KR102765948B1 - Ceria particle for abrasive and slurry comprising the same - Google Patents

Abstract

The present invention relates to a polishing ceria particle having an excellent polishing rate for planarizing a body to be polished and effectively suppressing the occurrence of scratches on the body to be polished. Specifically, the polishing ceria particle provided according to one embodiment includes a facet, which is a region in which at least one of the {1, 0, 0} and {1, 1, 1} crystal planes forms a surface based on the {h, k, l} crystal plane family defined by the Miller index, and includes a first Raman peak located in a range of 455 to 465 cm ^-1 and a second Raman peak located in a range of 600 to 610 cm ^-1 in a Raman spectrum.

Description

{Ceria particle for abrasive and slurry comprising the same}

The present invention relates to abrasive ceria particles and a slurry containing the same, and more particularly, to abrasive ceria particles and a slurry containing the same, which have an excellent polishing rate and can effectively suppress scratches that may occur on the surface of a body to be polished during a polishing process.

In the chemical mechanical polishing (CMP) process, which is usually performed to planarize semiconductor wafers during a semiconductor process, a polishing slurry is used in which metal oxide polishing particles for mechanical polishing and dispersants or additives for chemical reaction with the semiconductor substrate, which is the object to be polished, are mixed and dispersed in deionized water. This polishing slurry needs to have a constant polishing speed while minimizing defects such as scratches on the surface of the semiconductor substrate, which is the object to be polished, after the CMP process.

In particular, a slurry containing cerium oxide nanoparticles is used in a shallow trench isolation (STI) process for selectively polishing a silicon oxide film. When cerium oxide is used as an abrasive particle, the excellent redox properties and catalytic properties of cerium oxide enable easy removal of the silicon oxide film through a chemical reaction with the silicon oxide film. In these abrasive particles, the selectivity and flatness, etc. vary depending on the material properties of the manufactured cerium oxide itself, so that the physicochemical properties of cerium oxide greatly contribute to the improvement of the polishing properties.

However, as semiconductor devices are required to be highly integrated and dense, the line width of wiring patterns is becoming finer, and devices are becoming thinner, the scratch level on the wafer surface or the surface of the workpiece is directly related to the production yield, and therefore the importance of reducing scratches that may occur during the polishing process is increasing. In addition, since slurry containing expensive cerium oxide is being used not only in the STI process but also in the pre-metal dielectric (PMD) process, it is required to reduce the manufacturing cost by simplifying the manufacturing process.

To meet these requirements, Korean Patent No. 10-1117525 provides cerium oxide abrasive particles using a hydrothermal reaction that dissolves the sharp particle surface of cerium oxide abrasive particles pulverized through a milling process. However, the size of the abrasive particles is not uniform, it is still not free from scratches on the object to be polished, and its manufacturing process is complicated.

Accordingly, there is a need for the development of cerium-based nanoparticles that have an excellent polishing rate during the flattening process of a polished body through polishing during a semiconductor process, can minimize the occurrence of scratches on the flattened surface of the polished body after the polishing process, and can be provided economically with a simplified manufacturing process.

Republic of Korea Patent No. 10-1117525

The purpose of the present invention is to provide ceria particles which have an excellent polishing rate for planarizing a body to be polished during a semiconductor process and which can minimize the occurrence of scratches that may be formed on the surface of the body to be polished after the planarization process.

Another object of the present invention is to provide a slurry for chemical mechanical polishing (CMP) comprising ceria particles capable of effectively suppressing scratch formation while having an excellent polishing rate.

According to one embodiment of the present invention, a polishing ceria particle includes a facet, which is a region in which at least one of the {1, 0, 0} and {1, 1, 1} crystal planes forms a surface based on the {h, k, l} crystal plane family defined by a Miller index, and includes a first Raman peak located in a range of 455 to 465 cm ^-1 and a second Raman peak located in a range of 600 to 610 cm ^-1 in a Raman spectrum.

In the abrasive ceria particles according to one embodiment of the present invention, the ratio (I ₁ /I _{2 ) of the intensity of the first Raman peak (I 1 )} divided by the intensity of the second Raman peak (I ₂ ) may be 30 to 60.

In the abrasive ceria particles according to one embodiment of the present invention, the ceria particles may further include a third Raman peak located in the range of 1150 to 1200 cm ^-1 .

In the abrasive ceria particles according to one embodiment of the present invention, the ratio (I ₁ /I _{3 ) of the intensity of the first Raman peak (I 1 )} divided by the intensity of the third Raman peak (I ₃ ) may be 200 to 250.

In the abrasive ceria particles according to one embodiment of the present invention, the facet, which is a region forming the surface of the ceria particles, may include edge dislocations.

In an embodiment of the present invention, a polishing ceria particle, wherein when polishing a silicon oxide film using the ceria particle, the number of first scratches satisfying the following equation 1 under the following surface roughness measurement conditions using an atomic force microscope (AFM) is 10 or less.

