Wafer and wafer manufacturing method

Abstract

To provide a wafer having marks that can be detected without changing a sensor and that can expand the area for forming a device.SOLUTION: A wafer (10) is provided with a through hole (20) that penetrates the wafer in the thickness direction as a mark indicating the crystal orientation of the wafer.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a wafer and a method for manufacturing the wafer. [Background technology]

[0002] As disclosed in Patent Documents 1 and 2, crystalline wafers such as silicon wafers are formed with marks indicating crystal orientation, such as an orientation flat formed as a straight line on part of the periphery or a notch formed by cutting out part of the periphery. Also, as disclosed in Patent Document 3, this type of mark may be formed in two places on the wafer.

[0003] In a wafer, devices cannot be formed on the orientation flat or notch, and therefore the area for forming devices cannot be expanded due to the constraints imposed by the orientation flat or notch. To solve this problem, a technique has been proposed in which a mark indicating the crystal orientation is formed inside the wafer (inside in the thickness direction), as disclosed in Patent Document 4. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-003773 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-221393 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-134374 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-055139 Summary of the Invention [Problem to be solved by the invention]

[0005] When a mark is formed inside a wafer, the sensor that was previously used to detect orientation flats and notches in the equipment that processes or processes the wafer cannot detect the mark, so the sensor must be changed, which is costly and time-consuming.

[0006] Therefore, there is a need for a wafer having marks that can be detected without changing the sensor and that can expand the area in which devices are formed, and a method for manufacturing such a wafer. [Means for solving the problem]

[0007] A wafer according to one aspect of the present invention includes a through-hole that penetrates the wafer in the thickness direction as a mark indicating the crystal orientation of the wafer.

[0008] As an example, the through-hole is provided in a chamfered portion formed on the outer periphery of the wafer, or the through-hole is provided in the outer periphery of the wafer, on the inside of the chamfered portion formed on the outer periphery of the wafer.

[0009] The wafer may have a ring-shaped reinforcing portion formed on the outer periphery thereof, and a recessed portion located radially inward of the reinforcing portion, and the through-hole may be provided in the reinforcing portion.

[0010] A wafer according to one aspect of the present invention includes a recess in a chamfer formed on the outer periphery of the wafer, the recess having a depth in the radial direction of the wafer, as a mark indicating the crystal orientation of the wafer.

[0011] One aspect of the present invention is a wafer manufacturing method for manufacturing wafers from sliced ​​wafers obtained by slicing an ingot, the method including a planarization step for planarizing both surfaces of the sliced ​​wafer, a contour shaping step for shaping the outer shape of the sliced ​​wafer and forming a chamfered portion, and a mark formation step for forming a through hole penetrating in the thickness direction in the outer peripheral portion of the sliced ​​wafer that has undergone the planarization step or the contour shaping step.

[0012] One aspect of the present invention is a wafer manufacturing method for manufacturing wafers from sliced ​​wafers obtained by slicing an ingot, the method including: a planarization step for planarizing both surfaces of the sliced ​​wafer; a contour shaping step for shaping the outer shape of the sliced ​​wafer to form a chamfered portion; and a mark formation step for forming a recess having a radial depth in the chamfered portion on the outer periphery of the sliced ​​wafer that has undergone the planarization step or the contour shaping step. [Effects of the Invention]

[0013] According to the wafer and its manufacturing method of each aspect described above, the mark indicating the crystal orientation can be a through-hole penetrating the wafer in the thickness direction or a recessed portion provided in the chamfered portion with a depth in the radial direction of the wafer, thereby enabling detection without changing the sensor. Furthermore, by using such a through-hole or recessed portion as the mark indicating the crystal orientation, the area on the wafer where devices are formed can be expanded. [Brief explanation of the drawings]

