KR100414871B1 - Method for forming group ⅸ metal layer using atomic layer deposition - Google Patents

Abstract

The present invention provides a method of forming a Group 9 metal film by atomic layer deposition to obtain a high purity Group 9 metal film (cobalt, iridium, rhodium) by allowing impurities at a low temperature and minimizing impurities in the film and suppressing particle generation. For the purpose of, loading a substrate in a reaction chamber of an atomic layer deposition apparatus, adsorbing a Group 9 metal precursor on the substrate, and supplying a reducing reaction gas into the reaction chamber to react with the adsorbed Group 9 metal precursor. To form a Group 9 metal film in atomic layer units.

Description

METHOD FOR FORMING GROUP METAL LAYER USING ATOMIC LAYER DEPOSITION}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming a Group 9 metal used as an electrode of a high dielectric constant and ferroelectric capacitor in a DRAM and a FRAM.

Recently, metals such as iridium (Ir), rhodium (Rh), and cobalt (Co) have been used as electrodes of DRAM / FeRAM capacitors. In addition, it is used as a catalyst in the organic synthesis process.

In addition, chemical vapor deposition (CVD) is mainly applied to uniformly deposit the metals in the highly integrated memory device.

In general, chemical vapor deposition (CVD) is used to deposit a thin film on a substrate such as an exposed film surface on a silicon wafer or wafer, and in chemical vapor deposition, the precursor is heated to a temperature above the decomposition temperature of the precursor. Pyrolytic volatile compounds that are contacted on a substrate. Then, films deposited by chemical vapor deposition, for example, films composed of metals, metal mixtures, metal alloys, ceramics, metal compounds, and mixtures thereof, are formed on the substrate depending on the choice of precursor and the reaction conditions.

This chemical vapor deposition method deposits a thin film having a required thickness on a substrate using a precursor and a reaction gas for pyrolyzing the precursor.

First, various gases are injected into the reaction chamber, and a thin film of the required thickness is deposited on the substrate by chemically reacting gases induced by high energy such as heat, light and plasma.

Conventional chemical vapor deposition of cobalt, rhodium and iridium, Group 9 elements (hereinafter abbreviated as 'Group 9 metals') (M) on the periodic table, is a precursor (MX or MX ₃ where X is an oxidation state of +1 or +3, where X is Anionic ligand) and oxygen (O ₂ ) or hydrogen (H ₂ ) as the reaction gas.

At this time, oxygen (O ₂ ) reacts with the precursor to reduce the oxidized Group 9 metal and at the same time reacts with X as the anionic ligand (Ligand) to generate a reaction product. Here, the anionic ligand means an ion having a non-covalent electron pair, and F-, Cl-, OH-, alkyl (Alkyl), aryl (alkoxy), alkoxy, β-diketonate, cyclopenta Dienyl (cyclopentadienyl), alkylcyclopentadienyl (alkylcyclopentadienyl) and the like.

On the other hand, the reaction of the precursors of the Group 9 metal (MX, MX ₃ ) and the reaction gas is performed as follows.

MX, MX ₃ + O ₂ M + C _x H _y O _z

[Scheme 1] shows the oxidation reaction of the Group 9 precursor, neutral reaction products such as Alkene such as CO, H ₂ , Butene (Butne), H, Butyl (Butyl) through the oxidation, reduction reaction Anionic or cationic reaction products such as alkyl, β-diketonate are formed.

However, the neutral reaction product can be removed by vacuum, but the anion or cationic reaction product remains as an impurity in the Group 9 metal film. In addition, since the decomposition reaction of oxygen (O ₂ ) and ligand (X) is not only very complicated but also reaction takes place in a short time, impurities such as carbon (C), hydrogen (H) and oxygen (O) are contained in the Group 9 metal film. These impurities remain in the thermal process for the densification of the Group 9 metal film or during the subsequent deposition process, and there is a problem of deteriorating the film characteristics of adjacent films including the Group 9 metal film.

