Processing method of workpiece

Abstract

To provide a processing method of a workpiece comprising a substrate and a protection member bonded to a front surface side of the substrate, that can prevent a back surface side of the substrate from being formed into an uneven shape due to grinding of the back surface side of the substrate.SOLUTION: A protection member is embedded in a border of a plurality of devices each having a concave part on a front surface side of a substrate by depressing the protection member, and the protection member is ground to be flat on the front surface side of the protection member. In this case, a gap between the substrate and the protection member can be eliminated or miniaturized, and a gap between a chuck table holding the substrate via the protection member and the protection member can be eliminated or miniaturized. Therefore, by executing them in prior of the grinding on the back surface side of the substrate, it can be prevented that the back surface side of the substrate becomes an uneven shape due to the grinding on the back surface side of the substrate.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a method for processing a workpiece including a substrate having a surface side with an uneven shape formed by a plurality of devices formed on the surface side, and a protective member attached to each of the plurality of devices that form convex portions on the surface side of the substrate.

Background Art

[0002] Chips of devices such as ICs (Integrated Circuits) are essential components in various electronic devices such as mobile phones and personal computers. Such chips are manufactured, for example, in the following order.

[0003] First, photolithography or the like is performed to form a plurality of devices each including a large number of elements on the surface side of a substrate such as a wafer. Next, the back side of the substrate is ground to thin the substrate. Next, the substrate is cut along the boundaries of the plurality of devices to divide the substrate into a plurality of chips.

[0004] As a method for thinning the substrate, for example, grinding the back side of the substrate in a grinding apparatus can be mentioned (see, for example, Patent Document 1). This grinding apparatus generally includes a chuck table for holding the surface side of the substrate, and a spindle having a grinding wheel on which a plurality of grinding stones are discretely arranged in an annular shape attached to the tip.

[0005] When grinding the back side of the substrate in this grinding apparatus, both the chuck table and the spindle are rotated, and while supplying a liquid (grinding water) to the interface between the substrate and the grinding wheel, the chuck table and the grinding wheel are approached so that the plurality of grinding stones contact the back side of the substrate. Thereby, the back side of the substrate is ground while the substrate is pressed by the plurality of grinding stones.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2014-124690 [Overview of the project] [Problems that the invention aims to solve]

[0007] Grinding the back side of a substrate can cause damage to multiple devices formed on the front side of the substrate due to pressure. Therefore, grinding the back side of a substrate is generally performed after attaching a protective material to the front side of the substrate, with the substrate held by a chuck table via this protective material.

[0008] However, the surface of this substrate has an uneven shape. Specifically, when multiple devices are formed on the surface of the substrate, the areas where the multiple devices are formed become convex, and the areas where the multiple devices are not formed, i.e., the boundaries between the multiple devices, become concave. Therefore, even if a protective material is attached to the surface of the substrate, the protective material may not adhere to the areas that form the boundaries between the multiple devices, resulting in a gap between the substrate and the protective material.

[0009] Furthermore, if grinding is performed on the back side of the substrate in this state, the substrate, pressed by multiple grinding wheels, may deform and sink into the gap. Moreover, if the back side of the substrate is ground while it is deformed in this way, the areas that form the boundaries between multiple devices on the substrate cannot be sufficiently ground. As a result, in this case, the back side of the substrate after grinding may have an uneven surface.

[0010] On the other hand, by attaching a protective member softened by heating to the surface side of the substrate, the gap between the area forming the boundary of multiple devices and the protective member can be eliminated or reduced. However, in this case, the surface side of the protective member, i.e., the side not attached to the substrate, may have an uneven shape that reflects the uneven shape of the substrate's surface.

[0011] Specifically, when protective members are attached to the surface side of the substrate in this manner, the areas on the surface side of the protective members attached to the region where multiple devices are formed become convex, and the areas on the surface side of the protective members attached to the boundaries of multiple devices become concave. Therefore, even when the substrate is placed on the chuck table via this holding member, a gap may occur between the holding member and the chuck table.

[0012] Furthermore, if grinding is performed on the back side of the substrate in this state, the substrate and protective material, pressed by multiple grinding wheels, may deform and sink into the gap. Moreover, if the back side of the substrate is ground while the substrate and protective material are deformed in this way, the areas that form the boundaries between multiple devices on the substrate cannot be sufficiently ground. As a result, in this case, the back side of the substrate after grinding may have an uneven surface.

[0013] In view of these points, the object of the present invention is to provide a method for processing a workpiece comprising a substrate and a protective member attached to the surface side of the substrate, wherein grinding of the back side of the substrate can prevent the back side of the substrate from becoming uneven. [Means for solving the problem]

[0014] According to one aspect of the present invention, a method for processing a workpiece is provided, comprising: a substrate having an uneven surface shape due to the formation of a plurality of devices on its surface; and protective members attached to each of the plurality of devices that are convex on the surface of the substrate, the method comprising: a holding step of holding the back side of the substrate with a chuck table; an embedding step, after the holding step, bringing a first grinding wheel rotating while the chuck table is rotated closer to the chuck table so that the protective member is pressed and embedded in the boundary of the plurality of devices that are concave on the surface of the substrate; and a flattening step, after the embedding step, bringing a second grinding wheel rotating while the chuck table is rotated closer to the chuck table so that the protective member is ground and the surface of the protective member is flattened.

