Polishing pad, pyrolysis oil obtained therefrom and method for producing the same

Abstract

To provide: a polishing pad that has excellent physical properties and can increase the polishing rate of a CMP process; and a technology that can increase the recycling rate of used polishing pads.SOLUTION: The invention relates to a polishing pad that comprises a polishing layer 10. When pyrolysis oil obtained from the polishing pad is analyzed according to the KS M 2457 standard, the content of chlorine components is 13000 mg / kg or more. When the pyrolysis oil is analyzed by inductively coupled plasma atomic emission spectrometry, the content of metal components is less than 4 mg / kg.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The implementation relates to a polishing pad used in the chemical mechanical planarization (CMP) process of semiconductor devices, a pyrolysis oil obtained from the polishing pad, and a method for producing the pyrolysis oil. [Background technology]

[0002] In the semiconductor manufacturing process, the chemical mechanical polishing (CMP) process is a process in which a semiconductor substrate such as a wafer is attached to a head and brought into contact with the surface of a polishing pad fixed on a platen, and the platen and the head are moved relative to each other to flatten uneven portions of the semiconductor substrate surface.

[0003] In the CMP process, the polishing pad is required to have stable physical properties since it has a significant impact on the surface processing quality of the semiconductor substrate. In particular, since the polishing rate of the CMP process can be sensitively affected by the components and physical properties of the polishing pad, it is necessary to optimize the components and physical properties of the polishing pad.

[0004] On the other hand, as environmental issues have become more serious recently, attempts have been made to recycle used polishing pads. However, polishing pads are difficult to process for recycling (for example, by melting using heat), and the recycling rate has not yet reached a satisfactory level.

[0005] Therefore, it is necessary to develop a polishing pad that has excellent physical properties and can increase the polishing rate in the CMP process, and a technology that can increase the recycling rate of used polishing pads. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Republic of Korea Patent Publication No. 2009-0029336 Summary of the Invention [Problem to be solved by the invention]

[0007] Generally, polishing pads contain a cured polyurethane material prepared from a composition containing a urethane-based prepolymer, a curing agent, and a foaming agent as main components. However, the present inventors have found that, during thermal decomposition of a polishing pad containing the cured polyurethane material, the physical properties of the polishing pad change depending on the content of residual chlorine components, and that the change in physical properties affects the removal rate of the CMP process.

[0008] The present inventors have also found that the recycling rate of the polishing pad can be increased by pyrolyzing the polishing pad.

[0009] As a result, the embodiment provides a polishing pad in which the content of residual chlorine components after thermal decomposition is controlled and which can exhibit excellent physical properties.

[0010] Furthermore, the embodiment provides a pyrolysis oil obtained by pyrolyzing the polishing pad and a method for producing the same. [Means for solving the problem]

[0011] According to an embodiment for solving the above problem, a polishing pad including a polishing layer is provided, in which, when the pyrolysis oil obtained by pyrolyzing the polishing pad at 320°C for 6 hours is analyzed in accordance with the KS M 2457 standard, the content of chlorine components is 13,000 mg / kg or more.

[0012] According to another embodiment, a pyrolysis oil obtained from a polishing pad is provided, the pyrolysis oil having a chlorine content of 13,000 mg / kg or more when analyzed according to the KS M 2457 standard.

[0013] In another embodiment, a method for producing pyrolysis oil is provided, the method comprising the steps of: placing a polishing pad in a chamber; pyrolyzing the polishing pad placed in the chamber at 280°C to 350°C; and passing the vaporized stream formed by the pyrolysis through a heat exchanger to obtain liquid pyrolysis oil, wherein the pyrolysis oil has a chlorine content of 13,000 mg / kg or more when analyzed according to the KS M 2457 standard. [Effects of the Invention]

[0014] The polishing pad according to the embodiment is obtained through an optimized curing reaction by precisely controlling the components, such as the urethane-based prepolymer, curing agent, and foaming agent, which are raw materials used to manufacture the polishing pad, and the content of each component, so that the content of residual chlorine components during thermal decomposition is analyzed within a certain range, which can result in excellent mechanical properties such as hardness and elastic modulus. Therefore, when a CMP process is performed using the polishing pad according to the embodiment, it is possible to provide a semiconductor substrate (e.g., wafer) that exhibits a high polishing rate and has excellent surface processing quality.

[0015] In addition, the pyrolysis oil according to the embodiment is obtained by pyrolyzing polishing pads (specifically, used polishing pads) and can be used as a high-quality heat source (e.g., heating oil, power plant fuel, etc.) after a refining process, etc. Therefore, the embodiment can contribute to improving environmental issues by increasing the recycling rate of polishing pads. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view of a polishing pad according to one implementation. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described below using examples. Note that the examples are not limited to the contents disclosed below, and may be modified in various forms as long as the gist of the invention is not changed.

[0018] In this specification, when a component is described as being formed above / below another component, or as being connected or coupled to each other, this includes being formed, coupled or coupled directly between these components, or indirectly via other components. It should also be understood that the reference to the above / below of each component may change depending on the direction from which the object is viewed.

[0019] As used herein, the term "comprising" is intended to embody certain features, regions, steps, steps, elements and / or components, and does not exclude the presence or addition of other features, regions, steps, steps, elements and / or components, unless specifically stated to the contrary.

[0020] All numbers and expressions expressing quantities of components, reaction conditions, and the like described herein may be understood to be modified in all instances by the term "about," unless otherwise specified.

[0021] <Polishing pad> The embodiment provides a polishing pad including a polishing layer, and optionally further including an adhesive layer and a cushion layer. The polishing pad according to this embodiment has a controlled content of residual chlorine components after pyrolysis, which will be described in detail below with reference to FIG.

[0022] [Polishing layer] The polishing layer 10 included in the polishing pad according to the embodiment serves to polish a semiconductor substrate (e.g., a wafer) to be polished. Such a polishing layer 10 can be formed (manufactured) using a composition (polishing layer-forming composition) including a urethane-based prepolymer, a curing agent, and a foaming agent.

