WO2024177066A1

WO2024177066A1 - Plasma processing device

Info

Publication number: WO2024177066A1
Application number: PCT/JP2024/006032
Authority: WO
Inventors: 大輔松尾; 靖典安東
Original assignee: 日新電機株式会社
Priority date: 2023-02-24
Filing date: 2024-02-20
Publication date: 2024-08-29
Also published as: JP2024120292A

Abstract

A plasma processing device (100) for generating plasma in a vacuum container (1) by applying a high-frequency current to an antenna (2) provided outside the vacuum container (1), the plasma processing device comprising: a slit plate (6) that closes an opening (1x), of the vacuum container (1), formed at a position facing the antenna (2); a dielectric plate (7) that closes, from the outside of the vacuum container (1), a plurality of slit openings (6x) formed in the slit plate (6); a plurality of mask members (8) that are provided for the respective slit openings (6x) and that cover the slit openings (6x) from the inside of the vacuum container (1) by being spaced apart from the openings; and a fixation mechanism (9) that fixes the plurality of mask members (8) in correspondence with the respective slit openings (6x).

Description

Plasma Processing Equipment

The present invention relates to a plasma processing device that uses plasma to process a workpiece.

Plasma processing apparatuses have been proposed that generate inductively coupled plasma (abbreviated ICP) by passing a high-frequency current through an antenna, and use the resulting induced electric field to process a substrate or other workpiece. Patent Document 1 discloses such a plasma processing apparatus in which an antenna is placed outside a vacuum vessel, and a high-frequency magnetic field generated from the antenna is transmitted into the vacuum vessel through a magnetic field transmission window that is provided to cover an opening in the side wall of the vacuum vessel, thereby generating plasma within the vacuum vessel.

The plasma processing apparatus of Patent Document 1 includes a metal slit plate that covers the opening of the vacuum vessel, and a dielectric plate that covers the slits formed in the slit plate from the outside of the vacuum vessel. In this plasma processing apparatus, the metal slit plate and the dielectric plate superimposed on the slit plate function as a magnetic field transmission window, so the thickness of the magnetic field transmission window can be made smaller than when only the dielectric plate functions as the magnetic field transmission window. This makes it possible to shorten the distance from the antenna to the inside of the vacuum vessel, and to efficiently supply the high-frequency magnetic field generated by the antenna into the vacuum vessel.

International Publication No. 2020-188809

However, in the configuration of the plasma processing apparatus of Patent Document 1, deposits due to plasma generated near the slits and deposits due to particles wrapped around by sputtering, etc., accumulate on the dielectric plate. If such deposits are conductive, the inner surface forming the slit becomes conductive through the deposits. This causes a high-frequency magnetic field generated by the antenna to cause a high-frequency current to flow in the slit plate along the longitudinal direction of the antenna, and the dielectric plate is heated by the heat generated by the slit plate and the deposits. This results in thermal distortion of the dielectric plate and a decrease in strength due to a chemical reaction between the dielectric plate and the deposits, which may cause the dielectric plate to be damaged.

In order to address such problems, in the plasma processing apparatus of Patent Document 1, for example, it is conceivable to cover the slits from the inside of the vacuum vessel with a mask plate consisting of a single flat plate, leaving a gap. With such a configuration, the slits formed in the slit plate are covered from the inside of the vacuum vessel with the mask plate, so that the dielectric plate is hidden when viewed from inside the vacuum vessel, and it is possible to prevent conductive flying objects, etc. from adhering to and contaminating the dielectric plate.

On the other hand, when a mask plate as described above is provided, it is preferable that the thickness of the mask plate is as thin as possible so as not to reduce the transmittance of the high-frequency magnetic field generated by the antenna. However, since the mask plate described above is a single flat plate, making it thinner will cause the mask plate to warp and become deformed.

The mask plate is heated by the heat of the generated plasma or by radiation from the workpiece by the plasma, so to prevent the mask plate from deforming due to heating, it is desirable for the mask plate to be made of a heavy metal such as Mo or W, which has a small thermal expansion coefficient. On the other hand, in addition to the beam-shaped regions that cover the slits formed in the slit plate, the mask plate also has slits between the beam-shaped regions that allow a magnetic field to pass through. Since Mo or W is difficult to cut, it is difficult to cut the mask plate to form slits, and cutting the mask plate in this way is also costly.

