Plasma processing device

Abstract

Provided is a plasma processing device exhibiting a superior uniformity in the amount of a plasma-containing gas ejected in the extension direction of a plasma ejection opening.　The plasma processing device comprises: (a) a gas introduction unit for guiding a feed gas into the interior of the plasma processing device; (b) a flow rate suppressor for suppressing the flow rate of the feed gas introduced from the gas introduction unit; (c) a gas distribution flow path which has a plurality of gas distribution ports and distributes the feed gas that has passed through the flow rate suppressor to the plurality of gas distribution ports; (d) a plasma generation unit including a plasma generation space and a plurality of branch pipes connecting the plurality of gas distribution ports to the plasma generation space; (e) a pair of electrodes positioned so as to sandwich the plasma generation space; and (f) an opening for ejecting a plasma-containing gas.

Description

Plasma processing apparatus

[0001] This invention relates to a plasma processing apparatus.

[0002] Plasma processing apparatuses are used in manufacturing processes for plastics, paper, fibers, semiconductors, liquid crystals, films, etc. For example, by irradiating the object to be processed with plasma from a plasma processing apparatus, surface treatment for improving hydrophilicity, adhesiveness, or printing adhesion to the surface of the object to be processed, removal and cleaning of organic substances present on the surface of the object to be processed, or formation of an oxide film on the surface of the object to be processed is performed.

[0003] An example of a plasma processing apparatus is shown in Patent Document 1. The plasma processing apparatus described in Patent Document 1 is shown in FIG. 9. FIG. 9 is a perspective view of the plasma processing apparatus 900. FIG. 10 is a cross-sectional view when the plasma processing apparatus 900 in FIG. 9 is cut along the line II-II. Also, FIG. 11 is a cross-sectional view when the plasma processing apparatus 900 in FIG. 9 is cut along the line III-III.

[0004] As shown in FIGS. 9, 10, and 11, the plasma processing apparatus 900 includes a first electrode 10, a second electrode 15, a dielectric substrate 30 sandwiched between the first electrode 10 and the second electrode 15, and a gas buffer substrate 40 located on the side opposite to the side where the dielectric substrate 30 is disposed when viewed from the second electrode 15. That is, the plasma processing apparatus 900 is configured by laminating the first electrode 10, the dielectric substrate 30, the second electrode 15, and the gas buffer substrate 40 in the -Y direction. The first electrode 10 is connected to a high-voltage power supply device 63, and the high-voltage power supply device 63 and the second electrode 15 are grounded (see FIG. 10).

[0005] As shown in FIG. 10, a space 27 exists between the dielectric substrate 30 and the second electrode 15. The space 27 extends in the X and Z directions and has a flat shape that is narrow in the Y direction. Since the space 27 is between the first electrode 10 and the second electrode 15, when a voltage is applied between the first electrode 10 and the second electrode 15, dielectric barrier discharge occurs in the space 27. The dielectric barrier discharge plasmatizes the gas in which the raw material gas G0 supplied from the raw material gas supply source 59 passes through the space 27. Therefore, the space 27 is also called the plasma generation space 27.

[0006] As shown in Figures 9 and 10, the plasma processing apparatus 900 is equipped with a plasma ejection opening 5 from which plasma-containing gas G1 is ejected. The plasma ejection opening 5 extends in the X direction and has a narrow shape in the Y direction. As shown in Figure 10, the plasma ejection opening 5 communicates with the plasma generation space 27. The plasma processing apparatus 900 can perform plasma treatment on the surface of a workpiece by ejecting the plasma-containing gas G1 in a wide area from the plasma ejection opening 5.

[0007] Figure 12 is a cross-sectional view of the plasma processing apparatus 900 in Figure 10, taken along the line IV-IV. The main surface of the second electrode 15 can be seen from this cross-sectional view. The plasma generation space 27 is surrounded by the edge 16 of the second electrode 15, except for the plasma ejection opening 5.

[0008] As shown in Figure 10, the plasma processing apparatus 900 has a gas buffer space 41 upstream of the plasma generation space 27. The gas buffer space 41 has a flattened shape that extends in the X and Z directions and is narrow in the Y direction. The flattening direction of the gas buffer space 41 is aligned with the flattening direction of the plasma generation space 27.

[0009] As shown in Figure 10, the plasma generation space 27 and the gas buffer space 41 are connected by branch pipes 53. Although only one branch pipe 53 is shown in the cross-sectional view of Figure 10, the plasma processing apparatus 900 has multiple branch pipes 53 arranged in the X direction. Figure 12 shows that each of the branch pipes 53 has multiple raw material gas inlets 54 that are in contact with the plasma generation space 27, and these are arranged in the X direction.

[0010] The gas buffer space 41 is a space for storing the raw material gas G0 and also a space for distributing the raw material gas G0 to multiple branch pipes 53. The gas buffer space 41 distributes the raw material gas G0 introduced from the gas inlet 60 to each branch pipe 53, and the raw material gas G0 distributed to each branch pipe 53 enters the plasma generation space 27 via the corresponding raw material gas inlet 54. Therefore, the raw material gas G0 that is separated during the process of flowing from the gas buffer space 41 to each branch pipe 53 rejoins with the raw material gas G0 flowing through the other branch pipes 53 in the plasma generation space 27. The rejoined raw material gas G0 is converted into plasma-containing gas G1 in the plasma generation space 27 and then widely ejected in the X direction from the plasma ejection opening 5.

