Processing method

Abstract

This invention provides a processing method that can suppress the formation of step differences on the grinding surface of an abrasive pad caused by grinding the grinding surface of a workpiece, and maintain the shape of an abrasive pad suitable for flattening the grinding surface even after such grinding. The workpiece is ground by ensuring that points on the outer periphery of the grinding surface at a predetermined coordinate (first coordinate) contained in a coordinate plane parallel to the grinding surface do not contact the grinding surface, while points on the outer periphery of the grinding surface at other coordinates (third coordinate) contact the outer periphery of the grinding surface. In this case, the entire grinding surface of the workpiece can be ground, and the area near the outer periphery of the grinding surface of the abrasive pad can be worn to the same degree as the more inner area. Thus, the formation of step differences on the grinding surface of the abrasive pad caused by grinding the grinding surface of the workpiece is suppressed, and the shape of an abrasive pad suitable for flattening the grinding surface can be maintained even after such grinding.

Description

Technical Field

[0001] This invention relates to a processing method for grinding a workpiece having a circular grinding surface using an abrasive pad with a circular grinding surface. Background Technology

[0002] Chips for electronic devices such as semiconductor devices and optical devices are manufactured using workpieces such as semiconductor wafers formed of silicon (Si) or silicon carbide (SiC) or insulating wafers formed of sapphire (alumina (Al2O3)). Such chips are manufactured, for example, by thinning a workpiece on which a large number of devices are formed on the front side, and then dividing the workpiece according to the regions containing each device.

[0003] One method for thinning the workpiece is grinding the back side of the workpiece. However, when grinding the workpiece, sometimes a layer with disordered crystal structure (fragmented layer) of the material constituting the workpiece is formed on the back side (the ground surface), and / or grinding marks remain, and micro-cracks are formed. Furthermore, when such workpieces are diced to manufacture chips, there is a concern that the bending strength of the resulting chips will be reduced.

[0004] Therefore, in order to remove the broken layer, grinding marks, and / or cracks formed on the ground surface side of the workpiece, the ground surface of the workpiece is sometimes ground after grinding (see, for example, Patent Document 1). This grinding is performed, for example, by rotating both the workpiece and a grinding pad in which abrasive particles are dispersed in a resin such as polyurethane foam or a nonwoven fabric such as felt, so that the grinding surface of the grinding pad comes into contact with the back side (ground surface) of the workpiece.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2003-243345

[0006] The abrasive surface of an abrasive pad wears down due to the grinding of the workpiece's surface. Therefore, when grinding a large number of workpieces with the same surface size using only a portion of the abrasive surface of the abrasive pad, a stepped difference sometimes forms on the abrasive surface. For example, sometimes the area near the outer periphery of the abrasive surface protrudes downwards compared to the inner area.

[0007] When using such abrasive pads to grind the surface of a workpiece, there is a concern that the surface may not be flattened. Specifically, abrasive pads are typically soft, and therefore, the abrasive surface of the pad may sometimes deform during the grinding process.

[0008] For example, during grinding, the load applied to the outer periphery of the workpiece may increase due to the presence of a step difference formed on the grinding surface of the grinding pad. When grinding a workpiece with a grinding surface of the same size as the aforementioned workpieces in this state, there is a concern that the area near the outer periphery of the workpiece may be over-ground and become thinner (resulting in edge collapse). Summary of the Invention

[0009] In view of the above, the object of the present invention is to provide a processing method that can suppress the formation of step differences in the grinding surface of the grinding pad caused by grinding of the grinding surface of the workpiece, and can maintain the shape of the grinding pad suitable for flattening the grinding surface even after such grinding.

[0010] According to the present invention, a processing method is provided for grinding a workpiece having a circular grinding surface using a grinding pad having a circular grinding surface, wherein the processing method comprises the following steps: a holding step, holding the workpiece on a chuck table having a conical holding surface having a central protrusion; an adjustment step, adjusting the angle between the rotation axis of the chuck table and the rotation axis of the grinding pad, such that the line segment obtained by connecting the points on the outer periphery of the holding surface that has the shortest distance from the grinding surface in a direction perpendicular to the grinding surface and the center of the holding surface is parallel to the grinding surface; and a positioning step, positioning the grinding pad and the chuck table in a horizontal direction. The grinding pad is positioned above the chuck table by relative movement, such that in a coordinate plane parallel to the grinding surface, the first coordinate of the point on the outer periphery of the surface to be ground, which overlaps with the line segment, does not overlap with the grinding pad, and the second coordinate of the center of the surface to be ground overlaps with the grinding pad; and the grinding step, in a state where the grinding pad and the chuck table have been rotated, the point on the outer periphery of the surface to be ground, located at the first coordinate, does not contact the grinding surface, and the point on the outer periphery of the surface to be ground, located at a third coordinate on the coordinate plane, which is different from the first coordinate, contacts the outer periphery of the grinding surface, thereby grinding the workpiece.