The present invention was made to solve all of these problems at once, and its main objective is to reduce the thickness of the mask member that covers the slits formed in the slit plate and to use a material with a low thermal expansion coefficient for the mask member in a plasma processing apparatus in which an antenna is placed outside the vacuum vessel and a magnetic field transmission window is formed by overlapping a dielectric plate and a slit plate.

In other words, the plasma processing apparatus according to the present invention is a plasma processing apparatus that generates plasma within a vacuum vessel by passing a high-frequency current through an antenna provided outside the vacuum vessel, and is characterized by comprising a slit plate that covers an opening formed in the vacuum vessel at a position facing the antenna, a dielectric plate that covers multiple slit openings formed in the slit plate from the outside of the vacuum vessel, multiple mask members that are provided for each of the slit openings and cover the slit openings from the inside of the vacuum vessel with gaps, and a fixing mechanism that fixes the multiple mask members in correspondence with each of the slit openings.

With this configuration, since a mask member is provided for each slit opening, the size of each mask member is smaller than that of a mask plate in which the slit plate is covered with a single flat plate. Therefore, the mask member is less likely to warp during processing, and the thickness of the mask member can be made thinner. As a result, it is possible to suppress a decrease in the transmittance of the high-frequency magnetic field generated by the antenna.
In addition, since a mask member is provided for each slit opening and there is no need to cut the mask member to form the slits, heavy metals such as Mo or W, which have a small thermal expansion coefficient, can be used as the material for the mask member, and deformation of the mask member due to heating can be suppressed.

It is preferable that the slit opening is rectangular in shape with its longitudinal direction intersecting the antenna, the mask member is elongated and extends from one end of the slit opening to the other end in the longitudinal direction, and the fixing mechanism includes a pressing member that presses the mask member against the slit plate, and a fitting portion formed on the pressing member or the slit plate and that fits into the longitudinal end of the mask member.
With this configuration, the mask member is positioned by the fitting portion, so that it is possible to prevent the mask member from shifting when the pressing member presses the mask member. Also, since the mask member is provided across the longitudinal direction of the slit opening, the mask member can be fixed in correspondence with the slit opening, and it is possible to prevent conductive flying objects and the like from adhering to and contaminating the dielectric plate.

A plurality of the mask members are provided for each of the slit openings, and the plurality of mask members provided for each of the slit openings are provided with gaps between each other to cover the slit openings.
With this configuration, the width of each mask member along the longitudinal direction of the antenna is smaller than when the slit opening is covered with a single mask member, thereby reducing the induced current generated in each mask member and further suppressing the decrease in the transmittance of the high-frequency magnetic field.
Furthermore, since the multiple mask members are provided with gaps between them, it is possible to suppress unevenness in plasma density that may occur along the antenna due to the multiple mask members coming into contact with each other.

The mask members are provided in multiple numbers for each slit opening along the longitudinal direction of the antenna, and are elongated with different longitudinal lengths. In the thickness direction of the slit plate, the mask members longer in the longitudinal direction are arranged toward the inside of the vacuum vessel. The fitting portion is provided along the longitudinal direction of the antenna and further includes a plurality of recesses that fit into the respective ends of the mask members, and is arranged so as to sandwich the end of the mask member that is longer in the longitudinal direction between a communicating wall formed by communicating adjacent portions of the plurality of recesses and an opposing wall provided opposite the communicating wall.
With this configuration, each mask member is fixed in the longitudinal direction of the antenna by the communicating wall and the opposing wall, so that it is possible to prevent each mask member from shifting in the longitudinal direction of the antenna. In particular, when the mask member longer in the longitudinal direction is attached to the slit plate, it is possible to prevent the mask member from falling off the slit plate.
In addition, since adjacent portions of the multiple recesses are connected, the multiple mask members provided for each slit opening are provided without gaps when viewed from inside the vacuum vessel, and therefore the multiple mask members provided for each slit opening cover the dielectric plate without gaps when viewed from inside the vacuum vessel, preventing conductive flying objects and the like from adhering to and contaminating the dielectric plate.

