Polishing pad with excellent recoverability and pyrolysis oil obtained therefrom

Abstract

Embodiments relate to a polishing pad including a polishing layer. The chlorine (Cl) content is less than 10,000 ppm when pyrolysis oil obtained by pyrolyzing the polishing layer at 320 DEG C for 6 hours is analyzed by combustion ion chromatography (C-IC) according to the IEC 62321-3-2 standard.

Description

Technical Field

[0001] Embodiments relate to a polishing pad for use in a chemical mechanical planarization (CMP) process of a semiconductor device, and pyrolytic oil obtained from the polishing pad. Background Art

[0002] In the semiconductor manufacturing process, the chemical mechanical planarization (CMP) process refers to the steps of fixing a semiconductor substrate (such as a wafer) on a head and contacting the surface of a polishing pad mounted on a polishing disk, and moving the polishing disk and the head relative to each other to smooth out irregularities on the surface of the semiconductor substrate.

[0003] In this CMP process, the polishing pad needs to have stable physical properties because it has a great influence on the surface processing quality of the semiconductor substrate. In particular, since the polishing rate of the CMP process may be sensitive to the components contained in the polishing pad and its physical properties, it is necessary to optimize the components contained in the polishing pad and its physical properties.

[0004] Meanwhile, as environmental issues have become increasingly prominent, attempts have been made to recycle used polishing pads. However, the recycling process of polishing pads (e.g., melt processing using thermal energy) is difficult, and discarded polyurethane polishing pads cannot be degraded, causing environmental problems. Therefore, attempts have been made to use the pyrolysis oil recovered from the pyrolysis of waste polishing pads as an energy source, or to prepare polyols as a raw material for polishing pads for regeneration of polishing pads. Meanwhile, polishing pads generally contain highly toxic halogen elements such as chlorine, which remain even after thermal decomposition, making recycling difficult.

[0005] Therefore, there is a need to develop a polishing pad technology that is excellent in overall physical properties and performance during the CMP process and has high recyclability through thermal decomposition after use.

[0006] Prior art documents

[0007] (Patent Document 1) Korean Patent Application No. 2009-0029336 Summary of the invention

[0008] Technical issues

[0009] In order to solve the above-mentioned conventional problems, the inventors have conducted research and found that a polishing pad in which the residual chlorine content after pyrolysis of polyurethane is controlled within a specific range can be obtained. Based on this, the occurrence of defects and scratches in the CMP process can be minimized while maintaining the excellent physical properties and performance of the polishing pad. In addition, the pyrolysis oil obtained by pyrolysis of the polishing pad can be used as an energy source or recycled as an organic resource, such as a raw material for preparing a polishing pad, thereby reducing the environmental burden.

[0010] Therefore, the embodiment aims to provide a polishing pad having excellent physical properties by controlling the content of residual chlorine components after pyrolysis. In addition, the embodiment aims to provide pyrolysis oil obtained by pyrolysis of a polishing pad and a preparation method thereof.

[0011] Solution to the problem

[0012] According to an embodiment to solve the above problems, there is provided a polishing pad including a polishing layer, wherein when pyrolysis oil obtained by pyrolyzing the polishing layer at 320° C. for 6 hours is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2 standard, the chlorine (Cl) content is less than 10,000 ppm.

[0013] According to another embodiment, there is provided a pyrolysis oil obtained from a polishing layer of a polishing pad, having a chlorine (Cl) content of less than 10,000 ppm when analyzed by combustion ion chromatography (C-IC) according to IEC62321-3-2 standard.

[0014] Advantageous Effects of the Invention

[0015] In the polishing pad according to the embodiment, the residual chlorine content after the pyrolysis of the polishing layer is adjusted to a certain range; therefore, the occurrence of defects and scratches in the CMP process can be minimized while maintaining the excellent physical properties and performance of the polishing pad. Therefore, when the CMP process is performed using the polishing pad, a semiconductor substrate (e.g., a wafer) with excellent surface processing quality can be provided while achieving a high polishing rate.

[0016] In addition, the pyrolysis oil according to the embodiment is obtained by pyrolyzing the polishing layer of the polishing pad and can be used as a high-quality energy source through a refining process. Therefore, the embodiment helps to improve environmental issues while increasing the recovery rate of the polishing pad. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a cross-sectional view of a polishing pad according to an embodiment.

[0018] Figure 2 The process of obtaining pyrolysis oil by pyrolysis of a polishing pad is shown.

[0019] Figure 3 The process of obtaining energy and basic raw materials from pyrolysis oil is shown.

[0020] (Reference numerals—10: polishing layer, 20: adhesive layer, 30: support layer, 100: chamber, 200: heat exchanger, 300: distillation column) DETAILED DESCRIPTION

[0021] In the following description of the embodiments, when it is judged that the description may make the subject matter of the embodiments unclear, the detailed description of known functions and configurations will be omitted. In addition, for the needs of the specification, the size of each element in the drawings may be enlarged or omitted and may be different from the actual size.

[0022] In this specification, when a component is described as being located above / below another component or being connected or coupled to each other, it covers the case where these components are directly or indirectly formed, connected, or coupled through other components. In addition, it should be understood that the criteria of "above" and "below" of each component may vary depending on the direction of the object being observed.

[0023] In this specification, the terms related to each component are used to distinguish the differences between them and are not intended to limit the scope of the embodiments. In addition, in this specification, a singular expression is interpreted as including the plural unless otherwise specified in the context.

[0024] In this specification, terms such as "first", "second", etc. are used to describe various components. However, these components should not be limited by these terms. These terms are used to distinguish one element from another.

[0025] In this specification, the word "comprising" is intended to specify features, regions, steps, processes, elements, and components. Unless otherwise explicitly stated, the existence or addition of any other features, regions, steps, processes, elements, and components is not excluded.

[0026] For convenience, the molecular weight of the compound or polymer described in this specification is expressed in molar mass units, but can be understood as a relative mass relative to carbon- 12. In addition, the molecular weight of the compound or polymer described in this specification can be interpreted as a number average molecular weight or a weight average molecular weight, for example, as a number average molecular weight.

[0027] In the present specification, in the numerical ranges limiting component size, physical properties, etc., when a numerical range limited to an upper limit and a numerical range limited to a lower limit are separately exemplified, it should be understood that the numerical range combining these upper and lower limits is also included in the exemplary range of the present invention.

[0028] Polishing pad

[0029] According to one embodiment, a polishing pad includes a polishing layer.

[0030] Figure 1 is a cross-sectional view of a polishing pad according to one embodiment. Figure 1 The polishing pad may include a support layer (30) located below the polishing layer (10). In addition, an adhesive layer (20) may be inserted between the polishing layer and the support layer.

[0031] In an embodiment, when pyrolysis oil obtained by pyrolyzing the polishing layer at 320° C. for 6 hours is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2 standard, the chlorine (Cl) content is less than 10,000 ppm.

[0032] The IEC 62321-3-2 standard using combustion ion chromatography (C-IC) is a detection method for screening halogen components developed based on the use specifications of halogens. Compared with traditional halogen analysis methods (such as oxygen bomb ion chromatography and oxygen bottle ion chromatography), the test method has excellent precision, accuracy, and reproducibility, and is automated; therefore, the reliability of the test results is very high.

[0033] According to one embodiment, the chlorine content in the pyrolysis oil obtained from the polishing layer of the polishing pad may be less than 10,000 ppm, for example, 5,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 200 ppm or less, 100 ppm or less, 80 ppm or less, 50 ppm or less, 30 ppm or less, 20 ppm or less, or 10 ppm or less. With the chlorine content adjusted to the above range, the size of the debris can be reduced while maintaining the excellent physical properties and performance of the polishing pad, thereby minimizing the occurrence of defects and scratches in the CMP process.

[0034] In addition, according to one embodiment, the lower limit of the range of the chlorine content in the pyrolysis oil obtained from the polishing layer of the polishing pad may be, for example, 0 ppm or more, greater than 0 ppm, 1 ppm or more, 2 ppm or more, 3 ppm or more, 4 ppm or more, or 5 ppm or more. Within the above range, the surface area and adsorption force can be adjusted as the debris is aggregated into an appropriate size to facilitate adsorption and desorption in the wafer and the polishing pad, and the electrical attraction and repulsion can be adjusted to make the polishing performance more suitable.

[0035] As a specific embodiment, when the pyrolysis oil obtained by pyrolyzing the polishing layer at 320°C for 6 hours is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2, the chlorine (Cl) content may be 1 ppm or more and less than 10,000 ppm. As another specific embodiment, when the pyrolysis oil is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2, the chlorine (Cl) content may be 1 ppm to 1,000 ppm. As another specific embodiment, when the pyrolysis oil is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2, the chlorine (Cl) content may be 1 ppm to 100 ppm. As another specific embodiment, when the pyrolysis oil is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2, the chlorine (Cl) content may be 1 ppm to 10 ppm.

