion on the outside, and having a protective member fixed to one surface, for separating a part of the thin portion of the first substrate as a second substrate. The setting method includes: a holding step of holding the first substrate on a holding surface of a holding plate; a removal region inner peripheral edge setting step of setting an inner peripheral edge of the removal region that defines an outer shape of the second substrate in the thin portion located inside an outer peripheral edge of the holding surface; and a removal region outer peripheral edge setting step of setting the outer peripheral edge of the removal region on the first substrate such that, in a radial direction of the first substrate, the outer peripheral edge of the removal region is located at a midpoint between the inner peripheral edge of the removal region and the outer peripheral edge of the holding surface or outside the midpoint.

Advantages of the Invention

[0022] In the manufacturing method according to one aspect of the present invention, an inner peripheral edge and an outer peripheral edge of a removal region are set on a first substrate. In particular, in the removal region outer peripheral edge setting step, in a radial direction of the first substrate, the outer peripheral edge of the removal region is set on the first substrate such that the outer peripheral edge of the removal region is located at a midpoint between the inner peripheral edge of the removal region and the outer peripheral edge of the holding surface or outside the midpoint.

[0023] Therefore, compared with the case where the outer peripheral edge of the removal region is located inside the midpoint in the radial direction of the first substrate, in a plan view of the wafer, the area of the region of the thin portion remaining integrally with the protruding portion is reduced, so that cracking at the boundary between the thin portion and the protruding portion can be prevented, and the possibility that the thin portion separated from the thinned wafer remains on the protective member can be reduced.

[0024] Also, in the manufacturing method according to another aspect of the present invention and the setting method according to still another aspect of the present invention, for the same reason, the possibility that the thin portion separated from the thinned wafer remains on the protective member can be reduced.

Brief Description of the Drawings

[0025] [Figure 1] It is a flowchart of a manufacturing method for manufacturing a plurality of chips. [Figure 2] FIG. 2(A) is a perspective view of the front side of the wafer, FIG. 2(B) is a perspective view of the back side of the wafer, and FIG. 2(C) is a cross-sectional view taken along line A-A of FIG. 2(B). [Figure 3] It is a partial cross-sectional side view showing the holding step. [Figure 4] FIG. 4(A) is a diagram showing the inner peripheral edge setting step of the removal region, and FIG. 4(B) is a diagram showing the outer peripheral edge setting step of the removal region. [Figure 5] FIG. 5(A) is a plan view of the wafer showing the removal region, and FIG. 5(B) is a cross-sectional view taken along line B-B of FIG. 5(A). [Figure 6] FIG. 6(A) is a partial cross-sectional side view showing an example at the start of the separation step, and FIG. 6(B) is a partial cross-sectional side view showing an example at the end of the separation step. [Figure 7] FIG. 7(A) is a partial cross-sectional side view showing the start of the protrusion peeling step, and FIG. 7(B) is a partial cross-sectional side view showing the annular thin-walled portion and the protrusion that fall integrally in the protrusion peeling step. [Figure 8] It is a partial cross-sectional side view showing the peeling step in the related art. [Figure 9] It is a partial cross-sectional side view showing the dividing step. [Figure 10] FIG. 10(A) is a plan view of the wafer showing the inner peripheral edge setting step and the outer peripheral edge setting step of the removal region in the second embodiment, and FIG. 10(B) is a cross-sectional view taken along line C-C of FIG. 10(A). [Figure 11] FIG. 11(A) is a plan view of the wafer showing the inner peripheral edge setting step and the outer peripheral edge setting step of the removal region in the third embodiment, and FIG. 11(B) is a cross-sectional view taken along line D-D of FIG. 11(A).

MODE FOR CARRYING OUT THE INVENTION

[0026] (First Embodiment) Referring to the accompanying drawings, an embodiment according to an aspect of the present invention will be described. FIG. 1 is a flowchart of a manufacturing method for manufacturing a plurality of device chips (i.e., chips) 61 (see FIG. 9) from a wafer (i.e., a first substrate) 11 (see FIG. 2(A) etc.).

[0027] In the first embodiment, the holding step S10, the removal area inner periphery setting step S20, the removal area outer periphery setting step S30, the separation step S40, the protruding part peeling step S50, and the division step S60 are performed in this order. However, the removal area inner periphery setting step S20 and the removal area outer periphery setting step S30 may be performed in either order.

[0028] The flowchart shown in Figure 1 includes a manufacturing method for producing a thinned wafer 51 by separating a portion of the thin-walled portion 23 of the wafer 11 (see Figure 2(C), etc.) as a thinned wafer (i.e., a second substrate) 51 (see Figure 6(B), etc.), and a setting method for setting a removal region 41 (see Figure 4(B), Figure 5(A), etc.) on the wafer 11.

[0029] Before explaining each step in Figure 1, we will refer to Figures 2(A) to 2(C) to describe the wafer 11 to be processed. Figure 2(A) is a perspective view of the front surface 11a of the wafer 11, Figure 2(B) is a perspective view of the back surface (i.e., one side) 11b of the wafer 11, and Figure 2(C) is a cross-sectional view of AA in Figure 2(B).

[0030] The wafer 11 has a disc-shaped silicon single crystal substrate. In this embodiment, the thickness of the wafer 11 (i.e., the thickness of the protrusion 21 described later) is approximately 775 μm, and the diameter of the wafer 11 is approximately 300 mm. However, the values ​​for thickness and diameter are examples only and are not necessarily limited to this example.

[0031] Furthermore, the single-crystal substrate constituting the wafer 11 is not limited to silicon, but may be formed from a single-crystal substrate of a compound semiconductor such as silicon carbide (SiC) or gallium nitride (GaN), or from other materials.

[0032] As shown in Figure 2(A), multiple division lines (i.e., streets) 13 are arranged in a grid pattern on the surface 11a side of the wafer 11. In Figure 2(A), for the sake of clarity, the extensions of two mutually orthogonal division lines 13 are shown as dashed lines as a representative example.

[0033] Each rectangular region demarcated by multiple division lines 13 has a device 15, such as an IC (Integrated Circuit), formed within it. The multiple devices 15 are located in the central part of the wafer 11 in the radial direction 47 (see Figure 4(A), etc.). There are no restrictions on the type, quantity, shape, structure, size, or arrangement of the multiple devices 15.