[0011] Japanese Patent Publication No. 2023-40527

[0012] When ejecting plasma-containing gas from a plasma ejection opening, it is desirable that the amount of plasma-containing gas ejected be uniform in the direction of extension of the plasma ejection opening.

[0013] As described above, in the plasma processing apparatus 900 described in Patent Document 1, the raw material gas G0 stored in the gas buffer space 41 is supplied to the plasma generation space 27 via branch pipes 53 that are aligned in the extending direction (X direction) of the plasma ejection opening 5. Therefore, the amount of raw material gas G0 supplied to the plasma generation space 27 is relatively uniform in the extending direction, and as a result, the amount of plasma-containing gas G1 ejected tends to be relatively uniform in the extending direction. However, there is room for improvement in the uniformity of the ejection amount in the extending direction of the plasma ejection opening 5 in the plasma processing apparatus 900.

[0014] The present invention aims to provide a plasma processing apparatus that improves the uniformity of the amount of plasma-containing gas ejected in the extending direction of the plasma ejection opening.

[0015] The plasma processing apparatus of the present invention is a plasma processing apparatus that ejects a plasma-containing gas onto a workpiece and performs plasma processing on the workpiece, the plasma processing apparatus comprising: (a) a gas introduction section that introduces a raw material gas, which is the raw material for the plasma-containing gas, into the interior of the plasma processing apparatus; (b) a flow velocity suppressor that suppresses the flow velocity of the raw material gas introduced from the gas introduction section; (c) a gas distribution channel having a plurality of gas distribution ports that distribute the raw material gas that has passed through the flow velocity suppressor to the plurality of gas distribution ports; (d) a plasma generation section connected to the plurality of gas distribution ports, the plasma generation section comprising: a plasma generation space that generates plasma from the raw material gas; and a plurality of branch pipes that connect each of the plurality of gas distribution ports to the plasma generation space; (e) a pair of electrodes arranged to sandwich the plasma generation space and to which a voltage is applied for plasmaizing the raw material gas in the plasma generation space; and (f) an opening located at one end of the plasma generation space that ejects the plasma-containing gas.

[0016] Firstly, in this specification, flow rate refers to volumetric flow rate (unit: m³). ３ This represents the volume of fluid flowing over a surface per unit time (m²). ２ The cross-sectional area refers to the surface that crosses the fluid flowing through the channel (hereinafter, "channel cross-sectional area" may be simply referred to as "cross-sectional area"). Flow velocity (unit: m / s) refers to the flow rate per unit cross-sectional area of ​​the fluid flowing through the channel.

[0017] The process leading to the creation of the above-mentioned plasma processing apparatus will now be explained. As a result of diligent research, the inventors have discovered that in the plasma processing apparatus 900, one of the factors causing variation in the amount of plasma-containing gas G1 ejected in the direction of extension of the plasma ejection opening 5 is the gas buffer space 41 located upstream of the multiple branch pipes 53.

[0018] The details will be explained with reference to Figure 13. Figure 13 is a cross-sectional view of the plasma processing apparatus 900 (plasma processing apparatus described in Patent Document 1) in Figure 10, when cut along the V-V line. The gas buffer space 41 is surrounded by the edge 46 of the gas buffer substrate 40. The gas buffer substrate 40 has a gas introduction port 61 for introducing raw material gas G0 in the central region of its main surface. In the case of the cross-sectional view shown in Figure 13, the gas introduction port 61 is actually located in front of the viewer from the direction indicated in the cross-sectional view, so the gas introduction port 61 is not shown in the cross-sectional view. However, to confirm the position of the gas introduction port 61 on the XZ plane, the gas introduction port 61 is shown with a dashed line. The gas introduction port 61 in Figure 13 can be considered as a projection of the actual gas introduction port 61 onto the cross-sectional view, with its position and size on the XZ plane being directly represented.

[0019] As shown in Figure 10, the gas inlet connection port 61 is connected to the gas inlet 60, and the gas inlet 60 is connected to the raw material gas supply source 59. Then, as shown in Figure 13, the raw material gas G0 introduced from the gas inlet connection port 61 spreads throughout the gas buffer space 41. In Figure 13, the arrows extending radially from the gas inlet connection port 61 indicate the flow direction of the raw material gas G0 flowing from the gas inlet connection port 61 into the gas buffer space 41. The raw material gas G0 is released in various directions and spreads throughout the gas buffer space 41.

[0020] When a fluid moves from a narrow space such as a gas inlet to a wider space such as a gas buffer space 41, the fluid expands rapidly. Around the gas inlet connection port 61, where the fluid is expanding, the fluid state is unstable, such as when the flow velocity rapidly decreases. As a result, the pressure may rise sharply locally near the gas inlet connection port 61. On the other hand, at the end of the gas buffer space 41, away from the gas inlet connection port 61, the fluid state stabilizes and the pressure decreases overall. The branch pipes 53 are distributed from near the gas inlet connection port 61 to the end of the gas buffer space 41, away from the gas inlet connection port 61. Therefore, a large amount of gas flows into the branch pipes close to the gas inlet connection port 61 due to the rapidly rising pressure, while less gas flows into the branch pipes further away from the gas inlet connection port 61 due to the relatively lower pressure. In a wide space such as the gas buffer space 41, the flow into the branch pipes 53 is concentrated near the gas inlet connection port 61. The amount of gas flowing into each of the branch pipes 53 becomes uneven, and as a result, the amount of plasma ejected in the direction of extension of the plasma ejection opening 5 is greater closer to the gas inlet connection port 61.

