Polishing pad

Abstract

To provide a polishing pad that can suppress polishing agents from being insufficiently supplied partially.SOLUTION: A polishing pad, which is attached to a polishing device that polishes a work-piece, comprises: a disk-like base including a first surface and a second surface and having a concave part formed on the first surface side, a porous member provided in the concave part of the base, a polishing layer fixed to the second surface side of the base, and a plurality of penetration holes connected to the porous member while penetrating through the polishing layer, in which polishing agents supplied to the porous member are supplied to the plurality of penetration holes.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polishing pad for polishing a workpiece, a mount to which the polishing pad is attached, and a polishing apparatus including the mount.

Background Art

[0002] In the manufacturing process of device chips, a wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets (division planned lines) arranged in a grid pattern is used. By dividing this wafer along the streets, a plurality of device chips each including a device can be obtained. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] In recent years, with the miniaturization of electronic devices, there has been a demand for thinning of device chips. Therefore, a process of thinning the wafer before division may be performed using a grinding apparatus. The grinding apparatus includes a chuck table for holding a workpiece and a grinding unit for grinding the workpiece, and a grinding wheel including a grinding stone is attached to the grinding unit. By holding the wafer on the chuck table, rotating the chuck table and the grinding wheel, and bringing the grinding stone into contact with the wafer, the wafer is ground and thinned (see Patent Document 1).

[0004] When a wafer is ground with a grinding wheel, processing marks such as fine irregularities and scratches remain on the surface of the wafer (the surface to be ground). If a wafer in this state is divided and a device chip is manufactured, processing marks remain on the device chip, reducing the flexural strength (bending strength) of the device chip. Therefore, the wafer is polished using a polishing device after grinding. The polishing device comprises a chuck table for holding the workpiece and a polishing unit for polishing the workpiece, with a disc-shaped polishing pad attached to the polishing unit. The wafer is held in the chuck table, and the wafer is polished by rotating the chuck table and polishing pad while bringing the polishing pad into contact with the wafer (see Patent Document 2). As a result, the surface of the wafer that was ground is flattened, and processing marks remaining on the ground surface are removed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2000-288881 [Patent Document 2] Japanese Patent Application Publication No. 8-99265 [Overview of the project] [Problems that the invention aims to solve]

[0006] When polishing a workpiece, a polishing device is sometimes used in which the polishing pad is positioned so that it overlaps the entire workpiece. In this case, the polishing fluid is supplied to the center of the workpiece through a polishing fluid supply channel formed to penetrate the center of the polishing unit and the polishing pad. The polishing fluid supplied to the workpiece then spreads from the center to the outer edge of the workpiece due to the centrifugal force of the rotating workpiece. As a result, the polishing fluid is supplied to the entire workpiece.

[0007] However, depending on the size of the workpiece and the polishing conditions (rotation speed of the workpiece and polishing pad, supply amount of polishing fluid, etc.), the polishing fluid supplied to the center of the workpiece may not spread to the outer edge, resulting in insufficient polishing fluid at the outer edge. In this case, machining defects are more likely to occur at the outer edge of the workpiece.

[0008] The present invention has been made in view of the above problems, and aims to provide a polishing pad and mount that can suppress partial supply shortages of polishing fluid, as well as a polishing apparatus equipped with the mount. [Means for solving the problem]

[0009] According to one aspect of the present invention, a polishing pad to be attached to a polishing device for polishing a workpiece comprises a disc-shaped base having a first surface and a second surface, with a recess provided on the first surface side, a porous member provided in the recess of the base, a polishing layer fixed to the second surface side of the base, and a portion penetrating the polishing layer. It enters into the second side of the base The porous member comprises a plurality of through holes connected to the porous member, The through-hole closest to the center of the polishing layer is located within 50 mm of the center of the polishing layer, and the through-hole closest to the outer edge of the polishing layer is located within 50 mm of the outer edge of the polishing layer. Polishing liquid supplied to the porous member This is through the voids inside the porous member. Supply to multiple through holes It will be done A polishing pad is provided.

[0011] Preferably, The through-hole closest to the center of the polishing layer is located within 10 mm of the center of the polishing layer. Preferably, the through-hole closest to the outer edge of the polishing layer is located within 10 mm of the outer edge of the polishing layer. [Effects of the Invention]

