Method and device for cutting out small-diameter wafer

Abstract

To make it possible to efficiently cut out a small-diameter wafer in a short time without much time and labor.SOLUTION: In a method for cutting out a small-diameter wafer W2 from a large-diameter wafer W1 in which a mark M indicating a crystal orientation is formed in a part of an outer periphery while leaving the mark M, a tape attaching step of attaching a tape T to one surface of the large-diameter wafer W1, a wafer holding step of holding the large-diameter wafer W1 on a chuck table 10 via the tape T, a mark detecting step of detecting the mark M of the large-diameter wafer W1 by an imaging unit (mark detecting unit) 32, and a cutting step of moving one or both of the chuck table 10 and a cutting blade 34 in a horizontal plane while rotating the chuck table 10 so that a processing point P of the cutting blade (cutting means) 34 with respect to the large-diameter wafer W1 passes through the mark M and draws a circle in a plane of the large-diameter wafer W1 are conducted.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for slicing a small-diameter wafer from a wafer to obtain wafers having a smaller diameter than the wafer. [Background technology]

[0002] Marks such as V-notches and orientation flats that indicate the crystal orientation are formed on the outer periphery of a disk-shaped semiconductor wafer (hereinafter simply referred to as a "wafer"), and these marks are used as references for positioning the wafer.

[0003] Incidentally, a conventional method for slicing a wafer having a larger diameter (hereinafter referred to as a "large diameter wafer") into a wafer having a smaller diameter (hereinafter referred to as a "small diameter wafer") has been proposed in Patent Document 1.

[0004] However, when small-diameter wafers are cut out from large-diameter wafers using the method proposed in Patent Document 1, the cut small-diameter wafers do not contain marks such as V-notches or orientation flats that indicate crystal orientation. Therefore, these marks must be newly formed on part of the outer periphery of the small-diameter wafers, which requires a lot of time and effort.

[0005] Therefore, Patent Document 2 proposes a method for slicing small-diameter wafers while leaving marks formed on the large-diameter wafer. In this slicing method, as shown in Fig. 6, when a small-diameter wafer W2 having a diameter φD2 is slicing from a large-diameter wafer W1 having a diameter φD1 (>φD2), the large-diameter wafer W1 is supported on a ring frame F with its center O1 offset radially from the center O2 (the center of the small-diameter wafer W2) of the ring frame F by ε (= (φD1 - φD2) / 2) as shown in the figure so that the center O2 of the small-diameter wafer W2 coincides with the rotation center of a chuck table (not shown). Then, from this state, while rotating the chuck table together with the large-diameter wafer W1, a cutting blade (not shown) cuts the large-diameter wafer W1 along the path indicated by the dashed line in Fig. 6, thereby slicing the small-diameter wafer W2 having a diameter φD2 from the large-diameter wafer W1 while leaving the marks M formed on the large-diameter wafer W1 intact. The large diameter wafer W1 is supported by the ring frame F via tape T attached to its back surface and the underside of the ring frame F, and the large diameter wafer W1 and the ring frame F are integrated by the tape T to form a work set WS. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-040056 [Patent Document 2] Japanese Patent Application Publication No. 2023-183692 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the slicing method proposed in Patent Document 2, it is necessary to hold the large-diameter wafer W1 on the chuck table in a state where it is offset by ε as shown in Fig. 6 so that the center O2 of the small-diameter wafer W2 to be slicing coincides with the rotation center of the chuck table, and therefore it is necessary to hold the large-diameter wafer W1 in the work set WS in a state where it is offset by ε with respect to the ring frame F. This requires high precision in transporting the large-diameter wafer W1 to the slicing device, which poses a problem of making the device expensive.

[0008] Depending on the size of the large-diameter wafer W1 held in the work set WS while being offset radially by ε from the center of the ring frame F, the large-diameter wafer W1 may protrude from the opening of the ring frame F, causing a problem that the large-diameter wafer W1 cannot be supported. Alternatively, it is necessary to use a ring frame F with an opening that does not allow the large-diameter wafer W1 to protrude.

[0009] Furthermore, once the large diameter wafer W1 has been transferred to the chuck table, it is not easy to confirm that the center O2 of the small diameter wafer W2 cut out from the large diameter wafer W1 coincides with the center of rotation of the chuck table. If the center O2 of the small diameter wafer W2 is misaligned with the center of rotation of the chuck table, the large diameter wafer W1 (work set WS) must be repositioned on the chuck table, which results in the problem of time and effort being required to cut out the small diameter wafer W2.

