KR20100124988A - Method of preparing ceria powder and slurry composite using the same - Google Patents

Abstract

PURPOSE: A manufacturing method for ceria and a slurry composition using thereof are provided to improve the polishing speed and the polishing selectivity of the composition using a rapid heating and rapid cooling process. CONSTITUTION: A manufacturing method for ceria comprises a step of calcining a cerium compound in 700~1,000 deg C. The manufacturing method comprises a step of rapidly heating the cerium compound for 700~1,000 deg C, and a step of rapidly cooling the cerium compound to 15~30 deg C. The calcining time is 10 minutes~2 hours. The heating speed for the rapidly heating process is 20~900 deg C/min.

Description

Method for preparing cerium oxide and slurry composition using same {Method of preparing ceria powder and slurry composite using the same}

The present invention relates to a method of producing cerium oxide and a slurry composition using the same, and more particularly, to a method of manufacturing cerium oxide having high polishing rate and polishing selectivity and capable of reducing fine scratches in a chemical mechanical polishing process, and using the same It relates to a slurry composition.

Recently, as the degree of integration of semiconductor devices increases, a wide area flattening process is required to secure a margin for a high-performance exposure process. Chemical Mechanical Polishing (CMP) is a process used for wide-area leveling of such semiconductor devices. The chemical mechanical polishing (CMP) has excellent flattening capability and simple process compared to other planarization methods.

The polishing slurry used in the chemical mechanical polishing process generally includes abrasive particles, deionized water, and additives. Colloidal silica particles or fumed silica particles are mainly used as the abrasive particles. Is not high enough, and the polishing selectivity of the oxide film and the nitride film is low, and thus, there is a problem in that various steps of the process must be further performed.

In order to supplement the above problem, the use of a slurry containing cerium oxide particles used in the existing glass processing process is contemplated. However, although cerium oxide particles have the advantage of high polishing speed and high polishing selectivity of oxide and nitride films, the specific gravity is 6 to 8 times higher than that of silica particles, resulting in poor dispersion stability during slurry production. There is a problem that a large amount of fine scratches occur. Particularly, during the chemical mechanical polishing process, the shallow trench isolation (STI) CMP process has serious consequences in terms of performance and production yield of semiconductor devices when the trench is thin and fine scratches are generated. Most of these fine scratches are known to be due to the shape and size of the abrasive particles.

As a prior art for preparing a cerium oxide slurry, Hitachi Korea Patent 10-2007-0087037 discloses a method for synthesizing cerium oxide particles. The patent describes the properties of the particles and the types of additives required for the slurry properties for STI CMP. Korean Patent No. 10-2007-0087840 of KC Tech Co., Ltd. discloses a method for reducing fine scratches through a aging process after preparing a slurry. Hitachi Korea Patent 10-2001-7014923 discloses a method for synthesizing cerium oxide particles with a change in heating rate. However, these manufacturing methods still suffer from the problem of inadequate access to cerium oxide abrasive particles, which can cause numerous scratches.

Accordingly, it is an object of the present invention to provide a cerium oxide production method and slurry composition using the same, which have a high polishing rate and polishing selectivity and can reduce fine scratches in a chemical mechanical polishing process.

Another object of the present invention is to provide a cerium oxide manufacturing method suitable for a shallow trench isolation (STI) chemical mechanical polishing process and a slurry composition using the same.

In order to achieve the above object, the present invention, the method for producing a cerium oxide by calcining the cerium compound at 700 to 1,000 ℃, the step of rapidly heating the cerium compound to 700 to 1,000 ℃; And rapidly cooling the calcined cerium compound to 15 to 30 ° C.

Here, the calcination time is 10 minutes to 2 hours, the heating rate of the rapid heating step is 20 to 900 ℃ / minute, the cooling rate of the quenching step is preferably 20 to 400 ℃ / minute.