[0014] [Figure 1] 3A to 3C are diagrams illustrating a planarization step for manufacturing a wafer according to the first embodiment. [Figure 2] 5A to 5C are diagrams illustrating a contour shaping step for manufacturing a wafer according to the first embodiment. [Figure 3] 3A to 3C are diagrams illustrating a mark forming step for manufacturing a wafer according to the first embodiment. [Figure 4] FIG. 2 is a diagram showing a laser processing device used in a mark forming step. [Figure 5] FIG. 2 is a diagram showing the wafer according to the first embodiment after marks have been formed. [Figure 6] 10A to 10C are diagrams illustrating a mark forming step for manufacturing a wafer according to the second embodiment. [Figure 7] 10A to 10C are diagrams illustrating a mark forming step for manufacturing a wafer according to the third embodiment. [Figure 8] 10A to 10C are diagrams illustrating a mark forming step for manufacturing a wafer according to the fourth embodiment. [Figure 9] 10A to 10C are diagrams illustrating a mark forming step for manufacturing a wafer according to the fourth embodiment. [Figure 10] FIG. 10 is a diagram showing a wafer according to the fourth embodiment after marks have been formed. [Figure 11] FIG. 10 is a diagram showing a wafer according to the fifth embodiment after marks have been formed. [Figure 12] FIG. 13 is a diagram showing a wafer according to the sixth embodiment after marks have been formed. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of a wafer to which the present invention is applied and a method for manufacturing the same will be described with reference to the drawings. Figures 1 to 3 show the steps of manufacturing a wafer of the first embodiment, with Figure 1 showing the planarization step, Figure 2 showing the contour shaping step, and Figure 3 showing the mark formation step. Figure 4 shows a laser processing device 40, which is an example of a manufacturing device used in the mark formation step. Figure 5 shows a wafer 10 manufactured through the above steps.

[0016] The wafer 10 is, for example, a silicon wafer. In the following description, the thickness direction of the wafer 10 (or sliced ​​wafers 11 before the wafer 10 is completed) is defined as the Z-axis direction. In addition, for the laser processing device 40, the Z-axis direction is the up-down direction, and the X-axis and Y-axis directions are horizontal directions perpendicular to the Z-axis direction. The X-axis and Y-axis directions are perpendicular to each other.

[0017] As shown in FIG. 1 , a cylindrical ingot is sliced ​​into disks using a cutting device such as a wire saw to form sliced ​​wafers 11, and a planarization process is then performed using a grinding device (not shown) to flatten both surfaces of the sliced ​​wafers 11. Waviness, distortion, and cutting marks on both surfaces that occur when the sliced ​​wafers 11 are formed from the ingot are removed in the planarization process. The two surfaces of the sliced ​​wafer 11 that have been flattened in the planarization process are designated as a first surface 12 and a second surface 13. The outer periphery of the sliced ​​wafer 11 after being cut from the ingot forms a cylindrical outer periphery 14 that connects the first surface 12 and the second surface 13.

[0018] In the contour shaping step shown in FIG. 2 , which is performed following the flattening step, the contour of the sliced ​​wafer 11 is shaped by a chamfering device (not shown) to form a chamfered portion 15 on the outer periphery. The chamfered portion 15 is formed by tapering the corners at the boundary between the first surface 12 and the outer periphery 14 into tapered surfaces 16 and tapering the corners at the boundary between the second surface 13 and the outer periphery 14 into tapered surfaces 17. As shown enlarged in FIG. 3 , the tapered surfaces 16 and 17 are inclined so that the distance between them in the Z-axis direction decreases as they approach the outer periphery 14 in the radial direction of the sliced ​​wafer 11 (i.e., as they proceed toward the outer diameter of the sliced ​​wafer 11). Forming the chamfered portion 15, which has a shape where the corners of the outer periphery of the sliced ​​wafer 11 are rounded, improves the mechanical strength of the sliced ​​wafer 11, making it less susceptible to cracking or chipping.

[0019] The chamfering device is, for example, a grinding device equipped with a grinding wheel for chamfering, and the grinding wheel for chamfering is rotated while being brought into contact with the outer periphery of the sliced ​​wafers 11 to form the tapered surfaces 16 and 17. Alternatively, the chamfering device may be a laser processing device that forms the tapered surfaces 16 and 17 by irradiating them with a laser beam.

[0020] Alternatively, the contour shaping step may be performed first to form the chamfered portion 15 on the outer periphery of the sliced ​​wafer 11, and then the flattening step may be performed to flatten both surfaces of the sliced ​​wafer 11.

[0021] In the mark forming step shown in Fig. 3, through holes 20 are formed as marks indicating crystal orientation in the outer peripheral portion of the sliced ​​wafer 11 that has been subjected to the planarization step and the contour shaping step. By forming the through holes 20, the wafer 10 shown in Fig. 5 is completed. In this mark forming step, laser processing is performed using a laser processing device 40, and a laser beam is irradiated in the Z-axis direction toward the chamfered portion 15 of the sliced ​​wafer 11 to form the through holes 20 that penetrate the sliced ​​wafer 11 in the thickness direction (Z-axis direction).

