JP3723794B2 - Electrode structure of plasma surface treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the structure of an electrode for plasma generation in a plasma surface treatment apparatus that performs surface treatment such as etching, film formation, surface modification, and cleaning of an object to be processed by plasma, and particularly in a so-called remote type plasma surface treatment apparatus. The present invention relates to an electrode structure.
[0002]
[Prior art]
In a plasma surface treatment apparatus, a treatment gas is introduced between a pair of electrodes (plasma space) and an electric field is applied to generate plasma, which is applied to an object to be treated to perform a desired surface treatment. The pair of electrodes includes, for example, two metal conductor flat plates arranged in parallel, and a solid dielectric made of ceramic or the like is coated on the opposing surfaces of these flat plates by thermal spraying or the like (see, for example, Patent Document 1). ).
A so-called remote type plasma surface treatment apparatus is also known in which an object to be processed is arranged outside a pair of electrodes and a processing gas that is turned into plasma is sprayed toward the object (for example, see Patent Document 2).
[0003]
[Patent Document 1]
JP 11-236676 A (paragraph 0049 on page 5, FIG. 9)
[Patent Document 2]
JP 11-251304 A (first page, FIG. 2)
[0004]
[Problems to be solved by the invention]
In the conventional plasma surface processing apparatus, in order to secure a space for passing the processing gas between the pair of electrodes and generating the plasma, a space maintaining means such as a spacer for maintaining a predetermined space between the electrodes is required separately. It was. In addition, when the plasma space between the electrodes and the processing gas blowout port at the downstream end thereof extend in a slit shape, for example, the processing gas is dispersed and uniformed in this extending direction and then introduced into the plasma space. Separately, a means for dispersing and homogenizing was necessary.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention introduces a processing gas into a plasma space between a pair of opposed electrodes and plasmaizes (activates) it by an applied electric field to form an object to be processed (base material, In the so-called remote-type plasma surface treatment apparatus that blows off to a workpiece, each of the pair of electrodes is a dielectric plate as a solid dielectric layer provided on the opposing surface of the electrode body and at least the other electrode of the electrode body The two dielectric plates are abutted in a palmed state and sandwiched between both electrode bodies, and a concave groove serving as the plasma space is formed on the abutting surface of at least one of the dielectric plates. The concave groove is opened at the boundary between the front end surfaces of the plate that should face the workpiece, forming a blowout port at the downstream end of the plasma space. This eliminates the need for a separate spacing maintaining means for maintaining the spacing between the electrodes at a predetermined level, thereby reducing the number of parts and making the structure compact.
[0006]
Further, it is desirable that a gas homogenization path for uniformizing the processing gas in the direction along the boundary is formed between the pair of dielectric plates. This eliminates the need for a separate gas uniformizing means, and can further reduce the number of parts. In this case, a pair of dielectric plates are extended from the electrode body to the base end side facing away from the object to be processed, the gas uniformizing path is formed in the extending portion, and the space in the gas uniformizing path is formed. May be continued. Furthermore, the extension part is formed with a recess in which the gas homogenization path is divided in half on the opposing surfaces, the pair of extension parts are butted together, and the gas splitting path is aligned. May be formed.
[0007]
The concave groove expands along the boundary between the distal end surfaces of the pair of dielectric plates as it approaches the distal end portion that should face the workpiece side from the base end portion that should face the opposite side of the electrode. It is desirable that the branches be branched like this. As a result, the processing gas can be dispersed and blown out in the process of passing through the space, and the configuration can be made more compact.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 and 2 show a plasma surface treatment apparatus M1 according to a first embodiment of the present invention. The apparatus M1 includes a processing gas source 1, a pulse power source 2 (electric field applying means), and an electrode unit 10. The processing gas source 1 stores a processing gas corresponding to the purpose of the plasma surface treatment. The pulse power source 4 (electric field applying means) outputs a pulse voltage to the electrode body 21. It is desirable that the rise time and / or fall time of this pulse is 10 μs or less, the electric field strength is 1-1000 kV / cm, and the frequency is 0.5 kHz or more.
