JP2011212759A - Polishing pad and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad capable of improving the flatness precision of an object to be polished by improving a polishing rate.SOLUTION: The polishing pad 10 includes longitudinal foams 3 in the thickness direction and a foam body 2 formed with continuous foams 5 therein by the wet film formation method. On the opposite face side to a polishing surface P of the foamed body 2, one resin base material 7 formed with a pattern of a recessed portion 2a and a protrusion portion 2b is bonded to another base material. The foamed body 2 has a region 2a formed with an opening 4 in which the foam 3 is open and a region 2b formed with an opening 6 in which the foam 5 is open. The region 2a corresponds to the recessed portion 2a of the resin base material 7 and the region 2b corresponds to the protrusion portion 2b of the resin base material 7. A total of thickness of the foamed body 2 and the resin base material 7 is uniform. An area of a resin portion at the polishing surface P is ensured in the region 2a and inflow and outflow of slurry are promoted in the region 2b.

Description

  The present invention relates to a polishing pad and a manufacturing method of the polishing pad, and in particular, polishing for polishing an object to be polished, in which a number of vertically long foams are continuously formed in the thickness direction by a wet film forming method. The present invention relates to a polishing pad comprising a sheet-like foam having a surface, and a resin base material having one surface bonded to the opposite side of the polishing surface of the foam, and a method for producing the polishing pad.

  Conventionally, optical parts materials such as lenses, plane parallel plates, reflection mirrors, glass disks for hard disks, photomasks, silicon wafers, glass substrates for liquid crystal displays, etc. require high precision flatness. Therefore, a polishing process using a polishing pad is performed. In such a precision polishing process of an object to be polished, a finishing process (secondary polishing) is widely performed after a polishing process (primary polishing) once in order to improve flatness. During the polishing process, a polishing liquid (slurry) containing abrasive particles is supplied between the object to be polished and the polishing pad.

  In general, a polyurethane resin sheet-like foam formed by a wet film forming method is used for a polishing pad. In the wet film forming method, a resin solution in which a resin is dissolved in a water-miscible organic solvent is applied to a sheet-shaped film forming substrate, and then the resin is coagulated and regenerated in an aqueous coagulating liquid. In the obtained foam, a large number of foams accompanying the solidification regeneration of the polyurethane resin are continuously formed in the inside, and a skin layer having a thickness of about several μm is formed on the surface of the foam. Is done. In a polishing pad provided with a foam formed by such a wet film forming method, a groove is formed on the surface side of the foam in order to prevent the slurry supplied at the time of polishing processing from being unevenly distributed on the processing surface. Processing may be performed. Thus, since the slurry can move through the groove during the polishing process, the slurry can be uniformly distributed over the entire processed surface and the polishing rate can be improved. However, the shape of the groove formed in the foam may be transferred to the processed surface of the object to be polished, and the flatness accuracy of the object to be polished may be impaired.

  On the other hand, depending on the type of object to be polished and the level of polishing processing such as primary polishing and secondary polishing, the skin layer side of the foam is subjected to grinding treatment such as dressing (light sanding) or buffing, and the surface ( An opening may be formed in the polishing surface. In a polishing pad with an opening formed in the polishing surface, foaming expands and contracts due to the pressing force applied during polishing, so the object to be polished is polished at a stable polishing rate by flowing in and out while the slurry is held in the foam. Is done. In addition, since foreign matters such as sludge (polishing waste) generated during polishing are stored in the foam, generation of scratches on the surface of the object to be polished is suppressed.

  As a polishing pad that has been dressed on the skin layer side, for example, by opening only the micropores without opening the internal foam, and suppressing the decrease in surface hardness due to the opening of the foam, A technique for improving waviness is disclosed (see Patent Document 1). In addition, a technique for facilitating the inflow, retention, and discharge of the slurry by removing the skin layer and opening the foam inside to form a foam having a larger opening diameter than the conventional one (patent) Reference 2). Furthermore, in order to eliminate the difference in accuracy of the flatness of the object to be polished caused by the difference in peripheral speed between the outer peripheral part and the central part of the foam, the base material is applied only to the outer peripheral part without attaching the base material to the central part. Buffing is performed on the polishing surface side of the foam, an opening having a large opening diameter is formed in the outer peripheral portion, and an opening having a small opening diameter is formed in the central portion, thereby reducing the amount of polishing on the entire processed surface of the object to be polished. A technique for achieving uniformity is also disclosed (see Patent Document 3).