[0036] Since the polishing pad according to an embodiment has the chlorine content adjusted to a certain range as described above, the size of debris can be reduced, thereby minimizing the occurrence of defects and scratches in the CMP process.

[0037] In addition, according to one embodiment, the polishing pad includes a certain content of sulfur (S) during pyrolysis. As a result, the size of the debris can be adjusted while maintaining the excellent overall physical properties and performance of the polishing pad, thereby reducing the occurrence of defects and scratches in the CMP process and improving process stability. For example, when the pyrolysis oil is analyzed using an elemental analyzer, the sulfur (S) content may be 1 ppm to 100 ppm. Specifically, when the pyrolysis oil is analyzed using an elemental analyzer, the sulfur (S) content may be 3 ppm to 100 ppm. More specifically, when the pyrolysis oil is analyzed using an elemental analyzer, the sulfur (S) content may be 3 ppm to 100 ppm. More specifically, when the pyrolysis oil is analyzed using an elemental analyzer, the sulfur (S) content may be 3 ppm to 10 ppm.

[0038] In addition, according to one embodiment, when the polishing layer is pyrolyzed, the polishing pad may include a certain amount of residual metal components. For example, when the pyrolysis oil obtained by pyrolyzing the polishing layer at 320° C. for 6 hours is analyzed using ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer), the total content of the metal components may be 1 ppm to 3,000 ppm. Specifically, when the pyrolysis oil is analyzed using ICP-OES, the total content of the metal components may be 1 ppm to 3,000 ppm, 1 ppm to 1,500 ppm, 1 ppm to 1,000 ppm, 1 ppm to 100 ppm, or 1 ppm to 10 ppm. More specifically, when the pyrolysis oil is analyzed using ICP-OES, the total content of the metal components may be 3 ppm to 3,000 ppm, 3 ppm to 1,500 ppm, 3 ppm to 1,000 ppm, 3 ppm to 100 ppm, or 3 ppm to 10 ppm.

[0039] The metal component originates from the catalyst component used in preparing the polishing pad, and the detection of the metal component may mean that a polishing pad having excellent physical properties has been prepared. Specifically, as the metal component content in the pyrolysis oil obtained by pyrolysis of the polishing layer is within the above range, the polishing pad can have high strength and hardness.

[0040] Meanwhile, the metal component is not particularly limited, but it may specifically include at least one selected from the group consisting of aluminum (Al), iron (Fe), cadmium (Cd), chromium (Cr), lead (Pb), and arsenic (As). In a specific embodiment, when the pyrolysis oil is analyzed using ICP-OES, the aluminum (Al) content may be 1 ppm to 100 ppm, 1 ppm to 50 ppm, 1 ppm to 10 ppm, or 1 ppm to 5 ppm. In another specific embodiment, when the pyrolysis oil is analyzed using ICP-OES, the iron (Fe) content may be 1 ppm to 100 ppm, 1 ppm to 50 ppm, 1 ppm to 10 ppm, or 1 ppm to 5 ppm. In a more specific embodiment, when the pyrolysis oil is analyzed using ICP-OES, the aluminum (Al) content and the iron (Fe) content may each be 1 ppm to 50 ppm.

[0041] In addition, when the pyrolysis oil is analyzed using ICP-OES, the silicon (Si) content may be 1 ppm to 3,000 ppm, specifically, 100 ppm to 3,000 ppm.

[0042] In addition, according to one embodiment, the pyrolysis oil may contain various substances. When distilled, the pyrolysis oil may exhibit a specific range of boiling points according to the different substances contained. Specifically, when the pyrolysis oil (the substances contained in the pyrolysis oil) is analyzed according to the ASTM D2887 (specifically, ASTM D2887-19a) standard, the initial boiling point may be 10°C to 50°C, and the final boiling point may be 400°C to 500°C. Specifically, the initial boiling point of the pyrolysis oil may be 30°C to 40°C, and the final boiling point of the pyrolysis oil may be 430°C to 460°C.

[0043] When the pyrolysis oil is distilled to analyze its boiling point, the boiling point of the substance accounting for 5% by weight of the pyrolysis oil may be 10°C to 69°C. The boiling point of the substance accounting for 10% by weight of the pyrolysis oil may be 69°C to 73°C. The boiling point of the substance accounting for 20% by weight of the pyrolysis oil may be 73°C to 78°C. The boiling point of the substance accounting for 30% by weight of the pyrolysis oil may be 78°C to 87°C. The boiling point of the substance accounting for 40% by weight of the pyrolysis oil may be 87°C to 112°C. The boiling point of the substance accounting for 50% by weight of the pyrolysis oil may be 112°C to 137°C. The boiling point of the substance accounting for 60% by weight of the pyrolysis oil may be 137°C to 163°C. The boiling point of the substance accounting for 70% by weight of the pyrolysis oil may be 163°C to 199°C. The boiling point of the material accounting for 80% by weight of the pyrolysis oil may be 199° C. to 298° C. The boiling point of the material accounting for 90% by weight of the pyrolysis oil may be 298° C. to 358° C. The boiling point of the material accounting for 95% by weight of the pyrolysis oil may be 358° C. to 500° C.

[0044] Furthermore, according to one embodiment, the polishing pad has excellent performance and overall physical properties.

[0045] When a polishing pad is used to polish the silicon oxide layer of a silicon wafer with a ceria slurry, the polishing rate (removal rate) can reach above, above, Above, or Above, and the following, the following, Below, or As an example, when a polishing pad is used to polish a silicon oxide layer of a silicon wafer using a ceria slurry, the polishing rate determined according to the following equation may be: to

[0046]

[0047] Specifically, the polishing rate may be a polishing rate for a silicon wafer having a diameter of 300 mm on which silicon oxide has been deposited. In addition, the polishing rate may be measured under a polishing load of 4.0 psi while the polishing pad is rotated at a speed of 150 rpm, the calcined cerium oxide slurry is supplied to the polishing pad at a rate of 250 ml / min, and the polishing disk is rotated at a speed of 150 rpm for 60 seconds. The temperature condition when measuring the polishing rate is not particularly limited, but it may be, for example, room temperature condition.

[0048] In addition, the pad cut rate of the polishing layer may be 30 μm / hr to 60 μm / hr, 30 μm / hr to 50 μm / hr, 40 μm / hr to 60 μm / hr, or 40 μm / hr to 50 μm / hr.

[0049] The thickness of the polishing pad 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. Within the above range, the basic physical properties of the polishing pad can be fully exhibited while minimizing the particle size variation between the upper and lower parts.

[0050] Polishing layer

[0051] The polishing layer provides a polishing surface that contacts the semiconductor substrate during the CMP process and constitutes a top pad of the polishing pad.

[0052] According to one embodiment, the polishing layer includes a polyurethane resin.

[0053] The polishing layer includes a urethane-based prepolymer, a foaming agent, and a curing agent. Specifically, the polyurethane resin may be formed from a composition including a urethane-based prepolymer, a foaming agent, and a curing agent.

[0054] More specifically, the polishing layer includes a polyurethane-based resin, which is a reaction product of an urethane-based prepolymer, a blowing agent, and a curing agent, i.e., a cured product of a composition in which the components are mixed. Therefore, it includes a porous polyurethane-based resin. In addition, the polishing layer may include a plurality of pores formed by the blowing agent.

[0055] The polishing layer may have a thickness of, for example, 0.8 mm or more, 1 mm or more, 1.2 mm or more, or 1.5 mm or more, and 5 mm or less, 3 mm or less, 2.5 mm or less, or 2 mm or less. As a specific embodiment, the thickness of the polishing layer may be 0.8 mm to 5 mm or 1.5 mm to 3 mm.

[0056] The polishing layer may have, for example, 0.6 g / cm 3 Above, 0.7g / cm 3 Above, or 0.75g / cm 3 Above, and 0.9g / cm 3 Below, 0.85g / cm 3 Below, or 0.8g / cm 3 As a specific embodiment, the specific gravity of the polishing layer can be 0.6 g / cm 3 Up to 0.9g / cm 3 or 0.7g / cm 3 Up to 0.9g / cm 3 .

[0057] The polishing layer may have a hardness of, for example, 30 Shore D or more, 40 Shore D or more, or 50 Shore D or more, and 80 Shore D or less, 70 Shore D or less, 65 Shore D or less, or 60 Shore D or less. As a specific embodiment, the hardness of the polishing layer may be 30 Shore D to 80 Shore D or 50 Shore D to 65 Shore D.