[0011] In addition, in this invention, the processing method preferably includes a trimming step before the positioning step, in which a recess is formed in the circular central region of the grinding surface, and during the grinding step, a portion of the boundary of the interface between the grinding surface and the surface being ground is arc-shaped along the outer periphery of the recess.

[0012] In this invention, points on the outer periphery of the surface to be ground, located at a predetermined coordinate (first coordinate) contained in a coordinate plane parallel to the grinding surface, are not in contact with the grinding surface, while points on the outer periphery of the surface to be ground, located at other coordinates (third coordinate), are in contact with the outer periphery of the grinding surface to grind the workpiece. In this case, the entire surface to be ground of the workpiece can be ground, and the area near the outer periphery of the grinding surface of the grinding pad can be worn to the same degree as the area further inward.

[0013] Therefore, it is possible to suppress the formation of step differences in the grinding surface of the grinding pad caused by the grinding of the workpiece, and even after such grinding, it is possible to maintain the shape of the grinding pad suitable for flattening the grinding surface. Attached Figure Description

[0014] Figure 1 This is a perspective view schematically showing an example of a processing device.

[0015] Figure 2 It is a perspective view schematically showing an example of a workpiece.

[0016] Figure 3 This is a partial sectional side view schematically showing an example of a chuck worktable.

[0017] Figure 4 This is a flowchart illustrating an example of a processing method for a workpiece.

[0018] Figure 5 (A) is a schematic top view showing the chuck table positioned at the grinding location and the grinding pad adjusted in position. Figure 5 (B) is a schematic representation. Figure 5 A sectional view of the section at line A1B1 shown in (A).

[0019] Figure 6 (A) is a schematic top view illustrating the grinding of a workpiece using an abrasive pad. Figure 6 (B) is a schematic representation. Figure 6 A sectional view of the section at line A2B2 shown in (A).

[0020] Figure 7 It is a flowchart that schematically illustrates a variation of the processing method for the workpiece.

[0021] Figure 8 This is a schematic side view showing the dressing unit positioned at the grinding location and the grinding pad with its position adjusted.

[0022] Figure 9 (A) is a schematic top view showing the grinding of a workpiece using a modified grinding pad. Figure 9 (B) is a schematic representation. Figure 9 A sectional view of the section at line A3B3 shown in (A).

[0023] Label Explanation

[0024] 11: Workpiece (11a: Front, 11b: Back); 13: Pre-defined dividing line; 15: Component; 2: Processing device; 4: Base (4a: Opening); 6: Conveying mechanism; 8a, 8b: Box platform; 10a, 10b: Box; 12: Position adjustment mechanism (12a: Platform, 12b: Pin); 14: Loading mechanism; 16: Turntable; 18: Chuck worktable (18a: Holding surface); 20: Frame; 22: Perforated plate; 24: Spindle; 26: Rotation axis; 28: Bearing; 30: Support plate; 32: Worktable base; 36: Tilting adjustment unit (36a: Fixed support mechanism, 36b, 36c: Movable support mechanism); 38: Support column; 40: Upper support body; 42: Bearing; 44: Support plate; 46: Motor; 48: Dressing unit; 50: Support Components: 52: Dressing section; 54: Support structure; 56: Z-axis moving mechanism; 58: Guide rail; 60: Moving plate; 62: Lead screw shaft; 64: Motor; 66: Fixture; 68: Grinding unit; 70: Spindle housing; 72: Spindle; 74: Mounting seat; 76a, 76b: Grinding wheel; 78: Support structure; 80: X-axis moving mechanism; 82: Guide rail; 84: Moving plate; 86: Lead screw shaft; 88: Motor; 90: Z-axis moving mechanism; 92: Guide rail; 94: Moving plate; 96: Lead screw shaft; 98: Motor; 100: Fixture; 102: Grinding unit; 104: Spindle housing; 106: Spindle; 108: Mounting seat; 110: Grinding pad; 112: Transfer mechanism; 114: Cleaning mechanism; 116: Rotation axis; 118: Recess. Detailed Implementation

[0025] The embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a perspective view schematically illustrating an example of a processing apparatus capable of grinding and polishing a workpiece. Additionally, Figure 1 The X-axis (front-back direction) and Y-axis (left-right direction) shown are perpendicular to each other on the horizontal plane. In addition, the Z-axis (up-down direction) is perpendicular to the X-axis and Y-axis (vertical direction).

[0026] Figure 1 The processing apparatus 2 shown has a base 4 that supports each component. An opening 4a is formed on the front end side of the upper surface of the base 4, and a conveying mechanism 6 for conveying a plate-shaped workpiece is provided in the opening 4a. Figure 2 This is a perspective view schematically showing an example of a workpiece being transported by a conveying mechanism 6.

