JPWO2018181347A1 - Polishing pad - Google Patents

Abstract

An object of the present invention is to provide a polishing pad excellent in polishing performance and polishing slurry discharge characteristics. A polishing pad having a polishing portion and a groove portion on a polishing surface, wherein the surface of the groove portion has an unfoamed portion, and the surface of the polishing portion has a foamed portion exposed.

Description

  The present invention relates to a polishing pad excellent in polishing performance and polishing slurry discharge characteristics.

  2. Description of the Related Art Conventionally, in a polishing process of a thin plate member such as a magnetic disk or a semiconductor wafer in a hard disk drive (HDD), processing that does not cause minute scratches or latent scratches on the surface of an object to be processed is required. Smooth mirror finishing is performed using a nonwoven fabric or foam polishing pad while supplying the contained polishing slurry.

  The polishing pad is required to have not only a polishing property but also a discharge property of a polishing slurry for smooth mirror polishing. Therefore, in order to improve the balance between the supply and discharge (discharge characteristics) of the polishing slurry, the polishing layer has a groove on the polishing surface, and the average roughness (Ra) of the inner surface of the groove is 1.0 to 5.0. A polishing pad having a thickness of 0 μm has been proposed (Patent Document 1).

  However, in the polishing pad of Patent Literature 1, a groove is formed in the porous material by cutting or the like, and the inner surface of the groove is made nonporous by post-processing such as laser melting, so that the processing is complicated. In addition, the state (particularly roughness) of the polishing surface of the polishing layer is not specified, and there is a problem that the polishing property and the discharge property of the polishing slurry may not be compatible with each other. There was a problem that it could not be obtained.

JP 2006-186239 A

  In view of the above circumstances, an object of the present invention is to provide a polishing pad excellent in polishing performance and polishing slurry discharge characteristics.

  An aspect of the present invention is a polishing pad having a polishing portion and a groove portion on a polishing surface, wherein the surface of the groove portion has an unfoamed portion, and the surface of the polishing portion has a foamed portion exposed. It is a pad.

  In the polishing pad of the above aspect, the polishing surface is a polishing section for polishing the object to be polished, and a polishing slurry supplied to the polishing pad when the object to be polished is discharged from the polishing pad to the outside. And a groove portion. Since the foamed portion of the foam is exposed on the surface of the polishing portion and the surface of the groove portion has an unfoamed portion, the maximum height roughness (Rz) of the polishing portion surface is determined by the maximum height roughness (Rz) of the groove portion surface. ), And the arithmetic average roughness (Ra) of the polished portion surface is larger than the arithmetic average roughness (Ra) of the groove portion surface.

  An embodiment of the present invention provides a polishing pad, wherein the maximum height roughness (Rz) of the surface of the groove portion is 10 μm to 30 μm, and the maximum height roughness (Rz) of the surface of the polishing portion is 30 μm to 100 μm. It is.

  An embodiment of the present invention provides a polishing pad, wherein the arithmetic mean roughness (Ra) of the surface of the groove portion is 0.1 μm to 10 μm, and the arithmetic average roughness (Ra) of the surface of the polishing portion is 10 μm to 45 μm. is there.

  An embodiment of the present invention provides a polishing pad having a value of (maximum height roughness (Rz) of the surface of the polishing portion)-(maximum height roughness (Rz) of the surface of the groove portion) of 20 μm to 70 μm. is there.

  An embodiment of the present invention is the polishing pad, wherein a value of (arithmetic average roughness (Ra) of the surface of the polishing portion)-(arithmetic average roughness (Ra) of the surface of the groove) is 5 μm to 35 μm.

  An embodiment of the present invention has a three-dimensional cell structure, having a resin foam made of a thermoplastic resin, the thermoplastic resin is at least selected from the group consisting of polyphenylene sulfide resin, polyethylene terephthalate resin and polycarbonate resin This is one type of polishing pad.

  According to the aspect of the present invention, since the surface of the groove has an unfoamed portion, the polishing slurry can be smoothly discharged from the polishing pad. Therefore, it is possible to prevent the polishing residue (polishing residue) mixed into the polishing slurry by the polishing process from remaining on the polishing pad. Further, since the polishing slurry can be smoothly discharged from the polishing pad, the temperature rise of the polishing pad can be prevented. On the other hand, the foamed part is exposed on the surface of the polishing part, that is, since the surface is rough, the polishing performance of the polishing part is improved, and also in that the polishing slurry is trapped in the exposed foamed part. In addition, the polishing performance of the polishing section is improved.