[0058] The polishing layer may have, for example, a tensile strength of 5 N / mm2 or more, 10 N / mm2 or more, or 15 N / mm2 or more, and 30 N / mm2 or less, 25 N / mm2 or less, or 20 N / mm2 or less. As a specific embodiment, the tensile strength of the polishing layer may be 5 N / mm 2 Up to 30N / mm 2 or 15N / mm 2 Up to 25N / mm 2 .

[0059] The polishing layer may have, for example, an elongation of 50% or more, 70% or more, 90% or more, 106% or more, or 120% or more, and 300% or less, 250% or less, 200% or less, or 150% or less. As a specific embodiment, the elongation of the polishing layer may be 50% to 300% or 90% to 130%. The elongation may be elongation at break.

[0060] As a specific example, the polishing layer may have a hardness of 50 Shore D to 65 Shore D, a strength of 15 N / mm 2 Up to 25N / mm 2 Tensile strength, and elongation of 90% to 130%.

[0061] The pores exist in the polishing layer in a dispersed form.

[0062] The average diameter of the pores may be, for example, 10 μm to 60 μm, 10 μm to 50 μm, 20 μm to 50 μm, 20 μm to 40 μm, 10 μm to 30 μm, 20 μm to 25 μm, or 30 μm to 50 μm.

[0063] In addition, the total area of ​​the pores may be 30% to 60%, 35% to 50%, or 35% to 43% based on the total area of ​​the polishing layer. In addition, the total volume of the pores may be 30% to 70%, or 40% to 60% based on the total volume of the polishing layer.

[0064] The surface of the polishing layer may have grooves for mechanical polishing. The grooves may have a depth, width, and pitch designed according to the needs of mechanical polishing, without particular limitation.

[0065] The polishing pad according to one embodiment has a chlorine content adjusted to a certain range, thereby reducing the size of debris while maintaining excellent physical properties and performance of the polishing pad, thereby minimizing the occurrence of defects and scratches in the CMP process. For example, when the polishing layer is analyzed by combustion ion chromatography (C-IC) according to the IEC 62321-3-2 standard, the chlorine (Cl) content may be less than 10,000 ppm. Specifically, the chlorine content in the polishing layer may be 5,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 200 ppm or less, 100 ppm or less, 80 ppm or less, or 50 ppm or less.

[0066] In addition, according to one embodiment, the lower limit of the range of chlorine content in the polishing layer can be, for example, 0 ppm or more, greater than 0 ppm, 1 ppm or more, 5 ppm or more, 10 ppm or more, 20 ppm or more, 50 ppm or more, or 100 ppm or more. Within the above preferred range, the surface area and adsorption force can be adjusted as the debris is aggregated into an appropriate size to facilitate adsorption and desorption in the wafer and the polishing pad, and the electrical attraction and repulsion can be adjusted to make the polishing performance more suitable.

[0067] As a specific embodiment, when the polishing layer is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2, the chlorine (Cl) content may be 10 ppm to 1,000 ppm. As another specific embodiment, when the polishing layer is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2, the chlorine (Cl) content may be 10 ppm to 100 ppm, 20 ppm to 80 ppm, or 20 ppm to 50 ppm. As another specific embodiment, when the polishing layer is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2, the chlorine (Cl) content may be 50 ppm to 10,000 ppm or 100 ppm to 10,000 ppm.

[0068] The chlorine content can be obtained by measuring the chlorine content in a sample by IEC 62321-3-2 standard, which is an international standard for measuring the content of a specific substance by combustion ion chromatography (C-IC). In this case, the sample for measuring the chlorine content may be a circular sample with a diameter of 3 cm and a height of 0.3 cm taken out from the polishing layer of the polishing pad.

[0069] Urethane prepolymer

[0070] According to one embodiment, the polishing layer of the polishing pad includes a urethane-based prepolymer.

[0071] Prepolymers generally refer to polymers with relatively low molecular weights whose degree of polymerization is adjusted to a moderate level so that they can be easily molded in the process of producing cured products. Prepolymers can be molded into final cured products by themselves or after reacting with another polymerizable compound.

[0072] In one embodiment, the urethane-based prepolymer may be prepared by reacting an isocyanate compound with a polyol.

[0073] The isocyanate compound used for preparing the urethane-based prepolymer may be one selected from the group consisting of aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, or a combination thereof.

[0074] The isocyanate compound may include, for example, one selected from the group consisting of 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 1,5-naphthyl diisocyanate, phenyl p-diisocyanate, toluene diisocyanate, 4,4′-diphenylmethyl diisocyanate, hexamethylene diisocyanate, dicyclohexylmethyl diisocyanate, isophorone diisocyanate, and combinations thereof.

[0075] The polyol is a compound including at least two hydroxyl groups (—OH) per molecule, and may include one selected from the group consisting of polyether polyol, polyester polyol, polycarbonate polyol, polycaprolactone polyol, and a combination thereof.

[0076] The polyol may include, for example, 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-butylene glycol, 1,3-butylene glycol, 2-methyl-1,3-propylene glycol, 1,4-butylene glycol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, tripropylene glycol, and combinations thereof.

[0077] The polyol may have a weight average molecular weight (Mw) of 100 to 3,000. The polyol may have a weight average molecular weight (Mw), for example, of 100 to 3,000, for example, of 100 to 2,000, for example, of between 100 and 1,800.

[0078] In one embodiment, the polyol may include a low molecular weight polyol having a weight average molecular weight (Mw) of 100 to 300 and a high molecular weight polyol having a weight average molecular weight (Mw) of 300 to 1,800.

[0079] In addition, the urethane-based prepolymer may have a weight average molecular weight (Mw) of about 500 to about 3,000. The urethane-based prepolymer may have a weight average molecular weight (Mw), for example, of about 1,000 to about 2,000, or for example, of about 1,000 to about 1,500.

[0080] In one embodiment, the isocyanate compound used to prepare the urethane-based prepolymer may include an aromatic diisocyanate compound, and the aromatic diisocyanate compound, for example, may include 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI). The polyol compound used to prepare the urethane-based prepolymer may include polytetramethylene ether glycol (PTMEG) and diethylene glycol (DEG).

[0081] In another embodiment, the isocyanate compound for preparing the urethane-based prepolymer may include an aromatic diisocyanate compound and an alicyclic diisocyanate compound. For example, the aromatic diisocyanate compound may include 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI), and the alicyclic diisocyanate compound may include dicyclohexylmethyl diisocyanate (H12MDI). The polyol compound for preparing the urethane-based prepolymer may include polytetramethylene ether glycol (PTMEG) and diethylene glycol (DEG).

[0082] The urethane-based prepolymer may have an isocyanate terminal group content (NCO%) of 5 wt % or more, 7.5 wt % or more, or 10 wt % or more, and 13 wt % or less, 12 wt % or less, or 11 wt % or less. As a specific embodiment, the urethane-based prepolymer may have an isocyanate terminal group content (NCO%) of 7.5 wt % to 12 wt %. As a more specific embodiment, the urethane-based prepolymer may have an isocyanate terminal group content (NCO%) of 11 wt % to 12 wt %.

[0083] The isocyanate terminal group content (NCO%) of the urethane-based prepolymer can be designed by comprehensively adjusting the type and content of the isocyanate compound and polyol compound used to prepare the prepolymer, the process conditions such as temperature, pressure and time during the preparation process, and the type and content of additives used in the preparation process.

[0084] If the isocyanate terminal group content (NCO%) of the urethane-based prepolymer satisfies the above range, in the subsequent reaction between the urethane-based prepolymer and the curing agent, the reaction rate, reaction time, and final cured structure can be adjusted from the perspective of the use and purpose of the final polishing pad to facilitate polishing performance.

[0085] In one embodiment, the urethane-based prepolymer may have an isocyanate terminal group content (NCO%) of 8 wt % to 10 wt %, for example, 8 wt % to 9.4 wt %. If the NCO% of the urethane-based prepolymer is lower than the above range, electrical properties based on the chemically hardened structure in the polishing pad may be achieved, thereby failing to achieve the desired polishing performance in terms of polishing rate and flatness, and the polishing pad may also have a shortened service life due to an excessively high cutting rate. On the other hand, if the NCO% exceeds the above range, surface defects on the semiconductor substrate, such as scratches and vibration marks, may increase.

[0086] Foaming agent

[0087] The foaming agent is a component for forming a pore structure in the polishing layer, and may include one selected from the group consisting of a solid-phase foaming agent, a gas-phase foaming agent, a liquid-phase foaming agent, and a combination thereof.