[0027] Figure 2 The workpiece 11 shown is, for example, a wafer having a circular front side 11a and a back side 11b and formed of a semiconductor material such as silicon (Si). The front side 11a of the workpiece 11 is divided into multiple regions by multiple intersecting predetermined dividing lines 13, and devices such as ICs (Integrated Circuits) are formed in each region.

[0028] Alternatively, a film-like strip with a diameter approximately equal to that of the workpiece 11 can be adhered to the front side 11a of the workpiece 11. This strip, for example, is formed of resin, and when grinding the back side 11b of the workpiece 11, the strip mitigates the impact applied to the front side 11a, thus protecting the device 15.

[0029] Furthermore, there are no restrictions on the material, shape, structure, and size of the workpiece 11. For example, the workpiece 11 can be a substrate formed from other semiconductor materials, ceramics, resins, or metals. Similarly, there are no restrictions on the type, number, shape, structure, size, and arrangement of the devices 15. Alternatively, the devices 15 may not be formed on the workpiece 11.

[0030] Box platforms 8a and 8b are provided in front of the opening 4a. Boxes 10a and 10b capable of holding multiple workpieces 11 are respectively placed on the box platforms 8a and 8b. A position adjustment mechanism 12 for adjusting the position of the workpieces 11 is provided diagonally behind the opening 4a.

[0031] The position adjustment mechanism 12 includes, for example, a platform 12a configured to support the central portion of the workpiece 11; and a plurality of pins 12b configured to move closer to and further away from the platform 12a in a region outer of the platform 12a. For example, when the workpiece 11, which is moved from the box 10a by the conveying mechanism 6, is placed on the platform 12a, the center of the workpiece 11 is aligned with the central portion of the platform 12a by the plurality of pins 12b.

[0032] A loading mechanism 14 is provided near the position adjustment mechanism 12, which is capable of holding and rotating the workpiece 11. The loading mechanism 14 has an adsorption pad capable of adsorbing the upper surface side of the workpiece 11, and transports the workpiece 11, whose position has been adjusted by the position adjustment mechanism 12, to the rear. A disc-shaped turntable 16 is provided behind the loading mechanism 14.

[0033] The rotary table 16 is connected to a rotary drive source (not shown) such as an electric motor and rotates about a straight line parallel to the Z-axis as its axis of rotation. Four chuck tables 18, which support the workpiece 11 during machining, are arranged at approximately equal intervals along the circumference of the rotary table 16 on its upper surface. There is no limitation on the number of chuck tables 18 provided on the rotary table 16.

[0034] The loading mechanism 14 uses an adsorption pad to adsorb the workpiece 11 and loads it into a chuck table 18 located near the loading / unloading position. The turntable 16, for example, directs... Figure 1 Rotate in the direction of the arrows shown to move each chuck table 18 sequentially to the loading / unloading position, the rough grinding position, the fine grinding position, and the grinding position.

[0035] Figure 3 This is a schematic partial cross-sectional side view of the chuck worktable 18, etc. The chuck worktable 18 has a frame 20 made of a metal material such as stainless steel or ceramic. The frame 20 has a disc-shaped bottom wall and an annular side wall extending upward from the outer periphery of the bottom wall. Furthermore, recesses are formed in the frame 20 by the bottom wall and the side wall.

[0036] An attraction path (not shown) is formed on the bottom wall of the frame 20. One end of the attraction path is exposed on the bottom surface of the recess, and the other end of the attraction path is connected to an attraction source (not shown) such as an injector. A perforated plate 22 is fixed in the recess. The lower surface of the perforated plate 22 is generally flat, and the upper surface of the perforated plate 22 is a conical shape with a central convex protrusion.

[0037] Furthermore, when the suction source is activated, a negative pressure is generated in the space near the upper surface of the perforated plate 22. Therefore, the upper surface of the perforated plate 22 functions as the holding surface 18a of the chuck table 18 that holds the workpiece 11. Specifically, when the suction source is activated while the workpiece 11 is being moved onto the upper surface of the perforated plate 22, the workpiece 11 is attracted and held by the chuck table 18.

[0038] The upper part of a cylindrical spindle 24 is connected to the lower part of the chuck table 18. The chuck table 18 can be removed from the spindle 24. The lower part of the spindle 24 is connected to a rotary drive source (not shown) such as an electric motor. When this rotary drive source is activated, the chuck table 18 rotates about a rotation axis 26 passing through the center of the holding surface 18a.

[0039] A ring-shaped bearing 28 is provided below the chuck table 18 to support the chuck table 18 in a rotatable manner. A ring-shaped support plate 30 is fixed below the bearing 28. A ring-shaped table base 32 is provided below the support plate 30. The spindle 24 is located in an opening located in the center of each of the bearing 28, the support plate 30, and the table base 32.

[0040] Three support mechanisms (fixed support mechanism 36a, first movable support mechanism 36b, and second movable support mechanism 36c) are provided at approximately equal intervals along the circumference of the worktable base 32 on the lower surface side of the worktable base 32. In this specification, these three support mechanisms are collectively referred to as tilt adjustment unit 36.

