JP2004076122A - Plasma surface treatment method and apparatus for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform surface treatment, such as reforming, of a substrate to be treated without damaging the substrate by generating a uniform plasma free of microarcs under pressure approximate to the atmosphere pressure. <P>SOLUTION: Reactive gases are jetted and supplied so as to be confined in a spacing between counter electrodes 2, through which spacing, the substrate 5 to be treated passes, from both of gas jet ports 11 and 11 disposed on the introducing side and discharging side of the substrate 5 to be treated toward the spacing. Further, the oscillation frequency of a high-frequency oscillation machine 12 for supplying a sinusoidal high-frequency voltage to the counter electrodes 2 is made to follow up the resonance frequency of a load side resonance circuit by a PLL (Phase Locked Loop) circuit 15 to prevent the distortion of the supply voltage and to suppress the generation of the microarcs by a steep noise component, thereby continuously forming the stable plasma. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma surface treatment method and an apparatus therefor, and more specifically, to a substrate such as an FPD, an FPD color filter, a printed circuit board, a film-shaped substrate, a silicon wafer, a photomask, and a solar cell under a pressure close to normal pressure. The present invention relates to a plasma surface treatment technique for performing surface treatment with plasma.
[0002]
[Prior art]
In the semiconductor-related industry, various surface treatments are performed on substrates such as FPDs (flat panel displays), FPD color filters, printed boards, film-shaped substrates, silicon wafers, photomasks, and solar cells. This includes modification treatment for imparting hydrophilicity or hydrophobicity, improvement in adhesion by removing residues, drying, and the like.
[0003]
The modification treatment for imparting hydrophilicity or hydrophobicity is performed, for example, in a process of forming various films on a glass substrate of an FPD, before a sputtering treatment, before a photoresist coating, before a developing solution coating, and before a photoresist stripping treatment. UV light and far ultraviolet light. However, this method uses a photo-excitation reaction, so that it is difficult to reduce the processing time.
[0004]
Removal of the residue is performed as a pretreatment for depositing amorphous silicon, polysilicon, or a metal thin film on the glass substrate of the FPD by CVD or sputtering. If a residue such as an organic substance remains on the substrate before depositing the thin film, the adhesion between the glass substrate and the thin film may be poor, and the thin film may be easily peeled off. That is, by using a UV lamp or an excimer lamp device to remove residues such as organic substances before deposition, the adhesion is improved. However, this method also involves a reaction of photoexcitation, so that the processing speed is slow and the productivity is poor.
[0005]
The improvement of adhesion is also performed as a pretreatment when an etching solution, a developing solution, and a resist solution are applied to a substrate using a UV lamp or an excimer lamp in a manufacturing process of an FPD or the like. However, as described above, in the photoexcitation reaction, the reaction speed is slow, the number of lamps is increased to several tens or more, and the device becomes large, so that the power consumption is large.
[0006]
In the method using the UV lamp and the excimer lamp, the illuminance decreases with the irradiation time, and the predetermined performance cannot be obtained. For this reason, there is also a problem that the lamp replacement cost and the operation of the apparatus for replacement must be stopped.
[0007]
Drying is performed on, for example, a silicon wafer. Conventionally, a drying method using an IPA vapor, a drying method using the Marangoni phenomenon of IPA, a spin drying method, a heater drying method, and the like have been adopted.
[0008]
However, these methods have a problem of residues on the substrate after drying. In particular, when IPA is used, the waste liquid is contaminated with the organic solvent, which causes a problem of environmental pollution.
[0009]
In order to solve the above problem, it is conceivable to adopt a conventional technique of surface treatment using vacuum plasma under a low pressure. However, since vacuum plasma is generated in an airtight chamber, an exhaust mechanism such as the airtight chamber and a vacuum pump is required, so that the cost for introducing the apparatus and the area occupied by the apparatus increase. Further, since batch processing cannot be performed and continuous processing by line conveyance cannot be performed, it is difficult to increase productivity.
[0010]
In order to solve the above problem, it is necessary to perform a process under a pressure near normal pressure. When this treatment is performed using a conventional technique, surface treatment is performed by using helium, air, nitrogen, argon gas, or the like as a reaction gas and generating corona discharge between a pair of opposed electrodes.
