CMP composite polishing pad

Abstract

To provide a composite polishing pad for CMP with improved polishing performance and lifespan. [Solution] A composite polishing pad for CMP comprising a polymer substrate layer having a number of protrusions formed on its upper surface and a carbon nanotube layer having carbon nanotubes embedded and fixed on its upper surface, wherein the polymer substrate layer comprises a soft polymer layer having a number of protrusions formed on its upper surface and a hard polymer layer laminated on the upper surface of the soft polymer layer, the carbon nanotube layer being provided on the surface of the hard polymer layer, and the carbon nanotubes being embedded in an irregular net form structure on the upper surface of the hard polymer layer.

Description

[Technical Field]

[0001] The present invention relates to a composite polishing pad for CMP containing carbon nanotubes. [Background technology]

[0002] Chemical Mechanical Polishing (CMP) is a key process for flattening and mirror-finishing wafers and glass panels, and is carried out through the mechanical and chemical action of a polishing pad and a slurry containing nanoparticles.

[0003] FIG. 1 is a schematic diagram of a CMP apparatus. In a CMP apparatus, a carrier (3) firmly holds a polishing object (2, e.g., a wafer) and presses the object against a polishing pad (100) fixed to a rotating table (1). Specifically, while the carrier (3) and rotating table (1) rotate independently, a liquid slurry (abrasive) is applied to the polishing pad (100) from a nozzle (5), thereby performing chemical and mechanical polishing. During the polishing process, a conditioner (4) is applied to the polishing pad (100) at a position spaced apart from the polishing object (1), roughening the surface of the polishing pad (100) and maintaining its rough surface condition.

[0004] Polyurethane-based polishing pads are commonly used in CMP equipment. However, conventional polyurethane-based polishing pads have the disadvantage of rapidly wearing out due to friction between the highly hard nanoparticles, the object being polished, and the diamond conditioner during the polishing process, resulting in a short lifespan. Furthermore, due to their irregular surface roughness, they cannot guarantee uniform polishing performance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 10-2021-0002429 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a composite polishing pad for CMP having significantly improved polishing performance and lifespan. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a polymeric substrate layer including a plurality of protrusions molded onto an upper surface thereof; and a carbon nanotube layer comprising carbon nanotubes embedded and fixed to the upper surface of the polymer substrate layer; the polymer substrate layer includes a soft polymer layer having a plurality of protrusions formed on an upper surface thereof, and a hard polymer layer laminated on the upper surface of the soft polymer layer; the carbon nanotube layer is provided on a surface of the hard polymer layer; The carbon nanotubes are embedded in an irregular net form on the upper surface of the hard polymer layer to provide a composite polishing pad for CMP.

[0008] In one embodiment of the present invention, the irregular net-form structure may be a structure formed by scattering carbon nanotubes so that some of the carbon nanotubes overlap each other.

[0009] In one embodiment of the present invention, the soft polymer layer may have a Shore hardness of 20D to 45D. In one embodiment of the present invention, the hard polymer layer may have a Shore hardness of 45D to 70D. In one embodiment of the present invention, the protrusions may have a maximum width of 10 μm to 500 μm and a height of 3 μm to 150 μm.

[0010] In one embodiment of the present invention, the carbon nanotubes may have a diameter of 1 nm to 50 nm and a length of 1 μm to 30 μm. In one embodiment of the present invention, the protrusion may be hemispherical in shape. [Effects of the Invention]

[0011] The composite polishing pad for CMP of the present invention has a polymer substrate layer formed of a laminate of a soft polymer layer and a hard polymer layer, thereby improving the polishing efficiency and life of the polishing pad. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing the structure of a typical CMP apparatus. [Figure 2] 1 is a cross-sectional view schematically showing one embodiment of a composite polishing pad of the present invention. [Figure 3] 1 is a cross-sectional view schematically showing the structure of protrusions included in a composite polishing pad according to one embodiment of the present invention. [Figure 4] 10A and 10B are diagrams illustrating contact patterns between fine protrusions, abrasive particles, and an object to be polished due to differences in mechanical properties of the fine protrusions provided on a polishing pad. [Figure 5] 1A to 1C are diagrams illustrating a method for manufacturing a composite polishing pad according to one embodiment of the present invention. [Figure 6] 1 shows an SEM photograph of a composite polishing pad having carbon nanotubes arranged in a random net form on the upper surface of a polymer substrate layer, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. The same reference numerals are used throughout the specification to refer to similar parts.

[0014] When a component is referred to as being "coupled to, provided with, or provided on" another component, it should be understood that the component may be directly coupled to or provided on the other component, but there may be other components in between.

