KR20010055401A - Composition for cmp polishing - Google Patents

Abstract

PURPOSE: A composition for polishing is provided for little generating u-scratch on surface of wafer after grinding it and increasing precipitation-stability and flatness to enable it to be effective in surface levelling process for wafers of semiconductor devices. CONSTITUTION: The composition used in the surface levelling process for wafers of the semiconductor device comprises 30-99 wt.% of deionized water and 0.1-50 wt.% of metal oxide powder as principle components, and 0.001-5 wt.% of polyoxyethylene alkyl phenyl ether compound. The polyoxyethylene alkyl phenyl ether compound is defined as the formula 1 (wherein, R is alkyl group having 1-20 carbon atoms; and n is integer of 2 to 100). The metal oxide is at least one selected from a group consisting of silica, alumina, ceria, zirconia, titania and have the first mean particle size of 0-100nm and the second mean particle size of 50-250nm.

Description

Polishing composition {COMPOSITION FOR CMP POLISHING}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing composition for planarizing a semiconductor device, and more particularly, does not cause mu-scratches, which is characterized by containing deionized water and a metal oxide as a main component and containing a polyoxyethylene alkyl phenyl ether compound. The present invention relates to a polishing composition having excellent sedimentation stability.

As the degree of integration of integrated circuits (ICs) increases today, the importance of global planarization of wafers in semiconductor devices is increasing. Among these, chemical mechanical polishing has started to attract attention as a new planarization technology. Polishing, hereinafter referred to as CMP). A new polishing process called CMP is a wafer polishing method that combines mechanical and chemical polishing developed by IBM in the United States in the late 1980s. CMP process is essential for manufacturing submicron scale highly integrated chip along with PECVD and RIE process. ILD (Interlayer Dielectric) CMP and metal CMP are each layer for high integration and multilayer of devices. It is used for global planarization of.

In the CMP process, the wafer is polished by pads and slurry, and the polishing table to which the pad is attached is rotated, and the wafer is mounted on the head by surface tension or vacuum to simultaneously rotate and oscillate. Pressurize. The head part applies a constant pressure to the table to contact the surface of the wafer and the pad, and a slurry of polishing liquid flows between the minute gaps (pores of the pad) between the contact surfaces by the abrasive particles and the surface projections of the pad. Mechanical polishing is performed and chemical polishing is performed by the chemical composition of the slurry. In the CMP process, the pressure applied between the pad and the wafer makes contact from the top of the device protrusion, and the pressure is concentrated on this part, resulting in a relatively high surface removal rate. The protrusions are removed evenly over to make flattening.

As mentioned above, the planarization process is a necessary process in the fabrication of highly integrated semiconductor chips, and the currently developed planarization processes (Resist Etch Back, Spin on Glass (SOG), and BPSG Reflow) are complicated. While the CMP process can be completed by only one polishing and cleaning process, and has a flattening range of 100 to 1000 times compared to other planarization processes, the CMP process has been spotlighted as a new flattening technology. Is getting.

Polishing compositions used in such semiconductor CMP processes generally include deionized water, metal oxides, and additives in common, and according to the material to be polished, single crystal silicon polishing, insulating layer polishing, metal wiring and plug polishing. It can be divided into three kinds of dragons.

Examples of the polishing composition for CMP, which is currently applied to semiconductor production according to the material to be polished and the CMP process, for example, a slurry composed of silica / amine as a slurry for polishing an insulating layer (US Pat. No. 4,169,337), silica / Quarter grade A slurry composed of ammonium salts (US Pat. No. 5,139,571) is known, and alumina / H ₂ O ₂ (US Pat. No. 5,244,523), silica / K ₃ Fe (CN) ₆ (US Pat. 5,340,370), silicon nitride / dicarboxylic acid (European Patent No. 786,504), slurry consisting of metal oxide / oxidizer / fluorine ion (WO 9,743,070) and the like have been proposed.

However, these polishing slurries have a problem that the polishing rate, flatness, selectivity, and the like have been satisfactorily satisfied in the polishing performance evaluation items, but a large amount of μ-scratch generated on the wafer surface after polishing is generated. The occurrence of μ-scratches in the CMP process has fatal consequences in terms of function and yield of semiconductor devices. For example, if the structure of trenches in STI is as thin and fine as 200 nm, and the micro-scratch occurs, the insulation part may be disconnected, and it may affect the formation of TR or gate formed on the upper layer and fail the device. Since it causes (Device Fail), the polishing composition used in the CMP process is required not to cause defects such as μ-scratch on the wafer surface after polishing.

