JP2020198282A - Plasma processing apparatus - Google Patents

Abstract

To provide a plasma processing apparatus having an antenna disposed outside a processing chamber, capable of efficiently provide a high frequency magnetic field generated at the antenna to the processing chamber.SOLUTION: A plasma processing apparatus for vacuum processing a work piece placed in a processing charmer using plasma, comprising: a container body that has an opening 211 in a wall constituting the processing charmer; a metal plate 221 that is provided so as to cover the opening 211 and is provided with a slit penetrating in a thickness direction; a dielectric plate 222 that is supported by and in contact with the metal plate 221 and covers the silt from the outside of the processing chamber; and an antenna 3 that is provided outside of the processing chamber so as to face the metal plate 221 and is connected to a high frequency power source and generates a high frequency magnetic field, in which h-D/2>0.7 (h is a distance (mm) between a central axis of the antenna 3 and a surface of the metal plate 221 on an antenna side, and D is a diameter (mm) of the antenna 3) is satisfied.SELECTED DRAWING: Figure 3

Description

The present invention relates to a plasma processing apparatus that processes an object to be processed using plasma.

Conventionally, a plasma processing device that applies a high-frequency current to an antenna, generates inductively coupled plasma (abbreviated as ICP) by an induced electric field generated by the high frequency current, and processes an object to be processed such as a substrate by using this inductively coupled plasma. Proposed by. As such a plasma processing apparatus, Patent Document 1 states that an antenna is arranged outside the vacuum vessel, and a high-frequency magnetic field generated from the antenna is applied inside the vacuum vessel through a dielectric window provided so as to close the opening of the side wall of the vacuum vessel. Disclosed is a device that generates plasma in a processing chamber by allowing it to permeate into a vacuum chamber.

JP-A-2017-004665

However, in the above-mentioned plasma processing apparatus, since the dielectric window is used as a part of the side wall of the vacuum vessel, the dielectric window has sufficient strength to withstand the differential pressure inside and outside the vessel when the inside of the vacuum vessel is evacuated. Must have. In particular, since the dielectric material constituting the dielectric window is ceramics or glass having low toughness, it is necessary to sufficiently increase the thickness of the dielectric window in order to have sufficient strength to withstand the above-mentioned differential pressure. Therefore, when the distance from the antenna to the processing chamber in the vacuum vessel becomes long, the strength of the induced electric field in the processing chamber becomes weak, and there is a problem that the efficiency of plasma generation decreases.

The present invention has been made in view of such a problem, and provides a plasma processing apparatus capable of efficiently supplying a high-frequency magnetic field generated from an antenna to a processing chamber in an antenna arranged outside the processing chamber. The main task is to do.

That is, the plasma processing apparatus according to the present invention vacuum-treats the object to be processed arranged in the processing chamber by using plasma, and has a container body having an opening in the wall forming the processing chamber and the opening. A metal plate provided so as to close and a slit penetrating in the thickness direction is formed, a dielectric plate which is supported in contact with the metal plate and closes the slit from the outside of the processing chamber, and the metal. An antenna provided outside the processing chamber so as to face the plate and connected to a high-frequency power source to generate a high-frequency magnetic field is provided, and the following equation (1) is satisfied.
h-D / 2> 0.7 (1)
Here, h is the distance (mm) between the central axis of the antenna and the surface of the metal plate on the antenna side, and D is the diameter (mm) of the antenna.