[0021] Based on the above findings, the inventors realized that the use of the gas buffer space 41 increases the amount of gas flowing into the branch pipe 53 near the gas inlet connection port 61, hindering further uniformity of the gas amount in the extending direction of the plasma ejection opening 5. To solve the above problem, they aimed to narrow the gas buffer space 41. As a result, the inventors adopted a gas distribution channel with a narrower space than the gas buffer space 41 instead of the gas buffer space 41.

[0022] The gas distribution channel is a smaller space than the gas buffer space 41. Specifically, the gas distribution channel differs from the gas buffer space 41 in that it has a narrower cross-sectional area. In particular, if the cross-sectional area of ​​the gas distribution channel is about the same as the cross-sectional area of ​​the gas inlet connection port, the fluid flow within the gas distribution channel will be stable, and the raw material gas will spread relatively uniformly even far from the gas inlet connection port. Here, "the cross-sectional area of ​​the gas distribution channel is about the same as the cross-sectional area of ​​the gas inlet connection port" means that the cross-sectional area of ​​the gas distribution channel should be within ±20% of the cross-sectional area of ​​the gas inlet connection port, and preferably within ±10%.

[0023] However, as a result of further diligent research by the inventors, it was found that when a gas distribution channel was used instead of a gas buffer space for distributing gas to the gas distribution ports, the non-uniformity of the amount of gas flowing through each gas distribution port was eliminated to some extent, but not completely, and differences in the amount of gas flowing through each gas distribution port still occurred.

[0024] The reason for the difference in gas volume when a gas distribution channel is used is explained below. Regarding the gas distribution ports arranged perpendicular to the extension direction of the gas distribution channel, near the inlet of the gas distribution port close to the gas inlet, the velocity vector of the raw material gas in the extension direction of the gas distribution channel is relatively large. As a result, it is difficult for the gas to flow to the gas distribution port close to the gas inlet, and the amount of raw material gas decreases compared to the gas distribution port farther from the gas inlet. Consequently, the amount of ejection from the plasma ejection opening 5 is less when it is closer to the gas inlet connection port 61. Thus, it is thought that the non-uniformity in the extension direction of the plasma ejection opening 5 occurs due to a mechanism different from that when a gas buffer space 41 is used.

[0025] Therefore, the present inventors have devised a plasma processing apparatus that includes "(b) a flow velocity suppressor that suppresses the flow velocity of the raw material gas introduced from the gas introduction section." As a result of the flow velocity suppressor reducing the flow velocity of the gas introduced from the gas introduction section, the difference between the amount of gas flowing through the gas distribution port near the gas introduction section and the amount of gas flowing through the gas distribution port far from the gas introduction section becomes smaller, and the gas distribution amount can be made uniform. This means that the gas diffuses sufficiently in the longitudinal direction and the amount of gas is made uniform in the longitudinal direction. In other words, the amount of plasma processing gas discharged from the plasma ejection opening toward the workpiece is made uniform in the extending direction of the plasma ejection opening. The flow velocity suppressor's ability to suppress the flow velocity can be calculated by comparing the inlet flow velocity of the fluid on the inlet side of the flow velocity suppressor with the outlet flow velocity of the fluid on the outlet side of the flow velocity suppressor. As a flow velocity suppressor, it is desirable for the outlet flow velocity to be reduced by 10% or more compared to the inlet flow velocity, preferably by 20% or more, and more preferably by 30% or more.

[0026] The opening of the plasma processing apparatus may extend along the first direction and have a narrower shape along the second direction perpendicular to the first direction. With respect to the gas distribution channel described in (c) of the plasma processing apparatus, the gas distribution channel may extend along the first direction, and the plurality of gas distribution ports may be arranged along the first direction. Furthermore, with respect to the plurality of branch pipes described in (d) of the plasma processing apparatus, the plurality of branch pipes may be arranged along the first direction.

[0027] With respect to the plasma generation space described in (d) in the plasma processing apparatus, the plasma generation space may be wide along the first direction and the third direction which is orthogonal to both the first and second directions, and narrow along the second direction. Furthermore, with respect to the pair of electrodes described in (e) in the plasma processing apparatus, the pair of electrodes may be configured to sandwich the plasma generation space from both sides of the second direction.

[0028] Furthermore, the "first direction" in the above corresponds to the "X direction" in the following embodiment, the "second direction" in the above corresponds to the "Y direction" in the following embodiment, and the "third direction" in the above corresponds to the "Z direction" in the following embodiment.

[0029] As a specific embodiment of the flow velocity suppressor, the minimum inner diameter of the space between the gas introduction section and the gas distribution channel may be larger than the channel diameter of the gas distribution channel.

[0030] As a specific embodiment of the flow velocity suppressor, the flow velocity suppressor may have a branch between the gas distribution channel and the blocked channel.

