KR102237351B1 - Composition for polishing pad, polishing pad and preparation method of semiconductor device - Google Patents

Abstract

In the composition according to the embodiment, the weight ratio of toluene 2,4-diisocyanate reacted with one NCO group and toluene 2,4-diisocyanate reacted with two NCO groups in the urethane-based prepolymer is controlled to control physical properties such as gelation time. I can. Therefore, since the polishing pad obtained by curing the composition according to the embodiment has a hardness suitable for the soft pad, the polishing rate and the pad cutting rate can be controlled, it is possible to efficiently manufacture a high-quality semiconductor device using the polishing pad. I can.

Description

A composition for a polishing pad, a method of manufacturing a polishing pad, and a semiconductor device {COMPOSITION FOR POLISHING PAD, POLISHING PAD AND PREPARATION METHOD OF SEMICONDUCTOR DEVICE}

The embodiment relates to a composition for a polishing pad, a polishing pad, and a method of manufacturing a semiconductor device. More specifically, the embodiment is a composition for a porous polyurethane polishing pad that can be used in a chemical mechanical polishing (CMP) process of a semiconductor device, a porous polyurethane polishing pad prepared from the composition, and a semiconductor device using the polishing pad It's about the method.

In the chemical mechanical polishing (CMP) process of the semiconductor manufacturing process, a semiconductor substrate such as a wafer is attached to a head and a slurry is supplied to the semiconductor substrate surface in a state in which it is brought into contact with the surface of a polishing pad formed on a platen. It is a process of mechanically flattening the irregularities on the surface of the semiconductor substrate by reacting with each other and moving the platen and the head relative to each other.

The polishing pad is an essential raw and subsidiary material that plays an important role in such a CMP process, and is generally made of a polyurethane resin, and the polyurethane resin includes a prepolymer obtained by reacting a diisocyanate monomer with a polyol, a curing agent, a foaming agent, etc. do.

In addition, the polishing pad has a groove in charge of large flow of slurry and pores supporting fine flow on the surface, and the pores are made of a solid foaming agent having pores, an inert gas, a liquid material, fiber, etc. Or by generating a gas through a chemical reaction.

The type of polishing pad used in the CMP process can be determined according to the object to be polished.For example, a hard pad having a relatively high hardness is used for polishing an oxide film, and a soft pad having a relatively low hardness is used for polishing a metal film. Is used. Among them, in order to improve the soft pad, research is being conducted to improve the performance including the polishing rate while controlling the hardness.

Korean Patent Application Publication No. 2016-0027075

The properties and physical properties of the urethane-based prepolymer used to manufacture the polishing pad may change depending on the monomer, which greatly affects the performance of the chemical mechanical polishing (CMP) process. Therefore, it can be said that controlling the physical properties of the urethane-based prepolymer is an important factor that can greatly change the properties of the polishing pad.

Accordingly, as a result of research by the present inventors, the gelation properties change according to the content of diisocyanate monomers constituting the urethane-based prepolymer for manufacturing the polishing pad and the degree of reaction or non-reaction, and accordingly, physical properties including hardness of the polishing pad As a result, it was found that it affects the CMP performance, such as the removal rate.

Therefore, the object of the embodiment is a composition in which physical properties are improved by controlling the content and reaction or non-reaction degree of diisocyanate monomers in the urethane-based prepolymer, a polishing pad suitable for a soft pad obtained from the composition, and a semiconductor using the polishing pad. It is to provide a method of manufacturing.

According to one embodiment, a urethane-based prepolymer is included, and the urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer is at least one aromatic A diisocyanate monomer is included, and the at least one aromatic diisocyanate monomer includes toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, and the urethane-based prepolymer is toluene 2,4 in which one NCO group is reacted. A composition is provided, comprising a diisocyanate and toluene 2,4-diisocyanate reacted with two NCO groups in a weight ratio of 100: 14 to 28.

According to another embodiment, a polishing layer is included, and the polishing layer includes a cured product of a composition comprising a urethane-based prepolymer, a curing agent, and a blowing agent, and the urethane-based prepolymer is at least one diisocyanate monomer and at least one polyol Including a prepolymerization reaction product of, the at least one diisocyanate monomer includes at least one aromatic diisocyanate monomer, and the at least one aromatic diisocyanate monomer is toluene 2,4-diisocyanate and toluene 2,6- Including diisocyanate, the urethane-based prepolymer comprises toluene 2,4-diisocyanate reacted with one NCO group and toluene 2,4-diisocyanate reacted with two NCO groups in a weight ratio of 100: 14 to 28, A polishing pad is provided.

According to another embodiment, comprising the step of polishing the surface of the semiconductor substrate using a polishing pad, the polishing pad includes a polishing layer, the polishing layer is a composition comprising a urethane-based prepolymer, a curing agent, and a foaming agent. Including a cured product, wherein the urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer includes at least one aromatic diisocyanate monomer, The at least one aromatic diisocyanate monomer includes toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, and the urethane-based prepolymer is toluene 2,4-diisocyanate reacted with one NCO group and two NCOs. A method of manufacturing a semiconductor device comprising a group-reacted toluene 2,4-diisocyanate in a weight ratio of 100: 14 to 28 is provided.

