Processing method of workpiece

Abstract

To provide a processing method for a workpiece that can suppress remaining of burrs.SOLUTION: The processing method for a workpiece, which processes the workpiece having an electrode embedded therein, includes: a holding step of making a chuck table hold a front surface side of the workpiece; a grinding step of grinding the workpiece and exposing the electrode at a rear surface side of the workpiece, by bringing a grinding stone into contact with the rear surface side of the workpiece held by the chuck table, while rotating a grinding wheel including the grinding stone in a first direction, after the holding step; and an electrode processing step of processing the electrode, by bringing the grinding stone into contact with the electrode exposed at the rear surface side of the workpiece held by the chuck table, while rotating the grinding wheel in a second direction which is opposite to the first direction, after the grinding step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for machining a workpiece in which an electrode is embedded. [Background technology]

[0002] The device chip manufacturing process uses a wafer in which devices are formed in multiple areas defined by multiple intersecting streets (planned division lines). By dividing this wafer along the streets, multiple device chips, each equipped with a device, are obtained. The device chips are incorporated into various electronic devices, such as mobile phones and personal computers.

[0003] In recent years, in order to increase the integration density of devices, a technology for manufacturing a device chip (stacked device chip) having multiple stacked devices has been put to practical use. For example, a stacked device chip is manufactured by stacking multiple device chips and connecting the devices with through-silicon vias (TSVs) that penetrate the device chips from top to bottom. The use of through-silicon vias allows the wiring connecting the devices to be shorter compared to wire bonding, etc., which allows for the miniaturization of stacked device chips and the improvement of their processing speed.

[0004] When manufacturing a stacked device chip in which stacked devices are connected by through electrodes, a wafer with through electrodes is used (see Patent Document 1). For example, a stacked wafer is formed by stacking multiple wafers with through electrodes and connecting the devices included in each wafer with the through electrodes. Multiple stacked device chips are obtained by dividing this stacked wafer along the streets. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-53218 Summary of the Invention [Problem to be solved by the invention]

[0006] When forming a through electrode in a workpiece such as a wafer, first, a groove formed on the front side of the workpiece is filled with a conductive material to form a workpiece with an electrode buried therein. Then, the back side of the workpiece is ground to expose the buried electrode on the back side of the workpiece, thereby forming a through electrode that penetrates the workpiece in the thickness direction.

[0007] A grinding machine is used to grind a workpiece. The grinding machine includes a chuck table that holds the workpiece and a grinding unit that grinds the workpiece. A grinding wheel including multiple grinding stones is attached to the grinding unit. The workpiece is held by the chuck table, and the grinding stone is brought into contact with the backside of the workpiece while the chuck table and grinding wheel are rotated, thereby grinding the backside of the workpiece.

[0008] However, if the workpiece is ground until the buried electrodes are exposed on the backside of the workpiece, the grinding wheel will come into contact with the exposed electrodes on the backside of the workpiece in the final stage of the grinding process. At this time, the electrodes are stretched by the grinding wheel rotating at high speed, and whisker-like burrs may form extending from the electrodes. These burrs can cause problems such as deformation of the through-hole electrodes on the backside of the workpiece and short circuits between adjacent electrodes, resulting in reduced quality of device chips.

[0009] The present invention has been made in view of the above problem, and has an object to provide a method for processing a workpiece that can suppress the remaining burrs. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided a method for machining a workpiece having an embedded electrode, the method comprising: a holding step of holding the front side of the workpiece on a chuck table; a grinding step of, after the holding step, rotating a grinding wheel including a grinding stone in a first direction and bringing the grinding stone into contact with the back side of the workpiece held on the chuck table to grind the workpiece and expose the electrode on the back side of the workpiece; and an electrode machining step of, after the grinding step, rotating the grinding wheel in a second direction opposite to the first direction and bringing the grinding stone into contact with the electrode exposed on the back side of the workpiece held on the chuck table to machine the electrode. The amount of the workpiece ground in the electrode machining step is smaller than the amount of the workpiece ground in the grinding step. A method for processing a workpiece is provided. According to another aspect of the present invention, there is provided a method for machining a workpiece having an embedded electrode, the method including: a holding step of holding a front side of the workpiece on a chuck table; a grinding step of, after the holding step, rotating a grinding wheel including a grinding stone in a first direction and bringing the grinding stone into contact with a back side of the workpiece held on the chuck table to grind the workpiece and expose the electrode on the back side of the workpiece; and an electrode machining step of, after the grinding step, rotating the grinding wheel in a second direction opposite to the first direction and bringing the grinding stone into contact with the electrode exposed on the back side of the workpiece held on the chuck table to machine the electrode, wherein a machining feed rate in the electrode machining step is slower than a machining feed rate in the grinding step. The processing feed rate in the electrode processing step may be 1 μm / s or less. [Effects of the Invention]