[0010] The present invention has been made in view of the above problems, and an object of the present invention is to provide a method and apparatus for slicing small diameter wafers, which can efficiently slice small diameter wafers in a short time without requiring much time and effort. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a method for cutting out small-diameter wafers, which is a method for cutting out small-diameter wafers having a smaller diameter than a wafer having a mark indicating a crystal orientation formed on part of the outer periphery thereof while leaving the mark, and is characterized by carrying out the following steps: a tape application step of applying tape to one side of the wafer; a wafer holding step of holding the wafer on a chuck table via the tape; a mark detection step of detecting the mark on the wafer with a mark detection unit; and a cutting out step of moving one or both of the chuck table and the cutting out means in a horizontal plane while rotating the chuck table so that the processing point of a cutting means for the wafer passes through the mark and describes a circle within the wafer surface.

[0012] Furthermore, the present invention provides an apparatus for dicing small diameter wafers, which comprises: a chuck table that holds, by a holding surface, a work set configured by supporting a wafer, the work set having a mark formed on part of the outer periphery thereof indicating a crystal orientation, on a ring frame via tape affixed to one surface of the wafer and to the ring frame; a chuck table rotation mechanism that rotates the chuck table about its center; dicing means that dices small diameter wafers from the wafer held on the chuck table; and a horizontal movement mechanism that moves the dicing means and the chuck table relatively in a non-horizontal direction, and which dices small diameter wafers from the wafer while leaving the mark; and a control unit that controls the chuck table rotation mechanism and the horizontal movement mechanism so that the processing point of the dicing means for the wafer passes through the mark and describes a circle within the wafer surface. [Effects of the Invention]

[0013] According to the present invention, the work set can be transported to the chuck table in the usual manner with the center of the wafer and the center of the ring frame of the work set aligned, eliminating the need for expensive equipment and allowing the use of conventional equipment. The control unit controls the chuck table rotation mechanism and horizontal movement mechanism, and the processing point of the cutting means for the wafer held on the chuck table moves in a circular motion within the wafer plane, passing through the mark on the wafer, to cut the wafer along a circle (a circle eccentric with respect to the wafer). In other words, by simply controlling the movement of the processing point, small-diameter wafers can be efficiently cut out from the wafer in a short time while leaving the marks formed on the wafer intact. This eliminates the need to newly form marks on the outer periphery of the cut small-diameter wafers, thereby saving the time and effort required for mark formation.

[0014] Furthermore, since the wafer is held in the work set with its center aligned with the center of the ring frame, small-diameter wafers cut from the wafer can be easily handled and transported, and problems such as the wafer protruding from the ring frame and not being securely held by the ring frame can be prevented. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of a small-diameter wafer cutting device according to the present invention; [Figure 2] FIG. [Figure 3] FIG. 2 is a plan view of a large-diameter wafer and a small-diameter wafer. [Figure 4] 1(a) to 1(f) are plan views showing the process of cutting out small diameter wafers in the order of steps. [Figure 5] FIG. 2 is a plan view showing the movement trajectory of the processing point of the cutting blade. [Figure 6] FIG. 1 is a plan view of a work set illustrating a conventional method for cutting small diameter wafers. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0017] [Configuration of the cutting device] First, the configuration of the cut-out device 1 according to the present invention will be described below with reference to Fig. 1. In the following description, as shown by the arrows in Fig. 1, the "front-rear" direction is the X-axis direction, the "left-right" direction is the Y-axis direction, and the "up-down" direction is the Z-axis direction.

[0018] FIG. 1 is a perspective view of the cutting device 1. The illustrated cutting device 1 has a base 2 that supports each component, and a gate-type column 3 is installed vertically at the rear end (-X axis direction end) of this base 2.