The micro-scratch on the surface of the wafer after polishing the wafer is also generated by a polishing process such as a platen or quill speed and pressure of the polishing machine, but most of the micro-scratches in the slurry are several micrometers (1 to 10). It is known to be caused by particles having a size of 탆) (hereinafter, large particles), and the generation of these large particles also contributes to the settling of the slurry. These large particles are caused by aggregation or agglomeration (aggregation or agglomeration), rapid changes in temperature and pH, clogging or crusting in delivery / piping systems and the like. As such, large particles are generated due to environmental changes during transportation, storage, and the like regardless of the dispersion method and the degree of dispersion, and thus, there are many difficulties in handling the CMP slurry.

On the other hand, the effective period of the polishing composition used in the CMP process is about 6 months to 12 months with respect to the sedimentation stability, and the polishing composition having poor sedimentation stability causes μ-scratches quickly, and the reproducibility of the polishing rate is high. As a result, the performance of the slurry during long-term storage and long-distance transportation of the polishing composition may be deteriorated over time.

The present invention overcomes the problems of the prior art described above, by adding a polyoxyethylene alkyl phenyl ether compound to a polishing composition based on deionized water and a metal oxide, mu-scratch is not produced or minimized, sedimentation stability and flatness It is to provide a polishing composition having improved.

That is, the present invention is to provide a polishing composition comprising a polyoxyethylene alkyl phenyl ether as a polishing composition comprising deionized water and fine metal oxide powder.

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

The polishing composition of the present invention is characterized by comprising deionized water, metal oxide fine powder, and polyoxyethylene alkyl phenyl ether.

Metal oxides used as abrasives in the polishing composition of the present invention include silica (Si0 ₂ ), alumina (Al ₂ 0 ₃ ), ceria (Ce0 ₂ ), produced by the fuming method or the Sol-Gel method, Any one currently used may be used, such as zirconia (Zr0 ₂ ), titania (Ti0 ₂ ), or the like. In the present invention, the primary particle size of these metal oxides is 10 to 100 nm, preferably 20 to 60 nm (BET measurement results). If the size of the primary particles is less than 10 nm, the removal rate is not preferable because of the low removal rate. On the contrary, if the size of the primary particles is larger than 100 nm, the polishing rate increases, but dispersion is difficult and large particles are present. It can cause a lot of scratches.

It is preferable that the size of the secondary average particle in the water-soluble dispersion state of these metal oxides is 50 to 250 nm, and the maximum particle size is preferably less than 500 nm. Problems may arise. That is, the larger the average particle and the maximum particle, the lower the sedimentation stability, and if left at room temperature for more than 30 days, the sedimentation occurs, and thus it is not preferable because it must undergo a stirring process before use in the CMP process.

The content of these metal oxides in the polishing composition of the present invention is generally 0.1 to 50 wt%, preferably 1 to 25 wt%, based on the total amount of the composition. Specifically, 9 to 15 wt% is used when the polishing composition comprising silica as an abrasive is used for polishing the insulating layer of the semiconductor wafer, and 3 to 6 wt% is used when the metal wiring and plug polishing are used.

Among the polishing composition components of the present invention, in addition to the deionized water and the fine metal oxide powder, polyoxyethylene alkyl phenyl ether represented by the following general formula (1) is included as an essential component.

In the above formula, R is an alkyl group having 1 to 20 carbon atoms,

n is an integer between 2 and 100.

Representative examples of such polyoxyethylene alkyl phenyl ether compounds include polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, and the like. In the present invention, the polyoxyethylene alkyl phenyl ether compound may be used alone or in combination of two or more kinds of the compounds represented by the formula (1).

The content of such polyoxyethylene alkyl phenyl ether compound is 0.001 to 5 wt%, preferably 0.01 to 1 wt% based on the total amount of the polishing composition. If the content of the polyoxyethylene alkyl phenyl ether is less than 0.001 wt%, the effect intended in the present invention cannot be expected. On the contrary, if the content of the polyoxyethylene alkyl phenyl ether is more than 5 wt%, the effect of adding the polyoxyethylene alkyl phenyl ether compound is no longer improved. to be. The content of deionized water in the polishing composition of the present invention is 30 to 99wt%.

In the present invention, the mechanism by which the poly-oxyethylene alkyl phenyl ether significantly improves the micro-scratching properties and flatness of the polishing composition is not precisely identified, but it is estimated to be due to the following causes.

Polyoxyethylene alkyl phenyl ether compounds have humectants, which prevent the agglomeration or condensation of metal oxides in the polishing composition components, thereby inhibiting the formation of large particles causing micro-scratches, and transporting, storing, shipping / This prevents clogging or crusting in the piping system, which leads to a reduction in μ-scratches, and is thought to improve flatness by improving the flowability of the slurry during polishing to ensure uniform contact with the wafer surface.