In the composition according to the above embodiment, the amount of diisocyanate monomer in the urethane-based prepolymer and the degree of reaction or non-reaction are controlled to control physical properties such as gelation time. Therefore, since the polishing pad obtained by curing the composition according to the embodiment has a hardness suitable for the soft pad, the polishing rate and the pad cutting rate can be controlled, it is possible to efficiently manufacture a high-quality semiconductor device using the polishing pad. I can.

In the description of the following embodiments, in the case where each layer, pad, or sheet is described as being formed on or under each layer, pad, or sheet, "upper" and "lower" Includes both directly or indirectly formed through other components.

The standards for the top/bottom of each component will be described based on the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation, and does not mean a size that is actually applied.

In the present specification, "including" one component means that other components may be further included, rather than excluding other components, unless specifically stated to the contrary.

In addition, all numerical ranges representing physical property values, dimensions, and the like of the constituents described in the present specification are to be understood as being modified by the term "about" in all cases unless otherwise specified.

[Composition for polishing pad]

The composition according to an embodiment includes a urethane-based prepolymer, and the urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer is one Toluene 2 containing the above aromatic diisocyanate monomers, wherein the at least one aromatic diisocyanate monomer includes toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, and the urethane-based prepolymer is reacted with one NCO group. ,4-diisocyanate and toluene 2,4-diisocyanate reacted with two NCO groups in a weight ratio of 100:14 to 28.

The composition according to the above embodiment may further include a curing agent, a foaming agent, and other additives.

Urethane prepolymer

The urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol. The prepolymerization reaction generally refers to a reaction in which polymerization of a monomer is stopped in an intermediate step to facilitate molding in manufacturing a final polymer molded article to obtain a relatively low molecular weight polymer. Accordingly, the prepolymer including the prepolymerization reaction product may be formed as a final product by itself or by further reacting with other polymerizable compounds or curing agents. For example, the weight average molecular weight (Mw) of the urethane-based prepolymer may be 500 g/mol to 3,000 g/mol, 600 g/mol to 2,000 g/mol, or 700 g/mol to 1,500 g/mol.

The at least one diisocyanate monomer may be at least one aromatic diisocyanate monomer and/or at least one aliphatic diisocyanate monomer, for example, toluene diisocyanate (TDI), naphthalene-1,5-di Isocyanate (naphthalene-1,5-diisocyanate), para-phenylene diisocyanate (p-phenylene diisocyanate), tolidine diisocyanate (tolidine diisocyanate), diphenylmethane diisocyanate (diphenylmethane diisocyanate (MDI)), hexamethylene diisocyanate ( It may be one or more isocyanates selected from the group consisting of hexamethylene diisocyanate, HDI), dicyclohexylmethane diisocyanate (H12MDI), isophorone diisocyanate, and the like.

As a specific example, the at least one diisocyanate monomer includes at least one aromatic diisocyanate monomer, and the at least one aromatic diisocyanate monomer includes toluene 2,4-diisocyanate and toluene 2,6-diisocyanate .

As another specific example, the at least one diisocyanate monomer further includes at least one aliphatic diisocyanate monomer, and the at least one aliphatic diisocyanate monomer is diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI) , Dicyclohexylmethane diisocyanate (H12MDI), and the like.

The polyol refers to a compound having two or more hydroxyl groups, and may include a monomolecular polyol and a high molecular polyol. Examples of the monomolecular polyol include ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), propanediol (PDO), methylpropanediol (MP-diol), and the like. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, polycarprolactone polyol, and the like. The high molecular weight polyol may have a weight average molecular weight of 300 g/mol to 3,000 g/mol.

The content of the at least one aromatic diisocyanate monomer in the urethane-based prepolymer may be 20% to 50% by weight, or 25% to 45% by weight.

In addition, the content of the at least one aliphatic diisocyanate monomer in the urethane-based prepolymer may be 0% to 15% by weight, or 1% to 10% by weight.

In addition, the content of the polyol in the urethane-based prepolymer may be 35% to 80% by weight, or 45% to 70% by weight.

Chain composition in the prepolymer

The urethane-based prepolymer includes a polymerization reaction product of various molecular weights between a diisocyanate monomer and a polyol.

For example, in the urethane-based prepolymer, the diisocyanate monomer is reacted with at least one NCO group (ie, two NCO groups are reacted or one NCO group is reacted) to form a chain in the prepolymer.

The reaction of the NCO group with a polyol or a side reaction with other compounds is included, and is not particularly limited. For example, the reaction of the NCO group may include a chain extension reaction or a crosslinking reaction.

As an example, in the reaction of the NCO group, in the process of reacting a diisocyanate monomer and a polyol for preparing the urethane-based prepolymer, an NCO group and an OH group react to form a urethane group (-NH-C(=O)-O-). It includes the urethane reaction to form. As a representative example, the NCO group of toluene diisocyanate (TDI) may react with the OH group of diethylene glycol (DEG) and urethane to form a chain as shown in the following formula.

As another example, the reaction of the NCO group may include a urea reaction with an amine compound, and as a result, a urea group (-NH-C(=O)-NH-) may be formed.

As another example, the reaction of the NCO group may further include a crosslinking reaction, and for example, may further include a crosslinking reaction forming an allophanate group or a biuret group.

Reaction of aromatic isocyanate monomer

In particular, at least one diisocyanate monomer used in the preparation of the urethane-based prepolymer includes at least one aromatic diisocyanate monomer, and the at least one aromatic diisocyanate monomer is involved in the prepolymerization reaction at a high rate.

