Polishing pad and method for manufacturing the same, and method for manufacturing polished products

Abstract

To provide a manufacturing method for a polishing pad that is excellent in surface quality and in polishing rate.SOLUTION: A manufacturing method for a polishing pad comprises: a mixing step in which raw materials are continuously supplied to a continuous polymerizer, then the raw materials are mixed, with a rotor, in a mixing chamber of the continuous polymerizer and curable compositions are continuously ejected from the mixing chamber; a flowing-in step in which the ejected curable compositions are flowed into a forming mold having a plurality of concave parts; and a curing step in which the curable compositions flowed into the forming mold are cured to obtain a polishing layer, where the rotor has a stirring blade oriented in the same direction as a rotating direction thereof or a stirring blade oriented in a direction crossing the rotating direction.SELECTED DRAWING: None

Description

Technical Field

[0005] ,

[0001] The present invention relates to a polishing pad, a method for manufacturing the same, and a method for manufacturing a polished product.

Background Art

[0002] A polishing pad is used for polishing optical materials, semiconductor devices, glass substrates for hard disks, etc. Also, a polishing pad is used when polishing a device in which an oxide layer, a metal layer, etc. are formed on a semiconductor wafer. As a conventional polishing pad, one having a polishing layer formed of a synthetic resin such as polyurethane and having a concentric or lattice-shaped groove shape on the surface of the polishing layer has been used. Such a groove shape can contribute to the supply and discharge of the polishing slurry during polishing.

[0003] In recent years, due to the miniaturization of wiring in semiconductor devices, etc., more precise polishing has been required, and a polishing pad with even finer irregularities on the polishing surface has been demanded. For example, Patent Document 1 discloses a method of obtaining a polishing pad by subjecting the surface to microfabrication by a micro molding method using a master mold made of metal. In a method using such a molding method, a fine uneven pattern can be formed by using a mold having a fine uneven pattern.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, molds are expensive, and if the pattern of raised and recessed areas needs to be changed, an expensive new mold must be manufactured. Alternatively, a method of forming the raised and recessed pattern on the substrate using screen printing can be considered. However, screen printing makes it difficult to form raised and recessed patterns with significant height, and it is also difficult to obtain fine raised and recessed patterns.

[0006] Incidentally, the polishing surface of the polishing pad wears down during the polishing process, and its properties can change over time. As the polishing surface wears down, the contact area between the workpiece and the polishing pad changes, causing the surface pressure at each polishing point to change over time. The inventors have investigated and found that such changes in surface pressure at polishing points affect the surface quality of the workpiece.

[0007] This invention has been made in view of the above-mentioned problems, and aims to provide a method for manufacturing polishing pads that have excellent surface quality and polishing rate. [Means for solving the problem]

[0008] In other words, the present invention is as follows. [1] A mixing step in which raw materials are continuously supplied to a polymerizer, the raw materials are mixed by a rotor in the mixing chamber of the continuous polymerizer, and a curable composition is continuously discharged from the mixing chamber, A pouring step in which the discharged curable composition is poured into a mold having a plurality of recesses, The system comprises a curing step of curing the curable composition poured into the mold to obtain a polished layer, The rotor is a rotor having stirring blades oriented in the same direction as the direction of rotation or stirring blades oriented in a direction intersecting the direction of rotation. A method for manufacturing polishing pads. [2] The aforementioned mold is a mold made of silicone. A method for manufacturing the polishing pad described in [1]. [3] The aforementioned raw materials include polyisocyanate and polyol. A method for manufacturing an abrasive pad as described in [1] or [2]. [4] The volume of the mixing chamber is smaller than the total amount of the curable composition poured into one of the molds. The mixing step to the infusion step is performed continuously. A method for manufacturing an abrasive pad as described in any one of items [1] to [3]. [5] In the pouring process, the discharged curable composition is poured into the center of the mold. A method for manufacturing an abrasive pad as described in any one of items [1] to [4]. [6] In the pouring process, a conical baffle plate is placed in the center of the mold, and the discharged curable composition is poured into the mold while flowing down the conical baffle plate. A method for manufacturing an abrasive pad as described in any one of items [1] to [5]. [7] In the pouring process, the conical baffle plate is removed from the center, and the discharged curable composition is further poured into the mold. The method for manufacturing the polishing pad described in [6]. [8] In the pouring process, a weir is placed on the outer circumference of the mold. A method for manufacturing an abrasive pad as described in any one of items [1] to [7]. [9] The curable composition comprises a prepolymer obtained by the reaction of a polyisocyanate and a polyol. A method for manufacturing an abrasive pad as described in any one of items [1] to [8].