However, when the treatment such as the reforming is performed by corona discharge, thermal and electrical damage of the substrate due to the micro arc becomes a serious problem.
[0011]
As an improvement of the above method, it is conceivable to generate a stable glow discharge by increasing the amount of helium used in the reaction gas. However, in this case, helium is expensive and requires a considerable gas flow rate, and at the same time, the applied power density is 1 w / cm. ² The above is necessary. For this reason, the usage amount and the power consumption of the reaction gas increase, and the running cost increases. In addition, in this case, heat generation of the electrode unit and the discharge unit causes thermal damage to the substrate to be processed. In particular, when an inert gas is used, there is also a problem that metal contamination from the electrode metal portion on the processing substrate occurs due to a sputtering effect (secondary electron emission phenomenon).
[0012]
Further, it is also possible to perform a surface treatment by generating a glow discharge by selecting a combination of types of gas used and a processing flow rate. However, in this case, if there is a metal thin film in a printed circuit board or a film substrate such as polyimide, an electric field is concentrated on the metal thin film portion, a micro arc is generated, and the thin film is damaged, and the substrate is damaged by the micro arc. Was also triggered.
[0013]
Therefore, it is unsuitable for processing a metal film patterned on a thin film such as polyimide or a silicon wafer.
[0014]
[Problems to be solved by the invention]
The present invention has been proposed for the purpose of solving the above problems, and generates a uniform plasma without a micro-arc under a pressure near the atmospheric pressure, regardless of the surface material of the substrate to be processed, at normal temperature conditions. It is an object of the present invention to provide a processing method and apparatus capable of continuously performing a surface treatment on a substrate with a substrate and stably removing organic substances on the surface, modifying the surface, depositing a thin film, etc. without processing damage to the substrate. .
[0015]
Another object of the present invention is to dry a substrate without using IPA, causing no environmental pollution due to waste liquid, and without causing a problem of residue on the substrate.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, the plasma surface treatment method of the present invention fills a gap between a pair of counter electrodes covered with a solid dielectric with a reaction gas at a pressure near atmospheric pressure, and applies a high-frequency voltage to the counter electrodes. In an apparatus for performing a surface treatment on a substrate to be processed passing through the gap by plasma generated in the gap, an opening for introduction and an opening for discharge of the substrate to be processed are opened, the gap between the opposed electrodes is separated from an external space, and a reaction gas is formed. By injecting them into the gap from both the inlet opening and the outlet opening.
[0017]
In the above configuration, the reaction gas, which is injected into the gap from both the introduction side and the discharge side of the substrate to be processed and is excited to be plasma, is confined in the electrode gap, and the minimum gas A stable and uniform plasma can be generated at a flow rate, and a uniform plasma can be generated in a length direction of the electrode, which is a passing direction of the substrate to be processed.
[0018]
Further, the plasma surface treatment apparatus of the present invention, the opening for introduction and the opening for discharge of the substrate to be processed, and a partition partitioning the gap between the counter electrodes from the external space, from both the introduction opening and the discharge opening, A gas injection port for injecting and supplying a reaction gas so as to be confined toward the gap is provided, and the gas injection port is provided for each space of the gap divided by the substrate to be processed with respect to the introduction opening and the discharge opening. It is configured as
[0019]
In this apparatus, the reaction gas rectified by the cavity is supplied to the substrate to be processed through slit-shaped gas injection ports provided so as to extend in the width direction of the electrode at upper and lower positions in the introduction opening and the discharge opening. Since they are separately supplied to the front and back surfaces, the dielectric constant of the front and back surfaces of the substrate to be processed at the time of plasma generation can be made uniform, and uniform plasma can be generated on the front and back surfaces.
[0020]
The reason why the pair of electrodes is covered with the solid dielectric is to isolate the electrodes from the outside air and the gas to be used and to prevent the substrate to be processed from being contaminated by metal constituting the electrodes.
