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

Background Art

[0002] In the semiconductor manufacturing process, chemical mechanical polishing (CMP) is a process of mechanically planarizing the uneven portions on the surface of a semiconductor substrate by supplying slurry while contacting a semiconductor substrate such as a wafer attached to a head 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.

[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 includes grooves on the surface for carrying a large flow of slurry and pores for supporting a fine flow.

[0004] For the production 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 polyurethane foam sheet is sliced at the upper and lower surfaces 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). Thus, the grooves provided in the polishing pad play a role of assisting in planarizing 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 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the CMP (Chemical Polishing) process, polishing pads remove film by abrading the wafer surface. However, the fluidity of the slurry varies depending on the type of slurry and the film quality, which affects the polishing rate and the WIWNU (Within Wafer Non-Uniformity) value. Another method to deform the wafer profile is to adjust the process conditions, but this incurs consumption of time and material.

[0008] Therefore, as a result of our research, we have found that by introducing specially designed radial grooves in addition to concentric grooves, the fluidity of the slurry can be improved, and the wafer profile and polishing rate can be changed.

[0009] Therefore, the challenge of the implementation example is to provide a polishing pad with improved slurry fluidity and polishing efficiency, and a method for manufacturing semiconductor devices using the same. [Means for solving the problem]

[0010] To solve the aforementioned problem, an example provides a polishing pad comprising a polishing layer having a polishing surface, wherein the polishing layer comprises 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 edge, and after polishing the silicon oxide film of a silicon wafer with a ceria slurry on the polishing surface, the polishing rate is measured at 30 or more randomly located points, and the WIWNU (Within Wafer Non-Uniformity) calculated by the following formula is 15% or less. JPEG0007835812000001.jpg1471 Here, RR_stdev is the standard deviation of the polishing rate (Å / min) measurements, and RR_avg is the mean of the polishing rate (Å / min) measurements.

[0011] Another example provides a method for manufacturing a semiconductor device, which includes the step of polishing the surface of a semiconductor substrate using the polishing pad. [Effects of the Invention]

[0012] The polishing pad according to the above-described example can improve the fluidity of the slurry and change the wafer profile and polishing rate by introducing specially designed radial second grooves in addition to the concentric first grooves.

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

[0014] Therefore, the polishing pad according to the above-described example can be applied to the manufacturing of semiconductor devices, thereby improving process efficiency and product quality. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 shows a plan view of a polishing pad according to one implementation example. [Figure 2] Figure 2 shows the manufacturing process of a semiconductor device using a polishing pad, as an example of its implementation. [Figure 3] Figure 3 shows a cross-sectional view of the polished layer including the first groove, cut along A1-A1' in Figure 1. [Figure 4] Figure 4 shows a cross-sectional view of the polished layer including the second groove, cut along A2-A2' in Figure 1. [Figure 5]FIG. 5 shows the wafer profile after the CMP process using the polishing pads obtained in Examples 1 to 3 and Comparative Examples 1 and 2.

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 sizes of the respective components in the drawings may be exaggerated or omitted for the purpose of explanation and may differ from the actual sizes 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 these components are formed, connected or coupled directly or indirectly through 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, the singular expression includes the plural expression unless the context clearly has a different meaning.

[0019] In this specification, terms such as first and second 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 component.

[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 there is a contrary description.

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

[0022] In the numerical ranges that limit the size, physical properties, etc., of the components described herein, if numerical ranges limited only by upper limits and numerical ranges limited only by lower limits are given as separate examples, it should be understood that the numerical ranges formed by combining these upper and lower limits are also included in the exemplary ranges.

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

[0024] The abrasive layer may, for example, contain a urethane polymer and may be porous. The urethane polymer may be formed by a curing reaction between a urethane prepolymer and a curing agent. Specifically, the abrasive layer may be manufactured from an abrasive layer composition containing a urethane prepolymer, a curing agent, a foaming agent, and other additives.

