KR102643607B1 - Composition for forming thin film, thin film and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a composition for forming a thin film, a thin film using the same, and a method for manufacturing the same, wherein the composition for forming a thin film is a reaction product of titanium tetrahalide and an alkoxyarene-based compound; and a non-polar solvent; the thin film produced therefrom has low specific resistance and excellent step coverage.

Description

Composition for forming a thin film, a thin film using the same, and a method for manufacturing the same {COMPOSITION FOR FORMING THIN FILM, THIN FILM AND MANUFACTURING METHOD THEREOF}

The present invention relates to a composition for forming a thin film, a thin film using the same, and a method for manufacturing the same.

The integration degree of memory and non-memory semiconductor devices is increasing day by day, and as their structures become more complex, the importance of step coverage in depositing various thin films on a substrate is increasing.

Such thin films for semiconductors include metal nitrides, metal oxides, metal silicides, and metals. Typical metal nitride thin films include titanium nitride (TiN), tantalum nitride (TaN), and zirconium nitride (ZrN), and these thin films are doped with aluminum (Al) and copper, which are used as silicon layers of semiconductors and interlayer wiring materials. It is used as a diffusion barrier with (Cu) and as an adhesion layer when depositing a tungsten (W) thin film on a substrate.

In order to obtain excellent physical properties of a thin film deposited on a substrate, the selection of the precursor is the most important requirement. For example, when titanium chloride (TiCl ₄ ) is used to deposit titanium nitride (TiN), which is representative of the nitride metals, Despite the excellent economic efficiency of this metal, it has several problems as follows.

First, chlorine atoms present in the precursor may flow into the deposited titanium nitride thin film, causing corrosion of the aluminum wiring material. Second, since the deposition temperature is high at around 600°C, it is difficult to apply in the case of aluminum wiring with a low melting point. , _Third , during the process, non-volatile by-products such as titanium chloride ammonia complex [ _{TiCl 4} : (NH ₃ ) do.

In addition, methods for manufacturing titanium nitride (TiN) thin films using titanium amide [Ti(NR ₂ ) ₄ , R = CH ₃ or C ₂ H ₅ ] are being developed, but development is difficult due to the instability and risk of the precursor. There was a problem that it was not suitable for application to next-generation semiconductor devices because it had limitations in applying the ALD process.

In order to solve the above-mentioned problems, the purpose of the present invention is to provide a composition for forming a thin film that can effectively remove process by-products generated during substrate formation and improve the uniformity of the thin film.

Additionally, the present invention aims to provide a thin film formed using the thin film forming composition.

Additionally, the present invention aims to provide a method for manufacturing the thin film.

In order to solve the above problems, the present invention provides a reaction product of titanium tetrahalide and an alkoxyarene-based compound; and a non-polar solvent. It provides a composition for forming a thin film comprising a.

Additionally, the present invention provides a thin film formed using the thin film forming composition.

Additionally, the present invention provides a method for producing a thin film including the step of depositing a thin film on a substrate using the composition for forming a thin film.

The composition for forming a thin film of the present invention can effectively remove the content of chlorine (Cl) ions, which are a process by-product, even if the deposition temperature increases when forming a substrate, and when manufacturing a thin film using this composition, the resistivity of the produced thin film is reduced. can reduce and improve step coverage.

Figure 1 is a TEM photograph of the thin film prepared in Example 1.
Figure 2 is a TEM photograph of the thin film prepared in Comparative Example 1.

Hereinafter, the present invention will be described in detail.

1. Composition for thin film formation

The present invention provides a composition for forming thin films.

The composition for forming a thin film according to the present invention is a reaction product of titanium tetrahalide and an alkoxyarene-based compound; and non-polar solvents.

The titanium tetrahalide is a precursor of a composition for forming a thin film, and may include, for example, at least one selected from the group consisting of TiF ₄ , TiCl ₄ , TiBr ₄ and TiI ₄ , and specifically, may be TiCl ₄ However, it is not limited to this.

In addition, titanium tetrahalide has excellent thermal stability and does not decompose at room temperature and exists in a liquid state, so it can be usefully used as a precursor for chemical vapor deposition or atomic layer deposition to deposit a thin film.

The alkoxyarene compound may be included to reduce the content of halogen atoms in the composition.

At this time, the alkoxyarene compound preferably contains a benzene ring or a naphthalene ring because it is not highly reactive with titanium tetrahalide, and more preferably contains a benzene ring.

In addition, the alkoxyarene-based compound preferably contains an alkoxy group because the lone pair of electrons of the oxygen atom of the alkoxy group keeps the halogen atom well. At this time, the alkoxy group may be a C _1-4 alkoxy group.

Furthermore, the alkoxyarene compound may include at least one selected from the group consisting of methoxy benzene, dimethoxy benzene, and ethoxy benzene in terms of vapor pressure.

At this time, the reaction product may be prepared from a composition containing titanium tetrahalide and an alkoxyarene compound at a molar ratio of 1:0.1 to 3. Specifically, the reaction product may be prepared from a composition containing titanium tetrahalide and an alkoxyarene compound at a molar ratio of 1:0.8 to 1.2. If the content of the alkoxyarene compound is added in excess of the upper limit, it may cause generation of impurities and increase the resistance of the manufactured membrane, and if the content of the alkoxyarene compound is added below the lower limit, the halogen atom The reduction effect cannot be obtained.

