JP2001237220A - Local processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a local treatment apparatus capable of improving surface treatment efficiency by stably and efficiently generating gas discharge by protecting an electrode portion from deterioration due to oxidation. SOLUTION: A pair of electrodes 46 and 48 facing each other so as to sandwich a discharge tube 40 through which a processing gas flows, and a lead 30 connecting the one electrode 46 to a high-frequency power supply form an electrode portion. The surface of the electrode portion was subjected to a gold plating process, and a high frequency power supply having an output frequency of 30 MHz or more was used.

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 a local treatment apparatus for locally performing 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 workpiece due to charge-up. JP-A-6-190269 discloses that a high-frequency voltage is applied from a power supply between a pair of electrodes to generate a discharge, and a gas such as helium or oxygen passing through a discharge region between the two electrodes is excited and ionized to be activated. Generates seeds and emits a gas containing this active species as a reactive gas stream from the gas outlet to the object to be processed. There has been proposed a surface treatment apparatus having a gun structure that enables the above.

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

[0005]

However, there have been the following problems in the prior art.

When the gas discharge is continuously generated, the electrode generates heat, and reacts with the surrounding air to oxidize and deteriorate the electrode. For this reason, the performance of the electrode unit is reduced, the generation efficiency of gas discharge is reduced, and the surface treatment efficiency is reduced. In particular, this problem was remarkable when copper was used as the material of the electrode portion.

In particular, when gas discharge is caused by high-frequency power having an output frequency of 30 MHz or more, the high-frequency power is transmitted on the surface of the electrode portion. Was required.

An object of the present invention is to provide a local processing apparatus capable of improving the surface processing efficiency by generating gas discharge stably and efficiently by protecting the electrode portion from deterioration due to oxidation. is there.

Another object of the present invention is to provide a local processing apparatus capable of improving the efficiency of surface treatment by increasing the conduction efficiency of high-frequency power.

[0010]

In order to achieve the above object, in a local processing apparatus according to the present invention, a pair of electrodes arranged opposite each other so as to sandwich a discharge tube through which a processing gas flows, and the electrodes are provided. One of the electrodes was formed with a lead connected to a high-frequency power supply, and the surface of the electrode was plated. For this reason, even if gas discharge is continuously generated and the electrode unit generates heat, the surface of the electrode unit is protected by the plating process, so that the electrode unit can be protected from deterioration due to oxidation. In particular, even when the electrode portion is formed of copper, it is possible to prevent oxidation of the surface of the electrode portion and to reliably ensure performance. Thereby, gas discharge can be generated stably and efficiently.

In the above configuration, the plating may be gold plating. Thereby, the surface of the electrode portion can have a low electric resistivity, the conduction efficiency can be increased, and the generation efficiency of gas discharge can be increased.

In the above configuration, the high-frequency power supply includes:
The output frequency can be 30 MHz or higher. When the output frequency is 30 MHz or more, the high-frequency power is transmitted through the surface of the electrode. By plating the surface portion with gold, the surface portion of the electrode portion has improved conduction efficiency, so that high-frequency power can be conducted effectively and the gas discharge generation efficiency can be increased.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the local processing apparatus of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a local processing apparatus 2 according to this embodiment.
0 is a sectional view. Local processing device 2 in the present embodiment
0 has a casing member 21. The casing member 21 includes an upper casing member 22, a middle casing member 24, a lower casing member 26, and a bottom casing member 28. Each of the upper and lower casing members 22, 24, 26, and 28 is formed by hollowing out the center of a substantially prismatic block into a substantially cylindrical shape. The casing member 21 is in close contact with the upper to bottom casing members 22, 24, 26, and 28 by centering the hollow portions. For this reason, since the casing member 21 can omit or add a part of the casing members 22, 24, 26, and 28, the casing member 2
The size can be adjusted according to the members to be inserted into the device. In the present embodiment, the casing member 21 is formed of aluminum. For this reason, the casing member 2
(1) Electromagnetic waves can be shielded to the outside. The material of the casing member 21 is not limited to aluminum, but may be any material having a shielding function.

