JP5914244B2 - Polishing pad - Google Patents

Description

  The present invention relates to a polishing pad having a surface on one side of an elastic resin sheet as a polishing surface.

  Bare silicon, semiconductor devices, magnetic disk substrates, and the like are polished to smooth their surfaces. This polishing process is to rotate a polishing pad against the surface to be polished while supplying a polishing liquid (slurry) in which abrasive grains are dispersed in an alkaline solution or an acidic solution to the surface to be polished. This is what is called chemical mechanical polishing (CMP).

  The polishing pad is made of various materials according to the required smoothness. In particular, in a polishing pad for final finishing, an elastic resin sheet made of an elastic material such as urethane resin formed by a wet film forming method is often used. The wet film forming method is a method in which a resin solution in which a resin is dissolved is applied to one surface of a film forming substrate, and the applied resin solution is coagulated by immersing it in a coagulating liquid bath. . By replacing the solvent and the coagulation liquid in the resin solution, the resin in the resin solution is aggregated and regenerated (coagulated) to form an elastic resin sheet.

  A plurality of elongated bubbles extending from one surface of the elastic resin sheet to the other surface are formed inside the elastic resin sheet formed by the wet film forming method (Patent Document 1 below). The bubbles are formed in a process in which the resin is aggregated by a wet film forming method, and function as a space for temporarily storing the slurry when performing polishing.

  For example, when the object to be polished is pressed against a part of the rotating polishing pad, the bubbles in the part contract, and the slurry stored inside is discharged toward the object to be polished. When the object to be polished moves to another part, the bubbles expand and return to the original size, and the slurry is stored in the process in the process. Thus, a predetermined amount of slurry is always circulated and supplied between the polishing surface of the polishing pad and the object to be polished as the bubbles repeatedly discharge and store the slurry. As a result, clogging of the polishing pad is prevented, the polishing rate is improved, and polishing with excellent surface quality can be performed.

  The inventors of the present invention further improve the polishing rate of the polishing pad by forming the elongated bubbles in the elastic resin sheet so as to be inclined with respect to the polishing surface rather than being formed substantially perpendicular to the polishing surface. I found. This is presumed to be because the discharge and storage of the slurry in the bubbles are performed more smoothly than in the case where the bubbles are perpendicular to the polishing surface.

  That is, the elongated bubbles have an opening at the tip on the polishing surface side, and the slurry is discharged and stored through the opening. If the bubbles are inclined with respect to the polishing surface, the opening is not yet blocked by the object to be polished when the object to be polished is pressed and the bubbles start to contract. In other words, there is a time difference between the timing at which the bubble starts to contract and the timing at which the opening at the tip of the bubble is blocked. As a result, it is considered that the slurry is discharged smoothly.

  As a method for forming slender bubbles so as to be inclined with respect to the polishing surface, a resin is used in a solidification step of a wet film formation method (step of solidifying a resin solution in which a resin is dissolved in a coagulation liquid). There is a method in which the film formation substrate coated with the solution is slowly lowered and immersed while maintaining a state perpendicular to the liquid surface of the coagulation liquid. In this case, the bubbles are formed such that the tip on the opposite side (polishing surface side) from the film forming substrate is inclined toward the coagulating liquid side (downward).

  The polishing pad is formed by using such an elastic resin sheet alone or by arranging a plurality of the same. As a result, when the elastic resin sheet is viewed along a direction perpendicular to the polishing surface, the inclination direction of each bubble is substantially the same in at least a part of the polishing surface.

JP 2005-335028 A

  In such a polishing pad, a cutting groove is formed in a part of the polishing surface for the purpose of further improving the circulation of the slurry with the object to be polished. Such a cutting groove is formed by cutting a part of the polished surface, and has a V-shaped cross section. In other words, the groove is defined by two inclined surfaces.

  However, when the above-described cutting groove is formed on the elastic resin sheet formed so that the elongated bubbles are inclined, the durability of the elastic resin sheet in the cutting groove may be lowered. For this reason, a part of the elastic resin sheet is damaged by the force received from the object to be polished, so that uniform polishing cannot be performed and so-called polishing unevenness may occur.

  This invention is made | formed in view of such a subject, The objective is to provide the polishing pad with high durability of an elastic resin sheet, forming the cutting groove in a grinding | polishing surface.

  In order to solve the above problems, a polishing pad according to the present invention is a polishing pad in which one surface of an elastic resin sheet is a polishing surface and the other surface is a supported surface, and the inside of the elastic resin sheet Are formed with a plurality of elongated bubbles extending from the supported surface toward the polishing surface, and each of the bubbles is inclined so as to be inclined with respect to the polishing surface at least in the vicinity of the polishing surface. A plurality of the bubbles formed in at least a part of the first region of the elastic resin sheet when viewed along a direction perpendicular to the polishing surface, The directions extending toward the polishing surface are substantially the same in the first direction, and a cutting groove having a V-shaped cross section is substantially perpendicular to the first direction on the polishing surface in the first region. Formed along the second direction The cutting groove is partitioned by a first inclined surface located on the near side along the first direction and a second inclined surface located on the back side along the first direction, and the second An angle formed by the inclined surface with respect to the polishing surface is smaller than an angle formed by the inclined portion with respect to the polishing surface.

  The polishing pad according to the present invention has an elastic resin sheet, and a plurality of elongated bubbles extending from the supported surface toward the polishing surface are formed inside the elastic resin sheet. Each bubble has an inclined portion formed so as to be inclined with respect to the polishing surface at least in the vicinity of the polishing surface. Since such bubbles are formed, the slurry is stored and discharged in each bubble when polishing is performed, and the circulation supply of the slurry to the surface to be polished is promoted.

  Further, in the present invention, when the elastic resin sheet is viewed along a direction perpendicular to the polishing surface, the plurality of bubbles formed in at least a part of the first region of the elastic resin sheet are inclined at the polishing surface. Are formed such that directions extending in the direction toward the polishing surface along the inclined portion are substantially the same direction (first direction). The entire elastic resin sheet may be one first region or may be divided into a plurality of first regions. In any case, the bubbles contained in the same first region are the first in which the directions in which the inclined portions extend toward the polishing surface are substantially the same when the elastic resin sheet is viewed along the direction perpendicular to the polishing surface. It has become a direction.