[10] In the curing step, the curable composition is cured at 75 to 125°C. A method for manufacturing an abrasive pad as described in any one of items [1] to [9].

[11] The process further includes a degassing step for removing gas from the raw materials before the aforementioned mixing step. A method for manufacturing an abrasive pad as described in any one of items [1] to

[10] . [Effects of the Invention]

[0009] According to the present invention, a method for manufacturing a polishing pad excellent in surface quality and polishing rate can be provided.

Brief Description of the Drawings

[0010] [Figure 1A] It is a schematic diagram showing an example of the plate making process of this embodiment. [Figure 1B] It is a schematic diagram showing an example of the mold making process of this embodiment. [Figure 1C] It is a schematic diagram showing an example of the pouring process of this embodiment. [Figure 1D] It is a schematic diagram showing an example of the pouring process of this embodiment. [Figure 1E] It is a schematic diagram showing an example of the pouring process of this embodiment. [Figure 1F] It is a schematic diagram showing an example of the pouring process of this embodiment. [Figure 1G] It is a schematic diagram showing an example of the pouring process of this embodiment. [Figure 1H] It is a schematic diagram showing an example of the curing process and the peeling process of this embodiment. [Figure 1I] It is a schematic diagram showing another example of the curing process and the peeling process of this embodiment. [Figure 2] It is a perspective view showing an example of the polishing pad of this embodiment.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described in detail, but the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof.

[0012] The numerical range described in this disclosure may be defined by combining any one of several candidate upper limits and any one of several candidate lower limits. In addition, unless otherwise specified, the numerical range may be defined by combining any two of several candidate upper limits, or by combining any two of several candidate lower limits.

[0013] 1. Method for manufacturing polishing pads The manufacturing method for the polishing pad of this embodiment comprises a mixing step of continuously supplying raw materials to a polymerizer, mixing the raw materials by a rotor in the mixing chamber of the continuous polymerizer, and continuously discharging a curable composition from the mixing chamber; a pouring step of pouring the discharged curable composition into a mold having a plurality of recesses; and a curing step of curing the curable composition poured into the mold to obtain a polishing layer.

[0014] Furthermore, the manufacturing method of the polishing pad of this embodiment may further include a plate-making step of forming a mask on the photosensitive resin layer of a plate material comprising a support and a photosensitive resin layer provided on the support, irradiating the photosensitive resin layer with light from the mask side, and selectively removing the parts of the photosensitive resin layer that have been irradiated with light or parts that have not been irradiated with light to produce an intaglio plate with an uneven pattern.

[0015] Furthermore, the manufacturing method of the polishing pad according to this embodiment may further include a mold manufacturing step, in which a mold resin composition is brought into contact with the uneven pattern formed on the intaglio plate obtained in the plate making step, hardened, and then the hardened material is peeled off from the intaglio plate to produce a mold onto which the uneven pattern has been transferred.

[0016] The following describes each step, referring to Figures 1A to 1D.

[0017] 1.1. Printmaking Process The plate-making process S1 is a process for producing an intaglio plate by forming a relief pattern by forming a mask 33 on the photosensitive resin layer 32 of a plate material 30 which comprises a support 31 and a photosensitive resin layer 32 provided on the support 31, irradiating the photosensitive resin layer 32 with light from the mask 33 side, and selectively removing the parts of the photosensitive resin layer 32 that have been irradiated with light or that have not been irradiated with light. In the following description, a photosensitive resin layer 32 that hardens upon light irradiation will be used as an example, but the process is not limited to this.

[0018] In the plate-making process S1, first, a plate material 30 comprising a support 31, a photosensitive resin layer 32, and a cover sheet 34 is prepared (S11), and light is irradiated onto the photosensitive resin layer 32 from the support 31 side (S12). As a result, a portion 32a of the photosensitive resin layer 32 on the support 31 side partially hardens.

[0019] Next, the cover sheet 34 is peeled off to form a mask 33, and light is shone onto the photosensitive resin layer 32 from the mask 33 side (S13). As a result, the photosensitive resin layer 32 is partially cured by the light that passes through the mask 33. At this time, the photosensitive resin layer 32 cured by exposure from the mask 33 side and the photosensitive resin layer 32 cured by exposure from the support 31 side may form a single cured product.