(Surface roughness measurement conditions)

AFM scan: 50 randomly selected 0.5 μm x 0.5 μm square unit scan areas

(Formula 1)

S1 ≥ 1.5 nm

In Equation 1, S1 is a parameter indicating the first scratch and is each RMS (Root Mean Square) value measured in 50 randomly selected scan areas.

In the abrasive ceria particles according to one embodiment of the present invention, for 100 line profiles connecting opposing edges in straight lines in each of the 50 square unit scan areas, the number of second scratches satisfying the following Equation 2 may be 10 or less.

(Formula 2)

S2 ≤ k H _min (ave)

In Equation 2, H _min (ave) is the average of the lowest height H _min in each line profile having the highest height as the origin (0), k is a real number greater than or equal to 1.5, and S2 is the height of the area defined as the second scratch in the line profile.

In the abrasive ceria particles according to one embodiment of the present invention, the ceria particles may be polygonal including 3 to 8 facets.

In the abrasive ceria particles according to one embodiment of the present invention, the ceria particles may include crystal particles having a size of 1 to 60 nm.

In the abrasive ceria particles according to one embodiment of the present invention, the ceria particles may be aggregated particles in which the crystal particles are aggregated.

In the abrasive ceria particles according to one embodiment of the present invention, the aggregated particles may have a size of 20 to 200 nm.

In the abrasive ceria particles according to one embodiment of the present invention, the ceria particles may have a surface charge and a zeta potential of -40 to +60 mV in an aqueous dispersion state at pH 4.

According to another aspect of the present invention, a slurry for chemical mechanical polishing (CMP) comprising the aforementioned abrasive ceria particles is provided.

A slurry for chemical mechanical polishing (CMP) according to one embodiment of the present invention may further include a dispersant.

According to one embodiment of the present invention, the abrasive ceria particles include a facet, which is a region in which at least one of the {1, 0, 0} and {1, 1, 1} crystal planes forms a surface based on the {h, k, l} crystal plane family defined by the Miller index, and include a first Raman peak located in the range of 455 to 465 cm ^-1 and a second Raman peak located in the range of 600 to 610 cm ^-1 in a Raman spectrum, thereby effectively suppressing the occurrence of scratches on a body to be polished and providing an excellent polishing rate for planarization of the body to be polished.

FIG. 1 is a drawing illustrating an X-ray diffraction (XRD) pattern of ceria particles manufactured according to one embodiment of the present invention.
FIG. 2(a) is a drawing showing a field emission scanning electron microscope (FE-SEM) image of ceria particles obtained in Example 3, and FIGS. 2(b) and 2(c) are drawings showing high-resolution transmission electron microscope (HR-TEM) images of Example 3.
FIG. 3 is a drawing illustrating a Raman spectrum of ceria particles manufactured according to one embodiment of the present invention.

The present invention will be described in more detail below through specific examples or embodiments including the attached drawings. However, the following specific examples or embodiments are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Also, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein for the purpose of description is only for the purpose of effectively describing particular embodiments and is not intended to be limiting of the invention.

Additionally, the singular forms used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise.

Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

According to one aspect of the present invention, the abrasive ceria particles provided include a facet, which is a region in which at least one of the {1, 0, 0} and {1, 1, 1} crystal planes forms a surface based on the {h, k, l} crystal plane family defined by the Miller index, and include a first Raman peak positioned in a range of 455 to 465 cm ^-1 and a second Raman peak positioned in a range of 600 to 610 cm ^-1 in a Raman spectrum.

Conventionally, it can have the effect of reducing the occurrence of scratches on the object to be polished by alleviating the sharpness of the sharp particle surface of the abrasive particles, but it has the disadvantage of reducing the polishing rate of the object to be polished, and the sharp particle surface of the cerium oxide pulverized through the milling process may still be included, so it has the disadvantage of being inefficient in suppressing the occurrence of scratches on the object to be polished.

On the other hand, the abrasive ceria particles according to one embodiment of the present invention include a facet, which is a region in which at least one of the {1, 0, 0} and {1, 1, 1} crystal planes forms a surface based on the {h, k, l} crystal plane family defined by the Miller index, and includes a first Raman peak located in the range of 455 to 465 cm ^-1 and a second Raman peak located in the range of 600 to 610 cm ^-1 in a Raman spectrum. Accordingly, the occurrence of scratches that may occur on a body to be polished during polishing using the ceria particles of the present invention is effectively suppressed, and the body to be polished after the final planarization process is completed can be advantageous for highly integrated and high-density semiconductor devices.

In particular, when a slurry for chemical mechanical polishing (CMP) including ceria particles according to one embodiment of the present invention is used as an abrasive in a shallow trench isolation (STI) process, the polishing selectivity of a silicon oxide film and a silicon nitride film can be improved due to the more excellent physicochemical properties of the particles, and scratch occurrence can be significantly reduced while being advantageous for high planarization.

In one embodiment, the ceria particles can be polygonal having from 3 to 20, specifically from 3 to 16, more specifically from 3 to 8 facets.

