JP7626744B2 - Polishing pad and method of manufacturing same - Google Patents

Description

The present invention relates to a polishing pad and a method for manufacturing the same.

Polishing pads are used for lapping and polishing optical materials, semiconductor devices, glass substrates for hard disks, etc. Various types of polishing pads are known, including polishing pads using nonwoven fabric, polishing pads using foamed or non-foamed polyurethane, polishing pads with fixed abrasive grains, and polishing pads using a resin layer with a concave-convex pattern as a polishing surface.

Among these, the polishing pad using the resin layer having a concave-convex pattern as the polishing surface has the advantage that the groove formed by the concave-convex pattern acts on the fluidity of the slurry, and as a result, the object to be polished can be polished uniformly. The manufacturing method of such a polishing pad includes a method of cutting the surface of a flat base material to form grooves, a method of applying a screen printing method to form a concave-convex pattern on a substrate, and a method of making a mold having a concave-convex pattern and using the mold to mold.

For example, Patent Document 1 discloses a method for manufacturing a polishing pad in which a metal master mold is used to perform micro-machining on the surface by a micro-molding method, because there is a limit to the miniaturization of dimensions such as groove width and depth in a method of forming grooves by cutting. In such a molding method, a mold having a fine uneven pattern is used, making it possible to form a fine uneven pattern that requires micro-machining, which is difficult to process by conventional cutting processes.

JP 2005-74614 A

However, when using a metal mold as in Patent Document 1, fine machining such as cutting must be performed when producing the mold, and no method has been provided that completely eliminates the need for cutting. In addition, since the mold is expensive, it is difficult to use, and when it is desired to appropriately change the concave-convex pattern, such as the width or depth of the groove, it is necessary to produce an expensive mold again, which is unrealistic.

In addition, the method of forming a concave-convex pattern on a substrate by screen printing can form a concave-convex pattern without a cutting process, but the dot-shaped resin (convex portion) formed on the substrate by screen printing tends to spread on the substrate due to its own weight and viscosity, so there is a limit to obtaining a concave-convex pattern with a high convex portion. Furthermore, the convex portion of the polishing pad tends to be scraped off with polishing and the polishing rate gradually decreases, but when the height of the convex portion is low (the depth of the groove is shallow), the polishing rate decreases immediately, so there is a problem that the product life of the polishing pad cannot be sufficiently secured.

The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a method for manufacturing a polishing pad that can form a sufficiently high uneven pattern more easily and at lower cost without going through a cutting process, and a polishing pad manufactured by said method.

The present inventors have conducted extensive research into the above problems, and as a result have found that the above problems can be solved by a method for forming a relief plate using a printing material having a photosensitive resin layer, thereby completing the present invention.

That is, the present invention is as follows.
[1]
A method for producing a polishing pad having a polishing layer formed by curing a curable composition, comprising the steps of:
a plate preparation step of forming a mask on the photosensitive resin layer of a plate material including 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 light-irradiated or non-light-irradiated portions of the photosensitive resin layer to prepare a relief plate having a relief pattern;
a curing step of curing the curable composition in contact with the concave-convex pattern formed on the obtained concave-convex plate to obtain a cured product of the curable composition to which the concave-convex pattern has been transferred;
a peeling step of peeling the cured product from the relief plate to obtain an abrasive layer;
having
A method for manufacturing a polishing pad.
[2]
In the curing step, the temperature of the relief plate is 130° C. or less.
A method for producing the polishing pad described in [1].
[3]
A polishing layer is provided which is formed by curing a curable composition,
The bending strength of the polishing layer is 50 MPa or more.
Polishing pad.
[4]
The polishing layer has a concave-convex pattern in which a support region and a convex portion formed on the support region are integrally molded.
The polishing pad according to [3].

According to the present invention, it is possible to provide a method for manufacturing a polishing pad that can form a sufficiently high uneven pattern more easily and at lower cost without going through a cutting process, and a polishing pad manufactured by said method.