[0041] The worktable base 32 is supported by a fixed support mechanism 36a, a first movable support mechanism 36b, and a second movable support mechanism 36c. The fixed support mechanism 36a has a support column (fixed shaft) of a specified length. The upper part of the support column is connected to an upper support body fixed to the lower surface of the worktable base 32, and the lower part of the support column is fixed to the support base.

[0042] The first movable support mechanism 36b and the second movable support mechanism 36c each have a support column (movable shaft) 38 with external threads formed at its front end. The front end (upper part) of the support column 38 is rotatably connected to an upper support body 40 fixed to the lower surface of the worktable base 32. Specifically, the upper support body 40 is a metal columnar component such as a rod with internal threads, and the external threads of the support column 38 are rotatably connected to the internal threads of the upper support body 40.

[0043] An annular bearing 42 with a predetermined outer diameter is fixed to the outer periphery of the support column 38 of the first movable support mechanism 36b and the second movable support mechanism 36c. A portion of the bearing 42 is supported on a stepped support plate 44. That is, the first movable support mechanism 36b and the second movable support mechanism 36c are supported on the support plate 44.

[0044] A motor 46 is connected to the lower part of the support column 38 to rotate the support column 38. When the motor 46 is activated to rotate the support column 38 in one direction, the upper support body 40 rises. Conversely, when the motor 46 is activated to rotate the support column 38 in another direction, the upper support body 40 falls. In this way, the upper support body 40 of the first movable support mechanism 36b and the second movable support mechanism 36c rises and falls, thereby adjusting the tilt of the worktable base 32 (i.e., the chuck worktable 18).

[0045] Refer again Figure 1The remaining components of the processing apparatus 2 will now be described. A dressing unit 48 for dressing the grinding pad 110 (described later) is arranged between a pair of adjacent chuck worktables 18 along the circumference of the rotary table 16. The dressing unit 48 has a cylindrical support member 50 whose lower end is fixed to the upper surface of the rotary table 16. A dressing part 52 is mounted on the upper end of the support member 50.

[0046] The trimming section 52 may have a structure in which abrasive grains are dispersed in a binding material such as resin, or a structure in which a coating layer containing dispersed abrasive grains is provided on the surface of the upper end of the support member 50. These abrasive grains may be formed from materials such as silicon carbide (SiC), cubic boron nitride (cBN), diamond, or metal oxide microparticles. Furthermore, examples of these metal oxide microparticles include microparticles formed from silicon oxide, cerium oxide, zirconium oxide, or aluminum oxide.

[0047] A columnar support structure 54 is provided behind the rough grinding position and the fine grinding position (behind the rotary table 16). A Z-axis moving mechanism 56 is provided on the front surface of the support structure 54 (the side of the rotary table 16). The Z-axis moving mechanism 56 has a pair of guide rails 58 fixed to the front surface of the support structure 54 and extending along the Z-axis direction.

[0048] A movable plate 60 is connected to the front surface of a pair of guide rails 58 in a manner that allows it to slide along the pair of guide rails 58. Additionally, a lead screw 62 extending along the Z-axis is disposed between the pair of guide rails 58. A motor 64 for rotating the lead screw 62 is connected to its upper end.

[0049] Furthermore, a nut portion (not shown) is provided on the surface of the lead screw shaft 62 where a spiral groove is formed, housing balls that roll on the surface of the rotating lead screw shaft 62, thus forming a ball screw. That is, when the lead screw shaft 62 rotates, the balls circulate within the nut portion, and the nut portion moves along the Z-axis direction.

[0050] Furthermore, the nut is fixed to the rear surface (back side) of the movable plate 60. Therefore, if the lead screw shaft 62 is rotated by the motor 64, the movable plate 60 and the nut move together along the Z-axis. In addition, a fixing device 66 is provided on the front surface (front side) of the movable plate 60.

[0051] The fixture 66 supports the grinding unit 68 for grinding the workpiece 11. The grinding unit 68 has a spindle housing 70 fixed to the fixture 66. A spindle 72 extending along the Z-axis is rotatably housed in the spindle housing 70.

[0052] A rotary drive source (not shown) such as an electric motor is connected to the upper end of the spindle 72, and the spindle 72 rotates by the power of the rotary drive source. In addition, the lower end of the spindle 72 protrudes from the lower surface of the spindle housing 70, and a disc-shaped mounting base 74 is fixed to the lower end.

[0053] A rough grinding wheel 76a is mounted on the lower surface of the mounting base 74 of the grinding unit 68 on the rough grinding position side. The rough grinding wheel 76a has a grinding wheel base formed with approximately the same diameter as the mounting base 74. Furthermore, the grinding wheel base is formed of a metal material such as stainless steel or aluminum.

