CHEMICAL-MECHANICAL POLISHING PAD WITH PROTRUDED STRUCTURES

Info

Publication number: 20210323114
Type: Application
Filed: Oct 14, 2020
Publication Date: Oct 21, 2021
Inventor: Goo Youn KIM (Newark, DE)
Application Number: 17/070,454

Abstract

A polishing pad includes a supporting layer and a protruded pattern disposed on the supporting layer. The protruded pattern includes a horizontal extended surface and a vertical side surface. Further, the supporting layer includes a first supporting layer and a second supporting layer, and the first supporting layer is disposed on the second supporting layer. In particular, a variation of a horizontal cross-sectional area of the protruded pattern is equal to or less than 50% along a protrusion direction.

Description

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional Application No. 63/013,064 filed on Apr. 21, 2020, which application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to chemical-mechanical polishing, and more particularly, to chemical-mechanical polishing pads with protruded structures for improved thermal stability and improved consistency of polishing surface roughness.

RELATED ART

Chemical-mechanical polishing (CMP) is used in semiconductor fabrication processes for smoothing uneven or undulated patterns on the wafer surface. The CMP process flattens the surface of a wafer or a manufacturing article on the atomic level, while minimizing surface defects, using interactions of frictional and chemical energies. Polishing is achieved by generating a relative motion between a manufacturing article and a polishing pad while pressing down the manufacturing article on the polishing pad and supplying polishing slurry. The CMP process is used in the ultra large scale integration (ULSI) manufacturing and considered an essential technology for smoothing transistor elements or interlayer insulations of multi-layer interconnects, fabricating tungsten or copper interconnects, and the like.

As shown in FIG. 1, a typical CMP process includes attaching a polishing pad 1 on a platen 2, supplying a polishing slurry 3 on the polishing pad 1, pressing a manufacturing article 4 such as a wafer against the polishing pad 1, and generating a relative motion between the polishing pad 1 and the manufacturing article 4. The polishing pad is a polishing tool formed in a thin planar shape and mainly made of a polymer material. To control the polishing rate uniformly across the wafer, both the polishing pad and the wafer are rotated as shown in FIG. 1 in a state where the polishing pad and the wafer are pressed against each other. In particular, the polishing rate may be determined by a product of polishing pressure and a relative velocity between the polishing pad and the wafer (i.e., polishing pressure x relative velocity). In other words, once the polishing tool and the manufacturing article are given, the polishing rate is determined by the pressure and the relative velocity. One of the requirements for the CMP process is a polishing stability, or an ability to maintain repeatability. Factors that impact the polishing stability include variations of frictional heat and surface condition.

The frictional heat generated from the frictional abrasion has a significant impact on the polishing. For example, even when the polishing pressure and the relative velocity are constant, the amount of frictional heating can vary depending on the chemical, mechanical, and/or thermal properties of the polishing slurry and the pad. Accordingly, the frictional heat impacts the polishing rate. Therefore, although an ability to tightly control the pressure and the relative velocity generally improves the polishing stability or repeatability, a complex matrix of variations in consumable parts and polishing conditions even during the process significantly impacts the polishing stability. Therefore, controlling the complex factors in the CMP process with a tight precision is critical for a stable and repeatable polishing process.

However, as the polishing process proceeds, the frictional heat from the polishing process accumulates in the equipment, and the process temperature deviates, causing degradation of the polishing stability and repeatability. As such, control of the frictional heat is required to maintain the polishing stability. Since conventional polishing pads in the related art are made of polymer layers with poor heat transfer characteristics, improvement is required.

In addition, another factor that degrades the polishing stability is the consistency of the pad surface. More specifically, the polishing rates are proportional to the surface roughness of the pad. However, the roughness of the polishing surface varies over time. To overcome this problem and to restore the surface roughness, the polishing pads are typically scrubbed with a roughening tool such as a conditioning disc 5 (FIG. 1) that includes diamond particles coated thereon. Since numerous factors such as the size and distribution of the diamond particles, pressure, conditioning method, and the stability of the conditioning tool govern the conditioning results, it is difficult to consistently maintain the surface condition of the polishing pad. As a result, the surface roughness of the conventional polishing pads in the related art is unstable.

SUMMARY

The present disclosure provides design and manufacturing of polishing pads, which are used as a polishing tool in the semiconductor or optical components manufacturing during, for example, chemical-mechanical polishing, mechano-chemical polishing, and tribochemical polishing processes. The polishing pads according to the present disclosure may provide improved thermal stability and may maintain more consistent surface roughness of the polishing surface.

