KR20000055130A - Preparation method for metal oxide slurry with narrow distribution - Google Patents

Abstract

PURPOSE: A manufacturing method of metal oxide slurry for a chemical mechanical polishing (CMP) processing of a semiconductor element having uniform particle dispersion is provided to make the particle dispersion narrow and uniform by centrifuging fine-dispersed solution by a method of milling, hi-mixing or fluid collision to remarkably reduce the generating rate of micro-scratch. CONSTITUTION: Metal oxide slurry (4) in a solution state uniformly mixed with water in a predetermined concentration is flown into a dispersion device (5) through a transferring line. The transferred slurry is dispersed by a milling, hi-mixing or fluid collision method inside the dispersion device and flown into a centrifuge (6). The metal oxide slurry is centrifuged with predetermined rotating speed and rotating time in the centrifuge. Some extremely particulate-being metal oxide slurry (1) is discharged and is not used. However, the metal oxide slurry (2) for a chemical mechanical polishing (CMP) in a proper size is used but some metal oxide slurry of too large-sized particles for retrieving to the dispersion device is discharged again to the dispersion device.

Description

Manufacturing method of metal oxide slurry for semiconductor device CPM having uniform particle distribution {PREPARATION METHOD FOR METAL OXIDE SLURRY WITH NARROW DISTRIBUTION}

The present invention relates to a method for producing a metal oxide slurry used in the chemical mechanical polishing (CMP) process of the semiconductor device manufacturing process, and more specifically, milling, high mixing or fluid collision by mixing the metal oxide and water After microdispersion, the microdispersion was centrifuged to narrow and uniform the metal oxide particle distribution in the slurry and to completely remove the large metal oxide particle, thereby providing excellent dispersion stability and polishing rate, and significantly reducing the occurrence of μ-scratch. It relates to a method for producing a metal oxide slurry for semiconductor device CMP that can be reduced.

CMP process of semiconductor device manufacturing process is a kind of lithography that is used to manufacture semiconductor devices. As semiconductor devices have increasingly finer and higher density and multi-layered wiring structure, the planarization of insulating films and wirings of each layer is increased. Introduced, it can be said to be an essential process in the manufacture of semiconductors.

In general, the metal oxide slurry used in the CMP process has good dispersibility, excellent polishing speed, low defects such as μ-scratch on the wafer surface after softening, and high purity. Among them, the occurrence of μ-scratch has been attracting a lot of attention recently because it is directly related to the yield of wafers in the shallow trench isolation process.

All of these conditions, except high purity, are closely related to the size and distribution of the metal oxide particles, which are the main components of the slurry. That is, in terms of particle size, the smaller the particle size of the metal oxide, the better the dispersion stability and the better in terms of reducing the μ-scratch, but the polishing rate is lowered, there is a problem that the polishing productivity per unit time is lowered. In addition, it is preferable that the particle size distribution is uniformly narrow and uniformly distributed, because when the slurry having a wide particle size distribution is used, the flatness of the polishing surface is lowered and the occurrence of μ-scratch is not preferable. .

Therefore, for the CMP process, a slurry having an appropriate size and distribution is required in consideration of the above polishing rate, dispersion stability, μ-scratch, and the like. In addition, even if the particle distribution is narrow and uniformly distributed, if there is a small amount of macrometal oxide particles, there is a limit in reducing the occurrence of the micro-scratch, so it is preferable to completely remove the macrometal oxide.

As a known method for producing a metal oxide slurry for CMP, U.S. Patent No. 5,382,272 proposes a method of rapidly stirring with a Dynomill or a Ballmill after adding a beads. Contamination of the bead component on the dispersion mechanism due to the bead collision is inevitable, and there is a tailing (Tailing) phenomenon in the particle distribution also has a disadvantage that it is difficult to produce a uniform slurry with a narrow distribution range. In addition, as time goes by, the dispersion performance due to bead etching decreases, and thus the size and distribution deviation of the particles for each lot during production are severe, and thus reproducible polishing performance is not expected, and productivity is also lowered.

Alternatively, a method of rotating the fluid with a rotor of IKA, Germany, at high speed is known to cause collision and friction to the stator. This method is improved compared to the mixing method. The method also pointed out problems such as etching phenomenon due to wall collision of stator on dispersion mechanism and deterioration of dispersion performance over time.

In addition, since both methods are known to have a particle size of about 1 μm, they are not suitable for preparing ultrafine metal oxide slurry required in a CMP process. It cannot be used as a CMP slurry for the shallow trench isolation process, which causes fatal results in terms of function and yield.