[0011] In a method for processing a workpiece according to one aspect of the present invention, the workpiece is ground with a grinding wheel rotated in a first direction to expose an electrode on the back side of the workpiece, and then the electrode is processed with a grinding wheel rotated in a second direction opposite to the first direction. This reduces or removes burrs extending from the electrode, thereby suppressing the burrs from remaining after grinding. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1(A) is a perspective view showing a workpiece, FIG. 1(B) is a cross-sectional view showing the workpiece, and FIG. 1(C) is a perspective view showing a device. [Figure 2] FIG. [Figure 3] FIG. 2 is a cross-sectional view showing a chuck table. [Figure 4] 1 is a flowchart showing a method for processing a workpiece. [Figure 5] FIG. 2 is a side view showing the grinding apparatus in which a workpiece is held by a chuck table. [Figure 6]FIG. 6(A) is a side view showing a grinding device that grinds a workpiece, FIG. 6(B) is a side view showing a grinding device that separates a grinding wheel from a workpiece, and FIG. 6(C) is a side view showing a grinding device that processes an electrode. [Figure 7] FIG. 7(A) is a plan view showing the workpiece in the grinding step, and FIG. 7(B) is a plan view showing the electrode in the grinding step. [Figure 8] Fig. 8(A) is a plan view showing the workpiece in the electrode machining step, and Fig. 8(B) is a plan view showing the electrode in the electrode machining step. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present invention will be described below with reference to the accompanying drawings. First, an example of the structure of a workpiece that can be processed by the method for processing a workpiece according to this embodiment will be described. Fig. 1(A) is a perspective view of a workpiece 11, and Fig. 1(B) is a cross-sectional view of the workpiece 11.

[0014] For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as single crystal silicon, and has a front surface (first surface) 11a and a back surface (second surface) 11b that are generally parallel to each other. The workpiece 11 is divided into a plurality of rectangular regions by a plurality of streets (planned division lines) 13 that are arranged in a grid pattern so as to intersect with each other. Furthermore, devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed in each of the plurality of regions divided by the streets 13 on the front surface 11a of the workpiece 11.

[0015] However, there are no limitations on the material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a substrate (wafer) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15.

[0016] 1(C) is a perspective view showing device 15. For example, device 15 includes a plurality of electrodes 17 that are exposed on the surface of device 15 and are connected to other wiring, electrodes, devices, etc. Note that connection electrodes such as bumps may be formed on the surfaces of electrodes 17.

[0017] Furthermore, a plurality of electrodes (via electrodes, through electrodes) 19 are buried inside each of a plurality of regions partitioned by the streets 13 of the workpiece 11. The electrodes 19 are formed in a columnar shape along the thickness direction of the workpiece 11, and are connected to the electrodes 17 of the device 15, etc. There are no limitations on the material of the electrodes 19, and for example, a conductive material such as copper, tungsten, or aluminum may be used.

[0018] The electrodes 19 are each formed from the device 15 toward the rear surface 11b of the workpiece 11, and the length (height) of the electrodes 19 is less than the thickness of the workpiece 11. Therefore, the electrodes 19 are not exposed on the rear surface 11b of the workpiece 11, but are buried inside the workpiece 11. In addition, an insulating film (not shown), such as a silicon oxide film, is provided between the workpiece 11 and the electrodes 19 to insulate the workpiece 11 from the electrodes 19.

