JP2011212779A - Polishing pad and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad and method for manufacturing the same, capable of improving the flatness 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. The foamed body 2 has a region 2a formed with an opening 4 having an opening diameter of 30 μm or less by opening the foam 3 and a region 2b formed with an opening 6 having an opening diameter of 50 μm or more by opening the foam 5, in a polishing surface P. The region 2a and the region 2b are arranged to form a stripe-like pattern in the polishing surface P. During a polishing process, an object to be polished is completely polished in the region 2a and slurry outflow and inflow 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 provided with a sheet-like foam having a surface and a method of manufacturing 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 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 of the object to be polished may be impaired.

  On the other hand, the surface (polishing surface) is subjected to grinding treatment such as dressing (light sanding) or buffing on the skin layer side of the foam according to the type of object to be polished and the level of primary polishing or secondary polishing. In some cases, an opening is formed. In a polishing pad with an opening formed on the polishing surface, foaming expands and contracts due to the pressing force applied during polishing, so that 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 can be 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 foam is not opened and the microporous is opened, the resin is stretched and the opening is closed as the opening diameter is small and the polishing process proceeds. Further, the opening may be clogged due to abrasive grains and polishing debris, 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. In addition, 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 object to be polished is substantially omitted. It becomes difficult to polish the surface flatly. 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 to recover the deformation of foaming is impaired and it becomes difficult to return to the 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 inner peripheral portion, the entire surface of the foam is not supported by the base material, and the base material and the foam Therefore, the slurry and the foam can easily be peeled off when the slurry penetrates to the bonding surface with the base material during polishing.

  An object of the present invention is to provide a polishing pad capable of improving the polishing rate and improving the flatness 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 including a sheet-like foam having a surface, the foam has a first region in which the foaming opening is formed on the polishing surface, and an opening diameter larger than the opening in the first region. And a second region having a large opening, and the first and second regions are arranged so as to form a pattern.

  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 foaming is easily expanded and contracted by the pressing force applied during the polishing process, and the inflow and outflow of the slurry in the foaming is promoted. According to the first aspect, the polishing rate is improved by arranging the first region for reliably polishing the workpiece and the second region for promoting the inflow and outflow of the slurry so as to form a pattern. The flatness 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 μm to 100 μm. In addition, the aperture ratio of the first region is preferably smaller than the aperture ratio of the second region. The pattern can be striped, latticed, or concentric.

  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 used as a base so that the concave and convex portions are adjacent to each other. A coating step for coating at a different coating amount; a coagulation regeneration step for coagulating the resin solution applied to the base material in the coating step in a concavo-convex manner in a coagulating liquid containing water as a main component and regenerating it into a sheet; A grinding process step of buffing or slicing the sheet regenerated in the coagulation regeneration step so that the thickness of the sheet becomes uniform on the side opposite to the substrate.

  According to a third 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 formed on a substrate on which a pattern of convex portions and concave portions is formed. An application step for applying a flat surface to the substrate, and a coagulation regeneration step for coagulating the resin solution applied to the base material in the application step in a coagulating liquid containing water as a main component to regenerate the sheet. The sheet regenerated in the coagulation regeneration step is peeled from the substrate, and a flat surface is pressed against the surface of the sheet from which the substrate is peeled, so that the thickness of the sheet becomes uniform. And a grinding step for buffing or slicing the surface.

  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. The effect that the flatness of the polished product can be improved can be obtained.

It is sectional drawing which shows typically the polishing pad of embodiment to which this invention is applied. 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 distribute | arranged by the polishing surface at stripe form. It is a top view which shows typically the pattern of the 1st and 2nd area | region of the polishing pad of another aspect which can apply this invention, (A) is arrange | positioned concentrically about the 1st and 2nd area | region. Pattern (B) shows a pattern in which the first and second regions are arranged in a lattice pattern. It is a top view which shows typically the distribution state of the opening formed in the polishing surface of the conventional polishing pad.

  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 the present embodiment includes a foam 2 formed of a 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.

  The foam 2 is formed into a sheet shape with a polyurethane resin by a wet film forming method. In this example, a surface layer (skin layer) formed during wet film formation is removed by buffing, and a polished surface P is formed on the surface. In the foam 2, the foam 3 and the foam 5 having a vertically rounded cross-sectional shape are formed along the thickness direction of the foam 2. 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. The size of the foam 5 is formed larger than the size of the foam 3. In the foam 2, the skin layer is removed by buffing, and the foam 3 and the foam 5 are opened on the polishing surface P, so that an opening 4 having an opening diameter of 30 μm or less and an opening 6 having an opening diameter of 50 μm or more are formed. Yes. 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 those small micropores are omitted in FIG. 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 formed by a wet film forming method.