[0023] The urethane-based prepolymer contained in the composition may be a polymer obtained by reacting a polyol compound with an isocyanate compound. Such a urethane-based prepolymer may have a weight-average molecular weight (Mw) of 500 g / mol to 3000 g / mol, specifically 600 g / mol to 2000 g / mol, 700 g / mol to 1500 g / mol, or 800 g / mol to 1000 g / mol.

[0024] The urethane-based prepolymer may have an isocyanate terminal group content (NCO%) of 7.5 to 11% by weight, specifically 7.5 to 10%, 8 to 10%, or 8.5 to 9.5% by weight. By providing an NCO% within this range, a polishing pad can be provided that exhibits desired levels of polishing rate, polishing profile, etc., and minimizes the occurrence of defects on semiconductor substrates during the CMP process. Such a polishing pad may have a relatively high content of residual chlorine components after thermal decomposition.

[0025] The polyol compound for obtaining the urethane-based prepolymer may be at least one selected from the group consisting of polyether polyols, polyester polyols, polycarbonate polyols, and acrylic polyols. More specifically, the polyol compound may include at least one selected from the group consisting of polytetramethylene ether glycol, polypropylene ether glycol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, and tripropylene glycol.

[0026] Such polyol compounds have a weight-average molecular weight (Mw) of 100 g / mol to 3000 g / mol, specifically 100 g / mol to 2500 g / mol, 200 g / mol to 2000 g / mol, or 300 g / mol to 1800 g / mol. For example, the polyol compounds may include a low-molecular-weight polyol compound having a weight-average molecular weight (Mw) of 100 g / mol to less than 300 g / mol, and a high-molecular-weight polyol compound having a weight-average molecular weight (Mw) of 300 g / mol to 1800 g / mol.

[0027] Specifically, the isocyanate compound for obtaining the urethane-based prepolymer may be one or more selected from the group consisting of aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. More specifically, the isocyanate compound may include one or more selected from the group consisting of 2,4-toluenediisocyanate, 2,6-toluenediisocyanate, naphthalene-1,5-diisocyanate, p-phenylenediisocyanate, tolidinediisocyanate, 4,4'-diphenylmethanediisocyanate, hexamethylenediisocyanate, dicyclohexylmethanediisocyanate, and isophoronediisocyanate.

[0028] The curing agent may include a compound that undergoes a curing reaction with the urethane-based prepolymer, and may include at least one selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols. More specifically, the curing agent may include one or more selected from the group consisting of 4,4'-methylenebis(2-chloroaniline), diethyltoluenediamine, diaminodiphenylmethane, dimethylthio-toluenediamine, propanediolbis(p-aminobenzoate), diaminodiphenylsulfone, m-xylylenediamine, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine, and polypropylenetriamine.

[0029] For example, the curing agent preferably contains 4,4'-methylenebis(2-chloroaniline). By including 4,4'-methylenebis(2-chloroaniline) in the curing agent, the curing reaction is optimized, and a polishing pad having excellent overall physical properties and a relatively high content of residual chlorine components after thermal decomposition can be provided.

[0030] The content of the curing agent may be 18 to 27 parts by weight, specifically 19 to 26 parts by weight, or 20 to 26 parts by weight, based on 100 parts by weight of the urethane-based prepolymer. By having the content of the curing agent within this range, it may be more advantageous to realize a polishing pad with excellent physical properties.

[0031] Meanwhile, the reaction ratio (curing reaction ratio) between the urethane-based prepolymer and the curing agent may be specifically an equivalent ratio of 1:0.75 to 1.1, an equivalent ratio of 1:0.8 to 1.05, an equivalent ratio of 1:0.85 to 1.05, or an equivalent ratio of 1:0.9 to 1. By carrying out the curing reaction at this reaction ratio, the curing reaction is optimized, and a polishing pad having excellent overall physical properties and a relatively high content of residual chlorine components after thermal decomposition can be provided.

[0032] The foaming agent contained in the composition is used to form a pore structure in the polishing layer 10 and may include one or more foaming agents selected from the group consisting of solid-phase foaming agents, liquid-phase foaming agents, and gas-phase foaming agents (e.g., inert gases such as nitrogen, argon, and helium). Specifically, the foaming agent is preferably a solid-phase foaming agent containing expandable particles.

[0033] The expandable particles are particles that can expand due to heat or pressure. Specifically, the expandable particles may include thermally expanded particles, unexpanded particles, or a combination thereof. The thermally expanded particles are particles that have been pre-expanded by heat. The unexpanded particles may refer to particles whose final size is determined by the heat or pressure applied during the manufacturing process of the polishing layer 10. Such expandable particles may include a resin outer shell and an expansion-inducing component present inside the shell.

[0034] The resin outer shell may include a thermoplastic resin, which may be at least one selected from the group consisting of vinylidene chloride copolymers, acrylonitrile copolymers, methacrylonitrile copolymers, and acrylic copolymers.

[0035] The expansion-inducing component may include one or more selected from the group consisting of hydrocarbon compounds, chlorofluoro compounds, and tetraalkylsilane compounds.

[0036] Specifically, the hydrocarbon compound may include one or more selected from the group consisting of ethane, ethylene, propane, propene, n-butane, isobutane, n-butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, and petroleum ether.

[0037] The chlorofluoro compound may include one or more selected from the group consisting of trichlorofluoromethane (CClF), dichlorodifluoromethane (CClF), chlorotrifluoromethane (CClF), and dichlorotetrafluoroethylene (CClF-CClF).

[0038] The tetraalkylsilane compound may include at least one selected from the group consisting of tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane.

[0039] For example, the expansion-inducing component is preferably a chlorofluoro compound. By using a chlorofluoro compound as the expansion-inducing component, a uniform and desired pore structure is formed in the polishing layer 10, and a polishing pad having excellent overall physical properties and a relatively high content of residual chlorine components after thermal decomposition can be provided.