[0088] According to one embodiment, the foaming agent may be a non-chlorine-based foaming agent that does not contain a chlorine component. In particular, it may not contain or minimize the use of chlorine-based foaming agent components commonly used in the preparation of polishing pads, such as vinylidene chloride (VDC). For example, based on the total weight of the foaming agent, the content of the non-chlorine-based foaming agent may be 50% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, 97% by weight or more, 99% by weight or more, or 99.5% by weight or more, and 100% by weight or less or 99.5% by weight or less, as a specific embodiment, 80% by weight to 100% by weight, 90% by weight to 100% by weight, or 80% by weight to 99.5% by weight. In addition, based on the total weight of the blowing agent, the content of the chlorine-based blowing agent may be less than 20 weight %, less than 10 weight %, less than 5 weight %, less than 1 weight %, less than 0.5 weight %, or less than 0.3 weight %, and more than 0 weight %, more than 0.1 weight %, or more than 0.5 weight %, as specific embodiments, 0 weight % to 20 weight %, 0 weight % to 1 weight %, 0 weight % to 0.5 weight %, or 0.5 weight % to 20 weight %.

[0089] The foaming agent may be at least one selected from a solid-phase foaming agent including particles having a hollow structure, a liquid-phase foaming agent using a volatile liquid, and an inert gas.

[0090] As an example, the solid phase foaming agent may include hollow structure particles that expand and adjust their size by heating. The advantage of such a solid phase foaming agent is that it is used as a raw material in an expanded form, the size of the pores can be controlled to be uniform, and the particle size is uniform.

[0091] In addition, the solid phase foaming agent may include expandable particles. Expandable particles are particles that have the property of being able to expand after being heated or pressurized. Their size in the final polishing layer can be determined by the heat or pressure applied during the preparation of the polishing layer. The expandable particles are used in the raw material in the state of particles that have not yet expanded. Their final size is determined when they are expanded by the heat or pressure applied during the preparation of the polishing layer.

[0092] The solid-phase foaming agent may have an average particle size of 5 μm to 100 μm, specifically, 5 μm to 50 μm or 20 μm to 50 μm. As described below, when the solid-phase foaming agent is a particle used in an expanded state in a raw material, the average particle size of the solid-phase foaming agent may refer to the average particle size of the expanded particles themselves. As described below, when the solid-phase foaming agent is a particle used in an unexpanded state in a raw material, it may refer to the average particle size of the particles after undergoing heat or pressure expansion in a preparation method.

[0093] The solid phase foaming agent in the form of expandable particles may include a resin shell; and an expansion inducing component wrapped in the shell. The expandable particles may be heated in the preparation method to evaporate the wrapped expansion inducing component to form a hollow structure.

[0094] For example, the housing may be composed of a thermoplastic resin. The thermoplastic resin may be at least one selected from the group consisting of an acrylonitrile-based copolymer, a methacrylonitrile-based copolymer, and an acrylic copolymer.

[0095] The thickness of the shell may be, for example, greater than 0.1 μm, greater than 0.5 μm, greater than 1 μm, greater than 2 μm, or greater than 3 μm, and less than 15 μm, less than 12 μm, or less than 10 μm; as a specific embodiment, 2 μm to 15 μm.

[0096] The expansion inducing component may include one selected from the group consisting of hydrocarbon compounds, tetraalkylsilane compounds, and combinations thereof. Specifically, the hydrocarbon compound may include one selected from the group consisting of ethane, ethylene, propane, propylene, n-butane, isobutane, n-butene, isobutylene, n-pentane, isopentane, neopentane, n-hexane, heptane, petroleum ether, and combinations thereof. The tetraalkylsilane compound may include one selected from the group consisting of tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, trimethyl-n-propylsilane, and combinations thereof.

[0097] The solid phase foaming agent may include particles treated with an inorganic component. In one embodiment, the solid phase foaming agent may be a foaming agent treated with silicon dioxide (SiO2) particles. Treating the solid phase foaming agent with an inorganic component may prevent aggregation between multiple particles. The solid phase foaming agent treated with an inorganic component may differ from a solid phase foaming agent that has not been treated with an inorganic component in chemical, electrical, and / or physical properties on the foaming agent surface.

[0098] Commercial products of solid phase foaming agents include Nouryon’s 920DE20d70, 051DET40d25, and 051DET40d42 and Matsumoto’s F-65DE, F-80DE, and FN-80SDE.

[0099] As a specific example, the foaming agent for the polishing pad according to an embodiment includes a solid-phase foaming agent. The solid-phase foaming agent may include at least one selected from the group consisting of acrylonitrile-based copolymers, methyl methacrylate-based copolymers, methacrylonitrile-based copolymers, and acrylic acid-based copolymers.

[0100] The content of the solid-phase foaming agent may be greater than 0.1 parts by weight, greater than 0.5 parts by weight, or greater than 1 part by weight, and less than 5 parts by weight, less than 3 parts by weight, or less than 2 parts by weight, relative to 100 parts by weight of the urethane-based prepolymer. As a specific embodiment, the content of the solid-phase foaming agent may be 0.1 parts by weight to 5 parts by weight or 0.5 parts by weight to 2 parts by weight, relative to 100 parts by weight of the urethane-based prepolymer.

[0101] The type and content of the solid phase foaming agent can be designed according to the desired pore structure and physical properties of the polishing layer.

[0102] Meanwhile, the liquid-phase foaming agent can be introduced during the mixing and reaction of the prepolymer and the curing agent to form pores. The liquid-phase foaming agent does not participate in the reaction between the prepolymer and the curing agent. In addition, the liquid-phase foaming agent physically evaporates under the action of the heat generated during the mixing reaction of the prepolymer and the curing agent to form pores.

[0103] The volatile liquid-phase blowing agent may be in a liquid state at 25°C, and it does not react with an isocyanate group, an amide group, and an alcohol group. Specifically, the volatile liquid-phase blowing agent may be selected from the group consisting of cyclopentane, n-pentane, cyclohexane, n-butyrate, bis(perfluorobutyl)(trifluoromethyl)amine; and perfluoro compounds such as perfluorotributylamine, perfluoro-N-methylmorpholine, perfluorotripentylamine, and perfluorohexane. Commercially available perfluoro compound products include FC-40 (3M), FC-43 (3M), FC-70 (3M), FC-72 (3M), FC-770 (3M), FC-3283 (3M), and FC-3284 (3M).

[0104] In addition, the foaming agent may include a gas phase foaming agent. For example, the foaming agent may include a solid phase foaming agent and a gas phase foaming agent.

[0105] The gas phase blowing agent may include an inert gas. The gas phase blowing agent is introduced as a component for forming pores during the reaction of the urethane-based prepolymer and the curing agent.

[0106] The type of inert gas is not particularly limited as long as it is a gas that does not participate in the reaction between the urethane-based prepolymer and the curing agent. For example, the inert gas may include one selected from the group consisting of nitrogen (N2), carbon dioxide (CO2), argon (Ar), helium (He), and a combination thereof.

[0107] The type and content of the gas phase foaming agent can be designed according to the desired pore structure and physical properties of the polishing layer.

[0108] Based on the total volume of the composition, the amount of inert gas introduced may be 10% to 30%. Specifically, based on the total volume of the composition, the amount of inert gas introduced may be 15% to 30%. Specifically, the gas phase blowing agent may be introduced through a predetermined feeding pipeline during the mixing process of the urethane-based prepolymer, the solid phase blowing agent, and the curing agent. The feed rate of the gas blowing agent is about 0.8L / min to about 2.0L / min, for example, about 0.8L / min to about 1.8L / min, for example, about 0.8L / min to about 1.7L / min, for example, about 1.0L / min to about 2.0L / min, for example, about 1.0L / min to about 1.8L / min, for example, about 1.0L / min to about 1.7L / min.

[0109] Curing agent

[0110] The curing agent is a compound that chemically reacts with the urethane-based prepolymer to form a final cured structure in the polishing layer. For example, it may include an amine compound or an alcohol compound. Specifically, the curing agent may include one selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, aliphatic alcohols, and combinations thereof.

[0111] According to one embodiment, the curing agent may include a non-chlorine-based curing agent that does not contain chlorine components. For example, based on the total weight of the curing agent, the content of the non-chlorine-based curing agent may be 50% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, 97% by weight or more, 99% by weight or more, or 99.5% by weight or more, and 100% by weight or less or 99.5% by weight or less, as a specific embodiment, 80% by weight to 100% by weight, 90% by weight to 100% by weight, or 80% by weight to 99.5% by weight. In addition, based on the total weight of the curing agent, the content of the chlorine-based curing agent may be less than 20 weight %, less than 10 weight %, less than 5 weight %, less than 1 weight %, less than 0.5 weight %, or less than 0.3 weight %, and more than 0 weight %, more than 0.1 weight %, or more than 0.5 weight %, as specific embodiments, 0 weight % to 20 weight %, 0 weight % to 1 weight %, 0 weight % to 0.5 weight %, or 0.5 weight % to 20 weight %.

[0112] The curing agent may be at least one selected from a solid-phase curing agent and a liquid-phase curing agent.