FIG. 2 is a partial side sectional view of the polishing pad according to the embodiment of the present invention. FIG. 3 is a partial side sectional view of a resin member used in an example of a method for manufacturing a polishing pad according to an embodiment of the present invention. FIG. 1A is an explanatory view of an entire groove forming mold member used in an example of a method for manufacturing a polishing pad according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view of the groove forming mold member taken along line AA. FIG. It is explanatory drawing of the example of the manufacturing method of the polishing pad which concerns on the example of embodiment of this invention using the groove | channel part forming die member.

  Hereinafter, a polishing pad according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, in a polishing pad 1 according to an embodiment of the present invention, a polishing surface 10 which is a polishing-side surface has a polishing portion 11 and a groove portion 12. The polishing unit 11 is a part that polishes an object to be polished (not shown). The groove portion 12 is a portion for discharging the polishing slurry and polishing residue supplied to the polishing pad when polishing the object to be processed from the polishing surface 10 to the outside.

  The polishing pad 1 includes a resin foam 15 having a surface unfoamed layer 13 whose surface layer is an unfoamed portion, and a foamed portion 14 provided inside the surface unfoamed layer 13. In the polishing pad 1, the foamed portion 14 of the resin foam 15 is exposed on almost the entire surface of the polishing portion 11. Therefore, in the polishing pad 1, the surface of the polishing portion 11 does not have the surface non-foamed layer 13.

  The foaming portion 14 of the resin foam 15 has a three-dimensional cell structure in which a plurality of cells 17 partitioned by cell walls 16 are formed densely. Since the three-dimensional bubble structure is exposed from the surface in the polishing unit 11, the inner surface of the bubble 17 is exposed on the surface of the polishing unit 11. Therefore, the surface of the polishing section 11 has a porous structure. In the polishing section 11, the foamed section 14 can be exposed by previously removing the surface non-foamed layer 13 by a polishing process or the like.

  On the other hand, the surface of the groove 12 has an unfoamed portion of the resin foam 15. That is, the surface of the groove 12 is the surface unfoamed layer 13. No bubbles are formed in the surface unfoamed layer 13 by the foaming process. In the polishing pad 1, almost the entire surface of the groove 12 is a surface non-foamed layer 13 which is an unfoamed portion. Therefore, the surface of the groove 12 does not expose the inside of the bubble 17, that is, the inner surface of the bubble wall 16, and does not show a porous structure.

  From the above, the surface of the groove portion 12 which is the surface unfoamed layer 13 is smooth, and the surface of the polishing portion 11 where the foamed portion 14 is exposed is rougher than the surface of the groove portion 12. That is, the maximum height roughness (Rz) and the arithmetic average roughness (Ra) of the surface of the polishing portion 11 are larger than those of the surface of the groove portion 12. In the present specification, “maximum height roughness (Rz)” and “arithmetic average roughness (Ra)” mean values measured with a laser microscope (VX-X150, manufactured by Keyence Corporation).

  The maximum height roughness (Rz) of the surface of the polishing section 11 is not particularly limited. For example, the lower limit is preferably 20 μm or more from the viewpoint of improving the polishing performance of the polishing section 11 due to the rough surface. The thickness is more preferably 25 μm or more, particularly preferably 30 μm or more, from the viewpoint that the polishing slurry is caught on the inner surface of the cell wall 16 of the foaming section 14 and the polishing performance of the polishing section 11 is further improved. On the other hand, the upper limit of the maximum height roughness (Rz) of the surface of the polishing portion 11 is, for example, preferably 100 μm or less, more preferably 65 μm or less, and particularly preferably 55 μm or less from the viewpoint of ease of production of the resin foam 15. .

  The arithmetic average roughness (Ra) of the surface of the polishing section 11 is not particularly limited. For example, the lower limit is preferably 10 μm or more from the viewpoint of improving the polishing performance of the polishing section 11 due to the rough surface. The size is more preferably 15 μm or more, particularly preferably 25 μm or more, from the viewpoint that the polishing slurry is caught on the inner surface of the cell wall 16 of the portion 14 and the polishing performance of the polishing portion 11 is further improved. On the other hand, the upper limit value of the arithmetic average roughness (Ra) of the surface of the polishing portion 11 is, for example, preferably 45 μm or less, and particularly preferably 35 μm or less from the viewpoint of ease of production of the resin foam 15.