[0014] A polishing pad and mount according to one aspect of the present invention includes a porous member to which polishing fluid is supplied. This allows the polishing fluid to flow from the center to the outer edge of the polishing pad and mount, making it easier to supply the polishing fluid not only to the center but also to the outer edge of the workpiece. As a result, partial shortages in the supply of polishing fluid are suppressed, and the occurrence of processing defects is prevented. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view showing a polishing device. [Figure 2] Figure 2(A) is a perspective view showing the upper side of the first mount, and Figure 2(B) is a perspective view showing the lower side of the first mount. [Figure 3] Figure 3(A) is a perspective view showing the upper side of the first polishing pad, and Figure 3(B) is a perspective view showing the lower side of the first polishing pad. [Figure 4] This is a partial cross-sectional side view showing a polishing device that polishes a workpiece with a first polishing pad mounted on a first mount. [Figure 5] Figure 5(A) is a perspective view showing the upper side of the second mount, and Figure 5(B) is a perspective view showing the lower side of the second mount. [Figure 6] Figure 6(A) is a perspective view showing the upper side of the second polishing pad, and Figure 6(B) is a perspective view showing the lower side of the second polishing pad. [Figure 7] This is a partial cross-sectional side view showing a polishing device that polishes a workpiece using a second polishing pad mounted on a second mount. [Modes for carrying out the invention]

[0016] Hereinafter, an embodiment of one aspect of the present invention will be described with reference to the attached drawings. First, an example of the configuration of the polishing apparatus according to this embodiment will be described. Figure 1 is a perspective view showing the polishing apparatus 2. In Figure 1, the X-axis direction (first horizontal direction, front-back direction) and the Y-axis direction (second horizontal direction, left-right direction) are perpendicular to each other. Also, the Z-axis direction (vertical direction, height direction, up-down direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0017] The polishing device 2 includes a rectangular parallelepiped base 4 that supports or accommodates each component of the polishing device 2. Cassette mounting areas (cassette mounting stands) 6a and 6b are provided at the front end of the base 4 on which cassettes 8a and 8b are placed. Cassettes 8a and 8b are containers capable of accommodating multiple workpieces 11, and are arranged on the cassette mounting areas 6a and 6b, respectively. Cassette 8a contains the workpieces 11 before polishing, and cassette 8b contains the workpieces 11 after polishing.

[0018] For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as silicon, and includes surfaces 11a and back surfaces 11b that are generally parallel to each other. The workpiece 11 is partitioned into a plurality of rectangular regions by a plurality of streets (lines to be divided) arranged in a grid pattern so as to intersect each other. Further, on the surface 11a side of the plurality of regions partitioned by the streets, devices (not shown) such as IC (Integrated Circuit), LSI (Large Scale Integration), LED (Light Emitting Diode), and MEMS (Micro Electro Mechanical Systems) devices are formed respectively.

[0019] By dividing the workpiece 11 along the streets, a plurality of device chips each having a device are manufactured. Further, by performing grinding on the back surface 11b side of the workpiece 11 before division to thin the workpiece 11, a thinned device chip can be obtained. Furthermore, by performing polishing on the back surface 11b side of the workpiece 11 after grinding using the polishing device 2, the back surface 11b (the surface to be ground) side of the workpiece 11 is flattened, and processing marks such as fine irregularities and scratches remaining on the back surface 11b of the workpiece 11 are removed.

[0020] When polishing the back surface 11b side of the workpiece 11 with the polishing device 2, a protective member 13 is attached to the surface 11a side of the workpiece 11. As the protective member 13, a tape including a film-shaped base material formed in a circular shape and an adhesive layer (paste layer) provided on the base material can be used. For example, the base material is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate, and the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive or the like. Further, the adhesive layer may be an ultraviolet curable resin that is cured by irradiation with ultraviolet rays. The protective member 13 protects the surface 11a side (device side) of the workpiece 11.

[0021] The workpiece 11 is accommodated in the cassette 8a with the protective member 13 attached thereto. Then, the cassette 8a containing a plurality of workpieces 11 is placed on the cassette placement area 6a. Note that there are no restrictions on the type, material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a substrate made of a semiconductor other than silicon (such as GaAs, InP, GaN, SiC, etc.), sapphire, glass (such as quartz glass, borosilicate glass, etc.), ceramics, resin, metal, or the like. Also, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device.

[0022] An opening 4a is provided in a region on the upper surface side of the base 4 that is located between the cassette placement areas 6a and 6b. Inside the opening 4a, a first transfer mechanism 10 for transferring the workpiece 11 is provided. Also, in front of the opening 4a, an operation panel 12 for inputting various information (such as processing conditions) into the polishing device 2 is installed.

[0023] A position adjustment mechanism (alignment mechanism) 14 for adjusting the position of the workpiece 11 is provided diagonally rearward of the first transfer mechanism 10. The workpiece 11 accommodated in the cassette 8a is transferred onto the position adjustment mechanism 14 by the first transfer mechanism 10. Then, the position adjustment mechanism 14 adjusts the position of the workpiece 11 by sandwiching the workpiece 11. Also, a second transfer mechanism (loading arm) 16 for holding and turning the workpiece 11 is provided in the vicinity of the position adjustment mechanism 14.

