Polishing pad having improved slurry flowability and method of manufacturing semiconductor device using same

Abstract

According to the polishing pad provided by the embodiment of the invention, in addition to the first grooves in the concentric form, the second grooves in the radial form, which are specially designed, are adopted, so that the flowability of slurry can be improved, and the wafer curve and the polishing rate can be changed.

Description

Technical Field

[0001] Embodiments of the present invention relate to a polishing pad for use in a chemical mechanical planarization (CMP) process of a semiconductor device. Specifically, they relate to a polishing pad having improved slurry flowability and a method of manufacturing a semiconductor device using the same. Background Art

[0002] The chemical mechanical planarization (CMP) process in the semiconductor preparation method refers to fixing a semiconductor substrate such as a wafer on a head and contacting it with the surface of a polishing pad mounted on a pressure plate, and then chemically treating the surface of the semiconductor substrate by providing a slurry while the pressure plate and the head are moving relative to each other, thereby mechanically planarizing the irregular parts of the surface of the semiconductor substrate.

[0003] The polishing pad is an important component that plays an important role in such a CMP process. Generally, the polishing pad is made of polyurethane resin and has grooves for large flow slurry and holes for supporting small flow on its surface.

[0004] In order to prepare such a polishing pad, diisocyanate and polyol are reacted to obtain a prepolymer, which is mixed with a curing agent and a foaming agent and then cured to obtain a polyurethane foam sheet. Thereafter, the upper and lower surfaces of the polyurethane foam sheet are cut to a desired thickness to obtain a top pad, a groove of a specific shape is formed on the surface of the top pad using a tip or the like, and then it is bonded to a polyurethane bottom pad to prepare a polishing pad.

[0005] The grooves may have various shapes. For example, the grooves may have a circular shape with a shared center (see Korean Patent Publication No. 2005-0095818). The grooves provided on the polishing pad are used to assist in the flattening of the wafer surface by carrying the slurry while allowing the slurry to flow.

[0006] Prior art literature

[0007] (Patent Document 1) Korean Patent Publication No. 2005-0095818. Summary of the invention

[0008] Technical issues

[0009] The polishing pad in the CMP process removes film materials while polishing the wafer surface. The fluidity of the slurry varies depending on the type of slurry and film materials, resulting in variations in polishing rate and wafer within wafer non-uniformity (WIWNU) values. The wafer profile is modified by adjusting process conditions, which consumes time and materials.

[0010] As a result of studies conducted by the present inventors, it has been found that if specially designed radial grooves are used in addition to concentric grooves, the flowability of the slurry can be improved, and the wafer curve and the polishing rate can be changed.

[0011] Therefore, an object of embodiments of the present invention is to provide a polishing pad having improved slurry fluidity and polishing rate, and a method of manufacturing a semiconductor device using the polishing pad.

[0012] Solution to the problem

[0013] According to an embodiment for achieving the above-mentioned purpose, a polishing pad is provided, which includes a polishing layer having a polishing surface, wherein the polishing layer includes a plurality of first grooves, the first grooves having a circular shape and sharing the center of the polishing surface; and a plurality of second grooves, the second grooves being radially formed outward from positions at a distance from the center of 10% to 90% of the radius of the polishing surface, and when a silicon oxide layer of a silicon wafer is polished on the polishing surface using a cerium dioxide slurry and the polishing rate is measured at 30 or more random positions, the within-wafer non-uniformity (WIWNU) calculated by the following equation is 15% or less.

[0014]

[0015] Here, RR_stdev is the polishing rate The standard deviation of the measured values, and RR_avg is the polishing rate The average of the measurements.

[0016] According to yet another embodiment, there is provided a method of manufacturing a semiconductor device, which includes polishing a surface of a semiconductor substrate using a polishing pad.

[0017] Beneficial effects of the present invention

[0018] Since the polishing pad according to the embodiment of the present invention adopts specially designed second grooves in radial form in addition to the first grooves in concentric form, the fluidity of the slurry can be improved, and the wafer curve and the polishing rate can be changed.

[0019] In particular, the use of the second grooves can improve the fluidity of the CMP slurry, thereby changing the polishing rate of the central area of ​​the wafer and the wafer curve, thereby reducing the WIWNU value and increasing the life of the polishing pad.

[0020] Therefore, the polishing pad according to the present embodiment of the present invention can be used in the manufacture of semiconductor devices to improve process efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a plan view of a polishing pad according to an embodiment.

[0022] Figure 2 A method of manufacturing a semiconductor device using a polishing pad according to an embodiment is described.

[0023] Figure 3 is along Figure 1 2 is a cross-sectional view of the polishing layer including the first groove taken along the line A1-A1' in FIG.

[0024] Figure 4 is along Figure 1 A cross-sectional view of the polishing layer including the second groove taken along line A2-A2' in FIG.

[0025] Figure 5 Wafer profiles after a CMP process using the polishing pads obtained in Examples 1 to 3 and Comparative Examples 1 and 2 are shown.

