KR101345555B1 - Compositon of slurry - Google Patents

Abstract

Slurry compositions are provided. The slurry composition comprises 0.01 to 5% by weight of a metal oxide, a polishing accelerator having a weight ratio of 0.1 to 2.0 with respect to the metal oxide and a dispersion stabilizer having a weight ratio of 0.01 to 0.05 with respect to the metal oxide, the rest being deionized water or pH At least one modulator.

CMP, Slurry, Ceria, Abrasive Promoter, Dispersion Stabilizer

Description

Slurry Composition {Compositon of slurry}

1 is a schematic perspective view of a chemical mechanical polishing apparatus.

<Explanation of symbols for the main parts of the drawings>

11: polishing head 12: polishing table

13: polishing pad 14: slurry feeding device

15: pad conditioner 20: slurry composition

50: chemical mechanical polishing device

The present invention relates to slurry compositions, and more particularly to slurry compositions used in chemical mechanical polishing processes.

Chemical Mechanical Polishing (CMP) is a process of planarizing the surface of a semiconductor substrate by combining a mechanical polishing effect by an abrasive and a chemical reaction effect by an acid or base solution. In other words, chemical mechanical polishing is a planarization process that removes protruding portions of the surface of a semiconductor substrate, such as copper (Cu), which is difficult to manufacture a more efficient multi-layer wiring semiconductor device, or conventional dry etching. It was developed by IBM in the late 1980s to form damascene wiring made of material.

In the chemical mechanical polishing process, a polishing solution called a slurry is required. The slurry is a dispersion of fine particles for mechanical polishing, and a solution such as an acid or a base for chemical reaction with the semiconductor substrate to be polished is made of ultrapure water ( It refers to a solution dispersed and mixed in DI water).

Slurry used in the chemical mechanical polishing process is composed of a compound such as abrasive particles having a large physical action and etchant (chemical) acting to selectively expose the portion exposed to the surface of the semiconductor substrate by physical and chemical action Etch it. In general, the metal oxide slurry used in the chemical mechanical polishing process has good dispersibility, excellent polishing rate, low defects such as micro scratches on the surface of the semiconductor substrate after polishing, and high purity.

The metal oxide used in the slurry for chemical mechanical polishing is appropriately selected according to the type of the film to be polished. For example, silica (SiO ₂ ) is present in a large amount in the earth's crust and is relatively inexpensive. Generally, a dispersion of silica was used as the metal oxide of the slurry composition.

As described above, the silica used in the slurry composition is required to be purified in high purity, and in order to exhibit sufficient polishing rate, the silica should be contained in an amount of about 9 to 14 wt% based on the total amount of the slurry composition. In addition, when silica is discharged to the outside, there is a risk of environmental pollution, and additional costs are required to deal with it.

Therefore, in order to reduce the polishing process cost while maintaining the polishing rate, it is necessary to reduce the content of the metal oxide used as the abrasive particles of the slurry composition, and to use more environmentally friendly materials.

The technical problem to be achieved by the present invention is to provide a slurry composition that can maintain or improve the polishing rate while reducing the content of the metal oxide in the slurry composition.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

Slurry composition according to an embodiment of the present invention for achieving the above technical problem is 0.01 to 5% by weight of the metal oxide, a polishing accelerator having a weight ratio of 0.1 to 2.0 and the weight ratio of the metal oxide A dispersion stabilizer that is from 0.01 to 0.05 and at least one of deionized water or a pH adjuster as the remainder.

Specific details of other embodiments are included in the detailed description and the accompanying drawings.

Advantages and features of the present invention, and methods of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in detail. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, “comprises” and / or “comprising” does not exclude the presence or addition of one or more other components to the mentioned components. "And / or" include each and every combination of one or more of the mentioned items.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

The slurry composition according to one embodiment of the present invention includes a metal oxide, an abrasive promoter, a dispersion stabilizer, deionized water and / or a pH adjuster.