[0113] The solid phase curing agent may contain an active hydrogen group. The solid phase curing agent may contain an amino group (-NH2) as an active hydrogen group.

[0114] In addition, the solid phase curing agent may be an ester compound containing two or more benzene rings. Specifically, the solid phase curing agent may include two or more ester groups in a molecule.

[0115] The solid phase curing agent may have a weight average molecular weight of 150 to 400, such as 150 to 350, such as 200 to 350, such as 250 to 350, such as 300 to 350. The solid phase curing agent may have a melting point (mp) of 100°C to 150°C, such as 100°C to 140°C, such as 110°C to 130°C.

[0116] In one embodiment, the solid phase curing agent includes at least one selected from the group consisting of bis(4-aminobenzoic acid)-1,3-propylidene ester (PDPAB), 4-aminobenzoic acid-4-(4-aminobenzoyl)oxyphenyl ester, 4-aminobenzoic acid-4-(4-aminobenzoyl)oxybutyl ester, 4-aminobenzoic acid-4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl ester, and bis(methylaminobenzoic acid)methylene ester (MBNA).

[0117] The liquid phase curing agent may contain an active hydrogen group. The liquid phase curing agent may include at least one selected from the group consisting of an amino group (-NH2), a hydroxyl group (-OH), a carboxylic acid group (-COOH), an epoxy group, and a combination thereof as an active hydrogen group. Specifically, it may contain an amino group (-NH2).

[0118] In addition, the liquid phase curing agent may contain sulfur in the molecule. Specifically, the liquid phase curing agent may contain two or more sulfur elements in the molecule.

[0119] The liquid curing agent may have a weight average molecular weight of 50 to 300, such as 100 to 250, such as 150 to 250, such as 200 to 250.

[0120] In addition, the liquid phase curing agent may be in a liquid state at room temperature. Alternatively, the liquid phase curing agent may have a boiling point (bp) of 160°C to 240°C, specifically 170°C to 240°C, and more specifically 170°C to 220°C.

[0121] Examples of the liquid-phase curing agent include at least one selected from the group consisting of 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), 2,6-bis(methylthio)-4-methyl-1,3-phenylenediamine, and N,N′-bis(sec-butylamino)diphenylmethane.

[0122] In addition, the curing agent may also include other curing agents in addition to the liquid phase curing agent and the solid phase curing agent. The additional curing agent may be, for example, at least one of an amine compound and an alcohol compound. Specifically, the additional curing agent may include at least one compound selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols.

[0123] For example, the additional curing agent may be at least one selected from the group consisting of diaminodiphenylmethane, diaminodiphenyl sulfone, meta-xylylenediamine, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine, polypropylenetriamine, ethylene glycol, diethylene glycol, dipropylene glycol, butanediol, hexanediol, glycerol, and trimethylolpropane.

[0124] As a specific example, the curing agent may include at least one selected from the group consisting of diethyltoluenediamine (DETDA), 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), bis(4-aminobenzoic acid)-1,3-propylidene ester (PDPAB), N,N′-bis(sec-butylamino)diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-phenylenediamine, 4-aminobenzoic acid-4-(4-aminobenzoyl)oxyphenyl ester, 4-aminobenzoic acid-4-(4-aminobenzoyl)oxybutyl ester, 4-aminobenzoic acid-4-[4-(4-aminobenzoyl)oxy-3-methylbutyloxy]butyl ester, and bis(methylaminobenzoic acid) methylene ester (MBNA).

[0125] The content of the curing agent may be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more, and 50 parts by weight or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, or 25 parts by weight or less, relative to 100 parts by weight of the urethane-based prepolymer. The content of the curing agent may be 10 to 40 parts by weight, more specifically 15 to 35 parts by weight or 15 to 25 parts by weight, relative to 100 parts by weight of the urethane-based prepolymer.

[0126] additive

[0127] The composition for preparing the polishing layer may also include other additives, such as surfactants and reaction rate controllers. The names of "surfactant", "reaction rate controller" and the like are arbitrary names based on the main function of the substance. Each substance does not necessarily perform only the function defined by the name.

[0128] The surfactant is not particularly limited as long as it functions to prevent pores from merging and overlapping each other. For example, the surfactant may include a silicon-based surfactant.

[0129] The surfactant may be used in an amount of 0.2 to 2 parts by weight relative to 100 parts by weight of the urethane-based prepolymer. Specifically, the surfactant may be used in an amount of 0.2 to 1.9 parts by weight, such as 0.2 to 1.8 parts by weight, such as 0.2 to 1.7 parts by weight, such as 0.2 to 1.6 parts by weight, such as 0.2 to 1.5 parts by weight, such as 0.5 to 1.5 parts by weight, relative to 100 parts by weight of the urethane-based prepolymer. If the amount of the surfactant is within the above range, the pores generated by the gas-phase foaming agent can be stably formed and maintained in the mold.

[0130] The function of the reaction rate controller is to promote or inhibit the reaction. A reaction accelerator, a reaction inhibitor, or both can be used as needed. The reaction rate controller may include a reaction accelerator. For example, the reaction rate controller may be at least one reaction accelerator selected from the group consisting of a triamine compound and an organometallic compound.

[0131] Specifically, the reaction rate controller may include a compound selected from the group consisting of triethylenediamine, dimethylethanolamine, tetramethylbutylenediamine, 2-methyltriethylenediamine, dimethylcyclohexylamine, triethylamine, triisopropanolamine, 1,4-diazabicyclo[2.2.2]octane, bis(2-methylaminoethyl)ether, trimethylaminoethylethanolamine, N,N,N,N,N″-pentamethyldiethylenetriamine, dimethylaminoethylamine, dimethylaminopropylamine, benzyldimethylamine, N-ethylmorpholine, At least one of the group consisting of N,N-dimethylaminoethylmorpholine, N,N-dimethylcyclohexylamine, 2-methyl-2-azanorbornane, dibutyltin dilaurate, stannous isooctanoate, dibutyltin diacetate, dioctyltin diacetate, dibutyltin maleate, di(2-ethylhexanoate)dibutyltin, and dibutyltin dithiol. Specifically, the reaction rate controller may include at least one selected from the group consisting of benzyldimethylamine, N,N-dimethylcyclohexylamine, and triethylamine.

[0132] The reaction rate controller may be used in an amount of 0.05 to 2 parts by weight relative to 100 parts by weight of the urethane-based prepolymer. Specifically, the reaction rate controller may be used in an amount of 0.05 to 1.8 parts by weight, such as 0.05 to 1.7 parts by weight, such as 0.05 to 1.6 parts by weight, such as 0.1 to 1.5 parts by weight, such as 0.1 to 0.3 parts by weight, such as 0.2 to 1.8 parts by weight, such as 0.2 to 1.7 parts by weight, such as 0.2 to 1.6 parts by weight, such as 0.2 to 1.5 parts by weight, such as 0.5 to 1 part by weight. If the amount of the reaction rate controller is within the above range, the curing reaction rate of the prepolymer composition can be appropriately controlled, thereby forming a polishing layer having a desired pore size and hardness.

[0133] Additional component layers

[0134] The support layer constitutes a base pad and is used to support the polishing layer and absorb and disperse the impact applied to the polishing layer. Therefore, in the polishing process using the polishing pad, it can minimize damage and defects to the polishing object.

[0135] The support layer may be composed of non-woven fabric or suede, but is not limited thereto.

[0136] In one embodiment, the support layer may be a resin-impregnated nonwoven fabric. The nonwoven fabric may be a fiber nonwoven fabric including one selected from the group consisting of polyester fiber, polyamide fiber, polypropylene fiber, polyethylene fiber, and a combination thereof.

[0137] The resin impregnated in the nonwoven fabric may include polyurethane resin, polybutadiene resin, styrene-butadiene copolymer resin, styrene-butadiene-styrene copolymer resin, acrylonitrile-butadiene copolymer resin, styrene-ethylene-butadiene-styrene copolymer resin, silicone rubber resin, polyester-based elastomer resin, polyamide-based elastomer resin, and combinations thereof.

[0138] The support layer may have a thickness of, for example, 0.3 mm or more or 0.5 mm or more and 3 mm or less, 2 mm or less, or 1 mm or less. As a specific embodiment, the support layer may have a thickness of 0.3 mm to 3 mm or 0.5 mm to 1 mm.

[0139] The support layer may have a hardness of, for example, 50 Asker C or more, 60 Asker C or more, or 70 Asker C or more, and 100 Asker C or less, 90 Asker C or less, or 80 Asker C or less. As a specific embodiment, the hardness of the support layer may be 50 Asker C to 100 Asker C or 60 Asker C to 90 Asker C.

[0140] In addition, an adhesive layer may be interposed between the polishing layer (top pad) and the support layer (bottom pad).