That is, the plasma processing apparatus according to the present invention forms a magnetic field transmission window for transmitting a high-frequency magnetic field generated from an antenna to the processing chamber side by a slit formed in a metal plate and a dielectric plate arranged on the slit. ing. With such a configuration, since a part of the members forming the magnetic field transmission window is made of a metal material having a toughness higher than that of a dielectric material such as ceramics, the magnetic field transmission window is formed only by the dielectric material. The thickness of the magnetic field transmission window can be reduced as compared with the case. Further, since the dielectric plate is supported in contact with the metal plate, deformation of the dielectric plate during vacuum processing can be reduced, and bending stress generated in the dielectric plate can be reduced. Therefore, the thickness of the dielectric plate itself can be reduced. As a result, the distance from the antenna to the processing chamber can be shortened, and the high-frequency magnetic field generated from the antenna can be efficiently supplied to the processing chamber.
Further, if the thickness of the dielectric plate is too small, it cannot withstand the differential pressure during vacuum processing and may crack. However, as described above, the distance between the surface of the metal plate and the surface of the antenna is 0.7 mm. Since it is made larger, the thickness of the dielectric plate provided between the antenna and the metal plate can be designed to be thick enough to withstand the differential pressure during vacuum processing.
Further, since the metal plate is provided so as to close the opening of the container body, all the members surrounding the processing chamber, which is the plasma generation space, can be electrically grounded. As a result, the influence of the antenna voltage on the plasma can be reduced, and the electron temperature and the ion energy can be reduced.

If the distance between the surface of the antenna and the surface of the metal plate is too long, it becomes difficult to efficiently supply the high-frequency magnetic field generated from the antenna to the processing chamber. Therefore, it is preferable that the plasma processing apparatus further satisfies the following formula (2).
15 ≧ h−D / 2 (2)

It is preferable that the slit is formed so as to be located between the antenna and the processing chamber when viewed from the thickness direction. With such a case, the high frequency magnetic field generated from the antenna can be more efficiently supplied to the processing chamber.

It is preferable that the antenna has a linear shape and a plurality of the slits are formed in parallel with each other. With such a case, the high-frequency magnetic field can be supplied more uniformly to the processing chamber, so that the plasma density generated in the processing chamber can be made more uniform.

It is preferable that a flow path through which the cooling fluid can flow is formed inside the metal plate.
In such a case, the resistance heat generated by the induced current flowing through the metal plate can be transferred to the cooling fluid and released. As a result, it is possible to suppress the temperature rise of the metal plate during use, suppress the temperature rise due to the radiant heat from the metal plate to the object to be processed, and perform the plasma treatment on the object to be processed more stably.

Examples of the metal plate include those in which the flow paths are formed so as to pass at least between slits adjacent to each other.
When a slit is formed between the antenna and the processing chamber when viewed from the thickness direction, a relatively large induced current flows between adjacent slits in the metal plate (particularly directly under the antenna) and is generated in that portion. The amount of heat is the largest. Therefore, by forming the flow path so as to pass between the slits adjacent to each other, the metal plate can be efficiently cooled and the temperature rise can be efficiently suppressed.

The plasma processing device is attached to the container body so as to close the opening, and includes a window member that forms a magnetic field transmission window that allows a high-frequency magnetic field generated from the antenna to pass through the processing chamber. It is preferable to have a metal plate, the dielectric plate, and a holding frame for holding the metal plate and the dielectric plate.
In such a case, since the window member forming the magnetic field transmission window and the container body are separate members, even if the metal plate is consumed or soiled due to corrosion due to gas or deterioration due to heat, etc. The metal plate can be easily replaced and cleaned by removing the entire window member.

When the angle formed by the slit and the antenna becomes smaller (that is, when it approaches parallel) when viewed from the thickness direction of the metal plate, the induced current flowing through the metal plate increases so as to cancel the high-frequency magnetic field generated from the antenna, and the processing chamber becomes large. The strength of the high-frequency magnetic field supplied to the antenna may decrease.
Therefore, when viewed from the thickness direction of the metal plate, the angle formed by the slit and the antenna is preferably 30 ° or more and 90 ° or less. In this way, since the slit is formed so as to intersect the antenna when viewed from the thickness direction, the induced current flowing through the metal plate along the axial direction of the antenna is cut off by the slit. As a result, the induced current flowing through the metal plate can be reduced, and the strength of the high-frequency magnetic field supplied to the processing chamber can be improved. It is preferable that the angle formed by the slit and the antenna is larger (that is, closer to vertical). The angle is more preferably 45 ° or more and 90 ° or less, and even more preferably about 90 °.

