Polishing pad, manufacturing method thereof, and manufacturing method of semiconductor element using the same

Abstract

To provide a polishing pad that improves the polishing rate and flatness by adjusting the size and distribution of pores, a method for manufacturing the same, and a method for manufacturing a semiconductor element using the polishing pad.SOLUTION: A polishing pad includes an abrasive layer including a plurality of pores, the average diameter (Da) of the plurality of pores is 15 μm to 50 μm in the diameter distribution of the plurality of pores with respect to the polishing surface, and pores (Au) having a diameter greater than 200% of the number average diameter of the plurality of pores are included in an area ratio of more than 0.9% to less than 12% of the total area of the polishing surface.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The embodiment relates to a polishing pad that can be used in a semiconductor chemical mechanical polishing (CMP) process, a method for manufacturing the same, and a method for manufacturing a semiconductor device using the same. [Background technology]

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

[0003] Polishing pads are essential materials that play a key role in the CMP process. They are generally made of polyurethane resin and have grooves on their surface that allow for large flows of slurry, as well as pores that support fine flows.

[0004] The pores in the polishing pad can be formed using a solid-phase foaming agent with voids, a liquid-phase foaming agent filled with a volatile liquid, an inert gas, fibers, etc., or by generating gas through a chemical reaction.

[0005] The solid-phase blowing agent used is a microcapsule whose size has been adjusted by thermal expansion (thermally expanded microcapsule). The thermally expanded microcapsules have a uniform particle size as a structure of pre-expanded microballoons, making it possible to uniformly adjust the particle size of the pores. However, the thermally expanded microcapsules have the disadvantage that their shape changes under high-temperature reaction conditions of 100°C or higher, making it difficult to adjust the pore size. Furthermore, even if uniformity in quality is achieved through the size and distribution of the pores, there is limited freedom in designing the pores, limiting the ability to adjust the pore distribution.

[0006] For example, Patent Document 1 discloses a method for manufacturing a low-density polishing pad using an inert gas and a pore-inducing polymer, and a low-density polishing pad. However, the published patent has limitations in adjusting the size and distribution of the pores, and does not disclose anything about the removal rate of the polishing pad.

[0007] Similarly, Patent Document 2 discloses a method for manufacturing a polishing pad using two types of solid-phase foaming agents with different particle sizes, but the registered patent also has limitations in adjusting the size and distribution of pores to improve polishing performance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 2016-0027075 [Patent Document 2] Korean Patent No. 10-0418648 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, the object of the embodiment is to provide a polishing pad, a manufacturing method thereof, and a method for manufacturing a semiconductor device using the polishing pad, in which the size and distribution of pores can be adjusted to improve the polishing rate and flatness. [Means for solving the problem]

[0010] To achieve the above object, one embodiment includes a polishing layer containing a plurality of pores, and the polishing surface has a unit area (mm 2 The total area of ​​the pores per unit area is 40% to 60%, and D is expressed by the following mathematical formula 1: q The value is 5μm or more to 15μm or less, and is expressed by the following mathematical formula 2. sk The value is greater than 0.3 and less than 1, and is expressed by the following mathematical formula 3: ku The polishing pad has a value of greater than 1 and less than 5.

[0011] [Number 1] JPEG0007778859000001.jpg2243[number 2] JPEG0007778859000002.jpg2258[number 3] JPEG0007778859000003.jpg2160

[0012] In the above mathematical formulas 1 to 3, d is the value obtained by subtracting the number mean diameter of multiple pores from each pore diameter, and n is the unit area (mm 2 ) is the total number of pores per unit area.

[0013] Another embodiment includes a polishing layer including a plurality of pores, wherein the diameter distribution of the pores relative to the polishing surface is such that the number average diameter (D a ) is 15 μm to 50 μm, and the pores (A u ) is contained in an area ratio of 0.9% or more and less than 12% of the total area of ​​the polishing surface.

[0014] Another embodiment includes a step of mixing a composition including a urethane-based prepolymer, a curing agent, and a foaming agent, and a step of extruding and injecting the composition into a mold under a predetermined pressure condition to form a polishing layer, wherein the polishing layer includes a plurality of pores and has a polishing surface with a unit area (mm 2 The total area of ​​the pores per unit area is 40% to 60%, and D q The value is 5 μm or more to 15 μm or less, and D is expressed by the above mathematical formula 2 sk The value is greater than 0.3 and less than 1, and D is represented by the above mathematical formula 3. ku The present invention provides a method for producing a polishing pad in which the value is greater than 1 and less than 5.

[0015] Another embodiment includes a step of mixing a composition including a urethane-based prepolymer, a curing agent, and a solid-phase foaming agent, and a step of discharging and injecting the mixed composition into a mold under reduced pressure to form a polishing layer, wherein the reduced pressure is a vacuum of 0.6 kgf / cm. 2~1kgf / cm 2 The polishing pad includes a polishing layer containing a plurality of pores, and the diameter distribution of the pores based on the polishing surface is such that the number average diameter (D a ) is 15 μm to 50 μm, and the pores (A u ) accounts for 0.9% or more and less than 12% of the total area of ​​the polishing surface.

[0016] Another embodiment includes the steps of: attaching a polishing pad including a polishing layer including a plurality of pores to a platen; and rotating the polishing surface of the polishing layer relative to the surface of a wafer so that the polishing surface of the polishing layer and the surface of the wafer are brought into contact with each other, thereby polishing the surface of the wafer, wherein the polishing layer has a surface area (mm 2 The total area of ​​the pores per unit area is 40% to 60%, and D q The value is 5 μm or more to 15 μm or less, and D is expressed by the above mathematical formula 2 sk The value is greater than 0.3 and less than 1, and D is represented by the above mathematical formula 3. ku The present invention provides a method for manufacturing a semiconductor element, wherein the value is greater than 1 and less than 5.

[0017] Another embodiment includes a step of attaching a polishing pad including a polishing layer including a plurality of pores to a platen, and polishing the surface of the wafer by rotating the polishing surface of the polishing layer relative to the surface of the wafer so that the polishing surface of the polishing layer and the surface of the wafer are brought into contact with each other, and a step of polishing the surface of the wafer by rotating the polishing pad relative to the surface of the wafer, wherein the diameter distribution of the plurality of pores based on the polishing surface is a number average diameter (D a ) is 15 μm to 50 μm, and the pores (A u ) accounts for 0.9% or more and less than 12% of the total area of ​​the polished surface. [Effects of the Invention]

[0018] According to the above embodiment, the size (diameter) and distribution of the pores contained in the polishing pad can be adjusted, so that the polishing pad has a specific range of total pore area per unit area and D in Equations 1 to 3. q , D sk and D ku or the number average diameter (D a ) and by controlling the pores to have a diameter that is 200% or more larger than the number average diameter of the plurality of pores, polishing performance such as polishing rate and flatness can be further improved.

[0019] Furthermore, the polishing pad can be used to efficiently manufacture semiconductor elements of excellent quality. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 shows a schematic process for manufacturing a semiconductor device according to one embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a molding process using a mold according to one embodiment of the present invention. [Figure 3] FIG. 3 is a scanning electron microscope (SEM) image of pores in the polishing pad in Example 1-1. [Figure 4] FIG. 4 is a 100-fold magnified image of the polishing surface of 1 mm 2 of the polishing pad in Example 1-1 taken with a scanning electron microscope (SEM). DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described in more detail below. In the following description of implementation examples, when each layer, pad, etc. is described as being formed "on" or "under" each other, "on" and "under" include all layers, pads, etc. formed directly or indirectly through other components.

[0022] The reference to the top / bottom of each component will be explained based on the drawings. Note that the size of each component in the drawings may be exaggerated for the purpose of explanation and does not represent the size that is actually applied.

[0023] As used herein, the term "plurality" refers to more than one. In this specification, unless otherwise specified, when a part is said to "comprise" a certain component, it does not mean that it excludes other components, but that it may further include other components.

[0024] Furthermore, all numerical ranges expressing physical properties, dimensions, etc. of components described herein should be understood to be modified in all cases by the term "about" unless otherwise specified.

[0025] The present invention will be described in detail below with reference to examples, which may be modified in various ways without departing from the spirit of the invention.

[0026] [Polishing pad] The polishing pad according to one embodiment includes a polishing layer containing a plurality of pores, and has a polishing surface with a unit area (mm 2 The total area of ​​the pores per unit area is 40% to 60%, and D is expressed by the following mathematical formula 1. q The value is 5μm or more to 15μm or less, and is expressed by the following mathematical formula 2. sk The value is greater than 0.3 and less than 1, and is expressed by the following mathematical formula 3: ku The value is greater than 1 and less than 5.

[0027] [Number 1] JPEG0007778859000004.jpg2243[number 2] JPEG0007778859000005.jpg2258[number 3] JPEG0007778859000006.jpg2160

[0028] In the above mathematical formulas 1 to 3, d is the value obtained by subtracting the number-average diameter of multiple pores from the diameter of each pore, and n is the unit area (mm2 ) is the total number of pores per unit area.

[0029] D in the above mathematical formulas 1 to 3 q , D sk and D ku is the pore diameter of each pore, the number average diameter of multiple pores (D a ), and the total number of pores per unit area.

[0030] The diameter of the pores, the number average diameter of the plurality of pores, and the total number of the pores are 2 The pore size can be measured using a scanning electron microscope (SEM) and image analysis software based on the measured pore size, and the number of pores can be calculated. The polishing surface can refer to any one of the surfaces that are continuous in the thickness direction of the polishing layer. The polishing surface can also be the outermost surface that appears immediately after the polishing pad is manufactured, or the outermost surface that appears after a polishing process has been performed for a predetermined period of time.

[0031] The polishing pad has a change in the fluidity of the polishing slurry and a change in the polishing efficiency depending on the diameter and distribution of the pores on the surface of the polishing pad. That is, the fluidity of the polishing slurry is affected by the diameter of the pores on the surface of the polishing pad, and the distribution of the pore diameters can determine the occurrence of scratches on the surface of the object being polished and the polishing rate.

[0032] In one embodiment, the polishing pad can be adjusted by adjusting the number average diameter of the pores and the total number of pores per unit area, thereby adjusting the total area of ​​the pores and the D in Equations 1 to 3. q , D sk and D ku These parameters can be designed to have specific ranges, and as a result, excellent polishing rate and flatness can be achieved.

[0033] Therefore, it is very important to adjust the pore diameter and pore dispersion in the polishing pad, and in particular, to improve polishing performance, it is very important to design the pore diameter based on the polishing mechanism between the slurry and the semiconductor substrate in the CMP process.