The plasma processing apparatus may have a shielding wall disposed in the gap between the slit plate and the mask member for blocking charged particles moving along the longitudinal direction of the antenna.
With this configuration, the movement of charged particles along the longitudinal direction of the antenna within the gap can be suppressed by the shielding wall, so that generation of plasma between the mask member and the slit plate can be prevented.

In accordance with the present invention, which is configured in this manner, in a plasma processing apparatus in which an antenna is placed outside a vacuum vessel and a magnetic field transmission window is formed by overlapping a dielectric plate and a slit plate, the thickness of the mask member covering the slits formed in the slit plate can be reduced, and a material with a low thermal expansion coefficient can be used for the mask member.

1 is a cross-sectional view illustrating a schematic configuration of a plasma processing apparatus according to an embodiment. FIG. 4 is a perspective view of the configuration near the magnetic field transmission window in the embodiment, as viewed from inside the vacuum vessel. FIG. 4 is an exploded perspective view showing a configuration near a magnetic field transmission window in the embodiment. FIG. 4 is a plan view of the configuration near the magnetic field transmission window in the embodiment, as viewed from inside the vacuum vessel. 5A is a cross-sectional view taken along line AA in FIG. 4, and FIG. 5B is a partially enlarged view of part B in the cross-sectional view taken along line AA. 5 is a cross-sectional view taken along line BB in FIG. 4 . FIG. 11 is a plan view of a configuration in the vicinity of a magnetic field transmission window in another embodiment, as viewed from inside the vacuum vessel. 8A is a cross-sectional view taken along line AA in FIG. 7, and FIG. 8B is a partially enlarged view of part B in the cross-sectional view taken along line AA. Cross-sectional view taken along line BB in FIG. FIG. 11 is a plan view of a configuration in the vicinity of a magnetic field transmission window in another embodiment, as viewed from inside the vacuum vessel. 11A is a cross-sectional view taken along line AA in FIG. 10 , and FIG. 11B is a partially enlarged perspective view of part B in FIG. 10 when the pressing member is removed. FIG. 11 is a cross-sectional view showing a configuration in the vicinity of a magnetic field transmission window when cutting between the antenna and the fixing mechanism along the longitudinal direction of the antenna in another embodiment.

Below, an embodiment of a plasma processing apparatus according to the present invention will be described with reference to the drawings. Note that in all of the drawings shown below, some parts may be omitted or exaggerated as appropriate for ease of understanding. Identical components will be given the same reference numerals and descriptions thereof will be omitted as appropriate.

<Device Configuration>
The plasma processing apparatus 100 of this embodiment processes a substrate O by using an inductively coupled plasma P. Here, the substrate O is, for example, a substrate for a flat panel display (FPD) such as a liquid crystal display or an organic electroluminescence display, a flexible substrate for a flexible display, etc. The processing performed on the substrate O is, for example, film formation by a plasma CVD method, etching, ashing, sputtering, etc.

The plasma processing apparatus 100 is also called a plasma CVD apparatus when film formation is performed by plasma CVD, a plasma etching apparatus when etching is performed, a plasma ashing apparatus when ashing is performed, and a plasma sputtering apparatus when sputtering is performed.

Specifically, as shown in FIG. 1, the plasma processing apparatus 100 comprises a vacuum vessel 1 which is evacuated and into which a gas is introduced, an antenna 2 provided outside the vacuum vessel 1, and a high frequency power supply 3 which applies a high frequency to the antenna 2. In this configuration, by applying a high frequency from the high frequency power supply 3 to the antenna 2, a high frequency current IR flows through the antenna 2, generating an induced electric field within the vacuum vessel 1 and generating an inductively coupled plasma P.

The vacuum vessel 1 is, for example, a metal vessel, and an opening 1x is formed in its wall (here, the upper wall 1a) that penetrates in the thickness direction. The vacuum vessel 1 is electrically grounded here, and its interior is evacuated to a vacuum by a vacuum exhaust device 4.