Specifically, in order to generally minimize scratches that may be formed on the surface of a polished body during the flattening process of the polished body, abrasive particles having a spherical or quasi-spherical shape are provided. However, the abrasive ceria particles according to one embodiment of the present invention have a polygonal shape including facets, which are regions forming the particle surface, and include a first Raman peak located in the range of 455 to 465 cm ^-1 and a second Raman peak located in the range of 600 to 610 cm ^-1 in a Raman spectrum, thereby effectively suppressing the occurrence of scratches on the surface of a polished body and providing an excellent polishing rate.

As a specific example, the first Raman peak may be a Raman peak located in a range of 458 to 465 cm ^-1 , specifically in a range of 460 to 464 cm ^-1 , and the second Raman peak may be a Raman peak located in a range of 602 to 608 cm ^-1 , specifically in a range of 604 to 606 cm ^-1 .

As a specific example, the ratio (I ₁ /I _{2 ) of the intensity of the first Raman peak (I 1 )} divided by the intensity of the second Raman peak (I ₂ ) may be 20 to 80, specifically 30 to 60, more specifically 36 to 50, and even more specifically 38 to 45.

Here, the intensity of a Raman peak may mean the maximum intensity value located within a specific Raman shift range in a Raman spectrum.

The intensity of the second Raman peak in the Raman spectrum of ceria particles may indicate the degree of surface defects of the ceria particles, and the intensity of the second Raman peak may appear higher as the surface defects of the ceria particles increase. At this time, the ceria particles may be pulverized during the polishing process due to the presence of surface defects, thereby effectively suppressing the occurrence of scratches on the surface of the polished body. However, if there are too many surface defects, although it may be effective in suppressing the occurrence of scratches, the polishing rate may decrease. Therefore, in order to provide an excellent polishing rate and efficiently suppress the occurrence of scratches, it is advantageous for the ratio of the intensity of the first Raman peak (I ₁ ) divided by the intensity of the second Raman peak (I ₂ ) (I ₁ /I ₂ ) to satisfy the above-mentioned range.

In one embodiment, the ceria particles may further include a third Raman peak positioned in the range of 1150 to 1200 cm ^-1 , and a ratio of the intensity of the first Raman peak (I ₁ ) divided by the intensity of the third Raman peak (I ₃ ) (I ₁ /I ₃ ) may be 150 to 300, specifically 200 to 250, and more specifically 210 to 230.

In one embodiment, the ceria particles may include one or more crystallographic defects selected from line defects including edge dislocations, planar defects including twinning, and mixed defects thereof.

The occurrence of scratches on the polished body may be suppressed by crystallographic defects contained in the ceria particles during polishing. As a specific example, the occurrence of scratches that may occur on the polished body may be suppressed by the aforementioned crystallographic defects, which are caused by the ceria particles being crushed into a smaller size.

As an advantageous example, facets, which are regions forming the particle surface of ceria particles, can contain edge dislocations.

Specifically, in the case of ceria particles containing blade dislocation in the facet, which is a region forming the particle surface, the blade dislocation can move along the dislocation line during the polishing process, and the ceria particles can ultimately be crushed into smaller sizes, which effectively suppresses the occurrence of scratches on the surface of the object to be polished that may occur during polishing. In addition, since the ceria particles crushed into smaller sizes can continuously polish the object to be polished by exposing new facets, it can have the advantage of effectively flattening the surface of the object to be polished while minimizing the occurrence of scratches.

In one embodiment, the ceria particles may include crystal particles having a size of 1 to 100 nm, specifically, a size of 1 to 60 nm, more specifically, a size of 10 to 60 nm, and more specifically, a size of 20 to 40 nm. In this case, the size of the particle may mean the longest length in a straight line distance from a unit particle, and the longest length may be a value measured from a scanning electron microscope (SEM) image of the ceria particles.

Here, the ceria particles may be particles having a single crystal structure, but it is not excluded that particles having a polycrystalline structure are included.

For example, in the case of ceria particles having a polycrystalline structure including grain boundaries, the grain size may be 10 to 50 nm, specifically 15 to 40 nm, more specifically 20 to 35 nm, and even more specifically 25 to 30 nm.

Here, the grain size can be calculated using the Scherrer equation based on the XRD pattern measured using X-ray diffraction (XRD).

In general, there is a trade-off relationship between the polishing efficiency and scratch occurrence probability of the polished object with respect to the size of the abrasive particles. That is, as the size of the abrasive particles increases, the polishing speed and polishing rate increase, but there is a problem that the scratch occurrence rate of the polished object also increases, and as the size of the abrasive particles decreases, the scratch occurrence rate can be reduced, but there is a problem that the polishing speed and polishing rate decrease significantly.

Conventionally, a polishing rate is improved by providing cerium oxide abrasive particles having a blunt particle surface and an average size of up to 700 nm, but there is a problem that the scratch occurrence rate of a polished body may be increased. On the other hand, ceria particles according to one embodiment of the present invention can effectively suppress scratch occurrence while exhibiting an excellent polishing rate due to the crystallographic characteristics of ceria particles despite having a relatively significantly small size.