An aspect of the present disclosure may provide a polishing pad that includes a supporting layer and a protruded pattern disposed on the supporting layer. The protruded pattern may include a horizontal extended surface and a vertical side surface. The supporting layer may include a first supporting layer and a second supporting layer, and the first supporting layer may be disposed on the second supporting layer.

In some embodiments, one or more of the following aspects may be included individually or in any combination. A variation of a horizontal cross-sectional area of the protruded pattern may be equal to or less than 50% along a protrusion direction. An area ratio of the extended surface to the polishing pad may be equal to or greater than 1% and equal to or less than 80%. The protruded pattern may include a plurality of unit patterns separately disposed from each other, and/or the protruded pattern may include a plurality of unit patterns laterally connected with each other. A total peripheral length of the extended surface within a 1 cm²unit area of the polishing pad may be equal to or greater than 24 cm and equal to or less than 2400 cm. A height of the protruded pattern may be equal to or greater than 10 μm and equal to or less than 1000 μm.

The supporting layer may include a groove dividing the supporting layer into a plurality of sections. In some implementations, the supporting layer may include a first groove formed in the first supporting layer, the first groove dividing the supporting layer into a plurality of sections. A remaining thickness of the first supporting layer under the first groove may be equal to or less than 500 μm. The supporting layer may include a second groove formed within the first groove, and a width of the second groove may be narrower than a width of the first groove.

A thickness of the first supporting layer may be equal to or less than 1500 μm, and a thickness of the second supporting layer may be equal to or greater than 100 μm and equal to or less than 3000 μm. The first supporting layer may include a first material, and the second supporting layer may include a second material. The first material and the second material may be same or different. A first hardness of the first material may be equal to or greater than a second hardness of the second material. In some implementations, the protruded pattern may include a first material, and the supporting layer may include a second material. A first hardness of the first material may be equal to or greater than a second hardness of the second material. In some implementations, the second supporting layer may include a foam material having a porosity. The porosity of the foam material may be between 1% and 70%.

The first hardness may be equal to or greater than Shore 30D and equal to or less than Shore 80D, and the second hardness may be equal to or greater than Shore 20A and equal to or less than Shore 80A. For example, the first material may be selected from the group consisting of polyurethane, polybutadiene, polycarbonate, polyoxymethylene, polyamide, epoxy, acrylonitrile butadiene styrene copolymer, polyacrylate, polyetherimide, acrylate, polyalkylene, polyethylene, polyester, natural rubber, polypropylene, polyisoprene, polyalkylene oxide, polyethylene oxide, polystyrene, phenolic resin, amine, urethane, silicone, acrylate, fluorene, phenylene, pyrene, azulene, naphthalene, acetylene, p-phenylene vinylene, pyrrole, carbazole, indole, azepine, aniline, thiophene, 3,4-ethylenedioxysiphen, and p-phenylene sulfide. The second material may be selected from the group consisting of polyurethane, polybutadiene, polycarbonate, polyoxymethylene, polyamide, epoxy, acrylonitrile butadiene styrene copolymer, polyacrylate, polyetherimide, acrylate, polyalkylene, polyethylene, polyester, natural rubber, polypropylene, polyisoprene, polyalkylene oxide, polyethylene oxide, polystyrene, phenolic resin, amine, urethane, silicone, acrylate, fluorene, phenylene, pyrene, azulene, naphthalene, acetylene, p-phenylene vinylene, pyrrole, carbazole, indole, azepine, aniline, thiophene, 3,4-ethylenedioxysiphen, and p-phenylene sulfide.

Notably, the present disclosure is not limited to the combination of the elements as listed above and may be assembled in any combination of the elements as described herein. Other aspects of the disclosure are disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A brief description of each drawing is provided to more sufficiently understand drawings used in the detailed description of the present disclosure.

FIG. 1 shows a general setup of chemical-mechanical polishing process;

FIG. 2 shows a polishing pad according to an exemplary embodiment of the present disclosure;

FIG. 3 depicts a protruded pattern of a polishing pad according to exemplary embodiments of the present disclosure;

FIG. 4 illustrates parameters for a convective heat transfer model;

FIG. 5 shows representative modeling results of heat transfer amounts for various geometries of a protruded pattern of a polishing pad according to exemplary embodiments of the present disclosure;

FIGS. 6A, 6B, 7A, and 7B show various geometries of the protruded patterns according to exemplary embodiments of the present disclosure;

FIG. 8 shows representative experimental results of removal rates for various designs of a polishing pad according to exemplary embodiments of the present disclosure;

FIG. 9 compares temperature increase during the polishing process using a conventional polishing pad in the related art and a polishing pad according to an exemplary embodiment of the present disclosure; and

FIG. 10 compares the polishing efficiencies between polishing pads according to exemplary embodiments of the present disclosure and a conventional polishing pad in the related art.

