Wafter dividing method and dividing device

Abstract

To divide a wafer efficiently in a short time without breaking chips.SOLUTION: Provided is a method for dividing a wafer W where lattice-like streets L1, L2 are formed on the surface by taking a dividing origin g formed along the streets L1, L2 as the starting point. The method includes: a holding step for holing a ring frame F that holds the wafer W via a sheet T pasted to the ring frame F and the reverse side of the wafer W by a holding table 10; a sandwiching step for sandwiching the wafer W between a lower bar 31 linearly coming into contact with the lower side of the sheet along the streets L1, L2 and an upper bar 63 coming into contact with the top face of the wafer W along the streets L1, L2; and a dividing step for, while ultrasonically vibrating a press bar 62 extending in parallel to the upper bar 63 between the streets L1, L2, pressing the press bar 62 against the top face of the wafer W so as to cut and divide the wafer W starting from a dividing origin g.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a wafer dividing method and apparatus for dividing a wafer along lattice-shaped streets. [Background technology]

[0002] For example, in the manufacturing process of semiconductor devices, the surface of a disk-shaped semiconductor wafer (hereinafter simply referred to as a "wafer") is divided into a number of device regions by streets (planned division lines) formed in a grid pattern, and devices such as ICs and LSIs are formed in each device region. Then, the wafer on which a large number of devices are thus formed is divided along the streets to obtain a number of chips.

[0003] As a method for dividing a wafer along the streets, Patent Document 1 proposes a method in which a tape attached to a wafer having a modified layer formed therein by irradiation with a laser beam is expanded, thereby dividing the wafer starting from the modified layer.

[0004] However, even with the above method, it is difficult to divide the wafer by expanding the tape when the wafer is made of a hard material such as silicon carbide (SiC) or sapphire. For this reason, Patent Documents 2 to 4 propose a method of pressing a breaking blade of a breaking device against the wafer to break the wafer along the streets. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-140266 A [Patent Document 2] JP 2023-100580 A [Patent Document 3] JP 2013-058671 A [Patent Document 4] JP 2016-207921 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, wafers with a metal film such as titanium, gold, or copper formed on the back surface are sometimes broken, and even if a wafer with such a metal film is broken using a breaking device, the metal film may bend and the wafer cannot be broken. For this reason, a breaking blade is pressed with a large force to break the wafer with such a metal film, and when such a large force is applied to the wafer to break it, the chips come into contact with each other and chips are chipped. In addition, when a thick wafer is broken, it is necessary to apply a large force to the wafer to break it, so there is a problem that the wafer cannot be broken or it takes a long time to break it.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a wafer dividing method and dividing apparatus capable of dividing a wafer efficiently in a short time without damaging the chips. [Means for solving the problem]

[0008] A wafer dividing method according to a first invention is a method for dividing a wafer having grid-like streets formed on a surface thereof, starting from division starting points formed along the streets, and is characterized by including: a holding step of holding, on a ring-shaped holding table, a ring frame that supports the wafer via a sheet attached to the ring frame and the back surface of the wafer; a clamping step of clamping the wafer between a lower bar that contacts the lower surface of the sheet in a linear manner along the streets and an upper bar that contacts the upper surface of the wafer along the streets; and a dividing step of cutting the wafer starting from the division starting points by ultrasonically vibrating a pressing bar extending parallel to the upper bar and pressing the pressing bar against the upper surface of the wafer across the streets.

[0009] The wafer dividing method according to the second invention is a wafer dividing method for dividing a wafer having grid-like streets formed on a surface thereof, starting from division starting points formed along the streets, and is characterized by including a holding step of holding, with a ring-shaped holding table, a ring frame that supports the wafer via a sheet attached to the ring frame and the back surface of the wafer, and a dividing step of, with the underside of the sheet supported by a support part, ultrasonically vibrating a pressing bar extending from above the streets of the wafer, while pressing the pressing bar against the upper surface of the wafer away from the upper bar, thereby fracturing the wafer starting from the division starting points.

[0010] The wafer dividing apparatus of the first invention is an apparatus for carrying out the wafer dividing method of the first invention, and is characterized in that it comprises a ring-shaped holding table that holds the ring frame of a work set configured by supporting the wafer on the ring frame via a sheet attached to the ring frame and a wafer, a lower bar that is arranged inside the holding table and abuts against the sheet of the work set held on the holding table, a lower bar lifting mechanism that raises and lowers the lower bar, an upper bar that is arranged opposite the lower bar and abuts against an upper surface of the wafer of the work set held on the holding table, an upper bar lifting mechanism that raises and lowers the upper bar, a pressing bar that is arranged parallel to the upper bar and presses the wafer, and an ultrasonic vibrator that is arranged on the pressing bar and ultrasonically vibrates the pressing bar.

