JP2008257920A - Plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely fix the center electrode in a plasma treatment device to form two discharge spaces with three electrodes. <P>SOLUTION: A first outside electrode 22L is arranged at one side of the center electrode 21, and a second outside electrode 22 R is arranged at the opposite side. The face of the center side of the first outside electrode 22L is covered with a first dielectric member 32L, and the face of the center side of the second outside electrode 22R is covered with a second dielectric member 32R. A plurality of convex parts 32f are formed at the dielectric members 32L, 32R, these convex parts 32f are contacted with the center electrode 21, and the center electrode 21 is clipped. The neighboring convex parts 32f, 32f become the discharge spaces 32e. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus that converts a processing gas into plasma in a discharge space and contacts an object to be processed outside the discharge space, and more particularly to a plasma processing apparatus in which two discharge spaces are formed between three electrodes.

Patent Document 1 describes a plasma processing apparatus having three electrodes. The three electrodes are arranged side by side. A power source is connected to the center electrode, and the two left and right electrodes are grounded. Two discharge spaces are formed between these three electrodes.
JP 2003-338399 A

  In the structure in which three electrodes are arranged as in the above-mentioned document, an electric field is applied to both sides of the central electrode, and both sides are heated by discharge. It was not easy to fix the center electrode so that it could sufficiently withstand such an electric field or thermal stress.

In order to solve the above problems, the present invention provides a plasma processing apparatus in which a processing gas is introduced into and ejected from first and second discharge spaces and brought into contact with an object to be processed outside the two discharge spaces.
A center electrode;
A first outer electrode disposed on one side of the central electrode;
A second outer electrode disposed on the other side of the central electrode;
A first dielectric member made of a solid dielectric covering the surface of the first outer electrode facing the central electrode and forming the first discharge space between the central electrode;
A second dielectric member made of a solid dielectric covering the surface of the second outer electrode facing the center electrode and forming the second discharge space between the second electrode and the center electrode;
A first convex portion that protrudes toward the central electrode is formed on the first dielectric member,
A second protrusion projecting toward the center electrode is formed on the second dielectric member;
The first convex portion and the second convex portion are applied to the central electrode from both sides.
According to this feature, the central electrode is pressed from both sides by the first dielectric member and the second dielectric member, and the central electrode is deformed or displaced to the first outer electrode side or the second outer electrode side by an electric field or thermal stress. Can be prevented.

    It is preferable that the first dielectric member and the second dielectric member are clamped in the approaching direction by a clamping means. As a result, the first and second convex portions can be pressed against both sides of the central electrode, and deformation and displacement of the central electrode due to an electric field and thermal stress can be prevented more reliably.

  The first convex portion may extend from the side for introducing the processing gas into the first discharge space to the side for ejection. Thereby, the process gas flow in the first discharge space can be guided to the ejection direction side along the first convex portion. The second convex portion may extend from the side for introducing the processing gas into the second discharge space to the side for ejection. Thereby, the process gas flow in the second discharge space can be guided to the ejection direction side along the second convex portion.

  It is preferable that a plurality of the first protrusions are provided at intervals in a direction orthogonal to the extending direction, and a space between two adjacent first protrusions is the first discharge space. In addition, it is preferable that a plurality of the second convex portions are provided at intervals in a direction orthogonal to the extending direction, and a space between two adjacent second convex portions is the second discharge space. Thereby, deformation and displacement of the central electrode can be prevented more reliably.

  The first and second dielectric members protrude from the central electrode toward the process gas introduction side, and a common introduction path is defined between the projecting portions, and the common introduction path serves as a process gas source. It is preferable that it is continuous and is connected to both the first and second discharge spaces. Thereby, it is not necessary to provide a processing gas introduction path separately for the first and second discharge spaces, and the gas introduction structure can be simplified.

It is preferable to further include a central dielectric member made of a solid dielectric provided on the periphery of the central electrode. As a result, abnormal discharge from the peripheral edge of the central electrode can be prevented.
Preferably, the central dielectric member has substantially the same thickness as the central electrode, and is sandwiched from both sides by the first and second dielectric members together with the central electrode. This eliminates the need for a separate holding structure for the central dielectric member.
More preferably, the central dielectric member is provided at least on the edge of the central electrode on the processing gas ejection side. As a result, abnormal discharge to the workpiece can be reliably prevented.