JP 2004-243445 A JP 2007-160474 A JP 2009-136935 A

  However, in the technique of Patent Document 1, since the internal foaming is not opened and only the micropores are opened, the resin is stretched and the opening is closed as the opening diameter is small and the polishing process proceeds. In addition, the opening may be clogged due to abrasive particles and polishing dust, and the generation of scratches on the object to be polished may increase. When dressing is performed in order to solve these problems, large foaming in the inside opens, and improvement of undulation cannot be achieved. Also, since the thickness variation of the foam is larger than the thickness of the skin layer, even if dressing is performed to such an extent that the skin layer is not removed, the thickness variation of the foam cannot be eliminated, and the surface to be polished is flat. It becomes difficult to improve the accuracy. In the technique of Patent Document 2, since the opening diameter is large and the bulk density of the foam is low, the compression deformation of the foam is increased due to the pressing force during the polishing process, and permanent deformation is likely to occur. When permanent deformation occurs, the elasticity for restoring the deformation of foaming is impaired, and the foam is difficult to return to its original state. As a result, as the polishing process proceeds, the polishing performance changes, and the flatness of the object to be polished decreases. In the technique of Patent Document 3, since the base material is attached only to the outer peripheral portion of the foam without attaching the base material to the center part of the foam, the entire surface of the foam is not supported by the base material, and the slurry is not polished during polishing. There is a risk that the base material and the foam may permeate to the adhesive surface between the base material and the foam, and the base material and the foam may peel off.

  An object of the present invention is to provide a polishing pad capable of improving the polishing rate and improving the flatness accuracy of an object to be polished, and a method for manufacturing the polishing pad, in view of the above-mentioned cases.

  In order to solve the above-mentioned problems, the first aspect of the present invention is polishing for polishing a workpiece by forming a number of vertically long foams in the thickness direction in a continuous manner by a wet film formation method. In a polishing pad comprising a sheet-like foam having a surface and a resin base material having one surface bonded to the opposite side of the polishing surface of the foam, the resin base material has a recess and a recess on the one surface side. A pattern of convex portions is formed, and the foam has a first region in which the foaming opening is formed corresponding to the concave portion of the resin base material on the polishing surface, and the convex portion of the resin base material And a second region having an opening having an opening diameter larger than the opening of the first region, and the total thickness of the foam and the resin base material is uniformized It is characterized by being.

  In the first aspect, since the opening diameter of the first region is smaller than the opening diameter of the second region, the area of the resin portion on the polishing surface is ensured during the polishing process, so that the object to be polished can be reliably polished. Since the opening diameter of the second region is larger than the opening diameter of the first region, the inflow and outflow of the slurry in the foam is promoted during the polishing process. According to this aspect, the first region for reliably polishing the object to be polished and the second region for promoting the inflow and outflow of the slurry are arranged so as to form a pattern, thereby improving the polishing rate. Since the total thickness of the foam and the resin base material is made uniform, the pressing force applied to the object to be polished is equalized, so that the flatness accuracy of the object to be polished can be improved.

  In the first aspect, it is preferable that an opening having an opening diameter of 30 μm or less is formed in the first region, and an opening having an opening diameter of 50 μm or more is formed in the second region. The total width of the first and second regions is preferably in the range of 10 mm to 100 mm. In addition, the aperture ratio of the first region is preferably smaller than the aperture ratio of the second region. The pattern of the concave portion and the convex portion formed on the resin base material may be a stripe shape, a lattice shape, or a concentric circle shape. It is preferable that the resin base material is chamfered or processed with R on the concave and convex portions.

  According to a second aspect of the present invention, there is provided a polishing pad manufacturing method according to the first aspect, wherein a resin solution in which a resin is dissolved in a water-miscible organic solvent is applied to a film-forming substrate so that the surface becomes flat. A foam-forming step in which a sheet-like foam is formed by coagulation in a coagulating liquid containing water as a main component, and the foam formed in the foam-forming step is peeled from the film-forming substrate, A bonding step of bonding the surface of the foam from which the film-forming substrate is peeled off and the one surface of the resin substrate having a concave and convex pattern formed on one surface; and bonding the bonding step And a grinding step of subjecting the opposite surface side of the foam to the resin base so that the total thickness of the combined resin base and the foam is uniform.