[0019] The cutting device 1 has as its main components a chuck table 10 that holds and rotates the large-diameter wafer W1 together with the ring frame F, a chuck table rotation mechanism 12 that rotates the chuck table 10 around its central axis, an X-axis movement mechanism 20 that moves the chuck table 10 back and forth along the X-axis direction together with the large-diameter wafer W1, a cutting unit 30 that is a cutting means for cutting out the large-diameter wafer W1 held on the holding surface of the chuck table 10, a Z-axis movement mechanism 40 that raises and lowers the cutting unit 30 along the Z-axis direction (cutting feed direction), a Y-axis movement mechanism 50 that moves the cutting unit 30 back and forth along the Y-axis direction, and a control unit 60 that controls the X-axis movement mechanism 20, the Z-axis movement mechanism 40, and the Y-axis movement mechanism 50. The configurations of the main components of the cutting device 1, namely, the chuck table 10, the table rotation mechanism 12, the X-axis movement mechanism 20, the cutting unit 30, the Z-axis movement mechanism 40, the Y-axis movement mechanism 50, and the control unit 60, will be described below.

[0020] (Chuck table) The chuck table 10 is a disk-shaped member rotatably disposed in the approximate center of the base 2, and its upper surface constitutes a holding surface that holds the large-diameter wafer W1 together with the ring frame F. Four clamps 11 for fixing the ring frame F from all four sides are arranged around the periphery of the chuck table 10 at equal angular intervals (90° intervals) in the circumferential direction.

[0021] Here, the large-diameter wafer W1 is, for example, a thin, disk-shaped member made of single-crystal silicon (Si), and has a V-notch formed on part of its periphery as a mark M indicating the crystal orientation, as shown in Fig. 2. As the mark M indicating the crystal orientation of the large-diameter wafer W1, an orientation flat formed by linearly cutting part of the periphery of the large-diameter wafer W1 is known.

[0022] The large-diameter wafer W1 is supported by the ring frame F via tape T attached to its back surface (the bottom surface in FIG. 2) and the bottom surface of the ring frame F, and the large-diameter wafer W1 and the ring frame F are integrated by the tape T to form a work set WS. Note that the large-diameter wafer W1 may be made of silicon (Si), silicon carbide (SiC), glass, ceramics, sapphire, or the like.

[0023] (Chuck table rotation mechanism) The chuck table rotating mechanism 12 is a mechanism that rotates the chuck table 10 about a vertical axis, and is disposed below the chuck table 10. Here, the chuck table 10 is rotatably supported on a slider 22 (described later) of the X-axis moving mechanism 20 via the chuck table rotating mechanism 12, and as described above, can rotate about the vertical axis by the chuck table rotating mechanism 12, and can also move back and forth along the X-axis direction by the X-axis moving mechanism 20 disposed below it.

[0024] (X-axis movement mechanism) The X-axis movement mechanism 20 is a mechanism for reciprocating the chuck table 10 together with the large-diameter wafer W1 along the X-axis, and is configured to include a pair of left and right X-axis guide rails 21 arranged in the center of the base 2, a rectangular plate-shaped slider 22 slidably installed in the X-axis direction along these X-axis guide rails 21, a reversible X-axis ball screw 23 arranged along the X-axis between the pair of left and right X-axis guide rails 21, and an X-axis servo motor 24 serving as a rotational drive source for reversing the X-axis ball screw 23. The chuck table 10 is rotatably supported on the slider 22 via the chuck table rotation mechanism 12 about a vertical central axis. Although not shown, a nut member protrudes downward from the center of the underside of the slider 22 in the width direction, and the X-axis ball screw 23 is threadedly inserted into the nut member.

[0025] The X-axis servo motor 24 is provided with an encoder 25 that detects the rotation direction and number of rotations of the X-axis servo motor 24, and the encoder 25 and the X-axis servo motor 24 are electrically connected to the control unit 60. A detection signal from the encoder 25 is sent to the control unit 60, and the operation of the X-axis servo motor 24 is controlled by the control unit 60 based on this detection signal.

[0026] In the X-axis movement mechanism 20, when the X-axis servo motor 24 is started to rotate the X-axis ball screw 23 forward or backward, the slider 22, which has a protruding nut member (not shown) that screws onto the X-axis ball screw 23, slides in the X-axis direction along the pair of left and right X-axis guide rails 21, and the chuck table 10 moves back and forth along the X-axis direction together with the slider 22 and the chuck table rotation mechanism 12.

[0027] (Cutting unit) The cutting unit 30 includes a spindle unit 31 attached to the lower part of a lifting plate 42 (described later) of the Z-axis moving mechanism 40, and an imaging unit 32. The imaging unit 32 captures an image of the large diameter wafer W1 held on the holding surface of the chuck table 10, and detects the position of a mark M formed on a part of the outer periphery of the large diameter wafer W1. The detection signal is sent to the control unit 60.