[0011] The wafer dividing device of the second invention is an apparatus for carrying out the wafer dividing method of the second invention, and is characterized in that it comprises: a ring-shaped holding table that holds a ring frame of a work set configured by supporting the wafer on the ring frame via a sheet attached to a ring frame and a wafer, a support portion that is arranged inside the holding table and supports the underside of the sheet of the work set held on the holding table, a pressing bar that extends along the streets of the wafer and presses the streets from above, and an ultrasonic vibrator that is arranged on the pressing bar and ultrasonically vibrates the pressing bar. Effect of the Invention

[0012] According to the wafer dividing method of the first invention implemented by the dividing device of the first invention, the wafer is clamped along the street between the lower bar and the upper bar, and the pressing bar is ultrasonically vibrated while being pressed against the upper surface of the wafer away from the upper bar, so that the wafer is reliably cleaved from the dividing origin by brittle fracture (fatigue fracture due to repeated stress) caused by vibration energy transmitted from the pressing bar. Therefore, even if the wafer has a metal film formed on its back surface or is a thick wafer, the wafer can be reliably divided from the dividing origin in a short time without applying a large force, and the chips obtained by division are not damaged.

[0013] According to the wafer dividing method of the second invention implemented by the dividing device of the second invention, the underside of the wafer is supported by a support part via a sheet, and a pressure bar is ultrasonically vibrated and pressed against the street from above the street of the wafer, so that the wafer is reliably cleaved from the division origin by brittle fracture (fatigue fracture due to repeated stress) caused by vibration energy transmitted from the pressure bar. Therefore, even if the wafer has a metal film formed on its back side or is thick, the wafer can be reliably divided from the division origin in a short time without applying a large force, and the chips obtained by division are not damaged. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view of a wafer dividing device according to a first aspect of the present invention. [Diagram 2] FIG. [Diagram 3] 1 is a perspective view of a lower bar mechanism of a wafer dividing device according to a first aspect of the present invention. FIG. [Figure 4] 3 is a partial cross-sectional side view showing a holding step in the wafer dividing method according to the first embodiment of the first invention. FIG. [Diagram 5] 3 is a partial cross-sectional side view showing a clamping step in the wafer dividing method according to the first embodiment of the first invention. FIG. [Figure 6] 1 is a partial cross-sectional side view showing a dividing step in a wafer dividing method according to a first embodiment of the first invention. [Figure 7] 5 is a partial cross-sectional side view showing a holding step in a wafer dividing method according to a second embodiment of the first invention. FIG. [Figure 8] 5 is a partial cross-sectional side view showing a clamping step in a wafer dividing method according to a second embodiment of the first invention. FIG. [Figure 9] 5 is a partial cross-sectional side view showing a dividing step in a wafer dividing method according to a second embodiment of the first invention. FIG. [Figure 10] FIG. 11 is a perspective view of a wafer dividing device according to a first embodiment of the second invention. [Figure 11] 11 is a partial cross-sectional side view showing a holding step in the wafer dividing method according to the first embodiment of the second invention. FIG. [Figure 12] 11 is a partial cross-sectional side view showing a dividing step in a wafer dividing method according to a first embodiment of the second invention. FIG. [Figure 13] FIG. 11 is a perspective view of a wafer dividing device according to a second embodiment of the second invention. [Figure 14] FIG. 11 is a partial cross-sectional side view showing a holding step in a wafer dividing method according to a second embodiment of the second invention. [Figure 15]11 is a partial cross-sectional side view showing a dividing step in a wafer dividing method according to a second embodiment of the second invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [First invention] An embodiment of the first invention will be described below with reference to the accompanying drawings.

[0016] [Configuration of the splitter] First, the configuration of the wafer dividing apparatus 1 according to the first aspect of the present invention will be described. In the following description, the directions of the arrows shown in Fig. 1 are the X-axis direction (front-back direction), the Y-axis direction (left-right direction), and the Z-axis direction (up-down direction), respectively.

[0017] The dividing apparatus 1 according to the first invention is an apparatus for dividing a wafer W shown in Fig. 2, and the wafer W to be divided is, for example, a thin disk-shaped member made of single crystal silicon (Si), and a metal film S (see Fig. 4) of gold, silver, copper or the like is formed on its back surface (the lower surface in Fig. 2). The front surface (the upper surface in Fig. 2) of the wafer W is partitioned into a plurality of rectangular regions by mutually orthogonal streets (planned dividing lines) L1, L2 arranged in a lattice pattern, and devices D such as ICs and LSIs are formed in each rectangular region.

[0018] The wafer W having a large number of devices D formed on its surface is incorporated into a work set WS shown in Fig. 2, and the dividing method according to the first invention is carried out on the wafer W. Here, the work set WS is configured by bonding the back surface (more precisely, the underside of the metal film S) of the disk-shaped wafer W to a sheet T that is attached to a metal (e.g., SUS) ring frame F by closing its circular opening, thereby supporting the wafer W on the ring frame F via the sheet T, and integrating the wafer W with the ring frame F and the sheet T. Note that, as the material of the wafer W, in addition to silicon (Si), silicon carbide (SiC), which has high hardness, glass, ceramics, sapphire, etc. are used.