In addition, the present invention is 0.1 to 10% by weight of the cerium oxide relative to the total slurry composition; With respect to 100 parts by weight of the cerium oxide, a cerium oxide slurry composition comprising 2 to 20 parts by weight of dispersant and the remaining deionized water is provided.

Cerium oxide production method according to the invention, in the process of calcining the cerium compound, by forming a fine crack on the surface of the cerium oxide (polishing particles) through a rapid heating and quenching process, the prepared abrasive particles are non-uniform surface The particles have a low density, which is easily broken by external impact. Therefore, the abrasive particles can be easily broken by external pressure during wafer polishing, thereby significantly reducing the fine scratches on the surface to be polished, and since the broken abrasive particles proceed to polishing again, they have high polishing speed and polishing selectivity. Therefore, it is useful for Shallow Trench Isolation (STI) chemical mechanical polishing process which is sensitive to minute scratches.

Hereinafter, the present invention will be described in detail.

Cerium oxide production method of the present invention, in the method for producing cerium oxide by calcining the cerium compound at 700 to 1,000 ℃ step, the step of calcining the cerium compound to 700 to 1,000 ℃ preferably 750 to 950 ℃ and calcining Quenching the cerium compound to 15 to 30 ° C., preferably to 18 to 28 ° C.

The calcining is an operation of heating a substance to a high temperature to remove some or all of its volatile components, and in the present invention, it means that the cerium compound is formed of cerium oxide (polishing particles). For example, carbon dioxide (CO ₂ ), water (H ₂ O), and the like are removed from cerium carbonate (Ce ₂ (CO ₃ ) ₃ · 6H ₂ O) to form a cerium oxide (2CeO ₂ ) crystal. The calcining temperature may vary depending on the material, and is usually 700 to 1,000 ° C.

The calcining time of the cerium compound is 10 minutes to 2 hours, preferably 15 to 90 minutes. If the calcining time is less than 10 minutes, the cerium compound may be incompletely calcined to form cerium oxide, and if it is more than 2 hours, the strength of the cerium oxide particles may increase, which may cause scratches during polishing. It is economical.

If the temperature of the rapid heating step is out of the range, there is a fear that cerium oxide formation is difficult because the calcination of the cerium compound is incomplete, the surface of the cerium oxide produced when the temperature of the quenching step is out of the range. There is a possibility that a minute crack cannot be formed.

The heating rate of the rapid heating step is 20 to 900 ℃ / min, preferably, 50 to 500 ℃ / minute, the cooling rate of the quenching step is 20 to 400 ℃ / minute, preferably, 20 to 100 ℃ / Minutes. If the heating rate of the rapid heating step is out of the range, cerium oxide may be difficult to form or there may be a possibility of not forming a fine crack on the surface of the cerium oxide to be produced, and the cooling rate of the quenching step may be out of the range. In this case, fine cracks may not be formed on the surface of the cerium oxide to be produced.

In addition, the cerium oxide manufacturing method, the surface of the prepared abrasive particles are nonuniform and low density, so that the rapid heating and quenching step is performed at least once, preferably 2 To repeat three times.

The cerium compound used in the present invention may be a cerium compound used for the production of a conventional cerium oxide, preferably cerium carbonate, cerium hydroxide, cerium sulfate, cerium oxalate and mixtures thereof, more preferably cerium carbonate. have.

In the X-ray diffraction graph, the cerium oxide produced by the above production method has a main peak having a 2θ value of 27 to 30 ° and a minor peak of 30 to 35 °, and an area intensity ratio between the main peak and the sub peak (main peak) / Negative peak) is 3.0 or more. The average crystal size obtained by substituting the full width at half maximum (FWHM) of the cerium oxide powder by the X-ray diffraction method into the Scherrer Equation is 20 to 50 nm, preferably 25 to 45 nm. to be. When the crystal (particle) size of the cerium oxide powder is less than 20 nm, the polishing rate and polishing selectivity may be reduced during chemical mechanical polishing, and when the crystal size exceeds 50 nm, there is a concern that fine scratches may occur during chemical mechanical polishing. have.