[0034] In this specification, a circular region on surface 11a that encloses multiple devices 15 is referred to as the device region 17, and an annular region of surface 11a located outside the device region 17 in the radial direction 47 of the wafer 11 is referred to as the outer peripheral surplus region 19.

[0035] The device region 17 shown in Figure 2(A) is a circular region concentric with the wafer 11. In Figure 2(A), the outline of the device region 17 is shown with a dashed line, but the actual wafer 11 does not show the outline of the device region 17. For the sake of explanation, the outline of the device region 17 is also shown with a dashed line in Figure 2(B).

[0036] Although the wafers 11 in Figures 2(A) and 2(B) do not show notches indicating crystal orientation, actual wafers 11 have notches formed on them. Depending on the size of the wafer 11, an orientation flat may be formed on the wafer 11 instead of a notch.

[0037] As shown in Figures 2(B) and 2(C), the wafer 11 has an annular projection 21 and a disc-shaped thin-walled portion 23. The projection 21 is formed along the outer peripheral edge 11c of the wafer 11, and the thin-walled portion 23 is surrounded on its outside by the projection 21 in the radial direction 47 of the wafer 11.

[0038] In this embodiment, the thickness of the protruding portion 21 is 775 μm, while the thickness of the thin-walled portion 23 is 100 μm. However, for the sake of readability in the drawings, the thickness of the thin-walled portion 23 is shown as thicker than its actual thickness. The width of the protruding portion 21 in the radial direction 47 of the wafer 11 is, for example, 2.6 mm.

[0039] On the back surface 11b side of the wafer 11, there is a disc-shaped recess defined by a protruding portion 21 and a thin-walled portion 23. This wafer 11 having the recess is formed, for example, by applying a process called TAIKO (registered trademark) to a wafer that conforms to a predetermined standard such as SEMI (Semiconductor Equipment and Materials International) M1.

[0040] As shown in Figure 2(C), a metal layer 25 is provided over almost the entire back surface 11b of the wafer 11. The metal layer 25 is provided on the back surface 11b of the protrusion 21 (i.e., the outer annular region of the back surface 11b), the inner peripheral wall of the protrusion 21 (i.e., the cylindrical side region), and the back surface 11b of the thin-walled portion 23 (i.e., the central circular region of the back surface 11b), and is continuous in all its respective areas.

[0041] The metal layer 25 is thin enough not to completely fill the disc-shaped recess and has a substantially uniform thickness. For example, in the region of the back surface 11b excluding the bevel portion, the metal layer 25 has a thickness of approximately 20 μm.

[0042] The metal layer 25 has a three-layer structure, for example, consisting of a titanium (Ti) layer, a nickel (Ni) layer, and a silver (Ag) layer, with the titanium layer in contact with the silicon single crystal substrate and the silver layer exposed on the outermost surface. However, the structure of the metal layer 25 is not limited to a three-layer structure. The metal layer 25 may consist of a single layer, or two or more layers made of different materials.

[0043] As shown in Figure 2(C), when the inner circumferential wall of the protruding portion 21 and the back surface 11b of the thin-walled portion 23 are substantially perpendicular, the position of the outermost surface of the metal layer 25 provided on the inner circumferential wall of the protruding portion 21 defines the boundary 27 between the protruding portion 21 and the thin-walled portion 23.

[0044] The connection area between the inner circumferential wall of the protruding portion 21 and the back surface 11b of the thin-walled portion 23 is not limited to a right angle in the cross-sectional view shown in Figure 2(C), but may consist of a smooth curve, or it may consist of a stepped shape where the wafer 11 gradually thins out as it moves inward in the radial direction 47.

[0045] If the shape is a smooth curve or a stepped shape, the boundary 27 is, for example, the thinnest part of the connection region (i.e., the position that is the thickness of the thin-walled portion 23), but more preferably the boundary 27 is the outermost surface of the metal layer 25 provided on the inner circumferential wall of the protruding portion 21.

[0046] When performing laser processing or other processing on such a wafer 11, first, the central part of a circular protective tape (i.e., protective member) 31 made of resin is attached to the back surface 11b of the wafer 11, and a metal ring frame 33 is attached to the outer circumference of the protective tape 31 to form a wafer unit 35 (see Figure 3).

[0047] The protective tape 31 is attached to the wafer 11 following the contours of the recesses and is fixed to the back surface 11b of the protruding portion 21 and the thin-walled portion 23, as well as the inner peripheral wall of the protruding portion 21. In this way, the protective tape 31 is fixed to almost the entire back surface 11b of the wafer 11.

[0048] The protective tape 31 has, for example, a laminated structure of an adhesive layer and a base layer. The adhesive layer has an epoxy, acrylic, or rubber-based adhesive. The protective tape 31 is fixed to the wafer 11 and ring frame 33 by pressing the adhesive layer of the protective tape 31 against the wafer 11 and ring frame 33.

[0049] In this embodiment, the adhesive layer uses an ultraviolet-curing epoxy resin or acrylic resin that hardens with ultraviolet light. However, the material of the adhesive is not limited to this, as long as the adhesive strength can be partially reduced by light, heat, pressure, etc. The base layer is formed of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate.

[0050] The wafer 11 is processed in the form of a wafer unit 35. In this embodiment, the holding process S10 to the protruding portion peeling process S50 are performed using a laser processing apparatus 2 (see Figure 3). The laser processing apparatus 2 will now be described with reference to Figure 3, etc.

[0051] Note that the Z-axis shown in Figure 3 and subsequent drawings is approximately parallel to the vertical and vertical directions. The laser processing apparatus 2 has a disc-shaped holding plate 4. The outer diameter of the holding plate 4 is smaller than the outer diameter of the recess in the wafer 11 and larger than the outer diameter of the device region 17.

[0052] As shown in Figure 3, in this embodiment, the holding surface 4a of the holding plate 4 is exposed downwards. The holding plate 4 is a so-called chuck table that holds the wafer unit 35 by suction at its bottom surface. The holding plate 4 has a disc-shaped frame made of a non-porous metal or the like.

[0053] A recess (not shown) is provided at the bottom of the frame, and a porous body made of porous ceramics or the like is fixed to this recess. The bottom surfaces of the frame and the porous body are flush, forming a substantially flat holding surface 4a. When negative pressure is transmitted to the bottom surface of the porous body from a suction source (not shown), such as a vacuum pump, the wafer 11 is held in place by suction on the holding surface 4a.

