JP2019038046A - Polishing pad - Google Patents

Abstract

To properly supply a polishing liquid to a space between a polishing pad and a processed object.SOLUTION: A discoid polishing pad is attached to a polishing unit of a polishing device including: a holding table 20 which holds a processed object 1 and the polishing unit which polishes the processed object 1 held by the holding table 20. The polishing pad is characterized in including: a polish liquid supply passage 50 penetrating through a center part in a thickness direction; a groove 62 formed on a surface that contacts with the processed object 1 and reaching the polishing liquid supply passage 50; and a plug-like member 64 which has multiple holes 66 penetrating in the thickness direction and is disposed so as to close the polishing liquid supply passage 50.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a polishing pad attached to a polishing apparatus.

  In the manufacturing process of device chips used for electronic devices such as mobile phones and computers, first, a plurality of devices such as IC (Integrated Circuit) and LSI (Large Scale Integration) are formed on the surface of a semiconductor wafer. Next, the wafer is ground from the back side to be thinned to a predetermined thickness, and the wafer is divided for each device to form individual device chips.

  The wafer is ground by a grinding apparatus. The grinding apparatus includes a holding table that holds a wafer and a grinding unit that grinds the wafer, and the grinding unit includes a spindle and a grinding wheel attached to a lower end of the spindle. The grinding wheel includes a grinding wheel that contacts the wafer and grinds the wafer. For grinding the wafer, a grinding apparatus having a rough grinding grinding unit including a grinding wheel having relatively large abrasive grains and a finish grinding grinding unit including a grinding wheel having relatively small abrasive grains is used. There are cases (see Patent Document 1).

  When the back side of the wafer is ground, a minute uneven shape tends to be formed on the surface to be ground. Therefore, it is known that after the grinding, for example, the back surface of the wafer is polished by a CMP (Chemical Mechanical Polishing) method to remove the minute unevenness (see Patent Document 2).

  A polishing apparatus for polishing a workpiece such as a wafer includes a holding table for holding the workpiece and a polishing pad for polishing the workpiece. The diameter of the polishing pad is larger than the diameter of the wafer, and the polishing pad is disposed so as to cover the entire processing surface of the wafer held on the holding table when the wafer is polished. Then, when the polishing pad and the holding table for holding the wafer are rotated around respective rotation axes parallel to each other and the polishing pad is brought into contact with the wafer, the wafer is polished.

  A polishing liquid supply path that penetrates the polishing pad in the thickness direction is formed at the center of the polishing pad. When polishing a wafer, the polishing liquid is supplied to the wafer through the polishing liquid supply path. The polishing liquid is, for example, a chemical liquid (slurry) in which abrasive grains are dispersed. In polishing the workpiece, the polishing liquid not only acts chemically and mechanically to contribute to the polishing, but also contributes to the discharge of polishing waste generated by the polishing. Therefore, it is necessary to appropriately supply the polishing liquid to the entire surface to be processed. For this reason, for example, a groove is formed on the polishing surface of the polishing pad.

JP 2000-288888 A JP-A-8-99265

  For example, when the polishing pad is brought into contact with the workpiece so as to polish a workpiece having a relatively large diameter such as a diameter of 200 mm or a diameter of 300 mm, the lower end of the polishing liquid supply path of the polishing pad is Since it is blocked by the workpiece, the polishing liquid remains in the polishing liquid supply path. At the time of polishing, the polishing pad in which the groove is formed and the workpiece held on the holding table are rotated around respective axes parallel to each other while abutting each other. Then, the polishing liquid is appropriately supplied between the polishing pad and the surface to be processed.

  On the other hand, when polishing a workpiece having a relatively small diameter, particularly a workpiece having a diameter smaller than the radius of the polishing pad, the polishing pad is disposed so as to cover the entire surface of the workpiece. However, the lower end of the polishing liquid supply path may not be blocked by the workpiece. Then, even if the polishing liquid is supplied to the polishing liquid supply path, most of the polishing liquid flows out, so that the polishing liquid is appropriately applied to the processing surface of the workpiece through the groove formed on the polishing surface. Cannot supply. Unless the polishing liquid can be supplied appropriately, the workpiece cannot be properly polished.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a polishing pad capable of appropriately supplying a polishing liquid between the polishing pad and the workpiece.