[0026] <Description of Reference Numerals>

[0027] 100: polishing layer, 101: polishing surface,

[0028] 200: support layer, 300: adhesive layer,

[0029] 110: first groove, 120: second groove, 130: third groove,

[0030] 111, 121: inner side, 112, 122: bottom side,

[0031] h1: the depth of the first groove, h2: the depth of the second groove,

[0032] w1: the width of the first groove, w2: the width of the second groove,

[0033] t: thickness of the polishing layer, p: spacing of the first grooves,

[0034] A1-A1', A2-A2': cutting line,

[0035] 400: polishing pad, 500: pressing plate, 600: conditioning agent, 700: polishing slurry,

[0036] 810: polishing head, 820: carrier, 900: semiconductor substrate (wafer) DETAILED DESCRIPTION

[0037] Best Mode for Carrying Out the Invention

[0038] In the following description of the embodiment, when it is determined that the description may make the subject matter of the embodiment rather unclear, a detailed description of known functions and configurations incorporated herein will be omitted. In addition, for ease of description, the size of each element in the drawings may be exaggerated or omitted, and they may be different from the actual size.

[0039] In this specification, when a component is described as being formed above / below another component or connected or coupled to each other, it covers the case where these components are formed, connected or coupled directly or indirectly through another component. In addition, it should be understood that the criteria of the top and bottom of each component may vary depending on the direction of the object being observed.

[0040] In the present specification, the terms related to each component are used to distinguish them from each other, and are not intended to limit the scope of the embodiments. In addition, in the present specification, singular expressions are also interpreted as covering the plural, unless otherwise specified in the context.

[0041] Throughout this specification, the terms first, second, etc. are used to describe various components. However, these components should not be limited by these terms. These terms are used to distinguish one element from another.

[0042] In this specification, the term "comprising" is intended to specify a feature, region, step, process, element and component. Unless otherwise specifically stated, the existence or addition of any other features, regions, steps, processes, elements and components is not excluded.

[0043] For convenience, the molecular weight of the compound or polymer described in this specification is expressed in molar mass units, but it can be understood as a relative mass relative to carbon 12. In addition, the molecular weight of the compound or polymer described in this specification can be interpreted as a number average molecular weight or a weight average molecular weight, for example, as a number average molecular weight.

[0044] In the numerical ranges limiting the size, physical properties, etc. of components described in this specification, when a numerical range limited only by an upper limit and a numerical range limited only by a lower limit are separately exemplified, it should be understood that the numerical range combining these upper and lower limits is also included in the exemplary range of the present invention.

[0045] Polishing pad

[0046] Figure 1 is a plan view of a polishing pad according to an embodiment. Figure 1 , a polishing pad according to an embodiment includes a polishing layer (100) having a polishing surface (101).

[0047] For example, the polishing layer may include a urethane-based polymer and may be porous. The urethane-based polymer may be formed by a curing reaction of a urethane-based prepolymer and a curing agent. Specifically, the polishing layer may be formed by a polishing layer composition including a urethane-based prepolymer, a curing agent, a foaming agent, and other additives.

[0048] The polishing layer may include pores. The pores may have a closed-cell structure. The average diameter of the pores may be 5 μm to 200 μm. In addition, the polishing layer may include 20 volume % to 70 volume % of pores relative to the total volume of the polishing layer. That is, the porosity of the polishing layer may be 20 volume % to 70 volume %.

[0049] The thickness of the polishing layer is not particularly limited. Specifically, the average thickness of the polishing layer may be 0.8 mm to 5.0 mm, 1.0 mm to 4.0 mm, 1.0 mm to 3.0 mm, 1.5 mm to 2.5 mm, 1.7 mm to 2.3 mm, or 2.0 mm to 2.1 mm.

[0050] The polishing layer (100) comprises a plurality of first grooves (110) which are circular in shape and share the center of the polishing surface (101); and a plurality of second grooves (120) which are radially formed from a position at a distance from the center of 10% to 90% of the radius of the polishing surface toward the periphery.

[0051] The first groove is used to improve the polishing efficiency by reducing the fluidity of the slurry. The second groove is used to increase the fluidity of the slurry, thereby discharging the debris generated during the polishing process.

[0052] As described above, the first groove and the second groove are used to control the fluidity of the slurry during the CMP process. Their combination can properly control the maintenance and renewal of the slurry, thereby improving the polishing efficiency.

[0053] In particular, the second grooves do not extend from the center of the polishing surface; instead, they extend from a position away from the center. As a result, during the CMP process, the slurry fluidity in the polishing surface area in contact with the semiconductor substrate such as a wafer changes, thereby adjusting the wafer curve.

[0054] The distance between the position where the second groove extends and the center of the polishing surface can be, for example, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, or 80% or more of the radius of the polishing surface. As a specific example, the distance between the position where the second groove extends and the center of the polishing surface can be 10% to 39%, 40% to 59%, or 60% to 90% of the radius of the polishing surface.

[0055] In a specific embodiment, the second groove may include at least one of the following (i) to (iii).

[0056] (i) a plurality of second-A grooves formed radially toward the outer periphery from a position at a distance from the center of 10% to 39% of the radius of the polishing surface,

[0057] (ii) a plurality of second-B grooves formed radially toward the outer periphery from a position that is 40% to 59% of the radius of the polishing surface from the center, and

[0058] (iii) A plurality of second-C grooves are formed radially toward the outer periphery from a position that is 60% to 90% of the radius of the polishing surface from the center.