  Either one of the first and second dielectric members may be provided with a frame portion that follows the periphery of the central electrode. Thereby, the center electrode can be accurately positioned and held by the frame portion.

The present invention is suitable for plasma processing near atmospheric pressure (substantially normal pressure). Here, “substantially near atmospheric pressure (substantially normal pressure)” refers to a range of 1.013 × 10 ^{4 to} 50.663 × 10 ⁴ Pa, and considering the ease of pressure adjustment and the simplification of the apparatus configuration, 1 .333 × 10 ^{4 to} 10.664 × 10 ⁴ Pa are preferable, and 9.331 × 10 ^{4 to} 10.9797 × 10 ⁴ Pa are more preferable.

  According to the present invention, the central electrode is pressed from both sides by the first dielectric member and the second dielectric member, and the central electrode is deformed or displaced to the first outer electrode side or the second outer electrode side by an electric field or thermal stress. Can be prevented.

  FIG. 1 shows a first embodiment of the present invention. In the figure, reference numeral 1 denotes a three-electrode unit of the atmospheric pressure plasma processing apparatus, and reference numeral W denotes a workpiece to be disposed on the lower side of the three-electrode unit 1. The workpiece W is, for example, a glass substrate or a semiconductor substrate for a flat panel display.

  The three-electrode unit 1 includes three electrodes 21, 22, 22, three holders (dielectric members) 31, 32, 32, and an outer casing 10 that surrounds these electrodes 21, 22, 22 and holders 31, 32, 32. It has. The outer casing 10 includes an upper cap member 11, a side plate 12, and an end plate 13 (FIG. 3). These members 11, 12, and 13 are made of a corrosion-resistant resin such as Unilate (registered trademark).

  As shown in FIGS. 1 and 2, the cap member 11 has a rectangular parallelepiped shape whose longitudinal direction is the front-rear direction (a direction orthogonal to the paper surface of FIG. 1, the vertical direction of FIG. 2). The cap member 11 is placed on holders 31, 32, and 32, which will be described later, and is connected by bolts 14. The bolt insertion hole 11g of the cap member 11 is a long hole with the long axis directed to the left and right.

The cap member 11 includes a header path 11a extending in the longitudinal direction from one end surface, and a plurality of branch paths 11b provided at an equal pitch in the extending direction of the header path 11a, and is provided as a gas introduction member.
A gas supply path 2a extends from the processing gas source 2 and is connected to one end of the header path 11a. The processing gas source 2 stores gas species corresponding to the processing purpose. The other end of the header path 11a is located in the middle of the cap member 11 and is closed.
Each branch path 11b extends downward from the header path 11a and reaches the lower surface of the cap member 11 to be opened.

As shown in FIGS. 1 and 3, one of the three electrodes 21 has a thin rectangular plate shape, and is arranged vertically at the center of the three-electrode unit 1 with the longitudinal direction in the front-rear direction. ing. The thickness of the center electrode 21 is, for example, about 2 mm. A solid dielectric layer is not provided on the surface of the central electrode 21.
A feeding pin 23 from a power source (not shown) penetrates the cap member 11 and is connected to the central electrode 21. Thereby, the central electrode 21 is a hot electrode.

The other two electrodes 22, 22 are arranged on the left and right outer sides of the central electrode 21. When the left and right electrodes 22 are distinguished from each other, the left electrode 22 is denoted by “L” and the right electrode 22 is denoted by “R”. One (for example, the left side) electrode 22L forms a “first outer electrode”, and the other (for example, the right side) electrode 22R forms a “second outer electrode”. The two outer electrodes 22, 22 have the same thick plate shape, and are arranged with the longitudinal direction in the front-rear direction and the width direction in the vertical direction.
The thickness of the outer electrode 22 (the dimension in the left-right direction) is larger than the thickness of the central electrode 21. The vertical dimension of the outer electrode 22 is larger than the vertical dimension of the center electrode 21.
Each outer electrode 22 is electrically grounded via a ground wire (not shown) to constitute a ground electrode.