[0021]
It is preferable that the injection direction of the gas injection port is 5 ° to 45 ° with respect to the surface of the substrate to be processed. This is because the injection pressure of the reaction gas is applied to the inside of the electrode gap, and the reaction gas is smoothly supplied into the gap along the substrate to be processed. This makes it possible to make the plasma in the gap uniform even if the electrode length in the passage direction of the substrate to be processed increases.
[0022]
Further, it is preferable that a flow path of the cooling liquid is formed in the pair of electrodes. A circulating insulating liquid, such as pure water or ultrapure water, ethylene glycol, galden, or florinate, is circulated and pumped into the flow path of the cooling liquid by a pump, so that heat generated by applying a high frequency is suppressed. This can reduce thermal damage to the substrate to be processed.
[0023]
The plasma surface treatment apparatus of the present invention has the following features for high-frequency power supply. In other words, the plasma surface treatment apparatus forms a gap through which a substrate to be processed is opposed to each other, and a pair of electrodes receiving a supply of a reaction gas at a pressure near atmospheric pressure in the gap, and the electrode through a step-up transformer. A high-frequency oscillator that supplies a high-frequency voltage having a sinusoidal waveform, and a PLL circuit that causes the oscillation frequency of the high-frequency oscillator to follow the fluctuation of the resonance frequency of the parallel resonance circuit that occurs when the electrode and the secondary side of the step-up transformer are connected. It is characterized by having.
[0024]
In such a high-frequency power supply method, impedance matching between the power supply side and the load side can always be ensured even if the dielectric constant of the electrode gap fluctuates due to plasma generation conditions such as the type of reaction gas.
[0025]
As a result, distortion of the supply voltage can be prevented, and generation of harmonics can be prevented. Therefore, generation of micro-arcs due to a large peak value and a steep noise component can be suppressed, and stable plasma can be generated stably and continuously. Can be.
[0026]
In addition, since the minimum amount of power per unit area that can continuously generate plasma can be reduced, a surface treatment with extremely small damage to a substrate to be processed can be performed.
[0027]
The high-frequency power supply system for causing the oscillation frequency of the high-frequency oscillator having a step-up transformer to follow the fluctuation of the resonance frequency of the parallel resonance circuit by a PLL circuit is provided in the surface treatment apparatus characterized by a reaction gas supply system. Can be incorporated.
[0028]
The combination of the above-described high-frequency power supply system and the reaction gas supply system maximizes the effect of enabling stable and uniform plasma generation.
[0029]
When only the high-frequency power supply method is used and the reaction gas supply method is not used, the gas flow rate increases, but the effect of uniform plasma generation can be obtained.
[0030]
The plasma surface treatment apparatus described above can be used in the following manner.
[0031]
{Circle around (1)} A plasma surface treatment method in which the substrate temperature of the substrate to be treated is heated from a normal temperature to a predetermined temperature, for example, 180 ° C., to simultaneously perform drying, heating, and surface modification.
[0032]
{Circle around (2)} A plasma surface treatment method for performing surface modification for improving adherence in a semiconductor wafer treatment process before applying various chemical solutions such as a developing solution and a cleaning solution and a resist solution.
[0033]
{Circle around (3)} A plasma surface treatment method in which a metal thin film or a dielectric thin film is deposited on a thin film formed on a processing substrate by using a CVD or sputtering apparatus, and the surface is modified to improve the adherence.
[0034]
{Circle around (4)} A plasma surface treatment method for drying a wafer surface in a drying step after wafer cleaning and wet etching in an IC manufacturing process.
[0035]
【Example】
An embodiment of the present invention will be described below. FIG. 1 is a sectional view of an electrode unit 1 of a surface treatment apparatus according to an embodiment of the present invention. In the figure, reference numerals 2 and 2 denote a pair of plate electrodes which are opposed at equal intervals. The plate electrodes 2 and 2 have a cavity (not shown) formed therein, and the periphery thereof is covered with solid dielectrics 3 and 3. An insulating liquid as a cooling liquid is circulated through the cooling liquid supply pipes 4 and 4 into the internal cavities of the plate electrodes 2 and 2 to suppress heat generation of the plate electrodes 2 and 2. The insulating liquid is, for example, pure water or ultrapure water, ethylene glycol, galden, florinate, or the like. The cooling temperature is set, for example, such that the plate electrodes 2 and 2 are kept at 120 ° C. or less, and the substrate 5 to be processed is cooled. To prevent thermal damage.
