Method for manufacturing wafers and method for manufacturing bonded wafers

Abstract

The goal is to enable processing of the outer edge of the wafer, thereby reducing the processing time. [Solution] The present invention relates to a method for manufacturing a bonded wafer (400) obtained by joining a first wafer (100) and a second wafer (200). A bonding step is performed in which the first surface (101) of the first wafer and the second surface (201) of the second wafer are joined or bonded. After the bonding step, a side processing step is performed in which the side surface (103) of the first wafer is irradiated with a laser beam (LB) to process the side surface of the first wafer.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a wafer for processing the outer periphery of a wafer and a method for manufacturing a bonded wafer.

Background Art

[0002] Patent Document 1 discloses an edge trimming device, which performs processing of cutting and removing a chamfer portion on the outer peripheral edge of a wafer with a cutting blade. In this processing, as in Patent Document 2, when uneven wear occurs at the tip of the cutting blade, the chamfer portion cannot be completely removed. In order to avoid such a state, as disclosed in Patent Document 3, it is conceivable to dress the tip of the cutting blade to shape the tip.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0006] The present invention has been made in view of the above, and one of its objectives is to provide a method for manufacturing a wafer and a method for manufacturing a bonded wafer that can process the outer periphery of the wafer and shorten the time required for processing. [Means for solving the problem]

[0007] A wafer manufacturing method according to one aspect of the present invention includes a support step of bonding or joining one surface of a first wafer to one surface of a support substrate to support the first wafer on the support substrate; a side processing step of irradiating the side surface of the first wafer supported on the support substrate with a laser beam to make the cross-sectional shape of the side surface of the first wafer a predetermined cross-sectional shape; and a grinding step of grinding the other surface of the first wafer before or after the side processing step.

[0008] A method for manufacturing a bonded wafer according to one aspect of the present invention is a method for manufacturing a bonded wafer obtained by joining a first wafer and a second wafer, comprising: a joining step of joining or bonding one surface of the first wafer to one surface of the second wafer; and a side processing step of irradiating the side surface of the first wafer with a laser beam after the joining step to process the side surface of the first wafer. [Effects of the Invention]

[0009] According to the present invention, since the side surface of the first wafer is irradiated with a laser beam for processing, the dressing process can be omitted compared to processing using conventional cutting blades, thereby shortening the processing time. This makes it possible to efficiently perform processing such as changing the cross-sectional shape of the side surface of the first wafer or reducing the diameter of the first wafer. [Brief explanation of the drawing]

[0010] [Figure 1] The first embodiment of the method for manufacturing a bonded wafer is shown, with Figures 1A and 1B being explanatory diagrams of the bonding process, and Figures 1C and 1D being explanatory diagrams of the side processing process. [Figure 2] The second embodiment of the method for manufacturing a bonded wafer is shown, with Figures 2A and 2B being explanatory diagrams of the surface processing process and Figure 2C being an explanatory diagram of the chamfering process. [Figure 3] The manufacturing method for a bonded wafer according to the third embodiment is shown, with Figure 3A being an explanatory diagram of the side processing process, and Figures 3B and 3C being explanatory diagrams of the surface processing process. [Figure 4] The manufacturing method for a bonded wafer according to the fourth embodiment is shown, with Figures 4A and 4B being explanatory diagrams of the surface processing process and Figure 4C being an explanatory diagram of the side processing process. [Figure 5] This is an explanatory diagram of the side machining process related to a modified example. [Modes for carrying out the invention]

[0011] [First Embodiment] The manufacturing method of the bonded wafer according to the first embodiment will be described below with reference to the attached drawings, with reference to Figure 1. Figures 1A and 1B are explanatory diagrams of the bonding process, and Figures 1C and 1D are explanatory diagrams of the side processing process. In the manufacturing method of the bonded wafer according to the first embodiment, the bonding process and the side processing process are carried out in that order. Note that the processes shown in each figure in each embodiment below are merely examples and are not limited to this configuration. Also, in each figure, including Figure 1, the hatching in the cross-section of the bonding layer 300, which will be described later, has been omitted.

[0012] [Joining process] The bonding process begins by preparing a disc-shaped first wafer 100 and a second wafer 200, as shown in Figure 1A. The first wafer 100 and the second wafer 200 are typically composed of semiconductors such as silicon (Si).