[0059] In addition, see Figure 1 The polishing pad may further include a plurality of third grooves (130) radially formed from the center to the periphery of the polishing surface (101). When the third grooves are used as radial grooves in addition to the second grooves, the effect of increasing the fluidity of the slurry to discharge the debris generated during the polishing process can be further enhanced.

[0060] Figure 2 A method of manufacturing a semiconductor device using a polishing pad according to an embodiment is described.

[0061] refer to Figure 2 , once the polishing pad (400) according to an embodiment has been attached to the pressing plate (500), the semiconductor substrate (900) as the object to be polished is placed on the polishing layer of the polishing pad (400). In this case, the surface of the semiconductor substrate (900) to be polished is in direct contact with the polishing surface of the polishing pad (400). The polishing slurry (700) can be sprayed onto the polishing pad through a nozzle for polishing. Thereafter, the semiconductor substrate (900) and the polishing pad (400) are relatively rotated so as to polish the surface of the semiconductor substrate (900). In this case, the rotation direction of the semiconductor substrate (900) and the rotation direction of the polishing pad (400) can be the same direction or opposite directions. The semiconductor substrate (900) mounted on the polishing head (810) is pressed against the polishing surface of the polishing pad (400) with a predetermined load to contact it, and then its surface can be polished.

[0062] Since in the polishing pad according to an embodiment, in addition to the concentric grooves, specially designed radial grooves are also used, the fluidity of the slurry in the CMP process can be improved, and the wafer curve and the polishing rate can be changed. In particular, the use of the second groove can improve the fluidity of the CMP slurry, thereby changing the polishing rate and the wafer curve of the central area of ​​the wafer, thereby reducing the WIWNU value and increasing the life of the polishing pad.

[0063] The intra-wafer non-uniformity (WIWNU) is a value related to the polishing flatness and uniformity during the CMP process using the polishing pad. Once the CMP process is performed on a semiconductor device such as a wafer using the polishing pad, the polishing rate is measured at multiple points. Then, it is calculated using the following equation.

[0064]

[0065] Here, RR_stdev is the polishing rate The standard deviation of the measured values, RR_avg is the polishing rate The average of the measurements.

[0066] The standard deviation of the polishing rate (RR_stdev) can be calculated using the following equation.

[0067]

[0068] Here, RR is the polishing rate measurement value at each point, RR_avg is the average value of the polishing rate measurement values, and n is the number of polishing rate measurement values.

[0069] A polishing pad having a certain level of WIWNU or lower can produce high-quality semiconductor devices with excellent polishing flatness and uniformity in a CMP process.

[0070] According to one embodiment, when a silicon oxide layer of a silicon wafer is polished using a ceria slurry on a polishing surface and a polishing rate is measured at 30 or more random positions, the within-wafer non-uniformity (WIWNU) calculated by the above equation is 15% or less.

[0071] For example, the WIWNU of the polishing pad may be 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, or 7% or less. Meanwhile, the lower limit of the WIWNU is not particularly limited, but it may be, for example, 0% or more, 1% or more, 2% or more, 3% or more, 4% or more, or 5% or more. Specifically, the WIWNU of the polishing pad may be 0% to 15%, more specifically, 1% to 8%.

[0072] Furthermore, the polishing rate (removal rate) can be calculated using the following equation by measuring the film thickness of a semiconductor device such as a wafer before and after a CMP process.

[0073]

[0074] The standard deviation of the polishing rate (RR_stdev) can be, for example or smaller, or smaller, or smaller or Specifically, the difference between the maximum and minimum values ​​of the standard deviation of the polishing rate (RR_stdev) can be to to to or to

[0075] Furthermore, the difference between the maximum and minimum values ​​of the polishing rate measurement can be, for example, or smaller, or smaller, or smaller or Specifically, the difference between the maximum and minimum values ​​of the polishing rate measurement can be to to to or to

[0076] Furthermore, the average polishing rate (RR_avg) can be, for example to to to or to

[0077] In a specific embodiment, WIWNU may be 1% to 8%, and RR_avg may be to In another specific embodiment, RR_avg can be to Within the above-mentioned preferred polishing rate range, it may be more beneficial to obtain a desired effect level in the CMP process.

[0078] Grooves

[0079] refer to Figure 1 The polishing layer (100) of the polishing pad includes a plurality of first grooves (110) which are circular and share the center of the polishing surface; and a plurality of second grooves (120) which are radially formed from a position at a distance from the center of the polishing surface of 10% to 90% of the radius of the polishing surface to the outer periphery. In addition, the polishing pad may also include a plurality of third grooves (130) which are radially formed from the center of the polishing surface (101) to the outer periphery.

[0080] The number of first grooves formed in the polishing layer may be 10 or more, 30 or more, 50 or more, 70 or more, or 90 or more, and may be 200 or less, 190 or less, 170 or less, and 150 or less, 130 or less, or 120 or less, specifically, 10 to 200, 50 to 170, 70 to 150, or 90 to 130.

[0081] In addition, the number of second grooves formed in the polishing layer can be 2 or more, 4 or more, 6 or more, 8 or more, 10 or more or 12 or more, as well as 100 or less, 50 or less, 40 or less, 30 or less or 20 or less, specifically, 2 to 100, 2 to 50, 4 to 50 or 4 to 40.