[0015] As shown in FIGS. 2 and 3, the composite polishing pad for CMP of the present invention has the following features: a polymer substrate layer (10) having a number of protrusions molded on its upper surface; and The carbon nanotube layer (20) includes carbon nanotubes (22) embedded and fixed on the upper surface of the substrate layer.

[0016] The composite polishing pad of the present invention has the above-described structure, which is characterized by significantly improving the polishing efficiency and lifespan.

[0017] In other words, when abrasive particles are pressed into the carbon nanotube layer, the high hardness of the carbon nanotubes on the surface and the polyurethane in which the carbon nanotubes are embedded exerts a high force on the abrasive particles, improving the polishing efficiency. Furthermore, the increased mechanical strength provided by the carbon nanotube surface layer also improves the life of the polishing pad.

[0018] In one embodiment of the present invention, the carbon nanotubes of the carbon nanotube layer (20) may be embedded in an irregular net form on the surface of the polymer substrate layer (10), as shown in Figures 2 and 3.

[0019] The irregular net-form structure may be a structure formed by scattering carbon nanotubes so that some of the carbon nanotubes overlap. The term "scattered" here means that the carbon nanotubes are dispersed and arranged, and the term "overlapped" means that some of the carbon nanotubes overlap, strengthening the three-dimensional structure.

[0020] In one embodiment of the present invention, the polymer substrate layer (10) may have a Shore hardness of 20D to 70D, preferably 30D to 45D. When the hardness of the polymer substrate layer satisfies the above range, it is possible to appropriately form the contact area between the protrusions and the object to be polished, and it is also preferable because it is possible to improve the life and efficiency of the polishing pad.

[0021] In one embodiment of the present invention, the polymer material having a Shore hardness of 20D to 70D that forms the polymer substrate layer (10) may be one or more selected from the group consisting of polyurethane resin, UV-curable resin, silicone resin, etc., but is not limited thereto, and any material known in this field may be used without limitation as long as it does not adversely affect the present invention.

[0022] In one embodiment of the present invention, the thickness of the polymer substrate layer (10) excluding the height of the protrusions may be 2 mm to 50 mm, more preferably 3 mm to 30 mm.

[0023] The polymer substrate layer (10) may be formed of, for example, two or more layers. That is, a soft polymer layer having a Shore hardness of 20D to 45D may be disposed inside the polishing surface, and a hard polymer layer having a Shore hardness of 45D to 70D may be laminated on the outer surface of the soft polymer layer. In this case, the carbon nanotube layer may be provided on the surface of the hard polymer layer.

[0024] As described above, when the polymer substrate layer 10 is formed as a laminate of a soft polymer layer and a hard polymer layer, the soft polymer layer can ensure a wide contact area, and the hard polymer layer on the surface can press the abrasive particles deeply into the substrate. Furthermore, the functions of these layers can improve the polishing efficiency and lifespan of the polishing pad.

[0025] The above effect can be expressed as an image in Figure 4. Figure 4 shows the contact state between the micro-protrusions, abrasive particles, and the object to be polished (e.g., wafer) that changes depending on the difference in mechanical properties of the micro-protrusions provided on the polishing pad.

[0026] As shown in Figure 4(a), fine protrusions with mechanically soft properties are easily deformed and have a large contact area, but they do not apply a sufficient load to the abrasive particles, making it impossible to press them into the surface of the object to be polished and polish it. Furthermore, they are prone to wear, making continuous use as a polishing pad impossible.

[0027] On the other hand, in the case of micro-protrusions with strong mechanical properties (for example, micro-protrusions made of highly wear-resistant materials), as shown in Figure 4(b), there is an advantage in that a load can be applied to the abrasive particles and they can be pressed deep into the surface of the object to be polished, but there is a disadvantage in that a large contact area with the object to be polished cannot be formed.

[0028] On the other hand, as shown in Figure 4(c), when a coating layer is formed on the surface of a fine protrusion having mechanically soft properties using a material having mechanically strong properties (e.g., a material with high abrasion resistance), the above-mentioned effect can be obtained.

[0029] When the polymer substrate layer (10) is formed as a laminate of a soft polymer layer and a hard polymer layer, the thickness of the soft polymer layer, excluding the height of the protrusions, may be 1 mm to 20 mm, more preferably 2 mm to 10 mm. The thickness of the hard polymer layer, excluding the height of the protrusions, may be 5 μm to 90 μm, more preferably 10 μm to 40 μm. If the coating layer is thinner than the above thickness, the polishing pad is prone to wear. If the coating layer is too thick, the gripping force of the carbon nanotubes on the abrasive particles is reduced, and the polishing contact area is also reduced, which is undesirable. However, the above range can be appropriately adjusted by adjusting the density and length of the carbon nanotubes.