  In the present invention, a V-shaped cutting groove is formed on the polished surface in the first region. The cutting groove is formed along a second direction substantially perpendicular to the first direction, and is defined by two inclined surfaces (first inclined surface and second inclined surface). A 1st inclined surface is an inclined surface of the direction located in the near side along a 1st direction among two inclined surfaces. A 2nd inclined surface is an inclined surface of the direction located in the back | inner side along a 1st direction among two inclined surfaces. In other words, when viewed along the direction perpendicular to the polishing surface, the direction from the first inclined surface toward the second inclined surface is the direction in which the inclined portion of the bubble extends toward the polishing surface (first direction). Match.

  The angle formed by the second inclined surface with respect to the polishing surface is smaller than the angle formed by the inclined portion (of bubbles belonging to the same first region) with respect to the polishing surface. The present inventors have found that the durability of the elastic resin sheet is remarkably improved by making the shape of the cutting groove like this. The reason is as follows.

  Since the cutting groove is formed by cutting a part of the elastic resin sheet, the bubbles present at a position overlapping the cutting groove in plan view are partly cut out. That is, a communication hole communicating with the bubble is formed in a part of the inclined surface that partitions the cutting groove.

  Here, when the angle formed by the second inclined surface with respect to the polishing surface is temporarily larger than the angle formed by the inclined portion with respect to the polishing surface, the communication hole is formed at a position relatively far from the polishing surface among the bubbles. Will be. In this case, since the strength of the portion of the elastic resin sheet located between the communication hole and the polishing surface is significantly reduced, the portion may be damaged by receiving a force from the object to be polished. is there.

  On the other hand, in the present invention, the angle formed by the second inclined surface with respect to the polishing surface is smaller than the angle formed by the inclined portion with respect to the polishing surface. In this case, a portion of the elastic resin sheet that decreases in strength is not formed between the communication hole and the polishing surface. As a result, a portion that is damaged by receiving a force from the object to be polished is hardly formed at least in the vicinity of the polishing surface.

  As described above, according to the present invention, the durability of the elastic resin sheet is enhanced by devising the shape of the inclined surface that partitions the cutting groove while forming the cutting groove on the polished surface.

  Further, in the polishing pad according to the present invention, the elastic resin sheet has a circular shape in plan view, and when viewed along a direction perpendicular to the polishing surface, each of the bubbles has the inclined portion. It is also preferable that the direction extending toward the polishing surface is formed so as to substantially coincide with the circumferential direction of the elastic resin sheet.

  In this preferred embodiment, when the elastic resin sheet is viewed along a direction perpendicular to the polishing surface, each bubble has a circular shape in the plan view when the inclined portion extends toward the polishing surface. It is formed so as to substantially coincide with the circumferential direction.

  With such a configuration, the inclination direction of the bubbles extending toward the polishing surface is along the direction in which the bubbles advance with respect to the object to be polished when the polishing process is performed. For this reason, the time difference between the timing at which the object to be polished is pressed and the bubbles contract and the timing at which the opening of the bubbles is blocked by the object to be polished is ensured to the maximum. As a result, the circulation property of the slurry between the object to be polished can be further enhanced.

  Further, in the polishing pad according to the present invention, the elastic resin sheet has a circular shape in plan view, and when viewed along a direction perpendicular to the polishing surface, each of the bubbles has the inclined portion. It is also preferable that the direction extending toward the polishing surface is formed so as to substantially coincide with the direction toward the center of the elastic resin sheet.

  In this preferred embodiment, when the elastic resin sheet is viewed along a direction perpendicular to the polishing surface, each bubble has a circular shape in the plan view when the inclined portion extends toward the polishing surface. It is formed so as to substantially coincide with the direction toward the center.

  With such a configuration, the slurry discharged from each bubble to the polishing surface is directed toward the center of the polishing surface. As a result, the retention performance of the slurry between the object to be polished and the polishing surface can be improved.

  According to the present invention, it is possible to provide a polishing pad with high durability of the elastic resin sheet while forming a cutting groove on the polishing surface.

It is sectional drawing which shows a part of polishing pad which concerns on 1st embodiment of this invention. It is a figure which shows arrangement | positioning of the bubble formed in the elastic resin sheet of the polishing pad shown in FIG. 1, and the cutting groove. It is sectional drawing for demonstrating the specific shape of the cutting groove shown in FIG. FIG. 2 is a process diagram schematically showing a manufacturing process of the polishing pad shown in FIG. 1. It is a schematic diagram for demonstrating a coagulation | solidification process among the processes shown in FIG. It is a figure which shows arrangement | positioning of the bubble formed in the elastic resin sheet of the polishing pad which concerns on 2nd embodiment of this invention, and the cutting groove. It is a schematic diagram for demonstrating a solidification process among the manufacturing processes of the polishing pad shown in FIG. It is a schematic diagram for demonstrating a solidification process among the manufacturing processes of the polishing pad shown in FIG. It is a figure which shows arrangement | positioning of the bubble formed in the elastic resin sheet of the polishing pad which concerns on 3rd embodiment of this invention, and the cutting groove.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  First, the configuration of the polishing pad 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing a part of the polishing pad 1, and FIG. 2 is a view showing the arrangement of the bubbles 10 and the cutting grooves 80 formed in the elastic resin sheet 2 of the polishing pad. As shown in FIGS. 1 and 2, the polishing pad 1 has an elastic resin sheet 2 that is circular in plan view.

  One surface of the elastic resin sheet 2 is a polishing surface Sp for polishing an object to be polished. The other surface of the elastic resin sheet 2 is a supported surface Sf for attaching the polishing pad 1 to the polishing apparatus. In the present embodiment, the pad base material 20 is bonded to the supported surface Sf. The pad base material 20 is formed of a sheet-like polyethylene terephthalate (hereinafter referred to as PET) that is circular in plan view.

  A double-sided tape 30 is affixed to the opposite side of the surface of the pad base material 20 that contacts the supported surface Sf. After the release paper (not shown) of the double-sided tape 30 is removed, the polishing pad 1 is attached to the polishing apparatus by sticking the double-sided tape 30 on the polishing surface plate of the polishing apparatus.