  The polishing surface P of the foam 2 has a region 2a in which an opening 4 having an opening diameter of 30 μm or less is mainly formed and a region 2b in which an opening 6 having an opening diameter of 50 μm or more is mainly formed. 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. Between the area | region 2a and the area | region 2b, the opening of the range whose opening diameter is 30 micrometers-50 micrometers is formed in steps.

  As shown in FIG. 2, on the polishing surface P, the regions 2a and 2b are arranged in a regular pattern so as to form a stripe shape. At this time, the region 2a is separated such that the shortest distance between one end of one region a and the other end of the adjacent region 2a via the region 2a and the region 2b is 1 to 10 mm. ing. 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 7 for attaching the polishing pad 10 to the polishing machine bonded to the surface opposite to the polishing surface P. The double-sided tape 7 has a base material such as polyethylene terephthalate (hereinafter abbreviated as PET), and an adhesive is applied to both surfaces thereof. A release paper 8 is provided on the other surface side (lowermost surface side) of the double-sided tape 7.

(Manufacturing)
The polishing pad 10 includes a preparation step for preparing a resin solution in which a polyurethane resin is dissolved, a coating step (coating step) for continuously applying the resin solution to a film-forming substrate, and a polyurethane resin in an aqueous coagulation liquid. The coagulation regeneration step (coagulation regeneration step) for coagulating and regenerating into a sheet shape, the washing / drying step for cleaning and drying the coagulated and regenerated polyurethane resin, and the thickness of the foam 2 after drying is made uniform on the polishing surface P side. It is manufactured through a grinding process (grinding process step) for applying a grinding process and a laminating process for attaching the double-sided tape 7 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. As additives, in order to control the length of foam 3 and foam 5 in the thickness direction and the number per unit volume, a pigment such as carbon black, a hydrophilic activator that promotes the formation of foam, and the solidification regeneration of polyurethane resin A hydrophobic active agent or the like to be stabilized can be used. The resulting solution is degassed under reduced pressure to obtain a polyurethane resin solution. At this time, the polyurethane resin solution used is prepared so that the viscosity measured by a B-type viscometer is 10,000 cp or more. The viscosity of the polyurethane resin solution can be adjusted by changing the concentration of the solution and the number average molecular weight of the polyurethane resin.

  In the coating process, the polyurethane resin solution obtained in the preparation process is applied at a normal temperature with a coating device such as a knife coater so that the concave and convex portions are arranged next to each other on the belt-shaped film forming substrate. Apply continuously by changing the amount. At this time, the coating thickness of the polyurethane resin solution is adjusted by coating while periodically changing the gap (clearance) between the knife coater or the like and the film forming substrate. In this example, the coating thickness is adjusted so that the region 2a and the region 2b are striped. That is, the portion where the region 2a is formed is concave by reducing the coating thickness, and the portion where the region 2b is formed is convex by increasing the coating thickness, and there is a difference in height between the concave and convex portions. A polyurethane resin solution is applied so as to be in the range of 50 to 200 μm. In this example, the thickness of the convex portion is adjusted to 750 μm and the thickness of the concave portion is adjusted to 650 μm so that the height difference between the concave portion and the convex portion of the polyurethane resin solution is 100 μm. 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 step, 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, in an uneven shape. 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 in a concavo-convex shape on the film-forming substrate as the substitution of the DMF and the coagulating liquid in the liquid mixture proceeds. When DMF is desolvated from the mixed liquid and DMF and the coagulating liquid are replaced, foam 3, foam 5 and foam not shown are formed in the polyurethane resin inside the skin layer, and foam 3, foam 5, and Foam (not shown) communicates in a mesh shape. Foam like foam 5 is formed on the convex part of the polyurethane resin, and foam like foam 3 is formed on the concave part. That is, since the foam 3 and the foam 5 are formed over the entire coating thickness of the polyurethane resin, the size of the foam 5 formed on the convex portion is larger than the size of the foam 3 formed on the concave portion. . 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 foam 3 and foam 5 having a larger film forming substrate side than the surface side are formed. The

  In the cleaning / drying process, the sheet-like polyurethane resin solidified and regenerated in the coagulation regeneration process (hereinafter referred to as a film-forming resin) is peeled off from the film-forming substrate, washed in a cleaning solution such as water and washed into the film-forming resin. Residual DMF is removed. After cleaning, the film forming resin is dried with a cylinder dryer. The cylinder dryer includes a cylinder having a heat source therein. The film-forming resin is dried by passing along the peripheral surface of the cylinder. The film-forming resin after drying is wound up in a roll shape.

