Wafer processing method

Abstract

This invention provides a wafer processing method that addresses contamination generated during laser processing to form shield tunnels. [Solution] A method for processing a wafer 10 having a product area and an outer peripheral excess area into a product, comprising: a substrate preparation step of preparing a substrate 20 having an annular protrusion corresponding to the outer peripheral excess area and a recess surrounded by the protrusion corresponding to the product area; a sealing step of attaching the outer peripheral excess area of ​​the wafer 10 and the protrusion of the substrate 20 with an adhesive 30 to form a sealing body W; a shield tunnel formation step of irradiating the wafer 10 of the sealing body W with a pulsed laser beam LB along a planned division line along the outer shape of the product to grow pores 102 from the top surface to the bottom surface and a modified body 104 that shields the pores 102 to form a shield tunnel 100; and a division step of dividing the wafer 10 into a product using the shield tunnel 100 formed along the planned division line as a starting point.

Description

Technical Field

[0005] ,

[0001] The present invention relates to a method for processing a wafer having a product area where a product is formed and an outer peripheral surplus area surrounding the product area into a product.

Background Art

[0002] A wafer on which a plurality of devices such as ICs and LSIs are partitioned by a dicing line and formed on the surface is ground on the back surface by a grinding device to form a predetermined thickness, and then diced into individual device chips by a dicing device having a rotatable cutting blade, and is used in electrical devices such as mobile phones, personal computers, and electrical equipment.

[0003] In addition, when manufacturing products such as optical components, interposer substrates, circular substrates, cover plates for device chips, and devices, although it is necessary to cut a wafer formed from a plate-like material such as quartz glass, sapphire, silicon carbide (SiC), gallium nitride (GaN), lithium tantalate (LT), lithium niobate (LN), etc. into the size and shape of the product, for example, when cutting quartz glass, LT, or LN with a dicing device, chipping occurs on the outer periphery of the product and the quality is unstable. Also, sapphire, SiC, and GaN have high hardness and are difficult to cut with a cutting blade. Furthermore, when the product includes a curve such as a circle, it is extremely difficult to cut along the outer shape of the product. Therefore, it is recommended to use the laser processing technology for forming a shield tunnel developed by the applicant (see, for example, Patent Document 1).

Prior Art Documents

[0006] The present invention has been made in view of the above facts, and its main technical problem is to provide a wafer processing method that can solve the problem of dust generated by forming a shield tunnel accumulating and blocking the pores of the shield tunnel formed in the wafer, thereby contaminating the processing area in subsequent processes performed after laser processing to form the shield tunnel. [Means for solving the problem]

[0007] To solve the above-mentioned main technical problems, the present invention provides a wafer processing method for processing a wafer having a product region on which a product is formed and an outer peripheral excess region surrounding the product region into a product, comprising: a substrate preparation step of preparing a substrate having an annular protrusion corresponding to the outer peripheral excess region and a recess surrounded by the protrusion and corresponding to the product region; a sealing step of positioning the outer peripheral excess region of the wafer on the protrusion and attaching it via an adhesive to form a sealed body in which the product region of the wafer and the recess of the substrate face each other and are sealed; a shield tunnel formation step of irradiating a pulsed laser beam along a planned division line along the outer shape of the product in order to process the wafer of the sealed body into a product, thereby growing pores from the top surface to the bottom surface of the wafer and a modified material that shields the pores to form a shield tunnel; and a division step of dividing the wafer into products using the shield tunnel formed on the planned division line as a starting point.

[0008] The shield tunnel formation process preferably includes: an aperture number setting step of setting the numerical aperture (NA) of the focusing lens so that the value obtained by dividing the numerical aperture (NA) of the focusing lens that focuses the pulsed laser beam by the refractive index (N) of the wafer (NA / N) is in the range of 0.05 to 0.2; a positioning step of positioning the focusing lens and the wafer relative to each other in the optical axis direction so that the focal point of the pulsed laser beam is located at a desired position in the thickness direction of the wafer; and a shield tunnel formation step of irradiating with a pulsed laser beam to grow pores and a modified material that shields the pores to form the shield tunnel.

