Polishing pad and process for preparing the same and process for preparing semiconductor device semiconductor device

Abstract

According to one embodiment, a polishing pad includes a top pad that contacts a wafer to perform polishing, and a bottom pad located on one side of the top pad. In the polishing rate profile of a CMP process for a silicon oxide layer, the polishing rate at a distance of 95 mm from the wafer center is greater than the polishing rate at a distance of 85 mm from the wafer center. As a result, the polishing rate and polishing flatness can be improved; in particular, the polishing rate profile characteristics at the edge of the polishing pad are excellent.

Description

Technical Field

[0001] The embodiments relate to a polishing pad for use in a chemical mechanical planarization (CMP) process of a semiconductor device. Specifically, they relate to a polishing pad and a method for preparing the same. Prior Technology

[0002] Chemical mechanical planarization (CMP) in semiconductor fabrication refers to the following steps: fixing a semiconductor substrate (such as a wafer) to a head and contacting it with the surface of a polishing pad mounted on a platform, wherein the platform and the head move relative to each other to planarize irregularities on the surface of the semiconductor substrate.

[0003] In this CMP process, the polishing pad needs to have stable physical properties, as these significantly affect the surface finish of the semiconductor substrate. In particular, since the polishing rate of the CMP process can vary sensitively depending on the composition and physical properties of the polishing pad, it is necessary to optimize the composition and physical properties of the polishing pad.

[0004] Meanwhile, a polishing pad can consist of a top pad and a sub-pad. The top pad contacts a wafer for polishing, while the sub-pad is located below the top pad to support it. The sub-pad can be used to absorb and disperse impacts applied to the top pad, or to improve properties such as polishing rate; however, there are limitations to improving properties such as polishing speed through a sub-pad. Accordingly, research is ongoing to further improve properties such as polishing rate of the polishing pad through a sub-pad. [Previous Technical Documents] (Patent Document 1) Korean Early Publication Patent Publication No. 2018-0044771 Summary of the Invention

[0005] [Technical Issues] Accordingly, one embodiment aims to provide a polishing pad and a method for preparing the same, the polishing pad comprising a specific sub-pad under a top pad, thereby improving the polishing rate and polishing flatness without degrading the physical properties of the top pad. [Solution to the Problem]

[0006] A polishing pad according to one embodiment includes a top pad and a sub-pad, the top pad being in contact with a wafer to perform polishing, and the sub-pad being located on one side of the top pad, wherein the following relationship 1 is satisfied. [Relationship 1] RR85 < RR95

[0007] In Equation 1, RR85 is the polishing rate (Å / min) at a distance of 85 mm from the wafer center in the CMP process for silicon oxide layers; while RR95 is the polishing rate (Å / min) at a distance of 95 mm from the wafer center in the CMP process for silicon oxide layers.

[0008] A method for preparing a polishing pad according to another embodiment includes: (1) preparing a top pad using a top pad composition comprising a urethane prepolymer, a foaming agent, and a curing agent; (2) preparing a sub-pad comprising a nonwoven layer and a suede layer; and (3) combining the top pad and the sub-pad to prepare a polishing pad, wherein the polishing pad satisfies the above-described relation 1.

[0009] A method for fabricating a semiconductor device according to another embodiment includes using a polishing pad to polish the surface of a semiconductor substrate. [Advantages of this invention]

[0010] According to one embodiment, a polishing pad includes a top pad that contacts a wafer to perform polishing, and a bottom pad located on one side of the top pad. In the polishing rate distribution of a CMP process for a silicon oxide layer, the polishing rate at a distance of 95 mm from the wafer center is greater than the polishing rate at a distance of 85 mm from the wafer center. As a result, the polishing rate and polishing flatness can be improved; in particular, the polishing rate distribution characteristics at the edge of the polishing pad are excellent.

[0011] More specifically, the pad has a dual structure comprising a non-woven fabric layer and a suede layer, and its physical properties, such as hardness, compressibility, density, and the like, are adjusted. As a result, in the polishing rate distribution of the CMP process, the slope between 85 mm and 95 mm from the wafer center satisfies a positive value, unlike conventional polishing pads which have negative slopes. Accordingly, the polishing rate of the pad can be improved; in particular, the polishing rate distribution characteristics at the edge of the pad are excellent, resulting in excellent polishing flatness.

[0012] Furthermore, since the polishing pad according to this embodiment can improve the polishing rate and polishing flatness without degrading the physical properties and processability of the polishing pad, it is possible to improve CMP performance and yield when using it to fabricate semiconductor devices. Simple Explanation of the Diagram

[0013] Figure 1 shows a scanning electron microscope (SEM) image of the cross-section of the secondary pad in Example 1.

[0014] Figure 2 shows a scanning electron microscope (SEM) image of the cross-section of the secondary pad in Comparative Example 1.

[0015] Figure 3 shows a scanning electron microscope (SEM) image of the cross-section of the secondary pad in Comparative Example 2.

[0016] Figure 4 shows the polishing rate distribution of the polishing pad in Example 1 during the CMP process.

[0017] Figure 5 shows the polishing rate distribution of the polishing pad in the CMP process of Comparative Example 1.

[0018] Figure 6 shows the polishing rate distribution of the polishing pad in the CMP process of Comparative Example 2.

[0019] Figure 7 shows the polishing rate distribution of the polishing pads in Example 1 and Comparative Examples 1 and 2 during the CMP process.

[0020] Figure 8 shows the slope between 85 mm and 95 mm from the wafer center in the polishing rate distribution of the polishing pads of Example 1 and Comparative Examples 1 and 2 during the CMP process.

[0021] Figure 9 schematically illustrates a method for fabricating a semiconductor device according to one embodiment. Implementation

[0022] [Best Mode for Implementing the Invention] The present invention will be described in detail below with reference to embodiments. The embodiments are not limited to those disclosed herein. These embodiments can be modified in various ways without altering the spirit of the invention.

[0023] In this specification, the terms used to refer to individual components are for the purpose of distinguishing them from each other and are not intended to limit the scope of the embodiments. Furthermore, in this specification, unless the context otherwise requires, the singular expressions should be construed as also encompassing the plural.

[0024] Unless otherwise specified, when a component is referred to as "comprising" an element in this specification, it should be understood that the component may also include other elements, rather than excluding other elements.

[0025] In this specification, when a component is described as being formed above / below another component or connected or coupled to each other, this covers situations where these components are formed, connected, or coupled directly or indirectly through another component. Furthermore, it should be understood that the criteria for determining whether a component is above or below may change depending on the orientation of the object being observed.

[0026] Unless otherwise specified, all numerical ranges of the physical properties, dimensions and similar components used herein shall be understood to be modified by the term “about”.

[0027] In limiting the numerical range of the size, physical properties and similar properties of the components described in this specification, when a numerical range limited only by an upper limit and a numerical range limited only by a lower limit are illustrated separately, it should be understood that a numerical range combining these upper and lower limits is also covered within the exemplary scope of this invention. [Polishing Pad]

[0028] A polishing pad according to one embodiment includes a top pad and a sub-pad, the top pad being in contact with a wafer to perform polishing, and the sub-pad being located on one side of the top pad, wherein the following relationship 1 is satisfied. [Relationship 1] RR85 < RR95

[0029] In Equation 1, RR85 is the polishing rate (Å / min) at a distance of 85 mm from the wafer center in the polishing rate distribution of the CMP process for silicon oxide layers; while RR95 is the polishing rate (Å / min) at a distance of 95 mm from the wafer center in the polishing rate distribution of the CMP process for silicon oxide layers.

[0030] Specifically, the top pads, typically made of polyurethane materials, are viscoelastic, which causes uneven pressure distribution during the CMP process, leading to pad deformation. In particular, springback occurs due to the strong pressure applied to prevent wafer detachment, which may degrade the polishing rate distribution characteristics at the edges during the CMP process.

[0031] In a polishing pad according to one embodiment, a secondary pad is provided on one side of the top pad, and the top pad contacts a wafer to perform polishing, thereby improving the polishing rate distribution characteristics in the CMP process, more specifically, the polishing rate distribution characteristics at the edges. The type and characteristics of the secondary pad are controlled, thereby allowing effective control of the viscoelastic properties of the top pad. Accordingly, in the polishing pad according to one embodiment, in the polishing rate distribution of a CMP process for a silicon oxide layer, the polishing rate at a distance of 95 mm from the wafer center is greater than the polishing rate at a distance of 85 mm from the wafer center. As a result, the polishing rate and polishing flatness can be improved; in particular, the polishing rate distribution characteristics at the edges of the polishing pad are excellent.

[0032] In a polishing pad according to one embodiment, the average slope between 85 mm and 95 mm from the wafer center is positive in the polishing rate distribution of the CMP process for the silicon oxide layer.