[0054] The bottom of a cylindrical rotating shaft 6 is fixed to the top surface of the retaining plate 4. The rotating shaft 6 is, for example, the rotor of a motor and, together with a stator (not shown), constitutes a motor. However, the rotating shaft 6 may also be a shaft to which a driven pulley is fixed instead of a rotor. In this case, the rotating shaft 6 rotates as power from the motor is transmitted via the drive pulley and an endless belt.

[0055] A clamp unit 8 is provided on the side of the retaining plate 4. The clamp unit 8 has an elongated, thin plate-shaped support member 8a that supports the ring frame 33 from below, and an elongated, thin plate-shaped pressing member 8b that presses down on the ring frame 33 from above.

[0056] The support member 8a and the pressing member 8b each extend along a predetermined direction perpendicular to the Z-axis (i.e., the direction perpendicular to the plane of the paper in Figure 3). The pressing member 8b is fixed to the retaining plate 4, and the support member 8a is movable along the Z-axis by an actuator (not shown), and can move closer to and further away from the pressing member 8b.

[0057] The position of the ring frame 33 relative to the retaining plate 4 is fixed by sandwiching the ring frame 33 between the upper and lower plates. Below the retaining plate 4, a camera unit 10 is provided. The camera unit 10 includes an objective lens whose optical axis is aligned with the Z-axis, and an image sensor such as a CCD (Charge-Coupled Device) image sensor.

[0058] The camera unit 10 images the wafer 11, with its surface 11a exposed facing downwards, from a position below the holding surface 4a, for example, using visible light. The image of the wafer 11 obtained by imaging is used for setting the removal area 41, aligning the wafer 11 during laser processing, etc., as described later.

[0059] Although not shown in Figure 3, a laser beam irradiation unit 12 (see Figure 6(A)) is provided below the holding surface 4a and near the outer periphery of the holding surface 4a. The laser beam irradiation unit 12 has a laser oscillator (not shown).

[0060] A laser oscillator comprises a laser medium such as an Nd:YAG crystal, an optical resonator, a Q-switch, etc. When excitation light is shone onto the laser medium from an excitation light source such as a flash lamp or laser diode, the laser oscillator emits a pulsed laser beam due to the action of the optical resonator, Q-switch, etc.

[0061] A pulsed laser beam emitted from a laser oscillator is converted to a wavelength (e.g., 355 nm) that is absorbed by the wafer 11 using a nonlinear optical crystal (not shown). The pulsed laser beam L, whose wavelength has been converted, is irradiated onto the wafer 11 from the aperture 14a of the concentrator 14 and is focused to approximately a single point on the wafer 11 by a focusing lens (not shown) provided inside the concentrator 14.

[0062] The optical axis 14b of the light condenser 14 and the light condenser lens is tilted obliquely with respect to the Z axis such that the aperture 14a faces the center of the holding surface 4a. Specifically, the light condenser 14 and the optical axis 14b are tilted such that the optical axis 14b is contained within a virtual plane that includes the axis 6a of the rotation axis 6 and is perpendicular to the holding surface 4a.

[0063] By tilting the light concentrator 14 in this way, the laser beam L reflected from the wafer 11 returns to the light concentrator 14, preventing the operation of the laser beam irradiation unit 12 from becoming unstable.

[0064] The tilt of the light concentrator 14 is not limited to the example shown in Figure 6(A). The light concentrator 14 may be tilted so that the incident surface of the laser beam L includes the axis 6a of the rotation axis 6 and is perpendicular to a virtual plane that is perpendicular to the holding surface 4a.

[0065] Although not shown in Figures 3 and 6(A), as shown in Figure 7(A), a pair of peeling units 18 are provided on the side of the holding surface 4a. Each peeling unit 18 has a support bar 18a that extends along a predetermined direction perpendicular to the Z-axis (i.e., the direction perpendicular to the plane of the paper in Figure 7(A)).

[0066] The support bar 18a is configured to be movable toward and toward the rotation shaft 6 by an actuator such as a motor or air cylinder. Two cylindrical bodies 18b are fixed to the top surface of the support bar 18a.

[0067] The two cylindrical bodies 18b are fixed to the support bar 18a in such a manner that they are separated by a predetermined distance in the predetermined direction perpendicular to the Z-axis. A thin disc (i.e., a release member) 18c is fixed to the top surface of the cylindrical body 18b so as to be rotatable relative to the cylindrical body 18b.

[0068] The axis of rotation of the disc 18c is approximately parallel to the Z-axis. The disc 18c is inserted between the protective tape 31 and the protrusion 21 of the wafer 11 in order to peel off the protrusion 21 after the adhesive strength of the protective tape 31 decreases in the annular region of the back surface 11b corresponding to the protrusion 21.

[0069] Above one of the peeling units 18, an ultraviolet irradiation device (not shown) is provided that irradiates ultraviolet light downward. The ultraviolet irradiation device includes a UV (ultraviolet) lamp, a UV-LED (Light Emitting Diode), etc., and irradiates ultraviolet light from a position above the holding surface 4a to the area outside the holding surface 4a in the radial direction of the holding plate 4.

[0070] Incidentally, the laser processing device 2 is equipped with a touch panel display (not shown). The touch panel display functions as an input device for the operator to input instructions to the laser processing device 2, and also as a display device for displaying images captured by the camera unit 10, a GUI (Graphical User Interface), etc.

[0071] Alternatively, instead of a touch panel display, a display device without input functionality may be provided on the laser processing device 2. However, in this case, a separate input device (keyboard, mouse, trackball, touchpad, digitizer, etc.) for the operator to input instructions to the laser processing device 2 will be provided.

[0072] The transmission of negative pressure from the suction source to the holding surface 4a, the clamp unit 8, the rotating shaft 6, the camera unit 10, the laser beam irradiation unit 12, the peeling unit 18, the ultraviolet irradiation device, the touch panel display, etc., are controlled by the controller (not shown) of the laser processing device 2.

[0073] A controller is composed of a computer that includes, for example, a processor represented by a CPU (Central Processing Unit), main memory such as DRAM (Dynamic Random Access Memory), and auxiliary storage such as flash memory, hard disk drives, and solid-state drives.

[0074] The auxiliary storage device stores software containing a predetermined program. The controller's functions are realized by operating the processor and other components according to this software. Next, referring to Figures 3 to 7(B) in order, the holding process S10 to the protruding part peeling process S50 in the laser processing apparatus 2 will be explained.

