JP5935993B2 - Retainer - Google Patents

Description

  The present invention relates to a holder, and more particularly to a holder for holding an object to be polished when the object to be polished is polished by a single-side polishing machine.

  Conventionally, materials such as flat panel display (FPD) glass substrates, color filters, indium tin oxide (ITO) film-formed substrates (polished objects) require high-precision flatness. The used polishing process is performed. In general, a single-side polishing machine that polishes an object to be polished one side at a time is used for polishing the object to be polished. In this single-side polishing machine, an object to be polished is held on a holding surface plate, and a polishing cloth is attached to the polishing surface plate. At the time of polishing, the polishing object is polished by supplying a circulating polishing liquid containing abrasive particles and rotating both surface plates while applying pressure to the object to be polished.

JP 2009-202314 A Japanese Patent No. 2849533

  In general, in a polishing process using a single-side polishing machine, the holding surface plate is made of a soft cloth or the like in order to suppress scratches or the like of the object to be polished that occurs when the object is in direct contact with a metal holding surface plate. A holding tool having a holding pad is attached. Although it is possible to avoid scratches and the like by attaching the holding pad, when the adhesiveness and static friction between the holding pad and the object to be polished are insufficient, that is, when the object holding ability of the holding pad is insufficient, Since the lateral shift of the object to be polished occurs during the polishing process, it becomes difficult to polish the object to be polished flatly. In order to suppress this lateral displacement, a holder is known in which a template having an opening into which an object can be inserted is formed along the periphery of the holding pad (see, for example, Patent Document 1).

In FIG. 4, the cross section of the holder used conventionally is shown.
As shown in FIG. 4, a conventionally used holder is configured by attaching a ring-shaped frame member 103 along the peripheral edge of the bottom surface of a disk-shaped holding pad 101. The object to be polished W is accommodated in the frame member 103, and the object to be polished W is pressed against the polishing pad 105 to hold the object to be polished W. When polishing the workpiece W, it is necessary to apply a predetermined polishing pressure to the holding pad 101. In order to make the thickness of the workpiece W uniform, the force pressing the workpiece W against the polishing pad 105 is required. Must be vertical and uniform. In order to make the force pressing the workpiece W against the polishing pad 105 vertical and uniform, the force pressing the holding pad 101 against the workpiece needs to be vertical and uniform.

  However, with the conventionally used holder, it has been difficult to make the force pressing the workpiece W against the polishing pad 105 vertical and uniform. Generally, the thickness t1 of the ring-shaped frame member 103 needs to be smaller than the thickness t2 of the workpiece W. However, the workpiece W is accommodated in the frame member 103, and the frame member 103 When the bottom surface and the bottom surface of the workpiece are pressed against the surface of the polishing pad, the thickness of the holding pad 101 becomes non-uniform. In this case, the thickness t3 of the inner portion 101a of the holding pad that is in contact with the workpiece W is thinner than the thickness t4 of the outer portion 101b of the holding pad 101 to which the frame member 103 is attached. Thereby, the level | step difference G and the inclined surface 107 are formed between the outer side part 101b and the inner side part 101a. When the step G and the inclined surface 107 are formed on the holding pad 101, the inclined surface 107 extending between the outer portion 101b and the inner portion 101a of the holding pad 101 comes into contact with the workpiece W and is perpendicular to the vertical direction. An inclined force F1 is applied.

  Further, when the inclined surface 107 is formed on the holding pad 101, the inner side portion 101 a of the holding pad is pulled downward by the outer side portion 101 b of the holding pad 101. When the inner portion 101a of the holding pad is pulled downward, the force that the inner portion 101a of the holding pad applies to the workpiece W increases, and the force that presses the workpiece W against the polishing pad 105 increases. . The force F2 that the inner portion 101a of the holding pad presses the workpiece W against the polishing pad 105 is not uniform over the entire surface of the holding pad 101, and varies depending on the distance from the inclined surface 107 that is the point of action of the downward pulling force. , It becomes stronger at the periphery of the workpiece W and weaker at the center. When the force F1 is applied to the object to be polished from the holding pad in the inclination direction or the non-uniform force F2 is applied, the force for pressing the object W against the polishing pad 105 becomes non-uniform. As a result, it was difficult to make the thickness of the object to be polished uniform.