If the width of the slit is too large for the thickness of the metal plate, the electric field generated between the antenna and the metal plate can easily enter the processing chamber through the slit, which may affect the generated plasma. is there.
Therefore, the width dimension of the slit is preferably not less than or equal to the thickness of the metal plate, and more preferably not more than 1/2. As a result, it is possible to suppress the entry of the electric field into the processing chamber and reduce the influence on the generated plasma. The "slit width dimension" as used herein means the length of the slit in the direction along the antenna at a portion overlapping the antenna when viewed from the thickness direction.

The width dimension of the metal plate between the slits adjacent to each other is preferably 15 mm or less, and more preferably 5 mm or less.
By doing so, the induced current flowing through the metal plate can be made smaller, and the strength of the high-frequency magnetic field supplied to the processing chamber can be further improved.

According to the present invention as described above, in an antenna arranged outside the processing chamber, it is possible to provide a plasma processing apparatus capable of efficiently supplying a high frequency magnetic field generated from the antenna to the processing chamber.

The cross-sectional view orthogonal to the longitudinal direction of the antenna which shows typically the whole structure of the plasma processing apparatus of this embodiment. The cross-sectional view along the longitudinal direction of the antenna which shows typically the whole structure of the plasma processing apparatus of the same embodiment. The cross-sectional view along the longitudinal direction of the antenna which shows typically the structure of the window member of the plasma processing apparatus of the same embodiment. The plan view seen from the antenna side which shows typically the structure of the window member of the plasma processing apparatus of the same embodiment. The plan view which shows typically the relationship between the antenna and the slit of the plasma processing apparatus of the same embodiment. The plan view which shows typically the structure of the cooling mechanism which cools a metal plate of the same embodiment. FIG. 5 is a cross-sectional view along the longitudinal direction of the antenna schematically showing the overall configuration of the plasma processing apparatus of another embodiment. The plan view which shows typically the relationship between the antenna and the slit of the plasma processing apparatus of another embodiment. The plan view (a) and the front view (b) schematically show the structure of the metal plate of another embodiment. A graph explaining the effect of the length between slits on the strength of a high-frequency magnetic field. A graph explaining the effect of the slit angle on the strength of a high-frequency magnetic field. A graph explaining the effect of the slit width on the strength of a high-frequency magnetic field. A graph explaining the effect of the thickness of a metal plate on the strength of a high-frequency magnetic field. The graph explaining the relationship between the high frequency power applied to an antenna and the plasma emission intensity. A graph explaining the relationship between the distance between the central axis of the antenna and the surface of the metal plate and the plasma emission intensity.

The plasma processing apparatus according to the embodiment of the present invention will be described below with reference to the drawings. The plasma processing apparatus described below is for embodying the technical idea of the present invention, and the present invention is not limited to the following unless otherwise specified. Further, the contents described in one embodiment can be applied to other embodiments. In addition, the size and positional relationship of the members shown in each drawing may be exaggerated to clarify the explanation.

<Device configuration>
The plasma processing apparatus 100 according to the present embodiment vacuum-treats an object W to be processed such as a substrate by using an inductively coupled plasma P. Here, the substrate is, for example, a substrate for a flat panel display (FPD) such as a liquid crystal display or an organic EL display, a flexible substrate for a flexible display, or the like. The treatment applied to the substrate is, for example, film formation, etching, ashing, sputtering, etc. by the plasma CVD method.

The plasma processing apparatus 100 of the present embodiment is a plasma CVD apparatus when forming a film by a plasma CVD method, a plasma etching apparatus when performing etching, a plasma ashing apparatus when performing ashing, and plasma sputtering when performing sputtering. Also called a device.