Metal oxides in the slurry composition are abrasive particles that act under pressure from the polishing apparatus to chemically polish the surface of the semiconductor substrate mechanically or by functional groups on the surface of the particles. As such a metal oxide, a material having appropriate strength, particle diameter, and chemical properties may be used in consideration of the use of polishing and the degree of polishing. For example, ceria, silica, alumina, titania, zirconia, germania or mixtures thereof can be used.

In general, the slurry composition is a consumable material, once used in the polishing process, since the particle shape of the metal oxide in the slurry composition becomes uneven and chemically modified, it is discharged without recycling and then treated with wastewater. Therefore, if the slurry contains a large amount of metal oxides, waste water treatment facilities are required because not only the processing cost increases but also the environmental pollution can be caused. Therefore, even when used in a small amount, it is required to use a metal oxide having a low risk of environmental pollution in the slurry without degrading polishing performance, for example, ceria can be used. Ceria has a chemical reaction with an object to be polished faster than silica and has a concentration of about 10 times that of silica. Thus, ceria can be used in small amounts as a metal oxide and is more environmentally friendly than silica, thereby reducing the cost of wastewater treatment.

The particle diameter of the metal oxide particles is determined in consideration of the polishing target film, the polishing degree, the polishing rate, and the like, and may be, for example, 5 to 500 nm. In particular, the metal oxide particles may have a uniform shape and particle diameter in order to increase the uniformity of the polishing. For example, all particles of metal oxides may be spherical with the same particle diameter.

The content of the metal oxide may be 0.01 to 0.5% by weight based on the total weight of the slurry composition. If the content of the metal oxide is 0.01% by weight or more, the polishing effect on the polishing object may be sufficiently exhibited. It may be at least 0.1% by weight to obtain a more suitable polishing rate. In addition, if the content of the metal oxide exceeds 5% by weight, the use of excess metal oxide may increase the cost and incur additional waste water treatment costs, while the polishing rate does not increase significantly with the increase of the metal oxide content. Preferably 0.5 weight% or less can be used. Therefore, the content of the metal oxide to exhibit a sufficient polishing rate while reducing the manufacturing cost may be 0.1% by weight to 0.5% by weight.

Polishing promoters serve to increase the polishing rate by assisting the polishing action of the metal oxide. Such polishing promoters may include at least one of ammonia, one or more quaternary amines or salts thereof. The quaternary amine can reinforce the oxide film removal rate of the slurry by the oxide film removal force of the amine itself. Quaternary amines include, but are not limited to, (CH ₃ ) ₄ NOH, (C ₂ H ₅ ) ₄ NOH, (C ₄ H ₉ ) ₄ NOH, and the like. In addition, as the salt, for example, chloride, bromide salt, iodide salt, carbonate salt, sulfate salt or nitrate may be used, but is not limited thereto.

The content of the polishing accelerator may have a range of 0.1 to 2.0 by weight to metal oxide. That is, the weight ratio of the metal oxide and the polishing promoter may be 10: 1 to 1: 2. It is preferable that the polishing accelerator is about 0.1 times (10%) or more of the metal oxide by weight in a content to exhibit a sufficient polishing promoting effect. In addition, since the polishing accelerator plays an auxiliary role for the polishing action of the metal oxide, when the amount of the metal oxide is relatively small, the amount of the polishing accelerator increases, so that the polishing promoting effect does not increase proportionally. In addition, when the content of the polishing accelerator is excessive, dispersibility may be inhibited. Therefore, considering the efficiency and dispersibility according to the amount of the polishing accelerator, the content of the polishing accelerator may be about 2 times (200%) or less of the metal oxide weight.

The dispersion stabilizer serves to stabilize the dispersion of the metal oxide, which may include water-soluble anionic compounds, water-soluble nonionic compounds, water-soluble cationic compounds, and the like. It may be a sex compound.

Examples of the water-soluble anionic compound include lauryl sulfate toriethanolamine, lauryl ammonium sulfate, polycarboxylic acid or salts thereof. The water soluble anionic compounds used as dispersion stabilizers may be, but are not limited to, polycarboxylic acids, polyacrylic acids or salts thereof in the form of polymers.