[0009]
Although detailed illustration is omitted, the electrode unit 10 is supported by the gantry while being accommodated in the nozzle head. Below the electrode unit 10, a large-area plate-like base material (object to be processed) W is set, and the base material W is subjected to surface treatment such as film formation, etching, and surface modification. It is like that.
[0010]
The electrode unit 10 includes a pair of electrodes 20 and 30 that are separate from each other. The electrodes 20 and 30 face each other in the front-rear direction (left and right in FIG. 1) and are abutted and integrated. The electrodes 20 and 30 include electrode bodies 21 and 31 made of conductive metal, respectively, and a dielectric plate 25 as a solid dielectric layer provided on a surface of the electrode body 31 facing the other electrode. The main body 21 of the electric field applying electrode 20 on the rear side has a quadrangular cross section and extends long to the left and right (in the direction orthogonal to the paper surface in FIG. 1). The pulse power source 2 is connected to the electric field applying electrode main body 21 via a feeder line 2a. A main body 31 of the ground electrode 30 on the front side has the same shape as the electric field applying electrode main body 21 and extends to the left and right. A ground wire 3a extends from the ground electrode body 31 and is grounded.
[0011]
The dielectric plate 25 of the electric field applying electrode 20 is made of a solid dielectric plate such as ceramic, and extends long to the left and right according to the long electrode body 21. As shown in FIG. 2, the dielectric plate 25 starts from the center of the upper edge and goes downward (the tip that should face the workpiece) in the left and right longitudinal direction (the tips of the dielectric plates 25 and 35). A tree-like groove 25x branching over a plurality of stages so as to expand (along the boundary between the planes) and a recess 25y connected to a number of branches at the end of the tree-like groove 25x are formed. The recess 25y extends over substantially the entire length of the dielectric plate 25 and reaches the lower end surface. The tree groove 25x and the recess 25y constitute a “concave groove to be a plasma space”.
[0012]
Similarly, the dielectric plate 35 of the ground electrode 30 is formed of a solid dielectric plate and extends long to the left and right in accordance with the ground electrode body 31. Although detailed illustration is omitted, the dielectric plate 32 is also formed with a tree-like groove 35x and a recess 35y having the same shape as the dielectric plate 25 of the electric field applying electrode 20 (see FIG. 1).
[0013]
The two dielectric plates 25 and 35 are abutted to each other and bonded together, and are sandwiched between the electrode bodies 21 and 31 from both the front and rear sides. As a result, the tree-like grooves 25x and 35x of the dielectric plates 25 and 35 are joined together to form a tree-like passage (gas homogenization path, gas dispersion path) 10x. The upstream end of the tree-like passage 10x is opened on the border of the upper surface each other of the dielectric plate 25 and 35, and has a supply port 10x _IN. The process gas source 1 via the gas supply pipe 1a is connected to the supply port 10x _IN.
Further, the recesses 25y and 35y are joined together to form a gas blowing passage 10y continuous with the passage 10x. The lower end of the passageway 10y is opened to the border of the lower surface to each other of the case body 22, 32 constitutes the outlet 10y _OUT.
The passages 10x and 10y are substantially entirely interposed between the electrode bodies 21 and 31 to form a “plasma space”.
[0014]
The operation of the plasma surface treatment apparatus M1 having the above configuration will be described.
Process gas from the process gas source 1, via the gas supply pipe 1a, is introduced into 10x tree-like passage from the supply port 10x _IN. Then, the tree-like passage 10x moves downward to the passage 10y while being uniformly dispersed in the longitudinal direction. On the other hand, an electric field is applied between the electrode bodies 21 and 31 by the pulse power source 2. As a result, glow discharge is generated in the passages 10x and 10y. As a result, process gases are sequentially plasma in the course of dispersion distribution of the tree-like passage 10x, after being further plasma even gas blowout passage 10y, toward the outlet 10y _OUT at the lower end to the substrate W blowout Is done. Thus, a desired surface treatment can be performed at once in the longitudinal direction of the substrate W and uniformly.