Specifically, as shown in FIG. 1, the plasma processing apparatus 100 includes a vacuum container 2 in which a processing chamber 1 that is evacuated and into which gas G is introduced is formed inside, and an antenna provided outside the processing chamber 1. 3 and a high frequency power supply 4 for applying a high frequency to the antenna 3. The vacuum vessel 2 is formed with a magnetic field transmission window 5 for transmitting a high-frequency magnetic field generated from the antenna 3 into the processing chamber 1. When a high frequency is applied from the high frequency power supply 4 to the antenna 3, the high frequency magnetic field generated from the antenna 3 passes through the magnetic field transmission window 5 and is formed in the processing chamber 1, so that an induced electric field is generated in the space inside the processing chamber 1. , This produces an inductively coupled plasma P.

The vacuum container 2 includes a container body 21 and a window member 22 that forms a magnetic field transmission window 5.

The container body 21 is, for example, a metal container, and the processing chamber 1 is formed inside by the wall (inner wall) thereof. An opening 211 penetrating in the thickness direction is formed on the wall of the container body 21 (here, the upper wall 21a). The window member 22 is detachably attached to the container body 21 so as to close the opening 211. The container body 21 is electrically grounded, and the window member 22 and the container body 21 are vacuum-sealed with a gasket such as an O-ring or an adhesive.

The vacuum vessel 2 is configured such that the processing chamber 1 is evacuated by the vacuum exhaust device 6. Further, the vacuum container 2 is configured such that the gas G is introduced into the processing chamber 1 via, for example, a flow rate regulator (not shown) and a plurality of gas introduction ports 212 provided in the container body 21. The gas G may be set according to the processing content to be applied to the substrate W. For example, when performing film formation on a substrate by plasma CVD, the gas G is a gas diluted with the raw material gas or a dilution gas (e.g., H _2). More specifically, when the raw material gas is SiH _4, a Si film is used, when SiH ₄ + NH ₃ is used, a SiN film is used, when SiH ₄ + O ₂ is used, a SiO ₂ film is used, and when SiF ₄ + N ₂ is used, a SiN film is used. : F film (fluoride silicon nitride film) can be formed on the substrate respectively.

Further, a substrate holder 7 for holding the substrate W is provided in the vacuum container 2. As in this example, a bias voltage may be applied to the substrate holder 7 from the bias power supply 8. The bias voltage is, for example, a negative DC voltage, a negative bias voltage, or the like, but is not limited thereto. With such a bias voltage, for example, the energy when the positive ions in the plasma P are incident on the substrate W can be controlled to control the crystallinity of the film formed on the surface of the substrate W. .. A heater 71 for heating the substrate W may be provided in the substrate holder 7.

As shown in FIGS. 1 and 2, a plurality of antennas 3 are provided, and each antenna 3 is arranged outside the processing chamber 1 so as to face the magnetic field transmission window 5. Here, the distance between each antenna 3 and the magnetic field transmission window 5 is set to about 2 mm. Each antenna 3 is arranged so as to be substantially parallel to the surface of the substrate W provided in the processing chamber 1.

Each antenna 3 has the same configuration, and has a linear shape (specifically, a columnar shape) having a length of several tens of centimeters or more in appearance. A high-frequency power supply 4 is connected to the feeding end 3a, which is one end of the antenna 3, via a matching circuit 41, and the terminal 3b, which is the other end, is directly grounded. The terminal portion 3b may be grounded via a capacitor, a coil, or the like.

Here, each antenna 3 has a hollow structure in which a flow path through which the coolant CL can flow is formed. Specifically, as shown in FIG. 2, each antenna 3 includes at least two conductor elements 31 and a capacitor 32 which is a quantitative element electrically connected in series with the conductor elements 31 adjacent to each other. Here, each antenna 3 includes three conductor elements 31 and two capacitors 32. Each conductor element 31 has the same shape as a straight tube (specifically, a circular tube) in which a linear flow path through which the cooling liquid flows is formed. The material of each conductor element 31 is, for example, copper, aluminum, alloys thereof, or metals such as stainless steel, but the material is not limited to this, and may be changed as appropriate.