  The three holders 31, 32, 32 are each made of a solid dielectric ceramic such as alumina. These holders 31, 32, 32 correspond to the three electrodes 21, 22, 22 on a one-to-one basis.

  As shown in FIG. 4, the holder 31 (central dielectric member) corresponding to the central electrode 21 integrally includes a bottom portion 31c (processing gas ejection side portion) and a pair of front and rear side portions 31d. It forms a thin flat plate with a “concave” shape with an upper side opened, and partially surrounds the periphery of the central electrode 21. A bottom side 31 c of the center holder 31 is attached to the lower end edge of the center electrode 21. As shown in FIG. 3, the front and rear side portions 31 d of the holder 31 are attached to the front and rear edges of the electrode 21. The upper end portion of the side portion 31d protrudes above the electrode 21. The thickness of the holder 31 is the same size as the central electrode 21 (for example, about 2 mm). As shown in FIGS. 1 and 3, the left surfaces of the center electrode 21 and the center holder 31 are flush with each other, and the right surfaces are flush with each other.

  The two left and right holders 32 and 32 are substantially symmetrical. When these left and right holders 32 and 32 and their components are distinguished from each other, the left one is given a symbol “L” and the right one is given a “R”. One (eg, the left side) holder 32L constitutes a “first dielectric member”, and the other (eg, the right side) holder 32R constitutes a “second dielectric member”.

  Each of the left and right holders 32 has a vertical discharge side plate portion 32a, and an upper plate portion 32b and a lower plate portion 32c that protrude horizontally from the upper and lower ends of the discharge side plate portion 32a to the opposite side of the other holder. It has a U-shaped cross section. The discharge side plate portion 32a is thin, and the upper and lower plate portions 32b and 32c are thick.

The left electrode 22L is accommodated in the left holder 32L. The discharge side plate portion 32aL covers the surface of the electrode 22L facing the center electrode 21. The upper plate portion 32bL is assigned to the upper surface of the electrode 22L. The lower plate portion 32cL is addressed to the lower surface of the electrode 22L.
Similarly, the right electrode 22R is accommodated in the right holder 32R. The discharge side plate portion 32aR covers the surface of the electrode 22R facing the central electrode 21, the upper plate portion 32bR is directed to the upper surface of the electrode 22R, and the lower plate portion 32cR is addressed to the lower surface of the electrode 22R. .

A plurality of grooves 32e are formed on the surface of each of the left and right holders 32 facing the center electrode 21. The groove 32e extends up and down over the entire height direction of the holder 32, and is opened to reach the upper end surface and the lower end surface of the holder 32, respectively. The plurality of grooves 32e are arranged in parallel at intervals in the front-rear direction. Between the adjacent groove | channel 32e and the groove | channel 32e, it is the protruding item | line 32f. The ridges 32f extend vertically (from the processing gas introduction side to the ejection side) over the entire height direction of the holder 32 including the discharge side plate portion 32a. The protrusion 32 f is integrated with the holder 32.
The protrusion 32fL of one holder 32L constitutes a “first protrusion”, and the protrusion 32fR of the other holder 32R constitutes a “second protrusion”.
The thickness of the groove 32e portion of the discharge side plate portion 32a is about 1 mm. The thickness of the portion of the protrusion 32f between the groove 32e and the groove 32e of the discharge side plate portion 32a is about 2 mm.

  As shown in FIGS. 1 and 4, the four corners of the left holder 32L, the four corners of the center holder 31, and the four corners of the right holder 32R are connected by bolts 33 (tightening means), respectively, and the left and right holders 32L , 32R are tightened in a direction approaching each other. The holders 32L and 31 are formed with insertion holes 32g and 31g through which the bolts 33 are passed, respectively. The holder 32R has a female screw hole 32h into which the tip of the bolt 33 is screwed. The bolt 33 may also penetrate the holder 32R, and a nut may be screwed into the tip of the bolt 33 and tightened.

