JP2000169969A - Electric discharge plasma treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to rapidly obtain treatment conditions meeting purposes at the time of carrying out the surface treatment of a base material by using an electric discharge plasma. SOLUTION: This method executes the treatment of the base material surface by arranging counter electrodes under the pressure near the atmosphere pressure, impressing pulse voltage between the counter electrodes in the state of disposing the base material on one electrode of these counter electrodes to generate a plasma and using the plasma. The fluid motion in the discharge space and the transfer and reception of interparticle energy are simulated by using the data on the gaseous flow, such as the gas kind, gas flow velocity and gaseous pressure, of the gas to be discharged and the data on ionization fields, such as impressed voltage, pulse rise time, pulse electric field shape, pulse frequency, inter-electrode distance, as parameters, by which the degree of electrolytic dissociation of the gas of each time and space is determined and the pulse electric field shape is so determined as to maximize the time average in the degree of electrolytic dissociation of the gas of whole electric discharge space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a discharge plasma under a pressure near the atmospheric pressure, and more particularly, to the use of glow discharge plasma under a pressure near the atmospheric pressure, the degree of ionization and the distance between electrodes. Of the presence of charged particles, and the degree of ionization and dissociation of the introduced source gas, and the chemical vapor synthesis (CVD) reaction of the particles, for example, to predict the contribution of discharge parameters to the processing effect. The present invention relates to a discharge plasma treatment method for treating a substrate surface.

[0002]

2. Description of the Related Art A method for continuously forming a thin film of a transparent metal oxide or the like on a plastic film using glow discharge plasma is disclosed in JP-A-7-333404 and JP-A-8-165565. A plasma CVD or sputtering method under a low pressure as shown is disclosed. However, in these methods, since the film roll is installed in the vacuum chamber, the vacuum must be repeatedly released and formed every time a raw material is carried in or a product is carried out. It takes time. In addition, since it is necessary to use a complicated and large-scale vacuum discharge device, there is a problem that the equipment becomes expensive.

In order to solve such a problem, the present applicant has already proposed a film forming method (CVD) using normal-pressure pulsed plasma.

According to the film forming method, a counter electrode composed of a pair of electrodes facing each other and having one or both electrodes whose opposing surfaces (outermost surfaces) are coated with a solid dielectric is applied to a pressure near atmospheric pressure. The glow discharge plasma is generated by applying a pulse voltage between the opposing electrodes, and the glow discharge plasma is generated. This is a method of continuously forming a thin film on a material. In this film formation method,
A thin film can be formed directly on the film substrate by introducing the film substrate directly into the film forming environment from the atmospheric pressure environment.

[0005] In the film forming method using the normal-pressure pulse plasma described above, the pulse voltage applied between the opposing electrodes is:
For example, a pulse waveform as shown in FIGS. 2 to 7 is used, and the rising edge of the pulse waveform is 100 μm.
It is said that it is preferably set to s or less. The frequency of the pulse electric field applied between the opposing electrodes is 0.5 kHz.
It is considered that the frequency is preferably in the range of １００100 kHz. Further, the pulse duration in the pulse electric field is 1 μm.
s to 1000 μs, more preferably 3 μs to 20 μs.
It is considered that the range of 0 μs is good.

[0006]

The plasma C
Discharge phenomena under a low pressure, such as VD and sputtering, have been studied for a long time, and the tendency of discharge parameters leading to a desired treatment effect can be easily predicted by lean gas simulation based on the phenomenology. However, the glow discharge phenomenon near the atmospheric pressure has recently been discovered, and the scientific phenomena of the film formation method using the normal-pressure pulse plasma described above have not been elucidated yet. At present, the discharge parameters required to obtain the desired processing effect must be obtained by trial and error, and enormous time is required to develop the production technology.

Further, in the conventional lean gas simulation method, one kind of gas molecule (mainly a monoatomic gas such as argon) is to be calculated (see the following literatures 1) and 2).
In this simulation method, one pair of collision pairs which determines the calculation time is required for elastic collision, and 10 pairs are required for calculation because electron collision is added for inelastic collision. If this is simulated under normal pressure, the calculation from the huge number of particles becomes enormous.

