KR20020008933A - Composition for cmp(chemical mechanical polishing) - Google Patents

Abstract

PURPOSE: Provided is a chemical mechanical polishing(CMP) composition, which can reduce the generation of mu-scratch after polishing and can be used as a polishing agent for a wafer of a semiconductor. CONSTITUTION: The CMP composition comprises 0.1-50wt% of at least one metal oxide selected from the group consisting of SiO2, Al2O3, CeO2, ZrO2, and TiO2, 45-99wt% of deionized water, and 0.01-10wt% of a polyether modified dimethylsiloxane comprising the repeat unit(formula), wherein x, y, n, and m are independently integers of 20-100, and R1 is -H or -CH.

Description

Composition for CPM {COMPOSITION FOR CMP (CHEMICAL MECHANICAL POLISHING)}

The present invention relates to a composition for chemical mechanical polishing (hereinafter referred to as CMP), and more specifically, to a polishing composition comprising deionized water and a metal oxide as a main component, and adding a silicon compound to a polishing material after CMP. The present invention relates to a composition for CMP which prevents or minimizes the generation of mu-scratches.

In recent years, as semiconductor devices have become higher performance and higher integration, they have entered the era of ultra large scale integration (hereinafter referred to as ULSI) represented by 256M byte and 1G byte DRAM. With the trend toward miniaturization, next-generation devices will require 0.18-0.12nm lines. In order to obtain a desired resolution in such a highly integrated photo process, it is necessary to increase the stepper performance, increase the lens numerical aperture, and shorten the wavelength of light. However, if these conditions are met, the depth of focus (DOF) is shallow and the resolution of the device surface is insufficient due to the step difference of the device surface.

On the other hand, when the wiring structure is miniaturized and a high density integrated circuit is to be obtained, the number of wiring layers needs to be multilayered. In the case of a logic element array (Logic), the number of layers is increased to 6-7 layers, and in the case of DRAM, the number of layers is 2-2. It will increase to the third floor. As the number of wiring layers increases, the surface structure of the device becomes more complicated, and the degree of surface irregularities also increases.

Planarization technology has emerged as an important technology to solve the problems caused by the reduction of the depth of focus margin and the multilayer structure of the wiring structure during lithography. This is because the surface planarized is not only easy to lithography and wiring but also these processes can be ideally performed. Conventional wafer planarization processes (such as Reflow / SOG Etch Back / ECR Depo & Etch) are mostly partial planarization techniques and are insufficient to realize wide area planarization. Among these, CMP is the planarization technique that has attracted attention as the most efficient technique that can realize wide area planarization.

The principle of the CMP technique is to supply a slurry of polishing liquid while the polishing material is brought into contact with the polishing pad surface to chemically react the surface of the polishing material and to physically move the polishing pad and the polishing material relative to each other. It is to flatten the uneven portion of the material to be polished.

The main components of the composition for CMP include deionized water, metal oxides, pH or bases for pH adjustment, and oxidizing agents for improving the polishing rate. Among them, metal oxides include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), cerium oxide (CeO ₂ ), zirconium oxide (ZrO ₂ ), and titanium oxide (TiO ₂ ), which are fumed or sol-gel. It is manufactured by the (Sol-Gel) method. Known matters regarding these slurry compositions are classified according to types and additives of metal oxides, for example, slurry composed of silica / amine as slurry for polishing an insulating layer (US Pat. No. 4,169,337), slurry composed of silica quaternary ammonium salt (US Patent No. 5,139,571), Alumina / H202 (US Patent No. 5,244,523), Silica / K ₂ Fe (CN) ₆ (US Patent No. 5,340,370), Slurry for Polishing Metal Wires and Plugs (European) Patent No. 786,504), slurry consisting of metal oxide / oxidant / fluorine ions (WO Patent No. 9,743,070) and the like. The slurries are slurries that are actually used for semiconductor production according to the material to be polished and the CMP process, and the polishing rate, flatness, and selectivity of the polishing performance evaluation items are somewhat satisfactory. Has a problem that a large amount is generated. Defects such as μ-scratches on the material to be polished after CMP are mostly caused by some large abrasive particles contained in the slurry. The size of such large particles is about several micrometers (1-10 micrometers), which may be caused by aggregation due to a change in the dispersion state of the abrasive in the slurry or drying as the slurry is exposed to the outside air. In addition, a compound capable of minimizing the number of large particles generated by agglomeration by preventing a change in dispersion state of the abrasive and buffering the generated large particles in contact with the material to be polished is required. In particular, in the case of thin trench isolation (hereinafter referred to as STI) process, the occurrence of μ-scratch is fatal because it causes the device to fail, and the structure forming the trench is thin and fine at about 200 nm, causing the μ-scratch to occur. This is because the STI structure itself is destroyed and affects trenches or capacitors formed on the upper layer. Therefore, in the CMP process, it is very important to remove the micro-scratches.