[0015]
As described above, according to the device M1, the dielectric plates 25 and 35 are abutted with each other in a palmed state, and are further held between the electrode main bodies 21 and 31, thereby maintaining a predetermined interval between the electrode main bodies 21 and 31. be able to. Therefore, no separate spacing maintaining means is required, the number of parts can be reduced, and the structure can be made compact. Further, the gas passages 10x and 10y can be formed by bringing the dielectric plates 25 and 35 together, and the processing gas can be converted into plasma while being dispersed and uniformed in the passages 10x and 10y. Therefore, a separate gas dispersion / uniformization means is unnecessary, the number of parts can be further reduced, and the configuration can be further downsized.
[0016]
Next, another embodiment of the present invention will be described. In the following embodiments, the same configurations as those of the above-described embodiments are denoted by the same reference numerals in the drawings, and the description is simplified.
3 and 4 show a second embodiment of the present invention. In the plasma surface treatment apparatus M2 according to this embodiment, as in the apparatus M1, the electrode unit 20 includes a pair of electric field application electrodes 20 and a ground electrode 30 that are separate from each other. , It is integrated by being butted. Each electrode 20, 30 includes a long electrode body 21, 31 and a dielectric case 22, 32.
[0017]
The dielectric case 22 of the electric field applying electrode 20 includes a case main body 23 and a lid 24 that extend to the left and right according to the long electrode main body 21. The case body 23 and the lid 245 are made of a solid dielectric such as ceramic. The case body 23 is formed with an internal space 23 a that opens to the back surface opposite to the ground electrode 30. The electric field applying electrode main body 21 is detachably accommodated in the internal space 23 a, and the rear opening of the internal space 23 a is closed with a lid 24. In the case main body 23, a tree-like groove 25x and a concave portion 25y similar to those in the first embodiment are formed in the opposing wall 25A (dielectric plate) that forms the inner wall of the internal space 23a and should face the ground electrode 30. (FIG. 4).
The dielectric case 22 has a function as a solid dielectric layer surrounding the electric field applying electrode main body 21. Therefore, the facing wall 25A has a function as a solid dielectric layer to be provided on the surface of the electric field applying electrode body 21 facing the ground electrode 30. The power supply line 2 a may be drawn out through the case body 23 or through the lid 24.
[0018]
Similarly, the dielectric case 32 of the ground electrode 30 includes a case body 33 made of a solid dielectric and a lid 34 that extend to the left and right according to the ground electrode body 31. The case body 33 is formed with an internal space 33 a that opens to the back surface opposite to the electric field applying electrode 20. The ground electrode main body 31 is detachably accommodated in the internal space 33a, and the back opening of the internal space 33a is closed with a lid. In the case main body 33, a tree-like groove 35x and a recess 35y similar to the above-described opposing wall 25A are formed in the opposing wall 35A (dielectric plate) that constitutes the inner wall of the internal space 33a and should be opposed to the electric field applying electrode 20. (See FIG. 3).
The dielectric case 32 has a function as a solid dielectric layer surrounding the ground electrode body 31. Therefore, the facing wall 35A has a function as a solid dielectric layer to be provided on the surface of the ground electrode body 31 facing the electric field applying electrode 20. The ground wire 3a may be pulled out through the case body 33 or through the lid 34.
[0019]
And the opposing surfaces of both the electrodes 20 and 30, that is, the opposing walls 25A and 35A are abutted to each other and bonded together. (The opposing walls 25A, 35A are sandwiched from the front and rear sides by the electrode bodies 21, 31.) Thereby, the tree-like grooves 25x, 35x of the opposing walls 25A, 35A are joined together to form a tree-like passage ( (Gas homogenization path, gas dispersion path) 10x is formed, and the recesses 25y and 35y are joined together to form a gas outlet passage 10y connected to the passage 10x.
[0020]
According to the plasma surface treatment apparatus M2 according to the second embodiment, the entire electrode bodies 21 and 31 are covered with the dielectric cases 22 and 32 as solid dielectric layers. Also, abnormal discharge can be prevented at the back and edges. Further, when dirt such as a film adheres to the cases 22 and 32, the electrode main bodies 21 and 31 can be taken out, and only the cases 22 and 32 can be cleaned by immersing them in a chemical solution such as a strong acid. It can be simplified.
[0021]
5 and 6 show a third embodiment of the present invention. In the plasma surface treatment apparatus M3 according to this embodiment, the case main bodies 23 and 33 are extended above the electrode main bodies 21 and 31, respectively. The gas uniformizing portion 11 is constituted by these upper extending portions of the pair of case main bodies 23, 33, and the electrode facing arrangement portion 12 is constituted by the lower side portions.