[0013] The first wafer 100 has a first surface 101 and a first back surface 102 which are perpendicular to the thickness direction. The first surface 101 is one surface of the first wafer 100, and the first back surface 102 is the other surface of the first wafer 100. The second wafer 200 has a second surface 201 and a second back surface 202 which are perpendicular to the thickness direction. The second surface 201 is one surface of the second wafer 200, and the second back surface 202 is the other surface of the second wafer 200.

[0014] In Figure 1A, the first wafer 100 is positioned with its first surface 101 facing downwards and its first back surface 102 facing upwards, and the second wafer 200 is positioned with its second surface 201 facing upwards and its second back surface 202 facing downwards. The first wafer 100 has a side surface 103 formed along its outer edge, and the side surface 103 is formed perpendicular to the first surface 101 and the first back surface 102. Corners 104 and 105, which are approximately right angles, are formed at the intersections of the first surface 101 and the side surface 103, and at the intersections of the first back surface 102 and the side surface 103.

[0015] In the bonding process, as shown in Figure 1B, the second back surface 202 of the second wafer 200 is held facing downwards on the chuck table 11. Around the same time, an insulating film is formed on the second surface 201 of the second wafer 200. Then, the insulating film surface is activated using argon gas (a rare gas). An insulating film is also formed on the first surface 101 of the first wafer 100. Then, the insulating film surface is activated using argon gas. After the first surface 101 of the first wafer 100 is brought into contact with the second surface 201 of the second wafer 200, the first surface 101 of the first wafer 100 is pressed against the second surface 201 of the second wafer 200 to bring the activated first surface 101 and the second surface 201 into close contact. As a result, interatomic stress acts, bonding the surfaces 101 and 201 of the first wafer 100 and the second wafer 200, respectively, to form a bonded wafer 400. The bonding layer 300 that bonds the first wafer 100 and the second wafer 200 in the bonding wafer 400 is composed of an insulating film on the first surface 101 of the first wafer 100 and an insulating film on the second surface 201 of the second wafer 200.

[0016] In addition, in the present embodiment, due to the dimensional tolerances of the first wafer 100 and the second wafer 200, the first wafer 100 has a larger diameter dimension than the second wafer 200. Therefore, in the bonded wafer 400, the side surface 103 of the first wafer 100 protrudes outward from the outer periphery of the second wafer 200.

[0017] Here, the bonding member for forming the bonding layer 300 may be, for example, a double-sided adhesive sheet in which an adhesive is formed in a circular sheet shape. In addition to the double-sided adhesive sheet, a circular double-sided adhesive tape can be used. Also, a bonding layer 300 may be formed by applying an adhesive or a liquid resin to the second surface 201 of the second wafer 200 and bonding the first wafer 100. Therefore, in the bonding process, the bonding wafer 400 may be formed by bonding the respective surfaces 101 and 201 of the first wafer 100 and the second wafer 200.

[0018] [Side surface processing step] After the bonding process is completed, as shown in FIGS. 1C and 1D, a side surface processing step is performed in the laser processing apparatus 20. The laser processing apparatus 20 only needs to be configured to be able to perform the laser processing step of the present embodiment, and is not limited to the configuration shown in FIGS. 1C and 1D.

[0019] As shown in FIGS. 1C and 1D, the laser processing apparatus 20 is configured to relatively move a chuck table 21 that holds the bonded wafer 400 and a laser irradiation unit 22 that irradiates a laser beam LB to laser-process the side surface 103 of the first wafer 100.

[0020] [[ID=二十]] The laser irradiation unit 22 irradiates the side surface 103 of the first wafer 100 on the bonded wafer 400 held in the chuck table 21 with a laser beam LB emitted from a laser oscillator (not shown). The laser irradiation unit 22 is equipped with an optical system such as mirrors and lenses that guide the pulsed laser beam LB emitted from the laser oscillator to the first wafer 100, and focuses the laser beam LB onto the first wafer 100. The laser oscillator contains, for example, a laser medium such as Nd:YAG suitable for laser oscillation and generates a pulsed laser beam LB with a wavelength absorbed by the first wafer 100 at a predetermined repetition frequency. The laser irradiation unit 22 irradiates and focuses the laser beam LB onto the first wafer 100 from the side of the chuck table 21.