[0025] The polishing layer may contain voids. These voids may have a closed-cell structure. The average diameter of the voids may be between 5 μm and 200 μm. Furthermore, the polishing layer may contain voids amounting to 20% to 70% of the total volume of the polishing layer. In other words, the porosity of the polishing layer may be between 20% and 70% of the 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 that shares the center of the polishing surface 101, and a plurality of second grooves 120 that are formed radially from a point 10% to 90% away from the center of the polishing surface to the outer edge.

[0028] The first groove has the effect of reducing the fluidity of the slurry and improving polishing efficiency, while the second groove has the effect of increasing the fluidity of the slurry and discharging the residue generated during the polishing process.

[0029] Thus, the first groove and the second groove play a role in controlling the fluidity of the slurry during the CMP process, and their combination can appropriately adjust the degree of slurry maintenance and renewal, thereby improving polishing efficiency.

[0030] In particular, the second groove does not start from the center of the polishing surface, but from a point a certain distance away from the center. This allows for variations in the fluidity of the slurry in the region of the polishing surface that comes into contact with a semiconductor substrate such as a wafer during the CMP process, thereby adjusting the wafer profile.

[0031] The starting point of the second groove may be, for example, a point located at a distance of 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 polished surface from the center of the polished surface. Specifically, the starting point of the second groove may be a point located at a distance of 10% to 39% of the radius of the polished surface from the center of the polished surface, at a distance of 40% to 59% or at a distance of 60% to 90%.

[0032] In one specific example, the second groove 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 polished surface away from the center to the outer edge, (ii) A plurality of second B grooves formed radially from a point 40% to 59% of the radius of the polished surface from the center to the outer edge, and (iii) A plurality of second C grooves formed radially from a point 60% to 90% of the radius of the polished surface from the center to the outer edge.

[0033] Referring to Figure 1, the polishing pad may further include a plurality of third grooves 130 that are formed radially from the center to the outer edge of the polishing surface 101. By providing third grooves in addition to the second grooves as radial grooves, the fluidity of the slurry can be increased, and the effect of discharging residue generated during the polishing process can be further improved.

[0034] Figure 2 shows the manufacturing process of a semiconductor device using a polishing pad, as an example of its implementation. Referring to Figure 2, after mounting a polishing pad 400 according to one implementation example onto the platen 500, the semiconductor substrate 900 to be polished is placed on the polishing surface of the polishing pad 400. At this time, the surface of the semiconductor substrate 900 to be polished 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 through a nozzle. Subsequently, 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 in opposite directions. With the semiconductor substrate 900 mounted on the polishing head 810, it is pressed against the polishing surface of the polishing pad 400 with a predetermined load, and then its surface can be polished.

[0035] The polishing pad according to the above-described example can improve slurry flow in the CMP process and change the wafer profile and polishing rate by introducing specially designed radial grooves in addition to concentric grooves. In particular, the introduction of the second groove can improve CMP slurry flow, change the polishing rate and wafer profile in the central region of the wafer, reduce the WIWNU value, and increase pad life.

[0036] WIWNU is a value related to polishing flatness and uniformity during the CMP process using a polishing pad. It can be calculated by performing the CMP process on a semiconductor device such as a wafer using a polishing pad, measuring the polishing rate at numerous points, and then using the following formula. JPEG0007835812000002.jpg1471 Here, RR_stdev is the standard deviation of the polishing rate (Å / min) measurements, and RR_avg is the mean of the polishing rate (Å / min) measurements.

[0037] The standard deviation of the polishing rate (RR_stdev) can be calculated as follows. JPEG0007835812000003.jpg1869 Here, RR is the polishing rate measurement at each individual point, RR_avg is the average of the polishing rate measurements, and n is the number of polishing rate measurements.

[0038] Polishing pads in which the aforementioned WIWNU is below a specific level can be used to manufacture high-quality semiconductor devices 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 a ceria slurry on the polishing surface, the polishing rate is measured at 30 or more randomly located points, and the WIWNU calculated using the above formula is 15% or less.

[0040] 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. On the other hand, the lower limit of the WIWNU is not particularly limited, but 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%, and more specifically, 1% to 8%.