[0082] In a specific embodiment, the polishing layer can include a total of 50 to 150 first grooves and a total of 2 to 50 second grooves.

[0083] In another specific embodiment, the polishing layer can include 50 to 150 total first grooves, 4 to 50 total second grooves, and 4 to 50 total third grooves.

[0084] Furthermore, the planar shape of the second groove may be, for example, a plurality of straight lines radially formed at constant angular intervals and extending from a position away from the center toward the outer periphery.

[0085] Reference Figure 3 and Figure 4 , the first groove and the second groove may include inner surfaces (111 and 121) perpendicular to the polishing surface and bottom surfaces (112 and 122) parallel to the polishing surface.

[0086] refer to Figure 3 The width (w1) of the first groove (110) is a value obtained by measuring the width of the bottom surface (112) of the first groove. The depth (h1) of the first groove (110) is a value obtained by measuring the vertical straight line distance between the bottom surface (112) and the polishing surface (101).

[0087] The width (w1) of the first groove (110) may be, for example, 0.1 mm or more, 0.2 mm or more, or 0.3 mm or more, and may be 1 mm or less, 0.9 mm or less, or 0.8 mm or less, as a specific example, 0.1 mm to 1 mm.

[0088] The depth (h1) of the first groove (110) may be, for example, 0.4 mm or more, 0.5 mm or more, or 0.6 mm or more, and may be 1.2 mm or less, 1.1 mm or less, or 1.0 mm or less, as a specific example, 0.4 mm to 1.2 mm.

[0089] refer to Figure 3 The width (w2) of the second groove (120) is a value obtained by measuring the width of the bottom surface (122) of the second groove. The depth (h2) of the second groove (120) is a value obtained by measuring the vertical straight line distance between the bottom surface (122) and the polishing surface (101).

[0090] The width (w2) of the second groove (120) may be, for example, 0.5 mm or more, 0.6 mm or more, or 0.7 mm or more, and may be 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, as a specific example, 0.5 mm to 1.5 mm.

[0091] The depth (h2) of the second groove (120) may be, for example, 0.5 mm or more, 0.6 mm or more, or 0.7 mm or more, and may be 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, as a specific example, 0.5 mm to 1.5 mm.

[0092] In a specific embodiment, the width of the first groove may be 0.1 mm to 1 mm, and the width of the second groove may be 0.5 mm to 1.5 mm.

[0093] In a specific embodiment, the depth of the first groove may be 0.4 mm to 1.2 mm, and the depth of the second groove may be 0.5 mm to 1.5 mm.

[0094] The depth of the second groove may be equal to or deeper than the depth of the first groove. For example, the depth of the second groove may be 100% to 300% of the depth of the first groove. Alternatively, the depth of the second groove may be greater than 100% to 300% or 100% to 250% of the depth of the first groove. Alternatively, the depth of the second groove may be 110% to 300%, such as 120% to 300%, such as 120% to 200%, or such as 125% to 150% of the depth of the first groove. Within the above range, the fluidity of the slurry can be increased, thereby more effectively discharging debris generated in the polishing process.

[0095] In addition, the depth (h2) of the second groove may be 90% or less of the thickness (t) of the polishing layer. Specifically, the depth of the second groove may be 70% or less or 50% or less of the thickness of the polishing layer. More specifically, the depth of the second groove may be 10% to 60%, 20% to 50%, or 30% to 50% of the thickness of the polishing layer. Within the above range, deformation of the polishing layer due to the formation of the groove may be prevented, and the fluidity of the slurry may be further improved.

[0096] The width of the second groove may be 50% to 200% of the width of the first groove. Specifically, the width of the second groove may be 100% to 200% of the width of the first groove. Alternatively, the width of the second groove may be 100% to 180%, such as 100% to 170%, such as 100% to 165%, or such as 100% to 160%, of the width of the first groove. Within the above range, it is beneficial to improve the fluidity of the slurry while ensuring a sufficient polishing area.

[0097] In addition, the width of the third groove is a value obtained by measuring the width of the bottom surface of the third groove. The depth of the third groove is a value obtained by measuring the vertical straight line distance between the bottom surface of the third groove and the polishing surface (101).

[0098] The width of the third groove may be, for example, 0.5 mm or more, 0.6 mm or more, or 0.7 mm or more, and may be 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, as a specific example, 0.5 mm to 1.5 mm.

[0099] The depth of the third groove may be, for example, 0.5 mm or more, 0.6 mm or more, or 0.7 mm or more, and may be 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, as a specific example, 0.5 mm to 1.5 mm.

[0100] A plurality of first grooves may be used and spaced apart from each other at a certain distance interval. A plurality of second grooves may be used and spaced apart from each other at a certain angle interval. In addition, a plurality of third grooves may be used and spaced apart from each other at a certain angle interval.

[0101] The polishing layer may include a plurality of first grooves with a constant pitch. Figure 3 The pitch (p) of the first grooves (110) refers to the straight-line distance between the midpoints of the bottom surfaces (112) of any two first grooves.

