TWI546315B - Polishing pad and manufacturing method thereof - Google Patents

Description

Polishing pad and method of manufacturing same Technical field

The present invention relates to a material which is stable and high in polishing efficiency, such as an optical material such as a lens or a mirror, a glass substrate for a hard disk, an aluminum substrate, and a general metal polishing process, which requires high surface flatness. The flattening of the polishing pad. The polishing pad of the present invention is suitable for, in particular, planarizing a germanium wafer and a device on which an oxide layer, a metal layer or the like is formed, or even a laminate. A planarization step prior to forming the oxide layer or metal layer.

Background technique

A material which is required to have a high degree of surface flatness is exemplified by a disk of a single crystal crucible which is called a tantalum wafer for manufacturing a semiconductor integrated circuit (IC, LSI). In the steps of manufacturing IC, LSI, etc., in order to form a semiconductor junction that can be trusted for various film formation, in the layering. In each step of forming an oxide layer or a metal layer, it is required to planarize the surface of the germanium wafer with high precision. In such a polishing finishing step, the polishing pad is generally fixedly connected to a rotatable supporting disk called a platform, and a workpiece such as a semiconductor wafer is fixedly connected to the polishing head. And, by the action of both sides, the platform and the polishing head The relative speed is generated, and the grinding operation is actually performed by continuously supplying the slurry containing the abrasive grains to the polishing pad.

In terms of polishing characteristics of the polishing pad, it is required that the object to be polished has excellent flatness (flatness) and in-plane uniformity, and the polishing rate is fast. The flatness and in-plane uniformity of the object to be polished can be improved to some extent by the high elastic modulus polishing layer. Further, the polishing rate can be improved by increasing the amount of the slurry after the polishing layer is used as a foam, or by increasing the durability of the slurry after the polishing layer is hydrophilic.

For example, Patent Document 1 proposes a composition for a polishing pad characterized in that: in order to enhance the wettability of the polishing pad to water, (A) a crosslinked elastomer, (B) is selected from a carboxyl group and an amine. a substance having at least one functional group in a group consisting of a hydroxyl group, a hydroxyl group, an epoxy group, a sulfonic acid group, and a phosphoric acid group, and a water-soluble substance, and the (A) crosslinked elastic system is crosslinked by 1,2-poly A polymer of butadiene.

Further, Patent Document 2 proposes a polishing pad in which a urethane resin containing a compound having a hydrophilic group copolymerized with a hydrophilic group is easily dissolved in a polishing pad, and a urethane having a hydrophilic agent is contained. a polishing pad composed of an ethyl ester composition selected from the group consisting of 2,4,7,9-tetramethyl-5-decyne-4,7-diol-diethoxyethylene ether, and 2 At least one of the group consisting of 4,7,9-tetramethyl-5-decyne-4,7-diol, and the compound having the hydrophilic group is an ethylene oxide monomer.

Further, in Patent Document 3, in order to obtain a polishing pad having good flatness, in-plane uniformity, and high polishing rate, and having little change in polishing rate and excellent life characteristics, it has been proposed to use a hydrophilic isocyanate terminal prepolymer (B). In the method, the raw material component of the prepolymer (B) contains, as a raw material component of the polyurethane resin foam, ₂ parts by weight or more of ethylene oxide unit (-CH ₂ CH ₂ O-). A hydrophilic high molecular weight polyol component having a number average molecular weight of 500 or more and an isocyanate component.

Further, Patent Document 4 proposes an abrasive layer containing an organic solvent which is soluble in a resin which can dissolve the polishing layer and which contains a partially soluble polysaccharide which is insoluble or insoluble in water in order to enhance the hydrophilicity of the polishing layer. ingredient.

However, when the polishing layer is made hydrophilic, the polishing rate can be increased, but the flatness of the object to be polished is deteriorated.

Prior technical literature Patent literature

Patent Document 1: Patent No. 3826702

Patent Document 2: Patent No. 3851135

Patent Document 3: Patent No. 4189963

Patent Document 4: Patent No. 5189440

Summary of invention

An object of the present invention is to provide a polishing pad which is excellent in polishing speed and excellent in planarization characteristics, and a method for producing the same.

In order to solve the above problems, the inventors of the present invention have repeatedly reviewed the above problems. As a result, it has been found that the above problems can be solved by the following polishing pad, and the present invention has been completed.

The present invention relates to a polishing pad characterized in that it is formed as a foam of the aforementioned polyurethane resin in a polishing pad having a polishing layer composed of a polyurethane resin foam. The polyurethane resin of the material is reacted with an isocyanate group of an alkoxymethyl group-containing isocyanate represented by the following formula (1) by an amine ester group or a urea group of an isocyanate terminal prepolymer. The side chain is introduced with an alkoxy group.