Reference 1) Nambu, Usami, Ota: Fundamentals and programming of diluted gas numerical simulation method, Materials of the Society of Mechanical Engineers, No. 940-61 Reference 2) Usami, Teshima: Supersonic diluted free jet molecules by DCMC method Simulation, Transactions of the Japan Society of Mechanical Engineers (B
DISCLOSURE OF THE INVENTION The present invention has been made in view of such circumstances, and in performing a surface treatment of a base material using discharge plasma, the present invention has been developed according to the purpose. An object of the present invention is to provide a discharge plasma processing method capable of quickly obtaining processing conditions.

[0009]

According to the present invention, a counter electrode is arranged under a pressure near the atmospheric pressure, and a pulse voltage is applied between the counter electrodes in a state where a base material is disposed on one of the counter electrodes. A method for generating a discharge plasma by applying a voltage and applying a surface treatment to a substrate using the discharge plasma. The method includes data on a gas flow such as a gas type, a gas flow rate, and a gas pressure of a discharge target gas, and an applied voltage. By simulating the fluid motion in the discharge space and the transfer of energy between particles, using data on ionization field such as pulse rise / fall time, pulse electric field shape, pulse frequency, distance between electrodes as parameters, Is determined by determining the gas ionization degree of the entire discharge space and selecting the pulse electric field shape so that the time average is maximized.

According to the discharge plasma processing method of the present invention,
Parameters related to gas flow, such as gas type, total gas flow rate, gas flow rate, etc., and parameters related to ionization field, such as applied voltage, pulse rise / fall time, pulse shape, frequency, distance between electrodes, etc. Since the degree of ionization taking into account the contribution and interdependence of each of a large number of parameters can be calculated by simulation calculation, the discharge conditions according to the purpose can be narrowed down, and it is quickly suitable by actually confirming it. Discharge conditions can be obtained.

Next, a simulation method applied to the discharge plasma processing method of the present invention will be described in detail below.

First, the normal pressure plasma generated in the film forming method using the normal pressure pulsed plasma is limited to a narrow space (several mm) between the discharge electrodes.
Since the above process is often performed, the particles are ionized under a gas atmosphere having a pressure that is 4 to 5 orders of magnitude higher than that of the low-pressure plasma method, that is, a particle count of 4 to 5 orders of magnitude higher. Is characterized by the fact that a high-density glow discharge is generated, so that the treatment effect can be obtained at a very high speed.The distance between the electrodes is so small that the Langmuir probe method, which is generally used as a glow discharge diagnostic method, is characterized by a discharge. , It is difficult to know an accurate discharge state.

Therefore, in the present invention, a technique of simulating a normal-pressure pulse plasma and obtaining a processing condition (discharge condition) according to the purpose is adopted. As described above, there is a problem that an enormous amount of calculations are required to handle an enormous number of particle motions as compared with the low pressure method (lean gas simulation).

In order to solve this, in the present invention, the calculation region is reduced to a range where there is no problem in the simulation calculation (optimization of the calculation region), and the particle motion (behavior) is treated as the same in the simulation calculation. However, the amount of calculation is reduced by using a representative particle rule (optimizing the number of calculated particles) in which the motion of a particle group having no problem is represented by one pseudo particle. Also, by taking into account the gas flow between the opposed electrodes, the accuracy of the simulation calculation of the atmospheric pressure pulsed plasma is improved.

Note that the above-described calculation area reduction processing is as follows.
The area between the counter electrodes is divided into a predetermined number of layer areas (cells),
This is a process of reducing the thickness of each cell to a thickness that does not hinder the simulation calculation, thereby reducing the number of data used in the calculation.

A specific example of the simulation calculation of the normal pressure pulse plasma will be described with reference to FIG. In addition,
FIG. 1 is a block diagram showing the operation contents of a simulation calculation program executed on a computer or the like. In the simulation calculation of this example, the counter electrode is a parallel plate electrode (see FIG. 9), and the upper electrode (1
A pulse electric field is applied from 2a), and the lower electrode (12b) is used as a ground electrode.