[0020] Then, the mask 33 is peeled off (S14), and the parts that were not irradiated with light are selectively removed (S15). This makes it possible to obtain an intaglio plate 40 with an arbitrary uneven pattern formed on the support 31. The support 31 may be peeled off from the intaglio plate 40.

[0021] Here, the printing plate material is not particularly limited as long as it comprises a support and a photosensitive resin layer provided on the support. Here, there are no particular limitations on the material having the photosensitive resin layer and the support, but examples include Printite (trade name) manufactured by Toyobo Co., Ltd. and Treleaf (trade name) manufactured by Toray Industries, Inc. after the cover film has been peeled off to expose the photosensitive resin layer.

[0022] The photosensitive resin is not particularly limited as long as it undergoes a chemical change upon the action of light, resulting in a change in its solubility or affinity for the solvent. In this embodiment, the photosensitive resin constituting the photosensitive resin layer includes not only resins that undergo chemical or structural changes upon the action of light, but also resin compositions that, even if the resin itself is not photosensitive, can exhibit photosensitivity by mixing in a photosensitizer or the like.

[0023] Such photosensitive resins are not particularly limited, but examples include polyetheramides, polyether esteramides, ammonium salt type tertiary nitrogen atom-containing polyamides, addition polymers of amide compounds having one or more amide bonds and organic diisocyanate compounds, and addition polymers of diamines without amide bonds and organic diisocyanate compounds.

[0024] Furthermore, conventionally known photosensitive resins can be used, including photo-insolubilizable resins such as resins that become insoluble by photodimerization of functional groups, resins that become insolubilizable by radical recombination after generating radicals by photodecomposition of functional groups, and resins that become insolubilizable by polymerization of low-molecular-weight monomers upon light irradiation; and photo-solubilizable resins such as resins that become solubilizable by cleavage of crosslinking bonds upon light irradiation, resins having functional groups whose polarity changes upon light irradiation, and resins that become solubilizable by cleavage of the main chain upon light irradiation. The photosensitive resin may be used alone or in combination of two or more types.

[0025] The support material is not particularly limited, but examples include plastic sheets such as polyethylene film and polyester film; metal sheets such as steel and aluminum; and other sheets such as glass. When used as an intaglio plate, the support material may have the function of supporting the relief pattern formed by selectively removing the photosensitive resin layer.

[0026] The mask partially blocks the light irradiated onto the photosensitive resin layer, and in the plate-making process, the pattern on the mask is transferred to the photosensitive resin layer by light irradiation. The mask is not particularly limited as long as it can partially block the light irradiated onto the photosensitive resin layer. Alternatively, the mask with the desired pattern may be attached after the cover film has been peeled off to expose the photosensitive resin layer, or the pattern may be formed on the mask that is attached to the photosensitive resin layer.

[0027] The light used for irradiation is not particularly limited as long as it can change the properties of the photosensitive resin, but examples include ultraviolet light. Examples of light sources that emit such light include chemical lamps or ultra-high pressure mercury lamps.

[0028] The selective removal of the photosensitive resin layer is not particularly limited as long as it is a method suitable for each photosensitive resin, but examples include washing treatment using water or an organic solvent. The intaglio plate obtained in this way has a relief pattern in which the parts of the photosensitive resin layer that were irradiated with light and the parts that were not irradiated with light have been selectively removed.

[0029] Furthermore, if the photosensitive resin layer is a photo-insolubilable resin, the parts that were not irradiated with light are selectively removed, and if the photosensitive resin layer is a photo-solubilable resin, the parts that were irradiated with light are selectively removed.

[0030] The shape of the uneven pattern can be appropriately changed depending on the mask used, and the height h (depth or thickness) of the uneven pattern can be appropriately adjusted depending on the thickness of the photosensitive resin layer used and the intensity of the irradiated (exposed) light. The height of the uneven pattern is substantially equivalent to the height H of the protrusions in the polished layer. Furthermore, the height of the uneven pattern is synonymous with the depth of the selectively removed photosensitive resin layer.

[0031] The resulting intaglio print may be dried after a washing process, and the relief pattern may be further exposed to light (post-exposure). Post-exposure can improve the adhesion between the support and the relief pattern, and further improve the hardness of the relief pattern.