  In the grinding treatment step, grinding treatment is performed on the skin layer side formed on the surface of the film-forming resin so that the thickness of the film-forming resin whose surface is unevenly formed is uniform. The size of the foam 5 formed in the thick part of the film-forming resin is larger than the size of the foam 3 formed in the thin part, and both the foam 3 and the foam 5 are reduced in diameter on the skin layer side. Yes. For this reason, the foam diameter of the foam 5 is larger than the foam diameter of the foam 3 when viewed at a certain thickness position from the surface from which the substrate is peeled. Accordingly, the foaming 3 and the foaming 5 formed inside the film-forming resin by performing grinding treatment on the skin layer side are opened at the polishing surface P, and the opening 4 having an opening diameter of 30 μm or less and the opening diameter of 50 μm. The above opening 6 is formed. A buffing machine, a slicing machine, or the like can be used for the grinding process. Thereby, the thickness of the film-forming resin formed in the uneven shape is made uniform, and the foam 2 is obtained.

  In the laminating process, one surface of the double-sided tape 7 is bonded to the surface opposite to the polishing surface P of the obtained foam 2. The other side of the double-sided tape 7 is covered with a release paper 8. 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. For this reason, in the region 2b, the foam 5 is easily expanded and contracted by the pressing force applied during the polishing process, and the inflow and outflow of the slurry in the foam is promoted. 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. The opening diameter and opening ratio of the region 2a are formed so as to be smaller than the opening diameter and opening ratio of the region 2b. For this reason, in the region 2a, the area of the resin portion of the polishing surface P is ensured during the polishing process, and the object to be polished can be reliably polished.

  Further, in the polishing pad 10 of the present embodiment, the region 2a for reliably performing the polishing process and the region 2b for promoting the inflow and outflow of the slurry in the foam are arranged in a stripe shape so as to form a pattern. The total width of the region 2a and the region b2 is adjusted to be in the range of 10 to 100 mm. For this reason, the slurry can be dispersed substantially uniformly over the entire processed surface during polishing, so that the polishing rate can be improved and the object to be polished can be flattened. If the total width of the region 2a and the region 2b is separated in a range smaller than 10 mm, unevenness of the slurry is likely to occur on the processed surface, and the dispersed state of the slurry becomes non-uniform, making it difficult to polish the object to be polished substantially flatly. Become. On the other hand, if the total width of the region 2a and the region 2b is separated within a range larger than 100 mm, 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 in the foam 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, it is difficult to supply the slurry to the entire processing surface, resulting in unevenness, and the dispersion state of the slurry is deteriorated.

  Furthermore, in the polishing pad 10 of the present embodiment, the foam 2 is made of polyurethane resin, and the viscosity of the resin solution used for manufacturing the foam 2 is adjusted to 10,000 cp or more. For this reason, the resin solution applied in a concavo-convex shape to the base material in the application step can be coagulated and regenerated in a coagulating liquid while maintaining the concavo-convex shape. If the viscosity of the resin solution is less than 10,000 cp, even if the resin solution is applied to the base material in an irregular shape in the coating process, the surface of the resin solution becomes flat by the coagulation regeneration process, and the unevenness is not formed. Since the solidification is regenerated, the region 2a and the region 2b cannot be arranged.

  In addition, in this embodiment, although the thing made from a polyurethane resin was illustrated as a resin-made foam, this invention is not limited to this, You may use another resin. 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.

  Further, in the present embodiment, an example in which the polyurethane resin solution is applied to the film-forming substrate in a concavo-convex shape in the application process at the time of producing the foam 2 is shown, but the present invention is not limited to this. It is only necessary that the film resin can be coagulated and regenerated so that the thickness of the resin film becomes a predetermined pattern of irregularities. For example, the polyurethane resin solution may be applied so that the surface is flat on a film forming substrate formed so that the convex portions and the concave portions are adjacent to each other in the application step. Even in this case, the sheet regenerated after coagulation regeneration is peeled off from the film-forming substrate, and a flat surface is pressed against the surface of the sheet where the substrate is peeled, so that the surface is buffed so that the thickness is uniform. Or the like.

  Further, in the present embodiment, the example in which the double-sided tape 7 is bonded to the side surface opposite to the polishing surface P of the foam 2 when the foam 2 is manufactured is shown, but the present invention is not limited to this. For example, a support may be further bonded between the double-sided tape 7 and the foam 2. By bonding the support, the foam 2 is supported on the entire surface, so that the polishing pad 10 can be stably fixed to the polishing surface plate.

  Furthermore, in the present embodiment, the example in which the region 2a and the region 2b are arranged in a stripe shape is shown, but the present invention is not limited to this. In other words, the region 2a and the region 2b may be arranged in any shape as long as the regions 2a and 2b are arranged adjacent to each other in a regular pattern. For example, as shown in FIG. 3 (A), they may be arranged concentrically, or as shown in FIG. 3 (B). In the case where the regions 2a to 2b are arranged concentrically or in a lattice shape, in the coating process, after the polyurethane resin is coated on the film-forming substrate so that the surface is flat, the polyurethane resin is applied to the portion where the convex portion is disposed with a nozzle. A foam can be manufactured by further applying in a spot form. Even if the region 2a and the region 2b are arranged in any shape including them, the same effect as in the present embodiment can be obtained.