[0024] A rectangular opening 4b formed such that the longitudinal direction is along the X-axis direction is provided in a region on the upper surface side of the base 4 that is located behind the second transfer mechanism 16. Inside the opening 4b, a chuck table (holding table) 18 for holding the workpiece 11 is provided. The upper surface of the chuck table 18 is a flat surface that is generally parallel to the horizontal plane (XY plane), and constitutes a holding surface 18a for holding the workpiece 11. The holding surface 18a is connected to a suction source (not shown) such as an ejector via a suction path (not shown), a valve (not shown), etc. formed inside the chuck table 18.

[0025] An X-axis movement mechanism 20 is connected to the chuck table 18. For example, the X-axis movement mechanism 20 is a ball screw type movement mechanism and comprises a ball screw (not shown) arranged along the X-axis direction and a pulse motor (not shown) that rotates the ball screw. The X-axis movement mechanism 20 is also equipped with a table cover 22 that surrounds the chuck table 18, and a bellows-shaped dustproof and waterproof cover 24 that can be extended and retracted along the X-axis direction is provided at the front and rear of the table cover 22. The components of the X-axis movement mechanism 20 (ball screw, pulse motor, etc.) are covered by the table cover 22 and the dustproof and waterproof cover 24.

[0026] The workpiece 11, which has been aligned by the position adjustment mechanism 14, is transported by the second transport mechanism 16 onto the holding surface 18a of the chuck table 18 and held by the chuck table 18. The X-axis movement mechanism 20 then moves the chuck table 18 along the X-axis direction together with the table cover 22. The chuck table 18 is also connected to a rotational drive source (not shown), such as a motor, which rotates the chuck table 18 around a rotation axis that is approximately parallel to the Z-axis direction.

[0027] A rectangular parallelepiped support structure 26 is provided at the rear end of the base 4. A Z-axis movement mechanism 28 is provided on the front side of the support structure 26. The Z-axis movement mechanism 28 comprises a pair of guide rails 30 fixed to the front side of the support structure 26 along the Z-axis direction. Flat movable plates 32 are slidably mounted on the pair of guide rails 30.

[0028] A nut portion (not shown) is provided on the rear (back) side of the movable plate 32. A ball screw 34, which is positioned between a pair of guide rails 30 along the Z-axis direction, is screwed into this nut portion. A pulse motor 36 is also connected to the end of the ball screw 34. When the ball screw 34 is rotated by the pulse motor 36, the movable plate 32 moves along the guide rails 30 in the Z-axis direction.

[0029] A support member 38 is provided on the front side (surface side) of the movable plate 32. The support member 38 supports the polishing unit 40 that polishes the workpiece 11 held by the chuck table 18.

[0030] The polishing unit 40 comprises a hollow cylindrical housing 42 supported by a support member 38. A cylindrical spindle 44, positioned along the Z-axis, is rotatably housed in the housing 42. The tip (lower end) of the spindle 44 is exposed to the outside of the housing 42, and a rotational drive source (not shown), such as a motor, is connected to the base (upper end) of the spindle 44.

[0031] A disc-shaped mount 46 is fixed to the tip of the spindle 44. A disc-shaped polishing pad 48 for polishing the workpiece 11 is mounted on the mount 46. For example, the polishing pad 48 is fixed to the underside of the mount 46 by a fastener such as a bolt 50. The polishing pad 48 rotates around a rotation axis that is roughly parallel to the Z-axis direction by power transmitted from the rotation drive source via the spindle 44 and the mount 46.

[0032] When polishing the workpiece 11, first, the chuck table 18 is moved by the X-axis movement mechanism 20 to position the workpiece 11 below the polishing unit 40. Then, while rotating the chuck table 18 and spindle 44, the polishing unit 40 is lowered at a predetermined speed by the Z-axis movement mechanism 28. As a result, the rotating polishing pad 48 comes into contact with the surface of the workpiece 11 to be polished, and the workpiece 11 is polished.

[0033] Inside the polishing unit 40, a polishing fluid supply passage 52 is formed along the Z-axis direction. One end (upper end) of the polishing fluid supply passage 52 is connected to the polishing fluid supply source 56 via a valve 54. The other end (lower end) of the polishing fluid supply passage 52 is connected to the mount 46. When polishing the workpiece 11, the polishing fluid supplied from the polishing fluid supply source 56 flows into the mount 46 via the valve 54 and the polishing fluid supply passage 52, and is supplied to the polishing pad 48 and the workpiece 11.

[0034] A third transport mechanism (unloading arm) 58, which holds and rotates the workpiece 11, is positioned adjacent to the second transport mechanism 16. A cleaning unit 60 for cleaning the workpiece 11 is positioned in front of the third transport mechanism 58. The workpiece 11, which has been polished by the polishing unit 40, is transported from the chuck table 18 to the cleaning unit 60 by the third transport mechanism 58 and cleaned by the cleaning unit 60.