[0054] In addition, a plurality of grinding wheels containing abrasive grains suitable for coarse grinding are fixed on the lower surface of the grinding wheel base. The lower surface (grinding surface) of each of the plurality of grinding wheels is a surface that is approximately perpendicular to the Z-axis direction, and performs coarse grinding on the workpiece 11 held by the chuck table 18 located in the coarse grinding position.

[0055] Similarly, a grinding wheel 76b for fine grinding is mounted on the lower surface of the mounting base 74 of the grinding unit 68 on the fine grinding position side. This grinding wheel 76b has a grinding wheel base formed to approximately the same diameter as the mounting base 74. Furthermore, this grinding wheel base is formed of a metal material such as stainless steel or aluminum.

[0056] Furthermore, a plurality of grinding wheels containing abrasive grains suitable for fine grinding are fixed on the lower surface of the grinding wheel base. The lower surface (grinding surface) of each of the plurality of grinding wheels is a surface that is approximately perpendicular to the Z-axis direction, and performs fine grinding on the workpiece 11 held by the chuck table 18 positioned in the fine grinding position. In addition, the abrasive grains contained in the grinding wheels for fine grinding are generally smaller in size than the abrasive grains contained in the grinding wheels for rough grinding.

[0057] Additionally, a liquid supply nozzle (not shown) is disposed near the grinding wheels 76a and 76b for supplying a liquid such as pure water (grinding fluid) to the area (machining point) where the workpiece 11 contacts the grinding wheel. Alternatively, instead of this nozzle or based on this nozzle, an opening for supplying liquid may be provided on the grinding wheels 76a and 76b, and the grinding fluid may be supplied to the machining point through this opening.

[0058] A support structure 78 is provided on the side of the grinding area (the side of the turntable 16). An X-axis moving mechanism 80 is provided on the side of the support structure 78 on the turntable 16 side. The X-axis moving mechanism 80 has a pair of guide rails 82 that are fixed to the side of the support structure 78 on the turntable 16 side and extend along the X-axis direction.

[0059] A movable plate 84 is connected to the turntable 16 side of a pair of guide rails 82 in a manner that allows it to slide along the pair of guide rails 82. Additionally, a lead screw 86 extending along the X-axis is disposed between the pair of guide rails 82. A motor 88 for rotating the lead screw 86 is connected to the front end of the lead screw 86.

[0060] Furthermore, a nut portion (not shown) is provided on the surface of the lead screw shaft 86 where a spiral groove is formed, housing balls that roll on the surface of the rotating lead screw shaft 86, thus forming a ball screw. That is, when the lead screw shaft 86 rotates, the balls circulate within the nut portion, and the nut portion moves along the X-axis direction.

[0061] Furthermore, the nut is fixed to the side of the movable plate 84 opposite to the support structure 78 (back side). Therefore, if the lead screw shaft 86 is rotated by the motor 88, the movable plate 84 and the nut move together along the X-axis. In addition, a Z-axis moving mechanism 90 is provided on the side of the movable plate 84 on the turntable 16 side (front side).

[0062] The Z-axis moving mechanism 90 has a pair of guide rails 92 fixed to the front of the moving plate 84 and extending along the Z-axis direction. The moving plate 94 is connected to the turntable 16 side of the pair of guide rails 92 in a manner that allows it to slide along the pair of guide rails 92.

[0063] Additionally, a lead screw shaft 96 extending along the Z-axis is disposed between a pair of guide rails 92. A motor 98 for rotating the lead screw shaft 96 is connected to the upper end of the lead screw shaft 96. Furthermore, a nut portion (not shown) is provided on the surface of the lead screw shaft 96 having helical grooves, housing balls that roll on the surface of the rotating lead screw shaft 96, thus forming a ball screw.

[0064] That is, when the lead screw shaft 96 rotates, the balls circulate within the nut section, and the nut section moves along the Z-axis. Furthermore, this nut section is fixed to the side (back side) of the moving plate 94 opposite to the moving plate 84. Therefore, if the lead screw shaft 96 is rotated using the motor 98, the moving plate 94 and the nut section move together along the Z-axis.

[0065] A fixing device 100 is provided on the face (front) of the turntable 16 side of the movable plate 94. The fixing device 100 supports the grinding unit 102 for grinding the workpiece 11. The grinding unit 102 has a spindle housing 104 fixed to the fixing device 100.

[0066] A spindle 106 extending along the Z-axis is rotatably housed in a spindle housing 104. A rotary drive source (not shown) such as an electric motor is connected to the upper end of the spindle 106, and the spindle 106 rotates by the power of the rotary drive source.

[0067] The lower end of the spindle 106 protrudes from the lower surface of the spindle housing 104, and a disc-shaped mounting base 108 is fixed to the lower end. A disc-shaped grinding pad 110 is mounted on the lower surface of the mounting base 108. The grinding pad 110 has a diameter larger than the workpiece 11 held by the chuck table 18, for example, it is a fixed abrasive grinding pad with abrasive grains dispersed inside.

