KR100633333B1 - Composition Calculation Method for Multi Component Thin Film by Atomic Layer Deposition - Google Patents

Abstract

To provide a method for estimating the composition of a multi-component thin film to be formed by monoatomic deposition in a non-destructive manner, the present invention provides a thin film growth rate per unit cycle (Cycle) of the component layer constituting the thin film and It is to measure the density of the thin film, calculate the thickness factor (R) and the concentration factor (C) through this, and then calculate the composition ratio of the final multicomponent thin film as the component element. . The composition ratio is calculated by considering the concentration factor (C) after converting from the initial source gas feeding rate (m: n) to the thickness ratio (Thickness Ratio) using the thickness factor (R). Using the composition estimation method of the present invention, it is possible to accurately and nondestructively predict the composition of a multicomponent thin film, and to accurately design the Hf / Al feeding rate (m: n) necessary to form a thin film having a desired composition.

 Monolithic vapor deposition, composition, thickness, concentration

Description

Composition Calculation Method for Multi Component Thin Film by Atomic Layer Deposition

1 is a graph of experimental results for obtaining the growth rate (ie, thickness factor) of HfO ₂ and Al ₂ O ₃ .

2 shows the composition ratio calculated from the initial Hf / Al source feeding rate (m: n) to the thickness ratio (T) using the thickness factor (R) and finally considering the concentration factor (C). Chart showing results.

3 is a chart comparing the composition ratio of Hf / Al calculated by the present invention with the actual ICP-MS method.

4 is a graph of FIG. 3.

The present invention relates to a method for accurately calculating and controlling the relative composition ratio of atoms constituting a thin film through experiments when forming a multi-component thin film by atomic layer deposition.

Recently, dielectric and gate insulating films of DRAM devices have been formed by atomic layer deposition (ALD). This is because compared with the conventional chemical vapor deposition (CVD: Chemical Vapor Deposition) is excellent in the step (conformality) and the characteristics of the thin film in the low temperature process.

Recently, in order to improve the properties of thin films, in addition to conventional oxide or nitride thin films of HfO ₂ , Al ₂ O ₃ or TiN, Hf _x Al _y O _z , Al mixed with two or more atoms to improve their performance Thin-film dielectrics such as _x Ta _y O _z , Al _x Zr _y O _z , and SrTiO ₃ are being researched and developed.

However, since the properties of these thin films are highly dependent on the composition of the constituent elements constituting the thin film, it is very important to predict and adjust the composition of the thin film reliably.

However, there is currently no method for nondestructively predicting and controlling the composition of multicomponent thin films formed by monoatomic deposition. That is, conventionally, an out-line composition analysis method using a destructive analysis method such as ICP-MS or RBS has been proposed, and there is no method for predicting and controlling the composition of a thin film through experimental techniques.

It is an object of the present invention to provide a method for estimating the composition ratio between atoms of a multicomponent thin film to be formed by monoatomic deposition in a non-destructive manner.

The basic principle of the present invention is to measure the film growth rate and film density per unit cycle of the component layers constituting the thin film, and propose a thickness factor (R) as a method of proposing the same. And the concentration factor (C), and then calculate the composition ratio between atoms of the final multicomponent thin film as the component element.

The present invention is carried out a feeding sequence of the source gas of A, purge gas, reaction gas of D, purge gas m times (an integer of m ≥ 1), the source gas of B, purge gas, reaction gas of D, purge Deposition is carried out by monoatomic deposition (ALD) in which the feeding cycle of the gas is performed n times (an integer of n≥1) as a unit cycle, and element A (A is Al, Hf, Zr, Nb, Ta, La, Ti, Dy, Pr, Sr, Ba and Bi) any one selected from the group of A, and B element (B is any one selected from the group except the A component), A _x B _y D A method for estimating the composition ratio of B / A for a _z (D includes O or N) dielectric film,
Fixing the n to a predetermined integer value and performing the unit cycle while changing the value of m to form a plurality of first thin film samples having different compositions of A to B;
Obtaining a thickness factor (R _AD ) for the first thin film by calculating a slope of the change in thickness of the plurality of first thin film samples;
Fixing the m to a predetermined integer value and performing the unit cycle while changing the value of n to form a plurality of second thin film samples having different compositions of B to A;
Obtaining a thickness factor (R _AD ) for the second thin film by calculating a slope of the change in thickness of the plurality of second thin film samples;
Forming an AD thin film by repeatedly performing a feeding sequence of a source gas, a purge gas, a reaction gas of D, and a purge gas, and measuring the density (ρ _AD ) of the AD thin film;
Forming a BD thin film by repeatedly performing a feeding sequence of a source gas, a purge gas, a reaction gas of D, and a purge gas of B, and measuring a density ρ _BD of the BD thin film;
Obtaining a concentration factor (C) by Equation 1 below; And
Obtaining the composition ratio of B / A by the following equation
It provides a method for estimating the composition of a non-destructive multi-component dielectric comprising a.