[0035] For example, the cleaning unit 60 includes a spinner table (not shown) that holds and rotates the workpiece 11, and a nozzle (not shown) that supplies a cleaning solution such as pure water. The workpiece 11 is held by the spinner table, and while the spinner table is rotated, the cleaning solution is supplied to the workpiece 11 from the nozzle, thereby cleaning the workpiece 11. This removes processing debris, polishing fluid, etc., adhering to the workpiece 11. After cleaning, the workpiece 11 is transported out of the cleaning unit 60 by the first transport mechanism 10 and stored in the cassette 8b.

[0036] Furthermore, the polishing apparatus 2 includes a control unit (control unit, control device) 62 connected to each component that constitutes the polishing apparatus 2 (first transport mechanism 10, operation panel 12, position adjustment mechanism 14, second transport mechanism 16, chuck table 18, X-axis movement mechanism 20, Z-axis movement mechanism 28, polishing unit 40, valve 54, polishing fluid supply source 56, third transport mechanism 58, cleaning unit 60, etc.). The control unit 62 controls the operation of the polishing apparatus 2 by outputting control signals to each component of the polishing apparatus 2.

[0037] For example, the control unit 62 is composed of a computer and includes a calculation unit that performs calculations necessary for the operation of the polishing device 2, and a storage unit that stores various information (data, programs, etc.) used for the operation of the polishing device 2. The calculation unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memory such as ROM (Read Only Memory) and RAM (Random Access Memory).

[0038] Next, we will describe in detail the mount 46 of the polishing unit 40 and the polishing pad 48 attached to the mount 46. Figure 2(A) is a perspective view showing the top side of the mount 46, and Figure 2(B) is a perspective view showing the bottom side of the mount 46.

[0039] The mount 46 includes a disc-shaped base 70. For example, the base 70 is made of a metal such as SUS (stainless steel) and includes a first surface (upper surface) 70a and a second surface (lower surface) 70b that are generally parallel to each other.

[0040] A cylindrical polishing fluid supply passage (through hole) 70c is provided in the center of the base 70, extending from the first surface 70a to the second surface 70b and penetrating the base 70 in the thickness direction. Additionally, a plurality of cylindrical insertion holes (through holes) 70d are provided on the outer circumference of the base 70, extending from the first surface 70a to the second surface 70b and penetrating the base 70 in the thickness direction. These insertion holes 70d are arranged at approximately equal intervals along the circumferential direction of the base 70. While Figures 2(A) and 2(B) show two insertion holes 70d, there is no limit to the number of insertion holes 70d.

[0041] The first surface 70a of the base 70 is connected to the spindle 44 (see Figure 1). This connects the polishing fluid supply passage 70c to the polishing fluid supply passage 52 (see Figure 1). The mount 46 may be the same component as the spindle 44, or it may be a separate component that is detachable from the spindle 44. A bolt 50 (see Figure 1) is inserted into the insertion hole 70d.

[0042] Figure 3(A) is a perspective view showing the upper side of the polishing pad 48, and Figure 3(B) is a perspective view showing the lower side of the polishing pad 48. The polishing pad 48 comprises a disc-shaped base 72 that is mounted on the mount 46, and a disc-shaped polishing layer 78 fixed to the base 72.

[0043] For example, the base 72 is made of a metal such as aluminum, aluminum alloy, or SUS (stainless steel), or a resin such as PPS (polyphenylene sulfide), and includes a first surface (upper surface) 72a and a second surface (lower surface) 72b that are generally parallel to each other. In addition, a cylindrical recess (groove) 72c is provided in the center of the first surface 72a side of the base 72. The recess 72c is formed from the first surface 72a toward the second surface 72b side and is arranged concentrically with the base 72.

[0044] A disc-shaped porous member 74 is fitted into the recess 72c. The porous member 74 is made of a porous material such as porous ceramics, porous resin, or porous metal, and contains voids that communicate in the thickness direction and radial direction. The porosity of the porous member 74 (the ratio of the volume of voids to the volume of the porous member 74) is, for example, 20% to 80%, preferably 30% to 70%. For example, the porous member 74 is fixed to the bottom surface and side walls of the recess 72c with an adhesive. The depth of the recess 72c and the thickness of the porous member 74 are approximately equal, and the first surface 72a of the base 72 and the surface (top surface) 74a of the porous member 74 are arranged on approximately the same plane.

[0045] Furthermore, an annular sealing member 76 is provided on the first surface 72a side of the base 72. For example, the sealing member 76 is an O-ring made of rubber and is provided on the radially outer side of the recess 72c. The lower end of the sealing member 76 is embedded in the first surface 72a side of the base 72, and the upper end of the sealing member 76 is exposed from the base 72.

[0046] On the first surface 72a side of the outer circumference of the base 72, there are multiple cylindrical screw holes 72d formed from the first surface 72a toward the second surface 72b. The same number of screw holes 72d are provided as the insertion holes 70d of the mount 46 (see Figures 2(A) and 2(B)), and are arranged at roughly equal intervals along the circumferential direction of the base 72. The tip of a bolt 50 (see Figure 1) is inserted into and screwed into the screw holes 72d.