[0036]
The reason that the plate electrodes 2 and 2 are covered with the solid dielectrics 3 and 3 is that the electrodes are isolated from the outside air and the used gas, and that the substrate 5 to be processed is not contaminated with the metal of the plate electrodes 2 and 2. That's why. The relative permittivity of the solid dielectrics 3, 3 is preferably 10 or more in order to concentrate the electric field in the discharge gap.
[0037]
The opposing surfaces of the solid dielectrics 3, 3 become parallel discharge surfaces 6, 6 for generating plasma, between which the substrate 5 to be processed passes. Reference numerals 7 and 7 denote transfer ports.
[0038]
Reference numerals 8 and 8 denote a pair of electrode unit covers, which form cavities 9 and 9. Reference numerals 10 and 10 denote gas inlets to the cavities 9 and 9, and 11, 11, 11, and 11 denote gas injection ports.
[0039]
The reaction gas introduced from the gas inlets 11 is rectified by the cavities 9, and two gases are disposed on the introduction side and the discharge side of the substrate 5, two for each discharge surface 6, 6. It is injected into the gap between the discharge surfaces 6, 6 through the injection ports 11, 11, 11, 11. As shown in FIG. 3, the structure of the gas injection port 11 is a slit-shaped opening extending in a direction (width direction of the electrode) perpendicular to the plane of FIG. , And has an appropriate angle θ with respect to the discharge surface 6. This angulation is performed by making the corners of the solid dielectrics 3, 3 on the introduction and discharge sides of the substrate 5 to be tapered into a tapered surface 3a, and an inclined plate 8a inside the electrode portion cover 8 forming the cavities 9, 9. This is done by placing By changing the inclination and position of the tapered surface 3a and the inclined plate 8a, the injection state of the reaction gas can be made appropriate.
[0040]
FIG. 2 is a cross-sectional view of the electrode unit 1 of FIG. 1 when viewed from a direction orthogonal to FIG. The structure of the electrode portion 1 shown in FIGS. 1 and 2 can be freely adapted by changing the size of the discharge surface 6 and its peripheral portion in accordance with the size of the substrate 5 to be processed. .
[0041]
FIG. 4 shows an electric circuit to which a high-frequency oscillator 12 is connected to supply high-frequency power to the electrode unit 1. This figure shows that a parallel resonance circuit 14 is formed by the capacitance C of the electrode unit 1 and the inductance L of the secondary winding of the step-up transformer 13 provided on the output side of the high-frequency oscillator 12. .
[0042]
When plasma is generated in the electrode portion 1 by applying a high frequency, the dielectric constant in the gap between the discharge surfaces 6, 6 fluctuates greatly. The dielectric constant is determined by plasma generation conditions (gas type, gas flow rate, high-frequency power, material and thickness of a substrate to be processed, processing temperature, etc.). Due to the change in the dielectric constant, the resonance frequency f in the parallel resonance circuit 14 is changed. _o = 1 / [2π√ (LC)] greatly changes, and impedance mismatch between the high-frequency oscillator 12 and the electrode unit 1 occurs. In this case, it is expected that the reflected power is generated and the waveform is distorted, the plasma becomes unstable due to its harmonic component which fluctuates sharply at a large peak value, and uniform processing cannot be performed.
[0043]
Therefore, in the circuit of FIG. 4, a PLL circuit 15 is provided in the high-frequency oscillator 12 so that the resonance frequency f _o The oscillation frequency of the high-frequency oscillator 12 fluctuates in accordance with the fluctuation of the frequency.
