TWI600498B - Honing pad and honing pad manufacturing method - Google Patents

Description

Method for manufacturing polishing pad and polishing pad

The present invention relates to a polishing pad and a method of manufacturing the same, and, in particular, to a polishing pad for finishing a bare semiconductor, a semiconductor device, and a disk, and a method of manufacturing the same.

A polishing pad used for polishing a semiconductor device or the like is roughly classified into a hard and soft type, and a hard mainstream is a dry method in which a chain of a urethane prepolymer is stretched while being stretched, and a soft mainstream is an aminocarboxylic acid. A wet method in which an ester resin solution is formed in a coagulation bath and dried. In recent years, a high degree of flatness and a high degree of uniformity are required for an object to be polished, and an example of using a soft polishing pad in a finishing polishing step or the like is increasing.

In particular, in the finishing polishing step of bare dies, semiconductor devices, and magnetic disks, it is expected that the polishing amount and the polishing flatness are excellent, and at the same time, it is expected to suppress the occurrence of polishing damage (also referred to as defects or scratches). Conventionally, a polishing pad having a wet urethane resin film as a polishing layer has been used in the finishing polishing step (see, for example, Patent Document 1 and Patent Document 2), but there is a problem that defects occur.

In addition, the grinding used for the finishing grinding step has been previously proposed. The pad is provided with a light-transmitting portion for optically and visually detecting the polishing end point. For example, a light-transmitting portion is provided by using a thermoplastic resin capable of imparting light transmittance (Patent Document 3), or a polishing slurry (slurry) The groove portion used is translucent (Patent Document 4, Patent Document 5).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 2-220838

[Patent Document 2] Japanese Patent Laid-Open No. 2011-067923

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2002-324770

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2005-001059

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2005-340718

The conventional wet polishing pad having a polyurethane resin film as an abrasive layer has a problem that it is liable to cause polishing damage. The present inventors have found that when a polyurethane film is formed into a film, a film forming aid or carbon black is added in addition to the polyurethane resin constituting the polishing layer. In the case of an additive, a component of the components which is insoluble in the polar solvent of the soluble resin contributes to the grinding damage. In particular, it has been found that carbon black is blended in the polishing layer for the purpose of improving elastic properties or improving polishing stability, but it is a cause of polishing damage.

Further, since the addition of the carbon black and the foamed structure make the polyurethane resin film impervious, it is necessary to remove a part of the polishing layer in order to provide a region in which the polishing end point is optically and visually detected. The removal of a part of the polishing layer causes a problem that the manufacturing steps of the polishing pad are complicated, and liquid leakage or the like occurs from the joint portion of the window member.

On the other hand, if the polyurethane resin constituting the polishing layer is not added with carbon black, the film formability is deteriorated, and it is difficult to obtain a uniform foam shape.

Accordingly, it is an object of the present invention to provide a polishing pad for finishing which can achieve polishing which has less of the above-mentioned disadvantages and which is less abrasive.

Further, an object of the present invention is to provide a polishing pad for finishing which realizes polishing with less polishing damage and has an end point detection region without liquid leakage.

The present invention solves the above problems by the following polishing pad and a method for producing the same.

(1) A polishing pad which is a polishing pad having a polyurethane resin film as a polishing layer on a film-forming substrate, wherein the polishing pad comprises a polishing slurry holding portion and a polishing slurry. In the material flow path portion, the polishing slurry holding portion has air bubbles, and the polishing slurry flow path portion does not have air bubbles, and the total mass (solid content mass) of the polyurethane resin film is the above. The polishing layer contains 0.5% by mass to 6% by mass of hydrophobic spherical cerium oxide.

(2) The polishing pad according to (1) above, wherein at least a part of the polishing slurry flow path portion has a light-transmitting region having an absorbance to visible light of less than 60%.

(3) The polishing pad according to the above (1) or (2), wherein the urethane resin has a flow initiation temperature of 220 ° C or lower.

(4) The polishing pad according to any one of (1) to (3) above, wherein the hydrophobic spherical cerium oxide is cerium oxide whose surface is alkylated.

(5) A method for producing a polishing pad, which is a method for producing a polishing pad having a polyurethane resin film as a polishing layer on a film-forming substrate, wherein the method for producing the polishing pad is characterized in that a polymerization is formed a resin solution obtained by dissolving a urethane resin and a hydrophobic spherical cerium oxide in an amount of 0.5% by mass to 6% by mass based on the total mass (solid content) of the polyurethane resin film in a solvent The resin solution is formed on the film-forming substrate by a wet coagulation method to form a polishing layer, and a part of the polishing layer is embossed to form a bubble-free polishing slurry flow path portion.