[0075] Figure 3 is a partial cross-sectional side view showing the holding process S10. In the holding process S10, with the support member 8a separated downward from the pressing member 8b, the wafer unit 35 is transported to the vicinity of the holding plate 4 by a transport unit (not shown), and the back surface 11b of the wafer 11 and the holding surface 4a are brought close together via the protective tape 31 so that the wafer 11 covers the holding surface 4a.

[0076] Then, by transmitting negative pressure to the holding surface 4a, the wafer 11 is held by suction at the holding surface 4a, and by raising the support member 8a, the ring frame 33 is clamped by the clamp unit 8. In this way, the wafer 11 is fixed to the holding plate 4.

[0077] After the holding process S10, the camera unit 10 is used to set the removal area 41 to be removed by ablation. Figure 4(A) shows the removal area peripheral setting process S20. Note that Figure 4(A) shows a plan view of the wafer 11 as seen from below by the camera unit 10.

[0078] The X and Y axes are perpendicular to the Z axis, and the XY plane is approximately parallel to the horizontal plane. Also, in Figure 4(A), for the sake of explanation, the diameter of the wafer 11 parallel to the X axis and the diameter of the wafer 11 parallel to the Y axis are shown on the surface 11a with dashed lines.

[0079] In the removal area peripheral setting step S20, first, the coordinates of the center 11d of the surface 11a of the wafer 11 are calculated. To calculate the coordinates of the center 11d, for example, images of three different locations on the outer periphery of the surface 11a are acquired by alternately imaging the outer periphery of the surface 11a with the camera unit 10 and rotating the rotation axis 6.

[0080] Subsequently, through image processing such as binarization, the coordinates of one point on the outer edge 11c of the surface 11a are obtained in each image, and the coordinates of the center of the circle (i.e., the center 11d) are calculated using the coordinates of three points on the outer edge 11c. Image acquisition, image processing, and coordinate calculation are performed automatically by the controller.

[0081] The origin of the XY coordinate system is, for example, the center of the holding surface 4a, but is not limited to this. The controller may recognize any point on the XY plane that does not change position within the laser processing apparatus 2 as the origin of the XY coordinate system.

[0082] After obtaining the coordinates of the center 11d, the operator sets, via a touch panel display, which region from the center 11d in the radial direction 47 of the wafer 11 (see arrow in Figure 4(A)) will be considered the outer diameter of the thinned wafer 51.

[0083] The outer shape of the thinned wafer 51 is, for example, circular, and the outer diameter of the thinned wafer 51 is set to be larger by a predetermined length (for example, 1 mm, 2 mm, etc.) than the circle inscribed in the outermost device 15.

[0084] In this way, the inner peripheral edge 43 of the removal region 41 that defines the outer shape of the thinned wafer 51 of a predetermined size is set to the thin-walled portion 23 located inside the outer peripheral edge 4b ​​of the holding surface 4a. In this embodiment, the removal region outer peripheral edge setting step S30 is performed following the removal region inner peripheral edge setting step S20.

[0085] Figure 4(B) shows the removal area outer edge setting step S30. The X and Y axes in Figure 4(B) are the same as in Figure 4(A). In the removal area outer edge setting step S30, the outer edge 45 of the removal area 41 is set on the wafer 11 such that, in the radial direction 47 of the wafer 11, the outer edge 45 of the removal area 41 is located at the midpoint 49 between the inner edge 43 of the removal area 41 and the outer edge 4b ​​of the holding surface 4a, or is located outside the midpoint 49.

[0086] In this embodiment, since the inner peripheral edge 43 of the removal region 41 and the boundary 27 are both circles, in Figure 4(B), the set of their midpoints 49 in the radial direction 47 of the wafer 11 is shown by a dashed line for convenience.

[0087] In the example shown in Figure 4(B), the outer edge 45 of the removal region 41 is set to a position corresponding to the outer edge 4b ​​of the retaining surface 4a. The position corresponding to the outer edge 4b ​​is, for example, the exact same position as the outer edge 4b ​​in the XY plane.

[0088] For example, the operator sets, via a touch panel display, the position in micrometers from the inner edge 43 in the radial direction 47 of the wafer 11 to determine what constitutes the outer edge 45, in increments of 1 μm, based on the distance from the inner edge 43.

[0089] However, the outer edge 4b ​​may be located within a range from a position (start position) that is x% of the radius of the wafer 11 inward from the outer edge 4b ​​in the radial direction 47 of the wafer 11, to a position (end position) that is x% of the radius of the wafer 11 outward from the outer edge 4b ​​in the radial direction 47 of the wafer 11 (x is any positive real number).

[0090] In addition, in the removal area outer edge setting step S30, the outer edge 45 may be set by the distance from the center 11d in the radial direction 47 of the wafer 11 instead of the distance from the inner edge 43, or by the distance from the boundary 27 of the protruding portion 21 and the thin-walled portion 23.

[0091] For example, if the radius of wafer 11 is 150 mm, the radius of the inner peripheral edge 43 (i.e., the radius of the device region 17) is 145.6 mm, and the radii of the outer peripheral edge 4b ​​and outer peripheral edge 45 of the holding surface 4a are 146 mm each. In other words, the width of the removal region 41 in the radial direction 47 of wafer 11 is 0.4 mm (i.e., 400 μm).

[0092] Figure 5(A) is a plan view of wafer 11 showing the removal region 41 after the removal region inner edge setting process S20 and the removal region outer edge setting process S30. For ease of explanation, the removal region 41 is shaded. Figure 5(B) is a cross-sectional view of BB in Figure 5(A).

[0093] In this embodiment, the removal area 41 is highlighted on the touch panel display as shown in Figure 5(A). Furthermore, if there is an error, for example, if the outer edge 45 is set closer to the center 11d than the inner edge 43, an error warning is displayed. This allows the operator to easily notice any setting errors, thereby preventing processing defects caused by human error.

[0094] After the removal area inner edge setting step S20 and the removal area outer edge setting step S30, a separation step S40 is performed to remove the removal area 41 in the thickness direction 11e of the wafer 11 by ablation. Figure 6(A) is a partial cross-sectional side view showing an example at the start of the separation step S40, and Figure 6(B) is a partial cross-sectional side view showing an example at the end of the separation step S40.