By the above tightening, as shown in FIG. 1, each protrusion 32fL of the left holder 32L is pressed against the left surface of the center electrode 21, and each protrusion 32fR of the right holder 32R is pressed to the right surface of the center electrode 21. Is pressed against. Thereby, the center electrode 21 is clamped from both sides by the left and right holders 32 and 32 and fixed.
Further, as shown in FIG. 2, the front and rear end portions of the left and right holders 32, 32 are pressed against the side portion 31d of the central holder 31 from both the left and right sides, and as shown in FIG. The lower portions of the ridges 32 f of 32 and 32 are pressed against the bottom 31 c of the holder 31 from both the left and right sides. Thereby, the center holder 31 is clamped from both sides by the left and right holders 32, 32 and fixed.

  As shown in FIG. 1, the upper portions of the left and right holders 32, 32 are positioned so as to protrude above the central electrode 21 (gas introduction side). A common introduction path 32i is defined between the upper portions (projecting portions) of the left and right holders 32, 32. The branch path 11b of the cap member 11 is connected to the upper end portion of the common introduction path 32i. The groove 32eL, 32eR of both the left and right holders 32L, 32R is connected to the lower end of the common introduction path 32i. The upper side part of the side part 31d of the center holder 31 defines the front and rear edges of the common introduction path 32i.

A method for surface-treating the workpiece W by the plasma processing apparatus configured as described above will be described.
The processing gas from the processing gas source 2 is supplied to the header path 11a through the gas supply path 2a. The processing gas is sequentially introduced into the common introduction path 32i via the branch path 11b while flowing downstream in the header path 11a. Furthermore, the processing gas is introduced from the common introduction path 32i into the left and right grooves 32eL and 32eR, and flows downward in the grooves 32eL and 32eR.

In parallel, a voltage is supplied from a power source (not shown) to the central hot electrode 21 via the power supply pin 23. As a result, an electric field is applied between the center electrode 21 and the left ground electrode 22L, and between the center electrode 21 and the right ground electrode 22R, thereby generating an atmospheric pressure glow discharge. At this time, the discharge side plate portion 32 a of each holder 32 serves as a solid dielectric layer for stable discharge to be disposed on the surface of the electrode 22. The bottom 31c of the center holder 31 can prevent an abnormal discharge such as an arc from dropping from the center electrode 21 to the workpiece W.
A portion of each (for example, the left side) holder 32L that overlaps the electrode 21 in each groove 32eL becomes a “first discharge space”. The portion of each of the grooves 32eR of the other (for example, the right side) holder 32R that overlaps the electrode 21 is a “second discharge space”. As a result, the processing gas is turned into plasma (including decomposition, excitation, activation, radicalization, and ionization) in the groove 32e.
This plasma-ized processing gas is ejected downward from the groove 32e. The processing gas comes into contact with the workpiece W and surface treatment is performed.

  According to the three-electrode unit 1, the center electrode 21 can be clamped from both sides by the left and right holders 32, 32 and can be securely fixed. As a result, the central electrode 21 can be prevented from being deformed or displaced by an electric field or thermal stress acting on both sides. As a result, the thickness of the first and second discharge spaces 32e can be kept constant.

Next, another embodiment of the present invention will be described. In the following embodiments, the same reference numerals are attached to the drawings for the same configurations as those already described, and the description thereof is omitted.
The protrusions 32f only have to be provided at least in a portion of the holder 32 that faces the central electrode 31, and do not necessarily extend over the entire length of the holder 32 in the vertical direction.
For example, in the embodiment shown in FIG. 5, only the upper and lower portions of the holder 32 are formed so that the short ridges 32fa and 32fb as the first and second protrusions extend vertically. A short groove 32ea is formed between the upper protrusions 32fa. A short groove 32eb is formed between the lower protrusions 32fb. The lower end portion of the upper convex portion 32fa hits the upper portion of the center electrode 31 indicated by a two-dot chain line in FIG. The upper end portion of the lower convex portion 32 fb comes into contact with the lower side portion of the central electrode 31.

  On the surface facing the center electrode 31 of the holder 32, an intermediate recess 32k is formed between the upper protrusion 32fa and the lower protrusion 32fb. The upper end of the intermediate recess 32k is continuous with the upper groove 32ea, and the lower end of the intermediate recess 32k is continuous with the lower groove 32eb.

  The processing gas passes through each upper groove 32ea and is merged in the intermediate recess 32k and is converted into plasma. Therefore, it is not always necessary to distribute the processing gas accurately and evenly in each groove 32ea. The processing gas converted into plasma in the intermediate recess 32k is ejected through the lower groove 32eb.