[0034] D shown in the above mathematical formula 1 q The D value is a parameter closely related to the pore size in the pore distribution, and is a measure of how the pores are spread out relative to the number-average diameter of the pores in the pore distribution graph. q A larger value means a larger stomatal dispersion, and D q A small value means a small dispersion.

[0035] The above D q The value is the pore diameter of the polished surface and the number average diameter of multiple pores (D a ) can be calculated using the root mean square (RMS) of the difference d. q The value may be 5 μm or more and 15 μm or less, specifically 7 μm or more and 14 μm or less, more specifically 7 μm or more and 13 μm or less, more than 10 μm and 15 μm or less, 5 μm or more and 10 μm or less, or 8 μm or more and 12 μm or less. q When the value is within the above range, the polishing performance such as the polishing rate and flatness is excellent. q If the value exceeds 15 μm, the polishing performance requiring physical CMP, particularly the polishing rate when polishing a tungsten film, may increase excessively, and the flatness of the oxide film and the tungsten film may deteriorate. q If the value is less than 5 μm, the amount of slurry carried per pad area is small, which may result in an excessively low polishing rate when polishing a tungsten film or a deterioration in flatness relative to an oxide film.

[0036] In the above mathematical formula 1, the number average diameter (Da) of the pores on the polished surface is 2 The sum of the pore diameters in the D may be defined as an average value obtained by dividing the sum by the number of pores.a The polishing pad may have a D in the range of 15 μm to 25 μm, specifically 18 μm to 25 μm, more specifically 18 μm to 23 μm, or 18 μm to 22 μm. a If D is satisfied, the polishing rate and flatness can be improved. a If the thickness is less than 15 μm, the polishing rate when polishing a tungsten film will be excessively low and the flatness relative to an oxide film will be poor. On the other hand, if the thickness exceeds 25 μm, both the polishing rate and the flatness relative to a tungsten film and an oxide film will be poor.

[0037] In addition, D shown in the above mathematical formula 2 sk The value D may represent the degree of deviation of the pore distribution graph with respect to the number average diameter of the pores. sk In the case of , it is a measure of how much the pore distribution graph is biased toward the smaller or larger side compared to the number-average diameter of pores in the pore distribution graph. When it is less than 1, it means that the pore distribution graph is biased toward the smaller side compared to the number-average diameter of pores for a normal distribution, and when it is greater than 1, it means that the pore distribution graph is biased toward the larger side compared to the number-average diameter of pores for a normal distribution.

[0038] The above D relating to the implementation example sk The value may be greater than 0.3 and less than 1, specifically greater than 0.4 and less than 1, more specifically greater than 0.4 and less than 0.9, greater than 0.6 and less than 1, or greater than 0.3 and less than 0.6. sk When the value is within the above range, it can be said that the number of large pores is greater than the number average diameter of the pores, and the polishing performance such as the polishing rate and flatness of the polishing pad is excellent. sk If the value is 0.3 or less, it means that there are more small pores relative to the number average diameter of the pores. In this case, the amount of slurry carried per unit area of ​​the polishing pad is small, so the polishing rate, especially when polishing a tungsten film, may be significantly reduced. skIf the value is 1 or more, the polishing rate when polishing a tungsten film may increase excessively, and the flatness of the tungsten film and oxide film may deteriorate.

[0039] Meanwhile, D shown in the above mathematical formula 3 ku The value indicates how broad the overall pore distribution is; when it is less than 3, it means that the pore distribution is sharp compared to the normal distribution of the average pore diameter, and when it is greater than 3, it means that the pore distribution is broad compared to the normal distribution.

[0040] According to an embodiment of the present invention, D ku The value may be a number close to 3, that is, greater than 1 and less than 5, greater than 2 and less than 5, greater than 2.5 and less than 4.5, greater than 3.5 and less than 5, greater than 1 and less than 3.5, greater than 1 and less than 4, greater than 2 and less than 3, or greater than 3 and less than 4.5, ku If the value satisfies the above range, the fluidity of the polishing slurry is excellent, and the polishing rate and flatness can be improved. ku If the value is less than 1, the polishing rate when polishing a tungsten film may be significantly reduced, and ku If the value is 5 or more, the pore size will not be uniform, which may have an adverse effect on the fluidity of the polishing slurry, and scratches may occur on the surface of the object being polished, which may reduce polishing performance such as polishing rate and flatness.

[0041] According to the implementation example, in the above mathematical formulas 1 to 3, the unit area (mm 2 n, which indicates the total number of pores per pore, may be 700 to 2500, specifically 750 to 2200. d, which indicates the difference between the diameter of each pore and the number-average diameter of the pores, may be -30 to 60, specifically -20 to 50.

[0042] Furthermore, the polishing pad may have a total pore area per unit area of ​​the polishing surface of 40% to 60%, specifically 40% to 55%, more specifically 40% to 50%, more than 50% to 60%, or 45% to 53%. If the total pore area is less than 40%, the polishing rate when polishing a tungsten film may be excessively small, and the flatness of an oxide film may be deteriorated. On the other hand, if the total pore area is more than 60%, the polishing rate when polishing a tungsten film may be excessively large, or the polishing rate when polishing an oxide film may be excessively small. Furthermore, the flatness of the tungsten film may be significantly deteriorated.

[0043] The polishing pad according to the embodiment of the present invention has a total area of ​​the pores per unit area of ​​the polishing surface and D in the above mathematical formulas 1 to 3. q , D sk and D ku All of the above ranges must be satisfied.

[0044] According to one embodiment, the polishing pad has a total area of ​​the pores per unit area of ​​the polishing surface of 40% to 50%, and the D q The value is more than 10 μm and 15 μm or less, and sk The value is greater than 0.6 and less than 1, and ku The value can be greater than 3.5 and less than 5.

[0045] According to another embodiment, the polishing pad has a total area of ​​the pores per unit area of ​​the polishing surface of more than 50% to 60% or less, and the D q The value is 5 μm or more and 10 μm or less, and the D sk The value is more than 0.3 and not more than 0.6, and ku The value can be greater than 1 and less than or equal to 3.5.

[0046] In another embodiment, the polishing pad includes a polishing layer including a plurality of pores, and the diameter distribution of the pores relative to the polishing surface is such that the number average diameter (D a ) is 15 μm to 50 μm, and the pores (A u) is contained in an area ratio of 0.9% or more and less than 12% of the total area of ​​the polishing surface.

[0047] The number-average diameter and area ratio of the pores can be calculated by measuring the diameter of each pore observed using a scanning electron microscope (SEM) and image analysis software. The polishing surface can refer to any one of the surfaces that are continuous in the thickness direction of the polishing layer. The polishing surface can also be the outermost surface that appears immediately after the polishing pad is manufactured, or the outermost surface that appears after a polishing process has been performed for a predetermined period of time.

[0048] The polishing pad's fluidity and polishing efficiency vary depending on the diameter of the pores present on its surface. That is, the fluidity of the polishing slurry is affected by the diameter of the pores present on the surface of the polishing pad, and the distribution of these pore sizes determines the polishing rate and the occurrence of scratches on the surface of the object being polished. In particular, uneven pore size can result in a loss of uniformity in polishing performance. In one embodiment, the polishing pad can improve the uniformity of pores and polishing performance by controlling pores to have a diameter 200% or more larger than the number-average diameter of the pores, thereby achieving excellent polishing rates and flatness.

[0049] According to an embodiment of the present invention, the polishing pad includes a polishing layer containing a plurality of pores, and D represented by Equation 1 q The value is 5 μm or more to 15 μm or less, and D is expressed by the above mathematical formula 2 sk The value is greater than 0.3 and less than 1, and D is represented by the above mathematical formula 3. ku The value is greater than 1 and less than 5, and in the diameter distribution of the pores based on the polished surface, the number average diameter (D a ) is 15 μm to 50 μm, and the pores (A u ) may be included in an area ratio of 0.9% or more to less than 12% of the total area of ​​the polishing surface. 2The total area of ​​the pores per unit area may be 40% to 60%.

[0050] D in the above mathematical formulas 1 to 3 q , D sk and D ku The pore distribution shows the number average diameter of the pores (D a ) and by controlling the pores to have a diameter that is 200% or more larger than the number average diameter of the plurality of pores, the uniformity of polishing performance can be improved, and polishing performance such as polishing rate and flatness can be further improved.

[0051] The polishing pad has a diameter distribution of the pores based on the polishing surface, and the number average diameter (D a ) may be 15 μm to 50 μm, 15 μm to 30 μm, 15 μm to 25 μm, 15 μm to 23 μm, 15 μm to 21 μm, or 18 μm to 25 μm.

[0052] The above D a may be defined as the number average diameter of the pores, which is the average value obtained by dividing the sum of the pore diameters by the number of pores.

[0053] According to one embodiment, the polishing pad of the present invention has a D a If D is satisfied, the polishing rate and flatness can be improved. a If the thickness is less than 15 μm, the polishing rate when polishing an oxide film will be excessively high, or the polishing rate when polishing a tungsten film will be low, resulting in excessively low flatness. a If the thickness exceeds 50 μm, the polishing rate when polishing the tungsten film may become excessively high or the flatness may become excessively low.

[0054] Pores (A u ) are sometimes referred to as unusual pores in this specification, and their area ratio, A u (%) can be calculated using the following mathematical formula 4.

[0055] [Number 4] JPEG0007778859000007.jpg1772In the above mathematical formula 4, A t (μm 2 ) is the total measured area, and A u (μm 2 ) is the area of ​​pores having a diameter that is 200% or more larger than the number average diameter of the pores.

[0056] The above A u (%) can be 0.9% or more and less than 12%, 0.9% or more and less than 10%, 1% or more and less than 12%, 1% to 10%, 0.9% or more and less than 5%, 0.9% or more and less than 4%, 2% to 10%, 5% to 11%, or 6% to 11% of the total area of ​​the polishing surface. u (%), the overall pore uniformity can be satisfied, and the uniform polishing performance during the CMP process can also be improved. u If the A (%) of the polishing pad is in the above range, the uniformity of the pores may be impaired, which may make it difficult to achieve uniform polishing performance. As a result, the flatness of the tungsten film and the oxide film may be excessively deteriorated, and the polishing rate when polishing the oxide film may be reduced. u If it is less than (%), the polishing rate when polishing a tungsten film may be excessively reduced, and the polishing rate when polishing an oxide film may be excessively increased, which may adversely affect the polishing performance.

[0057] According to one implementation, the A u Diameter (D u ) is the number average diameter (D a ) is greater than twice the size of the D u can be calculated as in Equation 5 below.