[0028] The spindle unit 31 also has a rectangular box-shaped spindle housing 33 arranged along the Y-axis direction, and this spindle housing 33 contains a spindle motor (neither of which is shown) that rotates and drives the spindle arranged along the Y-axis direction, and a circular cutting blade 34, which is a processing tool, is attached to the tip of the spindle that protrudes from the spindle housing 33.

[0029] (Z-axis movement mechanism) The Z-axis movement mechanism 40 is a mechanism for raising and lowering the cutting-out unit 30 along the Z-axis direction, and is configured to include a pair of Z-axis guide rails 41 arranged parallel to each other and vertically on the left and right of a rectangular plate-shaped slider 51, a lifting plate 42 that can move up and down along these Z-axis guide rails 41, a rotatable Z-axis ball screw 43 that is arranged vertically between the pair of Z-axis guide rails 41, and a Z-axis servo motor 44 that can rotate forward and backward and drives the Z-axis ball screw 43. The cutting-out unit 30 is attached to the lower part of the lifting plate 42. A nut member (not shown) protrudes from the back surface of the lifting plate 42, and the Z-axis ball screw 43 is threadedly inserted into the nut member.

[0030] In the Z-axis movement mechanism 40 configured as described above, when the Z-axis servo motor 44 is activated and the Z-axis ball screw 43 rotates forward or backward, the lifting plate 42, from which a nut member (not shown) that threads onto the Z-axis ball screw 43 protrudes, moves up and down along the pair of Z-axis guide rails 41, causing the cutting unit 30 attached to the lifting plate 42 to move up and down along the Z-axis direction. The Z-axis servo motor 44 is provided with an encoder 45 that detects the direction and number of rotations of the Z-axis servo motor 44, and the encoder 45 and the Z-axis servo motor 44 are electrically connected to the control unit 60. A detection signal from the encoder 45 is transmitted to the control unit 60, which controls the operation of the Z-axis servo motor 44 based on the detection signal.

[0031] (Y-axis movement mechanism) The Y-axis movement mechanism 50 is a mechanism for reciprocating the cutting unit 30 along the Y-axis direction, and includes a slider 51. The slider 51 is movable along the Y-axis direction along a pair of upper and lower Y-axis guide rails 52 that are arranged parallel to each other along the Y-axis direction in front of the gate-type column 3 that is erected vertically on the base 2.

[0032] The Y-axis movement mechanism 50 is provided with a Y-axis ball screw 53 that can rotate forward and backward and is arranged along the Y-axis between a pair of upper and lower Y-axis guide rails 52, and a nut member (not shown) that protrudes from the back surface of the slider 51 is threadedly engaged with the Y-axis ball screw 53. One axial end of the Y-axis ball screw 53 is connected to a Y-axis servo motor 54 that serves as a rotational drive source.

[0033] Therefore, in the Y-axis movement mechanism 50, when the Y-axis servo motor 54 is activated to rotate the Y-axis ball screw 53 forward or backward, the slider 51, which has a protruding nut member (not shown) that screws onto the Y-axis ball screw 53, can move in the Y-axis direction along the Y-axis guide rail 52 together with the lifting plate 42. This allows the cutting unit 30 attached to the lifting plate 42 to move in the Y-axis direction along the Y-axis guide rail 52. The Y-axis servo motor 54 is provided with an encoder 55 that detects the rotation direction and rotation speed of the Y-axis servo motor 54, and the encoder 55 and the Y-axis servo motor 54 are electrically connected to a control unit 60. A detection signal from the encoder 55 is sent to the control unit 60, and the control unit 60 controls the operation of the Y-axis servo motor 54 based on the detection signal sent from the encoder 55.

[0034] In conclusion, in the cutting device 1 shown in FIG. 1, the chuck table 10 and the large diameter wafer W1 (work set WS) held thereon are movable along the X-axis direction, and the cutting unit 30 is movable along the Y-axis direction and the Z-axis direction.

[0035] (Control unit) The control unit 60 includes a CPU (Central Processing Unit) that performs arithmetic processing according to a control program, and storage units such as a ROM (Read Only Memory) and a RAM (Random Access Memory). In particular, in this embodiment, the control unit 60 functions to control the chuck table rotation mechanism 12, the X-axis movement mechanism 20, and the Y-axis movement mechanism 50 so that the processing point P (see FIG. 4) of the cutting blade 34 of the cutting unit 30 on the large diameter wafer W1 passes through the mark M on the large diameter wafer W1 and draws a circle within the plane of the large diameter wafer W1, which will be described in detail later.