The cerium oxide slurry composition according to the present invention is suitable for the chemical mechanical polishing (CMP) process, especially for the STI CMP process, in which the performance and production yield of semiconductor devices are greatly reduced even in fine scratches. To 10% by weight, preferably 0.5 to 5% by weight, based on 100 parts by weight of the cerium oxide, 2 to 20 parts by weight of dispersant, preferably 3 to 15 parts by weight and the remaining deionized water (pure water).

If the cerium oxide is less than 0.1% by weight, the cerium oxide may not fully function as the abrasive particles, the polishing rate, polishing selectivity, etc. may be degraded, and the dispersion efficiency may be reduced. There is a fear that layer separation of the slurry composition may occur due to the aggregation of, and there is no particular advantage as there is a fear that fine scratches are further generated during polishing.

The dispersant used in the present invention is used to enhance the dispersing effect, and may be used a conventional dispersant such as carboxylic acid or salt thereof used in a conventional chemical mechanical polishing slurry composition, and preferably polycarboxyl. Acids or salts thereof, more preferably polyacrylic acid or salts thereof (such as ammonium polyacrylate salts) can be used. Specific examples of the carboxylic acid include glutaric acid, glutamic acid, glycolic acid, glycolic acid, lauric acid, lactic acid, malic acid, Malonic acid, valeric acid, citric acid, stearic acid, succinic acid, acetic acid, oxalic acid, adipic acid acid, capric acid, caproic acid, caproic acid, caprylic acid, formic acid, fumaric acid, phthalic acid, propionic acid, Pyruvic acid (tarruric acid), tartaric acid (tartaric acid), polyacrylic acid (polyacrylic acid) and salts thereof and mixtures thereof may be exemplified. As the salt of the carboxylic acid, conventional carboxylic acid salts such as sodium salt, ammonium salt, and potassium salt may be used. The said carboxylic acid or its salt can be used individually or in combination of 2 or more types.

When the dispersant is a polycarboxylic acid, the average molecular weight of the dispersant is 5000 to 20000, preferably 10000 to 15000, if the average molecular weight of the dispersant is less than 5000, the dispersibility may be lowered, even if it exceeds 20000 There is a fear that the dispersibility is lowered.

When the dispersant is less than 2 parts by weight with respect to 100 parts by weight of the cerium oxide, the cerium oxide in the slurry composition may not be sufficiently dispersed and may be entangled or aggregated. If the amount is more than 20 parts by weight, the dispersant may act as an impurity. There is no advantage.

The cerium oxide slurry composition is preferably used to disperse the cerium oxide in deionized water, in order to prevent particle agglomeration of the prepared slurry, the dispersion device may use a conventional stirrer and a disperser, Specific examples may include a shaker, homogenizer, paint shaker, ultrasonic disperser, bead mill, roll mill, apex mill, vibrating ball mill, and a dispersing apparatus using them. In the case of using a bead mill, conventional beads can be used as the dispersion medium, and zirconia beads, alumina beads, glass beads, and the like can be exemplified as representative examples.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples are intended to illustrate the invention, and the invention is not limited by the following examples.

Example 1 Preparation of Cerium Oxide

After preparing a tube furnace heated to 700 ° C. (calcination temperature), 30 g of room temperature (15 to 30 ° C. cerium carbonate powder) was placed in a platinum container and slowly pushed into the tube (heated portion). The rate of loading was adjusted to adjust the heating rate to 100 ° C./min.The cerium carbonate powder was heated to a calcination temperature (700 ° C.), calcined for 1 hour, and then the platinum container was taken out to prepare a desiccator. It was cooled to room temperature (cooling rate 50 ° C./min) to obtain a yellow powder, which was controlled by controlling the temperature of the cooling water flowing around the desiccator. As a result, it was confirmed that the cerium oxide, and the result of substituting the full width at half maximum (FWHM) of the cerium oxide powder by the X-ray diffraction method into the Scherrer Equation, the average It was confirmed that the tablet size of about 28nm. Furthermore, given in TEM (transmission electron microscopy) picture 1 the degree of the cerium oxide powder.