[0030] In one embodiment of the present invention, the protrusions may have a maximum width of 10 μm to 500 μm and a height of 3 μm to 150 μm, but the ranges are not limited to these and can be appropriately adjusted depending on the object to be polished and the polishing conditions.

[0031] In one embodiment of the present invention, the carbon nanotubes may have a diameter of 1 nm to 50 nm and a length of 1 μm to 30 μm, but the diameter and length are not limited to these ranges and can be appropriately adjusted depending on the object to be polished and the polishing conditions.

[0032] In one embodiment of the present invention, the protrusions may have a shape similar to a hemisphere, for example, but are not particularly limited to this shape. As shown in Figures 2 and 3, the protrusions include a polymer substrate layer (10) and a carbon nanotube layer (20) and protrude upward from the composite polishing pad.

[0033] In one embodiment of the present invention, the composite polishing pad may have a structure in which no pores exist between the polymer substrate layer 10 and the carbon nanotubes embedded and fixed in the substrate layer 10. When no pores exist, the polymer substrate layer 10 and the carbon nanotubes embedded and fixed in the substrate layer 10 can be more firmly bonded to each other, which is preferable.

[0034] The pore-free structure can be formed by forming the bond between the layers in a vacuum, as described below. The term "pore-free" can also mean that there are substantially no pores.

[0035] The present invention also provides a method for manufacturing a composite polishing pad for CMP, which, as shown in FIG. 5, can include the following steps (a) to (c): (a) scattering carbon nanotubes onto a mold having a large number of protrusions engraved thereon so that the carbon nanotubes overlap each other; (b) coating a polymer on top of the carbon nanotubes to form a polymer substrate layer having a flat top surface; and (c) demolding the mold

[0036] The method of scattering the carbon nanotubes in step (a) so that they overlap each other can be performed by a method known in the art. For example, as shown in Figure 5, the carbon nanotubes can be sprayed into a mold through a nozzle. In this case, the carbon nanotubes can be sprayed in a form dispersed in a solvent. Examples of the solvent include, but are not limited to, water, ethanol, and isopropyl alcohol.

[0037] The coating in step (b) may be performed by a method known in the art, such as spin coating, spray coating, or other methods known in the art.

[0038] In one embodiment of the present invention, step (b) may be performed in a vacuum. When the coating is performed in a vacuum, it is possible to prevent pores from being formed between the carbon nanotubes and the polymer substrate layer, which is preferable because the carbon nanotubes can be more firmly embedded and fixed.

[0039] The present invention also provides a method for manufacturing another composite polishing pad for CMP, the method comprising the following steps (a) to (d): (a) scattering carbon nanotubes on a substrate so that they overlap each other; (b) coating a polymer on top of the carbon nanotubes to form a polymer substrate layer having a flat top surface; (c) separating and removing the substrate from the carbon nanotubes; and (d) embossing the surface from which the substrate has been removed to form a plurality of protrusions including a polymer substrate layer and a carbon nanotube layer arranged in a network pattern.

[0040] The coating in step (b) may be performed by a method known in the art, such as spin coating, spray coating, or other methods known in the art.

[0041] The substrate separation in the step (c) may be performed by, for example, mechanical silicon separation (demolding), silicon etching, or the like.

[0042] The embossing process in step (d) may be performed by applying pressure to the upper surface of the carbon nanotube substrate from which the substrate has been removed using a mold having a number of protrusions engraved thereon under heating conditions. The temperature of the mold may be, but is not limited to, 200 to 250°C. The mold may be made of a metal material such as nickel or copper, and the micropattern may be fabricated using a Micro Electro-Mechanical System (MEMS) process.

[0043] In one embodiment of the present invention, step (b) may be performed in a vacuum. When the coating is performed in a vacuum, it is possible to prevent pores from being formed between the carbon nanotubes and the polymer substrate layer, which is preferable because the carbon nanotubes can be more firmly embedded and fixed.

[0044] Hereinafter, the present invention will be described in detail with reference to examples. However, the examples according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the examples detailed below. The examples of the present invention are provided to more completely explain the present invention to those skilled in the art. [Example]

[0045] Example 1: Preparation of a composite polishing pad Carbon nanotubes were dispersed in isopropyl alcohol to prepare a carbon nanotube dispersion. The dispersion was then applied to a mold engraved with numerous hemispherical protrusions each 50 μm in radius using a pneumatic nozzle. A polyurethane resin (50 μm) with a Shore hardness of 30D was applied to the mold coated with the carbon nanotubes under vacuum to form a polymer substrate layer 5 mm thick, measured from the top of the carbon nanotubes. After the polymer substrate layer was cured, the mold was separated and removed to produce the composite polishing pad of the present invention.