[0040] Such a solid-phase blowing agent has an average particle size of 5 μm to 200 μm, specifically 10 μm to 100 μm, 15 μm to 70 μm, or 20 μm to 45 μm. When the solid-phase blowing agent contains thermally expanded particles as the expandable particles, the average particle size may refer to the average particle size of the thermally expanded particles themselves. When the solid-phase blowing agent contains unexpanded particles as the swellable particles, the average particle size may refer to the average particle size of the particles after they have been expanded by heat or pressure.

[0041] The content of the solid-phase foaming agent is 0.5 to 10 parts by weight, specifically 0.7 to 5 parts by weight, 0.9 to 3 parts by weight, or 1 to 2 parts by weight, based on 100 parts by weight of the urethane-based prepolymer. By having the content of the solid-phase foaming agent within this range, it may be more advantageous to realize a polishing pad with excellent physical properties.

[0042] Meanwhile, the composition for forming the polishing layer 10 may further contain additives such as a surfactant and a reaction rate modifier. The surfactant may specifically be a silicone surfactant.

[0043] Specific examples of the reaction rate adjuster include one or more selected from the group consisting of triethylenediamine, dimethylethanolamine, tetramethylbutanediamine, 2-methyl-triethylenediamine, dimethylcyclohexylamine, triethylamine, triisopropanolamine, 1,4-diazabicyclo(2,2,2)octane, bis(2-methylaminoethyl)ether, trimethylaminoethylethanolamine, N,N,N,N,N″-pentamethyldiethyldimethylaminoethylamine, dimethylaminopropylamine, benzyldimethylamine, N-ethylmorpholine, N,N-dimethylaminoethylmorpholine, N,N-dimethylcyclohexylamine, 2-methyl-2-azanorbornene, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, dioctyltin diacetate, dibutyltin maleate, dibutyltin bis(2-ethylhexanoate), and dibutyltin dimercaptide.

[0044] The thickness of the polishing layer 10 formed from such a composition is not particularly limited, but may be specifically 0.5 mm to 5 mm, 1 mm to 4.5 mm, 1.5 mm to 4 mm, or 2 mm to 3 mm. When the thickness of the polishing layer 10 is within the above range, the CMP process can be performed stably and the polishing pad can be made lighter.

[0045] [Cushion layer] The cushioning layer 30 further included in the polishing pad according to the embodiment is provided under the polishing layer 10 and serves to stably support the polishing layer 10 while absorbing and / or dispersing impacts applied to the polishing layer 10. The cushioning layer 30 may be formed (manufactured) using a nonwoven fabric or a porous pad.

[0046] The thickness of the cushion layer 30 is not particularly limited, but may be 0.5 mm to 2.5 mm, 0.6 mm to 2.3 mm, 0.7 mm to 2 mm, or 1 mm to 1.5 mm. When the thickness of the cushion layer 30 is within the above range, the polishing layer 10 can be stably supported while the polishing pad can be made lighter.

[0047] [Adhesive layer] The adhesive layer 20 further included in the polishing pad according to the embodiment is provided between the polishing layer 10 and the cushion layer 30 and serves to bond the polishing layer 10 and the cushion layer 30. Furthermore, the adhesive layer 20 may also serve to prevent polishing slurry supplied to the polishing layer 10 from leaking onto the cushion layer 30. The adhesive layer 20 may be formed (manufactured) using a hot melt adhesive composition.

[0048] The hot melt adhesive composition may include a commonly known hot melt adhesive, and the hot melt adhesive may specifically include one or more selected from the group consisting of polyurethane-based resins, polyester-based resins, ethylene-vinyl acetate-based resins, polyamide-based resins, and polyolefin-based resins.

[0049] The thickness of the adhesive layer 20 is not particularly limited, but may be 5 μm to 30 μm, 10 μm to 30 μm, 20 μm to 27 μm, or 23 μm to 25 μm. When the thickness of the adhesive layer 20 is within the above range, the bonding strength (adhesion strength) between the polishing layer 10 and the cushion layer 30 can be ensured at a required level.

[0050] Meanwhile, the polishing pad according to the embodiment may contain residual chlorine components during pyrolysis. That is, the polishing pad according to the embodiment has a chlorine content controlled to a specific range after pyrolysis, which allows it to have excellent physical properties such as hardness and elastic modulus, and to exhibit a high polishing rate and polishing flatness in the CMP process.

[0051] Specifically, when the pyrolysis oil obtained from the polishing pad according to the embodiment is pyrolyzed at 320°C for 6 hours and analyzed according to the KS M 2457 standard, the chlorine content may be 13,000 mg / kg (= ppm) or more. More specifically, the chlorine content may be 13,300 mg / kg or more, 13,500 mg / kg or more, 13,800 mg / kg or more, or 14,000 mg / kg or more. For example, the chlorine content may be 13,000 mg / kg to 16,000 mg / kg, 13,300 mg / kg to 15,800 mg / kg, 13,500 mg / kg to 15,700 mg / kg, 13,800 mg / kg to 15,500 mg / kg, or 14,000 mg / kg to 15,300 mg / kg. Since the content of residual chlorine components contained in the pyrolysis oil obtained by pyrolyzing the polishing pad is within the above range, the polishing pad does not cause environmental problems due to chlorine components and can exhibit high hardness, elastic modulus, etc.

[0052] Furthermore, polishing pads according to embodiments may contain residual metal components during pyrolysis. Specifically, when the pyrolysis oil obtained by pyrolyzing the polishing pad according to embodiments at 320°C for 6 hours is analyzed by inductively coupled plasma atomic emission spectrometry, the metal component content may be less than 4 mg / kg (= ppm). More specifically, the metal component content may be 1 μg / kg (= ppb) to 2 mg / kg, 10 μg / kg to 1 mg / kg, 100 μg / kg to 800 μg / kg, or 300 μg / kg to 500 μg / kg. The metal components originate from catalyst components, etc. used in the manufacture of the polishing pad, and the detection of metal components may indicate that a polishing pad with excellent physical properties has been manufactured. Specifically, when the metal component content in the pyrolysis oil obtained by pyrolyzing the polishing pad is within the above range, the polishing pad may exhibit high strength and hardness. Meanwhile, the metal component is not particularly limited, but may specifically include one or more selected from the group consisting of cadmium (Cd), chromium (Cr), lead (Pb), and arsenic (As).