In one embodiment, the ceria particles may be aggregated particles in which the above-described crystal particles are aggregated. At this time, the aggregated particles may have a size of, but not limited to, 10 to 200 nm, 20 to 200 nm, 20 to 100 nm, 20 to 80 nm, or 20 to 60 nm.

As an example, when polishing a silicon oxide film using the ceria particles described above, the number of first scratches satisfying the following equation 1 may be 10 or less under the following surface roughness measurement conditions using an atomic force microscope (AFM).

(Surface roughness measurement conditions)

AFM scan: 50 randomly selected 0.5 μm x 0.5 μm square unit scan areas

(Formula 1)

S1 ≥ 1.5 nm

In Equation 1, S1 is a parameter indicating the first scratch, and is each RMS (Root Mean Square) value measured in 50 randomly selected scan areas.

The first scratch satisfying Equation 1 may be a macro scratch of a micrometer scale, and the size of the first scratch may be 1 μm or more, 5 μm or more, 10 μm or more, 100 μm or more, 200 μm or more, 500 μm or more, and may be substantially 5000 μm or less.

At this time, the parameter S1 indicating the first scratch resulting from the presence of a macro scratch may be 1.5 nm or more, 1.6 nm or more, 1.7 nm or more, or 1.8 nm or more, and may be substantially 2.0 nm or less.

As a specific example, when polishing a silicon oxide film using the above-described ceria particles, the number of first scratches satisfying the above formula 1 may be 5 or less, 3 or less, 2 or less, 1 or less, or substantially 0.

Here, polishing of a silicon oxide film using ceria particles may be performed by supplying a slurry containing the above-described ceria particles and according to the following polishing conditions.

(Polishing conditions)

Grinder: UNIPLA 231 (Doosan Mechatech)

Pad: K-7 (Rohm&Hass)

Polishing time: 60s

Polishing pressure: 3 to 4 psi

Rotation speed of platen and head: 30 and 60 rpm respectively

Polishing material: 8 inch SiO ₂ blanket wafer (PE-TEOS,Poly)

Slurry composition for CMP: Aqueous dispersion containing 0.5 wt% ceria particles

Slurry feed rate: 200mL/min

In one specific example, for 100 line profiles connecting opposite edges in each of the 50 square unit scan areas, the number of second scratches satisfying Equation 2 below may be 10 or less.

(Formula 2)

S2 ≤ k H _min (ave)

In Equation 2, H _min (ave) is the average of the lowest height H _min in each line profile having the highest height as the origin (0), k is a real number greater than or equal to 1.5, and S2 is the height of the area defined as the second scratch in the line profile.

The second scratch satisfying the above equation 2 may be a micro scratch on a nanometer scale, and the k may be 1.6 or more, 1.8 or more, 2.0 or more, 2.5 or more, 3.0 or more, and may be substantially 5.0 or less.

As a specific example, S2, a parameter indicating a second scratch, can be a negative value, and can be -20 nm or less, -19 nm or less, -18 nm or less, -17 nm or less, -16 nm or less, -15 nm or less, -14 nm or less, -13 nm or less, -12 nm or less, -11 m or less, and can be substantially -1 nm or more, and more substantially -5 nm or more. In this case, the larger the absolute value of S2 indicating a negative value, the deeper the scratch may be.

As a specific example, when polishing a silicon oxide film using the aforementioned ceria particles, the number of second scratches satisfying the above formula 2 may be 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, and may actually be 1 or more.

As an example, the ceria particles can have a surface charge and a zeta potential of -40 to +60 mV in an aqueous dispersion at pH 4.

In a specific example, the ceria particles can have a zeta potential selected from the ranges of +15 to +60 mV, +20 to +50 mV, +25 to +40 mV, -40 to -15 mV, -30 to -15 mV or -25 to -15 mV.

Since the surface charge of ceria particles has a high absolute value of zeta potential as in the aforementioned range, it can have excellent dispersibility in an aqueous dispersion, and thus has the advantage of further improving the polishing rate of the polishing object.

In one embodiment, the ionic conductivity of the dispersed ceria particles, i.e., the aqueous dispersion, may be 1 to 100 μs/cm, specifically 5 to 50 μs/cm, and more specifically 5 to 20 μs/cm.

Since the ionic conductivity of the aqueous dispersion containing ceria particles satisfies the above-mentioned range, the ceria particles can have excellent dispersibility even in the slurry for chemical mechanical polishing (CMP) described later, thereby improving the polishing efficiency.

According to another aspect, the present invention provides a slurry for chemical mechanical polishing (CMP) comprising the abrasive ceria particles described above.