[0046] Example 2: Preparation of a Composite Polishing Pad Carbon nanotubes were dispersed in isopropyl alcohol to prepare a carbon nanotube dispersion. Next, the dispersion was applied to a polypropylene substrate placed on a hot plate heated to 60°C using a pneumatic nozzle. A polyurethane resin (trade name: Smooth-Cast) with a Shore hardness of 30D was applied to the mold to which the carbon nanotubes had been applied. TM 30D, manufactured by Smooth-On) was applied under a vacuum atmosphere to form a polymer substrate layer having a thickness of 5 mm based on the top end of the carbon nanotube.

[0047] After the polymer substrate layer was cured, the substrate was separated and removed, and the carbon nanotube surface from which the substrate had been removed was embossed by pressing at 200°C using a mold engraved with numerous hemispherical protrusions each having a radius of 50 μm, to produce a composite polishing pad of the present invention.

[0048] Example 3: Preparation of a Composite Polishing Pad Carbon nanotubes were dispersed in isopropyl alcohol to prepare a carbon nanotube dispersion. Next, the dispersion was applied to a polypropylene substrate placed on a hot plate heated to 60°C using a pneumatic nozzle. A polyurethane resin (trade name: Smooth-Cast) with a Shore hardness of 45D was applied to the mold to which the carbon nanotubes had been applied. TM 45D, manufactured by Smooth-On) was applied under vacuum atmosphere and spin-coated to form a hard polymer layer having a thickness of 5 mm based on the top end of the carbon nanotube.

[0049] After the hard polymer layer was cured, the silicon substrate was mechanically separated to transfer the carbon nanotubes to the polyurethane.

[0050] A polyurethane resin (trade name: Smooth-Cast) having a Shore hardness of 30D was applied to the hard polymer layer on the opposite side of the separated carbon nanotubes. TM 30D, manufactured by Smooth-On) was applied under a vacuum atmosphere to form a soft polymer layer having a thickness of 5 mm.

[0051] After hardening the soft polymer layer, the carbon nanotubes were pressed from above using a mold engraved with numerous hemispherical protrusions with a radius of 50 μm at 200°C to perform an embossing process, thereby producing the composite polishing pad of the present invention.

[0052] Comparative Example 1: Preparation of a Composite Polishing Pad Polyurethane resin with a Shore hardness of 30D (product name: Smooth-Cast TM30D, manufactured by Smooth-On) was applied to form a polymer substrate layer having a thickness of 5 mm.

[0053] After curing the polymer substrate layer, a composite polishing pad was manufactured by embossing the layer at 200° C. using a mold engraved with a number of hemispherical protrusions each having a radius of 50 μm. [Explanation of symbols]

[0054] 1: Rotating table 2: Wafer 3: Carrier (rotating head) 4: Conditioner 5: Nozzle 10: Polymer substrate layer 20: Carbon nanotube layer 22: Carbon nanotubes 30: Hard polymer coating layer 100: Composite polishing pad

Claims

1. a polymeric substrate layer including a plurality of protrusions molded onto an upper surface thereof; and a carbon nanotube layer comprising carbon nanotubes embedded and fixed to the top surface of the polymer substrate layer; the polymer substrate layer includes a soft polymer layer having a number of protrusions formed on an upper surface thereof, and a hard polymer layer laminated on the upper surface of the soft polymer layer; the carbon nanotube layer is provided on a surface of the hard polymer layer; The carbon nanotubes are embedded in an irregular net-like structure on the upper surface of the hard polymer layer.

2. 2. The composite polishing pad for CMP according to claim 1, wherein the irregular net-form structure is formed by scattering the carbon nanotubes so that some of the carbon nanotubes overlap each other.

3. 2. The composite polishing pad for CMP according to claim 1, wherein the soft polymer layer has a Shore hardness of 20D to 45D.

4. 2. The composite polishing pad for CMP according to claim 1, wherein the hard polymer layer has a Shore hardness of 45D to 70D.

5. 2. The composite polishing pad for CMP according to claim 1, wherein the protrusions have a maximum width of 10 μm to 500 μm and a height of 3 μm to 150 μm.

6. 2. The composite polishing pad for CMP according to claim 1, wherein the carbon nanotubes have a diameter of 1 nm to 50 nm and a length of 1 μm to 30 μm.

7. 2. The composite polishing pad for CMP according to claim 1, wherein the protrusions are hemispherical in shape.

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