[0032] 1.2. Mold Making Process The mold making step S2 is a step in which a mold resin composition 41 is brought into contact with the relief pattern formed on the intaglio plate 40 obtained in the plate making step S1 and cured (S21, S22), and then the cured product 43 is peeled off from the intaglio plate 40 (S23) to produce a mold 50 onto which the relief pattern has been transferred.

[0033] From a manufacturing standpoint, resin compositions for molds are preferably those that cure at relatively low temperatures, and are also preferably those that yield a cured product with excellent heat resistance and flexibility after curing. Such resin compositions are not particularly limited, but examples include room-temperature (low-temperature) curing resin compositions and mixed resin compositions that cure when two components are mixed.

[0034] Among these, resin compositions that cure at low temperatures of 130°C or below or at room temperature to form solid rubber molds are preferred, and resin compositions that form silicone molds are more preferred. Such molds made of solid rubber are preferred because they have appropriate flexibility and are easy to peel off from the intaglio plate and the curable composition. Furthermore, because they peel off easily from the intaglio plate, there is a tendency for less of the cured resin composition for the mold to remain on the intaglio plate.

[0035] The method for bringing the resin composition into contact with the relief pattern formed on the intaglio plate is not particularly limited as long as the resin composition is filled (poured) into the recesses of the intaglio plate. Examples include gravity casting, in which the mold composition is poured into the recesses by its own weight at room temperature and pressure, and vacuum casting, in which the mold and resin are placed in a vacuum container, the pressure is reduced, and the resin is poured into the recesses at atmospheric pressure.

[0036] Furthermore, the mold may contain a core material. The presence of a core material tends to further improve the dimensional stability of the mold. There are no particular limitations on the method for manufacturing a mold containing a core material, but examples include a method in which the resin composition for the mold is cured in contact with the core material during the mold manufacturing process, or a method in which the core material is bonded to the side of the mold opposite to the transfer surface of the uneven pattern after curing.

[0037] Furthermore, as an example of a method for curing the mold resin composition while it is in contact with the core material, after bringing the mold resin composition into contact with the uneven pattern formed on the intaglio plate, the core material may be bonded to the side of the mold resin composition opposite to the side in contact with the intaglio plate before curing the mold resin composition, and the exposed surface of the core material may be further covered with the mold resin composition to embed the core material inside the mold.

[0038] The core material is not particularly limited, but examples include materials with higher mechanical strength than the cured product of the mold resin composition.

[0039] The method for curing the resin composition for molding is not particularly limited as long as it is suitable for each resin composition for molding. Examples include curing by leaving it at room temperature, heat curing by applying heat, or mixing and leaving it, as in the case of a two-component mixture. Among these, from the viewpoint of considering the heat resistance of the intaglio plate made of a photosensitive resin, a method that proceeds to cure at room temperature is preferred.

[0040] Furthermore, from the viewpoint of heat resistance and durability of the intaglio plate, the temperature of the intaglio plate during the curing of the resin composition for the mold is preferably 130°C or lower, more preferably 100°C or lower, and even more preferably 75°C or lower. The lower limit of the intaglio plate temperature is not particularly limited, but it can be 15°C or higher. By keeping the temperature of the intaglio plate at 130°C or lower during the mold manufacturing process, deformation of the intaglio plate due to heat can be suppressed.

[0041] The temperature of the intaglio plate should preferably be considered not only when the intaglio plate and the curable composition in contact with it are heated by a thermosetting method, but also when a photocuring method and a two-component mixed resin are used, in situations where the intaglio plate may be heated due to temperature rise caused by light irradiation or heat generation due to the reaction.

[0042] 1.3. Degassing process The process may include a degassing step before the mixing step to remove air from the raw materials. This prevents the incorporation of air bubbles in the subsequent mixing and pouring steps. As a result, air bubbles can be avoided in the polished layer during the curing step, leading to improved polishing rate and surface quality.

[0043] There are no particular restrictions on the degassing method, but one possible method is to place the raw materials under negative pressure. In particular, it is preferable to place the raw materials under negative pressure while applying centrifugal force or stirring. Furthermore, when applying centrifugal force, rotation or revolution motion may also be used.

[0044] 1.4.Mixing process Mixing step S3 is a process in which raw materials are continuously supplied to the polymerizer, mixed by a rotor in the mixing chamber of the continuous polymerizer, and the curable composition is continuously discharged from the mixing chamber. Depending on the raw materials, the polymerization reaction may proceed from the moment of mixing. If such raw materials are mixed in a batch manner, there is a risk that the composition will partially harden before the mixed composition is poured in during the pouring step described later.