[0095] In separation step S40, for example, the wafer 11 is rotated at a predetermined speed while the light concentrator 14 is moved at a predetermined speed to the radially outer side of the holding surface 4a. An example of the processing conditions in separation step S40 is shown below.

[0096] Laser beam wavelength: 355nm Repetition frequency: 200kHz Average output: 2.0W Focusing spot diameter: 20 μm Rotation speed of the holding plate: 120 rpm Focuser movement speed: 0.1 mm / s

[0097] By dividing the wafer 11 into a thinned wafer 51 located directly beneath the holding surface 4a and an annular thin portion 23 and a protruding portion 21 remaining on the outside of the holding surface 4a in the radial direction of the holding surface 4a, the thinned wafer 51, which is part of the thin portion 23, can be separated from the wafer 11.

[0098] In this embodiment, in the removal area outer edge setting step S30, compared to the case where the outer edge 45 of the removal area 41 is located inside the midpoint 49 in the radial direction 47 of the wafer 11, the area of ​​the thin-walled portion 23 that remains integrally with the protruding portion 21 after the separation step S40 is reduced in a plan view of the wafer 11. Therefore, the possibility of cracking occurring at the boundary 27 and the thin-walled portion 23 separated from the thinned wafer 51 remaining on the protective tape 31 is reduced.

[0099] Following the separation process S40, a protrusion peeling process S50 is performed to peel off the protrusions 21 located on the outside of the thinned wafer 51, and the annular thin-walled portion 23 between the outer peripheral edge 45 of the removal region 41 and the protrusions 21, from the protective tape 31. Figure 7(A) is a partial cross-sectional side view showing the start of the protrusion peeling process S50.

[0100] In the protruding portion peeling process S50, first, ultraviolet light is irradiated through the protective tape 31 to the annular region of the protective tape 31 that is in contact with the back surface 11b of the protruding portion 21, thereby reducing the adhesive strength of the adhesive layer. However, since ultraviolet light is blocked from the region of the protective tape 31 that is in contact with the thinned wafer 51 and the ring frame 33, the adhesive strength in this region is maintained.

[0101] Next, the peeling units 18 are brought closer together, and the disc 18c is inserted between the protective tape 31 and the annular region corresponding to the back surface 11b of the protrusion 21. The hardened adhesive layer is broken by the disc 18c or peeled off from the protrusion 21. This releases the fixation of the protective tape 31 to the thin portion 23 between the outer peripheral edge 45 of the removal region 41 and the protrusion 21, and to the protrusion 21.

[0102] In other words, the thin-walled portion 23 and the protruding portion 21 move relative to the thinned wafer 51 which is stationary on the holding surface 4a (i.e., a part of the thin-walled portion 23 and the protruding portion 21 fall off). Figure 7(B) is a partial cross-sectional side view showing the annular thin-walled portion 23 and the protruding portion 21 falling together in the protruding portion peeling process S50.

[0103] Here, we will explain the advantages of setting the removal region 41 as described above. Figure 8 is a partial cross-sectional side view showing the protruding portion peeling process S50 in the related technology. In the example shown in Figure 8, instead of making the removal region 41 sufficiently larger in width than the diameter of the focal point of the laser beam L, a laser-processed groove 71 having approximately the same width as the diameter of the focal point of the laser beam L is formed on the wafer 11.

[0104] In other words, in the related technology shown in Figure 8, without setting the inner peripheral edge setting step S20 and the outer peripheral edge setting step S30 of the removal area as described above, the holding plate 4 is rotated while the position of the focal point of the laser beam L is fixed to a single point on the outer peripheral edge of the thinned wafer 51 (i.e., the inner peripheral edge 43 of the removal area 41 described above).

[0105] In this case, an extremely fine laser-processed groove 71 having a width approximately the same as the diameter of the focusing point (for example, 20 μm) is formed on the wafer 11. When such a fine groove is formed, in a plan view of the wafer 11, the area of ​​the region where the thin-walled portion 23 remains in the annular region between the outer edge 4b ​​of the holding surface 4a and the outer edge of the thinned wafer 51 is larger than the area of ​​the region in the same annular region where the thin-walled portion 23 does not remain.

[0106] As a result, in the protruding portion peeling process S50, when the disc 18c of the peeling unit 18 is inserted between the protruding portion 21 and the protective tape 31, a downward force acts on the protruding portion 21, and an upward force is applied to the inner circumference 47a of the remaining thin-walled portion 23, so that the inner circumference 47a is pressed against the holding surface 4a.

[0107] The inner circumference 47a of the remaining thin-walled portion 23 is weak due to its thinness, and therefore cracks and generates fragments during the protruding portion peeling process S50. Some of these fragments remain on the protective tape 31.

[0108] Furthermore, not only in the case of a laser-processed groove 71 having approximately the same width as the focusing point, but also in cases where a relatively large amount of remaining thin-walled portion 23 remains in the region between the outer peripheral edge 4b ​​of the holding surface 4a and the inner peripheral edge 43 of the removal region 41, the broken thin-walled portion 23 tends to remain on the protective tape 31 during the protruding portion peeling process S50.

[0109] If the thin portion 23 separated from the thinned wafer 51 remains on the protective tape 31 after the protruding portion peeling process S50, an additional removal process will be required to remove the remaining thin portion 23 from the protective tape 31, which will reduce productivity.

[0110] In contrast, in this embodiment, since the outer peripheral edge 4b ​​of the holding surface 4a is the outer peripheral edge 45 of the removal region 41, the inner peripheral portion 47a of the thin-walled portion 23 that receives force from the holding surface 4a in the protruding portion peeling process S50 becomes substantially zero. Therefore, the possibility that the thin-walled portion 23 remains on the protective tape 31 together with the thinned wafer 51 can be suppressed.

[0111] When prioritizing UPH (units per hour) in the separation process S40, it is useful to form a thin laser-processed groove 71 as shown in Figure 8. However, as mentioned above, it has been found that productivity may decrease because the thin-walled portion 23 remains on the protective tape 31 together with the thinned wafer 51.

[0112] In this embodiment shown in Figures 1 to 7, the reduction in productivity caused by the thin-walled portion 23 remaining on the protective tape 31 together with the thinned wafer 51 is resolved. Focusing only on the separation process S40, the UPH may be lower than that of the method described in the related technology shown in Figure 8. However, considering the entire production process in which a large number of wafers 11 are thinned wafers 51, the UPH of this embodiment may be improved compared to the related technology shown in Figure 8.

