Processing method for bonded substrate

Abstract

To provide a processing method of a bonded substrate capable of reducing the occurrence of contamination without generating a division defect at the time of dividing the bonded substrate.SOLUTION: A processing method of a bonded substrate includes: a first laser beam irradiation step 1 of forming a modified layer and a crack extending from the modified layer and extending to a second substrate side across a bonding surface between a first substrate and the second substrate by irradiating the bonded substrate, in which the first substrate and the second substrate are bonded, along a division line with a focal point of a laser beam having a wavelength having transparency to the first substrate positioned inside the first substrate; a second laser beam irradiation step 2 of forming a division starting point by positioning a focal region of the laser beam having the wavelength having the transparency with respect to the second substrate inside the second substrate and irradiating the second substrate along the division line; and a division step 3 of dividing the bonded substrate along the division line by applying an external force.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for processing a bonded substrate. [Background technology]

[0002] In recent years, when manufacturing devices such as image sensors, a bonded substrate in which two semiconductor substrates on which devices are formed are bonded together, or a bonded substrate in which a semiconductor substrate and a glass substrate are bonded together, has been used (see Patent Document 1).

[0003] A known method for manufacturing devices from the above-described bonded substrates is to form division starting points inside both substrates by irradiating them with a laser beam along the division lines, and then apply an external force to break the substrate along the division lines and separate it into individual devices. In such a method, in order to suitably prevent division defects during division, it is preferable that the division starting points are formed up to the vicinity of the bonding surface between the substrates. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-221284 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the focal point of the laser beam is positioned near the bonding surface, leakage light from this laser beam may reach the bonding surface and ablate it, potentially generating processing debris known as contamination.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for processing a bonded substrate that can prevent the occurrence of separation defects when separating the bonded substrate and can reduce the occurrence of contamination. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the method for processing a bonded substrate of the present invention is a method for dividing a bonded substrate formed by bonding a first substrate and a second substrate along a predetermined division line, by positioning a focal point of a laser beam having a wavelength that is transparent to the first substrate inside the first substrate and irradiating the laser beam along the division line, thereby forming a modified layer along the division line inside the first substrate, and cracks that extend from the modified layer and extend across the bonding surface between the first substrate and the second substrate to the second substrate side. a second laser beam irradiation step of positioning a focusing region of a laser beam having a wavelength that is transparent to the second substrate inside the second substrate and irradiating the laser beam along the planned division line to form division starting points inside the second substrate along the planned division line; and a dividing step of applying an external force to the bonded substrate stack to divide the bonded substrate stack along the planned division line after carrying out the first laser beam irradiation step and the second laser beam irradiation step.

[0008] Furthermore, in the method for processing a bonded substrate of the present invention, in the second laser beam irradiation step, it is preferable that a focused area of ​​a laser beam having a wavelength that is transparent to the second substrate is positioned inside the second substrate and irradiated, thereby forming a shielded tunnel inside the second substrate that includes a pore and an altered portion surrounding the pore.

[0009] Furthermore, in the method for processing a bonded substrate of the present invention, in the second laser beam irradiation step, it is preferable to position the focusing area of ​​the laser beam at a depth that does not overlap with the crack formed in the first laser beam irradiation step.

[0010] In the method for processing a bonded substrate of the present invention, the first substrate is preferably a Si substrate, and the second substrate is preferably a glass substrate. [Effects of the Invention]