[0047] A disc-shaped polishing layer 78, formed to be approximately the same diameter as the base 72, is fixed to the second surface 72b of the base 72. The polishing layer 78 is made of nonwoven fabric, foamed urethane, etc., and includes a first surface (upper surface) 78a and a second surface (lower surface) 78b that are generally parallel to each other. The polishing layer 78 also contains abrasive grains (fixed abrasive grains) as an abrasive material. As abrasive grains, for example, silica with a particle size of about 0.1 μm to 10 μm is used. However, the particle size, material, etc. of the abrasive grains are appropriately selected according to the material of the object to be polished.

[0048] The polishing layer 78 has multiple cylindrical through-holes 78c that penetrate the polishing layer 78 in the thickness direction, from the first surface 78a to the second surface 78b, extending throughout the entire polishing layer 78. For example, multiple through-holes 78c are arranged along multiple (12 in Figure 3(B)) imaginary lines arranged radially along the radial direction of the polishing layer 78. However, there are no restrictions on the number or arrangement of the through-holes 78c.

[0049] The diameters of the base 72 and the polishing layer 78 are, for example, 300 mm to 500 mm. The through hole 78c closest to the center of the polishing layer 78 is provided, for example, in a region within 50 mm of the center of the polishing layer 78, preferably within 10 mm. The through hole 78c closest to the outer edge of the polishing layer 78 is provided, for example, in a region within 50 mm of the outer edge of the polishing layer 78, preferably within 10 mm.

[0050] Each of the multiple through holes 78c is positioned to overlap with the porous member 74 and is connected to the porous member 74. Specifically, the upper end of the through hole 78c extends into the second surface 72b of the base 72 and reaches the lower surface of the porous member 74 (see Figure 4).

[0051] Figure 4 is a partial cross-sectional side view showing a polishing apparatus 2 that polishes a workpiece 11 with a polishing pad 48 mounted on a mount 46. When grinding the workpiece 11 with the polishing pad 48, the workpiece 11 is first held by the chuck table 18. For example, the workpiece 11 is placed on the chuck table 18 such that the front surface 11a (protective member 13 side) faces the holding surface 18a and the back surface 11b is exposed upwards. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 18a, the workpiece 11 is held by the chuck table 18 through the protective member 13.

[0052] Next, a polishing pad 48 is attached to the mount 46. Specifically, the polishing pad 48 is first positioned so that the second surface 70b of the base 70 and the first surface 72a of the base 72 are in contact. At this time, the angle of the polishing pad 48 is adjusted so that the insertion hole 70d of the base 70 and the threaded hole 72d of the base 72 are connected. Then, a bolt 50 is inserted into the insertion hole 70d and screwed into the threaded hole 72d. This fastens the bolt 50 and fixes the polishing pad 48 to the mount 46.

[0053] The chuck table 18, which holds the workpiece 11, is positioned below the polishing unit 40 by the X-axis movement mechanism 20 (see Figure 1). At this time, the workpiece 11 is positioned so that the entire back surface 11b (the surface to be polished) overlaps with the polishing layer 78 of the polishing pad 48. Then, while rotating the chuck table 18 and spindle 44, the polishing unit 40 is lowered by the Z-axis movement mechanism 28 (see Figure 1). As a result, the second surface 78b of the rotating polishing layer 78 is pressed against the back surface 11b of the workpiece 11, and the back surface 11b of the workpiece 11 is polished.

[0054] During the polishing of the workpiece 11, polishing fluid is supplied from the polishing fluid supply source 56 to the polishing fluid supply passage 52 via the valve 54. The polishing fluid that flows from the polishing fluid supply passage 52 into the polishing fluid supply passage 70c is then supplied to the multiple through holes 78c through the voids inside the porous member 74. As a result, the polishing fluid flows out from the lower ends of the multiple through holes 78c and is supplied to the back surface 11b side of the workpiece 11.

[0055] Furthermore, the second surface 78b side of the polishing layer 78 may be provided with linear grooves (not shown) connecting the lower ends of a plurality of through holes 78c. In this case, the cleaning fluid supplied to the workpiece 11 will flow more easily along the back surface 11b of the workpiece 11, and the polishing fluid will spread more easily over the entire back surface 11b side of the workpiece 11.

[0056] As the polishing fluid, a polishing fluid that does not contain abrasive particles is used. For example, alkaline solutions containing sodium hydroxide, potassium hydroxide, etc., acidic solutions containing permanganate, etc., and pure water can be used as polishing fluids. However, if the polishing layer 78 does not contain abrasive particles (fixed abrasive particles), a chemical solution (slurry) in which abrasive particles (free abrasive particles) are dispersed may be used as the polishing fluid.