[0031] In a specific embodiment of the flow velocity suppressor, the flow velocity suppressor may have a porous material that obstructs the flow of the raw material gas. The porous material is, for example, a filter or perforated metal.

[0032] The aforementioned branch pipes may be equipped with flow velocity suppressors.

[0033] This makes it possible to provide a plasma processing apparatus that improves the uniformity of the plasma-containing gas ejection amount in the extending direction of the plasma ejection opening.

[0034] This is a perspective view of the plasma processing apparatus. This is an enlarged cross-sectional view of the plasma processing apparatus in Figure 1 when cut along the P1 plane. This is a perspective view of the first member. This is a view of the first member in the -Y direction. This is an enlarged cross-sectional view of the plasma processing apparatus in Figure 1 when cut along the P2 plane. This is an enlarged view of the area near the flow velocity suppressor of the first member in the +Z direction. This is a diagram showing a modified example of the plasma processing apparatus. This is an enlarged view of the P3 region in Figure 2. This is a diagram showing the plasma processing apparatus described in Patent Document 1. This is a cross-sectional view of the plasma processing apparatus in Figure 9 when cut along the II-II line. This is a cross-sectional view of the plasma processing apparatus in Figure 9 when cut along the III-III line. This is a cross-sectional view of the plasma processing apparatus in Figure 10 when cut along the IV-IV line. This is a cross-sectional view of the plasma processing apparatus in Figure 10 when cut along the VV line.

[0035] [Overview of Plasma Processing Apparatus] The plasma processing apparatus will be described below with reference to the drawings as appropriate. Note that each drawing is a schematic illustration, and the dimensional ratios and numbers shown in the drawings do not necessarily correspond to the actual dimensional ratios and numbers. When expressing direction, if positive and negative directions are distinguished, they are indicated with positive and negative signs, such as "+X direction" and "-X direction". When the direction is expressed without distinguishing between positive and negative directions, it is simply indicated as "X direction". In other words, in this specification, when simply indicated as "X direction", both "+X direction" and "-X direction" are included. The same applies to the Y direction and Z direction.

[0036] An embodiment of the plasma processing apparatus will be described with reference to Figures 1 and 2. Figure 1 is an overall perspective view of the plasma processing apparatus 100. Figure 2 is an enlarged cross-sectional view of the plasma processing apparatus 100 of Figure 1 when cut across the P1 plane. The P1 plane is the YZ plane passing through point A. Point A is the center point of the inner circumference at the open end of the gas introduction pipe 3 that constitutes the gas introduction section 60.

[0037] The plasma processing apparatus 100 can perform plasma processing on a workpiece by ejecting plasma-containing gas G1 from a plasma ejection opening 5 that extends in one direction. The plasma processing apparatus 100 is supplied with raw material gas G0. The plasma processing apparatus 100 generates plasma-containing gas G1 from the raw material gas G0.

[0038] First, the flow of the raw material gas G0 and the plasma-containing gas G1 in the plasma processing apparatus 100 will be explained. The plasma processing apparatus 100 includes a gas introduction section 60, a gas distribution channel 50 (see Figure 1, or Figures 3, 4, or 5 described later), a plasma generation section 20 (see Figure 5 described later for the plasma generation section 20), a pair of electrodes (10, 15) (see Figure 2), a flow velocity suppressor 70 (see Figure 2), and a plasma ejection opening 5. The gas introduction section 60 guides the raw material gas G0 into the interior of the plasma processing apparatus 100. The flow velocity suppressor 70 is positioned between the gas introduction section 60 and the gas distribution channel 50 in the flow of the raw material gas G0.

[0039] In Figures 1 and 2, the arrows labeled GF indicate the flow direction of the raw material gas G0 and the plasma-containing gas G1. The raw material gas G0 flows in the order of the gas introduction section 60, the flow velocity suppressor 70, and the gas distribution channel 50. The flow velocity suppressor 70 can reduce the flow velocity of the raw material gas G0, but the details of the flow velocity suppressor 70 will be described later.

[0040] The raw material gas G0 is transformed into plasma-containing gas G1 in the plasma generation space 27. As shown in Figure 2, the plasma generation space 27 is positioned between a pair of electrodes (10, 15) in the Y direction. By applying a voltage between the pair of electrodes (10, 15) using a high-voltage power supply 63, a dielectric barrier discharge is generated between the pair of electrodes (10, 15), and the raw material gas G0 in the plasma generation space 27 is converted into plasma to generate plasma-containing gas G1.

[0041] As shown in Figure 2, the plasma processing apparatus 100 is composed of multiple components. Figure 3 is a perspective view showing only the first component 1 of the plasma processing apparatus 100. The first component 1 is equipped with a gas distribution channel 50 and multiple gas distribution ports 52, and can be said to be a component that constitutes the framework of the plasma processing apparatus 100. In this embodiment, the first component 1 functions as the second electrode 15 when it is grounded. Figure 4 is a view of the first component in the -Y direction. Details of the remaining components other than the first component 1 will be described later. Here, the gas distribution channel 50 will be described with reference to Figures 3 and 4 in addition to Figure 1.