(In the formula, X is OR ¹ or OH, R ¹ is independently an alkyl group having 1 to 4 carbon atoms, and R ² is an alkylene group having 1 to 6 carbon atoms.)

As described above, the present invention is characterized in that the side chain of the polyurethane resin is introduced with an alkoxy group. The alkoxypurine group present on the surface of the polishing layer is hydrolyzed by water in the slurry being ground, and a sterol group is formed on the surface of the polishing layer. The hydrophilicity of the surface of the polishing layer is enhanced by the hydrophilicity of the sterol group. As a result, the maintenance ability of the slurry can be improved, and the polishing speed can be accelerated.

On the other hand, since the alkoxy group is introduced into the side chain of the polyurethane resin, the polyurethane resin is less likely to swell by the slurry. Further, the alkoxy group present in the inside of the polishing layer is less likely to be hydrolyzed because it is less likely to come into contact with water in the slurry. Therefore, only the surface of the polishing layer can be hydrophilized, and the decrease in hardness of the entire polishing layer can be suppressed. As a result, the planarization characteristics of the polishing pad will become less likely to decrease.

The alkoxyfluorenyl-containing isocyanate 3-isocyanate propyl group Triethoxy decane.

Further, the alkoxyfluorenyl-containing isocyanate is preferably added in an amount of 1 to 10 parts by weight based on 100 parts by weight of the isocyanate-terminated prepolymer. Since the alkoxy fluorenyl group is introduced into the side chain of the polyurethane resin, hydrophilicity is exhibited by introducing a small amount of the alkoxy group. When the amount of the alkoxy group-containing isocyanate added is less than 1 part by weight, the surface of the polishing layer is not easily hydrophilized, and when it is more than 10 parts by weight, it is difficult to produce a polishing layer having excellent polishing properties.

Moreover, the present invention relates to a method for producing a polishing pad comprising mixing a first component containing an isocyanate terminal prepolymer and a second component containing a chain extender, and curing the polyurethane resin to prepare a polyurethane resin. The method for producing a polishing pad according to the step of forming a foam; wherein the step of adding a lanthanoid surfactant to the first component containing the isocyanate terminal prepolymer and allowing the lanthanoid surfactant to be relative to the first component And the total weight of the second component is 0.05 to 10% by weight, and the first component and the non-reactive gas are further stirred, and a bubble dispersion liquid in which the non-reactive gas is used as a bubble is dispersed, and the chain is extended. a second component of the agent is mixed with the bubble dispersion, and is cured to form a polyurethane foam, and the second component contains an alkoxy group represented by the following formula (1). Isocyanate.

(In the formula, X is OR ¹ or OH, R ¹ is independently an alkyl group having 1 to 4 carbon atoms, and R ² is an alkylene group having 1 to 6 carbon atoms.)

According to the aforementioned production method, an allophanate structure or a biuret structure can be formed by reacting an amino ester group or a urea group of an isocyanate terminal prepolymer with an isocyanate group of an alkoxy group-containing isocyanate to form a side. The chain is introduced with an alkoxymethyl group-containing polyurethane resin.

The alkoxyfluorenyl-containing isocyanate is preferably 3-isocyanate propyltriethoxysilane.

The amount of the alkoxyfluorenyl-containing isocyanate to be added is preferably from 1 to 10 parts by weight based on 100 parts by weight of the isocyanate-terminated prepolymer.

Still further, the present invention relates to a method of fabricating a semiconductor device comprising the step of polishing a surface of a semiconductor wafer using the polishing pad.

The polishing pad of the present invention is excellent in polishing rate and excellent in planarization characteristics. Further, in the polishing pad of the present invention, the surface of the polishing layer is changed to hydrophilicity by the slurry during the polishing operation, and aggregation of the abrasive grains is less likely to occur in the slurry, and scratching of the object to be polished can be effectively suppressed.

1‧‧‧ polishing pad (grinding layer)

2‧‧‧ grinding plate

3‧‧‧Abrasive (slurry)

4‧‧‧Abrased object (semiconductor wafer)

5‧‧‧Support table (grinding head)

6,7‧‧‧Rotary axis

Figure 1 is a view showing an example of a polishing apparatus used in CMP polishing. A schematic diagram.

Form for implementing the invention

The polishing pad of the present invention may be a polishing layer composed only of a polyurethane foam, or a laminate of a polishing layer and another layer (for example, a buffer layer or the like).

The polyurethane resin for forming a polyurethane foam according to the above, the amino ester group or the urea group of the isocyanate terminal prepolymer and the alkane represented by the following formula (1) The reaction of an isocyanate group of an isocyanate of an oxo group introduces an alkoxy group in the side chain.

(In the formula, X is OR ¹ or OH, R ¹ is independently an alkyl group having 1 to 4 carbon atoms, and R ² is an alkylene group having 1 to 6 carbon atoms.)