In addition, the urethane-based prepolymer comprises 80% to 100% by weight and 85% to 100% by weight of an aromatic diisocyanate monomer reacted with at least one NCO group based on the total weight of the at least one aromatic diisocyanate monomer. , 90% to 100% by weight, 80% to 95% by weight, 85% to 95% by weight, or 95% to 100% by weight.

In addition, the urethane-based prepolymer contains 10% to 30% by weight, 10% to 25% by weight of an aromatic diisocyanate monomer reacted with two NCO groups, based on the total weight of the at least one aromatic diisocyanate monomer, 10% to 20% by weight, 10% to 15% by weight, 15% to 30% by weight, or 20% to 30% by weight.

In addition, the urethane-based prepolymer contains 78% to 95% by weight, 80% to 95% by weight of the aromatic diisocyanate monomer reacted with one NCO group, based on the total weight of the at least one aromatic diisocyanate monomer, 85% to 95% by weight, 79% to 90% by weight, or 80% to 90% by weight.

At this time, the urethane-based prepolymer comprises the aromatic diisocyanate monomer reacted with the two NCO groups and the aromatic diisocyanate monomer reacted with the one NCO group in a weight ratio of 0.1:1 to 0.3:1, and a weight ratio of 0.1:1 to 0.25:1 , 0.1:1 to 0.2:1 weight ratio, 0.1:1 to 0.15:1 weight ratio, or 0.15:1 to 0.25:1 weight ratio.

Reaction of 2,4-TDI and 2,6-TDI

The aromatic diisocyanate monomer included in the urethane-based prepolymer according to the above embodiment includes toluene 2,4-diisocyanate and toluene 2,6-diisocyanate.

The urethane-based prepolymer contains toluene 2,4-diisocyanate reacted with one NCO group and toluene 2,4-diisocyanate reacted with two NCO groups 100: 14 to 28, 100: 15 to 28, 100: 14 to 25 , 100: 15 to 25, 100: 15 to 20, or 100: may include in a weight ratio of 20 to 28.

Specifically, the urethane-based prepolymer may include toluene 2,4-diisocyanate reacted with one NCO group and toluene 2,4-diisocyanate reacted with two NCO groups in a weight ratio of 100: 15 to 20.

In addition, the urethane-based prepolymer contains 10 wt% to 30 wt%, 10 wt% to 25 wt% of toluene 2,4-diisocyanate reacted with two NCO groups, based on the total weight of the at least one aromatic diisocyanate monomer. %, 10% to 20% by weight, 10% to 20.5% by weight, 10% to 15% by weight, 15% to 30% by weight, or 20% to 30% by weight.

Specifically, the urethane-based prepolymer may include 10 wt% to 15 wt% of toluene 2,4-diisocyanate reacted with two NCO groups based on the total weight of the at least one aromatic diisocyanate monomer.

As described above, the amount of the aromatic diisocyanate monomer in the urethane-based prepolymer and the degree of reaction or non-reaction are controlled, so that physical properties such as gelation time may be controlled. Therefore, since the polishing pad obtained by curing the composition according to the embodiment has a hardness suitable for the soft pad, the polishing rate and the pad cutting rate can be controlled, it is possible to efficiently manufacture a high-quality semiconductor device using the polishing pad. I can.

Unreacted diisocyanate monomer

In addition, some of the compounds used in the reaction for preparing the urethane-based prepolymer may not be involved in the reaction. Therefore, a compound remaining not involved in the reaction may also be present in the urethane-based prepolymer. Specifically, the urethane-based prepolymer may include an unreacted diisocyanate monomer.

In the present specification, the "unreacted diisocyanate monomer" refers to a diisocyanate monomer in which both NCO groups remain unreacted. The content of the unreacted diisocyanate monomer in the urethane-based prepolymer may be adjusted according to the monomer composition and process conditions during the preparation of the prepolymer.

The urethane-based prepolymer contains 7% by weight or less, 5% by weight or less, 0% by weight to 7% by weight, 1% by weight to 7% by weight, 0% by weight of the unreacted diisocyanate monomer, based on the weight of the urethane-based prepolymer. It may be included in an amount of from 1% to 5% by weight, or 1% to 5% by weight.

The unreacted diisocyanate monomer present in the urethane-based prepolymer may include an unreacted aromatic diisocyanate monomer.

For example, the urethane-based prepolymer contains 3% by weight or less, 2% by weight or less, 1% by weight or less, 0% by weight to 3% by weight of unreacted aromatic diisocyanate monomer based on the weight of the urethane-based prepolymer. , 0% to 1.5% by weight, 0% to 1% by weight, 0% to 0.5% by weight, 0.1% to 3% by weight, 0.5% to 3% by weight, or 1% to 3% by weight Can include.

At least one aromatic diisocyanate monomer used in the reaction of the urethane-based prepolymer includes toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, of which toluene 2,6-diisocyanate is relatively reactive. Since it is low, it may be present in the urethane-based prepolymer without reacting with the polyol.

In addition, the unreacted diisocyanate monomer present in the urethane-based prepolymer may further include an unreacted aliphatic diisocyanate monomer.

For example, the urethane-based prepolymer may contain an unreacted aliphatic diisocyanate monomer in an amount of 0% to 15% by weight, or 1% to 10% by weight, based on the weight of the urethane-based prepolymer.