[0009] It is preferable that the process includes an integration step before the splitting step in which a frame having a central opening for housing a wafer is positioned on the upper surface of the wafer, and tape is applied to it to integrate the wafer and the frame. It is also preferable that the process includes an expansion step after the splitting step in which the tape is expanded to increase the spacing between adjacent products. [Effects of the Invention]

[0010] The wafer processing method of the present invention is a wafer processing method for processing a wafer having a product region on which a product is formed and an outer peripheral excess region surrounding the product region into a product, comprising: a substrate preparation step of preparing a substrate having an annular protrusion corresponding to the outer peripheral excess region and a recess surrounded by the protrusion and corresponding to the product region; a sealing step of positioning the outer peripheral excess region of the wafer on the protrusion and attaching it via an adhesive to form a sealed body in which the product region of the wafer and the recess of the substrate face each other and seal the wafer; and dividing the wafer of the sealed body according to the outer shape of the product in order to process it into a product. The process includes a shield tunnel formation step, in which a pulsed laser beam is irradiated onto a fixed line to grow pores extending from the top to the bottom of the wafer and a modified material that shields these pores to form a shield tunnel, and a splitting step, in which the wafer is split into products using the shield tunnel formed on the line to be split. As a result, dust generated by the formation of the shield tunnel is contained in the recesses of the substrate, preventing the dust from accumulating in the shield tunnel and blocking the pores, thus eliminating the problem of dust accumulating in the pores and blocking them, which would then scatter and cause contamination in subsequent processes. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of a wafer processed by the wafer processing method of this embodiment. [Figure 2] (a) Perspective view of the substrate, (b) Cross section AA in (a). [Figure 3] This is a perspective view showing an embodiment of the sealing process of this embodiment. [Figure 4] This is a perspective view showing how the sealing body is placed and held on the chuck table of a laser processing apparatus. [Figure 5] (a) A perspective view showing how the shield tunnel formation process is carried out, (b) A partially enlarged cross-sectional view of the shield tunnel formation process shown in (a), and (c) A perspective view showing how the shield tunnel has been formed along all the planned division lines by the shield tunnel formation process. [Figure 6]This is a perspective view showing an integral process embodiment of this model. [Figure 7] This is a perspective view showing how to remove a substrate from a sealant. [Figure 8] This is a side view showing an enlarged portion of an embodiment of the division process. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments relating to a wafer processing method constructed according to the present invention will be described in detail with reference to the attached drawings.

[0013] Figure 1 shows a wafer 10, which is an example of a workpiece used in the wafer processing method of this embodiment. The wafer 10 is a circular plate-shaped member with a diameter of 200 mm and a thickness of 1.1 mm, formed, for example, from quartz glass. The wafer 10 comprises a central product region 16 where multiple 5 mm square products 12, demarcated by division lines 14, are formed, and an outer peripheral excess region 18 surrounding the product region 16. In Figure 1, for illustrative purposes, the division lines 14 are shown wide, but in reality, the division lines 14 follow the outer shape of the products 12 and are set to a width of about 10 μm, where the shield tunnel 100, which serves as the starting point for division during the division process described later, is formed. The products 12 produced by the wafer processing method of this embodiment are 5 mm square plate-shaped members of quartz glass that are divided into individual pieces by the division process described later. Note that the product 12 and planned division lines 14 indicated on the surface 10a of the wafer 10 shown in the illustration are included for illustrative purposes only. In the actual wafer 10, the product 12 and planned division lines 14 are not visible, and there is no visual difference between the surface 10a and the opposite back surface 10b of the wafer 10. Therefore, the surface 10a and back surface 10b are added for illustrative purposes only.