[0011] The present invention can prevent the occurrence of separation defects when separating bonded substrates, and can reduce the occurrence of contamination. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing a bonded substrate to be processed by a method for processing a bonded substrate according to an embodiment. [Figure 2] FIG. 2 is a flowchart showing the flow of the method for processing a bonded substrate according to the embodiment. [Figure 3] FIG. 3 is a side view, partly in section, showing one state of the first laser beam irradiation step shown in FIG. [Figure 4] FIG. 4 is an enlarged view showing the main part of FIG. [Figure 5] FIG. 5 is a side view, partly in section, showing one state of the second laser beam irradiation step shown in FIG. [Figure 6] FIG. 6 is an enlarged view showing the main part of FIG. [Figure 7] FIG. 7 is a perspective view schematically showing the structure of a shield tunnel. [Figure 8] 8 is a side view, partly in section, showing one state of the dividing step shown in FIG. 2. FIG. [Figure 9] FIG. 9 is a side view, partly in section, showing a state subsequent to FIG. [Figure 10] FIG. 10 is an enlarged side view, partly in section, showing a main part in one state of the first laser beam irradiation step according to the modified example. [Figure 11] FIG. 11 is a side view, partly in section, showing one state of the second laser beam irradiation step according to the modified example. [Figure 12] FIG. 12 is an enlarged view showing the main part of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0014] [Embodiment] A method for processing a bonded substrate 10 according to an embodiment of the present invention will be described with reference to the drawings.

[0015] (Bonded substrate 10) First, the structure of the bonded substrate 10, which is the target of processing by the method for processing a bonded substrate 10 according to an embodiment of the present invention, will be described. Fig. 1 is a perspective view showing the bonded substrate 10, which is the target of processing by the method for processing a bonded substrate 10 according to an embodiment. The bonded substrate 10 shown in Fig. 1 is a laminated substrate in which a first substrate 10-1 and a second substrate 10-2 are bonded together.

[0016] In the embodiment, the first substrate 10-1 is a Si substrate using Si (silicon) as the substrate 11, and is formed into a disk shape as a whole. In the embodiment, the thickness of the first substrate 10-1 from the front surface 12 to the back surface 15 of the substrate 11 is 650 μm. The front surface 12 side of the first substrate 10-1 is bonded to the second substrate 10-2. In other words, the front surface 12 of the first substrate 10-1 is a bonding surface 16 with the second substrate 10-2.

[0017] The first substrate 10-1 has a plurality of planned division lines 13 set in a grid pattern, and devices 14 formed on a surface 12 in areas partitioned by the intersecting planned division lines 13. The devices 14 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integrations), image sensors such as CCDs (Charge Coupled Devices) or CMOSs ​​(Complementary Metal Oxide Semiconductors), MEMS (Micro Electro Mechanical Systems), or memories (semiconductor memory devices).

[0018] In the embodiment, the second substrate 10-2 is a glass substrate using glass as the substrate 11, and is formed into a disk shape having the same overall diameter as the first substrate 10-1. In the embodiment, the thickness of the second substrate 10-2 from the front surface 12 to the back surface 15 is 700 μm. The front surface 12 side of the second substrate 10-2 is bonded to the first substrate 10-1. In other words, the front surface 12 of the second substrate 10-2 is the bonding surface 16 with the first substrate 10-1.

[0019] The bonding surfaces 16 of the first substrate 10-1 and the second substrate 10-2 are directly bonded without the use of an adhesive. Examples of bonding methods include anodic bonding, direct bonding, fusion bonding, and room-temperature bonding. With the first substrate 10-1 and the second substrate 10-2 bonded at the bonding surfaces 16, the bonded substrate 10 is divided into individual devices 14 along the planned division lines 13 by a processing method for the bonded substrate 10 according to an embodiment, and singulated into stacked chips 17 (see FIG. 9 ).

[0020] (Method for processing bonded substrate 10) Next, a method for processing a bonded substrate 10 according to an embodiment of the present invention will be described. Fig. 2 is a flowchart showing the flow of the method for processing a bonded substrate 10 according to the embodiment. The method for processing a bonded substrate 10 according to the embodiment is a method for dividing a bonded substrate 10, which is formed by bonding a first substrate 10-1 and a second substrate 10-2, along predetermined dividing lines 13. The method for processing a bonded substrate 10 includes a first laser beam irradiation step 1, a second laser beam irradiation step 2, and a dividing step 3.