  The material of the elastic resin sheet 2 is preferably a polyurethane resin formed by a so-called wet film forming method from the viewpoint of more effectively and reliably achieving the object of the invention, but if it is an elastic material that is hydrophobic and soluble in a polar solvent, There is no particular limitation.

  Innumerable bubbles are formed inside the elastic resin sheet 2. The bubbles are formed in various sizes, and are in a state of communicating in a mesh shape. In the following description, among these bubbles, they are elongated bubbles formed so as to extend from the supported surface Sf toward the polishing surface Sp, and are formed so as to cover substantially the entire thickness of the elastic resin sheet 2. Focusing only on relatively large bubbles, these will be expressed as “bubble 10” in particular. A large number of such bubbles 10 are formed inside the elastic resin sheet 2, but for convenience of illustration and description, only a part of them is drawn in FIGS. 1 and 2.

  As shown in FIG. 1, each of the bubbles 10 includes a large-diameter portion 11 formed at a relatively large diameter in the pad base material 20 side (supported surface Sf side), and a polishing surface from the large-diameter portion 11. And an inclined portion 12 extending elongated toward Sp. The extending direction of the inclined portion 12 is not perpendicular to the polishing surface Sp, but is inclined to the polishing surface Sp.

  The bubble 10 has an opening 13 formed at the tip on the polishing surface Sp side. On the other hand, no opening is formed at the tip on the supported surface Sf side (in addition, since a minute bubble exists between the bubble 10 and the supported surface Sf, the bubble is passed through these minute bubbles. 10 may communicate with the supported surface Sf side).

  Since the bubble 10 has such a shape, when polishing with the polishing pad 1, it functions as a pump for circulating and supplying slurry between the polishing surface Sp and the object to be polished. Demonstrate. That is, when an object to be polished is pressed against a part of the polishing surface Sp of the rotating polishing pad 1, the elastic resin sheet 2 is deformed to cause the bubbles 10 in the part to contract and the slurry stored inside. Is discharged toward the object to be polished. Further, when the object to be polished moves (relatively) to another part, the bubbles 10 expand and return to the original size, and in the process, the slurry is stored inside. As described above, the bubbles 10 repeatedly discharge and store the slurry (pumping is performed), whereby a predetermined amount of slurry is always circulated and supplied between the polishing surface Sp of the polishing pad 1 and the object to be polished. As a result, clogging of the polishing pad 1 is prevented, the polishing rate is improved, and polishing with excellent surface quality is performed.

  As shown in FIG. 2, when the elastic resin sheet 2 is viewed along a direction perpendicular to the polishing surface Sp, the direction in which each inclined portion 12 extends toward the polishing surface Sp (in FIG. 2, indicated by an arrow AR1). The angle (first angle) formed between the direction indicated) and the circumferential direction of the elastic resin sheet 2 at the position of the inclined portion 12 (the direction indicated by the arrow AR2 in FIG. 2) is all about 180 degrees. . The circumferential direction of the elastic resin sheet 2 is a direction in which the elastic resin sheet 2 that forms a circle in plan view rotates along the circumference. In the present embodiment, it can also be said that the elastic resin sheet 2 rotates relative to the object to be polished. In FIG. 2, the clockwise direction is the circumferential direction with the center of the elastic resin sheet 2 that is circular in a top view as the rotation axis.

  The polishing pad 1 according to this embodiment has the following effects because the first angle is substantially the same (about 180 degrees) for all the bubbles 10. When the elastic resin sheet 2 rotates relative to the object to be polished, the object to be polished approaches the bubble 10 from the large diameter portion 11 side. That is, the object to be polished moves relatively in the direction opposite to the arrow AR2, and approaches the bubble 10.

  Since the elastic resin sheet 2 is deformed when the object to be polished is pressed, when the object to be polished approaches as described above, the large-diameter portion 11 of the bubbles 10 is first compressed and its volume decreases. At this time, the opening 13 of the bubble 10 has not been blocked by the object to be polished. Therefore, the slurry stored in the bubbles 10 is smoothly discharged through the opening 13 and supplied between the polishing surface Sp and the object to be polished.

  Thereafter, the object to be polished further moves relative to close the opening 13. Immediately thereafter, the opening 13 is opened by the relative movement of the object to be polished, and the bubble 10 returns to its original size. At that time, the slurry existing between the polishing surface Sp and the object to be polished is sucked and stored again in the bubbles 10.

  As described above, since there is a time difference between the timing at which the volume of the bubble 10 starts to decrease and the timing at which the opening 13 is blocked, the slurry is smoothly discharged and stored. The time difference is caused by the inclined portion 12 of the bubble 10 being inclined with respect to the polishing surface Sp.

  Furthermore, in this embodiment, since the first angle is substantially the same (about 180 degrees) for all the bubbles 10, the time difference is also substantially the same for all the bubbles 10. As a result, the function of storing and discharging the slurry is exhibited substantially uniformly in each of the bubbles 10, so that occurrence of polishing unevenness can be suppressed.

  As shown in FIG. 2, six cutting grooves 80 are formed on the polishing surface Sp of the elastic resin sheet 2 so as to follow the radius of the elastic resin sheet 2. The cutting groove 80 is a groove having a V-shaped cross section formed so as to cut a part of the polishing surface Sp. In the polishing pad 1 according to the present embodiment, the circulation of the slurry between the object to be polished and the polishing surface Sp is improved by forming such a cutting groove 80.

  Here, when viewed along the direction perpendicular to the polishing surface Sp as shown in FIG. 2, in the region of the elastic resin sheet 2 in the vicinity of each cutting groove 80, the inclination direction of the bubbles 10 included in the region is as follows. Is substantially the same for all the bubbles 10. That is, in the region, the direction in which the inclined portion 12 of each bubble 10 extends toward the polishing surface Sp (the direction indicated by the arrow AR1: the first direction) is the direction in which the cutting groove 80 passing through the region extends (elasticity). The resin sheet 2 is substantially perpendicular to the radial direction (second direction).