  According to one aspect of the present invention, a disc-like shape mounted on the polishing unit of a polishing apparatus comprising: a holding table that holds a workpiece; and a polishing unit that polishes the workpiece held on the holding table. A polishing liquid supply path that penetrates the central portion in the thickness direction, a groove that is formed on a surface that contacts the workpiece and reaches the polishing liquid supply path, and a plurality of holes that penetrate the thickness direction. And a plug-like member disposed so as to close the polishing liquid supply path.

  The polishing pad according to one embodiment of the present invention is provided with a polishing liquid supply path that penetrates the polishing pad in the thickness direction, and the polishing liquid is supplied to the polishing liquid supply path when the workpiece is polished. The polishing pad is provided with a plug-like member so as to block the polishing liquid supply path, and the plug-like member has a plurality of holes penetrating in the thickness direction. Therefore, the polishing liquid passes through the plug-like member by passing through the hole.

  The polishing liquid passing through the hole of the plug-like member is dispersed and transmitted to the inner wall surface of the polishing liquid supply path when discharged below the hole. Then, the polishing liquid is supplied to the groove reaching the polishing liquid supply path, and the polishing liquid is supplied to the entire processing surface of the workpiece through the groove.

  Therefore, according to one embodiment of the present invention, a polishing pad is provided that can appropriately supply a polishing liquid between a polishing pad and a workpiece.

It is a perspective view which shows a polish device typically. FIG. 2A is a perspective view schematically showing the polishing pad as seen from the base material layer side, and FIG. 2B is a perspective view schematically showing the polishing pad as seen from the polishing layer side. FIG. 2C is a plan view schematically showing the polishing pad as viewed from the polishing layer side. It is sectional drawing which shows typically the grinding | polishing process using a polishing pad.

  Embodiments according to one aspect of the present invention will be described with reference to the accompanying drawings. The polishing pad according to this embodiment is attached to a polishing apparatus. A workpiece to be polished by the polishing apparatus and a polishing apparatus for polishing the workpiece will be described with reference to FIG. FIG. 1 is a perspective view schematically showing a polishing apparatus 2 for polishing a workpiece 1 such as a semiconductor wafer.

  The workpiece 1 processed in the polishing apparatus 2 is, for example, a substantially disk-shaped material made of silicon, SiC (silicon carbide), or other semiconductor material, or a material such as sapphire, glass, or quartz. It is a substrate. The surface of the workpiece 1 is divided into a plurality of regions by a plurality of division lines (streets) arranged in a lattice pattern, and devices such as ICs are formed in the plurality of regions. Finally, the workpiece 1 is divided along the division lines, whereby individual device chips are formed.

  The workpiece 1 is thinned by grinding the back surface. On the back surface of the ground workpiece 1, there is a tendency that a minute uneven shape is formed. Therefore, after grinding, the back surface of the workpiece 1 is polished to remove the minute irregularities. When the back side of the workpiece 1 is polished, a protective tape 3 may be attached to the surface of the workpiece 1. The protective tape 3 protects the surface side of the workpiece 1 from an impact applied when polishing the back surface of the workpiece 1 or transporting the workpiece 1, and prevents the device from being damaged.

  The protective tape 3 has a flexible film-like base material and a glue layer (adhesive layer) formed on one surface of the base material. For example, PO (polyolefin), PET (polyethylene terephthalate), polyvinyl chloride, polystyrene, or the like is used for the base material. For the glue layer (adhesive layer), for example, silicone rubber, acrylic material, epoxy material or the like is used.

  The polishing apparatus 2 has a base 4 that supports each component. Cassette mounting tables 6 a and 6 b are provided on the upper surface of the front portion of the base 4. On the cassette mounting table 6a, for example, a cassette 8a containing the workpiece 1 before polishing is placed. For example, a cassette 8b for housing the workpiece 1 after polishing is placed on the cassette mounting table 8b. On the base 4, a workpiece transfer robot 10 that transfers the workpiece 1 adjacent to the cassette mounting tables 6a and 6b is installed.

  On the upper surface of the front portion of the base 4, a positioning table 12 that determines the position of the workpiece 1 with a plurality of positioning pins, and a workpiece loading mechanism (loading arm) 14 that places the workpiece 1 on the holding table 20. A workpiece unloading mechanism (unloading arm) 16 for unloading the workpiece 1 from the holding table 20, and a spinner cleaning device 52 for cleaning and spin drying the polished workpiece 1. Yes.