First, data relating to the gas flow such as the type of gas to be discharged (first ionization potential of the gas to be discharged), gas flow velocity, gas pressure, etc., applied voltage, pulse rise / fall time, pulse electric field shape, When the data on the ionization field (between the opposed electrodes) such as the frequency and the distance between the electrodes is input (set), the optimal calculation region and the calculated particles for which the normal-pressure plasma simulation can be performed by the above-described reduction processing and the representative particle rule. The number is calculated, the initial state quantities of the representative particles are set, and these are stored as data.

Next, a representative pair of collision particles is extracted from the stored data, and the movement and collision (fluid motion) of the particles in the discharge space and the transfer of energy between the collision particles are calculated. After performing processing such as correction and energy storage during the period, ionization is determined from the data after these processing,
From the determination result, the degree of ionization (%) for each time and space is obtained and stored as data. Here, ionization means that the gas of the neutral particles is turned into plasma. Further, in the present invention, the calculation of particle movement / collision and energy transfer is performed using an arithmetic expression generally known in the field of dealing with particle motion, and a detailed description thereof will be omitted.

When the calculation of the degree of ionization in all calculation regions is completed, an average degree of ionization (%) is obtained from the calculated data, and each data (ionization degree data) is displayed. The ionization degree data can be displayed on a screen in a designated manner such as a numerical value, a graph, a distribution density image, or the like, and can be output to an external storage medium such as a floppy disk.

Here, in the normal pressure pulsed plasma simulation method as described above, when higher speed processing is expected, a combination that can obtain the maximum ionization degree within given conditions may be calculated. However, in the case where the substrate is plastic, if the plasma having a high ionization degree is used as it is in the treatment, holes or holes may be formed in the substrate due to ion bombardment. Further, in the CVD using a gas having a high reaction rate, there may be a problem that a film obtained by ion bombardment becomes cloudy. To avoid this, besides reducing the degree of ionization,
There is a method of giving a positive or negative bias to a pulse to be applied to change the tendency of charged particles to exist in space. For example, 60% of ions generated near the counter electrode of the electrode on which the substrate is disposed
By selecting the pulse waveform so that the percentage is not less than%, the effect of reducing the ion impact on the base material can be expected.

If the ion bombardment does not pose a problem in the CVD described in the above example, on the contrary, 60% or more of the generated reaction-excited species are unevenly distributed near the electrode on which the substrate is arranged, and It can be expected that the film deposition rate is increased and the film deposition on the opposing electrode is prevented. This can be expected to have a secondary effect such as prolonging the maintenance cycle and improving production efficiency by preventing electrode contamination.

Here, when the method of the present invention is applied to CVD using a gas-phase reaction gas such as a metal-containing gas as an introduced gas, information on film growth is obtained by repeatedly executing simulations as described below. (Deposition speed, reaction efficiency, etc.) can be obtained.

As an example, a simulation calculation of the growth of silicon dioxide using a mixed gas of tetraethoxysilane and oxygen and nitrogen as an introduction gas will be described below with reference to FIG.
This will be described with reference to the flowchart shown in FIG.

Also in this simulation calculation, the counter electrode is a parallel plate electrode (see FIG. 9), a pulse electric field is applied from its upper electrode (12a), and the lower electrode (12b) is a ground electrode.

First, similarly to the above-described simulation method (FIG. 1), input of condition data, setting of conditions of a CVD field (ionization field), division of calculation area cells, and setting of initial state quantities of particles are performed. Next, by using the previous simulation method and the preliminary calculation by the molecular orbital method, the number of collision pairs is reduced, and the transfer of energy due to the collision of charged particles with the molecule is simulated, so that the ionization and Reactions such as dissociation are calculated, then dissociation is determined from the data after the calculation, and silicon atoms and oxygen radicals (O ^* )
Is determined.

Here, reactions such as ionization and dissociation of molecules are usually performed by a stochastic method using a collision cross section (for example, see IEEJ: Gas Discharge Simulation Technique, IEEJ Technical Report, No. 140, p5-p13). ), Although this method is highly reliable in the field of molecular simulation, but under normal pressure, which is the subject of the present invention, the basic data of the collision cross-section of each molecule is weak. Actual calculations are difficult. Therefore, in the present invention,
An energy storage method is used to determine the generation of silicon atoms and oxygen radicals. Energy accumulation method is based on ionization of molecules.
This is an effective method for calculating a gas phase reaction under normal pressure because it is determined based on whether or not the accumulated energy of a reaction such as dissociation has exceeded a threshold value.

