KR100460312B1 - Slurry composition for chemical mechanical polishing of metal lines - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing slurry used in a chemical mechanical polishing / planarization (CMP) process for the purpose of planarizing wafers in the manufacture of semiconductor devices. More specifically, the present invention relates to fine metal oxide powders, iodine compounds, hydrogen peroxide, The present invention relates to a slurry for polishing metal wires comprising a phosphorus-based compound, acetic acid and deionized water. The polishing slurry of the present invention can achieve high polishing speed and excellent polishing uniformity, and is easy to store for a long time due to high dispersion stability. Do.

Description

Slurry composition for chemical mechanical polishing of metal lines

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing slurry used in a chemical mechanical polishing / planarization (CMP) process for the purpose of planarizing wafers in the manufacture of semiconductor devices. More specifically, the present invention relates to polishing by addition of an iodine compound and a phosphorus compound. The present invention relates to a slurry composition for polishing metal wires having improved performance and dispersion stability.

As the degree of integration of highly integrated circuits gradually increases, so does the requirement for flatness of semiconductor wafers. The reason is that the uniformity of the wafer becomes important because not only the semiconductor wiring becomes thinner but also the density increases, the margin of focus depth in the photoresist process decreases. As a method for increasing uniformity, various methods such as spin on glass etch back (SOG EB) and deposition etch back (DEP'N EB) have been proposed. It is most commonly used because not only extensive planarization is possible by the CMP process but also the CMP method is the best in terms of satisfaction with the planarity.

The CMP process is a process of flattening the wafer surface by adding a slurry containing ultrapure water, an abrasive, an oxidizing agent, and an auxiliary additive to the semiconductor wafer surface, and then performing an orbital motion mixed with rotational and linear motions in contact with the polishing pad. . The slurry used in the CMP process enables the selective etching of the exposed portions of the wafer surface by physical and chemical action, to achieve more improved and optimized planarization.

Such types of CMP slurry may be classified according to the polishing target, and may be classified into an oxide slurry for polishing an insulating layer and a slurry for metal polishing a tungsten or aluminum layer. In general, a metal line polishing slurry is prepared by adding an abrasive, an acid, an oxidizing agent, and a stabilizer to ultrapure water. At this time, silica oxide (SiO ₂ ), alumina (Al ₂ O ₃ ), etc., which are metal oxides, are used most frequently. As the oxidizing agent, hydrogen peroxide and inorganic oxidizing agents are mainly used.

For example, US Pat. No. 5,244,534 uses alumina as an abrasive, hydrogen peroxide as an oxidant, and ammonium hydroxide or potassium hydroxide as a pH adjuster. In addition, in Patent No. 5,340,370, silica was used as an abrasive and potassium ferricyanide was used as an oxidizing agent. However, in the case of the '534 patent, first, polishing should be performed in two stages, which is inconvenient in actual process and economically inefficient compared with the first stage polishing. Second, continuous decomposition of hydrogen peroxide in the slurry is used since only hydrogen peroxide is used as the oxidizing agent. Due to the lowering of the polishing rate is a problem. In the case of the '370 patent, an iron oxide-based inorganic oxidizing agent is used as an oxidizing agent. However, these compounds have been found to significantly reduce the dispersion stability of the slurry. The slurry for CMP is produced by dispersing an abrasive in an aqueous solution, and its dispersion stability is very important. The reason is that when the dispersion stability of the slurry is lowered, scratches are generated on the surface of the wafer during polishing, or it is difficult to maintain a constant polishing rate, which may cause a problem in transferring the slurry. Moreover, such compounds can act as contaminants by metal ions, resulting in lower semiconductor chip yield. In addition, an example of using a halogen compound such as a fluorine compound as an oxidizing agent is disclosed in US Pat. No. 5,516,346. In this case, the fluorine compound may cause damage such as corrosion to the polishing machine, which is a problem in long-term use.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above, to provide a slurry suitable for the CMP process of metal wiring, which has a uniform polishing performance, excellent dispersion stability during long-term storage and does not damage the polishing machine. It is.

That is, the present invention provides a slurry composition for polishing metal wires comprising fine metal oxide powder, iodine compound, hydrogen peroxide, phosphorus compound, acetic acid and deionized water.

Hereinafter, the present invention will be described in more detail.