A straight discharge tube 40 is arranged on the axis of the casing member 21. The discharge tube 40 has an upper end located on the axis of the upper casing member 22 and a lower end facing the inner wall surface of the bottom casing member 28. On the other hand, a nozzle tip 44 is detachably provided on a surface of the bottom casing member 28 facing the lower end of the discharge tube 40 so as to protrude to the outside, and the lower end of the discharge tube 40 is attached to the nozzle tip 44. Inlaid.
As described above, since the discharge tube 40 and the nozzle tip 44 are formed so as to be separable, the nozzle tip 44 can be replaced with one having a different hole diameter. For this reason, the area to be surface-treated can be adjusted. As a material of the nozzle tip 44, stainless steel (SUS) or aluminum is preferable.

The nozzle tip 44 has an upper end projecting into the bottom casing member 28. The upper end of the nozzle tip 44 has a substantially cylindrical nozzle holder 42.
And is fixedly held. The material of the nozzle holder 42 is preferably stainless steel (SUS) or aluminum.

The discharge tube 40 includes a lower casing member 2
The periphery of the surface facing 6 is covered with a protective member 36. The protection member 36 has an inverted T-shape in which a partition portion 39 is integrally provided at the center of the receiving portion 37. The protection member 36 is attached to the central axis of the partition 39 by a discharge tube 40.
To protect the discharge tube 40. And
The protection member 36 is provided so that the lower surface of the receiving portion 37
2 and is supported by the nozzle holder 42.

Both sides 3 of the partition 39 of the protective member 36
9a and 39b, in the vertical center shown in FIG.
A pair of rod-shaped electrodes 46 and 48 are in contact with each other.
Each of the pair of rod-shaped electrodes 46 and 48 has a substantially rectangular shape, and as shown in FIG.
Are arranged to face each other so as to be straight when viewed from above. The discharge tube 40 penetrates in the vertical direction through the axis of the partition 39 interposed between the rod-shaped electrodes 46 and 48, and causes gas discharge in the penetrating portion of the discharge tube 40. Thus, the pair of rod-shaped electrodes 4
6 and 48 are arranged near the nozzle tip 44. As a result, excited active species such as plasma can be immediately released from the nozzle tip 44 to the outside. For this reason, sufficient excited active species can reach the surface of the object.

The length of the receiving portion 37 in the longitudinal direction is longer than the length of the rod electrodes 46 and 48 in the longitudinal direction. Thereby, the installation area of both electrodes 46 and 48 is secured. In particular, a rod-shaped electrode 46 to which a high-frequency voltage is applied
Does not face the bottom casing member 28 linearly,
The short-circuit of the rod-shaped electrode 46 with the bottom casing member 28 can be prevented. The protection member 36 is made of alumina and quartz, and keeps the electrodes 46 and 48 insulated. The material of the protection member 36 is not limited to this as long as it is an insulator material.

The partition 39 of the protection member 36
The height of the rod-shaped electrode 4 is, as shown in FIG.
It is formed higher than 6,48. The partitioning portions 39a and 39b of the protection member 36 are connected to the rod-shaped electrodes 46 and 4 respectively.
8 is formed sufficiently long in the thickness direction. Thus, the rod-shaped electrodes 46 and 48 are prevented from linearly facing each other. When the rod-shaped electrodes 46, 48 face each other linearly, the protection member 3
There is a possibility that a creeping discharge which is conducted along the surface (creeping surface) of No. 6 may occur. When creeping discharge occurs, the discharge tube 4
The gas discharge within 0 is not generated or the generated gas discharge is stopped. As described above, the protection member 36
Since the partition portion 39 is formed sufficiently long in the thickness direction of the rod-shaped electrodes 46 and 48, creeping discharge can be prevented. For this reason, the gas discharge via the inside of the discharge tube 40 can be reliably generated, and the generated gas discharge can be stably maintained. The rod-shaped electrodes 46 and 48 are formed of aluminum, and each surface is plated with gold. Thereby, the rod-shaped electrodes 46, 4
8 can be prevented from corrosion and oxidation. Since gold has high conductivity, the conduction efficiency of the rod-shaped electrode can be improved. Further, it is possible to prevent the performance of the rod-shaped electrodes 46 and 48 from deteriorating.