[0022] 3, the laser processing device 40 includes a laser oscillator 41, a water source 42, and a processing head 43. The processing head 43 includes a focusing optical system that focuses the laser beam L emitted from the laser oscillator 41 and irradiates it downward. The processing head 43 also includes a supply port that supplies water from the water source 42 downward along the optical axis of the focusing optical system. The laser beam L passes through the supply port and is irradiated downward.

[0023] When processing the sliced ​​wafers 11 with the laser beam L, water is supplied from a water source 42 to form a liquid column from the processing head 43 to the sliced ​​wafers 11 below, and the laser beam L oscillated from a laser oscillator 41 is transmitted through the liquid column and irradiated onto the sliced ​​wafers 11. By guiding the laser beam L to the sliced ​​wafers 11 through water, debris generated by laser processing is removed, deterioration of the sliced ​​wafers 11 due to heat is prevented, and high-precision, fine processing can be performed.

[0024] It should be noted that the formation of a liquid column is not essential during laser processing. A suction port may be disposed near or surrounding the processing point where the laser beam L is irradiated, and debris may be sucked in. An air nozzle that injects air near the processing point may be provided, and the air injected from the air nozzle may blow away the debris, preventing it from adhering. Both an air nozzle and a suction port may also be disposed.

[0025] 4 shows the overall structure of laser processing apparatus 40. Laser processing apparatus 40 supports a chuck table 48 via an X-axis movement mechanism 45, a Y-axis movement mechanism 46, and a rotation mechanism 47, which are provided on a base 44. X-axis movement mechanism 45 moves chuck table 48 in the X-axis direction, Y-axis movement mechanism 46 moves chuck table 48 in the Y-axis direction, and rotation mechanism 47 rotates chuck table 48 around an axis in the Z-axis direction.

[0026] The X-axis moving mechanism 45 supports an X-axis table 452 on a guide rail 451 that is provided on the upper surface of the base 44 and extends in the X-axis direction, and moves the X-axis table 452 in the X-axis direction along the guide rail 451 by rotating a ball screw 453 that extends in the X-axis direction using a motor 454.

[0027] The Y-axis moving mechanism 46 supports the Y-axis table 462 on a guide rail 461 that is provided on the upper surface of the X-axis table 452 and extends in the Y-axis direction, and moves the Y-axis table 462 in the X-axis direction along the guide rail 461 by rotating a ball screw 463 that extends in the Y-axis direction with a motor 464.

[0028] The rotation mechanism 47 is supported on the Y-axis table 462, and supports the chuck table 48 rotatably relative to a support plate 471. The chuck table 48 is rotated by driving a motor (not shown).

[0029] The chuck table 48 is connected to a suction source (not shown), and is capable of suction-holding the sliced ​​wafer 11 on the holding surface, which is the upper surface of the chuck table 48. As shown in Fig. 3, the diameter of the chuck table 48 is smaller than the diameter of the sliced ​​wafer 11, and the outer periphery of the sliced ​​wafer 11, including the region where the chamfered portion 15 is formed, is held in a state where it protrudes outside the holding surface of the chuck table 48.

[0030] The machining head 43 is provided in a machining unit 49. A laser oscillator 41 (see FIG. 3) and a water source 42 (see FIG. 3) are provided inside the machining unit 49. The machining unit 49 including the machining head 43 is supported by a support block 50 protruding from the upper surface of the base 44, and is moved in the Z-axis direction by a Z-axis movement mechanism 51. The Z-axis movement mechanism 51 supports the machining unit 49 by a guide rail 511 provided on the support block 50 and extending in the Z-axis direction, and moves the machining unit 49 in the Z-axis direction along the guide rail 511 by rotating a ball screw 512 extending in the Z-axis direction with a motor 513.

[0031] The processing unit 49 is provided with a camera 52 near the processing head 43. The camera 52 captures an image of the area below, and the processing head 43 can be aligned with the sliced ​​wafer 11 held on the chuck table 48 based on the captured image.