The polyurethane resin is subjected to reaction hardening of a polyurethane raw material composition containing an isocyanate terminal prepolymer, an alkoxyfluorenyl group-containing isocyanate represented by the above formula (1), and a chain extender. The body is better.

The isocyanate terminal prepolymer is obtained by reacting a prepolymer raw material composition containing an isocyanate component, a polyol component (high molecular weight polyol, a low molecular weight polyol) or the like.

The isocyanate component is not particularly limited, and a compound well known in the field of polyurethanes can be used. Examples of the isocyanate component include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 4,4. Aromatic diisocyanate such as '-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, meta-phenylene diisocyanate, p-quinone diisocyanate, m-decyl diisocyanate; ethylene diisocyanate, Aliphatic diisocyanate such as 2,2,4-trimethylhexamethylene diisocyanate or 1,6-hexamethylene diisocyanate Ester; 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, alicyclic diisocyanate such as norbornene diisocyanate, and the like. These may be used alone or in combination of two or more.

The isocyanate component may be a trifunctional or higher polyfunctional polyisocyanate compound in addition to the above-described diisocyanate compound. As the polyfunctional isocyanate compound, a series of diisocyanate adduct compounds such as Desmodur-N (manufactured by Bayer Co., Ltd.) or Duranate (made by Asahi Kasei Kogyo Co., Ltd.) are commercially available.

A high molecular weight polyol (polyol) can be exemplified by a typical user in the technical field of polyurethane. Examples thereof include polyether polyols such as polytetramethylene ether glycol and polyethylene glycol, and representative polyester polyols such as polytetramethylene glycol adipate and polycaprolactone polyols. For example, a polyester polycarbonate polyol such as a reaction of a polyester diol of polycaprolactone with an alkylene carbonate, a methyl carbonate and a polyalcohol, and the resulting reaction is further carried out. A polyester polycarbonate polyol obtained by reacting a mixture with an organic dicarboxylic acid, a polycarbonate polyol obtained by transesterification of a polyhydroxy compound with an aromatic carbonate, or the like. These may be used alone or in combination of two or more.

The weight average molecular weight of the high molecular weight polyol is not particularly limited, but it is preferably from 500 to 3,000 from the viewpoint of the elastic properties of the obtained polyurethane resin. When the weight average molecular weight is less than 500, the obtained polyurethane resin does not have sufficient elastic properties, and it tends to become a weak polymer, and the polishing pad obtained from the polyurethane resin becomes too hard. There is a case where scratches are formed on the surface of the object to be polished. Moreover, since it is easy to wear, it is considered from the viewpoint of the life of the polishing pad. Not good. On the other hand, when the weight average molecular weight is more than 3,000, the polishing pad composed of the polyurethane resin obtained by using it becomes soft, and it is not easy to obtain a flatness which can be sufficiently satisfied.

In addition to the above high molecular weight polyols, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol may also be used in combination. , 2,3-butanediol, 1,6-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, Triethylene glycol, 1,4-bis(2-hydroxyethoxy)benzene, trimethylolpropane, glycerin, 1,2,6-hexanetriol, pentaerythritol, tetramethylolcyclohexane , methyl glucoside, sorbitol, mannitol, galactitol, sucrose, 2,2,6,6-tetrakis (hydroxymethyl)cyclohexanol, diethanolamine, N-methyldiethanolamine, and triethanolamine Equal low molecular weight polyols. Further, a low molecular weight polyamine such as ethylene diamine, toluenediamine, diphenylmethane diamine or diethylene triamine may be used in combination. Further, an alcoholamine such as monoethanolamine, 2-(2-aminoethylamino)ethanol or monopropanolamine may be used in combination. These low molecular weight polyols and low molecular weight polyamines may be used singly or in combination of two or more.

The isocyanate terminal prepolymer uses an isocyanate component, a polyol component, etc., and the equivalent ratio (NCO/H*) of the isocyanate group (NCO) to the active hydrogen (H*) is usually 1.2 to 8, in the range of 1.5 to 3. It is preferred to carry out the heating reaction.

The isocyanate terminal prepolymer has an amine ester group in the molecule, and may further have a urea group.

In the above formula (1), X is preferably OR ¹ . And, R ¹ to preferably methyl or ethyl. The alkoxyfluorenyl group-containing isocyanate represented by the above formula (1) is preferably 3-isocyanate propyltriethoxysilane.

The alkoxy group-containing isocyanate is preferably added in an amount of 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the isocyanate terminal prepolymer.

