KR100421928B1 - Slurry composition for polishing metal line of semiconductor wafer - Google Patents

Abstract

The present invention relates to a slurry composition for polishing a metal wiring of a semiconductor wafer, and more particularly, to a metal wiring polishing composition comprising deionized water, a metal oxide fine powder, an iodine compound, hydrogen peroxide, a phosphorus compound, and a pH adjusting agent. By the present invention, it is possible to provide a polishing composition having high polishing rate, flatness and polishing uniformity, and improved dispersion stability even during long-term storage of the slurry.

Description

Slurry composition for metallization polishing of semiconductor wafers {SLURRY COMPOSITION FOR POLISHING METAL LINE OF SEMICONDUCTOR WAFER}

The present invention relates to a slurry composition used in a chemical mechanical polishing / planarization (CMP) process aimed at planarization of a wafer surface in a semiconductor manufacturing process.

The chemical mechanical polishing / planarization (CMP) process refers to a process of polishing a surface of a semiconductor wafer using a slurry for CMP to which ultrapure water, an abrasive, an oxidizing agent, an auxiliary additive, and the like are added, a polishing pad made of polyurethane, and the like. A typical CMP process is as follows. In the CMP polishing machine, the polishing pad and the wafer are brought into contact with each other to perform an orbital motion in which the polishing pad and the wafer are mixed with rotational and linear motions, thereby dropping a slurry containing an abrasive and the like to polish the wafer. The CMP process selectively removes portions exposed to the wafer surface by the physical action of the abrasive and the chemical action of the added compound, providing improved and optimized planarization.

In the fabrication of highly integrated circuits, the flatness of semiconductor wafers is increasing with increasing integration. The reason is that the uniformity of the wafer becomes important as the semiconductor wiring becomes thinner and the density increases and the margin of focus depth in the photoresist process becomes smaller. Various methods such as spin on glass etch back (SOG EB) or DEP'N EB (deposition etch back) can be used to increase the planarization of the wafer, but the CMP method has recently been applied to wide area planarization and highly integrated circuits. It is widely used because not only wide flatness is possible only in CMP, but also satisfies flatness.

The slurry for CMP can be classified according to the polishing object, and can be broadly classified into an oxide polishing slurry for polishing an insulating layer and a metal polishing slurry for polishing a tungsten or aluminum layer.

In general, in the case of a metal polishing slurry, an abrasive, an acid, an oxidizer, a stabilizer, and the like are added to ultrapure water. As the abrasive, metal oxides such as silica (SiO ₂ ), alumina (Al ₂ O ₃ ), and the like are most commonly used. As the oxidizing agent, hydrogen peroxide and inorganic oxidizing agents are mainly used. For example, according to US Pat. No. 5,244,534, a polishing slurry was prepared by using alumina as an abrasive, hydrogen peroxide as an oxidant, and ammonium hydroxide or potassium was added. In addition, US Pat. No. 5,340,370 uses silica as an abrasive and prepared cyanide slurry using potassium cyanide iron as an oxidizing agent. In addition, US Pat. No. 4,956,313, US Pat. No. 6,077,337, and the related technologies are mentioned.

However, the U.S. Patent No. 5,244,534 has a problem in achieving a constant polishing performance as well as inconvenient to use because it has to be polished in two steps. Moreover, it is economically inefficient compared to one-stage polishing. In addition, when only hydrogen peroxide is used as an oxidizing agent, hydrogen peroxide is continuously decomposed in the slurry, and thus has a weak point in having polishing performance such as a constant polishing rate. In the case of U.S. Patent No. 5,340,370, an inorganic oxidizing agent of iron oxide type was used as an oxidizing agent. However, such compounds greatly reduce dispersion stability, and can act as a cause of contamination caused by metal ions, leading to a decrease in yield of semiconductor chips. . In the case of the slurry used for CMP, the dispersion stability is important because the abrasive is prepared by dispersing in an aqueous solution. If the dispersion stability is lowered, scratches may occur on the surface of the wafer during polishing, or there may be a problem in having a constant polishing rate, and a problem may occur in transporting the slurry. In addition, U.S. Patent No. 5,516,346 using a halogen compound as an oxidizing agent may easily cause corrosion in the polishing machine due to the addition of fluorine-based compounds, which may cause problems in long-term use.