  Although the maximum height roughness (Rz) of the surface of the groove 12 is not particularly limited, for example, the lower limit is preferably 10 μm or more, and particularly preferably 15 μm or more from the viewpoint of ease of production of the resin foam 15. On the other hand, the upper limit of the maximum height roughness (Rz) is, for example, that the polishing slurry is smoothly discharged from the polishing pad, and the polishing residue mixed into the polishing slurry by the polishing process on the object to be processed is retained in the polishing pad. The thickness is preferably 30 μm or less, from the viewpoint of reliably preventing polishing, and more preferably 25 μm or less, particularly preferably 20 μm or less, from the viewpoint of smoothly discharging the polishing slurry from the polishing pad and reliably preventing the temperature of the polishing pad from rising.

  Although the arithmetic average roughness (Ra) of the surface of the groove 12 is not particularly limited, for example, the lower limit is preferably 0.1 μm or more, particularly preferably 0.5 μm or more from the viewpoint of ease of production of the resin foam 15. On the other hand, the upper limit of the arithmetic average roughness (Ra) is, for example, such that the polishing slurry is smoothly discharged from the polishing pad and the polishing residue mixed into the polishing slurry by the polishing process on the object to be processed, but stays on the polishing pad. The thickness is preferably 10 μm or less, from the viewpoint of reliably preventing the occurrence of the problem, more preferably 5 μm or less, particularly preferably 3 μm or less, from the viewpoint of smoothly discharging the polishing slurry from the polishing pad and reliably preventing the temperature of the polishing pad from rising.

  The value of (maximum height roughness (Rz) of the surface of the polishing portion 11)-(maximum height roughness (Rz) of the surface of the groove portion 12), that is, the maximum height roughness (Rz) of the surface of the polishing portion 11 and the groove portion 12 The difference in the maximum height roughness (Rz) of the surface is not particularly limited. For example, the lower limit is preferably 20 μm or more, and more preferably 30 μm or more from the viewpoint of improving the balance between the polishing performance and the discharge characteristics of the polishing slurry. Is particularly preferred. On the other hand, the upper limit of the difference between the maximum height roughness (Rz) of the surface of the polishing portion 11 and the maximum height roughness (Rz) of the surface of the groove portion 12 is not particularly limited. From the viewpoint, it is preferably 70 μm or less, particularly preferably 60 μm or less.

  The value of (arithmetic average roughness (Ra) of the surface of the polishing portion 11)-(arithmetic average roughness (Ra) of the surface of the groove portion 12), that is, the arithmetic average roughness (Ra) of the surface of the polishing portion 11 and the surface of the groove portion 12 The difference in arithmetic average roughness (Ra) is not particularly limited. For example, the lower limit is preferably 5 μm or more, particularly preferably 10 μm or more from the viewpoint of improving the balance between polishing performance and polishing slurry discharge characteristics. On the other hand, the upper limit value of the difference between the arithmetic average roughness (Ra) of the surface of the polishing portion 11 and the arithmetic average roughness (Ra) of the surface of the groove portion 12 is not particularly limited, but from the viewpoint of ease of production of the resin foam 15. It is preferably at most 35 μm, particularly preferably at most 30 μm.

  The material of the resin foam 15 is not particularly limited, but examples thereof include hard resins such as polyphenylene sulfide resin (PPS resin), polyethylene terephthalate (PET resin), and polycarbonate resin (PC resin).

  The thickness of the resin foam 15 provided on the polishing pad 1 is not particularly limited, but may be, for example, in a range of about 0.5 to 2.0 mm. 0 mm. The depth of the groove 12 is not particularly limited, but may be, for example, in a range of about 0.2 to 1.0 mm, and is about 0.5 mm in the polishing pad 1.

  The resin foam 15 has a three-dimensional cell structure in which a plurality of cells (cells) and these cells are defined by cell walls so as to have mutually independent sections. The average cell diameter is not particularly limited, but is preferably, for example, 4 to 50 μm. The average cell wall thickness is not particularly limited, but is, for example, preferably 1 to 5 μm. Here, the bubble diameter is a diameter when bubbles in an arbitrary cross section are converted into a circle having the same area, and the average bubble diameter refers to an average of bubble diameters of arbitrarily selected 10 bubbles. The bubble wall thickness is a minimum thickness of a bubble wall between adjacent bubbles in an arbitrary cross section, and the average bubble wall thickness is an average of arbitrarily selected 10 wall thicknesses. The average cell diameter and the average cell wall thickness can be determined by image processing of a structure photograph of the resin foam 15 observed with a scanning electron microscope (SEM, manufactured by JEOL Ltd.).