It should be understood that the above-referenced drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the disclosure. The specific design features of the present disclosure, including, for example, specific dimensions, orientations, locations, and shapes, will be determined in part by the particular intended application and use environment.

DETAILED DESCRIPTION

Advantages and features of the present disclosure and a method of achieving the same will become apparent with reference to the accompanying drawings and exemplary embodiments described below in detail. However, the present disclosure is not limited to the exemplary embodiments described herein and may be embodied in variations and modifications. The exemplary embodiments are provided merely to allow one of ordinary skill in the art to understand the scope of the present disclosure, which will be defined by the scope of the claims. Accordingly, in some embodiments, well-known operations of a process, well-known structures, and well-known technologies will not be described in detail to avoid obscure understanding of the present disclosure. Throughout the specification, same reference numerals refer to same elements.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about.” The terms “first,” “second,” or the like are herein used to distinguishably refer to same or similar elements, and they may not infer an order or a plurality.

Aspects of the present disclosure provide design and manufacturing of polishing pads for chemical-mechanical polishing (CMP) processes. In particular, the polishing pads according to the present disclosure may exhibit improved thermal characteristics and maintain thermal stability during the CMP process. In addition, the polishing pads according to the present disclosure may minimize a variation of the surface roughness in the polishing pad with respect to polishing time, and thus, may provide technical advantages such as increased reliability and repeatability for the polishing process. Consequently, wafer planarization may be more reliably obtained. Moreover, due to the lower operating temperature, the polishing pads according to the present disclosure may last longer and require less frequent replacement, providing economic advantages. Defects of the polishing pad may be minimized as well. A conditioning tool such as the conditional disc 5 in FIG. 1 may be eliminated from the CMP setup, which may simplify the process and the CMP equipment configuration. In addition, since the polishing pads according to the present disclosure may maintain a more stable polishing temperature, the temperature of polishing slurry may be prevented from varying. Less temperature variation of the polishing slurry is advantageous because the temperature variation of the polishing slurry may vary the pH of the polishing slurry, and the pH of the polishing slurry may affect agglomeration of abrasive particles within the polishing slurry.

In order to maintain a constant surface temperature of a polishing pad, frictional heat generated at the pad may be transferred to polishing slurry at an increased rate. In turn, in order to more rapidly transfer the frictional heat to the slurry that is supplied onto the pad, the surface geometry of the polishing pad may be designed to allow the convective heat transfer to be increased. Conventional polishing pads in the related art have polishing studs formed in a conical shape due to the conditioning. Accordingly, a space for the slurry to flow through is more limited, and a distance between where the frictional heat is generated in the pad and where the pad contacts the slurry is greater. Therefore, heat transfer efficiencies are compromised.

Newton's law of cooling is shown in Equation 1 as below:

Q=hAΔT=hA(T−T_∞) [Equation 1]

where Q is the heat transfer amount; h the convective heat transfer coefficient; A the area of heat transfer; and ΔT the temperature difference, namely a difference between the polishing temperature (T) during the process and the background temperature (T_∞). The background temperature (T_∞) may refer to the temperature of the polishing slurry. Since the temperature difference (ΔT) between the operating temperature and the slurry temperature is typically 10 to 50 Kelvin (K), the design object for the polishing pad may become maximizing the heat transfer amount (Q) for the given temperature difference (ΔT). For example, the convective heat transfer coefficient (h) may be increased, or the area of contact (A) between the pad surface and the slurry may be increased.

Herein, the polishing slurry or the slurry may refer to a colloid in which abrasive particles and/or corrosive chemicals are suspended in a liquid (e.g., water). For the abrasive particles, cerium oxide powder may be used. Nominal particle size of the abrasive particles may be about 1 nm to about 500 nm. However, the present disclosure does not limit the type or characteristics of slurries to be used in the CMP process, and any slurries used in the field may be used in conjunction with the polishing pads according to the present disclosure.

Hereinbelow, polishing pads according to exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.