[0044]
Thereby, the resonance frequency f ₀ Is always output to the parallel resonance circuit 14 and the resonance state is maintained. In this case, the capacitance component (jωC) and the inductance component (jωL) can be ignored at that frequency, and the current I is determined only by the pure resistance R as shown in the equivalent circuit of FIG. That is, the condition for giving the maximum power consumption to the electrode unit 1 which is the load R in this circuit is to make the value of the internal resistance r of the battery V and the value of the load R the same. P = I ² R is secured. FIG. 6 shows a change in the impedance Z of the parallel resonance circuit 14 and a change in the power P consumed by the electrode unit 1 with respect to the frequency f of the high-frequency voltage supplied to the parallel resonance circuit 14. That is, the resonance frequency f ₀ At this time, the impedance Z becomes minimum and the power consumption P becomes maximum.
[0045]
Next, specific experimental results of the present invention in which the reaction gas supply method shown in FIGS. 1 to 3 and the high frequency power supply method described in FIGS. 4 and 5 are combined will be described.
[0046]
(Experimental example 1)
1 to 3, the electrode width w is 800 mm, the electrode length 1 is 30 mm, the distance g between the electrodes is 4 mm, the thickness d of the solid dielectric 3 is 3 mm, and aluminum oxide (Al) is used as the material of the solid dielectric. ₂ O ₃ 5), aluminum was used as the material of the electrode 2, and an experiment was performed with the power that can be supplied to the high-frequency oscillator 12 in FIG.
[0047]
Oscillation frequency was measured when a discharge experiment was performed using a single reaction gas of oxygen, nitrogen, argon, air, and helium or a mixed gas thereof in an atmosphere under normal pressure. In this case, it was confirmed that the frequency at the time of plasma generation varied between 29 KHz and 50 KHz, and that the resonance frequency of each gas type changed due to the difference in the dielectric constant of plasma generated between the electrodes.
[0048]
When the output waveform at this time was measured with a synchroscope, a sine wave having a small noise component was supplied, and a good plasma was generated in which no micro arc was recognized and no arc noise was recognized.
[0049]
However, when the operation of the PLL circuit 15 is stopped and the oscillation frequency is out of the resonance region, a lot of noise components are seen, and the noise exceeds a predetermined applied set voltage and a micro arc is generated. It was recognized that. This was a state close to corona discharge where arc noise occurs. At this time, when the peak voltage applied to both electrodes of the electrode unit 1 was measured with a synchroscope, it was about 1.5 times the applied set voltage.
[0050]
In these, maintaining the parallel resonance condition eliminates the generation of harmonics due to waveform distortion and can supply sine waves with little noise component, suppresses instantaneous voltage rise due to noise, and eliminates micro arc It represents that.
[0051]
In the present invention, as shown in FIG. 2, a reaction gas is injected from both the introduction side and the discharge side of the substrate to be treated so as to be confined in the electrode gap.
This structure encloses the gas once excited and ionized by the high frequency in the discharge surface 6, and enables stable and uniform plasma generation with a minimum gas flow rate. This means that the plasma generation sustained minimum high-frequency power can be lowered accordingly, and damage to the substrate to be processed can be reduced.
[0052]
The plasma generation sustained minimum high frequency power is 0.013 w / cm when the reaction gas is helium alone. ² Was obtained.
[0053]
In addition, when the injection direction of the gas injection port 11 (the angle θ in FIG. 1) is adjusted and the generation state of the plasma is examined, it is found that the angle of the microhole is in the range of θ = 5 ° to 45 ° with respect to the surface of the substrate to be processed. It was found that a good plasma without arc was obtained. In this case, the required gas flow rate could be reduced to about 1/2 as compared with the case where the reaction gas was flowed in one direction as shown in FIG.
[0054]
Next, several experiments were performed using the plasma surface treatment apparatus of Experimental Example 1 described above (the reaction gas supply method shown in FIGS. 1 to 3 and the high-frequency power supply method shown in FIG. 4). FIG. 7 shows the results of an experiment for modifying the glass surface by plasma irradiation using air as the reaction gas. Immediately after the treatment, the contact angle indicating the wettability was about 1.5 degrees, but it can be seen that the angle gradually increased with time (left for one hour).