According to the polishing pad of the present invention and the method for producing the same, localized presence, agglomeration, and the like of insoluble components caused by carbon black are alleviated, and polishing damage can be reduced. Further, by including the hydrophobic spherical cerium oxide, stable film formation can be performed even without carbon black or other foaming control aid or film-forming stabilizing aid.

In addition, since the polishing pad of the present invention does not contain carbon black and has no air bubbles in the polishing slurry flow path portion, the flow path portion is translucent, thereby exhibiting an effect of confirming the polishing end point without cutting a part of the polishing layer. .

1 shows a scanning electron microscope of a flow path portion of a polishing pad of Example 1. (Scanning Electron Microscope, SEM) photograph (30 times).

Fig. 2 is a SEM photograph (200 times) of the polishing pad of Example 2 after film formation.

Fig. 3 is a SEM photograph (200 times) of the polishing pad of Comparative Example 3 after film formation.

Hereinafter, embodiments for carrying out the invention will be described.

1. polishing pad

An embodiment of the polishing pad of the present invention is a polishing pad having a polyurethane film as a polishing layer on a film-forming substrate, the polishing pad being characterized by:

The polishing layer includes a polishing slurry holding portion and a polishing slurry flow path portion, and the polishing slurry holding portion has air bubbles. On the other hand, the polishing slurry flow path portion does not have air bubbles.

Further, the polishing layer contains 0.5% by mass to 6% by mass of hydrophobic spherical cerium oxide with respect to the total mass of the polyurethane resin film.

In the polishing pad of the present invention, the film-forming substrate is a material that functions as a substrate of the polishing pad, and can be used without any particular limitation as long as it is a substrate generally used in the art. As an example, a flexible polymer film such as a polyester film or a polyolefin film, a nonwoven fabric to which an elastic resin is impregnated, and the like are used, and among them, a polyester film is preferably used. The thickness of the substrate is preferably 250 μm or less, more preferably 50 μm to 250 μm. In addition, a film-forming substrate having a matte finish (a technique of projecting (spraying) fine sand on the surface of the film to impart irregularities to the surface) may be used as needed.

The polishing layer of the polishing pad of the present invention contains a polyurethane resin as a main component. In the present specification, the term "main component" as used herein means that it is contained in an amount of 50% by mass or more, and more preferably 80% by mass or more, based on the dry mass of the film. It is preferably contained in an amount of 90% by mass or more, and most preferably consists of a polyurethane resin.

The kind of the polyurethane resin is not particularly limited, and may be selected from various polyurethane resins depending on the purpose of use. For example, a polyester type, a polyether type, or a polycarbonate type resin can be used.

Examples of the polyester-based resin include polyester polyols such as ethylene glycol or butylene glycol and adipic acid, and diphenylmethane-4. A polymer of a diisocyanate such as 4'-diisocyanate (diphenylmethane-4, 4'-diisocyanate). Examples of the polyether-based resin include polyether polyols such as polytetramethylene ether glycol or polypropylene glycol, and isocyanates such as diphenylmethane-4,4'-diisocyanate. Condensate. Examples of the polycarbonate resin include a polycarbonate polyol and a polymer such as an isocyanate such as diphenylmethane-4,4'-diisocyanate. These resins may be sold under the trade name "CRISVON" manufactured by DIC Co., Ltd., or "SANPRENE" manufactured by Sanyo Chemical Industries Co., Ltd., and "RESAMINE" manufactured by Daisei Seiki Co., Ltd. Resins obtained on the market can also be self-manufactured with resins having desired properties.

In the case where the polishing layer of the present invention contains a polyurethane resin, for example, it is a thickness of 0.3 mm to 3.0 mm, and more preferably a thickness of 0.3 mm to 2.0 mm.

In the present invention, the flow initiation temperature of the polyurethane resin is preferably 220 ° C or lower, more preferably 150 ° C to 220 ° C. When the embossing process is performed in order to produce the polishing slurry flow path portion of the polishing layer, if it is outside the above range, the voids (bubbles) of the hydrophobic spherical cerium oxide and the resin are not completely filled. Unable to ensure transparency.