[0032] When the laser processing device 40 forms the through holes 20 in the sliced ​​wafer 11, the sliced ​​wafer 11 is sucked and held on the holding surface of the chuck table 48. The control unit of the laser processing device 40 operates the X-axis movement mechanism 45, the Y-axis movement mechanism 46, and the rotation mechanism 47 to change the relative positions of the sliced ​​wafer 11 and the processing head 43 in the horizontal direction, and positions the chamfering portion 15 directly below the processing head 43 while capturing an image of the position of the sliced ​​wafer 11 with the camera 52. More specifically, the location where the through holes 20 are to be formed is positioned on the optical axis of the focusing optical system of the processing head 43 that irradiates the laser beam L.

[0033] Next, the position of the processing head 43 in the Z-axis direction is adjusted by the Z-axis moving mechanism 51 so that the focal point of the laser beam L is at a predetermined position in the thickness direction of the sliced ​​wafer 11, and water from a water source 42 is supplied from the processing head 43 to the sliced ​​wafer 11 to form a liquid column, while the laser beam L oscillated from the laser oscillator 41 is irradiated onto the sliced ​​wafer 11. Then, by appropriately adjusting the radial and circumferential directions of the through-hole 20 that forms the irradiation position of the laser beam L, the through-hole 20 that penetrates the sliced ​​wafer 11 in the thickness direction is formed.

[0034] The processing conditions for forming the through-hole 20 by laser processing using the laser processing device 40 are, for example, as follows: The laser oscillator 41 oscillates, as the laser beam L, a pulsed laser beam having a wavelength of 355 nm, a repetition frequency of 20 kHz, a pulse width of 10 ps, ​​and an average output of 0.8 W. The focal length of the focusing optical system of the processing head 43 is 100 mm. The through-hole 20 is a circular through-hole having a diameter of 100 μm. The position of the processing head 43 is adjusted by the Z-axis movement mechanism 51, and the focusing position of the laser beam L is positioned on the upper surface of the sliced ​​wafer 11 (in the case of the through-hole 20, the tapered surface 16, which is the upper surface of the chamfered portion 15). In this state, the laser beam L is irradiated from the processing head 43 while forming a liquid column. The X-axis moving mechanism 45 and the Y-axis moving mechanism 46 move the processing head 43 and the sliced ​​wafer 11 relatively in the horizontal direction, and the irradiation position (laser spot) of the laser beam L is changed along a circular trajectory along the circumferential direction of the through-hole 20. The moving speed of the irradiation position of the laser beam L in the circumferential direction, i.e., the processing feed speed, is set to 5 mm / s. This laser irradiation is performed multiple times along multiple circular movement trajectories with different diameters to process the through-hole 20 in a concentric manner. In the concentric processing, the processing interval in the radial direction of the through-hole 20 is set to 5 μm. The concentric processing is performed, for example, sequentially from the center to the periphery of the through-hole 20. The concentric processing from the center to the periphery of the through-hole 20 constitutes one processing set. After one processing set is completed, the irradiation position of the laser beam L is returned to the center of the through-hole 20, and the next processing set is performed concentrically from the center to the periphery. The through-hole 20 is completed by performing a total of 10 sets of processing.

[0035] In the above processing example, concentric machining from the center to the periphery of the through hole 20 is repeated in each of the n sets (n is any number equal to or greater than 2) of machining, but the present invention is not limited to this processing example. For example, concentric machining from the periphery to the center of the through hole 20 may be repeated in each of the n sets of machining. Alternatively, concentric machining from the center to the periphery of the through hole 20 may be performed in the first set, and concentric machining from the periphery to the center of the through hole 20 may be performed in the second set, with this process being repeated in a sequence of center, periphery, center, periphery, and so on. Conversely, concentric machining from the periphery to the center of the through hole 20 may be performed in the first set, and concentric machining from the center to the periphery of the through hole 20 in the second set, with this process being repeated in a sequence of periphery, center, periphery, and so on, for the n sets of machining.

[0036] Wafer 10 completed through the above steps has through holes 20, which are marks indicating crystal orientation, in chamfered portion 15 on the outer periphery, as shown in Fig. 5. One end of through hole 20 in the Z-axis direction opens to tapered surface 16, and the other end of through hole 20 opens to tapered surface 17.

[0037] The through-hole 20 configured in this manner has an opening shape exposed on the front and back of the wafer 10, and therefore can be identified by sensors conventionally used to detect orientation flats or notches, and does not require a special sensor to detect marks provided inside the wafer 10. Therefore, processing devices and processing equipment that process and treat the wafer 10 can be operated without changing the sensors for detecting the through-hole 20.

