JPH11335869A - Surface treatment and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a large amt. of exciting active seed to arrive at the surface to be treated and to execute treatment with high efficiency at high speed by forming exciting active seed of gas by gas discharge, ejecting a treating gas contg. this exciting active seed onto the object to be treated and simultaneously reducing a boundary layer on the surface of the object to be treated. SOLUTION: While discharge gas is fed from a gas feeding source, high-frequency voltage is applied to a space between electrodes, and gas discharge is generated within a gas passage 12 to form plasma. The action of this plasma generates the exciting active seed of gas. The treating gas contg. this exciting active seed is fed from the gas passage 12 to an intermediate chamber 21, is passed through a supersonic generator 22 and is ejected onto the surface of the object 17 to be treated from a gas ejecting nozzle 20. When the treating gas entered the intermediate chamber 21 passes through the air passage 23 of the supersonic generator 22 at high speed, the oscillation of supersonic frequency is generated. In this way, the treating gas is ejected as a pulsating wave gas stream. On the surface of the object 17 to be treated, the boundary layer of the treating gas is destroyed by the oscillation, and surface-treatment is executed at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment technique for etching, ashing, modifying or forming a thin film on the surface of an object to be treated, and more particularly, to a technique for generating a gas discharge at or near atmospheric pressure. The present invention relates to a method and an apparatus for surface-treating an object to be processed using excited active species generated by plasma.

[0002]

2. Description of the Related Art Recently, as described in, for example, Japanese Patent Application Laid-Open No. Hei 7-245192, a comparative method which does not require vacuum equipment by utilizing excited active species generated by plasma discharge under a pressure near atmospheric pressure. Low cost and simple structure,
Surface treatment techniques for variously treating the surface of an object have been proposed. For surface treatment with plasma under atmospheric pressure,
A direct discharge method that directly exposes a workpiece to plasma generated by a direct discharge between the workpiece and an excited active species generated by the plasma generated by causing a gas discharge between a pair of electrodes. And an indirect discharge method for exposing an object to be processed.

FIG. 6 shows an example of a conventional surface treatment apparatus using an indirect discharge method using atmospheric pressure plasma, in which a narrow gas flow path defined between a pair of parallel plates 1 made of a dielectric material. 2 and a pair of electrodes 3 and 4 disposed on both sides thereof. When a high-frequency voltage is applied between the two electrodes from the power supply 6 while the discharge gas is being supplied from the gas supply source 5, gas discharge occurs in the gas flow path 2 and plasma is generated. The plasma generates excited active species of the gas, and the processing gas containing the excited species is injected from the nozzle unit 7.

An object to be processed 8 is placed on a movable table 9 immediately below the nozzle 7 with a small gap of about 1 to 2 mm. At the lower end of the nozzle portion 7, a processing gas flow path control plate 10 having a certain length in the front-rear direction is provided, and the flow of the processing gas injected from the nozzle portion is placed in a narrow gap with the surface of the workpiece. Has restricted. When the processing gas flows outward, that is, in the exhaust direction, through the gap, the excited active species contained in the processing gas is exposed to the surface of the object to be processed, whereby desired processing is performed on the surface.

[0005]

However, in the above-described conventional surface treatment apparatus, a very thin boundary layer of a gas having a thickness of about several μm, in which the flow stops, is generated on the surface of the object to be treated. Part of the heat reaches the surface of the workpiece only by thermal diffusion, and most of the air is exhausted without reaching the surface of the workpiece. Therefore, the processing speed is slow and the processing efficiency is deteriorated. there were.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a larger amount of surface treatment in an indirect discharge system by plasma discharge under atmospheric pressure. It is an object of the present invention to provide a method and an apparatus capable of causing excited active species to reach a surface of an object to be processed and efficiently processing the surface at a high speed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to achieve the above-mentioned object, and to generate a gas discharge in a predetermined gas at or near atmospheric pressure to excite the gas. Generating active species and injecting a processing gas containing the excited active species onto the surface of the workpiece to expose the surface to the excited active species, while reducing or removing a boundary layer on the surface of the workpiece; Thus, a surface treatment method characterized by treating the surface of an object to be treated is provided.

By injecting the gas flow containing the excited active species while controlling the formation of the boundary layer on the surface of the workpiece, the amount of the excited active species reaching the surface of the workpiece increases, Since new excited active species are continuously supplied, the reaction on the surface of the object to be treated, that is, the surface treatment is promoted.

According to the present invention, the boundary layer is vibrated by the pulsating wave by irradiating the surface of the object with ultrasonic waves.
Can be destroyed.