[0058] [Number 5] D u >D a ×2 In the above mathematical formula 5, D uis the diameter of the pores that are 200% or more larger than the number average diameter of the pores, and D a is the number average diameter of the pores.

[0059] According to the implementation example, the D u The thickness can be 100 μm or more, specifically 100 μm to 150 μm.

[0060] The total area ratio of the plurality of pores (A p The area ratio (%) can be 30% to 55%, 35% to 55%, 35% to 53%, 35% to 50%, 35% to 45%, 45% to 55%, or 46% to 53% of the total area of ​​the polished surface, and can be calculated using the following mathematical formula 6.

[0061] [Number 6] JPEG0007778859000008.jpg1771In the above mathematical formula 6, A t (μm 2 ) is the total measured area, and A p (μm 2 ) is the total area of ​​the multiple pores.

[0062] On the other hand, the remaining pores (A n ) is sometimes referred to as normal pore in this specification, and its area ratio, A n (%) can be calculated using the following mathematical formula 7.

[0063] [Number 7] JPEG0007778859000009.jpg1772In the above mathematical formula 7, A t (μm 2 ) is the total measured area, and A n (μm 2 ) is the area of ​​the remaining pores excluding pores having a diameter 200% or more larger than the number average diameter of the multiple pores.

[0064] The above A n(%) may be 34% to 54%, 34% to 45%, 35% to 50%, more than 39% to less than 52%, or more than 39% to less than 50% of the total area of ​​the polishing surface.

[0065] Meanwhile, in the diameter distribution of the plurality of pores based on the polished surface, the maximum peak pore diameter may be 10 μm to 150 μm. The maximum peak pore diameter may be defined as the diameter of the pore having the highest ratio to the sum of the cross-sectional areas of pores having that diameter.

[0066] In the diameter distribution of the pores based on the polished surface, the maximum peak pore diameter may be, for example, 10 μm to 50 μm, for example, 15 μm to 40 μm, or for example, 17 μm to 30 μm.Furthermore, in the diameter distribution of the pores based on the polished surface, the maximum peak pore diameter may be, for example, 60 μm to 150 μm, specifically 60 μm to 100 μm.

[0067] According to one implementation example, D in Equations 1 to 3 q , D sk and D ku When the polished surface has a pore distribution that exhibits the above formula, the pore diameter of the maximum peak in the diameter distribution of the plurality of pores based on the polished surface may be, for example, 10 μm to 50 μm.

[0068] According to another embodiment, the number average diameter (D a ) is 15 μm to 50 μm, and the pores (A u ) is contained in an area ratio of 0.9% or more and less than 12% of the entire area of ​​the polished surface, the maximum peak pore diameter in the diameter distribution of the multiple pores based on the polished surface may be 60 μm to 150 μm.

[0069] The pore diameter of the maximum peak may be approximately 5 μm to 30 μm larger or smaller than the number average diameter of the pores, or approximately 10 μm to 20 μm larger or smaller than the number average diameter of the pores.

[0070] The above embodiment allows the diameter and distribution of the pores contained in the polishing pad to be adjusted, thereby adjusting the total area of ​​the pores per unit area of ​​the polishing surface within a specific range and the D q , D sk , and D ku and / or the number average diameter (D a ) and the area ratio of pores having a diameter 200% or more larger than the number average diameter of the plurality of pores, the polishing rate and flatness can be further improved.

[0071] The polishing pad may have a polishing rate of 600 Å / min to 900 Å / min when polishing a tungsten film, and a polishing rate of 2700 Å / min to 3300 Å / min when polishing an oxide film.

[0072] For example, the polishing pad has a total area of ​​pores per unit area of ​​the polishing surface in a specific range and D in the above mathematical formulas 1 to 3. q , D sk and D ku By satisfying the above range, the polishing rate and flatness can be further improved. Specifically, when polishing a tungsten film, the polishing pad can have a polishing rate of 720 Å / min to 860 Å / min, specifically 730 Å / min to 850 Å / min, more specifically 750 Å / min to 850 Å / min.

[0073] Furthermore, the polishing rate of the polishing pad when polishing an oxide film may be 2750 Å / min to 3300 Å / min, specifically 2800 Å / min to 3200 Å / min, more specifically 2900 Å / min to 3200 Å / min, or 2900 Å / min to 3150 Å / min.

[0074] Furthermore, in the case of polishing flatness (WIWNU: Within Wafer Non Uniformity), which indicates the polishing uniformity within the surface of a semiconductor substrate, e.g., a wafer, the flatness for a tungsten film may be less than 12%, e.g., less than 11%, e.g., less than 10%, e.g., less than 9%, e.g., less than 5%, 4.8% or less, or 4.5% or less.Furthermore, the flatness when polishing an oxide film may be 10% or less, e.g., less than 10%, e.g., less than 9%, e.g., less than 6%, e.g., less than 4.5%, less than 4.0%, or 3.8% or less.

[0075] On the other hand, the number average diameter (D a ), and by controlling the pores to have a diameter that is 200% or more larger than the number average diameter of the plurality of pores, the polishing rate and flatness can be further improved. Specifically, the polishing pad can have a polishing rate of 610 Å / min to 900 Å / min, 610 Å / min to 850 Å / min, 610 Å / min to 820 Å / min, or 615 Å / min to 800 Å / min when polishing a tungsten film.

[0076] Furthermore, the polishing rate of the polishing pad when polishing an oxide film may be 2860 Å / min to 3250 Å / min, 2900 Å / min to 3200 Å / min, or 2920 Å / min to 3200 Å / min.

[0077] Furthermore, in terms of polishing flatness (WIWNU), which indicates the polishing uniformity within the semiconductor substrate surface, the flatness of a tungsten film may be less than 10%, less than 9%, 4.5% or less, or less than 4.3%, and the flatness of an oxide film when polished may be less than 12%, less than 10%, less than 9%, less than 8%, less than 6%, less than 5%, or less than 4%.

[0078] The polishing pad may further comprise one or more reaction rate modifiers selected from the group consisting of tertiary amine compounds and organometallic compounds, and a silicone surfactant.

[0079] [Polishing pad manufacturing method] The method for manufacturing the polishing pad may include mixing a composition containing a urethane-based prepolymer, a curing agent, and a foaming agent, and injecting the composition into a mold under a predetermined pressure or reduced pressure to form a polishing layer.

[0080] According to one embodiment, a method for manufacturing the polishing pad includes: mixing a composition including a urethane-based prepolymer, a curing agent, and a foaming agent (Step 1); and molding the composition into a mold under a predetermined pressure condition to form a polishing layer (Step 2). The polishing layer includes a plurality of pores, and the polishing layer has a unit area (mm 2 The total area of ​​the pores per unit area is 40% to 60%, and the D q The value is 5 μm or more to 15 μm or less, and D is expressed by the above mathematical formula 2 sk The value is greater than 0.3 and less than 1, and D is represented by the above mathematical formula 3. ku The value is greater than 1 and less than 5.

[0081] Another embodiment of a method for manufacturing a polishing pad includes: mixing a composition including a urethane-based prepolymer, a curing agent, and a solid-phase foaming agent (Step 1); and forming a polishing layer by discharging and injecting the mixed composition into a mold under reduced pressure (Step 2), wherein the reduced pressure is a vacuum of 0.6 kgf / cm. 2 ~1kgf / cm 2 According to the above-described production method, the number average diameter of the pores and the pores having a diameter that is 200% or more larger than the number average diameter of the pores can be controlled by adjusting the reduced pressure conditions.

[0082] In addition, a method for manufacturing a polishing pad according to another embodiment includes the steps 1 and 2, and D of the mathematical formulas 1 to 3 is q , D sk , and D ku The pore distribution exhibits a number average diameter (D a ) and pores having a diameter that is 200% or more larger than the number average diameter of the plurality of pores can be controlled to fall within the above range.

[0083] According to an embodiment of the present invention, the physical properties of the pores can be adjusted by adjusting the contents of the urethane-based prepolymer, the curing agent, and the blowing agent. Specifically, in the manufacturing method, the type and content of the blowing agent, particularly the solid-phase blowing agent and / or the gas-phase blowing agent, the content of the reaction rate modifier, if necessary, and the pressure in the mold are adjusted to adjust the pore size, the number-average diameter of the pores, the total number of pores per unit area, and the total area of ​​the pores, thereby obtaining a D having the specific range. q , D sk , and D ku and / or the number-average diameter of multiple pores (D a ) and pores having a diameter that is 200% or more larger than the number average diameter of the plurality of pores, thereby improving the polishing characteristics such as the polishing rate and flatness of the polishing pad.

[0084] In addition, specific pores having a diameter 200% or more larger than the number average diameter of the plurality of pores may be unintentionally formed due to process instability, for example, due to improper control of pressure conditions resulting in excessive injection of pores, expansion of the solid foaming agent to an abnormal size, or the formation of open cells due to deformation of the solid foaming agent, etc. In some embodiments, the present invention can form the specific pores within an appropriate range by controlling the incorporation of air or bubbles through high-pressure injection and reduced-pressure discharge, and by appropriately adjusting the size of the solid foaming agent.

[0085] Specifically, a method for manufacturing the polishing pad according to one embodiment may include a step (first step) of mixing a composition including a urethane-based prepolymer, a curing agent, and a foaming agent.

[0086] The first step is a step of mixing the components to obtain a composition containing a mixture of a urethane-based prepolymer, a foaming agent, and a curing agent. The curing agent can be added together with the urethane-based prepolymer and the solid-phase foaming agent, or the urethane-based prepolymer and the solid-phase foaming agent can be mixed first, and then the curing agent can be mixed second.

[0087] As an example, the urethane-based prepolymer, the solid-phase blowing agent, and the curing agent may be added to the mixing process substantially simultaneously.

[0088] As another example, the urethane prepolymer and the solid-phase blowing agent may be mixed in advance, and then the curing agent may be added. That is, the curing agent does not have to be premixed into the urethane prepolymer. If the curing agent is premixed into the urethane prepolymer, it may be difficult to control the reaction rate, and the stability of the prepolymer, especially that having an isocyanate terminal group, may be significantly impaired.

[0089] The step of preparing the mixture involves mixing the urethane prepolymer and the curing agent to initiate a reaction and to evenly disperse the solid-phase blowing agent. Specifically, the mixing may be performed at a speed of 1,000 rpm to 10,000 rpm or 4,000 rpm to 7,000 rpm. This speed range may be more effective in evenly dispersing the solid-phase blowing agent in the raw materials.