[0068] Furthermore, the circular lower surface (grinding surface) of the abrasive pad 110 is a surface that is approximately perpendicular to the Z-axis direction, and it is used to dry-grind the workpiece 11 held by the chuck table 18 positioned at the grinding position. This abrasive pad 110 is manufactured, for example, by impregnating a polyurethane solution containing abrasive grains with an average particle size of 20 μm or less into a nonwoven polyester fabric and then drying it.

[0069] The abrasive particles dispersed inside the abrasive pad 110 are formed of materials such as silicon carbide, cBN, diamond, or metal oxide microparticles. Examples of metal oxide microparticles include those formed of silicon oxide, cerium oxide, zirconium oxide, or aluminum oxide. Furthermore, the abrasive pad 110 is flexible and flexes slightly depending on the load applied when abrading the workpiece 11.

[0070] A transfer mechanism 112 is provided on the side of the transfer mechanism 14, which is capable of holding and rotating the workpiece 11 that has been ground by the grinding unit 102. A cleaning mechanism 114 is provided in front of the transfer mechanism 112 and behind the opening 4a, which is configured to clean the workpiece 11 transferred out by the transfer mechanism 112. The workpiece 11 cleaned by the cleaning mechanism 114 is transferred by the transfer mechanism 6, for example, and stored in the box 10b.

[0071] Figure 4 This is a flowchart illustrating an example of a processing method for the workpiece 11 in the processing apparatus 2. In this method, the workpiece 11 is first held on the chuck table 18 (holding step: S1). Specifically, after the loading mechanism 14 moves the workpiece 11, which is positioned at a predetermined position by the position adjustment mechanism 12, into the chuck table 18 positioned at the loading / unloading position, the chuck table 18 attracts and holds the workpiece 11.

[0072] Next, the tilt of the chuck table 18 is adjusted (tilt adjustment step: S2). Specifically, the tilt adjustment unit 36 ​​adjusts the tilt of the chuck table 18 so that the line segment obtained by connecting the highest point on the outer periphery of the retaining surface 18a of the chuck table 18 to the center of the retaining surface 18a is perpendicular to the Z-axis direction. That is, the tilt adjustment unit 36 ​​adjusts the tilt of the chuck table 18 so that this line segment is parallel to the lower surface (grinding surface) of the grinding wheel for rough grinding, the lower surface (grinding surface) of the grinding wheel for fine grinding, and the lower surface (grinding surface) of the grinding pad 110.

[0073] Next, the chuck table 18 is positioned in the rough grinding position (first positioning step: S3). Specifically, the rotary table 16 is moved along... Figure 1 The direction of the arrow shown is rotated so that the trajectory of the grinding wheel 76a used for rough grinding, when rotated from above, overlaps with one end and the other end of the line segment mentioned above.

[0074] Next, the workpiece 11 is subjected to rough grinding (rough grinding step: S4). Specifically, while rotating the chuck table 18 and the grinding wheel 76a for rough grinding, the grinding wheel 76a is lowered in such a way that the lower surface (grinding surface) of the grinding tool contacts the upper surface (e.g., the back surface 11b) of the workpiece 11. In addition, grinding fluid is supplied to the area (machining point) where the workpiece 11 contacts the grinding tool via a liquid supply nozzle or the like.

[0075] Next, the chuck table 18 is positioned in the fine grinding position (second positioning step: S5). Specifically, the rotary table 16 is moved along... Figure 1 The direction of the arrow shown is rotated so that the trajectory of the grinding wheel 76b for fine grinding, when rotated from above, overlaps with one end and the other end of the line segment mentioned above.

[0076] Next, the workpiece 11 is finely ground (fine grinding step: S6). Specifically, while rotating the chuck table 18 and the grinding wheel 76b for fine grinding, the grinding wheel 76b is lowered so that the lower surface of the grinding tool contacts the upper surface (e.g., the back surface 11b) of the workpiece 11. In addition, grinding fluid is supplied to the area (machining point) where the workpiece 11 contacts the grinding tool via a liquid supply nozzle or the like.

[0077] Next, position the chuck table 18 in the grinding position and adjust the position of the grinding pad 110 (third positioning step: S7). Figure 5 (A) is a schematic top view showing the chuck table 18 positioned in the grinding position and the grinding pad 110 adjusted in position. Figure 5 (B) is a schematic representation. Figure 5A sectional view of the section at line A1B1 shown in (A).

[0078] in addition, Figure 5 (A) can also be expressed as a coordinate plane parallel to the grinding surface of the grinding pad 110, i.e., a coordinate plane parallel to the X-axis and Y-axis directions (XY coordinate plane). In this third positioning step (S7), point P1 on the outer periphery of the upper surface (e.g., the back surface 11b) (the grinding surface) of the workpiece 11, which overlaps with the line segment L (corresponding to the line segment mentioned above), is positioned at the first coordinate (X1, Y1), and the center P2 of the grinding surface of the workpiece 11 is positioned at the second coordinate (X2, Y2).