[0036] [Method of cutting small diameter wafers] Next, a method for slicing the large diameter wafer W1 into small diameter wafers W2 (see FIG. 3) using the slicing apparatus 1 configured as above will be described below with reference to FIGS.

[0037] The method for slicing small diameter wafers W2 according to the present invention includes the steps of: 1) Tape application process: 2) Wafer holding process: 3) Mark detection process: 4) Cutting process: The above steps are carried out in order to slice the small diameter wafer W2 from the large diameter wafer W1 shown in FIG. 3. Each step will be described below.

[0038] 1) Tape application process: The tape adhering step is a step of adhering tape T to the back surface (the lower surface in FIG. 2) of the large diameter wafer W1 and the lower surface of the ring frame F, and in this adhering step, the large diameter wafer W1 is supported on the ring frame F via the tape T adhered to the large diameter wafer W1 and the ring frame F. As a result, the large diameter wafer W1 and the ring frame F are integrated by the tape T to form the work set WS shown in FIG.

[0039] In this embodiment, in the work set WS configured as described above, the large-diameter wafer W1 is placed in the center of the ring frame F so that its center O1 coincides with the center of the ring frame F, as shown in Fig. 2, and is supported by the ring frame F via the tape T. In this way, the large-diameter wafer W1 is supported concentrically by the ring frame F, so that when the large-diameter wafer W1 is large, problems such as the large-diameter wafer W1 protruding from the ring frame F do not occur.

[0040] 2) Wafer holding process: The wafer holding process is a process in which the large diameter wafer W1 is held together with the work set WS on the holding surface of the chuck table 10 shown in FIG. 1. When the large diameter wafer W1 is placed on the holding surface of the chuck table 10 together with the ring frame F that holds it, with the tape T facing downward, the ring frame F is fixed together with the large diameter wafer W1 on the holding surface of the chuck table 10 via the tape T by four clamps 11.

[0041] As described above, the center O1 of the large-diameter wafer W1 and the center of the ring frame F coincide with each other and are concentric, so the center O1 of the large-diameter wafer W1 held on the holding surface of the chuck table 10 coincides with the center of the chuck table 10. Therefore, unlike the conventional example shown in Fig. 6, it is not necessary to confirm that the center O2 of the small-diameter wafer W2 cut out from the large-diameter wafer W1 coincides with the center of the chuck table 10 while the work set WS (ring frame F) is held on the chuck table 10. In this embodiment, when the work set WS (large-diameter wafer W1) is held on the holding surface of the chuck table 10, the center of the large-diameter wafer W1 coincides with the center of the chuck table 10.

[0042] 3) Mark detection process: The mark detection process is a process of optically detecting the position (angular position) of a mark (in this embodiment, a V-notch) M formed on a part of the outer periphery of the large diameter wafer W1 by imaging the large diameter wafer W1 using the imaging unit 32 shown in Figure 1, and the detection signal output from the imaging unit 32 is sent to the control unit 60.

[0043] 4) Cutting process: 3, the cutting process is a process of cutting out small-diameter wafers W2 having a diameter φD2 (<φD1) smaller than the diameter φD1 from a large-diameter wafer W1 having a diameter φD1, and in this embodiment, the small-diameter wafers W2 are cut out from the large-diameter wafer W1 while leaving the marks M formed on the large-diameter wafer W1 as they are. That is, the control unit 60 controls the chuck table rotation mechanism 12, the X-axis movement mechanism 20, and the Y-axis movement mechanism 50 so that the processing point P for the large-diameter wafer W1 of the cutting unit 30 passes through the marks M on the large-diameter wafer W1 and draws a circle of diameter φD2 (a circle eccentric with respect to the large-diameter wafer W1) shown by the dashed line in FIG. 3 within the plane of the large-diameter wafer W1.

