KR20140041651A - Apparatus and method for thin films fabrication using multi-step pulse - Google Patents

Abstract

The present invention relates to an apparatus and a method for forming a thin film using a multi-stage pulse technology. The thin film forming apparatus according to the present invention includes: a vacuum reactor in which a sputter to which a multi-stage pulse voltage is applied is installed, for generating plasma through plasma discharging; a target for guiding plasma ions generated by the plasma discharging to generate solid elements in the vacuum reactor through sputtering; a magnetron unit for applying a magnetic field to the inside the vacuum reactor through the target; and a multi-stage power application unit for applying a negative voltage and a positive voltage which correspond to the multi-stage pulse voltage to the target. [Reference numerals] (130) Multi-stage power application unit

Description

Apparatus and method for thin films fabrication using multi-step pulse}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus using a multi-step pulse technique and a method of forming the same. More specifically, in a sputter using a multi-step pulse, a positive bias voltage, which is a second bias voltage among multi-step pulse voltages, is applied to a sputter target. The present invention relates to a thin film forming apparatus and a thin film forming method using the same, by which afterglow ions are incident on a substrate in the form of an ion beam and act as an additional energy source, thereby improving the quality or characteristics of the thin film.

In general, in the PVD process used in the thin film process, a thin film process is performed using various methods such as evaporation, DC or RF sputtering, DC or RF magnetron sputtering, and ion plating. Among them, the sputtering method is a method of depositing a thin film by using the principle that the particles with high energy collide with the target and release the target atoms.The thin film can be deposited on various materials (metals, compounds, insulators, etc.) It can be produced and widely used.

At this time, the stuttering is a DC or RF power supply method according to the power supply method applied to the sputter. The DC power supply method uses a target made of a conductor material and is the most standard method with a simple structure and a high film formation speed. In addition, the RF power source is capable of using an insulator or dielectric as well as a conductor, and can operate at low pressure.

In the general sputtering method, there is an advantage of increasing plasma density by trapping electrons in a magnetic field formed by installing a permanent magnet or an electromagnet on the back of the target, thereby increasing the sputter yield of the target.

On the other hand, in the thin film processing method other than the sputtering method, the ion plating method evaporates a source to be deposited using heat or an electron beam, and then ionizes the vaporized deposition atoms or molecules by using a plasma in the chamber. The ionized evaporated particles are incident with energy corresponding to the negative potential applied to the substrate to which the negative potential is applied.

In addition, the thin film by the evaporated particles incident with a higher energy than the evaporated particles having a general thermal energy forms a thin film having a dense and excellent physical properties due to the transfer of energy and momentum to the surface of the thin film. However, ion plating may cause defects due to the physical collision of thin films due to the addition of additional plasma generation methods and high energy incidence.

The ions incident on the substrate during thin film deposition depend on the morphology, composition, orientation, and mechanical properties of the thin film, depending on the energy, density, and relative mass ratio of ions to the substrate atoms. ) And so on. If the voltage of the substrate is too high, bonding occurs in the thin film, leading to an increase in the stress state, which may lower the adhesion and the quality of the film. In addition, the temperature and negative potential applied to the substrate affects the density of tissues that affect wear resistance and corrosion resistance, such as the formation of voids in the thin film.

As a method of controlling the incidence of such ions, a method of applying a negative potential to the substrate may be used. Negative potential was applied to the substrate to control the energy of ions incident on the substrate during the thin film process, and to observe the crystallinity change due to the collision between the incident ions and the substrate. (Ref.Jianliang Lin Moore, JJ Sproul, WD Lee, SL Jun Wang, "Effect of Negative Substrate Bias on the Structure and Properties of Ta Coatings Deposited Using Modulated Pulse Power Magnetron Sputtering", Plasma Science, 38, 3071-3078, 2010)

In addition, the sputtered solid element was passed through a plasma, and ionized and ionized solid ions were incident on the substrate by the potential applied to the substrate, and the characteristics of the thin film were also observed. (Ref. Fengjuan Jing, Yukimura, K., Hara, S., Nakano, S., Ogiso, H., Han Huang, "High-Power Pulsed Magnetron Sputtering Glow Plasma in Argon Gas and Pulsed Ion Extraction", Plasma Science, 38, 3016-3027, 2010)

However, the incidence of ions that change the properties of the thin film requires the addition of an additional plasma generation method and an additional power supply configuration for applying a voltage to the substrate.