[0019] 1 comprises, as main components, a ring-shaped holding table 10 that holds a ring frame F of a work set WS, a lower bar mechanism 30 arranged inside the holding table 10, a pressing bar mechanism 60 provided on a gate-shaped column 110 that is vertically erected on a base 100, and an ultrasonic vibration imparting unit 80. Below, the configurations of the holding table 10, the lower bar mechanism 30, the pressing bar mechanism 60, and the ultrasonic vibration imparting unit 80, which are the main components of the dividing device 1, will be described respectively.

[0020] (holding table) The ring-shaped holding table 10 is rotatably mounted on a slider 21 of a horizontal movement mechanism 20, and two fixed clamps 11 and two movable clamps 12 are arranged on its upper surface at equal angular pitches (90° pitches) in the circumferential direction. Here, each fixed clamp 11 is fixed to the upper surface of the holding table 10, and each movable clamp 12 has a pressing element 12a that is movable along the radial direction of the holding table 10 (the direction of the arrow in the figure).

[0021] Thus, the holding table 10 can be rotated around a vertical central axis by a rotation mechanism (not shown), and can be reciprocated along the Y-axis direction by a horizontal movement mechanism 20. Here, the horizontal movement mechanism 20 includes a pair of guide rails 22 laid parallel to each other along the Y-axis direction on the base 100, a rectangular plate-like slider 21 movable along these guide rails 22, a rotatable ball screw 23 arranged along the Y-axis direction on the side of one (+Y-axis direction) guide rail 22, and a servo motor 24, which is a forward / reverse rotatable rotation drive source connected to one axial end of the ball screw 23. The other axial end of the ball screw 23 is rotatably supported by the base 100 via a bearing (not shown).

[0022] A rectangular block-shaped nut member 25 is attached to one side of the slider 21, and the ball screw 23 is screwed into the nut member 25. Therefore, when the servo motor 24 is started to rotate the ball screw 23 forward and backward, the nut member 25 that screws into the ball screw 23 is attached, and the slider 21 can reciprocate in the Y-axis direction along the pair of guide rails 22. Therefore, the holding table 10 supported by the slider 21 can also reciprocate in the Y-axis direction.

[0023] (Lower bar mechanism) The lower bar mechanism 30, arranged inside the holding table 10, as shown in Figure 3, is equipped with four lower bars 31 of different lengths arranged in a cross shape at equal angular pitch (90° pitch) circumferentially, a lower bar rotation mechanism 40 that intermittently rotates these lower bars 31 by 90°, and a lower bar lifting mechanism 50 that raises and lowers each lower bar 31 in the Z-axis direction.

[0024] Each of the four lower bars 31 is a rectangular plate-like member long in the X-axis direction, and is attached radially to the outer periphery of a rotatable rotating shaft 41 arranged along the X-axis direction, and the tip of each lower bar 31 is stepped. Here, the rotating shaft 41 is rotatably supported by a frame 42, and a driven gear 43 is attached to one axial end (+X-axis end) protruding from the frame 42. An electric motor 44, which is a rotary drive source, is attached in a horizontally placed state to one end (the side where the driven gear 43 is provided) of the frame 42. A drive gear 45 is attached to the end of an output shaft (motor shaft) (not shown) that extends horizontally from the electric motor 44 and penetrates one side of the frame 42, and the drive gear 45 and the driven gear 43 are engaged with each other. In this embodiment, the driven gear 43 and the drive gear 45 have the same diameter.

[0025] Thus, the rotating shaft 41, the electric motor 44, the driven gear 43, the drive gear 45, etc. constitute a lower bar rotation mechanism 40 that rotates the four lower bars 31. Therefore, when the electric motor 44 is started, the rotation of its output shaft (motor shaft) is transmitted to the rotating shaft 41 via the mutually meshing drive gear 45 and driven gear 43, and the rotating shaft 41 and the four lower bars 31 attached thereto rotate intermittently by an angle of 90 degrees around the axis of the rotating shaft 41. The four lower bars 31, which are different in length, are rotated by an angle of 90 degrees by the lower bar rotation mechanism 40, so that the lower bars 31, whose lengths correspond to the lengths of the streets L1 and L2 of the wafer W held on the holding surface of the holding table 10, are positioned vertically below the wafer as shown in FIG. 4, and clamp the lower surface of the wafer W together with the upper bar 63 as described later.

[0026] Further, the lower bar lifting mechanism 50 that lifts and lowers the four lower bars 31 includes a pair of guide rails 52 arranged along the Z-axis direction (up and down direction) on a vertically standing rectangular plate-like base 51, a rotatable ball screw 53 arranged along the Z-axis direction between these guide rails 52, and a servo motor 54 that is a rotation drive source connected to the lower end of the ball screw 53. The upper end of the ball screw 53 is rotatably supported by the base 51 via a bearing 55. Further, a nut member (not shown) is attached to the frame 42, and the ball screw 53 is screwed and inserted into the nut member.