[0022]
The upper part (gas homogenization part 11) of the case body 23 on the electric field application side has two upper and lower half expansion chambers 23b and 23d partitioned by a horizontal partition wall 26, and has a substantially E-shaped cross section. ing. The half expansion chambers 23b and 23d are opened toward the case main body 33 on the ground side. Similarly, the upper part (gas uniformizing part 11) of the case body 33 on the grounding side is divided into two upper and lower halved expansion chambers 33b and 33d that are partitioned by the horizontal partition wall 36 and open toward the electric field application side case body 23. Have.
[0023]
An inner space 23 a that opens to the back surface opposite to the ground electrode 30 is formed in the lower portion (electrode facing arrangement portion 12) of the case body 23 on the electric field application side. The electric field applying electrode main body 21 is detachably accommodated in the internal space 23 a, and the back opening of the internal space 23 a is closed with a lid 24. In the case main body 23, a concave wall (concave groove) 25a is formed on the surface facing the electrode 30 on the facing wall 25A (dielectric plate) that forms the inner wall of the internal space 23a and should face the ground electrode 30. . The recess 25a extends over substantially the entire length of the case main body 23 and reaches the lower end surface of the case main body 23 (the front end surface that should face the workpiece).
[0024]
Similarly, an inner space 33 a that opens to the back surface on the opposite side of the electric field applying electrode 20 is formed on the lower side (electrode facing arrangement portion 12) of the case main body 33 on the ground side. The ground electrode main body 31 is detachably accommodated in the internal space 33a, and the back opening of the internal space 33a is closed with a lid. In the case body 33, a concave wall 35 </ b> A is formed on the surface facing the electrode 20 on the facing wall 35 </ b> A (dielectric plate) that forms the inner wall of the internal space 33 a and should face the electric field applying electrode 20. The recess 35a extends over substantially the entire length of the case main body 33 and reaches the lower end surface of the case main body 33 (the front end surface that should face the object to be processed).
[0025]
The opposing edges of the upper and left and right sides of the pair of case bodies 23 and 33 are abutted. Thereby, in both gas equalization parts 11, upper half expansion chambers 23b and 33b are combined, and the 1st expansion chamber 11b is formed, and lower half expansion chambers 23d and 33d are combined and lower side The second expansion chamber 11d is formed. These expansion chambers 11b and 11d extend to the left and right, and also extend in the front-rear width direction, and have a sufficiently large volume.
[0026]
On the upper plate of the pair of case main bodies 23 and 33, a supply port 11a is formed at the center in the longitudinal direction of the opposing edges. The processing gas source 1 is connected to the supply port 11a through a gas supply pipe 1a. The first expansion chamber 11b is connected to the supply port 11a.
[0027]
Between the opposing edges of the partition walls 26 and 36 of the pair of case bodies 23 and 33, a slit-shaped gap 11c (pressure loss forming path) is formed. The upper and lower expansion chambers 11b and 11d are connected via the gap 11c.
In the pair of case bodies 23 and 33, a slit-like gap 11 e (introduction path to the plasma space) is formed between the opposing edges of the boundary plates 27 and 37 between the gas homogenizing portion 11 and the electrode facing arrangement portion 12. ing. The second expansion chamber 11d is connected to the plasma space 12a described later via the gap 11e. The supply port 11a, the expansion chamber 11b, the gap 11c, the expansion chamber 11d, and the gap 11e constitute a “gas homogenization path”.
[0028]
Further, in the electrode facing arrangement portion 12 of both case bodies 23 and 33, the concave portions 25a and 35a are joined together to form a plasma space 12a. The plasma space 12a opens to the lower surfaces of the case bodies 23 and 33, and configures a blowout port 12a _OUT that is elongated to the left and right.