[0053] Meanwhile, pyrolysis oil obtained by pyrolyzing a polishing pad according to an embodiment may contain various substances, and when distilled, it may exhibit a boiling point in a specific range depending on the substances contained in the pyrolysis oil. Specifically, when the boiling point of the pyrolysis oil (substances contained in the pyrolysis oil) is analyzed according to ASTM D2887 (specifically, ASTM D2887-19a), the initial boiling point may be 53°C to 62°C, and the final boiling point may be 510°C to 520°C. For example, the initial boiling point of the pyrolysis oil may be 54°C to 61°C, 55°C to 60°C, 56°C to 59°C, or 57°C to 58°C. The final boiling point of the pyrolysis oil may be 511°C to 519°C, 512°C to 518°C, 513°C to 517°C, or 514°C to 516°C.

[0054] Furthermore, when the pyrolysis oil is distilled and the boiling points are analyzed, the boiling points of substances that account for 5% by weight of the pyrolysis oil are 62°C to 73°C (for example, 63°C to 72°C, or 65°C to 70°C), the boiling points of substances that account for 10% by weight of the pyrolysis oil are 73°C to 90°C (for example, 74°C to 85°C, or 75°C to 80°C), and the boiling points of substances that account for 20% by weight of the pyrolysis oil are 90°C to 110°C (for example, 92°C to 105°C, or 95°C to 100°C). The boiling point of the substance that accounts for 30% by weight of the pyrolysis oil may be 110°C to 130°C (e.g., 112°C to 125°C, or 115°C to 120°C), the boiling point of the substance that accounts for 40% by weight of the pyrolysis oil may be 130°C to 185°C (e.g., 135°C to 175°C, or 145°C to 155°C), and the boiling point of the substance that accounts for 50% by weight of the pyrolysis oil may be 185°C to 225°C (e.g., 190°C to 210°C, or 192°C to 200°C). The boiling point of the substance that accounts for 60% by weight of the pyrolysis oil is 225°C to 265°C (for example, 228°C to 245°C, or 230°C to 235°C), the boiling point of the substance that accounts for 70% by weight of the pyrolysis oil is 265°C to 325°C (for example, 270°C to 310°C, or 275°C to 285°C), and the boiling point of the substance that accounts for 80% by weight of the pyrolysis oil is 325°C to 350°C. (e.g., 328°C to 340°C, or 330°C to 335°C), the boiling point of a substance that accounts for 90% by weight of the pyrolysis oil may be 350°C to 420°C (e.g., 370°C to 400°C, or 385°C to 395°C), and the boiling point of a substance that accounts for 95% by weight of the pyrolysis oil may be 420°C to 505°C (e.g., 425°C to 480°C, or 430°C to 440°C).

[0055] Polishing pads according to such implementations can have a Shore D hardness of greater than 50, 52 or greater, 54 or greater, or 56 or greater (specifically, greater than 50 to 65, 52 to 63, 54 to 62, or 55 to 60).

[0056] In addition, the polishing pad according to the embodiment has an elastic modulus of 90 N / mm 2 Above, 95N / mm 2 Over 100N / mm 2 More than 110N / mm 2More than 120N / mm 2 or more than 130N / mm 2 More than (specifically, 90N / mm 2 ~160N / mm 2 , 95N / mm 2 ~158N / mm 2 , 100N / mm 2 ~155N / mm 2 , 110N / mm 2 ~153N / mm 2 , or 120N / mm 2 ~150N / mm 2 ) can be.

[0057] A polishing pad according to such an embodiment can exhibit excellent polishing rate and polishing flatness in a CMP process.

[0058] Specifically, the polishing pad according to the embodiment may have a polishing rate (Å / min) of 3700 Å / min or more, 3800 Å / min or more, 3900 Å / min or more, 3950 Å / min or more, or 4000 Å / min or more (specifically, 3700 Å / min to 4500 Å / min, 3800 Å / min to 4400 Å / min, 3900 Å / min to 4350 Å / min, or 4000 Å / min to 4300 Å / min).

[0059] Furthermore, the polishing pad according to the embodiment may have a polishing flatness (%) of 4.9% or more, 5.0% or more, 5.1% or more, 5.2% or more, or 5.3% or more (specifically, 4.9% to 6.5%, 5.0% to 6.3%, 5.1% to 6.2%, 5.2% to 6.1%, or 5.3% to 6.0%).

[0060] Meanwhile, the thermal decomposition temperature of the polishing pad according to the embodiment may be specifically 280°C to 345°C, 290°C to 340°C, 295°C to 330°C, 300°C to 325°C, or 310°C to 320°C.

[0061] The polishing pad according to the embodiment can be manufactured by sequentially or simultaneously mixing a urethane-based prepolymer, a curing agent, and a foaming agent to prepare a composition, and then injecting the composition into a mold and curing it to form a polishing layer.

[0062] Specifically, the mixing may be performed at a speed of 1,000 rpm to 10,000 rpm, or 4,000 rpm to 7,000 rpm. The temperature during the production of the composition by such mixing is 50°C to 150°C, and vacuum degassing may be performed as necessary.

[0063] Specifically, the step of forming the polishing layer is carried out at a temperature of 60 to 150°C and a pressure of 50 kg / m 2 ~260kg / m 2 The reaction can be carried out under pressure conditions of 0.1 to 1000 kJ / min.

[0064] The polishing pad according to the embodiment may be manufactured by further performing steps of forming an adhesive layer and a cushioning layer after forming the polishing layer, and may further undergo steps such as cutting the surface of the polishing layer, forming grooves in the surface of the polishing layer, an inspection process, and a packaging process, and these steps may be performed using conventional methods for manufacturing polishing pads.