Such a dispersion stabilizer may be added so that the weight ratio of the metal oxide is 0.01 to 0.05, that is, the weight ratio of the metal oxide and the dispersion stabilizer is in the range of 99: 1 to 95: 5. When the dispersion stabilizer is added in a smaller amount than the above range, the dispersion of the metal oxide may not be sufficiently stabilized, and in the case where the dispersion stabilizer is exceeded, the polishing liquid stability may be inhibited, such as a decrease in the polishing effect over time.

Deionized water may be used as a solvent for mixing the metal oxide, the dispersion stabilizer, and the polishing accelerator. Deionized water refers to pure water that is free of inorganic salts. When the inorganic salts remain in the solvent, metal oxides, polishing accelerators, dispersion stabilizers and the like may cause chemical reactions to precipitate or contaminate the slurry composition, thereby degrading the quality of the slurry composition. Therefore, high purity deionized water may be used as the solvent of the slurry composition.

Meanwhile, the pH value of the slurry composition may be determined in consideration of polishing rate, preventing dishing, corrosion and surface roughness, viscosity of the slurry, and dispersion stability. Generally the pH of the slurry composition may be between 4 and 11 to indicate a sufficient polishing rate.

In addition, the pH of the slurry composition capable of producing a high polishing rate may vary depending on the type of metal oxide of the slurry composition. For example, when silica is used as the metal oxide, the pH may have a high polishing rate in the range of 10 to 11, but in the case of ceria, a sufficient polishing rate may be achieved when the slurry composition has a pH of 5 to 8.

Meanwhile, when the metal oxide and the dispersion stabilizer are mixed in deionized water in the slurry composition, a pH value of about 7 to 8 is shown. However, when a polishing accelerator is added thereto, the pH value rises rapidly due to the basicity of the polishing accelerator itself. Thus, pH adjusters can be added to properly adjust the pH. As the pH adjusting agent, an acid or a base may be appropriately added by comparing the pH of the slurry composition with a target pH before adding. For example, an acid such as hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), or nitric acid (HNO ₃ ) may be used as a regulator for lowering the pH.

The slurry composition according to an embodiment of the present invention may be used for polishing the silicon oxide film in the chemical mechanical polishing process, although not limited thereto. Here, the silicon oxide film which can be polished by the slurry composition is a silicon oxide film deposited by High Density Plasma Chemical Vapor Deposition (HDPCVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD). For example, it may be an interlevel dielectric (ILD), an intermetal dielectric (IMD), or a premetal dielectric (PMD).

Chemical mechanical polishing using the slurry composition according to an embodiment of the present invention may be performed by the following method, for example. Referring to FIG. 1, a semiconductor substrate w having an insulating film is first mounted on a polishing head 11 of a chemical mechanical polishing apparatus 50. A predetermined pressure is applied to bring the insulating film of the semiconductor substrate w to be polished into contact with the polishing pad 13 mounted on the polishing table 12, and the slurry composition (between the semiconductor substrate w and the polishing pad 13) While supplying 20, polishing is performed by relatively moving the semiconductor substrate w and the polishing pad 13. The slurry composition 20 may be supplied onto the polishing pad 13 from the slurry supply device 14 separately installed, or may be supplied onto the surface of the polishing pad 13 from the surface plate side. If necessary, the pad conditioner 14 may be in contact with the surface of the polishing pad 13 to adjust the surface of the polishing pad 13.

Hereinafter, the present invention will be described in more detail with reference to experimental and comparative examples. However, it should be understood that the following experimental examples are intended to illustrate the present invention and the present invention is not limited by the following experimental examples.

Experimental Example 1

First, ceria particles having a particle diameter of about 200 nm were mixed with deionized water to have a concentration of 0.25% by weight relative to the polishing liquid. Polyacrylic acid was then added as a dispersion stabilizer to 3.0% of the ceria particle weight and then dispersed. Subsequently, (CH ₃ ) ₄ NOH was added as a polishing accelerator to 0.05% by weight, that is, 0.2 times (20%) of the weight of ceria particles, and then stirred. The slurry composition was then adjusted such that the pH of the mixture was 6, 8 and 10 by adding HCl as pH adjuster while measuring the pH of the stirred mixture.