[0045] In the mixing process, a rotor is used that has stirring blades oriented in the same direction as the rotation or stirring blades oriented in a direction intersecting the rotation. Using a rotor with stirring blades oriented in the same direction as the rotation tends to improve mixing efficiency. As a result, unevenness in the physical properties of the resulting cured product tends to be suppressed. Also, using a rotor with stirring blades oriented in a direction intersecting the rotation tends to reduce the entrapment of air bubbles in the raw materials being mixed. As a result, defects caused by air bubble entrapment tend to be suppressed in the resulting cured product. A rotor with stirring blades oriented in the same direction as the rotation is also called a parallel-type rotor or pin rotor, and a rotor with stirring blades oriented in a direction intersecting the rotation is also called a cross-type rotor.

[0046] Furthermore, if the composition hardens before the pouring process, it may not penetrate into the fine details of the mold, making it more likely for defects to occur in the shape of the polished layer. In addition, if the hardening process progresses before the pouring process, changes in physical properties may occur between the parts where hardening progressed earlier and those where it progressed later.

[0047] In contrast, in this embodiment, raw materials are continuously supplied to the polymerizer, mixed by a rotor in the mixing chamber of the continuous polymerizer, and the curable composition is continuously discharged from the mixing chamber. This allows uniformly mixed raw materials to be quickly supplied to the pouring process before polymerization progresses. As a result, defects in the shape of the polished layer can be suppressed, changes in physical properties are less likely to occur, and the polishing rate and surface quality are further improved.

[0048] The volume of the mixing chamber is smaller than the total amount of curable composition poured into a single mold, and it is preferable to perform the mixing and pouring processes continuously. If the volume of the mixing chamber is smaller than the total amount of curable composition poured into a single mold, the amount of mixed composition will be insufficient in a single mixing step. Therefore, the mixing and pouring processes must be performed continuously rather than in a batch manner.

[0049] By performing the mixing and pouring processes consecutively in this manner, it is possible to suppress excessive hardening of the raw materials during the mixing and pouring processes. As a result, defects in the shape of the polished layer can be further suppressed, changes in physical properties are less likely to occur, and polishing rate and surface quality tend to improve.

[0050] The raw materials preferably contain polyisocyanate and polyol, and may also contain a urethane prepolymer obtained by the reaction of polyisocyanate and polyol. This allows for the production of a polyurethane resin. The raw materials may also contain a curing agent as needed. This tends to further improve the polishing rate and surface quality.

[0051] 1.4.1. Constituent units derived from polyisocyanates The constituent units derived from polyisocyanates are not particularly limited, but examples include constituent units derived from alicyclic isocyanates, aliphatic isocyanates, and aromatic isocyanates. Among these, aromatic isocyanates are preferred, and diphenylmethane-4,4'-diisocyanate (MDI) is more preferred.

[0052] Alicyclic isocyanates are not particularly limited, but examples include 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, and isophorone diisocyanate.

[0053] Aliphatic isocyanates are not particularly limited, but examples include hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), tetramethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, trimethylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0054] Aromatic isocyanates are not particularly limited, but examples include phenylene diisocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4-TDI), xylylene diisocyanate, naphthalene diisocyanate, and diphenylmethane-4,4'-diisocyanate (MDI).

[0055] 1.4.2. Constituent units derived from polyols The constituent units derived from polyols are not particularly limited, but examples include low molecular weight polyols with a molecular weight of less than 300 and high molecular weight polyols with a molecular weight of 300 or more. Among these, it is preferable to use at least low molecular weight polyols, and it is preferable to use low molecular weight polyols and high molecular weight polyols in combination.

[0056] Low molecular weight polyols are not particularly limited, but examples include low molecular weight polyols having two hydroxyl groups such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexane glycol, 2,5-hexanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, tricyclodecanedimethanol, and 1,4-cyclohexanedimethanol; and low molecular weight polyols having three or more hydroxyl groups such as glycerin, hexanetriol, trimethylolpropane, isocyanuric acid, and erythritol. Low molecular weight polyols may be used individually or in combination of two or more.

[0057] Furthermore, while the polymer polyol is not particularly limited, examples include polyether polyols, polyester polyols, polycarbonate polyols, polyether polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols. The polymer polyol may be used alone or in combination of two or more types.