[0113] By the way, in this embodiment, after the protruding portion peeling step S50, the thinned wafer 51 is transported to the dicing apparatus 20 (see Figure 9) and the thinned wafer 51 is divided into multiple device chips 61 (dividing step S60). First, the dicing apparatus 20 will be described with reference to Figure 9.

[0114] The dicing apparatus 20 of this embodiment is a cutting apparatus that cuts a thinned wafer 51 along a planned division line 13 using a cutting blade 38 mounted on a spindle 32. However, the dicing apparatus 20 is not limited to a cutting apparatus.

[0115] The dicing apparatus 20 may also be a laser processing apparatus that ablates the thinned wafer 51 by irradiating it along the division line 13 with a pulsed laser beam having a wavelength absorbed by the thinned wafer 51.

[0116] The dicing apparatus 20 of this embodiment has a disc-shaped chuck table 22. The structure of the chuck table 22 is substantially the same as that of the holding plate 4 described above. However, the holding surface 22a of the chuck table 22 faces upward.

[0117] Multiple (typically four) clamp units 24 are provided on the side of the chuck table 22 at approximately equal intervals around the circumferential direction of the chuck table 22. Each clamp unit 24 has a base portion 24a that supports the ring frame 33 from below and a claw portion 24b that presses down on the ring frame 33 from above.

[0118] The upper end of the rotating shaft 26 is fixed to the lower surface of the chuck table 22. The axis of the rotating shaft 26 is positioned approximately parallel to the Z-axis. The rotating shaft 26 is, for example, the rotor of a motor and, together with a stator (not shown), constitutes a motor.

[0119] However, the rotating shaft 26 may be a shaft to which a driven pulley is fixed instead of a rotor. In this case, the rotating shaft 26 rotates as power from the motor is transmitted via the drive pulley and an endless belt.

[0120] The chuck table 22 and the rotary shaft 26 are supported by a single movable plate (not shown). This movable plate is movable along the X-axis by an X-axis movement mechanism (not shown) having a ball screw and a servo motor. The X-axis movement mechanism is used, for example, for machining feed.

[0121] A cutting unit 30 is provided above the holding surface 22a. The cutting unit 30 has a cylindrical spindle 32 whose longitudinal direction is aligned with the Y-axis. The tip of the spindle 32 protrudes outside the spindle housing (not shown).

[0122] The rest of the spindle 32 is housed in the spindle housing. The spindle 32 is held in the spindle housing in a manner that allows it to rotate by hydrostatic air bearings (i.e., air bearings).

[0123] The spindle 32 corresponds to the rotor that makes up the motor, and the stator that makes up the motor is provided inside the spindle housing. A mount 34 is fixed to the tip of the spindle 32. By fixing the retaining flange portion 36 to the mount 34, the annular cutting blade 38 is clamped between the mount 34 and the retaining flange portion 36.

[0124] In this manner, the cutting blade 38 mounted on the tip of the spindle 32 rotates in conjunction with the rotation of the spindle 32. A cutting fluid supply nozzle (not shown) is provided at the tip of the spindle housing in a manner that does not interfere with the cutting blade 38, and supplies cutting fluid such as pure water to the cutting blade 38.

[0125] A camera unit (not shown) is fixed to the cutting unit 30. The camera unit is positioned above the holding surface 22a and captures images of the wafer 11 held by suction on the holding surface 22a, for example, using visible light. The images obtained from the capture are used for aligning the cutting blade 38 with respect to the planned division line 13, kerf checks, etc.

[0126] The cutting unit 30 is movable along the Y-axis and Z-axis by a Y-axis movement mechanism and a Z-axis movement mechanism (not shown) having a ball screw and a servo motor, respectively. The Y-axis movement mechanism performs, for example, indexing feed of the cutting blade 38, and the Z-axis movement mechanism performs, for example, adjustment of the amount of cutting depth of the cutting blade 38 into the thinned wafer 51.

[0127] The transmission of negative pressure from the suction source to the holding surface 22a, the clamp unit 24, the rotating shaft 26, the X-axis movement mechanism, the cutting unit 30, the Y-axis movement mechanism, the Z-axis movement mechanism, etc., are controlled by a controller (not shown) of the dicing device 20.

[0128] A controller is composed of a computer that includes, for example, a processor (such as a CPU), main memory such as DRAM, and auxiliary memory such as flash memory. Software containing predetermined programs is stored in the auxiliary memory. The controller's functions are realized by operating the processor and other components according to this software.

[0129] Figure 9 is a partial cross-sectional side view showing the splitting process S60. In the splitting process S60, first, the wafer unit 35 from which the protruding portion 21 and the thinned portion 23 on the outer periphery have been removed is transported to the chuck table 22 by a transport unit (not shown), and the thinned wafer 51 is held by suction on the holding surface 22a via the protective tape 31, while the ring frame 33 is clamped by the clamp unit 24.

[0130] Next, the position of the lower end of the rapidly rotating cutting blade 38 is adjusted between the back surface 11b and the holding surface 22a. Then, while supplying cutting fluid to the cutting blade 38, the chuck table 22 is moved along the X-axis relative to the cutting blade 38 so that the cutting blade 38 passes through the planned division line 13 (i.e., machining feed is performed).

[0131] In this manner, after cutting one planned division line 13 to cut the thinned wafer 51, the cutting unit 30 is moved along the Y-axis by a predetermined indexing feed amount (i.e., the distance between adjacent planned division lines 13). Then, another planned division line 13 is cut in the same manner to cut the thinned wafer 51.

[0132] After cutting all the planned division lines 13 along one direction to cut the thinned wafer 51, the chuck table 22 is rotated 90 degrees, and similarly, all the remaining planned division lines 13 are cut to cut the thinned wafer 51. This divides the thinned wafer 51 into multiple device chips 61.

[0133] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 10(A) and 10(B). In the second embodiment, the removal area outer edge setting step S30 is performed in the same way as in the first embodiment, but in the second embodiment, the position of the outer edge 45 is different from that of the first embodiment.

[0134] Figure 10(A) is a plan view of wafer 11 showing the removal area inner edge setting step S20 and the removal area outer edge setting step S30 in the second embodiment, and Figure 10(B) is a cross-sectional view of CC of Figure 10(A). In the second embodiment, the outer edge 45 of the removal area 41 is located between the midpoint 49 and the outer edge 4b ​​of the holding surface 4a, rather than being located at the outer edge 4b ​​of the holding surface 4a.