[0079] Furthermore, the first coordinate (X1, Y1) is a point located slightly outside the outer periphery of the polishing pad 110 and not overlapping with the polishing pad 110. The second coordinate (X2, Y2) is a point that overlaps with the polishing pad 110. That is, in the third positioning step (S7), the turntable 16 is positioned such that most of the area, except for a very small portion containing point P1 of the workpiece 11, overlaps with the polishing pad 110. Figure 1 Rotate and adjust the position of the grinding unit 102 along the X-axis in the direction of the arrow shown.

[0080] Next, the workpiece 11 is ground (grinding step: S8). Figure 6 (A) is a schematic top view showing the grinding of the workpiece 11 using the grinding pad 110. Figure 6 (B) is a schematic representation. Figure 6 A cross-sectional view of the section at line A2B2 shown in (A). Additionally, Figure 6 (A) can also be expressed as showing the XY coordinate plane.

[0081] In this grinding step (S8), while the chuck table 18 rotates about the rotation axis 26 and the grinding pad 110 rotates about the rotation axis 116, the grinding pad 110 is lowered in such a way that the lower surface (grinding surface) of the grinding pad 110 contacts the grinding surface of the workpiece 11. At this time, the grinding pad 110 slightly deflects according to the load applied when grinding the workpiece 11.

[0082] In other words, a portion of the workpiece 11 bites into the abrasive pad 110 (see reference). Figure 6 (B)). Therefore, not only the area at the top of the workpiece 11 in the Z-axis direction (and) Figure 5 The area where line segment L (shown in (A) overlaps) is in contact with the abrasive pad 110, and the area (abrasive area) R1 located slightly below this area is also in contact with the abrasive pad 110.

[0083] Furthermore, the grinding area R1 does not include point P1 located at the first coordinate (X1, Y1), but includes points P3a and P3b on the outer periphery of the grinding surface of the workpiece 11 located at the third coordinates (X3a, Y3a) and (X3b, Y3b) on the XY coordinate plane, which are different from the first coordinate.

[0084] Furthermore, the grinding area R1 varies depending on the relative position of the chuck table 18 and the grinding pad 110, which has been adjusted in the third positioning step (S7). Therefore, in the third positioning step (S7), the relative position of the chuck table 18 and the grinding pad 110 is adjusted such that point P1 is not included in the grinding area R1, but points P3a and P3b are included.

[0085] exist Figure 4 In the method shown, the workpiece 11 is ground such that points on the outer periphery of the surface to be ground, located at the first coordinate (X1, Y1) contained in the XY coordinate plane, do not contact the grinding surface of the grinding pad 110, while points on the outer periphery of the surface to be ground, located at the third coordinates (X3a, Y3a) and (X3b, Y3b), contact the outer periphery of the grinding surface. In this case, the entire surface to be ground of the workpiece 11 can be ground, and the area near the outer periphery of the grinding surface of the grinding pad 110 can be worn to the same degree as the area further inward.

[0086] Therefore, it is possible to suppress the formation of step differences on the grinding surface of the grinding pad 110 caused by the grinding of the grinding surface of the workpiece 11, and even after such grinding, it is possible to maintain the shape of the grinding pad 110 suitable for flattening the grinding surface.

[0087] Additionally, in this method, when grinding the surface of the workpiece 11, sometimes a portion (unused area) R2 near the center of the grinding surface of the grinding pad 110 (refer to) Figure 6 (A)) does not contact the ground surface of the workpiece 11. Furthermore, in this case, there is concern that due to the grinding of the ground surface of the workpiece 11, the unused area R2 will protrude downwards compared to the outermost area (forming a step difference).

[0088] When the workpiece 11 is polished using a polishing pad 110 that protrudes from the unused area R2, there is concern that the polished surface of the workpiece 11 may be difficult to flatten. Specifically, in this case, there is concern that annular recesses concentric with the polished surface of the workpiece 11 may be formed on the polished surface.

[0089] Therefore, in this invention, it is preferable to form a recess in the circular region (central region) containing the unused region R2 before the third positioning step (S7). Figure 7This is a flowchart illustrating an example of such a processing method. In this method, a holding step (S1) and a tilt adjustment step (S2) are performed first.

[0090] Next, the trimming unit 48 is positioned in the grinding position and the position of the grinding pad 110 is adjusted (positioning step 4: S9). Figure 8 This is a schematic side view showing the dressing unit 48 positioned at the grinding location and the grinding pad 110 with its position adjusted.

[0091] Specifically, make the turntable 16 along Figure 1 Rotate and adjust the position of the grinding unit 102 along the X-axis in the direction of the arrow shown, so that, when viewed from above, the dressing unit 48 is aligned with the central area of ​​the grinding surface of the grinding pad 110. Figure 6 (A) shows the overlapping area containing the unused region R2.