[0058] The number-average molecular weight of the polymer polyol is preferably 300 to 1200, more preferably 400 to 950, and even more preferably 500 to 800. By using such a polymer polyol, it tends to be easier to adjust the dynamic viscoelastic properties and D hardness within the above range.

[0059] Among these, polyester polyols are preferred, and polyester polyols composed of adipic acid and ethylene glycol are more preferred. By using such polymeric polyols, it is easier to adjust the dynamic viscoelastic properties and D hardness within the above range, it is easier to adjust the hardness at low temperatures, and it is possible to suppress the decrease in hardness with increasing temperature. In addition, flatness can be further improved.

[0060] The content of constituent units derived from polyester polyol is preferably 40 to 100 parts, preferably 50 to 90 parts, and more preferably 60 to 84 parts, per 100 parts of constituent units derived from polyisocyanate. By having the content of constituent units derived from polyether polyol within the above range, it is easier to adjust the dynamic viscoelastic properties and D hardness within the above range, and flatness can be further improved.

[0061] 1.4.3. Hardener The curing agent is not particularly limited, but examples include polyamines and polyols. The curing agent may be used alone or in combination of two or more types.

[0062] Polyamines are not particularly limited, but examples include aliphatic polyamines such as ethylenediamine, propylenediamine, and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and dicyclohexylmethane-4,4'-diamine; and aromatic polyamines such as 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4-methyl-2,6-bis(methylthio)-1,3-benzenediamine, 2-methyl-4,6-bis(methylthio)-1,3-benzenediamine, and 2,2-bis(3-amino-4-hydroxyphenyl)propane.

[0063] Among these, aromatic polyamines are preferred, and 3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) is more preferred.

[0064] Examples of polyols include those similar to the polyols described above. Among these, low molecular weight polyols are preferred, and 1,4-butylene glycol is even more preferred.

[0065] 1.4.4. Other curable compositions Other curable compositions not mentioned above are not particularly limited, but include, for example, thermosetting resins; UV-curable resins; photocurable compositions containing a photopolymerization initiator and a polymerizable compound; thermosetting compositions containing a thermal polymerization initiator and a polymerizable compound; and curable compositions containing a two-component curable resin. The curable composition may also optionally contain a crosslinking agent having two or more polymerizable functional groups.

[0066] The polymerizable compounds mentioned above are not particularly limited, but examples include unsaturated carboxylic acids having polymerizable unsaturated groups such as (meth)acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid; unsaturated carboxylic acid esters having polymerizable unsaturated groups such as (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate; polyesters having unsaturated groups; polyethers having polymerizable unsaturated groups; polyamides having polymerizable unsaturated groups; urethanes having polymerizable unsaturated groups; and aromatic compounds having polymerizable unsaturated groups such as styrene.

[0067] The above-mentioned photopolymerization initiators are not particularly limited, but examples include benzophenone compounds, acetophenone compounds, and thiothisanthone compounds. The thermal polymerization initiators are also not particularly limited, but examples include azo compounds such as 2,2'-azobisbutyronitrile; and peroxides such as methyl ethyl ketone peroxide and benzoyl peroxide (BPO).

[0068] Furthermore, while the thermosetting resin is not particularly limited, examples include phenolic resins, epoxy resins, acrylic resins, and formaldehyde resins.

[0069] While not particularly limited, the UV-curable resin is preferably a prepolymer with a number-average molecular weight of approximately 1,000 to 10,000. Examples of materials include acrylic (methacrylic) ester resins, urethane-modified resins thereof, and thiocol resins. Reactive diluents and organic solvents can be used as appropriate depending on the application.

[0070] Furthermore, the two-component curing resin is not particularly limited, but for example, prepolymers with different physical properties can be used, such as epoxy resins, unsaturated polyester resins, and polyamide resins.

[0071] Among these, those that cure at room temperature are preferred, considering the heat resistance of the mold. Such curable compositions are not particularly limited, but examples include curable compositions containing polymerization initiators that act at room temperature, UV-curable resins and photocurable compositions that cure by light irradiation, and mixed-type curable compositions that cure by mixing two components.

[0072] 1.5.Pouring process The pouring step S4 is a step of pouring the curable composition 51 into a mold 50 having a plurality of recesses. The method of bringing the curable composition into contact with the uneven pattern formed on the mold is not particularly limited as long as the curable composition is filled (poured) into the recesses of the mold. Examples include gravity casting, in which the curable composition is poured into the recesses by its own weight at room temperature and atmospheric pressure, and vacuum casting, in which the mold and resin are placed in a vacuum container, the pressure is reduced, and the composition is poured into the recesses at atmospheric pressure.