[0014] The wafer processing method of this embodiment for processing the wafer 10 described above will be explained below.

[0015] (Substrate preparation process) When implementing the method for processing a wafer of the present invention, a substrate preparation step described below is carried out. In FIG. 2(a), a substrate 20 prepared in the substrate preparation step of the present embodiment is shown. The illustrated substrate 20 includes an annular convex portion 22 corresponding to the outer peripheral surplus region 18 of the wafer 10 described above and a concave portion 24 surrounded by the convex portion 22 and corresponding to the product region 16 of the wafer 10 described above.

[0016] The substrate 20 is formed of, for example, silicon (Si). For the substrate 20, a circular plate-like member of silicon with a diameter of 200 mm and a thickness of 1.0 mm is prepared, and a region closer to the center corresponding to the product region 16 of the wafer 10 described above is ground by, for example, grinding means in which a plurality of grinding wheels are arranged annularly and configured to be rotatable, whereby the concave portion 24 is formed. As a result, as understood from FIG. 2(b) showing the cross section A-A of FIG. 2(a), for example, the width of the convex portion 22 in the substrate 20 is 5 mm and the depth of the concave portion 24 is 0.2 mm. Note that the shape and dimensions of the substrate of the present invention are set corresponding to the workpiece and are not limited to the above-described shape and dimensions. Also, in FIG. 2(b), for convenience of explanation, it is described as being different from the actual dimension ratio.

[0017] (Sealing step) If the substrate 20 is prepared as described above, as shown in FIG. 3, a sealing step is carried out to form a sealed body W in which the product region 16 of the wafer 10 and the concave portion 24 of the substrate 20 are opposed and sealed.

[0018] More specifically, first, an adhesive 30 such as a UV curable resin or an epoxy resin is disposed on the upper surface of the convex portion 22 of the substrate 20 described above. The adhesive 30 is not particularly limited, but for example, a heat releasable tape "Revival Alpha" (registered trademark) manufactured by Nitto Denko Corporation can be used. Then, the substrate 20 is placed in a working chamber with a high-pressure atmosphere slightly higher than the standard atmospheric pressure (1 atm), for example, 1.1 atm. As shown in FIG. 3, the product region 16 of the wafer 10 and the concave portion 24 of the substrate 20 are opposed to each other and adhered through the adhesive 30 to form a sealed body W in which gas is sealed in the internal space S (see FIG. 5(b)) by the concave portion 24 of the wafer 10 and the substrate 20. The pressure in the working chamber with the high-pressure atmosphere described above is set to a pressure such that, for example, when the sealed body W is taken out under the standard atmospheric pressure and the wafer 10 side is directed upward, the weight of the product region 16 of the wafer 10 can be supported by the high-pressure gas sealed in the sealed body W and the back surface 10b can be maintained flat.

[0019] (Shield tunnel forming step) In order to divide the wafer 10 constituting the sealed body W described above into individual products 12, a shield tunnel forming step is performed in which a pulsed laser beam is irradiated onto a division planned line 14 along the outer shape of the product 12 to form pores reaching from the upper surface to the lower surface. When performing the shield tunnel forming step, the sealed body W described above is transported to a laser processing apparatus 40 (only a part is shown) shown in FIGS. 4 and 5.

[0020] The laser processing apparatus 40 comprises at least a chuck table 42 shown in Figure 4, a laser beam irradiation means 44 shown in Figure 5(a), and control means (not shown). As shown in Figure 4, the chuck table 42 comprises a holding surface 42a made of a breathable material and a frame 42b surrounding the holding surface 42a. A suction means (not shown) is connected to the holding surface 42a via the frame 42b, and by operating the suction means, negative pressure can be generated on the holding surface 42a. The chuck table 42 comprises an X-axis feed means (not shown) for moving the chuck table 42 in the X-axis direction shown in Figure 5(a), a Y-axis feed means (not shown) for moving the chuck table 42 in the Y-axis direction perpendicular to the X-axis direction shown, and a rotational drive means for rotating the chuck table 42.