[0135] In this embodiment as well, in the removal area outer edge setting step S30, compared to the case where the outer edge 45 of the removal area 41 is located inside the midpoint 49 in the radial direction 47 of the wafer 11, the area of ​​the thin-walled portion 23 that remains integrally with the protruding portion 21 after the separation step S40 is reduced in a plan view of the wafer 11. Therefore, the possibility of cracking occurring at the boundary 27 and the thin-walled portion 23 separated from the thinned wafer 51 remaining on the protective tape 31 can be further reduced.

[0136] In the separation step S40, the removal area 41 is removed by ablation, separating the wafer 11 into a protruding portion 21 having a thin-walled portion 23 on its inner circumference and a thinned wafer 51. Then, in the protruding portion peeling step S50, the protruding portion 21 having a thin-walled portion 23 on its inner circumference is peeled off from the protective tape 31.

[0137] (Experimental Example) Table 1 below shows the experimental results when, in the radial direction 47 of the wafer 11, the inner edge 43 and outer edge 45 of the removal region 41 are inside the outer edge 4b ​​of the holding surface 4a, and the width of the annular region from the inner edge 43 of the removal region 41 (i.e., the outer edge of the device region 17) to the outer edge 4b ​​of the holding surface 4a is 0.40 mm, and the width of the annular region from the outer edge 45 of the removal region 41 to the boundary 27 is 1.40 mm.

[0138] In this experiment, after the holding step S10 and the removal area peripheral edge setting step S20 were performed on multiple wafers 11, the removal area 41 was set in the removal area peripheral edge setting step S30 so that the diameter of the peripheral edge 45 of the removal area 41 was different for each wafer, and then the separation step S40 and the protruding part peeling step S50 were performed sequentially.

[0139] In particular, the distance d from the outer edge 45 of the removal region 41 in the radial direction 47 of the wafer 11 to the outer edge 4b ​​of the holding surface 4a was varied from 0.05 mm to 0.38 mm. Since the spot diameter of the laser beam L used in the separation process S40 was 0.02 mm (i.e., the width of the removal region 41 was 0.02 mm), the maximum value of the distance d was set to 0.38 mm.

[0140] The smaller the distance d, the larger the area of ​​the removal region 41 becomes, and therefore the smaller the area of ​​the annular thin-walled portion 23 located on the outside of the thinned wafer 51. In other words, the smaller the distance d, the less likely the thin-walled portion 23 located on the outside of the thinned wafer 51 is to break in the protrusion peeling process S50, and therefore it is easier to peel off from the protective tape 31 together with the protrusion 21. As a result, fewer fragments of the broken thin-walled portion 23 remain on the protective tape 31.

[0141] [Table 1]

[0142] As shown in [Table 1], in experiments #1 to #3, no fragments of the thin-walled portion 23 remained on the protective tape 31 after the protruding portion peeling process S50. In contrast, in experiments #4 and #5, where the distance d exceeded 0.20 mm, fragments of the thin-walled portion 23 remained on the protective tape 31 after the protruding portion peeling process S50. When the distance d is 0.20 mm, the outer edge 45 of the removal area 41 is located at the midpoint 49 mentioned above.

[0143] Therefore, in the removal area outer edge setting step S30, it is preferable that the distance d is set to be 0.20 mm or less, inward from the outer edge 4b ​​of the holding surface 4a (i.e., the outer edge 45 of the removal area 41 is located at or outside the midpoint 49).

[0144] Note that the distance d may be zero. In the first embodiment described above, the outer edge 45 of the removal region 41 coincides with the outer edge 4b ​​of the retaining surface 4a, so the distance d is zero. However, by making the distance d a non-zero finite value, the removal region 41 can be made narrower compared to the case where the distance d is zero.

[0145] Therefore, compared to the case where the distance d is zero, the processing time in the separation process S40 can be shortened, and thus the UPH in the manufacturing of the thinned wafer 51 and the device chip 61 can be increased.

[0146] (Third Embodiment) Next, a third embodiment will be described with reference to Figures 11(A) and 11(B). Figure 11(A) is a plan view of the wafer showing the removal area inner edge setting step S20 and the removal area outer edge setting step S30 in the third embodiment, and Figure 11(B) is a DD cross-sectional view of Figure 11(A).

[0147] In the examples shown in Figures 11(A) and 11(B), the outer edge 45 of the removal region 41 is set to a boundary 27 located outside the outer edge 4b ​​of the holding surface 4a in the radial direction 47 of the wafer 11 (i.e., outside the midpoint 49).

[0148] In the third embodiment, the processing time in the separation step S40 is longer compared to the first and second embodiments, but, similar to the first and second embodiments, the possibility of cracks occurring at the boundary 27 and the thinned portion 23 separated from the thinned wafer 51 remaining on the protective tape 31 can be reduced.

[0149] Furthermore, if the outer edge 45 of the removal region 41 is located outside the outer edge 4b ​​of the holding surface 4a in the radial direction 47 of the wafer 11, the possibility of the thin-walled portion 23 separated from the thinned wafer 51 remaining on the protective tape 31 can be reduced, regardless of how large the distance d is.

[0150] Furthermore, the structures, methods, etc., according to the embodiments described above can be modified as appropriate without departing from the scope of the object of the present invention.

[0151] In the separation step S40, instead of making the movement trajectory of the focal point of the laser beam L spiral as described above, the movement trajectory of the focal point of the laser beam L may be made into multiple concentric circles of different diameters by alternately repeating the rotation of the holding plate 4 by approximately 360 degrees and the index feed that moves the light concentrator 14 by a predetermined amount radially outward from the holding surface 4a.

[0152] Furthermore, in the laser processing apparatus 2, the separation process S40 can also be performed by moving the focal point of the laser beam L using a galvanometer scanner (not shown) or the like, while keeping the holding plate 4 stationary without rotating it.

[0153] By the way, in the above embodiment, the wafer 11 was processed in the form of a wafer unit 35 in which the protective tape 31 is fixed to the back surface 11b of the wafer 11, but the wafer 11 may also be processed in the form in which the protective tape 31 is fixed to the front surface 11a of the wafer 11.