[0021] The laser processing apparatus 20 further includes a rotation mechanism 24 that rotates the chuck table 21 around an axis extending in the vertical direction, a horizontal movement mechanism 25 that moves the chuck table 21 in a horizontal direction, for example, in two orthogonal axis directions, and a lifting mechanism 26 that moves the chuck table 21 in the vertical direction.

[0022] The rotation mechanism 24 includes a drive motor and pulley mechanism (not shown) and rotates the chuck table 21 around an axis extending vertically. The horizontal movement mechanism 25 and the lifting mechanism 26 employ appropriate structures such as cylinders, motors, sliders, and ball screws.

[0023] In the side-processing step, the bonded wafer 400 is first held on the chuck table 21 with the second back surface 202 of the second wafer 200 facing downwards. Then, the chuck table 21 and the bonded wafer 400 are rotated by the drive of the rotation mechanism 24. While this rotation continues, a laser beam LB having an absorbing wavelength is irradiated from the laser irradiation unit 22 onto the side surface 103 of the first wafer 100 on the bonded wafer 400. The irradiated laser beam LB is focused onto the side surface 103 of the first wafer 100 by a focusing lens (not shown). In other words, the relative position between the rotating first wafer 100 and the laser irradiation unit 22 is adjusted by moving the chuck table 21 via the drive of the horizontal movement mechanism 25 and the lifting mechanism 26 so that the laser beam LB is focused onto the side surface 103 when irradiated.

[0024] When the laser beam LB is irradiated onto the side surface 103, the portion forming the side surface 103 of the first wafer 100 is sublimated and ablated. As a result, as shown in Figure 1D, the portion forming the side surface 103 of the first wafer 100 is removed, and the diameter of the first wafer 100 is reduced. Air may also be sprayed onto the area to be ablated to prevent the molten material of the first wafer 100 from adhering to the newly formed side surface 103 (the side surface of the first wafer 100 with a reduced diameter), and to prevent thermal deformation of the first wafer 100 due to the ablation process.

[0025] In the side-processing step in this embodiment, the entire thickness of the first wafer 100 is ablated, and the diameter of the first wafer 100 is uniformly reduced across the entire thickness. To perform this processing, the chuck table 21 is repeatedly moved up and down by the drive of the lifting mechanism 26, and the focusing position of the laser beam LB is displaced to reciprocate in the vertical direction (thickness direction of the first wafer 100). At this time, as the ablation process progresses, the horizontal movement mechanism 25 is driven so that the focusing position of the laser beam LB is gradually displaced toward the center of the first wafer 100. Even after the side-processing step is performed, the formation of angles 104 and 105 that are approximately right angles is maintained at the intersection of the first surface 101 and the side surface 103, and at the intersection of the first back surface 102 and the side surface 103.

[0026] Ablation processing refers to the phenomenon in which, when the irradiation intensity of a laser beam LB exceeds a predetermined processing threshold, it is converted into electronic, thermal, photochemical, and mechanical energy on a solid surface. As a result, neutral atoms, molecules, positive and negative ions, radicals, clusters, electrons, and light are explosively released, and the solid surface is etched.

[0027] According to the first embodiment described above, the side surface 103 of the first wafer 100 is irradiated with a laser beam LB to process the first wafer 100 in a way that reduces its diameter. This eliminates the need for dressing, which is required in conventional processing using cutting blades, and shortens the time required for processing the side surface 103, enabling efficient manufacturing of bonded wafers 400.

[0028] Furthermore, by processing the first wafer 100 to reduce its diameter, it can be formed so that the first wafer 100 does not protrude from the outer circumference of the second wafer 200. As a result, even when the bonded wafer 400 is rotated at high speed during processing, fluttering will not occur in the outer circumference of the first wafer 100, and chipping of the outer circumference can be avoided.

[0029] Furthermore, the first wafer 100 may be reduced in diameter and chamfered at corners 104 and 105 by irradiating it with a laser beam LB, similar to the chamfering process in the second embodiment described later. In other words, even if chamfered portions are not formed on the first wafer 100 before reducing its diameter, chamfered portions may be formed during the diameter reduction process.