  An opening 4 a is provided on the upper surface of the rear portion of the base 4. In the opening 4a, an X-axis moving table 18 on which a holding table (chucking table) 20 for sucking and holding the workpiece 1 is mounted is provided. The X-axis moving table 18 can be moved in the X-axis direction by an X-axis direction moving mechanism (not shown). The X-axis moving table 8 includes a loading / unloading region 22 where the workpiece 1 is attached to and detached from the holding table 20 by the function of the X-axis direction moving mechanism, and the workpiece 1 sucked and held on the holding table 20. And a processing region 24 to be polished.

  The upper surface of the holding table 20 serves as a holding surface 20 a that holds the workpiece 1. The holding table 20 includes therein a suction path 20b (see FIG. 3) having one end connected to a holding surface 20a of the holding table 20 and the other end connected to a suction source (not shown). When the suction source is operated, a negative pressure acts on the workpiece 1 placed on the holding surface 20 a, and the workpiece 1 is sucked and held on the holding table 20. The holding table 20 can rotate around an axis perpendicular to the holding surface 20a.

  A polishing unit 26 for polishing the workpiece 1 is disposed above the processing region 24. A support portion 28 is erected at the rear end portion of the base 4 of the polishing apparatus 2, and the polishing unit 26 is supported by the support portion 28. A pair of Z-axis guide rails 30 extending in the Z-axis direction are provided on the front surface of the support portion 28, and a Z-axis moving plate 32 is slidably attached to each Z-axis guide rail 30.

  A nut portion (not shown) is provided on the back surface side (rear surface side) of the Z-axis moving plate 32, and a Z-axis ball screw 34 parallel to the Z-axis guide rail 30 is screwed into the nut portion. ing. A Z-axis pulse motor 36 is connected to one end of the Z-axis ball screw 34. When the Z-axis ball screw 34 is rotated by the Z-axis pulse motor 36, the Z-axis moving plate 32 moves in the Z-axis direction along the Z-axis guide rail 30.

  The polishing unit 26 is fixed to the lower part on the front side of the Z-axis moving plate 32. If the Z-axis moving plate 32 is moved in the Z-axis direction, the polishing unit 26 can be moved in the Z-axis direction.

  The polishing unit 26 includes a spindle 40 that is rotated by a motor connected to the base end side, and a polishing pad 44 according to the present embodiment that is fixed to a mount 42 disposed on the distal end side of the spindle 40 by a fixture 46. And comprising. The motor is provided in the spindle housing 38, and when the motor is operated, the polishing pad 44 rotates according to the rotation of the spindle 40.

  A polishing liquid supply path 50 that penetrates the polishing unit 26 in the Z-axis direction is formed inside the polishing unit 26. The upper end side of the polishing liquid supply path 50 is connected to a polishing liquid supply source 48. When the workpiece 1 is polished, the central portion of the polishing pad 44 is passed from the polishing liquid supply source 48 through the polishing liquid supply path 50. The polishing liquid is supplied to the polishing liquid supply path 60 (see FIG. 3) formed in the above.

  When polishing the workpiece 1 held on the holding table 20 positioned in the processing area 24, the polishing pad 44 is covered with the polishing pad 44 so as to cover the entire surface of the workpiece 1 to be polished. Arranged above. Then, the polishing pad 44 and the holding table 20 are rotated around respective axes along the Z-axis direction, and the polishing pad 44 is lowered and brought into contact with the workpiece 1. At this time, in order to supply the polishing liquid between the workpiece 1 and the polishing pad 44, the polishing liquid supply source 48 is operated to send the polishing liquid to the polishing liquid supply path 50.

  For example, when the polishing pad 44 is brought into contact with the workpiece 1 so as to polish the workpiece 1 larger than the radius of the polishing pad 44, the lower end of the polishing liquid supply path 60 of the polishing pad 44 is The polishing liquid remains on the workpiece 1 because it is blocked by the workpiece 1. At the time of polishing, the polishing pad 44 and the workpiece 1 are rotated around an axis along the Z-axis direction while abutting each other, so that the polishing liquid is supplied to the polishing pad 44 and the workpiece. It is appropriately supplied between the workpiece 1 and the work surface.