[0021] <First laser beam irradiation step 1> Fig. 3 is a side view, partially in cross section, showing one state of the first laser beam irradiation step 1 shown in Fig. 2. Fig. 4 is an enlarged view showing the main part of Fig. 3. The first laser beam irradiation step 1 is a step for forming a modified layer 20 along the planned division line 13 inside the first substrate 10-1, and a crack 21 extending from the modified layer 20 and straddling the bonding surface 16 between the first substrate 10-1 and the second substrate 10-2 to the second substrate 10-2 side.

[0022] In the first laser beam irradiation step 1, a modified layer 20 and cracks 21 are formed inside the first substrate 10-1 by a laser processing apparatus 50 shown in FIG. 3. The laser processing apparatus 50 includes a holding table 51 and a laser beam irradiation unit 52. The holding table 51 holds the first substrate 10-1 on a holding surface and is rotatable about a vertical axis. The laser beam irradiation unit 52 irradiates a laser beam 54 onto the bonded substrate stack 10 (first substrate 10-1) held on the holding table 51. The laser beam irradiation unit 52 includes, for example, an oscillator that oscillates the laser beam 54, a condenser 53 (see FIG. 4, etc.) that condenses and irradiates the laser beam 54 toward the first substrate 10-1, and various optical components that guide the laser beam 54 from the oscillator to the condenser 53. The laser processing apparatus 50 further includes a moving unit (not shown) that moves the holding table 51 and at least the condenser 53 of the laser beam irradiation unit 52 relative to each other, and an imaging unit (not shown) that images the bonded substrate 10 held on the holding table 51.

[0023] In the first laser beam irradiation step 1, a focal point 55 of a laser beam 54 is positioned inside the first substrate 10-1 and the laser beam 54 is irradiated along the intended dividing line 13 to form a modified layer 20 and cracks 21. The laser beam 54 irradiated in the first laser beam irradiation step 1 is a laser beam of a wavelength that is transparent to the first substrate 10-1, such as infrared rays (IR).

[0024] When the rear surface 15 of the first substrate 10-1 is matte, the laser beam 54 is irradiated from the second substrate 10-2 side. When the rear surface of the first substrate 10-1 is a mirror surface, the laser beam 54 is irradiated from the first substrate 10-1 side (see the modified example described later). In the embodiment, the case where the laser beam 54 is irradiated from the second substrate 10-2 side will be described.

[0025] The modified layer 20 refers to a region where the density, refractive index, mechanical strength, or other physical properties are different from those of the surrounding area as a result of irradiation with the laser beam 54. The modified layer 20 is, for example, a melt-processed region, a crack region, a dielectric breakdown region, a refractive index change region, or a region where these regions are mixed. The modified layer 20 has lower mechanical strength and the like than other parts of the first substrate 10-1.

[0026] In the first laser beam irradiation step 1 and the second laser beam irradiation step 2, the bonded substrate 10 may be transported and processed while being supported by an annular frame 40 (see FIGS. 8 and 9) and tape 41. The frame 40 is an annular plate member made of metal or resin and has an opening larger than the outer diameter of the bonded substrate 10. The tape 41 is in the form of a sheet whose outer diameter is larger than the opening of the frame 40, and is attached to the back side of the frame 40 so as to cover the opening of the frame 40.

[0027] The tape 41 may be configured to include, for example, a base layer made of an expandable synthetic resin and an adhesive layer laminated on the base layer and made of an expandable and adhesive synthetic resin, or may be configured of a thermoplastic resin without an adhesive layer. The bonded substrate 10 is positioned at a predetermined position in the opening of the frame 40, and the back surface 15 side of the first substrate 10-1 or the back surface 15 side of the second substrate 10-2 (in the embodiment, the back surface 15 side of the first substrate 10-1) is attached to the tape 41, thereby being fixed to the frame 40 and the tape 41.

[0028] In the first laser beam irradiation step 1, first, the back surface 15 of the first substrate 10-1 is suction-held to the holding surface (upper surface) of the holding table 51 via the tape 41. Next, the bonded substrate stack 10 and the condenser 53 of the laser beam irradiation unit 52 are aligned. Specifically, the holding table 51 is moved to the irradiation area below the laser beam irradiation unit 52 by a moving unit (not shown). Next, the bonded substrate stack 10 is photographed and aligned by an imaging unit (not shown), and the irradiation portion of the laser beam irradiation unit 52 is aligned vertically toward the planned division line 13, and then the focal point 55 of the laser beam 54 is set inside the first substrate 10-1.