Unreacted NCO group content

The urethane-based prepolymer may have an unreacted NCO group at the end of the polymer, oligomer or monomer contained therein.

As a specific example, the urethane-based prepolymer, based on the weight of the urethane-based prepolymer, 5% to 13% by weight of unreacted NCO groups, 5% to 10% by weight, 5% to 9% by weight, 6 It may be included in an amount of 8% by weight to 8% by weight, 7% by weight to 9% by weight, or 7% by weight to 8% by weight.

As a specific example, the urethane-based prepolymer may include 5% to 9% by weight of unreacted NCO groups based on the weight of the urethane-based prepolymer.

Method for producing urethane-based prepolymer

The urethane-based prepolymer may be prepared by prepolymerizing at least one diisocyanate monomer and at least one polyol as described above.

In this process, the content of each type of diisocyanate and polyol and the reaction conditions are adjusted to control the content of each type of diisocyanate monomer and the degree of reaction or non-reaction.

The content and degree of reaction or non-reaction of diisocyanate monomers in the urethane prepolymer can be measured using NMR equipment.After confirming that the prepolymerization reaction has been performed at the desired level, change the reaction conditions if necessary to prepare the urethane prepolymer. Can be manufactured.

In addition, additional monomers such as isocyanate or alcohol, or other additives may be further added to the prepolymerization reaction.

Hardener

The curing agent may be one or more of an amine compound and an alcohol compound. Specifically, the curing agent may include one or more compounds selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols.

For example, the curing agent 4,4'-methylenebis (2-chloroaniline) (MOCA), diethyltoluenediamine (DETDA), diaminodiphenylmethane (diaminodiphenylmethane), diaminodiphenylsulfone (diaminodiphenylsulfone) ), m-xylylenediamine, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine, polypropylenediamine Propylenetriamine, ethylene glycol, diethylene glycol, dipropylene glycol, butanediol, hexanediol, glycerin, and trimethylolpropane ( trimethylolpropane) may be one or more selected from the group consisting of.

The urethane-based prepolymer and the curing agent may be mixed in a molar equivalent ratio of 1:0.8 to 1:1.2, or a molar equivalent ratio of 1:0.9 to 1:1.1, based on the number of moles of reactive groups in each molecule. have. Here, "based on the number of moles of each reactive group" means, for example, based on the number of moles of isocyanate groups in the urethane-based prepolymer and the number of moles of reactive groups (amine groups, alcohol groups, etc.) of the curing agent. . Accordingly, the urethane-based prepolymer and the curing agent may be introduced at a constant rate in the mixing process by adjusting the injection rate so that the urethane-based prepolymer and the curing agent are added per unit time in an amount satisfying the molar equivalent ratio exemplified above.

blowing agent

The foaming agent is not particularly limited as long as it is commonly used for forming voids in the polishing pad.

For example, the foaming agent may be at least one selected from a solid foaming agent having a hollow structure, a liquid foaming agent using a volatile liquid, and an inert gas.

The solid foaming agent may be a thermally expanded microcapsule, which may be obtained by heating and expanding the thermally expandable microcapsules. The thermally expanded microcapsules have an advantage of being able to uniformly control the particle size of pores by having a particle diameter of a uniform size as a structure of an already expanded microballoon. Specifically, the solid foaming agent may be a micro-balloon structure having an average particle diameter of 5 μm to 200 μm.

The thermally expandable microcapsules include an outer shell containing a thermoplastic resin; And a foaming agent encapsulated inside the outer shell. The thermoplastic resin may be at least one selected from the group consisting of vinylidene chloride-based copolymers, acrylonitrile-based copolymers, methacrylonitrile-based copolymers, and acrylic copolymers. Furthermore, the blowing agent may be at least one selected from the group consisting of hydrocarbons having 1 to 7 carbon atoms.

The solid foaming agent may be used in an amount of 0.1 parts by weight to 2.0 parts by weight based on 100 parts by weight of the urethane-based prepolymer. Specifically, the solid foaming agent may be used in an amount of 0.3 parts by weight to 1.5 parts by weight, or 0.5 parts by weight to 1.0 parts by weight based on 100 parts by weight of the urethane-based prepolymer.

The type of the inert gas is not particularly limited as long as it does not participate in the reaction between the urethane-based prepolymer and the epoxy curing agent. For example, the inert gas _{may be at least one selected from the group consisting of nitrogen gas (N 2} ), carbon dioxide gas (CO ₂ ), argon gas (Ar), and helium gas (He). Specifically, the inert gas may be nitrogen gas (N ₂ ) or carbon dioxide gas (CO ₂ ).

The inert gas may be introduced in a volume corresponding to 10% to 30% of the total volume of the polyurethane composition. Specifically, the inert gas may be introduced in a volume corresponding to 15% to 30% of the total volume of the polyurethane composition.

Gelation time

The composition takes a certain amount of time until it is gelled by curing, which is referred to as a gel time.

The gelation time of the composition may be 100 seconds or more, 110 seconds or more, 120 seconds or more, 150 seconds or more. For example, the gelation time of the composition may be 100 seconds to 300 seconds, 110 seconds to 250 seconds, 100 seconds to 200 seconds, 120 seconds to 220 seconds, 150 seconds to 300 seconds, or 150 seconds to 200 seconds. As a specific example, the composition may have a gelation time of 120 seconds to 220 seconds.