The reaction product may be a compound that is formed by reacting the titanium tetrahalide and the alkoxyarene compound and includes a coordination bond between titanium as a central metal and an arene ring as a ligand. That is, the reaction product may be a complex in which titanium tetrahalide and an alkoxyarene compound are coordinated. At this time, the number of coordination bonds may vary depending on the mixing molar ratio of titanium tetrahalide and the alkoxyarene compound.

The composition for forming a thin film according to the present invention includes a non-polar solvent as a dilution solvent and the reaction product, and serves to reduce the content of benzene derivatives in the composition produced by the reaction of the titanium tetrahalide and the alkoxyarene compound.

The type of the non-polar solvent is not particularly limited, but for example, it may include at least one selected from the group consisting of substituted or unsubstituted C ₄ -C ₆ cycloalkanes and C ₁ -C ₁₀ alkanes. . When the non-polar solvent contains cycloalkanes and/or alkanes in the carbon number, it is possible to prevent the problem of volatilization of reaction products with relatively high vapor pressure when forming a thin film.

For example, the cycloalkane may be a C ₄ -C ₆ monocycloalkane. Specifically, the cycloalkane may include at least one selected from the group consisting of cyclopentane, ethylcyclohexane, and cyclohexane.

Additionally, the alkane may include at least one selected from the group consisting of pentane, hexane, heptane, and octane.

That is, the nonpolar solvent may include at least one selected from the group consisting of cyclopentane, ethylcyclohexane, cyclohexane, pentane, hexane, heptane, and octane.

The composition may include the reaction product and the non-polar solvent in a weight ratio of 1:1 to 3. Specifically, the composition may include the reaction product and the non-polar solvent at a weight ratio of 1:1.5 to 2.5, or 1.8 to 2.3. If the content of the non-polar solvent exceeds the upper limit, impurities may occur in the film after deposition of the thin film, and if the content of the non-polar solvent is less than the lower limit, the effect of reducing halogen atoms of the alkoxyarene compound may be insufficient.

2. Thin film

The present invention provides a thin film formed using the composition for forming a thin film as described above.

The thin film may include TiN or TiO ₂ .

3. Thin film manufacturing method

The method for producing a thin film according to the present invention includes depositing a thin film on a substrate using the composition for forming a thin film described above.

The deposition may be performed by an atomic layer deposition (ALD) process or a chemical vapor deposition process.

Specifically, a method for manufacturing the thin film will be described.

First, place the substrate in the reaction chamber.

The substrate may be a semiconductor substrate such as a silicon substrate, germanium substrate, silicon-germanium substrate, or a silicon-on-insulator (SOI) substrate. Additionally, the substrate may have a conductive layer or an insulating layer formed on one side.

Furthermore, the reaction chamber may be a chamber in which atomic layer deposition or chemical vapor deposition is performed.

In order to deposit a thin film on a substrate placed in the chamber, the composition for forming a thin film described above is prepared. At this time, the composition for forming a thin film may be in a liquid form.

Next, the liquid thin film forming composition can be injected into the vaporizer and then delivered into the chamber in vapor form. At this time, the method of delivering the thin film forming composition into the chamber is a method of transferring volatilized gas using vapor pressure, a direct liquid injection method, or a liquid transfer method (Liquid) in which the precursor material is dissolved in an organic solvent and transported. Delivery System (LDS), etc. can be used. Specifically, a liquid transfer method may be used to deliver the thin film forming composition into the chamber.

At this time, one or more mixtures selected from argon (Ar), nitrogen (N ₂ ), and helium (He) may be used as a transport gas or dilution gas for moving the thin film forming composition on the substrate.

Next, the transferred thin film forming composition may be adsorbed on the substrate, and the non-adsorbed thin film forming composition may be purged. At this time, an inert gas can be used as the purge gas.

Next, the reaction material can be supplied into the chamber.

The reactive material may include a reducing agent (eg, NH ₃ ) or a nitriding agent (eg, N ₂ ). A metal thin film may be deposited using the reducing agent, and a metal nitride thin film may be deposited using the nitriding agent.

Meanwhile, the reactive material may further include an oxidizing agent such as H ₂ O, H ₂ O ₂ , O ₂ , O ₃ , N ₂ O, etc. In addition, the reaction material and the adsorbed thin film forming composition may react to form a metal oxide thin film.

Next, unreacted material can be purged. Accordingly, excess reaction materials and generated by-products can be removed.

As described above, the manufacturing method includes the steps of adsorbing the composition for forming a thin film on a substrate, purging the non-adsorbed composition for forming a thin film, supplying a reactant, and purging the unreacted material in one unit. cycle, and the one-unit cycle can be repeated to form a thin film of desired thickness.

At this time, the deposition temperature may be 100 to 700 °C.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited by the following examples.