Either one of the holders 32 and the central holder 31 may be integrated.
For example, in the embodiment shown in FIG. 6, a pair of frame portions 321 are integrally formed on both sides of the surface of the holder 32R facing the other holder 32L (not shown) so as to protrude toward the holder 32L. ing. Each frame part 321 has a side frame part 321a that extends vertically along the side part of the holder 32R, and a lower frame part 321b that bends in an L shape inward from the lower end part of the side frame part 321a. is doing. The lower frame portion 321b extends from the side frame portion 321a to the vicinity of the groove 32e closest to the end portion.
The side frame part 321 a corresponds to the side part 31 d of the center holder 31 in the first embodiment (FIGS. 1 to 4), and the lower frame part 321 b corresponds to a part of the bottom part 31 of the center holder 31.

The center electrode 31 is fitted in the pair of frame portions 321. The side edges of the central electrode 31 are attached to the inner end face of the side frame part 321a, and both end parts of the lower edge of the central electrode 31 are placed on the upper end face of the lower frame part 321.
Thereby, the center electrode 31 can be accurately positioned and held with respect to the holder 32.
Separately, the central holder 31 is unnecessary, and the number of parts can be reduced.

The holders 31 and 32 do not have to be integrated with each other, and may be configured by combining a plurality of parts.
For example, in the embodiment shown in FIG. 7, the bottom side 31 c of the center holder 31 and the side sides 31 d and 31 d on both sides are formed of separate solid dielectric plates. These three side portions 31c, 31d, and 31d may be bonded to each other with an adhesive, can be separated without being bonded, and are clamped by tightening the holders 32L and 32R on both sides. It may be.

  In the embodiment shown in FIG. 8, the discharge side plate portion 32a, the upper plate portion 32b, and the lower plate portion 32c of the holder 32R are separate from each other. The upper plate portion 32b is bonded to the back surface of the upper end portion of the discharge side plate portion 32a with an adhesive. The lower plate portion 32c is bonded to the back surface of the lower end portion of the discharge side plate portion 32a with an adhesive.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, the clamping means for the left and right holders 32, 32 may be clamps.
The three holders 31, 32L, 32R may be bonded to each other with an adhesive instead of the fastening means. Furthermore, the holders 31, 32 and the electrodes 21, 22L, 22R may be bonded.
The first convex portion and the second convex portion are not necessarily linear, and may be spot-like projections. The first and second convex portions formed of spot-like protrusions may be regularly scattered on the discharge side plate portion 32 a of the dielectric member 32.
The upper and lower plate portions 32b and 32c of the first and second holders 32 may be omitted, and the first and second dielectric members may be configured only by the discharge side plate portion 32a.
The pair of side portions 31d and 31d of the center holder 31 may be omitted, and the center dielectric member may be configured only by the bottom portion 31c (processing gas ejection side portion).
The central holder 31 may be omitted, and the peripheral portions of the left and right holders 32 and 32 may be in contact with each other.
The length in the longitudinal direction (dimension in the front-rear direction) of each electrode 21, 22L, 22R may be set according to the width (dimension in the front-rear direction) of the workpiece W.

In the first embodiment of FIGS. 1 to 4, the positions, pitches, and numbers of the left and right ridges 32 fL, 32 fR coincide with each other. May be.
In the embodiment of FIG. 5, the position, pitch, and number in the front-rear direction of the upper and lower ridges 32fa, 32fb are consistent with each other.
In the embodiment of FIG. 6, the frame portion 321 may be configured by only the side frame portion 321a, and the lower frame portion 321b may be omitted. When the center electrode 31 is bonded to the holder 32, the lower frame portion 321b may be omitted.
In the embodiment of FIG. 6, the frame portion 321 is provided on the second holder 32R on the right side, but the frame portion 321 may be integrally formed on the first holder 31L on the left side.
The embodiment of FIG. 8 shows the right second holder 32R, but the left first holder 32L may also have three plate portions 32a, 32b, and 32c that are separate from each other. Good.
In the embodiment of FIG. 8, separate plate portions 32a, 32b, and 32c may be joined to each other with screws instead of the adhesive.
A solid dielectric layer may be provided on the surface of the central electrode 21 by thermal spraying or the like.
The present invention can be applied to various surface treatments such as cleaning, surface modification (hydrophilization, water repellency, etc.), etching, and film formation. The present invention is not limited to plasma processing near atmospheric pressure, and can also be applied to plasma processing under vacuum.