[0030] Next, embodiments of the present invention other than those described above will be described. In the following description, the same reference numerals may be used for components that are the same as or equivalent to those described in embodiments described before the embodiment being described, and the description may be omitted or simplified.

[0031] [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to Figure 2. Figures 2A and 2B are explanatory diagrams of the surface machining process, and Figure 2C is an explanatory diagram of the chamfering process. In the second embodiment, after performing the joining process and side machining process of the first embodiment in the same manner, the surface machining process and chamfering process described below are performed in order.

[0032] [Surface processing process] In the second embodiment, as shown in Figures 2A and 2B, the surface machining process is performed in the grinding mechanism 30 after the completion of the side machining process described above. In the surface machining process, the second back surface 202 of the second wafer 200 of the bonded wafer 400 is held facing downwards on the chuck table 31 of the grinding mechanism 30.

[0033] Subsequently, a portion of the annularly arranged grinding wheels 33 of the grinding wheel 32 in the grinding mechanism 30 is positioned to face the first back surface 102, which will be the upper surface of the first wafer 100. Then, while the chuck table 31 and the grinding wheel 32 are rotated around their respective vertical axes, the lower surface of the grinding wheels 33 is pressed against the first back surface 102 of the first wafer 100. As a result, the first back surface 102 of the first wafer 100 is ground by the grinding wheels 33, and the first wafer 100 is thinned to a predetermined thickness.

[0034] Even after the surface processing step is performed, the formation of corners 104 and 105 at the intersection of the first surface 101 and the side surface 103, and at the intersection of the first back surface 102 and the side surface 103, is maintained on the first wafer 100.

[0035] The surface processing step described above was performed using a grinding wheel 33 in the grinding mechanism 30, but various modifications are possible. For example, the surface of the first back surface 102 of the first wafer 100 may be polished with a rotating polishing pad (dry polishing, wet polishing, CMP), or etched by plasma etching.

[0036] [Chamfering process] After the surface processing process, a chamfering process is performed to chamfer the corners 104 and 105 of the first wafer 100. The chamfering process is performed using the same or similar laser processing apparatus 20 as the side processing process.

[0037] In the chamfering process, similar to the side processing process, the bonded wafer 400 is held and rotated by the chuck table 21, and a laser beam LB with an absorbing wavelength is irradiated from the laser irradiation unit 22 onto the side surface 103 of the first wafer 100. This irradiation with the laser beam LB causes both corners 104 and 105 on the side surface 103 of the first wafer 100 to be chamfered into an R shape, which is an arc shape in cross-section. In other words, the relative position between the side surface 103 of the first wafer 100 and the laser irradiation unit 22 is adjusted via the driving of the horizontal movement mechanism 25 and the lifting mechanism 26 so that ablation processing can be performed to create the above shape by irradiation with the laser beam LB.

[0038] According to the second embodiment described above, in the manufacturing of the bonded wafer 400, the surface processing process can be used to perform grinding to thin the first wafer 100, as well as polishing and etching to remove irregularities on the first back surface 102. Furthermore, after these processes, the corners 104 and 105 of the first wafer 100 can be chamfered by a chamfering process, which can better prevent chipping and cracking on the outer periphery of the first wafer 100.

[0039] [Third Embodiment] Next, a third embodiment of the present invention will be described with reference to Figure 3. Figure 3A is an explanatory diagram of the side machining process, and Figures 3B and 3C are explanatory diagrams of the surface machining process. In the third embodiment, the shape of the side surface 103 after machining in the side machining process is changed compared to the first embodiment, and a surface machining process by grinding is performed similar to that in the second embodiment.

[0040] [Side processing process] In the third embodiment, the side processing step, as shown in Figure 3A, involves ablation processing on the side surface 103 of the first wafer 100 so that the diameter of the first wafer 100 is reduced in a portion of the thickness direction. In Figure 3A, the first wafer 100 is ablated by irradiation with a laser beam LB so that the diameter is reduced on the first surface 101 side in the thickness direction, while the first back surface 102 side is not irradiated with the laser beam LB and remains unprocessed. In other words, in order to enable ablation processing as described above, the relative position between the side surface 103 of the first wafer 100 and the laser irradiation unit 22 is adjusted via the driving of the horizontal movement mechanism 25 and the lifting mechanism 26 when the laser beam LB from the laser irradiation unit 22 is irradiated.