FIG. 2 shows a polishing pad according to an exemplary embodiment of the present disclosure, and FIG. 3 depicts a protruded pattern of the polishing pad according to exemplary embodiments of the present disclosure. Referring to FIGS. 2 and 3, the polishing pad 10 may include a plurality of protruded patterns 100 and a supporting layer 200. Each of the plurality of protruded patterns 100 may include an extended surface 120 formed as a horizontal plane and a vertical side surface 180 substantially perpendicular to the extended surface 120. In order to increase the convective heat transfer, the area of contact (A in Equation 1) may be increased, for example, by increasing a surface area of the side surface 180.

For each protruded pattern 100, the convective heat transfer may be calculated based on Equation 2 as below:

Q=√{square root over (hPkA_c)}(T_b−T_∞)tan h(mL) [Equation 2]

where m is the fin parameter defined as

$\sqrt{\frac{h P}{k A_{c}}};$

h the convective heat transfer coefficient; P the peripheral length of the extended surface 120; A_cthe area of the extended surface 120; k the conductive heat transfer coefficient of the protruded pattern material; T_bthe temperature of the extended surface 120; and T_∞ the temperature of the slurry. The parameters for the convective heat transfer model are shown in FIG. 4.

According to exemplary embodiments of the present disclosure, since the protruded pattern 100 includes an extended surface 120 that is protruded from the supporting layer 200, the frictional heat generated at the extended surface 120 during the polishing process may be more readily transferred away from the protruded pattern 100 to the slurry via the side surface 180 of the protruded pattern 100. Therefore, the heat transfer efficiency may be increased.

FIG. 5 shows representative modeling results of the heat transfer amount for various geometries of the protruded pattern of the polishing pad according to exemplary embodiments of the present disclosure. More specifically, FIG. 5 shows the modeling results for the heat transfer amounts (Q) by varying a peripheral length (P) and a height (L) of the extended surface 120 while using the convective heat transfer coefficient (h) of the slurry of 0.8 W/m²K, the conductive heat transfer coefficient (k) of the protruded pattern 100 of 0.5 W/mK, and ΔT of 50 K. Referring to FIG. 5, the amount of heat transfer (Q) increases as the peripheral length (P) of the protruded pattern 100 increases and as the height (L) of the protruded pattern 100 increases. Therefore, in order to increase the amount of heat transfer for a given polishing pad area, the peripheral length (P) and the protruding height (L) of the protruded pattern 100 may be increased. Since the effect is less pronounced when the height (L) is greater than about 1000 μm as shown in FIG. 5, the height (L) of the protruded pattern 100 may be equal to or less than about 1000 μm and equal to or greater than about 10 μm.

As described above, the amount of heat transfer (Q) may be enhanced by increasing the surface area through which the convective heat transfer occurs since an overall thermal resistance is predominated by a convective thermal resistance, and the convective thermal resistance is decreased as the surface area in contact with the slurry is increased. Accordingly, the peripheral length (P) may be increased for a given area (A_c) of extended surface 120. For example, a total peripheral length of the extended surface 120 within a 1 cm²unit area of the polishing pad 10 may be equal to or greater than about 24 cm and equal to or less than about 2400 cm.

To increase the peripheral length of the extended surface 120 per unit area of the polishing pad 10, the overall dimension of the protruded pattern 100 may be decreased, and/or the protruded pattern 100 may be formed in particular geometries. For example, the protruded pattern 100 may include a polygon such as a triangle, a quadrangle, a pentagon, a hexagon, and the like. The protruded pattern 100 may also include a circle, an ellipse, or any free-curved shapes. Further, the protruded pattern 100 may include a geometry which is a combination of two or more shapes. In some embodiments, the protruded pattern 100 may include a plurality of unit patterns separately disposed from each other. Additionally or alternatively, the protruded pattern 100 may include a plurality of unit patterns that are laterally connected with each other to form a network of unit patterns.