[0044] Specifically, the large diameter wafer W1 (work set WS) rotates once around the center of the chuck table 10 (work set WS) at a constant speed by the chuck table rotation mechanism 12, and the chuck table 10 and the large diameter wafer W1 held thereon are moved a predetermined distance in the X-axis direction by the X-axis movement mechanism 20, and at the same time, the chuck table 10 and the large diameter wafer W1 held thereon are moved a predetermined distance in the Y-axis direction by the Y-axis movement mechanism 50. Here, the memory of the control unit 60 stores the rotation angle θ of the chuck table 10 for the diameter φD2 of the small diameter wafer W2 to be cut out. i The movement amount x of the cutting blade 34 in the X-axis direction of the processing point P with respect to the large diameter wafer W1 i and the amount of movement in the Y-axis direction, y i (i=1, 2, 3, . . . , N natural numbers) are stored as data. Therefore, the control unit 60 reads out the data stored in the storage unit and converts the data (θ i ,x i ,y i ) to control the chuck table rotating mechanism 12, the X-axis moving mechanism 20, and the Y-axis moving mechanism 50. Details of this control will be explained below with reference to FIG.

[0045] 1, when the work set WS is held by the four clamps 11 on the holding surface of the chuck table 10, the mark M formed on the outer periphery of the large-diameter wafer W1 faces the +X-axis direction, so the chuck table rotation mechanism 12 rotates the chuck table 10 and the work set WS (large-diameter wafer W1) held thereon by an angle of 90°, and as shown in FIG. 4(a), the mark M is aligned with the position of the cutting blade 34 of the cutting unit 30. In this state, the rotation angle θ of the chuck table 10 (large-diameter wafer W1) is set to 0 (θ=0), and the movement amount x0 in the X-axis direction and the movement amount y0 in the Y-axis direction of the cutting blade 34 of the cutting unit 30 are both set to 0 (x0=0, y0=0).

[0046] 4(a), from a state in which the cutting blade 34 of the cutting unit 30 shown in FIG. 1 is positioned at the position where the mark M1 of the large diameter wafer W1 is formed, a spindle motor (not shown) is started to rotate the cutting blade 34 at a predetermined speed (for example, 20,000 min -1 ), the cutting blade 34 is lowered by a predetermined distance (the height at which the tip of the cutting blade 34 cuts into a tape (not shown) attached to the underside of the large diameter wafer W1) at a predetermined speed (10 μm / sec) by the Z-axis movement mechanism 40 shown in FIG. 1, causing the cutting blade 34 to cut into the large diameter wafer W1. The cutting blade 34 cuts into the large diameter wafer W1 while passing over (avoiding) the mark M on the large diameter wafer W1.

[0047] 4(b), when the chuck table 10 is rotated (1 / 8 rotation) by an angle θ=45° in the direction of the arrow (counterclockwise) by the chuck table rotation mechanism 12 together with the large-diameter wafer W1, the Y-axis movement mechanism 50 moves the processing point P of the cutting blade 34 by y1 in the -Y-axis direction, and the X-axis movement mechanism 20 moves the chuck table 10 (large-diameter wafer W1) by x1 in the +X-axis direction. Note that in FIG. 4, the chuck table 10 (large-diameter wafer W1) is fixed and the cutting blade 34 is shown moving in the X-axis direction relative to the chuck table 10 (large-diameter wafer W1), but in reality, the cutting blade 34 does not move in the X-axis direction, and the chuck table 10 (large-diameter wafer W1) is moved in the X-axis direction relative to the cutting blade 34 by the X-axis movement mechanism 20. In this manner, when the chuck table 10 rotates together with the large diameter wafer W1 in the direction of the arrow (counterclockwise) by an angle θ=45°, the arc-shaped portion of the small diameter wafer W2 shown by the solid line is cut by the cutting blade 34.

[0048] 4(c), when the chuck table 10 is rotated (a quarter rotation) by an angle θ=90° in the direction of the arrow (counterclockwise) by the chuck table rotation mechanism 12 together with the large diameter wafer W1, the processing point P of the cutting blade 34 is moved by y2 in the -Y axis direction by the Y axis movement mechanism 50, and the chuck table 10 (large diameter wafer W1) is moved by x2 in the +X axis direction by the X axis movement mechanism 20. In this way, when the chuck table 10 is rotated by an angle θ=90° in the direction of the arrow (counterclockwise) together with the large diameter wafer W1, the cutting blade 34 cuts into the arc-shaped portion of the small diameter wafer W2 indicated by the solid line.

