KR100746512B1 - Plasma deposition method and apparatus therefor - Google Patents

Abstract

A plasma deposition method and apparatus therefor are disclosed. First, a solution sample containing a solvent and a metal component is introduced and sprayed. The solvent is removed from the sprayed solution sample and the inductively coupled plasma is applied to the solvent-free metal component under low pressure of 10 torr or less. The metal component powder obtained by decomposition by the applied plasma is allowed to be deposited on the substrate. According to the present invention, vacuum deposition by plasma can be performed using a sample in a solution state. The metal component in the introduced sample can be deposited with good film quality by using ICP under low pressure.

Description

Plasma deposition method and apparatus therefor {Method of Plasma Depositing and Apparatus for Implementing The Same}

1 is a schematic cross-sectional view for explaining a conventional sputtering deposition method.

2 is a flowchart illustrating a plasma deposition method of the present invention.

3 is a block diagram for explaining the plasma deposition apparatus of the present invention.

4 is a partially enlarged cross-sectional view of the plasma deposition apparatus of the present invention.

5 is an enlarged cross-sectional view of a sample introduction tube in the plasma deposition apparatus of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: sample spray device 20: solvent removal device

30: sample introduction tube 40: plasma reactor

50: vacuum deposition chamber

The present invention relates to a plasma deposition method and an apparatus therefor, and more particularly, to a method and apparatus therefor capable of depositing under vacuum by introducing various samples in a solution state.

Since inductively coupled plasma (ICP) has emerged as an atomizer, it has a relatively high temperature compared to the flame device used in the past, and high analytical sensitivity can be obtained by using argon, an inert gas. It is a high sensitivity analyzer with low chemical interference effect, and it has the advantage of simultaneous quantification from main component to trace component because the analysis range from the calibration curve to 10 ⁴ to 10 ⁵ is linear. It has evolved at a very high rate, meeting the requirements as much as possible.

In recent years, the development of analytical instruments has been progressing toward broadening the scope of application of analytical instruments and obtaining better analytical performance through interconnection with other instruments. Since ICP does not have the ability to segregate identification of elemental species, it seeks to expand the scope of analysis by connecting spectrometer and chromatography, which are separate analysis equipment. In addition to ICP-atomic emission spectrometry (ICP-AES) or ICP-mass spectrometry (ICP-MS), which are high performance analytical equipment for elemental analysis in widely used organic solvent samples, for example, ion-exchange chromatography; IC-ICP directly connected to IC), HPLC-ICP connected to high pressure liquid chromatography, and Preconcentration-FIA (flow injection analysis) -ICP, which enables trace element analysis by solvent extraction, are typical. This linkage allows the ICP to detect elemental species and to quantify trace elements by concentration.                         

However, when an aqueous solution or an organic solvent sample is introduced into a low pressure ICP, a highly volatile organic solvent is overloaded with plasma, causing a serious problem of making the plasma unstable and even turning off the plasma, making the analysis impossible. Plasma also produces carbon compounds such as C ₂ , CN, and CO, which can cause severe spectroscopic interference when analyte is detected. As a result, the introduction of a liquid sample causes carbon deposition on the torch and sample cone, which not only destabilizes the plasma but also causes interference, which reduces the analytical performance of the ICP.

Accordingly, the problem of introducing a liquid sample to the ICP must be solved first so that the desired compound can be easily used. As a result, the problem of introducing a liquid sample has been a limiting factor to the application of ICP at atmospheric pressure as well as low pressure ICP, which is a high sensitivity and high performance analytical instrument, and many studies have been attempted to solve the problem.

Recently, a desolvation system has been developed that introduces only the analytes required for analysis into the plasma and removes solvents that are not needed. Representative examples are two systems, cryogenic desolvator and membrane desolvator, both of which show excellent solvent removal efficiency.

egg. s. The cryogenic desolvation system developed by RS Houk et al. Is a device that condenses and removes solvents by repeating heating (at about 40 ° C above the boiling point of the solvent) and cooling (about -80 ° C). . Despite providing excellent solvent removal efficiency and sensitivity, cryogenic desolvation devices are limited in their use due to difficulties in use and complexity of the device, clogging of sample tubes due to solvent condensation, and high maintenance costs.

