JP2001237224A - Local processing unit - Google Patents

Abstract

(57) [Problem] To provide a local processing apparatus capable of improving the surface processing efficiency by stably and efficiently generating gas discharge. SOLUTION: The casing member 21 has an electromagnetic shielding. A discharge tube 40 for circulating a processing gas is provided in the casing member 21. A pair of electrodes 46 and 48 are arranged on both sides of the discharge tube 40 so as to face each other. An inverted T made of a dielectric material is provided between the discharge tube 40 and the pair of electrodes 46 and 48.
A protection member 36 in the shape of a letter is provided. Thus, the pair of electrodes 46 and 48 and the casing member 21 are shut off.

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. A typical example of a surface treatment apparatus suitable for local surface treatment for such atmospheric pressure plasma is disclosed in JP-A-9-23229.
No. 3 discloses this. 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.

[0004]

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

When a high voltage is applied between electrodes when a pair of electrodes facing each other with a discharge tube interposed therebetween are linearly facing each other, a creeping discharge in which a current flows through the surface of the discharge tube. May occur. When creeping discharge occurs on the discharge tube surface in this manner, gas discharge does not occur in the discharge tube, and the generated gas discharge becomes unstable, so that excited active species are not generated and surface treatment cannot be performed. there were.

The excited active species generated by the above-mentioned plasma is generally unstable at atmospheric pressure, has a short life, and tends to return to its original stable state in a very short time. Therefore, in the above-described surface treatment of the indirect discharge type, 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. For this reason, it is necessary to provide a pair of electrodes sandwiching the discharge tube on the gas outlet side so as to be near the surface of the workpiece. The discharge tube may be covered with a casing made of a metal material to perform electromagnetic shielding.However, as described above, a pair of electrodes sandwiching the discharge tube is provided on the gas outlet side,
It is provided so as to be close to and opposed to the casing bottom. For this reason, when the casing and the electrode can approach each other linearly, abnormal discharge may occur between the electrode and the casing. When such abnormal discharge occurs, gas discharge does not occur in the discharge tube, so that there is a problem that no excited active species are generated and surface treatment cannot be performed.

In particular, when gas discharge is generated with high-frequency power having an output frequency of 30 MHz or more, since the high-frequency power is conducted on the surface of the electrode, the occurrence rate of the abnormal discharge and creeping discharge increases, and However, there is a problem that the conduction efficiency is reduced.

[0008] An object of the present invention is to provide a local processing apparatus capable of improving surface treatment efficiency by stably and efficiently generating gas discharge by preventing creeping discharge and abnormal discharge. .

It is another object of the present invention to provide a local processing efficiency 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, a local processing apparatus according to the present invention has a casing which forms an electromagnetic shield, and a discharge tube for flowing a processing gas through the casing. And a pair of electrodes facing each other on both sides of the discharge tube, a partition portion disposed between the discharge tube and the pair of electrodes, and a receiving portion covering a lower portion of the pair of electrodes. The configuration is such that a protection member, which is a letter-shaped dielectric, is provided. For this reason, a creeping discharge or an abnormal discharge does not occur due to the cutoff between the electrodes and the casing, and a gas discharge can be stably and efficiently generated. Further, since the protection member is formed of a dielectric, the capacitance of the pair of electrodes increases, and the rate of occurrence of gas discharge in the discharge tube can be increased. In particular, when the output frequency is 30 MHz or more, high-frequency power is transmitted through the surface of the electrode, but since the electrodes are shielded from the casing by the protective member, the high-frequency power can be effectively transmitted. As a result, the gas discharge generation efficiency can be increased.

[0011]

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 so that the hollow portions of the top to bottom casing members 22, 24, 26, 28 are aligned. As described above, the casing member 21 includes the upper to bottom casing members 22,
Since a part of 24, 26, 28 can be omitted or added, the size of the casing member 21 can be adjusted according to the member to be inserted therein. In the present embodiment, the casing member 21 is formed of a metal material such as aluminum, and shields electromagnetic waves. 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 surface treatment can be performed with a nozzle having an optimal hole diameter according to the region or shape to be subjected to the surface treatment. In addition, the nozzle tip 44
As a material of the above, 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 the nozzle tip 44 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.

As shown in FIG. 2 (a), the protective member 36 has a pair of rod-shaped electrodes 46, 48 in contact with the center of the partition 39 on both sides 39a, 39b in the vertical direction in FIG. 2 (a). I have. Each of the pair of rod-shaped electrodes 46 and 48 has a substantially rectangular shape. The pair of rod-shaped electrodes 46 and 48 are opposed to each other so as to sandwich the partition 39 of the protection member 36. That is, FIG.
As shown in the figure, the rod-shaped electrode 46, the protective member 36, and the rod-shaped electrode 48 are arranged so as to be linear in a top view.
The discharge tube 40 is vertically penetrated through the axis of the partition portion 39 to generate gas discharge in the penetrated portion of the discharge tube 40. Thus, the pair of rod-shaped electrodes 4
6 and 48 are arranged near the nozzle tip 44,
The excited active species generated by the gas discharge can be immediately released from the nozzle tip 44 to the outside. For this reason, a sufficient amount of excited active species can reach the surface of the workpiece to be disposed near the nozzle tip 44.