[0027] Therefore, when the servo motor 54 is started to rotate the ball screw 53 forward and backward, the frame 42, to which a nut member (not shown) that screws into the ball screw 53 is attached, rises and falls together with the rotating shaft 41 and the electric motor 44, etc., and the four lower bars 31 attached radially to the rotating shaft 41 also rise and fall along the Z-axis direction.

[0028] (Pressure bar mechanism) 1 and 4, the pressing bar mechanism 60 is provided with a slider 61 bent in a horizontal L-shape, and a pressing bar 62 and an upper bar 63 arranged parallel to each other along the Y-axis direction are vertically supported by the slider 61. The pressing bar 62 is a plate member bent in an inverted L-shape and has a horizontal portion 62A and a vertical portion 62B, and the lower end of the vertical portion 62B forms a sharp knife edge. A distance adjustment mechanism 64 is provided between the horizontal portion 62A of the pressing bar 62 and the slider 61.

[0029] Additionally, the vertical upper bar 63, which is disposed adjacent to the pressing bar 62 and parallel to the X-axis direction (the direction perpendicular to the paper surface of FIG. 4), is a plate member bent into an inverted L shape, and a shaft 65 extending upward from its upper end passes vertically through the slider 61, and a damper 66 is attached to the upper end of the shaft 65 protruding upward from the slider 61. The damper 66 is composed of an air cylinder or a coil spring, and serves to urge the upper bar 63 downward with a constant force.

[0030] 1, the pressure bar lifting mechanism 70 includes a pair of guide rails 72 attached parallel to each other along the Z-axis direction to a rectangular plate-like vertical base 71 fixed to a gate-type column 110, a rotatable ball screw 73 disposed along the Z-axis direction between the guide rails 72, and a servo motor 74 as a rotation drive source connected to the upper end of the ball screw 73. Here, the lower end of the ball screw 73 is rotatably supported by the base 100 via a bearing (not shown), and the ball screw 73 is screwed into a nut member (not shown) attached to the slider 61.

[0031] Therefore, when the servo motor 74 is started to rotate the ball screw 73 forward and backward, the slider 61, to which a nut member (not shown) that screws into the ball screw 73 is attached, moves up and down in the Z-axis direction along a pair of guide rails 72, so that the pressure bar 62 and upper bar 63 attached to the slider 61 move up and down together in the Z-axis direction.

[0032] (Ultrasonic vibration unit) The ultrasonic vibration imparting unit 80 imparts ultrasonic vibration to the pressing bar 62 in a dividing step of the wafer W, which will be described later, and is composed of an ultrasonic vibrator 81 provided at the middle of the vertical part 62B of the pressing bar 62 in the height direction, and a high-frequency power source 82 for supplying high-frequency power to the ultrasonic vibrator 81. Here, as shown in FIG. 1, the high-frequency power source 82 is attached to a gate-shaped column 110, and a power cord 83 extending from the high-frequency power source 82 is electrically connected to the ultrasonic vibrator 81 provided on the pressing bar 62.

[0033] [Wafer division method] First Embodiment Next, a method for dividing the wafer W according to the first embodiment of the first invention, which is carried out using the dividing apparatus 1 configured as above, will be described. This dividing method includes the following steps: 1) Holding process 2) Clamping process 3)Dividing process The above steps are sequentially performed on the wafer W in this order to divide the wafer W into a plurality of chips. Hereinafter, 1) the holding step, 2) the clamping step, and 3) the dividing step will be described in order with reference to Figs. 4 to 6.

[0034] 1) Holding process: In the holding process, as shown in Figure 4, the work set WS is placed on the holding table 10, and with the outer periphery of the ring frame F of the work set WS in contact with the two fixed clamps 11, the pressers 12a of the other two movable clamps 12 are moved radially inward on the holding table 10 to press the outer periphery of the ring frame F against the two fixed clamps 11, thereby positioning the ring frame F (i.e., the work set WS) on the holding table 10 and holding it in that state.

[0035] Inside the wafer W, modified layers are formed in a grid pattern along the streets L1 and L2 (see FIG. 2). That is, a laser beam having a wavelength that is transparent to the wafer W is focused on the inside of the wafer W and irradiated along the streets L1 and L2, thereby forming vertical modified layers along the streets L1 and L2 partially inside the wafer W, and these modified layers are used as the dividing points g. Here, the modified layer refers to an area whose density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding area.