The abrasive layer package of the present invention is relative to the total mass of the polyurethane resin film The hydrophobic spherical cerium oxide is contained in an amount of 0.5% by mass to 6% by mass, preferably 0.5% by mass to 5% by mass of the hydrophobic spherical cerium oxide. When it is less than 0.5% by mass, the foaming structure is insufficient and the film formation is unstable, which is not preferable. On the other hand, when it exceeds 6% by mass, the aggregation becomes excessive and the defects increase, which is not preferable.

The average particle diameter of the hydrophobic spherical cerium oxide is, for example, preferably 5 nm to 55 nm, more preferably 5 nm to 25 nm.

Cerium oxide has various crystal forms, and is typically low-temperature quartz (trigonal), high-temperature quartz (hexagonal, so-called crystal), tridymite (ortramedral, hexagonal), Cristobalite (orthogonal system, cubic crystal system), in addition to high pressure metamorphosis, there are coesite (coesite, monoclinic system), heavy meteorite (stishovite) (orthogonal system, rutile (rutile) structure) and so on. In addition, there are amorphous quartz glass, in addition to colloid-like silica gel (colloidal silica), orthorhombic vermiculite (Keatite) which can be produced under hydrothermal conditions. (also known as yttrium oxide K; tetragonal system), fibrous yttrium oxide W having a siloxane chain by oxidation of SiO, fumed silica, etc., in the present invention, From the viewpoint of the foaming aid and the reduction of aggregation, it is particularly preferred to be a spherical cerium oxide selected from the group consisting of smoked or colloidal cerium oxide.

Further, in the present invention, the surface of the spherical cerium oxide is hydrophobic. The method of hydrophobizing the surface of the cerium oxide is not particularly limited, and a method of imparting hydrophobicity to the surface of cerium oxide is suitably employed. For example, the surface may be subjected to alkylation treatment to impart hydrophobicity. The alkyl group is usually an alkyl group having a carbon number of about 1 to 20, and specific examples thereof include methyl (methyl), ethyl (ethyl), propyl (propyl), and butyl ( Butyl) is a lower alkyl group having 1 to 4 carbon atoms, an aminopropyl group, an octadecyl group or the like. In this embodiment, A method of alkylation treatment using a methyl group. The method for producing cerium oxide is produced by subjecting cerium tetrachloride to high temperature hydrolysis in an oxyhydrogen flame. The produced cerium oxide is subjected to a dehydrochlorination step and a cooling step to adjust the bulk density.

The degree of hydrophobicity is expressed by dropping methanol in water and M value (vol. %) as a methanol concentration when the cerium oxide is completely wet. The larger the value, the higher the hydrophobicity. The M value (vol.%) is preferably from 30 to 80, more preferably from 40 to 70.

The polishing layer of the present invention may further contain an additive such as a film forming aid or a foaming inhibiting aid in addition to the polyurethane resin and the hydrophobic spherical cerium oxide. Among them, in order to ensure the light transmittance of the polishing slurry flow path portion, the polishing layer of the present invention preferably contains substantially or completely no carbon black.

The additive is preferably selected from the group consisting of a film forming aid and a foaming inhibiting aid.

As a film-forming adjuvant, a hydrophobic active agent etc. are mentioned. Examples of the hydrophobic active agent include polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, and perfluoroalkyl epoxy. a non-ionic surfactant such as a perfudoalkyl ethylene oxide adduct, a glycerine fatty acid ester, a propylene glycol fatty acid ester, or an alkyl carboxylic acid ( Anion surfactant such as alkyl carboxylic acid).

Examples of the foaming suppressing aid include a hydrophilic active agent and the like. Examples of the hydrophilic active agent include an anionic surfactant such as a carboxylate, a sulfonate, a sulfate or a phosphate.

In the case of adding a filming aid as an additive, relative to the polyamine group The total mass (solid content) of the acid ester resin film is preferably 0.2% by mass to 10% by mass. When the foaming inhibiting aid is added as an additive, it is preferably 0.2% by mass to 10% by mass based on the total mass (solid content) of the polyurethane resin film.

The polishing layer of the present invention includes a polishing slurry holding portion and a polishing slurry flow path portion.

In the present specification, the polishing slurry means a polishing slurry containing an abrasive and other additives used when polishing a surface to be polished such as a wafer using a polishing pad.

The polishing slurry holding portion means a region having the function of polishing the original surface of the surface to be polished by holding the polishing slurry containing the polishing agent or the like.

The polishing slurry flow path portion means a groove region for supplying a polishing slurry to the polishing pad and the surface to be polished. Usually, the groove width is 0.005 mm to 3.0 mm, the groove depth is 0.1 mm to 2.0 mm, and the polishing slurry holding portion (land) is 0.1 mm to 5.0 mm. The polishing surface of the polishing pad is arranged in a lattice shape or a concentric shape. However, the invention is not limited thereto. It suffices that it has a function of supplying the slurry to the polishing surface during polishing or discharging the slurry from the polishing surface.

