JP2000216141A - Surface treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To possibly reduce the distance between a discharge region and a nozzle for jetting a reactive gas in utilization of an atmospheric pressure plasma, make the nozzle size to be freely selectable according to process conditions, improve the discharge stability and enable the good local surface treatment. SOLUTION: A dielectric gas entrance block 37 is coupled with a discharge tube 10 and a metal nozzle chip 25 to define a gas passage extending from a gas feed source to a gas jet hole, and an insulation member 29 hermetically and electromagnetically shuts off the gap between a power and ground electrodes 12, 13 opposed at both sides thereof, so that an electric discharging gas may be discharged under a pressure nearly the atmospheric pressure in the discharge tube 10. A reactive gas is jetted from a gas jet hole as a thin jet and forcedly evacuated out from an exhaust hole opened around it. An insulation member defining an exhaust gas passage with the inside of a nozzle holder 26 and an electrode block 19 are hermetically joined by fitting corresponding protrusions and recesses and using a gasket.

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 an excitation generated in a plasma at or near atmospheric pressure. The present invention relates to an apparatus for locally performing a surface treatment using active species.

[0002]

2. Description of the Related Art Conventionally, the surface of an object to be treated is variously processed at a low cost without using a vacuum facility by utilizing an excited active species generated by a plasma discharge at a pressure near the atmospheric pressure. Surface treatment techniques that can be used are known. For surface treatment with plasma under atmospheric pressure,
A direct discharge method in which a gas discharge is directly generated between the electrode and the object to be processed and is directly exposed to plasma generated by the gas discharge;
Plasma is generated by gas discharge between a pair of electrodes,
There is an indirect discharge method in which an object to be processed is exposed to the excited active species generated thereby.

The indirect discharge method requires a high output because the processing rate is lower than that of the direct discharge method.
This is advantageous in that there is no risk of damage to the processing object due to charge-up. Japanese Patent Application Laid-Open No. Hei 6-190269 by the applicant of the present application discloses that a high frequency voltage is applied between a pair of electrodes from a power source to generate a discharge, and a gas such as helium or oxygen passing through a discharge region between the two electrodes is excited. By ionizing to generate active species, a gas containing the active species is jetted out of the gas outlet as a reactive gas stream to the object to be processed, thereby localizing the object according to the shape of the object and the restriction of the processing range. There has been proposed a surface treatment apparatus having a gun structure that enables efficient dry cleaning.

Further, a typical example of a surface treatment apparatus particularly suitable for such a local surface treatment using atmospheric pressure plasma is disclosed in Japanese Patent Application Laid-Open No. 9-232293 by the present applicant. This conventional apparatus includes, for example, a thin discharge tube made of a dielectric material such as glass having a narrow cross section having an inner diameter of 1 mm or less and a pair of electrodes opposed to each other so as to sandwich the discharge tube. Is arranged facing the surface of the object to be processed. While introducing a predetermined gas into a discharge gas from a gas supply source, a reactive gas containing an excited active species generated by generating a gas discharge between both electrodes,
The gas is sprayed from the nozzle portion as a thin gas flow onto the surface of the workpiece.

[0005]

However, excited active species generated by such plasma generally have an unstable and short life under atmospheric pressure and tend to return to the original stable state in a very short time. is there. Therefore, in the surface treatment of the indirect discharge type described above, the distance between the discharge region and the nozzle or the gas outlet is made as short as possible so that a sufficient amount of excited active species can always reach the surface of the workpiece. There is a need.

Further, a glass material having relatively excellent durability and heat resistance is used for the discharge tube described in the above-mentioned Japanese Patent Application Laid-Open No. 9-232293, but it is still more durable than a metal material. Poor. In particular, when the size of the nozzle at the distal end of the discharge tube is reduced, there is a problem that the durability is remarkably reduced, and the processing is difficult and expensive. However, simply connecting a nozzle formed of a metal material to the tip of the discharge tube may cause a discharge between the electrode and the nozzle.