The slurry composition for polishing metal wires of the present invention is prepared by dispersing fine metal oxide powder, iodine compound, hydrogen peroxide, phosphorus compound and acetic acid in deionized water, preferably

1 to 30% by weight fine metal oxide powder;

0.01 to 0.5 wt% of an iodine compound;

0.25-2% by weight of hydrogen peroxide;

0.01-0.05 weight% of a phosphorus compound; And

Acetic acid 0.03-0.05% by weight

It includes.

The fine metal oxide powder used in the present invention serves as an abrasive, and uses fine powder of silica (SiO ₂ ) and / or alumina (Al ₂ O ₃ ).

The content of the fine metal oxide powder is preferably 1 to 30% by weight based on the total slurry, more preferably 3 to 12% by weight for silica and 3 to 10% by weight for alumina. If the content of the fine metal oxide powder is more than 30% by weight, it is difficult to control the dispersion stability and the polishing rate.However, when the content of the metal oxide fine powder is less than 1% by weight, the dispersion stability is good, but the amount of the abrasive grains is low, resulting in physical polishing performance. It's hard to expect

The iodine-based compound used in the present invention serves as an oxidizing agent to oxidize the metal wiring together with hydrogen peroxide, o-Iodobenzoic acid, 4-Iodobenzoic acid, o-iodine aniline ( at least one compound selected from the group consisting of o-Iodoaniline, m-Iodoaniline and p-Iodoanisole. In the present invention, by using such an iodine-based compound as an oxidizing agent it was possible to achieve a high polishing rate. In addition, when only a single inorganic oxidant is used, an excessive amount of oxidant should be added in order to ensure high polishing performance, which has been pointed out as a problem that results in a decrease in dispersion stability of the slurry. Since iodine compound and hydrogen peroxide are used in combination, it is possible to reduce the contamination by metal contaminants and to prevent the deterioration of dispersion stability. Furthermore, unlike the conventional fluorine-based compound, the iodine-based compound does not cause corrosion of the polishing machine and does not cause a problem in use.

The content of the iodine-based compound is preferably 0.01 to 0.5% by weight relative to the total slurry, more preferably 0.02 to 0.1% by weight. In addition, the hydrogen peroxide used as the oxidant together with the iodine-based compound is added to 0.25 to 2% by weight, more preferably 0.5 to 1.5% by weight relative to the total slurry. If the iodine compound and the hydrogen peroxide exceed the content range, the erosion or dishing occurs severely in the plug of the semiconductor circuit, whereas if the iodine compound and the hydrogen peroxide exceed the content range, the oxidation power of the slurry is too weak to be normal. In particular, when the iodine compound is added in excess, the dispersion stability of the slurry decreases, and even during polishing, corrosion or pitching occurs, thereby lowering the yield of semiconductor circuits. Will have

Phosphorus-based compound used in the present invention serves to maintain a uniform polishing rate by maintaining a constant oxidizing power of the slurry by preventing the hydrogen peroxide in the slurry to be continuously decomposed, such as trimethyl phosphite ) And / or triethyl phosphite.

The content of the phosphorus-based compound is preferably 0.01 to 0.05% by weight relative to the total slurry, more preferably 0.02 to 0.04% by weight, if the content is out of the above range can not achieve the object of the present invention.

Acetic acid used in the present invention serves as a pH adjusting agent, it is preferable to add so as to be 0.03 to 0.05% by weight relative to the total slurry.

The polishing slurry of the present invention comprising the aforementioned components is very suitable for polishing tungsten or aluminum, which is a semiconductor wiring material.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example One

A mixture of 50 g of fumed silica (commercial Aerosil 90G), 928.8 g of deionized water, 0.5 g of o-iodinebenzoic acid, 20 g of hydrogen peroxide (50%), 0.4 g of acetic acid, and 0.3 g of trimethylphosphite was 2,000 rpm in a 2 L polyethylene flask. The slurry obtained by stirring and dispersing at a rate of 90 minutes was filtered through a 1 μm depth filter to prepare a polishing slurry.

In order to evaluate the polishing performance of the slurry thus prepared, a tungsten-coated wafer was subjected to a quill speed of 120 rpm, a pad speed of 120 rpm, and a slurry flow rate of 150 ml / min using a Strasbaugh 6EC polishing machine. Polishing for 1 minute, the results are shown in Table 1 below.

Example 2 To 5

Except for the use of 4-iodine benzoic acid, o- iodine aniline, m- iodine aniline, or p- iodine anisole instead of o-iodine benzoic acid in Example 1 to prepare a polishing slurry and polishing performance It evaluated, and the result is shown in Table 1.