  Therefore, the present invention has been made to solve the above-mentioned problems, and the thickness of the object to be polished is reduced by making the force applied by the holding pad to the object to be polished substantially vertical and uniform. An object is to provide a holder that can be made uniform.

In order to solve the above-described problems, the present invention provides a holding pad formed of foamable polyurethane and a thickness of the object to be polished that is attached along the peripheral edge of the bottom surface of the holding pad pressed against the object to be polished. thinner than it is, and a frame member of a ring shape, and the said bottom surface of the holding pad, said being an inner circumferential cuts along the formation of frame member, the width of the cuts, a holding pad with a predetermined pressure When the inner part inside the holding pad is cut against the object to be polished and compressed and spread outward in the circumferential direction, the side surface of the deformed inner peripheral part can contact the side of the outer part outside the notch Are dimensioned so that

  According to the present invention configured as described above, a notch can be formed in the holding pad formed of foamable urethane, and by forming this notch, the force applied to the object to be polished by the holding pad can be increased. It can be made almost vertical and uniform. That is, by forming a ring-shaped cut in the holding pad, the holding pad can be substantially divided into an outer portion and an inner portion.

  As described above, in the conventionally used holder, when the object to be polished is accommodated in the frame material of the holder and pressed against the polishing pad, the thickness of the outer side of the holding pad that is in contact with the frame material is reduced. It becomes thicker than the thickness of the inner side of the holding pad in contact with the object to be polished, and an inclined surface is formed on the holding pad. On the other hand, when the holder is pressed against the polishing pad by forming a notch between the outer part of the holding pad and the inner part of the holding pad and separating them, the outer part of the holding pad No inclined surface is formed between the inner side of the holding pad. Thereby, it can prevent that parts other than the inner part of a holding pad contact a to-be-polished object. Further, the outer part of the holding pad and the inner part of the holding pad are separated, so that the outer part of the holding pad can be prevented from being pulled inward in the circumferential direction due to the deformation of the inner part of the holding pad. Thereby, it is possible to prevent the force applied to the object to be polished from the holding pad at the peripheral edge of the object to be polished, and to make the force applied by the holding pad to the object to be polished uniform over the entire inner surface of the holding pad. be able to.

Furthermore , according to the present invention configured as described above, the cut width formed in the holding pad can be reduced. And by reducing the width of the cut, even if the inner part of the notch of the holding pad is compressed by the workpiece and spreads outward in the circumferential direction, it contacts the side surface of the outer part of the holding pad. Spreading can be suppressed. Then, by suppressing the inner side portion of the holding pad from spreading outward in the circumferential direction, the thickness of the inner side portion of the holding pad can be kept substantially uniform over the entire inner side portion of the holding pad.

  For example, in the structure described in Patent Document 2, a groove having a predetermined width is formed between the outer portion of the holding pad and the inner portion of the holding pad. However, if a groove having a predetermined width is formed in the holding pad, the inner portion of the holding pad is compressed and easily deformed in the outer circumferential direction. When the holding pad is deformed in the outer peripheral direction, the amount of deformation near the side surface of the inner side of the holding pad increases, and as a result, the force applied to the object to be polished near the side surface of the inner side of the holding pad is weak. turn into. Therefore, with the structure described in Patent Document 2, the force applied to the object to be polished by the holding pad cannot be made uniform. On the other hand, in the present invention, when the inner part inside the holding pad is cut and expanded in the outer peripheral direction, the side surface of the deformed inner peripheral part becomes the outer part outside the notch. Therefore, the force applied by the holding pad to the object to be polished can be made uniform over the entire inner surface of the holding pad.