Further, in order to generate a sufficient amount of excited active species and to make the nozzle diameter smaller to enable more local surface treatment, the discharge tube, the discharge tube, A structure in which a plurality of pipe members are connected to each other from the nozzle to the nozzle is preferable. In this case, helium, which is generally used as a discharge gas, is light and easy to leak, so in order to obtain a stable discharge, each connection part is sufficiently sealed to prevent leakage of the discharge gas particularly near the electrode,
It is necessary to reliably prevent the leakage of the high-frequency electric field from the electrode and the occurrence of creeping discharge due to the leakage.

Therefore, the surface treatment apparatus of the present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a distance between a discharge region and a nozzle for injecting a reactive gas. Provide a surface treatment device that is as short as possible, can freely select the nozzle size as needed, and improves the stability of discharge and enables favorable local surface treatment using atmospheric pressure plasma. Is to do.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and comprises a discharge tube of a dielectric material which defines a gas flow passage therein and is connected at one end to a gas supply source. A power supply electrode and a ground electrode that are arranged opposite to each other with the discharge tube interposed therebetween so as to generate a gas discharge at atmospheric pressure or a pressure in the vicinity of the discharge gas supplied from the gas supply source into the discharge tube; A nozzle made of a metal material connected to the other end of the discharge tube so as to inject a reactive gas containing an excited active species of a discharge gas generated by the gas discharge toward the object to be processed, and both electrodes and the nozzle; And a first dielectric component that blocks the gap between the two.

According to the surface treatment apparatus of the present invention, by forming the nozzle from a metal material separately from the discharge tube, it is possible to cope with processing conditions such as the shape and structure of an object to be processed and dimensions of a processing portion. The nozzle size can be set freely, or the nozzle itself can be easily replaced to change its size,
Further, discharge between the metal nozzle and the electrode can be prevented by the first dielectric component.

In one embodiment, the apparatus further includes an exhaust suction port opened around the gas injection port of the nozzle, and an exhaust passage communicating from the exhaust suction port to the outside. Thereby, the surface-treated reactive gas can be immediately exhausted and collected from the vicinity of the surface of the object to be treated, and for example, contamination due to re-adhesion of organic substances and other reaction products removed by ashing or the like can be prevented, The influence on the surrounding area can be reduced, and the air pollution due to the diffusion of the reactive gas can be prevented.

If the nozzle has a double structure in which a gas injection port is opened at the center of the exhaust suction port, the reactive gas can be efficiently and effectively recovered from the vicinity of the surface of the workpiece immediately after the injection of the reactive gas. In particular, the local processing is less likely to affect the surrounding area, which is convenient.

In one embodiment, the apparatus further comprises a second dielectric component for shutting off the space between the exhaust passage and the electrode, to prevent the discharge of the reactive gas from being generated, and to stabilize the discharge in the discharge tube. Can be enhanced.

The second dielectric component can be composed of a plurality of dielectric members, and the dielectric members adjacent to each other are:
If the corresponding uneven portions are fitted together and joined, it becomes difficult for the gas to flow at the joined portion, so that the used reactive gas exhausted is substantially restricted from leaking from the exhaust passage to the vicinity of the electrode. As a result, the stability of the discharge in the discharge tube can be further improved.

Further, when the joint between the adjacent dielectric members of the second dielectric component is sealed with a gasket such as an O-ring, the leakage of the reactive gas from the exhaust passage to the electrode side can be ensured. It is preferable because it can be prevented.

In another embodiment, one or more passage members made of a dielectric material connected to the discharge tube and / or the nozzle to form a gas passage of the discharge gas to the gas injection port are further provided. A plurality of dielectric members disposed between the electrode and the connecting portion between the passage member, the discharge tube and the nozzle are joined by fitting the corresponding concave and convex portions, thereby supporting local processing. As a result, not only the size of the nozzle can be reduced, but also the discharge gas which may leak from the connecting portion of the gas passage to the vicinity of the electrode can be prevented.