3A to 3C are process diagrams of a method for manufacturing a polishing pad according to the present embodiment. FIG. 4 is a process diagram showing another embodiment of the curing process. FIG. 13 is a top view showing an example of use of a relief plate when multiple relief plates are used. FIG. 11 is a process diagram showing an example of a curing process using a plurality of relief plates.

The following describes in detail an embodiment of the present invention (hereinafter referred to as the "present embodiment"); however, the present invention is not limited to this embodiment, and various modifications are possible without departing from the gist of the present invention.

[Method of manufacturing polishing pad]
The manufacturing method of the polishing pad of this embodiment is a manufacturing method of a polishing pad having a polishing layer formed by curing a curable composition, and includes a plate preparation step of forming a mask on a photosensitive resin layer of a plate material having a support and a photosensitive resin layer provided on the support, irradiating light onto the photosensitive resin layer from the mask side, and selectively removing the parts of the photosensitive resin layer that have been irradiated with light or the parts that have not been irradiated with light to prepare an uneven plate having an uneven pattern formed thereon, a curing step of curing the curable composition in contact with the uneven pattern formed on the obtained uneven plate to obtain a cured product of the curable composition to which the uneven pattern has been transferred, and a peeling step of peeling the cured product from the uneven plate to obtain the polishing layer.

As described above, in the conventional method using a metal mold, cutting cannot be completely eliminated, which is problematic from the viewpoint of cost, and there is also a problem that it is difficult to respond to changes in the concave-convex pattern such as the width and depth of the grooves, etc. In addition, there is a problem that it is difficult to obtain a concave-convex pattern having high convexities in the method using a screen printing method or the like.

In contrast, in the method for producing a polishing pad of the present embodiment, a plate having a desired uneven pattern can be obtained relatively easily from a plate material having a photosensitive resin layer, and the obtained uneven plate can be used as a mold as it is, thereby making it possible to efficiently obtain a polishing layer having an arbitrary uneven pattern. In addition, the uneven pattern can be easily changed. In particular, in the method for producing a polishing pad of the present embodiment, the uneven plate once produced can be repeatedly used in the curing process, thereby further improving the production efficiency.

FIG. 1 shows a flow chart of the manufacturing method of the polishing pad of this embodiment. As shown in FIG. 1, in the manufacturing method of the polishing pad of this embodiment, a plate material 3 having a photosensitive resin layer 1 and a support 2 is used, and the plate material 3 is irradiated with light through a mask 4, so that a relief plate 5 can be obtained without cutting or the like. The obtained relief plate 5 can have various relief patterns 6 depending on the mask 4 used, and the relief pattern 6 has grooves according to the thickness of the photosensitive resin layer 1. In the subsequent curing step, the relief pattern 6 of the relief plate 5 is accurately transferred to the cured product of the curable composition 7. Therefore, the polishing pad 10 having the polishing layer 9 obtained by the manufacturing method of this embodiment can form a relief pattern 11 having grooves that are much deeper than those obtained by screen printing. In the plate manufacturing step shown in FIG. 1, an embodiment in which the portion 1a irradiated with light remains to form the relief pattern 6 of the relief plate 5 is shown, but as described later, an embodiment in which the portion 1b not irradiated with light remains to form the relief pattern 6 of the relief plate 5 may also be used. Each step will be described in more detail below.

[Plate making process]
The plate preparation process is a process in which a mask is formed on the photosensitive resin layer of a plate material having a support and a photosensitive resin layer provided on the support, light is irradiated onto the photosensitive resin layer from the mask side, and the parts of the photosensitive resin layer that are irradiated with light or those that are not irradiated with light are selectively removed to produce an uneven plate having an uneven pattern.

The plate material is not particularly limited as long as it has a support and a photosensitive resin layer provided on the support. Here, the plate material having the photosensitive resin layer and the support is not particularly limited, but examples thereof include Printite (product name) manufactured by Toyobo Co., Ltd. and Toray Relief (product name) manufactured by Toray Industries, Inc., after the cover film is peeled off to expose the photosensitive resin layer.