[0036] 2) Clamping process: In the clamping process, as shown in FIG. 5, the lower bar 31 is raised by the lower bar lifting mechanism 50, and the tip of the lower bar 31 abuts on a position aligned with the street L1 or L2 (division starting point g) on ​​the lower surface of the wafer W via the sheet T. In addition, the slider 61 and the pressing bar 62 and upper bar 63 supported by the pressing bar lifting mechanism 70 are lowered, and the lower surface of the upper bar 63 abuts on a position aligned with the street L1 or L2 (division starting point g) on ​​the upper surface of the wafer W, and the pressing bar 62 abuts on a position offset in the -Y-axis direction from the division starting point g on the upper surface of the wafer W. Therefore, the portion of the wafer W where the division starting point g is formed is clamped by the upper bar 63 and the lower bar 31. The surface of the wafer W is imaged by an imaging unit (not shown), and the positions of the streets L1 and L2 are detected by image processing such as pattern matching of the image obtained by imaging.

[0037] 3) Splitting process: 6, in the dividing step, ultrasonic vibration is applied from an ultrasonic vibration applying unit 80 to a pressing bar 62 whose knife-edge-shaped lower end comes into contact with the upper surface of the wafer W at a position offset from the dividing starting point g in the -Y-axis direction and presses the upper surface with a predetermined force. That is, when a high-frequency power supply 82 of the ultrasonic vibration applying unit 80 is turned on and high-frequency power is applied to an ultrasonic vibrator 81 via a power cord 83, the ultrasonic vibrator 81 is activated (excited) and the pressing bar 62 ultrasonically vibrates, so that the wafer W is reliably divided starting from the dividing starting point g by brittle fracture (fatigue fracture due to repeated stress) caused by vibration energy propagated from the pressing bar 62.

[0038] Then, when division along the street L1 in one direction is completed, the holding table 10 and the wafer W held thereon are moved in the Y-axis direction (indexing direction) by one pitch (the interval between adjacent streets L1) by the horizontal movement mechanism 20 shown in Fig. 1, and the same division of the wafer W is performed on the next street L1. Then, when division of the wafer W along all of the streets L1 in one direction is completed, the holding table 10 and the wafer W (work set WS) held thereon are rotated by an angle of 90 degrees around a vertical axis center by a rotation mechanism (not shown), and division along the street L2 in the other direction perpendicular to the one street L1 is similarly performed. Then, when the wafer W is divided along all of the streets L2 in the other direction, a series of division operations for the wafer W is completed, and a plurality of chips are obtained by dividing the wafer W.

[0039] As described above, according to the division method according to the first embodiment of the first invention, even if the wafer W has a metal film S formed on the back surface, the wafer W can be divided reliably from the division starting point g in a short time without applying a large force to the wafer W, and the chips obtained by division are not damaged. In addition, in this embodiment, the pressing bar 62 abuts against the upper surface of the wafer W at a position offset from the division starting point g in the -Y axis direction and presses the upper surface with a predetermined force, so that a bending stress acts on the division starting point g, and the wafer W is divided reliably from the division starting point g in a short time by this bending stress. In addition, even if the wafer W is thick, the wafer W can be divided reliably from the division starting point g in a short time without applying a large force to the wafer W, and the chips obtained by division are not damaged.

[0040] <Second embodiment> Next, a method for dividing the wafer W according to the second embodiment of the first invention will be described. This dividing method is similar to the first embodiment, in that: 1) Holding process 2) Clamping process 3)Dividing process This is a method for dividing a wafer W into a plurality of chips by sequentially carrying out the above steps on a wafer W. Hereinafter, 1) a holding step, 2) a clamping step, and 3) a dividing step will be described in order with reference to Figs. 7 to 9.

[0041] 1) Holding process: In the holding process, as shown in Figure 7, the work set WS is placed on the holding table 10, and with the outer periphery of the ring frame F of the work set WS in contact with the two fixed clamps 11, the pressers 12a of the other two movable clamps 12 are moved radially inward on the holding table 10 to press the outer periphery of the ring frame F against the two fixed clamps 11, thereby holding the ring frame F (i.e., the work set WS) in a positioned state on the holding table 10.

[0042] In this embodiment, the protective film f wound around the supply roll R1 is pulled out and taken up by the take-up roll R2, and the protective film f between the two rolls R1, R2 is pressed by the two guide rollers r, the pressure bar 62, and the upper bar 63 and is in a tensioned state above the wafer W.

[0043] 2) Clamping process: 8, in the clamping step, the lower bar 31 is raised by the lower bar lifting mechanism 50, and the tip of the lower bar 31 abuts at a position aligned with the street L1 or L2 (division starting point g) on ​​the lower surface of the wafer W via the sheet T. Also, the slider 61 and the pressing bar 62 and upper bar 63 supported thereby are lowered by the pressing bar lifting mechanism 70, and the lower surface of the upper bar 63 abuts at a position aligned with the street L1 or L2 (division starting point g) on ​​the upper surface of the wafer W via the protective film f, and the pressing bar 62 abuts at a position offset in the -Y-axis direction from the division starting point g on the upper surface of the wafer W via the protective film f. Therefore, the upper and lower surfaces of the wafer W are clamped by the upper bar 63 and the lower bar 31 via the protective film f and the sheet T at the portion where the division starting point g is formed.