[0038] The through holes 20 are arranged not on both flattened surfaces (first surface 12, second surface 13) of the wafer 10 but on the chamfered portion 15 on the outer periphery thereof. Therefore, the area used for forming devices on the wafer 10 is not narrowed by the presence of the through holes 20, and it is possible to expand the area for forming devices.

[0039] The through-hole 20 has a shape that opens only on both sides of the chamfered portion 15 in the Z-axis direction, so that the outer peripheral surface 14, which is the surface shape of the outer peripheral edge of the wafer 10, can be left intact over the entire circumference. This configuration is useful when positioning (centering, etc.) the wafer 10 using the outer peripheral surface 14, and the mark indicating the crystal orientation does not interfere with positioning the wafer 10, improving work efficiency.

[0040] In conventional mark manufacturing, the shapes that become the base of the mark are formed together in the ingot, and due to limitations in the processing accuracy of the ingot, it is difficult to make the shapes of the orientation flat and notch in the sliced ​​wafers after cutting from the ingot uniform and small. In contrast, in the manufacturing method of this embodiment, the through holes 20 that serve as marks are formed one by one in the sliced ​​wafers 11 after cutting from the ingot, so processing accuracy is high and it is possible to achieve uniform shapes and small sizes of the through holes 20.

[0041] Furthermore, the through holes 20 formed using the laser processing device 40, which performs processing using the laser beam L from the processing head 43, can be made extremely small compared to the conventional orientation flats and notches formed by cutting an ingot, etc. Therefore, it is possible to form small through holes 20 that fit within the width of the chamfered portion 15 in the radial direction of the wafer 10.

[0042] The chamfered portion formed on the outer peripheral edge of the sliced ​​wafer 11 may have an arc-like cross-sectional shape, like the chamfered portion 18 of the wafer of the second embodiment shown in Fig. 6, instead of the polygonal cross-sectional shape shown in Fig. 3 and Fig. 5. This chamfered portion 18 has a structure in which the first surface 12 and the second surface 13 are connected by a curved surface that is convex toward the outer peripheral side of the sliced ​​wafer 11. As shown in Fig. 6, by forming a through-hole 21 that penetrates the sliced ​​wafer 11 in the thickness direction (Z-axis direction) of the chamfered portion 18 as a mark indicating the crystal orientation, the same effect as when the through-hole 20 is formed in the chamfered portion 15 described above can be obtained.

[0043] FIG. 7 shows a mark forming step for manufacturing a wafer according to the third embodiment. In the wafer according to the third embodiment, a through hole 22 is formed in the sliced ​​wafer 11 in the outer peripheral portion (portion of the first surface 12 and the second surface 13 closer to the outer periphery) inside the chamfered portion 15, penetrating the wafer in the thickness direction as a mark indicating the crystal orientation. One end of the through hole 22 opens to the first surface 12, and the other end of the through hole 21 opens to the second surface 13. The through hole 22 is formed using a laser processing device 40, similar to the through hole 20 described above. While FIG. 7 shows the chamfered portion 15 having a polygonal cross section formed on the outer peripheral edge of the sliced ​​wafer 11, the shape of the chamfered portion is not limited thereto and may be the chamfered portion 18 having an arc-shaped cross section shown in FIG. 6.

[0044] As with the through hole 20 in the wafer of the first embodiment, the through hole 22 formed by the laser processing device 40 can be made extremely small compared to existing orientation flats or notches. Therefore, even if the through hole 22 is provided in the outer peripheral portion inside the chamfered portion 15, the through hole 22 does not restrict the size of the device formation area compared to when an orientation flat or a notch is formed. Therefore, by using the through hole 22 as the mark, the effect of expanding the area in which devices are formed on the wafer is obtained.

[0045] As with the through holes 20 described above, the through holes 22 are shaped to open only on both sides of the wafer in the Z-axis direction, so that the outer peripheral surface 14, which is the surface shape of the outer peripheral edge of the wafer, can be left intact over the entire circumference, improving work efficiency when using the outer peripheral surface 14 to position the wafer. Furthermore, since the through holes 22, which serve as marks, are formed one by one in the sliced ​​wafers 11 after being cut from the ingot, high processing accuracy is achieved, and the shapes of the through holes 22 can be made uniform and small.