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C = N _B / N _A
N _A = a × ρ _AD / M _AD
N _B = b × ρ _BD / M _BD
(Where M _AD is the molecular weight of the AD thin film, M _BD is the molecular weight of the BD thin film, a is the atomic ratio value of A in the thin film AD, b is the atomic ratio value of B in the thin film BD)

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m × R _AD : n × R _BD × C

In the present invention, a transmission electron microscope (TEM) or X-ray reflection method (TEM) is used as a method for measuring the thicknesses of the first thin films and the second thin films, and the density of the AD thin film. As a method for measuring (ρ _AD ) and the density (ρ _BD ) of the BD thin film, an X-ray reflection method is used.

In addition, when the reaction gas is any one selected from the group of O ₃ , H ₂ O and O ₂ plasma, a multicomponent oxide is obtained, and the reaction gas is N ₂ or NH ₃ or a plasma thereof. Component-based nitrides can be obtained. As the purge gas, Ar or N ₂ gas is used, and the reaction chamber is vacuum pumped when purging.

DETAILED DESCRIPTION Hereinafter, the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention.

This embodiment is a dielectric using Al ₂ O ₃ and HfO ₂ together, and is a monolayer of [Al ₂ O ₃ ] _x [HfO ₂ ] _(1-x) thin film in which Al ₂ O ₃ and HfO ₂ are uniformly mixed. Shows how to estimate the composition ratio of each component when forming by evaporation

The basic unit cycle for forming the [Al ₂ O ₃ ] _x [HfO ₂ ] _(1-x) dielectric is as follows. That is, the feeding sequence of Al source gas, purge gas (such as Ar or N ₂ ), oxidation reaction gas (such as O ₂ ), and purge gas supply is performed m times (an integer of m≥1), and Hf The unit cycle is constituted by performing n times (an integer of n ≧ 1) in the feeding order of the source gas, the purge gas, the oxidizing reaction gas, and the purge gas. This unit cycle is repeated to obtain a thin film of a desired thickness.

(Step 1)

1 is a graph of experimental results for obtaining growth rates (ie, thickness factors) of HfO ₂ and Al ₂ O ₃ .

Performing the unit cycle described above, while forming a plurality of first thin film samples having different compositions of Al for Hf while fixing n to 1 and changing the value of m to 1, 2, 3, 4, By calculating the slope by graphing the thickness change for the thin film samples, the thickness factor R _Al2o3 can be obtained, resulting in "R _Al2o3 = 1.13".

In addition, a plurality of second thin film samples having different composition of Hf for Al while performing the unit cycle described above, fixing m to 1 and changing the value of n to 1, 2, 3, 4, 5, 6 After forming, and calculating the slope for the thickness change for the plurality of second thin film samples, the thickness factor R _HfO2 can be obtained, which is "R _HfO2 = 0.82".

In this experiment, the oxidation reaction gas was H ₂ O. The thickness measurement of the first and second thin films is possible by a method such as TEM.

The thickness factor R is a measure of the degree to which the component layer contributes in thickness to the formation of the final thin film per source feeding cycle.

On the other hand, the growth rate of HfO ₂ and Al ₂ O ₃ is not obtained from a single HfO ₂ thin film or a single Al ₂ O ₃ thin film, so that m and n are very small when forming an actual Hf _x Al _y O _z thin film. Since the adsorption reaction of the source is performed in the transition cycle region, it is intended to reflect the source adsorption and oxidation reaction as much as possible in the real situation.

(Step 2)

After obtaining the thickness factor as described above, the thin film density of each component layer was measured, and the Al ₂ O ₃ was repeated a plurality of times by feeding the Al source gas, purge gas, oxidation reaction gas, and purge gas. A thin film is formed and the density ρ _Al2O3 of the Al ₂ O ₃ thin film is measured. And to form a HfO ₂ thin film by performing the feeding order of the source gas of Hf, purge gas, oxidation gas, the purge gas a plurality of times repeatedly, measure the density ρ HfO ₂ thin film _HfO2.

The density of a thin film is inherent in ALD depending on the deposition method, the precursor used, the oxide, the deposition temperature, and the like. The density of the thin film is determined by the number of atoms of Hf or Al in the thin film per unit volume. Can give information The density of the thin film is possible by measuring the reflectivity using X-Ray.

When HfO ₂ and Al ₂ O ₃ are formed using H ₂ O as an oxidation source, the thin film density is as follows.

HfO ₂ : 9.16 g / cm 3

Al ₂ O ₃ : 3.23 g / cm 3

(Step 3)

Next, the concentration factor (C) is obtained by the following equation (3), and the composition is obtained by the following equation (4). This is explained in detail.

From the two thickness factors extracted, it is possible to convert m: n, which is the initial feeding ratio of Hf and Al, to a thickness ratio (m × R _Al2o3 : n × R _HfO2 ).

In addition, the concentration factor (C) is defined as in Equation 3 below to extract the degree of contribution of the number of atoms that the component layer per unit volume or per unit thickness contributes to the final thin film in the source feeding rate.