  According to the present invention, the first region for reliably polishing the object to be polished and the second region for promoting the inflow and outflow of the slurry are arranged so as to form a pattern, thereby improving the polishing rate. Since the total thickness of the foam and the resin base material is made uniform, the pressing force applied to the object to be polished is equalized, so that the flatness accuracy of the object to be polished can be improved. Obtainable.

It is sectional drawing which shows typically the polishing pad of embodiment to which this invention is applied. It is process drawing which shows the outline of the manufacturing process of the polishing pad of embodiment. It is explanatory drawing explaining the state of foaming formed in the polyurethane resin in a bonding process and a grinding process, (A) is the polyurethane resin from which the film-forming base material was peeled, (B) is a resin base material being bonded together. (C) shows the polyurethane resin after the grinding treatment. It is a top view which shows typically the pattern in which the 1st and 2nd area | region of the polishing pad of embodiment was arrange | positioned at the polishing surface at stripe form. It is a top view which shows typically the arrangement pattern of the 1st and 2nd area | region of the polishing pad of another aspect which can apply this invention, (A) is a concentric arrangement pattern, (B) Lattice arrangement Each pattern is shown. It is a top view which shows typically the distribution state of the opening formed in the grinding | polishing surface of the conventional polishing pad, (A) is the state in which only the opening whose opening diameter is 30 micrometers or less was formed, (B) has an opening diameter. A state where openings of 50 μm or more are formed is shown.

  Hereinafter, embodiments of a polishing pad to which the present invention is applied will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, the polishing pad 10 of this embodiment includes a sheet-like foam 2 and a resin base material 7 formed of polyurethane resin by a wet film forming method. The foam 2 has a substantially flat polishing surface P for polishing an object to be polished.

  One surface side of the resin base material 7 is bonded to the opposite surface side of the polishing surface P of the foam 2. On one surface side of the resin base material 7, a pattern of concave portions 7a and convex portions 7b is formed. The difference in thickness between the concave portion 7a and the convex portion 7b is formed to be in the range of 50 to 200 μm. The total thickness of the foam 2 and the resin base material 7 is made uniform by buffing the skin layer formed during wet film formation. That is, the polishing surface P is formed on the buffed surface. The foam 2 is formed with foam 3 and foam 5 having a rounded cross-section that is vertically long along the thickness direction. Both the foam 3 and the foam 5 are formed so that the diameter on the polishing surface P side is smaller than the surface side opposite to the polishing surface P. That is, the foam 3 and the foam 5 are reduced in diameter on the polishing surface P side. In the foam 2, the portion where the foam 3 is formed corresponds to the concave portion 7 a of the resin base material 7, and the portion where the foam 5 is formed corresponds to the convex portion 7 b of the resin base material 7. For this reason, the length of the foam 5 in the thickness direction is smaller than the length of the foam 3 in the thickness direction. Moreover, the opening 4 having an opening diameter of 30 μm or less is formed by opening the foam 3 on the polishing surface P, and the opening 6 having an opening diameter of 50 μm or more is formed by opening the foam 5 on the polishing surface P. In the polyurethane resin between the foam 3 and the foam 5, micropores smaller than the foam 3 and the foam 5 are formed, but these micropores are omitted in FIG. 1. The foam 3, the foam 5 and the micropores are connected in a mesh pattern with communication holes (not shown). That is, the foam 2 has a continuous foam structure.

  A region 2a as a first region in which the foam 3 is opened and the opening 4 having an opening diameter of 30 μm or less is mainly formed on the polishing surface P of the foam 2, and the opening 6 in which the foam 5 is opened and the opening diameter is 50 μm or more. Has a region 2b as a second region formed mainly. The resin base material 7 bonded to the foam 2 is formed with a striped pattern of concave portions 7a and convex portions 7b on one surface side. The region 2a corresponds to the concave portion 7a of the resin base material 7, and the region 2b corresponds to the convex portion 7b. In other words, the regions 2a and 2b respectively corresponding to the concave portions 7a and the convex portions 7b formed in the stripe pattern are arranged on the polishing surface P so as to form a stripe pattern. The aperture ratio of the region 2a is formed to be smaller than the aperture ratio of the region 2b. The opening ratios of the region 2a and the region 2b indicate the ratio of the opening area of the region to the entire area of each region of the polishing surface P.