A holder member 50 is interposed between the back surface of the rod-shaped electrode 46 and the inner wall surface of the casing member 21. The holder member 50 has a base end in contact with the inner wall surface of the lower casing member 26 and a distal end of the holder member 50 in contact with the back surface of the rod-shaped electrode 46. Thus, the rod-shaped electrode 46 is positioned and held on the protection member 36 side. As the material of the holder member 50, alumina or quartz can be preferably used, but it is not limited to this as long as it is an insulator material.

On the other hand, the other rod-shaped electrode 48 is connected to the extension electrode 4 exposed to the outer surface of the lower casing member 21.
9 are integrally connected. The extension electrode 49 is connected to a ground path (not shown). Thereby, the grounding of the rod-shaped electrode 48 is ensured, and a short circuit in the casing member 21 can be prevented.

On the protection member 36, a substantially cylindrical intermediate member 34 is disposed. The intermediate member 34 is disposed so that a side surface portion faces the inner wall surface of the middle casing member 24. The lower surface of the intermediate member 34 contacts the upper surface of the partition 39 of the protection member 36 to position the protection member 36. Further, a through hole is provided in the central shaft portion of the intermediate member 34, and the discharge tube 40 is inserted into the through hole to protect the discharge tube 40. The intermediate member 34 is formed of Teflon or mica-based ceramics, thereby maintaining insulation to the outside of the discharge tube 40. The intermediate member 34 is preferably made of Teflon or mica ceramic, but is not limited to this as long as it is an insulator material.

On the upper side of the intermediate member 34, an insulating member 3
2 are arranged. The insulating member 32 has a substantially cylindrical shape corresponding to a hollow portion of the upper casing member 22. The insulating member 32 is fitted in a hollow portion of the upper casing member 32. Thereby, the casing member 21 is sealed in the upper surface direction, and a sealed space can be formed inside the casing member 21. The upper surface of the insulating member 32 is formed in a cross-sectional concave shape, and the concave bottom surface is formed corresponding to the upper surface of the intermediate member 34. The lower surface of the insulating member 32 is formed in the shape of an inverted convex section that projects downward, and the lower surface of the inverted convex portion is in contact with the upper surface of the intermediate member 34. The insulating member 32 has a gas inflow hole 33 opened on the peripheral surface. A gas inflow pipe 62 connected to a gas supply source (not shown) is also provided on one side surface of the upper casing member 22, and a distal end of the gas inflow pipe 62 corresponds to an upper opening of the gas inflow hole 33. I have. The gas inlet 33
Extends from the upper opening toward the axial center of the insulating member 32 and is bent downward along the axis at the axial center.
The gas inlet 33 reaches the lower surface of the insulating member 32 and has a lower opening at the lower surface. In the lower opening of the gas inflow hole 33 on the lower surface of the insulating member 32,
The upper end of the discharge tube 40 is inserted. Therefore, the processing gas flowing from the gas inflow pipe 62 is sent out to the upper portion of the discharge tube 40 through the gas inflow hole 33. Also,
A cylindrical pressing member 35 is formed on the inner wall surface of the lower opening of the gas inflow hole 33. The holding member 35 has an inner flange formed thereon, and the inner flange contacts the upper portion of the discharge tube 40 and urges the discharge tube 40 downward. For this reason,
The positioning of the discharge tube 40 can be performed. The insulating member 32 is made of Teflon and performs insulation holding. The insulating member 32 is not limited to this as long as it is an insulator material.

A lead 30 is inserted from the axial center of the upper surface of the upper casing member 22. The lead 30 bends in the diameter direction near the upper surface of the insulating member 32. Then, it descends along the inner wall surface of the upper surface concave portion of the insulating member 32 and penetrates the insulating member 32. As described above, since the bottom surface of the concave portion of the upper surface of the insulating member 32 is formed corresponding to the upper surface of the intermediate member 34, the lead 30 penetrating the insulating member 32 descends so as to contact the side surface of the intermediate member 34. Thereby, the lead 30 can be protected by the intermediate member 34. The lead 30 extends further downward and connects to the rod-shaped electrode 46. As a result, electrical conduction between the lead 30 and the rod-shaped electrode 46 is ensured. The lower end of the lead 30 contacts the receiving portion 37a of the protective member 36, thereby improving the conduction efficiency.