Examples 2 to 4 Preparation of Cerium Oxide

A yellow powder was prepared in the same manner as in Example 1, except that the calcination temperature was changed to 800 ° C. (Example 2), 900 ° C. (Example 3), and 1000 ° C. (Example 4) instead of 700 ° C. It was. As a result of analyzing the powder by X-ray diffraction, it was confirmed that it was cerium oxide, and the average crystal size of each cerium oxide was measured in the same manner as in Example 1, and the results are shown in Table 1 below. In addition, TEM images of each cerium oxide powder are shown in FIGS. 2 to 4.

Examples 5 to 8 Preparation of Cerium Oxide

Change the calcining temperature to 900 ° C. instead of 700 ° C., and change the heating rate to 20 ° C./min instead of 100 ° C./min (Example 5), 50 ° C./min (Example 6) 450 ° C./min (Example 7) and 900 A yellow powder was prepared in the same manner as in Example 1, except that it was changed to ° C / min (Example 8). As a result of analyzing the powder by X-ray diffraction, it was confirmed that it was cerium oxide, and the average crystal size of each cerium oxide was measured in the same manner as in Example 1, and is shown in Table 1 below. In addition, TEM images of each cerium oxide powder are shown in FIGS. 5 to 8.

Examples 9 to 11 Preparation of Cerium Oxide

Change the calcination temperature to 900 ° C. instead of 700 ° C., heating rate to 450 ° C./min instead of 100 ° C./min, and cooling rate 20 ° C./min instead of 50 ° C./min (Example 9), 100 ° C./min (implementation A yellow powder was prepared in the same manner as in Example 1, except that Example 10) and 200 ° C / min (Example 11) were changed. As a result of analyzing the powder by X-ray diffraction, it was confirmed that it was cerium oxide, and the average crystal size of each cerium oxide was measured in the same manner as in Example 1, and the results are shown in Table 1 below. In addition, TEM images of each cerium oxide powder are shown in FIGS. 9 to 11.

Example 12 Preparation of Cerium Oxide

Except for changing the calcination temperature to 900 ° C instead of 700 ° C, the heating rate to 450 ° C / minute instead of 100 ° C / min, the calcination time to 30 minutes instead of 1 hour, and repeating the heating and cooling steps one more time. To prepare a yellow powder in the same manner as in Example 1. As a result of analyzing the powder by X-ray diffraction, it was confirmed that it is cerium oxide, and the average crystal size of cerium oxide was measured in the same manner as in Example 1, and is shown in Table 1 below. In addition, a TEM photograph of each cerium oxide powder is shown in FIG. 12.

Example 13 Preparation of Cerium Oxide

A yellow powder was prepared in the same manner as in Example 12, except that the calcination time was changed to 20 minutes instead of 30 minutes, and the heating and cooling steps were repeated two more times. As a result of analyzing the powder by X-ray diffraction, it was confirmed that it is cerium oxide, and the average crystal size of cerium oxide was measured in the same manner as in Example 1, and is shown in Table 1 below. In addition, a TEM photograph of each cerium oxide powder is shown in FIG. 13.

Example 14 Preparation of Cerium Oxide

A yellow powder was prepared in the same manner as in Example 12, except that the calcination time was changed to 15 minutes instead of 30 minutes, and the heating and cooling steps were repeated three more times. As a result of analyzing the powder by X-ray diffraction, it was confirmed that it is cerium oxide, and the average crystal size of cerium oxide was measured in the same manner as in Example 1, and is shown in Table 1 below. In addition, a TEM photograph of each cerium oxide powder is shown in FIG. 14.