[0065] <Pyrolysis oil> An embodiment provides pyrolysis oil obtained from a polishing pad. Specifically, the pyrolysis oil according to the embodiment is obtained from a polishing pad, and when analyzed according to the KS M 2457 standard, the pyrolysis oil may have a chlorine content of 13,000 mg / kg (= ppm) or more. Specifically, the chlorine content may be 13,300 mg / kg or more, 13,500 mg / kg or more, 13,800 mg / kg or more, or 14,000 mg / kg or more. For example, the chlorine content may be 13,000 mg / kg to 16,000 mg / kg, 13,300 mg / kg to 15,800 mg / kg, 13,500 mg / kg to 15,700 mg / kg, 13,800 mg / kg to 15,500 mg / kg, or 14,000 mg / kg to 15,300 mg / kg. When the content of the residual chlorine component contained in the pyrolysis oil is within the above range, the pyrolysis oil can be converted into a high-quality heat source.

[0066] Specifically, the pyrolysis oil obtained by pyrolyzing the polishing pad can be converted into heavy oil, naphtha, etc. through a refining process (e.g., distillation, etc.), and the heavy oil can be used as a heat source for heating oil, power plant fuel, etc. Furthermore, the naphtha can be converted into petrochemical base materials such as benzene, toluene, xylene, butanediol, etc. through a cracking process, etc., and can be used in industry.

[0067] In addition, the pyrolysis oil obtained by pyrolyzing the polishing pad may contain metal components. Specifically, the pyrolysis oil according to the embodiment may have a metal component content of less than 4 mg / kg (= ppm) when analyzed by inductively coupled plasma atomic emission spectrometry. More specifically, the metal component content may be 1 μg / kg (= ppb) to 2 mg / kg, 10 μg / kg to 1 mg / kg, 100 μg / kg to 800 μg / kg, or 300 μg / kg to 500 μg / kg. The metal component is not particularly limited, but may include one or more selected from the group consisting of cadmium, chromium, lead, and arsenic.

[0068] Furthermore, pyrolysis oil according to embodiments may contain various substances, and when distilled, it may exhibit a boiling point within a specific range depending on the substances contained in the pyrolysis oil. Specifically, when the boiling point of the pyrolysis oil (substances contained in the pyrolysis oil) is analyzed according to ASTM D2887 (specifically, ASTM D2887-19a), the initial boiling point may be 53°C to 62°C, and the final boiling point may be 510°C to 520°C. For example, the initial boiling point of the pyrolysis oil may be 54°C to 61°C, 55°C to 60°C, 56°C to 59°C, or 57°C to 58°C. The final boiling point of the pyrolysis oil may be 511°C to 519°C, 512°C to 518°C, 513°C to 517°C, or 514°C to 516°C.

[0069] Furthermore, when the pyrolysis oil is distilled and the boiling points are analyzed, the boiling points of substances that account for 5% by weight of the pyrolysis oil are 62°C to 73°C (for example, 63°C to 72°C, or 65°C to 70°C), the boiling points of substances that account for 10% by weight of the pyrolysis oil are 73°C to 90°C (for example, 74°C to 85°C, or 75°C to 80°C), and the boiling points of substances that account for 20% by weight of the pyrolysis oil are 90°C to 110°C (for example, 92°C to 105°C, or 95°C to 100°C). The boiling point of the substance that accounts for 30% by weight of the pyrolysis oil may be 110°C to 130°C (e.g., 112°C to 125°C, or 115°C to 120°C), the boiling point of the substance that accounts for 40% by weight of the pyrolysis oil may be 130°C to 185°C (e.g., 135°C to 175°C, or 145°C to 155°C), and the boiling point of the substance that accounts for 50% by weight of the pyrolysis oil may be 185°C to 225°C (e.g., 190°C to 210°C, or 192°C to 200°C). Furthermore, the boiling point of the substance that accounts for 60% by weight of the pyrolysis oil is 225°C to 265°C (for example, 228°C to 245°C, or 230°C to 235°C), the boiling point of the substance that accounts for 70% by weight of the pyrolysis oil is 265°C to 325°C (for example, 270°C to 310°C, or 275°C to 285°C), and the boiling point of the substance that accounts for 80% by weight of the pyrolysis oil is 325°C to 350°C. (e.g., 328°C to 340°C, or 330°C to 335°C), the boiling point of a substance that accounts for 90% by weight of the pyrolysis oil may be 350°C to 420°C (e.g., 370°C to 400°C, or 385°C to 395°C), and the boiling point of a substance that accounts for 95% by weight of the pyrolysis oil may be 420°C to 505°C (e.g., 425°C to 480°C, or 430°C to 440°C).

[0070] The temperature at which the polishing pad is pyrolyzed to obtain such pyrolysis oil is not particularly limited, but may be specifically 280°C to 350°C, more specifically 280°C to 345°C, 290°C to 340°C, 295°C to 330°C, 300°C to 325°C, or 310°C to 320°C.

[0071] On the other hand, once the pyrolysis of the polishing pad is complete, residual solids remain, which can be used as solid fuel.

[0072] Such pyrolysis oil is obtained from the polishing pad described above, which may be a waste polishing pad used in a CMP process. This can improve the conventional problem of difficulty in recycling waste polishing pads, and further contribute to the provision of renewable energy and the reduction of environmental problems.

[0073] <Method of producing pyrolysis oil> The embodiment provides a method for producing the pyrolysis oil. Specifically, the method includes the steps of: placing a polishing pad in a chamber (step S-1); pyrolyzing the polishing pad at 280°C to 350°C (step S-2); and passing the vaporized stream formed by the pyrolysis through a heat exchanger to obtain liquid pyrolysis oil (step S-3).