Methods using membranes have already been widely used in many fields such as bioseparation, medical treatment and the like. Membrane separation is a technique using the characteristic of the membrane to remove only the solvent characteristic by using the difference in the solubility of the substance to be separated into the membrane and the degree of diffusion when passing through the membrane.

Specifically, the method of removing the solvent from the membrane can be divided into two ways. The first is that the solvent molecules are adsorbed-dissolved in the membrane and diffuse-removed by the difference in concentration from the inside of the membrane to the outside. The degree of solvent removal is an important factor in the solubility of the solvent in the membrane. Another method is simply diffusion-passing through the pores of the membrane to remove, where diffusion coefficient is a more important factor. The use of membrane separation devices has the advantage of providing more analyte delivery efficiency and more than 90% solvent removal efficiency. The performance of such a membrane separation device is largely determined by the nature (material) of the membrane and the geometry of the device.

Meanwhile, J. No. 5,259,254 (November 9, 1993) and 5,400,665 (March 28, 1995). J. Zhu et al. Linked PTFE (polytetrahydrofuran) membranes with ultrasonic nebulizers (USNs) to effectively remove polar and nonpolar organic solvents, greatly improving the analytical capabilities of ICP, including reducing baselines and improving detection limits. The results were made. However, the drawbacks of nebulizer USN remain the problems of high sample consumption, large memory effect, sample loss due to the use of long membranes and high cost.

Among the sample introduction methods, a microconcentric nebulizer (MCN) made by modifying a pneumatic nebulizer appeared. MCN is known to have a small effect on the measurement signal of a substance present in the matrix. MCN has been used mainly for ICP-MS because it has advantages in reducing intermolecular spectral interference and minimizing the influence of the matrix. It is expected to be able to make relatively small droplets when spraying the same solvent because they have a relatively small capillary inner diameter than the pneumatic nebulizer. Therefore, the reduction of the large signal value does not occur since the spraying efficiency will be increased.

In recent years, a perfluoroalkoxy teflon (PFA) spraying apparatus capable of spraying finer droplets has been used. Since MCN has the disadvantage of dissolving in HF solution, HF solution can not only overcome the disadvantage that it can not be used, but also is manufactured to spray using fine capillary to make fine droplets with high efficiency. There is this.

As a result, by using an excellent spray equipment, desolvation equipment, etc. in conjunction with the ICP, the solvent sample was introduced to enable analysis by plasma.

On the other hand, deposition using plasma is a technique that is applied in various fields. In particular, in the manufacture of semiconductor devices, various deposition methods have been used for stacking various layers, and representative examples are chemical vapor deposition (CVD) and physical vapor deposition (PVD) processes. .

The CVD process is a technique in which a layer acting as a dielectric or conductor is decomposed into a compound in a gaseous state and then laminated on a substrate by a chemical reaction. In a CVD process, chemicals containing material atoms to be deposited enter the reaction chamber. In the reaction chamber, the gaseous chemical reacts with other gases to produce the desired material and deposit it on the substrate. The CVD process is divided into atmospheric pressure CVD (APCVD), which has an internal pressure of 1 atm, and low pressure CVD (lower pressure CVD) at or below 1 atm, and plasma-enhanced PECVD (plasma) to increase the reaction rate at low temperatures. enhanced CVD). Various thin films such as SiO ₂ , Si ₃ N ₄ , polysilicon, etc. may be formed according to the type and temperature of the gas.

The PVD process, a vacuum deposition method for metal wiring, allows the temperature of a substrate to be freely controlled and is deposited by physical control rather than chemical reaction. The deposition of metal on the substrate is analogous to the evaporation of water from the cup into the air. Increasing the temperature, some water molecules at the water-air interface get enough internal energy to evaporate. Likewise, when a solid is given a sufficient temperature, solid atoms evaporate into the atmosphere. As an external energy supply method for evaporation of a solid, electron beam evaporation deposition and sputtering evaporation deposition are mainly used. Electron beam vacuum deposition is a method of evaporating a material by raising the temperature of the material in a vacuum, and sputtering deposition refers to a target material falling off and being deposited by hitting a target, which is a deposition material, of ions in a plasma.