[0057] When the back surface 11b of the workpiece 11 is polished with the polishing pad 48, the back surface 11b of the workpiece 11 is flattened, and any remaining machining marks on the back surface 11b of the workpiece 11 are removed. Then, when the polishing unit 40 descends to a predetermined position, the amount of polishing of the workpiece 11 (the difference in thickness of the workpiece 11 before and after polishing) reaches a predetermined value, and the polishing of the workpiece 11 is stopped.

[0058] When the polishing pad 48 is used to polish the workpiece 11, the centrifugal force of the rotating polishing pad 48 acts on the polishing fluid that flows into the porous member 74 from the polishing fluid supply passage 70c, causing the polishing fluid to flow and spread towards the outer edge of the porous member 74 through the voids inside the porous member 74. Then, the polishing fluid flows from the porous member 74 into each of the multiple through holes 78c, and the polishing fluid is supplied to the workpiece 11 from the lower ends of the multiple through holes 78c. As a result, a sufficient amount of polishing fluid is supplied to a wide area from the center to the outer edge of the workpiece 11.

[0059] Although Figure 4 shows an example configuration in which the upper ends of the multiple through holes 78c extend into the second surface 72b of the base 72 and reach the lower surface of the porous member 74, there are no restrictions on the configuration of the porous member 74 and the multiple through holes 78c as long as the porous member 74 and the multiple through holes 78c can be connected. For example, the thickness of the porous member 74 may be approximately equal to the thickness of the base 72, and the lower surface of the porous member 74 may be exposed at the second surface 72b of the base 72. In this case, the through holes 78c are formed only in the polishing layer 78, and the porous member 74 and the through holes 78c are connected at the interface between the base 72 and the polishing layer 78.

[0060] Furthermore, while Figure 4 shows an example configuration in which a porous member 74 is provided on the polishing pad 48, a porous member can also be provided on the mount 46. Modifications of the mount 46 and polishing pad 48 will be described below.

[0061] Figure 5(A) is a perspective view showing the top side of mount 46A, and Figure 5(B) is a perspective view showing the bottom side of mount 46A. Mount 46A is a modified example of mount 46 shown in Figures 2(A) and 2(B).

[0062] Mount 46A comprises a disc-shaped base 80. For example, the base 80 is made of a metal such as SUS (stainless steel) and includes a first surface (upper surface) 80a and a second surface (lower surface) 80b that are generally parallel to each other.

[0063] A cylindrical polishing fluid supply passage (through hole) 80c is provided in the center of the first surface 80a side of the base 80, extending from the first surface 80a towards the second surface 80b and penetrating the base 80 in the thickness direction. The polishing fluid supply passage 80c is formed to extend from the first surface 80a to the porous member 82 described later and is connected to the porous member 82.

[0064] The outer circumference of the base 80 is provided with multiple cylindrical insertion holes (through holes) 80d that penetrate the base 80 in the thickness direction, from the first surface 80a to the second surface 80b. The multiple insertion holes 80d are arranged at approximately equal intervals along the circumferential direction of the base 80. Although Figures 5(A) and 5(B) show two insertion holes 80d, there is no limit to the number of insertion holes 80d.

[0065] A cylindrical recess (groove) 80e is provided in the center of the second surface 80b of the base 80. The recess 80e is formed extending from the second surface 80b toward the first surface 80a and is arranged concentrically with the base 80. A disc-shaped porous member 82 is fitted into the recess 80e. The porous member 82 is made of a porous material such as porous ceramics, porous resin, or porous metal, and contains voids that communicate in the thickness direction and radial direction. The porosity of the porous member 82 (the ratio of the volume of voids to the volume of the porous member 82) is, for example, 20% to 80% or 30% to 70%.

[0066] For example, the porous member 82 is fixed to the bottom surface and side walls of the recess 80e with adhesive. This connects the lower end of the polishing fluid supply passage 80c (see Figure 5(A)) to the porous member 82. The depth of the recess 80e and the thickness of the porous member 82 are approximately equal, and the second surface 80b of the base 80 and the surface (bottom surface) 82a of the porous member 82 are generally on the same plane.

[0067] The first surface 80a of the base 80 is connected to the spindle 44 (see Figure 1). This connects the polishing fluid supply passage 80c to the polishing fluid supply passage 52 (see Figure 1). The mount 46A may be the same component as the spindle 44, or it may be a separate component that is detachable from the spindle 44. A bolt 50 (see Figure 1) is inserted into the insertion hole 80d.

[0068] Figure 6(A) is a perspective view showing the upper side of the polishing pad 48A, and Figure 6(B) is a perspective view showing the lower side of the polishing pad 48A. Note that the polishing pad 48A is a modified version of the polishing pad 48 shown in Figures 3(A) and 3(B). The polishing pad 48A comprises a disc-shaped base 84 that is mounted on the mount 46A, and a disc-shaped polishing layer 88 fixed to the base 84.