The lead 30 is formed of a plurality of plate members, and the plurality of plate members are stacked and arranged. In the present embodiment, the lead 30 is formed by laminating three plate members. And
In the present embodiment, the upper end of the lead 30 is connected to a high-frequency power source (not shown). In the present embodiment, a high frequency voltage having a frequency of 40.68 MHz is used. High-frequency power generated by a high-frequency power supply (not shown) is conducted from the upper end of the lead 30,
Such high-frequency power is transmitted to the rod-shaped electrode 46 not through the inside of the lead 30 but through the surface of the lead 30. As described above, the lead 30 has a plurality of plate-like members stacked and arranged, but high-frequency power is transmitted through the surface of the lead 30 through the gap between the plate-like members. In the present embodiment, since three plate-shaped members are stacked and arranged, the conduction efficiency of high-frequency power can be tripled. Thus, a high-frequency voltage can be efficiently applied to the rod-shaped electrode 46, and gas discharge can be performed with the high-frequency voltage. By applying the high-frequency voltage to the rod-shaped electrode 46 in this manner,
Electrons vibrate at a high frequency between the rod-shaped electrodes 46 and 48, and the collision of the electrons transforms the processing gas into plasma to become excited active species. Accordingly, high-density plasma can be generated at a high generation rate, and abnormal discharge can be suppressed. Further, even if the volume of the entire lead 30 is reduced, the power is efficiently transmitted by increasing the surface area of the lead 30, and the local processing apparatus 20 can be made compact. Further, the high frequency voltage has a frequency of 30 MHz.
By using an electrode having a thickness of z or more, electrons oscillate between the rod-shaped electrodes 46 and 48 while maintaining the high-frequency voltage conduction efficiency. Can be generated, and the processing efficiency can be improved.

The lead 30 is formed of copper,
Gold plated on the surface. Thereby, oxidation of the lead 30 can be prevented and high-frequency power can be stably conducted.

A hollow area 60 is formed between the casing member 21, the lead 30, the rod electrode 46, and the protective member 36 and the intermediate member 34. A form in which a dielectric such as mica-based ceramics is disposed in the hollow region 60 to insulate the hollow region 60 may be considered. However, FIG.
As shown in (b), the relative permittivity of the mica-based ceramic, which is a dielectric (insulator), is at least five times greater than that in the air atmosphere. In this manner, the provision of the hollow space and the formation of the insulating space is more effective in maintaining insulation when transmitting high-frequency power than the case where the inside of the casing member 21 is filled with the dielectric material. The inventor paid attention. Since the hollow region 60 is formed as described above, insulation is effectively maintained, and leakage current can be minimized. As a result, creeping discharge can be more effectively prevented, and the generation efficiency of excited active species such as plasma can be increased.

An air supply pipe 52 protrudes from one side of the lower casing member 26, and an air discharge pipe 54 protrudes from the other side of the lower casing member 26. Cooling air is supplied from the air supply pipe 52 to the casing member 21.
I will guide you inside. Then, heat exchange inside the casing member 21 is performed through the hollow region 60 in the casing member 21, and the heat is released to the outside of the casing member 21 from the air discharge pipe 54. Thus, it is possible to prevent the electrode from being overheated during the plasma generation process, to keep the temperature inside the casing member 21 constant, and to stabilize the discharge. Then, the electrode portions (rod electrodes 46, 4)
8, it is possible to prevent the extension electrode 49 and the lead 30) from being damaged due to thermal expansion or the like. Note that the structure is not particularly limited to the above structure as long as the electrode portion in the casing member 21 can be air-cooled.

The operation of the local processing device 20 configured as described above is as follows. The local processing apparatus 20 has a tip of the nozzle tip 44 facing above a processing object (not shown).