When the determination by the above-described energy accumulation method (gas phase reaction calculation) is completed, and it is confirmed that the molecules (ions) have reached the substrate surface, the process proceeds to the calculation in the reaction region on the substrate surface. . The substrate surface reaction calculation calculates the movement, collision, and energy accumulation of particles in the substrate surface area, and determines whether thin films are formed (film formation) based on whether molecules adhere to the substrate surface. Do with. Then, the above-described processes of the gas phase reaction calculation and the substrate surface reaction calculation are sequentially repeated until a desired simulation result is obtained.

Here, the reason why the simulation is performed by combining the gas phase reaction calculation and the substrate surface reaction calculation in the above example will be described in further detail.

First, many techniques relating to film formation simulation have been reported at present, but most of them focus on surface reactions. On the other hand, in a discharge simulation, it is usual to pay attention only to a gas phase reaction (see the following references 3) and 4).

In the simulation of the present invention, since the purpose is to predict a film formation result for an actual apparatus, it is necessary to achieve both a gas phase reaction and a substrate surface reaction. Therefore, as shown in the flowchart of FIG. 10, the result obtained by the gas phase reaction calculation is directly input to the surface reaction calculation block and looped until the film formation determination is performed, so that the gas phase reaction and the By integrating the surface reaction and the simultaneous calculation of the gas phase reaction and the surface reaction, the consistency with the actual result of the normal pressure pulsed plasma CVD is improved. By such a simulation method, the number of molecules leading to film formation can be calculated, thereby making it possible to predict a film formation rate, a reaction efficiency with respect to an introduced gas concentration, and the like, and based on the information, optimal film formation conditions. Can be obtained quickly.

Reference 3) Nanbu Nakanaka: Particle Simulation of RF Pulse Discharge of Chlorine, Proceedings of the 10th Computational Mechanics Conference, p245-p246 Reference 4) IEEJ: Characteristics and Simulation Techniques of Nonequilibrium rf Plasma, Electricity Technical report of the Society, No. 595 In the discharge plasma treatment method of the present invention, the material of the counter electrode used to generate discharge plasma is a simple metal such as copper or aluminum, an alloy such as stainless steel or brass, or Intermetallic compounds and the like can be mentioned. The counter electrode preferably has a structure in which the distance between the electrodes is substantially constant in order to avoid occurrence of arc discharge due to electric field concentration.
In addition to the above-mentioned parallel plate electrode, a cylindrical opposed plate type, a spherical opposed plate type, a hyperboloid opposed plate type, a coaxial cylindrical type structure and the like can be mentioned.

In the discharge plasma processing method of the present invention, it is preferable to provide a solid dielectric on one or both of the opposing surfaces of the opposing electrode. At this time, if there is a part where the electrodes directly face each other without being covered by the solid dielectric,
Since an arc discharge is easily generated therefrom, the solid dielectric is in close contact with the electrode on which the solid dielectric is provided, and completely covers the opposing surface of the contacting electrode.

The shape of the solid dielectric may be a sheet or a film, but is preferably about 0.5 to 5 mm. If it is too thick, a high voltage is required to generate discharge plasma, and If the voltage is too high, dielectric breakdown occurs when a voltage is applied, and arc discharge occurs.

Examples of the material of the solid dielectric include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxides such as silicon dioxide, aluminum oxide, zirconium dioxide and titanium dioxide, and double oxides such as barium titanate. Is mentioned.

However, the solid dielectric has a relative dielectric constant of 2
It is preferable that the above conditions (under a 25 ° C. environment, the same applies hereinafter).
Examples of such a dielectric include polytetrafluoroethylene, glass, and a metal oxide film.