  If the average cell diameter is smaller than 4 μm, the number of abrasive grains held in the cells will decrease, and the polishing rate will decrease and a stable polished surface will not be obtained. If the average cell diameter exceeds 50 μm, the strength of the cell wall will decrease. Insufficiently, a stable polishing state cannot be obtained, and the surface quality is deteriorated. At the same time, a large amount of abrasive particles accumulate in bubbles, secondary particles are generated, and surface defects such as scratches are easily generated. By setting the average cell diameter in this range, the cell structure is more optimized and the polishing rate is excellent.

  The ratio of the average cell diameter to the average cell wall thickness is preferably 4 or more and 10 or less. If the ratio of the average cell diameter to the average cell wall thickness is less than 4, the number of abrasive particles held as polishing particles inside the cells will decrease, and the polishing rate will decrease, and a stable polishing surface will not be obtained. If it exceeds, the strength of the cell wall will be insufficient, and a stable polishing state will not be obtained, and the polishing rate will decrease.

  Next, an example of a method for manufacturing the polishing pad 1 according to the embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 2, in manufacturing the polishing pad 1, a flat resin member having a surface unfoamed layer 13 whose surface layer is an unfoamed portion and a foamed portion 14 provided inside the surface unfoamed layer 13 is used. Use 20. One flat surface on which the surface unfoamed layer 13 is provided is a polishing-side surface of the polishing pad 1. Therefore, the outer surface of the surface non-foamed layer 13 of the resin member 20 is substantially flat. The thickness of the resin member 20 is the thickness of the resin foam 15 described above, and the thickness of the surface unfoamed layer 13 of the resin member 20 is not particularly limited, but may be, for example, in a range of about 25 to 100 μm. The thickness of the resin member 20 is about 50 μm. The thickness of the foamed portion 14 of the resin member 20 is a thickness obtained by subtracting the thickness of the front and back surface unfoamed layers 13 of the resin member 20 from the thickness of the resin member 20.

  First, the groove 12 is formed in the surface unfoamed layer 13 of the resin member 20 described above. As a method of forming the groove 12, for example, as shown in FIGS. 3A and 3B, a groove forming mold member 21 having a blade-shaped protrusion 22 is used. The groove forming die member 21 has a thin flat plate shape. The arrangement of the protrusions 22 of the groove forming mold member 21 is not particularly limited, but in FIG. 3A, a plurality of protrusions 22 are formed concentrically at substantially equal intervals. The cross-sectional shape of the projection 22 is not particularly limited. However, as shown in FIG. 3B, in the groove-forming member 21, the cross-section of the projection 22 is substantially triangular.

  By pressing the groove forming mold member 21 on the resin member 20 of FIG. 2 and pressing the top of the protrusion 22 of the groove forming mold member 21 against the surface unfoamed layer 13 of the resin member 20 with a predetermined pressure, the surface The unfoamed layer 13 is pushed in the direction of the foamed portion 14 to form the groove 12 in the polishing pad 1. Accordingly, the grooves 12 are formed in the surface unfoamed layer 13 of the resin member 20 corresponding to the positions of the protrusions 22 of the groove forming mold member 21 in FIG. Further, the depth of the groove 12 is specified corresponding to the height of the protrusion 22. Therefore, the height of the protrusion 22 can be appropriately selected according to the desired depth of the groove 12, and can be, for example, in the range of about 0.2 to 1.0 mm. The groove 21 is about 0.5 mm. Examples of the material of the groove forming die member 21 include metal and hard resin.

  As a method of applying the groove-forming member 21 to the resin member 20, for example, as shown in FIG. 4, while forming the groove-forming member 21 in a roll shape, while rotating the roll-shaped groove-forming member 21, The groove 12 can be formed on the resin member 20 by pressing the protrusion 22 against the surface unfoamed layer 13 of the resin member 20 with a predetermined pressure.

  On the polishing side of the resin member 20 in which the groove 12 is formed, a part other than the groove 12 functions as the polishing part 11. By removing the surface unfoamed layer 13 at a portion other than the groove portion 12 by a polishing process such as buffing, the foamed portion 14 of the resin member 20 is exposed to form the polishing portion 11 and the polishing pad 1 can be obtained.

  The thickness of the resin foam 15 including the surface unfoamed layer 13 that is removed by buffing or the like is not particularly limited, but may be, for example, removal in a range of about 50 to 200 μm. In the polishing pad 1 according to the example, since the thickness of the surface unfoamed layer 13 of the resin member 20 is about 50 μm, the polishing pad 1 is in a state after about 100 μm has been removed.