  Next, a specific shape of the cutting groove 80 will be described with reference to FIG. FIG. 3B schematically shows a part of a cross section when the elastic resin sheet 2 is cut perpendicularly to the direction in which the cutting groove 80 extends (second direction). As shown in FIG. 3B, the cutting groove 80 is partitioned by the first inclined surface Sc1 and the second inclined surface Sc2.

  The first inclined surface Sc1 is a front side along the first direction (the direction indicated by the arrow AR1 in FIG. 2 and the rightward direction in FIG. 3) of the two inclined surfaces that define the cutting groove 80. It is an inclined surface located on the side. An angle formed by the first inclined surface Sc1 with respect to the polishing surface Sp is an angle θ1.

  The second inclined surface Sc <b> 2 is an inclined surface located on the back side along the first direction among the two inclined surfaces that define the cutting groove 80. The angle formed by the second inclined surface Sc2 with respect to the polishing surface Sp is an angle θ2.

  The angle formed by the inclined portion 12 of the bubble 10 with respect to the polishing surface Sp is substantially the same angle θ3 for each bubble 10. In the present embodiment, as shown in FIG. 3B, the cutting groove 80 is formed so that the angle θ2 is smaller than the angle θ3. The effect of forming the shape of the cutting groove 80 in this way will be described below.

  FIG. 3A schematically shows a cross section of the elastic resin sheet 2 as in FIG. 3B, but unlike the present embodiment, the cutting is performed so that the angle θ2 is larger than the angle θ3. The cross section when the groove 80 is formed is shown. As shown in FIG. 3A, when the angle θ2 is larger than the angle θ3, the cutting groove 80 can be in a state in which a part of the bubble 10 is cut out at the bottom (portion farthest from the polishing surface Sp). High nature. At this time, a communication hole HL communicating with the bubble 10 is formed in a part of the second inclined surface Sc2 that defines the cutting groove 80.

  The communication hole HL is formed at a position relatively far from the polishing surface Sp in the bubble 10. As a result, the portion (strength reduction portion WP) from the communication hole HL to the polishing surface Sp in the elastic resin sheet 2 becomes a thin plate supported only in the vicinity of the polishing surface Sp, and the strength is significantly reduced.

  Therefore, when performing the polishing process, there is a high possibility that the strength-decreasing portion WP protrudes from the polishing surface Sp or is scraped off by receiving a force from the polishing object. If a part of the elastic resin sheet 2 is damaged in this manner, the object to be polished cannot be uniformly polished, and so-called uneven polishing or the like occurs.

  In contrast, the cutting groove 80 according to the present embodiment is formed such that the angle θ2 is smaller than the angle θ3 as shown in FIG. In this case, a portion of the elastic resin sheet 2 that is removed when forming the cutting groove includes a portion of the bubble 10 that is closest to the polishing surface Sp (near the opening 13). In other words, the bubble 10 in the vicinity of the cutting groove is in a state where a portion closest to the polishing surface Sp is cut out. As a result, the communication hole HL is also formed in FIG. 3B, but no portion of the elastic resin sheet 2 whose strength is reduced is formed between the communication hole HL and the polishing surface Sp. As a result, it can be said that the portion (strength reduced portion WP) that is damaged by receiving the force from the object to be polished is hardly formed at least in the vicinity of the polishing surface Sp.

  As described above, in the polishing pad 1 according to the present embodiment, the cutting groove 80 is formed on the polishing surface Sp to improve the circulation of the slurry and improve the polishing rate, while the cutting groove 80 is formed. The durability deterioration of the elastic resin sheet 2 is suppressed.

  In the polishing pad 1 according to the present embodiment, the angles formed by the first direction and the second direction are the same (substantially vertical) as described above in all the cutting grooves 80 formed on the polishing surface Sp. Yes. However, the embodiment of the present invention is not limited to the above aspect. For example, a cutting groove in which the angle formed by the first direction and the second direction is different from the angle in the other cutting groove 80 may be additionally formed on a part of the polishing surface Sp.

  Further, a cutting groove having a shape other than a V-shaped cross section may be additionally formed on a part of the polishing surface Sp. Furthermore, a groove formed by a method other than cutting may be additionally formed on a part of the polishing surface Sp.

  Next, the manufacturing process of the polishing pad 1 will be described with reference to FIGS. FIG. 4 is a process diagram showing the outline of the manufacturing process of the polishing pad 1, and FIG. 5 is a schematic diagram for explaining the solidification process among the manufacturing processes. Hereinafter, description will be made in the order of steps shown in FIG.

  First, the preparation step (S1) is a step of preparing a resin solution in which a polyurethane resin is dissolved. Specifically, the polyurethane resin is dissolved by mixing a polyurethane resin, a water-miscible organic solvent capable of dissolving the polyurethane resin, and an additive.

  As the organic solvent, N, N-dimethylformamide (hereinafter abbreviated as DMF) was used. The polyurethane resin is selected from polyurethane resins such as polyester, polyether and polycarbonate. It is desirable to select and use a polyurethane resin having a 100% modulus of 4 to 50 MPa. Use of a polyurethane resin having a 100% modulus lower than 4 MPa is not preferable because the hardness of the obtained sheet is too low and the polishing flatness is significantly impaired. In addition, it is not preferable to use a resin having a 100% modulus higher than 50 MPa because the flexibility of the obtained sheet is too low and it is easy to cause polishing scratches. The resin concentration and viscosity of the resin solution in which the polyurethane resin is dissolved are not particularly limited, but may be appropriately selected depending on the coater to be used and the coagulation conditions so that it can be uniformly applied and uniformly coagulated.

  In view of the formation of relatively large bubbles 10 in the elastic resin sheet 2, the resin solution is prepared by dissolving polyurethane resin in DMF at 10 to 50% by weight, preferably 15 to 30% by weight. Is in the range of 3 to 20 Pa · s, preferably in the range of 3 to 10 Pa · s when measured at 25 ° C. using a B-type rotational viscometer.

  The additive is added to control the size and number of bubbles 10 formed in the elastic resin sheet 2, and a pigment such as carbon black, a hydrophilic additive, a hydrophobic additive, or the like is used. Can do.