[0041] Furthermore, the polishing rate can be calculated using 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 of the polishing rate (RR_stdev) may 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 and minimum values ​​of the standard deviation of the polishing rate (RR_stdev) may 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] Furthermore, the difference between the maximum and minimum values ​​of the polishing rate measurements may 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 and minimum values ​​of the polishing rate measurements may 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] Furthermore, the average polishing rate (RR_avg) may 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 may be 1% to 8%, and the RR_avg may be 2500 Å / min to 4000 Å / min. In another specific example, the RR_avg may be 3200 Å / min to 3400 Å / min. Within the range of the preferred polishing rate, it may be more advantageous to obtain the desired level of CMP process effect.

[0046] [Groove] Referring to Figure 1, the polishing layer 100 of the polishing pad includes a plurality of first grooves 110 having a circular shape that shares a common 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 away from the center to the outer edge. The polishing pad may further include a plurality of third grooves 130 formed radially from the center to the outer edge of the polishing surface 101.

[0047] The number of 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 also 200 or less, 190 or less, 170 or less, 150 or less, 130 or less, or 120 or less, and specifically, it may be 10 to 200, 50 to 170, 70 to 150, or 90 to 130.

[0048] Furthermore, the number of second grooves formed in the polishing layer may be 2 or more, 4 or more, 6 or more, 8 or more, 10 or more, or 12 or more, and may also be 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.

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

[0050] In other specific examples, the polishing layer may contain 50 to 150 of the first grooves, 4 to 50 of the second grooves, and 4 to 50 of the third grooves.

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

[0052] Referring to Figures 3 and 4, the first groove and the second groove may include inner surfaces 111, 121 perpendicular to the polishing surface and bottom surfaces 112, 122 parallel to the polishing surface.

[0053] Referring to Figure 3, the width w1 of the first groove 110 is the measured width of the bottom surface 112 of the first groove, and the depth h1 of the first groove 110 is the measured vertical straight-line distance between the bottom surface 112 of the first groove and the polished 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 also 1 mm or less, 0.9 mm or less, or 0.8 mm or less, and as a specific example, it may be between 0.1 mm and 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 also 1.2 mm or less, 1.1 mm or less, or 1.0 mm or less, and as a specific example it may be 0.4 mm to 1.2 mm.

[0056] Referring to Figure 3, the width w2 of the second groove 120 is the measured width of the bottom surface 122 of the second groove, and the depth h2 of the second groove 120 is the measured vertical straight-line distance between the bottom surface 122 of the second groove and the polished 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 also 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, and as a specific example, it may be between 0.5 mm and 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 also 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, and as a specific example, it may be between 0.5 mm and 1.5 mm.

[0059] In one specific example, 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.

[0060] In other specific examples, 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.

[0061] The depth of the second groove may be the same as or greater 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 greater than 100% to 250% 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%, or for example, 125% to 150%. When the depth is within this range, the fluidity of the slurry is improved, allowing for more efficient removal of residue generated during the polishing process, while simultaneously minimizing defects on the polished surface while ensuring an appropriate polishing rate when polishing the wafer with the polishing pad.

[0062] Furthermore, 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 this range, the fluidity of the slurry can be further improved while preventing deformation of the polishing layer due to groove formation.

[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%, or for example, 100% to 160% of the width of the first groove. When the width is within this range, it is advantageous in improving the fluidity of the slurry while ensuring a sufficient polishing area.

[0064] Furthermore, the width of the third groove is the value obtained by measuring the width of the bottom surface of the third groove, and the depth of the third groove is the value obtained by measuring the vertical straight-line distance between the bottom surface of the third groove and the polished 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 also 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, and as a specific example, it may be between 0.5 mm and 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 also 1.5 mm or less, 1.4 mm or less, or 1.3 mm or less, and as a specific example, it may be between 0.5 mm and 1.5 mm.

[0067] The first grooves may be provided in multiple quantities and separated from each other by a certain distance, and the second grooves may be provided in multiple quantities and separated from each other by a certain angular interval. Furthermore, the third grooves may be provided in multiple quantities and separated from each other by a certain angular interval.