The gelation time may be, for example, a value measured at 70°C.

Characteristics after curing

The composition may have mechanical properties such as tensile strength, elongation, and hardness after curing within a specific range.

For example, the tensile strength after curing of the composition is 5 N/mm ² to 30 N/mm ² , 10 N/mm ² to 25 N/mm ² , 10 N/mm ² to 20 N/mm ² , or 15 N /mm ² to 30 N/mm ² may be.

In addition, the elongation after curing of the composition may be 50% to 400%, 200% to 400%, 200% to 300%, or 250% to 350%.

In addition, the hardness of the composition after curing is 20 Shore D to 70 Shore D, 30 Shore D to 60 Shore D, 40 Shore D to 60 Shore D, 30 Shore D to 50 Shore D, or 40 Shore D to 50 Shore D. I can.

Specifically, the composition may be more suitable for a soft pad by having a hardness of 40 Shore D to 50 Shore D after curing.

In addition, the composition may have ^{a tensile strength of 10 N/mm 2} to 25 N/mm ² and an elongation of 200% to 350% after curing.

The composition may have a plurality of micropores after curing.

The average diameter of the micropores may be 10 µm to 50 µm, 20 µm to 50 µm, 20 µm to 40 µm, 20 µm to 30 µm, or 30 µm to 50 µm.

In addition, the composition has a removal rate after curing of 1000 Å/50 seconds to 3000 Å/50 seconds, 1000 Å/50 seconds to 2000 Å/50 seconds, 1500 Å/50 seconds to 2500 Å/50 seconds, or 1500 Å/50 seconds to 1900 Å/50 seconds.

In addition, the composition has a pad cut rate after curing of 15 µm/hr to 45 µm/hr, 20 µm/hr to 35 µm/hr, 25 µm/hr to 45 µm/hr, and 25 µm/hr to It may be 35 μm/hr.

[Manufacturing method of polishing pad]

A method of manufacturing a polishing pad according to an embodiment includes the step of forming while curing the composition according to the embodiment.

That is, a method of manufacturing a polishing pad according to an embodiment includes the steps of preparing a raw material composition including a urethane-based prepolymer, a curing agent, and a foaming agent; And curing by injecting the raw material composition into a mold, wherein the urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer is It contains at least one aromatic diisocyanate monomer, and the urethane-based prepolymer contains toluene 2,4-diisocyanate reacted with one NCO group and toluene 2,4-diisocyanate reacted with two NCO groups: 100: 14 to 28 Included in the weight ratio of.

Specifically, the step of preparing the raw material composition may include preparing a first composition comprising a urethane-based prepolymer; Preparing a second composition comprising a curing agent; Preparing a third composition comprising a blowing agent; And sequentially or simultaneously mixing the first composition with the second composition and the third composition to prepare a raw material composition.

The mixing step for preparing the raw material composition may include mixing the first composition with the second composition and then further mixing with the third composition, or mixing the first composition with the third composition and then mixing the second composition with the third composition. It can be carried out by further mixing with the composition.

In addition, the step of preparing the raw material composition may be performed under conditions of 50° C. to 150° C., and if necessary, may be performed under vacuum defoaming conditions.

The step of injecting and curing the raw material composition into a mold may be performed under a ^{temperature condition of 60°C to 120°C and a pressure condition of 50 kg/m 2} to 200 kg/m ^2.

In addition, the manufacturing method may further include a step of cutting the surface of the obtained polishing pad, a step of processing a groove on the surface, an adhesion step with a lower layer, an inspection step, a packaging step, and the like. These processes can be performed in the manner of a conventional polishing pad manufacturing method.

[Polishing pad]

A polishing pad according to an embodiment includes a polishing layer including a cured product of the composition according to the embodiment.

That is, the polishing pad according to one embodiment includes a polishing layer, the polishing layer includes a cured product of a composition including a urethane-based prepolymer, a curing agent, and a foaming agent, and the urethane-based prepolymer is at least one diisocyanate monomer and It includes a prepolymerization reaction product of at least one polyol, the at least one diisocyanate monomer includes at least one aromatic diisocyanate monomer, and the at least one aromatic diisocyanate monomer is toluene 2,4-diisocyanate and toluene Including 2,6-diisocyanate, and the urethane-based prepolymer contains toluene 2,4-diisocyanate reacted with one NCO group and toluene 2,4-diisocyanate reacted with two NCO groups in a weight ratio of 14 to 28 Include as.

The cured product included in the polishing layer may be a porous polyurethane resin. That is, the polishing layer may include a polyurethane resin and a plurality of micropores dispersed in the polyurethane resin. The polyurethane resin may be derived from the urethane-based prepolymer.

The weight average molecular weight (Mw) of the polyurethane resin is 500 g/mol to 1,000,000 g/mol, 5,000 g/mol to 1,000,000 g/mol, 50,000 g/mol to 1,000,000 g/mol, 100,000 g/mol to 700,000 g/ mol, or 500 g/mol to 3,000 g/mol.