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

Such photosensitive resins are not particularly limited, but examples thereof include polyether amides,
Examples of the polyether ester amide include polyamides containing tertiary nitrogen atoms of ammonium salt type, addition polymers of amide compounds having one or more amide bonds and organic diisocyanate compounds, and addition polymers of diamines having no amide bonds and organic diisocyanate compounds.

The photosensitive resin may be a conventionally known one, and examples of such photoinsolubilizable resins include resins that are insolubilized by photodimerization of functional groups, resins that generate radicals by photodecomposition of functional groups and are insolubilized by radical recombination, and resins that are insolubilized by polymerization of low molecular weight monomers by light irradiation; photosolubilizable resins such as resins that are solubilized by cleavage of crosslinking bonds by light irradiation, resins having functional groups whose polarity changes by light irradiation, and resins that are solubilized by cleavage of the main chain by light irradiation. The photosensitive resins may be used alone or in combination of two or more.

The support is not particularly limited, and examples thereof include plastic plates such as polyethylene films and polyester films, metal plates such as steel and aluminum, and other plates such as glass. When used as a relief plate, the support can have a function of supporting a relief pattern formed by selectively removing the photosensitive resin layer.

The mask partially blocks the light irradiated to the photosensitive resin layer, and the pattern of the mask is transferred to the photosensitive resin layer by light irradiation in the plate making process. The mask is not particularly limited as long as it can partially block the light irradiated to the photosensitive resin layer. In addition, the mask may be one in which a mask having a desired pattern is adhered to the photosensitive resin layer after peeling off the cover film to expose the photosensitive resin layer, or one in which a pattern is formed on the mask adhered to the photosensitive resin layer.

The light to be irradiated is not particularly limited as long as it can change the properties of the photosensitive resin, and examples of the light include ultraviolet light, etc. Examples of light sources that emit such light include chemical lamps and ultra-high pressure mercury lamps.

The selective removal of the photosensitive resin layer is not particularly limited as long as it is a method suitable for each photosensitive resin, and examples include washing out treatment using water or an organic solvent. The relief plate obtained in this manner has a relief pattern in which the parts of the photosensitive resin layer that have been irradiated with light or the parts that have not been irradiated with light have been selectively removed. The shape of the relief pattern can be appropriately changed depending on the mask used, and the height h (depth or thickness) of the relief 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 h of the relief pattern is substantially equal to the height of the convex parts 11a of the polishing layer (
FIG. 1. The height h of the concave-convex pattern is synonymous with the depth of the selectively removed photosensitive resin layer.

The obtained relief plate may be dried after washing out treatment, and the relief pattern may be irradiated with light (post-exposure). Post-exposure can improve the adhesion between the support and the relief pattern, and can further increase the hardness of the relief pattern.

[Curing process]
The curing step is a step in which the curable composition is cured in contact with the concave-convex pattern formed on the obtained relief plate, to obtain a cured product of the curable composition to which the concave-convex pattern has been transferred. The surface of the concave-convex pattern of the cured product obtained in this step (the surface of the convex portions) becomes the polishing surface for polishing an object to be polished.

The curable composition is not particularly limited, and examples thereof include a thermosetting resin, a UV curable resin, a photocurable composition containing a photopolymerization initiator and a polymerizable compound, a thermosetting composition containing a thermal polymerization initiator and a polymerizable compound, a curable composition containing a two-liquid mixed curable resin, etc. Furthermore, the curable composition may contain a crosslinking agent having two or more polymerizable functional groups, etc., as necessary.

The polymerizable compound is not particularly limited, but examples thereof include unsaturated carboxylic acids having a polymerizable unsaturated group, such as (meth)acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid; unsaturated carboxylic acid esters having a polymerizable unsaturated group, such as (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate; polyesters having unsaturated groups; polyethers having a polymerizable unsaturated group; polyamides having a polymerizable unsaturated group; urethanes having a polymerizable unsaturated group; and aromatic compounds having a polymerizable unsaturated group, such as styrene.

The photopolymerization initiator is not particularly limited, but examples thereof include benzophenone-based compounds,
Examples of the thermal polymerization initiator include, but are not limited to, azo compounds such as 2,2'-azobisbutyronitrile, and peroxides such as methyl ethyl ketone peroxide and benzoyl peroxide (BPO).