[0074] Step S-1 may involve loading a polishing pad, specifically a used polishing pad, into the chamber. That is, a used polishing pad that has been used in a CMP process may be loaded into the chamber. If the used polishing pad further includes a cushion layer and an adhesive layer in addition to the polishing layer, the used polishing pad may be loaded into the chamber in its discarded state (with the polishing layer / adhesive layer / cushion layer combined) without the process of separating each layer. In addition, one or more used polishing pads, specifically 1 to 5 or 2 to 3, may be loaded into the chamber simultaneously. This allows for easy recycling (processing) of used polishing pads.

[0075] The chamber is attached to a reactor capable of pyrolyzing the polishing pad, and may be made of a heat-resistant material and have a structure that can be separated from the reactor upon completion of pyrolysis. In addition to the polishing pad (specifically, a waste polishing pad), waste materials (scrap) generated during the manufacture of the polishing pad may also be introduced into the chamber.

[0076] Step S-2 may involve pyrolyzing the polishing pad placed in the chamber at 280°C to 350°C. Specifically, the pyrolysis temperature of the polishing pad may be 280°C to 345°C, 290°C to 340°C, 295°C to 330°C, 300°C to 325°C, or 310°C to 320°C. By pyrolyzing the polishing pad within this temperature range, pyrolysis oil can be obtained in high yield and the generation of harmful components such as dioxins during the pyrolysis process can be minimized. In addition, the chlorine content of the pyrolysis oil can be controlled to a desired level.

[0077] Meanwhile, the thermal decomposition of the polishing pad may be carried out in the presence of a catalyst. The catalyst may be any commonly known catalyst used in the thermal decomposition of polymers, and may include, for example, zeolite or potassium hydroxide. By carrying out the thermal decomposition in the presence of the catalyst, the yield of pyrolysis oil can be increased while suppressing the generation of by-products such as tar.

[0078] By carrying out such an S-2 stage, the pyrolysis oil can be vaporized and converted into a vaporized stream.

[0079] The step S-3 may include passing the vaporized stream formed by the pyrolysis through a heat exchanger to obtain a liquid pyrolysis oil. Specifically, the vaporized stream may be converted into a liquid pyrolysis oil by being cooled through the heat exchanger. The heat exchanger may be any suitable type as long as it has a known structure and material.

[0080] The pyrolysis oil obtained through the S-3 step may contain chlorine components. Specifically, when analyzed according to the KS M 2457 standard, the pyrolysis oil may have a chlorine content of 13,000 mg / kg or more. More specifically, the chlorine content may be 13,300 mg / kg or more, 13,500 mg / kg or more, 13,800 mg / kg or more, or 14,000 mg / kg or more. For example, the chlorine content may be 13,000 mg / kg to 16,000 mg / kg, 13,300 mg / kg to 15,800 mg / kg, 13,500 mg / kg to 15,700 mg / kg, 13,800 mg / kg to 15,500 mg / kg, or 14,000 mg / kg to 15,300 mg / kg.

[0081] Meanwhile, after the completion of the S-3 step, the solid matter remaining in the chamber can be used as solid fuel through a separate recovery process.

[0082] The pyrolysis oil obtained through the S-3 stage may be subjected to a refining process such as distillation.

[0083] (Example) The following examples will be used to more specifically explain this implementation, but the scope of this implementation is not limited to these examples.

[0084] Example 1 A casting machine equipped with an injection line for a urethane-based prepolymer, a curing agent, an inert gas, and a reaction rate modifier was used to manufacture a polishing pad.

[0085] Specifically, a urethane-based prepolymer (SKC) with 9.3 wt% unreacted NCO was filled into the prepolymer tank, 4,4'-methylenebis(2-chloroaniline) (Isihara) was filled into the curing agent tank, and nitrogen (N2) was used as the inert gas. 100 parts by weight of the urethane-based prepolymer were mixed with 1 part by weight of a solid-phase blowing agent (Akzonobel) and 1 part by weight of a silicone surfactant (Evonik), and then the mixture was poured into the prepolymer tank.

[0086] The raw materials were mixed at a constant rate into the mixing head through their respective feed lines. The prepolymer and curing agent were mixed at an equivalent ratio of 1:0.95, and nitrogen (N2), an inert gas, was added at a rate of 1 L / min. The mixed raw materials were discharged into a mold (1000 mm x 1000 mm x 3 mm) preheated to 80°C at a rate of 10 kg / min, and then cast at 120°C to obtain a compact. The top and bottom of the compact were then cut to a thickness of 0.5 mm to obtain a 2 mm thick abrasive sheet (abrasive layer).

[0087] Next, a cushion sheet was prepared in which a polyester fiber nonwoven fabric was impregnated with a polyurethane resin.

[0088] Thereafter, the polishing sheet and the cushion sheet were bonded together using a hot melt adhesive to prepare a polishing pad (thickness: 3.4 mm) having a structure of polishing layer / adhesive layer / cushion layer.

[0089] Example 2 A polishing pad was manufactured using a casting machine equipped with an inert gas injection line and a reaction rate modifier injection line for the urethane-based prepolymer, the curing agent, and the inert gas injection line, while the inert gas injection line was shut off.

[0090] Specifically, a urethane-based prepolymer (SKC) having 9.3 wt% unreacted NCO was filled into the prepolymer tank, and 4,4'-methylenebis(2-chloroaniline) (Ishihara) was filled into the curing agent tank. 100 parts by weight of the urethane-based prepolymer was mixed with 2 parts by weight of a solid-phase blowing agent (Akzonobel) and then poured into the prepolymer tank.

[0091] The raw materials were mixed at a constant rate while being fed into the mixing head through each feed line. The prepolymer and curing agent were added at an equivalent ratio of 1:1.05. The mixed raw materials were discharged at a rate of 10 kg / min into a mold (1000 mm x 1000 mm x 3 mm) preheated to 80°C, and then cast at 80°C to obtain a molded body. The upper and lower ends of the molded body were then cut to a thickness of 0.5 mm each to obtain a 2 mm thick abrasive sheet (abrasive layer).