The thickness of the polishing layer may be 0.8 mm to 5.0 mm, 1.0 mm to 4.0 mm, 1.0 mm to 3.0 mm, 1.5 mm to 2.5 mm, 1.7 mm to 2.3 mm, or 2.0 mm to 2.1 mm. When it is within the above range, it is possible to sufficiently exhibit basic physical properties as a polishing layer while minimizing the variation in particle size by upper and lower portions of the pores.

The specific gravity of the polishing layer may be 0.6 g/cm 3 to 0.9 g/cm 3, or 0.7 g/cm 3 to 0.85 g/cm 3.

In addition, the polishing layer may have the same physical properties and pore properties after curing of the composition according to the previous embodiment, in addition to the above-described physical properties.

The hardness of the polishing layer may be 20 Shore D to 70 Shore D, 30 Shore D to 60 Shore D, 40 Shore D to 60 Shore D, 30 Shore D to 50 Shore D, or 40 Shore D to 50 Shore D.

The tensile strength of the polishing layer is 5 N/mm ² to 30 N/mm ² , 10 N/mm ² to 25 N/mm ² , 10 N/mm ² to 20 N/mm ² , or 15 N/mm ² to It can be 30 N/mm ^2.

The elongation of the polishing layer may be 50% to 400%, 200% to 400%, 200% to 300%, or 250% to 350%.

The micropores are dispersed and present in the polyurethane resin.

The average diameter of the micropores may be 10 µm to 50 µm, 20 µm to 50 µm, 20 µm to 40 µm, 20 µm to 30 µm, or 30 µm to 50 µm. As a specific example, the micropores may have an average diameter of 20 μm to 25 μm.

In addition, the micropores may be included in an amount of 100 to 300, 150 to 300, or 100 to 250 per ^{0.3 cm 2 area of the polishing layer.}

In addition, the total area of the micropores may be 30% to 60%, 35% to 50%, or 35% to 43% based on the total area of the polishing layer.

In addition, the micropores may be included in 30% to 70% by volume, 30% to 70% by volume, or 40% to 60% by volume based on the total volume of the polishing layer.

The polishing layer may have a groove for mechanical polishing on its surface. The groove may have an appropriate depth, width and spacing for mechanical polishing, and is not particularly limited.

The polishing pad may further include a support layer stacked with the polishing layer. The support layer serves to absorb and disperse the impact applied to the polishing layer while supporting the polishing layer. The support layer may include a nonwoven fabric or suede, and may have a thickness of 0.5 mm to 1 mm and a hardness of 60 Asker C to 90 Asker C.

In addition, an adhesive layer may be inserted between the polishing layer and the support layer. The adhesive layer may include a hot melt adhesive. The hot melt adhesive may be at least one selected from the group consisting of polyurethane resins, polyester resins, ethylene-vinyl acetate resins, polyamide resins, and polyolefin resins. Specifically, the hot melt adhesive may be at least one selected from the group consisting of polyurethane resins and polyester resins.

The removal rate of the polishing pad is 1000 Å/50 sec to 3000 Å/50 sec, 1000 Å/50 sec to 2000 Å/50 sec, 1500 Å/50 sec to 2500 Å/50 sec, or 1500 Å /50 seconds to 1900 Å/50 seconds. As a specific example, the polishing pad may have a polishing rate of 1000 Å/50 seconds to 2500 Å/50 seconds. The polishing rate may be an initial polishing rate immediately after manufacture of the polishing pad (ie, immediately after curing). In addition, the pad cut rate of the polishing pad is 15 µm/hr to 45 µm/hr, 20 µm/hr to 35 µm/hr, 25 µm/hr to 45 µm/hr, and 25 µm/hr to 35. It may be μm/hr.

When the polishing pad is within the above characteristic range, since the polishing rate and the pad cutting rate can be controlled while having a hardness suitable for the soft pad, a semiconductor device of high quality can be efficiently manufactured using the polishing pad.

[Semiconductor device manufacturing method]

A method of manufacturing a semiconductor device according to an embodiment includes polishing a surface of a semiconductor substrate using a polishing pad according to the embodiment.

That is, a method of manufacturing a semiconductor device according to an embodiment includes polishing a surface of a semiconductor substrate using a polishing pad, wherein the polishing pad includes a polishing layer, and the polishing layer is a urethane-based prepolymer, a curing agent And a cured product of a composition comprising a blowing agent, wherein the urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, and the at least one diisocyanate monomer is at least one aromatic A diisocyanate monomer is included, and the at least one aromatic diisocyanate monomer includes toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, and the urethane-based prepolymer is toluene 2,4 in which one NCO group is reacted. -Diisocyanate and toluene 2,4-diisocyanate reacted with two NCO groups in a weight ratio of 100: 14 to 28.

Specifically, after the polishing pad according to the embodiment is mounted on the surface, the semiconductor substrate is disposed on the polishing pad. At this time, the surface of the semiconductor substrate is in direct contact with the polishing surface of the polishing pad. A polishing slurry may be sprayed onto the polishing pad for polishing. Thereafter, the semiconductor substrate and the polishing pad may rotate relative to each other, so that the surface of the semiconductor substrate may be polished.

The polishing pad according to the embodiment is obtained by curing a urethane-based prepolymer whose composition is adjusted and has excellent elongation, hardness, fine pore characteristics, polishing rate, etc., so that a semiconductor device of excellent quality can be efficiently produced by using the polishing pad. Can be manufactured.

[Example]

It will be described in more detail through the following examples, but is not limited to the scope of these examples.