[0068] The polishing layer may contain multiple first grooves at a constant pitch interval. Referring to Figure 3, the pitch interval p of the first grooves 110 means the straight-line distance between the centers of the bottom surfaces 112 of any two first grooves.

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

[0070] Furthermore, the polishing layer may have the second grooves at a certain angle, for example, between 10° and 50°, between 15° and 45°, or between 20° and 40°. Furthermore, the polishing layer may have the third grooves at a certain angle, for example, between 10° and 50°, between 15° and 45°, or between 20° and 40°.

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

[0072] The support layer supports the polishing layer and absorbs and disperses 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 nonwoven fabric or a porous pad.

[0073] The support layer may contain voids. The voids contained in the support layer may have an open-cell structure. The voids contained in the support layer may have a shape that extends in the thickness direction of the support layer. Furthermore, the porosity of the support layer may be greater than that of the polished layer.

[0074] Furthermore, 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. Moreover, the adhesive layer can prevent the polishing liquid from leaking from the top of the polishing layer to the bottom of the support layer.

[0075] The adhesive layer may include a hot melt adhesive. More 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 resins, polyester resins, ethylene-vinyl acetate resins, polyamide resins, and polyolefin resins. Specifically, the hot-melt adhesive may be one or more selected from the group consisting of polyurethane resins and polyester resins.

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

[0078] Furthermore, the polishing pad may be further provided with a window in the polishing layer. The window allows for in-situ measurement of the flatness and thickness of the wafer surface, which helps in determining the end point of the CMP process.

[0079] For example, the polishing layer has a first through-hole in the thickness direction, and a window can be inserted into the first through-hole. The support layer also has a second through-hole in the thickness direction, and the first and second through-holes can be connected to each other.

[0080] The window may be formed from a composition comprising a urethane-based prepolymer and a curing agent. Preferably, the window is non-foamed and does not need to contain fine bubbles.

[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] [Manufacturing method for polishing pads] The method for manufacturing a polishing pad according to the above-described embodiment includes the steps of: (1) manufacturing a polishing layer having a polishing surface; (2) forming a plurality of first grooves in the polishing layer that are circular in shape and share the center of the polishing surface; and (3) forming a plurality of second grooves in the polishing layer that are formed radially from a point 10% to 90% away from the center of the polishing surface to the outer edge. Steps (2) and (3) may be performed sequentially or simultaneously.

[0083] Furthermore, the method for manufacturing the polishing pad may further include, in addition to steps (1) to (3), step (4) forming a plurality of third grooves in the polishing layer that are radially formed from the center to the outer edge of the polishing surface. Steps (2) to (4) may be performed sequentially or simultaneously. Alternatively, step (2) may be performed first, followed by steps (3) and (4) simultaneously. The following provides a detailed explanation for each stage.

[0084] In step (1) above, an abrasive layer including an abrasive surface is manufactured. The abrasive layer may contain a urethane polymer manufactured from a composition comprising a urethane prepolymer, a curing agent, a foaming agent, and other additives.

[0085] A prepolymer generally refers to a polymer with a relatively low molecular weight whose polymerization process has been stopped at an intermediate stage to facilitate the molding of the final product.

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

[0087] The curing agent may be one or more amine compounds and alcohol compounds. 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 one that is commonly used for forming voids in polishing pads. For example, the foaming agent may 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 step (2), a plurality of first grooves having a circular shape and sharing the center of the polished surface are formed in the polishing layer. In step (3), a plurality of second grooves are formed in the polishing layer, radiating from a point 10% to 90% away from the center of the polished surface to the outer edge.

[0090] In this case, the depths of the second groove and the third groove can be made the same as or deeper than the depth of the first groove. For this purpose, the second groove and the third groove can be made after the first groove, but if the second groove is made first, it may be complicated and difficult to make it deeper than the first groove.

[0091] Furthermore, the specific configuration of the first groove, second groove, and third groove, such as depth, width, and spacing, is the same as that exemplified in the polishing pad described above.