FIGS. 2, 6A, 6B, 7A, and 7B show the protruded pattern 100 formed in various geometries. FIG. 2 shows the protruded pattern 100 formed in a square shape, and FIG. 6A shows a cross pattern. Furthermore, FIG. 6B shows a combined pattern of a cross and squares. As shown in FIG. 6B, the protruded pattern 100 may have non-uniform heights varying locally within a unit pattern. In some embodiments, as shown in FIGS. 7A and 7B, the peripheral length (P) may be adjusted by increasing or decreasing the overall size of the same geometry. The geometry of the protruded pattern 100 according to the present disclosure is not limited to the above examples, and it may be variably determined to increase or decrease the peripheral length (P) of the protruded pattern 100. An area ratio of the extended surface 120 with respect to the polishing pad 10 may be equal to or greater than about 1% and equal to or less than about 80%. For example, the area ratio of the extended surface 120 with respect to the polishing pad 10 may be about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%. Herein, the area ratio of the extended surface 120 with respect to the polishing pad 10 may refer to a ratio of the total area of the extended surface 120 within the polishing pad 10 with respect to a planform area of the polishing pad 10. Similarly, the area ratio may be calculated as a sum of the area of the extended surface 120 within a unit area of the polishing pad 10.

According to an exemplary embodiment of the present disclosure, as shown in FIG. 2, the supporting layer 200 may include a first supporting layer 210 and a second supporting layer 220. When the polishing pad 10 is uneven and the supporting layer 200 is rigid, the polishing pad 10 may exert uneven polishing pressures to the manufacturing article such as a wafer. To prevent the polishing pad 10 from exerting uneven polishing pressures on the manufacturing article, the second supporting layer 220 may be formed with a material more flexible or pliable than the first supporting layer 210. In other words, the first supporting layer 210 may include a first material, and the second supporting layer 220 may include a second material. The first material and the second material may be same or different from each other, and a first hardness of the first material may be greater than a second hardness of the second material. For example, the second supporting layer 220 may include a foam material having a porosity to provide a hardness in the required range. The porosity of the foam material may be between about 1% and about 80%. Alternatively, the porosity of the foam material may be between about 1% and about 70%. By forming the second supporting layer 220 with a less rigid material, discrepancies of the polishing pressures across the polishing pad 10 may be alleviated, and the uniformity of the polishing process may be improved.

Alternatively, the first supporting layer 210 and the second supporting layer 220 may be formed with a same material, and configured to have different hardness. For example, the first supporting layer 210 and the second supporting layer 220 formed with the same material may include a foam material having different porosities. Alternatively or additionally, the first supporting layer 210 and the second supporting layer 220 may include different additives to vary the hardness of the material. A thickness of the first supporting layer 210 may be equal to or less than about 1500 μm. A thickness of the second supporting layer 220 may be equal to or greater than about 100 μm and equal to or less than about 3000 μm.

In some embodiments, the supporting layer 200 may be formed as a single layer. In such embodiments, the protruded pattern 100 may include a first material, and the supporting layer 200 may include a second material. The first material and the second material may be same or different. In particular, a first hardness of the first material may be greater than a second hardness of the second material. In other words, the second hardness of the second material may be less than the first hardness of the first material to allow the polishing pad 10 to exert more uniform pressure to the manufacturing article. The first material of the protruded pattern 100 and the second material of the supporting layer 200 may be same while the supporting layer 200 may have less hardness due to different additives and/or structures.

Since the slurry includes about 90 to 99% water, the thermal characteristics of the slurry may be considered similar to the thermal characteristics of water, a thermal conductivity of which is about 0.6 W/mK. As such, the thermal conductivity of the slurry may be relatively low, and accordingly, the convective heat transfer mode may dominate over the conductive heat transfer mode. The convective heat transfer may be affected by the type of flow (e.g., a laminar flow regime or a turbulent flow regime), and a forced convection may enhance the convective heat transfer more efficiently than a natural convection. Since the CMP process involves a relative motion between a rotating polishing pad and a wafer while being maintained in a pressed state, the slurry may be forcedly supplied, discharged, mixed, and agitated. Such movements of the slurry may affect the convective heat transfer.

Aspects of the present disclosure provide structures of the polishing pad in which the slurry may move in turbulent flows due to the micro structures of the polishing surface. For example, the polishing pad 10 may include structures through which the slurry may move around rapidly, thereby allowing the slurry to contact more micro patterns and transfer the heat more efficiently. Accordingly, at least one groove may be formed on the polishing pad surface to more effectively control the slurry flows.

Referring to FIG. 2 again, the polishing pad 10 according to an exemplary embodiment of the present disclosure may include a groove in the supporting layer 200 for enhancing the flows of the slurry. For example, the supporting layer 200 may include a first groove 230 and a second groove 240. The first groove 230 may be formed in the first supporting layer 210 to divide the supporting layer 200 into a plurality of sections. The second groove 240 may be formed within the first groove to enhance the supply and discharge of the slurry. A width of the second groove 240 may be narrower than a width of the first groove 230. For example, the width of the second groove 240 may be between about 0.1 mm to about 0.5 mm (inclusive) or about 2 mm to about 5 mm (inclusive). A depth of the second groove 240 may be about 1% to about 99% of a thickness of the second supporting layer 220. Alternatively, when the supporting layer 200 is formed as a single layer, a groove may included in the single layer of the supporting layer 200.