  In the above-described example of the manufacturing method of the polishing pad 1, the groove 12 having a smooth surface can be formed by pressing the blade-shaped protrusion 22 against the resin member 20 having the surface unfoamed layer 13 and the foamed portion 14. Is easy to manufacture. Further, since the groove 12 can be formed by pressing the protrusion 22 against the resin member 20, the shape and arrangement of the groove 12 can be changed by changing the shape and arrangement of the protrusion 22, and the design of the groove 12 can be freely performed. The degree can be improved.

  The method for producing the resin member 20 having the surface unfoamed layer 13 and the foamed portion 14 is not particularly limited, and a known method can be used. For example, a molding of a predetermined unfoamed resin is sealed in a high-pressure container, an inert gas is injected into the high-pressure container, and the inert gas permeates the molding under pressure. After infiltrating the inert gas, the pressure in the pressure vessel is released, and then the molded body is heated and foamed, and the molded body is further cooled to produce the resin member 20 having the surface unfoamed layer 13 and the foamed portion 14. Can be mentioned. Alternatively, a foaming nucleating agent is added to a thermoplastic resin layer for forming a foamed layer, or a crystallization nucleating agent and a crystallization accelerator are added to a thermoplastic resin layer for forming a non-foamed layer. This also makes it possible to control the foamability of each resin layer to some extent. In addition, by adopting a specific resin as the thermoplastic resin used for forming each layer, it is possible to more strictly control the foaming property. By appropriately adjusting the foaming conditions, the dimensions of the bubbles 17, the dimensions of the cell walls 16, the density of the bubbles 17, and the like are adjusted, and the maximum height roughness (Rz) and the arithmetic average roughness (Rz) of the polishing unit 11 are adjusted. Ra) can be adjusted.

  The polishing pad according to the embodiment of the present invention can be used, for example, in a polishing apparatus for polishing magnetic disks, semiconductor wafers, various substrates, and electronic materials. As the polishing apparatus, for example, a lower surface plate having a polishing pad disposed on the inner surface thereof, a support member for supporting an object to be processed such as a semiconductor wafer on the lower surface plate polishing pad, and a polishing pad disposed on the inner surface, the semiconductor wafer For example, a polishing apparatus having an upper surface plate for applying a predetermined pressure to an object to be processed and a polishing slurry supply means may be used.

  Next, another embodiment of the polishing pad of the present invention will be described. In the polishing pad 1 according to the above-described embodiment, the foamed portion 14 is exposed from the entire surface of the polishing portion 11, and the polishing portion 11 does not have the surface non-foamed layer 13. Among them, the foamed portion 14 may be exposed from a part of the surface, and the other surface may be the surface non-foamed layer 13.

  Further, in the above-described groove forming mold member, the cross section of the protrusion is substantially triangular. However, the shape is not limited as long as the protrusion is in the form. For example, a square such as a trapezoid or the like may be used instead. A polygon such as a pentagon, a substantially semi-elliptical shape, a substantially semi-circular shape, etc. may be used.

  Since the polishing pad of the present invention is excellent in polishing performance and polishing slurry discharge characteristics, it can be used in a wide range of fields, for example, in the field of polishing magnetic disks and semiconductor wafers requiring advanced smooth mirror polishing. High utility value.

DESCRIPTION OF SYMBOLS 1 Polishing pad 10 Polished surface 11 Polished part 12 Groove part 13 Surface non-foamed layer 14 Foamed part 15 Resin foam

Claims (6)

A polishing pad having a polishing portion and a groove portion on the polishing surface,
A polishing pad in which the surface of the groove has an unfoamed portion, and the surface of the polishing portion has a foamed portion exposed.   The polishing pad according to claim 1, wherein the maximum height roughness (Rz) of the surface of the groove portion is 10 m to 30 m, and the maximum height roughness (Rz) of the surface of the polishing portion is 30 m to 100 m. .   The polishing according to claim 1, wherein an arithmetic average roughness (Ra) of a surface of the groove portion is 0.1 μm to 10 μm, and an arithmetic average roughness (Ra) of a surface of the polishing portion is 10 μm to 45 μm. pad.   The value of (maximum height roughness (Rz) of the surface of the polishing portion)-(maximum height roughness (Rz) of the surface of the groove portion) is 20 μm to 70 μm. The polishing pad according to item.   The value of (arithmetic average roughness (Ra) of the surface of the polishing portion)-(arithmetic average roughness (Ra) of the surface of the groove portion) is 5 μm to 35 μm. The polishing pad as described.   A resin foam having a three-dimensional cellular structure and made of a thermoplastic resin, wherein the thermoplastic resin is at least one selected from the group consisting of a polyphenylene sulfide resin, a polyethylene terephthalate resin and a polycarbonate resin. The polishing pad according to any one of claims 1 to 5.

Images