[0049] 4(d), when the chuck table 10 is rotated (half-rotated) by an angle θ=180° in the direction of the arrow (counterclockwise) by the chuck table rotation mechanism 12 together with the large-diameter wafer W1, the Y-axis movement mechanism 50 moves the processing point P of the cutting blade 34 by y3 in the -Y-axis direction, and the X-axis movement mechanism moves the chuck table (large-diameter wafer) by x2 in the -X-axis direction, returning to the initial position shown in FIG. 4(a). In this way, when the chuck table 10 is rotated (half-rotated) by an angle θ=180° in the direction of the arrow (counterclockwise) together with the large-diameter wafer W1, the cutting blade 34 cuts into the semicircular portion of the small-diameter wafer W2 indicated by the solid line.

[0050] 4(e), when the chuck table 10 is rotated (3 / 4 rotation) by an angle θ=270° in the direction of the arrow (counterclockwise) by the chuck table rotation mechanism 12 together with the large diameter wafer W1, the processing point P of the cutting blade 34 is moved by y4 in the +Y axis direction by the Y-axis movement mechanism 50, and the chuck table 10 (large diameter wafer W1) is moved by x4 in the -X axis direction by the X-axis movement mechanism 20. In this way, when the chuck table 10 is rotated (3 / 4 rotation) by an angle θ=270° in the direction of the arrow (counterclockwise) together with the large diameter wafer W1, the cutting blade 34 cuts into the arc-shaped portion of the small diameter wafer W2 indicated by the solid line.

[0051] Then, as shown in FIG. 4(f), when the chuck table rotation mechanism 12 rotates the chuck table 10 together with the large-diameter wafer W1 by an angle θ=360° (one rotation) in the direction of the arrow (counterclockwise), the Y-axis movement mechanism 50 moves the processing point P of the cutting blade 34 by y4 in the +Y-axis direction and returns to the initial position shown in FIG. 4(a), and the X-axis movement mechanism 20 moves the chuck table 10 (large-diameter wafer W1) by x4 in the −X-axis direction and returns to the initial position shown in FIG. 4(a). In this manner, when the chuck table 10 together with the large-diameter wafer W1 rotates by an angle θ=360° (one rotation) in the direction of the arrow (counterclockwise), the cutting blade 34 cuts into the circular portion of the small-diameter wafer W2 indicated by the solid line. As a result, a small-diameter wafer W2 having a diameter φD2 (<φD1) is cut out from the large-diameter wafer W1 having a diameter φD1, leaving the mark M formed on the outer periphery of the large-diameter wafer W1 intact.

[0052] As described above, the control unit 60 controls the chuck table rotation mechanism 12, the X-axis movement mechanism 20, and the Y-axis movement mechanism 50, and rotates the chuck table 10 once together with the work set WS (large diameter wafer W1). The movement amount x of the cutting blade 34 in the X-axis direction relative to the large diameter wafer W1 for each rotation angle θ of the chuck table 10 is calculated. i and the amount of movement in the Y-axis direction, y i By changing the diameter of the cutting blade 34, a small diameter wafer W2 having a diameter of φD2 (<φD1) can be cut out from the large diameter wafer W1 having a diameter of φD1, while leaving a mark M formed on the outer periphery of the large diameter wafer W1. In this case, the locus of the processing point P of the cutting blade 34 relative to the large diameter wafer W1 is a circle having a diameter of φy3, as shown by the dashed line C in FIG.

[0053] As described above, according to this embodiment, the work set WS can be transferred to the chuck table 10 in the usual manner with the center O1 of the large-diameter wafer W1 and the center of the ring frame F of the work set WS aligned. This eliminates the need for expensive equipment and allows the use of conventional equipment. The control unit 60 controls the chuck table rotation mechanism 12 and the horizontal movement mechanisms, the X-axis movement mechanism 20 and the Y-axis movement mechanism 50, to move the processing point P of the cutting blade 34 for the large-diameter wafer W1 held on the chuck table 10 so as to pass through the mark M on the large-diameter wafer W1 and draw a circle within the plane of the large-diameter wafer W1, thereby cutting the large-diameter wafer W1 along a circle (a circle eccentric with respect to the large-diameter wafer W1). In other words, by simply controlling the movement of the processing point P, small-diameter wafers W2 can be efficiently cut out from the large-diameter wafer W1 in a short time while leaving the mark M formed on the large-diameter wafer W1 intact. This eliminates the need to newly form a mark M on the outer periphery of the cut small-diameter wafer W2, thereby saving the time and effort required for forming the mark M.