In still another embodiment, at least a portion of one or more of the passage members made of a dielectric material for forming a gas passage of the discharge gas, a discharge tube, and a connection portion between the nozzles is formed, for example. By being sealed with a gasket such as an O-ring, it is possible to reliably prevent leakage of the discharge gas and sneaking around the electrode.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 schematically shows the entire structure of a preferred embodiment of the surface treatment apparatus according to the present invention. The surface treatment apparatus of the present embodiment is for locally treating an object to be treated such as a wafer 2 placed on a table 1, and includes a mounting section 3, a gas introduction section 4, and a discharge section 5.
And a nozzle unit 6. The surface treatment apparatus is arranged such that the base 7 of the mounting section 3 is fixed to the support frame 8 with bolts 9 or the like, and the tip of the nozzle section 6 is located immediately above the wafer 2.

As well shown in FIG.
Has an elongated discharge tube 10 formed of a dielectric material such as glass penetrating vertically through the center thereof. The discharge tube 10
The intermediate portion is inserted into the center hole of the protective member 11 having a rectangular cross section shown in FIG. 3 and made of a dielectric material such as alumina. On both sides of the discharge tube and the protection member, a pair of bar-shaped electrodes 12, 13 extending in the vertical direction are also arranged to face each other.

One end of each of the leads 14 and 15 made of a copper strip is pressed to each of the two electrodes by a pair of pressing members 16a and 16b.
And set screws 17a and 17b. The lead 14 of the power supply electrode 12 is connected to the gas introduction section 4 and the mounting section 3.
And extends upward, and the other end is electrically connected to an external high frequency power supply 18. The lead 15 of the ground electrode 13 is drawn out of the junction between the discharge part 5 and the gas introduction part 4 and is grounded.

The discharge section 5 has a cylindrical shape centered on the discharge tube 10, and has an electrode holder 19 made of a dielectric material for holding the two electrodes 12, 13 insulated from the outside. As shown in FIG. 3, the electrode holder has two holder members 19 that are vertically divided and joined near their diameters.
a and 19b. On one holder member 19a, a recess 20 for accommodating the discharge tube on which the protection member is mounted and both electrodes is formed at the center of the joint surface along the axial direction. In the recess 20, a corrugated plate for biasing each electrode toward the center so that the electrodes 12 and 13 abut against the respective surfaces of the protective member 11 and maintain the discharge tube 10 at the center thereof. Springs 21a and 21b are mounted in the gap between the inner wall of the recess and the electrode.

The other holder member 19b projects into the recess 20 when joined to the holder member 19a, and a projection is formed at the center of the joint surface so that the two electrodes do not move within the recess. 22 are formed. At this time, as shown in FIG. 3, the joint portion between the two holder members is bent at a right angle by fitting the concave shoulder portion 20a to the protruding inner corner portion 22a, thereby flowing gas. Therefore, the inside of the recess 20, that is, the vicinity of the electrode is blocked from the outside.
The electrode holder 19 is integrally held and fixed from the outside by a lower casing member 23 tightened with bolts.

As shown in FIG. 2, the nozzle portion 6 is connected by fitting the lower end of the discharge tube 10 to the center hole thereof, and has a metal nozzle tip 25 having a gas injection opening 24 at the end. Having. Since the nozzle tip 25 is formed of a metal material as a component separate from the discharge tube 10, the gas injection port 24 can be relatively easily processed into a desired fine size suitable for local surface treatment. In addition, the metal nozzle tip is compared with a conventional dielectric such as glass,
High rigidity, excellent durability, little risk of breakage, and easy maintenance. In another embodiment, the diameter and / or shape of the gas injection port can be easily changed by replacing the nozzle tip itself.

Further, the nozzle portion 6 has a substantially cone-shaped metal nozzle holder 26 having a circular hole larger than the outer diameter of the nozzle tip at the lower end thereof. The nozzle tip 25 is inserted through a metal retainer 27 fitted to the outer periphery of the nozzle holder 26 so that its tip penetrates the center of the circular hole of the nozzle holder 26 and projects slightly below the lower end of the nozzle holder. To sit on the bottom of the nozzle holder. Thereby, as shown in FIG. 4, around the gas injection port 24,
An annular exhaust suction port 28 is defined by the gap with the circular hole. The retainer 27 is formed with diametrically concave grooves 27a and 27b on both upper and lower surfaces, respectively.