  In the structure described in Patent Document 2, the groove between the outer portion of the holding pad and the inner portion of the holding pad has a predetermined width, so that the inner portion of the holding pad is easily deformed during polishing. turn into. As a result, the object to be polished cannot be sufficiently fixed by the holding pad at the time of polishing, and a lateral displacement may occur. However, as in the present invention, the notch between the inner part and the outer part of the holding pad is used. By narrowing, it is possible to suppress deformation of the inner part during polishing. Thereby, the lateral displacement of the object to be polished can be prevented.

  Furthermore, in the structure described in Patent Document 2, since the groove between the outer portion of the holding pad and the inner portion of the holding pad has a predetermined width, the slurry easily stays in the groove. When the slurry stays in the groove, aggregates are easily formed by particles in the slurry, and as a result, scratches are easily formed on the object to be polished by the aggregates. On the other hand, by forming a narrow cut as in the present invention, it is possible to prevent the slurry from staying inside, and thus the object to be polished is damaged by the aggregate formed by the particles in the slurry. Can be prevented.

  As described above, according to the present invention, the force applied by the holding pad to the object to be polished can be made substantially vertical and uniform, whereby the thickness of the object to be polished can be made uniform. .

The perspective view which shows an example of the single-side polisher to which the holder by embodiment of this invention is applied. FIG. 3 is a cross-sectional view of a main part of the polishing head according to the embodiment of the present invention. Sectional drawing which shows the state which is holding the wafer on the polishing pad with the holder by embodiment of this invention. Sectional drawing of the holder used conventionally.

Hereinafter, a holder according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing an example of a single-side polishing machine to which a holder is applied.

  First, as shown in FIG. 1, the single-side polishing machine 1 includes a polishing surface plate 5 having a polishing pad 3 fixed on the upper surface. A shaft 7 is provided at the bottom of the polishing surface plate 5, and the polishing surface plate 5 is configured to be able to rotate around the axis of the shaft 7. A plurality of polishing heads 9 are disposed on the polishing pad 3 at positions eccentric from the axis of the shaft 7. For example, a wafer is held as an object to be polished between the polishing head 9 and the polishing pad 3.

FIG. 2 is a cross-sectional view of the main part of the polishing head.
The polishing head includes a base 11, and a holder 13 according to an embodiment of the present invention is attached to the bottom surface of the base 11. The holder 13 includes a holding pad 15 formed of foamable polyurethane and a frame member 17 attached to the outer periphery of the holding pad 15.

  The holding pad 15 has a disk shape. For example, a polyurethane resin having a modulus of 100% (a value obtained by dividing a load applied to a non-foamed resin sheet double length by a cross-sectional area) is 20 MPa or less. Is formed by wet film formation. Innumerable bubbles 19 are formed inside the holding pad 15, and the cushioning property of the holding pad 15 is improved by the bubbles.

  The frame member 17 is formed of a ring-shaped member having the same outer diameter as that of the holding pad 15, and is fixed to the bottom surface of the holding pad 15 so that the outer periphery thereof coincides with the outer periphery of the holding pad 15. The frame member 17 surrounds the wafer W from the circumferential direction, thereby preventing the wafer W from being detached from between the polishing head 9 and the polishing pad 3. Therefore, the inner diameter of the frame member 17 is slightly larger than the outer diameter of the wafer W. Further, the thickness of the frame member 17 is made thinner than the thickness of the wafer W. Such a frame member 17 is formed by adding a fiber material such as glass fiber to a thermosetting resin such as an epoxy resin or a phenol resin.