[0054] Furthermore, since the large-diameter wafer W1 is held in the work set WS with its center O1 aligned with the center of the ring frame F, the small-diameter wafers W2 cut out from the large-diameter wafer W1 can be easily handled and transported, and problems such as the large-diameter wafer W1 protruding from the ring frame F and not being securely held by the ring frame F can be prevented.

[0055] In the above embodiment, the center of the ring frame F of the work set WS coincides with the center of the large-diameter wafer W1, but they do not have to coincide. That is, after the work set WS is held on the chuck table 10, the center of the large-diameter wafer W1 is detected, and the amount of deviation between the center of rotation of the chuck table 10 and the center of the large-diameter wafer W1 and the direction of the deviation based on the mark M are recognized. When cutting out the small-diameter wafer W2, the chuck table 10 and the cutting blade 34 may be moved in the X-axis and Y-axis directions while correcting the amount and direction of the deviation.

[0056] In the above embodiment, the chuck table rotation mechanism 12 rotates the chuck table 10 together with the concentric large-diameter wafer W1 (workpiece set WS) once, while the X-axis movement mechanism 20 moves the chuck table 10 (large-diameter wafer W1) in the X-axis direction and the Y-axis movement mechanism 50 moves the cutting blade 34 in the Y-axis direction. However, a configuration in which the cutting blade 34 moves simultaneously in the X-axis and Y-axis directions may also be used. In this case, movement of the chuck table 10 in the X-axis direction is not necessary. Alternatively, a configuration in which the chuck table 10 moves simultaneously in the X-axis and Y-axis directions may also be used, in which case movement of the cutting blade 34 in the Y-axis direction is not necessary.

[0057] Furthermore, the present invention is not limited to the application of the above-described embodiments, and it goes without saying that various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0058] 1: Cutting device, 2: Base, 3: Gate column, 10: Chuck table, 11: Clamp, 12: Chuck table rotation mechanism, 20: X-axis movement mechanism (horizontal movement mechanism), 21: X-axis guide rail, 22: slider, 23: X-axis ball screw, 24: X-axis servo motor, 25: encoder, 30: cutting unit (cutting means), 31: spindle unit, 32: imaging unit (mark detection unit), 33: Spindle housing, 34: Cutting blade, 40: Z-axis movement mechanism, 41: Z-axis guide rail, 42: lifting plate, 43: Z-axis ball screw, 44: Z-axis servo motor, 45: Encoder, 50: Y-axis movement mechanism (horizontal movement mechanism), 51: Slider, 52: Y-axis guide rail, 53: Y-axis ball screw, 54: Y-axis servo motor, 55: encoder, 60: control unit, C: trajectory of the cutting blade processing point, φD1: diameter of the large diameter wafer, D2: diameter of small diameter wafer, F: frame, M: mark, O1: center of large diameter wafer, O2: Center of small diameter wafer, P: Processing point of cutting blade, T: Tape, W1: Large diameter wafer (wafer) A, W2: Small diameter wafer, WS: Work set

Claims

1. A method for slicing small diameter wafers, comprising the steps of: slicing a wafer having a mark indicating a crystal orientation formed on a part of its outer periphery into small diameter wafers having a smaller diameter than the wafer while leaving the mark; a tape adhering step of adhering a tape to one surface of the wafer; a wafer holding step of holding the wafer on a chuck table via the tape; a mark detection step of detecting the mark on the wafer by a mark detection unit; a cutting step of moving one or both of the chuck table and the cutting means in a horizontal plane while rotating the chuck table so that a processing point of the cutting means for the wafer passes through the mark and describes a circle within the wafer surface; The method for cutting out small diameter wafers is as follows.

2. a chuck table that holds, by a holding surface, a work set configured by supporting a wafer, which has a mark indicating a crystal orientation formed on a part of its outer periphery, on a ring frame via tape affixed to one surface of the wafer and the ring frame; a chuck table rotation mechanism that rotates the chuck table about its center as an axis; a cutting means for cutting out a small diameter wafer from the wafer held on the chuck table; a horizontal movement mechanism that moves the cutting means and the chuck table relatively in a horizontal direction; a small diameter wafer cutting device for cutting small diameter wafers from the wafer while leaving the mark, a control unit that controls the chuck table rotation mechanism and the horizontal movement mechanism so that the processing point of the cutting means for the wafer passes through the mark and draws a circle within the wafer surface.

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