In one specific embodiment of the present invention, the CMP slurry may contain 0.1 to 20 wt% of ceria particles, specifically 0.5 to 10 wt%, and more specifically 0.5 to 5 wt%, based on the total weight. When the CMP slurry contains ceria particles less than 0.1 wt%, polishing does not occur sufficiently, so that the object to be polished is not smoothly flattened. When the CMP slurry contains ceria particles more than 20 wt%, the polishing rate is high, which may cause excessive polishing of the object to be polished, and the initial dispersibility of the ceria particles contained in the CMP slurry is poor, which may deteriorate the polishing quality. Therefore, it is preferable that the CMP slurry contain ceria particles within the above range based on the total weight.

In one embodiment of the present invention, the slurry for chemical mechanical polishing (CMP) may further include a dispersant.

The dispersant is a material that is widely used in the art to improve the dispersion of ceria particles in a CMP slurry, and there is no limitation on its use. For example, the dispersant may include at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, polyoxyalkylene alkyl ether, polyoxyalkylene alkyl ester, polyoxypropylene ether, polyoxyethylene methyl ether, polyethylene glycol sulfonic acid, polyethylene oxide, polypropylene oxide, polyalkyl oxide, polyoxyethylene oxide, polyethylene oxide-propylene oxide copolymer, cellulose, methylcellulose, methylhydroxyethyl cellulose, methylhydroxypropyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, carboxymethyl hydroxyethyl cellulose, glycerin, polypropylene glycol, sulfoethyl cellulose, and carboxymethyl sulfoethyl cellulose.

In one specific example, the dispersant may be included in an amount of 0.01 to 15 wt%, preferably 0.05 to 10 wt%, and more preferably 1 to 5 wt%, based on the total weight of the CMP slurry. In order to improve the dispersibility of the ceria particles included in the CMP slurry without lowering the polishing rate and thereby increase the polishing uniformity of the surface of the workpiece, it is preferable that the dispersant be included in the CMP slurry within the above range.

According to another aspect, the present invention provides a method for producing abrasive ceria particles.

A method for producing abrasive ceria particles comprises the steps of: a) discharging plasma to a cerium precursor solution in which a cerium precursor and a solvent are mixed, to produce ceria particles including a facet, which is a region in which at least one of the {1, 0, 0} and {1, 1, 1} crystal planes forms a surface based on the {h, k, l} crystal plane family defined by a Miller index, and including a first Raman peak positioned in a range of 455 to 465 cm ^-1 and a second Raman peak positioned in a range of 600 to 610 cm ^-1 in a Raman spectrum; and b) washing the produced ceria particles.

Conventionally, in manufacturing abrasive ceria particles, the ceria particles are crushed and a hydrothermal reaction process is performed for up to 48 hours to soften the sharp edges of the crushed ceria particles and change them into a blunt shape. This has the disadvantage of being a complex manufacturing process and requiring a long manufacturing time.

On the other hand, the method for manufacturing abrasive ceria particles according to the present invention can provide abrasive ceria through a simple process by manufacturing ceria particles having the above crystallographic characteristics and Raman characteristics through underwater plasma treatment, and then going through a post-treatment process of washing the manufactured ceria particles, so the manufacturing process can be simplified compared to the conventional process, and the manufacturing time can also be significantly reduced.

Hereinafter, a method for manufacturing abrasive ceria particles is described in more detail step by step. However, since the types of each constituent material are the same or similar to those described above, duplicate descriptions are omitted.

In a method for manufacturing abrasive ceria particles according to one embodiment of the present invention, the cerium precursor may include cerium having a trivalent and/or tetravalent oxidation state, and examples thereof include Ce(NO ₃ ) ₃ , Ce(NO ₃ ) ₃ xH ₂ O, (NH ₄ ) ₂ Ce(NO ₃ ) ₆ , (NH4) ₂ Ce(NO ₃ ) ₆ xH ₂ O, Ce(NH ₄ ) ₄ (SO ₄ ) ₄ , Ce(NH ₄ ) ₄ (SO ₄ ) ₄ xH ₂ O, Ce ₂ (CO ₃ ) ₃ , Ce(OH) ₄ , CeC ₂ , Ce(O ₂ C ₂ H ₃ ) ₃ xH ₂ O, CeBr ₃ , Ce ₂ (CO ₃ ) ₃ xH ₂ O, CeCl ₃ xH ₂ O, CeCl ₃ , CeF ₃ , CeF ₄ , Ce ₂ (C ₂ O ₄ ) ₃ , Ce(SO ₄ ) ₂ , Ce(SO ₄ ) ₂ xH ₂ O, Ce ₂ (SO ₄ ) ₃ , and Ce ₂ (SO ₄ ) ₃ xH ₂ O.

As an example, the cerium precursor solution may be a solution in which the cerium precursor described above and a solvent are mixed, and the solvent may be used without limitation as long as it is a solvent capable of performing the underwater plasma discharge described below, but as an example, it may include at least one of deionized water and an organic solvent, and preferably, it may be a solvent in which deionized water and an organic solvent are mixed, and the organic solvent may be an alcohol solvent including a polyol, and specifically, it may be ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, methyl alcohol, isopropyl alcohol, ethanol, methoxyethanol, acetone, toluene, and the like.