The hardening of the isocyanate terminal prepolymer uses a chain extender. The chain extender is an organic compound having two or more active hydrogen groups, and the active hydrogen group may be a hydroxyl group, a first or second amine group, or a thiol group (SH). Specifically, for example, 4,4'-methylenebis(o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4'-methylene double (2,3) -dichloroaniline), 3,5-bis(methylthio)-2,4-toluenediamine, 3,5-bis(methylthio)-2,6-toluenediamine, 3,5-dimethyl Toluene-2,4-diamine, 3,5-diethyltoluene-2,6-diamine, trimethylene glycol-di-p-aminobenzoate, 1,2-bis(2-amine Phenylthio)ethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, N,N'-di-Sec-butyl- 4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, m-diamine, N,N'-di-Sec-butyl A polyamine exemplified by a phenyl-p-diamine, an inter-phenylenediamine, a p-nondiamine or the like, or a low molecular weight polyhydric alcohol or a low molecular weight polyamine. These may be used alone or in combination of two or more.

The polyurethane foam may be produced by a well-known urethane technique such as a melt method or a solution method, but it is preferably produced by a melt method in consideration of cost, work environment, and the like.

The number of isocyanate groups of the prepolymer of the active hydrogen group (hydroxyl group, amine group) relative to the chain extender is preferably from 0.95 to 1.00, so that the amine ester group or the urea group of the prepolymer can be effectively contained. The isocyanate group of the alkoxyfluorenyl isocyanate reacts to form an allophanate structure or a biuret structure.

A method for producing a polyurethane foam, which can be added Examples of the hollow particle method, the mechanical foaming method (including the mechanical foaming method), the chemical foaming method, and the like are exemplified.

In particular, a mechanical foaming method using a fluorene-based surfactant having a copolymer of a polyalkyl siloxane and a polyether is preferred. Examples of the quinone-based surfactants include preferred compounds such as SH-192 and L-5340 (manufactured by Dow Corning Toray Silicone Co., Ltd.) and B8443 and B8465 (manufactured by GOLDSCHMIDT). The lanthanoid surfactant is preferably added in an amount of 0.05 to 10% by weight, preferably 0.1 to 5% by weight, based on the composition of the raw material of the polyurethane.

A stabilizer such as an antioxidant, a lubricant, a pigment, a filler, an antistatic agent, and other additives may be added to the polyurethane raw material composition as needed.

The polyurethane foam may be a closed cell type or a continuous cell type, but to prevent intrusion into the slurry inside the polishing layer and to prevent hydrolysis of the alkoxy group present in the polishing layer. A separate bubble type is preferred.

An example of a method of producing a fine bubble type polyurethane resin foam constituting a polishing pad (polishing layer) will be described below. The method for producing such a polyurethane resin foam has the following steps.

1) A foaming step of preparing a bubble dispersion of an isocyanate terminal prepolymer

To the isocyanate terminal prepolymer (the first component), a ruthenium-based surfactant is added, and the mixture is stirred in the presence of a non-reactive gas to form a bubble dispersion liquid in which a non-reactive gas is dispersed as a bubble. When the prepolymer is a solid at normal temperature, it is preheated to an appropriate temperature and used after melting.

2) mixing step of an alkoxyfluorenyl-containing isocyanate and a chain extender

Adding, mixing and stirring the alkoxylated group in the bubble dispersion The isocyanate and the chain extender (the second component) are used as a foaming reaction liquid.

3) Molding step

The foaming reaction liquid described above was injected into a mold.

4) Hardening step

The foaming reaction liquid flowing into the mold is heated to harden the reaction.

The non-reactive gas used for forming the bubbles is preferably non-flammable. Specifically, a rare gas such as nitrogen, oxygen, carbon dioxide, helium or argon, or a mixed gas thereof may be used as an example. The removal of moisture-laden air after drying is optimal in terms of cost.

It is not necessary to specifically limit the non-reactive gas to be dispersed in a bubble shape, and the stirring device including the first component of the lanthanoid surfactant may be a known stirring device. Specifically, a homogenizer or a dissolver may be used. A 2-axis planetary mixer is taken as an example. The shape of the stirring blade of the stirring device is not particularly limited, but it is preferable to use fine bubbles obtained by using the whisker type stirring blade.

Further, in the foaming step, stirring of the alkoxyfluorene-containing isocyanate and the chain extender in the stirring and mixing steps of the bubble dispersion is also carried out, and a different stirring device is preferably used. In particular, the stirring in the mixing step may not be agitation of the bubbles, and it is preferred to use a stirring device which does not entrap large bubbles. Such a stirring device is preferred to use a planetary mixer. The stirring device of the foaming step and the mixing step may be the same stirring device, and may be adjusted after adjusting the stirring conditions such as the rotation speed of the stirring blade as needed.