The area occupied by the polishing slurry holding portion in the polishing layer is preferably from 30% to 90%, more preferably from 40% to 85%.

In the polishing layer of the polishing pad of the present invention, the polishing slurry holding portion has bubbles, whereas the polishing slurry flow path portion does not have bubbles. Moreover, it is preferable that the polishing slurry holding portion and the polishing slurry flow path portion are integrally formed of the same polyurethane resin film.

The polishing layer of the present invention is a polyurethane film formed by a usual wet coagulation method, and thus has a gas formed by a wet coagulation method. bubble. That is, the characteristic cross section obtained by the wet coagulation method has tear-like continuous bubbles.

On the other hand, since the polishing slurry flow path portion is formed by embossing after forming the polyurethane resin film, voids (bubbles) between the hydrophobic spherical cerium oxide and the resin are filled, thereby There are essentially no bubbles. Regarding the presence or absence of air bubbles, an SEM or a Charge Coupled Device (CCD) can be used to visually confirm the image from the cross section.

At least a part or all of the bubble-free polishing slurry flow path portion may be used as a light-transmitting region for optically and visually detecting the polishing end point. The absorbance of the light-transmitting region is preferably less than 60%, more preferably less than 40%, and still more preferably less than 10%. If the absorbance is 60% or more, the detection accuracy is lowered, which is not preferable.

In the present invention, the solidification value of the polyurethane resin (water as a poor solvent) is preferably in the range of 8 to 20, more preferably 10 to 20.

The solidified value is a diluted resin solution obtained by diluting a solvent used in the resin-containing solution of the following procedure so that the resin containing the resin solution is 1% by mass, and the temperature of the solution is adjusted to 25 At °C, the stirring was carried out by a stirrer, and a poor solvent at 25 ° C was added dropwise to obtain the amount of dripping water (ml) required for the gelation of the polyurethane resin and the disappearance of white turbidity. In the present invention, a poor solvent can be defined as a solvent which lowers solubility. Examples of the poor solvent for the polyurethane resin include water, a lower alcohol, and a ketone having a low carbon number, and water is preferred.

When the solidification value of the polyurethane resin is in the above range, the affinity with the slurry is high and the slurry circulation is smooth, which is preferable.

Further, the polyurethane resin film of the present invention preferably has a Shore A hardness. It is 40° or less, more preferably 10° to 40°.

When the A hardness is less than the above range, the elasticity becomes extremely large, so that the mat itself becomes large and deformed when it comes into contact with the object to be polished, and the flattening performance is deteriorated. On the other hand, if it is larger than the above range, it lacks elasticity, resulting in defects.

Further, the number of foaming of the polyurethane film of the present invention is preferably 100 pieces/mm ² or more, more preferably 100 pieces/mm ² to 500 pieces/mm ² . In the present specification, the term "number of foaming" means the number of bubbles per surface area of the polishing layer (after the grinding treatment). The "number of foaming" can be measured, for example, by using an electron microscope or the like to enlarge the surface and using an image processing software.

The ratio of the opening area of the polyurethane film in the polishing pad of the present invention is preferably in the range of 20% or more, more preferably 25% or more. In the present specification, the ratio of the opening area means a ratio (%) of the opening area to the total area of the surface of the polishing layer (after the grinding treatment). The measurement of the opening area ratio (%) can be obtained, for example, from the area of the opening (bubble) in a certain area obtained by observation with a scanning electron microscope.

The average opening diameter of the polyurethane film in the polishing pad of the present invention is preferably in the range of 20 μm to 50 μm. When the average opening diameter is within the above range, polishing with high surface quality can be performed. In the present specification, the average opening diameter is obtained by using a microscope (VH-6300, manufactured by KEYENCE) to enlarge the range of the pad surface by about 1.3 mm square (excluding the groove or embossed portion) to Observation was performed at 175 times, and the obtained image was binarized by an image processing software (Image Analyzer V20LAB Ver. 1.3, manufactured by Nikon) to confirm the number of bubbles, and The area of each bubble is calculated as the projected area diameter and its average value (average bubble diameter). In addition, will The cutoff value (lower limit) of the bubble diameter was set to 10 μm, and the noise component was excluded.