[0021] The laser beam irradiation means 44 includes an optical system (not shown) including an oscillator that emits a pulsed laser beam LB, and a concentrator 45 including a concentrating lens (not shown) that focuses the pulsed laser beam LB and irradiates the wafer 10. The laser beam irradiation means 44 of this embodiment further includes a Z-axis feed means for moving the focal point of the pulsed laser beam LB irradiated from the concentrator 45 in the vertical direction (Z-axis direction). If the laser processing apparatus 40 is a laser processing apparatus with a fixed focal point position, the Z-axis feed means for moving the chuck table 42 in the vertical direction is provided on the chuck table 42 side.

[0022] Once the above-described sealing body W is transported to the laser processing apparatus 40, as shown in Figure 4, the back surface 10b of the wafer 10 is placed on the holding surface 42a of the chuck table 42 with the back surface 10b facing upwards, and the suction means is activated to hold it in place by suction. The shield tunnel formation process of this embodiment includes, for example, performing the following steps.

[0023] (Magnification number setting step) In this embodiment, in order to form a shield tunnel, the numerical aperture (NA) of the focusing lens that focuses the pulsed laser beam LB emitted by the laser beam irradiation means 44 is set such that the value obtained by dividing the numerical aperture (NA) of the focusing lens by the refractive index (N=1.44) of the quartz glass constituting the wafer 10 (NA / N) is in the range of 0.05 to 0.2. In this embodiment, the numerical aperture (NA) of the focusing lens is set to 0.25. Note that the timing at which the above numerical aperture setting step is performed is not particularly limited and may be performed before the sealing body W is transported to the laser processing apparatus 40.

[0024] (Positioning step, shield tunnel formation step) With the focusing lens of the light condenser 45 set to an appropriate numerical aperture in the numerical aperture setting step described above, a positioning step is performed in which the Z-axis feed means is operated to position the focusing lens and the wafer 10 relative to each other in the optical axis direction, so that the focusing point P of the pulsed laser beam LB irradiated from the laser beam irradiation means 44 is positioned at a desired position in the thickness direction of the wafer 10, as shown in Figure 5(b).

[0025] In executing the positioning step of this embodiment, the X-axis feed means and Y-axis feed means described above are activated to position the chuck table 42, on which the sealing body W is held by suction, directly below an alignment means (not shown). Then, alignment is performed by the alignment means, and the wafer 10 constituting the sealing body W held by suction on the chuck table 42 is imaged to detect the processing location (XY coordinates of the division line 14 described above) where the pulsed laser beam LB will be irradiated by the laser beam irradiation means 44, and the height (Z coordinate) of the back surface 10b of the wafer 10 at the XY coordinates of the division line 14, and these are stored in a control means (not shown).

[0026] Once the position information (XY coordinates) of the planned division line 14 on the wafer 10 and the height (Z coordinate) of the back surface 10b, detected by the alignment means described above, are stored in the control means, a predetermined processing start position (XY coordinates) of the planned division line 14 is positioned directly below the concentrator 45 based on the position information regarding the XY coordinates of the planned division line 14 and the height (Z coordinate) of the back surface 10b, in order to form a shield tunnel 100 along the planned division line 14. Next, the Z-axis feed means is activated to move the focal point P in the optical axis direction (Z direction) to position the focal point P at a desired depth position on the wafer 10 (positioning step).

[0027] Then, when forming the shield tunnel 100, as shown in Figures 5(a) and (b), the focal point P of the pulsed laser beam LB is positioned at a desired depth and irradiated, and the X-axis feed means is operated to feed the chuck table 42 in the X-axis direction for processing. In the shield tunnel formation process of this embodiment, the focal point P of the pulsed laser beam LB is changed multiple times from a shallow position on the upper surface to a deep position, and irradiated five times (five passes) to form a shield tunnel 100 that includes pores 102 extending from the back surface 10b (upper surface) to the front surface 10a (lower surface) of the wafer 10, and a modified material 104 that shields the pores 102, as shown in Figure 5(b).