Experimental Example 2

A slurry composition was prepared in the same manner as in Experiment 1, except that (CH ₃ ) ₄ NOH was added as an polishing accelerator to 0.1 wt%, that is, 0.4 times (40%) of the weight of ceria particles.

Experimental Example 3

A slurry composition was prepared in the same manner as in Experiment 1, except that (CH ₃ ) ₄ NOH was added as an polishing accelerator to 0.2 wt%, that is, 0.8 times (80%) of the weight of ceria particles.

Experimental Example 4

A slurry composition was prepared in the same manner as in Experiment 1, except that (CH ₃ ) ₄ NOH was added as a polishing accelerator to 0.5 weight% of the polishing liquid, that is, twice the weight of ceria particles (200%).

Experimental Example 5

A slurry composition was prepared in the same manner as in Experimental Example 1, except that NH ₄ OH was added as a polishing accelerator to 0.05% by weight, that is, 0.2 times (20%) of the weight of ceria particles.

Experimental Example 6

A slurry composition was prepared in the same manner as in Experiment 1 except that NH ₄ OH was added as an polishing accelerator to 0.1 wt%, that is, 0.4 times (40%) of the weight of ceria particles.

Experimental Example 7

A slurry composition was prepared in the same manner as in Experimental Example 1, except that NH ₄ OH was added as a polishing accelerator to 0.2% by weight, that is, 0.8 times (80%) of the weight of ceria particles.

Comparative Experimental Example 1

First, ceria particles having a particle diameter of about 200 nm were mixed with deionized water to have a concentration of 0.25% by weight relative to the polishing liquid. Then, polyacrylic acid was added as a dispersion stabilizer to 3.0% of the weight of ceria particles and then dispersed to prepare a slurry composition in which the ceria particles were stably dispersed.

To investigate the polishing rate of the slurry compositions prepared by Comparative Experimental Example 1 and Experimental Examples 1 to 7 were carried out for 2 minutes at 60 rpm, 4 psi using G & P Poly-250 as the polishing apparatus. The SiO ₂ insulating film in which tetraethoxysilane was deposited by plasma organic chemical vapor deposition (PECVD) was polished and the polishing rate was measured. The results are shown in Table 1.

Polishing Accelerators and Contents Polishing rate
(Å / min, pH = 6) Polishing rate
(Å / min, pH = 8) Polishing rate
(Å / min, pH = 10) Comparative Experimental Example 1 - - 326 - Experimental Example 1 (CH ₃ ) ₄ NOH 0.05% by weight 812 805 800 Experimental Example 2 (CH ₃ ) ₄ NOH 0.1% by weight 880 859 825 Experimental Example 3 (CH ₃ ) ₄ NOH 0.2% by weight 881 871 860 Experimental Example 4 (CH ₃ ) ₄ NOH 0.5% by weight 857 883 870 Experimental Example 5 NH ₄ OH 0.05% by weight 777 688 389 Experimental Example 6 NH ₄ OH 0.1 wt% 844 701 415 Experimental Example 7 NH ₄ OH 0.2% by weight 959 708 548

As shown in Table 1, the polishing rate increases as the content of the polishing accelerator increases, but when the content of the polishing accelerator changes from 0.8 times to 2 times the weight of the ceria particle, the polishing rate does not increase significantly but may decrease slightly. It can be seen. In addition, in the case of (CH ₃ ) ₄ NOH, there was almost no change in the polishing rate as the pH was changed to 6, 8, and 10, but it was found that NH ₄ OH had the maximum polishing rate at pH 6.

Experimental Example 8

First, ceria particles having a particle diameter of about 200 nm were mixed with deionized water to have a concentration of 0.3% by weight relative to the polishing liquid. Polyacrylic acid was then added as a dispersion stabilizer to 3.0% of the ceria particle weight and then dispersed. Subsequently, (CH ₃ ) ₄ NOH was added as a polishing accelerator to 0.2% by weight relative to the polishing liquid, that is, 0.67 times (67%) of the weight of ceria particles, followed by stirring. The slurry composition was then adjusted such that the pH of the mixture was 8 by adding HCl as the pH adjusting agent while measuring the pH of the stirred mixture.