[0041] [Surface processing process] After the side machining process is completed, as shown in Figures 3B and 3C, the surface machining process is performed by the grinding mechanism 30, and the first back surface 102 of the first wafer 100 is ground by the rotating grinding wheel 33. In the surface machining process of the third embodiment, grinding is performed up to the position in the thickness direction where the diameter dimension of the first wafer 100 was reduced in the side machining process. Therefore, all the thickness portions on the first back surface 102 side of the first wafer 100 that were not irradiated by the laser beam LB and were left unprocessed are removed.

[0042] According to the third embodiment described above, compared to the first embodiment, the amount of first wafer 100 removed by irradiation with the laser beam LB in the side processing step can be reduced. On the other hand, compared to the second embodiment, the third embodiment can make the diameter dimension of the first wafer 100 after grinding in the surface processing step the same (see Figures 2B and 3C). Therefore, in the third embodiment, when processing the first wafer 100 to the diameter shown in Figures 2B and 3C, the processing time in the side processing step can be shortened by reducing the amount of first wafer 100 removed.

[0043] [Fourth Embodiment] Next, a fourth embodiment of the present invention will be described with reference to Figure 4. Figures 4A and 4B are explanatory diagrams of the surface machining process, and Figure 4C is an explanatory diagram of the side machining process. In the fourth embodiment, after performing the joining process as in the first embodiment, the surface machining process and the side machining process are performed in that order. Therefore, the surface machining process is performed before the side machining process.

[0044] [Surface processing process] As shown in Figures 4A and 4B, the surface processing step is performed in the grinding mechanism 30 with the side surface 103 of the first wafer 100 protruding outward from the outer circumference of the second wafer 200 in the bonded wafer 400. This surface processing step is performed in the same manner as the surface processing step of the second embodiment, except that the shape of the first wafer 100 in the bonded wafer 400 is different, and the first wafer 100 is thinned to a predetermined thickness.

[0045] [Side processing process] The side processing process is performed using the laser processing apparatus 20 after the surface processing process has been completed. In the side processing process, the bonded wafer 400 is held and rotated by the chuck table 21, and a laser beam LB having an absorbing wavelength is irradiated from the laser irradiation unit 22 onto the side surface 103 of the first wafer 100. Irradiation with this laser beam LB reduces the diameter of the first wafer 100 over the entire thickness range, and ablation processing is performed so that both corners 104 and 105 on the side surface 103 of the first wafer 100 are chamfered into an arc shape in cross-sectional view. In other words, the relative position between the side surface 103 of the first wafer 100 and the laser irradiation unit 22 is adjusted via the driving of the horizontal movement mechanism 25 and the lifting mechanism 26 so that ablation processing can be performed to the above shape by irradiation with the laser beam LB.

[0046] According to the fourth embodiment described above, the diameter reduction of the first wafer 100 and the chamfering of the side surface 103 can be performed simultaneously in the side surface processing process, thereby shortening the processing time.

[0047] Furthermore, the present invention is not limited to the embodiments described above, and can be implemented with various modifications. In the embodiments described above, the size, shape, etc., shown in the accompanying drawings are not limited thereto, and can be appropriately modified within the scope that allows the present invention to exert its effects. In addition, the present invention can be implemented with appropriate modifications as long as it does not deviate from the scope of its objectives.

[0048] In the embodiments described above, a method for manufacturing the bonded wafer 400 was explained. However, by changing the object to be bonded or joined with the first wafer 100, the method can be used to manufacture the first wafer 100 (wafer).

[0049] In the manufacturing method of the first wafer 100, a support step is performed instead of the bonding step described above. In this support step, a support substrate is used instead of the second wafer 200. The support substrate is formed in the shape of a disc, similar to that of the first wafer 100, and is not particularly limited; for example, one equivalent to the first wafer 100 or the second wafer 200 can be used.

[0050] In the support process, one surface of the support substrate is bonded or joined to a first surface 101, which is one side of the first wafer 100, and the first wafer 100 is supported by the support substrate. The support process is carried out in the same manner as the bonding process described above, except that a support substrate is used instead of a second wafer 200.