As described above, the first supporting layer 210 may include a first material, and the second supporting layer 220 may include a second material. The first material and the second material may be same or different. In particular, a first hardness of the first material may be equal to or greater than a second hardness of the second material. Due to the less rigid or more pliable second material of the second supporting layer 220, the pressing force may be more evenly distributed across the polishing pad surface even with a presence of unevenness and/or thickness variations in the polishing pad, and thereby the manufacturing article such as a wafer may be polished more smoothly (e.g., with a higher flatness or a higher evenness). In other words, the softer second supporting layer 220 may allow the first supporting layer 210 and/or the protruded pattern 100 to more compliantly follow the surface topology or geometry of the surface of the manufacturing article when the polishing pad 10 and the manufacturing article are pressed.

In some embodiments, the first supporting layer 210 may be divided into a plurality of independent sections by the first groove 230. The first groove 230 may allow the first supporting layer 210 to move in a more flexible manner by providing smaller and divided sections. A depth of the first groove 230 may be determined to allow a remaining thickness of the first supporting layer 210 under the first groove 230 to be equal to or less than about 500 μm. The remaining thickness of the first supporting layer 210 may be defined as a distance between a top of the second supporting layer 220 and a bottom of the first groove 230. In some embodiments, the remaining thickness of the first supporting layer 210 under the first groove 230 may be zero, which indicates that the first groove 230 is formed through the entire thickness of the first supporting layer 210. In such case, the first supporting layer 210 may be divided into completely independent sections.

In some embodiments, the thickness of the first supporting layer 210 may be zero or close to zero. In this instance, the protruded patterns 100 may be essentially disposed on the second supporting layer 220. Since the second supporting layer 220 (or a single-layered supporting layer 200) may be formed of a material with a less hardness than the protruded patterns 100, each of the protruded patterns 100 may individually follow the surface of the manufacturing article due to the more compliant nature of the second supporting layer 220.

For example, the materials for the first supporting layer 210 and/or the second supporting layer 220 may include polyurethane, polybutadiene, polycarbonate, polyoxymethylene, polyamide, epoxy, acrylonitrile butadiene styrene copolymer, polyacrylate, polyetherimide, acrylate, polyalkylene, polyethylene, polyester, natural rubber, polypropylene, polyisoprene, polyalkylene oxide, polyethylene oxide, polystyrene, phenolic resin, amine, urethane, silicone, acrylate, fluorene, phenylene, pyrene, azulene, naphthalene, acetylene, p-phenylene vinylene, pyrrole, carbazole, indole, azepine, aniline, thiophene, 3,4-ethylenedioxysiphen, p-phenylene sulfide, or the like.

The first hardness of the first supporting layer 210 may be between about Shore 30D and about Shore 80D (inclusive) in terms of Shore Hardness scales. The second hardness of the second supporting layer 220 may be between about Shore 20A and about Shore 80A (inclusive) in terms of Shore Hardness scales. As described above, in some embodiments, the protruded pattern 100 may be formed of the same first material as the first supporting layer 210. In such case, the first material may be a composite material that includes additives to enhance abrasiveness and/or hardness. For example, Teflon, graphene, carbon nanoparticles, or the like may be included as the additives. In brief, the protruded pattern 100, the first supporting layer 210, and the second supporting layer 220 may be formed with materials different from each other, or two or more components may be formed with a same material.

In some embodiments, the protruded pattern 100 may include one or more additives to increase the hardness and/or wear resistance. Further, the protruded pattern 100 may be coated to increase the wear resistance. By way of example, one or more of Teflon, boron nitride, or carbon nanotube may be included as the additives and/or used as the coating material. By decreasing thermal conductivity, the Teflon coating may prevent or reduce the deformation of the protruded pattern 100 due to heat during the polishing. Boron nitride may increase mechanical strength.