[0033] For example, in this polishing pad, in the polishing rate distribution of the CMP process for the silicon oxide layer, the average slope between distances of 85 mm and 95 mm from the wafer center can be 0.1 or more, 0.3 or more, 0.5 or more, 0.8 or more, 1.0 or more, 1.2 or more, 1.5 or more, 2 or more, 3 or more, 3.5 or more, 4 or more, 5.5 or more, 6 or more, 7 or more, 8 or more, 9.5 or more, 10.5 or more, 11 or more, 12 or more, 13.5 or more, or 15 or more, 1.5 to 15, 2 to 11.5, 3 to 10.5, 4.5 to 9, or 5 to 8.5. Since the average slope between distances of 85 mm and 95 mm from the wafer center in the polishing rate distribution of the CMP process for the silicon oxide layer meets the above range, the polishing rate and polishing flatness can be further improved.

[0034] Furthermore, according to the following relationship 2, the polishing pad can have a polishing rate difference (ΔRR) of 200 Å / min or less. [Equation 2] ΔRR = RR95 – RR85

[0035] In Equation 2, RR85 is the polishing rate (Å / min) at a distance of 85 mm from the wafer center in the polishing rate distribution of the CMP process for silicon oxide layers; while RR95 is the polishing rate (Å / min) at a distance of 95 mm from the wafer center in the polishing rate distribution of the CMP process for silicon oxide layers.

[0036] For example, the polishing rate difference (ΔRR) according to Equation 2 above can be 180 Å / min or less, 150 Å / min or less, 120 Å / min or less, 100 Å / min or less, 80 Å / min or less, or 50 Å / min or less. Since the polishing pad according to one embodiment has a polishing rate difference according to Equation 2 above and satisfying the above range, it has excellent polishing uniformity.

[0037] In addition, RR85 can be 1,950 Å / min to 3,300 Å / min, 2,000 Å / min to 3,000 Å / min, 2,100 Å / min to 2,950 Å / min, 2,250 Å / min to 2,900 Å / min, or 2,300 Å / min to 2,650 Å / min, and RR95 can be 2,000 Å / min to 3,500 Å / min, 2,150 Å / min to 3,350 Å / min, 2,200 Å / min to 3,200 Å / min, or 2,350 Å / min to 3,000 Å / min.

[0038] Furthermore, when the silicon oxide layer system of a silicon wafer is polished with cerium oxide slurry using this polishing pad, the average polishing rate can be from 2,100 Å / min to 3,500 Å / min according to the following mathematical formula 1. [Mathematical Expression 1] Average polishing rate (Å / min) = thickness difference before and after polishing (Å) / polishing time (min)

[0039] For example, when the silicon oxide layer of a silicon wafer is polished with a polishing pad using cerium oxide slurry, the average polishing rate (removal rate) can be 2,100 Å / min to 3,300 Å / min, 2,150 Å / min to 3,100 Å / min, 2,200 Å / min to 2,950 Å / min, or 2,250 Å / min to 2,800 Å / min.

[0040] Specifically, the polishing rate can be the polishing rate of a silicon wafer with a diameter of 300 mm, on which silicon oxide is deposited. Furthermore, the polishing rate can be measured under a polishing load of 4.0 psi while the polishing pad rotates at 150 rpm, calcined cerium oxide slurry is supplied to the polishing pad at a rate of 250 ml / min, and the platform rotates at 150 rpm for 60 seconds. There are no particular restrictions on the temperature conditions for measuring this polishing rate, but it can be, for example, room temperature.

[0041] Furthermore, the polishing pad may have an in-wafer non-uniformity (WIWNU) of 10% or less for oxides. For example, the in-wafer non-uniformity of the polishing pad for oxides may be 9% or less, 7% or less, 5% or less, 4% or less, or 3% or less.

[0042] The inhomogeneity (WIWNU) within the wafer is calculated using the following mathematical formula 2. [Mathematical Expression 2] Intra-wafer non-uniformity (WIWNU) (%) = (Standard deviation of polished thickness (Å) / Average polished thickness (Å)) × 100 (%) secondary pad

[0043] A polishing pad according to one embodiment includes a secondary pad. Specifically, the secondary pad is located below the top pad. More specifically, the secondary pad is used to support the top pad (i.e., the polishing layer) and to absorb and disperse impacts applied to the polishing layer. Therefore, damage and defects to the object to be polished can be minimized during the polishing process using this polishing pad.

[0044] The secondary pad may have a structure in which a plurality of pores are formed, and these pores may have an open cell structure, but are not limited thereto. In addition, the secondary pad may have a higher pore formation rate than the top pad, and may have a lower hardness than the top pad, making it softer.

[0045] According to one embodiment, the secondary pad may include a nonwoven fabric layer and a suede layer. Specifically, the secondary pad may include a suede layer on a nonwoven fabric layer, and the suede layer may be located on one side of the top pad. More specifically, the polishing pad may have a structure in which the top pad is stacked on the secondary pad, and it may have a structure in which the nonwoven fabric layer, the suede layer, and the top pad are stacked.

[0046] The nonwoven layer may be a resin-impregnated nonwoven layer. For example, the nonwoven layer may be a fibrous nonwoven layer comprising at least one fiber selected from the group consisting of: polyester fibers, polyamide fibers, polypropylene fibers, and polyethylene fibers.

[0047] Furthermore, the resin impregnated in the nonwoven layer may include at least one resin selected from the group consisting of: polyurethane resin, polybutadiene resin, styrene-butadiene copolymer resin, styrene-butadiene-styrene copolymer resin, acrylonitrile-butadiene copolymer resin, styrene-ethylene-butadiene-styrene copolymer resin, polysiloxane rubber resin, polyester elastomer resin and polyamide elastomer resin.

[0048] The suede layer can be combined with the non-woven fabric layer to form a pad. Specifically, the suede layer can be formed by casting a resin onto the non-woven fabric layer.

[0049] The resin used to prepare the suede layer may include at least one resin selected from the group consisting of: polyurethane resin, polybutadiene resin, styrene-butadiene copolymer resin, styrene-butadiene-styrene copolymer resin, acrylonitrile-butadiene copolymer resin, styrene-ethylene-butadiene-styrene copolymer resin, polysiloxane rubber resin, polyester elastomer resin and polyamide elastomer resin.

[0050] The thickness ratio of the non-woven fabric layer to the suede layer can be 1:0.5 to 2. For example, the thickness ratio of the non-woven fabric layer to the suede layer can be 1:0.7 to 1.8, 1:0.9 to 1.5, 1:1 to 1.2, 1:0.7 to 0.9, or 1:1.5 to 1.8.

[0051] The sub-pad may have a thickness of 0.5 mm to 2.5 mm. For example, the total thickness of the sub-pad may be 0.6 mm or higher, 0.7 mm or higher, 0.85 mm or higher, 0.95 mm or higher, 1 mm or higher, 1.1 mm or higher, 1.3 mm or higher, or 1.5 mm or higher, 0.5 mm to 2.3 mm, 0.6 mm to 2.15 mm, 0.8 mm to 2 mm, 1 mm to 1.9 mm, 1.2 mm to 1.9 mm, or 1.3 mm to 1.85 mm.

[0052] In addition, the sub-pad can have a hardness of 60 Shore D to 90 Shore D. For example, the hardness of the sub-pad can be 62 Shore D to 85 Shore D, 65 Shore D to 85 Shore D, or 65 Shore D to 83 Shore D.

[0053] The pad may have a compression ratio of 5% to 15%. For example, the compression ratio of the pad may be 5.5% to 13%, 6% to 11.5%, 6.5% to 10%, or 7% to 9%.

[0054] Specifically, the sub-plate was cut into 5 cm long and 5 cm wide pieces, and an 85 g weight was placed on each piece for 30 seconds. The thickness was measured using a turntable thickness gauge (Yasuda, 129-E) (A). An additional 800 g weight was placed on each piece (the 85 g weight and the 800 g weight were placed together) for 3 minutes to measure the thickness (B). The compression ratio was then calculated according to the following mathematical formula 3. [Mathematical Expression 3] Compression ratio (%) = [(A – B) / A] × 100

[0055] Additionally, the pad may have a density of 0.25 g / cm³ to 0.7 g / cm³. For example, the density of the pad may be 0.25 g / cm³ to 0.65 g / cm³, 0.3 g / cm³ to 0.65 g / cm³, or 0.3 g / cm³ to 0.6 g / cm³.

[0056] The pad can have a compressive elasticity of 70% to 90%. For example, the compressive elasticity can be 72% to 88% or 75% to 85%.