[0042] [Plasma Distribution Channel] As shown in FIG. 3, the gas distribution channel 50 extends in the X direction and is a narrow channel in the Y and Z directions. Since only the first member 1 is shown in FIG. 3, the gas distribution channel 50 appears to be open in the -Z direction. However, in reality, as shown in FIG. 1, the gas distribution channel 50 is covered by the second member 2 described later, and the gas distribution channel 50 cannot be seen from outside the plasma processing apparatus 100. In FIG. 4, since the gas distribution channel 50 and the plurality of gas distribution ports 52 are hidden and not visible, they are shown by dashed lines. FIG. 4 shows a state in which the branch pipes (details of the branch pipes will be described later) extending from the plurality of gas distribution ports 52 extend to the raw material gas inlet 54. Also, in FIGS. 3 and 4, since only the first member 1 is shown, the overall image of the flow rate suppressor 70 cannot be shown. Therefore, in FIGS. 3 and 4, the position where the flow rate suppressor 70 exists is indicated by a dashed-dotted line.

[0043] As shown in FIG. 4, the gas distribution channel 50 has a plurality of gas distribution ports 52 arranged in the X direction. And the flow rate suppressor 70 (and the gas introduction part 60) is located at the center of the gas distribution channel 50. The gas distribution channel 50 extends in the +X direction from the flow rate suppressor 70 and also extends in the -X direction from the flow rate suppressor 70. That is, the raw material gas G0 that has passed through the flow rate suppressor 70 flows through the gas distribution channel 50 in the +X direction and the -X direction. In this way, the raw material gas G0 introduced from the gas introduction part 60 is distributed to the plurality of gas distribution ports 52. The flow rate suppressor 70 (gas introduction part 60) is preferably located at the center of the gas distribution channel 50. However, the flow rate suppressor 70 (gas introduction part 60) may be provided at a position other than the center of the gas distribution channel 50, for example, a position close to one end of the gas distribution channel 50 in either one of the extending directions.

[0044] As shown in FIG. 5, the cross-sectional shape of the gas distribution channel 50 is rectangular, but it does not necessarily have to be rectangular. The cross-sectional shape of the gas distribution channel 50 may be circular, elliptical, or a polygon other than rectangular. The cross-sectional area of the gas distribution channel 50 may be changed according to the distance from the flow rate suppressor 70. For example, the cross-sectional area of the gas distribution channel 50 may be made smaller as the distance from the flow rate suppressor 70 increases.

[0045] The inner diameter of the gas distribution channel 50 may be 5 mm or more and 20 mm or less, and more preferably 8 mm or more and 15 mm or less. The length from the flow velocity suppressor 70 to the end of the gas distribution channel 50 may be 30 mm or more and 200 mm or less, and may also be 50 mm or more and 100 mm or less.

[0046] [Plasma generation unit] Fig. 5 is an enlarged cross-sectional view when the plasma processing apparatus 100 of Fig. 1 is cut along the P2 plane. The P2 plane is the YZ plane passing through point B. Point B is the center point of one gas distribution port 52. The plasma generation unit 20 is connected to the gas distribution port 52 via branch pipes (53a, 53b). The plasma generation unit 20 has a plasma generation space 27 that is wide in the X and Z directions and narrow in the Y direction, and a plurality of branch pipes (53a, 53b) that communicate with the plasma generation space 27. As shown in Fig. 5, the gas distribution channel 50 communicates with the plasma generation space 27 via the branch pipes (53a, 53b). The plasma generation space 27 is sandwiched between the dielectric substrate 30 and the second electrode 15 (first member 1). Also, since the plasma generation space 27 is located between the pair of electrodes (10, 15), by applying a voltage to the pair of electrodes (10, 15), the source gas G0 in the plasma generation space 27 is plasmaized. The gas distribution port 52 can be said to be the connection part of the gas distribution channel 50 and the branch pipes (53a, 53b). The source gas G0 flows from the gas distribution channel 50 through the gas distribution port 52 into the branch pipes (53a, 53b). There are a plurality of branch pipes 53 in Fig. 3. Each branch pipe 53 is arranged side by side in the X direction. Each branch pipe 53 connects the plasma generation space 27 of the plasma generation unit 20 and each of the gas distribution ports 52.

[0047] In the present embodiment, the branch pipe 53 has a first part 53a extending in the +Z direction from each gas distribution port 52, and a second part 53b extending in the Y direction so as to connect the first part 53a and the plasma generation space 27. The part where the second part 53b of the branch pipe 53 contacts the plasma generation space 27 is the source gas inlet 54. The source gas G0 flows in the order of the gas distribution port 52, the first part 53a of the branch pipe 53, the second part 53b of the branch pipe 53, the source gas inlet 54, and the plasma generation space 27.

[0048] The branch pipe 53 is composed of two parts, a first part 53a and a second part 53b, which can be distinguished by differences in shape, direction of travel, or branching, but the specific shape of such a branch pipe 53 is not limited to these. The branch pipe 53 may be composed of one part or of three or more parts. The branch pipe 53 may have a curved shape rather than a straight shape. In this embodiment, the cross-sections of the first part 53a and the second part 53b are both circular, but they do not necessarily have to be circular cross-sections. The branch pipe 53 may have, for example, a rectangular cross-section or an elliptical cross-section.