[0015] Furthermore, it is preferable to further include a grinding step in which the back surface of the substrate is ground after the planarization step.

[0016] Furthermore, in the embedding step, it is preferable that a liquid with a lower flow rate than the liquid supplied to the contact interface between the protective member and the second grinding wheel in the flattening step is supplied to the contact interface between the protective member and the first grinding wheel.

[0017] Furthermore, in the embedding step, it is preferable that a liquid with a higher temperature than the liquid supplied to the contact interface between the protective member and the second grinding wheel in the flattening step is supplied to the contact interface between the protective member and the first grinding wheel.

[0018] Furthermore, it is preferable that the first grinding wheel includes a grinding wheel with a lower concentration than the grinding wheels included in the second grinding wheel. Moreover, it is preferable that the first grinding wheel includes a grinding wheel with a narrower blade width than the grinding wheels included in the second grinding wheel. Alternatively, it is preferable that the first grinding wheel and the second grinding wheel are the same grinding wheel.

[0019] According to another aspect of the present invention, a method for processing a workpiece is provided, comprising a substrate having an uneven surface shape due to the formation of a plurality of devices on its surface, and protective members attached to each of the plurality of devices that are convex on the surface of the substrate, the method comprising: a holding step of holding the back side of the substrate with a chuck table; and an embedding and flattening step, after the holding step, of bringing a rotating grinding wheel close to the chuck table while rotating the chuck table so that the protective members are pressed and ground so that the protective members are embedded in the boundaries of the plurality of devices that are concave on the surface of the substrate and the surface of the protective members is flattened. [Effects of the Invention]

[0020] In the present invention, by pressing the protection member, the protection member is embedded at the boundaries of a plurality of devices that are recessed on the front surface side of the substrate, and the protection member is ground to flatten the front surface side of the protection member.

[0021] In this case, it becomes possible to eliminate the gap between the substrate and the protection member, or to reduce this gap, and also to eliminate the gap between the chuck table that holds the substrate via the protection member and the protection member, or to reduce this gap. Therefore, by implementing the present invention prior to grinding the back surface side of the substrate, it is possible to prevent the back surface side of the substrate from becoming uneven along with the grinding of the back surface side of the substrate.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1(A) is a perspective view schematically showing an example of a substrate, and FIG. 1(B) is a cross-sectional view schematically showing the substrate shown in FIG. 1(A). [Figure 2] FIG. 2(A) is a cross-sectional view schematically showing a state where a protection member is adhered to the front surface side of a substrate, and FIG. 2(B) is a cross-sectional view schematically showing an example of a workpiece including the substrate and the protection member adhered to the front surface side of the substrate. [Figure 3] FIG. 3 is a perspective view schematically showing an example of a grinding device. [Figure 4] FIG. 4 is a diagram schematically showing a chuck table included in the grinding device and components that can communicate with the chuck table. [Figure 5] FIG. 5 is a partial cross-sectional side view schematically showing a grinding wheel and the like included in the grinding device. [Figure 6] FIG. 6 is a flowchart schematically showing an example of a processing method of a workpiece for grinding the workpiece in the grinding device. [Figure 7] FIG. 7 is a diagram schematically showing the state of the holding step S1 shown in FIG. 6. [Figure 8] FIG. 8 is a diagram schematically showing the state of the embedding step S2 shown in FIG. 6. [Figure 9]Figure 9 is a schematic cross-sectional view showing the workpiece after the burying step S2 shown in Figure 6. [Figure 10] Figure 10 is a schematic diagram showing the planarization step S3 shown in Figure 6. [Figure 11] Figure 11 is a schematic cross-sectional view showing the workpiece after the planarization step S3 shown in Figure 6. [Figure 12] Figure 12 is a schematic diagram showing the inversion step S4 shown in Figure 6. [Figure 13] Figure 13 is a schematic diagram showing the grinding step S5 as shown in Figure 6. [Figure 14] Figure 14 is a schematic cross-sectional view showing the workpiece after grinding step S5, as shown in Figure 6. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described with reference to the attached drawings. Figure 1(A) is a schematic perspective view showing an example of a substrate, and Figure 1(B) is a schematic cross-sectional view showing a cross-section of the substrate shown in Figure 1(A).

[0024] The substrate 11 shown in Figures 1(A) and 1(B) has a disc-shaped wafer 13 made of a semiconductor material such as silicon, which includes a generally parallel surface 13a and a back surface 13b. Notches 13c are formed on the side surface of the wafer 13, which are used to indicate a specific crystal orientation of the semiconductor material constituting the wafer 13.

[0025] Furthermore, multiple devices 15 are formed on the surface 13a (the surface side of the substrate 11) of the wafer 13. These multiple devices 15 are arranged in a matrix. That is, the boundaries between the multiple devices 15 extend in a grid pattern. Each of the multiple linear portions included in these boundaries is also called a division line.

[0026] Furthermore, the surface of the substrate 11 has an uneven shape. Specifically, the areas on the surface of the substrate 11 where multiple devices 15 are formed are convex, and the areas where multiple devices are not formed, that is, the boundaries of the multiple devices 15 extending in a grid pattern, are concave.

[0027] Then, prior to grinding the back surface of the substrate 11, a disc-shaped protective member having a diameter approximately equal to that of the wafer 13 is attached to the front surface of the substrate 11. Figure 2(A) is a schematic partial cross-sectional side view showing how the protective member is attached to the front surface of the substrate 11.