In a solvent comprising a mixture of deionized water and an organic solvent, the volume ratio of deionized water: organic solvent may be 1:0.01 to 10, specifically 1:0.05 to 5, and more specifically 1:0.1 to 1.

When a solvent containing deionized water and an organic solvent is mixed with a cerium precursor, spontaneous precipitation can occur, which can increase the efficiency of the underwater plasma discharge described later, and as a result, when ceria particles are manufactured by the high temperature and/or high pressure generated momentarily and locally during plasma generation, ceria particles containing the aforementioned crystallographic defects and Raman characteristics can be generated due to strong energetic stress.

At this time, since the plasma is generated locally, in order to increase the production yield of ceria particles including the aforementioned crystallographic defects and Raman characteristics, it is preferable that the cerium precursor solution be prepared using a solvent in which deionized water and an organic solvent are mixed, with a volume ratio of deionized water:organic solvent within the above range.

In one embodiment, the concentration of the cerium precursor solution can be from 100 to 800 mM, specifically from 200 to 600 mM, and more specifically from 250 to 450 mM.

In one embodiment, the discharge of the underwater plasma can be performed by any one plasma power source selected from alternating current, direct current, high voltage pulse, radio frequency (RF), and microwave.

Specifically, the supply voltage applied from the aforementioned plasma power source may be 100 to 400 V, preferably 120 to 300 V, and more preferably 130 to 220 V, and the supply current may be applied at 0.1 to 50 A, preferably 1 to 40 A, and more preferably 10 to 30 A.

In order to uniformly form the size of ceria particles manufactured by efficiently generating plasma discharge, it is recommended to generate plasma discharge by supplying voltage and current within the above range.

In one specific example, the plasma discharge may be performed sequentially 1 to 5 times, specifically 2 to 4 times, and the conditions of each plasma discharge performed sequentially may be independently the same or different from each other.

At this time, the size and shape of the ceria particles can be controlled according to the power applied for plasma discharge, and the size and shape of the ceria particles can be the same as or similar to those described above.

In one embodiment of the present invention, the cerium precursor solution may further include a catalyst before performing the plasma discharge in step a).

In detail, the cerium precursor solution may contain 0.001 to 10 vol%, specifically 0.001 to 5 vol%, and more specifically 0.01 to 1 vol% of the catalyst. As the catalyst is contained in the cerium precursor solution in the above range, the plasma discharge described above can be intensely generated at the supplied voltage described above, and thus the size and shape of the ceria particles produced can be controlled.

In one specific example, the catalyst may be at least one selected from KNO ₃ , CH ₃ COOK, K ₂ SO ₄ , KCl, LiOH, KOH, Ca(OH) ₂ , Ni(OH) ₂ , Mg(OH) ₂ , KF, NaOH, NaF, Na ₂ O, CH ₃ COONa, Na ₂ SO ₄ , C ₅ H ₅ N, NaOCl, K ₂ C ₂ O ₄ , NH ₄ OH and N ₂ H ₄ , preferably at least one selected from NH ₄ OH and N ₂ H ₄ .

As an example, the above-described ceria particles manufactured via plasma discharge can be washed to provide abrasive ceria particles.

According to one embodiment of the present invention, the washed ceria particles in step b) can be mixed with deionized water to prepare a slurry for CMP, and at this time, the CMP slurry can contain 0.1 to 20 wt% of the ceria particles, specifically 0.5 to 10 wt%, and more specifically 0.5 to 5 wt%, based on the total weight.

According to one embodiment of the present invention, after step b), a step of adding a dispersant to the slurry for CMP may be further included, and the added dispersant may be the same as or similar to that described above.

At this time, a dispersant may be added to the CMP slurry based on the ionic conductivity of the aqueous dispersion containing the aforementioned ceria particles, and in order to maintain excellent dispersibility of the ceria particles within the CMP slurry and improve polishing efficiency, the dispersant may be included at 0.01 to 15 wt%, preferably 0.05 to 10 wt%, and more preferably 1 to 5 wt%, based on the total weight of the CMP slurry.

In one specific example, the ionic conductivity of the slurry for CMP may be 0.1 to 100 uS/cm, specifically 1 to 50 uS/cm, and more specifically 3 to 30 uS/cm.

Hereinafter, the polishing ceria particles according to the present invention and the CMP slurry containing the same will be described in more detail through examples. However, the following examples are only a reference for explaining the present invention in detail, and the present invention is not limited thereto and may be implemented in various forms.

Also, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description herein is only for the purpose of effectively describing specific embodiments and is not intended to limit the present invention. Also, the unit of additives not specifically described in the specification may be weight percent.