[0092] The formation of the first groove, the second groove, and the third groove may be carried out by cutting and removing a portion of the polishing surface. For example, the cutting may be carried out using a tip. The polishing surface of the polishing layer may be cut by the tip to form grooves. Specifically, after fixing the tip so as to contact the polishing surface of the polishing layer, the polishing pad containing the polishing layer may be rotated or moved in a desired direction to remove a portion of the surface of the polishing layer and form grooves. 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] Furthermore, the method for manufacturing 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 groove has been formed.

[0094] The curved surface can be formed by partially removing the corner where the polished surface and the inner surface of the groove meet. The curved surface can be performed using a grinder or chalk. Specifically, the curved surface can be performed by partially removing the corner where the polished surface and the inner surface of the groove meet, so that the radius of curvature is 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 wafer surface during the CMP process can be effectively prevented.

[0095] The curved surface machining can be performed using a grinder. The grinder may also include a grinding surface. That is, the corner where the polished surface and the inner surface of the groove meet can be machined into a curved surface by the grinding surface of the grinder.

[0096] Furthermore, the grinder can machine the corner where the inner surface of the groove meets the polishing surface into a curved surface while rotating. In this case, the rotational speed of the grinder may be 1,000 rpm to 50,000 rpm, 2,000 rpm to 35,000 rpm, or 5,000 rpm to 20,000 rpm.

[0097] The groove forming process and the curved surface machining process can be performed continuously. For example, the groove forming chip and the grinder or chalk for curved surface machining can be positioned adjacent to each other, allowing groove forming and curved surface machining to be performed continuously on the polished surface.

[0098] [Manufacturing method for semiconductor element] Using the polishing pad described above, semiconductor devices can be manufactured by chemical-mechanical polishing.

[0099] A method for manufacturing a semiconductor device according to one embodiment includes the step of polishing the surface of a semiconductor substrate using the polishing pad described above. Specifically, the method for manufacturing a semiconductor device may include the step of providing the polishing pad according to the embodiment, and the step of polishing the surface of the semiconductor substrate by rotating the polishing pad and the surface of the semiconductor substrate relative to each other so that the polishing surface of the polishing layer and the surface of the semiconductor substrate come into contact with each other.

[0100] Figure 2 shows a semiconductor device manufacturing process using a polishing pad, based on one implementation example.

[0101] First, the polishing pad 400 according to the above embodiment is mounted on the platen 500, and then the semiconductor substrate 900 to be polished is placed on the polishing pad 400. At this time, the surface of the semiconductor substrate 900 to be polished 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 through a nozzle. The flow rate of the polishing slurry 700 supplied through the nozzle is approximately 10 cm³. 3 / min ~ approx. 1000cm 3 The range is selected according to the purpose within the given timeframe, for example, approximately 50 cm. 3 / min ~ approx. 500cm 3 It could be, but is not limited to, / minute.

[0102] Subsequently, the semiconductor substrate 900 and the polishing pad 400 rotate relative to each other, so that the surface of the semiconductor substrate 900 can be polished. 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 are selected according to the purpose, within a range of approximately 10 rpm to approximately 500 rpm, for example, approximately 30 rpm to approximately 200 rpm, but are not limited thereto.

[0103] The semiconductor substrate 900, while mounted on the polishing head 810, is pressed against the polishing surface of the polishing pad 400 with a predetermined load, and then its surface is polished. The load applied by the polishing head 810 to the surface of the semiconductor substrate 900 and the polishing surface of the polishing pad 400 is approximately 1 gf / cm². 2 ~About 1000gf / cm 2 The appropriate value is selected within the range depending on the purpose, for example, approximately 10 gf / cm³. 2 ~About 800gf / cm 2 It is possible, but not limited to this.

[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 a monolayer film in which oxide regions and tungsten regions are mixed within a single layer. As the object to be polished has such film properties and the polishing pad has the properties according to the implementation example, defects can be minimized in the semiconductor device manufactured by the semiconductor device manufacturing method.