C = N _HF / N _Al

N _Al = a (2) × ρ _Al2O3 / M _Al2O3

N _Hf = b (1) × ρ _HfO2 / M _HfO2

(Where, M _Al2O3 is the molecular weight, the Al ₂ O ₃ thin film M _HfO2 has a molecular weight of HfO ₂ thin film a thin film Al _{a (2)} Al atomic ratio values in the O ₃ (i.e. 2), b is thin Hf _{b (1)} Hf atomic ratio value at O ₂ (ie 1)

Through this defined concentration factor, the final composition ratio of Hf / Al in the thin film can be converted to Equation 4 below.

m × R _Al2o3 : n × R _HfO2 × C

As described above, after converting from the initial Hf / Al source feeding rate (m: n) to the thickness ratio (Thickness Ratio) using the thickness factor (R), finally considering the concentration factor (C), Hf / The composition ratio of Al can be calculated. 2 is a table showing the results.

3 is a chart comparing the composition ratio of Hf / Al calculated by the present invention with the actual ICP-MS method, and FIG. 4 will graph the resulting value. As can be seen from Figures 3 and 4 it can be seen that the calculated value and the actual analysis value is very well matched.

Using the composition estimation method of the present invention, it is possible to accurately and non-destructively predict the composition ratio of source atoms in a multicomponent thin film, and to accurately design the Hf / Al feeding rate (m: n) required to form a thin film having a desired composition. It is possible.

This embodiment has been described for the [Al ₂ O ₃ ] _x [HfO ₂ ] _(1-x) dielectric, but also Al _x ZrO _z , Hf _x Si _y O _z , Al _x Ta _y O _z It is also applicable to accurately predict and control the composition of thin films.

As such, although the technical idea of the present invention has been described in detail according to the above-described 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.

Using the composition estimation method in the present invention, it is possible to accurately and non-destructively predict the composition of the multicomponent thin film, and to accurately design the source gas feeding rate (m: n) necessary to form a thin film having a desired composition.

As a result, it is possible to greatly improve the reliability of the dielectric of the DRAM capacitor and the gate dielectric.

Claims (6)

The feeding sequence of the source gas of A, purge gas, reaction gas of D, and purge gas is performed m times (an integer of m≥1), and the feeding sequence of source gas, purge gas of D, reaction gas of D, and purge gas Is deposited by monoatomic deposition (ALD) in which unit cycles are performed n times (which is an integer of n≥1), and element A (A is Al, Hf, Zr, Nb, Ta, La, Ti, Dy, A _x B _y D _z (where D is any one selected from the group of Pr, Sr, Ba, and Bi) and element B (B is any one selected from the group excluding the A component) In the method for estimating the composition ratio of B / A to the dielectric thin film) Fixing the n to a predetermined integer value and performing the unit cycle while changing the value of m to form a plurality of first thin film samples having different compositions of A to B; Obtaining a thickness factor (R _AD ) for the first thin film by calculating a slope of the change in thickness of the plurality of first thin film samples; Fixing the m to a predetermined integer value and performing the unit cycle while changing the value of n to form a plurality of second thin film samples having different compositions of B to A; Obtaining a thickness factor (R _AD ) for the second thin film by calculating a slope of the change in thickness of the plurality of second thin film samples; Forming an AD thin film by repeatedly performing a feeding sequence of a source gas, a purge gas, a reaction gas of D, and a purge gas, and measuring the density (ρ _AD ) of the AD thin film; Forming a BD thin film by repeatedly performing a feeding sequence of a source gas, a purge gas, a reaction gas of D, and a purge gas of B, and measuring a density ρ _BD of the BD thin film; Obtaining a concentration factor (C) by Equation 1 below; And Obtaining the composition ratio of B / A by the following formula 2 Composition estimating method of a non-destructive multi-component dielectric comprising a. (Eq. 1) C = N _B / N _A N _A = a × ρ _AD / M _AD N _B = b × ρ _BD / M _BD (Where M _AD is the molecular weight of the AD thin film, M _BD is the molecular weight of the BD thin film, a is the atomic ratio value of A in the thin film AD, b is the atomic ratio value of B in the thin film BD) (Eq. 2) m × R _AD : n × R _BD × C The method of claim 1, Estimation of the composition of the non-destructive multicomponent dielectric using a transmission electron microscope (TEM) or an X-ray reflection method (TEM) as a method for measuring the thicknesses of the first thin films and the second thin films Way. The method of claim 1, A method for estimating the density (ρ _AD ) of the AD thin film and the density (ρ _BD ) of the BD thin film, the method of estimating the composition of a non-destructive multi-component dielectric, characterized in that the X-ray reflection method. The method of claim 1, The reaction gas of D is any one selected from the group of O ₃ , H ₂ O and O ₂ plasma composition estimation method of the non-destructive multi-component dielectric. The method of claim 1, The method of estimating the composition of the non-destructive multi-component dielectric, characterized in that the reaction gas of D is N ₂ or NH ₃ or plasma thereof. The method of claim 1, The purge gas is Ar or N ₂ gas, the method of estimating the composition of the non-destructive multi-component dielectric, characterized in that for pumping the reaction chamber when the purge gas is supplied.

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