In the method for producing a polyurethane foam, foaming is carried out After the reaction liquid flows into the mold and reacts to the unflowed foam to be heated and post-heat treated, it has an effect of improving the physical properties of the foam, and is excellent. The foaming reaction liquid may be placed in a heating oven immediately after flowing into the mold, and post-heat treatment may be performed. Under such conditions, heat is not immediately transmitted to the reaction components, so the bubble diameter does not become large. It is preferable to carry out the hardening reaction under normal pressure because the shape of the bubble can be stabilized.

In the polyurethane foam, a well-known catalyst for promoting a polyurethane reaction such as a tertiary amine system can also be used. After considering the flow time of the mold flowing into the predetermined shape after the mixing step, the type and amount of the catalyst are selected.

The production of the polyurethane foam may be a batch method in which each component is measured and put into a container and stirred, or may be continuously supplied after the components and the non-reactive gas are supplied to the stirring device, and then the bubble dispersion is sent out. A continuous production method for producing molded articles.

In addition, a prepolymer which is a raw material of the polyurethane resin foam is placed in a reaction container, and then an alkoxyfluorene-containing isocyanate and a chain extender are introduced and stirred, and then poured into a mold of a predetermined size. The body may be formed into a thin sheet shape by a method of slicing the block using a planar or band saw-like microtome or in the stage of the above-mentioned mold.

The average cell diameter of the polyurethane foam is preferably from 30 to 200 μm. When it exceeds this range, the flatness (flatness) of the object to be polished after polishing tends to decrease.

The hardness of the polyurethane foam is preferably from 40 to 70 degrees in terms of Asker D hardness. When Asker D hardness is less than 40 degrees, research The flatness of the object to be polished is lowered. On the other hand, when the thickness is more than 70 degrees, the flatness is good, but the uniformity (homogeneity) of the object to be polished tends to decrease.

The specific gravity of the polyurethane foam is preferably 0.5 to 1.3. When the specific gravity is less than 0.5, the surface strength of the polishing layer is lowered, and the flatness of the object to be polished tends to decrease. Moreover, when it is more than 1.3, the number of the bubbles on the surface of the polishing layer is small, and the flatness is good, but the polishing rate tends to decrease.

The abrasive surface in contact with the polishing object of the polishing pad (abrasive layer) of the present invention has a hold. It is better to update the surface shape of the slurry. The polishing layer composed of the foam has a large number of openings on the polishing surface, and has the function of holding and renewing the slurry, and in order to more effectively perform the retention of the slurry and the renewal of the slurry, and to prevent the object to be polished It is preferable that the object to be polished is damaged by adsorption, and the surface of the polishing surface has a concavo-convex structure. The uneven structure is not particularly limited as long as it can be maintained. The shape of the slurry may be updated, for example, an XY lattice groove, a concentric circular groove, a through hole, a non-through hole, a polygonal column, a cylinder, a spiral groove, an eccentric circular groove, a radial groove, and a combination thereof Ditch. Moreover, the concavo-convex structures generally have regularity, but are more suitable for the retention of the slurry. Renewability, can also change the groove pitch, groove width, groove depth, etc. in each range.

The method for producing the concavo-convex structure is not particularly limited, and for example, a method of mechanically cutting a mold using a turning tool of a predetermined size, or a method of hardening a resin by flowing a resin into a mold having a predetermined surface shape, A method of producing a platen extruded resin having a predetermined surface shape, a method of producing by using a photolithography method, a method of producing by using a printing method, a method of producing by using a laser beam having a carbon dioxide laser or the like, or the like.

The polishing pad of the present invention may also be a laminate of the above-mentioned polishing layer and buffer sheet.

The buffer sheet (buffer layer) is a member that reinforces the characteristics of the polishing layer. The buffer sheet is required in CMP to have both the flatness and uniformity associated with the trade-off. The flatness refers to the flatness of the pattern portion when the object to be polished having fine irregularities is generated during the formation of the polishing pattern, and the uniformity refers to the uniformity of the entire object to be polished. The flatness is improved by the characteristics of the abrasive layer, and the uniformity is improved by the characteristics of the buffer sheet. In the polishing pad of the present invention, it is preferred to use a cushioning sheet which is softer than the polishing layer.

The buffer sheet may, for example, be a fiber nonwoven fabric such as a polyester nonwoven fabric, a nylon nonwoven fabric or an acrylic nonwoven fabric, or a resin impregnated nonwoven fabric impregnated with a polyester nonwoven fabric such as polyurethane, a polyurethane foam, or a poly A polymer resin foam such as an ethylene foam, a rubber resin such as butadiene rubber or isoprene rubber, or a photosensitive resin.

A method of laminating the polishing layer and the buffer sheet may be exemplified by a method of sandwiching and pressing the double-sided tape between the polishing layer and the buffer sheet.