Examples and Comparative Examples

(1) Preparation of urethane-based prepolymer

4 toluene 2,4-diisocyanate (2,4-TDI), toluene 2,6-diisocyanate (2,6-TDI), polytetramethylene ether glycol (PTMEG) and dicyclohexylmethane diisocyanate (H12MDI). After putting into the old flask and reacting at 80° C., diethylene glycol (DEG) was further added and reacted at 80° C. for an additional 2 hours. Urethane-based prepolymers of various compositions were prepared by adjusting the content and reaction conditions of each type of diisocyanate and polyol introduced in this process.

To analyze the composition of the urethane-based prepolymer, 5 mg of a urethane-based prepolymer sample _{was dissolved in CDCl 3} ^{and analyzed 1} H-NMR and ¹³ C-NMR using a nuclear magnetic resonance (NMR) device (JEOL 500 MHz, 90° pulse) at room temperature. Was performed. In the obtained NMR data, by integrating the peaks of the reacted methyl group and the unreacted methyl group of TDI, the content of the reacted or unreacted monomer in the urethane-based prepolymer was calculated.

Specifically, when the weight of 2,4-TDI (hereinafter referred to as “4-reacted 2,4-TDI”) reacted with only the NCO group substituted at the 4-position among the two NCO groups is 100 parts by weight, 2,4-TDI (hereinafter referred to as "2,4-reacted 2,4-TDI") in which both NCO groups react with polyol to form a chain, 2,6 in which both NCO groups do not react with polyol -TDI (hereinafter referred to as "unreacted 2,6-TDI") and 2,6-TDI in which only the NCO group substituted at the 2-position or 6-position among the two NCO groups was reacted with the polyol (hereinafter "2-reaction (Referred to as "2,6-TDI") was calculated (otherwise, 2,4-TDI reacted with only the 2-position NCO group and 2,6-TDI reacted with both NCO groups were hardly detected) . The results are summarized in the following table.

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 content
(Part by weight) 4-reacted 2,4-TDI 100.00 100.00 100.00 100.00 100.00 100.00 100.00 2,4-reacted 2,4-TDI 16.61 14.19 22.96 25.68 13.90 28.30 29.62 Unreacted 2,6-TDI 0 1.68 2.45 0.39 21.22 4.50 8.20 2-reacted 2,6-TDI 22.97 20.96 1.89 1.34 9.59 3.80 24.05 Total TDI amount 139.58 136.83 127.30 127.41 144.71 136.6 161.87

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 content
(weight%)
(All TDI
By weight) 4-reacted 2,4-TDI (a) 71.64 73.08 78.55 78.49 69.10 73.21 61.78 2,4-reacted 2,4-TDI 11.90 10.37 18.04 20.16 9.61 20.72 18.30 Unreacted 2,6-TDI 0.00 1.23 1.92 0.31 14.66 3.29 5.07 2-reacted 2,6-TDI (b) 16.46 15.32 1.48 1.05 6.63 2.78 14.86 (a) + (b) 88.10 88.40 80.04 79.54 75.73 75.99 76.64 Full TDI 100 100 100 100 100 100 100

(2) Manufacturing of polishing pad

A casting apparatus equipped with a tank and an input line for supplying raw materials such as a prepolymer, a curing agent, an inert gas and a blowing agent, respectively, was prepared. Urethane-based prepolymer prepared above, curing agent (4,4'-methylenebis (2-chloroaniline), Ishihara company), inert gas (N ₂ ), liquid foaming agent (FC3283, 3M company), solid foaming agent (Akzonobel) and A silicone-based surfactant (Evonik) was charged into each tank. The raw materials were stirred while being added to the mixing head at a constant speed through each input line. At this time, the prepolymer and the curing agent were added in an equivalent ratio of 1:1 and a total amount of 10 kg/min.

The stirred raw material was discharged to a mold (1,000 mm x 1,000 mm x 3 mm) and the reaction was completed to obtain a solid cake-shaped molded body. Thereafter, the upper and lower ends of the molded body were each cut by a thickness of 0.5 mm to obtain a polishing layer having a thickness of 2 mm.

Thereafter, the polishing layer was subjected to surface milling and groove forming processes, and laminated with the support layer using a hot melt adhesive to obtain a polishing pad.

Specific process conditions of the polishing layer are summarized in the following table.

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 NCO% of prepolymer (% by weight) 7.15 7.15 7.15 7.15 9.3 7.15 7.15 Casting mold Single Single Single Single Single Single Single Casting, cutting, grooving Sequential Sequential Sequential Sequential Sequential Sequential Sequential Prepolymer content (parts by weight) 100 100 100 100 100 100 100 Surfactant content (parts by weight) 0.2~1.5 0.2~1.5 0.2~1.5 0.2~1.5 0.2~1.5 0.2~1.5 0.2~1.5 Solid foaming agent content (parts by weight) 0.5~2.0 0.5~2.0 0.5~2.0 0.5~2.0 0.5~2.0 0.5~2.0 0.5~2.0 Inert gas (L/min) 0.5~1.5 0.5~1.5 0.5~1.5 0.5~1.5 0.5~1.5 0.5~1.5 0.5~1.5

Test example

The polishing pads obtained in Examples and Comparative Examples were tested for the following items, and the results are shown in the following table.