The point of addition of the polyoxyethylene alkyl phenyl ether compound in preparing the polishing composition of the present invention is not particularly limited, and may be any case before or after dispersing the metal oxide, and may be additionally added to a commercially available slurry composition. The same effect can be obtained.

In the polishing composition of the present invention, other additives such as a base or acid for adjusting pH, an oxidizing agent for improving the polishing rate, and a stabilizer for the stability of the slurry are added within a range that does not impair the physical properties of the composition, depending on the type of polishing material. Can be added. For example, when polishing an insulating layer of a wafer, a base such as KOH or an amine salt, and an acid and an oxidizing agent such as H ₂ S0 ₄ , HN0 ₃ , and CH ₃ COOH are used together when polishing metal wires and plugs. It can be added and used.

The polishing composition of the present invention can be used for polishing various industrial products such as semiconductors, photomasks, glass disks, and synthetic resins, and can be used for surface planarization of semiconductor device wafers, particularly in the semiconductor industry. Specifically, the polishing composition of the present invention can be used for polishing single crystal silicon, polishing interlayer insulating film, polishing metal wiring and plug, and barrier material polishing in the manufacture of semiconductor devices.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are intended to be illustrative, but not limiting.

Example 1

A mixture of 130 g of commercially available silica (Aerosil 200, manufactured by Degussa), 18 g of 20% -KOH solution, and 860 g of deionized water was added to a 2-liter polyethylene flask and premixed at 1000 rpm for 2 hours to polyoxyethylene nonyl phenyl ether lg ( 0.1 wt%) was added and then dispersed for 1 hour at 1500 rpm using a batch-type dynomil containing 500 g of 2 mm glass beads to prepare a polishing composition and evaluated for polishing performance as shown in Table 1 below. . The resulting polishing composition was filtered using a 1 μm Depth filter and then polished for 2 minutes under the following conditions to measure the polishing rate and flatness from the change in thickness removed by polishing, and then using a KLA (TENCOR company) instrument. The number of scratch occurrences was measured.

οAbrasive model: 6EC (STRASBAUGH)

οPolishing condition:

Pad Type: IC1000 / SubaIV Stacked (Rodel)

Platen Speed: 120rpm

Quill Speed: 120rpm

Pressure: 6psi

-Back Pressure: 0psi

-Temperature: 25 ℃

Slurry flow: 150 ml / min

Examples 2 to 3

Except that polyoxyethylene alkyl phenyl ether was used instead of polyoxyethylene nonyl phenyl ether, after the polishing composition was prepared in the same manner as in Example 1, the polishing performance was evaluated and the results are shown in Table 1 together.

Examples 4-7

Instead of fumed silica, other metal oxides were used as described in Table 1, except that the pH was changed after dispersing. The polishing composition was prepared in the same manner as in Example 1, and the polishing performance was evaluated. 1 is shown together.

Comparative Example 1

Except for not adding polyoxyethylene nonyl phenyl ether in Example 1 after preparing a polishing composition in the same manner as in Example 1, the polishing performance was evaluated and the results are shown in Table 2 below.

Comparative Example 2

Except for not adding polyoxyethylene nonyl phenyl ether in Example 4 after preparing a polishing composition in the same manner as in Example 1 and evaluated the polishing performance and the results are shown in Table 2 together.

Comparative Example 3

Except for not adding polyoxyethylene nonyl phenyl ether in Example 5 after preparing a polishing composition in the same manner as in Example 1 and evaluated the polishing performance and the results are shown in Table 2 together.

Comparative Example 4

Except for not adding polyoxyethylene nonyl phenyl ether in Example 6 after preparing a polishing composition in the same manner as in Example 1, the polishing performance was evaluated and the results are shown in Table 2 together.

Comparative Example 5

Except not adding polyoxyethylene nonyl phenyl ether in Example 7, after the polishing composition was prepared in the same manner as in Example 1, the polishing performance was evaluated and the results are shown in Table 2 together.