[0028] In this manner, once the shield tunnel 100 is formed along the predetermined division line 14, the Y-axis feed means is activated to index and feed the wafer 10 in the Y-axis direction by the interval of the division line 14, positioning adjacent unprocessed division lines 14 in the Y-axis direction directly below the concentrator 45. Then, in the same manner as described above, the focal point P of the pulsed laser beam LB is positioned at a predetermined depth position on the division line 14 of the wafer 10 and irradiated, thereby processing and feeding the wafer 10 in the X-axis direction. Similarly, the wafer 10 is processed and fed in the X-axis and Y-axis directions to form shield tunnels 100 along all division lines 14 along the X-axis direction.

[0029] Next, the rotational drive means described above is activated to rotate the chuck table 42 by 90 degrees, aligning the unprocessed division line 14 perpendicular to the division line 14 in which the shield tunnel 100 has already been formed, in the X-axis direction. Then, the same shield tunnel 100 as described above is formed along each of the remaining division lines 14 by positioning the focal point P of the pulsed laser beam LB and irradiating it in the same manner as described above (shield tunnel formation step).

[0030] As described above, the encapsulant W of this embodiment is formed by positioning the excess outer peripheral region 18 of the wafer 10 on the protrusion 22 of the substrate 20 and attaching it via an adhesive 30, thereby sealing the product region 16 of the wafer 10 and the recess 24 of the substrate 20 facing each other. As shown in Figure 5(b), a space S is formed between the surface 10a of the wafer 10 and the recess 24 of the substrate 20. Therefore, the dust 19 generated when the pores 102 of the shield tunnel 100 are formed in the shield tunnel formation process described above falls from the pores 102 and is contained in the recess 24 of the substrate 20 that constitutes the space S. This prevents the dust 19 from accumulating in the pores 102 that constitute the shield tunnel 100 and blocking the pores 102, and eliminates the problem of the pores 102 being contaminated by the dust 19 and the dust 19 scattering and contaminating the surroundings in a later process (e.g., a splitting process).

[0031] By performing the shield tunnel formation process described above, shield tunnels 100 are formed along all the planned division lines 14, as shown in Figure 5(c). In this embodiment, the wafer 10 and the substrate 20 are bonded together via an adhesive 30, and the encapsulant W is formed in a high-pressure atmosphere (e.g., 1.1 atmospheres) working chamber. The shield tunnel formation process described above forms numerous shield tunnels 100 along with pores 102 that penetrate vertically. However, the diameter of these pores 102 is very small, for example, about 5 μm, and only a small amount of air escapes from these pores 102. Therefore, problems such as high-pressure gas escaping from the space S inside the encapsulant W and changing the height of the back surface 10b do not occur during the shield tunnel formation process.

[0032] Furthermore, the sealing step in the wafer processing method of the present invention is not necessarily limited to being carried out under the high-pressure atmosphere described above, but may also be carried out under standard atmospheric pressure. In that case, it is assumed that the back surface 10b of the wafer 10 will have a slightly concave shape due to the weight of the wafer 10, but by detecting the height of the back surface 10b of the wafer 10 along the division line 14 by the alignment performed in the positioning step of the shield tunnel formation process described above, it is possible to position the focal point of the pulsed laser beam LB at a desired depth in the wafer 10.

[0033] The processing conditions for the laser processing performed in the shield tunnel formation process described above are set as follows, for example. Wavelength: 1030nm Repetition frequency: 50kHz Pulse width: 200 fs ~ 10 ps Average output: 2.5W Machining feed rate: 500 mm / s Defocus of the condensing point: 0mm, 0.1mm, 0.2mm, 0.4mm from the top surface. It is set to 0.6mm (5 passes).