[0092] Next, a cushion sheet was prepared in which a polyester fiber nonwoven fabric was impregnated with a polyurethane resin.

[0093] Thereafter, the polishing sheet and the cushion sheet were bonded together using a hot melt adhesive to prepare a polishing pad (thickness: 3.4 mm) having a structure of polishing layer / adhesive layer / cushion layer.

[0094] (Comparative Example 1) A casting machine equipped with an injection line for a urethane-based prepolymer, a curing agent, an inert gas, and a reaction rate modifier was used to manufacture a polishing pad.

[0095] Specifically, a urethane-based prepolymer (SKC) with 9.3 wt% unreacted NCO was filled into the prepolymer tank, 4,4'-methylenebis(2-chloroaniline) (Isihara) was filled into the curing agent tank, and nitrogen (N2) was used as the inert gas. 100 parts by weight of the urethane-based prepolymer were mixed with 1 part by weight of a solid-phase blowing agent (Akzonobel) and 1 part by weight of a silicone surfactant (Evonik), and then the mixture was poured into the prepolymer tank.

[0096] The raw materials were mixed at a constant rate while being fed into the mixing head through each feed line. The prepolymer and curing agent were fed at an equivalent ratio of 1:0.7, and nitrogen (N2), an inert gas, was fed at a rate of 1 L / min. The mixed raw materials were discharged at a rate of 10 kg / min into a mold (1000 mm x 1000 mm x 3 mm) preheated to 80°C, and then cast at 80°C to obtain a molded body. The top and bottom of the molded body were then cut to a thickness of 0.5 mm each to obtain a 2 mm thick abrasive sheet (abrasive layer).

[0097] Next, a cushion sheet was prepared in which a polyester fiber nonwoven fabric was impregnated with a polyurethane resin.

[0098] Thereafter, the polishing sheet and the cushion sheet were bonded together using a hot melt adhesive to produce a polishing pad (thickness: 3.4 mm) having a structure of polishing layer / adhesive layer / cushion layer.

[0099] (Comparative Example 2) A casting machine equipped with an injection line for a urethane-based prepolymer, a curing agent, an inert gas, and a reaction rate modifier was used to manufacture a polishing pad.

[0100] Specifically, a urethane-based prepolymer (SKC) with 7.1% by weight of unreacted NCO was filled into the prepolymer tank, 4,4'-methylenebis(2-chloroaniline) (Isihara) was filled into the curing agent tank, and nitrogen (N2) was used as the inert gas. 100 parts by weight of the urethane-based prepolymer was mixed with 1 part by weight of a solid-phase blowing agent (Akzonobel) and 1 part by weight of a silicone surfactant (Evonik), and then the mixture was poured into the prepolymer tank.

[0101] The raw materials were mixed at a constant rate while being fed into the mixing head through each feed line. The prepolymer and curing agent were fed at an equivalent ratio of 1:0.95, and nitrogen (N2), an inert gas, was fed at a rate of 1 L / min. The mixed raw materials were discharged at a rate of 10 kg / min into a mold (1000 mm x 1000 mm x 3 mm) preheated to 80°C, and then cast at 80°C to obtain a molded body. The upper and lower ends of the molded body were then cut to a thickness of 0.5 mm each to obtain a 2 mm thick abrasive sheet (abrasive layer).

[0102] Next, a cushion sheet was prepared in which a polyester fiber nonwoven fabric was impregnated with a polyurethane resin.

[0103] Thereafter, the polishing sheet and the cushion sheet were bonded together using a hot melt adhesive to produce a polishing pad (thickness: 3.4 mm) having a structure of polishing layer / adhesive layer / cushion layer.

[0104] (Comparative Example 3) A polishing pad was manufactured in the same manner as in Example 1, except that dimethylthiotoluene diamine (Covestro) was used instead of 4,4'-methylenebis(2-chloroaniline) as the curing agent.

[0105] (Test Example 1: Chlorine Component Content Analysis 1) Three polishing pads produced in Examples 1 and 2 and Comparative Examples 1 to 3 were placed in a chamber and pyrolyzed at 320°C for six hours. The vaporized stream formed by pyrolysis was passed through a heat exchanger to obtain liquid pyrolysis oil. After the liquid pyrolysis oil stream disappeared, the process was followed by a cooling process, completing the production of pyrolysis oil.

[0106] The produced pyrolysis oil was analyzed for the content of chlorine components in accordance with the KS M 2457 standard (KS M 2457:2003), and the results are shown in Table 1 below.

[0107] (Test Example 2: Chlorine Component Content Analysis 2) The polishing pads produced in Examples 1 and 2 were fixed to the platen of a CMP apparatus, and a silicon wafer (diameter: 300 mm) with a tungsten (W) film placed underneath was subjected to a CMP process (polishing load: 2.8 psi, calcined silica slurry applied). The CMP process was then repeated until the polishing pads were deemed unusable. The polishing pads deemed unusable (waste polishing pads) were then collected and subjected to the same process as in Test Example 1 to produce pyrolysis oil.

[0108] The produced pyrolysis oil was analyzed for the content of chlorine components in accordance with the KS M 2457 standard (KS M 2457:2003), and the results are shown in Table 1 below.

[0109] [Table 1]

[0110] Referring to Table 1, it can be seen that the polishing pads (polishing pads before the polishing process) according to Examples 1 and 2, which correspond to realization examples, have a chlorine component content of 13,000 mg / kg or more after thermal decomposition, whereas the polishing pads according to Comparative Examples 1 to 3 have a chlorine component content of less than 13,000 mg / kg after thermal decomposition.

[0111] On the other hand, the waste polishing pads from Examples 1 and 2 collected after the CMP process were also confirmed to have a chlorine content of 13,000 mg / kg or more after thermal decomposition, indicating that the chlorine components originate not from the CMP process but from the polishing pad itself.