  As shown in FIG. 4, the region 2 a and the region 2 b of the foam 2 are arranged in a regular pattern so as to have a stripe shape on the polishing surface P. At this time, in the region 2a, the shortest distance between one end of one region 2a and the other end of the adjacent region 2a via the region 2a and the region 2b is adjusted to a range of 1 to 10 mm. Yes. Moreover, the area ratio of the area | region 2a with respect to the grinding | polishing surface P is adjusted to the range of 1 / 3-9 / 10. The area ratio of the region 2a to the polishing surface P indicates the area ratio of the entire region including the resin portion and the opening portion. “Pattern with regularity” does not mean a strict geometric regular structure, but the state in which regularity is structurally recognized, that is, the aperture diameter and the distribution of apertures are random. It means that it was not formed. Therefore, even if slight irregularities (variations) occur in the shape, size, interval, etc. of the openings, they are included in the pattern having regularity.

  Further, the polishing pad 10 has one surface side of the double-sided tape 8 for attaching the polishing pad 10 to the polishing machine bonded to the surface opposite to the polishing surface P. The double-sided tape 8 has a base material such as polyethylene terephthalate (hereinafter abbreviated as PET), and an adhesive is applied to both surfaces thereof. A release paper (not shown) is provided on the other side (lowermost side) of the double-sided tape 8.

(Manufacturing)
As shown in FIG. 2, the polishing pad 10 includes a preparation process for preparing a resin solution in which a polyurethane resin is dissolved, and an application process (a part of a foam formation step) in which the resin solution is continuously applied to a film-forming substrate. , A coagulation regeneration process (part of the foam formation step) in which the polyurethane resin is coagulated and regenerated into a sheet in an aqueous coagulation liquid, a washing / drying process for washing and drying the coagulated and regenerated polyurethane resin, and a polyurethane resin after drying. Bonding step (bonding step) for peeling the film substrate and bonding the resin substrate 7 and a grinding step (grinding) for applying a grinding process so as to make the thickness uniform on the surface opposite to the resin substrate of the polyurethane resin Step), and is manufactured through a laminating process in which a double-sided tape 8 is attached to the resin base material 7 attached to the foam 2. Hereinafter, it demonstrates in order of a process.

  In the preparation step, N, N-dimethylformamide (hereinafter abbreviated as DMF), which is a water-miscible organic solvent capable of dissolving the polyurethane resin, and an additive are mixed to dissolve the polyurethane resin. The water-miscible organic solvent may be any organic solvent that is miscible with water at an arbitrary ratio. For example, N, N-dimethylacetamide or the like may be used in addition to DMF. For the polyurethane resin, a polyester-based, polyether-based, or polycarbonate-based resin is used. For example, the polyurethane resin is dissolved in DMF so as to be 30% by weight. Additives include pigments such as carbon black to control foam size and number per unit volume, hydrophilic activators that promote foam formation, and hydrophobic activators that stabilize polyurethane resin coagulation regeneration Can be used. The resulting solution is degassed under reduced pressure to obtain a polyurethane resin solution.

  In the application step, the polyurethane resin solution obtained in the preparation step is applied to the belt-shaped film forming substrate with a substantially uniform thickness at a normal temperature by an application device such as a knife coater. At this time, the application thickness (application amount) of the urethane resin solution is adjusted by adjusting the gap between the knife coater and the film forming substrate. A resin-made nonwoven fabric or film such as PET resin can be used for the film-forming substrate, but in this example, a PET film is used as the film-forming substrate.

  In the coagulation regeneration process, the polyurethane resin solution applied to the film-forming substrate is guided to a coagulation liquid (water-based coagulation liquid) whose main component is water which is a poor solvent for the polyurethane resin. First, micropores are formed on the surface side of the applied resin solution, and a skin layer having a thickness of about several μm is formed. Thereafter, the polyurethane resin coagulates and regenerates on the film-forming substrate as the substitution of the DMF in the polyurethane resin solution and the coagulating liquid proceeds. When DMF is desolvated from the polyurethane resin solution and DMF and the coagulating liquid are replaced, a large number of foams and micropores not shown are formed in the polyurethane resin inside the skin layer, and foaming and illustration are omitted. The micropores communicate in a network. A large number of foams in the interior are formed in a vertically long shape over the entire coating thickness of the polyurethane resin. At this time, since the PET sheet of the film forming substrate does not permeate water, desolvation occurs on the surface side (skin layer side) of the mixed solution, and foaming larger on the film forming substrate side than the surface side is formed.