In addition, there was an offset collision method (US Pat. Nos. 4,533,254, 5,360,089) or an opposite collision method in the dispersion chamber previously invented by the inventors of the present invention (Korean Patent Application No. 98-39212). It is not easy and due to the etching of the orifice during a long time manufacturing, it is not possible to avoid the contamination of the metal component with the dispersion force decreases. In this respect, there is a need for a method of preparing a metal oxide slurry that lowers the pressure of the fluid to reduce the orifice etch so that it can be stably used in the CMP process. In addition, since the existing methods contain macroparticles even in a small amount in the slurry, there is a problem that the micro-scratch is not caused so much that the yield is lowered in the CMP process and the subsequent STI process. Was being asked.

An object of the present invention is to solve the conventional problems as described above, to make the metal oxide particle distribution in the aqueous solution narrow and uniform up to 500nm or less and to remove the huge metal oxide particles, generally required in the CMP process In addition to the speed and dispersion stability, in particular, it is to provide a method for producing a metal oxide slurry for semiconductor device CMP that can improve the flatness of the wafer and significantly reduce the incidence of µ-scratch.

This object of the present invention can be achieved by mixing the metal oxide and water to finely disperse by milling, Hi-Mixing or fluid collision method, and then centrifuging the microdispersion.

1 is a conceptual diagram of centrifugation according to the present invention;

2 is a schematic view of a metal slurry production apparatus according to the present invention.

Explanation of symbols for the main parts of the drawings

1: overly atomized metal oxide slurry

2: metal oxide slurry for CMP

3: metal oxide slurry for dispersing device recovery

4: metal oxide in aqueous solution

5: Disperser

6: centrifuge

That is, the present invention is a step 1 to disperse 5 to 50% by weight of metal oxide in 50 to 95% by weight of water by milling, Hi-Mixing or fluid collision method and the dispersed metal oxide slurry It relates to a method for producing a metal oxide slurry for a semiconductor device CMP, characterized in that consisting of two steps of centrifugation at a rotation speed of 1500 RPM to 4500 RPM, rotation time 5 minutes to 15 minutes.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Figure 2 is a schematic diagram of a process for producing a cargo slurry of the present invention, looking at the overall flow first, the dispersion device through the metal oxide (metal oxide slurry) 4 in the aqueous solution uniformly mixed with water at a certain concentration through a transfer line Inflow to (5). The slurry thus transferred is dispersed in a dispersing apparatus by milling, high mixing or fluid collision, and the finely dispersed metal oxide slurry is introduced into the centrifuge 6. In this centrifuge, the metal oxide slurry is centrifuged at a constant rotation speed and rotation time so that the excessively atomized metal oxide slurry (1) is not discharged and used, and the metal oxide slurry (2) for CMP of suitable size is used. The metal oxide slurry 3 for dispersing the dispersing device with excessively large particles is discharged back to the dispersing device.

In general, the metal oxide has a difference in dispersibility depending on the surface area, the larger the surface area, the better the dispersion under the same pressure, the metal oxide can be used in the present invention surface area prepared by oxidizing at a high temperature of 1000 ℃ or more Any one of 20 to 300 m 2 / g range is possible, and more preferably from the group consisting of SiO ₂ , CeO ₂ , ZrO ₂ can be used in one or two or more mixed forms, one of which is used alone It is suitable.

In the premixing tank, the metal oxide slurry is prepared in a high concentration in the premixing tank such that the metal oxide is in the range of 1 to 50% by weight, preferably 5 to 50% by weight, and the concentration of the solids in the premixed slurry is If it is less than 1% by weight, the dispersion effect desired in the present invention cannot be obtained, and if it exceeds 50% by weight, the viscosity increases rapidly due to thixotropy, which is undesirable. In the actual CMP process, the premixed slurry is diluted and used. For example, the solid concentration of the diluted metal oxide slurry used in the CMP process using the metal oxide used in the present invention is 10 to 25% by weight SiO ₂ slurry, 1 to 5% by weight CeO ₂ slurry, ZrO ₂ slurry The mixing is preferably 4 to 8% by weight in terms of polishing performance and raw material cost reduction.

In the present invention, since a conventional dispersion method is used as the method for dispersing the metal oxide, both a milling method, a hi-mixing method, or a fluid collision method can be used. Milling method (US Pat. No. 5,382,272) is a method of high speed stirring with Dynomill or Ballmill after adding beads, and the high mixing method is a stator by rotating the fluid at high speed with a rotor. This is a method of causing collision and friction to the stator. In these two methods, in order to be suitable for CMP slurry, dispersion time should be increased or rotation speed should be increased and dispersion stabilizer should be used to disperse. The use of a stabilizer or the like makes the CMP slurry unsuitable for high purity. Therefore, the dispersion by the fluid collision method is preferable, and the fluid collision method is an offset collision method (US Pat. Nos. 4,533,254, 5,380,089), or the present inventors' counter-impact method (Korean Patent Application No. 98-39212). In the present invention, the dispersion using the opposite collision method will be described as an example.