The present invention is to solve the problems of the prior art as described above, by adding a phosphorus-based compound to reduce the decomposition of hydrogen peroxide to the slurry composition to maintain a constant oxidizing power of the slurry to have a uniform polishing rate, An object of the present invention is to provide a slurry composition for polishing metal wires having a high polishing rate by using an iodine-based oxidant together.

That is, the present invention relates to a slurry composition for polishing metal wires including deionized water, fine metal oxide powder, iodine compound, hydrogen peroxide, phosphorus compound, and pH adjusting agent.

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

As the abrasive, which physically plays a role in the composition of the present invention, metal oxides such as silica, alumina, zirconia, ceria, and the like are used. It is suitable to add in the range of 1 to 30% by weight, preferably 3 to 12% by weight for silica, and 1 to 30% by weight, preferably 3 to 10% by weight for alumina, zirconia and ceria. It is appropriate to be. If the addition amount is out of this range, it is difficult to control the dispersion stability and polishing rate, and if the addition amount is small, the dispersion stability is good, but it is difficult to expect physical polishing performance due to the low abrasive particles.

Since the slurry for CMP of the present invention is used to polish metal wires or the like on a semiconductor wafer, an oxidizing agent and a pH adjusting agent are added to oxidize and soften the metal layer. As the oxidant component, an iodine compound and hydrogen peroxide are added. In the case of the iodine-based compound does not reduce the dispersion stability of the slurry, unlike the fluorine-based has the advantage that does not cause corrosion in the polishing machine. In the present invention, since hydrogen peroxide is used together with the iodine compound, the polishing rate can be increased, thereby reducing the amount of iodine compound added, reducing contamination by metal contaminants, and improving dispersion stability. .

The iodine compound is preferably added in an amount of 0.01 to 0.5% by weight, more preferably 0.02 to 0.1% by weight. If it is added in excess of the above range, the dispersion stability of the slurry is lowered, and in addition, corrosion or pitching may occur at the time of polishing, thereby lowering the yield of semiconductor circuits. Have. In addition, the addition of less than this does not appear to improve the polishing rate. As the iodine-based compound, specifically, iodobenzene diacetate, iodoacetic acid, iodoethane, etc. may be used, and more preferably, iodobenzene diacetate is dissolved in distilled water or alcohol. do.

The hydrogen peroxide is added in the range of 0.5 to 4.0% by weight, preferably 1.0 to 3.0% by weight, based on a 50% by weight solution. If it is added in excess of the above range, erosion or dishing occurs badly in the plug of the semiconductor circuit, etc., and when less than this, the oxidation power of the slurry is weak and it is difficult to have a normal polishing performance.

To the slurry composition of the present invention, a phosphorus-based compound is added to prevent hydrogen peroxide from continuously decomposing. The amount of the iodine compound added is preferably 0.01 to 0.05% by weight, more preferably 0.02 to 0.04% by weight. If it is added in excess of the above range, erosion or dishing occurs badly in the plug of the semiconductor circuit. In addition, when less than this, the slurry oxidation power is too weak to have a normal polishing performance. Specifically, the phosphorus-based compound may be trimethyl phosphite or triethyl phosphite.

Nitric acid, acetic acid, sulfuric acid or phosphoric acid is added to the slurry composition of the present invention as a pH adjusting agent. The pH adjusting agent is added in the range of 0.3 to 0.5% by weight so that the pH of the slurry composition is in the range of 1.5 to 4.5, preferably 2.0 to 4.0. If the pH is out of the above pH range, the polishing rate is lowered and a large amount of scratches may occur. If the pH is lower than this, a large amount of scratches may occur and handling may require attention.

Hereinafter, the present invention will be described in more detail with reference to the following examples. The following examples are provided for the purpose of explanation and are not intended to limit the present invention.

Example 1

A mixture of 50 g of fumed silica (commercial Aerosil 90G), 923.8 g of deionized water, 0.5 g of urethane benzene diacetate, 5 g of propanol, 20 g of hydrogen peroxide (50%), 4 g of nitric acid, and 0.3 g of trimethyl phosphite was 2,000 rpm in a 2 L polyethylene flask. The slurry obtained by stirring for 90 minutes at and dispersed was filtered using a 1 μm depth filter to prepare a slurry. The slurry was polished using Strasbaugh 6EC for 1 minute at a quill speed (120 rpm) and a pad speed (120 rpm) at a tungsten-coated wafer for 1 minute, and the flow rate of the slurry was 150 ml / min. Adjusted. Table 1 shows the measurement results of the physical properties after polishing.