[0044] 3) Splitting process: 9, in the dividing step, ultrasonic vibration is applied from an ultrasonic vibration applying unit 80 to a pressing bar 62 whose knife-edge-shaped lower end comes into contact with the upper surface of the wafer W at a position offset from the dividing starting point g in the -Y-axis direction and presses the upper surface with a predetermined force. That is, when a high-frequency power supply 82 of the ultrasonic vibration applying unit 80 is turned on and high-frequency power is applied to an ultrasonic vibrator 81 via a power cord 83, the ultrasonic vibrator 81 is activated (excited) and the pressing bar 62 ultrasonically vibrates, so that the wafer W is reliably divided starting from the dividing starting point g by brittle fracture (fatigue fracture due to repeated stress) caused by vibration energy propagated from the pressing bar 62.

[0045] In this embodiment, the upper surface of the portion including the division starting point g, which is the division portion of the wafer W to be divided in the division process, is covered with a protective film f as shown in Figure 9. Therefore, the device D is protected by the protective film f, and the protective film f prevents division powder generated by the division of the wafer W from scattering to the surrounding area.

[0046] Then, when the division along the street L1 in one direction is completed, cutting is performed on the next street L1 in the same manner as in the first embodiment. Then, when the division of the wafer W along all of the streets L1 in one direction is completed, the holding table 10 and the wafer W (work set WS) held thereon are rotated by an angle of 90 degrees around a vertical axis center by a rotation mechanism (not shown), and division along the street L2 in the other direction perpendicular to the one street L1 is similarly performed. Then, when the wafer W is divided along all of the streets L2 in the other direction, a series of division operations for the wafer W is completed, and a plurality of chips are obtained by dividing the wafer W. In this embodiment, the same effects as those obtained in the first embodiment can be obtained.

[0047] [Second Invention] Next, the second invention will be described.

[0048] First Embodiment First, the configuration of a dividing apparatus 1A for carrying out the dividing method of a wafer W according to the first embodiment of the second invention is shown in FIG. 10. Since the basic configuration of the dividing apparatus 1A shown in the figure is the same as the basic configuration of the dividing apparatus 1 according to the first invention shown in FIG. 1, in FIG. 10, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and repeated explanation of them will be omitted below.

[0049] In the dividing apparatus 1A shown in Fig. 10, a rectangular block-shaped support part 90 is disposed inside a ring-shaped holding table 10, and a rectangular plate-shaped elastic member 91 that elastically deforms to allow deformation of the wafer W during division is attached to the flat upper surface of this support part 90. In addition, the pressing bar mechanism 60 includes a pressing bar 62 attached perpendicularly to a slider 61, and a pressing bar lifting mechanism 70 that lifts and lowers the pressing bar 62. The other configurations are the same as those of the dividing apparatus 1 according to the first invention shown in Fig. 1.

[0050] Thus, the method for dividing a wafer W according to the first embodiment of the second invention, which is carried out using the dividing apparatus 1A shown in FIG. 10, is as follows: 1) Holding process 2)Dividing process The above steps are carried out in sequence to divide the wafer W into a plurality of chips. The following describes 1) the holding step and 2) the dividing step in sequence with reference to FIGS.

[0051] 1) Holding process: The holding process is the same as the holding process in the first invention, and as shown in Figure 11, the work set WS is placed on the holding table 10, and the outer periphery of the ring frame F of the work set WS is placed against the two fixed clamps 11. With this, the pressing members 12a of the other two movable clamps 12 are moved radially inward on the holding table 10 to press the outer periphery of the ring frame F against the two fixed clamps 11, thereby holding the ring frame F (i.e., the work set WS) in a positioned state on the holding table 10.

[0052] As described above, when the ring frame F of the work set WS is positioned and held on the holding table 10, the lower surface of the wafer W is received and supported by the support portion 90 via the sheet T and the elastic member 91.

[0053] 2) Splitting process: In the dividing step, as shown in Fig. 11, the knife-edge-shaped lower end of the pressing bar 62 is positioned at the dividing starting point g of the wafer W and presses the upper surface of the wafer W, and then ultrasonic vibration is applied to the pressing bar 62 from the ultrasonic vibration applying unit 80. That is, when the high-frequency power supply 82 of the ultrasonic vibration applying unit 80 is turned on and high-frequency power is applied to the ultrasonic vibrator 81 via the power cord 83, the ultrasonic vibrator 81 is started (excited) and the pressing bar 62 is ultrasonically vibrated, so that the wafer W is reliably divided from the dividing starting point g by brittle fracture (fatigue fracture due to repeated stress) caused by the vibration energy propagated from the pressing bar 62. In this dividing step, the elastic member 91 is elastically deformed at the dividing starting point g of the wafer W to allow the wafer W to deform, so that the wafer W is effectively divided from the dividing starting point g.