  The resin solution obtained as described above contains a large number of bubbles immediately after mixing. Therefore, it is desirable to perform vacuum defoaming before performing the next coating step.

  The subsequent application step (S2) is a step of applying the resin solution obtained in the preparation step to one surface of the film forming substrate 40 to form the solidified layer 15. The coagulated layer 15 is a portion that will later become the elastic resin sheet 2. The film forming substrate 40 is a base for forming the elastic resin sheet 2 by a wet film forming method, and in this embodiment, a PET film having a circular shape in plan view is used. The shape of the film forming substrate 40 in plan view is the same as the shape of the pad substrate 20.

  In the coating step, the resin solution is coated substantially uniformly on the film forming substrate 40 by a coating device such as a knife coater. In the present embodiment, the knife coater was adjusted so that the coating thickness of the resin solution (the thickness of the solidified layer 15) was in the range of 0.8 to 1.2 mm.

  The subsequent solidification step (S3) is a step of forming the elastic resin sheet 2 by bringing the solidified liquid LQ into contact with the surface of the solidified layer 15 formed in the coating step and solidifying the solidified layer 15. The coagulation liquid LQ is a liquid that is a poorer solvent for the polyurethane resin than the solvent (DMF) in the resin solution, and water is used in this embodiment. In order to adjust the coagulation rate (regeneration rate) of the polyurethane resin, a solution obtained by adding an organic solvent such as DMF to water may be used as the coagulation liquid LQ. The temperature of the coagulation liquid LQ was controlled to be 15 to 40 ° C.

  When the solidified liquid LQ is brought into contact with the surface of the solidified layer 15 (resin solution), DMF at the interface between the solidified layer 15 and the solidified liquid LQ diffuses toward the solidified liquid LQ, and the resin in the portion is regenerated. As a result, a film is formed. As a result, a skin layer having a microporous structure in which many fine bubbles are formed is formed in the range of several μm in thickness from the surface of the layer to be solidified 15.

  Thereafter, DMF diffuses relatively slowly through the skin layer from the layer to be solidified 15 toward the solidified liquid LQ, and at the same time, the solidified liquid LQ permeates into the layer to be solidified 15 through the skin layer. That is, DMF and water are replaced. Accordingly, in the solidified layer 15, resin aggregation and regeneration proceed from the vicinity of the skin layer toward the film forming substrate 40 side. The aggregation speed (regeneration speed) is fast near the skin layer, and slows away from the skin layer.

  As the resin agglomerates, bubbles filled with the coagulating liquid LQ are formed inside the layer 15 to be coagulated, but as a result of the aggregation proceeding as described above, the bubbles are formed from the film forming substrate 40 side. It is formed to be elongated so as to extend toward the skin layer side. Further, due to the difference in the aggregation rate, the bubbles have a large diameter on the film forming substrate 40 side and are elongated near the skin layer. Through the above process, the elongated bubbles 10 having the large diameter part 11 and the inclined part 12 as described with reference to FIG. 1 are formed.

  With reference to FIG. 5, the solidification process will be described more specifically. FIG. 5 schematically shows a state during the solidification process. As shown in FIG. 5, the film-forming substrate 40 having the solidified layer 15 formed on one surface side is held by a holding device (not shown) in a state where the normal direction of the surface is horizontal. Yes. The holding device has a rotation mechanism, and the film-forming substrate 40 rotates at a constant speed along the circumference of the surface on which the layer to be solidified 15 is formed (in the direction indicated by the arrow AR3). .

  In this state, the coagulating liquid LQ is discharged from the coagulating liquid supply apparatus 50, and the discharged coagulating liquid LQ is brought into contact with the surface of the solidified layer 15. The coagulating liquid supply apparatus 50 is a container in which a slit 51 having a length substantially the same as the radius of the film forming substrate 40 is formed, and an apparatus for discharging the coagulating liquid LQ stored inside from the slit 51 to the outside. It is. The coagulating liquid supply apparatus 50 includes a pressurizing apparatus (not shown), and the amount of coagulating liquid LQ discharged from the slit 51 (discharge amount per unit time) is controlled by the pressurizing apparatus.

  As shown in FIG. 5, the coagulating liquid supply device 50 is configured such that one end of the slit 51 is disposed at the center position of the film forming substrate 40 and the other end is disposed at the outer peripheral end of the film forming substrate 40. In this state, 51 is brought close to the surface of the layer 15 to be solidified. In this state, the coagulation liquid LQ is discharged from the slit 51. The amount of the coagulating liquid LQ discharged per unit time is such that the entire portion of the surface of the layer to be coagulated 15 facing the slit 51 is always in contact with the coagulating liquid LQ. Amount.

  The coagulating liquid supply device 50 is stationary, and the film forming substrate 40 (coagulated layer 15) is rotated as described above. For this reason, the position of the surface of the layer to be solidified 15 that is in contact with the coagulating liquid LQ moves along the circumferential direction (direction opposite to the arrow AR3) of the layer to be solidified 15 with the passage of time.

  Of the surface of the layer to be solidified 15, the portion near and above the slit 51 in FIG. 5 is a portion that will come into contact with the coagulation liquid LQ as the film forming substrate 40 rotates. In this portion, resin aggregation starts to proceed toward the contact portion with the coagulation liquid LQ, that is, downward, and thereafter contact with the coagulation liquid LQ. As a result, in the portion of the solidified layer 15 that has passed through the slit 51, the bubbles 10 are formed so as to extend from the film forming substrate 40 side toward the surface of the solidified layer 15. In addition, each of the bubbles 10 is in a state where the surface side portion is inclined along the rotation direction (arrow AR3) of the film forming substrate 40. That is, the inclined portion 12 as described with reference to FIGS. 1 and 2 is formed.

  After the discharge of the coagulation liquid LQ from the slit 51 is started, when the rotation angle of the film formation substrate 40 becomes 360 degrees or more and the skin layer is formed on the entire surface of the layer to be solidified, the film formation substrate 40 is formed. And the discharge of the coagulating liquid LQ from the slit 51 are stopped. At this time, the bubbles 10 as described above are formed in the entire layer to be solidified 15, and the arrangement thereof is as shown in FIG. At this time, from the viewpoint of preventing the coagulation liquid from dripping, a thickener (water-soluble polysaccharide, starch, carboxymethyl cellulose, alginic acid, etc.) may be added to the coagulation liquid.