The polyurethane resin of the present invention preferably has a resin modulus of from 1 MPa to 20 MPa, more preferably from 3 MPa to 10 MPa. The resin modulus is an index indicating the hardness of the resin, and is a value obtained by dividing the load applied by stretching the non-foamed resin film by 100% (when it is stretched to twice the original length) by the unit area (hereinafter Sometimes called 100% modulus). The higher the value, the harder the resin. When the resin modulus is in the above range, the effect of polishing the object to be polished with high efficiency and high quality can be obtained by the appropriate elastic properties required for the polishing pad. When the resin modulus is too low, the surface of the polishing pad excessively follows the unevenness on the surface of the object to be polished, and it is difficult to obtain polishing flatness. Conversely, if the resin modulus is too high, defects are likely to occur, which is not preferable.

The polishing pad of the present invention may have a single layer structure of an abrasive layer including only a polyurethane film, or may include other layers (lower layer, support layer) attached to the surface of the polishing layer opposite to the polishing surface. Made of multiple layers. The characteristics of the other layer are not particularly limited, and it is preferable that a layer harder than the polishing layer (high A hardness) is bonded to the opposite surface side of the polishing layer. By providing a layer harder than the polishing layer, it is possible to prevent the fine irregularities of the polishing plate from affecting the shape of the polishing surface, and the polishing flatness is further improved. Further, the rigidity of the polishing cloth is generally increased, whereby wrinkles and the like are generated when the polishing cloth is attached to the fixing plate.

Further, in the present invention, when the polishing pad has a multilayer structure, it is only necessary to use a double-sided tape, an adhesive or the like, and it is necessary to press and fix the plurality of layers while pressing. The double-sided tape or the adhesive used at this time is not particularly limited, and can be arbitrarily selected from the double-sided tape or the adhesive known in the art.

In addition, the polishing pad of the present invention can perform surface grinding (buffing) Treatment) or the surface is subjected to a slice process to remove it.

2. Method for manufacturing polishing pad

The method for producing a polishing pad of the present invention is a method for producing a polishing pad having a polyurethane resin film as a polishing layer on a film-forming substrate, and includes the following steps.

In the step (a), the polyurethane sulphuric acid is dissolved in the polyurethane resin and the hydrophobic globular cerium oxide in an amount of 0.5% by mass to 6% by mass based on the total mass (solid content) of the urethane resin film. a resin solution obtained in a solvent; in the step (b), the resin solution is formed on the film-forming substrate by a wet coagulation method to form a polyurethane film; and the step (c) is performed by A part of the above-mentioned polyurethane film is embossed to produce a bubble-free slurry flow path portion.

The method of the present invention may further perform a step of performing surface grinding on the surface side formed on the surface of the film-formed polyurethane resin film between the steps (b) and (c).

Each step will be described.

Further, the film-forming substrate, the polyurethane resin, and the hydrophobic spherical cerium oxide in the above method are the same as those described in the description of the polishing layer.

Examples of the solvent for dissolving the polyurethane resin and the hydrophobic spherical cerium oxide include a water-miscible organic solvent. The organic solvent is not particularly limited as long as it can dissolve the polyurethane resin and is water-miscible. As an example, N,N-Dimethyl Formamide (DMF), N,N-Dimethyl Acetamide (DMAc), tetrahydrofuran (N,N-Dimethyl Acetamide, DMAc) Tetrahydrofuran, THF), Dimethyl Sulfoxide (DMSO), N-Methylpyrrolidone (N-Methylpyrrolidone, NMP), acetone (acetone), and the like. Among these, DMF or DMAc can be preferably used.

The concentration of the polyurethane resin in the above-mentioned polyurethane solvent soluble solvent is preferably 15% by mass to 50% by mass, more preferably 20% by mass to 40% by mass. When the concentration is within the above range, the polyurethane-containing solution has moderate fluidity and can be uniformly applied to the film-forming substrate in the subsequent coating step.

A resin solution containing a polyurethane resin and a predetermined amount of hydrophobic spherical cerium oxide is formed on a film-forming substrate by a wet coagulation method.

The wet coagulation method is a method of forming a film on a film-forming substrate from a solution containing a polyurethane resin film-forming composition (containing at least a polyurethane resin and hydrophobic spherical cerium oxide). The method is a film forming method including a coating step, a solidifying step, and a washing and drying step.

In the coating step, the solution containing the polyurethane resin film-forming composition is continuously coated by a knife coater, a reverse coater, or the like in such a manner as to become substantially uniform. The step of laying on a film-forming substrate.