Comparative Example 1 Preparation of Cerium Oxide

30 g of cerium carbonate was placed in a platinum container, heated to 900 ° C. at a heating rate of 10 ° C./min using a tube furnace, calcined for 1 hour while heated to 900 ° C., and then cooled at 10 ° C. in a tube furnace. After cooling to room temperature in minutes, a yellow powder was obtained. As a result of analyzing the powder by X-ray diffraction, it was confirmed that it is cerium oxide, and the average crystal size of cerium oxide was measured in the same manner as in Example 1, and is shown in Table 1 below. In addition, a transmission electron microscopy (TEM) photograph of each cerium oxide powder is shown in FIG. 17.

Examples 15 to 28 and Comparative Example 2 Preparation and Evaluation of Cerium Oxide Slurry Composition

Preparation of Cerium Oxide Slurry Composition

1.5 kg of deionized water (pure water) and 1.05 g of ammonium polyacrylic acid salt solution were gradually added to the premixing vessel, followed by mixing. Then, 15 g of cerium oxide prepared in Examples 1 to 14 and Comparative Example 1 was added thereto, and zirconia beads were added. Dispersed for 30 minutes in a bead mill to obtain a cerium oxide slurry composition (Examples 15-28 and Comparative Example 2).

Evaluation of Cerium Oxide Slurry Composition

Using each of the prepared slurry compositions, a 8-inch diameter blanket silicon wafer having a 1.0 μm silicon oxide film layer produced by TEOS (Tetra Ethyl Ortho Silicate) -plasma CVD method and a silicon nitride film layer produced by low pressure CVD method were used. The 8-inch diameter blanket silicon wafers were polished using the AVANTI 472 equipment from IPEC. Polishing conditions were polished for 1 minute at a slurry flow rate of 150 cc / min at a falling pressure of 4 psi, a table speed of 60 rpm, and a head speed of 50 rpm. After the completion of the polishing, the resultant was washed with deionized water (pure water) and dried, and the amount of silicon oxide film and silicon nitride film remaining on the wafer was measured by an optical interferometer to measure the polishing rate of the oxide film and the nitride film. The number of scratches was measured using Negev's inspection equipment, and the number of scratches in the 8-inch wafer was 0.3-2.5 μm. The results are shown in Table 1.

Cerium oxide Cerium Oxide Manufacturing Conditions Evaluation results heating
speed
(℃ /
minute) calcination
Temperature
(℃) calcination
time
(minute) Cooling
speed
(℃ /
minute) Etc Average
decision
size
(nm) Oxide film
grinding
speed
(Å / min) Nitride film
grinding
speed
(Å / min) scratch
Count Example 15 Example 1 100 700 60 50 28 2845 57 54 Example 16 Example 2 800 30 3194 72 61 Example 17 Example 3 900 36 3318 81 63 Example 18 Example 4 1000 42 3452 102 72 Example 19 Example 5 20 900 36 3128 74 65 Example 20 Example 6 50 35 3217 65 67 Example 21 Example 7 450 31 3026 57 48 Example 22 Example 8 900 29 2766 51 71 Example 23 Example 9 450 20 31 3157 81 66 Example 24 Example 10 100 38 3311 48 52 Example 25 Example 11 200 39 2631 50 75 Example 26 Example 12 30 50 Repeat 35 3411 55 45 Example 27 Example 13 20 2 repetitions 34 3215 53 37 Example 28 Example 14 15 3 repetitions 33 3029 49 36 Comparative Example 2 Comparative Example 1 10 60 10 44 2455 107 176

From the above results, the slurry composition containing the cerium oxide (Examples 1 to 14) of the present invention is faster than the slurry composition containing the cerium oxide (Comparative Example 1) prepared through a conventional calcination process, the oxide film removal rate is faster and the nitride film Since the difference from the removal rate is large, it can be seen that the polishing rate and the polishing selectivity are excellent, and it can be seen from FIGS. 1 to 14 that the lattice patterns are not uniformly arranged in various directions and appear faint. This is because the surface of the cerium oxide is unevenly formed by giving a fine crack to the surface of the cerium oxide by controlling the heating rate and the cooling rate. As a result, the cerium oxide, which is the abrasive grain, is easily broken by external pressure during the polishing process, thereby significantly reducing fine scratches on the surface to be polished. Will have. Due to these characteristics, it can be seen that the cerium oxide particles according to the present invention are also useful for the Shallow Trench Isolation (STI) chemical mechanical polishing process which is sensitive to minute scratches.