  The present invention is applicable to, for example, surface treatment in a manufacturing process of a glass substrate for a flat panel display or a semiconductor substrate.

It is front sectional drawing which shows the 3 electrode unit of the atmospheric pressure plasma processing apparatus which concerns on 1st Embodiment of this invention along the II line | wire of FIG. FIG. 2 is a plan sectional view of the three-electrode unit along the line II-II in FIG. 1. FIG. 3 is a plan sectional view of the three-electrode unit along the line III-III in FIG. 1. FIG. 3 is an exploded perspective view of the three-electrode unit (excluding the outer casing). It is the figure which showed 2nd Embodiment which concerns on the modification of a 1st, 2nd convex part, and looked at the holder of the three-electrode unit. It is a perspective view which shows 3rd Embodiment which concerns on the modification of the holding structure of a center electrode. It is the figure which showed 4th Embodiment which concerns on the modification of a center holder, and looked at the said center holder directly. It is a perspective view which shows 5th Embodiment which concerns on the modification of a holder on either side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Three-electrode unit W of atmospheric pressure plasma processing apparatus To-be-processed object 21 Central electrode 22L First outer electrode 22R Second outer electrode 31 Central holder (central dielectric member)
31c Processing gas ejection side portion 32L of central dielectric member First holder (first dielectric member)
32R second holder (second dielectric member)
32a Discharge side plate 32eL groove (first discharge space)
32eR groove (second discharge space)
32fL ridge (first ridge)
32fR ridge (second ridge)
33 bolts (tightening means)
32i Common introduction path 321 Frame

Claims (8)

In the plasma processing apparatus for introducing a processing gas into the first and second discharge spaces and ejecting the processing gas to contact an object to be processed outside the two discharge spaces,
A center electrode;
A first outer electrode disposed on one side of the central electrode;
A second outer electrode disposed on the other side of the central electrode;
A first dielectric member made of a solid dielectric covering the surface of the first outer electrode facing the central electrode and forming the first discharge space between the central electrode;
A second dielectric member made of a solid dielectric covering the surface of the second outer electrode facing the center electrode and forming the second discharge space between the second electrode and the center electrode;
A first convex portion that protrudes toward the central electrode is formed on the first dielectric member,
A second protrusion projecting toward the center electrode is formed on the second dielectric member;
The plasma processing apparatus, wherein the first convex portion and the second convex portion are applied to the central electrode from both sides.   The first dielectric member and the second dielectric member are tightened in the approaching direction by a tightening means, and the first convex portion and the second convex portion are pressed against the central electrode from both sides. The plasma processing apparatus according to claim 1.   3. The plasma processing apparatus according to claim 1, wherein the first convex portion extends from a side for introducing a processing gas into the first discharge space to a side for ejection. 4.   The plurality of first protrusions are provided at intervals in a direction orthogonal to the extending direction, and a space between two adjacent first protrusions is the first discharge space. 4. The plasma processing apparatus according to 3.   The first and second dielectric members protrude from the central electrode toward the process gas introduction side, and a common introduction path is defined between the projecting portions, and the common introduction path serves as a process gas source. The plasma processing apparatus according to claim 3, wherein the plasma processing apparatus is continuous and is connected to both the first and second discharge spaces. A central dielectric member made of a solid dielectric provided on the periphery of the central electrode;
6. The center dielectric member according to claim 1, wherein the center dielectric member has substantially the same thickness as the center electrode, and is sandwiched from both sides by the first and second dielectric members together with the center electrode. The plasma processing apparatus according to 1.   The plasma processing apparatus according to claim 6, wherein the central dielectric member is provided at least on an edge of the central electrode on a processing gas ejection side.   The plasma processing apparatus according to claim 1, wherein a frame portion is provided on one of the first dielectric member and the second dielectric member along the periphery of the central electrode.

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