Figure 1 shows a schematic cross-sectional view of the sputtering method. According to the drawing, in the vacuum chamber 1, the substrate 2 and the target 3, which is a material to be deposited, are provided at the lower and upper portions, respectively. When the RF power source 4 is applied to the target 3, the Ar gas in the vacuum chamber 1 is decomposed by the plasma, and the decomposed powder ions strike and separate the target 3. The sputtered particles 6 are to be deposited on the substrate 2. 5 denotes a shield.

The PVD process is mainly used to obtain metal thin films such as aluminum, and the sputtering method is mainly used during the PVD process for aluminum deposition for integrated circuit wiring.

However, according to the sputtering process, the target material must be provided in the vacuum chamber in a solid state.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma deposition method capable of vacuum deposition by plasma using a sample in a solution state in view of the various techniques described above.

Another object of the present invention is to provide a plasma deposition method capable of forming by plasma using a sample in a solution state.

It is still another object of the present invention to provide a plasma deposition apparatus capable of introducing a sample in a solution state and capable of depositing a target material in the introduced sample with good film quality by using ICP under low pressure.

In order to achieve the above object, in the present invention

Introducing a solution sample comprising a solvent and a metal component;                     

Spraying the solution sample;

Removing solvent from the sprayed solution sample;

Applying an inductively coupled plasma to the solvent-free metal component under a low pressure of 10 torr or less; And

It provides a plasma deposition method comprising the step of depositing a metal component powder obtained by decomposition by the applied plasma on a substrate.

As the solvent, almost all water-soluble liquids and organic solvents including water, isopropyl alcohol, sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid and the like can be used.

In particular, the removal of the solvent is preferably performed using a solvent removal apparatus using a membrane, more preferably using a double membrane desolvator (DMD) including a double membrane consisting of an inner membrane and an outer membrane. It is preferable to carry out. In addition, the analyte from which the solvent has been removed is preferably transported along the center of the cooling gas to be transported while forming a tangential flow with respect to the traveling direction.

In order to achieve the above object of the present invention, in the present invention

Introducing a solution sample comprising a solvent and a molding material;

Spraying the solution sample;                     

Removing solvent from the sprayed solution sample;

Applying an inductively coupled plasma at a low pressure of 10 torr or less to the molding material from which the solvent has been removed; And

It provides a plasma deposition method comprising the step of depositing a powder of the molding material obtained by decomposition by the applied plasma on a predetermined target.

As the solvent, almost all water-soluble liquids and organic solvents including water, isopropyl alcohol, sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid and the like can be used. As the metal component, all components applicable to a state in which a transition metal element including aluminum, titanium, magnesium, zinc, strontium, rare earth metals such as europium and samarium, as well as a halogen element are applicable and dissolved in a soluble solvent. This is possible.

According to this method, if a metal component as well as a non-metallic component is introduced and deposited on a target, it becomes possible to fabricate a predetermined shape using a desired material.

Another object of the present invention described above

An injection tube for introducing a solution sample containing a solvent and a metal component;

A spraying device for spraying the solution sample;

A solvent removal device for removing the solvent from the sprayed solution sample;

A vacuum pump for applying a low pressure of 10 torr or less to the solvent-free metal component;

A plasma reactor for applying inductively coupled plasma under low pressure; And

It is achieved by a plasma deposition apparatus including a vacuum deposition chamber for depositing a metal component powder obtained by decomposition by the applied plasma on a substrate.

In the present invention, by introducing a solvent removal device and low-pressure low-temperature ICP for plasma deposition, it provides a plasma deposition method that can easily deposit various components contained in the sample in a solution state.

When the plasma is produced at low pressure, the plasma is in a non-local thermodynamic equilibrium (non-LTE) state because the electron temperature is much higher than the temperature of the gas. The gas temperature at this time is called cold plasma because it is much lower than the electron temperature compared to atmospheric pressure inductively coupled plasma.