(Example 1)

A cerium precursor solution was prepared by mixing 600 g of Ce( _NO3 ) _36H2O precursor in a solvent containing 4 L of _deionized water and ethanol at a volume % of 1:0.5, and then a first plasma discharge was performed for 5 minutes by supplying 150 V voltage with a 60 Hz AC power supply to the prepared cerium precursor solution, and then a second plasma discharge was performed for 2 minutes by supplying 200 V voltage. Thereafter, the obtained ceria particles were precipitated for 10 to 15 minutes, and the obtained ceria particles were washed five times with deionized water, and then the obtained ceria particles were mixed with deionized water to prepare a CMP slurry containing 0.5 wt% of ceria particles.

(Example 2)

A slurry for CMP was prepared by performing the same procedure as in Example 1, except that 600 g of (NH ₄ ) ₂ Ce(NO ₃ ) ₆ was used as a cerium precursor.

(Example 3)

The same procedure as in Example 1 was followed, but a cerium precursor solution and a N ₂ H ₄ catalyst were added to prepare a slurry for CMP after plasma discharge.

(Example 4)

The same procedure as in Example 1 was followed, but a cerium precursor solution and NH ₄ OH catalyst were added to prepare a slurry for CMP after plasma discharge.

(Example 5)

The same procedure as in Example 1 was performed, but 2 wt% of ethylene glycol (dispersant) was added based on the total weight of the slurry for CMP.

(Comparative Example 1)

A slurry for CMP was manufactured by performing the same procedure as in Example 1, except that only the first plasma discharge was performed for 5 minutes by supplying 200 V voltage with a 60 Hz AC power supply.

(Comparative Example 2)

The same procedure as in Example 1 was followed, except that a cerium precursor solution prepared using deionized water as a solvent instead of a mixed solvent was used.

(Experimental Example 1) Analysis of ceria particles

Figure 1 is a drawing illustrating an X-ray diffraction (XRD) pattern of Example 3. As illustrated in Figure 1, peaks having 2 theta values positioned at about 27°, 33°, and 47° correspond to the (111), (200), and (220) planes of ceria, respectively, confirming that ceria particles were produced through underwater plasma discharge.

In addition, the grain size was calculated using the Scherrer equation with the half width at the center peak of the (111) plane of the ceria particles, and it was confirmed that the grain size was 26 to 29 nm.

Although not illustrated in the drawing, it was confirmed that ceria particles were produced in Examples 1, 2, 4, 5, and Comparative Examples 1 and 2.

FIG. 2(a) is a drawing showing a field emission scanning electron microscope (FE-SEM) image of ceria particles obtained in Example 3, and FIGS. 2(b) and 2(c) are drawings showing high-resolution transmission electron microscope (HR-TEM) images of Example 3.

As shown in Fig. 2(a), it was confirmed that ceria particles of 25 to 40 nm in size were manufactured and independently dispersed without agglomeration, and Figs. 2(b) and 2(c) confirmed that the ceria particles contained edge dislocations and twinning defects. In particular, it was observed that the edge dislocations were included in the facets of the ceria particles. In particular, a relatively large number of edge dislocations were observed in Examples 1 to 4 compared to Comparative Examples 1 and 2.

Additionally, the particle shape and particle size observed from FE-SEM images for each ceria particle are summarized in Table 1 below.

(Table 1)

FIG. 3 is a diagram illustrating a Raman spectrum of Example 3. As shown in FIG. 3, it was confirmed that the first Raman peak was included at a Raman shift of about 462 cm ^-1 , the second Raman peak was included at a Raman shift of about 605 cm ^-1 , and the third Raman peak was included at a Raman shift of about 1180 cm ^-1 .

The Raman characteristics for each ceria particle, i.e., the ratio of the intensity of the first Raman peak (I ₁ ) divided by the intensity of the second Raman peak (I ₂ ) along with the positions of each Raman peak (I ₁ /I ₂ ) and the ratio of the intensity of the first Raman peak (I ₁ ) divided by the intensity of the third Raman peak (I ₃ ) (I ₁ /I ₃ ) are summarized in Table 2 below.

(Table 2)

Referring to Table 2, it can be seen that the positions of the Raman peaks of Examples 1 to 4 and Comparative Examples 1 to 2 manufactured using underwater plasma discharge appear similar, but the intensity ratios of the Raman peaks appear different. This is because, as confirmed from the HR-TEM images described above, in Examples 1 to 4 containing a relatively large number of defects, the intensity of the second Raman peak increases, resulting in a smaller I ₁ /I ₂ value compared to Comparative Examples 1 and 2.

(Experimental Example 2) Polishing Characteristics Analysis

Polishing was performed under the following conditions using the CMP slurry manufactured according to each example and comparative example, and the polishing characteristics were compared and analyzed.

(Polishing conditions)

Grinder: UNIPLA 231 (Doosan Mechatech)

Pad: K-7 (Rohm&Hass)

Polishing time: 60s

Polishing pressure: 3 psi

Rotation speed of platen and head: 30 and 60 rpm respectively

Workpiece: 8 inch SiO ₂ blanket wafer (PE-TEOS, Poly)

Slurry feed rate: 200mL/min

After polishing the object to be polished under the above polishing conditions, the polishing rate, the number of first scratches, and the number of second scratches confirmed are summarized in Table 3 below.