In order to solve this problem, when using a reducing gas hydrogen (H ₂ ) as a reaction gas, the deposition temperature must be set higher than 700 ℃ in order to activate the hydrogen (H ₂ ) so that the precursor itself decomposes and carbonate (Carbonate). ), There is still a problem that impurities are still present in the film. In addition, when the Group 9 metal film is applied as an upper electrode of a capacitor using an oxide film such as Ta ₂ O ₅ , BST, PZT, SBT as a dielectric film, when hydrogen (H ₂ ) is used at a high temperature, the oxide film is reduced. Can't secure the property.

In addition, in the case of depositing a Group 9 metal film by chemical vapor deposition using the precursors (MX, MX ₃ ) as described above, a nonvolatile material such as carbonate, through a decomposition reaction in which a reaction gas reacts with a precursor in a gaseous state, An oxide is produced. Such a nonvolatile material is present in the form of agglomerates on the Group 9 metal film, and thus, acts as a main cause of particle generation.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and provides a method for forming a Group 9 metal film by atomic layer deposition which is suitable for minimizing impurities in the film and suppressing particle generation while enabling a low temperature process. have.

1 is a process flowchart showing a method of forming a Group 9 metal film by an atomic layer deposition method according to an embodiment of the present invention;

Figure 2 is a flow chart of the Group 9 metal precursor, the reaction gas and purge gas in accordance with an embodiment of the present invention.

3A to 3C are cross-sectional views illustrating a method of forming a Group 9 metal film according to FIG. 1;

* Explanation of symbols for the main parts of the drawings

11 substrate 12 group 9 metal precursor

13: hydrazine 14: group 9 metal atomic layer

15: Group 9 metal film

Method of forming a Group 9 metal film by the atomic layer deposition method of the present invention for achieving the above object comprises the steps of loading a substrate in the reaction chamber of the atomic layer deposition apparatus, adsorbing a Group 9 metal precursor on the substrate, and And supplying a reducing reaction gas into the reaction chamber to induce a reaction with the adsorbed Group 9 metal precursor to form a Group 9 metal film in atomic layer units.

Preferably, the Group 9 metal precursor is any one of MX or MX ₃ having an oxidation state of +1 or +3, wherein M is any one of cobalt, rhodium or iridium, and X is an anionic ligand. Wherein X is H, C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₁ -C ₈ alkoxy, C ₆ -C ₁₂ aryl, β-diketonate, cyclopentadienyl, C _{1 to} C ₈ alkylcyclopentadienyl and derivatives in which a halogen group element is added to these materials.

Preferably, the reaction gas includes any one of hydrazine, dimethyl hydrazine, ammonia, NH ₂ R, NHR ₂ , NR ₃ , C _{1 to} C ₁₀ alkyl hydrazine, C _{1 to} C ₁₀ dialkyl hydrazine or a mixture thereof. And R is any one of hydrogen (H), C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₁ -C ₈ alkoxy, C ₆ -C ₁₂ aryl and derivatives in which a halogen element is added to these materials It is characterized by including one.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. .

Hereinafter, a method of forming a Group 9 metal film by atomic layer deposition according to an embodiment of the present invention will be described.

In the present invention, any one of MX or MX ₃ in which the oxidation state of the Group 9 metal (M) is +1 or +3 is used as a precursor, and a highly reducing gas such as hydrazine (Hydrazine; N ₂ H ₄ ) is used as the reaction gas. It provides a method for depositing a Group 9 metal film in atomic layer units using.

Here, hydrazine (N ₂ H ₄ ) is a compound of nitrogen (N) and hydrogen (H), a colorless liquid that smokes in air, has a similar smell to ammonia, has a melting point of 2 ℃, boiling point of 113.5 ℃, and specific gravity of 1.011. .

The precursor of the Group 9 metal and the hydrazine react as follows.

,

Where M is a Group 9 metal (Co, Rh, Ir), and X is an anionic ligand.

In this case, X is H, C ₁ -C ₁₀ Alkyl, C ₂ -C ₁₀ Alkenyl, C ₁ -C ₈ Alkoxy, C ₆ -C ₁₂ Aryl, β- Diketonates, cyclopentadienyl, C ₁ -C ₈ alkylcyclopentadienyl, and derivatives in which a halogen group element is added to these materials.