In addition, from the evaluation results of the cerium oxide slurry compositions of Examples 21 (Example 7) and Examples 26 to 28 (Examples 12 to 14), when the cerium oxide was produced, the oxide film polishing rate was repeated if the heating and cooling processes were repeated one or more times. It can be seen that the increase in the nitride film polishing rate and the number of scratches decreases. Comparing FIGS. 7 and 12 to 14, it can be seen that the lattice pattern of the abrasive grains is more uniformly formed in FIGS. 12 to 14 than in FIG. 7. This is because the fine cracks on the surface of the abrasive grains are increased through the rapid heating and quenching steps during the production of the abrasive grains.

1 is a TEM photograph of a cerium oxide powder prepared by the method of Example 1. FIG.

2 is a TEM photograph of a cerium oxide powder prepared by the method of Example 2. FIG.

3 is a TEM photograph of a cerium oxide powder prepared by the method of Example 3. FIG.

4 is a TEM photograph of a cerium oxide powder prepared by the method of Example 4. FIG.

5 is a TEM photograph of a cerium oxide powder prepared by the method of Example 5. FIG.

6 is a TEM photograph of a cerium oxide powder prepared by the method of Example 6. FIG.

7 is a TEM photograph of a cerium oxide powder prepared by the method of Example 7. FIG.

8 is a TEM photograph of a cerium oxide powder prepared by the method of Example 8. FIG.

9 is a TEM photograph of a cerium oxide powder prepared by the method of Example 9. FIG.

10 is a TEM photograph of a cerium oxide powder prepared by the method of Example 10.

11 is a TEM photograph of a cerium oxide powder prepared by the method of Example 11. FIG.

12 is a TEM photograph of a cerium oxide powder prepared by the method of Example 12.

13 is a TEM photograph of a cerium oxide powder prepared by the method of Example 13. FIG.

14 is a TEM photograph of a cerium oxide powder prepared by the method of Example 14. FIG.

15 is a TEM photograph of a cerium oxide powder prepared by a method of Comparative Example 1. FIG.

Claims (5)

A method of producing cerium oxide by calcining a cerium compound at 700 to 1,000 ° C., comprising: rapidly heating the cerium compound to 700 to 1,000 ° C .; And A method of producing cerium oxide, comprising rapidly cooling a calcined cerium compound to 15 to 30 ° C. The oxidation according to claim 1, wherein the calcining time is 10 minutes to 2 hours, the heating rate of the rapid heating step is 20 to 900 ° C / minute, and the cooling rate of the quenching step is 20 to 400 ° C / minute. CE manufacturing method. The method of claim 1, wherein the cerium oxide manufacturing method comprises the rapid heating and quenching steps being repeated one or more times. The method of claim 1, wherein the cerium compound is selected from the group consisting of cerium carbonate, cerium hydroxide, cerium sulfate, cerium oxalate, and mixtures thereof. Cerium oxide, based on the total slurry composition, from 0.1 to 10% by weight; 2 to 20 parts by weight of a dispersant based on 100 parts by weight of the cerium oxide; And Containing the remaining deionized water, The cerium oxide may be calcined at 700 to 1,000 ° C. to produce cerium oxide, the method comprising: rapidly heating the cerium compound to 700 to 1,000 ° C .; And a cerium oxide slurry composition prepared by a method of preparing a cerium oxide, the method including quenching the calcined cerium compound to 15 to 30 ° C.

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