[0054] Then, when division along the street L1 in one direction is completed, the holding table 10 and the wafer W held thereon are moved by one pitch in the Y-axis direction (indexing direction) by the horizontal movement mechanism 20 shown in Fig. 10, and the same division of the wafer W is performed on the next street L1. Then, when division of the wafer W along all the streets L1 in one direction is completed, the holding table 10 and the wafer W (work set WS) held thereon are rotated by an angle of 90 degrees around a vertical axis center by a rotation mechanism (not shown), and division is similarly performed along the street L2 in the other direction perpendicular to the one street L1. Then, when the wafer W is divided along all the streets L2 in the other direction, a series of division operations for the wafer W is completed, and a plurality of chips are obtained.

[0055] As described above, according to the dividing method of the first embodiment of the second invention, even if the wafer W has a metal film S formed on the back surface, the wafer W can be divided reliably from the dividing starting point g in a short time without applying a large force, and the chips obtained by dividing are not damaged. In addition, even if the wafer W is thick, the wafer W can be divided reliably from the dividing starting point g in a short time without applying a large force, and the chips obtained by dividing are not damaged.

[0056] <Second embodiment> Next, a second embodiment of the second invention will be described with reference to FIGS.

[0057] FIG. 13 shows the configuration of a dividing apparatus 1B for carrying out a dividing method for a wafer W according to a second embodiment of the second invention. Since the basic configuration of the dividing apparatus 1B shown in the figure is the same as the basic configuration of the dividing apparatuses 1, 1A shown in FIGS. 1 and 10, in FIG. 13, the same elements as those shown in FIGS. 1 and 10 are denoted by the same reference numerals, and repeated explanation of them will be omitted below.

[0058] In the dividing device 1B shown in Fig. 13, two support parts 90 in the form of rectangular blocks long in the X-axis direction are arranged at a predetermined interval in the Y-axis direction inside the ring-shaped holding table 10. In addition, the pressing bar mechanism 60 includes a pressing bar 62 attached perpendicularly to a slider 61, and a pressing bar lifting mechanism 70 for raising and lowering the pressing bar 62. The other configurations are the same as those of the dividing device 1A according to the first embodiment shown in Fig. 10.

[0059] Thus, the method for dividing a wafer W according to the second embodiment of the second invention, which is carried out using the dividing apparatus 1B shown in FIG. 13, is as follows: 1) Holding process 2)Dividing process The above steps are carried out in sequence to divide the wafer W into a plurality of chips. The following describes 1) the holding step and 2) the dividing step in sequence with reference to FIGS.

[0060] 1) Holding process: The holding process is the same as the holding process in the first invention, and as shown in Figure 14, the work set WS is placed on the holding table 10, and the outer periphery of the ring frame F of the work set WS is placed against the two fixed clamps 11. With this, the pressers 12a of the other two movable clamps 12 are moved radially inward on the holding table 10 to press the outer periphery of the ring frame F against the two fixed clamps 11, thereby holding the ring frame F (i.e., the work set WS) in a positioned state on the holding table 10.

[0061] As described above, when the ring frame F of the work set WS is held in a positioned state on the holding table 10, the lower surface of the wafer W is received and supported by the two supports 90 via the sheet T.

[0062] 2) Splitting process: In the dividing step, as shown in Fig. 15, the knife-edge-shaped lower end of the pressing bar 62 is positioned at the dividing starting point g of the wafer W and presses the upper surface of the wafer W, and then ultrasonic vibration is applied to the pressing bar 62 from the ultrasonic vibration applying unit 80. That is, when the high-frequency power supply 82 of the ultrasonic vibration applying unit 80 is turned on and high-frequency power is applied to the ultrasonic vibrator 81 via the power cord 83, the ultrasonic vibrator 81 is started (excited) and the pressing bar 62 is ultrasonically vibrated, so that the wafer W is reliably divided from the dividing starting point g by brittle fracture (fatigue fracture due to repeated stress) caused by the vibration energy propagated from the pressing bar 62. Note that the lower surface of the divided portion including the dividing starting point g of the wafer W is supported by two supporting parts 90 arranged side by side along the Y-axis direction with a gap between them, and therefore the deformation of the wafer W during division is permitted by the gap between the two supporting parts 90.

[0063] Then, when division along the street L1 in one direction is completed, the holding table 10 and the wafer W held thereon are moved by one pitch in the Y-axis direction (indexing direction) by the horizontal movement mechanism 20 shown in Fig. 13, and the same division of the wafer W is performed on the next street L1. Then, when division of the wafer W along all the streets L1 in one direction is completed, the holding table 10 and the wafer W (work set WS) held thereon are rotated by an angle of 90 degrees around a vertical axis center by a rotation mechanism (not shown), and division along the street L2 in the other direction perpendicular to the one street L1 is similarly performed. Then, when the wafer W is divided along all the streets L2 in the other direction, a series of division operations for the wafer W is completed, and a plurality of chips are obtained.