ICPs operating under atmospheric pressure are interfered with by the components contained in the atmosphere. On the contrary, when the low pressure low temperature ICP is used, there are advantages such as reduction of polyatomic interference due to external air blocking, low power, reduction of gas consumption, and easy ignition.

At low pressures, however, the plasma temperature decreases, and the density of electrons and heavy particles is very sensitive to environmental changes. In particular, when a liquid sample is directly introduced, the problem that the plasma is turned off due to overloading even a small amount of the solvent is a major disadvantage of the low temperature ICP. In the present invention, in order to solve the above problems, while introducing a liquid sample in order to achieve the advantages of low-temperature low-temperature plasma ten minutes, try to introduce a low-pressure plasma after removing the solvent in the sample to the maximum, through which easy plasma deposition It is.

Hereinafter, the plasma deposition method according to the present invention will be described in detail with reference to FIG. 2. 2 is a flowchart illustrating a plasma deposition method according to the present invention.

First, a liquid sample obtained by dissolving a target material to be deposited in an appropriate solvent is introduced (S1). For example, a sample solution is prepared by dissolving a deposition material such as aluminum, titanium, magnesium, zinc, lead, strontium, and the like in a solvent such as water, isopropyl alcohol, sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, phosphoric acid, and the like. It is intended to be introduced into a plasma deposition system to deposit metal components. Introduction of the sample is mainly continuous.

In order to make the introduced liquid sample into a small droplet capable of removing the solvent, a small aerosol droplet is sprayed using a predetermined spraying device (S2).

The solvent is removed from the sprayed aerosol droplets to leave only the metal component (S3). All known solvent removal methods may be used for the removal of the solvent, and preferably, the removal of the solvent is performed by adsorption-dissolution-evaporation by the membrane.

Inductively coupled plasma is applied to the analyte from which the solvent is removed under low pressure (S4). Preferably, the pressure should be about 10 torr or less, so that the plasma is produced in a nearly vacuum state.                     

Under low pressure, the metal component is decomposed into radicals, ions, etc. by an applied plasma, and vacuum deposition is performed by depositing it on a substrate (S5).

According to the method of the present invention as described above, it is possible to introduce the sample in a liquid state, and after removing the solvent from the introduced sample, the inductively coupled plasma is applied under low pressure to reduce polyatomic interference due to external air blocking. The advantages of using low power can be obtained.

Hereinafter, a preferred plasma deposition apparatus capable of performing the plasma deposition method will be described in detail.

3 is a block diagram illustrating a plasma deposition apparatus according to an embodiment of the present invention. The apparatus includes a sample spraying device 10 for making a large aerosol droplet into a small aerosol droplet, a solvent removing apparatus 20 for removing solvent from the sprayed aerosol droplet and leaving only the metal component, and the remaining metal component Sample introduction tube 30 for transferring the vacuum deposition chamber 50 for maintaining the plasma reactor 40 and the plasma reactor 40 for applying a plasma to the introduced sample at a low pressure and at the same time a vacuum deposition process is performed (50) ) The plasma reactor 40 is provided with a material flow control device 46 for regulating the flow of material, a matching box 42 and an RF oscillator 44 for applying power to the coil, and the plasma reactor 40 The vacuum chamber 50 connected to) is provided with a vacuum pump, a vacuum gauge 52, and a pressure control valve 54.

In particular, in the present invention, a new apparatus is manufactured and used for the application of the low pressure low temperature ICP. In FIG. And an enlarged cross-sectional view of the vacuum deposition chamber portion.

When the solvent is removed by the solvent removing device 20 and introduced into the center along the sample introduction pipe 30 in the direction of the metal component A from which the solvent is removed, the cooling gas B injected from the outside is injected along the inside of the external pipe 33. . This is plasmaated as the coil for application of power passes inside the wound plasma reactor 40, in which the environment is at a low pressure of about 10 torr or less by the vacuum deposition chamber 50 continuously installed. The vacuum deposition chamber 50 is provided with a pressure gauge 55 and a vacuum pump 57.

Metal powder 54 broken into various ions, radicals and the like by an applied inductively coupled plasma is deposited on a substrate 52 which is installed at the load core of the vacuum deposition chamber 50 and fixed by the holder 52. The heater 51 is connected to the holder to heat the sputtered powder to be easily deposited on the substrate.