The length of the receiving portion 37 in the longitudinal direction is longer than the length of the rod-shaped 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 protective member 36 is made of alumina or 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 twice as long as 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, when applying the voltage to the rod-shaped electrodes 46, 48,
There is a possibility that a creeping discharge which is conducted along the surface (creep surface) of the protection member 36 may occur. When the creeping discharge occurs, the gas discharge does not occur in the discharge tube 40 or the generated gas discharge is stopped. As described above, the partition 39 of the protection member 36 is
8, since it is formed sufficiently long in the thickness direction, 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 electrodes 46 and 48 are formed of aluminum, and the surfaces thereof are plated with gold. Thereby, corrosion due to oxidation of the rod-shaped electrodes 46 and 48 can be prevented. Further, since gold has high conductivity, the conduction efficiency of the rod-shaped electrodes 46 and 48 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 protective 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 and arranged 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 power supply having an output frequency of 40.68 MHz is used. High-frequency power output from a high-frequency power supply (not shown) is supplied from the upper end of the lead 30 to the rod-shaped electrode 46.
However, such high-frequency power is conducted not on the inside of the lead 30 but on the surface of the lead 30. As described above, the lead 30 has a plurality of plate-like members stacked and arranged. For this reason, the high-frequency power is transmitted through the surface of each plate member through the gap between the stacked plate 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 sufficient to generate a gas discharge can be applied to the rod-shaped electrode 46, and the gas discharge can be performed with the high-frequency voltage.

The lead 30 is made 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 provided between the casing member 21, the lead 30, the bar-shaped electrode 46, and the protective member 36 and the intermediate member 34. A configuration in which the periphery of the conduction path is surrounded by a dielectric such as mica-based ceramics and insulated is also conceivable. 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. As described above, the provision of the hollow region 60 to form the insulating space can more effectively maintain the insulation when conducting the high-frequency power than the configuration in which the inside of the casing member 21 is filled with the dielectric. The present inventor paid attention. Since the hollow region 60 is formed in this manner, insulation is effectively maintained during high-frequency power transmission, and leakage current can be minimized.

An air supply pipe 52 projects from one side of the lower casing member 26, and an air discharge pipe 54 projects 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. Damage due to thermal expansion or the like of the electrode portion can be prevented. 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. When performing the surface treatment of the processing target, the local processing apparatus 20 faces the tip of the nozzle tip 44 above the processing target (not shown).

The processing gas for performing the surface treatment flows into the casing member 21 from a gas inflow pipe 62 provided on the side wall of the upper casing member 22. The processing gas flows into the upper portion of the discharge tube 40 through the gas inflow hole 33 of the insulating member 32, and proceeds downward in the discharge tube 40. On the other hand, a high-frequency voltage is applied to the rod-shaped electrode 46 arranged opposite to the discharge tube 40 as described above. When such a high-frequency voltage is applied to the rod-shaped electrodes 46, the electrons vibrate at high frequencies in the vacuum tube 40 interposed between the rod-shaped electrodes 46 and 48. As described above, since the processing gas flows into the vacuum tube 40, the high-frequency oscillating electrons collide with the processing gas and are turned into plasma, thereby generating plasma of excited active species. Therefore, high-density plasma can be generated, the plasma generation rate can be increased, and abnormal discharge can be suppressed. The excited active species can be immediately sent out from the tip of the nozzle tip 44 onto the surface of the workpiece. For this reason, sufficient excitation active species can be sent out onto the object to be processed, and the surface treatment of the object can be performed. The object to be processed includes a semiconductor chip and a wafer. The processing steps include etching, ashing, modification of the surface of the object to be processed, formation of a thin film, and the like, but the application is not particularly limited to this.

FIG. 3A shows a local processing apparatus 2 according to an 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, a pair of 46,
The electrode local processing device 20 in which the casing member 21 is shut off from the electrode 48, and the comparative example is a local processing device having no protective member 36. 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 0.5m
m. The outer diameter of the nozzle tip is 3.0 mm and the inner diameter is 1.5 mm. When the ashing rates of the embodiment and the comparative example are compared under the above processing conditions, FIG.
As shown in (a), the result was obtained that the processing efficiency could be increased three times or more even with the same output.

[0032]

As described above, the local processing apparatus according to the present invention has a casing which forms an electromagnetic shield, a discharge tube through which a processing gas flows is provided in the casing, and a discharge tube for the discharge tube is provided. An inverted T-shaped dielectric composed of a pair of electrodes facing each other on both sides, a partition portion disposed between the discharge tube and the pair of electrodes, and a receiving portion covering a lower portion of the pair of electrodes. Since a certain protective member is provided, creepage discharge and abnormal discharge do not occur due to the cutoff between the electrodes and the casing, and gas discharge can be stably and efficiently generated. Further, since the protection member is formed of a dielectric, the capacitance of the pair of electrodes increases, and the rate of occurrence of gas discharge in the discharge tube can be increased.
In particular, when the output frequency is 30 MHz or more, high-frequency power is transmitted through the surface of the electrode, but since the electrodes are shielded from the casing by the protective member, the high-frequency power can be effectively transmitted. As a result, the gas discharge generation efficiency can be increased.

[0033]

[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 Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/302 H (72) Inventor Hiroaki Akiyama 3-5-5 Yamato, Suwa-shi, Nagano Prefecture Seiko Epson Corporation F term (reference) 4K030 FA01 KA15 KA30 4K057 DA16 DD01 DD10 DE14 DE20 DM02 DM06 DM39 DN01 5F004 AA16 BA06 BA20 BB11 BB32 BD01 BD04 5F045 AA08 AC17 EF02 EF11 EH04 EH08 EH13 EJ05

Claims (1)

[Claims] A discharge tube through which a processing gas flows, and a pair of electrodes disposed on both sides of the discharge tube to oppose each other. An inverted T comprising a partition portion disposed between the pair of electrodes and a receiving portion covering a lower portion of the pair of electrodes.
A local processing apparatus provided with a protection member made of a V-shaped dielectric.