Republic of Korea Patent No. 10-0716258

Accordingly, the present invention was devised to solve the above-mentioned disadvantages and problems in the conventional thin film forming apparatus and method, and the second bias voltage among the multi-stage pulse voltages in the sputter target in the sputter using multi-stage pulses. Thin film forming apparatus using multi-stage pulse technology that improves the quality and characteristics of thin film by applying a positive bias voltage and applying afterglow ions to the substrate in the form of an ion beam and acting as an additional energy source. An object of the present invention is to provide a method for forming a thin film.

The above object of the present invention is a vacuum reactor for generating a plasma by a plasma discharge is provided with a sputter to which a multi-stage pulse voltage is applied; A target for inducing plasma ions generated by the plasma discharge to generate solid element cations by sputtering in the vacuum reactor; A magnetron unit for applying a magnetic field in the vacuum reactor across the target; And a multi-stage power supply unit for applying a positive voltage which is a second bias voltage among the multi-stage pulse voltages to the target.

In the thin film forming apparatus of the present invention, when sputtering is generated in the vacuum reactor, a multi-stage pulse voltage may be applied to the target, and the plasma may be generated by applying a first bias voltage (negative voltage) of the multi-stage pulse voltage. Sputtering occurs by inducing ions, and a second bias voltage (positive voltage) of a multi-stage pulse voltage is applied to inject gas into which ion ionized by plasma and sputtered atoms pass through the plasma to push out ionized cations. Ion beams can be generated.

In addition, it is preferable that the first bias voltage is a negative bias voltage, and the second bias voltage is applied with a positive bias voltage.

The target is a material to be deposited on a substrate, that is, carbon (C), silicon (Si), copper (Cu), gold (Au), aluminum (Al), titanium (Ti), chromium (Cr), platinum (Pt) It is preferably formed of an element to be deposited on the surface of the substrate, such as any one element or compound, such as aluminum oxide (Al ₂ O ₃ ) and indium tin-oxide (ITO).

The multi-stage power supply unit may be configured as a power supply to which a negative voltage capable of regulating voltage for sputtering and a positive voltage capable of regulating voltage of cation are modulated and applied.

The magnetron unit applies a magnetic field to the outside of the target across the target which is a general magnetron sputter unit or target, and the center pole and the side pole surrounding the center pole may have a racetrack arrangement. It can also be implemented in a sputtered structure without a magnet unit.

Among the multi-stage pulse voltage, an afterglow cation generated according to the magnitude, period, and duty period of the negative voltage and the positive voltage applied to the sputter is incident on the substrate to improve the characteristics of the thin film.

As described above, in the thin film forming apparatus and the thin film forming method using the multi-step pulse technology according to the present invention, the afterglow ions are incident on the substrate in the form of an ion beam to act as an additional energy source, thereby improving the quality and characteristics of the thin film. There is an advantage to improve. In the sputtering method using a pulse reported in the past, the effect of the cation due to the overshooting voltage at the initial stage of the reverse time caused by the characteristics of the power applied to the sputter has an effect of improving the quality of the thin film. It is difficult to control or sustain the magnitude of the positive voltage. However, by using the method according to the present invention, by controlling the duration or the duration of the positive voltage for generating the cation, the cation having the desired energy and flux can be incident on the substrate to achieve the effect of improving the properties of the thin film. .

1 is a block diagram of a thin film forming apparatus according to the present invention.
2 is a view showing an example of a multi-step pulse voltage applied to the thin film forming apparatus according to the present invention.
3 is an energy distribution diagram of a cation formed according to a multi-step pulse voltage applied to the thin film forming apparatus according to the present invention.
Figure 4 is an example of the crystallinity change of the Ti thin film formed according to the multi-level pulse voltage applied to the thin film forming apparatus according to the present invention

Matters concerning the operational effects including the technical configuration of the thin film forming apparatus and the thin film forming method using the multi-step pulse technology according to the present invention with reference to the drawings showing preferred embodiments of the present invention are clearly shown below. Will be understood.