The solidification step is a step of immersing a substrate coated with a solution containing a composition for forming a polyurethane resin film in a coagulating liquid containing water as a poor solvent for the polyurethane resin as a main component. .

As the coagulation liquid, a mixed solution of water, water, and a polar solvent such as DMF is used. Among them, a mixed solution of water or water and a polar solvent such as DMF is preferred. Examples of the polar solvent include water-miscible organic solvents for dissolving the polyurethane resin, such as DMF, DMAc, THF, DMSO, NMP, and acetone. Further, the concentration of the polar solvent in the mixed solvent is preferably from 0.5% by mass to 30% by mass.

The temperature of the coagulating liquid or the immersion time is not particularly limited, and for example, it may be immersed at 5 ° C to 80 ° C for 5 minutes to 60 minutes.

The washing and drying step is a step of washing and drying the film-form polyurethane resin obtained by solidifying it by a coagulation bath from the film-forming substrate or without peeling off.

The organic solvent remaining in the polyurethane resin is removed by a cleaning treatment. Water is used as a washing liquid used for washing.

After washing, the polyurethane resin is dried. The drying treatment may be carried out by a method previously employed. For example, it may be dried in a dryer at 80 ° C to 150 ° C for about 5 minutes to 60 minutes. The film-forming resin after drying is wound into a roll shape. Through the above steps, a polyurethane film can be obtained.

It is also possible to perform surface grinding (polishing treatment) on the surface layer side formed on the surface of the obtained polyurethane resin film. That is, the substantially flat surface of the pressure-bonding jig can be pressure-bonded to the surface of the film-forming resin opposite to the surface layer, and the surface layer side can be subjected to a grinding treatment by sandpaper or a diamond buffing roll. The particle size number of the sandpaper or diamond polishing roller used can be selected and used within #100~#400. Thereby, a part of the cells are opened at the polishing surface to form an opening, and the thickness of the polyurethane resin film can be made uniform.

As described above, by embossing a part of the obtained polyurethane resin film, a bubble-free polishing slurry flow path portion can be produced.

The embossing process is a method in which a mold having an embossed pattern is sandwiched between two metal pressure plates, and a resin sheet bonded to a resin substrate is pressed for a predetermined time at a constant temperature and pressure. . When the mold is removed, irregularities corresponding to the embossed shape formed on the side of the polishing surface are formed. The processing conditions may be appropriately determined depending on the properties of the resin to be used. For example, the embossing die may be heated to a temperature of from 140 ° C to 180 ° C and pressurized at a pressure of from 4.5 MPa to 9.0 MPa for 120 seconds to 180 seconds. .

The shape of the embossing is not particularly limited, and examples thereof include a lattice shape, a concentric shape, and a radial shape.

As described above, in the present invention, in order to produce a bubble-free flow path portion by embossing, the flow initiation temperature of the polyurethane resin is preferably 220 ° C or lower, more preferably 150 ° C to 220 ° C. . The reason for this is that if it is outside the above range, voids (bubbles) between the hydrophobic spherical cerium oxide and the resin are not filled, and the bubbles cannot be sufficiently removed.

Further, in the present invention, the surface and/or the back surface of the polyurethane resin film may be subjected to a grinding treatment as needed or the substrate and/or the adhesive layer may be bonded to the polishing layer, and the light transmitting portion may be further provided. .

The method of the grinding treatment is not particularly limited, and the grinding can be carried out by a known method. Specifically, grinding by sandpaper is mentioned.

In the case of performing the grinding, the grinding is performed in a range of 50 μm to 300 μm, preferably about 50 μm to 250 μm.

When the polishing pad of the present invention is used, the polishing pad is attached to the polishing platen of the polishing machine so that the polishing surface of the polishing layer faces the object to be polished. Next, while the slurry is supplied, the polishing platen is rotated to polish the machined surface of the object to be polished.

Examples of the object to be polished which is processed by the polishing pad of the present invention include bare enamel, a semiconductor device, a magnetic disk, and the like. Among them, the polishing pad of the present invention is particularly suitable for finishing polishing of a semiconductor device, and thus is preferable.

[Examples]

[Example 1]

As shown in Table 1 below, a polyester-based polyamine containing 100% modulus of the resin 60 parts of a solution of a urethane resin (30 parts) and DMF (70 parts) was additionally added with 60 parts of DMF and hydrophobic spherical cerium oxide (average particle diameter: 7 nm, hydrophobicity: M value (vol. %) = 48) 0.9 parts (3% by mass based on the total mass of the polyurethane resin) and mixed, whereby a resin-containing solution was obtained.