[0049] The inner diameter of the branch pipe 53 may be 1 mm or more and 8 mm or less, and preferably 2 mm or more and 5 mm or less. The length of the branch pipe 53 (or the total length of the multiple parts if it is composed of multiple parts) may be 5 mm or more and 50 mm or less, and may be 10 mm or more and 30 mm or less.

[0050] In Figure 4, the raw material gas inlet 54 is shown as a circular opening, but it may also be an elliptical or rectangular opening extending in the X direction, for example. In order to function as a branch pipe 53 or a gas distribution port 52, there should be at least two branch pipes 53 and gas distribution ports 52, and the number of branch pipes 53 and gas distribution ports 52 is not particularly restricted. However, it is preferable that there be, for example, 10 or more branch pipes 53 and gas distribution ports 52, and even better, 20 or more. From the viewpoint of distributing the gas over a wide area in the X direction, it is preferable that the branch pipes 53 are formed over a wide area in the X direction.

[0051] [Plasma ejection opening] The plasma ejection opening 5 is an opening formed between the dielectric substrate 30 and the first member 1. The plasma ejection opening 5 as a whole extends in the X direction and has a narrow opening in the Y direction (see Figure 9 or Figure 11). In this embodiment, the plasma ejection opening 5 is a single slit-shaped opening, but it does not necessarily have to be a single opening. It may be a plurality of openings that extend in the X direction as a whole, such as a plurality of openings connected in a band in the X direction.

[0052] The plasma ejection opening 5 is located at the +Z end of the plasma generation space 27 and communicates with the plasma generation space 27 of the plasma generation unit 20. This causes the plasma-containing gas G1 (see Figure 1 or Figure 2) generated in the plasma generation space 27 to be ejected in a wide area in the X direction. This allows the workpiece surface to be plasma-treated in a strip-like manner. By moving the plasma ejection opening 5 and the workpiece relative to each other while plasma treatment is being performed, the entire workpiece surface can be plasma-treated.

[0053] [Flow Velocity Suppressor] Figure 6 is an enlarged view of the area around the flow velocity suppressor 70 of the first member 1 shown in Figure 3, viewed in the +Z direction. The flow velocity suppressor 70 will be explained with reference to Figure 6 in addition to Figures 2 and 3. The flow velocity suppressor 70 is a flow path having a low conductance structure for reducing the flow velocity of the raw material gas G0. In this embodiment, there are two flow velocity suppressors (70a, 70b) (see Figures 2 and 6).

[0054] The first flow velocity suppressor 70a reduces conductance by narrowing the flow path. Specifically, the first flow velocity suppressor 70a has a structure in which the minimum inner diameter 70i in the space between the gas introduction section 60 and the gas distribution flow path 50 is larger than the flow path diameter (minimum inner diameter) 50i of the gas distribution flow path 50, thereby suppressing the flow velocity of the raw material gas G0 (see Figure 6).

[0055] As shown in Figure 2, in Figure 2, four flows GF of the raw material gas G0 are directed toward the first velocity suppressor 70a. The two central flows pass through the gas distribution channel 50 and either proceed towards the back of the diagram (in the -X direction) or towards the front (in the +X direction). Figure 6 also shows that the first velocity suppressor 70a has two locations: one that goes toward the gas distribution channel 50 on the +X side of the velocity suppressor 70, and another that goes toward the gas distribution channel 50 on the -X side of the velocity suppressor 70. At each of the two ends, a portion of the raw material gas G0 is unable to proceed to the gas distribution channel 50 due to the narrowing of the channel and is bounced back. The bounced back-flowing raw material gas G0 collides with the forward-flowing raw material gas G0, causing the flow velocity of the raw material gas G0 to decrease.

[0056] As shown in Figure 2, the second flow velocity suppressor 70b reduces conductance by providing a branch to the blocked flow path 71. When the flow path branches, a portion of the raw material gas G0 goes to the blocked flow path 71 instead of the gas distribution flow path 50. The raw material gas G0 that is blocked and bounced back in the blocked flow path 71 collides with the raw material gas G0 that is flowing in the forward direction, and as a result the flow velocity of the raw material gas G0 decreases. The end of the blocked flow path 71 has a tapered shape in which the central part protrudes the most in the plane perpendicular to the direction of flow of the flow path. Such a tapered shape generates a strong backflow concentrated in the central part, thus increasing the flow velocity suppression effect.

[0057] The reason why reducing the flow velocity with the flow velocity suppressors (70a, 70b) can equalize the gas distribution rate is explained below. If the flow velocity of the raw material gas G0 is high, the raw material gas G0 flowing through the gas distribution channel 50 will pass through the gas distribution port 52 and proceed through the gas distribution channel 50. As a result, a phenomenon occurs where it is difficult for gas to flow from the gas distribution channel 50 to the branch pipe 53.

[0058] This phenomenon occurs when the gas inlet 60 is located in the center of the gas distribution channel 50. In this case, the gas ejection rate is low near the gas inlet 60, and increases near the end of the gas distribution channel 50, away from the gas inlet 60. However, if the flow velocity of the raw material gas G0 is low, the above phenomenon does not occur, and the raw material gas G0 can flow into the gas distribution port 52 even if it is located near the gas inlet 60. As a result, the difference between the amount of gas flowing through the gas distribution port 52 close to the gas inlet 60 and the amount of gas flowing through the gas distribution port 52 farther away from the gas inlet 60 becomes smaller, and the gas distribution rate can be made more uniform. Furthermore, because the flow rate of the processed gas diffuses sufficiently in the X direction, the amount of plasma processed gas emitted from the plasma ejection opening 5 toward the workpiece becomes uniform in the direction of the slit's extension. In other words, the amount of plasma-containing gas ejected through the plasma generation space 27 becomes more uniform in the X direction.