[0028] The protective member 17, which is attached to the surface side of the substrate 11, comprises, for example, a film-like base material and an adhesive layer (glue layer) provided on the substrate 11 side of the base material. Furthermore, this base material is made of, for example, a polyolefin, polyvinyl chloride, or polyethylene terephthalate resin. The adhesive layer is made of, for example, an epoxy-based or acrylic-based adhesive.

[0029] The protective member 17 is then attached to the surface side of the substrate 11 by being pressed, for example, using a pressure roller R, with its adhesive layer side in contact with the substrate 11. As a result, a workpiece is formed comprising the substrate 11 and the protective member 17 attached to the surface side of the substrate 11. Figure 2(B) is a schematic cross-sectional view showing the workpiece formed in this manner.

[0030] In the workpiece 19 shown in Figure 2(B), the protective member 17 is attached to each of the multiple devices 15 that are convex on the surface side of the substrate 11, but not to the boundaries of the multiple devices that are recessed. As a result, a gap G is created between the substrate 11 and the protective member 17.

[0031] Furthermore, in the workpiece 19, the protective member 17 is deformed to sink slightly between the adjacent pair of devices 15. As a result, the surface side of the protective member 17, that is, the side not attached to the substrate 11, has an uneven shape that slightly reflects the uneven shape of the surface side of the substrate 11.

[0032] Figure 3 is a schematic perspective view showing an example of a grinding apparatus for grinding a workpiece 19. Note that the X-axis direction (front-back direction) and Y-axis direction (left-right direction) shown in Figure 3 are mutually orthogonal directions on the horizontal plane, and the Z-axis direction (up-down direction) is a direction perpendicular to the X-axis direction and the Y-axis direction, respectively (vertical direction).

[0033] The grinding apparatus 2 shown in Figure 3 is equipped with a base 4 that supports various components. Cassette tables 6a and 6b are provided on the front end surface of the base 4. Cassettes 8a and 8b, which can accommodate multiple workpieces 19, are placed on the cassette tables 6a and 6b.

[0034] Furthermore, a recess 4a is formed on the upper surface of the base 4, which is located slightly behind the cassette tables 6a and 6b. Inside this recess 4a is a transport mechanism 10 that can unload the workpiece 19 from the cassettes 8a and 8b and load the workpiece 19 into the cassettes 8a and 8b.

[0035] This transport mechanism 10 has, for example, multiple joints and a robot hand, and holds the workpiece 19 on one side of the robot hand. Furthermore, the transport mechanism 10 can also reverse the robot hand that holds the workpiece 19, that is, it can reverse the top and bottom of the workpiece 19.

[0036] Furthermore, a position adjustment mechanism 12 for adjusting the position of the workpiece 19 is provided diagonally behind the recess 4a. This position adjustment mechanism 12 includes a disc-shaped position adjustment table and a plurality of pins arranged around the position adjustment table. The workpiece 19, which has been discharged from the cassettes 8a and 8b by the transport mechanism 10, is then placed on this position adjustment table and its center is aligned to a predetermined position.

[0037] Specifically, when the workpiece 19 is brought into the position adjustment table, multiple pins move towards the position adjustment table along its radial direction. As a result, the multiple pins come into contact with the side surface of the workpiece 19, causing it to move slightly. Consequently, the center of the workpiece 19 is aligned to a predetermined position.

[0038] Furthermore, a transport mechanism 14 is provided to the side of the position adjustment mechanism 12 for holding the workpiece 19 and transporting it backward. This transport mechanism 14 includes, for example, a support shaft extending in the Z-axis direction, an arm whose base end is fixed to the upper end of the support shaft and which extends in a direction perpendicular to the Z-axis direction, and a suction pad fixed to the underside of the tip of the arm.

[0039] Furthermore, the support shaft of the conveying mechanism 14 is connected to a rotating mechanism (not shown), such as a motor. When this rotating mechanism operates, the support shaft rotates with a straight line along the Z-axis as the axis of rotation. In addition, the support shaft of the conveying mechanism 14 is connected to a moving mechanism (not shown), such as an air cylinder. When this moving mechanism operates, the support shaft moves along the Z-axis, that is, the support shaft moves up and down.

[0040] For example, the transport mechanism 14 holds the workpiece 19 and transports it backward in the following order. First, the rotation mechanism rotates the support shaft so that the suction pad is positioned directly above the workpiece 19, whose center has been aligned to a predetermined position by the position adjustment mechanism 12. Next, the movement mechanism lowers the support shaft so that the suction pad comes into contact with the workpiece 19.

[0041] Next, the suction pads suck the upper surface of the workpiece 19 so that the workpiece 19 is held by the suction pads. Then, the moving mechanism raises the support shaft so that the suction pads holding the workpiece 19 are raised. Next, the rotating mechanism rotates the support shaft so that the suction pads holding the workpiece 19 are swiveled. As a result, the workpiece 19 is transported backward.

[0042] A turntable 16 is provided behind the transport mechanism 14. This turntable 16 is connected to a rotating mechanism such as a motor (not shown). When this rotating mechanism operates, the turntable 16 rotates along a straight line that passes through the center of the upper surface of the turntable 16 and is parallel to the Z-axis direction, for example, along the direction of the arrow shown in Figure 3.