[0057] Specifically, compressive elasticity refers to the degree of recovery after compression. The sub-disc is cut into 5 cm long and 5 cm wide pieces, and an 85 g weight is placed on each piece for 30 seconds. The thickness (A) is measured using a turntable thickness gauge (Yasuda, 129-E). An additional 800 g weight is placed on top (the 85 g and 800 g weights are placed together) for 3 minutes, the 800 g weight is removed, and the disc is left to stand for 1 minute to measure the thickness (C). Compressive elasticity is calculated according to the following mathematical formula 4. [Mathematical Expression 4] Compressive elasticity (%) = [C / A] × 100

[0058] Although this pad is thicker than pads composed of a single layer of nonwoven fabric or suede, it has a lower density and its hardness, compressibility, and compressive elasticity are controlled within the desired range. As a result, the polishing rate distribution in the CMP process is uniform relative to the distance from the center, thereby improving polishing flatness. In particular, the polishing rate distribution characteristics at the edge of the polishing pad can be improved.

[0059] In addition, an adhesive layer can be inserted between the top pad and the sub-pad.

[0060] The adhesive layer may include a hot-melt adhesive. The hot-melt adhesive may be selected from at least one of the group consisting of: polyurethane resins, polyester resins, ethylene-vinyl acetate resins, polyamide resins, and polyolefin resins. As a specific example, the hot-melt adhesive may be selected from at least one of the group consisting of polyurethane resins and polyester resins.

[0061] In addition, a double-sided tape can be laminated beneath this support layer. When used in CMP equipment, once the release liner of the double-sided tape has been removed, it is attached to the platform for use. Top pad

[0062] A polishing pad according to one embodiment includes a top pad. Specifically, the top pad refers to an assembly that contacts a wafer to perform polishing and includes a polishing layer. More specifically, the top pad includes a polishing layer comprising a polyurethane resin.

[0063] The polished layer comprises a urethane prepolymer, a foaming agent, and a curing agent. Specifically, the polyurethane resin may be formed from a composition comprising a urethane prepolymer, a foaming agent, and a curing agent.

[0064] More specifically, the polishing layer comprises a polyurethane resin, which is a reaction product of a polyurethane prepolymer, a foaming agent, and a curing agent, i.e., a cured product of a mixture of these components. As a result, it comprises a porous polyurethane resin. Furthermore, the polishing layer may contain a plurality of pores formed by the foaming agent.

[0065] The polished layer may have a thickness of, for example, 0.8 mm or greater, 1 mm or greater, 1.2 mm or greater, or 1.5 mm or greater, and 5 mm or less, 3 mm or less, 2.5 mm or less, or 2 mm or less. As a specific example, the thickness of the polished layer may be from 0.8 mm to 5 mm or from 1.5 mm to 3 mm.

[0066] The polished layer may have a specific gravity of, for example, 0.6 g / cm³ or higher, 0.7 g / cm³ or higher, or 0.75 g / cm³ or higher, and 0.9 g / cm³ or lower, 0.85 g / cm³ or lower, or 0.8 g / cm³ or lower. As a specific example, the specific gravity of the polished layer may be from 0.6 g / cm³ to 0.9 g / cm³ or from 0.7 g / cm³ to 0.9 g / cm³.

[0067] The polished layer may have a hardness of, for example, 30 Shore D or greater, 40 Shore D or greater, or 50 Shore D or greater, 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 example, the hardness of the polished layer may be 30 Shore D to 80 Shore D or 50 Shore D to 65 Shore D.

[0068] The polished layer may have a tensile strength of, for example, 5 N / mm² or greater, 10 N / mm² or greater, 15 N / mm² or greater, 30 N / mm² or less, 25 N / mm² or less, or 20 N / mm² or less. As a specific example, the tensile strength of the polished layer may be from 5 N / mm² to 30 N / mm² or from 15 N / mm² to 25 N / mm².

[0069] The polished layer may have an elongation of, for example, 50% or greater, 70% or greater, 90% or greater, 106% or greater, or 120% or greater, and 300% or less, 250% or less, 200% or less, or 150% or less. As a specific example, the elongation of the polished layer may be from 50% to 300% or from 90% to 130%. This elongation may be the elongation at break.

[0070] As a specific example, the polished layer may have a hardness of 50 Shore D to 65 Shore D, a tensile strength of 15 N / mm² to 25 N / mm², and an elongation of 90% to 130%.

[0071] The pores are dispersed within the polished layer.

[0072] The average diameter of the pore can 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.

[0073] Furthermore, based on the total area of ​​the polished layer, the total area of ​​the pores can be 30% to 60%, 35% to 50%, or 35% to 43%. Furthermore, based on the total volume of the polished layer, the total volume of the pores can be 30% to 70% or 40% to 60%.

[0074] The polishing layer may have grooves on its surface for mechanical polishing. These grooves may have the desired depth, width, and spacing for mechanical polishing, without particular limitation.

[0075] According to one embodiment, the polishing pad comprises a carbamate-based prepolymer.

[0076] Prepolymers generally refer to polymers with relatively low molecular weights; the degree of polymerization is adjusted to an intermediate level to facilitate product molding during the manufacturing process. Prepolymers can be molded alone or after reacting with another polymerizable compound. For example, prepolymers can be prepared by reacting an isocyanate compound with a polyol.

[0077] The isocyanate compound used in the preparation of carbamate prepolymers may be selected from one of the group consisting of aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, or combinations thereof.

[0078] The isocyanate compound may include, for example, one selected from the group consisting of: toluene 2,4-diisocyanate (2,4-TDI), toluene 2,6-diisocyanate (2,6-TDI), naphthalene 1,5-diisocyanate, p-phenyl diisocyanate, bitoluene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and combinations thereof.

[0079] A polyol is a compound containing at least two or more hydroxyl groups (-OH) per molecule. For example, it may contain a group selected from one of the following: polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, and combinations thereof.

[0080] The polyol may include, for example, those selected from the group consisting of: polytetramethylene ether glycol, polypropylene ether glycol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 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, tripropylene glycol, and combinations thereof.

[0081] The polyol may have a weight average molecular weight (Mw) of 100 g / mol to 3,000 g / mol. For example, the weight average molecular weight of the polyol may be 100 g / mol to 3,000 g / mol, 100 g / mol to 2,000 g / mol, or 100 g / mol to 1,800 g / mol.

[0082] According to one embodiment, the polyol may comprise a low molecular weight polyol having a weight average molecular weight (Mw) of 100 g / mol to 300 g / mol, and a high molecular weight polyol having a weight average molecular weight (Mw) of 300 g / mol to 1,800 g / mol.

[0083] Furthermore, the carbamate prepolymer may have a weight average molecular weight (Mw) of 500 g / mole to 3,000 g / mole. For example, the weight average molecular weight of the carbamate prepolymer may be 500 g / mole to 2,500 g / mole, 1,000 g / mole to 2,000 g / mole, or 1,000 g / mole to 1,500 g / mole.

[0084] According to one embodiment, the isocyanate compound used to prepare the carbamate-based prepolymer may include an aromatic diisocyanate compound, and the aromatic diisocyanate compound may include, for example, 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI). The polyol compound used to prepare the carbamate-based prepolymer may include polytetramethylene ether glycol (PTMEG) and diethylene glycol (DEG).

[0085] According to one embodiment, the isocyanate compound used to prepare the carbamate-based prepolymer may include aromatic diisocyanate compounds and alicyclic diisocyanate compounds. 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 dicyclohexylmethane diisocyanate (H12MDI). The polyol compound used to prepare the carbamate-based prepolymer may include polytetramethylene ether glycol (PTMEG) and diethylene glycol (DEG).

[0086] The carbamate-based prepolymer may have an isocyanate end group content (NCO%) of 5% or more, 8% or more, or 10% or more, and 13% or less, 12% or less, or 11% or less. As a specific example, the carbamate-based prepolymer may have an isocyanate end group content (NCO%) of 8% to 11% or 9% to 10% by weight.

[0087] The isocyanate end group content (NCO%) of a carbamate prepolymer can be designed by comprehensively adjusting the following: the type and content of the isocyanate and polyol compounds used to prepare the carbamate prepolymer; the process conditions in the method used to prepare the carbamate prepolymer, such as temperature, pressure and time; and the type and content of the additives used in the preparation of the carbamate prepolymer.

[0088] If the isocyanate end group content (NCO%) of the urethane prepolymer meets the above range, the reaction rate, reaction time and final cured structure in the subsequent reaction between the urethane prepolymer and the curing agent can be adjusted in a manner that is beneficial to polishing performance, according to the purpose and intended use of the final polishing pad.

[0089] According to one embodiment, the urethane prepolymer may have an isocyanate end group content (NCO%) of 8% to 11% by weight or 9% to 10% by weight.

[0090] If the NCO% in the urethane prepolymer is less than the above range, the electrical properties based on the chemically hardened structure in the polishing pad may not be achieved, making it impossible to achieve the desired polishing performance in terms of polishing rate and flatness. Furthermore, due to the excessive increase in pad cutting rate, there may be a problem of shortened polishing pad life. On the other hand, if the NCO% exceeds the above range, surface defects on the semiconductor substrate (such as scratches and skip marks) may increase.