Dispersion conditions for making a metal oxide slurry suitable for CMP generally without centrifugation, and dispersion conditions when using centrifugation are shown in Table 1 below.

Oppositional conflict condition Metal oxide pressure Solid Concentration (%) pH Particle Distribution (nm) Average particle (nm) When using a centrifuge SiO ₂ 400 12.5 11 30 to 560 220 When not using centrifuge SiO ₂ 800 12.5 11 30 to 450 190

As shown in Table 1, when centrifugation is used, the pressure of the fluid during the dispersion may be lowered, so that the life of the orifice due to etching is generally increased from 3 months to 4 months, and the etching rate is reduced, so that a stable slurry is more stable for a long time. You can get it.

In the present invention, a method of connecting the dispersing device and the centrifugal separator is used to control the removal of the large particles of the metal oxide particles and the particle distribution. In the present invention, the precipitation rate of the metal oxide particles during centrifugation is affected by the rotation speed and the rotation time. That is, if the rotational speed of the centrifugal separator is too fast or the rotation time is too long, phase separation with the dispersion solvent occurs due to the aggregation between the metal oxide particles, and thus its use is impossible, and if the rotation speed is slow or the rotation time is short, No effect at all. In order to obtain the optimum slurry for CMP using the effect of centrifugation, the conditions should be as follows. (Iii) In order to remove large particles, the centrifuge may be rotated at 2800 RPM to 4500 RPM for 10 minutes to 15 minutes, and more preferably at 3000 RPM to 3500 RPM for 12 minutes. (Ii) The conditions for controlling the distribution of the metal oxide particles are preferably 5 to 15 minutes at 2000 RPM to 3000 RPM, and more preferably 8 to 13 minutes at 2500 RPM to 3000 RPM. The metal oxide slurry centrifuged in this manner is distributed as shown in FIG. 1 and removes 10% (1) of the surface layer solution and 10% (3) of the bottom layer, and only 80% (2) of the middle layer is used as the slurry for CMP. . 2 shows a conceptual diagram of this centrifugation.

By appropriately adjusting the rotation speed of the centrifuge within the above conditions, the size of the obtained metal oxide particles can be adjusted. Faster rotation speeds reduce the overall particle size, narrow the width of the particle distribution, and slow the rotation speed. This results in a larger particle size and a wider particle distribution. Therefore, the present invention has the advantage that it is possible to obtain particles of various sizes and distribution simply by the rotational speed of the centrifuge.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Example 1

Aerosil 200 of commercially available silica (manufactured by Degussa Co., Ltd.): 500 g of surface area 200 m / g), 50 g of 20% -KOH solution, 3550 g of deionized water were mixed in a Teflon-coated premixing tank with a capacity of 1 m 3 Through the transfer pump (Diaphram 1-50 atm) and the high pressure pump (Intensifier pump 50-1500 atm), the inlet diameter is 0.4mm, the outlet diameter is 0.2mm, and is transferred to the dispersion chamber equipped with two ceramic orifices. It was made to oppose and disperse. The slurry from the dispersion chamber was centrifuged at 1700 RPM for 7 minutes using a Teflon material centrifuge with a capacity of 100 ml or more, and the sample of the obtained slurry was measured using a particle size analyzer (Zetasizer, Malvern). The size was measured and shown in Table 2.

Examples 2 to 3

Except that the rotation time of the centrifuge was changed as shown in Table 1 was carried out in the same manner as in Example 1 and the results are shown in Table 2.

Examples 4-18

Except that the rotational speed and rotation time of the centrifuge was changed as shown in Table 1, and was carried out in the same manner as in Example 1 and the results are shown in Table 2.

Example 19

The same procedure as in Example 5 was carried out except that ceria (CeO ₂ : surface area of 30 m ₂ / g) was used instead of silica of Example 1 and the amount thereof was 90 g, and the results are shown in Table 2.

Example 20

The same procedure as in Example 14 was carried out except that ceria (CeO ₂ : surface area 30 m ₂ / g) was used instead of silica of Example 1 and the amount thereof was 90 g, and the results are shown in Table 2.

Examples 21-22

Zirconia (ZrO ₂ : surface area 30 m ₂ / g) was used in place of the silica of Example 1, except that 90 g of the amount thereof was used, and the results are shown in Table 2, respectively.