[0019] For example, an insulating film is formed on the inner wall of a columnar groove formed on the surface 11a side of the workpiece 11, and then a conductive material is filled into the groove. This forms the workpiece 11 with the electrode 19 buried therein. Thereafter, a device 15 including a semiconductor element, an electrode, wiring, an insulating film, etc. is formed on the surface 11a side of the workpiece 11, and the device 15 is connected to the electrode 19.

[0020] When the back surface 11b of the workpiece 11 is ground to thin the workpiece 11, the lower end of the electrode 19 is exposed on the back surface 11b of the workpiece 11. As a result, the electrode 19 becomes a through electrode that penetrates the workpiece 11 in the thickness direction, and the electrode 19 can be connected to other wiring, electrodes, devices, etc. In this way, the workpiece 11 having a through electrode is formed.

[0021] A grinding device is used to grind the workpiece 11. FIG. 2 is a perspective view showing the grinding device 2. In FIG. 2, the X-axis direction (first horizontal direction, front-to-back direction) and the Y-axis direction (second horizontal direction, left-to-right direction) are perpendicular to each other. The Z-axis direction (processing feed direction, vertical direction, height direction, up-down direction) is perpendicular to the X-axis and Y-axis directions. The grinding device 2 includes a chuck table (holding table) 4 that holds the workpiece 11, and a grinding unit 10 that grinds the workpiece 11.

[0022] The chuck table 4 has a cylindrical frame (main body) 6 made of metal such as SUS (stainless steel), glass, ceramics, resin, or the like. A cylindrical recess 6b is provided in the center of the upper surface 6a of the frame 6. A disk-shaped holding member 8 made of a porous material such as porous ceramics is fitted into the recess 6b. The holding member 8 includes holes (flow paths) that communicate from the upper surface to the lower surface of the holding member 8. The upper surface of the holding member 8 forms a circular suction surface 8a that sucks the workpiece 11 when the workpiece 11 is held by the chuck table 4.

[0023] The depth of the recess 6b and the thickness of the holding member 8 are set to be approximately the same, and the upper surface 6a of the frame 6 and the suction surface 8a of the holding member 8 are arranged on approximately the same plane. The upper surface 6a of the frame 6 and the suction surface 8a of the holding member 8 form the holding surface 4a of the chuck table 4. The holding surface 4a (suction surface 8a) is connected to a suction source (not shown) such as an ejector via holes included in the holding member 8, a flow path 6c (see FIG. 3) formed inside the frame 6, a valve (not shown), etc.

[0024] A moving unit (not shown) that moves the chuck table 4 horizontally (in the XY plane) is connected to the chuck table 4. For example, a ball screw type moving mechanism or a turntable is used as the moving unit. In addition, a rotation drive source (not shown) such as a motor is connected to the chuck table 4 to rotate the chuck table 4 around a rotation axis set in a direction perpendicular to the holding surface 4a.

[0025] 3 is a cross-sectional view showing the chuck table 4. The holding surface 4a of the chuck table 4 is formed in a conical shape with its apex at the center of the holding surface 4a and is slightly inclined relative to the radial direction of the holding surface 4a. The chuck table 4 is arranged in a slightly inclined state so that a holding region 4b, which corresponds to a part of the holding surface 4a and extends from the center to the outer periphery of the holding surface 4a, is arranged parallel to the horizontal plane. The rotation axis of the chuck table 4 is set along a direction perpendicular to the radial direction of the holding surface 4a and is slightly inclined relative to the vertical direction.

[0026] 3, for ease of explanation, the inclination of the holding surface 4a is exaggerated, but the actual inclination of the holding surface 4a is small. For example, when the diameter of the holding surface 4a is approximately 290 mm or more and 310 mm or less, the difference in height between the center of the holding surface 4a and the outer circumferential edge of the holding surface 4a (corresponding to the height of the cone) is set to approximately 20 μm or more and 40 μm or less.

[0027] As shown in Fig. 2, a grinding unit 10 is disposed above the chuck table 4. The grinding unit 10 includes a cylindrical spindle 12 disposed along the Z-axis direction. A disk-shaped mount 14 made of metal or the like is fixed to the tip end (lower end) of the spindle 12. A rotation drive source (not shown), such as a motor, that rotates the spindle 12 in both directions is connected to the base end (upper end) of the spindle 12.