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

[0106] For example, if the semiconductor substrate to be polished contains an oxide film, the method for manufacturing the semiconductor device may include a step of supplying the slurry for polishing the oxide film. If the semiconductor substrate contains a tungsten film, the method for manufacturing the semiconductor device may include a step of supplying the slurry for polishing the tungsten film. If the semiconductor substrate contains a composite film of an oxide film and a tungsten film, the method for manufacturing the semiconductor device may include a step of sequentially supplying the slurry for polishing the oxide film and the slurry for polishing the tungsten film to the polishing surface. In this case, 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 embodiment, the method for manufacturing the semiconductor device may further include a step of processing the polishing surface of the polishing pad 400 with a conditioner 600 at the same time as polishing the semiconductor substrate 900, in order to maintain the polishing surface of the polishing pad 400 in a state suitable for polishing.

[0108] (Examples) Examples are described below, but the feasible scope is not limited to these.

[0109] (Example 1: Manufacturing of polishing pads) Stage 1: Manufacturing of the polishing layer A casting apparatus was prepared, equipped with tanks and input lines for supplying the prepolymer, curing agent, inert gas, and reaction modifier, respectively. The prepolymer tank was filled with an NCO-terminated urethane prepolymer (NCO 8.0%, product name: PUGL-450D, SKC Corporation), the curing agent tank was filled with bis(4-amino-3-chlorophenyl)methane (ISHIHARA Corporation), the inert gas tank was filled with argon gas, and the reaction modifier tank was filled with a tertiary amine reaction accelerator (product name: A1, AIRPRODUCT Corporation). The prepolymer, curing agent, inert gas, and reaction modifier were added to the mixing head at a constant rate through their respective input lines while being stirred. During this process, the prepolymer and curing agent were added while maintaining a total input rate of 10 kg / min, matching the equivalent volume of the reactor. The reaction modifier was added at a constant rate of 0.5% (by weight) of the total input amount of the prepolymer and curing agent. Furthermore, an inert gas was added at a constant rate of 20% (by volume) of the total amount of prepolymer and curing agent added. The stirred raw materials were extruded into a mold (1000 mm × 1000 mm × 3 mm) to complete the reaction and obtain a solid-phase cake-like molded body. Subsequently, the upper and lower ends of the molded body were cut to a thickness of 0.5 mm each to obtain a polished layer with a thickness of 2 mm.

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

[0111] Stage 3: Formation of the second and third grooves (radial grooves) Using a tip, radial second and third grooves were formed on the polishing surface of the polishing layer. Specifically, after fixing the tip in contact with the polishing surface of the polishing layer, the polishing pad containing the polishing layer was moved to remove a portion of the surface of the polishing layer, thereby forming grooves for the second and third grooves. The second grooves were formed radially from the first groove, which was formed 30th from the center of the polishing surface, to the edge of the polishing surface, and the third grooves were formed radially from the center of the polishing surface to the edge of the polishing surface. A total of 16 second grooves were formed at angular intervals of approximately 22.5°, and a total of 16 third grooves (starting from the center) were also formed at angular intervals of approximately 22.5°. These second and third grooves were formed alternately with respect to each other, and the angular interval between the second and third grooves was approximately 11.25°. Furthermore, 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 polishing surface.

[0113] (Examples 2 and 3: Manufacturing of polishing pads) 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 dimensions of each groove were adjusted as shown in Table 2 below to produce a polishing pad.

[0114] (Comparative Example 1: Manufacturing of polishing pads) The same procedure as in Example 1 was repeated, but without forming the second and third grooves, a polishing pad was manufactured with only the first groove formed, as shown in Tables 1 and 2 below.

[0115] (Comparative Example 2: Manufacturing of polishing pads) The same procedure as in Example 1 was repeated, but without forming the second groove, a polishing pad was manufactured with only the first groove and the third groove formed, as shown in Tables 1 and 2 below.