Example 6

Except for using triethyl phosphite instead of trimethyl phosphite in Example 1 to prepare a polishing slurry in the same manner and to evaluate the polishing performance, the results are shown in Table 1.

Example 7 To 11

In Examples 1 to 5, except that the amounts of o-iodine benzoic acid, 4-iodine benzoic acid, o-iodine aniline, m-iodine aniline and p-iodine anisole were respectively reduced to 0.2 g, for polishing Slurry was prepared and the polishing performance was evaluated, the results are shown in Table 1.

Example 12

Except that the addition amount of triethyl phosphite in Example 6 to 0.4g to prepare a polishing slurry in the same manner and evaluated the polishing performance, the results are shown in Table 1.

Example 13 To 15

Polishing performance was evaluated in the same manner except that the slurry prepared in Example 1 was evaluated after 30, 60, and 90 days, respectively, and the results are shown in Table 1.

Example 16

Except for using the fumed alumina instead of fumed silica in Example 1 to prepare a polishing slurry in the same manner and to evaluate the polishing performance, the results are shown in Table 1.

Comparative example One

Except for the use of ferric nitrate (ferric nitrate) instead of o-iodine benzoic acid in Example 1 to prepare a polishing slurry in the same manner and to evaluate the polishing performance, the results are shown in Table 1.

Comparative example 2

Except for increasing the addition amount of o-iodine benzoic acid in Example 1 to prepare a polishing slurry in the same manner and evaluated the polishing performance, the results are shown in Table 1.

Comparative example 3 To 5

Except for using the slurry in which the trimethyl phosphite is not added in Examples 13 to 15 was evaluated for the polishing performance, the results are shown in Table 1.

division Average size (㎛) Scratches () Removal rate (Å / min) Erosion Dishing Corrosion Example 1 0.156 5 3,850 630 110 N.D. Example 2 0.156 6 3,860 630 100 N.D. Example 3 0.155 5 3,830 600 80 N.D. Example 4 0.156 5 3,820 610 80 N.D. Example 5 0.156 6 3,800 550 75 N.D. Example 6 0.156 5 3,860 610 110 N.D. Example 7 0.155 5 3,830 480 90 N.D. Example 8 0.155 7 3,830 470 90 N.D. Example 9 0.154 6 3,800 440 70 N.D. Example 10 0.155 5 3,790 450 70 N.D. Example 11 0.155 6 3,750 510 60 N.D. Example 12 0.156 5 3,810 560 90 N.D. Example 13 0.157 7 3,730 600 90 N.D. Example 14 0.159 7 3,700 580 90 N.D. Example 15 0.159 9 3,690 570 70 N.D. Example 16 0.224 11 4,150 650 120 N.D. Comparative Example 1 0.189 33 3,340 1,530 190 20 Comparative Example 2 0.173 30 4,950 1,670 150 10 Comparative Example 3 0.206 65 1,380 280 100 N.D. Comparative Example 4 0.236 138 1,010 260 80 N.D. Comparative Example 5 0.298 293 620 170 80 N.D.

[Remarks]

* The erosion, dishing and corrosion are based on a pattern wafer with a line width of 0.2 μm.

* The scratch has a size of 0.3 ㎛ or more.

* N.D. stands for Not Detected.

As described in detail above, using the polishing slurry of the present invention can achieve a high polishing rate and excellent polishing uniformity, high dispersion stability is easy to long-term storage.

Claims (5)

1 to 30% by weight of fine metal oxide powder, 0.01 to 0.5% by weight of iodine compounds, 0.25-2% by weight of hydrogen peroxide, 0.01-0.05% by weight of a phosphorus compound, Acetic acid 0.03-0.05% by weight, and In the slurry composition for polishing metal wire containing deionized water as the remaining component, the iodine-based compound is selected from the group consisting of o-iodinebenzoic acid, 4-iodinebenzoic acid, o-iodineaniline, m-iodineaniline and p-iodineanisol. Slurry composition for metallization polishing, characterized in that at least one compound selected. delete The slurry composition for polishing a metal wire according to claim 1, wherein the metal oxide is silica (SiO ₂ ) and / or alumina (Al ₂ O ₃ ). delete The slurry composition for polishing metal wire according to claim 1, wherein the phosphorus compound is trimethyl phosphite and / or triethyl phosphite.