[0064] As described above, according to the dividing method of the second embodiment of the second invention, as with the dividing method of the first embodiment, even if the wafer W has a metal film S formed on its back surface, the wafer W can be divided reliably from the dividing starting point g in a short time without applying a large force, and the chips obtained by dividing are not damaged. Note that even if the wafer W is thick, the wafer W can be divided reliably from the dividing starting point g in a short time without applying a large force, and the chips obtained by dividing are not damaged.

[0065] In the above embodiment, the modified layer formed inside the wafer W by irradiation with a laser beam is used as the splitting starting point g. However, other methods for forming the splitting starting point g in the wafer W may be used, such as blade dicing, in which the wafer W is cut along the streets with a cutting blade to form kerfs, plasma dicing, in which grooves are formed in the wafer W along the streets by plasma etching under vacuum, and laser ablation, in which a laser beam is irradiated onto the surface of the wafer W to form grooves in the wafer W along the streets.

[0066] In addition, the present invention is not limited to the application of the embodiments described above, and various modifications are possible within the scope of the claims and the technical ideas described in the specification and drawings. [Explanation of symbols]

[0067] 1, 1A, 1B: splitting device, 10: holding table, 11: fixing clamp, 12: movable clamp, 12a: movable clamp pressure member, 20: horizontal movement mechanism, 21: slider, 22: guide rail, 23: ball screw, 24: servo motor, 25: nut member, 30: lower bar mechanism, 31: lower bar, 40: lower bar rotation mechanism, 41: rotating shaft, 42: frame, 43: driven gear, 44: electric motor, 45: drive gear, 50: Lower bar lifting mechanism, 51: Base, 52: Guide rail, 53: Ball screw, 54: servo motor, 55: bearing, 60: pressure bar mechanism, 61: slider, 62: pressure bar, 62A: horizontal part of pressure bar, 62B: vertical part of pressure bar, 63: upper bar, 64: gap adjustment mechanism, 65: shaft, 66: damper, 70: pressure bar lifting mechanism, 71: base, 72: guide rail, 73: ball screw, 74: servo motor, 80: ultrasonic vibration imparting unit, 81: ultrasonic vibrator, 82: high frequency power source, 83: power cord, 90: support, 91: elastic member, 100: base, 110: gate-shaped column, D: device, F: ring frame, f: protective film, g: splitting point, L1, L2: Street, R1, R2: Roll, r: Guide roller, S: Metal film, T: Sheet, W: Wafer, WS: Work set

Claims

1. A method for dividing a wafer having grid-like streets formed on a surface thereof, the method comprising the steps of: dividing the wafer at division starting points formed along the streets, the method comprising the steps of: a holding step of holding the ring frame, which supports the wafer via a sheet attached to the ring frame and the back surface of the wafer, on a ring-shaped holding table; a clamping step of clamping the wafer between a lower bar that contacts the lower surface of the sheet linearly along the street and an upper bar that contacts the upper surface of the wafer along the street; a dividing step of ultrasonically vibrating a pressing bar extending parallel to the upper bar and pressing the pressing bar against an upper surface of the wafer away from the upper bar, thereby dividing the wafer from the dividing starting point; A method for dividing a wafer comprising the steps of:

2. A method for dividing a wafer having grid-like streets formed on a surface thereof, the method comprising the steps of: dividing the wafer at division starting points formed along the streets, the method comprising the steps of: a holding step of holding the ring frame, which supports the wafer via a sheet attached to the ring frame and the back surface of the wafer, on a ring-shaped holding table; a dividing step of ultrasonically vibrating a pressing bar extending from above the street of the wafer against the street while supporting the lower surface of the sheet by a supporting portion, thereby dividing the wafer from the dividing starting point; A method for dividing a wafer comprising the steps of:

3. A wafer dividing apparatus for carrying out the wafer dividing method according to claim 1, comprising: a ring-shaped holding table for holding a ring frame of a work set configured by attaching a sheet to a ring frame and a wafer and supporting the wafer on the ring frame via the sheet; a lower bar disposed inside the holding table and abutting against the sheet of the work set held on the holding table; A lower bar lifting mechanism for lifting the lower bar; an upper bar disposed opposite to the lower bar and in contact with an upper surface of the wafer of the work set held on the holding table; an upper bar lifting mechanism for lifting the upper bar; A pressing bar that is arranged parallel to the upper bar and presses the wafer; an ultrasonic vibrator that is disposed on the pressure bar and ultrasonically vibrates the pressure bar; A wafer dividing apparatus comprising:

4. A wafer dividing apparatus for carrying out the wafer dividing method according to claim 2, comprising: a ring-shaped holding table for holding a ring frame of a work set configured by attaching a sheet to a ring frame and a wafer and supporting the wafer on the ring frame via the sheet; a support portion that is disposed inside the holding table and supports a lower surface of the sheet of the work set held on the holding table; a pressing bar extending along the street of the wafer and pressing the street from above; an ultrasonic vibrator that is disposed on the pressure bar and ultrasonically vibrates the pressure bar; A wafer dividing apparatus comprising:

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