[0102] Specifically, the polishing layer may have first grooves with a spacing of 1 mm to 10 mm. Alternatively, the polishing layer may have first grooves with a spacing of 1 mm to 5 mm. Alternatively, the polishing layer may have first grooves with a spacing of 2 mm to 4 mm.

[0103] In addition, the polishing layer may have a second groove at a certain angle, for example, at intervals of 10° to 50°, 15° to 45°, or 20° to 40°. In addition, the polishing layer may have a third groove at a certain angle, for example, at intervals of 10° to 50°, 15° to 45°, or 20° to 40°.

[0104] Additional components

[0105] refer to Figure 3 and Figure 4 The polishing pad may further include a support layer (200) disposed on the lower side of the polishing layer (100).

[0106] The support layer is used to support the polishing layer and absorb and disperse the impact applied to the polishing layer. The hardness of the support layer may be less than the hardness of the polishing layer. The support layer may include a non-woven fabric or a porous pad.

[0107] The support layer may include pores. The pores included in the support layer may have an open-pore structure. The pores included in the support layer may have a shape extending in the thickness direction of the support layer. In addition, the porosity of the support layer may be greater than the porosity of the polishing layer.

[0108] In addition, the polishing pad may further include an adhesive layer (300) between the polishing layer (100) and the support layer (200). The adhesive layer is used to bond the polishing layer and the support layer to each other. In addition, the adhesive layer can inhibit the polishing liquid from leaking downward from the upper part of the polishing layer to the support layer.

[0109] The adhesive layer may include a hot melt adhesive. Specifically, the adhesive layer may include a hot melt adhesive having a melting point of 90° C. to 130° C. More specifically, the adhesive layer may include a hot melt adhesive having a melting point of 110° C. to 130° C.

[0110] The hot melt adhesive may be at least one selected from the group consisting of polyurethane resin, polyester resin, ethylene-vinyl acetate resin, polyamide resin and polyolefin resin. Specifically, the hot melt adhesive may be at least one selected from the group consisting of polyurethane resin and polyester resin.

[0111] The thickness of the adhesive layer may be 5 μm to 30 μm, specifically, 20 μm to 30 μm, and more specifically, 23 μm to 27 μm.

[0112] Additionally, the polishing pad may include a window in the polishing layer. The window helps determine the endpoint of the CMP process by measuring the flatness and thickness of the wafer surface in situ.

[0113] For example, the polishing layer has a first through hole in the thickness direction, and the window can be inserted into the first through hole. In addition, the support layer has a second through hole in the thickness direction, and the first through hole and the second through hole can be connected to each other.

[0114] The window may be formed from a window composition comprising a urethane-based prepolymer and a curing agent. Preferably, the window may be non-foamy. Microbubbles may not be present in the window.

[0115] For example, the window may have a thickness of 2.3 mm to 2.5 mm, a light transmittance of 60% to 80%, and a refractive index of 1.45 to 1.60.

[0116] Method for preparing polishing pad

[0117] A method for preparing a polishing pad according to an embodiment includes (1) preparing a polishing layer including a polishing surface; (2) forming a plurality of first grooves, the first grooves being circular in shape and sharing the center of the polishing surface; and (3) forming a plurality of second grooves, the second grooves being radially formed from positions at a distance from the center of 10% to 90% of the radius of the polishing surface toward the periphery. Steps (2) and (3) may be performed sequentially or simultaneously.

[0118] Furthermore, in addition to steps (1) to (3), the method for preparing a polishing pad may further include (4) forming a plurality of third grooves, the third grooves being radially formed from the center of the polishing surface toward the periphery. Steps (2) to (4) may be performed sequentially or simultaneously. Alternatively, step (2) may be performed first, and steps (3) and (4) may be performed simultaneously.

[0119] Hereinafter, each step will be described in detail.

[0120] In step (1), a polishing layer including a polishing surface is prepared.

[0121] The polishing layer may include a urethane-based polymer prepared from a composition including a urethane-based prepolymer, a curing agent, a foaming agent, and other additives.

[0122] Prepolymers generally refer to polymers with a relatively low molecular weight, in which the degree of polymerization is adjusted to an intermediate level in order to facilitate the shaping of the molded article to be produced in the end.

[0123] The prepolymer can be formed alone or after reacting with another polymerizable compound. Specifically, the urethane-based prepolymer can be prepared by reacting an isocyanate compound with a polyol, and can contain unreacted isocyanate groups (NCO). The isocyanate compound and the polyol compound are not particularly limited as long as they can be used to prepare the urethane-based polymer.

[0124] The curing agent may be at least one of an amine compound and an alcohol compound. Specifically, the curing agent may include at least one compound selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols.

[0125] The foaming agent is not particularly limited as long as it is generally used to form voids in the polishing pad. For example, the foaming agent may be at least one selected from a solid-phase foaming agent having a hollow structure, a liquid-phase foaming agent using a volatile liquid, and an inert gas.

[0126] In the above step (2), a plurality of first grooves are formed which have a circular shape and share the center of the polishing surface. In addition, in step (3), a plurality of second grooves are formed radially from a position at a distance from the center of 10% to 90% of the radius of the polishing surface toward the outer periphery.

[0127] In this case, the depth of the second groove and the third groove can be equal to or deeper than the depth of the first groove. For this reason, the second groove and the third groove can be formed later than the first groove. If the second groove is formed first, it may be inconvenient and difficult to form them deeper than the first groove.