According to the present invention, for example, the object to be processed is vibrated by, for example, vibrating a table on which the object to be processed is mounted, thereby similarly vibrating the layer of gas in contact with the surface of the object to be processed, thereby forming a boundary layer. It can be broken and its formation difficult.

Further, according to the present invention, by forming a turbulent flow in the processing gas on the surface of the processing object, it is also difficult to form a boundary layer, and at the same time, new excited active species reach the surface of the processing object. Can help you.

According to another aspect of the present invention, there is provided a gas flow path for supplying a predetermined gas, and a gas discharge is generated in the gas in the gas flow path at or near atmospheric pressure. A pair of a power electrode and a ground electrode for generating excited active species of the gas, a nozzle for jetting a processing gas containing the generated excited active species toward the surface of the processing object, and a surface of the processing object And a boundary layer control means for reducing or removing the boundary layer. By configuring the surface treatment apparatus in this manner, the above-described method of the present invention can be realized.

In the embodiment of the present invention, a means for applying vibration to the surface of the object to be processed can be used as such a boundary layer control means, whereby the gas layer in contact with the surface of the object to be processed is vibrated. Breaks down the boundary layer and makes its formation difficult. More specifically, a device that emits ultrasonic waves toward the surface of the object to be processed or a vibration device that vibrates a table on which the object to be processed is placed can be used. Ultrasonic launcher,
It consists of an ultrasonic generator that generates ultrasonic vibrations by passing a processing gas, and when the processing gas is ejected from a nozzle as a pulsating wave flow, the excited active species and ultrasonic waves are simultaneously and continuously irradiated on the surface of the workpiece. Is preferred.

In another embodiment, the boundary layer control means comprises a flow path control plate for regulating the processing gas ejected from the nozzle to flow along the surface of the object to be processed, and the flow path control plate. A plurality of concavities and convexities continuous along the flow direction of the processing gas are provided on the surface facing the object to be processed. Accordingly, a turbulent flow is generated when the processing gas passes through the unevenness, so that a boundary layer is hardly formed, and new excited active species easily reach the surface of the workpiece due to the destruction of the boundary layer.

[0015]

FIG. 1 shows a preferred embodiment of a surface treatment apparatus according to the present invention. This surface treatment device
Two rectangular thin plates 11 made of a dielectric material such as a glass plate
Are arranged to face each other with a small gap, thereby having a narrow slit-like gas flow path 12 defined inside thereof, and a pair of a power supply electrode 13 and a ground electrode 14 disposed so as to sandwich the gas flow path 12. The upper end of the gas flow path 12 is the gas supply source 1
5 and a nozzle unit 16 is attached to the lower end thereof. On the lower side of the nozzle unit 16,
An object 17 is placed on a movable table 18 with a small gap.

The nozzle unit 16 is integrally provided with a processing gas flow control plate 19 extending in the front-rear direction. Similar to the conventional flow path control plate 10 described with reference to FIG. 6, the flow path control plate 19 directs the flow of the processing gas injected from the nozzle unit to a narrow space defined between the processing gas and the surface of the workpiece. Restrict in space. As shown in FIG. 2, the lower surface of the nozzle unit 16 has an elongated linear gas injection port 2.
0 is opened and the gas flow path 12
Is in communication with

At the bottom of the intermediate chamber 21, an ultrasonic wave generator having a well-known structure based on a whistle principle utilizing cavitation of air as described in, for example, JP-A-6-165960 and JP-A-7-60211. A vessel 22 is disposed in a passage leading to the gas injection port 20. The ultrasonic generator 22 has a vertical air passage 23 in which a stenosis part and an expansion part are alternately continuous.
1 and has a lower end communicating with the gas injection port 20.

In use, a high-frequency voltage is applied between the electrodes 13 and 14 from the power supply 24 while a predetermined discharge gas is supplied from the gas supply source 15 in the same manner as in the conventional surface treatment using atmospheric pressure plasma. Then, a gas discharge is generated in the gas passage 12. As a result, plasma is formed, and excited species of the gas are generated by the action of the plasma. The processing gas containing the excited active species enters the intermediate chamber 21 from the gas flow path 12, passes through the ultrasonic generator 22, and is injected from the gas injection port 20 to the surface of the workpiece.

When the processing gas entering the intermediate chamber 21 passes through the air passage 23 of the ultrasonic generator at a high speed, ultrasonic vibration, that is, vibration of the ultrasonic frequency is generated. As a result, the processing gas is jetted as a pulsating wave gas flow, so that an ultrasonic wave is radiated on the surface of the processing target 17 in addition to the excited active species. The excited active species in the processing gas are dispersed at a substantially uniform density over the entire length of the gas injection port 20 by providing the intermediate chamber 21.