[0043] Furthermore, the turntable 16 is provided with three disc-shaped table bases 18 at approximately equal angular intervals along the circumferential direction of the turntable 16. A chuck table 20 for holding the workpiece 19 is mounted on the upper end of each table base 18. Figure 4 is a schematic diagram showing the chuck table 20 and components that can communicate with the chuck table 20.

[0044] The chuck table 20 has a disc-shaped frame 22 made of, for example, ceramics. This frame 22 has a disc-shaped bottom wall 22a and cylindrical side walls 22b that rise from the outer circumference of the bottom wall 22a. That is, a disc-shaped recess is formed on the upper surface of the frame 22, defined by the bottom wall 22a and the side walls 22b. A disc-shaped porous plate 24 made of porous ceramics or the like is fixed in this recess.

[0045] The upper surfaces of the side walls 22b of the frame 22 and the upper surface of the porous plate 24 are configured to have a shape corresponding to the side surface of a cone, and function as holding surfaces for holding the workpiece 19. In addition, a flow path 22c is formed in the bottom wall 22a, which opens at the bottom surface of the recess and penetrates the bottom wall 22a. This flow path 22c is connected to the suction source 28a via valve 26a and to the fluid supply source 28b via valve 26b.

[0046] The suction source 28a includes, for example, an ejector. The fluid supply source 28b includes, for example, a tank for storing high-pressure gas, a filter for removing foreign matter mixed in with the gas supplied from the tank, and a regulator for adjusting the pressure of the gas supplied from the tank.

[0047] Furthermore, the chuck table 20 is connected to a rotating mechanism (not shown). This rotating mechanism includes, for example, a motor and pulleys. When this rotating mechanism operates, the chuck table 20 rotates around a straight line passing through the center of its holding surface as the axis of rotation.

[0048] Furthermore, the chuck table 20 is supported by a tilt adjustment mechanism (not shown) via a table base 18. This tilt adjustment mechanism includes two movable axes and one fixed axis, which are arranged at approximately equal angular intervals along the circumferential direction of the chuck table 20. When at least one of the two movable axes partially raises or lowers the table base 18 and the chuck table 20, the tilt of the rotation axis of the chuck table 20 is adjusted.

[0049] Furthermore, when the turntable 16 is rotated along the direction of the arrow shown in Figure 3 with the chuck table 20 mounted on the table base 18, the chuck table 20 moves together with the table base 18. This allows the table base 18 and the chuck table 20 to be sequentially positioned, for example, at the loading / unloading position adjacent to the transport mechanism 14, the first grinding position diagonally behind the loading / unloading position, and the second grinding position to the side of the first grinding position.

[0050] Then, the workpiece 19, which has been transported to the rear by the transport mechanism 14, is loaded onto the chuck table 20, which is positioned at the loading / unloading location. The loading of the workpiece 19 onto the chuck table 20 is carried out in the following order, for example.

[0051] First, the transfer mechanism connected to the support shaft of the transport mechanism 14 lowers the support shaft so that the workpiece 19, held by the suction pad of the transport mechanism 14, approaches the holding surface of the chuck table 20. Next, the suction from the upper surface of the workpiece 19 by the suction pad is stopped. As a result, the workpiece 19 is separated from the suction pad and transported to the chuck table 20.

[0052] Then, when the workpiece 19 is loaded onto the chuck table 20, the suction source 28a is activated and the valve 26a is opened so that the lower surface of the workpiece 19 is sucked into and held by the chuck table 20. Next, the turntable 16 is rotated to position the chuck table 20, which holds the workpiece 19, at the first grinding position or the second grinding position.

[0053] A columnar support structure 30 is provided behind both the first and second grinding positions. A moving mechanism 32 is provided on the front side of the support structure 30. This moving mechanism 32 includes a pair of guide rails 34 that extend along the Z-axis direction. Furthermore, a moving plate 36 is attached to the pair of guide rails 34 in a slidable manner.

[0054] Furthermore, a nut (not shown) included in the ball screw is fixed to the rear side (back side) of the movable plate 36, and a screw shaft 38 extending along the Z-axis direction is rotatably connected to this nut. In addition, a motor 40 is connected to one end (upper end) of the screw shaft 38. When the motor 40 rotates the screw shaft 38, the movable plate 36 moves along the Z-axis direction together with the nut.

[0055] Furthermore, a fixing device 42 is provided on the front (surface) of the movable plate 36. The fixing device 42 supports the grinding unit 44. This grinding unit 44 has a spindle housing 46 that is fixed to the fixing device 42. In addition, a spindle 48 extending along the Z-axis direction or a direction slightly inclined with respect to the Z-axis direction is rotatably housed in the spindle housing 46.

[0056] Furthermore, the lower end (tip) of the spindle 48 is exposed from the spindle housing 46 and forms a disc-shaped mount 50. The outer edge of the mount 50 is provided with multiple holes (not shown) that penetrate the mount 50 in the thickness direction, and bolts 52 are inserted into each hole.

[0057] Furthermore, a grinding wheel 54 for rough grinding, for example, is attached to the lower surface of the mount 50 of the grinding unit 44 on the first grinding position side using bolts 52. Similarly, a grinding wheel 54 for finish grinding, for example, is attached to the lower surface of the mount 50 of the grinding unit 44 on the second grinding position side using bolts 52.

[0058] Alternatively, a grinding wheel (first grinding wheel) 54 used in the embedding step S2 described later may be mounted on the lower surface of the mount 50 of one of the grinding units 44 on the first grinding position side or the second grinding position side, and a grinding wheel (second grinding wheel) 54 used in the flattening step S3 described later may be mounted on the other side.