First, Figure 1 is a block diagram of a thin film forming apparatus according to the present invention, Figure 2 is a view showing an example of a multi-step pulse voltage applied to the thin film forming apparatus according to the present invention, Figure 3 is a thin film forming according to the present invention FIG. 4 is an example of the crystallinity change of the Ti thin film formed according to the multi-step pulse voltage applied to the thin film forming apparatus according to the present invention. FIG.

As shown, the thin film forming apparatus according to the present invention may include a vacuum reactor 100, a target 110, a magnetron unit 120 and a multi-stage power supply unit 130.

The vacuum reactor 100 is equipped with a sputter, and the gas introduced into the vacuum reactor is discharged by the negative voltage applied to the sputter to generate a plasma. That is, a plasma, which is a group of plasma ions and electrons, may be generated in the sputter installed on the vacuum reactor 100.

In this case, the plasma may not be formed by any one method but may be generated by various plasma methods.

Plasma ions generated by the sputter installed on the vacuum reactor may be alternately applied with a negative voltage and a positive voltage by the multistage power supply unit 130, and may be applied to the target 110 in the multistage power supply unit 130. When a negative voltage, which is a first bias voltage, is applied, plasma ions collide with the target 110 to generate sputtering, and the solid element sputtered from the target 110 on the substrate 140 under the vacuum reactor 100 (n). The thin film may be formed by).

In addition, after the thin film is formed on the substrate 140, the positive voltage (+) in the afterglow state near the target 110 is applied to the substrate 140 as a positive voltage, which is the second bias voltage, is applied from the multi-stage power supply unit 130. As the incident energy is transmitted to the substrate, the characteristics of the thin film may be improved as an effect of applying a temperature to the substrate 140 may be obtained.

At this time, the appropriate energy of the cation (+) may be controlled by controlling the positive voltage, the energy of the cation (+), it may be possible to control the flux. In addition, a magnetic field may be applied across the target 110 at the upper portion of the target 110, and application of the magnetic field may be applied through the magnetron unit 120 installed at the upper portion of the vacuum reactor 100.

To this end, the magnetron unit 120 preferably has a race track arrangement consisting of a center pole 121 and a side pole 122 surrounding the center pole, and electrons rotating along the race track are sputtered in a neutral state. Collide with the element to generate a solid element cation in the plasma state, thereby increasing the density of the solid element cation in the vicinity of the target. In addition, it may be implemented in a sputter structure without a magnet unit.

In this case, the multi-stage power supply unit 130 may be configured as a power supply to which a positive voltage and a negative voltage are alternately applied by switching.

Referring to the operation of the thin film forming apparatus of the present invention configured as described above are as follows.

First, the plasma processing gas is introduced into the vacuum reactor through a gas inlet (not shown) provided in the vacuum reactor 100. The discharged discharge gas is generated by the negative voltage which is the first bias voltage among the multi-stage pulse voltages applied through the multi-stage power supply unit 130 to the sputter installed on the vacuum reactor.

In addition, an additional plasma source may be installed to increase the density of the cations by the plasma in the vacuum reactor. In this case, the plasma may be switched through various methods as described above, namely, capacitive plasma discharge, inductively coupled plasma discharge, helicon discharge using a microwave wave, and microwave plasma discharge. It is not limited and can be switched in other ways.

Next, in the multi-stage pulse voltage applied to the sputter, the ion of the plasma generated by the negative voltage, which is the first bias voltage, in the multi-stage power supply unit 130 collides with the target 110, and the solid element is sputtered (n). As the incident light enters the substrate 140, a thin film may be formed on the surface of the substrate.

At this time, if a voltage is applied below the discharge voltage after the first bias voltage, the plasma disappears, but the afterglow state is maintained for a predetermined time before the plasma disappears.

In the multi-stage power supply unit 130, a positive voltage, which is a second bias voltage, is applied among the multi-stage pulses alternately applied to the sputter, and when the positive voltage is applied, the plasma is in an afterglow state before the plasma disappears. The positive electrode (+) is incident on the substrate 140 in the form of an ion beam by the voltage of the target 110 to which a positive voltage is applied.