By configuring each antenna 3 in this way, the combined reactance of the antenna 3 is simply the inductive reactance minus the capacitive reactance, so that the impedance of the antenna 3 can be reduced. As a result, even when the antenna 3 is lengthened, the increase in impedance can be suppressed, the high-frequency current IR easily flows through the antenna 3, and the inductively coupled plasma P can be efficiently generated in the processing chamber 1. ..

The high-frequency power supply 4 can pass a high-frequency current IR through the matching circuit 41 to the antenna 3. The frequency of the high frequency is, for example, 13.56 MHz, which is generally used, but the frequency is not limited to this and may be changed as appropriate.

Thus, in the plasma processing apparatus 100 of the present embodiment, as shown in FIG. 3, the window member 22 includes a metal plate 221 and a dielectric plate 222 provided in order from the processing chamber 1 side toward the antenna 3 side. .. The metal plate 221 is formed with slits 221s penetrating in the thickness direction thereof, and is provided so as to close the opening 211 of the container body 21. The dielectric plate 222 is supported in contact with the metal plate 221 and is provided on the surface of the metal plate 221 on the antenna 3 side so as to close the slit 221s from the outside side (that is, the antenna 3 side) of the processing chamber 1. .. In the plasma processing apparatus 100 of the present embodiment, the magnetic field transmission window 5 is formed by the slit 221s of the metal plate 221 and the dielectric plate 222 that closes the slit 221s. That is, the high-frequency magnetic field generated from the antenna 3 passes through the dielectric plate 222 and the slit 221s and is supplied to the processing chamber 1. The vacuum in the processing chamber 1 is maintained by the metal plate 221 that closes the opening 211 and the dielectric plate 222 that closes the slit 221s of the metal plate 221. In the following description, the thickness direction of the metal plate 221 is simply referred to as the "thickness direction".

The metal plate 221 transmits a high-frequency magnetic field generated from the antenna 3 into the processing chamber 1 and prevents an electric field from entering the processing chamber 1 from outside the processing chamber 1. Specifically, the metal material is rolled (for example, cold rolling or hot rolling) to form a flat plate. Here, the thickness of the metal plate 221 is set to about 5 mm, but the thickness is not limited to this and may be changed as appropriate according to the specifications. The thickness of the metal plate 221 may be as long as it can withstand the differential pressure between the internal and external pressures of the processing chamber 1 during vacuum processing, and is preferably 1 mm or more.

As shown in FIGS. 3 and 4, the metal plate 221 has a shape (here, a rectangular shape) that can cover the entire opening 211 of the container body 21 in a plan view. The area surrounded by the outer peripheral edge of the metal plate 221 is larger than the area of the opening 211 of the container body 21. The metal plate 221 is provided so as to surround the peripheral edge of the opening 211 of the container body 21 on the antenna 3 side so as to be in contact with and supported by the container body 21. The metal plate 221 is arranged so as to be substantially parallel to the surface of the substrate W arranged in the processing chamber 1. The metal plate 221 and the container body 21 are vacuum-sealed by interposing a sealing structure (not shown) between them. Here, the sealing structure is realized by a sealing member such as an O-ring or a gasket or an adhesive provided between the metal plate 221 and the container body 21. These sealing members are provided so as to surround the outer peripheral edge of the opening 211.

In the present embodiment, the metal plate 221 is in electrical contact with the container body 21 and is grounded via the container body 21. Not limited to this, the metal plate 221 may be directly grounded.