The obtained resin-containing solution was cast on a polyester film (thickness: 188 μm). Thereafter, the polyester film in which the resin-containing solution is cast is immersed in a coagulation bath (the coagulating liquid is water), and the resin-containing solution is solidified, washed, and dried to obtain a resin film.

The surface layer side formed on the surface of the obtained resin film was subjected to a grinding treatment (grinding amount: 200 μm). Then, a part of the resin film is embossed by a grid-like mold to prepare a polishing slurry flow path portion (see FIG. 1) without bubbles, and a polishing pad in which a resin film and a double-sided tape are bonded is obtained. In addition, in Table 1, unless otherwise indicated, the "part" means a mass part.

Resin 1: polyester urethane resin, 100% modulus 7.8 MPa, solidification value 13.3

Resin 2: polyester urethane resin, 100% modulus 6.0 MPa, solidification value 10.8

[Example 2 to Example 6 and Comparative Example 1 to Comparative Example 3]

Conditions other than the type and amount of the resin (described in Table 1) were set to be the same as in Example 1, and a polishing pad was produced.

In Comparative Example 1, a polishing pad was produced in the same manner as in Example 1 except that carbon black was added instead of the hydrophobic spherical cerium oxide so as to be 7.0% by mass based on the total mass of the polyurethane resin. In Comparative Example 2, 8.0% by mass of hydrophobic spherical cerium oxide was added to the total mass of the polyurethane resin, and in Comparative Example 3, A polishing pad was produced in the same manner as in Example 1 except that hydrophobic spherical cerium oxide was added.

<Physical evaluation>

(Method for measuring the number of foaming)

The average bubble diameter (μm) and the number of bubbles per 1 mm ² were observed by a microscope (VH-6300, manufactured by KEYENCE) to enlarge the range of the pad surface by about 1.3 mm square (except for the embossed portion) to 175 times. The image processing software (Image Analyzer V20LAB Ver. 1.3, manufactured by Nikon) binarized the obtained image to confirm the number of bubbles, and calculated the projected area diameter and its average value from the area of each bubble ( Average bubble diameter). Further, the critical value (lower limit) of the bubble diameter was set to 10 μm to exclude the noise component.

(Shore A hardness)

In the measurement of the Shore A hardness, a sample piece (10 cm × 10 cm) was cut out from the foam sheet, and a plurality of sample pieces were stacked so as to have a thickness of 4.5 mm or more, and a type A hardness meter (Japanese Industrial Standard, JIS K) was used. 7311) The measurement was performed. For example, when one sample piece has a thickness of 1.4 mm, four pieces are overlapped and measured.

(average opening diameter and opening area ratio)

The average opening diameter (μm) and the opening area ratio (%) were measured by a scanning electron microscope (manufactured by JEOL Ltd., JSM-5500LV) to enlarge the range of about 5 mm square to 1000 times and observe 9 places. This image was binarized by an image processing software (Image Analyzer V20LAB Ver. 1.3, manufactured by Nikon), and the number of openings (number of bubbles) was confirmed, and the projection was calculated from the area of each opening (bubble). The area diameter and its average value are taken as the average opening diameter. In addition, the area ratio of the opening (bubble) in the range of 5 mm square is calculated. It is the opening area ratio (%). Further, the critical value (lower limit) of the bubble diameter was set to 11 μm to exclude the noise component.

<grinding test>

The polishing pads of the respective examples and comparative examples were subjected to polishing treatment under the following polishing conditions, and the polishing rate, the polishing uniformity, and the presence or absence of defects were measured. As the object to be polished, a substrate in which an insulating film having a thickness of 1 μm was formed on a 12-inch germanium wafer by tetraethoxysilane by chemical vapor deposition (CVD) (uniformity ( CV%) is 13%). Grinding was performed on the basis of 25 substrates, and the stability of the polishing rate and the polishing uniformity of the first, tenth, and twenty-th sheets was evaluated.

Grinder EBARA F-REX300

Grinding head GII

Slurry Planar Company Slurry

Work piece (work) 300mm SIO2 (tetraethyl orthosilicate (TEOS))

Pad diameter 740mm

The mat is broken 9N×30 minutes, the diamond dresser is 54rpm, the fixing speed is 80rpm, and the ultra-pure water is 200ml/min.