An object of the present invention for solving the above problems is to add a silicon compound to the polishing composition mainly containing deionized water and metal oxides for CMP to prevent or minimize the generation of μ-scratch on the material to be polished after CMP It is to provide a composition.

That is, the present invention

Metal oxides 0.1-50% by weight,

45-99% by weight deionized water and

Polyether-modified dimethylsiloxane composed of the monomer of formula (1)

0.01-10 wt%

It is to provide a composition for CMP comprising a.

(Wherein x, y, n, m are each independently an integer between 20 and 100; R1 is -H for ethylene oxide and R1 is -CH group for propylene oxide)

Hereinafter, the present invention will be described in detail.

Metal oxides used in the present invention include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), cerium oxide (CeO ₂ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), and the like. It is manufactured by the Sol-Gel method. The particle size of the primary particles of the metal oxide, that is, the particles before the aqueous solution dispersion is 10-100 nm, preferably 20-60 nm (BET measurement result). If the particle size of the primary particles is less than 10nm, the polishing rate is lowered and the productivity is not good, and if the particle size exceeds 100nm, the polishing rate is faster, which is advantageous in terms of productivity but difficult to disperse Since large particles are present in a large amount, it is not good to increase the incidence of μ-scratch.

The preferred particle size of the secondary particles of the metal oxide, that is, particles in an aqueous solution dispersion state is 50 to 500 nm, more preferably 50 to 250 nm. If the particle size is less than 50 nm, the polishing rate is slow, which is not good in terms of productivity. If the particle size is more than 500 nm, the micro-scratch increases not only rapidly but also the sedimentation stability is lowered, so that it is settled at room temperature for more than one week. Since this happens, a pretreatment step (stirring step) is additionally required in the CMP process, which is not good.

The content of the metal oxide is 0.1 to 50% by weight based on the whole composition, preferably 1 to 25% by weight. Generally, the polishing liquid slurry using silica as an abrasive is used for polishing a semiconductor wafer insulating layer in a content of 9-15% by weight, and in the case of polishing for metal wires and plugs, the content is 3-6% by weight. .

In the present invention, the silicone additive is used as an essential additive in the polishing composition component and is a polyether-modified dimethylpolysiloxane copolymer composed of the monomer of Formula 1 below. Polyether-modified dimethylpolysiloxane of the formula (1) is a compound having improved compatibility by being made by modifying the silicone chain by adding various organics or by controlling the number of branches. One method for controlling the compatibility of the polyether modified dimethylpolysiloxanes is to control the proportion of polyether groups, which also affects surface tension. In other words, as the number of dimethyl groups increases, the surface tension decreases, and as the number decreases, the surface tension increases. In addition, the polarity of the silicone additive structure may be adjusted when the polyether itself is changed. That is, the polyether chain is composed of ethylene oxide and propylene oxide. Polyethylene oxide is hydrophilic (polar) and polypropylene oxide is hydrophobic (nonpolar). It is possible to change the polarity of the silicon additive structure by adjusting the ratio of the polyethylene oxide and polypropylene oxide.

[Formula 1]

(Wherein x, y, n, m are each independently an integer between 20 and 100; R1 is -H for ethylene oxide and R1 is -CH group for propylene oxide)

The content of the silicone additive is 0.01-10% by weight based on the total composition. If the content is less than 0.01% by weight can not expect the effect of the present invention, if it exceeds 10% by weight not only the effect of the addition of the silicone additive is exhibited, but also foaming occurs to remove the removal rate (removal rate) during polishing It is not good because it lowers.