The material constituting the metal plate 221 is, for example, one kind of metal selected from the group containing Cu, Al, Zn, Ni, Sn, Si, Ti, Fe, Cr, Nb, C, Mo, W or Co, or one of them. (For example, stainless alloy, aluminum alloy, etc.) may be used. It may also contain trace elements (unavoidable impurities) that are mixed depending on the conditions of raw materials, materials, manufacturing equipment, and the like. From the viewpoint of improving corrosion resistance and heat resistance, the surface of the metal plate 221 on the processing chamber 1 side may be coated.

As shown in FIG. 4, the slit 221s has a rectangular shape having a longitudinal direction in a direction orthogonal to the antenna 3 when viewed from the thickness direction, and is located between the antenna 3 and the processing chamber 1. It is formed directly below the antenna 3. The slits 221s are formed at positions corresponding to each antenna 3. Specifically, a plurality of slits 221s are formed at positions corresponding to one antenna 3. More specifically, one or a plurality of slits 221s are formed at positions corresponding to each conductor element 31 of the antenna 3. In the present embodiment, six slits 221s are formed at positions corresponding to each conductor element 31. The number of slits 221s is not limited to this, and may be appropriately changed according to the specifications. Although each slit 221s has the same shape here, it may have a different shape.

The slits 221s are formed parallel to each other at positions corresponding to each antenna 3 (specifically, each conductor element 31). Specifically, as shown in FIG. 5, each slit 221s is formed so that the angle θ _s formed by the longitudinal direction thereof and the antenna 3 is substantially the same when viewed from the thickness direction. Here, the angle θ _s formed by the slit 221 s and the antenna 3 is set to about 90 °.

Each slit 221s is formed so that its width dimension d _w is substantially the same. The width d _w of the slit 221s is preferably not more than the thickness of the metal plate 221, more preferably about 1/2 or less, more preferably about 1/3 or less.

The slits 221s are formed at equal intervals along the antenna 3 at a predetermined pitch length d _p. As shown in FIG. 5, the “pitch length” here is the distance between the center positions of the slits 221s adjacent to each other in the direction along the antenna 3.

Further, the slits 221s are formed so that the width dimensions of the metal plates 221 between the slits 221s adjacent to each other are the same. The "width dimension of the metal plate between the slits adjacent to each other" (hereinafter, also simply referred to as "the length between the slits") is the width dimension d _w of the slit 221s from the pitch length d _p of the slit 221s. It is the subtracted length. The length _{d s} between the slits is preferably 15mm or less, and more preferably 5mm or less.

The plasma processing apparatus 100 of the present embodiment includes a cooling mechanism 9 for cooling the metal plate 221. Specifically, as shown in FIG. 6, the cooling mechanism 9 has a flow path 91 formed inside the metal plate 221 through which the cooling fluid can flow and a cooling fluid supply for supplying the cooling fluid to the flow path 91. It is equipped with a mechanism (not shown). Both ends of the flow path 91 are open to the surface of the metal plate 221. The cooling fluid is supplied to the flow path 91 through one opening 91a and discharged from the other opening 91b.

The flow path 91 is formed so that a fluid flows in one direction from one opening 91a to the other opening 91b. Here, the flow path 91 is provided corresponding to each antenna 3 (specifically, the conductor element 31). The flow path 91 includes a first flow path portion 91x formed parallel to the lateral direction of the slit 221s and a second flow path portion 91y formed parallel to the longitudinal direction of the slit 221s. Combined, they are formed to meander between the plurality of slits 221s. The flow path 91 is formed so as to pass at least between the slits 221s adjacent to each other. More specifically, the second flow path portion 91y is formed so as to pass through the central portion between the slits 221s adjacent to each other. The cooling fluid supplied to the flow path 91 may be either a liquid or a gas.