Experimental Example 9

A slurry composition was prepared in the same manner as in Experimental Example 8, except that NH ₄ OH was added at an amount of 0.2% by weight relative to the polishing liquid, that is, 0.67 times (67%) of the weight of ceria particles, and the pH was adjusted to 6. It was.

Experimental Example 10

Slurry was prepared in the same manner as in Experiment 8 except that (CH ₃ ) ₄ NOH was added as 0.3 wt% of the polishing liquid, that is, 1 times (100%) of the ceria particle weight, and adjusted to pH 8 as the polishing accelerator. The composition was prepared.

Experimental Example 11

Ceria particles having a particle diameter of 200 nm are mixed with deionized water to have a concentration of 0.5% by weight relative to the polishing liquid, and (CH ₃ ) ₄ NOH is 0.2% by weight, i.e. 0.4 times the weight of ceria particles (40) as the polishing accelerator. %) And a slurry composition was prepared in the same manner as in Experiment 8 except that the pH was adjusted to 8.

Experimental Example 12

Ceria particles having a particle diameter of 200 nm were mixed with deionized water to have a concentration of 0.5% by weight relative to the polishing liquid, and NH ₄ OH was added as 0.2% by weight, 0.4 times (40%) of the ceria particles, as the polishing accelerator. The slurry composition was prepared in the same manner as in Experiment 8, except that the pH was adjusted to 6 and adjusted to pH 6.

Comparative Experimental Example 2

A silica slurry (Cabot, product name: SS-12) containing 12% by weight of ceria and a pH of 11 was prepared.

Polishing was performed to investigate the polishing rate of the slurry compositions prepared by Comparative Experimental Example 2 and Experimental Examples 8 to 12. Polishing of the PE-TEOS insulating film deposited by CVD was performed using MIRRA-Messa as a polishing apparatus. As for polishing conditions, the rotation speed of the polishing table of the polishing apparatus was 77 rpm, the rotation speed of the polishing head was 73 rpm, and the pressure applied to the semiconductor substrate was set to 4 psi. The polishing rate was measured and the results are shown in Table 2.

Abrasive particles and content Polishing Accelerators and Contents pH Polishing rate
(Å / min) Comparative Experimental Example 2 12% by weight of ceria 11 2450 Experimental Example 8 Ceria 0.3 wt% (CH ₃ ) ₄ NOH 0.2% by weight 8 1789 Experimental Example 9 Ceria 0.3 wt% NH ₄ OH 0.2% by weight 6 1176 Experimental Example 10 Ceria 0.3 wt% (CH ₃ ) ₄ NOH 0.3% by weight 8 2530 Experimental Example 11 Ceria 0.5 wt% (CH ₃ ) ₄ NOH 0.2% by weight 8 3064 Experimental Example 12 Ceria 0.5 wt% NH ₄ OH 0.2% by weight 6 2571

As shown in Table 2, the closer the ceria content was to 0.5% by weight, the higher the polishing rate and the higher the polishing rate when (CH ₃ ) ₄ NOH was used as the polishing accelerator. Comparative Example 2 did not significantly increase the polishing rate despite the ceria content of about 12 times by weight of about 20 times the other examples. On the other hand, when the content of ceria was 0.5% by weight and the content of (CH ₃ ) ₄ NOH was 0.2% by weight, the polishing rate was more than 3000 m 3 / min and showed excellent polishing rate. As a result, the polishing rate is not arithmetically proportional to the content of ceria, and it can be seen that a high polishing rate can be obtained by appropriate combination with a polishing accelerator.