[0055]
Further, two silicon wafers on which a gate oxide film is deposited at about 80 °, a polysilicon film is deposited at 4000 °, and a field oxide film is deposited at 4000 ° are prepared, one of which is left as a reference, and the other is subjected to surface treatment by plasma using the apparatus of the present invention. went. Next, IV characteristics and CV characteristics were measured for each of the reference and the processed wafer, and the measured values at the same position on the wafer were compared. The thin film was examined for damage to the thin film due to dielectric breakdown, spatter effect, and the like. As a result, almost no change was observed from the state before the treatment.
[0056]
Further, using the surface treatment apparatus of the present invention, helium, argon, nitrogen, oxygen, and air alone or mixed to generate the plasma, these gas molecules in the process of transition to ionization, dissociation Emission spectroscopy showed emission in the vacuum ultraviolet region with an emission wavelength of 170-340 °.
[0057]
The emission wavelength was such that water remaining on the wafer surface was decomposed into oxygen and hydrogen and completely dried. Therefore, in the IC manufacturing process, in the drying process after the wafer cleaning and wet etching, it is possible to dry without leaving any residue on the wafer surface and without causing environmental pollution due to waste liquid.
[0058]
According to the above experiments, (1) simultaneous treatment of drying, heating and surface modification, (2) surface modification for improving the adherence of the semiconductor wafer, (3) formed on the processed substrate It was confirmed that the surface modification for improving the adherence to the thin film, and (4) the drying of the semiconductor wafer surface can be performed without damage by the micro arc.
[0059]
Next, as shown in FIG. 8, an embodiment in which the electrode portion 16 of a type in which the reaction gas flows in one direction along the electrode surface is adopted and combined with the high frequency power supply system of FIG. 4 will be described.
[0060]
FIG. 8 is a sectional view showing an electrode unit 16 of another embodiment of the plasma surface treatment apparatus of the present invention. In the figure, reference numerals 2 and 2 denote a pair of plate electrodes which are opposed at equal intervals. The plate electrodes 2 and 2 have a cavity (not shown) formed therein, and the periphery thereof is covered with solid dielectrics 3 and 3. An insulating liquid such as pure water as a cooling liquid is circulated through the cooling liquid supply pipes 4 and 4 into the internal cavities of the plate electrodes 2 and 2, and the same operation as the structure of FIG. Reduce fever. The opposing surfaces of the solid dielectrics 3, 3 are parallel discharge surfaces for generating plasma, and the substrate 5 to be processed is passed between them. Reference numerals 7 and 7 denote transfer ports.
[0061]
Reference numerals 17 and 17 denote a pair of electrode unit covers, which form cavities 18 and 18. 19, 19 are gas introduction pipes to the cavities 18, 18, 20 and 20 are gas discharge pipes, 21 and 21 are partition walls for separating the cavity 18 upstream and downstream, 22 is an exhaust blower, and 23 is a high-frequency power supply device. 4 includes a high-frequency oscillator 12, a step-up transformer 13, and a PLL circuit 15 shown in FIG.
[0062]
In the electrode section 16, the rectified reaction gas entering the cavity 18 from the gas introduction pipe 19 flows through the gap between the plate electrodes 2 and 2 in one direction because it is blocked by the partition wall 21, and the gas exhaust pipe 20 and the exhaust gas The air is exhausted through the blower 22.
[0063]
A description will be given of the result of an experiment performed with the high-frequency power supply device 23 (the high-frequency power supply system in FIG. 4) that follows the resonance frequency of the electrode structure.
[0064]
Helium, argon, nitrogen, oxygen, and air alone or as a mixture were used as reaction gases. The generation of the micro arc depends on the flow rate of the reaction gas, and the higher the flow rate, the less the micro arc. In the case of helium alone at normal pressure, the introduction pressure from the gas introduction pipe 19 is set to 0.1 kg / cm. ² Then, the micro arc disappeared. Further, it has been found that it is preferable to exhaust from the exhaust blower 22 an amount exceeding the amount introduced from the gas introduction pipe 19. When such a gas introduction method is employed, an effect of preventing residues and the like of a substrate to be processed from being re-adhered to the substrate during processing has been observed.