[0028] An annular grinding wheel 16 for grinding the workpiece 11 is attached to the underside of the mount 14. The grinding wheel 16 is a processing tool that can be attached to and detached from the mount 14, and is fixed to the mount 14 with a fixing device such as a bolt.

[0029] The grinding wheel 16 includes an annular wheel base 18 made of metal (aluminum, stainless steel, etc.), resin, etc., and formed to have roughly the same diameter as the mount 14. The upper surface of the wheel base 18 is fixed to the lower surface of the mount 14. In addition, a plurality of grinding stones 20 are fixed to the lower surface of the wheel base 18.

[0030] The grinding wheels 20 are formed by fixing abrasive grains made of diamond, cBN (cubic boron nitride), or the like with a bonding material (bond material) such as a metal bond, a resin bond, or a vitrified bond. For example, multiple grinding wheels 20 are formed in a rectangular parallelepiped shape and arranged in a ring shape at approximately equal intervals along the outer periphery of the wheel base 18. However, there are no limitations on the material, shape, structure, size, etc. of the grinding wheels 20. Furthermore, the number and arrangement of the grinding wheels 20 can be set as desired.

[0031] A ball screw type moving mechanism (not shown) that moves (raises and lowers) the grinding unit 10 along the Z-axis direction is connected to the grinding unit 10. The grinding wheel 16 rotates around a rotation axis that is roughly parallel to the Z-axis direction by power transmitted from a rotation drive source (not shown) connected to the base end of the spindle 12 via the spindle 12 and the mount 14.

[0032] When the grinding wheel 16 is rotated, each of the grinding stones 20 moves along a circular rotational orbit (movement path) that is roughly parallel to the horizontal plane (XY plane). With the grinding wheel 16 rotating, the grinding stones 20 are brought into contact with the workpiece 11 held by the chuck table 4, thereby grinding the workpiece 11.

[0033] Furthermore, a grinding fluid supply path (not shown) for supplying a liquid (grinding fluid) such as pure water is provided inside or near the grinding unit 10. When the grinding unit 10 grinds the workpiece 11, the grinding fluid is supplied to the workpiece 11 and the grinding wheel 20. This cools the workpiece 11 and the grinding wheel 20, and also washes away chips (grinding chips) generated by the grinding process.

[0034] Next, a specific example of a method for machining the workpiece 11 using the grinding device 2 will be described. FIG. 4 is a flowchart showing the method for machining the workpiece. The method for machining the workpiece according to this embodiment includes a holding step S1, a grinding step S2, and an electrode machining step S3. By sequentially performing the holding step S1, the grinding step S2, and the electrode machining step S3, the electrode 19 (see FIGS. 1(B) and 1(C)) is exposed on the back surface 11b side of the workpiece 11, and burrs formed on the electrode 19 are removed.

[0035] First, the surface 11a side of the workpiece 11 is held by the chuck table 4 (holding step S1). FIG.

[0036] The workpiece 11 is placed on the chuck table 4 so that the front surface 11a faces the holding surface 4a and the back surface 11b is exposed upward. At this time, the workpiece 11 is placed so that the center position of the workpiece 11 and the center position of the holding surface 4a overlap and so that the entire suction surface 8a (see FIG. 2) is covered by the workpiece 11. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 4a, the workpiece 11 is suction-held by the chuck table 4.

[0037] Strictly speaking, as mentioned above, the holding surface 4a of the chuck table 4 is formed in a conical shape (see FIG. 3). Therefore, when the workpiece 11 is held by the chuck table 4, the workpiece 11 is held in a slightly deformed state along the holding surface 4a.

[0038] A protective sheet for protecting the workpiece 11 may be attached to the front surface 11a of the workpiece 11. This allows the device 15 (see FIGS. 1(A) to 1(C)) formed on the front surface 11a of the workpiece 11 to be covered and protected by the protective sheet.

[0039] For example, the protective sheet may be a tape including a circular film-like substrate and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. The workpiece 11 is then held on the holding surface 4a of the chuck table 4 via the protective sheet.