Experimental Example 13

Ceria particles having a particle diameter of about 200 nm were mixed with deionized water to have a concentration of 0.5% by weight relative to the polishing liquid. Polyacrylic acid was then added as a dispersion stabilizer to 1.5% of the ceria particle weight and then dispersed. Subsequently, (CH ₃ ) ₄ NOH was added as a polishing accelerator to 0.5% by weight of the polishing liquid, that is, 1 times (100%) of the weight of ceria particles, and then stirred. The slurry composition was then adjusted such that the pH of the mixture was 8 by adding HCl as the pH adjusting agent while measuring the pH of the stirred mixture.

Experimental Example 14

A slurry composition was prepared in the same manner as Experimental Example 13 except that polyacrylic acid was added as 5.0 wt% of the weight of the ceria particles as the dispersion stabilizer.

Experimental Example 15

A slurry composition was prepared in the same manner as in Experimental Example 13 except that polyacrylic acid was added as 10.0% by weight of the ceria particles as the dispersion stabilizer.

Experimental Example 16

A slurry composition was prepared in the same manner as in Experimental Example 13 except that polyacrylic acid was added as 25.0 wt% of the weight of ceria particles as the dispersion stabilizer.

Stability over time of the slurry composition prepared by Experimental Example 13 to Experimental Example 16 was investigated. First, polishing was performed using each slurry composition immediately after preparation, and the polishing rate was measured. The remaining slurry composition was left for 15 days and 45 days, followed by polishing, and the polishing rate was measured. The measured polishing rates are shown in Table 3 in comparison with the polishing rates immediately after preparation.

Dispersion stabilizer content (compared to ceria particles) Polishing rate immediately after manufacture (after 15 days) Polishing rate immediately after manufacture (after 45 days) Experimental Example 13 1.5% 100% 100% Experimental Example 14 5.0% 100% 98% Experimental Example 15 10.0% 96% 92% Experimental Example 16 15.0% 87% 84%

As shown in Table 3, when the content of the dispersion stabilizer is 1.5% and 5.0% of the ceria particle weight, the initial polishing rate may be maintained until 45 days after manufacture. It is weak.

Although the embodiments of the present invention have been described with reference to the accompanying drawings and the experimental examples, the present invention is not limited to the above embodiments, but may be manufactured in various forms, and the general knowledge in the art to which the present invention pertains. Those skilled in the art can understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

As described above, the slurry composition according to the present invention can sufficiently maintain the polishing rate while reducing the content of the metal oxide, thereby reducing the polishing process cost and not causing the problem of environmental pollution.

Claims (12)

0.01 to 5% by weight of a metal oxide, a polishing accelerator having a weight ratio of 0.1 to 2.0 with respect to the metal oxide, a dispersion stabilizer having a weight ratio of 0.01 to 0.05 with respect to the metal oxide, and the rest of deionized water or a pH adjusting agent at least Slurry composition comprising one. The method of claim 1, The slurry composition of the metal oxide is 0.1 to 0.5% by weight based on the slurry composition. The method according to claim 1, And the metal oxide is ceria, silica, alumina, titania, zirconia, germania or mixtures thereof. The method of claim 3, Slurry composition wherein the metal oxide is ceria. The method according to claim 1, And the polishing promoter comprises at least one of ammonia, one or more quaternary amines, or salts thereof. 6. The method of claim 5, And the quaternary amine is (CH ₃ ) ₄ NOH, (C ₂ H ₅ ) ₄ NOH, or (C ₄ H ₉ ) ₄ NOH. 6. The method of claim 5, Slurry composition wherein said salt is chloride, bromide, carbonate, sulfate or nitrate. The method according to claim 1, The slurry composition as said dispersion stabilizer is polycarboxylic acid, polyacrylic acid, or salts thereof. The method according to claim 1, Slurry composition having a pH of 4 to 11 of the slurry composition. The method of claim 9, Slurry composition having a pH of 6 to 10 of the slurry composition. The method according to claim 1, Wherein the pH regulator is HCl, H ₂ SO ₄ , H ₃ PO ₄ or HNO ₃ . The method according to claim 1, And the slurry composition is for polishing an interlayer insulating film, for polishing an intermetallic insulating film, or for polishing an insulating film of metal.

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