The double-sided tape has a general structure in which an adhesive layer is provided on both surfaces of a substrate such as a nonwoven fabric or a film. It is preferable to prevent the slurry from impregnating the buffer sheet, etc., so that the film is preferably used for the substrate. Further, the composition of the adhesive layer may be, for example, a rubber-based adhesive or an acrylic adhesive. The amount of the metal ion is considered, and the acrylic adhesive is preferred because the metal ion content is small. Further, since the composition of the polishing layer and the buffer sheet may be different, the adhesion of each layer may be appropriately determined on the premise that the composition of each of the adhesive layers of the double-sided tape is different.

The polishing pad of the present invention can also be arranged on the same side as the platform. Face tape. As in the above, the double-sided tape can be used as a general structure having an adhesive layer provided on both sides of the substrate. The substrate may be exemplified by a nonwoven fabric or a film. The peeling from the platform after the use of the polishing pad is considered, so that the film is preferably used for the substrate. Further, the composition of the adhesive layer may be, for example, a rubber-based adhesive or an acrylic adhesive. The amount of the metal ion is considered, and the acrylic adhesive is preferred because the metal ion content is small.

The semiconductor device is fabricated by the step of polishing the surface of the semiconductor wafer using the aforementioned polishing pad. A semiconductor wafer is generally a laminate of a wiring metal and an oxide film on a germanium wafer. The polishing method of the semiconductor wafer is not particularly limited, and for example, as shown in FIG. 1, the polishing plate 2 supporting the polishing pad (abrasive layer) 2, the support table (polishing head) supporting the semiconductor wafer 4, and the like can be used. A polishing apparatus that supplies a substrate material that uniformly presses the wafer and a supply mechanism of the polishing agent 3, and the like. The polishing pad 1 is attached to the polishing plate 2 by, for example, attaching it with a double-sided tape. The polishing pad 2 and the support table 5 are disposed such that the polishing pad 1 supported by the polishing pad 2 and the semiconductor wafer 4 are opposed to each other, and have rotation axes 6, 7 respectively. Further, a pressurizing mechanism for pressing the semiconductor wafer 4 onto the polishing pad 1 is provided on the support table 5 side. At the time of polishing, the polishing plate 2 and the support table 5 are rotated and the semiconductor wafer 4 is pressed against the polishing pad 1, and the slurry is supplied while being polished. The flow rate of the slurry, the polishing load, the number of rotations of the polishing plate, and the number of wafer rotations are not particularly limited, and can be appropriately adjusted.

Thereby, the portion where the surface of the semiconductor wafer 4 is convex is removed and polished into a flat shape. Thereafter, the semiconductor device is fabricated by dicing, bonding, packaging, or the like. The semiconductor device can be used to calculate a processing device or a memory.

[Examples]

Hereinafter, the present invention will be described in detail by way of examples, but the invention is not limited by the examples.

[Measurement, evaluation method]

(Measurement of average bubble diameter)

The prepared polyurethane foam was cut into a sheet having a thickness of 1 mm or less as much as possible in parallel by a microtome, and the cut-out was used as a sample for measurement. The surface of the sample was photographed at 100 times using a scanning electron microscope (S-3500N, manufactured by Hitachi Science Systems). Further, the image analysis software (WIN-ROOF, manufactured by MITANI CORPORATION) was used to measure the circle equivalent diameter of the entire bubble in an arbitrary range, and the average bubble diameter was calculated from the measured value.

(measurement of specific gravity)

According to JIS Z8807-1976. The prepared polyurethane foam was cut into a short piece (thickness: arbitrary) of 4 cm × 8.5 cm as a sample for specific gravity measurement at a temperature of 23 ° C ± 2 ° C and a humidity of 50% ± 5%. Allow to stand for 16 hours. The measurement was carried out using a hydrometer (manufactured by Sartorius Co., Ltd.) to measure the specific gravity.

(Measurement of hardness)

According to JIS K6253-1997. The prepared polyurethane foam is cut into a size of 2 cm × 2 cm (thickness: arbitrary) as a sample for hardness measurement at an environment of a temperature of 23 ° C ± 2 ° C and a humidity of 50% ± 5%. Let stand for 16 hours. The sample was placed at the time of measurement to have a thickness of 6 mm or more. The hardness was measured using a durometer (manufactured by Kobunshi Seisakusho Co., Ltd., Asker D type hardness meter). Further, the sample was immersed in water for 48 hours, and then the sample was taken out and wiped off. After the surface moisture, the hardness was measured in the same manner.

(Evaluation of grinding characteristics)

The polishing apparatus was evaluated by using MAT-ARW-8C1A (manufactured by MAT) and using the prepared polishing pad. The polishing rate was calculated by polishing a film formed by laminating a thermal oxide film of 1 μm on a wafer of 8 Å for 60 seconds, and then calculating the amount of polishing. For the film thickness measurement of the oxide film, a light-drying film thickness measuring device (manufactured by Nanometrics Co., Ltd., device name: Nanospec) was used. In the polishing conditions, the slurry system was added with a cerium oxide slurry (manufactured by SS12 Cabot Co., Ltd.) at a flow rate of 120 ml/min. The polishing load was 4.5 psi, the number of revolutions of the grinding plate was 93 rpm, and the number of wafer rotations was 90 rpm.