[0065]
【The invention's effect】
In the plasma surface treatment method of the present invention, a reactive gas is injected from both the introduction side and the discharge side of the substrate to be treated toward the gap between the pair of opposed electrodes so as to be confined in the gap. For this reason, the gas once excited and ionized by the high frequency is confined in the vicinity of the discharge surface, enabling stable and uniform plasma generation with a minimum gas flow rate, and the length of the electrode in the direction of passage of the substrate to be processed. Enables uniform plasma generation in any direction.
[0066]
When the gas injection port of the plasma surface treatment apparatus of the present invention is provided in each space of the gap bisected by the substrate to be processed with respect to the introduction opening and the discharge opening, the reaction gas rectified by the cavity is formed. Is supplied separately to the front and back surfaces of the substrate to be processed, and the dielectric constant of the front and back surfaces of the substrate to be processed during plasma generation is made uniform, so that uniform plasma can be generated without being affected by the passing state of the substrate to be processed. .
[0067]
Assuming that the inclination of the injection direction of the gas injection port with respect to the substrate to be processed is 5 ° to 45 °, the injection pressure of the reactive gas is caused to flow along the surface of the substrate to be processed while acting even inside the electrode gap. Therefore, even if the electrode length in the direction of passage of the substrate to be processed becomes large, the plasma in the gap can be made uniform.
[0068]
The plasma surface treatment apparatus in which the flow path of the cooling liquid is formed in the pair of electrodes suppresses overheating of the electrodes and prevents thermal damage to the substrate to be processed.
[0069]
The plasma surface treatment apparatus of the present invention is provided with a PLL circuit in a high-frequency oscillator for supplying high-frequency power having a sinusoidal waveform to a pair of electrodes via a step-up transformer, and the dielectric constant of the electrode gap is controlled by a plasma generation condition such as a reactive gas species. Therefore, even if it fluctuates, the resonance condition on the load side can be ensured and the distortion of the supply voltage can be prevented, and stable plasma can be continuously generated with low supply power.
[0070]
When the high-frequency power supply system using the PLL circuit is combined with the above-described reaction gas supply system of the present invention, the effect of obtaining a stable and uniform plasma is maximized.
[0071]
The above-described plasma surface treatment apparatus is easy to operate and causes little damage to the substrate. Therefore, various surface treatments for manufacturing a semiconductor device can be performed by using the following plasma surface treatment method.
[0072]
By heating the substrate temperature of the substrate to be processed from room temperature to a predetermined temperature, the plasma surface treatment method for simultaneously performing the drying, heating, and surface modification can obtain a high processing ability.
[0073]
It can be used as a plasma surface treatment method for performing surface modification for improving adhesion before a coating process of various chemicals in a semiconductor wafer treatment process. Since the surface modification is performed very frequently in the manufacturing process of the semiconductor device, the high processing capability of the device of the present invention is effective in reducing the number of steps.
[0074]
It can be used as a plasma surface treatment method for performing surface modification for improving adhesion before depositing a metal thin film or a dielectric thin film using a CVD or sputtering apparatus. Also in this method, the man-hour can be reduced due to the high processing capacity of the apparatus of the present invention.
[0075]
It can be used as a plasma surface treatment method for drying the wafer surface in various drying processes of an IC manufacturing process. This method has the advantage that no residue is left on the wafer surface and there is no environmental pollution due to waste liquid.
[Brief description of the drawings]
FIG. 1 is a sectional view of an electrode portion of a surface treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the electrode section of the surface treatment apparatus according to the embodiment of the present invention, cut in a direction orthogonal to FIG.
FIG. 3 is a sectional view taken along line AA of FIG. 2;
FIG. 4 is an electrical configuration diagram of the surface treatment apparatus of the present invention in which a high-frequency oscillator is connected to the electrode section.
FIG. 5 is an equivalent circuit diagram when the parallel resonance circuit formed by the electrode section and the secondary side of the step-up transformer in FIG. 4 satisfies resonance conditions.
6 is a diagram showing a change in impedance Z of the parallel resonance circuit and a change in power consumed in the electrode unit with respect to a frequency f of a high-frequency voltage supplied to the parallel resonance circuit in FIG. 4 in relation to a resonance frequency.