Gas is introduced into the vacuum vessel 1 via, for example, a flow rate regulator (not shown) or one or more gas inlets 11 provided in the vacuum vessel 1. The gas may be selected according to the processing contents to be performed on the substrate O. For example, when a film is formed on the substrate by plasma CVD, the gas is a raw material gas or a gas obtained by diluting the raw material gas with a dilution gas (for example, H ₂ ). To give a more specific example, when the raw material gas is SiH ₄ , a Si film can be formed on the substrate, when the raw material gas is SiH ₄ +NH ₃ , a SiN film can be formed, when the raw material gas is SiH ₄ +O ₂ , a SiO ₂ film can be formed, and when the raw material gas is SiF ₄ +N ₂ , a SiN:F film (fluorinated silicon nitride film) can be formed.

Inside this vacuum vessel 1, there is provided a substrate holder 5 for holding a substrate O. As in this example, a bias voltage may be applied to the substrate holder 5 from a bias power supply 12. The bias voltage may be, for example, a negative DC voltage, a negative bias voltage, etc., but is not limited to these. By using such a bias voltage, for example, it is possible to control the energy when positive ions in the plasma P are incident on the substrate O, thereby controlling the crystallinity of the film formed on the surface of the substrate O. A heater 51 for heating the substrate O may be provided inside the substrate holder 5.

As shown in FIG. 1, the antenna 2 is arranged to face the opening 1x formed in the vacuum vessel 1. Note that the number of antennas 2 is not limited to one, and multiple antennas 2 may be provided.

The high-frequency power supply 3 can pass a high-frequency current IR through the antenna 2 via a matching circuit 31. The frequency of the high-frequency current is, for example, a typical 13.56 MHz, but is not limited to this and may be changed as appropriate.

This plasma processing apparatus 100 further includes a slit plate 6 that blocks the openings 1x formed in the wall (upper wall 1a) of the vacuum vessel 1 from outside the vacuum vessel 1, a dielectric plate 7 that blocks the slit openings 6x formed in the slit plate 6 from outside the vacuum vessel 1, a plurality of mask members 8 that are provided for each slit opening 6x and cover each slit opening 6x from inside the vacuum vessel 1 with a gap G therebetween, and a fixing mechanism 9 that fixes the plurality of mask members 8 corresponding to each slit opening.

The slit plate 6 allows the high-frequency magnetic field generated by the antenna 2 to pass through the vacuum vessel 1, and prevents the electric field from entering the vacuum vessel 1 from the outside. Specifically, the slit plate 6 is flat, and multiple slit openings 6x are formed through it in the thickness direction. The slit openings 6x are rectangular with their longitudinal direction intersecting the antenna 2. The slit plate 6 preferably has a higher mechanical strength than the dielectric plate 7 described later, and preferably has a larger thickness dimension than the dielectric plate 7. The multiple slit openings 6x are formed parallel to each other when viewed from the thickness direction, and intersect with the antenna 2 (specifically, perpendicular to each other). That is, between the multiple slit openings 6x, a beam-shaped region 6z is formed parallel to each slit opening 6x. The multiple slit openings 6x all have the same shape (specifically, rectangular in plan view), and the length (width) along the longitudinal direction of the antenna 2 is, for example, 5 mm to 30 mm, but is not limited thereto.

To be more specific, the slit plate 6 is manufactured by rolling (e.g., cold rolling or hot rolling) a metal material such as one metal selected from the group including Cu, Al, Zn, Ni, Sn, Si, Ti, Fe, Cr, Nb, C, Mo, W, or Co, or an alloy thereof (e.g., stainless steel alloy, aluminum alloy, etc.), and has a thickness of, for example, about 5 mm. However, the manufacturing method and thickness are not limited to this and may be changed as appropriate depending on the specifications.

The slit plate 6 is larger than the opening 1x of the vacuum vessel in a plan view, and is supported by the upper wall 1a to close the opening 1x. A sealing member S (see FIG. 1), such as an O-ring or gasket, is interposed between the slit plate 6 and the upper wall 1a, creating a vacuum seal between them.