Example 2, 3

Except that the amount of addition of 0.1g and 5g respectively of the addition amount of the urethral benzene diacetate in Example 1 was carried out in the same manner, the results are shown in Table 1.

Example 4

Except that in addition to the urethoacetic diacetate and propanol 1.0g in addition to the urethoacetic acid in Example 1 was carried out in the same manner, the results are shown in Table 1.

Example 5

Except that in addition to the uretho benzene diacetate and propanol in Example 1 1.0g of the urethane ethane was carried out in the same manner, the results are shown in Table 1.

Example 6

Except for using triethyl phosphite instead of trimethyl phosphite in Example 1 was carried out in the same manner, the results are shown in Table 1.

Examples 7-9

After the slurry prepared in Example 1 was left for 30 days, 60 days, 90 days, the physical properties were evaluated, and the results are shown in Table 1.

Example 10

Except for using silica fume alumina instead of silica in Example 1 was carried out in the same manner, the results are shown in Table 1.

Comparative Example 1

Except for the addition of ferric nitrate (ferric nitrate) in place of the urethane benzene diacetate in Example 1 was carried out in the same manner, the results are shown in Table 2.

Comparative Example 2

Except that the addition amount of the urethral benzene diacetate in Example 1 to 8g was carried out in the same manner, the results are shown in Table 2.

Comparative Example 3

Except for the addition of the urethral benzene diacetate in Example 1 was carried out in the same manner, the results are shown in Table 2.

Comparative Example 4

Except not adding trimethyl phosphite in Example 1 was carried out in the same manner, the results are shown in Table 2.

Comparative Examples 5-7

After the slurry prepared in Comparative Example 3 was left for 30 days, 60 days and 90 days, the physical properties were evaluated, and the results are shown in Table 2.

Average size (㎛) Scratching () Removal rate (nm / min) Erosion Dishing WIWNU (%) Example 1 0.155 5 3,830 520 80 2.8 Example 2 0.155 5 3,750 500 100 3.0 Example 3 0.156 7 3,880 600 120 3.1 Example 4 0.156 8 3,720 480 100 3.1 Example 5 0.155 5 3,700 510 70 2.8 Example 6 0.155 6 3,820 510 80 2.7 Example 7 0.156 6 3,720 510 75 2.9 Example 8 0.156 6 3,700 480 90 3.0 Example 9 0.158 8 3,650 470 110 3.0 Example 10 0.220 11 4,250 580 120 2.6

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

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

* WIWNU: Within wafer non uniformity.

Average size (㎛) Scratching () Removal rate (nm / min) Erosion Dishing WIWNU (%) Comparative Example 1 0.190 31 3,250 1,250 160 3.8 Comparative Example 2 0.165 32 3,950 1,120 140 3.8 Comparative Example 3 0.163 18 1,970 630 90 4.0 Comparative Example 4 0.160 15 3,260 590 80 3.2 Comparative Example 5 0.183 43 2,560 890 120 2.9 Comparative Example 6 0.192 48 2,130 920 120 3.2 Comparative Example 7 0.206 135 1,860 900 130 3.3

The slurry composition according to the present invention has high polishing rate, flatness, and polishing uniformity, and has an effect of improving dispersion stability even during long-term storage of the slurry.

Claims (6)

A slurry composition for polishing metal wires comprising deionized water, fine metal oxide powder, iodine compound, hydrogen peroxide, phosphorus compound, and pH adjusting agent. The slurry composition for polishing metal wire according to claim 1, wherein the metal oxide is selected from the group consisting of silica, alumina, zirconia and ceria. The slurry composition for polishing metal wires according to claim 1, wherein the iodine-based compound is selected from the group consisting of iodobenzene diacetate, iodoacetic acid and iodoethane. The slurry composition for polishing metal wire according to claim 1, wherein the phosphorus compound is trimethyl phosphite, triethyl phosphite or a mixture thereof. The method of claim 1, wherein the fine metal oxide powder is 1 to 30% by weight, the content of the iodine compound is 0.01 to 0.5% by weight, the content of hydrogen peroxide (50%) is 0.5 to 4.0% by weight, and the content of the phosphorus compound is 0.01 to 0.05% by weight, the content of the pH regulator is 0.3 to 0.5% by weight, the remainder is deionized water, the slurry composition for polishing metal wires. The slurry composition for polishing metal wires according to claim 1, wherein the pH adjusting agent is selected from the group consisting of nitric acid, acetic acid, sulfuric acid, and phosphoric acid.