  The holding pad 15 further includes a cut 21 formed on the bottom surface thereof. The notch 21 has a ring shape and is formed concentrically with the holding pad 15. The notch 21 is formed at a position along the inner periphery of the frame member 17 when the frame member 17 is fixed to the holding pad 15. The cut 21 is formed by pressing a ring-shaped blade having a predetermined diameter against the holding pad 15. In addition, the notch 21 has a depth that does not reach the top surface of the holding pad 15 from the bottom surface of the holding pad 15. It is preferable that the depth of the notch 21 reaches 50 to 80% of the thickness of the holding pad 15, for example. The width of the notch 21 is preferably about 0.1 to 1.0 mm. However, the width of the notch 21 is as much as possible from the viewpoint of preventing the slurry from entering and uniforming the stress applied to the workpiece. The narrower one is more preferable.

  The holding pad 15 is substantially divided by an incision 21 into an inner part 15 a on the inner peripheral side of the notch 21 and an outer part 15 b on the outer peripheral side of the notch 21. The inner part 15a has a disc shape concentric with the holding pad 15, and the outer part 15b has a ring shape surrounding the inner part 15b. Since the notch 21 does not reach the upper surface of the holding pad 15, the inner portion 15a and the outer portion 15b are connected in the vicinity of the upper surface of the holding pad.

FIG. 3 is a cross-sectional view showing a state where the wafer is held on the polishing pad by the holder.
When the wafer W is accommodated inside the frame member 17 and the holder 13 is pressed against the polishing pad 3, the holding pad 15 is deformed by the wafer W and the frame member 17. Since the frame member 17 is thinner than the wafer W, the inner portion 15a in contact with the wafer W is more compressed than the outer portion 15b in contact with the frame member 17. Even in this case, since the inner portion 15a and the outer portion 15b are at least bottom surfaces separated by the cuts 21, the deformation of the inner portion 15a and the deformation of the outer portion 15b do not affect each other's deformation. . Therefore, the outer portion 15b is not pulled by the deformation of the inner portion 15a, and the inner portion 15a is not pulled by the deformation of the outer portion 15b. Accordingly, it is possible to prevent the outer portion 15b from being pulled inward in the circumferential direction and applied to the wafer W with a force inclined with respect to the vertical direction. Further, it is possible to prevent the vertical force applied to the wafer W from becoming uneven due to the inner portion 15a being pulled outward in the circumferential direction.

  Further, since the holding pad 15 is made of foamed polyurethane, even if a compressive force is applied to the holding pad 15, it is possible to suppress deformation of the outer shape to some extent by the internal bubbles, but depending on the applied pressure, The outer shape of the holding pad 15 may be deformed. Under a certain pressure, the inner part 15a and the outer part 15b are compressed in the vertical direction and expanded in the width direction. Since the inner portion 15a is wide and has a small amount of compression, the amount of expansion in the width direction is slightly smaller than that of the outer portion 15b. On the other hand, the amount of expansion of the outer portion 15b is increased. Therefore, the expansion of the outer portion 15b can be suppressed by sizing the width of the cut 21 so that the width of the cut 21 is sufficiently narrow and the outer portion 15b contacts the inner portion 15a when the outer portion 15b expands. .

  In addition, by reducing the width of the notch 21, the slurry is less likely to stay. Thereby, it can suppress that the aggregate is formed with the particle | grains in a slurry inside the notch 21, and it can prevent that the wafer W is damaged.

13 Holding tool 15 Holding pad 15a Inner part 15b Outer part 17 Frame material 21 Cut

Claims (1)

A holder used when polishing an object to be polished,
A holding pad formed of foamable polyurethane;
A ring-shaped frame member attached along the peripheral edge of the bottom surface pressed against the object to be polished in this holding pad, and thinner than the thickness of the object to be polished,
On the bottom surface of the holding pad, said frame member and the inner circumferential cuts along is formed of the notch width, the holding pad by pressing the workpiece to the holding pad with a predetermined pressure When the inner part inside the cut is compressed and spread outward in the circumferential direction, the side surface of the deformed inner peripheral part is dimensioned so that it can contact the side surface of the outer part outside the cut, Retaining tool.

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