[0029] In the first laser beam irradiation step 1, a laser beam 54 is irradiated into the interior of the first substrate 10-1 along the planned division lines 13 while the holding table 51 and the condenser 53 of the laser beam irradiation unit 52 are moved relatively in the processing feed direction. This forms a modified layer 20 along the planned division lines 13. In the embodiment, the processing conditions for the first laser beam irradiation step 1 are a wavelength of 1342 nm, an output of 0.75 to 1.8 W, a repetition frequency of 90 kHz, a feed rate of 400 mm / s, and an index of 2000 to 3000 μm.

[0030] When the laser beam 54 is irradiated through the second substrate 10-2, which is a glass substrate, as in the embodiment, the distance from the bonding surface 16 to the modified layer 20 is preferably about 0 μm or more and 50 μm or less. That is, the position of the focusing point 55 of the laser beam 54 is preferably set at a position 0 μm or more and 50 μm or less from the bonding surface 16. At this time, cracks 21 extend from the modified layer 20. The cracks 21 extend across the bonding surface 16 to the second substrate 10-2 side. The upper limit of the distance from the bonding surface 16 to the modified layer 20 is changed as appropriate depending on the material of the second substrate 10-2.

[0031] <Second laser beam irradiation step 2> Fig. 5 is a side view, partially in cross section, showing one state of the second laser beam irradiation step 2 shown in Fig. 2. Fig. 6 is an enlarged view showing the main part of Fig. 5. Fig. 7 is a perspective view schematically showing the structure of the shield tunnel 30. The second laser beam irradiation step 2 is a step of forming division start points along the intended division lines 13 inside the second substrate 10-2.

[0032] In the second laser beam irradiation step 2, a division starting point is formed inside the second substrate 10-2 by a laser processing device 50 shown in Fig. 5. The laser processing device 50 may be the same device as the laser processing device 50 used in the first laser beam irradiation step 1, or may be a separate device. In the second laser beam irradiation step 2 of the embodiment, a shield tunnel 30 including a pore 31 and an altered portion 32 surrounding the pore 31 is formed inside the second substrate 10-2.

[0033] In the second laser beam irradiation step 2, the focused region 56 of the laser beam 54 is positioned inside the second substrate 10-2 and irradiated along the planned dividing line 13, thereby forming the shield tunnel 30 including the pores 31 and the altered portion 32. The laser beam 54 irradiated in the second laser beam irradiation step 2 is a laser beam of a wavelength that is transparent to the second substrate 10-2, such as infrared rays (IR).

[0034] In this specification, the "light-concentration region" also includes a region extending a predetermined length in the thickness direction of the second substrate 10-2. Of the "light-concentration region," the "light-concentration point" where light is focused when forming the modified layer does not extend in the thickness direction but is concentrated at one point. The "light-concentration region" where light is focused when forming the shield tunnel is set to extend in the thickness direction.

[0035] In the second laser beam irradiation step 2, first, the back surface 15 of the first substrate 10-1 is suction-held to the holding surface (upper surface) of the holding table 51 via the tape 41. Note that, when the laser beam 54 is irradiated through the second substrate 10-2 in the first laser beam irradiation step 1 as in the embodiment, the back surface 15 of the first substrate 10-1 is already held by the holding table 51, and therefore the above procedure is omitted. Next, the bonded substrate 10 is aligned with the condenser 53 of the laser beam irradiation unit 52. Specifically, the irradiation unit of the laser beam irradiation unit 52 is aligned vertically facing the planned division line 13, and then the focused region 56 of the laser beam 54 is set inside the second substrate 10-2. In the second laser beam irradiation step 2, the focused region 56 of the laser beam 54 is positioned at a depth that does not overlap with the cracks 21 formed in the first laser beam irradiation step 1.