Metal oxide Centrifuge Particle Distribution (nm) Average particle (nm) Rotational Speed (RPM) Rotation time (min) Example 1 SiO ₂ 1700 7 30 to 500 190 Example 2 SiO ₂ 1700 9 35 to 470 190 Example 3 SiO ₂ 1700 12 40-450 180 Example 4 SiO ₂ 2500 7 45-460 190 Example 5 SiO ₂ 2500 9 50 to 440 180 Example 6 SiO ₂ 2500 12 40-430 170 Example 7 SiO ₂ 2900 7 45-460 180 Example 8 SiO ₂ 2900 9 40-450 175 Example 9 SiO ₂ 2900 12 35 to 400 170 Example 10 SiO ₂ 3100 11 30 to 440 160 Example 11 SiO ₂ 3100 12 30 to 410 150 Example 12 SiO ₂ 3100 14 25-400 150 Example 13 SiO ₂ 3300 11 30-420 160 Example 14 SiO ₂ 3300 12 30 to 400 160 Example 15 SiO ₂ 3300 14 25-400 155 Example 16 SiO ₂ 4000 11 25-400 155 Example 17 SiO ₂ 4000 12 25-390 150 Example 18 SiO ₂ 4000 14 20-370 140 Example 19 CeO ₂ 2500 9 50-520 220 Example 20 CeO ₂ 3300 12 30 to 480 200 Example 21 ZrO ₂ 2500 9 50 to 490 200 Example 22 ZrO ₂ 3300 12 30 to 470 180

Comparative Example 1

500 g of commercially available silica (SiO ₂ : 200 m2 / g), 50 g of 20% -KOH solution, 3550 g of deionized water were mixed in a premixed tank having a capacity of 1 m 3 and coated with a Teflon-coated tank (Diaphram 1-50 atm) and a high pressure. The inlet diameter was 0.4mm, the outlet diameter was 0.2mm, and was transferred to a dispersion chamber in which two ceramic orifices were installed through a pump (Intensifier pump 50-1500 atm), and was dispersed by opposing collision at 400 atm. Samples of the slurry that passed through the dispersion chamber were measured using a particle size analyzer (Zetasizer, Malvern) to measure particle size, distribution and average particle size, and are shown in Table 3.

Comparative Example 2

Ceria (CeO ₂ : 30 m ₂ / g) was used instead of silica in Comparative Example 1, except that 90 g of the amount thereof was used.

Comparative Example 3

Except for using zirconia (ZrO ₂ : 30 m ₂ / g) instead of silica in Comparative Example 1 and 90g of the amount was carried out in the same manner as in Comparative Example 1 and the results are shown in Table 3.

Metal oxide Pressure (atm) Particle Distribution (nm) Average size (nm) Comparative Example 1 SiO ₂ 400 30 to 560 220 Comparative Example 2 CeO ₂ 400 30 to 700 260 Comparative Example 3 ZrO ₂ 400 30-650 250

The polishing performance was also tested with the prepared slurry. The polishing machine used 6EC (STRABAUGH), and the wafer used 6-inch bare wafer coated with P-TEOS. The pad type was IC1000 / Subal VStacked (Rodel), and both the platen speed and the wafer speed were 120 rpm. In addition, the polishing rate was measured from the thickness change removed by polishing after 2 minutes polishing for each slurry under pressure and back pressure of 6psi, 0psi, temperature of 25 ℃, slurry flow rate of 150ml / min. Μ-scratch was measured using a KLA (TENCOR company) instrument. The results of this polishing performance test are shown in Table 4 below.

Manufacturing method Particle Size Distribution / Average Size (nm) Polishing performance test result Polishing Speed (Å / min) μ-scratch % Flatness Example 5 50-440/180 3500 8 3 Example 14 30-400/160 3400 One 7 Example 19 50-520/220 7000 13 3 Example 20 30-480/200 7000 2 7 Example 21 50-490/200 6500 10 3 Example 22 30-470/180 6300 2 7 Comparative Example 1 30-560/220 3700 50 15 Comparative Example 2 30-700/260 7000 70 16 Comparative Example 3 30-650/250 6600 60 15

As described above, according to the present invention, by reducing the etching of the dispersing apparatus, the dispersion can be stabilized for a long time, and the flatness can be improved by uniformly adjusting the metal oxide particle distribution, and particularly, the huge metal oxide particles are completely removed. Since the metal oxide slurry can be manufactured in various sizes and distributions, the metal oxide slurry can be prepared in the form of shallow trench isolation, interlayer semiconductor devices having a multi-layered metal interconnection structure. The insulating layer (Inter Layer Dielectric), Inter Metal Dielectric (Inter Metal Dielectric), etc. can be usefully used when planarizing the CMP process.

Claims (3)

In preparing a metal oxide slurry for a semiconductor device CMP, a step of dispersing 5 to 50% by weight of the metal oxide in 50 to 95% by weight of water by milling, Hi-Mixing or fluid collision method and Wherein the dispersed metal oxide slurry is centrifuged at a rotational speed of 2000 RPM to 4500 RPM and a rotation time of 5 minutes to 15 minutes. The method of claim 1, wherein the metal oxide is at least one selected from the group consisting of silica (SiO ₂ ), ceria (CeO ₂ ), and zirconia (ZrO ₂ ). . The method of claim 1, wherein the particle size distribution of the centrifuged slurry is 30 to 500nm.