[0059] Furthermore, the spindle housing 46 houses a rotating mechanism such as a motor, which is connected to the base end (upper end) of the spindle 48. When this rotating mechanism operates, the grinding wheel 54 rotates together with the spindle 48 with a rotation axis that is a straight line along the Z-axis direction or a direction slightly inclined with respect to the Z-axis direction.

[0060] Figure 5 is a schematic partial cross-sectional side view showing a grinding wheel 54, etc. This grinding wheel 54 includes an annular wheel base 56 made of a metal such as stainless steel or aluminum. Multiple grinding wheels 58 are fixed to the lower surface of the wheel base 56 at intervals of approximately equal angles along its circumferential direction. Each of the multiple grinding wheels 58 contains a binder such as a vitrified or resinoid and abrasive grains such as diamond dispersed in this binder.

[0061] Furthermore, a liquid supply unit 60 is provided near the grinding wheel 54. This liquid supply unit 60 includes, for example, a nozzle 62 located inside the grinding wheel 54 in a plan view, and a pump (not shown) that supplies a liquid such as pure water to the nozzle 62.

[0062] When this pump operates, liquid is supplied from the nozzle 62 to the workpiece 19 held by the chuck table 20 positioned at the first or second grinding position. In addition, the liquid supply unit 60 may supply liquid via a channel formed in the grinding wheel 54 instead of, or in addition to, the nozzle 62.

[0063] Furthermore, when the chuck table 20 holding the workpiece 19 is positioned at the first grinding position or the second grinding position, grinding is performed on the upper surface of the workpiece 19. An example of grinding the upper surface of the workpiece 19 will be described later. Once this grinding is complete, the turntable 16 is further rotated along the direction of the arrow shown in Figure 3 to position the chuck table 20 holding the workpiece 19 at the loading / unloading position.

[0064] A conveying mechanism 64 is provided in front of the loading / unloading position and to the side of the conveying mechanism 14, which holds the workpiece 19 and conveys it forward. This conveying mechanism 64 has, for example, the same structure as the conveying mechanism 14.

[0065] The transport mechanism 64 then transports the ground workpiece 19, which is held on the chuck table 20 positioned at the loading / unloading position, forward. For example, the unloading of the workpiece 19 from the chuck table 20 is performed in the following order.

[0066] First, the operation of the suction source 28a is stopped and the valve 26a is closed so that the workpiece 19 is separated from the chuck table 20, while the fluid supply source 28b is activated and the valve 26b is opened. Next, the moving mechanism connected to the support shaft of the conveying mechanism 64 lowers the support shaft so that the suction pad of the conveying mechanism 64 approaches the workpiece 19 held by the chuck table 20.

[0067] Next, the suction pads suck on the upper surface of the workpiece 19 so that the workpiece 19 is held by the suction pads. Then, the moving mechanism raises the support shaft so that the suction pads holding the workpiece 19 are raised. Next, the rotating mechanism rotates the support shaft so that the suction pads holding the workpiece 19 are swiveled. As a result, the workpiece 19 is transported forward.

[0068] The ground workpiece 19, which has been removed from the chuck table 20, is then transported to a cleaning unit 66 located to the side of the transport mechanism 64. This cleaning unit 66 includes, for example, a spinner table that rotates while holding the lower surface of the workpiece 19, and a cleaning nozzle that sprays cleaning fluid onto the upper surface of the workpiece 19 held by the spinner table.

[0069] The cleaning fluid used in the cleaning unit 66 is, for example, a mixed fluid of water and air. Alternatively, this cleaning fluid may contain only liquid such as water. Once the cleaning of the upper surface of the workpiece 19 in the cleaning unit 66 is complete, the transport mechanism 10 transports the workpiece 19 from the cleaning unit 66 to the cassettes 8a and 8b.

[0070] Figure 6 is a schematic flowchart illustrating an example of a workpiece processing method for processing a workpiece 19 in the grinding apparatus 2. In short, this method is an example of a method in which protective members 17 are embedded in the boundaries of a plurality of recessed devices 15 on the surface side of the substrate 11 included in the workpiece 19, the surface side of the protective members 17 is flattened, and then the back side of the substrate 11 is ground.

[0071] Specifically, in this method, first, the back side of the substrate 11, that is, the side on which the multiple devices 15 are not formed, is held by the chuck table 20 (holding step S1). Figure 7 is a schematic diagram showing the holding step S1.

[0072] In this holding step S1, first, the workpiece 19, which has been discharged from cassettes 8a and 8b, is loaded onto the chuck table 20 using the transport mechanisms 10 and 14, etc., so that the protective member 17 is facing upwards. Then, the suction source 28a is activated and the valve 26a is opened. As a result, the back side of the substrate 11 is held by the chuck table 20.

[0073] After the holding step S1, the protective member 17 is pressed and embedded in the boundaries of the multiple devices 15 that are recessed on the surface side of the substrate 11 (embedding step S2). Figure 8 is a schematic diagram showing the embedding step S2, and Figure 9 is a schematic cross-sectional view showing the workpiece 19 after the embedding step S2.