[0036] In the second laser beam irradiation step 2, the holding table 51 and the condenser 53 of the laser beam irradiation unit 52 are moved relatively in the processing feed direction, while a laser beam 54 is irradiated into the interior of the second substrate 10-2 along the planned division line 13. This forms a shield tunnel 30 along the planned division line 13. In the embodiment, the processing conditions for the second laser beam irradiation step 2 are a wavelength of 1030 nm, an output of 0.5 to 0.6 W, a repetition frequency of 25 kHz, a feed rate of 300 mm / s, and an index of 2000 to 3000 μm.

[0037] 7, the shield tunnel 30 has a pore 31 extending from the rear surface 15 of the second substrate 10-2 to the internal crack 21, and a cylindrical altered portion 32 surrounding the pore 31. The altered portion 32 is an amorphous region. The inner diameter 33 of the pore 31 is approximately 1 μm or less, the outer diameter 34 of the altered portion 32 is approximately 5 μm or less, and the distance between adjacent altered portions 32 is approximately 10 to 15 μm.

[0038] The shield tunnel 30 is formed up to the vicinity of the crack 21 formed in the first laser beam irradiation step 1. Because the crack 21 extends to the second substrate 10-2 side, the light-focusing region 56 can be sufficiently separated from the bonding surface 16. The position of the light-focusing region 56 of the laser beam 54 is preferably set at a position 15 μm to 100 μm from the bonding surface 16. This increases defocusing at the bonding surface 16, making it possible to prevent ablation of the bonding surface 16.

[0039] <Split Step 3> Fig. 8 is a side view, partially in cross section, showing one state of dividing step 3 shown in Fig. 2. Fig. 9 is a side view, partially in cross section, showing one state after Fig. 8. Dividing step 3 is performed after first laser beam irradiation step 1 and second laser beam irradiation step 2. Dividing step 3 is a step of dividing bonded substrate stack 10 along planned dividing lines 13 by applying an external force to bonded substrate stack 10.

[0040] 8 and 9, an external force is applied to the bonded substrate 10 to divide it along the division line 13 where the modified layer 20, crack 21, and shield tunnel 30 are formed. The expansion device 60 includes a holding table 61, a clamp member 62, and a lifting unit 63.

[0041] The holding table 61 uses its holding surface to suction and hold the back surface 15 of the first substrate 10-1 of the bonded substrate stack 10. The holding surface is a disk-shaped member made of porous ceramic or the like, and is connected to a vacuum suction source, for example, via a vacuum suction path. A cylindrical abutment member 64 is provided around the periphery of the holding table 61, and is coaxial with the outer periphery of the holding table 61. A roller member 65 is rotatably provided at the upper end of the abutment member 64, on the same plane as or slightly above the holding surface of the holding table 61.

[0042] In dividing step 3, first, expanding tape is attached to the rear surface 15 side of first substrate 10-1 of bonded substrate 10 and to annular frame 40. In this embodiment, tape 41 that has been attached in advance before first laser beam irradiation step 1 is used as the expanding tape. Next, in dividing step 3, as shown in FIG. 8 , rear surface 15 side of first substrate 10-1 of bonded substrate 10 is placed on the holding surface of holding table 61 via tape 41, and the outer periphery of frame 40 is fixed with clamp members 62. At this time, roller members 65 abut against tape 41 between the inner edge of frame 40 and the outer edge of bonded substrate 10.

[0043] 9, in the dividing step 3, the holding table 61 and the abutting member 64 are raised together by the lifting unit 63. At this time, since the outer periphery of the tape 41 is fixed by the clamping member 62 via the frame 40, the portion between the inner edge of the frame 40 and the outer edge of the bonded substrate stack 10 is expanded in the planar direction. Furthermore, the roller member 65 provided at the upper end of the abutting member 64 reduces friction with the tape 41.