[0073] Furthermore, after bringing the curable composition into contact with the uneven pattern formed on the mold, the process may further include a step of bonding a substrate to the side of the curable resin opposite to the side in contact with the mold, before curing the curable composition. By using a substrate, the curable composition is cured with the substrate sandwiched between the mold and the mold. This tends to improve the uniformity of the thickness of the resulting cured product and further improve the flatness of the back surface (the side opposite to the side in contact with the mold) of the resulting cured product.

[0074] Furthermore, the positional relationship between the base material 11 and the mold 50 may be such that the base material 11 does not come into contact with the uneven pattern of the mold 50, as shown in Figure 1H, or as shown in Figure 1I, the base material 11 comes into contact with the uneven pattern of the mold 50. If the base material 11 does not come into contact with the uneven pattern of the mold 50, the resulting cured product will have protrusions that constitute the uneven pattern and support regions for connecting the protrusions. If the base material 11 comes into contact with the uneven pattern of the mold 50, the resulting cured product will have protrusions that constitute the uneven pattern, and these protrusions will be formed on the base material 11.

[0075] In the pouring process, it is preferable to pour the discharged curable composition 51 into the center of the mold 50. This makes it easier for the curable composition 51 to penetrate into the fine details of the irregularities of the mold 50. As a result, defects in the shape of the polished layer tend to be suppressed.

[0076] Furthermore, as shown in Figures 1C to 1E, it is preferable to place a conical baffle plate 52 in the center of the mold 50 during the pouring process, and to pour the discharged curable composition 51 into the mold 50 while allowing it to flow along the conical baffle plate 52. The curable composition 51 travels along the conical baffle plate 52 in direction F1 (Figure 1C), spreads in a planar direction from the conical baffle plate 52 to the mold 50 in direction F2 (Figure 1D), and spreads in a planar direction from the center to the edge of the mold 50 in direction F3 (Figure 1E). As a result, the curable composition can easily penetrate into the fine details of the irregularities of the mold in the intermediate part A1 and edge A2 between the center and edge of the polishing pad. This also tends to further suppress defects in the shape of the polishing layer.

[0077] Furthermore, as shown in Figures 1C to 1E, when using the conical baffle plate 52, it is preferable to remove the conical baffle plate 52 from the center (Figure 1F) and then pour the discharged curable composition 51 further into the mold (Figure 1G). This makes it easier for the curable composition to penetrate into the fine details of the irregularities in the mold at the center of the polishing pad. As a result, defects in the shape of the polishing layer tend to be further suppressed.

[0078] Furthermore, as shown in Figures 1C to 1G, it is preferable to place a weir 53 on the outer circumference of the mold 50 during the pouring process. This allows the curable composition 51, which has spread in a planar direction from the center to the edge of the mold 50 in direction F3, to be blocked by the weir 53. As a result, the curable composition can more easily penetrate into the fine details of the irregularities of the mold at the edge A2 of the polishing pad. Therefore, it tends to further suppress defects in the shape of the polishing layer.

[0079] 1.6.Curing process The curing step S5 is a step in which the curable composition 51 poured into the mold 50 is cured to obtain a polishing layer 12. By curing the curable composition in contact with the uneven pattern formed on the obtained mold, a cured product of the curable composition with the uneven pattern transferred can be obtained. The surface of the uneven pattern (the surface of the protrusions) of the cured product obtained in this step becomes a polishing surface for polishing the workpiece.

[0080] The method for curing the curable composition is not particularly limited as long as it is suitable for each curable composition, but examples include photocuring methods such as irradiation with ultraviolet light, thermal curing methods that apply heat (including methods that leave at room temperature), or methods that involve mixing and leaving, such as two-component mixtures.

[0081] The curing process may be carried out using multiple molds. Similar to the mold manufacturing process, if the size of the polishing pad to be manufactured is larger than that of a single mold, a mold of the desired size can be manufactured by combining multiple molds, and then the cured material (polishing layer) can be formed using the combined mold. This eliminates the need to manufacture molds according to the size of the polishing pad, making it possible to omit the process of manufacturing molds of various sizes and further reducing manufacturing costs. In addition, although a rectangular mold was used as an example above, in this case, if a circular polishing pad is to be obtained, the resulting cured material (polishing layer) may be cut into a circular shape.