[0069] For example, the base 84 is made of a metal such as SUS (stainless steel) and includes a first surface (top surface) 84a and a second surface (bottom surface) 84b that are generally parallel to each other. The base 84 also has multiple cylindrical through holes 84c that penetrate the base 84 in the thickness direction, from the first surface 84a to the second surface 84b, and these holes are provided throughout the base 84. For example, multiple through holes 84c are arranged along multiple (12 in Figure 6(A)) dashed lines arranged radially along the radial direction of the base 84. However, there are no restrictions on the number or arrangement of the through holes 84c.

[0070] The diameter of the base 84 is, for example, 300 mm or more and 500 mm or less. The through hole 84c closest to the center of the base 84 is provided in a region within 50 mm, preferably within 10 mm, of the center of the base 84. The through hole 84c closest to the outer edge of the base 84 is provided in a region within 50 mm, preferably within 10 mm, of the outer edge of the base 84.

[0071] Furthermore, an annular sealing member 86 is provided on the first surface 84a side of the base 84. For example, the sealing member 86 is an O-ring made of rubber and is provided so as to surround a plurality of through holes 84c in a plan view. The lower end of the sealing member 86 is embedded in the first surface 84a of the base 84, and the upper end of the sealing member 86 is exposed from the base 84.

[0072] On the first surface 84a side of the outer circumference of the base 84, there are multiple cylindrical screw holes 84d formed extending from the first surface 84a to the second surface 84b. The same number of screw holes 84d are provided as the insertion holes 80d of the mount 46A (see Figures 5(A) and 5(B)), and are arranged at roughly equal intervals along the circumferential direction of the base 84. The tip of a bolt 50 (see Figure 1) is inserted into and screwed into the screw holes 84d.

[0073] A disc-shaped polishing layer 88, formed to be approximately the same diameter as the base 84, is fixed to the second surface 84b of the base 84. The polishing layer 88 includes a first surface (upper surface) 88a and a second surface (lower surface) 88b, which are approximately parallel to each other. The material of the polishing layer 88, the particle size and material of the abrasive grains (fixed abrasive grains) contained in the polishing layer 88, etc., are the same as those of the polishing layer 78 (see Figures 3(A) and 3(B)).

[0074] The polishing layer 88 has multiple cylindrical through-holes 88c that penetrate the polishing layer 88 in the thickness direction, from the first surface 88a to the second surface 88b, and these holes are provided throughout the entire polishing layer 88. For example, multiple through-holes 88c are arranged along multiple (12 in Figure 6(B)) imaginary lines arranged radially along the radial direction of the polishing layer 88. However, there are no restrictions on the number or arrangement of the through-holes 88c.

[0075] The diameter of the polishing layer 88 is, for example, 300 mm or more and 500 mm or less. The through hole 88c closest to the center of the polishing layer 88 is provided, for example, in a region within 50 mm from the center of the polishing layer 88, preferably within 10 mm. The through hole 88c closest to the outer edge of the polishing layer 88 is provided, for example, in a region within 50 mm from the outer edge of the polishing layer 88, preferably within 10 mm.

[0076] The angle of the polishing layer 88 is adjusted so that the through holes 84c and 88c are connected (see Figure 7). This creates multiple through holes that penetrate the polishing pad 48A in the thickness direction. Furthermore, the through holes 84c and 88c are positioned to overlap with the porous member 74 when the polishing pad 48A is mounted on the mount 46A (see Figure 7).

[0077] Figure 7 is a partial cross-sectional side view showing a polishing apparatus 2 that polishes a workpiece 11 with a polishing pad 48A mounted on a mount 46A. When grinding the workpiece 11 with the polishing pad 48A, the polishing pad 48A is mounted on the mount 46A. Specifically, first, the polishing pad 48A is positioned so that the second surface 80b of the base 80 and the first surface 84a of the base 84 are in contact. At this time, the angle of the polishing pad 48A is adjusted so that the insertion hole 80d of the base 80 and the threaded hole 84d of the base 84 are connected. Then, a bolt 50 is inserted into the insertion hole 80d and screwed into the threaded hole 84d. This fastens the bolt 50 and fixes the polishing pad 48A to the mount 46A.

[0078] As the chuck table 18 and spindle 44 are rotated, the polishing unit 40 is lowered by the Z-axis movement mechanism 28 (see Figure 1). The second surface 88b of the rotating polishing layer 88 is pressed against the back surface 11b of the workpiece 11, and the back surface 11b of the workpiece 11 is polished. During the polishing of the workpiece 11, polishing fluid is supplied from the polishing fluid supply source 56 to the polishing fluid supply passage 52 via the valve 54. The polishing fluid that flows from the polishing fluid supply passage 52 into the polishing fluid supply passage 80c is then supplied to the through holes 84c and 88c through the voids inside the porous member 82. As a result, the polishing fluid flows out from the lower end of the multiple through holes 88c and is supplied to the back surface 11b of the workpiece 11.