FIG. 7 is a diagram showing a result of an experiment of modifying a glass surface by plasma irradiation using air as a reaction gas.
FIG. 8 is a cross-sectional view of an electrode part which is another embodiment of the surface treatment apparatus of the present invention.
[Explanation of symbols]
1 Electrode section
2 Plate electrode
3 Solid dielectric
4 Coolant supply pipe
5 Substrate to be processed
6 Discharge surface
7 Transport rollers
8, 17 Electrode cover
9,18 Cavity
10 Gas inlet
11 Gas injection port
12 High frequency oscillator
13 Step-up transformer
14 Parallel resonance circuit
15 PLL circuit
19 Gas inlet pipe
20 Gas exhaust pipe
21 Partition wall
22 Exhaust blower
23 High-frequency power supply device

Claims (10)

A gap between a pair of counter electrodes covered with a solid dielectric is filled with a reaction gas at a pressure close to the atmospheric pressure, and a high-frequency voltage is applied to the counter electrodes to generate plasma in the gaps. In the processing device,
With the introduction opening and discharge opening of the substrate to be opened, the gap between the counter electrodes is separated from the external space, and the reaction gas is injected and supplied so as to confine the reaction gas from both the introduction opening and the discharge opening toward the gap. A plasma surface treatment method. A gap between a pair of counter electrodes covered with a solid dielectric is filled with a reaction gas at a pressure close to the atmospheric pressure, and a high-frequency voltage is applied to the counter electrodes to generate plasma in the gaps. In the processing device,
With the introduction opening and the discharge opening of the substrate to be opened, the partition wall separating the gap between the counter electrodes from the external space, and the reaction gas so as to be confined toward the gap from both the introduction opening and the discharge opening. Equipped with a gas injection port for injection supply,
The plasma surface treatment apparatus according to claim 1, wherein the gas injection port is provided in each space of the gap divided by the substrate to be processed, with respect to the introduction opening and the discharge opening. The injection direction of a gas injection port for supplying a reaction gas into a gap along a substrate to be processed has an inclination of 5 ° to 45 ° with respect to a surface of the substrate to be processed. Plasma surface treatment equipment. The plasma surface treatment apparatus according to claim 2, wherein a flow path of a cooling liquid is formed in the electrode. A gap is formed to pass the substrate to be processed in opposition, and a pair of electrodes receiving the supply of the reaction gas at a pressure near the atmospheric pressure is supplied to the gap, and a high frequency voltage having a sinusoidal waveform is supplied to the electrodes via a boosting transformer. A plasma surface, comprising: a high-frequency oscillator; and a PLL circuit that causes an oscillation frequency of the high-frequency oscillator to follow a fluctuation in a resonance frequency of a parallel resonance circuit that occurs when the electrode and the secondary side of the step-up transformer are connected. Processing equipment. A high-frequency oscillator that supplies a high-frequency voltage having a sinusoidal waveform to a pair of electrodes via a step-up transformer; and a change in resonance frequency of a parallel resonance circuit that occurs when the electrodes and the secondary side of the step-up transformer are connected. The plasma surface treatment apparatus according to any one of claims 2 to 4, further comprising a PLL circuit that tracks an oscillation frequency. Simultaneous treatment of drying, heating and surface modification by heating the substrate temperature of the substrate to be processed from a normal temperature to a predetermined temperature using the plasma surface treatment apparatus according to any one of claims 2 to 6. A plasma surface treatment method. Prior to the step of applying various chemicals and resists in a semiconductor wafer processing step, surface modification for improving adhesion is performed using the plasma surface treatment apparatus according to any one of claims 2 to 6. A plasma processing method characterized by the above-mentioned. The plasma surface treatment according to any one of claims 2 to 6, before depositing a metal thin film or a dielectric thin film on the processing substrate or a thin film formed on the processing substrate using a CVD or a sputtering apparatus. A plasma processing method comprising performing surface modification for improving adherence using an apparatus. 7. A plasma surface treatment method in which a wafer surface is dried using the plasma surface treatment apparatus according to claim 2 in a drying step after wafer cleaning and wet etching in an IC manufacturing process. .

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