[0090] The urethane prepolymer and curing agent may be mixed at a molar equivalent ratio of 1:0.8 to 1:1.2 or 1:0.9 to 1:1.1 based on the number of moles of reactive groups in each molecule. "Based on the number of moles of each reactive group" refers to, for example, the number of moles of isocyanate groups in the urethane prepolymer and the number of moles of reactive groups (amine groups, alcohol groups, etc.) in the curing agent. Therefore, the addition rate of the urethane prepolymer and curing agent may be adjusted so that the amounts added per unit time satisfy the molar equivalent ratio exemplified above, and they may be added at a constant rate during the mixing process. The individual specific components contained in the polishing pad will be described in detail below.

[0091] [Urethane prepolymer] A prepolymer generally refers to a polymer with a relatively low molecular weight whose polymerization degree has been stopped at an intermediate stage to facilitate molding in the production of a final molded product. A prepolymer can be molded by itself or after reacting with other polymerizable compounds. For example, a prepolymer can be prepared by reacting an isocyanate compound with a polyol.

[0092] The isocyanate compound used in preparing the urethane-based prepolymer may be, for example, one or more isocyanates selected from the group consisting of toluene diisocyanate (TDI), naphthalene-1,5-diisocyanate, p-phenylene diisocyanate, tolidine diisocyanate, 4,4′-diphenyl methane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate.

[0093] The polyol that can be used to prepare the urethane-based prepolymer can be, for example, one or more polyols selected from the group consisting of polyether polyol, polyester polyol, polycarbonate polyol, and acrylic polyol. The polyol can have a weight average molecular weight (Mw) of 300 g / mol to 3000 g / mol.

[0094] As described above, the urethane-based prepolymer can be prepared by reacting an isocyanate compound with a polyol. Specific types of the isocyanate compound and polyol are as exemplified for the polishing pad.

[0095] The urethane-based prepolymer may have a weight-average molecular weight (Mw) of 500 g / mol to 3000 g / mol. Specifically, the urethane-based prepolymer may have a weight-average molecular weight (Mw) of 600 g / mol to 2000 g / mol, or 800 g / mol to 1000 g / mol.

[0096] For example, the urethane-based prepolymer may be a polymer having a weight average molecular weight (Mw) of 500 g / mol to 3000 g / mol, which is obtained by polymerizing toluene diisocyanate as an isocyanate compound and polytetramethylene ether glycol as a polyol.

[0097] [Hardening agent] The curing agent may be one or more of an amine compound and an alcohol compound. Specifically, the curing agent may include one or more compounds selected from the group consisting of an aromatic amine, an aliphatic amine, an aromatic alcohol, and an aliphatic alcohol.

[0098] For example, the curing agent may be one or more selected from the group consisting of 4,4'-methylenebis(2-chloroaniline) (MOCA), diethyltoluenediamine, diaminodiphenylmethane, diaminodiphenylsulphone, m-xylylenediamine, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine, polypropylenetriamine, ethylene glycol, diethylene glycol, dipropylene glycol, butanediol, hexanediol, glycerine, and trimethylolpropane.

[0099] [Foaming agent] The foaming agent is a component for forming a pore structure in the polishing layer, and is not particularly limited as long as it is one that is commonly used to form pores in polishing pads.

[0100] For example, the foaming agent may be one or more selected from the group consisting of a solid-phase foaming agent having a hollow structure, a liquid-phase foaming agent using a volatile liquid, and an inert gas. Specifically, the foaming agent may include a gas-phase foaming agent, a solid-phase foaming agent, or both.

[0101] [Solid phase blowing agent] The solid-phase blowing agent may be a thermally expanded (size-adjusted) microcapsule, which may be a microballoon structure having an average particle size of 5 μm to 200 μm. The thermally expanded (size-adjusted) microcapsule may be obtained by thermally expanding a thermally expandable microcapsule.

[0102] The thermally expandable microcapsules may include an outer shell containing a thermoplastic resin and a blowing agent encapsulated inside the outer shell. The thermoplastic resin may be at least one selected from the group consisting of vinylidene chloride copolymers, acrylonitrile copolymers, methacrylonitrile copolymers, and acrylic copolymers. Furthermore, the encapsulated blowing agent may be at least one selected from the group consisting of hydrocarbons having 1 to 7 carbon atoms. Specifically, the encapsulated blowing agent may be ethane, ethylene, propane, propene, n-butane, isobutene, butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, or petroleum ether. The fluorocarbon may be selected from the group consisting of low molecular weight hydrocarbons such as fluorocarbon ether, chlorofluorohydrocarbons such as trichlorofluoromethane (CCl3F), dichlorodifluoromethane (CCl2F2), chlorotrifluoromethane (CClF3), and tetrafluoroethylene (CClF2-CClF2), and tetraalkylsilanes such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane.

[0103] According to one embodiment of the present invention, the solid foaming agent may have an average particle size (D50) of 20 μm to 50 μm. D50 refers to the volumetric particle size at the 50th percentile (median) of the particle size distribution. More specifically, the solid foaming agent may have a D50 of 25 μm to 48 μm. More specifically, the solid foaming agent may have a D50 of 25 μm to 40 μm, 28 μm to 40 μm, or 30 μm to 40 μm. When the D50 of the solid foaming agent satisfies the above range, the polishing rate and flatness can be further improved. If the D50 of the solid foaming agent is less than the above range, the number average diameter of the pores becomes small, which may affect the polishing rate and flatness. If the D50 of the solid foaming agent is greater than the above range, the number average diameter of the pores becomes excessively large, which may affect the polishing rate and flatness.

[0104] The standard deviation for the average particle size of the solid-phase blowing agent may be 15 or less, 13 or less, 11 or less, 7 to 11, or 7.5 to 10.4.

[0105] The solid-phase foaming agent may be used in an amount of 0.5 to 3 parts by weight based on 100 parts by weight of the urethane-based prepolymer.

[0106] Based on 100 parts by weight of the urethane-based prepolymer, the solid-phase blowing agent may be used in an amount of more than 0.5 parts by weight and less than 2.5 parts by weight, 0.6 parts by weight to 2.3 parts by weight, 0.8 parts by weight to 2 parts by weight, 0.8 parts by weight to 1.8 parts by weight, 1.0 parts by weight to 2.0 parts by weight, or 1.0 parts by weight to 1.5 parts by weight.

[0107] Alternatively, the solid-phase foaming agent may be used in an amount of 0.5 to 2.7 parts by weight, or 0.8 to 2.6 parts by weight, or 1.5 to 3 parts by weight, based on 100 parts by weight of the urethane-based prepolymer.

[0108] The solid-phase foaming agent may be fine hollow particles having a shell. The glass transition temperature (Tg) of the shell may be 70°C to 110°C, 80°C to 110°C, 90°C to 110°C, 100°C to 110°C, 70°C to 100°C, 70°C to 90°C, or 80°C to 100°C. When the glass transition temperature of the shell of the solid-phase foaming agent is within the preferred range, the pore distribution of the polishing surface can be achieved within the desired range by applying appropriate pressure and discharge conditions during the polishing pad manufacturing process to prevent deformation of the fine pores.

[0109] According to one embodiment of the present invention, the size (diameter) and pore size distribution of the pores having the above characteristics can be controlled by using only a solid-phase blowing agent without using a gas-phase blowing agent. In particular, the pore size distribution targeted in the present invention can be controlled by adjusting the type and content of the solid-phase blowing agent and / or the discharge rate and vacuum level when the composition is discharged and injected into a mold.

[0110] [Gas-phase blowing agent] The gas-phase blowing agent may include an inert gas, which may be added during the reaction of the urethane-based prepolymer, curing agent, solid-phase blowing agent, reaction rate modifier, and silicone-based surfactant to form pores. The inert gas may be any gas that does not participate in the reaction between the prepolymer and the curing agent. For example, the inert gas may be one or more selected from the group consisting of nitrogen gas (N), argon gas (Ar), and helium gas (He). Specifically, the inert gas may be nitrogen gas (N) or argon gas (Ar).

[0111] The inert gas may be added in a volume corresponding to 5% by volume to 30% by volume of the total volume of the composition (raw material mixture), specifically, the total volume of the urethane-based prepolymer, the foaming agent, the reaction rate modifier, the curing agent, and / or the surfactant.

[0112] Specifically, the inert gas may be added in an amount corresponding to more than 5 vol% to 20 vol% or more than 5 vol% to 18 vol%, specifically 6 vol% to 15 vol%, more specifically 6 vol% to 13 vol%, or 7.5 vol% to 10 vol% of the total volume of the composition.

[0113] Alternatively, the inert gas may be introduced in a volume corresponding to 6% to 25% by volume, specifically 8% to 25% by volume, of the total volume of the composition.

[0114] [Reaction rate adjuster] According to one embodiment of the present invention, the composition may include a reaction rate modifier.

[0115] The reaction rate regulator may be a reaction accelerator or a reaction retarder. Specifically, the reaction rate regulator may be a reaction accelerator, such as one or more reaction accelerators selected from the group consisting of tertiary amine compounds and organometallic compounds.

[0116] Specifically, the reaction rate modifier may include one or more selected from the group consisting of triethylenediamine, dimethylethanolamine, tetramethylbutanediamine, 2-methyl-triethylenediamine, dimethylcyclohexylamine, triethylamine, triisopropanolamine, 1,4-diazabicyclo(2,2,2)octane, bis(2-methylaminoethyl)ether, trimethylaminoethylethanolamine, N,N,N,N,N″-pentamethyldiethylenethalluriamine, dimethylaminoethylamine, dimethylaminopropylamine, benzyldimethylamine, N-ethylmorpholine, N,N-dimethylaminoethylmorpholine, N,N-dimethylcyclohexylamine, 2-methyl-2-azanorbornane, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, dioctyltin diacetate, dibutyltin maleate, dibutyltin di-2-ethylhexanoate, and dibutyltin dimercaptide. Specifically, the reaction rate adjuster may include one or more selected from the group consisting of benzyldimethylamine, N,N-dimethylcyclohexylamine, and triethylamine.

[0117] The reaction rate modifier may be used in an amount of 0.05 to 2 parts by weight based on 100 parts by weight of the urethane-based prepolymer.

[0118] Specifically, the reaction rate modifier may be used in an amount of more than 0.1 to 2 parts by weight, more than 0.1 to 1.8 parts by weight, specifically 0.3 to 1.8 parts by weight, more specifically 0.3 to less than 1.8 parts by weight, or 0.5 to 1.5 parts by weight, based on 100 parts by weight of the urethane prepolymer.