The dielectric plate 7 is provided on the outward surface 61 of the slit plate 6 that faces the outside of the vacuum vessel 1 (the reverse side of the inward surface that faces the inside of the vacuum vessel 1) and covers the slit opening 6x of the slit plate 6.

The dielectric plate 7 is a flat plate made entirely of a dielectric material, and is made of, for example, ceramics such as alumina, silicon carbide, silicon nitride, etc., inorganic materials such as quartz glass and non-alkali glass, and resin materials such as fluororesin (e.g. Teflon). From the viewpoint of reducing dielectric loss, the material making up the dielectric plate 7 preferably has a dielectric tangent of 0.01 or less, and more preferably 0.005 or less.

Here, the thickness of the dielectric plate 7 is made smaller than the thickness of the slit plate 6, but this is not limiting. For example, when the vacuum vessel 1 is evacuated, the thickness needs to be strong enough to withstand the pressure difference between the inside and outside of the vacuum vessel 1 received through the slit openings 6x, and may be set appropriately according to the specifications such as the number and length of the slit openings 6x. However, from the viewpoint of shortening the distance between the antenna 2 and the vacuum vessel 1, a thinner thickness is preferable.

With this configuration, the slit plate 6 and the dielectric plate 7 function as a magnetic field transmission window W that allows the magnetic field generated by the antenna 2 to pass through. In other words, when a high frequency is applied to the antenna 2 from the high frequency power supply 3, the high frequency magnetic field generated by the antenna 2 passes through the magnetic field transmission window W consisting of the slit plate 6 and the dielectric plate 7 and is formed (supplied) inside the vacuum vessel 1. As a result, an induced electric field is generated in the space inside the vacuum vessel 1, and an inductively coupled plasma P is generated.

The mask member 8 is provided on the inward surface 62 of the slit plate 6 that faces the inside of the vacuum vessel 1, and covers the slit opening 6x of the slit plate 6.

Specifically, as shown in Figures 2 to 6, the mask member 8 is elongated and extends from one end 6x1 to the other end 6x2 in the longitudinal direction of the slit opening 6x, and in this embodiment, the mask member 8 is a rectangular flat plate having a longitudinal direction intersecting the antenna 2. More specifically, the longitudinal length of the mask member 8 is longer than the longitudinal length of the slit opening 6x, and the length (width) of the mask member 8 along the longitudinal direction of the antenna 2 is approximately the same as the width of the slit opening 6x along the longitudinal direction of the antenna 2.

The mask member 8 is disposed parallel to the slit opening 6x when viewed from the thickness direction of the slit plate 6, and covers substantially the entire slit opening 6x. The mask member 8 may be formed so as to cover only a portion of the slit opening 6x. From the viewpoint of improving the transmittance of the magnetic field, the narrower the width of the mask member 8, the more preferable it is, e.g., 10 mm or less, and more preferably 5 mm or less.

Furthermore, the multiple mask members 8 are arranged parallel to each other when viewed from the longitudinal direction of the antenna 2. Here, each mask member 8 is arranged so as to intersect with the antenna 2 (specifically, so as to be perpendicular to it), and each has the same flat plate shape. Also, each mask member 8 is arranged parallel to each slit opening 6x when viewed from the thickness direction of the slit plate 6, and each mask member 8 covers almost the entirety of each slit opening 6x.

Moreover, the mask member 8 is made of a metal material such as a heavy metal with a small thermal expansion coefficient, such as Mo or W, or an alloy of these. The thickness of the mask member 8 is preferably smaller than the thickness of the slit plate 6, for example, about 5 mm or less. However, the thickness of the mask member 8 is not limited to this and may be changed as appropriate depending on the specifications.

The fixing mechanism 9 positions and fixes each mask member 8 so that each mask member 8 covers each slit opening 6x. Specifically, as shown in Figures 2 to 6, the fixing mechanism 9 is formed on the slit plate 6 and includes a fitting portion 91 that fits with the longitudinal end of the mask member 8, and a pressing member 92 that presses the mask member 8 against the slit plate 6.