On the surface of the workpiece 17 which has been subjected to the ultrasonic waves, the boundary layer of the processing gas is destroyed or its formation becomes difficult due to the vibration, so that excited active species in the processing gas are directly applied to the surface of the workpiece. Contact and react, the desired surface treatment is performed at higher speed. Further, since the processing gas and the ultrasonic wave are supplied simultaneously and continuously, and the new excited active species is constantly supplied to the surface of the processing object, the processing speed and efficiency are further improved.

In the present embodiment, the table 18 is driven in the direction of arrow A to perform the surface treatment while moving the object 17, so that the entire surface of the object to be processed can be efficiently and satisfactorily processed. Naturally, by fixing the table 18 and making the surface treatment apparatus movable, a similarly large area can be treated.

In another embodiment, the ultrasonic generator can be arranged at the gas injection port at the lower end of the gas flow channel 12 without the intermediate chamber. Instead of the ultrasonic generator, a separate device for electrically generating ultrasonic waves, such as a piezoelectric vibrator, can be provided near the gas injection port.

FIG. 3 shows a second embodiment of the surface treatment apparatus according to the present invention.
An example is shown. This surface treatment apparatus is provided with a processing gas flow control plate 26 extending in the front-rear direction to a nozzle portion 25 at the lower end of a gas flow path 12 composed of two parallel glass thin plates 11, similarly to the conventional apparatus of FIG. Is attached,
The point at which the processing gas is directly injected from the nozzle portion onto the surface of the workpiece 17 and the table 2 on which the workpiece 17 is placed
7 is different from the first embodiment in FIG. 1 in that it has a vibration device.

The vibrating device built in the table 27 has a known structure, for example, which is conventionally employed in an electromagnetic vibration type part feeder for aligning and supplying parts to an automatic assembling machine or a processing machine. Can be used. Specifically, the vibration plate and the balancer forming the table upper surface on which the object 17 is placed are spring-supported independently on the fixed base, and the excitation frequency is applied from the power supply 28 to the electromagnet provided on the balancer. The iron plate attached to the vibration plate is magnetically attracted to vibrate the vibration plate at a frequency of several tens Hz to several KHz.

As a result, vibrations of several tens Hz to several KHz are similarly applied to the object to be processed on the table 27, so that the processing gas injected from the nozzle 25
Turbulence when flowing along the surface of the object to be treated. As a result, the boundary layer on the surface of the workpiece is destroyed, and its formation is suppressed or prevented. Therefore, the excited active species contained in the processing gas directly contacts the surface of the workpiece,
In addition, since new excited active species are always replaced and supplied to the surface of the object to be processed, the surface treatment is performed at higher speed and more efficiently.

In another embodiment, the table 27 can be configured to be movable so that the object can be processed while being transported. Depending on the form, weight, etc. of the object to be processed, the object to be processed can be conveyed simultaneously with the surface treatment by the vibration of the table 27. In addition, as the vibration device, those having various structures other than those described above can be used.

FIG. 4 shows a third embodiment of the surface treatment apparatus according to the present invention.
An example is shown. This surface treatment apparatus is the second type shown in FIG.
As in the embodiment, the nozzle portion 25 at the lower end of the gas flow channel 12 is directly jetted onto the surface of the workpiece 17. A control plate 29 is attached.

The flow path control plate 29 of the present embodiment is
5 not only to restrict the flow of the processing gas from the processing object 5 into a narrow gap with the surface of the processing object, but also as shown in FIG. A labyrinth 30 is formed along the gas flow direction. The labyrinth 30 can be formed, for example, by implanting a large number of thin vertical plates at short fixed intervals on the lower surface of the flow path control plate, or by cutting a large number of throttle pieces on the lower surface of a relatively thick plate material. .

By forming the lower surface of the flow path control plate 29 with a fine uneven surface, a large number of narrowed portions and enlarged portions are finely continuous between the flow control plate and the surface of the workpiece. A flow path for the processing gas is formed. The processing gas injected from the nozzle part 25 is throttled when passing through the constricted part and accelerates, and in the enlarged part, merges with the flow of the processing gas which has flowed into the enlarged part first, and is well shown in FIG. To be processed 17
Many small turbulences 31 are generated on the surface. As a result, the boundary layer is destroyed on the surface of the workpiece and its formation is suppressed or prevented, so that the excited active species contained in the processing gas directly contacts the surface of the workpiece, and new active species are always replaced. The surface is then supplied to the surface of the object to be processed, thereby realizing high-speed and efficient surface treatment.

Naturally, the lower surface of the flow path control plate 29 can be formed of an uneven surface having various shapes and structures other than the labyrinth 30 as long as the above-described turbulence effect occurs.