[0074] In this embedding step S2, first, the grinding wheel 54 to be used in embedding step S2 is attached to the lower surface of the mount 50 of either the first grinding position side or the second grinding position side of the grinding unit 44 using bolts 52. Note that the attachment of this grinding wheel 54 may be performed prior to the holding step S1.

[0075] Furthermore, in the burial step S2, it is preferable to use a grinding wheel 54 that includes a grinding wheel 58 with a small blade width, i.e., a short length along the radial direction of the grinding wheel 54, so that the protective member 17 can be pressed locally. For example, it is preferable that the blade width of the grinding wheel 58 included in the grinding wheel 54 used in the burial step S2 is less than 3.0 mm.

[0076] Furthermore, in the burial step S2, it is preferable to use a grinding wheel 54 that includes a grinding wheel 58 with a low concentration, i.e., a low volume ratio of abrasive grains contained in the grinding wheel 58, so that the protective member 17 is not excessively ground. For example, it is preferable that the concentration of the grinding grains 58 contained in the grinding wheel 54 used in the burial step S2 is less than 100.

[0077] Next, the turntable 16 is rotated so that the workpiece 19 is positioned directly below the grinding wheel 54 used in the embedding step S2, and the chuck table 20 that holds the workpiece 19 is positioned at either the first grinding position or the second grinding position. Then, both the chuck table 20 and the grinding wheel 54 are rotated.

[0078] Next, the grinding wheel 54, which rotates while the chuck table 20 is rotated, is brought closer to the chuck table 20 so that the protective member 17 and the multiple grinding wheels 58 come into contact; that is, the grinding wheel 54 is lowered while both are rotating. Also, just before the protective member 17 and the multiple grinding wheels 58 come into contact, liquid L is supplied from the nozzle 62 to the contact interface between them.

[0079] In the embedding step S2, it is preferable that a high-temperature liquid L is supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 so that the protective member 17 is easily softened. For example, it is preferable that the temperature of the liquid L supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 in the embedding step S2 be 25° or higher.

[0080] Furthermore, in the burying step S2, it is preferable that a small flow rate of liquid L is supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 so that the protective member 17, which has been softened by frictional heat, is not excessively cooled by the liquid L. For example, it is preferable that the flow rate of liquid L supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 in the burying step S2 is less than 2.0 L / min.

[0081] Then, in the embedding step S2, liquid L is supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58, and the protective member 17 is pressed by the multiple grinding wheels 58 (see Figure 8). As a result, the protective member 17 is embedded in the boundary of the multiple devices 15 that are recessed on the surface side of the substrate 11, so as to eliminate or reduce the gap G between the substrate 11 and the protective member 17 (see Figure 9).

[0082] After the embedding step S2, the protective member 17 is ground to flatten its surface (flattening step S3). Figure 10 is a schematic diagram showing the flattening step S3, and Figure 11 is a schematic cross-sectional view showing the workpiece 19 after the flattening step S3.

[0083] In this flattening step S3, first, the rotation of both the chuck table 20 that holds the workpiece 19 and the grinding wheel 54 used in the embedding step S2 is stopped, and the grinding wheel 54 is separated from the protective member 17, that is, the grinding wheel 54 is raised.

[0084] Next, the grinding wheel 54 used in the burial step S2 is replaced with the one used in the flattening step S3. Note that the same grinding wheel 54 may be used in both the burial step S2 and the flattening step S3. In this case, replacement of the grinding wheel 54 becomes unnecessary.

[0085] Furthermore, a grinding wheel 54 to be used in the flattening step S3 may be pre-mounted on the lower surface of the mount 50 of the other grinding unit 44 on the first grinding position side or the second grinding position side. In this case, the turntable 16 may be rotated so that the chuck table 20 holding the workpiece 19 is positioned at the other of the first grinding position or the second grinding position without changing the grinding wheel 54.

[0086] In the flattening step S3, it is preferable to use a grinding wheel 54 that includes a grinding wheel 58 with a larger blade width than the grinding wheel 58 included in the embedding step S2, so that the entire surface of the protective member 17 can be uniformly ground. For example, it is preferable that the blade width of the grinding wheel 58 included in the grinding wheel 54 used in the flattening step S3 is 3.0 mm or more.

[0087] Furthermore, in the flattening step S3, it is preferable to use a grinding wheel 54 that contains grinding wheels 58 with a higher concentration than the grinding wheels 58 used in the embedding step S2, so that the protective member 17 can be ground smoothly. For example, it is preferable that the concentration of the grinding wheels 58 in the grinding wheel 54 used in the flattening step S3 is 100 or more.

[0088] Next, the grinding device 2 is operated in the same manner as in the embedding step S2. That is, with liquid L supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58, the rotating grinding wheel 54 is brought closer to the chuck table 20 while the chuck table 20 is rotated so that the protective member 17 and the multiple grinding wheels 58 come into contact.

[0089] In the planarization step S3, it is preferable that a liquid L at a lower temperature than the liquid L used in the embedding step S2 is supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 so that the protective member 17 is less likely to soften. For example, it is preferable that the temperature of the liquid L supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 in the planarization step S3 is less than 25°.

[0090] Furthermore, in the planarization step S3, it is preferable that a larger flow rate of liquid L than that used in the embedding step S2 is supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 so that the protective member 17, which has been softened by frictional heat, is sufficiently cooled by the liquid L. For example, it is preferable that the flow rate of liquid L supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 in the planarization step S3 is 2.0 L / min or more.