[0059] A modified example of the flow velocity suppressor is shown. The plasma processing apparatus 200 shown in Figure 7 includes a third flow velocity suppressor 70c in addition to the first flow velocity suppressor 70a. The third flow velocity suppressor 70c is made of a porous material that obstructs the flow of the raw material gas G0. Examples of such porous materials include filters (e.g., nonwoven fabric filters and ceramic filters) and porous metal plates.

[0060] [Flow velocity suppressor for branch pipe] The plasma processing apparatus 100 also has a flow velocity suppressor in the branch pipe 53. Figure 8 is an enlarged view of area P3 in Figure 2. The flow velocity suppressor 55 has a point where the first part 53a of the branch pipe 53 branches into a second part 53b and a closed flow path 51. As the flow path branches, some of the raw material gas G0 goes towards the closed flow path 51 instead of the second part 53b. The raw material gas G0 that is blocked in the closed flow path 51 and bounces back collides with the raw material gas G0 that is flowing in the forward direction, and as a result the flow velocity of the raw material gas G0 decreases.

[0061] Thus, flow velocity suppressors may be provided in the branch pipes 53. A feature of the flow velocity suppressors provided in the branch pipes 53 is that the flow velocity suppression effect can be made different for each branch pipe 53. As mentioned above, when the gas inlet 60 is in the center of the gas distribution channel 50, the amount of gas ejected is small near the gas inlet 60, and the amount of gas ejected increases near the end of the gas distribution channel 50 away from the gas inlet 60. The flow velocity suppression effect may be made small in the branch pipes 53 near the gas inlet 60, and large in the branch pipes 53 far from the gas inlet 60.

[0062] [Components of the Plasma Processing Apparatus] The plasma processing apparatus 100 has been described above, focusing on the flow of gases (G0, G1) inside the plasma processing apparatus 100. Below, the components that make up the plasma processing apparatus 100 will be described in detail. As described above, the plasma processing apparatus 100 is composed of a combination of multiple components. The plasma processing apparatus 100 includes a gas distribution channel 50 and a plurality of gas distribution ports 52, a first component 1 that functions as a second electrode 15, a second component 2 located on the -Z side of the first component 1, a gas introduction pipe 3 inserted into the second component 2 and forming a gas introduction section 60, a dielectric substrate 30 that together with the first component 1 forms a plasma generation space 27 connected to a plasma ejection opening 5, and a first electrode 10 positioned on a part of the +Y direction surface of the dielectric substrate 30.

[0063] As shown in Figure 3, the first member 1 is plate-shaped as a whole, extending in the X and Z directions. As described above, the first member 1 is provided with a gas distribution channel 50 and a plurality of gas distribution ports 52 on the bottom surface of the gas distribution channel 50. The gas distribution channel 50 and the gas distribution ports 52 may be formed by machining.

[0064] In this embodiment, the first member 1 is made of a conductive material to function as the second electrode 15. The first electrode 10 is a plate-like or foil-like material formed on a dielectric substrate 30, extending in the X and Z directions as a whole. The material of the pair of electrodes (10, 15) is not particularly limited, but highly conductive materials are preferred. Typical examples include one or more materials belonging to the group consisting of copper, silver, aluminum, and gold, or compounds of the said materials. Examples of foil-like electrode materials include metal foils such as copper foil and aluminum foil with adhesive processing on one side. The electrodes may also be sintered bodies containing conductive metals. The first electrode 10 and the second electrode 15 may be made of the same material or different materials. The width of at least one of the electrodes, the first electrode 10 and the second electrode 15, in the X direction is preferably greater than or equal to the width of the plasma generation space 27 in the X direction.

[0065] Of the first electrode 10 and the second electrode 15, one is the high-voltage electrode and the other is the low-voltage electrode. In this embodiment, the first electrode 10 is described as the high-voltage electrode connected to the high-voltage power supply device 63 and the second electrode 15 is the low-voltage electrode, but the two can be reversed.

[0066] In this embodiment, the first member 1 functions as the second electrode 15, but the first member 1 may be made of a dielectric material. In that case, it is preferable to provide the second electrode 15 separately from the first member 1.

[0067] The dielectric substrate 30 is preferably made of a material with a low relative permittivity. The relative permittivity of the material is preferably 10 or less. While a lower relative permittivity is preferable, it can typically be between 4 and 10. For example, the dielectric substrate may be made of aluminum oxide (Al) as the main material. ２ O ３ Materials composed of aluminum oxide (ANC) or aluminum nitride (AlN) may be used. Here, "main material" refers to the component that accounts for 80% or more when the constituent materials are analyzed for their components. The dielectric substrate may be made of ceramics (for example, aluminum oxide, aluminum nitride, or steatite). The dielectric substrate may use the aforementioned materials as a base material and contain substances that assist in electron generation, such as silver, platinum, copper, carbon, or transition metal compounds.