[0119] The reaction rate modifier may be used in an amount of 0.05 to 1.8 parts by weight, 0.05 to 1.7 parts by weight, 0.05 to 1.6 parts by weight, 0.1 to 1.5 parts by weight, 0.1 to 0.3 parts by weight, 0.2 to 1.8 parts by weight, 0.2 to 1.7 parts by weight, 0.2 to 1.6 parts by weight, 0.2 to 1.5 parts by weight, or 0.5 to 1 part by weight, based on 100 parts by weight of the urethane prepolymer.

[0120] When the reaction rate modifier is contained in an amount within the above range, the reaction rate (the time it takes for the mixture to solidify) of the mixture (e.g., a mixture of a urethane-based prepolymer, a curing agent, a solid-phase blowing agent, a reaction rate modifier, and a silicone-based surfactant) can be appropriately adjusted to form pores of the desired size.

[0121] [Surfactants] According to one embodiment of the present invention, the composition may include a surfactant. The surfactant serves to prevent pores from overlapping and clumping, and the type of surfactant is not particularly limited as long as it is a surfactant commonly used in the manufacture of polishing pads. For example, the surfactant may include a silicone-based surfactant. Commercially available silicone-based surfactants include B8749LF, B8736LF2, and B8734LF2 manufactured by Evonik.

[0122] The silicone surfactant may be included in an amount of 0.2 to 2 parts by weight based on 100 parts by weight of the urethane prepolymer. Specifically, the silicone surfactant may be included in an amount of 0.2 to 1.9 parts by weight, 0.2 to 1.8 parts by weight, 0.2 to 1.7 parts by weight, 0.2 to 1.6 parts by weight, 0.2 to 1.5 parts by weight, or 0.5 to 1.5 parts by weight based on 100 parts by weight of the urethane prepolymer. When the silicone surfactant is included in an amount within this range, pores derived from the gas-phase blowing agent can be stably formed and maintained in the mold.

[0123] [Reaction and Pore Formation] The urethane prepolymer and the curing agent are mixed and then reacted to form a solid polyurethane, which is then manufactured into a sheet or the like. Specifically, the isocyanate terminal group of the urethane prepolymer can react with the amine group, alcohol group, etc. of the curing agent. In this case, the gas-phase blowing agent and the solid-phase blowing agent containing an inert gas do not participate in the chemical reaction between the urethane prepolymer and the curing agent, and are physically dispersed evenly within the raw material to form a pore structure. The pore structure of the polishing pad can be determined by the pressure and / or discharge conditions during the polishing pad manufacturing process, which may cause a change in size of the solid-phase foaming agent, or by the penetration of external gas into the pores in the pore structure of the solid-phase foaming agent.

[0124] On the other hand, when a gas-phase foaming agent is used, the gas-phase foaming agent containing an inert gas also does not participate in the reaction between the urethane-based prepolymer and the curing agent, and is dispersed evenly within the raw material to form pores. The size of the pore structure formed by the gas-phase foaming can be adjusted by the pressure and / or discharge conditions during the manufacturing process of the polishing pad, which can affect the pore structure of the polishing pad.

[0125] Furthermore, when a reaction rate modifier is used, the reaction rate modifier adjusts the pore size by accelerating or delaying the reaction between the urethane-based prepolymer and the curing agent. For example, if the reaction rate modifier is a reaction retarder that delays the reaction, the pore size can be increased by increasing the time for the inert gas particles finely dispersed in the raw materials to combine. Conversely, if the reaction rate modifier is a reaction accelerator that accelerates the reaction, the pore size can be decreased by decreasing the time for the inert gas particles finely dispersed in the raw materials to combine.

[0126] Meanwhile, a method for manufacturing a polishing pad according to an embodiment of the present invention may include a step (second step) of forming a polishing layer by discharging and injecting the composition into a mold under a predetermined pressure or reduced pressure condition.

[0127] By adjusting the pressure or decompression conditions in the mold, the pore diameter, the number average diameter of the pores, the total number of pores per unit area, and the total area of ​​the pores are adjusted to obtain a D having the specific range. q , D sk and D ku value, and / or the number-average diameter of multiple pores (D a ) and pores having a diameter that is 200% or more larger than the number average diameter of the plurality of pores, thereby improving the polishing characteristics such as the polishing rate and flatness of the polishing pad.

[0128] In particular, pores having a diameter 200% or more larger than the number average diameter of the pores, i.e., specific pores, can be formed unintentionally due to process instability. In one embodiment, the present invention can further improve the performance of the polishing pad by forming the specific pores within an appropriate range by controlling the inclusion of air or bubbles through high-pressure injection and reduced-pressure discharge.

[0129] [Molding] FIG. 2 is a schematic diagram illustrating a molding process using a mold according to one implementation of the present invention.

[0130] Referring specifically to FIG. 2, the molding can be performed using a mold 100. Specifically, the raw material (composition) thoroughly mixed in a mixing head or the like can be discharged (b) into the mold to fill the interior of the mold. At this time, the discharge amount can be adjusted, which can affect the control of the specific pores. In addition, the specific pores can be formed within an appropriate range by controlling the incorporation of air or bubbles through high-pressure injection and reduced-pressure discharge (a), thereby further improving the performance of the polishing pad.

[0131] The discharge rate during the discharge (b) injection may be 5 kg / min to 20 kg / min, specifically 8 kg / min to 18 kg / min, more specifically 8 kg / min to 15 kg / min, or 10 kg / min to 12 kg / min. If the discharge rate exceeds this range, a large load may be applied, which may cause problems in the process. If the discharge rate is less than this range, the reaction between the urethane prepolymer and the curing agent may occur too quickly, resulting in easy solidification.

[0132] In addition, during the decompression and discharge (a), the degree of vacuum is 0.6 kgf / cm 2 ~1kgf / cm 2 Less than 0.6kgf / cm 2 ~0.9kgf / cm 2 , more specifically 0.7kgf / cm 2 ~0.9kgf / cm 2 The degree of vacuum plays an important role in controlling the pore size. That is, the decompression process removes air and bubbles that may cause large pores, thereby increasing the area ratio (A) of specific pores, which have a diameter 200% or more larger than the number average diameter of the multiple pores. u Therefore, when the pressure is reduced under the vacuum degree in the above range, A u (%) can be controlled so that the area ratio is within the range of 0.9% or more and less than 12%. If the degree of vacuum exceeds the above range, A u (%) becomes larger, and A n The initial polishing rate (%) becomes small, and when polishing a tungsten film, the initial polishing rate may be too high, and when polishing an oxide film, the initial polishing rate may be too low. In addition, the polishing performance may not be uniform, and the flatness of the tungsten film and the oxide film may decrease. In addition, when the degree of vacuum is below the above range, A u The polishing rate (%) becomes too low when polishing a tungsten film, and the initial polishing rate (%) becomes too high when polishing a tungsten film. In addition, the polishing performance is not uniform, and the flatness of the tungsten film and the oxide film may decrease.

[0133] The pressure inside the mold is 0.6 kgf / cm 2~1.2kgf / cm 2 The pressure inside the mold can be adjusted to 0.8 kgf / cm. 2 ~1.1kgf / cm 2 , 0.8kgf / cm 2 ~1.0kgf / cm 2 , 0.6kgf / cm 2 ~1.0kgf / cm 2 , 1.0kgf / cm 2 ~1.2kgf / cm 2 , or 0.9 kgf / cm 2 ~1.1kgf / cm 2 The pressure inside the mold may be, for example, 1 kgf / cm 2 This can be done under the following conditions.

[0134] If the pressure is 0.6 kgf / cm 2 If less than D q The value can be excessively large, 1.2 kgf / cm 2 If the number average diameter of the pores exceeds D q , D sk , and D ku This can affect the polishing characteristics, such as the polishing rate and flatness.

[0135] The reaction between the urethane prepolymer and the curing agent is completed in the mold, resulting in a cake-like molded product that is solidified according to the shape of the mold.

[0136] The resulting compact can then be appropriately sliced ​​or cut to form a polishing layer for the manufacture of a polishing pad. For example, after molding into a mold with a height 5 to 50 times the thickness of the polishing pad to be finally manufactured, the mold can be sliced ​​at equal thickness intervals to produce multiple polishing pad sheets. In this case, a reaction retarder can be used as a reaction rate adjuster to ensure sufficient solidification time. This allows the manufacture of a polishing layer even when the mold height is set to 5 to 50 times the thickness of the polishing pad to be finally manufactured. However, the polishing layer may have pores of different diameters depending on the position within the mold where it is molded. That is, a polishing layer molded at the bottom of the mold may have fine pores, while a polishing layer molded at the top of the mold may have pores of larger diameters than a sheet molded at the bottom.

[0137] Furthermore, to ensure that the polishing layer or each sheet has pores of uniform diameter, a mold capable of producing one sheet in a single molding operation may be used. Therefore, the height of the mold may not differ significantly from the thickness of the polishing pad to be finally manufactured. For example, the molding may be performed using a mold having a height corresponding to 1 to 3 times the thickness of the polishing pad to be finally manufactured. More specifically, the mold may have a height of 1.1 to 2.5 times, or 1.2 to 2 times the thickness of the polishing pad to be finally manufactured. In this case, a reaction accelerator may be used as a reaction rate adjuster to form pores of more uniform diameter.

[0138] Thereafter, the upper and lower ends of the molded body obtained from the mold can be cut off by, for example, 1 / 3 or less of the total thickness of the molded body, 1 / 22 to 3 / 10, or 1 / 12 to 1 / 4 of the total thickness of the molded body.

[0139] As a specific example, the molding may be performed using a mold having a height corresponding to 1.2 to 2 times the thickness of the polishing pad to be finally manufactured, and after the molding, the upper and lower ends of the molded body obtained from the mold may each be cut by 1 / 12 to 1 / 4 of the total thickness of the molded body.

[0140] After the surface cutting, the manufacturing method may further include a step of processing grooves in the surface, a step of bonding to a lower layer, a step of inspecting, a step of packaging, etc. These steps may be performed in the same manner as in a normal polishing pad manufacturing method.

[0141] [Polishing pad properties] As previously described, the polishing pad according to the embodiment is a polishing pad having a total pore area per unit area and a D in the above mathematical formulas 1 to 3. q , D sk and D ku When the pore distribution parameters including the above are within the above ranges, the polishing performance of the polishing pad, such as the polishing rate and flatness of the polishing pad, can be significantly improved.

[0142] Alternatively, the polishing pad according to the embodiment may be D a and A u When (%) is within the above range, uniform polishing performance can be achieved, and the polishing rate and flatness of the polishing pad can be significantly improved.

[0143] Alternatively, if the polishing pad according to the embodiment satisfies all of the above physical properties, the performance of the polishing pad may be further improved.