[0092] Next, the polishing pad 110 is trimmed (trimming step: S10). Specifically, while rotating the polishing pad 110, it is lowered so that the lower surface (polishing surface) of the polishing pad 110 contacts the upper surface of the trimming part 52 of the trimming unit 48. As a result, a recess is formed on the polishing surface of the polishing pad 110. In addition, if necessary, in order to form a recess in the central region of the polishing surface of the polishing pad 110, the polishing unit 102 can be moved along the X-axis while the polishing pad 110 is rotating.

[0093] Next, the third positioning step (S7) and the grinding step (S8) are performed. Figure 9 (A) is a schematic top view showing the workpiece 11 being ground using a modified abrasive pad 110. Figure 9 (B) is a schematic representation. Figure 9 A sectional view of the section at line A3B3 shown in (A). Additionally, Figure 9 (A) can also be expressed as showing the XY coordinate plane.

[0094] exist Figure 9 (A) and Figure 9 On the grinding surface of the grinding pad 110 shown in (B), a recess 118 is formed in such a way that it defines a portion of the boundary of the interface (referred to as the grinding area R1) in contact with the grinding surface of the workpiece 11. In other words, a portion of the boundary of the interface is arc-shaped along the outer periphery of the recess 118.

[0095] When such a recess 118 is formed on the grinding surface of the grinding pad 110, after the grinding step (S8), the central region of the grinding pad 110 will not protrude downwards compared to the outer regions (forming a step difference). Therefore, in this case, an annular recess concentric with the grinding surface of the workpiece 11 will not be formed on the workpiece 11, and the entire grinding surface of the workpiece 11 can be ground.

[0096] Furthermore, the above method is one aspect of the present invention, and the present invention is not limited to the above method. For example, the present invention can also be derived from... Figure 4 The machining method shown omits the steps for rough grinding and / or fine grinding of the workpiece 11 (first positioning step (S3) to fine grinding step (S6)).

[0097] Furthermore, in this invention, the movement directions of the chuck table 18 and the grinding unit 102 are not limited. For example, the chuck table 18 can move along the Z-axis direction, and the grinding unit 102 can move along the Y-axis direction. Additionally, the chuck table 18 may not be mounted on the upper surface of the turntable 16 but may be connected to an X-axis movement mechanism and / or a Y-axis movement mechanism composed of a ball screw or the like.

[0098] Furthermore, in this invention, a tilt adjustment unit can be provided to adjust the tilt of the grinding unit 102. Also, in the tilt adjustment step (S2) of this invention, the tilt of the grinding unit 102 can be adjusted without adjusting the tilt of the chuck table 18.

[0099] That is, in this invention, as long as the angle between the rotation axis 26 of the chuck table 18 and the rotation axis 116 of the grinding pad 110 can be adjusted so that the line segment obtained by connecting the point on the outer periphery of the holding surface 18a of the chuck table 18, which is perpendicular to the grinding surface of the grinding pad 110, and the point with the shortest distance from the grinding surface, is parallel to the center of the holding surface 18a, is also parallel to the grinding surface.

[0100] In addition, the structure and method of the above embodiments can be appropriately modified and implemented as long as they do not depart from the scope of the present invention.

Claims

1. A processing method comprising grinding a workpiece having a circular grinding surface using an abrasive pad with a circular grinding surface, characterized in that, The processing method has the following steps: The holding step involves holding the workpiece on a chuck table with a conical holding surface having a central protrusion; The adjustment steps involve adjusting the angle between the rotation axis of the chuck table and the rotation axis of the grinding pad, so that the line segment obtained by connecting the points on the outer periphery of the holding surface that is the shortest distance from the grinding surface in the direction perpendicular to the grinding surface and the center of the holding surface is parallel to the grinding surface. The positioning step involves moving the grinding pad relative to the chuck table in the horizontal direction to position the grinding pad above the chuck table, so that in a coordinate plane parallel to the grinding surface, the first coordinate of the point on the outer periphery of the surface being ground that overlaps with the line segment does not overlap with the grinding pad, and the second coordinate of the center of the surface being ground overlaps with the grinding pad. as well as In the grinding step, while the grinding pad and the chuck table are rotated, a point on the outer periphery of the surface to be ground located at the first coordinate is not in contact with the grinding surface, and a point on the outer periphery of the surface to be ground located at a third coordinate on the coordinate plane that is different from the first coordinate is in contact with the outer periphery of the grinding surface, thereby grinding the workpiece.

2. The processing method according to claim 1, characterized in that, The processing method also includes a trimming step that trims the grinding pad prior to the positioning step. In this finishing step, a concave portion is formed in the circular central region of the grinding surface. During this grinding step, a portion of the boundary of the interface between the grinding surface and the surface being ground is arc-shaped along the outer periphery of the recess.

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