The thermosetting resin is not particularly limited, but examples thereof include phenol resin, epoxy resin, acrylic resin, urethane resin, and formaldehyde resin.

The UV-curable resin is not particularly limited, but may be, for example, a resin having a number average molecular weight of 1000 to 10
Prepolymers having a molecular weight of about 1,000 are preferred, and examples of materials include acrylic (methacrylic) ester resins and their urethane modified resins, and thiokol resins. Reactive diluents and organic solvents can be used as appropriate depending on the application.

The two-liquid mixed curable resin is not particularly limited, but examples thereof include prepolymers having different physical properties, such as epoxy resins, unsaturated polyester resins, and polyamide resins.

Among these, from the viewpoint of the heat resistance of the relief printing plate, those that cure at room temperature are preferred. Such curable compositions are not particularly limited, but examples thereof include curable compositions containing a polymerization initiator that acts at room temperature, UV-curable resins and photocurable compositions that cure by irradiation with light, and mixed-type curable compositions that cure by mixing two liquids.

The method of contacting the curable composition with the concave-convex pattern formed on the concave-convex plate is not particularly limited as long as the curable composition is filled (pouring) into the concave portions of the concave-convex plate. Examples of the method include a gravity casting method in which the curable composition is poured into the concave portions by its own weight at room temperature and normal pressure, and a vacuum casting method in which a mold and resin are placed in a vacuum container, the pressure is reduced, and the curable composition is poured into the concave portions at atmospheric pressure.

In addition, after the concave-convex pattern formed on the concave-convex plate is brought into contact with the curable composition, a step of bonding a substrate to the surface of the curable resin opposite to the surface in contact with the concave-convex plate before curing the curable composition may be further included. By using a substrate, the curable composition is sandwiched between the substrate and the concave-convex plate and then cured. This tends to improve the uniformity of the thickness of the obtained cured product, and to further improve the flatness of the back surface (the surface opposite to the surface in contact with the concave-convex plate) of the obtained cured product. In addition, the positional relationship between the substrate and the concave-convex plate may be such that the substrate 8 does not contact the concave-convex pattern 6 of the concave-convex plate 5 as shown in FIG. 1, or may be such that the substrate 8 contacts the concave-convex pattern 6 of the concave-convex plate 5 as shown in FIG. 2. When the substrate 8 is not in contact with the concave-convex pattern 6 of the concave-convex plate 5, the obtained cured product has a concave-convex pattern 1.
When the substrate 8 is brought into contact with the concave-convex pattern 6 of the concave-convex plate 5, the resulting cured product has the convex portions 11a that constitute the concave-convex pattern 11, and the convex portions 11a are formed on the substrate 8.

The method for curing the curable composition is not particularly limited as long as it is a method suitable for each curable composition. For example, a photocuring method in which ultraviolet rays or the like are irradiated, a thermal curing method in which heat is applied (
Examples of the method include a method in which the mixture is left at room temperature, or a method in which the mixture is mixed and left as is the case with a two-liquid mixture type.

The relief pattern of the relief plate of this embodiment is made of a resin material made of a photosensitive resin.
Therefore, from the viewpoint of the heat resistance and durability of the relief plate, the temperature of the relief plate during curing of the curable composition is preferably 130° C. or less, more preferably 100° C. or less, and even more preferably 75° C. or less. The lower limit of the temperature of the relief plate is not particularly limited, but is preferably 15° C.
The temperature of the relief plate in the curing step is 130° C. or less, so that deformation of the relief plate due to heat can be suppressed. It is preferable that the temperature of the relief plate is also considered in the same manner in the case where the relief plate and the curable composition in contact with it are heated by the heat curing method, and in the case where a photocuring method and a two-liquid mixed resin are used, and where the relief plate may be heated due to a rise in temperature caused by light irradiation or heat generation caused by a reaction.