[0144] The polishing pad has a unit area (mm 2 The total number of pores per unit area (mm 2 ) of the polishing pad may be 600 or more. 2 The total number of pores per unit area (mm) of the polishing pad may be 700 or more, 750 or more, or 800 or more. 2 The total number of pores per unit area (mm) of the polishing pad may be 900 or more, but is not limited thereto. 2The total number of pores per unit area (mm) of the polishing pad may be 2500 or less, specifically 2200 or less, 1500 or less, or 1200 or less, but is not limited thereto. 2 The total number of pores per pore may be, but is not limited to, 700 to 2500, for example, 750 to 2200, 800 to 1500, or 800 to 1200.

[0145] Specifically, the polishing pad has an elastic modulus of 60 kgf / cm 2 More specifically, the elastic modulus of the polishing pad may be 100 kgf / cm or more. 2 The upper limit of the elastic modulus of the polishing pad is 150 kgf / cm or more, but is not limited thereto. 2 It can be, but is not limited to this.

[0146] Furthermore, the polishing pad according to the embodiment not only has excellent polishing performance, but also has excellent basic physical properties as a polishing pad, such as voltage resistance, specific gravity, surface hardness, tensile strength, and elongation.

[0147] The physical properties of the polishing pad, such as specific gravity and hardness, can be adjusted by the molecular structure of the urethane-based prepolymer polymerized by the reaction of isocyanate with polyol.

[0148] Specifically, the polishing pad may have a hardness of 30 Shore D to 80 Shore D. More specifically, the polishing pad may have a hardness of 40 Shore D to 70 Shore D, but is not limited thereto.

[0149] Specifically, the polishing pad has a density of 0.6 g / cm 3 ~0.9g / cm 3 More specifically, the polishing pad may have a specific gravity of 0.7 g / cm 3 ~0.85g / cm 3 The specific gravity of the cellulose may be, but is not limited to,

[0150] Specifically, the polishing pad has a resistance of 10 N / mm 2 ~100N / mm 2 More specifically, the polishing pad may have a tensile strength of 15 N / mm 2 ~70N / mm 2 Even more specifically, the polishing pad may have a tensile strength of 20 N / mm 2 ~70N / mm 2 The tensile strength of the adhesive may be, but is not limited to, 100 MPa.

[0151] Specifically, the polishing pad may have an elongation rate of 30% to 300%, and more specifically, the polishing pad may have an elongation rate of 50% to 200%.

[0152] The polishing pad has a withstand voltage of 14 kV to 23 kV, a thickness of 1.5 mm to 2.5 mm, and a specific gravity of 0.7 g / cm 3 ~0.9g / cm 3 The surface hardness at 25°C is 50 Shore D to 65 Shore D, and the tensile strength is 15 N / mm 2 ~25N / mm 2 The elongation rate can be, but is not limited to, 80% to 250%.

[0153] The polishing pad may have a thickness of 1 mm to 5 mm. Specifically, the polishing pad may have a thickness of 1 mm to 3 mm, 1 mm to 2.5 mm, 1.5 mm to 5 mm, 1.5 mm to 3 mm, 1.5 mm to 2.5 mm, 1.8 mm to 5 mm, 1.8 mm to 3 mm, or 1.8 mm to 2.5 mm. When the thickness of the polishing pad is within the above range, the basic physical properties of the polishing pad can be fully exhibited.

[0154] The polishing pad may have grooves on its surface for mechanical polishing, and the grooves may have a depth, width, and spacing appropriate for mechanical polishing, without particular limitation. A polishing pad according to an embodiment can simultaneously exhibit the physical properties of the polishing pad described above.

[0155] [Method of manufacturing semiconductor devices] A method for manufacturing a semiconductor device according to one embodiment includes polishing a surface of a semiconductor substrate using a polishing pad according to the embodiment.

[0156] That is, a method for manufacturing a semiconductor device according to one embodiment includes the steps of: attaching a polishing pad including a polishing layer including a plurality of pores to a platen; and polishing the surface of the wafer by rotating the polishing surface of the polishing layer relative to the surface of the wafer so that the polishing surface of the polishing layer and the surface of the wafer come into contact with each other; and the polishing layer has a surface area (mm ) of the polishing surface. 2 The total area of ​​the pores per unit area is 40% to 60%, and D q The value is 5 μm or more to 15 μm or less, and D is expressed by the above mathematical formula 2 sk The value is greater than 0.3 and less than 1, and D is represented by the above mathematical formula 3. ku The value can be greater than 1 and less than 5.

[0157] Another embodiment of a method for manufacturing a semiconductor device includes the steps of: attaching a polishing pad including a polishing layer including a plurality of pores to a platen; and polishing the surface of the wafer by rotating the polishing surface of the polishing layer relative to the surface of the wafer so that the polishing surface of the polishing layer and the surface of the wafer are brought into contact with each other; and polishing the surface of the wafer by rotating the polishing pad relative to the surface of the wafer so that the diameter distribution of the plurality of pores relative to the polishing surface is a number average diameter (D a ) is 15 μm to 50 μm, and the pores (A u ) may be contained in an area ratio of 0.9% or more and less than 12% of the total area of ​​the polishing surface.

[0158] In another embodiment, a method for manufacturing a semiconductor device includes the steps of: attaching a polishing pad including a polishing layer having a plurality of pores to a platen; and polishing the surface of the wafer by rotating the polishing surface of the polishing layer relative to each other so that the polishing surface of the polishing layer and the surface of the wafer come into contact with each other; and q , D sk and D ku and the number average diameter (D a ) and may have a diameter that is 200% or more larger than the number average diameter of the multiple pores.

[0159] 1 shows a schematic process of a semiconductor device manufacturing process according to one embodiment. Referring to FIG. 1, a polishing pad 110 according to one embodiment is mounted on a platen 120, and then a semiconductor substrate 130 is placed on the polishing pad 110. At this time, the surface of the semiconductor substrate 130 is in direct contact with the polishing surface of the polishing pad 110. For polishing, a polishing slurry 150 may be sprayed onto the polishing pad through a nozzle 140. The flow rate of the polishing slurry 150 supplied through the nozzle 140 is about 10 cm. 3 / min ~ approx. 1000cm 3 / min., can be selected depending on the purpose, for example, about 50 cm 3 / min ~ approx. 500cm 3 / min, but is not limited to this.

[0160] Thereafter, the semiconductor substrate 130 and the polishing pad 110 may rotate relative to each other to polish the surface of the semiconductor substrate 130. At this time, the rotation direction of the semiconductor substrate 130 and the rotation direction of the polishing pad 110 may be the same or opposite. The rotation speed of the semiconductor substrate 130 and the polishing pad 110 may be selected depending on the purpose within a range of about 10 rpm to about 500 rpm, and may be, for example, about 30 rpm to about 200 rpm, but is not limited thereto.

[0161] The semiconductor substrate 130 is attached to the polishing head 160 and pressed against the polishing surface of the polishing pad 110 with a predetermined load, and then the surface of the semiconductor substrate 130 is polished. The load applied by the polishing head 160 to the surface of the semiconductor substrate 130 and the polishing surface of the polishing pad 110 is about 1 gf / cm. 2 ~About 1000gf / cm 2 can be selected depending on the purpose within the range of, for example, about 10 gf / cm 2 ~About 800gf / cm 2 It can be, but is not limited to this.

[0162] In one embodiment, the method for manufacturing a semiconductor device may further include processing the polishing surface of the polishing pad 110 with a conditioner 170 simultaneously with polishing the semiconductor substrate 130 to maintain the polishing surface of the polishing pad 110 in a state suitable for polishing.

[0163] According to one embodiment, the size (diameter) and distribution of the pores contained in the polishing pad can be adjusted, so that the polishing pad has a specific range of total pore area per unit area and D in Equations 1 to 3. q , D sk and D ku The pore distribution shows the number average diameter (D a ) and by controlling the pores to have a diameter 200% or more larger than the number average diameter of the pores, polishing performance such as polishing rate and flatness can be further improved. Furthermore, by using the polishing pad, semiconductor devices with excellent quality can be efficiently manufactured.

[0164] (Example) The present invention will be described in more detail below with reference to examples. The following examples are merely illustrative of the present invention, and the scope of the present invention is not limited thereto.

[0165] (Example 1-1) In a casting machine equipped with a urethane-based prepolymer, a curing agent, an inert gas injection line, and a reaction rate modifier injection line, the prepolymer tank was filled with PUGL-550D (SKC) containing 9.1 wt% unreacted NCO, the curing agent tank was filled with 4,4'-methylenebis(2-chloroaniline) (MOCA, Ishihara), nitrogen (N) was used as the inert gas, and a reaction accelerator (Airproduct, product name: A1, a tertiary amine compound) was used as the reaction rate modifier. 100 parts by weight of the urethane-based prepolymer was premixed with 1 part by weight of a solid-phase blowing agent (AkzoNobel, product name: Expancel 461 DET 20 d40, average particle size: 32.67 μm) and 1 part by weight of a silicone-based surfactant (Evonik, product name: B8462), and then injected into the prepolymer tank.

[0166] The urethane prepolymer, curing agent, solid-phase blowing agent, reaction rate modifier, silicone surfactant, and inert gas were fed into the mixer at a constant rate through their respective feed lines. The molar equivalents of NCO groups in the urethane prepolymer and the molar equivalents of reactive groups in the curing agent were matched at a 1:1 ratio, and the total feed rate was maintained at 10 kg / min. The inert gas was fed at a constant volume of 10% of the total volume of the urethane prepolymer, curing agent, solid-phase blowing agent, reaction rate modifier, and silicone surfactant. The reaction rate modifier was fed in an amount of 0.5 parts by weight per 100 parts by weight of the urethane prepolymer.

[0167] The stirred raw material was poured into a mold (1000mm long, 1000mm wide, 3mm high) at a discharge rate of 10kg / min and a pressure of 1.0kgf / cm inside the mold. 2 The reaction was terminated to obtain a porous polyurethane molded body. The surface of the prepared porous polyurethane molded body was then ground using a grinding machine and grooved using a tip, and the average thickness was adjusted to 2 mm.

[0168] The porous polyurethane layer and the substrate layer (average thickness: 1.1 mm) were heat-sealed at 120° C. using a hot melt film (SKC Corporation, product name: TF-00) to produce a polishing pad.

[0169] (Example 1-2) A polishing pad was manufactured in the same manner as in Example 1-1, except that the contents of the reaction rate modifier, gas phase blowing agent, and solid phase blowing agent were adjusted as shown in Table 1 below.