[0068] The second member 2 is a rod-shaped structure that extends in the X direction as a whole. The second member 2 has a hole in the center in the X direction into which the gas introduction pipe 3 can be inserted. It is preferable that the cavity connected to the gas introduction pipe 3 be large. This cavity becomes the "space between the gas introduction section 60 and the gas distribution channel 50" as described above. And, as described above, if the minimum inner diameter 70i of this space is larger than the channel diameter (minimum channel inner diameter) 50i of the gas distribution channel 50, then this space becomes the first flow velocity suppressor 70a.

[0069] The gas inlet pipe 3 is cylindrical. In this embodiment, the inner diameter of the cavity in contact with the gas inlet pipe 3 in the second member 2 is the same as the inner diameter of the gas inlet pipe 3, but the inner diameter of the cavity in contact with the gas inlet pipe 3 may be smaller than the inner diameter of the gas inlet pipe 3. This reduces the conductance at the boundary between the gas inlet pipe 3 and the second member 2, thereby obtaining a new flow velocity suppression effect. Furthermore, the various flow velocity suppressors described above may be placed inside the gas inlet pipe 3.

[0070] Embodiments of the plasma processing apparatus and its modified forms have been described above. However, the present invention is not limited in any way to the embodiments and modified forms described above, and various improvements and modifications are possible without departing from the spirit of the present invention.

[0071] For example, in the above embodiment and the modified form, the plasma ejection opening 5 is configured to eject the plasma-containing gas G1 generated in the plasma generation space 27 in the Z direction (as shown in Figure 2, for example), but it is not limited to this. For example, the plasma ejection opening 5 may be configured to eject the plasma-containing gas G1 in the Y direction.

[0072] Furthermore, in the above embodiments and modified forms, the first direction (X direction) and the third direction (Z direction) are configured to be orthogonal (for example, as shown in Figure 2, etc.), but the first direction (X direction) and the third direction (Z direction) may not be configured to be orthogonal.

[0073] 1: First component (second electrode) 2: Second component 3: Gas inlet pipe 5: Plasma ejection opening 10: First electrode 15: Second electrode (first component) 16: Edge (of the second electrode) 20: Plasma generation section 27: Plasma generation space 30: Dielectric substrate 40: Gas buffer substrate 41: Gas buffer space 46: Edge (of the gas buffer substrate) 50: Gas distribution channel 51: Blocked channel (of the branch pipe) 52: Gas distribution port 53: Branch pipe 53a: First part (of the branch pipe) 53b: Second part (of the branch pipe) 54: Raw material gas inlet 55: Flow rate suppressor 59: Raw material gas supply source 60: Gas inlet 61: Gas inlet connection port 63: High voltage power supply 70: Flow rate suppressor 70a : First flow velocity suppressor 70b : Second flow velocity suppressor 70c : Third flow velocity suppressor 71 : Blocked flow path 100, 200 : Plasma processing device G0 : Raw material gas G1 : Plasma-containing gas

Claims

1. A plasma processing apparatus for plasma processing a workpiece by ejecting a plasma-containing gas toward the workpiece, wherein the plasma processing apparatus comprises: (a) a gas introduction section for introducing a raw material gas, which is the raw material for the plasma-containing gas, into the interior of the plasma processing apparatus; (b) a flow velocity suppressor for suppressing the flow velocity of the raw material gas introduced from the gas introduction section; (c) a gas distribution channel having a plurality of gas distribution ports for distributing the raw material gas that has passed through the flow velocity suppressor to the plurality of gas distribution ports; (d) a plasma generation section connected to the plurality of gas distribution ports, wherein the plasma generation section comprises a plasma generation space for generating plasma from the raw material gas, and a plurality of branch pipes connecting each of the plurality of gas distribution ports to the plasma generation space; (e) a pair of electrodes arranged to sandwich the plasma generation space, to which a voltage is applied for plasmaizing the raw material gas in the plasma generation space; and (f) an opening located at one end of the plasma generation space for ejecting the plasma-containing gas.

2. The plasma apparatus according to claim 1, characterized in that the opening of the plasma apparatus extends along a first direction and is narrower along a second direction perpendicular to the first direction, the plasma apparatus having a gas distribution channel that extends along the first direction, a plurality of gas distribution ports arranged along the first direction, and a plurality of branch pipes arranged along the first direction.

3. The plasma generation space is wide along the first direction and a third direction perpendicular to both the first and second directions, and narrow along the second direction, and the pair of electrodes are arranged to sandwich the plasma generation space from both sides of the second direction, as described in claim 2.

4. The plasma processing apparatus according to any one of claims 1 to 3, characterized in that the minimum inner diameter of the space between the gas introduction section and the gas distribution channel is greater than the channel diameter of the gas distribution channel.

5. The plasma processing apparatus according to any one of claims 1 to 3, characterized in that the flow velocity suppressor has a branch between the gas distribution channel and the occluded channel.

6. The plasma processing apparatus according to any one of claims 1 to 3, characterized in that the flow rate suppressor has a porous material that obstructs the flow of the raw material gas.

7. The plasma processing apparatus according to any one of claims 1 to 3, characterized in that the plurality of branch pipes are equipped with flow velocity suppressors.

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