The protruded pattern 100 may experience abrasion during the CMP process. The abrasion of the protruded pattern 100 may lead to altering the surface area of the protruded pattern 100 in contact with the manufacturing article. To minimize the variation of the contact area, the protruded pattern 100 may be designed to minimize a variation of a horizontal cross-sectional area. Herein, the horizontal cross-section of the protruded pattern 100 may be understood as a lateral cross-section that is perpendicular to a length direction or a protruding direction of the protruded pattern 100. The lengthwise variation of the horizontal cross-sectional area of the protruded pattern 100 may be equal to or less than about 50%. Further, the variation of the horizontal cross-sectional area of the protruded pattern 100 may be less than about 1%, 5%, 10%, or 20% along the protrusion direction. Due to the minimal variation in the horizontal cross-sectional area of the protruded pattern 100, the effective contact area between the polishing pad 10 and the manufacturing article may be maintained substantially constant even when the protruded pattern 100 wears out and the length (L) of the protruded pattern 100 gradually decreases.

FIG. 8 shows representative experimental results of removal rates for various designs of a polishing pad according to exemplary embodiments of the present disclosure. For these experiments, a cerium oxide slurry was used, and an oxide layer of a wafer was polished under various pressure and relative velocity (represented by a rotational speed) conditions. The horizontal axis of FIG. 8 shows the polishing rate represented by a product of pressure and rotational speed (revolutions per minute, RPM), and the vertical axis of FIG. 8 represents the removal rate. Referring to FIG. 8, the polishing pads according to the present disclosure may exhibit higher removal rates than the conventional polishing pad in the related art for nearly all conditions.

FIG. 9 compares the temperature increase during the polishing process using a conventional pad in the related art and a polishing pad according to an exemplary embodiment of the present disclosure. The horizontal axis of FIG. 9 represents the polishing time, and the vertical axis of FIG. 9 represents the temperature. The temperature data are shown in an arbitrary unit (AU) which corresponds to voltage measurements from the temperature sensor. The AU may be interpreted to be positively correlated with the temperature. Referring to FIG. 9, the polishing pad according to an exemplary embodiment of the present disclosure shows a smaller temperature increase than the conventional polishing pad in the related art for both silicon oxide polishing and silicon nitride (SiN) polishing. In particular, using the polishing pad according to an exemplary embodiment of the present disclosure, the temperature increase was limited to about 17 AU (after 212 seconds) while the temperature increased by about 23 AU (after 127 seconds) when using the conventional polishing pad in the related art. The experimental results indicate that the polishing pads according to the present disclosure may provide higher polishing rate (see FIG. 8) and also sustain lower temperatures for longer polishing times (see FIG. 9).

FIG. 10 compares the polishing efficiencies between polishing pads according to exemplary embodiments of the present disclosure and a conventional polishing pad in the related art. In FIG. 10, an STI wafer (HDP CVD oxide film) having a SKW3-2 pattern was used, and Dow® IC1010 was used as the conventional polishing pad in the related art. SP-20MD and SP-60MD represent polishing pads having protruded patterns according to exemplary embodiments of the present disclosure. FIG. 10 indicates that the SP-20MD and SP-60MD polishing pads according to exemplary embodiments of the present disclosure can demonstrate increased polishing efficiencies than the conventional IC1010 polishing pad. In other words, polishing rates of the top pattern are faster than polishing rates of the bottom trench.

As set forth herein, the subject matter of the present disclosure provides design and manufacturing of polishing pads with protruded patterns for the CMP process. The polishing pads according to the present disclosure may present improved thermal stability during the CMP process while providing higher polishing rates. In addition, the polishing pads according to the present disclosure may minimize a variation of surface roughness in the polishing pad over time. Therefore, the polishing pads according to the present disclosure may increase reliability and repeatability of the polishing process.

Hereinabove, although the present disclosure is described by specific matters such as concrete components, and the like, the exemplary embodiments and the drawings are provided merely for assisting in the entire understanding of the present disclosure. Therefore, the present disclosure is not limited to the exemplary embodiments described herein. Various modifications and changes can be made by a person of ordinary skill in the art to which the present disclosure pertains. The spirit of the present disclosure should not be limited to the above-described exemplary embodiments, and the following claims as well as all technical spirits modified equally or equivalently to the claims should be interpreted to fall within the scope and spirit of the disclosure.

Claims

1. A polishing pad comprising:

a supporting layer; and

a protruded pattern disposed on the supporting layer,

wherein the protruded pattern includes a horizontal extended surface and a vertical side surface.

2. The polishing pad of claim 1, wherein the supporting layer comprises:

a first supporting layer; and

a second supporting layer,

wherein the first supporting layer is disposed on the second supporting layer.