  The thickness and compression rate of the elastic resin sheet 2 at the time when the coagulation process is completed vary depending on the rotation speed of the film forming substrate 40. In the solidification step, the film-forming substrate 40 is rotated at a rotational speed determined in advance by experiments or the like so that the thickness is in the range of 500 to 700 μm and the compression rate is in the range of 7 to 20%. It is desirable. If the thickness and compression rate of the elastic resin sheet 2 are in the above ranges, the compression characteristics of the elastic resin sheet 2 are appropriate, and the polishing rate is improved. Further, the rotational speed is further adjusted so that the thickness and compression rate of the elastic resin sheet 2 are in the above ranges, and the angle θ3 formed by the inclined portion 12 of the bubble 10 with respect to the polishing surface Sp is in the range of 10 to 65 degrees. It is desirable to make an adjustment.

  The subsequent washing / drying step (S4) is a step in which the elastic resin sheet 2 formed by the coagulation step is washed to remove DMF and then dried. The cleaning is performed by preparing a cleaning tank in which a cleaning liquid (water) is stored and immersing and pressing the entire elastic resin sheet 2 and the film forming substrate 40 in the cleaning liquid a plurality of times. Drying is performed using a dryer that is heated and dried with hot air.

  In the subsequent grinding process (S5), the surface side of the elastic resin sheet 2 (the side opposite to the film forming substrate 40) is ground to remove irregularities on the surface of the skin layer to form a flat polished surface Sp. It is a process. By this grinding process, the thickness variation of the elastic resin sheet 2 is eliminated, and at the same time, an opening 13 is formed at the tip of each bubble 10.

  The subsequent cutting groove forming step (S6) is a step of forming the cutting groove 80 by cutting a part of the polishing surface Sp. In the cutting groove forming step, a normal processing machine capable of cutting the elastic resin sheet 2 is used.

  In the cutting groove forming step, the cutting groove 80 is formed so that the angle θ2 formed by the second inclined surface Sc2 with respect to the polishing surface Sp is smaller than the angle θ3 and the angle θ2 is in the range of 65 to 85 degrees. It is desirable. Further, the angle θ1 formed by the first inclined surface Sc1 with respect to the polishing surface Sp may be in the range of 0 to 80 degrees, but in the present embodiment, when the elastic resin sheet 2 is viewed from above, the elastic resin sheet The angle θ1 was adjusted so that the ratio of the area of the cutting groove 80 to the entire polishing surface Sp of 2 was in the range of 3 to 30%. If the area ratio of the cutting groove 80 is in the above range, the polishing efficiency can be maintained because the size of the polishing surface Sp can be secured to some extent while maintaining the slurry circulation appropriately.

  In the subsequent bonding step (S7), after removing the film formation substrate 40 from the elastic resin sheet 2, an adhesive is applied to the supported surface Sf of the elastic resin sheet 2 (the surface in contact with the film formation substrate 40). It is the process of bonding the pad base material 20 through. A double-sided tape 30 from which one release paper is removed is attached to the surface of the pad base 20 opposite to the elastic resin sheet 2. As already described, the double-sided tape 30 is for attaching the polishing pad 1 to the polishing apparatus.

  Next, the configuration of the polishing pad 1a according to the second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a view showing the arrangement of the bubbles 10a and the cutting grooves 80a formed in the elastic resin sheet 2a of the polishing pad 1a. As shown in FIG. 6, the polishing pad 1a is different from the polishing pad 1 only in the arrangement of the bubbles 10a and the cutting grooves 80a formed in the elastic resin sheet 2a, and is the same as the polishing pad 1 in the other respects. . In the following description, only the difference will be described, and detailed description of points common to the polishing pad 1 will be omitted. In the following description, a portion of the polishing pad 1a corresponding to the configuration of the polishing pad 1 (for example, the pad base material 20) is described with a letter “a” such as “pad base material 20a”.

  Each of the bubbles 10a includes a large diameter portion 11a formed with a relatively large diameter at the pad base material 20a side (supported surface Sfa side), and an inclined portion 12a elongated from the large diameter portion 11a toward the polishing surface Spa. And have. The direction in which the inclined portion 12a extends is not perpendicular to the polishing surface Spa, but is inclined to the polishing surface Spa. This is the same as the bubble 10 of the polishing pad 1.

  On the other hand, as shown in FIG. 6, when the elastic resin sheet 2a is viewed along the direction perpendicular to the polishing surface Spa, the direction in which each inclined portion 12a extends toward the polishing surface Spa (indicated by the arrow in FIG. 6). The angle (first angle) formed between the direction indicated by AR4 and the circumferential direction of the elastic resin sheet 2a at the position of the inclined portion 12a (the direction indicated by the arrow AR5 in FIG. 6) is about 90 degrees. ing. This is different from the polishing pad 1 in which the first angles are all 180 degrees.

  In the polishing pad 1a according to the present embodiment, the first angle is substantially the same (about 90 degrees) for all the bubbles 10a. As a result, the function of the bubbles 10a storing and discharging the slurry (for the same reason as that of the polishing pad 1) is exerted substantially uniformly in each of the bubbles 10a, so that it is possible to suppress the occurrence of polishing unevenness. It has become.

  Furthermore, in this embodiment, as shown in FIG. 6, all the inclined portions 12a are inclined so as to extend toward the center of the polishing surface Spa. For this reason, the slurry discharged from the opening 13a is directed toward the center of the polishing surface Spa. As a result, the retention performance of the slurry between the object to be polished and the polishing surface Spa can be improved.

  As shown in FIG. 6, two cutting grooves 80a are formed concentrically on the polishing surface Spa of the elastic resin sheet 2a along the circumferential direction of the elastic resin sheet 2a. The cutting groove 80a is a groove having a V-shaped cross section formed so as to cut a part of the polishing surface Spa. In the polishing pad 1a according to the present embodiment, the circulation of the slurry between the object to be polished and the polishing surface Sp is improved by forming such a cutting groove 80a.