[0036]

First, as an embodiment of the present invention, an example in which discharge conditions (pulse electric field waveform) are narrowed down from the following simulations 1 to 6 and processing examples 1 to 6 will be described. <Simulation 1> Discharge gas: Argon gas, gas pressure of 760 Torr, gas flow rate of 1.0 m / s, and gas flow conditions of 1.0 m / s. As poles (see FIG. 9), applied voltage +2 kV, -2 kV, rising 5 μs
ec, fall time 5 μsec, frequency 4 kHz (λ
= 25 μsec) as the ionization field data, a simulation was performed in the procedure shown in FIG. 1, and the average ionization degree was obtained.

As a result, the average ionization degree during the pulse application was 1.4%. The behavior of the ion density distribution between the electrodes increases with time, and after T = 2λ / 5 seconds (when a positive electric field is applied), the ions concentrate near the upper electrode. It was found to exist all over the area. <Simulation 2> As shown in FIG. 3, the fall time from the positive potential to the negative potential of the pulse waveform 2 is λ / 10
(2.5 μsec), except that it was the same as Simulation 1. At this time, the average ionization degree was 2.2%. Like the simulation 1, the tendency of the ions existing between the electrodes was concentrated near the upper electrode when the positive electric field was applied, and existed on the entire surface between the electrodes from the start of the negative electric field to the end of the pulse. <Simulation 3> As shown in FIG. 4, the same as Simulation 1 except that the rising time of the pulse waveform 3 was λ / 10 (2.5 μsec). At this time, the average ionization degree was 2.62%, and the existence tendency of ions was the same as in Simulations 1 and 2.

From the above simulations 1 to 3, it can be seen that it is effective to increase the pulse rise / fall time to improve the degree of ionization. In particular, it is effective to increase the rise time. In the simulations 1 to 3, the application time was shortened because the cycle length including the pulse pause time was fixed, but the ionization degree was improved despite that. this is,
The rise / fall time is a value that contributes to the acceleration of the particles, and it is considered that the resulting particle velocity contributes to the kinetic energy as a square.

From these results, the following simulation 4 was assumed, and the degree of ionization was assumed. <Simulation 4> As shown in FIG. 5, the rise time of the pulse waveform 4 was 3λ / 40 (1.875 μs),
It was the same as Simulation 1 except that the fall time was 3λ / 20 (3.75 μs). At this time, the average ionization degree was 3.1%.

The results of the above simulations 1 to 4 are
FIG. 8 shows a comparison based on relative ionization degrees where the ionization degree in simulation 1 was set to 1. It can be predicted that the ionization degree can be improved by changing the rise time in this way. <Processing Example 1> In the normal-pressure plasma processing apparatus (chamber 11: glass capacity: 8 L) shown in FIG. 9, the upper electrode 12a (φ140 mm) is arranged 2 mm above the grounded lower electrode 12b (φ140 mm), The inside of the chamber 11 is evacuated by a rotary pump (not shown) until the pressure in the chamber 11 becomes 0.1 Torr, and then the inside of the chamber 11 is 760 Ton.
Argon gas was introduced until the pressure reached rr. Thereafter, using a pulse power supply 13 having a rise time of 5 μs and a fall time of 5 μs, a pulse electric field of a positive potential of 3 kV and a negative potential of 3 kV is applied between the upper electrode 12a and the lower electrode 12b at a frequency of 4 kHz, and the electrodes are applied. The flowing current was determined and the current density was determined by dividing by the electrode area. The current density at this time was 62 mA / cm ² .

Here, in normal pressure discharge, plasma is generated only between the electrodes because the mean free path of the charged particles is extremely small. The current density is a measure for simply comparing the plasma density generated between the opposed electrodes (between the upper and lower electrodes) by utilizing this phenomenon. <Processing example 2> The processing example was the same as the processing example 1 except that a pulse power source having a rise time of 2.5 µs and a fall time of 2.5 µs was used. The current density at this time was 125 mA / cm ² . <Processing example 3> The processing example was the same as the processing example 1 except that a pulse power source having a rise time of 0.5 µs and a fall time of 0.5 µs was used. The current density at this time was 240 mA / cm ² .

From the tendency of the above processing examples 1 to 3, it can be understood that the rise / fall time of the pulse is a value that contributes to the improvement of the plasma density even in the actual discharge phenomenon. <Simulation 5> The applied voltage is +2 kV, -1 kV
The simulation was the same as the simulation 1 except that the pulse waveform 5 was biased to the positive electric field as shown in FIG. At this time, the average ionization density was 1.9%. However, the pulse pause time is 2λ / 5.