The flattening characteristics were evaluated by the amount of removal. After depositing a 0.5 μm thermal oxide film on a wafer of 8 μm, a predetermined pattern was formed, and then an oxide film of 1 μm was deposited by p-TEOS to prepare a wafer having an initial height difference of 0.5 μm. The wafer was polished under the above conditions, and after polishing, the height difference was measured to calculate the amount of removal. The amount of removal refers to a pattern in which a line having a width of 270 μm is arranged side by side in a space of 30 μm, and a pattern in which the line width of 30 μm is arranged side by side in a space of 270 μm, and the difference in height of the line portion between the two types of patterns is 2,000 μm or less. When the amount of removal in the 270 μm space is small, the amount of removal that is not to be removed is small, and high flatness is exhibited.

The evaluation of the scratches was performed by grinding three 8-inch test wafers under the above conditions, and then polishing the 8-inch wafer on which the thermal oxide film having a thickness of 10,000 Å was deposited for 1 minute, and using a defect evaluation device manufactured by KLA Tencor Co., Ltd. (Surfscan SP1), it was determined that there were several strips of 0.19 μm or more on the polished wafer.

Example 1

100 parts by weight of a polyether-based prepolymer (ADIREENE L-325, manufactured by UNIROYAL Co., Ltd.) and 3 parts by weight of a lanthanoid surfactant (B8465, manufactured by GOLDSCHMIDT Co., Ltd.) were added and mixed in a reaction vessel, and the mixture was adjusted to a vacuum of 70 ° C. Degas. Thereafter, the stirring blade was vigorously stirred at a rotation number of 900 rpm for about 4 minutes to mix the bubbles in the reaction system. Thereafter, 1 part by weight of 3-isocyanatepropyltriethoxysilane (hereinafter referred to as 3-IPESi) and 4,4'-methylenebis(o-chloroaniline) previously melted to 120 ° C were added to the reaction vessel ( Hereinafter, it is referred to as MOCA) 28.9 parts by weight (NCO Index: 1.0). After stirring the mixture for about 70 seconds, it was poured into a bread mold (mold container). When the mixture had no fluidity, it was placed in an oven and heat-treated at 100 ° C for 16 hours to obtain a polyurethane foam block.

The polyurethane resin foam block which was heated to about 80 ° C was sliced with a microtome (manufactured by AMITEC Co., Ltd., VGW-125) to obtain a polyurethane resin foam sheet. Next, the surface of the sheet was polished to a thickness of 1.27 mm using a polishing machine (manufactured by AMITEC Co., Ltd.) to prepare a sheet having an adjusted thickness precision. The polished sheet was punched into a diameter of 61 cm, and a groove having a groove width of 0.25 mm, a groove pitch of 1.50 mm, and a groove depth of 0.40 mm was formed on the surface by using a groove processing machine (manufactured by Techno Corporation). Processing to obtain a polishing layer. A double-sided tape (Double tack tape, manufactured by Sekisui Chemical Co., Ltd.) was attached to the surface on the side opposite to the groove-finished surface of the polishing layer by a bonding machine. Further, the corona-treated cushion sheet (manufactured by TORAY Co., Ltd., polyethylene foam, TORAYPEF, thickness: 0.8 mm) was surface-polished, and bonded to the double-sided tape using a bonding machine. In addition, use the fit The machine combines the other side of the buffer sheet with the double-sided tape to make a polishing pad.

Example 2

A polishing pad was produced in the same manner as in Example 1 except that the amount of 3-IPESi added was changed from 1 part by weight to 5 parts by weight.

Example 3

40 parts by weight of polyethylene glycol (PEG, manufactured by Dai-ichi Kogyo Co., Ltd., number average molecular weight: 1000) and polyethylene glycol (PEG, manufactured by Dai-ichi Kogyo Co., Ltd., number average molecular weight of 600) 12.8 weight were placed in the reaction container. A portion and a portion by weight of DEG were dehydrated and dehydrated for 1 to 2 hours while stirring. Next, nitrogen was introduced into a separable flask, and after replacing with nitrogen, TDI-80 (41.2 parts by weight) was added. While maintaining the temperature in the reaction system at about 70 ° C, the mixture was stirred until the reaction was completed. The end of the reaction is when the NCO% is approximately constant (NCO%: 9.96). Thereafter, vacuum degassing was carried out for about 2 hours to obtain a hydrophilic isocyanate terminal prepolymer (hereinafter referred to as a hydrophilic prepolymer).