[0046] 8 to 10 show a wafer and its manufacturing process according to the fourth embodiment. In the wafer according to the fourth embodiment, a recess 23 having a depth in the radial direction of the sliced ​​wafer 11 is formed in the outer periphery of the sliced ​​wafer 11 as a mark indicating the crystal orientation. FIGS. 8 and 9 show a mark forming process performed after the flattening process and the contour shaping process, and FIG. 10 shows the wafer 10 manufactured through these processes. While FIGS. 8 to 10 show a chamfered portion 15 having a polygonal cross section formed on the outer periphery of the sliced ​​wafer 11, the shape of the chamfered portion is not limited thereto and may be a chamfered portion 18 having an arcuate cross section as shown in FIG. 6.

[0047] The mark forming process shown in Fig. 8 shows a case where recesses 23 are formed by laser processing using a laser processing device 60. The processing head 61 provided in the laser processing device 60 has only the function of irradiating a laser beam L toward the sliced ​​wafer 11 and does not form a liquid column. The configuration of the laser processing device 60 other than the processing head 61 is similar to that of the above-mentioned laser processing device 40 (see Fig. 4), and detailed description thereof will be omitted.

[0048] 5 and 10, the recesses 23, whose depth is in the radial direction of the sliced ​​wafer 11, have a larger opening area than the through-holes 20, which penetrate the sliced ​​wafer 11 in the thickness direction, and the laser processing device 40, which forms the through-holes 20, performs finer processing than the laser processing device 60, which forms the recesses 23. For this reason, the laser processing device 40 forms the through-holes 20 using a processing head 43 that forms a liquid column and irradiates the laser beam L. In contrast, the recesses 23 are formed by the laser processing device 60, which uses a processing head 61 that does not form a liquid column.

[0049] The laser processing device 60 adsorbs and holds the sliced ​​wafer 11 on the chuck table 62, and performs laser processing while adjusting the relative positions of the processing head 61 and the chuck table 62 so that the focal point of the laser beam L irradiated from the processing head 61 is at the position to be processed of the chamfered portion 15, thereby forming the recess 23.

[0050] The mark forming step shown in Figure 9 shows the case where recesses 23 are formed by cutting processing using a cutting device 70. A processing unit 71 of the cutting device 70 has a ring-shaped cutting blade 73 attached to a spindle 72 extending horizontally. The spindle 72 is rotated by a spindle motor (not shown). The cutting device 70 is provided with a processing feed mechanism (not shown) that moves the processing unit 71 in the Z-axis direction. It also has an alignment mechanism (not shown) that moves a chuck table 74 that suction-holds the sliced ​​wafers 11 and the processing unit 71 relative to each other in the horizontal direction.

[0051] The cutting device 70 suction-holds the sliced ​​wafer 11 on the chuck table 74, and aligns the processing unit 71 with the chuck table 74 using an alignment mechanism so that the cutting depth of the cutting blade 73 in the radial direction of the sliced ​​wafer 11 falls within the width of the chamfered portion 15. Then, while driving the spindle motor to rotate the spindle 72 and the cutting blade 73, the processing unit 71 is lowered in the -Z direction using the processing feed mechanism. The rotating cutting blade 73 cuts into the sliced ​​wafer 11 while moving in the Z-axis direction, thereby forming recesses 23.

[0052] 10, the wafer 10 completed through each process has a recess 23, which is a mark indicating the crystal orientation, in the chamfered portion 15. The recess 23 is formed with a uniform cross-sectional shape in the Z-axis direction, with one end of the recess 23 opening to the tapered surface 16 and the other end of the recess 23 opening to the tapered surface 17. The recess 23 also opens toward the outside in the radial direction of the sliced ​​wafer 11 and is recessed toward the inside in the radial direction with respect to the outer circumferential surface 14.

[0053] The recesses 23 configured in this manner have openings exposed on the front and back of the wafer 10, so they can be identified by sensors conventionally used to detect orientation flats or notches, and do not require special sensors to detect marks provided inside the wafer 10. Therefore, processing devices and processing equipment that process and treat the wafer 10 can be operated without changing the sensors for detecting the recesses 23.

[0054] The depth of the recesses 23 in the radial direction of the wafer 10 does not reach the positions of both flattened surfaces (first surface 12, second surface 13) of the wafer 10, but remains at the chamfered portion 15 on the outer periphery. In other words, the recesses 23 are formed only in the chamfered portion 15 on the outer periphery of the wafer 10. This prevents the area of ​​the wafer 10 used for device formation from being narrowed by the presence of the recesses 23, making it possible to expand the area for device formation.