[0044] In the dividing step 3, as a result of the expansion of the tape 41, a radial tensile force acts on the tape 41. When the radial tensile force acts on the tape 41, the bonded substrate 10 to which the tape 41 is attached is divided at the modified layer 20, the cracks 21, and the shield tunnels 30 as fracture starting points, and is divided into individual laminated chips 17 having individual devices 14.

[0045] In the dividing step 3 of the embodiment, the holding table 61 and the abutting member 64 are raised to expand the tape 41, but the present invention is not limited to this, and the clamping member 62 may be lowered. That is, the holding table 61 and the abutting member 64 may be raised relative to the clamping member 62, and the clamping member 62 may be lowered relative to the holding table 61 and the abutting member 64.

[0046] [Modification] Next, a method for processing the bonded substrate 10 according to a modified example of the present invention will be described with reference to the drawings.

[0047] <First laser beam irradiation step 1> 10 is an enlarged, partially cross-sectional side view of a main portion of a first laser beam irradiation step 1 according to a modified example. In the first laser beam irradiation step 1 of the modified example, a laser beam 54 is irradiated from the first substrate 10-1 side. In the example shown in FIG. 10, a tape 41 is attached to the second substrate 10-2 side. In the first laser beam irradiation step 1 of the modified example, the back surface 15 of the second substrate 10-2 is suction-held to the holding surface (upper surface) of the holding table 51 via the tape 41, and the laser beam 54 is irradiated from the first substrate 10-1 side.

[0048] The procedure of first laser beam irradiation step 1 in the modified example is the same as that of first laser beam irradiation step 1 in the embodiment, except that the direction of irradiation of laser beam 54 is opposite. In the modified example, the processing conditions for first laser beam irradiation step 1 are a wavelength of 1099 nm, an output of 2.4 to 2.6 W, a repetition frequency of 120 kHz, a feed rate of 1000 mm / s, and an index of 2000 to 3000 μm.

[0049] When the laser beam 54 is irradiated directly from the side of the first substrate 10-1, which is a Si substrate, as in the modified example, the distance from the bonding surface 16 to the modified layer 20 is preferably set to be equal to or greater than 0 μm and equal to or less than half the thickness (650 μm) of the first substrate 10-1. In other words, the position of the focal point 55 of the laser beam 54 is preferably set in the range from the bonding surface 16 to a position half the thickness (650 μm) of the first substrate 10-1. In this case, the crack 21 extending from the modified layer 20 crosses the bonding surface 16 and reaches the side of the second substrate 10-2.

[0050] <Second laser beam irradiation step 2> Fig. 11 is a side view, partially in cross section, showing one state of the second laser beam irradiation step 2 according to the modified example. Fig. 12 is an enlarged view showing the main part of Fig. 11. In the second laser beam irradiation step 2 of the modified example, the focal point 57 of the laser beam 54 is positioned inside the second substrate 10-2 and the laser beam is irradiated along the division line 13, thereby forming a modified layer 22 along the division line 13 inside the second substrate 10-2 and cracks 23 extending from the modified layer 22. That is, in the second laser beam irradiation step 2 of the modified example, the modified layer 22 and the cracks 23 are formed instead of the shield tunnel 30 of the embodiment.

[0051] The procedure of second laser beam irradiation step 2 of the modified example is generally similar to the procedure of second laser beam irradiation step 2 of the embodiment. In second laser beam irradiation step 2 of the modified example, laser beam 54 is irradiated with focal point 57 of laser beam 54 set inside second substrate 10-2. At this time, focal point 57 of laser beam 54 is positioned at a depth that does not overlap with crack 21 formed in first laser beam irradiation step 1.

[0052] In the second laser beam irradiation step 2 of the modified example, a laser beam 54 is irradiated into the interior of the second substrate 10-2 along the planned division lines 13 while the holding table 51 and the condenser 53 of the laser beam irradiation unit 52 are moved relatively in the processing feed direction. This forms a modified layer 22 along the planned division lines 13. In the embodiment, the processing conditions for the second laser beam irradiation step 2 are a wavelength of 1064 nm, an output of 0.5 to 1 W, a repetition frequency of 50 kHz, a feed rate of 600 to 1200 mm / s, and an index of 2000 to 3000 μm.