The fitting portion 91 is formed on the inward surface 62 of the slit plate 6 and is provided to correspond to both ends 6x1, 6x2 of the slit opening 6x. In this embodiment, the fitting portion 91 is formed as a recess forming a part of a rectangular parallelepiped, and the recess forming the fitting portion 91 has a longitudinal direction along the longitudinal direction of the antenna 2. Specifically, the longitudinal length of the fitting portion 91 is approximately the same as the length (width) of the mask member 8 along the longitudinal direction of the antenna 2. In addition, one side forming the longitudinal direction of the recess approximately coincides with the inner side of the vacuum vessel 1 at both ends 6x1, 6x2 of the slit opening 6x. Furthermore, the multiple fitting portions 91 are provided along the longitudinal direction of the antenna 2 and are provided parallel to each other and spaced apart by the length (width) of the beam-shaped region 6z along the longitudinal direction of the antenna 2.

In this embodiment, the fitting portion 91 is formed with a mounting surface 91a on which the mask member 8 is placed. Specifically, the mounting surface 91a is provided inside the vacuum vessel 1 relative to the inward surface 62, and each mask member 8 covers each slit opening 6x from the inside of the vacuum vessel 1 with a gap G. This reduces the induced current generated in the mask member 8 and the slit plate along the antenna 2, and efficiently suppresses the decrease in the transmittance of the high frequency magnetic field. The dimension of the gap G between the outward surface of the mask member 8 and the inward surface 62 of the slit plate 6 is preferably set to a value of 5 mm or less.

More specifically, the fitting portion 91 is made of the same material as the slit plate 6, and is manufactured by rolling (e.g., cold rolling or hot rolling) a metal material such as a metal selected from the group including Cu, Al, Zn, Ni, Sn, Si, Ti, Fe, Cr, Nb, C, Mo, W, or Co, or an alloy thereof (e.g., stainless steel alloy, aluminum alloy, etc.). However, the fitting portion 91 does not have to be made of the same material as the slit plate 6.

The pressing member 92 is elongated along the longitudinal direction of the antenna 2, and fits into the fitting portion 91 when the mask member 8 is pressed. Specifically, the pressing member 92 has a plurality of convex portions 921 formed along the longitudinal direction of the pressing member 92, which fit into the concave portions constituting the fitting portion 91, and are arranged parallel to each other and spaced apart by the length (width) of the beam-shaped region 6z along the longitudinal direction of the antenna 2. In this embodiment, the convex portions 921 are rectangular parallelepiped extending along the longitudinal direction of the antenna 2, and the length of the convex portions 921 along the longitudinal direction of the antenna 2 and the length in the direction intersecting the antenna 2 are approximately the same as the longitudinal and lateral lengths of the concave portions of the fitting portion 91, respectively.

In this embodiment, a flow path 6c through which a cooling medium such as water flows is formed (or provided) in the slit plate 6. This flow path 6c is formed along the longitudinal direction of the antenna 2 near the fixing mechanism 9. Here, the flow path 6c is formed so as to be located directly above the fixing mechanism 9 along the thickness direction of the slit plate 6.

<Effects of this embodiment>
According to the plasma processing apparatus 100 of the present embodiment configured as described above, since a mask member 8 is provided for each of the slit openings 6x, the size of each mask member 8 is smaller than that of a mask plate in which the slit plate 6 is covered with a single flat plate. Therefore, the mask member 8 is less likely to warp, and the mask member 8 can be processed to have a thin thickness. As a result, it is possible to suppress a decrease in the transmittance of the high frequency magnetic field generated from the antenna 2.
In addition, since each mask member 8 is provided for each slit opening 6x and there is no need to cut the mask members 8 to form slits, heavy metals such as Mo or W, which have a small thermal expansion coefficient, can be used as the material for the mask members 8, and deformation of the mask members 8 due to heating can be suppressed.

Furthermore, according to the plasma processing apparatus 100 of this embodiment, the mask member 8 is positioned by the fitting portion 91, so that the mask member 8 can be prevented from shifting when the pressing member 92 is pressing the mask member 8. In addition, since the mask member 8 is provided along the longitudinal direction of the slit opening 6x, the mask member 8 can be fixed in correspondence with the slit opening 6x, and conductive flying objects and the like can be prevented from adhering to and contaminating the dielectric plate.