[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 A 300 mm diameter silicon wafer, with silicon oxide deposited by the CVD process, was placed in a CMP polishing apparatus. The silicon oxide film of the silicon wafer was then placed face down on a platen to which the porous polyurethane polishing pad had been attached. Subsequently, the silicon oxide film was polished by rotating the platen at 150 rpm for 60 seconds while adding a calcined ceria slurry at a rate of 250 mL / min onto the polishing pad under conditions of a polishing load of 4.0 psi and a polishing pad rotation speed of 150 rpm. After polishing, the silicon wafer was removed from the carrier, placed in a spin dryer, washed with deionized water (DIW), and then dried with nitrogen for 15 seconds. The film thickness change before and after polishing was measured using a spectroscopic interferometric wafer thickness gauge (model name: SI-F80R, Keyence Corporation). The polishing rate was then 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 where the polishing rate was measured were randomly selected. JPEG0007835812000006.jpg1471 Here, RR_stdev is the standard deviation of the polishing rate (Å / min) measurements, and RR_avg is the mean of the polishing rate (Å / min) measurements.

[0120] The standard deviation of the polishing rate, RR_stdev, can be calculated as follows. JPEG0007835812000007.jpg1869 Here, RR is the polishing rate measurement at each individual point, RR_avg is the average of the polishing rate measurements, and n is the number of polishing rate measurements.

[0121] The test results are shown in the table below. Figure 5 shows the wafer profiles after CMP using each polishing pad.

[0122] [Table 3]

[0123] The test results showed that in Examples 1-3, the wafer profile changed due to the introduction of the second groove, and in particular, the WIWNU value decreased due to the profile change in the central region of the wafer. From this, it can be seen that the CMP process performance can be improved by introducing the second groove and changing its starting position. [Explanation of Symbols]

[0124] 100: Polishing layer 101: Polished surface 200:Support layer 300: Adhesive layer 110: 1st Groove 120: 2nd Groove 130: Third Groove 111, 121: Inner surface 112, 122: Base h1: Depth of the first groove h2:Depth of the second groove w1: Width of the first groove w2: Width of the second groove t: thickness of the polished layer p: Peach spacing of the first groove A1-A1', A2-A2': Cutting line 400: Polishing pad 500: Platen 600: Conditioner 700: Polishing slurry 810: Polishing head 820: Carrier 900: Semiconductor substrate (wafer)

Claims

1. It includes an abrasive layer having an abrasive surface, The abrasive layer comprises an abrasive layer composition containing a urethane-based prepolymer, a curing agent, and a foaming agent. A plurality of first grooves having a circular shape that share the center of the polished surface, It includes a plurality of second grooves formed radially from the center to the outer edge, starting from a point 10% to 90% away from the radius of the polished surface, After polishing the silicon oxide film of a silicon wafer using a ceria slurry on the aforementioned polishing surface, the polishing rate is measured at 30 or more randomly located points, and the WIWNU (Within Wafer Non-Uniformity) calculated using the following formula is 1% to 8% for the polishing pad: Here, RR_stdev is the standard deviation of the measured polishing rate (Å / min), RR_avg is the average of the polishing rate (Å / min) measurements, and is between 2500 Å / min and 4000 Å / min.

2. The polishing pad according to claim 1, wherein the RR_avg is 3200 Å / min to 3400 Å / min.

3. The polished surface is The first groove comprises 50 to 150 such grooves. The polishing pad according to claim 1, comprising 2 to 50 of the second grooves.

4. The width of the first groove is 0.1 mm to 1 mm. The polishing pad according to claim 3, wherein the width of the second groove is 0.5 mm to 1.5 mm.

5. The depth of the first groove is 0.4 mm to 1.2 mm. The polishing pad according to claim 4, wherein the depth of the second groove is 0.5 mm to 1.5 mm.

6. The polishing pad according to claim 1, wherein the second groove includes at least one of the following (i) to (iii): (i) Multiple second A grooves formed radially from a point 10% to 39% of the radius of the polished surface from the center to the outer edge, (ii) A plurality of second B grooves formed radially from a point 40% to 59% of the radius of the polished surface from the center to the outer edge, and (iii) A plurality of second C grooves formed radially from a point 60% to 90% of the radius of the polished surface away from the center to the outer edge.

7. The polishing pad according to claim 1, further comprising a plurality of third grooves formed radially from the center to the outer edge of the polishing surface.

8. The aforementioned polished layer is The first groove comprises 50 to 150 such grooves. The aforementioned second groove includes 4 to 50 pieces, The polishing pad according to claim 7, comprising 4 to 50 of the third grooves.

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

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