[0091] A foaming agent is a component used to form a porous structure in the polished layer. It may contain one selected from the group consisting of: solid-phase foaming agents, gas-phase foaming agents, liquid-phase foaming agents, and combinations thereof.

[0092] According to one embodiment, the foaming agent may be a non-chlorinated foaming agent that does not contain chlorine components. In particular, it may not contain chlorinated foaming agent components commonly used in the preparation of polishing pads, such as vinylidene chloride (VDC), or its content may be minimized. For example, the content of the non-chlorinated foaming agent, based on the total weight of the foaming agent, may be 50% or more by weight, 80% or more by weight, 90% or more by weight, 95% or more by weight, 97% or more by weight, 99% or more by weight, or 99.5% or more by weight, and 100% or less by weight, or 99.5% or less by weight. As a specific example, it may be 80% to 100% by weight, 90% to 100% by weight, or 80% to 99.5% by weight. Furthermore, the content of chlorine-based foaming agent, based on the total weight of the foaming agent, may be 20% by weight or less, 10% by weight or less, 5% by weight or less, 1% by weight or less, 0.5% by weight or less, or 0.3% by weight or less, as well as 0% by weight or more, 0.1% by weight or more, 0.5% by weight or more. As a specific example, it may be 0% to 20% by weight, 0% to 1% by weight, 0% to 0.5% by weight, or 0.5% to 20% by weight.

[0093] The foaming agent may be selected from at least one of the following: a solid-phase foaming agent containing particles with a hollow structure, a liquid-phase foaming agent using a volatile liquid, and an inert gas.

[0094] As an example, a solid-phase foaming agent may contain particles with a hollow structure that have expanded and adjusted in size by heat. This solid-phase foaming agent has the advantage of controlling uniform pore size because it is applied to the raw material in an expanded form and has a uniform particle size.

[0095] Furthermore, the solid-phase foaming agent may contain expandable particles. These expandable particles are particles that can expand due to heat and pressure. Their size in the final polished layer can be determined by the heat or pressure applied during the preparation of the polished layer. The expandable particles are applied to the raw material in an unexpanded particle state. Their final size is determined when they expand due to heat or pressure during the preparation of the polished layer.

[0096] 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. When the solid-phase foaming agent is applied to the raw material particles in an expanded state as described below, the average particle size of the solid-phase foaming agent may refer to the average particle size of the expanded particles themselves. When the solid-phase foaming agent is applied to the raw material particles in an unexpanded state as described below, it may refer to the average particle diameter of the particles after they have expanded due to heat or pressure during the preparation process.

[0097] Solid-phase foaming agents in the form of expandable particles may comprise a resin shell and an expansion-inducing component encapsulated within the shell. These expandable particles can form a hollow structure by vaporizing the encapsulated expansion-inducing component through heating during the preparation process.

[0098] For example, the shell may comprise a thermoplastic resin. The thermoplastic resin may be selected from at least one of the group consisting of: acrylonitrile copolymers, methacrylonitrile copolymers, and acrylic copolymers.

[0099] The thickness of the shell can be, for example, 0.1 µm or greater, 0.5 µm or greater, 1 µm or greater, 2 µm or greater, or 3 µm or greater, and 15 µm or less, 12 µm or less, or 10 µm or less, with 2 µm to 15 µm as a specific example.

[0100] The swelling-inducing component may comprise a compound selected from the group consisting of: hydrocarbon compounds, tetraalkylsilane compounds, and combinations thereof. Specifically, the hydrocarbon may comprise a compound selected from the group consisting of: ethane, ethylene, propane, propylene, n-butane, isobutane, n-butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, petroleum ether, and combinations thereof. The tetraalkylsilane compound may comprise a compound selected from the group consisting of: tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, trimethyln-propylsilane, and combinations thereof.

[0101] The solid-phase foaming agent may contain particles treated with inorganic components. In one embodiment, the solid-phase foaming agent may be treated with silicon oxide (SiO2) particles. Treating the solid-phase foaming agent with inorganic components can prevent aggregation between multiple particles. Solid-phase foaming agents treated with inorganic components may differ from those without inorganic component treatment in terms of the chemical, electrical, and / or physical properties of the foaming agent surface.

[0102] Commercial solid-phase foaming agents include Nouryon's 920DE20d70, 051DET40d25, and 051DET40d42, and Matsumoto's F-65DE, F-80DE, and FN-80SDE.

[0103] As a specific example, the foaming agent used in a polishing pad according to one embodiment comprises a solid-phase foaming agent. The solid-phase foaming agent may comprise at least one selected from the group consisting of: acrylonitrile copolymers, methyl methacrylate copolymers, methacrylonitrile copolymers, and acrylic copolymers.

[0104] The content of the solid-phase blowing agent may be 0.1 parts by weight or more, 0.5 parts by weight or more, or 1 part by weight or more, and 5 parts by weight or less, 3 parts by weight or less, or 2 parts by weight or less, relative to 100 parts by weight of the urethane prepolymer. As a specific example, the content of the solid-phase blowing agent may be from 0.1 parts by weight to 5 parts by weight or from 0.5 parts by weight to 2 parts by weight relative to 100 parts by weight of the urethane prepolymer.

[0105] The type and content of the solid foaming agent can be designed according to the desired pore structure and physical properties of the polished layer.

[0106] Simultaneously, a liquid-phase foaming agent can be introduced during the mixing and reaction of the prepolymer and the curing agent to form pores. It does not participate in the reaction between the prepolymer and the curing agent. Furthermore, the liquid-phase foaming agent is physically vaporized by the heat generated during the mixing and reaction of the prepolymer and the curing agent to form pores.

[0107] This volatile liquid-phase blowing agent is liquid at 25°C and does not react with isocyanate groups, amide groups, or alcohol groups. Specifically, the volatile liquid-phase blowing agent can be selected from the group consisting of: cyclopentane, n-pentane, cyclohexane, n-butyl acetate, bis(nonafluorobutyl)(trifluoromethyl)amine; and perfluorinated compounds, such as perfluorotributylamine, perfluoro-N-methylmorphofolin, perfluorotripentylamine, and perfluorohexane. Commercially available perfluorinated compounds include FC-40 (3M), FC-43 (3M), FC-70 (3M), FC-72 (3M), FC-770 (3M), FC-3283 (3M), and FC-3284 (3M).

[0108] Furthermore, the foaming agent may include a gas-phase foaming agent. For example, the foaming agent may include both a solid-phase foaming agent and a gas-phase foaming agent.

[0109] The vapor-phase blowing agent may contain an inert gas. This vapor-phase blowing agent is fed simultaneously with the reaction of the urethane-based prepolymer and the curing agent to serve as a pore-forming component.

[0110] There are no particular restrictions on the type of inert gas, as long as it is a gas that does not participate in the reaction between the urethane 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 combinations thereof.

[0111] The type and content of the vapor-phase foaming agent can be designed according to the desired pore structure and physical properties of the polished layer.

[0112] The inert gas can be fed at a volume of 10% to 30% of the total volume of the composition. Specifically, the inert gas can be fed at a volume of 15% to 30% of the total volume of the composition. Specifically, the gas-phase blowing agent can be fed through a predetermined feed line while the urethane prepolymer, the solid-phase blowing agent, and the curing agent are mixed. For example, the feed rate of the gas-phase blowing agent is about 0.8 L / min to about 2.0 L / min, about 0.8 L / min to about 1.8 L / min, about 0.8 L / min to about 1.7 L / min, about 1.0 L / min to about 2.0 L / min, about 1.0 L / min to about 1.8 L / min, or about 1.0 L / min to about 1.7 L / min.

[0113] The curing agent is a compound that reacts chemically with a urethane prepolymer to form the final cured structure in the polished layer. For example, it may contain amine compounds or alcohol compounds. Specifically, the curing agent may contain a compound selected from one of the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, aliphatic alcohols, and combinations thereof.

[0114] According to one embodiment, the curing agent may comprise a non-chlorine-based curing agent that does not contain chlorine components. For example, the content of the non-chlorine-based curing agent, based on the total weight of the curing agent, may be 50% or more by weight, 80% or more by weight, 90% or more by weight, 95% or more by weight, 97% or more by weight, 99% or more by weight, or 99.5% or more by weight, and 100% or less by weight, or 99.5% or less by weight. As a specific example, it may be 80% to 100% by weight, 90% to 100% by weight, or 80% to 99.5% by weight. Furthermore, the content of the chlorine-based curing agent, based on the total weight of the curing agent, can be 20% by weight or less, 10% by weight or less, 5% by weight or less, 1% by weight or less, 0.5% by weight or less, or 0.3% by weight or less, and 0% by weight or more, 0.1% by weight or more, 0.5% by weight or more. As a specific example, it can be 0% to 20% by weight, 0% to 1% by weight, 0% to 0.5% by weight, or 0.5% to 20% by weight.