On the retainer 27, in order to prevent a discharge between the retainer and the nozzle tip and the two electrodes 12, 13, an insulating material made of a dielectric material such as alumina having a truncated conical shape whose side surfaces are inclined downward is used. A member 29 is arranged.
The insulating member 29 has the discharge tube 10 penetrating the center thereof, the protection member 11 protruding into a recess 30 formed in the center of the upper surface, and the lower end thereof abutting against the bottom of the recess. Therefore, the joint between the protection member 11 and the insulating member 29 is bent at a right angle by fitting the lower end of the protection member into the recess 30, making it difficult to flow gas at the joint, and reducing the vicinity of the electrode. Create a space between the lower end of the discharge tube 10 and the nozzle tip 2.
5 from the connection.

On the upper surface of the insulating member 29, a step 31 is formed on the outer peripheral edge. A step 32 corresponding to the shoulder of the step 31 is formed on the lower surface of the electrode holder 19. As shown in FIG. 2, the insulating member and the electrode holder are fitted with a shoulder 31 a of the step 31 at a corner 32 a of the step 32, and a gasket 33 is further formed between the step 31 and the lower surface of the electrode holder 19. It is sandwiched and joined. For the gasket, for example, a silicone rubber seal or the like can be used. Due to the flexibility of the gasket, not only can the joint between the insulating member and the electrode holder be hermetically sealed, but also the dimensional error of the joint when the concave and convex portions of both are fitted can be absorbed.

A narrow conical gap 34 is defined between the nozzle holder and the insulating member and the electrode holder joined as described above. The gap forms an exhaust passage communicating with the exhaust suction port 28 via the concave groove 27a of the retainer. As shown in FIG.
An exhaust pipe 35 that opens into the gap is screwed from the outside to the upper short cylindrical portion 26a, and the exhaust passage is connected to an external exhaust pump via the exhaust pipe.

Here, the insulating member and the electrode holder are
As described above, the uneven portions of the steps are fitted to each other and joined to each other, and the gasket is attached to the joining surface, so that the gap 34 and the inside of the recess 20 of the electrode holder are airtightly shut off. There is no risk that the used reactive gas flowing will flow around the electrodes and cause creeping discharge. Also, the reactive gas leaked from the connection between the discharge tube 10 and the nozzle tip 25 flows into the exhaust passage through the concave groove 27b on the upper surface of the retainer due to the suction force of the exhaust pump, and the used gas is discharged. Both are exhausted.

As shown in FIG. 5, the upper end of the discharge tube 10
Via a connecting member 36 made of an insulating material such as Teflon,
Gas introduction block 37 made of a dielectric material such as alumina
Is connected to the gas passage 38 of the first embodiment. O-rings 39 and 40 are mounted between the connecting member, the discharge tube and the gas introduction block, respectively, to hermetically seal their connection. The gas passage 38 is connected to a pipe 43 connected to an external gas supply source via a joint 42 screwed to an outer surface of an upper casing member 41 holding the gas introduction block. Similarly, an O-ring 44 for hermetically sealing the joint between the joint and the gas introduction block is attached to the joint.

An intermediate member 45 made of a dielectric material such as alumina is formed between the gas introduction block 37 and the electrodes 12 and 13 in a column shape through which the discharge tube 10 passes. The intermediate member has an upper surface abutting against the lower surfaces of the gas introduction block and the joint, and has a recess 46 substantially the same as the recess 30 of the insulating member 29 at the lower center thereof.
Are formed. The upper end of the protection member 11 protrudes into the recess 46 so as to contact the bottom surface thereof. The joint between the protective member and the intermediate member is similarly bent at a right angle by fitting the lower end of the protective member into the recess 46, thereby making it difficult to flow gas and allowing the protective member and the discharge tube to communicate with each other. The gap is blocked from the inside of the recess 20 of the electrode holder, that is, the space near the electrode.