  On the other hand, when polishing the workpiece 1 having a diameter smaller than the radius of the polishing pad 44, the polishing liquid supply of the polishing pad 44 can be performed even if the polishing pad 44 is brought into contact with the workpiece 1. The path 60 may not be blocked by the workpiece 1. Then, even if the polishing liquid is supplied to the polishing liquid supply path 60, most of the polishing liquid flows out, so that the polishing liquid cannot be appropriately supplied to the processing surface of the workpiece 1. Unless the polishing liquid can be appropriately supplied to the surface to be processed, the workpiece 1 cannot be properly polished.

  Therefore, the polishing pad 44 according to the present embodiment is used in order to supply the polishing liquid appropriately to the processing surface even when the workpiece 1 having a diameter smaller than the radius of the polishing pad 44 is polished. Next, the polishing pad 44 will be described in detail.

  The polishing pad 44 is disk-shaped, and when the polishing pad 44 is mounted on the mount 42 of the polishing unit 26, the base material layer 54 that contacts the mount 42 and the workpiece 1 are polished. And a polishing layer 56 in contact with the workpiece 1. 2A is a perspective view schematically showing the polishing pad 44 viewed from the base material layer 54 side, and FIG. 2B schematically shows the polishing pad 44 viewed from the polishing layer 56 side. FIG. 2C is a perspective view schematically showing the polishing pad 44 as viewed from the polishing layer 56 side.

  As shown in FIG. 2A, screw holes 58 are formed in the base material layer 54. When the polishing pad 44 is fixed to the mount 42, a fixing tool 46 having a thread is tightened in the screw hole 58. Further, as shown in FIG. 2B, a groove 62 is formed on the surface of the polishing layer 56 that contacts the workpiece 1. A polishing liquid supply path 60 that penetrates the polishing pad 44 in the thickness direction is formed at the center of the polishing pad 44, and the groove 62 reaches the polishing liquid supply path 60. The diameter of the polishing liquid supply path 60 is, for example, 20 mm to 30 mm.

  As shown in FIGS. 2A and 2C, a plug-like member 64 is disposed in the polishing liquid supply path 60 so as to close the polishing liquid supply path 60. The plug-like member 64 is formed with a plurality of holes 66 penetrating the plug-like member 64 in the thickness direction. For example, the diameter of the hole 66 is about 4 mm, and the plug-like member 64 is formed at four locations. The plug-like member 64 is produced, for example, by forming a hole 66 in a disc-like resin such as vinyl chloride with a drilling machine or the like.

  The polishing layer 56 is a nonwoven fabric containing abrasive grains, for example. When a fixed abrasive pad using a nonwoven fabric containing the abrasive grains is used for the polishing layer 56, a polishing liquid that does not contain abrasive grains is used when the workpiece 1 is polished. The polishing liquid is, for example, an alkali mixed liquid obtained by adding a water-soluble organic substance such as glycerin or ethylene glycol to an alkaline solution in which sodium hydroxide, potassium hydroxide, or the like is dissolved. Alternatively, pure water may be used.

  The polishing layer 56 may be a non-woven fabric that does not contain abrasive grains. In that case, for example, a slurry in which solid particles are dispersed in a dispersion medium is used as the polishing liquid. For the slurry, the type of dispersion medium, the type of solid particles, the shape and size of the solid particles, and the like are selected according to the planned polishing content, the type of the workpiece 1, and the like.

  Further, the polishing layer 56 has solid phase reaction fine particles that induce a solid phase reaction with the workpiece 1 and gettering layers that have a Mohs hardness higher than that of the workpiece 1 and can form a gettering layer on the workpiece surface. And fine particles. When the gettering layer is formed, entry of an impurity element into a device formed on the workpiece can be suppressed. The polishing pad 44 having the polishing layer 56 is obtained by dispersing the solid-phase reaction particles and the gettering particles in a liquid binder, immersing the liquid binder in a nonwoven fabric, and drying the nonwoven fabric. It is formed by letting.

  Next, the polishing of the workpiece 1 in the polishing apparatus 2 equipped with the polishing pad 44 will be described. FIG. 3 is a cross-sectional view schematically showing a polishing process using the polishing pad 44. As shown in FIG. 3, the polishing pad 44 is used by being mounted on a mount 42 disposed at the lower end of the spindle 40.

  When the polishing pad 44 is attached to the mount 42, the polishing liquid supply path 50 formed in the polishing unit 26 and the polishing liquid supply path 60 formed in the center of the polishing pad 44 are connected. .