[0115] The curing agent may be selected from at least one of solid-phase curing agents and liquid-phase curing agents.

[0116] The solid-phase curing agent may contain active hydrogen groups. The solid-phase curing agent may contain amine groups (-NH2) as active hydrogen groups.

[0117] Furthermore, the solid-phase curing agent can be an ester compound containing two or more benzene rings. Specifically, the solid-phase curing agent can contain two or more ester groups in its molecule.

[0118] The solid-phase curing agent may have a weight-average molecular weight of, for example, 150 g / mol to 400 g / mol, 150 g / mol to 350 g / mol, 200 g / mol to 350 g / mol, 250 g / mol to 350 g / mol, or 300 g / mol to 350 g / mol. Furthermore, the solid-phase curing agent may have a melting point (mp) of 100°C to 150°C, 100°C to 140°C, or 110°C to 130°C.

[0119] In one embodiment, the solid-phase curing agent comprises at least one selected from the group consisting of: 1,3-propanediol bis(4-aminobenzoate) (PDPAB), 4-(4-aminobenzoyl)oxyphenyl 4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl 4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl 4-aminobenzoate, and methylene dimethyl o-aminobenzoate (MBNA).

[0120] The liquid phase curing agent may contain an active hydrogen group. The liquid phase curing agent may contain at least one active hydrogen group selected from the group consisting of: amino (-NH2), hydroxyl (-OH), carboxylic acid (-COOH), epoxy group, and combinations thereof. Specifically, it may contain an amino (-NH2) group.

[0121] Furthermore, liquid phase curing agents may contain sulfur in their molecules. Specifically, they may contain two or more sulfur elements in their molecules.

[0122] The liquid phase curing agent may have a weight average molecular weight of 50 to 300, for example 100 to 250, for example 150 to 250, for example 200 to 250.

[0123] Furthermore, the liquid phase curing agent can be a liquid at room temperature. Alternatively, the liquid phase curing agent can 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.

[0124] Examples of such liquid phase curing agents include those selected from at least one of the following groups: 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), 2,6-bis(methylthio)-4-methyl-1,3-phenylenediamine, and N,N'-bis(secondary butylamino)diphenylmethane.

[0125] In addition to liquid-phase curing agents and solid-phase curing agents, the curing agent may further comprise other curing agents. The additional curing agent may be, for example, at least one of amine compounds and alcohol compounds. Specifically, the additional curing agent may comprise at least one compound selected from the group consisting of: aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols.

[0126] For example, the additional curing agent may be selected from at least one of the following groups: diaminodiphenylmethane, diaminodiphenylmethane, m-xylenediamine, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine, polypropylenetriamine, ethylene glycol, diethylene glycol, dipropylene glycol, butanediol, hexanediol, glycerol, and trimethylolpropane.

[0127] As a specific example, the curing agent may contain at least one selected from the group consisting of: 4,4'-methylenebis(2-chloroaniline) (MOCA), diethyltoluenediamine (DETDA), 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), 1,3-propanediol bis(4-aminobenzoate) (PDPAB), N,N'-bis(secondary butylamino)diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-phenylenediamine, 4-(4-aminobenzoyl)oxyphenyl-4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl-4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl-4-aminobenzoate, and methylenebis-methyl-o-aminobenzoate (MBNA).

[0128] The curing agent may be present in amounts of 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 prepolymer. The curing agent may also be present in amounts of 10 to 40 parts by weight, more particularly 15 to 35 parts by weight or 15 to 25 parts by weight, relative to 100 parts by weight of the urethane prepolymer.

[0129] Furthermore, the equivalent ratio of the urethane prepolymer to the curing agent can be from 1:0.5 to 2. For example, the equivalent ratio of the urethane prepolymer to the curing agent can be from 1:0.5 to 1.5, 1:0.5 to 1.0, or 1:0.6 to 1.2.

[0130] The composition used to prepare the polishing layer may further include other additives, such as a surfactant and a reaction rate controller. Names such as "surfactant" and "reaction rate controller" are arbitrary names based on the primary function of the substance. Individual substances do not necessarily perform functions limited to those defined by their names.

[0131] Surfactants are not specifically limited as long as their function is to prevent pore aggregation and overlap. For example, the surfactant may comprise a silicone-based surfactant.

[0132] The amount of surfactant used can be from 0.2 parts by weight to 2 parts by weight relative to 100 parts by weight of the urethane prepolymer. Specifically, the amount of surfactant used can be from 0.2 parts by weight to 1.9 parts by weight, 0.2 parts by weight to 1.8 parts by weight, 0.2 parts by weight to 1.7 parts by weight, 0.2 parts by weight to 1.6 parts by weight, 0.2 parts by weight to 1.5 parts by weight, or 0.5 parts by weight to 1.5 parts by weight relative to 100 parts by weight of the urethane prepolymer. If the amount of surfactant is within the above range, the pores derived from the vapor-phase foaming agent can be stably formed and maintained in the mold.

[0133] This reaction rate control agent has the effect of promoting or inhibiting the reaction. Depending on the purpose, a reaction promoter, a reaction inhibitor, or both may be used. The reaction rate control agent may contain a reaction promoter. For example, the reaction rate control agent may be at least one reaction promoter selected from the group consisting of tertiary amine compounds and organometallic compounds.

[0134] Specifically, the reaction rate control agent may comprise at least one selected from the group consisting of: triethylenediamine, dimethylethanolamine, tetramethylbutyldiamine, 2-methyl-triethylenediamine, 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, N,N-dimethylaminoethylmorpholine, N,N-dimethylcyclohexylamine, 2-methyl-2-azanorbornene, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, dioctyltin diacetate, dibutyltin maleate, dibutyltin di-2-ethylhexanoate, and dibutyltin dithiol. Specifically, the reaction rate control agent may include at least one selected from the group consisting of: benzyldimethylamine, N,N-dimethylcyclohexylamine, and triethylamine.

[0135] The reaction rate control agent can be used in an amount of 0.05 parts by weight to 2 parts by weight relative to 100 parts by weight of the urethane-based prepolymer. Specifically, the reaction rate control agent can be used in amounts of 0.05 parts by weight to 1.8 parts by weight, 0.05 parts by weight to 1.7 parts by weight, 0.05 parts by weight to 1.6 parts by weight, 0.1 parts by weight to 1.5 parts by weight, 0.1 parts by weight to 0.3 parts by weight, 0.2 parts by weight to 1.8 parts by weight, 0.2 parts by weight to 1.7 parts by weight, 0.2 parts by weight to 1.6 parts by weight, 0.2 parts by weight to 1.5 parts by weight, or 0.5 parts by weight to 1 part by weight relative to 100 parts by weight of the urethane-based prepolymer. If the reaction rate control agent is used within the above-mentioned content range, the curing reaction rate of the prepolymer composition can be appropriately controlled to form a polished layer with desired porosity and hardness. [Methods for preparing polishing pads]

[0136] A method for preparing a polishing pad according to another embodiment includes: (1) preparing a top pad using a top pad composition, the top pad composition comprising a urethane prepolymer, a foaming agent and a curing agent; (2) preparing a sub-pad comprising a nonwoven layer and a suede layer; and (3) combining the top pad and the sub-pad to prepare a polishing pad, wherein the polishing pad satisfies the above relation 1. (1) The step of preparing a top pad using a top pad composition comprising a carbamate prepolymer, a foaming agent and a curing agent;

[0137] A method for preparing a polishing pad according to another embodiment includes (1) preparing a top pad using a top pad composition comprising a carbamate prepolymer, a foaming agent and a curing agent.

[0138] The specific types and contents of the carbamate prepolymer, curing agent, and foaming agent are as illustrated above.

[0139] As a specific example, the foaming agent comprises a solid-phase foaming agent containing at least one selected from the group consisting of: acrylonitrile copolymers, methyl methacrylate copolymers, methacrylonitrile copolymers, and acrylic copolymers, and the curing agent contains at least one selected from the group consisting of: diethyltoluenediamine (DETDA), 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), and 1,3-propanediol bis(4-aminobenzoate). (PDPAB), N,N'-bis(secondary butylamino)diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-phenylenediamine, 4-(4-aminobenzoyl)oxyphenyl 4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl 4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl 4-aminobenzoate, and methylene bis-methyl o-aminobenzoate (MBNA).

[0140] The composition used for the top pad can be prepared by sequentially or simultaneously mixing a urethane prepolymer, a foaming agent, and a curing agent.

[0141] As an example, the steps for preparing the composition for the top pad can be carried out by: mixing a urethane prepolymer with a curing agent, and then further mixing it with a foaming agent; or mixing a urethane prepolymer with a foaming agent, and then further mixing it with a curing agent.

[0142] As another example, urethane prepolymers, curing agents, and foaming agents can essentially enter the mixing process simultaneously. If foaming agents, surfactants, and inert gases are further added, they can also essentially enter the mixing process simultaneously.