The processing gas flows into the opening of the discharge tube 40 provided on the side wall of the upper casing member 22. The processing gas advances in the discharge tube 40 and descends in the casing member 21. In the lower casing member 26, a high-frequency voltage is applied to the rod-shaped electrodes 46 and 48, and gas discharge occurs in the discharge tube 40. In this embodiment, since the voltage is applied at a high frequency, a high-density excited active species can be generated. The excited active species is nozzle tip 4
4, the excited active species can be sent out onto the object to be subjected to surface treatment. The object to be processed includes a semiconductor chip and a wafer. Processing steps include etching, ashing,
Although there are modification or thin film formation, the use is not particularly limited to this.

FIG. 3A shows a local processing apparatus 2 according to the embodiment.
FIG. 5 shows a comparison diagram of the ashing rates of the local processing devices of 0 and the comparative example. In the embodiment, the electrode portions (rod electrodes 46, 48,
The local processing apparatus 20 in which the extension electrode 49 and the lead 30) are plated with gold, and the comparative example is a local processing apparatus in which the electrode portion is not plated. As processing conditions, the He flow rate is 2 l / min, and the O ₂ flow rate is 30 ml / min. The distance from the tip of the nozzle tip to the workpiece is
It is about 0.5 mm. The outer diameter of the nozzle tip is 3.0m
m and the inner diameter is 1.5 mm. Comparing the ashing rates in the embodiment and the comparative example under the processing conditions as described above, as shown in FIG.
It can be seen that it can be increased more than twice.

[0033]

As described above, in the local processing apparatus according to the present invention, a pair of electrodes arranged to face each other so as to sandwich a discharge tube through which a processing gas flows, and one of the electrodes is connected to a high-frequency power supply. Form the electrode part with the lead to be connected,
The surface of the electrode portion was plated. For this reason, even if gas discharge is continuously generated and the electrode unit generates heat, the surface of the electrode unit is protected by the plating process, so that the electrode unit can be protected from deterioration due to oxidation. In particular, even when the electrode portion is formed of copper, it is possible to prevent oxidation of the surface of the electrode portion and to reliably ensure performance. Thereby, gas discharge can be generated stably and efficiently.

Further, by performing the plating by gold plating, the surface of the electrode portion can have a low electric resistivity, the conduction efficiency can be increased, and the gas discharge generation efficiency can be increased.

The high frequency power supply has an output frequency of 3
By setting the frequency to 0 MHz or higher, high-frequency power can be effectively transmitted, and the generation efficiency of gas discharge can be increased.

[0036]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a local processing apparatus according to an embodiment of the present invention.

FIG. 2 is a top view and a perspective view of a main part of the local processing apparatus according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the processing efficiency of the local processing apparatus and the relative dielectric constant of a material according to the present invention.

[Explanation of symbols]

 20 Local surface treatment device 21 Casing member 22 Upper casing member 24 Middle casing member 26 Lower casing member 28 Bottom casing member 30 Lead 32 ... Insulating member 33 ... Gas inflow hole 34 ... Intermediate member 35 ... Pressing member 36 ... Protective member 37 ... Receiving part 39 ... Partition part 40 ... Discharge tube 42 ... Nozzle holder 44 Nozzle tip 46 Rod electrode 48 Rod electrode 49 Extension electrode 50 Holder member 52 Air supply pipe 54 Air discharge pipe 60 Hollow area 62 ... Gas inflow pipe

 ──────────────────────────────────────────────────の Continuation of front page (72) Inventor Hiroaki Akiyama 3-3-5 Yamato, Suwa-shi, Nagano F-term in Seiko Epson Corporation (reference) 4G075 AA24 AA30 AA61 BA05 BC06 BC10 BD14 CA47 CA63 EB42 EC01 EC21 FA11 FB02 5F004 BA03 BA20 BB11 DA22 DA26 EA38

Claims (3)

[Claims] An electrode portion is formed by a pair of electrodes opposed to each other so as to sandwich a discharge tube through which a processing gas flows, and a lead connecting one of the electrodes to a high-frequency power supply, and a surface of the electrode portion is formed. A local treatment apparatus characterized in that a plating treatment is applied to the surface. 2. The local processing apparatus according to claim 1, wherein said plating is gold plating. 3. The high frequency power supply has an output frequency of 30M.
3. The local processing apparatus according to claim 2, wherein the frequency is higher than or equal to Hz.