(1) hardness

The sample was cut into 5 cm x 5 cm (thickness: 2 mm), and after storage at a temperature of 25° C. for 12 hours, hardness was measured using a hardness tester (HPE III Shore D).

(2) specific gravity

The sample was cut into 2 cm x 5 cm (thickness: 2 mm), and after storage at 25° C. for 12 hours, the multilayer specific gravity was measured using a hydrometer (MD-300S).

(3) Tensile strength

The sample was cut into 4 cm x 1 cm (thickness: 2 mm), and the highest strength value just before fracture was measured at a speed of 50 mm/min using a universal testing system (UTM, AG-X Plus).

(4) elongation

The sample is cut into 4 cm x 1 cm (thickness: 2 mm), and the maximum amount of deformation just before fracture is measured at a speed of 50 mm/min using a universal tester (UTM, AG-X Plus), compared to the initial length. The ratio of the maximum deformation amount is expressed as a percentage (%).

(5) gel time

The prepolymer and the curing agent were mixed in an equivalent amount of 1:1, and the time taken until the mixture was stirred at 5,000 rpm to gel at 70°C was measured.

division Evaluation item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Polishing layer Thickness (mm) 2 2 2 2 2 2 2 Hardness (Shore D) 45 44.4 44.2 44.8 58 47 49 Specific gravity (g/cc) 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Tensile strength (N/mm ² ) 18.5 18.7 18.9 18.6 23.0 20.0 21.2 Elongation (%) 274 280 286 283 98 232 212 Gelation time (s) 167 165 170 163 55 110 90 Support layer type Non-woven Non-woven Non-woven Non-woven Non-woven Non-woven Non-woven Thickness (mm) 1.1 1.1 1.1 1.1 1.1 1.1 1.1 Hardness (Asker C) 70 70 70 70 70 70 70 grinding
pad Thickness (mm) 3.32 3.32 3.32 3.32 3.32 3.32 3.32 Compression rate (%) 1.05 1.05 1.05 1.05 1.05 1.05 1.05

(6) removal rate

The initial polishing rate immediately after manufacturing the polishing pad was measured as follows.

Silicon oxide was deposited on a semiconductor substrate made of silicon having a diameter of 300 mm by a chemical vapor deposition (CVD) process. A polishing pad was attached to the CMP equipment, and the silicon oxide layer of the semiconductor substrate was installed to face the polishing surface of the polishing pad. While supplying the calcined ceria slurry on the polishing pad at a rate of 250 mL/min, the silicon oxide film was polished for 50 seconds at a load of 4.0 psi and a speed of 150 rpm. After polishing, the semiconductor substrate was removed from the carrier, mounted on a spin dryer, washed with distilled water, and dried with nitrogen for 15 seconds. With respect to the dried semiconductor substrate, a change in film thickness before and after polishing was measured using an optical interference type thickness measuring apparatus (SI-F80R, Keyence Co., Ltd.). Then, the polishing rate was calculated using the following equation. The results are shown in the table below.

Polishing rate (Å/50 seconds) = Change in film thickness before and after polishing (Å) / Polishing time (50 seconds)

(7) Pad cut rate

The polishing pad was pre-conditioned with deionized water for 10 minutes, and then conditioned in a conditioner using a diamond disk while spraying deionized water for 1 hour (Conditioner type: CI45, Conditioning type: In situ, Conditioner force: 5.0 lb, Conditioner rpm. : 101.0 rpm, Conditioner sweep speed: 19.0 sw/min, DIW flow rate: 250 cc/min). The cutting rate of the polishing pad was calculated by measuring the thickness changed during the conditioning process. The results are shown in the table below.

division Evaluation item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 grinding
pad Polishing rate (Å/50s) 1741 1770 1825.5 1795.3 3580 1823.4 1950 Pad cutting rate (㎛/hr) 27 28 29.5 26.5 18 22 19.5

As shown in the above table, the polishing pad of the Example had excellent polishing rate at a level suitable for the soft pad, whereas the polishing pad of the Comparative Example was generally not suitable for the soft pad due to increased aggregation of hard segments.

In addition, as shown in the table above, the polishing pad of Example had excellent pad cutting rate when conditioning using a diamond disk, while the polishing pad of Comparative Example had a low pad cutting rate due to increased aggregation of hard segments.

Claims (10)

delete delete delete delete delete delete delete delete delete Selecting a polishing pad; And
Polishing the surface of the semiconductor substrate using a polishing pad,
The polishing pad includes a polishing layer, and the polishing layer includes a cured product of a composition including a urethane-based prepolymer, a curing agent and a foaming agent,
The urethane-based prepolymer includes a prepolymerization reaction product of at least one diisocyanate monomer and at least one polyol, the at least one diisocyanate monomer includes at least one aromatic diisocyanate monomer, and the at least one aromatic diisocyanate The isocyanate monomer includes toluene 2,4-diisocyanate and toluene 2,6-diisocyanate,
The urethane-based prepolymer contains toluene 2,4-diisocyanate reacted with one NCO group and toluene 2,4-diisocyanate reacted with two NCO groups in a weight ratio of 100: 14 to 28,
The hardness of the polishing layer is 40 Shore D to 50 Shore D,
The tensile strength of the polishing layer is 10 N/mm ² to 25 N/mm ² ,
The elongation of the polishing layer is 200% to 350%, the method of manufacturing a semiconductor device.