[0082] In the curing process, the temperature at which the curable composition is cured is preferably 25°C or higher, 50°C or higher, 75°C or higher, 100°C or higher, or 125°C or higher. Alternatively, the temperature at which the curable composition is cured is preferably 200°C or lower, 150°C or lower, 125°C or lower, 100°C or lower, or 75°C or lower. The temperature can be adjusted as appropriate depending on the curable composition.

[0083] 1.7. Peeling Process The peeling step S6 is a step in which the hardened material is peeled off the mold 50 to obtain the polishing layer 12. The polishing layer 12 obtained in this step has an uneven pattern transferred from the mold 50, and the surface of the raised parts of the uneven pattern becomes a polishing surface for polishing the workpiece.

[0084] In this embodiment, a polishing pad having a sufficiently high uneven pattern can be manufactured at a lower cost and in a simpler manner, without going through a cutting process.

[0085] Figure 2 shows a schematic perspective view of the polishing pad of this embodiment. The polishing pad 1 of this embodiment may have a base material 11 and the polishing layer 12 disposed on the base material 11. In Figure 2, a plurality of protrusions made of the polishing layer 12 are arranged on the surface of the base material 11 to form an uneven pattern.

[0086] As shown in Figure 2, the polishing layer 12 has multiple frustoconical protrusions on the same plane. The upper surfaces of the protrusions serve as polishing surfaces for polishing the workpiece. The polishing layer 12 may form an uneven pattern together with the base material 11 as shown in Figure 2, or it may form an uneven pattern by itself.

[0087] The flat surface of the polishing pad in this embodiment may have grooves in areas where no protrusions are provided. Figure 2 shows a perspective view of a polishing pad with grooves 13 formed therein. The presence of such grooves tends to facilitate the supply of slurry to the polishing surface and the discharge of polishing debris. [Industrial applicability]

[0088] This invention has industrial applicability as a method for manufacturing polishing pads for polishing semiconductor devices and the like. [Explanation of Symbols]

[0089] 1… Grinding plate, 11… Substrate, 12… Grinding layer, 13… Groove, 30… Plate, 31… Support, 32… Part, 32… Photosensitive resin layer, 32a… Part, 33… Mask, 34… Cover sheet, 40… Gravure, 41… Molding resin composition, 43… Cured material, 50… Molding mold, 51… Curing composition

Claims

1. A mixing step in which raw materials are continuously supplied to a continuous polymerizer, the raw materials are mixed by a rotor in the mixing chamber of the continuous polymerizer, and a curable composition is continuously discharged from the mixing chamber, A pouring step in which the discharged curable composition is poured into a mold having a plurality of recesses, The system comprises a curing step of curing the curable composition poured into the mold to obtain a polished layer, The rotor is a rotor having stirring blades oriented in the same direction as the direction of rotation or stirring blades oriented in a direction intersecting the direction of rotation. In the pouring process, a conical baffle plate is placed in the center of the mold, and the discharged curable composition is poured into the mold while flowing down the conical baffle plate. A method for manufacturing polishing pads.

2. The aforementioned mold is a mold made of silicone. A method for manufacturing an abrasive pad according to claim 1.

3. The aforementioned raw materials include polyisocyanate and polyol. A method for manufacturing an abrasive pad according to claim 1.

4. The volume of the mixing chamber is smaller than the total amount of the curable composition poured into one of the molds. The mixing step to the infusion step is performed continuously. A method for manufacturing an abrasive pad according to claim 1.

5. In the pouring process, the discharged curable composition is poured into the center of the mold. A method for manufacturing an abrasive pad according to claim 1.

6. In the pouring process, the conical baffle plate is removed from the center, and the discharged curable composition is further poured into the mold. A method for manufacturing an abrasive pad according to claim 1.

7. In the pouring process, a weir is placed on the outer circumference of the mold. A method for manufacturing an abrasive pad according to claim 1.

8. The curable composition comprises a prepolymer obtained by the reaction of a polyisocyanate and a polyol. A method for manufacturing an abrasive pad according to claim 1.

9. In the curing step, the curable composition is cured at 75 to 125°C. A method for manufacturing an abrasive pad according to claim 1.

10. The process further includes a degassing step for removing gas from the raw materials before the aforementioned mixing step. A method for manufacturing an abrasive pad according to claim 1.

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