FIG. 5 is an enlarged cross-sectional view of a sample introduction tube in the vacuum deposition apparatus shown in FIG. 4. The solvent-free metal component is introduced into the plasma reactor 40 along the sample introduction tube 30, and the sample introduction tube 30 is an inner tube 31 for transferring the metal component from which the solvent has been removed. And a double tube of the outer tube 33 which is manufactured to receive the inner tube 31 and transfers the cooling gas flowing while forming a vertical flow therebetween.

Referring to the structure of the sample introduction pipe 30 in more detail as follows. It consists of a double tube of the inner tube 31 and the outer tube 33, so that the solvent-free metal component is moved along the inner space 32 of the inner tube 31. A cooling gas such as Ar is transferred to the space 34 formed between the inner tube 31 and the outer tube 33, which is preferably performed while forming a vertical flow that rotates in a direction perpendicular to the conveying direction. Do. To this end, the cooling gas introduction pipe 35 is installed at a position biased to one side while being perpendicular to the sample introduction pipe as shown in the drawing. Eventually, the cooling gas introduced along the cooling gas introduction pipe 35 proceeds around the analyte in the center but forms a vertical flow, so that the metal component of the center is injected into the reactor 40. In the center of the easy to receive plasma is to be applied. The sample introduction tube is preferably made of quartz or ceramic.

Other apparatuses used in the plasma deposition apparatus of the present invention include a spray apparatus for making a small sample of a solution state, which is not limited to a particular apparatus, it is possible to use all known apparatus. However, preferably, a perfluoroalkoxy teflon (PFA) sprayer, a microconcentric nebulizer (MCN), an ultrasonic nebulizer (USN), or a Meinhard type Pneumatic sprayer is used, and recently, a PFA sprayer capable of forming very fine droplets without being dissolved in an HF solution is used. Is used a lot.

In addition, as the solvent removal apparatus for removing the solvent from the liquid sample introduced into the ICP, any known solvent removal apparatus including a double membrane desolvator (DMD) apparatus is applicable. DMD devices, however, are efficient solvent removal devices that allow the introduction of aerosol sprayed between membranes so that the solvent gas is removed from the membrane and only metal components are introduced into the plasma. The DMD device is designed to remove solvent by an inner flow gas (Ar) flowing along the inside of the inner tube and an outer flow gas (Ar) flowing in the opposite direction to the inner flow gas along the outside of the outer tube. The aerosol produced by the spray device runs between the inner and outer tubes. The solvent is removed by diffusion through the pores of the membrane and only dry particles are injected into the plasma. Such a DMD device is shown in detail in Korean Patent Application No. 98-50024 filed on November 20, 1998.

The solvent is removed while passing through the solvent removal apparatus, and only the remaining metal component is injected into the plasma reactor 40 through the sample introduction tube 30. When inductively coupled plasma is produced by the applied RF power, the metal component is plasmalated and injected into the vacuum chamber 50 together with the Ar cooling gas. The injected metal component is deposited on the substrate 53 provided under the vacuum chamber 50. At this time, when the substrate 53 is heated to a predetermined temperature by using the heater 51, the sputtered powder is uniformly and easily attached on the substrate to form a thin film. For example, in the case of aluminum, when the wafer is heated to a temperature of about 700 ~ 800 ℃ it was confirmed that the deposition is easy.

According to this method, plasma deposition is possible by introducing a sample in a solution state, so that a trace component can be introduced. For example, since rare earth metals such as Eu and Sm are very expensive, it is difficult to sputter using pure metal lumps, but according to the method of the present invention, it is possible to manufacture and introduce only a small amount of the solution to be deposited so that a small amount of deposition is possible. Done.

In addition, according to the experiments of the present inventors, when the CH ₄ gas is injected during the injection of the solution in which the metal component is dissolved, it was confirmed that carbides of the metal were deposited on the substrate. Therefore, it is also possible to easily deposit various components by introducing a combination of a solution of a metal component and a gas as appropriate.