[0091] Then, in the planarization step S3, the protective member 17 is ground by the multiple grinding wheels 58 while the liquid L is supplied to the contact interface between the protective member 17 and the multiple grinding wheels 58 (see Figure 10). As a result, the surface side of the protective member 17 is planarized (see Figure 11).

[0092] After the planarization step S3, the workpiece 19 is inverted so that the substrate 11 is held on the chuck table 20 via the protective member 17 (inversion step S4). Figure 12 is a schematic diagram showing the inversion step S4.

[0093] In this reversal step S4, first, the rotation of both the chuck table 20 that holds the workpiece 19 and the grinding wheel 54 used in the flattening step S3 is stopped, and the grinding wheel 54 is separated from the protective member 17, that is, the grinding wheel 54 is raised.

[0094] Next, the turntable 16 is rotated so that the chuck table 20 holding the workpiece 19 is positioned in the loading / unloading position. Then, the operation of the suction source 28a is stopped and the valve 26a is closed, while the fluid supply source 28b is activated and the valve 26b is opened. This makes it possible to unload the workpiece 19 from the chuck table 20.

[0095] Next, the workpiece 19, which has been removed from the chuck table 20, is transported to the washing unit 66 using the transport mechanism 64 so that the protective member 17 is facing upwards. Then, the upper surface of the workpiece 19 is washed in the washing unit 66. This washes away the grinding debris generated in the flattening step S3, i.e., the debris of the protective member 17, from the upper surface of the workpiece 19.

[0096] Next, using the transport mechanisms 10, 14, etc., the workpiece 19 that was removed from the cleaning unit 66 is brought back onto the chuck table 20 with the protective member 17 facing downwards. Then, the suction source 28a is activated and the valve 26a is opened. As a result, the substrate 11 is held on the chuck table 20 via the protective member 17, that is, the surface side of the protective member 17 is held on the chuck table 20.

[0097] Here, the surface side of the protective member 17 is flattened in the flattening step S3. Therefore, in the inversion step S4, it is possible to eliminate or reduce the gap between the chuck table 20 and the protective member 17.

[0098] After the inversion step S4, the back side of the substrate 11 is ground (grinding step S5). Figure 13 is a schematic diagram showing the grinding step S5, and Figure 14 is a schematic cross-sectional view showing the workpiece 19 after the grinding step S5.

[0099] In this grinding step S5, first, a grinding wheel 54 for rough grinding is attached to the lower surface of the mount 50 of the grinding unit 44 on the first grinding position side using bolts 52, and a grinding wheel 54 for finish grinding is attached to the lower surface of the mount 50 of the grinding unit 44 on the second grinding position side using bolts 52. Note that the attachment of the grinding wheel 54 for rough grinding and the grinding wheel 54 for finish grinding may be performed prior to the reversal step S4.

[0100] Furthermore, the grinding wheel 54 for rough grinding may be the same as the grinding wheel 54 used in either the embedding step S2 or the flattening step S3. Similarly, the grinding wheel 54 for finish grinding may be the same as the grinding wheel 54 used in the other of the embedding step S2 or the flattening step S3. In these cases, replacement of the grinding wheel 54 becomes unnecessary.

[0101] Next, the turntable 16 is rotated so that the chuck table 20 holding the workpiece 19 is positioned at the first grinding position. Then, the grinding device 2 is operated in the same manner as in the embedding step S2 and the flattening step S3.

[0102] In other words, with liquid L supplied to the contact interface between the substrate 11 and the multiple grinding wheels 58, the chuck table 20 is rotated while the grinding wheel 54 for rough grinding, which rotates to bring the substrate 11 and the multiple grinding wheels 58 into contact, is brought close to the chuck table 20. As a result, the back side of the substrate 11 is roughly ground.

[0103] Next, the rotation of both the chuck table 20 that holds the workpiece 19 and the grinding wheel 54 for rough grinding is stopped, and the grinding wheel 54 is moved away from the protective member 17, that is, the grinding wheel 54 is raised.

[0104] Next, the turntable 16 is rotated so that the chuck table 20 holding the workpiece 19 is positioned at the second grinding position. Then, the grinding device 2 is operated in the same manner as in the embedding step S2 and the flattening step S3.

[0105] In other words, with liquid L supplied to the contact interface between the substrate 11 and the multiple grinding wheels 58, the grinding wheel 54 for finish grinding, which rotates while the chuck table 20 is rotated, is brought closer to the chuck table 20 so that it brings the substrate 11 and the multiple grinding wheels 58 into contact. As a result, the back side of the substrate 11 is finish-ground.

[0106] With the above steps, grinding of the back side of the substrate 11 is completed. At this point, there is no gap, or the gap is small, between the chuck table 20 and the protective member 17. Therefore, in grinding step S5, it is possible to prevent the back side of the substrate 11 from becoming uneven due to grinding.

[0107] In the workpiece processing method shown in Figure 6, in the embedding step S2, the protective member 17 is pressed to embed it in the boundaries of the multiple devices 15 that are recessed on the surface side of the substrate 11, and in the flattening step S3, the protective member 17 is ground to flatten the surface side of the protective member 17.

[0108] In this case, it is possible to eliminate or reduce the gap G between the substrate 11 and the protective member 17, and also to eliminate or reduce the gap between the chuck table that holds the substrate 11 via the protective member 17 and the protective member. Therefore, by performing the embedding step S2 and the flattening step S3 prior to the grinding step S5, it is possible to prevent the back surface of the substrate 11 from becoming uneven due to grinding of the back surface of the substrate 11.