  Furthermore, in this embodiment, it has the area | region 2a in which the opening 4 whose opening diameter is 30 micrometers or less was mainly formed in the grinding | polishing surface P, and the area | region 2b in which the opening 6 whose opening diameter was 50 micrometers or more was mainly formed. Although an example is shown, 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 a foam by applying in the application step so that two or more convex portions having different application thicknesses of the resin solution are formed.

  Hereinafter, examples of polishing pads 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 viscosity of the polyurethane resin solution measured with a B-type viscometer was 12,408 cp. After the obtained polyurethane resin solution was applied to the film-forming substrate in a concavo-convex shape, the sheet-like polyurethane resin solution was coagulated and regenerated in a coagulating liquid. The polyurethane resin had striped irregularities, the thickness of the concave portion was 650 μm, the width was 45 mm, the thickness of the convex portion was 750 μm, and the width was 5 mm. After washing and drying, the skin layer side was ground so that the thickness of the polyurethane resin was uniformly 600 μm. The double-sided tape 7 was bonded to manufacture the polishing pad 10 of Example 1 in which the regions 2a and 2b were arranged so as to form a stripe pattern.

(Comparative Example 1)
In Comparative Example 1, a polyurethane resin solution was applied to a film forming substrate so as to have a flat surface, and after forming a polyurethane resin having a thickness of 650 μm, an opening having an average opening diameter of 30 μm was formed on the polished surface. Thus, the polishing pad of Comparative Example 1 was manufactured in the same manner as in Example 1 except that the grinding 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 a of Example 1.

(Comparative Example 2)
In Comparative Example 2, a polyurethane resin solution was applied to the film-forming substrate so that the surface was flat, and after forming a polyurethane resin having a thickness of 750 μm, an opening having an average opening diameter of 50 μm was formed on the polished surface. Thus, the polishing pad of Comparative Example 2 was manufactured in the same manner as Example 1 except that the grinding amount was 150 μm and the skin layer side was ground. That is, as shown in FIG. 6A, the polishing pad of Comparative Example 2 is a polishing pad having only the region b 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 the amount of waviness of the surface image per unit area observed with an optical non-contact surface roughness meter is measured in angstroms ( Ii) Expressed in units. Evaluation was performed using a Zygo New View 5022 filter as a test evaluator that transmits wavelengths of 80 μm to 500 μm. When the numerical value of the measurement result is low, the undulation of the object to be polished is small, and the polishing surface is flatter. Table 1 below shows the polishing rate and waviness evaluation results.
(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 capable of improving the polishing rate and improving the flatness of an object to be polished and a method for manufacturing the polishing pad, and contributes to the manufacture and sales of the polishing pad. With the above applicability.

P polished surface 2 foam 2a region (first region)
2b region (second region)
3, 5 Foam 4, 6 Opening 10 Polishing pad

Claims (7)

  In a polishing pad provided with a sheet-like foam having a polishing surface for polishing an object to be polished, a large number of vertically long foams are continuously formed in the thickness direction inside by a wet film forming method. The body has a first region in which the foaming opening is formed on the polishing surface, and a second region in which an opening having an opening diameter larger than the opening in the first region is formed, A polishing pad, wherein the first and second regions are arranged so as to form a pattern.   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.   The polishing pad according to claim 4, wherein the pattern has a stripe shape, a lattice shape, or a concentric shape. It is a manufacturing method of the polishing pad according to claim 1,
An application step of applying a resin solution obtained by dissolving a resin in a water-miscible organic solvent while changing the application amount so that the convex portion and the concave portion are adjacent to the substrate,
A coagulation regeneration step in which the resin solution applied to the substrate in the coating step in a concavo-convex manner is coagulated in a coagulation liquid mainly composed of water and regenerated into a sheet;
A grinding step for buffing or slicing so that the thickness of the sheet is uniform on the side opposite to the substrate of the sheet regenerated in the coagulation regeneration step;
The manufacturing method characterized by including. It is a manufacturing method of the polishing pad according to claim 1,
An application step of applying a resin solution obtained by dissolving a resin in a water-miscible organic solvent to a substrate on which a pattern of convex portions and concave portions is formed so that the surface becomes flat,
A coagulation regeneration step in which the resin solution applied to the substrate in the application step is coagulated in a coagulation liquid containing water as a main component and regenerated into a sheet;
The sheet regenerated in the coagulation regeneration step is peeled from the substrate, and a flat surface is pressed against the surface of the sheet from which the substrate is peeled, so that the thickness of the sheet is uniform. Grinding step for buffing or slicing on the side;
The manufacturing method characterized by including.

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