  Here, when viewed along a direction perpendicular to the polishing surface Spa as shown in FIG. 6, in the region near the arbitrary radius of the elastic resin sheet 2 a, the inclination direction of the bubbles 10 a included in the region is all the same. The bubbles 10a are substantially the same. That is, in the region, the direction in which the inclined portion 12a of each bubble 10a extends toward the polishing surface Spa (the direction indicated by the arrow AR4: the first direction) is the direction in which the cutting groove 80a passing through the region extends (elasticity). It is substantially perpendicular to the circumferential direction (second direction) of the resin sheet 2.

  The specific cross-sectional shape of the cutting groove 80a is the same as the cross-sectional shape of the cutting groove 80 described with reference to FIG. That is, the cutting groove 80a is partitioned by a first inclined surface Sc1a (not shown) and a second inclined surface Sc2a (not shown).

  The first inclined surface Sc1a is an inclined surface located on the near side along the first direction (the direction indicated by the arrow AR4 in FIG. 6) among the two inclined surfaces that define the cutting groove 80a. An angle formed by the first inclined surface Sc1a with respect to the polishing surface Spa is an angle θ1a.

  2nd inclined surface Sc2a is an inclined surface located in the back | inner side along a 1st direction among the two inclined surfaces which divide the cutting groove 80a. An angle formed by the second inclined surface Sc2a with respect to the polishing surface Spa is an angle θ2a.

  The angle formed by the inclined portion 12a of the bubble 10a with respect to the polishing surface Spa is substantially the same angle θ3a for each bubble 10a. In this embodiment, similarly to the case of the cutting groove 80 shown in FIG. 3B, the cutting groove 80a is formed so that the angle θ2a is smaller than the angle θ3a. Since the effect of forming the shape of the cutting groove 80a in this way is the same as that of the cutting groove 80, description thereof is omitted.

  Then, the manufacturing process of the polishing pad 1a is demonstrated. The polishing pad 1a is manufactured through substantially the same process as the manufacturing process of the polishing pad 1 shown in FIG. 4, but the manufacturing process is the manufacturing of the polishing pad 1 only in the aspect of the solidification process and the cutting direction of the cutting process. It is different from the process. In the following, only the solidification step of the manufacturing process of the polishing pad 1a will be described, and the other steps are almost the same as those already described, and the description thereof will be omitted.

  This will be described with reference to FIGS. These are schematic diagrams for explaining the solidification step in the manufacturing process of the polishing pad 1a. First, as shown in FIG. 7A, a film forming substrate 40a having a solidified layer 15a formed on one surface and a stamping die 60 are prepared. The pressing die 60 is a disk-like member having the same shape as the film forming substrate 40a when viewed from above, and a surface 61 on one side thereof protrudes so as to form a part of a spherical surface. The stamping die 60 may be any material that is harder than the film forming substrate 40a, and for example, a metallic one can be used.

  Thereafter, as shown in FIG. 7B, the surface 61 of the pressing die 60 is pressed against the surface of the film forming substrate 40a on which the solidified layer 15a is not formed (hereinafter referred to as the back surface 41a). Then, the film forming substrate 40a is deformed into a spherical shape. At this time, substantially the entire back surface 41a is in contact with the surface 61, and the pressing die 60 and the film forming substrate 40a are fixed by a fixing jig (not shown) in this state. As a result, the layer 15a to be solidified is deformed along the surface 61, and the central portion thereof protrudes toward the side opposite to the film forming substrate 40a side.

  Subsequently, the layer 15a to be solidified is immersed in the coagulation bath 70 in which the coagulation liquid LQ is stored to be coagulated. At this time, as shown in FIG. 8, the film forming substrate 40a integrated with the die 60 has an outer peripheral portion substantially parallel to the liquid surface of the coagulating liquid LQ and coagulating the surface of the layer 15a to be coagulated. The liquid LQ faces the liquid surface. While maintaining this state, the film formation substrate 40a is slowly lowered, and the layer 15a to be solidified is immersed in the coagulation liquid LQ.

  Since the central portion of the layer to be solidified 15a protrudes downward, the surface of the layer to be solidified 15a first comes into contact with the solidified liquid LQ at the center of the circle when viewed from above. Thereafter, as the film forming substrate 40a descends, the position of the surface of the solidified layer 15a that is in contact with the solidified liquid LQ moves while expanding in a circle from the center of the solidified layer 15a toward the outer periphery. To do. That is, it moves along the radial direction of the layer to be solidified 15a with time.

  At this time, in the surface of the solidified layer 15a, the portion near and above the liquid surface of the coagulating liquid LQ is a part that will come into contact with the coagulating liquid LQ as the film forming substrate 40a descends. In the portion, the aggregation of the resin starts to proceed toward the contact portion with the coagulation liquid LQ, that is, toward the center of the layer to be solidified 15a. Thereafter, as the film forming substrate 40a is further lowered, the portion comes into contact with the coagulating liquid LQ. As a result, in the portion of the solidified layer 15a that has passed the liquid level of the solidified liquid LQ, the bubbles 10a are formed so as to extend from the film forming substrate 40a side toward the surface of the solidified layer 15a. ing. In addition, each of the bubbles 10a is in a state where the surface side portion is inclined along the direction toward the center of the film forming substrate 40a. That is, the inclined portion 12a as described with reference to FIG. 6 is formed.

  When the entire layer to be solidified 15a is immersed in the coagulating liquid LQ, the lowering of the film forming substrate 40 is stopped. At this time, the bubbles 10a as described above are formed in the entire solidified layer 15a, and the arrangement thereof is as shown in FIG.

  As a result, in the elastic resin sheet 2a formed through such a solidification step, the first angles in all the bubbles 10a are all about 90 degrees as described with reference to FIG.

  Next, the configuration of the polishing pad 1b according to the third embodiment of the present invention will be described with reference to FIG. FIG. 9 is a diagram showing the arrangement of the bubbles 10b and the cutting grooves 80b formed in the elastic resin sheet 2b of the polishing pad 1b. As shown in FIG. 9, the polishing pad 1b is different from the polishing pad 1 in the arrangement of the bubbles 10b and the cutting grooves 80b formed in the elastic resin sheet 2b. Further, the polishing pad 1 is also different in that the elastic resin sheet 2b is divided into a plurality (four). Others are the same as those of the polishing pad 1. In the following description, only the difference will be described, and detailed description of points common to the polishing pad 1 will be omitted. In the following description, a portion of the polishing pad 1b corresponding to the configuration of the polishing pad 1 (for example, the pad base material 20) is denoted by a letter “b” such as “pad base material 20b”.