[0112] (Test Example 3: Analysis of Metal Component Content) The pyrolysis oil of Example 1 obtained in Test Example 1 was analyzed by high-frequency inductively coupled plasma atomic emission spectrometry (analytical equipment: Perkin-Elmer, OPTIMA 7300 DV) to confirm the metal components, and the results are shown in Table 2 below.

[0113] [Table 2]

[0114] Referring to Table 2, it can be seen that trace amounts of metal components were detected in the pyrolysis oil of Example 1, which corresponds to an example of realization.

[0115] (Test Example 4: Material Analysis of Pyrolysis Oil) The pyrolysis oil of Example 1 obtained by Test Example 1 was subjected to a high-temperature simulated distillation test (SIMDIS) based on the ASTM D2887-19a standard to confirm the boiling points of each substance contained in the pyrolysis oil. The results are shown in Table 3 below.

[0116] [Table 3]

[0117] Referring to Table 3, it can be seen that the pyrolysis oil of Example 1, which corresponds to an embodiment, contains various substances, and therefore each substance has a specific boiling point.

[0118] (Test Example 5: Evaluation of the physical properties of polishing pads) The physical properties of the polishing pads produced in Examples 1 and 2 (polishing pads before the polishing process) and Comparative Examples 1 to 3 were evaluated as follows, and the results are shown in Table 4 below.

[0119] (1)Hardness A polishing pad test piece measuring 2 cm square was left for 16 hours in an environment at a temperature of 25°C and a humidity of 50±5%. After that, the Shore D hardness of the polishing pad was measured using a D-type hardness tester.

[0120] (2) Elastic modulus The elastic modulus was evaluated for a polishing pad test piece measuring 4 cm x 1 cm in length and width. Specifically, the elastic modulus was calculated by connecting the lines at 70% elongation and 20% elongation at a speed of 50 mm / min using a universal testing meter (UTM).

[0121] (3) Polishing rate A polishing pad was fixed on the platen of a CMP apparatus, and a silicon wafer (diameter: 300 mm) with the tungsten (W) film placed underneath was used for the CMP process. Specifically, the polishing load was adjusted to 2.8 psi, and calcined silica slurry was added to the polishing pad at a rate of 190 ml / min while the platen was rotated at 115 rpm for 30 seconds to polish the tungsten (W) film. After polishing, the silicon wafer was removed from the carrier, placed in a spin dryer, rinsed with purified water, and then dried for 15 seconds. The difference in thickness of the dried silicon wafer before and after polishing was measured using a contact surface resistance measurement device (four-point probe), and the polishing rate was calculated according to the following equation 1.

[0122] [Formula 1] Polishing rate (Å / min) = Polished thickness of silicon wafer (tungsten film) (Å) / Polishing time (min) (4) Polishing flatness After polishing for 1 minute under the same polishing conditions as in the polishing rate measurement, the in-plane film thickness of the silicon wafer was measured at 98 points, and the polishing flatness (WIWNU: Within Wafer Non Uniformity) was calculated according to the following formula 2.

[0123] [Formula 2] Polishing flatness (%) = (standard deviation of polished thickness (Å) / average polished thickness (Å)) × 100

[0124] [Table 4]

[0125] Referring to Table 4, it can be seen that the polishing pads of Examples 1 and 2, which correspond to practical examples, have higher hardness and elastic modulus than the polishing pads of Comparative Examples 1 to 3, and also have superior polishing rate and polishing flatness. [Explanation of symbols]

[0126] 10: Polishing layer 20: Adhesive layer 30: Cushion layer

Claims

1. 1. A polishing pad comprising a polishing layer, the polishing layer is made of a composition including a urethane-based prepolymer, a curing agent, and a foaming agent; The polishing pad is pyrolyzed at 320°C for 6 hours to obtain a pyrolysis oil, which, when analyzed according to the KS M 2457 standard, has a chlorine content of 13,000 mg / kg to 16,000 mg / kg; When the pyrolysis oil is analyzed according to the ASTM D2887 standard, the initial boiling point of the pyrolysis oil is 53°C to 62°C, and the final boiling point of the pyrolysis oil is 510°C to 520°C. A polishing pad.

2. 2. The polishing pad according to claim 1, wherein the pyrolysis oil has a metal content of less than 4 mg / kg when analyzed by inductively coupled plasma atomic emission spectrometry.

3. 10. The polishing pad of claim 1, wherein the curing agent comprises 4,4'-methylenebis(2-chloroaniline).

4. The urethane-based prepolymer has an isocyanate terminal group content (NCO%) of 7.5% by weight to 11% by weight, 2. The polishing pad according to claim 1, wherein the reaction ratio of the urethane-based prepolymer to the curing agent is an equivalent ratio of 1:0.75 to 1.

1.

5. A pyrolysis oil derived from a polishing pad including a polishing layer, the polishing layer is made of a composition including a urethane-based prepolymer, a curing agent, and a foaming agent; When analyzed according to the KS M 2457 standard, the chlorine content is 13,000 mg / kg to 16,000 mg / kg; When the pyrolysis oil is analyzed according to ASTM D2887 standard, the initial boiling point of the pyrolysis oil is 53°C to 62°C, and the final boiling point of the pyrolysis oil is 510°C to 520°C.

6. Loading a polishing pad including a polishing layer into a chamber; Pyrolyzing the polishing pad introduced into the chamber at 280°C to 350°C; and passing the vaporized stream formed by the pyrolysis through a heat exchanger to obtain a liquid pyrolysis oil; the polishing layer is made from a composition including a urethane-based prepolymer, a curing agent, and a foaming agent; When the pyrolysis oil is analyzed according to the KS M 2457 standard, the content of chlorine components is 13,000 mg / kg to 16,000 mg / kg; When the pyrolysis oil is analyzed according to ASTM D2887 standard, the initial boiling point of the pyrolysis oil is 53°C to 62°C, and the final boiling point of the pyrolysis oil is 510°C to 520°C.

7. The method for producing pyrolysis oil according to claim 6, wherein the polishing pad is a used polishing pad.

Images