According to the present invention as described above it is possible to deposit a variety of materials including a metal component on the target using a sample in a solution state to be able to deposit a small amount of the various components.

In addition, the conventional low pressure plasma had a problem that the plasma is turned off when the solution is directly introduced, but in the present invention, by introducing a solution spraying device, it is possible to introduce a solution sample from 5 µl / min to about 1 ml / min. It became. According to this, the spraying efficiency is almost 100%, and in such a state, the membrane can be used to completely evaporate the solvent and produce dry fine particles. Even if the sprayed particles are too large, the deposited state may be rough, so that the quality of the obtained product may be degraded. However, according to the present invention, a fine sample may be introduced, thereby obtaining a good quality product.

Although the present invention has been described above according to an embodiment of the present invention, it will be apparent to those skilled in the art that various modifications may be made without departing from the spirit of the present invention.

Claims (17)

Introducing a solution sample comprising a solvent and a metal component; Spraying the solution sample; Removing solvent from the sprayed solution sample; Applying an inductively coupled plasma to the solvent-free metal component under a low pressure of 10 torr or less; And And depositing a metal component powder obtained by decomposition by said applied plasma on a substrate. The method of claim 1, wherein the solvent is at least one selected from the group consisting of water, isopropyl alcohol, sulfuric acid, phosphoric acid, nitric acid, hydrofluoric acid, and hydrochloric acid. The method of claim 1, wherein the metal component is at least one selected from the group consisting of aluminum, titanium, magnesium, zinc, strontium, lead, europium, and samarium. The method of claim 1, wherein the removal of the solvent is carried out using a solvent removal apparatus using a film. The plasma deposition method of claim 1, wherein the removal of the solvent is performed using a double membrane desolvator (DMD) including a double membrane composed of an inner membrane and an outer membrane. 6. The plasma deposition method of claim 5, wherein the solvent-free metal component is transported along a central portion of the cooling gas that is transported while forming a tangential flow with respect to the traveling direction. The method of claim 1, wherein the substrate is a substrate for the manufacture of a semiconductor device (semiconductor device). Introducing a solution sample comprising a solvent and a molding material; Spraying the solution sample; Removing solvent from the sprayed solution sample; Applying an inductively coupled plasma at a low pressure of 10 torr or less to the molding material from which the solvent has been removed; And And depositing powder of the molding material obtained by decomposition by the applied plasma on a predetermined target. The plasma deposition method of claim 8, wherein the solvent is at least one selected from the group consisting of water, isopropyl alcohol, sulfuric acid, phosphoric acid, nitric acid, hydrofluoric acid, and hydrochloric acid. delete An injection tube for introducing a solution sample containing a solvent and a metal component; A spraying device for spraying the solution sample; A solvent removal device for removing the solvent from the sprayed solution sample; A vacuum pump for applying a low pressure of 10 torr or less to the solvent-free metal component; A plasma reactor for applying inductively coupled plasma under low pressure; And And a vacuum deposition chamber for depositing the metal component powder obtained by decomposition by said applied plasma onto a substrate. The apparatus of claim 11, wherein the spray device is a perfluoroalkoxy teflon (PFA) sprayer, a microconcentric nebulizer (MCN), an ultrasonic nebulizer (USN), or a Meinhard type Pneumatic nebulizer. The apparatus of claim 11, wherein the solvent removal apparatus is a double membrane desolvator (DMD). The method of claim 11, wherein the solvent-free metal component is introduced into the plasma reactor along the metal component introduction tube, the metal component introduction tube is an inner tube for transferring the metal component from which the solvent is removed; A sample which is manufactured to receive the inner tube and comprises a double tube of an outer tube for conveying a cooling gas flowing while forming a tangential flow with respect to the longitudinal direction of the inner tube between the inner tube and the inner tube. Detection device. The sample detection apparatus according to claim 14, wherein the metal component sample introduction tube is made of quartz or ceramic. 12. The sample detection apparatus according to claim 11, wherein the vacuum deposition chamber is further provided with a pressure control valve. 12. The sample detection apparatus according to claim 11, wherein the substrate provided in the vacuum deposition chamber is further provided with a heater.

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