  The elastic resin sheet 2b of the polishing pad 1b is divided into four fan-shaped resin sheets (2ba, 2bb, 2bc, 2bd) formed in a fan shape with a central angle of 90 degrees. It is circular in shape.

  Each fan-shaped resin sheet 2ba, 2bb, 2bc, 2bd is formed by cutting out an elastic resin sheet formed by a wet film-forming method into a fan shape. Specifically, in the solidification step of the wet film formation method, the film formation substrate 40b to which the resin solution has been applied (the layer to be solidified 15b is formed) is placed horizontally on the coagulation liquid LQ stored in the coagulation bath 70. While maintaining a state perpendicular to the liquid level, it is slowly lowered and immersed. In the elastic resin sheet formed in this way, the inclination directions of all the bubbles 10b formed therein are substantially the same.

  When cutting out the fan-shaped resin sheet 2ba and the like from such an elastic resin sheet, the direction in which the inclined portion 12b of the bubble 10b extends toward the polishing surface Spb (the direction indicated by the arrow AR6: the first direction) is the elastic resin sheet. It is cut out so as to be in the direction toward the center of 2b. In other words, it is cut out so that the first direction forms an angle of 45 degrees with respect to the fan-shaped radius.

  As a result, when viewed in a direction perpendicular to the polishing surface Spb, the polishing surface Spb of the elastic resin sheet 2b is divided into four regions each forming a fan shape, and the bubbles 10b formed in each region are inclined. The direction (first direction) in which the portion 12b extends toward the polishing surface Spb is substantially the same.

  On the polishing surface Spb in each of the above regions, two cutting grooves 80b are formed along a second direction substantially perpendicular to the first direction in the region. The cutting groove 80b is a groove having a V-shaped cross section formed so as to cut a part of the polishing surface Spb. In the polishing pad 1b according to the present embodiment, the circulation of the slurry between the object to be polished and the polishing surface Spb is improved by forming such a cutting groove 80b.

  The specific cross-sectional shape of the cutting groove 80b is the same as the cross-sectional shape of the cutting groove 80 described with reference to FIG. That is, the cutting groove 80b is partitioned by a first inclined surface Sc1b (not shown) and a second inclined surface Sc2b (not shown).

  The first inclined surface Sc1b is an inclined surface located on the near side along the first direction (the direction indicated by the arrow AR6 in FIG. 9) among the two inclined surfaces that define the cutting groove 80b. An angle formed by the first inclined surface Sc1b with respect to the polishing surface Spb is an angle θ1b.

  2nd inclined surface Sc2b is an inclined surface located in the back | inner side along a 1st direction among the two inclined surfaces which divide the cutting groove 80b. An angle formed by the second inclined surface Sc2b with respect to the polishing surface Spb is an angle θ2b.

  The angle formed by the inclined portion 12b of the bubble 10b with respect to the polishing surface Spb is substantially the same angle θ3b for each bubble 10b. In this embodiment, similarly to the case of the cutting groove 80 shown in FIG. 3B, the cutting groove 80b is formed so that the angle θ2b is smaller than the angle θ3b. Since the effect of forming the shape of the cutting groove 80b in this way is the same as that of the cutting groove 80, description thereof is omitted.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

1, 1a, 1b: Polishing pad 2, 2a, 2b: Elastic resin sheet 2ba, 2bb, 2bc, 2bd: Fan-shaped resin sheet 10, 10a, 10b: Air bubbles 11, 11a, 11b: Large diameter portions 12, 12a, 12b : Inclined part 13, 13a, 13b: Opening 15, 15a, 15b: Coagulated layer 20, 20a, 20b: Pad base material 30: Double-sided tape 40, 40a, 40b: Film forming base material 41a: Back surface 50: Coagulating liquid supply Apparatus 51: Slit 60: Stamping die 61: Surface 70: Coagulation bath LQ: Coagulating liquid 80, 80a, 80b: Cutting groove HL: Communication hole Sc1, Sc1a, Sc1b: First inclined surface Sc2, Sc2a, Sc2b: Second inclined surface Sf, Sfa, Sfb: Supported surface Sp, Spa, Spb: Polished surface WP: Strength reduction part

Claims (3)

A polishing pad having a surface on one side of the elastic resin sheet as a polishing surface and a surface on the other side as a supported surface,
A plurality of elongated bubbles extending from the supported surface toward the polishing surface are formed inside the elastic resin sheet,
Each of the bubbles has an inclined portion formed so as to be inclined with respect to the polishing surface at least in the vicinity of the polishing surface;
When viewed along a direction perpendicular to the polishing surface, the plurality of bubbles formed in at least a part of the first region of the elastic resin sheet is a direction in which the inclined portion extends toward the polishing surface. Are in substantially the same first direction,
A cutting groove having a V-shaped cross section is formed on the polished surface in the first region along a second direction substantially perpendicular to the first direction,
The cutting groove is partitioned by a first inclined surface located on the near side along the first direction and a second inclined surface located on the back side along the first direction,
The polishing pad, wherein an angle formed by the second inclined surface with respect to the polishing surface is smaller than an angle formed by the inclined portion with respect to the polishing surface. The elastic resin sheet has a circular shape in plan view,
When viewed along a direction perpendicular to the polishing surface, each of the bubbles is formed such that the direction in which the inclined portion extends toward the polishing surface substantially coincides with the circumferential direction of the elastic resin sheet. The polishing pad according to claim 1, wherein the polishing pad is provided. The elastic resin sheet has a circular shape in plan view,
When viewed along a direction perpendicular to the polishing surface, each of the bubbles has a direction in which the inclined portion extends toward the polishing surface substantially coincides with a direction toward the center of the elastic resin sheet. The polishing pad according to claim 1, wherein the polishing pad is formed.

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