[0141] 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 resin, polyester resin, ethylene-vinyl acetate resin, polyamide resin, and polyolefin resin. Specifically, the hot melt adhesive may be at least one selected from the group consisting of polyurethane resin and polyester resin.

[0142] In addition, a double-sided tape may be laminated under the support layer. When it is applied to a CMP device, after removing the release paper of the double-sided tape, it can be attached to a polishing pad for use.

[0143] Method for preparing polishing pad

[0144] According to one embodiment, a method for preparing a polishing pad includes preparing a polishing layer composition including a urethane-based prepolymer, a foaming agent, and a curing agent; injecting the polishing layer composition into a mold and curing to prepare a polishing layer; and laminating the polishing layer and a support layer.

[0145] The specific types and contents of the urethane-based prepolymer, curing agent, and blowing agent are as described above.

[0146] The polishing layer composition may be prepared by sequentially or simultaneously mixing a urethane-based prepolymer, a blowing agent, and a curing agent.

[0147] As an example, the step of preparing the polishing pad composition may be performed by mixing a urethane-based prepolymer with a curing agent and then further mixing with a blowing agent, or by mixing a urethane-based prepolymer with a blowing agent and then further mixing with a curing agent.

[0148] As another example, the urethane-based prepolymer, curing agent, and blowing agent can be put into the mixing process substantially at the same time. If blowing agent, surfactant, and inert gas are further added, they can be put into the mixing process substantially at the same time.

[0149] As another example, the urethane-based prepolymer, blowing agent, and surfactant may be premixed, and the curing agent, or the curing agent with an inert gas, may be added later.

[0150] The mixing initiates the reaction of the urethane-based prepolymer and the curing agent, and allows the blowing agent and the inert gas to be uniformly dispersed in the raw material. In this case, the reaction rate controller may intervene in the reaction at the beginning of the reaction of the urethane-based prepolymer and the curing agent, thereby controlling the reaction rate. Specifically, the mixing may be performed at a speed of 1,000 to 10,000 rpm or 4,000 to 7,000 rpm. Within the above speed range, it may be more conducive to the uniform dispersion of the inert gas and the blowing agent in the raw material.

[0151] In addition, the step of preparing the polishing layer composition may be performed at 50° C. to 150° C. If necessary, it may be performed under vacuum degassing conditions.

[0152] If the foaming agent includes a solid-phase foaming agent, the step of preparing the polishing layer composition may include mixing a urethane-based prepolymer and a solid-phase foaming agent to prepare a first pre-composition; and mixing the first pre-composition and a curing agent to prepare a second pre-composition.

[0153] The first precomposition may have a viscosity at about 80° C. of about 1,000 cps to about 2,000 cps, such as about 1,000 cps to about 1,800 cps, such as about 1,000 cps to about 1,600 cps, such as about 1,000 cps to about 1,500 cps.

[0154] If the foaming agent includes a gas-phase foaming agent, the step of preparing the polishing layer composition may include preparing a third pre-composition including a urethane-based prepolymer and a curing agent; and adding the gas-phase foaming agent to the third pre-composition to prepare a fourth pre-composition. In one embodiment, the third pre-composition may further include a solid-phase foaming agent.

[0155] In one embodiment, the step of preparing the polishing layer includes preparing a mold preheated to a first temperature; injecting the polishing layer composition into the preheated mold and curing it; and post-curing the cured polishing layer composition at a second temperature higher than the preheating temperature.

[0156] In one embodiment, the temperature difference between the first temperature and the second temperature may be about 10° C. to about 40° C., such as about 10° C. to about 35° C., such as about 15° C. to about 35° C. In one embodiment, the first temperature may be about 60° C. to about 100° C., such as about 65° C. to about 95° C., such as about 70° C. to about 90° C. In one embodiment, the second temperature may be about 100° C. to about 130° C., such as about 100° C. to about 125° C., such as about 100° C. to about 120° C.

[0157] Curing the polishing layer composition at the first temperature can be performed for about 5 minutes to about 60 minutes, such as about 5 minutes to about 40 minutes, such as about 5 minutes to about 30 minutes, such as about 5 minutes to about 25 minutes.

[0158] The step of post-curing the polishing pad composition cured at the first temperature at the second temperature can be performed for about 5 hours to about 30 hours, such as about 5 hours to about 25 hours, such as about 10 hours to about 30 hours, such as about 10 hours to about 25 hours, such as about 12 hours to about 24 hours, such as about 15 hours to about 24 hours.

[0159] Subsequently, the step of injecting the polishing layer composition into the mold and curing it may be performed at a temperature of 60° C. to 120° C. and a temperature of 50 kg / m 2 Up to 200kg / m 2 under pressure conditions.

[0160] In addition, the above preparation method may further include the steps of cutting the surface of the obtained polishing layer, machining grooves on the surface, bonding it to the lower part, inspecting, and packaging. These steps can be carried out according to the conventional method of preparing the polishing pad.

[0161] As an embodiment, the method for preparing a polishing pad may further include processing at least one side of the polishing layer. The step of processing at least one side of the polishing layer may include forming a groove on at least one side of the polishing layer; lathing at least one side of the polishing layer; and roughening at least one side of the polishing layer.

[0162] The grooves may include at least one of concentric circular grooves spaced at a certain interval from the center of the polishing layer; and radial grooves continuously connected from the center of the polishing layer to the edge of the polishing layer. Lathe turning may be performed by cutting the polishing layer to a certain thickness using a cutting tool. Roughening may be performed by machining the surface of the polishing layer using a grinding wheel.

[0163] Pyrolysis oil

[0164] Furthermore, the present invention also provides pyrolysis oil obtained from the polishing layer of the polishing pad.

[0165] According to one embodiment, the pyrolysis oil is obtained from the polishing layer of the above-mentioned polishing pad.

[0166] When the pyrolysis oil is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2 standard, the chlorine content may be less than 10,000 ppm, for example, 5,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 200 ppm or less, 100 ppm or less, 80 ppm or less, or 50 ppm or less. When the content of the residual chlorine component in the pyrolysis oil obtained by pyrolysis of the polishing layer of the polishing pad is within the above preferred range, environmental problems caused by the chlorine component can be effectively reduced.

[0167] In addition, according to one embodiment, the lower limit of the range of the chlorine content in the pyrolysis oil obtained from the polishing layer of the polishing pad may be, for example, 0 ppm or more, greater than 0 ppm, 1 ppm or more, 2 ppm or more, 3 ppm or more, 4 ppm or more, or 5 ppm or more. Since the content of the residual chlorine component in the pyrolysis oil is within the above range, the pyrolysis oil can be converted into high-quality energy.

[0168] Otherwise, the composition and properties of the pyrolysis oil are the same as those exemplified in the description of the polishing pad.

[0169] The temperature for pyrolyzing the polishing layer to obtain pyrolysis oil may be, for example, 280° C. to 350° C., 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. In addition, the time for pyrolyzing the polishing layer to obtain pyrolysis oil may be, for example, 1 hour to 10 hours, specifically, 2 hours to 9 hours, 3 hours to 9 hours, 4 hours to 8 hours, 5 hours to 7 hours, 5 hours to 6 hours, or 6 hours to 7 hours. As a specific example, pyrolysis oil can be obtained by pyrolyzing the polishing layer at 280° C. to 350° C. for 3 hours to 9 hours.

[0170] Meanwhile, when the pyrolysis of the polishing layer is completed, residual solids are left behind, which can be used as a solid fuel.

[0171] The pyrolysis oil is obtained from the polishing layer of the above-mentioned polishing pad. In this case, the polishing pad may be a waste polishing pad that has been used in the CMP process. Therefore, the embodiment can improve the problem that the waste polishing pad is difficult to recycle traditionally. In addition, it can help provide renewable energy and reduce environmental problems.

[0172] Pyrolysis oil is obtained by pyrolysis of the polishing layer of the polishing pad. Figure 2 The process of obtaining pyrolysis oil by pyrolysis of the polishing pad is shown. Figure 2 As shown, the process for preparing pyrolysis oil includes loading a polishing layer (10) of a polishing pad into a chamber (100) (step S-1); pyrolyzing the polishing layer (10) loaded into the chamber (100) at a temperature of 280° C. to 350° C. (step S-2); and passing a vaporized flow formed by pyrolysis through a heat exchanger (200) to obtain liquid pyrolysis oil (step S-3).

[0173] Step S-1 can be performed by loading the polishing layer, in particular, the polishing layer of the discarded polishing pad, into the chamber. That is, the polishing layer of the discarded polishing pad that has been used in the CMP process can be loaded into the chamber. Here, when the discarded polishing pad includes a support layer and an adhesive layer (wherein the polishing layer, the adhesive layer and the buffer layer are combined) in addition to the polishing layer, the layers are separated and only the polishing layer can be loaded into the chamber. In addition, one or more polishing layers, specifically, 1 to 5 or 2 to 3 polishing layers, can be loaded into the chamber. Therefore, the embodiment can easily recycle (process) the discarded polishing pad.