Metal oxide POE Alkyl Phenyl Ether Compound pH Polishing Speed (Å / min) μ-scratch (wrap / wafer) Polishing uniformity (WIWNU,%) Example 1 Silica (Si0 ₂ ) POE Nonyl Phenyl Ether 11 3,107 2 3.5 Example 2 Silica (Si0 ₂ ) POE octyl phenyl ether 11 3,288 3 3.5 Example 3 Silica (Si0 ₂ ) POE heptyl phenyl ether 11 3,251 6 3.8 Example 4 Alumina (Al ₂ 0 ₃ ) POE Nonyl Phenyl Ether 9 3,895 5 4.1 Example 5 Ceria (Ce0 ₂ ) POE Nonyl Phenyl Ether 4 4,958 8 4.8 Example 6 Zirconia (Zr0 ₂ ) POE Nonyl Phenyl Ether 7 4,695 11 5.2 Example 7 Titania (Ti0 ₂ ) POE Nonyl Phenyl Ether 10 4,047 11 5.2 * POE: Polyoxyethylene * WIWNU (Within Wafer Non-Uniformity): (Standard Deviation / Average Grinding Speed) x100

Metal oxide POE Alkyl Phenyl Ether Compound pH Polishing Speed (Å / min) μ-scratch (wrap / wafer) Polishing uniformity (WIWNU,%) Comparative Example 1 Silica (Si0 ₂ ) No addition 11 3,295 73 6.4 Comparative Example 2 Alumina (Al ₂ 0 ₃ ) No addition 9 3,941 152 6.9 Comparative Example 3 Ceria (Ce0 ₂ ) No addition 4 5,005 173 7.8 Comparative Example 4 Zirconia (Zr0 ₂ ) No addition 7 4,721 296 8.1 Comparative Example 5 Titania (Ti0 ₂ ) No addition 10 4,185 315 8.3

* WIWNU (Within Wafer Non-Uniformity): (Standard Deviation / Average Grinding Speed) x100

Examples 8-10

In order to evaluate the change in polishing performance (μ-scratch) after long term storage, the polishing composition prepared by the same method as in Example 1 was applied for 1 day (Example 8), 60 days (Example 9), 120 days (execution). Example 10) After storage, the respective polishing performances were evaluated and the results are shown in Table 3 below.

Comparative Examples 6 to 8

Except for using the polishing composition in which the polyoxyethylene nonyl phenyl ether is not added in Example 7, each polishing performance was evaluated in the same manner as in Example 8 and the results are shown in Table 3 together.

Metal oxide POE Alkyl Phenyl Ether Compound pH Polishing Speed (Å / min) μ-scratch (wrap / wafer) Polishing uniformity (WIWNU,%) Example 8 Silica (Si0 ₂ ) POE Nonyl Phenyl Ether 11 3,110 One 3.5 Example 9 Silica (Si0 ₂ ) POE Nonyl Phenyl Ether 11 3,121 3 3.4 Example 10 Silica (Si0 ₂ ) POE Nonyl Phenyl Ether 11 3,106 3 3.7 Comparative Example 6 Silica (Si0 ₂ ) No addition 11 3,288 82 6.5 Comparative Example 7 Silica (Si0 ₂ ) No addition 11 3,317 169 7.2 Comparative Example 8 Silica (Si0 ₂ ) No addition 11 3,304 205 7.8

* WIWNU (Within Wafer Non-Uniformity): (Standard Deviation / Average Grinding Speed) x100

As confirmed through the results of the above embodiment, in the polishing composition of the present invention, the generation of large particles causing the micro-scratch after polishing is suppressed so that the occurrence of the micro-scratch is reduced or hardly occurs. Furthermore, the slurry for semiconductor wafer abrasives tends to induce a large amount of μ-scratches, especially when used after long-term storage, whereas the polishing composition of the present invention containing polyoxyethylene alkyl phenyl ether is stored for 6 months or more and then used. It shows consistent polishing performance regardless of the designated period, such as no increase in the number of scratches. In addition, the polishing composition of the present invention has an advantage of excellent sedimentation stability because the dispersion stability is increased compared to the polishing composition without the addition of polyoxyethelin alkyl phenyl ether.

Claims (7)

A polishing composition comprising deionized water and a fine metal oxide powder, wherein the polishing composition comprises polyoxyethylene alkyl phenyl ether. The polishing composition according to claim 1, wherein the polyoxyethylene alkyl phenyl ether is at least one or more of the compounds represented by the following general formula (1). [Formula 1] In the above formula, R is an alkyl group having 1 to 20 carbon atoms, n is an integer between 2 and 100. The polishing composition according to claim 1, wherein the composition contains 0.1-50 wt% of a metal oxide, 30-99 wt% of deionized water, and 0.001-5 wt% of polyoxyethylene alkyl phenyl ether. The polishing composition according to claim 1, wherein the metal oxide is at least one selected from the group consisting of silica, alumina, ceria, zirconia, and titania. The polishing composition according to claim 3, wherein the metal oxide is silica or alumina. The polishing composition according to any one of claims 1 to 4, wherein the average primary particle size of the metal oxide is 0 to 100 nm. The polishing composition according to any one of claims 1 to 4, wherein the size of the secondary average particles in the dispersion of the metal oxide is 50 to 250 nm, and the maximum particle size is less than 500 nm.