Although the precise description of the effect of reducing the mu-scratch incidence during the CMP slurry polishing performance by the silicone additive is impossible, it may be explained on the following principle. That is, it is considered that the polyether-modified dimethylpolysiloxane compound acts as a wet dispersant to lubricate by preventing aggregation or agglomeration of metal oxides.

The addition order of the additives is not particularly limited and may be added before or after the dispersion of the metal oxide, and may be added to a commercially available slurry composition to have the same effect. In addition, when the silicon additive is used, the slurry particles do not settle during long-term storage, because the additive increases dispersion stability of the slurry particles for CMP. Therefore, the slurry for CMP according to the present invention exhibits an effect of reducing the incidence of µ-scratch than the conventional slurry for CMP. In addition, since the thixotrpy phenomenon in which the viscosity of the slurry rises before dispersion is prevented even during the slurry preparation, a side effect of producing the slurry may be very advantageous when the additive is not used.

The polishing composition according to the present invention may additionally add a second additive depending on the type of material to be polished. For example, when polishing the insulating layer of the wafer, a basic material such as KOH or an amine salt may be used. When polishing metal wires and plugs, an acid such as H ₂ SO ₄ , HNO ₃ , CH ₃ COOH and an oxidizing agent can be added.

The present invention will be described with reference to the following examples, and the following examples are only described for the purpose of illustrating the present invention and are not intended to limit the protection scope of the present invention.

Example 1

A mixture of 130 g of commercially available Aerosil 200 (Degussa), 18 g of 20% -KOH solution, and 860 g of deionized water was placed in a 2 L polyethylene flask, premixed at 1000 rpm for 2 hours, and then 5 g (0.5 g) of polyether modified dimethylpolysiloxane. By weight percent), which is a newly developed method of the present inventors, that is, a method of accelerating the premixed silica in an aqueous solution to high pressure to cause shearing force, impact and cavitation in the orifice. The mixture was dispersed in [Korean Patent Application Nos. 98-39212, 99-34608]. The resulting slurry was filtered using a 1 μm thick filter and then ground for 2 minutes under the following conditions, and the polishing rate was measured by changing the thickness removed by polishing. The number of occurrences was measured. The polishing performance evaluation results are shown in Table 1.

Examples 2-5

Except for fumed silica, except that each of the metal oxides shown in Table 1 and the pH after dispersion was adjusted in the same manner as in Example 1, the polishing performance evaluation results are shown in Table 1 .

Comparative Example 1

Except that polyether modified dimethylpolysiloxane was not added, it was carried out in the same manner as in Example 1, the results of the polishing performance evaluation is shown in Table 2.

Comparative Example 2-5

The polishing process was carried out in the same manner as in Example 1 except that no polyether modified dimethylpolysiloxane was added, the metal oxides shown in Table 2 were used instead of the fumed silica, and the pH after dispersion was adjusted differently. The evaluation results are shown in Table 2.

[Polishing condition]

Pad type; IC1000 / SubaIV Stack type (Rodel)

Platen speed; 90 rpm

Spindle speed; 30 rpm

Down force; 8 psi

Back pressure; 0psi

* Temperature ; 25 ℃

* Slurry flow rate; 150ml / min

Grinding machine; Model 6EC (STRASBAUGH)

* Material to be polished; 6 "-wafer with PE TEOS

As confirmed through the results of the Examples and Table 1, the composition for CMP of the present invention has the advantage that the mu-scratch incidence is reduced.

Claims (4)

Metal oxides 0.1-50% by weight, 45-99% by weight deionized water and Polyether-modified dimethylsiloxane consisting of repeating units of the formula 0.01-10 wt% Composition for CMP comprising a. [Formula 1] (Wherein x, y, n, m are each independently an integer between 20 and 100; R1 is -H for ethylene oxide and R1 is -CH group for propylene oxide) The metal oxide of claim 1, wherein the metal oxide is one selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), cerium oxide (CeO ₂ ), zirconium oxide (ZrO ₂ ), and titanium oxide (TiO ₂ ). The composition for CMP characterized by the above-mentioned. The composition for CMP according to claim 1, wherein the average particle size of the primary particles of the metal oxide is 10-100 nm. The composition for CMP according to claim 1, wherein the average particle size of the secondary particles of the metal oxide is 50 to 500 nm.