[0174] The chamber is mounted on a reactor capable of performing pyrolysis of the polishing layer, and it can be made of a heat-resistant material. It can have a structure that is separated from the reactor after the pyrolysis is completed.

[0175] Step S-2 can be performed by pyrolyzing the polishing layer loaded into the chamber at a temperature of 280° C. to 350° C. Specifically, the pyrolysis temperature of the polishing layer can 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. Since the polishing layer is pyrolyzed within the above temperature range, a high yield of pyrolysis oil can be obtained, and harmful substances such as diisocyanate can be minimized during the pyrolysis process. In addition, the pyrolysis oil can be controlled to contain a desired level of chlorine.

[0176] Meanwhile, the pyrolysis of the polishing layer may be carried out in the presence of a catalyst. The catalyst is not particularly limited as long as it is a catalyst commonly used in the pyrolysis of polymers. Specifically, it may include zeolite or potassium hydroxide. When pyrolysis is carried out in the presence of a catalyst, the yield of pyrolysis oil can be increased while suppressing the generation of byproducts such as tar.

[0177] When step S-2 is performed, the pyrolysis oil may be vaporized and converted into a vaporized stream.

[0178] Step S-3 can be performed by passing the vaporized stream formed by pyrolysis through a heat exchanger to obtain liquid pyrolysis oil. Specifically, the vaporized stream can be cooled by a heat exchanger to be converted into liquid pyrolysis oil. The heat exchanger is not particularly limited as long as it is made of commonly used structures and materials.

[0179] Meanwhile, when step S-3 is completed, the solids remaining in the chamber can be used as solid fuel through a separate recovery process. In addition, the pyrolysis oil obtained through step S-3 can be subjected to a refining process such as distillation.

[0180] As the content of residual chlorine components in pyrolysis oil is adjusted to a specific range, it can be converted into high-quality energy.

[0181] Figure 3 The process of obtaining energy and basic raw materials from pyrolysis oil is shown. Figure 3 As shown, the pyrolysis oil obtained by pyrolysis of the polishing layer can be converted into heavy oil, naphtha, etc. through a refining process such as in a distillation tower (300). In this case, the heavy oil can be used as an energy source, such as heating oil and power plant fuel. In addition, naphtha can be converted into basic petrochemical raw materials such as benzene, toluene, xylene, butanediol, etc. through a cracking process and used in industry.

[0182] Example

[0183] Although the following embodiments are provided, the scope of implementation is not limited thereto.

[0184] Example 1

[0185] Step (1) Preparation of urethane-based prepolymer

[0186] 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), dicyclohexylmethane diisocyanate (H12MDI), polytetramethylene ether glycol (PTMEG), and diethylene glycol (DEG) were added to a four-necked flask and then reacted at 80° C. for 3 hours to prepare a urethane-based prepolymer having 10 wt % of NCO terminal groups (NCO%<1).

[0187] Step (2) Preparation of polishing layer

[0188] A casting machine is provided with a storage tank and a feed pipe containing raw materials such as a prepolymer, a curing agent, an inert gas, and a foaming agent. The above-prepared urethane-based prepolymer, a curing agent (DMTDA, Covestro), a solid-phase foaming agent (F-65DE, Matsumoto), an inert gas (N2), and a silicon-based surfactant (Evonik) are respectively charged into the storage tank. Specifically, 32 parts by weight of the curing agent, 1 part by weight of the solid-phase foaming agent, and 1 part by weight of the surfactant are added to 100 parts by weight of the prepolymer, and the inert gas is fed at a rate of 1.5 L / min.

[0189] The raw materials were stirred while being fed into the mixing head at a constant rate through their respective feed pipes. The rotation speed of the mixing head was about 5,000 rpm. Then, the raw material mixture mixed in the mixing head was injected into a mold having a width of 1,000 mm, a length of 1,000 mm, and a height of 3 mm. The temperature of the mold was adjusted to about 80 (± 5) ° C. The mixture was cured in the mold and cast into a plate. The plate was post-cured at about 110 (± 5) ° C for about 18 hours to prepare a polishing layer.

[0190] Step (3) Preparation of polishing pad

[0191] One side of the polishing layer was turned using a cutting tool and grooved using a tool head to obtain an average thickness of 2 mm. The buffer layer was prepared by impregnating a polyester fiber nonwoven fabric with a polyurethane resin. Heat sealant was applied to one side of the buffer layer and the side of the polishing layer opposite to the polishing surface. The buffer layer and the polishing layer were laminated with the sides coated with heat sealant in contact with each other, and then heated at a temperature of about 140 (± 5) ° C and 2 kgf / cm 2 The polishing pad was prepared by pressing with a press roller under a pressure of .

[0192] Example 2

[0193] The same process as in Example 1 was repeated, and a casting machine with a storage tank and a feed pipe containing raw materials such as a prepolymer, a curing agent, an inert gas, and a foaming agent was provided for step (2). The above-prepared urethane-based prepolymer, a curing agent (DMTDA, Covestro), a solid-phase foaming agent (051DET40d25, Nouryon), an inert gas (N2), and a silicon-based surfactant (Evonik) were respectively charged into the storage tank. The subsequent procedures were carried out in the same manner as in Example 1 to prepare a polishing pad.

[0194] Example 3

[0195] The same process as in Example 1 was repeated, and a casting machine with a storage tank and a feed pipe containing raw materials such as a prepolymer, a curing agent, an inert gas, and a foaming agent was provided for step (2). The above-prepared urethane-based prepolymer, a curing agent (DMTDA, Covestro), a solid-phase foaming agent (F-80DE, Matsumoto), an inert gas (N2), and a silicon-based surfactant (Evonik) were respectively charged into the storage tank. The subsequent procedures were carried out in the same manner as in Example 1 to prepare a polishing pad.

[0196] Comparative Example 1

[0197] The same process as in Example 1 was repeated, and a casting machine with a storage tank and a feed pipe containing raw materials such as a prepolymer, a curing agent, an inert gas, and a foaming agent was provided for step (2). The above-prepared urethane-based prepolymer, a curing agent (MOCA, Ishihara), a solid-phase foaming agent (051DET40d25, Nouryon), an inert gas (N2), and a silicon-based surfactant (Evonik) were respectively charged into the storage tank. The subsequent procedures were carried out in the same manner as in Example 1 to prepare a polishing pad.

[0198] Comparative Example 2

[0199] The same process as in Example 1 was repeated, and a casting machine with a storage tank and a feed pipe containing raw materials such as a prepolymer, a curing agent, an inert gas, and a foaming agent was provided for step (2). The above-prepared urethane-based prepolymer, a curing agent (MOCA, Ishihara), a solid-phase foaming agent (461DET40d25, Nouryon), an inert gas (N2), and a silicon-based surfactant (Evonik) were respectively charged into the storage tank. The subsequent procedures were carried out in the same manner as in Example 1 to prepare a polishing pad.

[0200] Test Example 1

[0201] The following tests were performed on the polishing layer, support layer, and polishing pad laminated therefrom prepared as described above.

[0202] (1) Hardness

[0203] Each sample was cut into 5 cm×5 cm (thickness: 2 mm) and stored at room temperature and 30° C., 50° C., and 70° C. for 12 hours, and the Shore D hardness and Asker C hardness were measured using a hardness tester.

[0204] (2) Specific gravity

[0205] Each sample was cut into 2 cm×5 cm (thickness: 2 mm) and stored at a temperature of 25° C. for 12 hours, and the specific gravity was measured using a hydrometer.

[0206] (3) Tensile strength

[0207] Each sample was cut into 4 cm×1 cm (thickness: 2 mm). The samples were tested using a universal testing machine (UTM) at a rate of 50 mm / min to measure the ultimate strength before fracture.

[0208] (4) Elongation

[0209] Each sample was cut into 4 cm×1 cm (thickness: 2 mm). The sample was tested using UTM at a rate of 50 mm / min, and the maximum deformation before fracture was measured. The ratio of the maximum deformation to the initial length was expressed as a percentage (%).

[0210] The results are shown in the following table.

[0211]

Table 1

[0212]

[0213] As shown in the above table, the polishing pads of Examples 1 to 3 are at least comparable to the polishing pads of Comparative Examples 1 and 2 in terms of hardness, specific gravity, tensile strength, and elongation.

[0214] Test Example 2 Component Analysis

[0215] The polishing layer of the polishing pad prepared in each of Examples and Comparative Examples and the pyrolysis oil obtained therefrom were analyzed as follows.