On the other hand, the thin film forming method according to the present invention, even in the method using a co-sputter may be to apply energy to the substrate to improve the characteristics of the thin film by the cation.

Experimental results of measuring the energy of the cation due to the positive voltage, which is the second bias voltage, in the multi-step pulse are shown in the energy distribution of the cation shown in FIG. 3. In the experimental conditions of FIG. 3, the pressure of argon, which is the injection gas, is 1.5 mTorr, and the frequency and duty cycle of the modulator are 5 kHz and 20%, respectively.

The first bias voltage is -400 V and the second bias voltage is 0, 100, 200, 300 V among the multi-step pulse voltages applied to the stuffer. The energy of the cation was measured using an ion analyzer. As a result of the experiment, it can be seen that the energy of the cation changes as the second bias voltage of the multi-stage pulse voltage applied to the sputter is changed.

The incident cations may transfer energy such as heat is applied to the substrate 140 to improve characteristics of the thin film. The positive ion beam energy may be adjusted by adjusting the positive voltage, which is the second bias voltage, in the multi-stage power supply unit 130, and the positive ion beam energy and flux by adjusting the pulse frequency and the duty cycle. Can be adjusted.

As described above, a thin film is formed on the substrate by sputtering a desired material (material according to the material of the target) by a negative voltage, which is the first bias voltage, among the multi-level pulse voltages, and a positive amount of the second bias voltage among the multi-stage pulse voltages applied alternately. The characteristics of the thin film may be improved by repeating the process of transferring energy by applying a positive ion beam to the thin film by applying a voltage.

At this time, the negative voltage of the multi-level pulse voltage applied to the target 110 may be a pulse voltage of -100V to -2000V, preferably -300V to -1000V.

In addition, a positive voltage among the multi-level pulse voltages applied to the target 110 may be applied with a voltage of 0V to 1000V, preferably 10V to 500V, which may be changed by appropriate energy to improve the characteristics of the thin film. have.

The applied voltage is not limited to the described voltage, and may be adjusted in consideration of the kind of the solid element and the appropriate energy to improve the quality of the thin film.

In addition, a voltage may be applied to the substrate to control energy of the cation incident on the substrate, and temperature may be applied to the substrate so that additional energy may be transferred in addition to energy transfer by the cation. You can also do that.

On the other hand, the characteristic change of the thin film using the multi-step pulse voltage is as shown in FIG.

The characteristic change of the thin film shown in FIG. 4 is a view for examining the crystallinity change of the Ti thin film. The experimental condition of FIG. 4 is titanium (Ti) as a target material and the pressure of argon, which is an injection gas, is 3.6 mTorr. The frequency and duty cycle of the modulator are 15 kHz and 60%, respectively, and the first bias voltage is -600 V, and the second bias voltage is 0, 100, Changed to 200V. In order to observe the change of crystallinity of titanium (Ti) thin film, XRD was measured. As a result of the measurement, the energy of the cation changes as the second bias voltage of the multi-stage pulse voltage applied to the sputter changes. You can see what happens.

When the second bias voltage is 0V, most of them are deposited in the (002) crystal plane direction, but when the second bias voltage increases to 200V, most of them are deposited in the (100) crystal plane direction.

This is because the energy transfer by the cations incident on the thin film by the second bias voltage of the multi-level pulse voltage is a change in the characteristics of the thin film.

The embodiments described in the present specification and the configuration shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all of the technical idea of the present invention, and various equivalents may be substituted for them at the time of the present application. It should be understood that there may be water and variations.