[0034] (Integrated process, split process) Once the shield tunnel formation process described above has been carried out, a division process is performed to divide the wafer 10 into individual products 12, using the shield tunnel 100 formed along the planned division line 14 of the wafer 10 as a starting point. Preferably, before carrying out the division process of this embodiment, the integration process described below is carried out. To carry out this integration process, for example, as shown in Figure 6, an annular frame F having an opening Fa capable of accommodating the wafer 10 is prepared, and the opening Fa of the frame F is positioned on the back surface 10b (top surface) of the wafer 10 and an adhesive tape T is attached. Then, as shown in Figure 7, the substrate 20 constituting the sealant W is peeled off and removed from the wafer 10. In this embodiment, since the sealant W integrates the substrate 20 and the wafer 10 via the heat-release tape "Riva Alpha" (registered trademark) which functions as an adhesive 30, as described above, the substrate 20 can be easily removed from the wafer 10 by heating the outer circumference of the sealant W. In practice, the removal of the substrate 20 is performed with the tape T side facing upwards and the substrate 20 facing downwards. This completes the integrated process of integrating the wafer 10 and the frame F.

[0035] The splitting process can be carried out using various methods, for example, by the splitting device 50 shown in Figure 8 (only a portion is shown). The illustrated splitting device 50 comprises a pair of support bases 54, 54 spaced a predetermined distance apart, and a wedge-shaped splitting bar 52 with an acute-angled tip 52a that applies an external force along the direction of formation of the shield tunnel 100 of the wafer 10 supported by the support bases 54, 54. The splitting bar 52 is driven by, for example, an air cylinder (not shown).

[0036] When performing the splitting process to divide the wafer 10 into individual products 12 using the splitting device 50 described above, the wafer 10 is mounted between a pair of support bases 54, 54, as shown in Figure 8, so that the shield tunnel 100, which serves as the splitting starting point, is positioned between them. In this case, it is preferable to place the wafer 10 with the tape T side facing upward and the surface 10a of the wafer 10, which is integrated with the frame F, facing downward, that is, towards the pair of support bases 54, 54. Then, the wedge-shaped splitting bar 52 having an acute-angled tip 52a is moved downward as indicated by arrow R1, and the acute-angled tip 52a of the splitting bar 52 is pressed along the planned splitting line 14 on the wafer 10 where the shield tunnel 100 is formed, via the tape T. This pressing is performed along all planned splitting lines 14 while changing the pressing position of the acute-angled tip 52a. As a result, as shown in Figure 7, a dividing groove 110 is formed that divides the wafer 10 into individual 5 mm square products 12, using the shield tunnel 100 as a starting point, completing the dividing process and ending the wafer processing method of this embodiment. Note that the present invention is not necessarily limited to pressing from the tape T side as shown in the figure, and the acute-angled tip 52a may be pressed from the surface 10a side of the wafer 10. However, when dividing by pressing from the back surface 10b side via the tape T as described above, the pressing force is applied so that adjacent products 12 sandwiching the shield tunnel 100 are separated, forming the dividing groove 110, which is preferable because it prevents chipping on the outer circumference of the product 12.

[0037] The specific method for carrying out the splitting process is not limited to using the splitting device 50 described above. For example, the wafer 10 can be placed on a flexible mat-like surface, and the wafer 10 can be rolled over from above while being pressed by a roller whose longitudinal direction is aligned with the formation direction of the shield tunnel 100, thereby splitting the wafer 10 into individual products 12 using the shield tunnel 100 as a starting point. Furthermore, if it is possible to split the wafer 10 into individual products 12 using the shield tunnel 100 as a starting point by expanding the tape T, the expansion process described later can also serve as the splitting process.