[0040] Next, with the grinding wheel 16 rotated in the first direction, the grinding stone 20 is brought into contact with the back surface 11b of the workpiece 11 held by the chuck table 4, thereby grinding the workpiece 11 to expose the electrode 19 (see FIGS. 1(B) and 1(C)) on the back surface 11b of the workpiece 11 (grinding step S2). Fig. 6(A) is a side view showing the grinding device 2 that grinds the workpiece 11.

[0041] In the grinding step S2, first, the positional relationship between the chuck table 4 and the grinding wheel 16 is adjusted. Specifically, the chuck table 4 is positioned below the grinding unit 10 so that the center of the workpiece 11 overlaps with the rotational path of the grinding wheel 20. Then, the chuck table 4 and the grinding wheel 16 are each rotated in a predetermined direction at a predetermined number of rotations.

[0042] For example, in the grinding step S2, the chuck table 4 and the grinding wheel 16 are rotated clockwise in a plan view. This causes the grinding wheel 16 to rotate in a first direction (the direction indicated by arrow A). The rotation speed of the chuck table 4 is set to, for example, 60 rpm or more and 300 rpm or less, and the rotation speed of the grinding wheel 16 is set to, for example, 3000 rpm or more and 6000 rpm or less.

[0043] Next, with the chuck table 4 and grinding wheel 16 rotating, the grinding unit 10 is lowered along the Z-axis direction, bringing the workpiece 11 and the grinding wheel 16 closer to each other. The speed at which the grinding wheel 16 is lowered at this time, i.e., the relative movement speed in the Z-axis direction between the chuck table 4 (workpiece 11) and the grinding wheel 16, corresponds to the processing feed rate (grinding feed rate). The processing feed rate is set, for example, to 0.1 μm / s or more and 1 μm / s or less. However, the processing feed rate can be set appropriately depending on the type and material of the workpiece 11, the material of the grinding wheel 20, the amount of workpiece 11 ground (the difference in thickness of the workpiece 11 before and after grinding), etc.

[0044] When the grinding wheel 16 is lowered, the rotating grinding stone 20 comes into contact with the back surface 11b of the workpiece 11 held by the chuck table 4. As a result, the back surface 11b of the workpiece 11 is ground and scraped away, and the workpiece 11 is thinned.

[0045] 7(A) is a plan view showing the workpiece 11 in the grinding step S2. In the grinding step S2, the grinding wheel 20 comes into contact with a portion of the workpiece 11 that is supported by the holding region 4b (see FIG. 3) of the chuck table 4 or a region nearby, and grinds the workpiece 11 in an arc shape along a first direction (the direction indicated by arrow A, the direction from the outer periphery toward the center of the workpiece 11). Then, as the chuck table 4 rotates, the entire back surface 11b side of the workpiece 11 is ground by the grinding wheel 20.

[0046] When the workpiece 11 is ground to a predetermined thickness, the electrode 19 embedded in the workpiece 11 is exposed on the back surface 11b side of the workpiece 11. This causes the electrode 19 to become a through electrode that penetrates the workpiece 11 in the thickness direction, making it possible to connect the electrode 19 to other wiring, electrodes, devices, etc.

[0047] 7(B) is a plan view showing the electrode 19 in the grinding step S2. When the workpiece 11 is ground until the electrode 19 is exposed on the back surface 11b side of the workpiece 11, the grinding wheel 20 comes into contact with the electrode 19 in the final stage of the grinding step S2. At this time, the electrode 19 is stretched by the grinding wheel 20 rotating at high speed, and whisker-like burrs 19a may be formed along the rotation direction of the grinding wheel 20 (the direction indicated by arrow A in FIG. 7(A)).

[0048] The burrs 19a extend from the electrode 19 and protrude beyond the outer periphery of the electrode 19. These burrs 19a can cause problems such as deformation of the electrode 19 on the back surface 11b side of the workpiece 11 and short circuits between adjacent electrodes 19. Therefore, in this embodiment, the burrs 19a are reduced or removed by processing the electrode 19 with the grinding wheel 16 after the grinding step S2. This reduces the amount of burrs 19a remaining on the workpiece 11.

[0049] Specifically, first, after the grinding step S2, the grinding unit 10 is raised along the Z-axis direction to separate the workpiece 11 from the grinding wheel 20. Fig. 6(B) is a side view showing the grinding device 2 separating the grinding wheel 20 from the workpiece 11.