100. Vacuum reactor 110. Target
120. Magnetron Unit 130. Multi-Level Power Supply Unit
140. Substrate

Claims (14)

A vacuum reactor to which a sputter to which a multi-stage pulse voltage is applied is installed and to generate plasma by plasma discharge;
A target for generating solid elements by sputtering by inducing plasma ions generated by the plasma discharge;
A magnetron unit for applying a magnetic field in the vacuum reactor across the target; And
A multistage power supply unit for alternately applying a negative voltage, which is a first bias voltage and a second bias voltage, to the target, wherein the multistage power supply unit is a magnitude of a negative voltage and a positive voltage. It includes a multi-stage power supply unit configured to control independently,
Thin film forming apparatus using multi-step pulse. The method of claim 1,
The target is a material to be deposited on a substrate, that is, carbon (C), silicon (Si), copper (Cu), gold (Au), aluminum (Al), titanium (Ti), chromium (Cr), platinum (Pt) ), Aluminum oxide (Al ₂ O ₃ ) and indium tin oxide (ITO),
Thin film forming apparatus using multi-step pulse. The method of claim 1,
The thin film forming apparatus is generated by applying a multi-stage pulse voltage to the target when generating a plasma in the vacuum reactor,
When the negative voltage is applied, plasma ions are induced so that the sputtered atom n is incident on the substrate to form a thin film,
When the positive voltage is applied, the plasma cations in the afterglow state and the sputtered solid elements ionized by the plasma are pushed out to enter the sputtered thin film in the form of an ion beam, thereby transferring energy.
Thin film forming apparatus using multi-step pulse. The method of claim 3,
An additional voltage applying means for applying an additional voltage to the substrate or a heating means for applying a temperature to the substrate such that an additional energy transfer is made in addition to the energy transfer by the cation to the substrate,
Thin film forming apparatus using multi-step pulse. The method of claim 3,
The absolute value of the negative voltage is greater than the absolute value of the positive voltage,
Thin film forming apparatus using multi-step pulse. The method of claim 3,
The cation is
Cations generated by the ionization of the injected gas; And
The solid element generated by sputtering the target is a solid cation ionized by plasma,
Thin film forming apparatus using multi-step pulse. In the thin film processing method using a multi-step pulse,
a) introducing a discharge gas into the vacuum reactor and applying a multi-stage pulse voltage to the sputter to generate a plasma;
b) forming a thin film by injecting a sputtered solid atom (n) into a substrate by impinging a ion of plasma generated by a negative voltage, which is a first bias voltage, among the multi-step pulse voltages applied to the sputter; And
c) The positive ion of the plasma in the afterglow state is incident on the substrate in the form of an ion beam by a positive voltage, which is a second bias voltage, among the multi-stage pulse voltages applied to the sputter, and the energy is transferred to the substrate. As a thin film forming method comprising the step of improving the characteristics,
The multi-level pulse voltage is a multi-step pulse technology configured to independently control the magnitude of the negative voltage and the positive voltage,
Thin film formation method using a multi-step pulse. 8. The method of claim 7,
The absolute value of the negative voltage is greater than the absolute value of the positive voltage,
Thin film formation method using a multi-step pulse. 8. The method of claim 7,
Step c) to improve the properties of the thin film formed on the substrate is:
Multi-step pulse technology is used to control the negative voltages that generate plasma cations and the positive voltages that change the energy of cations so that they can be adjusted to the appropriate energy in each thin film formation process, and the frequency and duty cycle (duty cycle) to control the,
Thin film formation method using a multi-step pulse. 8. The method of claim 7,
Step c) to improve the properties of the thin film formed on the substrate is:
Controlling the positive voltage so that the energy is applied to the substrate to improve the characteristics of the thin film by the cation even in a method using a co-sputter,
Thin film formation method using a multi-step pulse. 8. The method of claim 7,
Step c) to improve the properties of the thin film formed on the substrate is:
Applying an additional voltage to the substrate to enable energy regulation of the cations incident on the substrate,
Thin film formation method using a multi-step pulse. 8. The method of claim 7,
Step c) to improve the properties of the thin film formed on the substrate is:
Further heating the substrate such that additional energy transfer occurs in addition to energy transfer by the cation to the substrate,
Thin film formation method using a multi-step pulse. 8. The method of claim 7,
Providing a cation by an additional plasma source for increasing the density of the cation by the plasma in the vacuum reactor,
Thin film formation method using a multi-step pulse. 8. The method of claim 7,
In order to effectively increase the ionization of the solid element by the plasma, a negative voltage, which is the first bias voltage among the multi-stage pulse voltages, is applied at several to several tens of kV to form cations in the solid element ionized at a high density due to the high plasma density. Included,
Thin film formation method using a multi-step pulse.

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