[0055] Furthermore, since the recesses 23 serving as marks are formed one by one on the sliced ​​wafers 11 after being cut out from the ingot, high processing accuracy can be achieved, and the recesses 23 can be made uniform in shape and small in size.

[0056] The wafer 30 of the fifth embodiment shown in FIG. 11 differs from the wafer 10 of each of the above-described embodiments in that it has a circular recess 33 in the central portion (inner in the radial direction) on the first surface 31 side, and a ring-shaped reinforcing portion 34 that protrudes in the Z-axis direction from the recess 33 on the outer periphery on the first surface 31 side. In other words, on the second surface 32 side, a plurality of devices 35 are formed in an inner area that does not overlap with the reinforcing portion 34. The wafer 30 is thinned by grinding the central portion of the first surface 31 to form the recess 33, and the outer periphery is not ground to form the reinforcing portion 34. The wafer 30 configured in this manner is reinforced by the reinforcing portion 34, ensuring the thickness of the outer periphery, and is therefore less susceptible to breakage or deformation.

[0057] Tapered surfaces 36 and 37 are formed on reinforcing portion 34 provided on the outer peripheral edge of wafer 30. Tapered surfaces 36 and 37 are formed by rounding off the corners of reinforcing portion 34, similar to tapered surfaces 16 and 17 of wafer 10 of the first embodiment.

[0058] The wafer 30 has a through hole 38 that penetrates the reinforcing portion 34 in the thickness direction of the wafer as a mark indicating the crystal orientation of the wafer 30. The through hole 38 can be formed by laser processing using the above-mentioned laser processing device 40. When the material and thickness of the wafer 30 are the same as those of the wafer 10, the processing conditions for processing the through hole 38 can be set to be generally similar to the processing conditions for the above-mentioned through hole 20.

[0059] 11, a through hole 38 is formed in a region of the reinforcing portion 34 that is radially inward of the tapered surface 36 and the tapered surface 37 (i.e., radially inward of the chamfered portion). Note that the through hole 38 may be configured so that at least a portion thereof overlaps the tapered surface 36 and the tapered surface 37.

[0060] Because the opening shape of the through-hole 38 is exposed on the front and back of the wafer 30 at the reinforcing portion 34, it can be identified by a sensor that has been used to detect a conventional orientation flat or notch, and there is no need for a special sensor that detects a mark provided inside the wafer 30. Therefore, processing devices and processing equipment that process and treat the wafer 30 can be used without changing the sensor for detecting the through-hole 38.

[0061] The through holes 38 are arranged not in the area of ​​the recess 33 where the devices 35 are formed, but in the reinforcing portion 34 on the outer periphery thereof. Therefore, the area of ​​the wafer 30 used to form the devices 35 is not narrowed by the presence of the through holes 38, and a wide area for forming the devices 35 can be secured.

[0062] Furthermore, the through hole 38 is formed within the width of the reinforcing portion 34 in the radial direction of the wafer 30, and has a shape that does not break the ring-shaped reinforcing portion 34 along the way, so that the strength provided by the reinforcing portion 34 can be ensured around the entire circumference of the wafer 30.

[0063] Furthermore, the through holes 38 are open only on both sides of the reinforcing portion 34 in the Z-axis direction and do not change the shape of the outer peripheral surface of the reinforcing portion 34, so they do not affect the positioning (centering, etc.) of the wafer 30 based on the outer peripheral surface of the reinforcing portion 34.

[0064] The wafer 30 of the sixth embodiment shown in Fig. 12 is obtained by changing the arrangement of the marks indicating the crystal orientation from the wafer 30 of the fifth embodiment. As a mark indicating the crystal orientation, a through hole 39 is provided in the inner peripheral portion of the reinforcing portion 34 (an area near the outer periphery of the recess 33) that penetrates through the wafer 30 in the thickness direction. The through hole 39 can be formed by laser processing using the laser processing device 40 described above, similar to the through hole 38 shown in Fig. 11.

[0065] Because the opening shape of the through-hole 39 is exposed on the front and back of the wafer 30, it can be identified by sensors conventionally used to detect orientation flats or notches, and does not require a special sensor to detect marks provided inside the wafer 30. Therefore, processing devices and processing equipment that process and treat the wafer 30 can be operated without changing the sensors for detecting the through-hole 39.