At this time, the first scratch was measured for surface roughness using an atomic force microscope (AFM) in 50 randomly selected square unit scan areas of 0.5 μm x 0.5 μm in size after polishing, and the first scratch was determined to exist when the RMS value for each obtained scan area was 1.5 nm or more.

In addition, it was determined that a second scratch exists when the following Equation 2 is satisfied for 100 line profiles connecting opposite edges in each of 50 square unit scan areas.

(Formula 2)

S2 ≤ k H _min (ave)

In Equation 2, H _min (ave) is the average of the lowest height H _min in each line profile having the highest height as the origin (0), k is a real number equal to 2.5, and S2 is the height of the area defined as the second scratch in the line profile.

(Table 3)

Referring to Table 3, it was confirmed that the polishing rates of Examples 3 to 5, in which the shape of the ceria particles included in the CMP slurry was square and the particle size was relatively large, were excellent.

Regarding the scratches formed on the surface of the polished body after polishing, the RMS value was checked for a square unit scan area of 0.5 μm x 0.5 μm in size, and as a result, it showed 1.5 nm or less overall, and the number of first scratches hardly occurred. However, in Example 4, one unit scan area with an RMS value of 1.6 nm was observed, and in Comparative Example 1, it was confirmed that there was one unit scan area showing an RMS value of 1.8 nm, and in Comparative Example 2, it was confirmed that there were two unit scan areas in which the RMS value exceeded 1.5 nm. In this case, when the scan area with an RMS value of 1.5 nm or more was observed with an optical microscope, it was confirmed that scratches of about 10 to 50 μm in size were present.

On the other hand, when the number of second scratches was confirmed based on S2, a parameter indicating the second scratch in the above equation 2, in the cases of Examples 1 to 5, 6 or fewer second scratches were observed, but in the cases of Comparative Examples 1 and 2, more than 10 second scratches were observed. At this time, it was confirmed that the observed second scratches had an S2 value of -11 to -18 nm.

From this, it can be seen that when a silicon oxide film is polished using a CMP slurry containing polishing ceria particles according to one embodiment of the present invention, not only can a significantly excellent polishing rate be provided, but also the occurrence of both micrometer-scale macroscopic scratches and nanometer-scale microscopic scratches can be effectively suppressed.

Although the present invention has been described through specific matters and limited examples as above, these have been provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations from this description.

Therefore, the idea of the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the claims described below as well as the claims are included in the scope of the idea of the present invention.

Claims (12)

It includes a facet, which is a region where the {1, 0, 0} crystal plane forms a surface based on the {h, k, l} crystal plane family defined by the Miller index,
A Raman spectrum comprising a first Raman peak located in the range of 455 to 465 cm ^-1 , a second Raman peak located in the range of 600 to 610 cm ^-1 , and a third Raman peak located in the range of 1150 to 1200 cm ^-1 ,
The ratio (I ₁ /I ₂ ) of the intensity of the first Raman peak (I ₁ ) divided by the intensity of the second Raman peak (I ₂ ) is 30 to 60.
The ratio (I ₁ /I ₃ ) of the intensity of the first Raman peak (I ₁ ) divided by the intensity of the third Raman peak (I ₃ ) is 200 to 250.
The above facets are abrasive ceria particles containing edge dislocations. delete delete delete delete In the first paragraph,
Polishing ceria particles having a number of first scratches satisfying the following equation 1 of 10 or less under the following surface roughness measurement conditions using an atomic force microscope (AFM) when polishing a silicon oxide film using the above ceria particles.
(Surface roughness measurement conditions)
AFM scan: 50 randomly selected 0.5 μm x 0.5 μm square unit scan areas
(Formula 1)
S1 ≥ 1.5 nm
(In Equation 1, S1 is a parameter indicating the first scratch and is each RMS (Root Mean Square) value measured in 50 randomly selected scan areas.) In Article 6,
Abrasive ceria particles having a number of second scratches satisfying Equation 2 below of 10 or less for 100 line profiles connecting opposite edges in straight lines in each of the 50 square unit scan areas above.
(Formula 2)
S2 ≤ k H _min (ave)
(In Equation 2, H _min (ave) is the average of the lowest height H _min in each line profile having the highest height as the origin (0), k is a real number greater than or equal to 1.5, and S2 is the height of the area defined as the second scratch in the line profile.) In the first paragraph,
The above ceria particles are abrasive ceria particles having a polygonal shape containing 3 to 8 facets. In the first paragraph,
The above ceria particles are polishing ceria particles containing crystal particles having a size of 1 to 60 nm. In Article 9,
The above ceria particles are polishing ceria particles that are aggregated particles in which the above crystal particles are aggregated. In Article 10,
The above-mentioned aggregated particles are polishing ceria particles having a size of 20 to 200 nm. In the first paragraph,
The above ceria particles are polishing ceria particles having a surface charge and a zeta potential of -40 to +60 mV in an aqueous dispersion state at pH 4.