Grinding plate rotation speed 70rpm, grinding head rotation speed 71rpm, slurry flow rate 200ml/min, grinding time 60 seconds

(with or without defects)

In the evaluation of the defect, 25 substrates were sequentially polished three times in sequence, and the unpatterned wafer surface inspection device (KLA-Tencor) was used for the five substrates from the 21st to the 25th after the polishing process. Highly sensed by the company, Surfscan SP1DLS) The measurement was performed in a mode to evaluate the presence or absence of defects on the surface of the substrate.

(grinding rate)

The polishing rate is the amount of grinding per minute in terms of thickness (Å). The average value of the thickness measurement results of each of the insulating films of the substrate before and after the polishing was determined. Further, the thickness measurement was carried out in a DBS mode of an optical film thickness film tester (KLA-Tencor Co., Ltd., ASET-F5x).

(grinding uniformity)

The polishing uniformity is a variation (standard deviation ÷ average value) (%) of the polishing amount (thickness) obtained from the thickness measurement results before and after the 17 polishing processes measured at the polishing rate. The polishing uniformity is usually preferably less than 4.0.

(absorbance)

The absorbance of the embossed portion was measured by the following method.

The absorbance of the polishing slurry flow path portion was measured for each of the polishing pads of the examples and the comparative examples.

Measuring device: UV-2450 (Shimadzu Corporation)

Wavelength: 200nm~800nm

<Result>

Among the polishing pads obtained in Examples 1 to 6 and Comparative Examples 1 to 3, the cross-sectional photograph of Example 1 is shown in Fig. 1, and the evaluation results are shown in Tables 1 and 2. Further, in Tables 1 and 2, the flow initiation temperature is referred to as Celsius (°C).

It was confirmed that the polishing pad of Example 1 was able to achieve stable film formation without adding a foaming control aid or a film-forming stabilizer, by adding 3 mass% of hydrophobic spherical cerium oxide. In addition, by using hydrophobic spherical cerium oxide, it is suppressed during film formation and during polishing. The condensation from time also suppresses the number of defects. Further, by suppressing the absorbance of the embossed portion by a combination with a resin having a flow initiation temperature of 220 ° C or lower, a part of the flow path portion can be formed into a light-transmitting region. The effects were similarly observed in the second to sixth embodiments.

In Comparative Example 1, 7.0% by mass of carbon black was added instead of the hydrophobic spherical cerium oxide. Foaming or film formation is stable, but produces a large number of defects. Further, the addition of carbon black causes the embossed portion to be non-transparent, and a translucent region cannot be formed in a part of the flow path portion.

Comparative Example 2 was produced under the same conditions as in Example 1 except that 85% by mass of hydrophobic spherical cerium oxide was added. However, since the amount of addition is large, aggregation becomes excessive, and as a result, uniformity of the resin film is hindered (Fig. 2). In addition, the generation of cohesiveness leads to the generation of defects.

Comparative Example 3 was produced under the same conditions as in Example 1 except that the hydrophobic spherical cerium oxide was not added. However, the film formation is unstable, and the variation in the density of foaming in the mat surface is increased (Fig. 3). Therefore, as a result, variations in slurry retention are exhibited, and uniformity is also largely lowered.

Claims (5)

A polishing pad which is a polishing pad having a polyurethane resin film as a polishing layer on a film-forming substrate, wherein the polishing pad is characterized in that the polishing layer includes a polishing slurry holding portion and a polishing slurry flow path The polishing slurry holding portion has air bubbles, and the polishing slurry flow path portion does not have air bubbles, and the polishing layer includes the total mass (solid content mass) of the polyurethane resin film. 0.5% by mass to 6% by mass of hydrophobic spherical cerium oxide. The polishing pad according to claim 1, wherein at least a part of the polishing slurry flow path portion has a light-transmitting region having an absorbance to visible light of less than 60%. The polishing pad of claim 1 or 2, wherein the polyurethane resin has a flow initiation temperature of 220 ° C or less. The polishing pad according to claim 1 or 2, wherein the hydrophobic spherical cerium oxide is cerium oxide whose surface is alkylated. A method for producing a polishing pad, which is a method for producing a polishing pad having a polyurethane film as a polishing layer on a film-forming substrate, wherein the method for producing the polishing pad is characterized in that a polyamine group is formed a resin solution obtained by dissolving a hydrophobic spherical cerium oxide in an amount of 0.5% by mass to 6% by mass based on the total mass (solid content) of the polyurethane resin film in a solvent; In the wet coagulation method, the resin solution is formed on a film-forming substrate to form a polishing layer, and a part of the polishing layer is embossed to form a bubble-free polishing slurry flow path portion.