In the case of the simulation 5, a large change appears in the distribution of ions and electrons between the electrodes due to the change in the pulse electric field. The distribution of ions between the electrodes is, first, T = 0 to 2
In λ / 5 seconds (0 to 10 μs, between positive electric fields)
There is a gradient from near the upper electrode to the lower electrode,
Disappears rapidly after transition to the negative electric field. The time until almost disappearance is 95% of the total ionization number by T = λ / 2 seconds later.
Is ionizing. Thus, a state where ions of 95% of the total ionization number are concentrated near the upper electrode is obtained. In the case of this pulse shape, the vicinity of the lower electrode can be exposed to ions in a short time. For this reason, when the base material is arranged on the lower electrode side (ground electrode side), when it is desired to reduce ion bombardment on the base material, a pulse waveform unevenly distributed in a positive electric field as shown in FIG. 6 can be expected to be advantageous. . <Simulation 6> The applied voltage is +1 kV, -2 kV
The simulation was the same as the simulation 5, except that the pulse waveform 6 was biased to the negative electric field as shown in FIG. At this time, the average ionization degree was 1.9%. The tendency of the charged particle distribution between the electrodes is such that ions are unevenly distributed near the lower electrode, contrary to the simulation 5. From this, when it is desired to positively use the effect of ions, such as increasing the processing speed, it is expected that discharging with a pulse waveform biased to a negative electric field as shown in FIG. 7 is effective. <Processing Example 4> In a normal-pressure pulse plasma processing apparatus (chamber 11: glass, capacity 8 L) shown in FIG. 9, a grounded lower electrode 12 b (φ140 mm, surface having a relative dielectric constant of 1)
6, a cellulose triacetate (TAC) film (80 μm thick, made by Konica) was placed on the ZrO2 dielectric, and the upper electrode 12a (φ140 mm, relative permittivity of 16 was 2 mm above the surface of the TAC film F). ZrO
2 coated with a dielectric) and placed under the following conditions
An O2 thin film was formed.

0.1 T inside the chamber 11 with an oil rotary pump
or evacuated until the pressure in the chamber 11 reaches 760 Torr, and then argon gas is introduced from an inert gas inlet (not shown) until the pressure in the chamber 11 reaches 760 Torr.
Flow rate 2 scc from the reaction gas introducer 14 provided on the upstream side of
A mixture of m vaporized Ti (O-iPr) 4 and argon gas at a flow rate of 998 sccm was introduced. After introducing the mixture for one minute, a rise time of 5 μs, a fall time of 5 μs, and a frequency of 4 μm are applied between the upper electrode 12a and the lower electrode 12b.
A pulse electric field having a positive potential of 2 kV and a negative potential of 2 kV was applied at a frequency of 1 kHz and discharged for 150 seconds to form a TiO2 thin film on the surface of the TAC film F. <Processing example 5> Discharge pulse is positive potential 2 kV, negative potential 1 kV
The procedure was the same as that of Processing Example 4 except for the above. <Processing example 6> Discharge pulse is set to positive potential 1 kV, negative potential 2 kV
The procedure was the same as that of Processing Example 4 except for the above.

Table 1 below summarizes the results of the above processing examples 4 to 6. The refractive index and the film thickness were measured at five points using an ellipsometer (DVA-36VW, manufactured by Mizojiri Optical Industrial Co., Ltd.), and the average value was obtained. However, in processing example 6, the film became cloudy and the film thickness could not be measured by optical measurement. Therefore, a high-resolution scanning electron microscope (S-4500 manufactured by Hitachi, Ltd.)
Was measured from the cross-sectional image.

[0046]

[Table 1]

As can be seen from Table 1, in the case of the processing example 5, compared with the case of applying the same pulse waveform in the processing example 4, the Ti
A refractive index close to the theoretical refractive index (2.3) of O2 is obtained. Regarding the film forming speed, the processing example 5 is the same as the processing examples 4 and 6.
Slower than. This is considered to be due to the fact that in the case of the processing example 5, the ion bombardment was slight because there was little ion in the vicinity of the base material, so that the growth was slow but the dense film grew.
It is considered that the reason why the refractive index was low in the treatment example 4 was that the surface was roughened by ion bombardment, the surface became porous, and the average refractive index of air and TiO2 appeared. That is, a result that can be explained by the prediction in the simulation 5 is obtained.