[0038] (Expansion process) In the wafer processing method of this embodiment, after performing the division step described above, as shown in Figure 7, an expansion step is performed in which the tape T is expanded in the radial direction indicated by arrow R2 in the figure by an appropriate method, thereby expanding the spacing between adjacent products 12 on the wafer 10. This is preferable because it makes it easier to pick up the products 12 that have been divided in the division step from the tape T which is integrated by the frame F and transport them to the next step.

[0039] In the embodiment described above, a shield tunnel 100 is formed along a linear division line 14 set in a grid pattern on the wafer 10, and the wafer 10 is divided using the shield tunnel 100 as a starting point to form a rectangular product 12 with a 5 mm square shape. However, the shape of the product formed by the wafer processing method of the present invention is not limited to this. For example, a circular plate-shaped member may be produced as the product, or any shape drawn by a free curve may be processed as the product. Even in such cases, a shield tunnel formation step can be performed in which the pulsed laser beam is irradiated along the division line along the outer shape of the product to form a shield tunnel 100 containing pores 102 extending from the top surface to the bottom surface, and a division step can be performed using the shield tunnel 100 as a starting point to produce a product of the desired shape.

[0040] Although the wafer 10 processed by the wafer processing method of the above-described embodiment was made of quartz glass, the present invention is not limited to this. For example, even if the wafer to be processed is made of a plate-like material such as sapphire, silicon carbide (SiC), gallium nitride (GaN), lithium tantalate (LT), or lithium niobate (LN), the same effects and advantages as those of the above-described embodiment can be obtained. [Explanation of symbols]

[0041] 10: Wafer 10a: surface 10b: Back side 12: Devices 14: Planned division line 16: Product area 18: Peripheral surplus area 19: Dust 20: Substrate 22: Convex part 24: Recess 30: Adhesive 40: Laser processing equipment 42: Chuck Table 44: Laser beam irradiation means 45: Light concentrator 50: Splitting device 52: Split bar 54: Support stand 100: Shield tunnel 102: Pores 104: Transformed body 110: Dividing groove F: Frame S: Space T: Tape W: Encapsulation body

Claims

1. A wafer processing method for processing a wafer having a product region on which a product is formed and an outer peripheral excess region surrounding the product region into a product, A substrate preparation step of preparing a substrate having an annular protrusion corresponding to the excess outer peripheral region and a recess surrounded by the protrusion corresponding to the product region, A sealing step in which the excess outer peripheral region of the wafer is positioned on the protrusion and attached via an adhesive to form a sealed body in which the product region of the wafer and the recess of the substrate are facing each other, A shield tunnel formation step involves irradiating a pulsed laser beam along a planned division line in line with the outer shape of the product in order to process the wafer of the encapsulation into a product, thereby growing pores from the top surface to the bottom surface of the wafer and a modified material that shields these pores to form a shield tunnel, and A wafer processing method comprising a splitting step of splitting a wafer into products using a shield tunnel formed on a line to be split as a starting point.

2. In the shield tunnel formation process, A numerical aperture setting step involves setting the numerical aperture (NA) of the focusing lens so that the value obtained by dividing the numerical aperture (NA) of the focusing lens by the refractive index (N) of the wafer (NA / N) is in the range of 0.05 to 0.2, and A positioning step involves positioning the focusing lens and the wafer relative to each other in the optical axis direction so that the focal point of the pulsed laser beam is located at a desired position in the thickness direction of the wafer, A method for processing a wafer according to claim 1, comprising a shield tunnel forming step of irradiating a pulsed laser beam to grow pores and a modified material that shields the pores to form the shield tunnel.

3. A wafer processing method according to claim 1, comprising an integration step of integrating the wafer and the frame by positioning the opening of a frame having an opening in the center for housing the wafer on the upper surface of the wafer and attaching tape to it before the splitting step.

4. The wafer processing method according to claim 2, further comprising an expansion step of expanding the tape after the splitting step to increase the spacing between adjacent products.

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