[0143] As another example, a urethane prepolymer, foaming agent, and surfactant can be mixed first, followed by the addition of a curing agent or a curing agent accompanied by an inert gas.

[0144] This mixing initiates the reaction between the urethane prepolymer and the curing agent, and uniformly disperses the blowing agent and the inert gas in the raw materials. In this case, a reaction rate control agent can intervene in the reaction between the urethane prepolymer and the curing agent from the beginning of the reaction to control the reaction rate. Specifically, the mixing can be carried out at speeds of 1,000 rpm to 10,000 rpm, or 4,000 rpm to 7,000 rpm. Within these speed ranges, it is more advantageous to uniformly disperse the inert gas and the blowing agent in the raw materials.

[0145] Furthermore, the preparation of the composition for the top pad can be carried out at temperatures ranging from 50°C to 150°C. If necessary, it can be carried out under vacuum defoaming conditions.

[0146] If the foaming agent contains a solid-phase foaming agent, the step of preparing the composition for the top pad may include: mixing the urethane prepolymer and the solid-phase foaming agent to prepare a first preliminary composition; and mixing the first preliminary composition with the curing agent to prepare a second preliminary composition.

[0147] The first preliminary composition may have a viscosity of about 1,000 cps to about 2,000 cps, about 1,000 cps to about 1,800 cps, about 1,000 cps to about 1,600 cps, or about 1,000 cps to about 1,500 cps at about 80°C.

[0148] If the foaming agent comprises a gas-phase foaming agent, the step of preparing the composition for the top pad may include: preparing a third preliminary composition comprising the urethane-based prepolymer and the curing agent; and feeding the gas-phase foaming agent into the third preliminary composition to prepare a fourth preliminary composition. In one embodiment, the third preliminary composition may further comprise a solid-phase foaming agent.

[0149] In one embodiment, the step of preparing the polished layer includes: preparing a mold preheated to a first temperature; injecting the composition for a top pad into the preheated mold and curing it; and post-curing the cured composition for the top pad at a second temperature above the preheated temperature.

[0150] According to one embodiment, the temperature difference between the first temperature and the second temperature can be from about 10°C to about 40°C, for example, from about 10°C to about 35°C, or from about 15°C to about 35°C. In one embodiment, the first temperature can be from about 60°C to about 100°C, from about 65°C to about 95°C, or from about 70°C to about 90°C. In one embodiment, the second temperature can be from about 100°C to about 130°C, for example, from about 100°C to about 125°C, or from about 100°C to about 120°C.

[0151] The step of curing the composition for the top pad at the first temperature can be carried out for about 5 minutes to about 60 minutes, about 5 minutes to about 40 minutes, about 5 minutes to about 30 minutes, or about 5 minutes to about 25 minutes.

[0152] The step of curing the component for the top pad, which has been cured at the first temperature, at the second temperature can be carried out for about 5 hours to about 30 hours, about 5 hours to about 25 hours, about 10 hours to about 30 hours, about 10 hours to about 25 hours, about 12 hours to about 24 hours, or about 15 hours to about 24 hours.

[0153] Subsequently, the step of injecting the composition for the top pad into a mold and allowing it to cure can be carried out at a temperature of 60°C to 120°C and a pressure of 50 kg / m² to 200 kg / m².

[0154] Furthermore, the method for preparing the top pad may further include the following steps: cutting the surface of the top pad thus obtained, machining grooves and the like on the surface. These steps can be performed in conventional methods for preparing the top pad.

[0155] As a specific example, the method for preparing the top pad may further include machining at least one side of the polished layer. The step of machining at least one side of the polished layer may include: forming a groove on at least one side of the polished layer; wire turning at least one side of the polished layer; and roughening at least one side of the polished layer.

[0156] These grooves may include at least one of the following: concentric circular grooves spaced at regular intervals from the center of the polished layer; and radial grooves continuously connected to the edge of the polished layer from the center of the polished layer. Wire turning can be performed by cutting the polished layer to a specific thickness using a cutting tool. Roughening can be performed by mechanically machining the surface of the polished layer with abrasive rollers. (2) Steps for preparing a secondary pad comprising a non-woven fabric layer and a suede layer

[0157] The method for preparing a polishing pad according to another embodiment includes: (2) preparing a pad comprising a nonwoven fabric layer and a suede layer.

[0158] Specifically, a nonwoven fabric layer is first prepared, and then a suede layer is formed on the nonwoven fabric layer, thereby preparing a secondary pad composed of a dual structure of a nonwoven fabric layer and a suede layer.

[0159] More specifically, step (2) includes impregnating a nonwoven fabric with a resin to prepare a nonwoven layer; and casting a resin onto one side of the nonwoven layer to form a suede layer.

[0160] First, a nonwoven fabric is impregnated with a resin to prepare a nonwoven layer.

[0161] The nonwoven fabric may be a fibrous nonwoven fabric comprising at least one fiber selected from the group consisting of: polyester fibers, polyamide fibers, polypropylene fibers, and polyethylene fibers. Furthermore, the impregnating resin may comprise at least one resin selected from the group consisting of: polyurethane resin, polybutadiene resin, styrene-butadiene copolymer resin, styrene-butadiene-styrene copolymer resin, acrylonitrile-butadiene copolymer resin, styrene-ethylene-butadiene-styrene copolymer resin, polysiloxane rubber resin, polyester elastomer resin, and polyamide elastomer resin.

[0162] Specifically, the nonwoven fabric is prepared by impregnation with the resin. As a specific example, the nonwoven fabric layer can be formed by impregnating polyester fibers with polyurethane resin and then drying them. The drying step can be carried out at 120°C to 150°C or 125°C to 145°C for 5 to 60 minutes, or 5 to 30 minutes.

[0163] The suede layer can be formed by casting resin onto the nonwoven layer. For example, the suede layer can be formed by casting at least one resin selected from the group consisting of: polyurethane resin, polybutadiene resin, styrene-butadiene copolymer resin, styrene-butadiene-styrene copolymer resin, acrylonitrile-butadiene copolymer resin, styrene-ethylene-butadiene-styrene copolymer resin, polysiloxane rubber resin, polyester elastomer resin, and polyamide elastomer resin. As a specific example, the suede layer can be formed by casting polyurethane resin onto the nonwoven layer and then drying it. The drying step can be carried out at 120°C to 150°C or 125°C to 145°C for 5 minutes to 60 minutes, or 5 minutes to 30 minutes.

[0164] Furthermore, once the suede layer has been formed on the nonwoven layer, the two sides of the pad (i.e., the outer surfaces of the nonwoven layer and the suede layer) can be sanded. As a specific example, this can be done by sanding the outer surfaces of the nonwoven layer and the suede layer with sanding rollers. (3) Step of combining the top pad and the sub-pad to prepare a polishing pad.

[0165] A method for preparing a polishing pad according to another embodiment includes: (3) combining the top pad and the sub-pad to prepare a polishing pad.

[0166] For example, an adhesive layer can be used to combine the top pad and the sub-pad. As a specific example, the sub-pad is placed below the top pad, and the top pad and the sub-pad are combined using a hot melt adhesive.

[0167] The hot melt adhesive may be selected from at least one of the group consisting of: polyurethane resins, polyester resins, ethylene-vinyl acetate resins, polyamide resins, and polyolefin resins. As a specific example, the hot melt adhesive may be selected from at least one of the group consisting of polyurethane resins and polyester resins.

[0168] In addition, a double-sided tape can be laminated beneath this support layer. When used in CMP equipment, once the release liner of the double-sided tape has been removed, it is attached to the platform for use. [Methods for fabricating semiconductor devices]

[0169] A method for fabricating a semiconductor device according to another embodiment includes using a polishing pad to polish the surface of a semiconductor substrate.

[0170] Specifically, a method for fabricating a semiconductor device may include: providing a polishing pad according to an embodiment; and rotating the polished surfaces of the polishing layer and the surface of the semiconductor substrate relative to each other while they are in contact to polish the surface of the semiconductor substrate.

[0171] Figure 9 illustrates a method for fabricating a semiconductor device using a polishing pad according to an embodiment. Referring to Figure 9, once the polishing pad (100) according to an embodiment has been attached to a platform (200), a semiconductor substrate (600), which is one of the objects to be polished, is placed on the polishing pad (100). In this case, the surface of the semiconductor substrate (600) to be polished is in direct contact with the polishing surface of the polishing pad (100). Polishing slurry (400) can be sprayed onto the polishing pad through a nozzle for polishing. The flow rate of the polishing slurry (400) supplied through the nozzle can be selected from about 10 cm3 / min to about 1,000 cm3 / min depending on the purpose. For example, it can be from about 50 cm3 / min to about 500 cm3 / min, but is not limited thereto.