Although the preferred embodiment of the present invention has been described in detail above, the present invention can be implemented by adding various modifications and changes to the above embodiment within the technical scope thereof. For example, the gas flow path can be formed by a circular glass tube or the like instead of a flat plate using two parallel thin glass plates. Also, for example, by using the oscillating table of the second embodiment in the first embodiment or adding a control plate of the third embodiment, it is possible to appropriately combine the configurations of the above embodiments. It is.

[0032]

Since the present invention is configured as described above, it has the following effects. According to the surface treatment method of the present invention, in the surface treatment of the indirect discharge method using the atmospheric pressure plasma, by controlling the formation of the boundary layer on the surface of the object to be treated, the excited active species contained in the injected treatment gas is controlled. Since the amount that can reach the surface of the object to be treated increases and new active species are constantly replaced, it is possible to realize a high-speed and efficient surface treatment. According to the surface treatment apparatus of the present invention, the boundary layer on the surface of the object to be treated can be controlled well, and the surface treatment method of the present invention can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a first embodiment of a surface treatment apparatus according to the present invention.

FIG. 2A is a partially enlarged cross-sectional view of a nozzle portion of FIG. 1, and FIG. 2B is a bottom view thereof.

FIG. 3 is a schematic diagram showing the configuration of a second embodiment of the surface treatment apparatus according to the present invention.

FIG. 4 is a schematic view showing the configuration of a third embodiment of the surface treatment apparatus according to the present invention.

FIG. 5 is a partially enlarged view of FIG. 4;

FIG. 6 is a schematic diagram showing a configuration of a conventional surface treatment apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Parallel plate 2 Gas flow path 3, 4 electrode 5 Gas supply source 6 Power supply 7 Nozzle part 8 Workpiece 9 Table 10 Flow path control plate 11 Thin plate 12 Gas flow path 13 Power supply electrode 14 Ground electrode 15 Gas supply source 16 Nozzle unit 17 Workpiece 18 Table 19 Flow control plate 20 Gas injection port 21 Intermediate chamber 22 Ultrasonic generator 23 Air passage 24 Power supply 25 Nozzle part 26 Flow control plate 27 Table 28 Power supply 29 Flow control plate 30 Labyrinth 31 Turbulence

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/3065 H05H 1/24 H05H 1/24 1/46 A 1/46 H01L 21/302 B

Claims (11)

[Claims] In order to surface-treat an object, a gas discharge is generated in a predetermined gas at or near atmospheric pressure to generate an excited active species of the gas, and the excited active species of the gas is generated. A step of injecting a processing gas containing the method to the surface of the object to be exposed to the excited active species, and a step of simultaneously reducing or removing a boundary layer on the surface of the object to be processed. Surface treatment method. 2. The process of reducing or eliminating the boundary layer,
2. The surface treatment method according to claim 1, comprising a step of irradiating the surface of the object with ultrasonic waves. 3. The process of reducing or eliminating the boundary layer comprises:
2. The surface treatment method according to claim 1, comprising a step of vibrating the object to be treated. 4. The surface treatment method according to claim 3, wherein the object is vibrated by vibrating a table on which the object is placed. 5. The process of reducing or eliminating the boundary layer,
2. The surface treatment method according to claim 1, further comprising a step of generating a turbulent flow in the processing gas on the surface of the processing object. 6. A gas flow path for supplying a predetermined gas, and a gas discharge is generated in the gas flow path at or near atmospheric pressure in the gas flow path, thereby exciting the gas. A pair of a power electrode and a ground electrode for generating seeds, a nozzle for jetting a processing gas containing the excited active species toward the surface of the workpiece, and reducing or removing a boundary layer on the surface of the workpiece. And a boundary layer control means. 7. The surface treatment apparatus according to claim 6, wherein said boundary layer control means comprises means for applying vibration to the surface of said workpiece. 8. The surface treatment apparatus according to claim 7, wherein said vibration applying means comprises an apparatus which emits ultrasonic waves toward said surface of said workpiece. 9. The apparatus according to claim 1, wherein said ultrasonic wave emitting device comprises an ultrasonic generator for generating ultrasonic vibration by passing said processing gas, and injecting said processing gas from said nozzle as a pulsating wave flow. Item 10. A surface treatment apparatus according to item 8. 10. The surface treatment apparatus according to claim 7, wherein said vibration applying means comprises a vibration device for vibrating a table on which said workpiece is placed. 11. A flow path control plate, wherein the boundary layer control means regulates the processing gas to flow along the surface of the processing object, and a surface of the flow path control plate facing the processing object. 7. The surface treatment apparatus according to claim 6, wherein a plurality of concavities and convexities are provided continuously along a flow direction of the processing gas.