[0128] Furthermore, specific configurations of the depth, width, pitch, etc. of the first groove, the second groove, and the third groove are as described above in the example regarding the polishing pad.

[0129] The formation of the first groove, the second groove, and the third groove may be performed by cutting and removing a portion of the polishing surface. For example, a tip may be used for cutting. The polishing surface of the polishing layer may be cut by the tip to form a groove. Specifically, the tip is fixed to abut against the polishing surface of the polishing layer, and then the polishing pad including the polishing layer may be rotated or moved in a desired direction to remove a portion of the surface of the polishing layer, thereby forming a groove. The formation of the first groove, the second groove, and the third groove may include forming an inner surface perpendicular to the polishing surface and a bottom surface parallel to the polishing surface by cutting.

[0130] In addition, the method of preparing the polishing pad may further include, after forming the groove, processing an edge where the polishing surface intersects the inner surface into a curved surface.

[0131] The curvature processing can be performed by removing the portion of the edge where the polishing surface intersects with the inner surface of the groove. The curvature processing can be performed using a grinder or a wedge. Specifically, the curvature processing can be performed by removing the portion of the edge where the polishing surface intersects with the inner surface of the groove, so that the radius of curvature becomes 0.1mm to 5mm, 0.1mm to 2mm or 0.3mm to 1.5mm. If the radius of curvature is within the above range, defects such as scratches on the wafer surface during the CMP process can be effectively prevented.

[0132] The curvature processing can be performed by using a grinder. In addition, the grinder may include a grinding surface. That is, the edge where the polishing surface intersects with the inner surface of the groove can be processed into a curved surface by the grinding surface of the grinder.

[0133] In addition, the grinder can process the edge where the inner surface of the groove intersects with the polishing surface into a curved surface while it rotates. In this case, the rotation speed of the grinder can be 1,000rpm to 50,000rpm, 2,000rpm to 35,000rpm, or 5,000rpm to 20,000rpm.

[0134] The groove forming step and the curvature processing step as described above can be performed continuously. As an example, the tip for forming the groove and the grinder or wedge for curvature processing are arranged adjacent to each other so that the groove forming and curvature processing can be performed continuously on the polishing surface.

[0135] A method for preparing a semiconductor device

[0136] The above-described polishing pad can be used to manufacture semiconductor devices by chemical and mechanical polishing.

[0137] A method for preparing a semiconductor device according to an embodiment includes polishing a surface of a semiconductor substrate using a polishing pad according to an embodiment. Specifically, the method for preparing a semiconductor device may include providing a polishing pad according to an embodiment; and while a polishing surface of the polishing layer and a surface of the semiconductor substrate are in contact with each other, they are relatively rotated to polish the surface of the semiconductor substrate.

[0138] Figure 2 A method of manufacturing a semiconductor device using a polishing pad according to an embodiment is described.

[0139] First, once the polishing pad (400) according to an embodiment has been attached to the pressing plate (500), the semiconductor substrate (900) as the object to be polished is placed on the polishing pad (400). In this case, the surface of the semiconductor substrate (900) to be polished is in direct contact with the polishing surface of the polishing pad (400). The polishing slurry (700) can be sprayed onto the polishing pad through a nozzle for polishing. The flow rate of the polishing slurry (700) supplied through the nozzle can be about 10 cm / s depending on the purpose. 3 / min to about 1,000cm 3 For example, the flow rate of the polishing slurry (400) may be about 50 cm / min. 3 / min to about 500cm 3 / min, but not limited to this.

[0140] Thereafter, the semiconductor substrate (900) and the polishing pad (400) are relatively rotated to polish the surface of the semiconductor substrate (900). In this case, the rotation direction of the semiconductor substrate (900) and the rotation direction of the polishing pad (400) may be the same direction or opposite directions. The rotation speeds of the semiconductor substrate (900) and the polishing pad (400) may be selected in the range of about 10 rpm to about 500 rpm, respectively, according to the purpose. For example, the rotation speeds of the semiconductor substrate (600) and the polishing pad (100) may be about 30 rpm to about 200 rpm, but are not limited thereto.

[0141] The semiconductor substrate (900) mounted on the polishing head (810) is pressed against the polishing surface of the polishing pad (400) with a predetermined load to contact therewith, and then the surface thereof can be polished. The load applied to the polishing surface of the polishing pad (400) and the surface of the semiconductor substrate (900) by the polishing head (810) can be between about 1 gf / cm2 and about 1 gf / cm3 according to the purpose. 2 To about 1,000gf / cm 2 For example, it can be about 10 gf / cm 2 To about 800gf / cm 2 , but not limited to this.

[0142] In one embodiment, the semiconductor substrate (900) as the object to be polished may include an oxide layer, a tungsten layer, or a composite layer thereof. Specifically, the semiconductor substrate (900) may include an oxide layer, a tungsten layer, or a composite layer of an oxide layer and a tungsten layer. The composite layer of the oxide layer and the tungsten layer may be a multilayer film in which a tungsten layer is stacked on one side of the oxide layer, or may be a single layer film in which an oxide region and a tungsten region are mixed in a single layer. Since the object to be polished has such a film substance, and at the same time the polishing pad has the characteristics according to the embodiment, the semiconductor device manufactured according to the method for manufacturing a semiconductor device may have minimal defects.

[0143] In one embodiment, the method for preparing a semiconductor device may further include: in the step of polishing the object to be polished, supplying any one of a slurry for polishing an oxide layer and a slurry for polishing a tungsten layer, or supplying the slurry for polishing an oxide layer and the slurry for polishing a tungsten layer to the polishing surface in sequence.

[0144] For example, if the semiconductor substrate as the object to be polished includes an oxide layer, the method for preparing a semiconductor device may include supplying a slurry for polishing the oxide layer. If the semiconductor substrate includes a tungsten layer, the method for preparing a semiconductor device may include supplying a slurry for polishing the tungsten layer. If the semiconductor substrate includes a composite layer of an oxide layer and a tungsten layer, the method for preparing a semiconductor device may include sequentially supplying a slurry for polishing the oxide layer and a slurry for polishing the tungsten layer to the polishing surface. Here, depending on the method, the slurry for polishing the oxide layer may be supplied first, and then the slurry for polishing the tungsten layer may be supplied, or the slurry for polishing the tungsten layer may be supplied first, and then the slurry for polishing the oxide layer may be supplied.

[0145] In one embodiment, in order to keep the polishing surface of the polishing pad (400) in a state suitable for polishing, the method for preparing a semiconductor device may further include treating the polishing surface of the polishing pad (400) using a conditioner (600) while polishing the semiconductor substrate (900).

[0146] Embodiments of the present invention

[0147] Although the following examples are provided, the scope of possible implementations is not limited thereto.

[0148] Example 1 Preparation of polishing pad

[0149] Step 1: Preparation of the polishing layer

[0150] A casting machine is provided, which is equipped with tanks and feed lines for prepolymer, curing agent, inert gas and reaction rate controller. A urethane-based prepolymer having NCO terminal groups (NCO content: 8.0%, trade name: PUGL-450D, SKC) is added to the prepolymer tank, bis(4-amino-3-chlorophenyl)methane (Ishihara) is added to the curing agent tank, argon (Ar) is added to the inert gas tank, and a tertiary amine-based reaction rate accelerator (trade name: A1, AirProduct) is added to the reaction rate controller tank. The prepolymer, curing agent, inert gas and reaction rate controller are stirred while being fed to a mixing head at a constant rate through their respective feed lines. In this case, the prepolymer and curing agent are fed while adjusting the equivalent ratio in the reactor, and the total feed amount is maintained at 10 kg / min. In addition, the reaction rate controller was fed at a constant amount of 0.5 wt% based on the total feed rate of the prepolymer and the curing agent. In addition, the inert gas was fed at a constant volume of 20% based on the total volume of the prepolymer and the curing agent. The mixed raw materials were injected into a mold (1,000 mm × 1,000 mm × 3 mm) and reacted to obtain a solid cake-shaped molded product. Thereafter, the top and bottom of the molded product were each ground to a thickness of 0.5 mm to obtain a polishing layer with a thickness of 2 mm.

[0151] Step 2: Formation of the first groove (concentric groove)

[0152] A concentric first groove is formed on the polishing surface of the polishing layer using a tip. Specifically, the tip is fixed to abut the polishing surface of the polishing layer, and then the polishing pad including the polishing layer is rotated to remove a portion of the surface of the polishing layer, thereby forming the first groove. A total of 117 first grooves (concentric grooves) are formed (with a pitch of 3.047 mm), sharing the center of the polishing surface. Each first groove is formed to have a width of 0.47 mm and a depth of 0.846 mm.

[0153] Step 3: Formation of the second groove and the third groove (radial groove)

[0154] A second groove and a third groove in a radial form are formed on the polishing surface of the polishing layer using a tip. Specifically, the tip is fixed to abut the polishing surface of the polishing layer, and then the polishing pad including the polishing layer is moved to remove a portion of the surface of the polishing layer, thereby forming the second groove and the third groove. When counting from the center of the polishing surface to the outer periphery of the polishing surface, the second groove is formed to extend radially from the 30th of the first groove. The third groove is formed to extend radially from the center of the polishing surface to the outer periphery of the polishing surface. A total of 16 second grooves are formed at an angular interval of about 22.5°. There are a total of 16 third grooves (extending from the center), which are formed at an angular interval of about 22.5°. The second groove and the third groove are formed alternately with each other, so that the angular interval between the second groove and the third groove is about 11.25°. In addition, each second groove is formed to have a width of 0.96 mm and a depth of 1.012 mm. Each third groove is formed to have a width of 0.96 mm and a depth of 1.012 mm.

[0155] As a result, a polishing pad having formed on its polishing surface the first grooves (concentric grooves), the second grooves (radial grooves extending from the 30th concentric groove when counted from the center), and the third grooves (radial grooves extending from the center) was obtained.

[0156] Examples 2 and 3: Preparation of polishing pads

[0157] The same steps as in Example 1 were repeated to prepare a polishing pad, except that the position where the second grooves extended was changed as shown in Table 1 below, and the sizes of the respective grooves were adjusted as shown in Table 2 below.

[0158] Comparative Example 1: Preparation of polishing pad

[0159] The same steps as in Example 1 were repeated to prepare a polishing pad, except that, as shown in Tables 1 and 2 below, only the first grooves were formed, and the second grooves and the third grooves were not formed.

[0160] Comparative Example 2: Preparation of polishing pad

[0161] The same steps as in Example 1 were repeated to prepare a polishing pad, except that, as shown in Tables 1 and 2 below, only the first groove and the third groove were formed, and the second groove was not formed.

[0162] [Table 1]

[0163]

[0164] [Table 2]

[0165]

[0166] Test Case 1: CMP Evaluation

[0167] The polishing pads prepared in Examples and Comparative Examples were respectively used to evaluate CMP, as follows.

[0168] (1) Polishing rate (removal rate)

[0169] A silicon wafer with a diameter of 300 mm on which silicon oxide has been deposited by a CVD process is arranged on a porous polyurethane polishing pad mounted on a CMP polishing machine platen, with the silicon oxide layer of the silicon wafer facing downward. Then, under a polishing load of 4.0 psi, while the polishing pad is rotated at a speed of 150 rpm, the calcined ceria slurry is supplied to the polishing pad at a rate of 250 ml / min, and the platen is rotated at a speed of 150 rpm for 60 seconds to polish the silicon oxide layer. After polishing is completed, the silicon wafer is removed from the carrier, loaded into a spin dryer, cleaned with deionized water (DIW), and then dried with nitrogen for 15 seconds. The film thickness of the silicon wafer dried before and after polishing is measured using a spectroscopic reflectometer thickness gauge (manufacturer: Keyence, model: SI-F80R). The polishing rate is calculated using the following equation.

[0170]

[0171] (2)WIWNU

[0172] Polishing was performed for 1 minute under the same polishing conditions as in the above section (1). The polishing rate of the silicon wafer thus polished was measured at 47 locations. The intra-wafer non-uniformity (WIWNU) was calculated according to the following equation. The positions of the various points at which the polishing rate was measured were randomly selected.

[0173]

[0174] Here, RR_stdev is the polishing rate The standard deviation of the measured values, and RR_avg is the polishing rate The average of the measurements.

[0175] The standard deviation of the polishing rate (RR_stdev) can be calculated using the following equation.

[0176]

[0177] Here, RR is the polishing rate measurement value at each point, RR_avg is the average value of the polishing rate measurement values, and n is the number of polishing rate measurement values.

[0178] The test results are shown in the table below. In addition, the wafer curve after CMP using each polishing pad is as follows Figure 5 shown.

[0179] [Table 3]

[0180]

[0181] As a result of the test, the wafer curves in Examples 1 to 3 were changed due to the use of the second grooves. In particular, the change in the curve in the center area of ​​the wafer reduced the WIWNU value. This shows that the CMP process performance can be improved by using the second groove and changing the position where it extends.

Claims

1. A polishing pad comprising a polishing layer having a polishing surface, wherein the polishing layer comprises a plurality of first grooves, the first grooves being circular in shape and sharing a center of the polishing surface; and a plurality of second grooves, the second grooves being radially formed from positions at a distance from the center of 10% to 90% of a radius of the polishing surface toward the outer periphery, and When a silicon oxide layer of a silicon wafer is polished using a ceria slurry on the polishing surface and the polishing rate is measured at 30 or more random positions, the within-wafer non-uniformity (WIWNU) calculated by the following equation is 15% or less: in, RR_stdev is the polishing rate The standard deviation of the measured values, and RR_avg is the polishing rate The average of the measurements.

2. The polishing pad according to claim 1, wherein The WIWNU is 1% to 8%, and the RR_avg is to 3. The polishing pad according to claim 2, wherein: The RR_avg is to 4. The polishing pad according to claim 1, wherein: The polishing layer includes a total of 50 to 150 first grooves and a total of 2 to 50 second grooves.

5. The polishing pad according to claim 4, wherein: The width of the first groove is 0.1 mm to 1 mm, and the width of the second groove is 0.5 mm to 1.5 mm.

6. The polishing pad according to claim 5, wherein: The first groove has a depth of 0.4 mm to 1.2 mm, and the second groove has a depth of 0.5 mm to 1.5 mm.

7. The polishing pad according to claim 1, wherein: The second groove includes at least one of the following (i) to (iii): (i) a plurality of second-A grooves formed radially toward the outer periphery from a position at a distance from the center of 10% to 39% of the radius of the polishing surface, (ii) a plurality of second-B grooves formed radially toward the outer periphery from a position that is 40% to 59% of the radius of the polishing surface from the center, and (iii) A plurality of second-C grooves are formed radially toward the outer periphery from a position that is 60% to 90% of the radius of the polishing surface from the center.

8. The polishing pad according to claim 1, further comprising a plurality of third grooves radially formed from a center toward an outer periphery of the polishing surface.

9. The polishing pad according to claim 8, wherein: The polishing layer includes a total of 50 to 150 first grooves, a total of 4 to 50 second grooves, and a total of 4 to 50 third grooves. 10 . A method of manufacturing a semiconductor device, comprising polishing a surface of a semiconductor substrate using the polishing pad according to claim 1 .

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