[0172] Then, the semiconductor substrate (600) and the polishing pad (100) are rotated relative to each other, thereby polishing the surface of the semiconductor substrate (600). In this case, the rotation direction of the semiconductor substrate (600) and the rotation direction of the polishing pad (100) can be the same or opposite. The rotation speed of the semiconductor substrate (600) and the polishing pad (100) can each be selected from about 10 rpm to about 500 rpm depending on the purpose. For example, it can be from about 30 rpm to about 200 rpm, but it is not limited to this.

[0173] A semiconductor substrate (600) mounted on a polishing head (510) is pressed against the polishing surface of a polishing pad (100) with a predetermined load to make contact with it, and its surface can then be polished. The load applied to the polishing surface of the polishing pad (100) by the polishing head (510) through the surface of the semiconductor substrate (600) can be selected in the range of about 1 gf / cm2 to about 1,000 gf / cm2, depending on the purpose. For example, it can be about 10 gf / cm2 to about 800 gf / cm2, but it is not limited thereto.

[0174] In one embodiment, the semiconductor substrate (600) serving as the object to be polished may comprise an oxide layer, a uranium layer, or a composite layer thereof. Specifically, the semiconductor substrate (600) may comprise an oxide layer, a uranium layer, or a composite layer of an oxide layer and a uranium layer. The composite layer of the oxide layer and the uranium layer may be a multilayer film, wherein the uranium layer is deposited on one side of the oxide layer, or it may be a single-layer film, wherein oxide regions and uranium regions are mixed in the single layer. When the object to be polished has this film material and the polishing pad has the characteristics according to this embodiment, the semiconductor device manufactured according to the method for preparing a semiconductor device may have minimal defects.

[0175] In one embodiment, the method for fabricating a semiconductor device may further include: in the step of polishing the object to be polished, supplying the polishing surface with either a slurry for polishing oxides or a slurry for polishing tungsten layers; or sequentially supplying the slurry for polishing oxides and the slurry for polishing tungsten layers.

[0176] For example, if the semiconductor substrate, which is the object to be polished, contains an oxide layer, the method for fabricating a semiconductor device may include supplying a slurry for polishing the oxide layer. If the semiconductor substrate contains a tungsten layer, the method for fabricating a semiconductor device may include supplying a slurry for polishing the tungsten layer. If the semiconductor substrate contains a composite layer of an oxide layer and a tungsten layer, the method for fabricating a semiconductor device may include sequentially supplying a slurry for polishing the oxide layer and a slurry for polishing the tungsten layer to the polishing surface. Here, depending on the method, the slurry for polishing the oxide layer may be supplied first, followed by the slurry for polishing the tungsten layer; or the slurry for polishing the tungsten layer may be supplied first, followed by the slurry for polishing the oxide layer.

[0177] In one embodiment, in order to keep the polished surface of the polishing pad (100) in a state suitable for polishing, the method of preparing the semiconductor device may further include: while polishing the semiconductor substrate (600), simultaneously processing the polished surface of the polishing pad (100) using a regulator (300).

[0178] With the polishing pad according to one embodiment having a chlorine content adjusted to a specific range in the polishing layer, it is possible to reduce the size of debris during the CMP process while maintaining the excellent physical properties and performance of the polishing pad, thereby minimizing the occurrence of defects and scratches. Therefore, it is possible to efficiently fabricate semiconductor devices with high quality using this polishing pad. [Model of the Invention]

[0179] The present invention will now be described in detail by way of examples. These examples are intended to further illustrate the invention, and their scope is not limited thereto. [Preparation of polishing pads] [Example 1] (1) Preparation of the top pad

[0180] A four-necked flask is filled with toluene diisocyanate (TDI), dicyclohexylmethane diisocyanate (H12MDI), polytetramethylene ether glycol (PTMEG), and diethylene glycol (DEG), and then reacted at 80°C for 3 hours to prepare a urethane prepolymer having an isocyanate end group content (NCO%) of 8% to 12% by weight.

[0181] A casting machine is provided, equipped with tanks and feed lines for raw materials (such as urethane prepolymers, curing agents, and inert gases). Specifically, the urethane prepolymers prepared in step (1), curing agents (4,4'-methylenebis(2-chloroaniline), MOCA), solid-phase foaming agents (average particle size: 20 µm), inert gases (N2), and silicone surfactants (manufacturer: Evonik) are each loaded into a tank. Here, the solid-phase foaming agent is fed at 1.5 parts by weight relative to 100 parts by weight of the urethane prepolymer, and the urethane prepolymer and the curing agent are fed at a 1:1 equivalent ratio and a total feed rate of 10 kg / min.

[0182] Subsequently, the raw materials are fed at a constant rate to the mixing head (mixing head rotation speed: approximately 5,000 rpm) via separate feed lines while being stirred. A mold (1,000 mm × 1,000 mm × 3 mm) is prepared and preheated at 80°C. The stirred mixture is poured into the mold and reacted to obtain a molded article in the form of a solid block. Then, the top and bottom of the molded article are each ground to obtain a polished layer used as a top pad. Here, the top pad has a thickness of 2 mm, a hardness of 58.8 Shore D, a specific gravity of 0.79 g / cc, and an elongation of 111%. (2) Preparation of the secondary pad

[0183] Polyester nonwoven fabric is impregnated with a polyurethane resin and dried at 140°C for 10 minutes to prepare a nonwoven layer with a thickness of approximately 0.7 mm. A polyurethane resin is then cast onto this nonwoven layer and dried at 140°C for 10 minutes to form a suede layer with a thickness of approximately 0.8 mm, thereby preparing a secondary pad (total thickness: 1.53 mm) consisting of a double structure of the nonwoven layer and the suede layer. Subsequently, both sides of the secondary pad are sanded. Figure 1 shows a scanning electron microscope (SEM) image of the cross-section of the secondary pad in Example 1. (3) Preparation of polishing pad

[0184] The top pad prepared in step (1) undergoes surface milling and groove forming steps. Then, the sub-pad prepared in step (2) is placed below the top pad, and the top pad and sub-pad are joined using a hot melt adhesive to prepare a polishing pad (total thickness: 3.55 mm). In this case, the top pad is joined so that the suede layer of the sub-pad is in contact with the top pad. Furthermore, double-sided tape (model name: 442JS, manufacturer: 3M) is laminated under the sub-pad so that it can be attached to the platform of the CMP equipment. [Comparative Example 1] (1) Preparation of the top pad

[0185] The top pad is prepared in the same manner as in Example 1. (2) Preparation of the secondary pad

[0186] Polyurethane resin was cast onto a polyethylene terephthalate (PET) film, which was then dried at 140°C for 10 minutes to form a suede layer with a thickness of approximately 0.63 mm, thereby preparing a sub-pad with a single suede layer structure. The surface of the suede layer was then sanded. Figure 2 shows a scanning electron microscope (SEM) image of the cross-section of the sub-pad in Comparative Example 1. (3) Preparation of polishing pad

[0187] The polishing pad (total thickness: 2.65 mm) was prepared in the same manner as in Example 1. [Comparative Example 2] (1) Preparation of the top pad

[0188] The top pad is prepared in the same manner as in Example 1. (2) Preparation of the secondary pad

[0189] Polyester-based nonwoven fabric is impregnated with a polyurethane resin and dried at 140°C for 10 minutes to prepare a nonwoven layer with a thickness of approximately 1.30 mm, thereby preparing a sub-pad with a single nonwoven layer structure. Subsequently, both sides of the nonwoven layer are subjected to sanding treatment. Figure 3 shows a scanning electron microscope (SEM) image of the cross-section of the sub-pad in Comparative Example 2. (3) Preparation of polishing pad

[0190] The polishing pad (total thickness: 3.32 mm) was prepared in the same manner as in Example 1. [<] [Physical properties of the secondary pad] [Test Example 1] [:hardness]

[0191] The hardness of the pads prepared in Example 1 and Comparative Examples 1 and 2 was measured. Specifically, each pad was cut into pieces 5 cm long and 5 cm wide and stored at 25°C for 12 hours. Their Shore D hardness was measured using a hardness meter. [Test Example 2] Compression ratio

[0192] Compression ratios were measured for the sub-pad systems prepared in Example 1 and Comparative Examples 1 and 2. Specifically, each sub-pad was cut into 5 cm long and 5 cm wide pieces, and an 85 g weight was placed on each for 30 seconds, with the thickness measured using a rotary thickness gauge (Yasuda, 129-E) (A). An additional 800 g weight was placed on each piece (the 85 g weight and the 800 g weight were placed together) for 3 minutes to measure the thickness (B). The compression ratio was then calculated according to the following mathematical formula 3. [Mathematical Expression 3] Compressibility (%) = [(A – B) / A] × 100 [Test Example 3] [:density]

[0193] The densities of the sub-pads prepared in Example 1 and Comparative Examples 1 and 2 were measured according to ASTM D1622. [Test Example 4] [Compression elasticity]

[0194] The compressive elasticity of the sub-pads prepared in Example 1 and Comparative Examples 1 and 2 was measured. Specifically, each sub-pad was cut into 5 cm long and 5 cm wide pieces, and an 85 g weight was placed on each for 30 seconds, with the thickness (A) measured using a turntable thickness gauge (Yasuda, 129-E). An additional 800 g weight was placed on each piece (the 85 g weight and the 800 g weight were placed together) for 3 minutes, the 800 g weight was removed, and the piece was left to stand for 1 minute to measure the thickness (C). The compressive elasticity was calculated according to the following mathematical formula 4. [Mathematical Expression 4] Compressive elasticity (%) = [C / A] × 100 [<] [Physical properties of polishing pads>] [Test Example 5] Polishing rate () [Removal rate]

[0195] The polishing pads of Example 1 and Comparative Examples 1 and 2 were each fixed to the platform of the CMP equipment, and a silicon wafer (300 mm in diameter) was placed with its silicon oxide layer facing down. Then, a CMP process was performed to measure the polishing rate.