  In the washing / drying step, the sheet-like polyurethane resin coagulated and regenerated in the coagulation regeneration step is peeled off from the film-forming substrate and washed in a cleaning solution such as water to remove DMF remaining in the polyurethane resin. After washing, the polyurethane resin is dried with a cylinder dryer. The cylinder dryer includes a cylinder having a heat source therein. The polyurethane resin is dried by passing along the peripheral surface of the cylinder. The polyurethane resin after drying is wound into a roll.

In the bonding step, one surface side of the resin substrate 7 is bonded to the surface from which the polyurethane resin film-forming substrate after cleaning and drying has been peeled off. As shown in FIG. 3 (A), after washing and drying, the polyurethane resin 2 ₀ wound in a roll, a large number of elongated foam across the thickness direction is formed at substantially the same height position. As shown in FIG. 3 (B), when bonded to one side of the resin substrate 7 that the pattern of the recesses 7a and the convex portion 7b is formed on one surface, the portion corresponding to the convex portion 7b of the polyurethane resin 2 ₀ , because they are pushed out to the surface side, the surface side of the polyurethane resin 2 ₀ becomes uneven. Since the difference in thickness between the concave portion 7a and the convex portion 7b is formed in the range of 50 to 200 μm, the height position of the foam 5 extruded by the convex portion 7b due to the difference in thickness is that of the foam 3 corresponding to the concave portion 7a. It becomes higher than the height position.

The grinding process, subjected to grinding treatment to the surface side of the polyurethane resin 2 ₀ such that the sum of the thickness of the polyurethane resin 2 ₀ and the resin base material 7 becomes uniform. Thus, as shown in FIG. 3 (C), the surface side of the polyurethane resin 2 ₀ a substantially flat polishing surface P is grinding process is formed. By buffing, the surface of the foam 2 is eliminated. Further, since the foam 5 is pushed out by the convex portion 7b, the foam 5 is removed more than the foam 3. Therefore, the opening diameter of the foam 5 is larger than the opening diameter of the foam 3. That is, on the polishing surface P of the foam 2, the region 2 a in which the foam 3 is opened and the opening 4 having an opening diameter of 30 μm or less is formed, and the region 2 b in which the foam 5 is opened and the opening diameter is 50 μm or more is formed. Are formed corresponding to the concave portion 7a and the convex portion 7b, respectively. A buffing machine, a slicing machine, or the like can be used for the grinding process.

  In the laminating process, the one surface side of the double-sided tape 8 is bonded to the other surface side of the resin base material 7 bonded to the obtained foam 2 on the one surface side. The other side of the double-sided tape 8 is covered with a release paper (not shown). Then, the polishing pad 10 is completed by performing an inspection such as cutting to a desired shape and size and confirming that there is no adhesion of dirt or foreign matter.

(Function)
Next, the operation and the like of the polishing pad 10 of this embodiment will be described.

  In the polishing pad 10 of the present embodiment, a region 2a in which the opening 4 having an opening diameter of 30 μm or less is mainly formed on the polishing surface P of the foam 2 and a region 2b in which the opening 6 having an opening diameter of 50 μm or more is mainly formed. have. Further, the aperture ratio of the region 2a is formed to be smaller than the aperture ratio of the region 2b. For this reason, in the region 2a, the area of the resin portion on the polishing surface P is ensured at the time of polishing, so that the object to be polished can be reliably polished. In the region 2b, since the opening diameter and the opening ratio are larger than the opening diameter and the opening ratio of the region 2a, the inflow and outflow of the slurry in the foam is promoted during the polishing process. Further, foreign matters such as sludge generated during the polishing process can be easily stored in the foam, and generation of scratches on the surface of the object to be polished can be suppressed.