The intermediate casing member 47 which holds the gas introducing block 37 together with the upper casing member 41 and is connected to the lower casing member 23 has a sleeve 48 made of an insulating material such as Teflon so as to cover the entire inner surface thereof. Is installed. The sleeve has its lower end abutted on the upper surface of the electrode holder 19 and has a gasket 49 mounted between its upper end and the lower end of the gas introduction block 37. Thereby, the intermediate casing member 47 and the electrode 1
2, 13 can be airtightly shut off, and discharge between them can be more reliably prevented.

In use, similarly to the conventional surface treatment using atmospheric pressure plasma, a discharge gas suitable for a desired surface treatment is squeezed from the gas supply source through a pipe 43, a joint 42 and a gas passage 38 while discharging the discharge tube. 10 at a predetermined flow rate, and at the same time, from the high-frequency power supply 18 to both electrodes 1.
A predetermined high-frequency voltage is applied between 2 and 13 to generate a stable gas discharge inside the discharge tube. Excited active species are generated inside the discharge tube 10 by the high-density plasma generated by the discharge, and the reactive gas containing the excited active species is further narrowed by the nozzle tip 25, and the thin jet 50 Is sprayed toward the surface of the workpiece 2. As described above, by narrowing the gas flow stepwise, a minute region on the surface of the workpiece 2 can be locally surface-treated.

The used reactive gas after the surface treatment is
The gas is sucked from the exhaust suction port 28 by the operation of the exhaust pump, and is forcibly exhausted to the outside through the exhaust passage together with the reaction product generated by the surface treatment, for example, the organic matter removed by the ashing process. As described above, by providing the gas injection port 24 at the center of the exhaust suction port 28 and at a position slightly protruding from the center, the reactive gas can be reliably supplied from the gas injection port to a target portion of the workpiece 2. After the treatment and after the treatment, the gas can be immediately exhausted from the vicinity of the surface of the object without diffusing into the atmosphere. As a result, there is no possibility that the exhaust gas will pollute or adversely affect the surrounding environment, and re-adhesion of the substance removed from the surface of the processing object will be effectively prevented.

With the configuration of the present invention described above, the gas passage from the gas supply source to the gas injection port 24 and the exhaust passage from the exhaust suction port 28 to the exhaust pipe 35 are airtight and electromagnetically close to the electrodes. Because it is blocked
There is no danger that the discharge gas and the used reactive gas will flow around the electrodes and cause creeping discharge. Therefore, a stable discharge is always obtained in the discharge tube 1, and a good surface treatment can be performed.

When an experiment was conducted in which the surface of the wafer was locally etched using the surface treatment apparatus of this embodiment, the results shown in Table 1 below were obtained. As the discharge gas, a mixed gas of helium and CF ₄ was used. As a comparative example, the same etching treatment was performed using a surface treatment apparatus using atmospheric pressure plasma having a conventional structure described in JP-A-6-190269 or the like.

[0036]

[Table 1]

According to the experimental results, it can be seen that the etching rate is four times that of the conventional case, and the processing efficiency is greatly improved. At the same time, the maximum applied output is 1.
It is understood that the discharge state is good and stable since the amount of helium is increased by 5 times or more and the amount of helium used is reduced. In addition, the processing cost is reduced by 10%. Considering that the processing efficiency is greatly improved, it can be understood that the apparatus of this embodiment is very excellent in cost-effectiveness.

Although the present invention has been described in detail with reference to the preferred embodiments, as will be apparent to those skilled in the art, the present invention can be implemented by adding various modifications and changes to the above embodiments. . For example, between the discharge tube and the nozzle tip,
Alternatively, an additional pipe member can be connected to the gas introduction block, and the reactive gas flow to be injected can be narrowed down while increasing the gas flow rate in the discharge tube.

[0039]

Since the present invention is configured as described above, it has the following effects. According to the surface treatment device of the present invention, since the nozzle is formed of a metal material separately from the discharge tube and connected, the nozzle size can be freely set or the nozzle can be replaced and the size can be appropriately changed. In accordance with the object to be treated and the conditions of the surface treatment, better local treatment can be performed, and discharge between the metal nozzle and the electrode can be prevented by the first dielectric component. The surface treatment can be performed with higher quality and a higher treatment rate. Further, the metal nozzle is relatively easy to process and has high durability, so that the maintainability of the entire apparatus is improved, and the productivity can be further improved and the cost can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the entire structure of an embodiment of a surface treatment apparatus according to the present invention.