<Other Modified Embodiments>
The present invention is not limited to the above-described embodiment.

In this embodiment, the shape of the mask member 8 is a rectangular flat plate, but the shape of the mask member 8 may be other elongated shapes, such as a column shape.

In this embodiment, the fitting portion 91 is formed on the slit plate 6, but the fitting portion 91 may also be formed on the pressing member 92.

In another embodiment of the plasma processing apparatus 100, as shown in Figs. 7 to 9, a plurality of mask members 8 may be provided for each slit opening 6x, and the mask members 8 provided for each slit opening 6x may be offset from each other to cover the slit opening 6x. In this case, the fixing mechanism 9 allows each mask member 8 to be offset from each other along the longitudinal direction of the antenna 2, and also to be provided with a gap G' between each mask member when viewed from the thickness direction of the slit plate 6. Note that each mask member 8 may or may not overlap each other when viewed from the longitudinal direction of the antenna 2 or the thickness direction of the slit plate 6. The size of the gap G' between each mask member 8 is not particularly limited. Furthermore, although two mask members 8 are provided for each slit opening 6x in Figs. 7 to 9, the number of mask members 8 provided for each slit opening 6x may be three or more.

With this configuration, the width of each mask member 8 along the longitudinal direction of the antenna 2 is smaller than when the slit opening 6x is covered with one mask member 8, so the induced current generated in each mask member 8 can be reduced and the decrease in the transmittance of the high frequency magnetic field can be further suppressed. In addition, since the multiple mask members 8 are provided with a gap G' between them, it is possible to suppress unevenness in plasma density that can occur along the antenna 2 due to the multiple mask members 8 coming into contact with each other.

Also, in another embodiment of the plasma processing apparatus 100, as shown in Figs. 10 and 11, a plurality of mask members 8 are provided for each slit opening 6x along the longitudinal direction of the antenna 2, and are elongated with different longitudinal lengths, and the mask members 8' that are longer in the longitudinal direction may be arranged toward the inside of the vacuum vessel 1 in the thickness direction of the slit plate 6. In this case, the fitting portion 91 may be provided along the longitudinal direction of the antenna 2, and further include a plurality of recesses that fit into the ends of each mask member 8, and may be provided so as to sandwich the end of the mask member 8' that is longer in the longitudinal direction between a communication wall w1 formed by communication between adjacent parts of the plurality of recesses and an opposing wall w2 provided opposite the communication wall w1.

In this embodiment, the fitting portion 91 includes a first recess 911 that fits with the mask member 8 that is shorter in the longitudinal direction, and a second recess 912 that fits with the mask member 8' that is longer in the longitudinal direction. The first recess 911 is provided closer to the ends 6x1 and 6x2 of the slit opening 6x than the second recess 912, and the mounting surface of the first recess 911 on which the mask member 8 is placed is formed between the inward surface 62 of the slit plate 6 and the mounting surface of the second recess 912 on which the mask member 8' is placed, as viewed from the thickness direction of the slit plate 6. In addition, the first recess 911 and the second recess 912 are provided adjacent to each other to form a communicating wall w1, and the second recess 912 has an opposing wall w2 that faces the communicating wall w1. The communicating wall w1 and the opposing wall w2 are provided parallel to each other and spaced apart by approximately the same distance as the short-side length of the mask member 8'.

With this configuration, when each mask member 8 is attached to the slit plate 6, since each mask member 8, 8' is fixed by the communicating wall w1 and the opposing wall w2, it is possible to prevent each mask member 8, 8' from shifting in the longitudinal direction of the antenna 2. In particular, when the mask member 8' which is longer in the longitudinal direction is attached to the slit plate 6, it is possible to prevent the mask member 8' from falling off the slit plate 6.
Furthermore, since adjacent portions of the first recess 911 and the second recess 912 are connected to each other, the mask members 8, 8' provided for each slit opening 6x are provided without any gaps when viewed from inside the vacuum vessel 1. Therefore, the mask members 8, 8' provided for each slit opening 6x cover the dielectric plate 7 without any gaps when viewed from inside the vacuum vessel 1, so that it is possible to prevent conductive flying objects and the like from adhering to and contaminating the dielectric plate 7.