[0029]
In the plasma surface processing apparatus M3 of the third embodiment, the processing gas from the processing gas source 1 is supplied to the supply port 11a through the gas supply pipe 1a. After being introduced into the first expansion chamber 11b and expanded (high conductance), the gap 11c is squeezed to cause pressure loss (low conductance), and then introduced into the second expansion chamber 11d and expanded again. Is done. Furthermore, it is squeezed by the gap 11e and causes pressure loss again. Thus, by alternately expanding and constricting, the processing gas can be sufficiently introduced in the left-right longitudinal direction and then introduced into the plasma space 12a. Then, by applying an electric field between the electrode bodies 21 and 31, the processing gas is turned into plasma. This plasma-ized processing gas is blown to the base material W from the blowout port 12a _{OUT at the} lower end.
[0030]
According to the apparatus M3, since the gas homogenizer 11 is integrally incorporated in the cases 22 and 32, a separate gas homogenizer is not required, and the number of parts can be further reduced.
In addition, the expansion chamber of the gas homogenizer is not limited to the first and second two stages, and may be provided with three or more stages. The pressure loss forming path that connects these expansion chambers may be configured to have a spot (through small hole) shape instead of a slit shape such as the gaps 11c and 11e.
[0031]
The present invention is not limited to the above embodiment, and various modifications can be made.
For example, the “concave groove serving as the plasma space” may be formed on the opposing surface of at least one of the dielectric plates, and the opposing surface of the other dielectric plate may be flat. Alternatively, it may be formed on one dielectric plate until halfway and the other portion is formed on the other dielectric plate.
The present invention can be applied to any plasma surface treatment under normal pressure or reduced pressure.
[0032]
【The invention's effect】
As described above, according to the present invention, there is no need for a separate distance maintaining means for maintaining a predetermined distance between the electrodes in the plasma surface treatment apparatus, the number of parts can be reduced, and the structure can be made compact. Can do.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a schematic configuration of a plasma surface treatment apparatus according to a first embodiment of the present invention.
2 is a front view of an electric field applying electrode dielectric plate of the electrode unit of the above apparatus along II-II in FIG. 1. FIG.
FIG. 3 is a side sectional view showing a schematic configuration of a plasma surface treatment apparatus according to a second embodiment of the present invention.
4 is a front view of an electric field applying electrode dielectric case of the electrode unit of the device according to the second embodiment along IV-IV in FIG. 3; FIG.
FIG. 5 is a side sectional view showing a schematic configuration of a plasma surface treatment apparatus according to a third embodiment of the present invention.
6 is a front view of an electric field applying electrode dielectric case of the electrode unit of the device according to the third embodiment along VI-VI in FIG. 5; FIG.
[Explanation of symbols]
M1, M2, M3 Plasma surface treatment equipment W Base material (object to be treated)
10x tree-shaped passage (plasma space)
10y Gas blowout passage (plasma space)
11 Gas homogenizer 12a Plasma space 21, 31 Electrode body 25, 35 Dielectric plates 25A, 35A Opposite walls (dielectric plates)
25a Concave (concave groove)
25x Tree-shaped groove (concave groove)
25y recess (concave groove)

Claims (4)

In a plasma surface treatment apparatus that introduces a processing gas into a plasma space between a pair of electrodes arranged opposite to each other and turns it into a plasma and blows it out to a workpiece,
Each of the pair of electrodes includes an electrode main body and a dielectric case made of a solid dielectric material that accommodates the electrode main body , and an opposing wall facing the other electrode of the dielectric case is the other electrode of the electrode main body. A solid dielectric layer provided on the opposite surface of the
The opposing walls of both dielectric cases are abutted, and a concave portion serving as the plasma space is formed on the abutting surface of the opposing walls of at least one of the dielectric cases, and the tip surfaces of the pair of opposing walls that should face the workpiece side An electrode structure of a plasma surface treatment apparatus, wherein the recess is opened at a boundary . An inner space for housing the electrode body in the dielectric case is opened on the back surface opposite to the other electrode, and an end of the dielectric case on the opening side is projected from the electrode body. The electrode structure of the plasma surface treatment apparatus according to claim 1. The electrode structure of the plasma surface treatment apparatus according to claim 1 or 2 , wherein a gas homogenizing path is formed by the pair of dielectric cases to homogenize the processing gas in a direction along the boundary. 3. The plasma surface treatment apparatus according to claim 1, wherein a tree-like groove is formed on the abutting surface of the facing wall so as to branch along the boundary toward the tip. Electrode structure.

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