  Further, in the polishing pad 10 of the present embodiment, the region 2a for reliably performing the polishing process on the polishing surface P and the region 2b for promoting the inflow and outflow of the slurry are arranged so as to form a stripe pattern. The total width of the region a and the region 2b is adjusted to be in the range of 10 to 100 mm. For this reason, at the time of polishing, the polishing rate is improved, the slurry can be dispersed substantially uniformly over the entire processed surface, and the object to be polished can be flattened with higher accuracy. In order to separate the region 2a and the region 2b in a range smaller than 50 μm, the diameter of the foam 3 and the foam 5, particularly the diameter on the resin base material 7 side is larger than the separation distance. It becomes difficult to form the region 2a and the region 2b so as to correspond to 7b. On the other hand, if the region 2a and the region 2b are separated from each other in a range larger than 200 μm, the region 2a for reliably polishing the object to be polished decreases, and the polishing rate cannot be improved.

  Furthermore, in the polishing pad 10 of the present embodiment, the area ratio of the region 2a to the polishing surface P is adjusted to a range of 1/3 to 9/10. For this reason, the effect | action which polishes the area | region 2a reliably and the effect | action which accelerates | stimulates the inflow / outflow of the slurry of the area | region 2b can be exhibited with sufficient balance. When the area ratio of the region 2a to the polishing surface P is smaller than 1/3, the dispersion state of the slurry is made uniform, but the region 2a for reliably polishing the object to be polished is reduced, so that the polishing rate is improved. Can not be. On the other hand, when the area ratio of the region 2a to the polishing surface P is larger than 9/10, the slurry is difficult to be supplied to the entire processing surface, causing unevenness, and the dispersed state of the slurry becomes non-uniform.

  Furthermore, in the polishing pad 10 of the present embodiment, buffing or the like is performed on the opposite surface side of the resin base material 7 of the foam 2 so that the total thickness of the foam 2 and the resin base material 7 is uniform. The grinding process is performed. For this reason, the object to be polished can be polished substantially uniformly, and the flatness of the object to be polished can be improved. Further, in the region 2b, the opening diameter of the opening 6 is larger than the opening diameter of the opening 4 and the opening ratio is larger than the region 2a. By being supported by 7b, the compression crushing of the foam 5 due to the pressing force repeatedly applied during the polishing process is suppressed, and stable polishing performance can be maintained for a long period of time. Further, since the region 2b is supported by the convex portion 7b of the resin base material 7, the hardness on the polishing surface P is almost the same in the region 2a and the region 2b, and the polishing particles are substantially uniformly distributed over the entire polishing surface P. Is pressed against the object to be polished, so that stable polishing can be performed.

  In the present embodiment, an example is shown in which the region 2a and the region 2b are disposed on the polishing surface P so as to form a stripe pattern, but the present invention is not limited to this. That is, any arrangement pattern may be used as long as the regions 2a and 2b are arranged so as to form a pattern having regularity. For example, as shown to FIG. 3 (A), you may arrange | position to concentric form, and as shown to FIG. 3 (B), you may arrange | position to a grid | lattice form. When the regions 2a to 2b are arranged concentrically or in a lattice shape, the polishing pad 10 is formed on the resin base material 7 in a concentric or lattice pattern of the recesses 7a to the protrusions 7b and bonded to the foam 2. Can be manufactured. Even if the region 2a and the region 2b are arranged in a pattern having any shape including these, the same effect as in the present embodiment can be obtained.

In this embodiment, an example in which the cross-sectional shape of the convex portion 7b of the resin base material 7 is rectangular (see FIG. 1) is shown, but the cross-sectional shape of the convex portion 7b of the resin base material 7 may be trapezoidal. Good. If it does in this way, it will become easier to adhere | attach a polyurethane resin and the resin base material 7. FIG. Furthermore, the widths of the concave portions 7a and the convex portions 7b of the resin base material 7 can be adjusted according to the polishing characteristics for the object to be polished.
That is, the concave portion 7a and the convex portion 7b may be formed to have the same width, or may be formed so that one is longer (or shorter) than the other. At this time, the width of the convex portion 7b is preferably larger than the diameters of the foam 3 and the foam 5, particularly the diameter on the resin base material 7 side. Further, although not particularly mentioned in the present embodiment, chamfering or R-processing may be performed on the concave portions 7a and the convex portions 7b of the resin base material 7. If it does in this way, a clearance gap will not be easily formed between the resin base material 7 and a polyurethane resin, an air biting etc. can be suppressed, and the resin base material 7 can be bonded together to the foam 2 easily. In addition, it is possible to suppress peeling during polishing.