[0053] Cracks 23 extend from the modified layer 22. The cracks 23 connect to the cracks 21 formed in the first laser beam irradiation step 1. Since the cracks 21 formed in the first laser beam irradiation step 1 extend to the second substrate 10-2 side, the focal point 57 can be sufficiently separated from the bonding surface 16. The position of the focal point 57 of the laser beam 54 is preferably set at a position 40 μm or more and 60 μm or less from the bonding surface 16. This increases defocusing at the bonding surface 16, making it possible to prevent ablation of the bonding surface 16.

[0054] As described above, in the processing method for bonded substrate 10 according to the embodiment and the modified example, first substrate 10-1 is irradiated with laser beam 54 to process it, and crack 21 extending to second substrate 10-2 is formed. As a result, when second substrate 10-2 is irradiated with laser beam 54, light-focusing region 56 (light-focusing point 57) can be positioned at a predetermined distance or more from bonding surface 16, thereby preventing ablation of bonding surface 16. This has the effect of preventing separation defects when separating bonded substrate 10 and reducing the occurrence of contamination.

[0055] The present invention is not limited to the above-described embodiment, and can be implemented in various modifications without departing from the gist of the present invention.

[0056] For example, in the first laser beam irradiation step 1 and the second laser beam irradiation step 2, processing does not have to be performed with tape 41 attached to bonded substrate 10. Furthermore, when processing is performed with tape 41 attached, it does not necessarily have to be attached to the surface shown in the embodiment and modified examples (the surface held by holding table 51), and it is also possible to attach tape 41 to the surface irradiated with laser beam 54, and irradiate laser beam 54 through tape 42.

[0057] In addition, in the dividing step 3, the dividing may be performed simply by expanding the tape 41, but before expanding, the tape 41 may be broken and divided using a breaking device, and then the space between the stacked chips 17 may be expanded by expanding. [Explanation of symbols]

[0058] 10 Bonded substrate 10-1 First board 10-2 Second board 13 Planned division line 16 Joint surface 20, 22 Modified layer 21, 23 Crack 30 Shield Tunnel 31 pores 32 Deformed area 50 Laser processing equipment 54 Laser Beam 55, 57 Focus point 56 Focus area 60 Expansion Unit

Claims

1. A method for processing a bonded substrate, in which a bonded substrate formed by bonding a first substrate and a second substrate is divided along a predetermined dividing line, comprising: a first laser beam irradiation step in which a focal point of a laser beam having a wavelength that is transparent to the first substrate is positioned inside the first substrate and the laser beam is irradiated along the planned division line, thereby forming a modified layer along the planned division line inside the first substrate and cracks extending from the modified layer to the second substrate side across the bonding surface between the first substrate and the second substrate; a second laser beam irradiation step of positioning a focused region of a laser beam having a wavelength that is transparent to the second substrate inside the second substrate and irradiating the second substrate along the planned division lines, thereby forming division starting points along the planned division lines inside the second substrate; After the first laser beam irradiation step and the second laser beam irradiation step are performed, a dividing step of dividing the bonded substrate stack along the dividing lines by applying an external force to the bonded substrate stack; Contains A method for processing a bonded substrate, comprising:

2. In the second laser beam irradiation step, A focused region of a laser beam having a wavelength that is transparent to the second substrate is positioned inside the second substrate and irradiated, thereby forming a shield tunnel including a pore and an altered portion surrounding the pore inside the second substrate.

2. The method for processing a bonded substrate according to claim 1, wherein the bonding step comprises:

3. In the second laser beam irradiation step, The focused region of the laser beam is positioned at a depth that does not overlap with the crack formed in the first laser beam irradiation step.

3. The method for processing a bonded substrate according to claim 2, wherein the bonding step comprises:

4. The first substrate is a Si substrate, and the second substrate is a glass substrate.

4. The method for processing a bonded substrate according to claim 1, wherein the bonding step comprises:

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