80 parts by weight of a polyether-based prepolymer (ADIREENE L-325, manufactured by UNIROYAL Co., Ltd.), 20 parts by weight of a hydrophilic prepolymer, and 3 parts by weight of a lanthanoid surfactant (B8465, manufactured by GOLDSCHMIDT Co., Ltd.) were placed in a reaction container. After mixing, adjust to 70 ° C and then vacuum degas. Thereafter, the stirring blade was vigorously stirred at a rotation number of 900 rpm for about 4 minutes to mix the bubbles in the reaction system. Thereafter, 1 part by weight of 3-IPESi and 29.4 parts by weight of MOCA (NCO Index: 1.0) previously melted to 120 ° C were added to the reaction vessel. After stirring the mixture for about 70 seconds, it was poured into a bread mold (mold container). When the mixture had no fluidity, it was placed in an oven and heat-treated at 100 ° C for 16 hours to obtain a polyurethane foam block. After that, A polishing pad was produced in the same manner as in Example 1.

Example 4

A polishing pad was produced in the same manner as in Example 3 except that the amount of 3-IPESi added was changed from 1 part by weight to 5 parts by weight.

Comparative example 1~3

A polishing pad was produced in the same manner as in Example 1 except that the mixing described in Table 1 was used.

The polishing pads of Examples 1 to 4 have a high polishing rate and are excellent in planarization characteristics. Moreover, scratches on the wafer can be effectively suppressed. On the other hand, the polishing pads and the flattening characteristics of the polishing pads of Comparative Examples 1 to 3 were insufficient. Moreover, the polishing pads of Comparative Examples 1 and 2 failed to suppress scratches on the wafer.

Industrial availability

The polishing pad of the present invention can stably perform planarization processing of a material requiring high surface flatness such as an optical material such as a lens or a mirror, a tantalum wafer, an aluminum substrate, or a general metal polishing process with high polishing efficiency. The polishing pad of the present invention is suitable for, in particular, planarizing a germanium wafer and a device on which an oxide layer, a metal layer or the like is formed, or even a laminate. A planarization step prior to forming the oxide layer or metal layer.

1‧‧‧ polishing pad (grinding layer)

2‧‧‧ grinding plate

3‧‧‧Abrasive (slurry)

4‧‧‧Abrased object (semiconductor wafer)

5‧‧‧Support table (grinding head)

6,7‧‧‧Rotating head

Claims (7)

A polishing pad characterized by being a polyamine group as a material for forming the polyurethane foam in a polishing pad having a polishing layer composed of a polyurethane foam. The formic acid ester resin is introduced into the side chain by reaction of an aminoester group of an isocyanate terminal prepolymer or a urea group with an isocyanate group of an alkoxyfluorenyl group-containing isocyanate represented by the following formula (1). Oxythiol (In the formula, X is OR ¹ or OH, R ¹ is independently an alkyl group having 1 to 4 carbon atoms, and R ² is an alkylene group having 1 to 6 carbon atoms). The polishing pad of claim 1, wherein the alkoxyfluorenyl-containing isocyanate-based 3-isocyanatepropyltriethoxysilane is used. The polishing pad according to claim 1 or 2, wherein the alkoxy group-containing isocyanate is added in an amount of 1 to 10 parts by weight based on 100 parts by weight of the isocyanate terminal prepolymer. A method for producing a polishing pad comprising a polishing pad in which a first component containing an isocyanate terminal prepolymer and a second component containing a chain extender are mixed and cured to form a polyurethane foam. The method of producing the ruthenium-based surfactant, wherein the ruthenium-based surfactant is added to the total weight of the first component and the second component, in the first component containing the isocyanate-terminated prepolymer. In the case of 0.05 to 10% by weight, the first component and the non-reactive gas are further stirred, and a bubble dispersion in which the non-reactive gas is used as a bubble is dispersed, and then the second component containing the chain extender is mixed. a step of preparing the polyurethane dispersion resin after curing the bubble dispersion liquid; and the second component contains an alkoxyfluorenyl group-containing isocyanate represented by the following formula (1); (In the formula, X is OR ¹ or OH, R ¹ is independently an alkyl group having 1 to 4 carbon atoms, and R ² is an alkylene group having 1 to 6 carbon atoms). The method for producing a polishing pad according to claim 4, wherein the alkoxyfluorenyl-containing isocyanate-based 3-isocyanatepropyltriethoxysilane is used. The method for producing a polishing pad according to claim 4 or 5, wherein the alkoxyfluorenyl-containing isocyanate is added in an amount of 1 to 10 parts by weight based on 100 parts by weight of the isocyanate-terminated prepolymer. A method of fabricating a semiconductor device, comprising the step of polishing a surface of a semiconductor wafer using the polishing pad of any one of claims 1 to 3.