Referring to [Reaction Scheme 1], hydrazine (N ₂ H ₄ ) reacts with the Group 9 metal precursors (MX, MX ₃ ) to form the Group 9 metal film (M), and highly volatile reaction products (HX, NH). ₃ , N ₂ ). At this time, reaction products including HX are easily removed under vacuum.

In addition to the above hydrazine, as a reducing reaction gas, dimethyl hydrazine (2Me ₂ NNH ₂ ), ammonia (NH ₃ ), NH ₂ R, NHR ₂ , NR ₃ , C ₁ -C ₁₀ alkylhydrazine, C ₁ -C ₁₀ dialkylhydrazine or Any one of these mixed gases, and R is hydrogen (H), C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₁ -C ₈ alkoxy, C ₆ -C ₁₂ aryl and these substances One of the derivatives to which a halogen group element is added is used.

A method of depositing a Group 9 metal film on an atomic layer basis using the above-described principle of Scheme 1 will be described with reference to FIG. 1.

In general, atomic layer deposition (ALD) first supplies a source gas to chemically adsorb a layer of source onto the substrate surface, and extra physically adsorbed sources are purged by flowing a purge gas. The reaction gas is supplied to the source to chemically react one layer of the source and the reaction gas to deposit the desired atomic layer thin film, and the remaining reaction gas is purged by flowing the purge gas in one cycle to deposit the thin film. As described above, in the atomic layer deposition method, not only a stable thin film but also a uniform thin film can be obtained by using a surface reaction mechanism. In addition, since the source gas and the reaction gas are separated from each other and sequentially injected and purged, it is known to suppress particle generation due to gas phase reaction compared to chemical vapor deposition (CVD).

1 is a process flowchart illustrating a method of forming a Group 9 metal film by atomic layer deposition according to an embodiment of the present invention, and FIG. 2 is a flow chart of a Group 9 metal precursor, a reaction gas, and a purge gas according to FIG. 1. 3A to 3C are cross-sectional views illustrating a method of forming a Group 9 metal film by the atomic layer deposition method of FIG. 1.

1 and 3A to 3C, after loading the substrate 11 on which the Group 9 metal film is to be deposited in the reaction chamber, the substrate 11 is preheated to a temperature of 100 ° C. to 900 ° C., and the Group 9 metal. Precursors (MX, MX ₃ ) 12 are supplied onto the heated substrate 11 for 0.1 to 5 seconds and adsorbed onto the substrate 11 surface. Here, reference numeral 12a denotes an adsorbed Group 9 metal precursor.

Subsequently, the supply of the Group 9 metal precursor 12 is stopped and the Group 9 metal precursor 12a adsorbed on the surface of the substrate 11 by supplying nitrogen (N ₂ ), which is a purge gas, for 0.1 to 5 seconds. The unreacted Group 9 metal precursor 12 present in the gaseous state is removed by vacuum.

As shown in FIG. 3B, hydrazine (N ₂ H ₄ ) 13, which is a reaction gas, is supplied for 0.1 seconds to 5 seconds to react with the Group 9 metal precursor 12a adsorbed on the surface of the substrate 11.

As shown in FIG. 3C, the hydrazine and the adsorbed Group 9 metal precursor are reacted by [Scheme 1] to form the atomic layer 14 and the volatile reaction products (HX, NH ₃ , N ₂ ) of the Group 9 metal film. do.

Subsequently, the supply of hydrazine 13 is stopped and nitrogen, which is a purge gas, is supplied again for 0.1 to 5 seconds to remove volatile reaction products and unreacted hydrazine, thereby providing a high purity Group 9 metal atomic layer 14 on the substrate 11. E).

Meanwhile, as the purge gas, helium (He), argon (Ar), ammonia (NH ₃ ), or a mixed gas thereof may be used in addition to nitrogen.