[Example]

Manufacturing example. Preparation of reaction products

Anisole was slowly added to TiCl ₄ at room temperature and stirred to prepare a red solid reaction product. At this time, TiCl ₄ and anisole were mixed at a 1:1 molar ratio, and it was confirmed that the prepared reaction product was a compound in which titanium was the central metal and a phenyl group was coordinated as a ligand.

Example 1.

A composition for forming a thin film was prepared by mixing the reaction product of the preparation example and cyclopentane at a weight ratio of 1:2.

Afterwards, the substrate was placed in the chamber, the prepared thin film forming composition was placed in a bubbler, and argon gas was supplied at 100 sccm at room temperature and heated to 150°C at a rate of 0.05 g/min using an LMFC (Liquid Mass Flow Controller). It was supplied through a vaporizer. The composition grown in vapor phase in the vaporizer was introduced into the chamber for 5 seconds, and then argon gas was supplied at 100 sccm for 10 seconds to perform argon purging. At this time, the pressure within the reaction chamber was controlled at 1 Torr. Afterwards, ammonia (NH ₃ ) as a reactive gas was introduced into the reaction chamber for 5 seconds, and then argon purging was performed for 10 seconds. At this time, the substrate on which the metal thin film was to be formed was heated to 440°C.

The above-described process was repeated 430 times to form a TiN thin film, which is a self-limiting atomic layer.

Comparative Example 1.

A TiN thin film was formed in the same manner as Example 1, except that TiCl ₄ was used instead of the reaction product.

Comparative Example 2.

An attempt was made to form a TiN thin film in the same manner as in Example 1, except that the polar solvent diethyl ether was used instead of cyclopentane, but the thin film was not formed due to the reaction between the reaction product and the polar solvent.

Experimental Example 1.

1-1: Measurement of chlorine (Cl) ion content

The content of Cl ions in the membranes of the examples and comparative examples was measured using a secondary ion mass spectrometer (magnetic sector type secondary ion mass spectrometer, CAMECA IMS 7f magnetic sector SIMS) and is shown in Table 1.

Example 1 Comparative Example 1 Comparative Example 2 Cl content (number) 11,932 13,116 not measurable

As shown in Table 1, the thin film of Example 1 had a lower chlorine ion content than the thin film of Comparative Example 1.

1-2: Resistivity characteristics

The sheet resistance of the TiN thin film prepared in Examples and Comparative Examples was measured using a 4-point probe, and the results are shown in Table 2.

Example 1 Comparative Example 1 Comparative Example 2 resistivity 148 μΩ·cm 161 μΩ·cm not measurable

As shown in 2, the thin film of Example 1 had lower specific resistance than the thin film of Comparative Example 1.

1-3: Step covering characteristics

The step coverage of the TiN thin films prepared in the Examples and Comparative Examples was confirmed using transmission electron microscopy (TEM), and the results are shown in Table 3 and Figures 1 and 2.

Example 1 Comparative Example 1 Comparative Example 2 Step coverage (%) 99.2 96.7 not measurable

As shown in Table 3, it can be seen that the step coverage of the thin film of Example 1 is superior to that of the thin film of Comparative Example 1.

Claims (15)

Reaction products of titanium tetrahalides and alkoxyarene-based compounds; A composition for forming a thin film comprising: and a non-polar solvent,
The reaction product is a composition for forming a thin film, which is a complex in which titanium tetrahalide and an alkoxyarene compound are coordinated. In claim 1,
The titanium tetrahalide is TiF ₄ , TiCl ₄ , TiBr ₄ and TiI ₄ , and includes at least one selected from the group consisting of TiI 4 . In claim 2,
The titanium tetrahalide is TiCl ₄ , a composition for forming a thin film. In claim 1,
A composition for forming a thin film, wherein the alkoxyarene compound contains a benzene ring or a naphthalene ring. In claim 1,
The alkoxyarene-based compound is a composition for forming a thin film containing an alkoxy group of C ₁ -C ₄ . In claim 5,
A composition for forming a thin film, wherein the alkoxyarene compound includes at least one selected from the group consisting of methoxybenzene, dimethoxybenzene, and ethoxybenzene. In claim 1,
The reaction product is a composition for forming a thin film, which is prepared from a composition containing titanium tetrahalide and an alkoxyarene compound at a molar ratio of 1:0.1 to 3. delete In claim 1,
The nonpolar solvent includes at least one selected from the group consisting of substituted or unsubstituted C ₄ -C ₆ cycloalkanes and C ₁ -C ₁₀ alkanes. In claim 9,
The non-polar solvent includes at least one selected from the group consisting of cyclopentane, ethylcyclohexane, cyclohexane, pentane, hexane, heptane, and octane. In claim 1,
The composition is a composition for forming a thin film, comprising a reaction product and a nonpolar solvent in a weight ratio of 1:1 to 3. A thin film formed using the composition for forming a thin film according to claim 1. In claim 12,
The thin film is a thin film containing TiN or TiO ₂ . A method of producing a thin film comprising depositing a thin film on a substrate using the composition for forming a thin film according to claim 1. In claim 14,
A method of manufacturing a thin film, wherein the deposition is performed by an atomic layer deposition (ALD) process or a chemical vapor deposition process.