3. The polishing pad of claim 1, wherein a variation of a horizontal cross-sectional area of the protruded pattern is equal to or less than 50% along a protrusion direction.

4. The polishing pad of claim 1, wherein an area ratio of the extended surface to the polishing pad is equal to or greater than 1% and equal to or less than 80%.

5. The polishing pad of claim 1, wherein the protruded pattern includes a plurality of unit patterns separately disposed from each other.

6. The polishing pad of claim 1, wherein the protruded pattern includes a plurality of unit patterns laterally connected with each other.

7. The polishing pad of claim 1, wherein a total peripheral length of the extended surface within a 1 cm2 unit area of the polishing pad is equal to or greater than 24 cm and equal to or less than 2400 cm.

8. The polishing pad of claim 1, wherein a height of the protruded pattern is equal to or greater than 10 μm and equal to or less than 1000 μm.

9. The polishing pad of claim 2, wherein the supporting layer includes a first groove formed in the first supporting layer, the first groove dividing the supporting layer into a plurality of sections.

10. The polishing pad of claim 9, wherein a remaining thickness of the first supporting layer under the first groove is equal to or less than 500 μm.

11. The polishing pad of claim 2, wherein a thickness of the first supporting layer is equal to or less than 1500 μm, and

wherein a thickness of the second supporting layer is equal to or greater than 100 μm and equal to or less than 3000 μm.

12. The polishing pad of claim 9, wherein the supporting layer includes a second groove formed within the first groove, and

wherein a width of the second groove is narrower than a width of the first groove.

13. The polishing pad of claim 1, wherein the supporting layer includes a groove dividing the supporting layer into a plurality of sections.

14. The polishing pad of claim 2, wherein the first supporting layer includes a first material, and the second supporting layer includes a second material, and

wherein a hardness of the first material is equal to or greater than a hardness of the second material.

15. The polishing pad of claim 1, wherein the protruded pattern includes a first material, and the supporting layer includes a second material, and

wherein a hardness of the first material is equal to or greater than a hardness of the second material.

16. The polishing pad of claim 2, wherein the second supporting layer includes a foam material having a porosity.

17. The polishing pad of claim 14, wherein the first hardness is equal to or greater than Shore 30D and equal to or less than Shore 80D, and

wherein the second hardness is equal to or greater than Shore 20A and equal to or less than Shore 80A.

18. The polishing pad of claim 17, wherein at least one of the first material or the second material is selected from the group consisting of polyurethane, polybutadiene, polycarbonate, polyoxymethylene, polyamide, epoxy, acrylonitrile butadiene styrene copolymer, polyacrylate, polyetherimide, acrylate, polyalkylene, polyethylene, polyester, natural rubber, polypropylene, polyisoprene, polyalkylene oxide, polyethylene oxide, polystyrene, phenolic resin, amine, urethane, silicone, acrylate, fluorene, phenylene, pyrene, azulene, naphthalene, acetylene, p-phenylene vinylene, pyrrole, carbazole, indole, azepine, aniline, thiophene, 3,4-ethylenedioxysiphen, and p-phenylene sulfide.

19. The polishing pad of claim 15, wherein the first hardness is equal to or greater than Shore 30D and equal to or less than Shore 80D, and

wherein the second hardness is equal to or greater than Shore 20A and equal to or less than Shore 80A.

20. The polishing pad of claim 19, wherein at least one of the first material or the second material is selected from the group consisting of polyurethane, polybutadiene, polycarbonate, polyoxymethylene, polyamide, epoxy, acrylonitrile butadiene styrene copolymer, polyacrylate, polyetherimide, acrylate, polyalkylene, polyethylene, polyester, natural rubber, polypropylene, polyisoprene, polyalkylene oxide, polyethylene oxide, polystyrene, phenolic resin, amine, urethane, silicone, acrylate, fluorene, phenylene, pyrene, azulene, naphthalene, acetylene, p-phenylene vinylene, pyrrole, carbazole, indole, azepine, aniline, thiophene, 3,4-ethylenedioxysiphen, and p-phenylene sulfide.

21. The polishing pad of claim 15, wherein the first material includes an additive to enhance hardness and/or wear resistance.

22. The polishing pad of claim 21, wherein the additive includes Teflon, graphene, carbon nanoparticles, or any combination thereof.

23. The polishing pad of claim 15, wherein the first material includes a coating material to enhance wear resistance.

24. The polishing pad of claim 23, wherein the coating material includes Teflon, boron nitride, carbon nanotube, or any combination thereof.