[0109] It should be noted that the above description represents only one aspect of the present invention, and the present invention is not limited to the above description. For example, in the present invention, the grinding apparatus in which the holding step S1, the embedding step S2, and the flattening step S3 are performed may be different from the grinding apparatus in which the grinding step S5 is performed. Also, in the present invention, the entity that performs the holding step S1, the embedding step S2, and the flattening step S3 may be different from the entity that performs the grinding step S5.

[0110] Furthermore, in the present invention, the embedding of the protective member 17 into the boundaries of the multiple devices 15 and the flattening of the surface side of the protective member 17 may be performed simultaneously. That is, the present invention may also be a workpiece processing method that, instead of the embedding step S2 and the flattening step S3, includes an embedding and flattening step after the holding step S1, in which the protective member 17 is pressed and ground, and the protective member 17 is embedded into the boundaries of the multiple devices 15 which are recessed on the surface side of the substrate 11, and the surface side of the protective member 17 is flattened, by rotating the chuck table 20 while bringing the rotating grinding wheel 54 closer to the chuck table 20.

[0111] Furthermore, the structures and methods of the embodiments described above can be modified as appropriate without departing from the scope of the present invention. [Explanation of Symbols]

[0112] 2: Grinding equipment 4: Base (4a: Recess) 6a, 6b: Cassette table 8a, 8b: Cassette 10: Conveying mechanism 11: Circuit board 12:Position adjustment mechanism 13: Wafer (13a: Front side, 13b: Back side) 14: Conveying mechanism 15: Device 16: Turntable 17: Protective material 18: Table base 19: Workpiece 20: Chuck Table 22: Frame (22a: bottom wall, 22b: side wall, 22c: flow path) 24: Porous board 26a, 26b: Valve 28a: Suction source 28b: Fluid supply source 30:Support structure 32: Movement mechanism 34: Guide rail 36: Mobile Plate 38: Screw shaft 40: Motor 42: Fixture 44: Grinding Unit 46: Spindle Housing 48: Spindle 50: Mount 52: Bolt 54: Grinding Wheel 56: Wheel base 58: Sharpening stone 60: Liquid supply unit 62: Nozzle 64: Conveying mechanism 66: Washing Unit

Claims

1. A method for processing a workpiece comprising a substrate having an uneven surface shape due to the formation of multiple devices on its surface, and protective members attached to each of the multiple devices that are convex portions on the surface of the substrate, A holding step in which the back side of the substrate is held by a chuck table, Following the holding step, an embedding step is performed, in which the chuck table is rotated while the first grinding wheel is brought close to the chuck table so that the protective member is pressed and embedded in the boundary of the plurality of devices which is a recess on the surface side of the substrate, Following the embedding step, a flattening step is performed in which a second grinding wheel, which rotates while the chuck table is rotated, is brought close to the chuck table so that the protective member is ground and the surface side of the protective member is flattened. A method for processing a workpiece, comprising the following components.

2. The method for processing a workpiece according to claim 1, further comprising a grinding step of grinding the back surface of the substrate after the planarization step.

3. The method for processing a workpiece according to claim 1, wherein in the embedding step, a liquid with a flow rate less than the liquid supplied to the contact interface between the protective member and the second grinding wheel in the flattening step is supplied to the contact interface between the protective member and the first grinding wheel.

4. The method for processing a workpiece according to claim 2, wherein in the embedding step, a liquid with a flow rate less than the liquid supplied to the contact interface between the protective member and the second grinding wheel in the flattening step is supplied to the contact interface between the protective member and the first grinding wheel.

5. The method for processing a workpiece according to claim 1, wherein in the embedding step, a liquid with a higher temperature than the liquid supplied to the contact interface between the protective member and the second grinding wheel in the flattening step is supplied to the contact interface between the protective member and the first grinding wheel.

6. The method for processing a workpiece according to claim 2, wherein in the embedding step, a liquid with a higher temperature than the liquid supplied to the contact interface between the protective member and the second grinding wheel in the flattening step is supplied to the contact interface between the protective member and the first grinding wheel.

7. The method for machining a workpiece according to any one of claims 1 to 6, wherein the first grinding wheel includes a grinding wheel with a lower concentration than the grinding wheel included in the second grinding wheel.

8. The method for machining a workpiece according to any one of claims 1 to 6, wherein the first grinding wheel includes a grinding wheel having a narrower cutting edge width than the grinding wheel included in the second grinding wheel.

9. The method for processing a workpiece according to any one of claims 1 to 6, wherein the first grinding wheel and the second grinding wheel are the same grinding wheel.

10. A method for processing a workpiece comprising a substrate having an uneven surface shape due to the formation of multiple devices on its surface, and protective members attached to each of the multiple devices that are convex portions on the surface of the substrate, A holding step in which the back side of the substrate is held by a chuck table, Following the holding step, the chuck table is rotated while a rotating grinding wheel is brought close to the chuck table so that the protective member is pressed and ground so that it is embedded in the recessed boundary of the plurality of devices on the surface side of the substrate and the surface side of the protective member is flattened, and the protective member is embedded in the recessed boundary of the plurality of devices on the surface side of the substrate, and the surface side of the protective member is flattened, A method for processing a workpiece, comprising the following components.

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