Subsequently, a cycle for continuously supplying the Group 9 metal precursor, the purge gas (nitrogen), the reaction gas (hydrazine), and the purge gas (nitrogen) according to the flowchart of FIG. 2 is set to 1 cycle and the cycle is continuously To form a Group 9 metal film 15 to a desired thickness.

As described above, the present invention minimizes impurities in the Group 9 metal film and suppresses particle generation by using an atomic layer deposition method and a highly reducing reaction gas in manufacturing the Group 9 metal film.

In other words, the reaction by-products of the Group 9 metal precursor and the reaction gas, that is, the volatile reaction products (HX, NH ₃ , N ₂ ) are neutral substances having a high vapor pressure and are not included in the membrane and are easily removed from the reaction chamber by vacuum exhaust. As a result, impurities such as carbon, hydrogen, and oxygen hardly remain.

In addition, the reaction gas and the precursor in the gaseous state during the normal chemical vapor deposition to some chemical reactions to form a non-volatile material, in the present invention, since the deposition reaction is performed only on the substrate surface is not generated particles.

When the above-described atomic layer deposition method is used for capacitor production of semiconductor devices, the reaction gas is prevented from reducing the oxide film formed on the substrate before the Group 9 metal film is formed due to the application of a highly reactive reaction gas.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the present invention has the effect of minimizing impurities remaining in the Group 9 metal film to produce a high purity Group 9 metal film, and by using the atomic layer deposition method, it is possible to deposit at a low temperature and to suppress particle generation. There is.

Claims (9)

In the manufacturing method of a metal film, Loading a substrate into a reaction chamber of an atomic layer deposition apparatus; Adsorbing a Group 9 metal precursor on the substrate; And Supplying a reducing reaction gas into the reaction chamber to induce a reaction with the adsorbed Group 9 metal precursor to form a Group 9 metal film in atomic layer units Forming method of Group 9 metal film by the atomic layer deposition method comprising a. The method of claim 1, The Group 9 metal precursor, Group 9 by atomic layer deposition, wherein any one of MX or MX ₃ having an oxidation state of +1 or +3 is used, wherein M is any one of cobalt, rhodium or iridium, and X is an anionic ligand. Formation method of a metal film. The method of claim 2, X is H, C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₁ -C ₈ alkoxy, C ₆ -C ₁₂ aryl, β-diketonate, cyclopentadienyl, C ₁ -C ₈ A method for forming a Group 9 metal film by atomic layer deposition, comprising any one of alkylcyclopentadienyl and derivatives in which a halogen group element is added to these materials. The method of claim 1, The reaction gas may include any one of hydrazine, dimethyl hydrazine, ammonia, NH ₂ R, NHR ₂ , NR ₃ , C ₁ -C ₁₀ alkylhydrazine, C ₁ -C ₁₀ dialkylhydrazine, or a mixture thereof. Silver hydrogen (H), C ₁ -C ₁₀ alkyl, C ₂ -C ₁₀ alkenyl, C ₁ -C ₈ alkoxy, C ₆ -C ₁₂ aryl and derivatives in which halogenated elements are added to these materials A method of forming a Group 9 metal film by an atomic layer deposition method. The method of claim 1, After adsorbing the Group 9 metal precursor, And stopping the supply of the Group 9 metal precursor and supplying a purge gas to remove the unreacted Group 9 metal precursor. The method of claim 5, The purge gas is nitrogen, helium, argon, ammonia, or a mixed gas of any of these, the method of forming a Group 9 metal film by the atomic layer deposition method. The method of claim 1, After supplying the reaction gas, Discontinuing the supply of the reaction gas and supplying the purge gas again to remove volatile reaction products and unreacted reaction gases from the reaction products of the reaction gas and the adsorbed Group 9 metal precursor. A method of forming a Group 9 metal film by atomic layer deposition. The method of claim 1, And the Group 9 metal precursor and the reaction gas are supplied for 0.1 second to 5 seconds. The method of claim 1, The substrate is heated to a temperature of 100 ℃ to 900 ℃ method of forming a Group 9 metal film by the atomic layer deposition method.