  Furthermore, in the present embodiment, the polishing surface P has an area 2a in which the opening 4 having an opening diameter of 30 μm or less is mainly formed and an area 2b in which the opening 6 having an opening diameter of 50 μm or more is mainly formed. However, the present invention is not limited to this. For example, the region 2b can be further divided into two or more regions in which openings having different opening diameters are formed among the openings 6 formed in the region 2b. In this case, it is possible to manufacture the polishing pad 10 by attaching the resin base material 7 on which two or more convex portions having different heights are formed to the foam 2 in the bonding step.

  Furthermore, in the present embodiment, the polyurethane foam is exemplified as the resin foam, but the present invention is not limited to this, and other resins may be used. For example, a polyester resin or the like may be used. If a polyurethane resin is used, a continuous foam structure can be easily formed by a wet film forming method.

  Furthermore, in this embodiment, when the polishing pad 10 is manufactured, the double-sided tape 8 in which an adhesive is applied to both surfaces of the base material is bonded to the other surface side of the resin base material 7 attached to the foam 2. Although an example is shown, the present invention is not limited to this. For example, the double-sided tape 8 may be composed of only an adhesive without having a base material.

  Hereinafter, examples of the polishing pad manufactured according to the present embodiment will be described. A comparative polishing pad manufactured for comparison is also shown.

Example 1
In Example 1, polyester MDI (diphenylmethane diisocyanate) polyurethane resin was used as the polyurethane resin for producing the foam 2. To 100 parts of a 30% by weight solution in which this polyurethane resin is dissolved, 45 parts of DMF as a solvent and 40 parts of a DMF dispersion containing 30% by weight of carbon black as a pigment are added and mixed to obtain a polyurethane resin solution. Was prepared. The obtained polyurethane resin solution was applied to a film forming substrate, and then coagulated and regenerated in a coagulating liquid. After the film-forming substrate is peeled off, washed and dried, a polyurethane resin having a thickness of 650 μm is formed into a stripe-like pattern having a concave portion 7a having a width of 45 mm and a convex portion 7b having a width of 5 mm. It bonded together to the resin base material 7 whose thickness difference is 100 micrometers. The skin layer side was ground with a grinding amount of 150 μm from the convex portion so that the total thickness of the polyurethane resin and the resin base material 7 was uniform. The average opening diameter of the region 2a was 25.4 μm, and the average opening diameter of the region 2b was 56.9 μm. A double-sided tape 8 was bonded to the resin substrate 7 to produce a polishing pad 10 of Example 1.

(Comparative Example 1)
In Comparative Example 1, after peeling the film-forming substrate from the polyurethane resin, a polyurethane resin having a thickness of 650 μm was bonded to a substrate having a flat surface and ground so that an opening having an average opening diameter of 30 μm was formed on the polished surface. A polishing pad of Comparative Example 1 was produced in the same manner as Example 1 except that the treatment amount was 50 μm and the skin layer side was ground. That is, as shown in FIG. 6A, the polishing pad of Comparative Example 1 is a polishing pad having only the region 2a of Example 1.

(Comparative Example 2)
In Comparative Example 2, after peeling the film-forming substrate from the polyurethane resin, a polyurethane resin having a thickness of 650 μm was bonded to a substrate having a flat surface, and grinding was performed so that an opening having an average opening diameter of 50 μm was formed on the polished surface. A polishing pad of Comparative Example 1 was produced in the same manner as in Example 1 except that the treatment amount was 150 μm and the skin layer side was ground. That is, as shown in FIG. 6B, the polishing pad of Comparative Example 1 is a polishing pad having only the region 2b of Example 1.

(Polishing)
Using the polishing pads of the examples and comparative examples, the hard disk aluminum substrate was polished under the following polishing conditions, and the polishing rate and waviness were measured. The polishing rate is one of the numerical values indicating the polishing efficiency, and represents the polishing amount per minute in terms of thickness. It calculated from the grinding | polishing amount calculated | required from the weight reduction of the aluminum substrate before and behind grinding | polishing processing, the grinding | polishing area of an aluminum substrate, and specific gravity. Waviness is one of the measurement items for evaluating the surface accuracy (flatness) of an object to be polished, and represents fine irregularities with a period of 80 to 500 μm in units of angstroms (Å). Zygo New View 5022 was used for the measurement of waviness.
(Polishing conditions)
Polishing machine used: Speedfam, 9B-5P polishing machine Polishing speed (rotation speed): 30 rpm
Processing pressure: 100 g / cm ²
Slurry: Colloidal silica slurry (pH: 1.5)
Slurry supply amount: 100cc / min
Object to be polished: Aluminum substrate for hard disk