[0170] (Examples 1-3) In the casting apparatus of Example 1-1, the inert gas injection line and the reaction rate modifier injection line were shut off. The prepolymer tank was filled with PUGL-600D (SKC Corporation, weight average molecular weight: 1500 g / mol) having 9.1 NCO%, and the curing agent tank was filled with 4,4'-methylenebis(2-chloroaniline) (TCI (Tokyo Chemical Industry)).

[0171] Furthermore, 100 parts by weight of the urethane-based prepolymer was mixed with 1.5 parts by weight of a solid-phase blowing agent (manufactured by AkzoNobel, product name: Expancel 551 DE 40 d42, average particle size: 40 μm) in advance, and then poured into the prepolymer tank.

[0172] The urethane prepolymer and curing agent mixed with the solid-phase blowing agent were fed into a mixing head at a constant rate through their respective feed lines while being stirred. The rotation speed of the mixing head was approximately 5000 rpm. The molar equivalents of the NCO groups in the urethane prepolymer and the molar equivalents of the reactive groups in the curing agent were matched at a 1:1 ratio, and the total feed rate was maintained at 10 kg / min.

[0173] The stirred raw material was poured into a mold (1000mm long, 1000mm wide, 3mm high) at a discharge rate of 10kg / min and a pressure of 0.8kgf / cm inside the mold. 2The reaction was terminated to obtain a porous polyurethane molded body. The surface of the prepared porous polyurethane molded body was then ground with a grinding machine and grooved with a tip, and the average thickness was adjusted to 2 mm.

[0174] The porous polyurethane layer and the substrate layer (average thickness: 1.1 mm) were heat-sealed at 120° C. using a hot melt film (manufacturer: SKC, product name: TF-00) to produce a polishing pad.

[0175] (Examples 1-4) A polishing pad was manufactured in the same manner as in Examples 1-3, except that the content of the solid-phase foaming agent and the vacuum pressure in the mold were adjusted as shown in Table 1 below.

[0176] Example 2-1 In a casting machine equipped with a urethane prepolymer, a curing agent, an inert gas injection line, and a reaction rate modifier injection line, the prepolymer tank was filled with PUGL-600D (SKC Corporation, weight average molecular weight: 1500 g / mol) having 9.1 NCO%, the curing agent tank was filled with 4,4'-methylenebis(2-chloroaniline) (TCI Corporation), and nitrogen (N2) was prepared as the inert gas. Furthermore, triethylenediamine (TEDA) from Sigma-Aldrich was used as the reaction rate modifier.

[0177] Furthermore, 100 parts by weight of the urethane-based prepolymer was mixed with 1 part by weight of a solid-phase blowing agent (AkzoNobel, product name: Expancel 461 DET 20 d40, average particle size: 40 μm) and 0.5 parts by weight of a silicone surfactant (Evonik, product name: B8462), and the resulting mixture was poured into a prepolymer tank.

[0178] The urethane prepolymer, curing agent, reaction rate modifier, and inert gas were fed into the mixing head at a constant rate through their respective feed lines while being stirred. The rotation speed of the mixing head was approximately 5000 rpm. The molar equivalent of the NCO group in the urethane prepolymer and the molar equivalent of the reactive group in the curing agent were adjusted to a ratio of 1:1, and the total feed rate was maintained at 10 kg / min. The inert gas was added to the mixing head at a rate of 10 kg / min to achieve a target specific gravity of 0.8 g / cm for the polyurethane sheet. 3 The temperature was set at 100°C, and the urethane prepolymer, curing agent, solid-phase blowing agent, reaction rate modifier, and silicone surfactant were added in an amount of 21% by volume of the total volume, and the reaction rate modifier was added in an amount of 0.5 parts by weight based on 100 parts by weight of the urethane prepolymer.

[0179] The stirred raw material was poured into a mold (1000mm long, 1000mm wide, 3mm high) at a discharge rate of 10kg / min and a vacuum of 0.8kgf / cm 2 The reaction was terminated to obtain a solid cake-like molded product, and the upper and lower ends of the molded product were then cut off by 0.5 mm to obtain an upper pad having a thickness of 2 mm.

[0180] The upper pad was then subjected to surface milling and groove forming processes, and laminated to the lower pad with a hot melt adhesive to produce a polishing pad.

[0181] (Example 2-2) As shown in Table 2 below, a polishing pad was produced in the same manner as in Example 2-1, except that the discharge rate was adjusted to 12 kg / min.

[0182] (Example 2-3) As shown in Table 2 below, the discharge rate was set to 12 kg / min and the vacuum level to 0.7 kgf / cm 2 A polishing pad was produced in the same manner as in Example 2-1, except that the pH was adjusted to 1.

[0183] (Examples 2-4) As shown in Table 2 below, the discharge rate was set to 10 kg / min and the vacuum level to 0.9 kgf / cm 2A polishing pad was produced in the same manner as in Example 2-1, except that the pH was adjusted to 1.

[0184] (Examples 2-5) In the casting apparatus of Example 2-1, the inert gas injection line and the reaction rate modifier injection line were shut off. The prepolymer tank was filled with PUGL-600D (SKC Corporation, weight average molecular weight: 1500 g / mol) having 9.1 NCO%, and the curing agent tank was filled with 4,4'-methylenebis(2-chloroaniline) (TCI Corporation).

[0185] Furthermore, 100 parts by weight of the urethane-based prepolymer was mixed with 1.5 parts by weight of a solid-phase blowing agent (AkzoNobel, product name: Expancel 551 DE 40 d42, average particle size: 40 μm) in advance, and then poured into the prepolymer tank.

[0186] The urethane prepolymer and curing agent mixed with the solid-phase blowing agent were fed into a mixing head at a constant rate through their respective feed lines while being stirred. The rotation speed of the mixing head was approximately 5000 rpm. The molar equivalents of the NCO groups in the urethane prepolymer and the molar equivalents of the reactive groups in the curing agent were matched at a 1:1 ratio, and the total feed rate was maintained at 10 kg / min.

[0187] The stirred raw material was poured into a mold (1000mm long, 1000mm wide, 3mm high) at a discharge rate of 10kg / min and a vacuum of 0.8kgf / cm 2 The reaction was terminated to obtain a solid cake-like molded product, and the upper and lower ends of the molded product were then cut off by 0.5 mm to obtain an upper pad having a thickness of 2 mm.

[0188] The upper pad was then subjected to surface milling and groove forming processes and laminated to the lower pad with a hot melt adhesive to produce a polishing pad.

[0189] (Comparative Examples 1-1 to 1-8) A polishing pad was manufactured in the same manner as in Example 1-1, except that the vacuum pressure in the mold, the content of the reaction rate modifier, the gas phase foaming agent, and the solid phase foaming agent were adjusted as shown in Table 1 below.

[0190] (Comparative Examples 1-9 and 1-10) A polishing pad was manufactured in the same manner as in Examples 1-3, except that the content of the solid-phase foaming agent and the vacuum pressure in the mold were adjusted as shown in Table 1 below.

[0191] (Comparative Example 2-1) A polishing pad was manufactured in the same manner as in Example 2-1, except that the degree of vacuum was adjusted to normal pressure as shown in Table 2 below.

[0192] (Comparative Example 2-2) As shown in Table 2 below, the discharge rate was set to 12 kg / min and the vacuum level to 0.5 kgf / cm 2 A polishing pad was produced in the same manner as in Example 2-5, except that the pH was adjusted to 1.

[0193] (Comparative Example 2-3) A polishing pad was manufactured in the same manner as in Example 2-5, except that the degree of vacuum was adjusted to normal pressure as shown in Table 2 below.

[0194] (Test example) (1) Stomatal characteristics <Number average diameter of multiple pores and total area of ​​pores per unit area> The polishing pad was cut into 1mm x 1mm squares (thickness: 2mm). 2 The cross section of the polished surface was observed from an image magnified 100 times using a scanning electron microscope (SEM).

[0195] Using image analysis software, the diameter of all pores was measured from the obtained images, and the number-average diameter of pores, the distribution of the sum of the cross-sectional areas by pore size, the number of pores, and the total area of ​​pores were obtained.

[0196] - Ratio of the sum of the cross-sectional areas of the pores: This was created by classifying the pores in 1 μm units from the SEM images. - number mean diameter (D a ): Polished surface 1mm 2 The average value obtained by dividing the sum of the multiple pore diameters by the number of multiple pores - Number of pores: Unit area (mm 2 ) Total number of pores per - Unit area (mm 2 ) Total pore area per (%): Percentage of the area of ​​pores only to the total area of ​​the SEM image

[0197] 3 and 4 are scanning electron microscope (SEM) images of pores in the polishing pad of Example 1-1 and 1 mm pores in the polishing pad of Example 1-1, respectively. 2 3 and 4 are SEM images of the polishing surface of Example 1-1 enlarged 100 times. As can be seen from Fig. 3 and Fig. 4, it was confirmed that the polishing pad of Example 1-1 exhibited a uniform pore distribution.

[0198] In the case of the polishing pad of Example 2-1, pores having diameters 200% or more larger than the number average diameter of the pores were controlled, and it was confirmed that the pores exhibited a uniform distribution, similar to Figures 3 and 4.

[0199] <Pores with a diameter 200% or more larger than the number-average diameter of multiple pores (A u ) area ratio (A u (%))> A u (%) can be calculated using the following mathematical formula 4.

[0200] [Number 4] JPEG0007778859000010.jpg1772In the above mathematical formula 4, A t (μm 2 ) is the total measured area, and A u (μm 2 ) is the area of ​​pores having a diameter that is 200% or more larger than the number average diameter of the pores.

[0201] <Total area ratio of multiple pores (A p (%))> A p (%) can be calculated using the following mathematical formula 6.

[0202] [Number 6] JPEG0007778859000011.jpg1771In the above mathematical formula 6, A t (μm 2 ) is the total measured area, and A p (μm 2 ) is the total area of ​​the multiple pores.

[0203] <The remaining pores (A n ) area ratio (A n (%))> A n (%) can be calculated using the following mathematical formula 7.

[0204] [Number 7] JPEG0007778859000012.jpg1772In the above mathematical formula 7, A t (μm 2 ) is the total measured area, and A n (μm 2 ) is the area of ​​the remaining pores excluding pores having a diameter 200% or more larger than the number average diameter of the multiple pores.

[0205] (2) Polishing rate of tungsten film and oxide film A 300 mm diameter silicon wafer with a tungsten (W) film formed by a CVD process was placed in a CMP polishing system. The silicon wafer was then placed with the tungsten film facing down on the platen equipped with the polishing pad. The polishing load was then adjusted to 2.8 psi, and calcined silica slurry was dispensed onto the polishing pad at a rate of 190 ml / min while the platen was rotated at 115 rpm for 30 seconds to polish the tungsten film. After polishing, the silicon wafer was removed from the carrier and placed in a spin dryer, where it was rinsed with purified water (DIW) and air-dried for 15 seconds. The difference in thickness of the dried silicon wafer before and after polishing was measured using a contact-type surface resistance measurement device (four-point probe). The polishing rate was then calculated using the following mathematical formula 8.