[0051] In the manufacturing method of the first wafer 100, after the support step, a side processing step is performed in the same manner as in the first or third embodiment described above. In the side processing step, a laser beam LB is irradiated onto the side surface 103 of the first wafer 100 supported on the support substrate, and the cross-sectional shape of the side surface 103 of the first wafer 100 is processed to a predetermined cross-sectional shape. Through the side processing step, the diameter dimension of the first wafer 100 can be reduced as shown in Figure 1D, or the cross-sectional shape can be changed in which the diameter dimension is altered in a part of the thickness direction of the first wafer 100 as shown in Figure 3A, or the cross-sectional shape can be changed in which both sides of the thickness direction of the side surface 103 are chamfered as shown in Figure 2C.

[0052] In the manufacturing method of the first wafer 100, a grinding step is performed before or after the side processing step, and this grinding step is performed in the same manner as the grinding performed in the surface processing step of the second or third embodiment described above. In the grinding step, the first back surface 102, which is the other surface of the first wafer 100, is ground, and the first wafer 100 is processed to become thinner.

[0053] In the manufacturing method for the first wafer 100, a first wafer 100 is manufactured by performing a support process, a side processing process, and a grinding process, thereby forming it to a predetermined diameter and thickness, and having its side surface 103 formed to a predetermined cross-sectional shape.

[0054] Furthermore, although the chamfering process was performed after the surface machining process in the second embodiment, the order may be reversed, and the chamfering process may be performed before the surface machining process.

[0055] Furthermore, in the bonded wafer 400, the surfaces to be bonded or joined in the first wafer 100 and the second wafer 200 may be any of the front surfaces 101, 201 and the back surfaces 102, 202. In the first wafer 100 and the second wafer 200, the surface to be bonded or joined is formed as one surface, and the opposite surface is formed as the other surface.

[0056] Furthermore, in the side processing step of the third embodiment, the cross-sectional shape of the side surface 103 of the first wafer 100 shown in Figure 5 can be formed by adjusting the drive of the horizontal movement mechanism 25 and the lifting mechanism 26 when the laser beam LB from the laser irradiation unit 22 is irradiated. This cross-sectional shape is formed so that the portion processed to reduce the diameter of the first wafer 100 is chamfered. By performing the surface processing step after forming this cross-sectional shape, the first wafer 100 with chamfered side surface 103 can be formed without performing a chamfering step, thereby shortening the manufacturing time. [Industrial applicability]

[0057] As described above, the present invention has the effect of reducing the time required for processing the outer periphery of a first wafer bonded to a second wafer or the like. [Explanation of Symbols]

[0058] 100: First wafer (wafer) 101: First surface (one side) 102: First reverse side (the other side) 103: Side view 104: Corner 105: Corner 200: Second wafer 201: Second surface (one side) 400: Bonded wafer LB: Laser beam

Claims

1. A method for manufacturing wafers, A support step of bonding or joining one side of the first wafer to one side of the support substrate to support the first wafer on the support substrate, A side processing step involves irradiating the side surface of the first wafer, which is supported by the support substrate, with a laser beam to make the cross-sectional shape of the side surface of the first wafer a predetermined cross-sectional shape, A method for manufacturing a wafer, comprising a grinding step of grinding the other surface of the first wafer before or after the side processing step.

2. A method for manufacturing a bonded wafer obtained by joining a first wafer and a second wafer, A bonding step of joining or bonding one side of the first wafer to one side of the second wafer, A method for manufacturing a bonded wafer, comprising: a side processing step of irradiating the side surface of the first wafer with a laser beam after the bonding step to process the side surface of the first wafer.

3. A method for manufacturing a bonded wafer according to claim 2, comprising a surface processing step of grinding, polishing, or etching the other surface of the first wafer before or after the side processing step.

4. A method for manufacturing a bonded wafer according to claim 3, comprising a chamfering step of chamfering the corner between the side surface of the first wafer and one of the faces of the first wafer, and the corner between the side surface of the first wafer and the other face of the first wafer, before or after the surface processing step.

5. The method for manufacturing a bonded wafer according to claim 2, wherein in the side processing step, the corner between the side surface of the first wafer and the one face of the first wafer, and the corner between the side surface of the first wafer and the other face of the first wafer are chamfered.

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