In the case of processing example 6, although the growth rate was high, a transparent film was not obtained and the film became cloudy. This is because, in the presence of ions concentrated near the base material, the reaction gas is rapidly decomposed and the film is grown.
It is considered that the film became cloudy due to the pulverization of 2.
From this, it can be determined that the above-described simulation 6 has obtained results in accordance with reality.

Next, a specific example of the simulation calculation shown in FIG. 10 will be described below together with a processing example. <Simulation 7> Discharge gas: N2 84% + O2 15.9% Film formation gas: Tetraalkoxysilane (TEOS) 0.1
% Gas pressure: 760 Torr Gas flow rate: 1.0 m / s Under the above gas conditions, the upper electrode of the parallel plate electrode having a distance between the electrodes of 2 mm is used as the applied electrode, and the lower electrode is used as the ground electrode (see FIG. 9). The pulse waveform 1 shown in FIG. 2 with an applied voltage of +9 kV, −9 kV, a rise time of 5 μsec, a fall time of 5 μsec, and a frequency of 4 kHz (λ = 25 μsec) is used as the data of the ionization field. A simulation was performed according to the procedure shown in FIG. 10 to determine the time dependence of the film growth.

As a result, as shown in the following Table 2 and each calculated value in FIG. 11, the time from surface diffusion to nucleus growth is 0.5.
After a lapse of seconds, it was calculated that the SiO2 film grew at a growth rate of about 70 DEG / sec.

[0051]

[Table 2]

<Processing Example 7> In the normal-pressure plasma processing apparatus (chamber 11: glass capacity: 8 L) shown in FIG. 9, 2 m from the grounded lower electrode 12 b (φ140 mm).
The upper electrode 12a (φ140 mm) is arranged above
The inside of the chamber 11 is set to 0.1 by a hydraulic rotary pump (not shown).
Evacuation is performed until the pressure reaches Torr.
14. N2 84% + O2 until the pressure reaches 760 Torr.
A mixture of 9% and TEOS 0.1% was introduced. Thereafter, the upper electrode 12a and the lower electrode 12b are used by using a pulse power source 13 having a rise time of 5 μs and a fall time of 5 μs.
At a frequency of 4 kHz, a positive potential of 9 kV, and a negative potential of 9 kV.
A lower electrode 1 heated to 70 ° C. by applying a pulsed electric field of V
PET base material (Lumirror T50 manufactured by Toray Industries, Inc.)
(Thickness: 80 μm) was discharged for 10 seconds to form a silicon oxide thin film.

The thickness of the thin film obtained in Processing Example 7 was measured using an ellipsometer (DVA-36VW, manufactured by Mizojiri Optical Industrial Co., Ltd.).
Was measured at five points, and the average value was determined. The results (experimental values) are shown in Table 2 and FIG.

In the above Table 2 and FIG.
Is smaller than the film thickness (calculated value) obtained by the simulation 7,
In the simulation calculation, it is considered that the deviation occurs because the leakage flow rate of the introduced gas from between the electrodes and the accurate reaction efficiency are not used as conditions. <Simulation 8> The gas pressure was set to 790 Torr, the gas flow rate was set to 1.0 m / s, the discharge gas N2: O2 was set to 21: 4, and the concentration of the raw material gas, tetraalkoxysilane (TEOS) was set to 0.05 to 0. It was changed in 0.05% steps in the range of 2%. The discharge time was 10 seconds, the ionization field and the temperature conditions were the same as in the simulation 7, and the concentration dependence of the film growth rate was calculated. The results (calculated values) are shown in Table 3 below and FIG.

[0055]

[Table 3]

<Processing Example 8> TEOS concentration of 0.05 to
A film was formed in the same manner as in Processing Example 7, except that the thickness was changed in 0.05% steps in the range of 0.2%.