[0066] The through holes 39 formed using the laser processing device 40 can be made smaller than existing orientation flats or notches. Therefore, even if the through holes 39 are provided at positions more inward than the reinforcing portions 34, the through holes 39 do not restrict the size of the device formation area as compared to when an orientation flat or a notch is formed. Therefore, by using the through holes 39 as marks, the effect of expanding the area in which devices are formed on the wafer 30 is obtained.

[0067] Furthermore, when through holes 39 are formed on the outer periphery of recess 33, there is no need to cut out the reinforcement portion 34 outside of recess 33, which is advantageous in that the strength of the reinforcement portion 34 can be ensured.

[0068] As described above, according to the wafers and wafer manufacturing methods of the embodiments to which the present invention is applied, by forming the mark indicating the crystal orientation as a through-hole penetrating the wafer in the thickness direction or a recess provided in the chamfered portion and having a depth in the radial direction of the wafer, detection is possible without changing the sensor, thereby improving the versatility of the apparatus for processing and treating the wafer. Furthermore, by forming the mark indicating the crystal orientation as such a through-hole or recess, the mark can be made smaller and arranged in a space-efficient manner, thereby expanding the area in which devices can be formed on the wafer.

[0069] The embodiments of the present invention are not limited to the above-described embodiments and modifications, and may be variously changed, substituted, or modified without departing from the spirit of the technical idea of ​​the present invention. Furthermore, if the technical idea of ​​the present invention can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention. [Industrial Applicability]

[0070] As described above, by applying the wafer and wafer manufacturing method of the present invention, the versatility of an apparatus equipped with a sensor for detecting marks indicating crystal orientation is improved, and it becomes possible to form devices on the wafer in a space-efficient manner, thereby achieving the effects of promoting efficiency and cost reduction in wafer processing and treatment. [Explanation of symbols]

[0071] 10: Wafer 11: Sliced ​​wafer 12: 1st page 13:Second side 14:Outer surface 15: Chamfered part 16: Tapered surface 17: Tapered surface 18: Chamfered part 20: Through hole (mark) 21: Through hole (mark) 22: Through hole (mark) 23: Recess (mark) 30: Wafer 31: 1st page 32: 2nd side 33: Recess 34: Reinforcement 35: Device 36: Tapered surface 37: Tapered surface 38: Through hole (mark) 39: Through hole (mark) 40: Laser processing equipment 41: Laser oscillator 42: Water source 43: Processing head 45:X-axis movement mechanism 46:Y-axis movement mechanism 47: Rotation mechanism 48: Chuck table 49: Processing unit 51:Z-axis movement mechanism 60: Laser processing equipment 61: Processing head 62: Chuck table 70: Cutting equipment 71: Processing unit 73: Cutting blade 74: Chuck table L: Laser beam

Claims

1. A wafer having a through-hole penetrating the wafer in a thickness direction as a mark indicating the crystal orientation of the wafer.

2. The wafer according to claim 1 , wherein the through-hole is provided in a chamfered portion formed on the outer periphery of the wafer.

3. 2. The wafer according to claim 1, wherein the through-hole is provided in the outer peripheral portion of the wafer, inside a chamfer formed on the outer peripheral edge of the wafer.

4. 2. The wafer according to claim 1, wherein the wafer has a ring-shaped reinforcing portion formed on an outer periphery thereof, a recessed portion radially inward from the reinforcing portion, and the through-hole is provided in the reinforcing portion.

5. A wafer having a recess whose depth extends in the radial direction of the wafer in a chamfered portion formed on the outer peripheral edge of the wafer as a mark indicating the crystal orientation of the wafer.

6. A wafer manufacturing method for manufacturing wafers from sliced ​​wafers obtained by slicing an ingot, comprising: a planarization step of planarizing both surfaces of the sliced ​​wafer; a contour shaping step of shaping the contour of the sliced ​​wafer to form a chamfered portion; a mark forming step of forming a through hole penetrating in the thickness direction in the outer peripheral portion of the sliced ​​wafer that has been subjected to the flattening step or the contour shaping step.

7. A wafer manufacturing method for manufacturing wafers from sliced ​​wafers obtained by slicing an ingot, comprising: a planarization step of planarizing both surfaces of the sliced ​​wafer; a contour shaping step of shaping the contour of the sliced ​​wafer to form a chamfered portion; a mark forming step of forming a recess having a depth in the radial direction in the chamfered portion on the outer periphery of the sliced ​​wafer that has been subjected to the flattening step or the contour shaping step; A method for manufacturing a wafer, comprising:

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