  First, the suction source of the holding table 20 is operated to suck and hold the workpiece 1 on the holding surface 20a. Then, the holding table 20 is moved to the processing region 24, and a polishing unit 26 is disposed above the workpiece 1 so as to cover the surface to be polished of the workpiece 1. Then, the holding table 20 and the polishing pad 44 are rotated around their respective axes along the Z-axis direction, and the polishing pad 44 is lowered. Then, when the polishing pad 44 comes into contact with the workpiece 1, polishing of the workpiece 1 is started.

  When polishing the workpiece 1, the polishing liquid supply source 48 of the polishing apparatus 2 is operated to supply the polishing liquid to the polishing liquid supply path 50. The polishing liquid supplied to the polishing liquid supply path 50 temporarily stays above the plug-shaped member 64 by the plug-shaped member 64 and flows out downward from the hole 66. The polishing liquid that has flowed downward from the hole 66 flows downward along the inner wall surface of the polishing liquid supply path 60 of the polishing pad 44, so that the polishing liquid is also supplied to the groove 62 reaching the polishing liquid supply path 60.

  Therefore, the polishing liquid is supplied to the groove 62 even if the polishing liquid supply path 60 of the polishing pad 44 is not blocked by the workpiece 1. Since the polishing liquid that has reached the groove 62 is supplied to the entire surface of the workpiece 1 through the groove 62, the workpiece 1 is appropriately polished.

  When the plug-like member 64 is not disposed on the polishing pad 44, the polishing liquid does not necessarily travel along the inner wall surface of the polishing liquid supply path 60. Therefore, in order to ensure that the polishing liquid reaches the groove 62, a large amount of polishing liquid must be supplied to the polishing liquid supply source. On the other hand, in the polishing pad 44 according to the present embodiment, since the plug-like member 64 is disposed, the polishing liquid can be transmitted to the inner wall surface of the polishing liquid supply path 60, so that a large amount It is not necessary to supply the polishing liquid.

  As described above, according to the polishing pad 44 according to this embodiment, the polishing liquid can be appropriately supplied between the polishing pad 44 and the workpiece 1.

  In addition, this invention is not limited to description of said embodiment, A various change can be implemented. For example, in the above-described embodiment, the polishing pad 44 in which the plug-like member 64 is disposed has been described, but one aspect of the present invention is not limited thereto. For example, the plug-like member 64 fitted into the polishing liquid supply path 60 of the polishing pad 44 having the polishing liquid supply path 60 is also an embodiment of the present invention.

  Further, the plug-like member 64 may not be disposed in the polishing liquid supply path 60, and may be, for example, a disk-like member having the same diameter as the polishing pad. A hole penetrating the disk-shaped member in the thickness direction is provided near the center of the disk-shaped member. Then, when the polishing pad 44 is fixed to the mount 42 at the lower end of the spindle 40, the disc-like member is sandwiched between the polishing pad 44 and the mount 42, so that the polishing liquid supply path 60 is It is blocked by the disk-shaped member, and the polishing liquid flows out downward through the hole.

  In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

DESCRIPTION OF SYMBOLS 1 Workpiece 3 Protection tape 2 Polishing device 4 Base 4a Opening 6a, 6b Cassette mounting base 8a, 8b Cassette 10 Workpiece conveyance robot 12 Positioning table 14 Workpiece loading mechanism (loading arm)
16 Workpiece unloading mechanism (unloading arm)
18 X-axis moving table 20 Holding table 20a Holding surface 20b Suction path 22 Loading / unloading area 24 Processing area 26 Polishing unit 28 Support section 30 Z-axis guide rail 32 Z-axis moving plate 34 Z-axis ball screw 36 Z-axis pulse motor 38 Spindle housing 40 Spindle 42 Mount 44 Polishing pad 46 Fixing tool 48 Polishing liquid supply source 50 Polishing liquid supply path 52 Cleaning unit 54 Base layer 56 Polishing layer 58 Screw hole 60 Grinding liquid supply path 62 Groove 64 Plug-shaped member 66 Hole 68 Polishing liquid

Claims (1)

A disc-shaped polishing pad mounted on the polishing unit of a polishing apparatus comprising: a holding table that holds a workpiece; and a polishing unit that polishes the workpiece held on the holding table,
A polishing liquid supply path that penetrates the central portion in the thickness direction;
A groove that is formed on a surface that contacts the workpiece and reaches the polishing liquid supply path;
A plug-like member having a plurality of holes penetrating in the thickness direction and disposed so as to close the polishing liquid supply path;
A polishing pad comprising: