Polishing pad with improved slurry flowability and process for preparing semiconductor device using the same

Abstract

To provide a polishing pad with improved slurry flowability used for a chemical mechanical polishing (CMP) process of a semiconductor device and process for preparing a semiconductor device using the same.SOLUTION: A polishing pad includes a polishing layer 100 including a polishing surface 101. The polishing layer includes a plurality of first grooves 110 having circular shapes sharing a center of the polishing surfaces and a plurality of second grooves 120 formed radial from a point, which is separated from the center by 10% to 90% of a radius of the polishing surface, to an outline. A silicon oxide film of a silicon wafer is polished using a ceria slurry for the polishing surface, a polishing rate is then measured at points at 30 or more random positions, and WIWNU (Within Wafer Non Uniformity)=RR_stdev / RR_avg is 15% or less. RR_stdev is a standard deviation of polishing rate (Å / min) measurement values, and RR_avg is an average of polishing rate (Å / min) measurement values.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] An implementation example relates to a polishing pad used in a chemical mechanical polishing (CMP) process of a semiconductor element, and specifically, to a polishing pad with improved slurry fluidity and a method for manufacturing a semiconductor element using the same.

Background Art

[0002] Among semiconductor manufacturing processes, chemical mechanical polishing (CMP) is a process of supplying slurry while attaching a semiconductor substrate such as a wafer to a head and bringing it into contact with the surface of a polishing pad formed on a platen, chemically reacting the surface of the semiconductor substrate, and relatively moving the platen and the head to mechanically flatten the uneven portions of the semiconductor substrate surface.

[0003] The polishing pad, as an essential component playing an important role in such a CMP process, is usually made of a polyurethane resin and is provided with grooves on the surface for carrying a large flow of slurry and pores for supporting a fine flow.

[0004] For the manufacture of the polishing pad, a prepolymer is obtained by reacting a diisocyanate and a polyol, and then a curing agent and a foaming agent are mixed with the prepolymer and cured to obtain a polyurethane foam sheet. Then, the upper and lower surfaces of the polyurethane foam sheet are sliced to a desired thickness to obtain an upper pad, and after grooves are dug in a specific shape on the surface of the upper pad using a tip or the like to form grooves, it is adhered to a polyurethane-based lower pad to complete the polishing pad.

[0005] The grooves may have various shapes, for example, there are grooves such as circles sharing a center (see Patent Document 1). In this way, the grooves provided in the polishing pad play a role of assisting in flattening the wafer surface while carrying the slurry and allowing it to flow.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Korean Patent Publication No. 2005-0095818 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] In the CMP process, the polishing pad removes the film quality while wearing down the wafer surface. However, the fluidity of the slurry varies depending on the type of slurry and the film quality, and the polishing rate and the WIWNU (Within Wafer Non Uniformity) value will change. As a method of deforming the wafer profile (Wafer Profile), there is also a method of adjusting the process conditions, but there is a consumption of time and materials.

[0008] Therefore, as a result of research by the present inventors, it has been found that by introducing radially grooved designs specially devised in addition to concentric grooves, the fluidity of the slurry can be improved and the wafer profile and the polishing rate can be changed.

[0009] Therefore, the problem of the embodiment is to provide a polishing pad with improved slurry fluidity and polishing rate and a method for manufacturing a semiconductor device using the same. [Means for Solving the Problems]

[0010] According to an embodiment to solve the above problems, it includes a polishing layer having a polishing surface, and the polishing layer includes a plurality of first grooves having a circular shape sharing the center of the polishing surface, and a plurality of second grooves formed radially from a point 10% to 90% of the radius of the polishing surface from the center to the outer contour. After polishing the silicon oxide film of the silicon wafer using ceria slurry on the polishing surface, a polishing pad is provided in which the WIWNU (Within Wafer Non Uniformity) calculated by the following formula is 15% or less by measuring the polishing rate at points in 30 or more random positions: JPEG2025077989000002.jpg1471 Here, RR_stdev is the standard deviation of the measured polishing rate (Å / min), and RR_avg is the average of the measured polishing rate (Å / min).

[0011] According to another embodiment, there is provided a method of manufacturing a semiconductor device, including a step of polishing the surface of a semiconductor substrate using the polishing pad.

Advantages of the Invention

[0012] The polishing pad according to the embodiment can improve the fluidity of the slurry and change the wafer profile and the polishing rate by introducing a specially designed radial second groove in addition to the concentric first groove.

[0013] In particular, the introduction of the second groove can improve the fluidity of the CMP slurry, change the polishing rate in the central region of the wafer and the wafer profile, reduce the WIWNU value, and increase the pad life.

[0014] Therefore, the polishing pad according to the embodiment can be applied to the manufacture of semiconductor devices, and can improve the process efficiency and product quality.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0016] In the following description of the implementation examples, if a specific description of a related known configuration or function is determined to obscure the gist of the implementation examples, the detailed description thereof will be omitted. Also, the size of each component in the drawings may be exaggerated or omitted for the purpose of explanation and may differ from the actual size applied.

[0017] In this specification, the description that one component is formed above / below another component, or is connected or coupled to each other, includes all cases where they are formed, connected, or coupled directly or indirectly via other components. Also, it should be understood that the criteria regarding above / below each component may vary depending on the direction of observing the object.

[0018] In this specification, the terms referring to each component are used to distinguish it from other components and are not intended to limit the implementation examples. Also, in this specification, a singular expression includes a plural expression unless the context clearly indicates a different meaning.

[0019] In this specification, terms such as first, second, etc. are used to describe various components, and the components should not be limited by the terms. The terms are used for the purpose of distinguishing one component from another.

[0020] In this specification, the description "including" is for specifying characteristics, regions, stages, processes, elements, components, and does not exclude the existence or addition of other characteristics, regions, stages, processes, elements, components unless otherwise stated.

[0021] For the molecular weights of the compounds and the molecular weights of the polymers described in this specification, for convenience, the units of molar mass are described, but they may be understood as relative masses based on carbon-12. Further, the molecular weight of the polymer described in this specification may be interpreted as the number average molecular weight or the weight average molecular weight, and may be interpreted as the number average molecular weight, for example.

[0022] In the numerical ranges that limit the size, physical properties, etc. of the components described in this specification, when a numerical range limited only by the upper limit value and a numerical range limited only by the lower limit value are separately exemplified, it should be understood that the numerical range combined with these upper and lower limit values is also included in the exemplified range.

[0023] [Polishing Pad] FIG. 1 shows a plan view of a polishing pad according to one implementation example. Referring to FIG. 1, a polishing pad according to one implementation example includes a polishing layer 100 having a polishing surface 101.

[0024] The polishing layer may include, for example, 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 produced from a polishing layer composition containing a urethane-based prepolymer, a curing agent, a foaming agent, and other additives.

[0025] The polishing layer may include voids. The voids (pores) may have a closed cell structure. The average diameter of the voids may be 5 μm to 200 μm. Further, the polishing layer may include voids of 20% to 70% by volume with respect to the total volume of the polishing layer. That is, the porosity of the polishing layer may be 20% to 70% by volume.

[0026] 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.

[0027] The polishing layer 100 includes a plurality of first grooves 110 having a circular shape sharing the center of the polishing surface 101, and a plurality of second grooves 120 formed radially from a point 10% to 90% of the radius of the polishing surface away from the center to the outer contour.

[0028] The first grooves have the effect of reducing the fluidity of the slurry and increasing the polishing efficiency, and the second grooves have the effect of increasing the fluidity of the slurry and discharging residues generated during the polishing process.

[0029] Thus, the first grooves and the second grooves serve to control the fluidity of the slurry during the CMP process, and by combining them, the degree of maintenance and renewal of the slurry can be appropriately adjusted, and the polishing efficiency can be improved.

[0030] In particular, the second grooves do not start from the center of the polishing surface, but start from a point at a certain distance away from the center. Thereby, the fluidity of the slurry can be changed in the region of the polishing surface in contact with a semiconductor substrate such as a wafer in the CMP process, and the wafer profile can be adjusted.

[0031] The starting point of the second grooves can be, for example, a point 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 away from the center of the polishing surface. As a specific example, the starting point of the second grooves can be a point 10% to 39% away from the center of the polishing surface, a point 40% to 59% away, or a point 60% to 90% away.

[0032] In one specific example, the second grooves may include at least one of the following (i) to (iii). (i) A plurality of second A grooves formed radially from a point 10% to 39% of the radius of the polishing surface away from the center to the outer contour. (ii) A plurality of second B grooves formed radially from a point 40% to 59% of the radius of the polishing surface away from the center to the outer contour, and (iii) A plurality of second C grooves formed radially from a point 60% to 90% of the radius of the polishing surface away from the center to the outer contour.

[0033] Referring to FIG. 1, the polishing pad may further include a plurality of third grooves 130 formed radially from the center of the polishing surface 101 to the outer contour. As a radial groove, in addition to the second groove, a third groove is provided, which can increase the fluidity of the slurry and further improve the effect of discharging the residue generated during the polishing process.

[0034] FIG. 2 shows a manufacturing process of a semiconductor device using a polishing pad according to an embodiment. Referring to FIG. 2, after mounting a polishing pad 400 according to an embodiment on a platen 500, a semiconductor substrate 900 to be polished is disposed on the polishing surface of the polishing pad 400. At this time, the surface to be polished of the semiconductor substrate 900 is in direct contact with the polishing surface of the polishing pad 400. For polishing, polishing slurry 700 may be sprayed onto the polishing pad via a nozzle. Then, the semiconductor substrate 900 and the polishing pad 400 rotate relative to each other, and the surface of the semiconductor substrate 900 can be polished. At this time, the rotation direction of the semiconductor substrate 900 and the rotation direction of the polishing pad 400 may be the same or opposite. The semiconductor substrate 900 is mounted on a polishing head 810, pressurized and abutted against the polishing surface of the polishing pad 400 with a predetermined load, and then its surface can be polished.

[0035] By introducing specially designed radial grooves in addition to the concentric grooves in the polishing pad according to the embodiment, the slurry fluidity in the CMP process can be improved, and the wafer profile and polishing rate can be changed. In particular, the introduction of the second groove can improve the CMP slurry fluidity, change the polishing rate and wafer profile in the central region of the wafer, reduce the WIWNU value, and increase the pad life.

[0036] WIWNU is a value related to polishing flatness and uniformity during the CMP process using a polishing pad. When performing the CMP process of semiconductor elements such as wafers using a polishing pad and measuring the polishing rate at a number of points, it can be calculated by the following formula. JPEG2025077989000003.jpg1471 Here, RR_stdev is the standard deviation of the measured values of the polishing rate (Å / min), and RR_avg is the average of the measured values of the polishing rate (Å / min).

[0037] The standard deviation of the polishing rate (RR_stdev) can be calculated by the following calculation. JPEG2025077989000004.jpg1869 Here, RR is the measured value of the polishing rate at each individual point, RR_avg is the average of the measured values of the polishing rate, and n is the number of measured values of the polishing rate.

[0038] A polishing pad with the WIWNU below a specific level can produce high-quality semiconductor elements with excellent polishing flatness and uniformity in the CMP process.

[0039] According to one implementation example, after polishing the silicon oxide film of a silicon wafer using ceria slurry on the polishing surface, the polishing rate is measured at points in 30 or more random positions, and the WIWNU calculated by the above formula is 15% or less.

[0040] For example, the WIWNU of the polishing pad can 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. On the other hand, the lower limit value of the WIWNU is not particularly limited, but can 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 is 0% to 15%, and more specifically, 1% to 8%.

[0041] Also, the polishing rate can be calculated by the following formula after measuring the film thickness of semiconductor elements such as wafers before and after the CMP process. Polishing rate (Å / min) = Change in film thickness before and after polishing (Å) / Polishing time (min)

[0042] The standard deviation (RR_stdev) of the polishing rate can be, for example, 1000 Å / min or less, 700 Å / min or less, 500 Å / min or less, or 400 Å / min or less. Specifically, the difference between the maximum value and the minimum value among the standard deviations (RR_stdev) of the polishing rate can be 0 Å / min to 1000 Å / min, 10 Å / min to 700 Å / min, 50 Å / min to 500 Å / min, or 100 Å / min to 400 Å / min.

[0043] Also, the difference between the maximum value and the minimum value among the measured polishing rates can be, for example, 2000 Å / min or less, 1500 Å / min or less, 1000 Å / min or less, or 500 Å / min or less. Specifically, the difference between the maximum value and the minimum value among the measured polishing rates can be 0 Å / min to 2000 Å / min, 10 Å / min to 1500 Å / min, 50 Å / min to 1000 Å / min, or 100 Å / min to 500 Å / min.

[0044] Also, the average polishing rate (RR_avg) can be, for example, 2000 Å / min to 4000 Å / min, 2500 Å / min to 4000 Å / min, 3000 Å / min to 3500 Å / min, or 2000 Å / min to 3400 Å / min.

[0045] In one specific example, the WIWNU can be 1% to 8%, and the RR_avg can be 2500 Å / min to 4000 Å / min. In other specific examples, the RR_avg can be 3200 Å / min to 3400 Å / min. Within the preferred range of the polishing rate, it may be more advantageous in obtaining the desired level of CMP process effect.

[0046] [Groove] Referring to FIG. 1, the polishing layer 100 of the polishing pad includes a plurality of first grooves 110 having a circular shape sharing the center of the polishing surface, and a plurality of second grooves 120 formed radially from a point 10% to 90% of the radius of the polishing surface from the center to the outer periphery. Further, the polishing pad may further include a plurality of third grooves 130 formed radially from the center to the outer periphery of the polishing surface 101.

[0047] The number of the first grooves formed in the polishing layer is 10 or more, 30 or more, 50 or more, 70 or more, or 90 or more, and is 200 or less, 190 or less, 170 or less, 150 or less, 130 or less, or 120 or less. Specifically, it can be 10 to 200, 50 to 170, 70 to 150, or 90 to 130.

[0048] Also, the number of the second grooves formed in the polishing layer is 2 or more, 4 or more, 6 or more, 8 or more, 10 or more, or 12 or more, and is 100 or less, 50 or less, 40 or less, 30 or less, or 20 or less. Specifically, it can be 2 to 100, 2 to 50, 4 to 50, or 4 to 40.

[0049] In one specific example, the polishing layer may include 50 to 150 of the first grooves and 2 to 50 of the second grooves.

[0050] In another specific example, the polishing layer may include 50 to 150 of the first grooves, 4 to 50 of the second grooves, and 4 to 50 of the third grooves.

[0051] Also, the planar shape of the second groove can be, for example, a plurality of radial straight lines formed at regular angular intervals from a point away from the center to the outer contour.

[0052] Referring to FIGS. 3 and 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.

[0053] Referring to FIG. 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, and the depth h1 of the first groove 110 is a value obtained by measuring the perpendicular linear distance between the bottom surface 112 of the first groove and the polishing surface 101.

[0054] The width w1 of the first groove 110 is, for example, 0.1 mm or more, 0.2 mm or more, or 0.3 mm or more, and is also 1 mm or less, 0.9 mm or less, or 0.8 mm or less, and can be, as a specific example, 0.1 mm to 1 mm.

[0055] The depth h1 of the first groove 110 is, for example, 0.4 mm or more, 0.5 mm or more, or 0.6 mm or more, and is also 1.2 mm or less, 1.1 mm or less, or 1.0 mm or less, and can be, as a specific example, 0.4 mm to 1.2 mm.

[0056] Referring to FIG. 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, and the depth h2 of the second groove 120 is a value obtained by measuring the perpendicular distance between the bottom surface 122 of the second groove and the polishing surface 101.

[0057] The width w2 of the second groove 120 is, for example, 0.5 mm or more, 0.6 mm or more, or 0.7 mm or more, and is also 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, and can be, as a specific example, 0.5 mm to 1.5 mm.

[0058] The depth h2 of the second groove 120 is, for example, 0.5 mm or more, 0.6 mm or more, or 0.7 mm or more, and is also 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, and can be, as a specific example, 0.5 mm to 1.5 mm.

[0059] In one specific example, the width of the first groove can be 0.1 mm to 1 mm, and the width of the second groove can be 0.5 mm to 1.5 mm.

[0060] In another specific example, the depth of the first groove can be 0.4 mm to 1.2 mm, and the depth of the second groove can be 0.5 mm to 1.5 mm.

[0061] The depth of the second groove may be the same as 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 more than 100% to 300% or less, or more than 100% to 250% or less of the depth of the first groove. Alternatively, the depth of the second groove may be 110% to 300% of the depth of the first groove, for example, 120% to 300%, for example, 120% to 200%, for example, 125% to 150%. When within the above range, the fluidity of the slurry is improved and the discharge of residues generated during the polishing process is more efficiently performed. At the same time, when polishing the wafer using the polishing pad, while ensuring an appropriate polishing rate, defects on the polished surface can be minimized.

[0062] Also, 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. When within the above range, while preventing deformation of the polishing layer due to groove formation, the fluidity of the slurry can be further improved.

[0063] 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%, for example, 100% to 170%, for example, 100% to 165%, for example, 100% to 160% of the width of the first groove. When within the above range, it is advantageous for improving the fluidity of the slurry while ensuring a sufficient polishing area.

[0064] Also, the width of the third groove is a value measured for the width of the bottom surface of the third groove, and the depth of the third groove is a value measured for the perpendicular straight-line distance between the bottom surface of the third groove and the polishing surface 101.

[0065] The width of the third groove is, for example, 0.5 mm or more, 0.6 mm or more, or 0.7 mm or more, and is also 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less. As a specific example, it can be 0.5 mm to 1.5 mm.

[0066] The depth of the third groove is, for example, 0.5 mm or more, 0.6 mm or more, or 0.7 mm or more, and is also 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less. As a specific example, it can be 0.5 mm to 1.5 mm.

[0067] A plurality of the first grooves are provided and are spaced apart from each other at a certain distance interval. A plurality of the second grooves are provided and can be spaced apart from each other at a certain angular interval. Also, a plurality of the third grooves are provided and can be spaced apart from each other at a certain angular interval.

[0068] The polishing layer may include a plurality of the first grooves at a certain pitch interval. Referring to FIG. 3, the pitch interval p of the first groove 110 means the linear distance between the centers of the bottom surfaces 112 of any two first grooves.

[0069] Specifically, the polishing layer may include the first grooves at a pitch interval of 1 mm to 10 mm. Or, the polishing layer may include the first grooves at a pitch interval of 1 mm to 5 mm. Or, the polishing layer may include the first grooves at a pitch interval of 2 mm to 4 mm.

[0070] Also, the polishing layer may include the second grooves at a certain angle, for example, at an interval of 10° to 50°, 15° to 45°, or 20° to 40°. Also, the polishing layer may include the third grooves at a certain angle, for example, at an interval of 10° to 50°, 15° to 45°, or 20° to 40°.

[0071] [Other components] Referring to FIGS. 3 and 4, the polishing pad may further include a support layer 200 disposed on the lower surface of the polishing layer 100.

[0072] The support layer serves to absorb and disperse the impact applied to the polishing layer while supporting the polishing layer. The hardness of the support layer may be smaller than the hardness of the polishing layer. The support layer may include a non-woven fabric or a porous pad.

[0073] The support layer may include voids. The voids included in the support layer may have a structure of open cells. The voids included in the support layer may have a shape extending in the thickness direction of the support layer. Also, the porosity of the support layer may be larger than the porosity of the polishing layer.

[0074] Further, the polishing pad may further include an adhesive layer 300 disposed between the polishing layer 100 and the support layer 200. The adhesive layer serves to bond the polishing layer and the support layer to each other. Furthermore, the adhesive layer may suppress the leakage of the polishing liquid from under the support layer from the upper part of the polishing layer.

[0075] 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.

[0076] The hot melt adhesive may be one or more selected from the group consisting of polyurethane-based resins, polyester-based resins, ethylene-vinyl acetate-based resins, polyamide-based resins, and polyolefin-based resins. Specifically, the hot melt adhesive may be one or more selected from the group consisting of polyurethane-based resins and polyester-based resins.

[0077] The thickness of the adhesive layer is 5μm to 30μm, specifically, 20μm to 30μm, and more specifically, 23μm to 27μm.

[0078] Further, the polishing pad may further include a window in the polishing layer. The window measures the flatness and thickness of the wafer surface in-situ, contributing to the determination of the end point of the CMP process.

[0079] For example, the polishing layer includes a first through-hole in the thickness direction, and a window may be inserted into the first through-hole. Further, the support layer includes a second through-hole in the thickness direction, and the first through-hole and the second through-hole may be connected to each other.

[0080] The window may be formed from a composition containing a urethane prepolymer and a curing agent. Preferably, the window is non-foamed and may not have fine bubbles inside.

[0081] 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.

[0082] [Method for manufacturing a polishing pad] The method for manufacturing a polishing pad according to the above embodiment includes: (1) manufacturing a polishing layer having a polishing surface; (2) forming a plurality of first grooves having a circular shape sharing the center of the polishing surface in the polishing layer; and (3) forming a plurality of second grooves radially formed from a point 10% to 90% of the radius of the polishing surface from the center of the polishing surface to the outer periphery in the polishing layer. The steps (2) and (3) may be performed sequentially or simultaneously.

[0083] Further, the method for manufacturing a polishing pad may further include, in addition to the steps (1) to (3), (4) forming a plurality of third grooves radially formed from the center of the polishing surface to the outer periphery in the polishing layer. The steps (2) to (4) may be performed sequentially or simultaneously. Alternatively, the step (2) may be performed first, and the steps (3) and (4) may be performed simultaneously. Hereinafter, each step will be specifically described.

[0084] In the step (1), a polishing layer including a polishing surface is manufactured. The polishing layer may include a urethane-based polymer manufactured from a composition including a urethane prepolymer, a curing agent, a foaming agent, and other additives.

[0085] A prepolymer generally means a polymer having a relatively low molecular weight whose degree of polymerization is terminated at an intermediate stage in order to facilitate the molding of the final product.

[0086] The prepolymer can be molded by itself or after reacting with other polymerizable compounds. Specifically, the urethane prepolymer is prepared by reacting an isocyanate compound and a polyol and may contain unreacted isocyanate groups (NCO). The isocyanate compound and the polyol compound are not particularly limited as long as they can be used in the preparation of the urethane polymer.

[0087] The curing agent can be one or more of an amine compound and an alcohol compound. Specifically, the curing agent may contain one or more compounds selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols.

[0088] The foaming agent is not particularly limited as long as it is usually used for forming voids in the polishing pad. For example, the foaming agent can be one or more selected from a solid-phase foaming agent having a hollow structure, a liquid-phase foaming agent using a volatile liquid, and an inert gas.

[0089] In the step (2), a plurality of first grooves having a circular shape sharing the center of the polishing surface are formed in the polishing layer. Also, in the step (3), a plurality of second grooves radially formed from a point 10% to 90% of the radius of the polishing surface from the center of the polishing surface to the outer contour are formed in the polishing layer.

[0090] At this time, the depths of the second groove and the third groove can be formed to be the same as or deeper than the depth of the first groove. For this purpose, the second groove and the third groove can be formed after the first groove. However, if the second groove is formed first, it may be difficult and cumbersome to form it deeper than the first groove in terms of process.

[0091] In addition, the specific configurations such as the depths, widths, and intervals of the first groove, the second groove, and the third groove are the same as those exemplified in the above-mentioned polishing pad.

[0092] The formation of the first groove, the second groove, and the third groove can be performed by cutting and removing a part of the polishing surface. For example, the cutting can be performed using a tip. The polishing surface of the polishing layer can be cut by the tip to form a groove. Specifically, after fixing the tip to contact the polishing surface of the polishing layer, the polishing pad including the polishing layer is rotated or moved in a desired direction, and a part of the surface of the polishing layer is removed to form 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 the cutting.

[0093] In addition, the manufacturing method of the polishing pad may further include a step of processing the corner where the polishing surface and the inner surface meet into a curved surface after the formation of the groove.

[0094] The curved surface processing can be formed by removing a part of the corner where the polishing surface and the inner surface of the groove meet. The curved surface processing can be performed using a grinder or a choke. Specifically, the curved surface processing can be performed by removing a part of the corner where the polishing surface and the inner surface of the groove meet so that the radius of curvature becomes 0.1 mm to 5 mm, 0.1 mm to 2 mm, or 0.3 mm to 1.5 mm. When the radius of curvature is within the above range, the occurrence of defects such as scratches on the surface of the wafer during the CMP process can be effectively prevented.

[0095] The above-mentioned curved surface processing can be performed using a grinder. Further, the grinder may include a grinding surface. That is, the angle where the polishing surface meets the inner surface of the groove can be processed into a curved surface by the grinding surface of the grinder.

[0096] Also, the grinder can process the angle where the inner surface of the groove meets the polishing surface into a curved surface while rotating. At this time, the rotational speed of the grinder can be 1000 rpm to 50000 rpm, 2000 rpm to 35000 rpm, or 5000 rpm to 20000 rpm.

[0097] The groove forming step and the curved surface processing step can be performed continuously. As an example, the tip for groove forming and the grinder or the chuck for curved surface processing are positioned adjacent to each other, and groove forming and curved surface processing can be continuously performed on the polishing surface.

[0098] [Method for manufacturing a semiconductor device] A semiconductor device can be manufactured by chemical mechanical polishing using the above-mentioned polishing pad.

[0099] A method for manufacturing a semiconductor device according to one implementation example includes a step of polishing the surface of a semiconductor substrate using the above-mentioned polishing pad. Specifically, the method for manufacturing the semiconductor device may include a step of providing the polishing pad according to the implementation example, and a step of relatively rotating the polishing surface of the polishing layer and the surface of the semiconductor substrate so as to be in contact with each other to polish the surface of the semiconductor substrate.

[0100] Figure 2 shows a semiconductor device manufacturing process using a polishing pad according to one implementation example.

[0101] First, after mounting the polishing pad 400 according to the one implementation example on the platen 500, the semiconductor substrate 900 to be polished is disposed on the polishing pad 400. At this time, the surface to be polished of the semiconductor substrate 900 is in direct contact with the polishing surface of the polishing pad 400. For polishing, polishing slurry 700 can be sprayed onto the polishing pad via a nozzle. The flow rate of the polishing slurry 700 supplied via the nozzle is selected according to the purpose within the range of about 10 cm 3 / min to about 1000 cm 3 / min, for example, it can be about 50 cm 3 / min to about 500 cm 3 / min, but is not limited thereto.

[0102] Thereafter, the semiconductor substrate 900 and the polishing pad 400 rotate relative to each other, and the surface of the semiconductor substrate 900 can be polished. At this time, the rotation direction of the semiconductor substrate 900 and the rotation direction of the polishing pad 400 may be the same direction or the opposite direction. The rotation speeds of the semiconductor substrate 900 and the polishing pad 400 are each selected according to the purpose within the range of about 10 rpm to about 500 rpm, for example, it can be about 30 rpm to about 200 rpm, but is not limited thereto.

[0103] The semiconductor substrate 900 is mounted on the polishing head 810 and then pressed against the polishing surface of the polishing pad 400 with a predetermined load, and then its surface can be polished. The load applied to the surface of the semiconductor substrate 900 and the polishing surface of the polishing pad 400 by the polishing head 810 is selected according to the purpose within the range of about 1 gf / cm 2 to about 1000 gf / cm 2 , for example, it can be about 10 gf / cm 2 to about 800 gf / cm 2 , but is not limited thereto.

[0104] In one implementation example, the semiconductor substrate 900 to be polished may include an oxide film, a tungsten film, or a composite film thereof. Specifically, the semiconductor substrate 900 may include an oxide film, a tungsten film, or a composite film of an oxide film and a tungsten film. The composite film of the oxide film and the tungsten film may be a multilayer film in which the tungsten film is laminated on one surface of the oxide film, or may be a single-layer film in which an oxide region and a tungsten region are mixed in one layer. When the object to be polished has such film quality characteristics and at the same time the polishing pad has the characteristics according to the implementation example, the semiconductor device manufactured by the method for manufacturing a semiconductor device may minimize defects.

[0105] In one implementation example, the method for manufacturing a semiconductor device may further include, in the step of polishing the object to be polished, supplying either one of the slurry for polishing the oxide film and the slurry for polishing the tungsten film, or sequentially supplying the slurry for polishing the oxide film and the slurry for polishing the tungsten film to the polishing surface.

[0106] For example, when the semiconductor substrate as the object to be polished includes an oxide film, the method for manufacturing a semiconductor device may include the step of supplying the slurry for polishing the oxide film. When the semiconductor substrate includes a tungsten film, the method for manufacturing a semiconductor device may include the step of supplying the slurry for polishing the tungsten film. When the semiconductor substrate includes a composite film of an oxide film and a tungsten film, the method for manufacturing a semiconductor device may include the step of sequentially supplying the slurry for polishing the oxide film and the slurry for polishing the tungsten film to the polishing surface. At this time, depending on the process, the slurry for polishing the oxide film may be supplied first and then the slurry for polishing the tungsten film may be supplied later, or the slurry for polishing the tungsten film may be supplied first and then the slurry for polishing the oxide film may be supplied later.

[0107] In one implementation example, the method for manufacturing the semiconductor device may further include, in order to maintain the polishing surface of the polishing pad 400 in a state suitable for polishing, a step of processing the polishing surface of the polishing pad 400 by a conditioner 600 simultaneously with the polishing of the semiconductor substrate 900.

[0108] (Example) Examples will be described below, but the realizable range is not limited to these.

[0109] (Example 1: Manufacturing of Polishing Pad) Step 1: Manufacturing of Polishing Layer A casting device equipped with tanks and input lines for supplying a prepolymer, a curing agent, an inert gas, and a reaction regulator respectively was prepared. The prepolymer tank was filled with an NCO-terminated urethane prepolymer (NCO 8.0%, product name: PUGL-450D, SKC Co., Ltd.), the curing agent tank was filled with bis(4-amino-3-chlorophenyl)methane (ISHIHARA Co., Ltd.), the inert gas tank was filled with argon gas, and the reaction regulator tank was filled with a tertiary amine-based reaction accelerator (product name A1, AIR PRODUCTS Co., Ltd.). The prepolymer, curing agent, inert gas, and reaction regulator were stirred while being fed into the mixing head at a constant rate through their respective input lines. At this time, the prepolymer and the curing agent were fed while adjusting the equivalent amount in the reactor and maintaining the total feed amount at 10 kg / min. Also, the reaction regulator was constantly fed in an amount of 0.5% (by weight) based on the total feed amount of the prepolymer and the curing agent. Further, the inert gas was constantly fed in an amount of 20% (by volume) based on the total feed amount of the prepolymer and the curing agent. The stirred raw material was discharged into a mold (1000 mm × 1000 mm × 3 mm) to complete the reaction, and a solid cake-shaped molded body was obtained. Then, the upper and lower ends of the molded body were each cut by 0.5 mm in thickness to obtain a polishing layer with a thickness of 2 mm.

[0110] Step 2: Formation of First Groove (Concentric Groove) Using a chip, a concentric first groove was formed on the polished surface of the polishing layer. Specifically, after fixing the chip so as to be in contact with the polished surface of the polishing layer, the polishing pad including the polishing layer was rotated to remove a part of the surface of the polishing layer, thereby forming a groove for the first groove. A total of 117 (pitch interval 3.047 mm) first grooves (concentric grooves) were formed in a circular shape sharing the center of the polished surface, and each first groove was formed with a width of 0.47 mm and a depth of 0.846 mm.

[0111] Step 3: Formation of the second groove and the third groove (radial grooves) Using a chip, a radial second groove and a third groove were formed on the polished surface of the polishing layer. Specifically, after fixing the chip so as to be in contact with the polished surface of the polishing layer, the polishing pad including the polishing layer was moved to remove a part of the surface of the polishing layer, thereby forming a groove for the second groove and the third groove. The second groove started from the 30th first groove formed from the center of the polished surface and was formed radially to the edge of the polished surface. The third groove started from the center of the polished surface and was formed radially to the edge of the polished surface. A total of 16 second grooves were formed at an angular interval of about 22.5°, and a total of 16 third grooves (starting from the center) were also formed at an angular interval of about 22.5°. These second grooves and third grooves were formed alternately with each other, and the angular interval between the second groove and the third groove was about 11.25°. Also, each second groove was formed with a width of 0.96 mm and a depth of 1.012 mm, and each third groove was also formed with a width of 0.96 mm and a depth of 1.012 mm.

[0112] As a result, a polishing pad was obtained in which a first groove (concentric groove), a second groove (radial groove starting from the 30th concentric groove from the center), and a third groove (radial groove starting from the center) were formed on the polished surface.

[0113] (Examples 2 and 3: Manufacture of the polishing pad) The same procedure as in Example 1 was repeated, but the starting position of the second groove was changed as shown in Table 1 below, and the individual groove dimensions were adjusted as shown in Table 2 below to fabricate a polishing pad.

[0114] (Comparative Example 1: Manufacture of Polishing Pad) The same procedure as in Example 1 was repeated, but the second groove and the third groove were not formed, and a polishing pad having only the first groove formed as shown in Table 1 and Table 2 below was fabricated.

[0115] (Comparative Example 2: Manufacture of Polishing Pad) The same procedure as in Example 1 was repeated, but the second groove was not formed, and a polishing pad having only the first groove and the third groove formed as shown in Table 1 and Table 2 below was fabricated.

[0116]

Table 1

[0117]

Table 2

[0118] (Test Example 1: CMP Evaluation) Using the polishing pads manufactured in the above Examples and Comparative Examples, CMP evaluation was performed as follows. (1) Removal rate After installing a 300-mm-diameter silicon wafer on which silicon oxide was deposited by a CVD process in a CMP polishing apparatus, the wafer was set on a platen with the porous polyurethane polishing pad attached thereto with the silicon oxide film of the silicon wafer facing downward. Thereafter, while feeding ceria slurry calcined at 250 mL / min onto the polishing pad under the conditions of a polishing load of 4.0 psi and a polishing pad rotation speed of 150 rpm, the platen was rotated at 150 rpm for 60 seconds to polish the silicon oxide film. After polishing, the silicon wafer was removed from the carrier, mounted on a spin dryer, washed with deionized water (DIW), and then dried with nitrogen for 15 seconds. The change in film thickness before and after polishing of the dried silicon wafer was measured using a spectroscopic interference wafer thickness meter (model name: SI-F80R, manufactured by Keyence Corporation). Thereafter, the polishing rate was calculated using the following formula. Polishing rate (Å / min) = Change in film thickness before and after polishing (Å) / Polishing time (min)

[0119] (2) WIWNU (Within Wafer Non Uniformity) After measuring the polishing rate at 47 points on a silicon wafer polished for 1 minute under the same polishing conditions as in (1) above, WIWNU was calculated using the following formula. The positions of the individual points at which the polishing rate was measured were randomly selected. JPEG2025077989000007.jpg1471 Here, RR_stdev is the standard deviation of the measured values of the polishing rate (Å / min), and RR_avg is the average of the measured values of the polishing rate (Å / min).

[0120] The standard deviation RR_stdev of the polishing rate can be calculated by the following calculation. JPEG2025077989000008.jpg1869 Here, RR is the measured value of the polishing rate at an individual point, RR_avg is the average of the measured values of the polishing rate, and n is the number of measured values of the polishing rate.

[0121] The above test results were shown in the following table. Also, the wafer profile after CMP using each polishing pad was shown in FIG. 5.

[0122]

Table 3

[0123] As a result of the tests, it was confirmed that in Examples 1 to 3, the wafer profile changed due to the introduction of the second group, and in particular, due to the profile change in the central region of the wafer, the WIWNU value decreased. From this, it can be seen that the introduction of the second group and the change in the starting position can improve the CMP process performance.

Description of Reference Numerals

[0124] 100: Polishing layer 101: Polishing surface 200: Support layer 300: Adhesive layer 110: First group 120: Second group 130: Third group 111, 121: Inner surface 112, 122: Bottom surface h1: Depth of the first group h2: Depth of the second group w1: Width of the first group w2: Width of the second group t: Thickness of the polishing layer p: Pitch between peaks of the first group A1 - A1', A2 - A2': Cutting lines 400: Polishing pad 500: Platen 600: Conditioner 700: Polishing slurry 810: Polishing head 820: Carrier 900: Semiconductor substrate (wafer)

Claims

1. a polishing layer having a polishing surface; The polishing layer is A plurality of first grooves having a circular shape sharing a common center on the polishing surface; a plurality of second grooves formed radially from a point 10% to 90% away from the center of the polishing surface by a radius of the polishing surface to an outer periphery; A polishing pad, in which a silicon oxide film of a silicon wafer is polished on the polishing surface using a ceria slurry, and then a polishing rate is measured at 30 or more randomly positioned points, and a WIWNU (Within Wafer Non Uniformity) calculated by the following formula is 15% or less: Where: RR_stdev is the standard deviation of the polishing rate (Å / min) measurements; RR_avg is the average of the measured polishing rate (Å / min).

2. The WIWNU is 1% to 8%, 2. The polishing pad of claim 1, wherein the RR_avg is between 2500 Å / min and 4000 Å / min.

3. 3. The polishing pad of claim 2, wherein the RR_avg is between 3200 Å / min and 3400 Å / min.

4. The polished surface is The first groove includes 50 to 150 pieces, 2. The polishing pad according to claim 1, comprising 2 to 50 second grooves.

5. The width of the first groove is 0.1 mm to 1 mm; 5. The polishing pad of claim 4, wherein the second groove has a width of 0.5 mm to 1.5 mm.

6. The depth of the first groove is 0.4 mm to 1.2 mm; 6. The polishing pad of claim 5, wherein 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 from a point that is 10% to 39% of the radius of the polishing surface from the center to the outer periphery; (ii) a plurality of second B grooves formed radially from a point that is 40% to 59% of the radius of the polishing surface from the center to the outer periphery; and (iii) A plurality of second C grooves formed radially from a point that is 60% to 90% of the radius of the polishing surface from the center to the outer periphery.

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

9. The polishing layer is The first groove includes 50 to 150 pieces, The second groove includes 4 to 50 pieces, The polishing pad according to claim 8, comprising 4 to 50 of the third grooves.

10. 10. A method for manufacturing a semiconductor device, comprising the step of polishing a surface of a semiconductor substrate with the polishing pad of claim 1.

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