FIG. 2 is a partially enlarged view of FIG. 1 showing a main part of the surface treatment apparatus.

FIG. 3 is a transverse sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a partially sectional view of a nozzle portion viewed from below.

FIG. 5 is a partially enlarged view of FIG. 1 showing a gas introduction unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Table 2 Wafer 3 Attachment part 4 Gas introduction part 5 Discharge part 6 Nozzle part 7 Base 8 Support frame 9 Bolt 10 Discharge tube 11 Protective member 12, 13 Bar-shaped electrode 14, 15 Lead 16a, 16b Hold down 17a, 17b Set screw 18 High frequency Power supply 19 Electrode holder 19a, 19b Holder member 20 Recess 20a Recess shoulder 21a, 21b Leaf spring 22 Projection 22a Projection inside corner 23 Casing member 24 Gas injection port 25 Nozzle chip 26 Nozzle holder 27 Retainer 27a, 27b Recess Groove 28 Exhaust air inlet 29 Insulating member 30 Indentation 31 Step 31a Shoulder 32 Step 32a Corner 33 Gasket 34 Gap 35 Exhaust pipe 36 Communication member 37 Gas introduction block 38 Gas passage 39, 40 O-ring 41 Casing member 42 Joint 43 Pipe 4 O-ring 45 intermediate member 46 recess 47 intermediate casing member 48 sleeve 49 a gasket 50 Jet

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroo Miyajima 3-3-5 Yamato, Suwa-shi, Nagano F-term in Seiko Epson Corporation (reference) 4K057 DA20 DB20 DD01 DE08 DE14 DE20 DG08 DG13 DG20 DM06 DM09 DN01 5F004 AA00 BA20 BB11 BB18 BC08 BD01 CA02 DA01 DA22 DA26 DB23

Claims (9)

[Claims] A discharge tube of a dielectric material defining a gas flow passage therein and connected at one end to a gas supply;
A power supply electrode and a ground electrode that are disposed opposite to each other with the discharge tube interposed therebetween so as to generate a gas discharge at a pressure of the atmospheric pressure or a vicinity thereof from the gas supply source to the discharge gas supplied into the discharge tube, A nozzle made of a metal material connected to the other end of the discharge tube so that a reactive gas containing an excited active species of the discharge gas generated by the gas discharge is jetted toward the object to be processed; A surface treatment apparatus, comprising: a first dielectric component that cuts off between an electrode and the nozzle. 2. The surface treatment apparatus according to claim 1, further comprising: an exhaust suction port opened around the gas injection port of the nozzle; and an exhaust passage communicating from the exhaust suction port to the outside. 3. The surface treatment apparatus according to claim 2, wherein the nozzle has a double structure in which the gas injection port is opened at the center of the exhaust suction port. 4. The surface treatment apparatus according to claim 1, further comprising a second dielectric component that cuts off between the exhaust passage and the electrode. 5. The device according to claim 4, wherein the second dielectric component comprises a plurality of dielectric members, and the adjacent dielectric members are joined by fitting corresponding concave and convex portions. Surface treatment equipment. 6. The surface treatment apparatus according to claim 5, wherein a joint between the adjacent dielectric members is sealed with a gasket. 7. One or more passage members made of a dielectric material for forming a gas passage of the discharge gas connected to the discharge tube and / or the nozzle and reaching the gas injection port are further provided. Wherein the dielectric member disposed between the electrode and the connecting portion between the passage member, the discharge tube and the nozzle, and adjacent to each other, is joined by fitting corresponding uneven portions. The surface treatment apparatus according to claim 1. 8. One or more passage members made of a dielectric material for forming a gas passage of the discharge gas connected to the discharge tube and / or the nozzle and reaching the gas injection port are further provided. The surface treatment apparatus according to claim 1, wherein at least a part of a connection portion between the passage member, the discharge tube, and the nozzle is sealed with a gasket. 9. The surface treatment apparatus according to claim 6, wherein the gasket is an O-ring.