  As shown in Table 1, in Comparative Example 2 in which an opening having an average opening diameter of 50 μm was formed, the waviness was 4.6 mm. On the other hand, in Comparative Example 1 in which an opening having an average opening diameter of 30 μm is formed, the undulation is 3.1 mm, and a pattern is formed in the region 2a having an opening diameter of 30 μm or less and the region 2b having an opening diameter of 50 μm or more. In Example 1, which was arranged to form, the undulation showed 3.0 mm. This is probably because the polishing pad of Comparative Example 2 has a small area of the resin portion on the polishing surface and is susceptible to a pressing force applied during the polishing process, so that the flatness of the object to be polished is impaired and the swell is deteriorated.

  On the other hand, in Comparative Example 1, the polishing rate was 0.08 μm / min, and in Comparative Example 2, the polishing rate was 0.07 μm / min. On the other hand, in Example 1, the polishing rate was 0.11 μm / min, and the polishing rate of Example 1 showed a value exceeding the polishing rates of Comparative Example 1 and Comparative Example 2. This is because in the polishing pad 10 of Example 1, the region 2a where the object to be polished can be reliably polished and the region 2b which promotes the inflow and outflow of the slurry are arranged so as to form a stripe pattern. It is considered that the polishing rate could be improved while finishing the slurry to have a uniform dispersion state on the entire processed surface during processing, and finishing the waviness of the workpiece to the same level as in Comparative Example 1. Such a polishing pad 10 can be suitably used for polishing a workpiece requiring high flatness accuracy.

  The present invention provides a polishing pad that can improve the polishing rate and improve the flatness accuracy of the object to be polished and a method for manufacturing the polishing pad, and therefore contributes to the manufacture and sales of the polishing pad. Has industrial applicability.

P polished surface 2 foam 2a region (first region)
2b region (second region)
3, 5 Foam 4, 6 Opening 7 Resin base material 7a Concave part 7b Convex part 10 Polishing pad

Claims (7)

  A sheet-like foam having a polishing surface for polishing an object to be polished, in which a large number of vertically long foams are continuously formed in the thickness direction by a wet film formation method, and a polishing surface of the foam A polishing pad provided with a resin base material having one surface side bonded to the opposite surface side, wherein the resin base material has a concave and convex pattern formed on the one surface side, and the foam is the polishing material On the surface, there are a first region in which the opening of the foam is formed corresponding to the concave portion of the resin base material, and an opening having a larger opening diameter than the opening of the first region corresponding to the convex portion of the resin base material. A polishing pad comprising: a second region formed, wherein a total thickness of the foam and the resin base material is uniformized.   2. The opening according to claim 1, wherein an opening having an opening diameter of 30 μm or less is formed in the first area, and an opening having an opening diameter of 50 μm or more is formed in the second area. Polishing pad.   The polishing pad according to claim 2, wherein the total width of the first and second regions is in a range of 10 mm to 100 mm.   The polishing pad according to claim 3, wherein an aperture ratio of the first region is smaller than an aperture ratio of the second region.   5. The polishing pad according to claim 4, wherein the concave and convex patterns formed on the resin base material are stripes, lattices, and concentric circles.   2. The polishing pad according to claim 1, wherein the resin base material has a chamfering process or a process with R applied to the concave part and the convex part. It is a manufacturing method of the polishing pad according to claim 1,
Foam that forms a sheet-like foam by applying a resin solution in which a resin is dissolved in a water-miscible organic solvent to a film-forming substrate so that the surface is flat and coagulating in a coagulating liquid containing water as a main component. A body formation step;
The foam formed in the foam forming step is peeled from the film forming substrate, and a pattern of concave and convex portions is formed on the surface side of the foam from which the film forming substrate is peeled and on one surface side. A laminating step of laminating the one side of the resin base material,
A grinding step of performing a grinding process on the opposite surface side of the foam resin base material so that the total thickness of the resin base material and the foam bonded in the bonding step is uniform;
The manufacturing method characterized by including.

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