[0206] [Number 8] Polishing rate (Å / min) = difference in thickness before and after polishing (Å) / polishing time (min)

[0207] In addition, using the same equipment, instead of a silicon wafer on which a tungsten film was formed, a silicon oxide (SiO x A 300 mm diameter silicon wafer with a silicon oxide film formed thereon was placed on the platen with the polishing pad attached, with the silicon oxide film facing down. The polishing load was then adjusted to 1.4 psi, and calcined silica slurry was dispensed onto the polishing pad at a rate of 190 ml / min while the platen was rotated at 115 rpm for 60 seconds to polish the silicon oxide film. After polishing, the silicon wafer was removed from the carrier, placed in a spin dryer, rinsed with purified water (DIW), and air-dried for 15 seconds. The difference in thickness of the dried silicon wafer before and after polishing was measured using a spectral interference wafer thickness gauge (Keyence Corporation, Model SI-F80R). The polishing rate was then calculated using Equation 8.

[0208] (3) Flatness of tungsten film and oxide film A silicon wafer on which a tungsten film was formed, obtained by the same method as in Experimental Example (2), and a silicon oxide (SiO x Each silicon wafer having a 1 μm (10,000 Å) thermal oxide film was polished for 1 minute under the above-mentioned polishing conditions, and the in-plane film thickness of the wafer was measured at 98 points. The within-wafer non-uniformity (WIWNU) was calculated based on the following mathematical formula 9.

[0209] [Number 9] Polishing flatness (WIWNU) (%) = (standard deviation of polished thickness / average polished thickness) x 100 (%)

[0210] The physical properties of the polishing pads produced in Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-10 were measured according to the conditions of the test examples, and the results are shown in Table 1 below.

[0211] [Table 1]

[0212] As shown in Table 1, in Examples 1-1 to 1-4, the total area of ​​pores per unit area of ​​the polished surface and D in Equations 1 to 3 q , D sk and D ku The polishing pads whose values ​​all fell within the ranges of the present invention showed significantly superior polishing rates and flatness for tungsten films and oxide films compared to Comparative Examples 1-1 to 1-10.

[0213] Specifically, the polishing pads of Examples 1-1 and 1-4 had polishing rates for tungsten films and oxide films in the ranges of 750 Å / min to 815 Å / min and 2850 Å / min to 3150 Å / min, respectively, and excellent flatness for tungsten films and oxide films of 4.5% or less, respectively.

[0214] In contrast, the polishing pad of Comparative Example 1-1, in which the total area of ​​pores per unit area of ​​the polishing surface was less than 40%, had a polishing rate for tungsten films and oxide films of 620 Å / min and 2215 Å / min, respectively, which was significantly lower than the polishing pads of Examples 1-1 to 1-4.

[0215] On the other hand, the polishing pad of Comparative Example 1-2, in which the total area of ​​pores per unit area of ​​the polishing surface exceeds 60%, has a flatness of 12.5% ​​for the tungsten film, which is significantly lower than the flatness of the polishing pad of Example 1-2 for the tungsten film. Furthermore, the polishing rate for the tungsten film was 950 Å / min, which is too high compared to the polishing pads of Examples 1-1 to 1-4, but the polishing rate for the oxide film was 2705 Å / min, which is very low.

[0216] On the other hand, D q The polishing pad of Comparative Example 1-3, which has a value of less than 5 μm, has a polishing rate of 711 Å / min when polishing a tungsten film, which is lower than that of the polishing pads of Examples 1-1 to 1-4, and the flatness of the oxide film is 10.2%, which is significantly lower than that of the polishing pads of Examples 1-1 and 1-2.

[0217] D q The polishing pad of Comparative Example 1-4, which had a value of more than 15 μm, had a polishing rate of 920 Å / min when polishing a tungsten film, which was excessively increased compared to the polishing pads of Examples 1-1 to 1-4, and showed poor flatness for tungsten films and oxide films of 10.5% and 7.5%, respectively, compared to Examples 1-1 to 1-4.

[0218] Also, D sk The polishing pads of Comparative Examples 1-5, which have a value of 0.3 or less, have a low removal rate when polishing a tungsten film, and sk The polishing pad of Comparative Example 1-6, which had a value of 1 or more, showed an excessive increase in polishing rate when polishing a tungsten film, and the flatness of the tungsten film and oxide film was significantly lower than that of the polishing pads of Examples 1-1 to 1-4.

[0219] On the other hand, D ku The polishing pads of Comparative Examples 1-7, which have a value of 1 or less, have a low removal rate when polishing a tungsten film, and ku It can be seen that the polishing pads of Comparative Examples 1-8, which have a value of 5 or more, are significantly reduced in both physical properties, that is, the removal rate and flatness, for the tungsten film and the oxide film.

[0220] In addition, it was confirmed that the polishing pads of Examples 1-3 and 1-4 can effectively improve the polishing rate and flatness by adjusting the vacuum pressure and the amount of solid-phase foaming agent added, even without using a reaction rate adjuster and a gas-phase foaming agent.

[0221] In contrast, the polishing pads of Comparative Examples 1-9 and 1-10, which do not use a reaction rate modifier or a gas-phase foaming agent like the polishing pads of Examples 1-3 and 1-4, have a total pore area per unit area and a D q The values ​​were outside the range of the present invention, and in this case, the polishing rate and flatness were significantly deteriorated.

[0222] Therefore, not only the total area of ​​pores per unit area of ​​the polished surface but also the D q , D sk and D ku It is clear that even if any one of the parameters is out of the range of the present invention, it will have a large effect on the polishing performance in terms of the polishing rate and flatness.

[0223] The polishing pads produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3 were measured for their physical properties under the conditions of the above-mentioned Test Examples, and the results are shown in Table 2 below.

[0224] [Table 2]

[0225] As shown in Table 2, Examples 2-1 to 2-5 are D ais in the range of 15μm to 50μm, and A u It was confirmed that D (%) was in the range of 0.9% or more and less than 12% of the total area of ​​the polished surface. a and A u (%) was satisfied, the polishing rate and flatness of the tungsten film and oxide film were significantly superior to those of Comparative Examples 2-1 to 2-3.

[0226] Specifically, the polishing pads of Examples 2-1 to 2-5 had polishing rates for tungsten films and oxide films in the ranges of 615 Å / min to 810 Å / min and 2910 Å / min to 3151 Å / min, respectively, and the flatness for tungsten films and oxide films was superior to that of the polishing pads of Comparative Examples 2-1 to 2-3.

[0227] In contrast, A u In the case of the polishing pad of Comparative Example 2-1, where the polishing rate and flatness of the oxide film are 2854 Å / min and 12.9%, respectively, the polishing rate and flatness are significantly lower than those of the examples, and in particular, the flatness of the tungsten film and oxide film is about 3.5 times lower than that of the polishing pad of Example 2-2. This is because, compared to Example 2-1, by adjusting the vacuum to normal pressure, A u It can be expected that the percentages will fall outside the scope of the present invention.

[0228] On the other hand, D a In the case of the polishing pads of Comparative Examples 2-2 and 2-3, where the value of (μm) is less than 15 μm, A u Even if (%) satisfies the range of the present invention, D a It can be seen that the flatness of the oxide film is significantly lower than that of the examples because the (μm) value is too low. This is because, compared to examples 2-5, the degree of vacuum is adjusted too low or adjusted to normal pressure, resulting in a decrease in the D a It is expected that (μm) values ​​will fall outside the scope of the present invention.

[0229] On the other hand, in the case of the polishing pad of Example 2-5, even without using a gas phase foaming agent, a surfactant, and a reaction rate modifier, by adjusting the discharge amount and the degree of vacuum, D within the scope of the present invention was obtained. a (μm) value and A u (%), and it was confirmed that both the polishing rate and flatness were within the appropriate range.

[0230] Therefore, it was found that satisfactory polishing performance can be achieved even when using only a solid-phase foaming agent without using a gas-phase foaming agent by controlling the content thereof, the amount of foaming agent discharged when the composition is discharged and injected into a mold, and the degree of vacuum. [Explanation of symbols]

[0231] 100: Mold a: Decompression discharge b: Discharge 110: Polishing pad 120: Platen 130: Semiconductor substrate 140: Nozzle 150: Polishing slurry 160: Polishing head 170: Conditioner

Claims

1. a polishing layer comprising a plurality of pores; The diameter distribution of the pores based on the polished surface is The number average diameter (D ａ ) is 15 μm to 50 μm, Pores having a diameter that is 200% or more larger than the number average diameter of the plurality of pores (A ｕ ) is contained in an area ratio of 0.9% or more and less than 12% of the total area of ​​the polishing surface.

2. the polishing layer comprises a cured product of a composition comprising a urethane-based prepolymer, a curing agent, and a solid-phase foaming agent; the solid phase blowing agent has a D50 of 20 μm to 50 μm; or 2. The polishing pad according to claim 1, wherein the solid-phase foaming agent is a fine hollow particle having a shell, and the glass transition temperature (Tg) of the shell is 70°C to 110°C.

3. 2. A method for manufacturing the polishing pad according to claim 1, comprising: mixing a composition including a urethane-based prepolymer, a curing agent, and a blowing agent; and a step of discharging and injecting the composition into a mold under a predetermined pressure or reduced pressure condition to form the polishing layer.

4. the blowing agent comprises a solid-phase blowing agent or comprises both a gas-phase blowing agent and a solid-phase blowing agent; the solid-phase blowing agent has an average particle size (D50) of 20 μm to 50 μm; 4. The method for producing a polishing pad according to claim 3, wherein the composition contains the solid-phase foaming agent in an amount of more than 0.5 parts by weight and less than 2.5 parts by weight per 100 parts by weight of the urethane-based prepolymer.

5. The reduced pressure is a vacuum of 0.6 kgf / cm ２ ~1 kgf / cm ２ The method for producing a polishing pad according to claim 3 , wherein the polishing pad is produced by heating at a rate of 1000 kJ / min or more.

6. 10. A method for manufacturing a semiconductor device using the polishing pad according to claim 1, mounting the polishing pad, the polishing pad including a polishing layer containing a plurality of pores, on a platen; and rotating the polishing surface of the polishing layer and the surface of the wafer relative to each other so that the polishing surface and the surface of the wafer come into contact with each other, thereby polishing the surface of the wafer.

Images