The thickness of the thin film obtained in Processing Example 8 was measured using an ellipsometer (DVA-36VW, manufactured by Mizojiri Optical Industrial Co., Ltd.).
Was measured at five points, and the average value was determined. The results (experimental values) are shown in Table 3 and FIG.

In Table 3 and FIG. 12, although there is a slight difference between the calculated value by the simulation 8 and the experimental value by the processing example 8, it is considered that the actual conditions are sufficiently simulated. Note that a downward bend in the film thickness (experimental value) is observed in the low-concentration region, which is considered to be due to the fact that the film thickness is extremely thin and includes many measurement errors.

[0059]

As described above, according to the discharge plasma processing method of the present invention, the data on the gas flow and the ionization field are used as parameters to simulate the fluid motion in the discharge space and the transfer of energy between particles. ,
The gas ionization degree for each time and space is determined, and the pulse electric field shape is selected so that the time average of the gas ionization degree of the entire discharge space is maximized, so that processing conditions according to the purpose can be quickly achieved. As a result, the time required for the discharge plasma treatment can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the contents of a simulation calculation used in the discharge plasma processing method of the present invention.

FIG. 2 is a diagram showing a pulse waveform 1 used in an embodiment of the present invention.

FIG. 3 is a diagram showing a pulse waveform 2 used in an embodiment of the present invention.

FIG. 4 is a diagram showing a pulse waveform 3 used in an embodiment of the present invention.

FIG. 5 is a diagram showing a pulse waveform 4 used in an embodiment of the present invention.

FIG. 6 is a diagram showing a pulse waveform 5 used in an example of the present invention.

FIG. 7 is a diagram showing a pulse waveform 6 used in an embodiment of the present invention.

FIG. 8 is a graph showing the waveform dependence of the degree of ionization.

FIG. 9 is a diagram schematically showing a configuration of a normal-pressure pulse plasma processing apparatus used in an embodiment of the present invention.

FIG. 10 is a block diagram showing the contents of another example of the simulation calculation used for the discharge plasma processing method of the present invention.

FIG. 11 is a graph showing calculated values and experimental values of time dependence of film growth.

FIG. 12 is a graph showing calculated values and experimental values of the dependence of the film growth rate on the TEOS concentration.

[Explanation of symbols]

 Reference Signs List 11 chamber 12a upper electrode 12b lower electrode 13 pulse power supply 14 reactive gas introducer F TAC film (base material)

Continued on the front page F term (reference) 4F073 BA16 BA24 BB01 CA01 HA01 HA09 HA12 HA15 4K030 AA06 AA09 AA14 AA18 BA44 FA03 HA07 HA16 JA01 JA09 JA11 JA14 JA16 KA30 KA32

Claims (3)

[Claims] 1. A discharge plasma is generated by arranging a counter electrode under a pressure close to the atmospheric pressure and applying a pulse voltage between the counter electrodes while a base material is disposed on one of the counter electrodes. A method for treating the surface of the base material using the discharge plasma, comprising: data on a gas type such as a gas to be discharged, a gas flow rate, a gas pressure, and the like; an applied voltage; a pulse rise / fall time; By simulating the fluid motion in the discharge space and the transfer of energy between particles using the data on the ionization field such as the pulse electric field shape, the pulse frequency, and the distance between the electrodes as parameters, the gas ionization degree for each time and space is obtained. A discharge plasma processing method characterized in that a pulse electric field shape is selected so that a time average of a gas ionization degree of an entire discharge space becomes maximum. 2. The method according to claim 1, further comprising calculating a gas ionization degree for each time and space by said simulation, calculating a temporal existence tendency of the charged particles in the space discharge, and distributing ions in the plasma to the surface of the substrate disposed on the electrode. 2. The discharge plasma processing method according to claim 1, wherein the shape of the pulse electric field is selected so as to be 60% or more in the vicinity. 3. The gas ionization degree for each time and space is obtained by the above simulation, and the temporal existence tendency of the charged particles in the space discharge is calculated, and the ions in the plasma are separated from the electrode on which the base material is arranged. 60% near the opposing electrode
2. The discharge plasma processing method according to claim 1, wherein the pulse electric field shape is selected so as to exist.