[0050] It is preferable that the rotation of the chuck table 4 be maintained even while the workpiece 11 is not in contact with the grinding wheel 20. This reduces the time required to rotate the chuck table 4 at a predetermined rotation speed in the subsequent electrode processing step S3.

[0051] Next, while the grinding wheel 16 is rotated in the second direction, the electrode 19 exposed on the back surface 11b of the workpiece 11 held by the chuck table 4 is brought into contact with the grinding stone 20, thereby machining the electrode 19 (electrode machining step S3). Fig. 6(C) is a side view showing the grinding device 2 that machines the electrode 19.

[0052] In the electrode machining step S3, first, the spindle 12 is rotated in a direction opposite to the rotation direction of the spindle 12 in the grinding step S2. This causes the grinding wheel 16 to rotate in a second direction (direction indicated by arrow B) opposite to the first direction. For example, if the grinding wheel 16 is rotated clockwise in a plan view in the grinding step S2, the grinding wheel 16 is rotated counterclockwise in a plan view in the electrode machining step S3. The rotation speed of the chuck table 4 is set, for example, to 60 rpm or more and 300 rpm or less, and the rotation speed of the grinding wheel 16 is set, for example, to 3000 rpm or more and 6000 rpm or less.

[0053] Next, with the chuck table 4 and grinding wheel 16 rotating, the grinding unit 10 is lowered along the Z-axis direction to bring the workpiece 11 and the grinding wheel 16 closer to each other. As a result, the rotating grinding wheel 20 comes into contact with the electrode 19 exposed on the back surface 11b of the workpiece 11 held by the chuck table 4, and the electrode 19 is ground together with the back surface 11b of the workpiece 11.

[0054] As described above, if the workpiece 11 and the grinding wheel 20 are separated after the grinding step S2 (see FIG. 6(B)), friction between the workpiece 11 and the grinding wheel 20 is eliminated before the electrode machining step S3 is performed, and the workpiece 11 and the grinding wheel 20 are cooled. This reduces the likelihood of machining defects such as surface burn of the workpiece 11 occurring in the electrode machining step S3. Furthermore, in the electrode machining step S3, the grinding wheel 20 comes into contact with the workpiece 11 again from a state where it has been separated from the workpiece 11. At this time, wear on the underside of the grinding wheel 20 is promoted, and the condition of the grinding wheel 20 is improved.

[0055] 8(A) is a plan view showing the workpiece 11 in the electrode machining step S3. In the electrode machining step S3, the grinding wheel 20 comes into contact with a portion of the workpiece 11 that is supported by the holding region 4b (see FIG. 3) of the chuck table 4 or a region nearby, and grinds the workpiece 11 in an arc shape along the second direction (the direction indicated by the arrow B, the direction from the center of the workpiece 11 toward the outer periphery).

[0056] The movement direction (second direction) of the grinding wheel 20 relative to the workpiece 11 in the electrode processing step S3 is opposite to the movement direction (first direction) of the grinding wheel 20 relative to the workpiece 11 in the grinding step S2. Therefore, the grinding wheel 20 grinds the electrode 19 in the opposite direction to the grinding step S2. Then, as the chuck table 4 rotates, all of the electrode 19 exposed on the back surface 11b side of the workpiece 11 is processed by the grinding wheel 20.

[0057] 8(B) is a plan view showing the electrode 19 in the electrode processing step S3. When the grinding wheel 20 rotating in the second direction is brought into contact with the electrode 19, the grinding wheel 20 comes into contact with the electrode 19 in the direction opposite to the extension direction of the burr 19a (the direction from the tip end to the base end of the burr 19a). As a result, the burr 19a is scraped back toward the center of the electrode 19, and the burr 19a is reduced or removed.

[0058] The electrode processing step S3 is a process for reducing or removing the burrs 19a, and does not directly aim to thin the workpiece 11. Therefore, the grinding conditions in the electrode processing step S3 can be freely set within a range that allows the burrs 19a to be reduced or removed.