[0154] Even when fixing the protective tape 31 to the surface (i.e., one side) 11a of the wafer 11, the laser processing apparatus 2 described above can be used to perform the holding process S10 to the protruding part peeling process S50. However, before dividing the wafer 11 with the dicing apparatus 20, the protective tape 31 is replaced so that the surface 11a is exposed.

[0155] If the protective tape 31 is not replaced, a cutting device may be used that has the function of imaging the surface 11a with a camera unit from below the chuck table, through the chuck table, using a special chuck table that is partially made of a material that is substantially transparent to visible light.

[0156] Incidentally, the shape of the wafer 11 is not limited to a disc, but may be a thin plate having any shape such as a rectangular plate or an elliptical disc. In this case as well, the wafer 11 has a protrusion 21 formed along the outer peripheral edge 11c of the wafer 11, and a thin-walled portion 23 whose outside is surrounded by the protrusion 21 in a plan view of the wafer 11. [Explanation of symbols]

[0157] 2: Laser processing equipment 4: Holding plate, 4a: Holding surface, 4b: Outer periphery, 6: Rotating shaft, 6a: Axial center 8: Clamp unit, 8a: Support member, 8b: Pressing member 10: Camera Unit 11: Wafer (first substrate), 11a: Front surface, 11b: Back surface (one side), 11c: Outer edge 11d: center, 11e: thickness direction 12: Laser beam irradiation unit 13: Planned division line, 15: Device, 17: Device area, 19: Peripheral surplus area 14: Focuser, 14a: Aperture, 14b: Optical axis 18: Peeling unit, 18a: Support bar, 18b: Cylindrical body, 18c: Disc (peeling member) 20: Dicing device 21: Protruding part, 23: Thin wall part, 25: Metal layer 22: Chuck table, 22a: Holding surface 24: Clamp unit, 24a: Base part, 24b: Claw part 26: Rotation axis 27: Boundary 31: Protective tape (protective material), 33: Ring frame, 35: Wafer unit 30: Cutting Unit 32: Spindle, 34: Mount, 36: Retaining flange, 38: Cutting blade 41: Removal area, 43: Inner edge, 45: Outer edge 47: Radial direction, 47a: Inner circumference 49: Midpoint 51: Thinned wafer (second substrate) 61: Device chip (chip) 71: Laser-cut grooves d: distance L: Laser beam S10: Holding process, S20: Removal area inner edge setting process, S30: Removal area outer edge setting process S40: Separation process, S50: Protrusion peeling process, S60: Division process

Claims

1. A manufacturing method for producing a second substrate, comprising separating a portion of the thin-walled portion of a first substrate, which has a protrusion formed along its outer edge and a thin-walled portion whose outer side is surrounded by the protrusion, and which has a protective member fixed to one surface, as a second substrate, A holding step of holding the first substrate with the holding surface of the holding plate, A removal area inner edge setting step, in which the inner edge of the removal area that defines the outer shape of the second substrate is set in the thin-walled portion located inside the outer edge of the retaining surface, A removal area periphery setting step, which sets the periphery of the removal area on the first substrate such that, in the radial direction of the first substrate, the periphery of the removal area is located at or outside the midpoint of the inner periphery of the removal area and the periphery of the holding surface, A separation step of separating the second substrate from the first substrate by removing the removal area in the thickness direction of the first substrate, After the separation step, a protrusion peeling step is performed in which the protrusion and the second substrate are moved relative to each other to peel the protrusion, the outer edge of the removal area and the thin portion between the protrusion and the protective member, A manufacturing method characterized by comprising the following:

2. The manufacturing method according to claim 1, characterized in that, in the step of setting the outer edge of the removal area, the outer edge of the removal area is set to be inward from the outer edge of the retaining surface such that the distance between the outer edge of the removal area and the outer edge of the retaining surface in the radial direction is 0.20 mm or less.

3. The manufacturing method according to claim 2, characterized in that, in the step of setting the outer edge of the removal area, the outer edge of the removal area is set at a position corresponding to the outer edge of the retaining surface.

4. The manufacturing method according to claim 1, characterized in that, in the step of setting the outer edge of the removal area, the outer edge of the removal area is set to be outside the outer edge of the retaining surface in the radial direction.

5. The manufacturing method according to any one of claims 1 to 4, characterized in that in the protruding portion peeling step, a peeling member is inserted between the protective member and the region corresponding to one surface of the protruding portion, and the protruding portion, the outer peripheral edge of the removal region, and the thin portion between the protruding portion are peeled off from the protective member.

6. A manufacturing method for producing a plurality of chips from a first substrate having a protrusion formed along the outer edge and a thin-walled portion whose outside is surrounded by the protrusion, and having a protective member fixed to one surface, A holding step of holding the first substrate with the holding surface of the holding plate, A removal area inner edge setting step, in which the inner edge of a removal area defining the outer shape of a second substrate of a predetermined size is set in the thin-walled portion located inside the outer edge of the retaining surface, A removal area periphery setting step, which sets the periphery of the removal area on the first substrate such that, in the radial direction of the first substrate, the periphery of the removal area is located at or outside the midpoint of the inner periphery of the removal area and the periphery of the holding surface, A separation step of separating the second substrate from the first substrate by removing the removal area in the thickness direction of the first substrate, After the separation step, a protrusion peeling step is performed in which the protrusion and the second substrate are moved relative to each other to peel the protrusion, the outer edge of the removal area and the thin portion between the protrusion and the protective member, After the protruding portion peeling step, the second substrate is divided into the plurality of chips in a dividing step, A manufacturing method characterized by comprising the following:

7. A setting method for setting a removal area on a first substrate in order to separate a part of the thin-walled portion of a first substrate, which has a protrusion formed along its outer edge and a thin-walled portion whose outside is surrounded by the protrusion, and on which a protective member is fixed, as a second substrate, the first substrate having a protrusion formed along its outer edge and a thin-walled portion whose outside is surrounded by the protrusion, A holding step of holding the first substrate with the holding surface of the holding plate, A removal area inner edge setting step, in which the inner edge of the removal area that defines the outer shape of the second substrate is set in the thin-walled portion located inside the outer edge of the retaining surface, A removal area periphery setting step, which sets the periphery of the removal area on the first substrate such that, in the radial direction of the first substrate, the periphery of the removal area is located at or outside the midpoint of the inner periphery of the removal area and the periphery of the holding surface, A setting method characterized by comprising the following features.

Images