The curing step may be performed using multiple relief plates. A top view showing an example of the use of relief plates when multiple relief plates are used is shown in FIG. 3, and an example of the curing step using multiple relief plates is shown in FIG. 4. As shown in FIG. 3, when the size of the polishing pad to be produced is larger than one relief plate 5a-5i, a relief plate of the desired size is produced by combining multiple relief plates 5a-5i (FIG. 3), and then the cured product (polishing layer) can be formed using the combined relief plates (FIG. 4). This eliminates the need to produce a relief plate according to the size of the polishing pad,
It is possible to omit the process of producing various sizes of relief plates, and the manufacturing cost can be further reduced. In the above example, the rectangular relief plates 5a to 5i are exemplified, but in this case, if a circular polishing pad is to be obtained, the obtained cured product (polishing layer) may be cut into a circle.

[Peeling process]
The peeling step is a step of obtaining an abrasive layer by peeling off the cured product from the relief plate. The abrasive layer obtained in this step has a relief pattern transferred from the relief plate, and the surfaces of the protruding parts of the relief pattern become the abrasive surfaces for polishing the workpiece.

[Polishing pad]
The polishing pad of this embodiment is obtained by the above-mentioned manufacturing method, and has a polishing layer formed by curing a curable composition, and the polishing layer has an irregular pattern of any shape and sufficient height. The bending strength of the polishing layer is 50 MPa, and preferably 50 to 1000.
MPa, more preferably 55 to 900 MPa, and further preferably 60 to 80
The bending strength is obtained by measurement performed in accordance with JIS K7203. When the bending strength is within the above range, damage or deformation of the abrasive layer can be suppressed when the abrasive layer is peeled off from the relief plate in the peeling step.

In addition, it is preferable that the polishing layer has a concave-convex pattern in which the support region and the convex portions formed on the support region are integrally molded. By integrally molding the convex portions and the support region, the process of joining the convex portions and the support region is eliminated, and costs can be reduced.
Compared to when the protrusions and the support region are bonded together, the bonding strength is higher and the protrusions are less likely to come off the support region.

Below, from the standpoints of the height of the uneven pattern, the high degree of freedom in designing the uneven pattern, and the simplicity (cost) of the manufacturing method, the method of manufacturing a polishing pad according to this embodiment, the method of manufacturing a polishing pad using a mold, and the method of manufacturing a polishing pad by screen printing were qualitatively evaluated.

As a result, in a manufacturing method that involves a process using a mold, a relatively high concave-convex pattern can be formed, but the design freedom of the concave-convex pattern is low due to the need to change the mold, and since it is a prerequisite to create an elaborate mold, the manufacturing process is also lacking in simplicity. Note that these drawbacks are not limited to metal molds, but are also the same when a resin mold that does not use a photosensitive resin is used.

Furthermore, in the method using screen printing, there is a limit to the height of the concave-convex pattern, and it is difficult to form a desired concave-convex pattern from the viewpoint of product life.

In comparison, the method for producing a polishing pad according to the present embodiment makes it possible to easily form a concave-convex pattern having a sufficient height at low cost.

The method for producing a polishing pad of the present invention has industrial applicability as a method for producing a polishing pad used for lapping or polishing optical materials, semiconductor devices, glass substrates for hard disks, and the like.

Reference Signs List 1: photosensitive resin layer, 1a: light irradiated portion, 1b: non-light irradiated portion, 2: support, 3: printing plate, 4: mask, 5, 5a to i: relief plate, 6: relief pattern, 7: curable composition, 8: substrate, 9: polishing layer, 10: polishing pad, 11: relief pattern, 11a: convex portion, 1
1b...Support area

Claims (2)

The polishing layer is formed by curing a curable composition (excluding those formed from foamed polyurethane),
The curable composition contains a thermosetting resin, a photocurable composition, a thermosetting composition, or a two-liquid mixed curable resin (excluding acetyl cellulose) ,
The polishing layer has a concave-convex pattern,
the surface of the concave-convex pattern is a polishing surface for polishing an object to be polished,
The bending strength of the polishing layer is 50 MPa or more.
Polishing pad. The polishing layer has a concave-convex pattern in which a support region and a convex portion formed on the support region are integrally molded.
2. The polishing pad of claim 1.