[0059] Specifically, the amount of workpiece 11 ground in electrode machining step S3 may be smaller than the amount of workpiece 11 ground in grinding step S2, thereby preventing excessive grinding of workpiece 11 and the generation of new burrs. For example, the amount of workpiece 11 ground in electrode machining step S3 can be set to 10 μm or less, preferably 5 μm or less.

[0060] Furthermore, the processing feed rate in the electrode processing step S3 (the lowering speed of the grinding wheel 16) may be lower than the processing feed rate in the grinding step S2. This reduces the load on the grinding wheel 20 in the electrode processing step S3, making it easier to remove the burrs 19a. For example, the processing feed rate in the electrode processing step S3 can be set to 1 μm / s or less, preferably 0.5 μm / s or less.

[0061] The processing of the workpiece 11 by the grinding apparatus 2 is controlled by a control unit (not shown) connected to the grinding apparatus 2. For example, the control unit is configured by a computer and includes an arithmetic unit that performs calculations necessary for the operation of the grinding apparatus 2, and a storage unit that stores various information (data, programs, etc.) used for the operation of the grinding apparatus 2. The arithmetic unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0062] A storage unit (memory) of the control unit stores a program describing a series of operations of the components of the grinding device 2 required to sequentially perform the holding step S1, grinding step S2, and electrode machining step S3. When machining the workpiece 11, the control unit reads the program from the storage unit, executes it, and sequentially outputs control signals to each component of the grinding device 2. This controls the operation of the grinding device 2, and the holding step S1, grinding step S2, and electrode machining step S3 are automatically performed.

[0063] As described above, in the method for processing a workpiece according to this embodiment, the workpiece 11 is ground with the grinding wheel 16 rotated in a first direction to expose the electrode 19 on the back surface 11b of the workpiece 11, and then the electrode 19 is processed with the grinding wheel 16 rotated in a second direction opposite to the first direction. This reduces or removes burrs extending from the electrode 19, thereby suppressing the burrs from remaining after grinding.

[0064] The structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0065] 11 Workpiece 11a Surface (first side) 11b Back side (2nd side) 13th Street (Planned division line) 15 devices 17 electrodes 19 Electrodes (via electrodes, through electrodes) 19a Bali 2 Grinding equipment 4 Chuck table (holding table) 4a Holding surface 4b Holding area 6 Frame (main body) 6a Top side 6b Recess 6c Flow path 8 Retaining member 8a Suction surface 10 Grinding unit 12 spindles 14 Mount 16 Grinding Wheel 18 Wheel base 20 Grinding Wheel

Claims

1. A method for processing a workpiece in which an electrode is embedded, comprising: a holding step of holding the front surface side of the workpiece on a chuck table; a grinding step in which, after the holding step, a grinding wheel including a grinding stone is rotated in a first direction, and the grinding stone is brought into contact with a back surface side of the workpiece held by the chuck table, thereby grinding the workpiece and exposing the electrode on the back surface side of the workpiece; and an electrode processing step of processing the electrode by bringing the grinding stone into contact with the electrode exposed on the back surface side of the workpiece held by the chuck table while rotating the grinding wheel in a second direction opposite to the first direction after the grinding step, The method for machining a workpiece, wherein the amount of the workpiece ground in the electrode machining step is smaller than the amount of the workpiece ground in the grinding step.

2. A method for processing a workpiece as described in claim 1, characterized in that the amount of grinding of the workpiece in the electrode processing step is 10 μm or less.

3. A method for processing a workpiece in which an electrode is embedded, comprising: a holding step of holding the front surface side of the workpiece on a chuck table; a grinding step in which, after the holding step, a grinding wheel including a grinding stone is rotated in a first direction, and the grinding stone is brought into contact with a back surface side of the workpiece held by the chuck table, thereby grinding the workpiece and exposing the electrode on the back surface side of the workpiece; and an electrode processing step of processing the electrode by bringing the grinding stone into contact with the electrode exposed on the back surface side of the workpiece held by the chuck table while rotating the grinding wheel in a second direction opposite to the first direction after the grinding step, A method for machining a workpiece, wherein a machining feed rate in the electrode machining step is smaller than a machining feed rate in the grinding step.

4. A method for processing a workpiece as described in claim 3, characterized in that the processing feed rate in the electrode processing step is 1 μm / s or less.

Images