[0216] (1) Chlorine content (polishing pad)

[0217] A circular sample having a diameter of 3 cm and a height of 0.3 cm was prepared from the polishing layer of the polishing pad. The chlorine content of each polishing layer was measured by IEC 62321-3-2, which is an international standard for measuring the content of specific substances by combustion ion chromatography (C-IC).

[0218] (2) Chlorine content (pyrolysis oil)

[0219] The polishing layer of each polishing pad is separated and loaded into a reaction chamber, followed by pyrolysis at 320°C for 6 hours. The vaporized stream formed by pyrolysis passes through a heat exchanger to obtain liquid pyrolysis oil. Subsequently, when the liquid pyrolysis oil stream disappears, the production of pyrolysis oil is completed by a cooling process. The pyrolysis oil thus prepared is loaded into a sample container. The chlorine content in the pyrolysis oil is measured by IEC62321-3-2, which is an international standard for measuring the content of specific substances by combustion ion chromatography (C-IC).

[0220] (3) Elemental analysis

[0221] The elements in the pyrolysis oil obtained in the polishing layer were analyzed in the same manner as in the above section (2). The element contents of C, H, N, S, and O, excluding halogens (F, Cl), were analyzed by combustion at 1,800° C. using a FLASH2000CHNS / O analyzer (element analyzer, Thermo Fisher Scientific). The sulfur (S) element content in the generated gas was quantitatively analyzed by a GC column.

[0222] (4) Inorganic content: ICP-OES

[0223] In the same manner as in the above-mentioned section (2), the inorganic content in the pyrolysis oil obtained in the polishing layer was measured. A sample of the pyrolysis oil was placed in an ICP-OES (5110SVDV, Agilent) and converted into an atomic or ionic excited state by an argon plasma. In this case, the intensity of light emitted when the electrons of the atoms or ions return to the ground state or low energy state was measured. Subsequently, the inorganic substances (Al, Si, and Fe) in the pyrolysis oil were quantitatively analyzed according to the calibration curve.

[0224]

Table 2

[0225]

[0226] As can be seen from the above table, the chlorine (Cl) content of the polishing layer of the polishing pad in Examples 1 to 3 and the chlorine content of the pyrolysis oil obtained therefrom are all measured within the ideal range. In addition, the contents of sulfur (S), aluminum (Al), iron (Fe), and silicon (Si) in the pyrolysis oil obtained from the polishing layer of the polishing pad in Examples 1 to 3 are all measured within the ideal range.

[0227] Test Example 3: Evaluation of CMP Process

[0228] The polishing pads prepared above were each subjected to the following tests.

[0229] (1) Polishing rate (removal rate)

[0230] In a CMP polisher, a silicon wafer with a diameter of 300 mm on which silicon oxide was deposited by a CVD process was placed on a porous polyurethane polishing pad mounted on a polishing disk, with the silicon oxide layer of the silicon wafer facing downward. Then, the silicon oxide layer was polished under a polishing load of 4.0 psi, while the polishing pad was rotated at a speed of 150 rpm, calcined cerium dioxide slurry was supplied to the polishing pad at a rate of 250 ml / min, and the polishing disk was rotated at a speed of 150 rpm for 60 seconds. After polishing, the silicon wafer was removed from the carrier, installed in a centrifugal dryer, cleaned with deionized water (DIW), and then blown dry with nitrogen for 15 seconds. The film thickness of the dried silicon wafer was measured before and after polishing using a spectroscopic reflectometer thickness gauge (manufacturer: Keyence, model: SI-F80R).

[0231] Then, the polishing rate was calculated using the following Equation 1.

[0232] [Equation 1]

[0233] (2) Defects

[0234] Polishing was performed using a CMP polisher in the same manner as the polishing rate test. After polishing, the silicon wafer was transferred to a cleaning device and cleaned for 10 seconds with 1% HF, deionized water (DIW), and 1% H2NO3, respectively. Subsequently, it was transferred to a centrifugal dryer, cleaned with deionized water (DIW), and then blown dry with nitrogen for 15 seconds. A defect measurement device (manufacturer: Tenkor, model: XP+) was used to measure the defect changes of the dried silicon wafer before and after polishing. Specifically, the total number of scratches, vibration marks, pits, and residues on the wafer surface was measured.

[0235] (3) Crumb size (D50 particle size)

[0236] (a) Obtaining an aqueous solution of the debris

[0237] The porous polyurethane polishing pad is attached to the polishing disc of the CMP polisher. Subsequently, without using a carrier, only trimmer and deionized water (DIW) are used to collect the debris of the polishing layer. The finishing of the polishing layer is carried out with a CI45 dish (pad cutting rate 80 to 90, Saesol), while the polishing disc speed is 93rpm, the trimmer load is 9lbs, the rotation speed is 64rpm, and the scanning speed is 19 times per minute, and deionized water is supplied with 300cc / min. The polishing layer debris formed after trimming 10 minutes is collected in the form of a solution mixed with deionized water, thereby obtaining 300mL of the debris aqueous solution.

[0238] (b) pH adjustment and debris particle size analysis

[0239] The chip aqueous solution had a pH value at a level of 6.0 to 6.5, and the pH value was adjusted to 5.5 using a nitric acid aqueous solution. Here, the concentration of the nitric acid aqueous solution used was 35%. The D50 particle size of the chip in the chip aqueous solution was measured using a particle size analyzer (Mastersize 3000, Malvern) and a medium-sized automatic disperser (Hydro MV, Malvern). The analyzer was set to use 1.55 of polyurethane as the refractive index of the material to be analyzed, 1.33 of deionized water as the refractive index of the dispersant, and a stirring speed of 2,500 rpm.

[0240] The results are shown in the following table.

[0241]

Table 3

[0242]

[0243] As can be seen from the above table, the polishing pads of Examples 1 to 3 are equal to or greater than Comparative Examples 1 and 2 in terms of polishing rate and other properties. In particular, the chip size measurement results generated by the polishing pads of Examples 1 to 3 are smaller than those of Comparative Examples 1 and 2, and the number of defects and scratches in Examples 1 to 3 is significantly lower than that of Comparative Examples 1 and 2.

Claims

1. A polishing pad comprising a polishing layer, wherein when pyrolysis oil obtained by pyrolysis of the polishing layer at 320° C. for 6 hours is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2 standard, the chlorine (Cl) content is less than 10,000 ppm.

2. The polishing pad according to claim 1, wherein When the pyrolysis oil was analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2 standard, the chlorine (Cl) content was 1 ppm to 100 ppm.

3. The polishing pad according to claim 1, wherein When the pyrolysis oil was analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES), the total content of metal components was 1 ppm to 3,000 ppm.

4. The polishing pad according to claim 1, wherein When the pyrolysis oil was analyzed using an element analyzer, the sulfur (S) content was 1 ppm to 100 ppm.

5. The polishing pad according to claim 1, wherein When the pyrolysis oil is analyzed according to the ASTM D2887 standard, the initial boiling point is 10°C to 50°C, and the final boiling point is 400°C to 500°C.

6. The polishing pad of claim 1 , wherein the polishing layer comprises a polyurethane resin formed from a composition comprising a urethane-based prepolymer, a blowing agent, and a curing agent, and the urethane-based prepolymer has an isocyanate terminal group content (NCO%) of 7.5 wt % to 12 wt %.

7. The polishing pad according to claim 6, wherein the foaming agent comprises a solid-phase foaming agent, the solid-phase foaming agent comprises at least one selected from the group consisting of acrylonitrile-based copolymers, methyl methacrylate-based copolymers, methacrylonitrile-based copolymers, and acrylic acid-based copolymers, and the curing agent comprises a curing agent selected from the group consisting of diethyltoluenediamine (DETDA), 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), bis(4-aminobenzoic acid)-1,3-propylidene ester (PDP AB), N,N′-bis(sec-butylamino)diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-phenylenediamine, 4-aminobenzoic acid-4-(4-aminobenzoyl)oxyphenyl ester, 4-aminobenzoic acid-4-(4-aminobenzoyl)oxybutyl ester, 4-aminobenzoic acid-4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl ester, and bis(methylaminobenzoic acid) methylene ester (MBNA).

8. The polishing pad according to claim 1, wherein the polishing layer has a hardness of 50 Shore D to 65 Shore D, a strength of 15 N / mm 2 Up to 25N / mm 2 Tensile strength, and elongation of 90% to 130%.

9. The polishing pad according to claim 1, wherein: When the polishing pad is used to polish the oxide silicon layer of a silicon wafer with a ceria slurry, the polishing rate determined according to the following equation is: to 10. A pyrolysis oil obtained from the polishing pad of claim 1, wherein when the pyrolysis oil is analyzed by combustion ion chromatography (C-IC) according to IEC 62321-3-2 standard, the chlorine (Cl) content is less than 10,000 ppm.

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