[0196] Specifically, the silicon oxide layer was polished under a polishing load of 4.0 psi, while the platform was rotated at 150 rpm for 60 seconds and calcined cerium oxide slurry and silicon dioxide slurry were supplied to the polishing pad at a rate of 250 ml / min. After polishing, the silicon wafer was removed from the carrier, placed in a rotary dryer, washed with deionized water, and then dried with nitrogen for 15 seconds. The thickness difference of the silicon oxide layer in the dried silicon wafer before and after polishing was measured using a spectroreflectometer-type thickness gauge (model: SI-F80R, manufacturer: Keyence). The polishing rate was calculated according to the following mathematical formula 1. [Mathematical Expression 1] Polishing rate (Å / min) = Thickness difference before and after polishing (Å) / Polishing time (min)

[0197] Furthermore, the slope between 85 mm and 95 mm from the wafer center in the polishing rate distribution obtained by measuring the polishing rate. [Test Example 6] Intra-wafer inhomogeneity

[0198] The polishing pads of Example 1 and Comparative Examples 1 and 2 were each fixed to the platform of the CMP equipment, and a silicon wafer (300 mm in diameter) was placed with its silicon oxide layer facing down. Then, a CMP process was performed to measure the non-uniformity within the wafer.

[0199] Specifically, the polishing was performed in the same manner as in Test Example 5. The in-plane film thickness of the wafer was measured at 98 points, and the in-wafer non-uniformity (WIWNU) was measured according to the following mathematical formula 2. [Mathematical Expression 2] Intra-wafer non-uniformity (WIWNU) (%) = (Standard deviation of polished thickness (Å) / Average polished thickness (Å)) × 100 (%) [Table 1] Example 1 Comparison Example 1 Comparison Example 2 secondary pad Thickness (mm) 1.53 0.63 1.30 Hardness (Shore D) 70.7 75.9 72 Compression ratio (%) 8.9 8.9 9.4 Density (g / cm3) 0.35 0.62 0.34 Compressive elasticity (%) 80.3 93.0 80.3 polishing pad R85 (Å / min) 2,459 1,943 2,213 R95 (Å / min) 2,532 1,587 2,101 Average polishing rate (Å / min) 2,301 2,000 2,072 slope 7.3989 -30.948 -20.311 Intra-wafer non-uniformity (%) 4.0 8.3 5.7

[0200] As can be seen from Table 1 above, in the polishing pad according to Example 1, the polishing rate distribution for the CMP process of the silicon oxide layer is higher at a distance of 95 mm from the wafer center than at a distance of 85 mm from the wafer center. Therefore, both the polishing rate and the polishing flatness are excellent.

[0201] More specifically, in Comparative Examples 1 and 2, where a sub-pad consisting of a single layer of suede or non-woven fabric, as in the prior art, is used, the slope between 85 mm and 95 mm from the wafer center in the polishing rate distribution of the CMP process for the silicon oxide layer has a negative value. In contrast, in the polishing pad of Example 1, which uses a dual structure of non-woven fabric and suede layers, the slope between 85 mm and 95 mm from the wafer center in the CMP process for the silicon oxide layer has a positive value, indicating a different trend in polishing rate distribution characteristics. In particular, in Comparative Examples 1 and 2, the slope is negative and is a larger value of approximately -30.948 and -20.311, while Example 1 has a positive slope with a value of approximately 7.3989. The latter shows that the polishing rate varies little at the edges, indicating excellent polishing uniformity; in contrast, Comparative Examples 1 and 2 show that the polishing rate drops sharply at the edges (see Figures 4 to 8).

[0202] Furthermore, since the pads of Example 1 have a lower density relative to thickness compared to the pads of Comparative Examples 1 and 2, the polishing rate is uniformly distributed relative to the distance from the wafer center in the CMP process, resulting in excellent polishing flatness.

[0203] 100: Polishing Pad 200: Platform 300: Regulator 400: Polishing slurry 510: Polishing head 520: Carrier 600: Semiconductor substrate (wafer)

Claims

1. A polishing pad comprising a top pad and a sub-pad, the top pad being in contact with a wafer to perform polishing, and the sub-pad being located on one side of the top pad, wherein the sub-pad comprises a non-woven fabric layer and a suede layer, wherein the following relation 1 is satisfied: [Relation 1] RR85 < RR95 In relation 1, RR85 is the polishing rate (Å / min) at a distance of 85 mm from the wafer center in the polishing rate profile of a CMP process for a silicon oxide layer; and RR95 is the polishing rate (Å / min) at a distance of 95 mm from the wafer center in the polishing rate profile of a CMP process for a silicon oxide layer.

2. The polishing pad of claim 1, wherein the average slope between distances of 85 mm and 95 mm from the wafer center has a positive value in the polishing rate distribution of the CMP process for the silicon oxide layer.

3. The polishing pad of claim 1, wherein in the polishing rate distribution for the CMP process of the silicon oxide layer, the average slope between distances of 85 mm and 95 mm from the wafer center is 0.5 or higher.

4. The polishing pad of claim 1, wherein the polishing pad has an in-wafer non-uniformity (WIWNU) of 10% or less for oxides, and the polishing rate difference (ΔRR) according to the following Equation 2 is 200 Å / min or less: [Equation 2] ΔRR = RR95 – RR85 In Equation 2, RR85 is the polishing rate (Å / min) at a distance of 85 mm from the wafer center in the polishing rate distribution for CMP processes of silicon oxide layers; and RR95 is the polishing rate (Å / min) at a distance of 95 mm from the wafer center in the polishing rate distribution for CMP processes of silicon oxide layers.

5. The polishing pad of claim 1, wherein when the silicon oxide layer of the silicon wafer is polished with cerium oxide slurry using the polishing pad, the average polishing rate can be from 2,100 Å / min to 3,500 Å / min according to the following mathematical formula 1: [Mathematical formula 1] Average polishing rate (Å / min) = thickness difference before and after polishing (Å) / polishing time (min).

6. The polishing pad of claim 1, wherein the suede layer is located on one side of the top pad, and the thickness ratio of the nonwoven layer to the suede layer is 1:0.5 to 2.

7. The polishing pad of claim 1, wherein the secondary pad has: a thickness of 0.5 mm to 2.5 mm, a hardness of 60 Shore D to 90 Shore D, a compression ratio of 5% to 15%, a density of 0.25 g / cm3 to 0.7 g / cm3, and a compressive elasticity of 70% to 90%, and the top pad has: a hardness of 50 Shore D to 65 Shore D, a specific gravity of 0.6 g / cm3 to 0.9 g / cm3, a tensile strength of 15 N / mm2 to 25 N / mm2, and an elongation of 90% to 130%.

8. A method for preparing a polishing pad, comprising: (1) preparing a top pad using a top pad composition comprising a carbamate prepolymer, a foaming agent and a curing agent; (2) preparing a sub-pad comprising a nonwoven layer and a suede layer; and (3) combining the top pad and the sub-pad to prepare a polishing pad, wherein the polishing pad satisfies the following relation 1: [Relation 1] RR85 < RR95 In relation 1, RR85 is the polishing rate (Å / min) at a distance of 85 mm from the wafer center in the polishing rate distribution for a CMP process of a silicon oxide layer; and RR95 is the polishing rate (Å / min) at a distance of 95 mm from the wafer center in the polishing rate distribution for a CMP process of a silicon oxide layer.

9. The method for preparing the polishing pad as claimed in claim 8, wherein step (2) comprises: impregnating a nonwoven fabric with a resin to prepare a nonwoven layer; and casting a resin onto one side of the nonwoven layer to form a suede layer.

10. A method of fabricating a semiconductor device, comprising polishing the surface of a semiconductor substrate using a polishing pad as claimed in claim 1.

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