In another embodiment of the plasma processing apparatus 100, a shielding wall SW for shielding charged particles moving along the longitudinal direction of the antenna 2 may be provided in the gap G between the slit plate 6 and the mask member 8. This shielding wall SW may have a wall surface formed to intersect (specifically, perpendicular to) the longitudinal direction of the antenna 2. When viewed from the longitudinal direction of the antenna 2, the shielding wall SW may be formed to shield all or part of the gap G. A plurality of shielding walls SW may be provided along the longitudinal direction of the antenna 2. The plurality of shielding walls SW are preferably parallel to each other and provided at a constant interval (pitch) along the longitudinal direction of the antenna 2. The interval (pitch) between the plurality of shielding walls SW along the longitudinal direction of the antenna 2 may be equal to or different from the interval between the slit openings 6x of the slit plate 6.

Specifically, as shown in FIG. 12, for example, a protrusion 6p that protrudes into the gap G toward the outward surface 81 of the mask member 8 may be formed on the inward surface of the beam-shaped region 6z of the slit plate 6, and this protrusion 6p may form the shielding wall SW. Alternatively, a protrusion that protrudes into the gap G toward the inward surface 62 of the slit plate 6 may be formed on the outward surface 81 of the mask member 8, and this protrusion may form the shielding wall SW.

It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the invention.

In accordance with the present invention, in a plasma processing apparatus in which an antenna is placed outside a vacuum vessel and a magnetic field transmission window is formed by overlapping a dielectric plate and a slit plate, the thickness of the mask member covering the slits formed in the slit plate can be reduced, and a material with a low thermal expansion coefficient can be used for the mask member.

REFERENCE SIGNS LIST 100: Plasma processing apparatus O: Substrate P: Inductively coupled plasma 2: Antenna 3: High frequency power supply 6: Slit plate 6x: Slit opening 7: Dielectric plate 8: Mask member 9: Fixing mechanism 91: Fitting portion 92: Pressing member W: Magnetic field transmission window S: Seal member

Claims

A plasma processing apparatus that generates plasma in a vacuum chamber by passing a high-frequency current through an antenna provided outside the vacuum chamber,
a slit plate for closing an opening formed in the vacuum vessel at a position facing the antenna;
a dielectric plate that covers the plurality of slit openings formed in the slit plate from outside the vacuum vessel;
a plurality of mask members provided for each of the slit openings and covering the slit openings from the inside of the vacuum vessel with gaps;
a fixing mechanism for fixing the plurality of mask members to correspond to each of the slit openings.
The slit opening has a rectangular shape having a longitudinal direction intersecting with the antenna,
the mask member is elongated and extends from one end to the other end in a longitudinal direction of the slit opening,
The fixing mechanism includes:
a pressing member for pressing the mask member against the slit plate;
2. The plasma processing apparatus according to claim 1, further comprising a fitting portion formed on the pressing member or the slit plate, the fitting portion fitting with an end portion of the mask member in the longitudinal direction.
The mask member is provided in plurality for each of the slit openings,
2. The plasma processing apparatus according to claim 1, wherein the mask members provided on the slit opening are spaced apart from one another to cover the slit opening.
The mask member is provided in a plurality of positions for each of the slit openings along the longitudinal direction of the antenna, and has an elongated shape with different longitudinal lengths,
In a thickness direction of the slit plate, a mask member that is longer in a longitudinal direction is disposed toward an inner side of the vacuum vessel,
the fitting portion is provided along a longitudinal direction of the antenna and further includes a plurality of recesses that fit into the ends of the mask members,
3. The plasma processing apparatus of claim 2, wherein the mask members provided in the slit openings are sandwiched between a communication wall formed by communication between adjacent portions of the plurality of recesses and an opposing wall provided in each of the plurality of recesses opposite the communication wall.
The plasma processing apparatus according to any one of claims 1 to 4, wherein a shielding wall is provided in the gap between the slit plate and the mask member to block charged particles moving along the longitudinal direction of the antenna.