[0079] Furthermore, a linear groove (not shown) connecting the lower ends of a plurality of through holes 88c may be provided on the second surface 88b side of the polishing layer 88. In this case, the cleaning fluid supplied to the workpiece 11 will flow more easily along the back surface 11b of the workpiece 11, and the polishing fluid will spread more easily over the entire back surface 11b side of the workpiece 11.

[0080] When the mount 46A described above is used to polish the workpiece 11, the centrifugal force of the rotating mount 46A acts on the polishing fluid that flows into the porous member 82 from the polishing fluid supply passage 80c, causing the polishing fluid to flow and spread towards the outer edge of the porous member 82 through the voids inside the porous member 82. Then, the polishing fluid flows from the porous member 82 into each of the multiple through holes 84c, and is supplied to the workpiece 11 from the lower ends of the multiple through holes 88c. As a result, a sufficient amount of polishing fluid is supplied to a wide area from the center to the outer edge of the workpiece 11.

[0081] Alternatively, a mount 46A (see Figures 5(A) and 5(B)) can be fixed to the spindle 44, and a polishing pad 48 (Figures 3(A) and 3(B)) can be attached to the mount 46A. In this case, the porous member 82 of the mount 46A and the porous member 74 of the polishing pad 48 come into contact, and the voids of the porous member 82 and the voids of the porous member 74 are connected.

[0082] As described above, the polishing pad 48 according to this embodiment is equipped with a porous member 74 to which polishing fluid is supplied (see Figures 3(A) and 4). This makes it possible to flow the polishing fluid from the center of the polishing pad 48 to the outer edge. Similarly, the mount 46A according to this embodiment is equipped with a porous member 82 to which polishing fluid is supplied (see Figures 5(B) and 7). This makes it possible to flow the polishing fluid from the center of the mount 46A to the outer edge. As a result, polishing fluid is more easily supplied not only to the center of the workpiece 11 but also to the outer edge, and partial shortages of polishing fluid are suppressed.

[0083] The structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the objectives of the present invention. [Explanation of Symbols]

[0084] 11 Workpiece 11a surface 11b Back side 13 Protective components 2 Polishing equipment 4 bases 4a,4b opening 6a, 6b Cassette mounting area (cassette mounting platform) 8a, 8b Cassette 10. First conveying mechanism 12. Control Panel 14. Position adjustment mechanism (alignment mechanism) 16. Second transport mechanism (loading arm) 18. Chuck table (holding table) 18a Holding surface 20 X-axis movement mechanism 22 Table Covers 24 Dustproof and splashproof cover 26 Support structure 28 Z-axis movement mechanism 30 Guide Rails 32 Mobile Plates 34 Ball screw 36 Pulse motor 38 Support member 40 polishing units 42 Housing 44 spindles 46, 46A mount 48,48A polishing pads 50 volts 52 Polishing liquid supply path 54 valves 56 Polishing fluid supply source 58. Third transport mechanism (unloading arm) 60 Washing Units 62 Control Unit (Control Unit, Control Device) 70 bases 70a 1st side (top side) 70b 2nd side (bottom side) 70c Polishing liquid supply path (through hole) 70d Insertion hole (through hole) 72 base 72a 1st side (top side) 72b 2nd side (bottom side) 72c recess (groove) 72d threaded hole 74 ポーラスComponents 74a Surface (top) 76 シール parts 78 grinding layers 78a Page 1 (top) 78b Page 2 (bottom) 78c Through Hole 80 abutment 80a Page 1 (top) 80b, Page 2 (bottom) 80c Grinding Fluid Supply Channel (Through Hole) 80d Insertion Hole (Through Hole) 80e concave part (groove) 82 ポーラスComponents 82a Surface (bottom) 84 abutment 84a Page 1 (top) 84b Page 2 (bottom) 84c Through Hole 84d ねじhole 86 シール parts 88 grinding layers 88a Page 1 (top) 88b Page 2 (bottom) 88c Through Hole

Claims

1. A polishing pad that is attached to a polishing device for polishing a workpiece, A disc-shaped base having a first surface and a second surface, with a recess provided on the first surface side, A porous member provided in the recess of the base, The polishing layer fixed to the second surface side of the base, It comprises a plurality of through holes that penetrate the polishing layer, enter the second surface side of the base and are connected to the porous member, The through-hole closest to the center of the polishing layer is located within a region of 50 mm from the center of the polishing layer. The through-hole closest to the outer edge of the polishing layer is provided in a region within 50 mm of the outer edge of the polishing layer. A polishing pad characterized in that the polishing liquid supplied to the porous member is supplied to a plurality of through holes through the voids inside the porous member.

2. The polishing pad according to claim 1, characterized in that the through hole closest to the center of the polishing layer is located within a region of 10 mm from the center of the polishing layer.

3. The polishing pad according to claim 1 or 2, characterized in that the through hole closest to the outer edge of the polishing layer is provided in a region within 10 mm from the outer edge of the polishing layer.

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