The dielectric plate 222 transmits the high-frequency magnetic field generated from the antenna 3 into the processing chamber 1 and closes the slit 221s to maintain the vacuum in the processing chamber 1. Specifically, the dielectric plate 222 has a flat plate shape entirely composed of a dielectric substance. Here, the plate thickness of the dielectric plate 222 is made smaller than the plate thickness of the metal plate 221, but the plate thickness is not limited to this. A thinner one is preferable from the viewpoint of shortening the distance between the antenna 3 and the processing chamber 1. The thickness of the dielectric plate 222 may be sufficient to withstand the differential pressure between the inside and outside of the processing chamber 1 received from the slits 221s when the processing chamber 1 is evacuated, and the number and length of the slits 221s and the dielectric material may be sufficient. It may be appropriately set according to the specifications such as the material of the plate 222. For example, when the width dimension d _w of the slit 221 s is 20 mm, the length dimension d _l of the slit 221 _s is 30 mm, the length between the slits d _s is 5 mm, and the dielectric plate 222 is made of non-alkali glass, the dielectric plate The plate thickness of 222 is preferably 0.7 mm or more.

The material constituting the dielectric plate 222 is a known material such as ceramics such as alumina, silicon carbide and silicon nitride, inorganic materials such as quartz glass and non-alkali glass, and resin materials such as fluororesin (for example, Teflon). Good. From the viewpoint of reducing dielectric loss, the material constituting the dielectric preferably has a dielectric loss tangent of 0.01 or less, and more preferably 0.005 or less.

The dielectric plate 222 is provided on the surface of the metal plate 221 on the antenna 3 side so as to cover and close the plurality of slits 221s formed in the metal plate 221. Specifically, the dielectric plate 222 is in contact with the surface of the metal plate 221 on the antenna 3 side so as to surround and adhere to the periphery of the plurality of slits 221s. The dielectric plate 222 and the metal plate 221 are vacuum-sealed by interposing a sealing structure (not shown) between them. Here, the sealing structure is realized by a sealing member such as an O-ring or a gasket or an adhesive provided between the dielectric plate 222 and the metal plate 221. These sealing members may be provided so as to surround all of the plurality of slits 221s at once, or may be provided so as to individually surround the plurality of slits 221s. Further, when the dielectric plate 222 is made of a material having high elasticity such as a resin material, the sealing structure may be realized by the elastic force of the dielectric plate 222.

The window member 22 further includes a holding frame 223 that holds the metal plate 221 and the dielectric plate 222. The holding frame 223 holds the metal plate 221 and the dielectric plate 222 by pressing them against the upper surface 21b of the container body 21. As shown in FIGS. 3 and 4, the holding frame 223 has a flat plate shape and is arranged on the dielectric plate 222 so as to be substantially parallel to the surface of the substrate W provided in the processing chamber 1. There is. Specifically, the lower surface of the holding frame 223 is arranged so as to be in contact with the upper surfaces of the dielectric plate 222 and the metal plate 221. The holding frame 223 is detachably attached to the upper surface 21b of the container body 21 by a fixing member (not shown) such as a screw mechanism.

The material constituting the holding frame 223 is, for example, one kind of metal selected from the group containing Cu, Al, Zn, Ni, Sn, Si, Ti, Fe, Cr, Nb, C, Mo, W or Co. It may be an alloy thereof or the like. Further, from the viewpoint of reducing the induced current flowing inside, the holding frame 223 is preferably made of a dielectric material. Examples of such a dielectric material include ceramics such as alumina, silicon carbide and silicon nitride, inorganic materials such as quartz glass and non-alkali glass, and resin materials such as fluororesin (for example, Teflon). Further, it is preferable that the fixing member such as a bolt for fixing the holding frame 223 is also made of a dielectric material such as ceramic as in the holding frame 223.

A plurality of elongated hole-shaped openings 223о penetrating in the thickness direction are formed in the holding frame 223, and the dielectric plate 222 is exposed from the openings 223о. As shown in FIG. 4, the opening 223о is formed at a position corresponding to each antenna 3 (specifically, each conductor element 31). More specifically, the opening 223о is formed so as to surround each antenna 3 and the magnetic field transmission window 5 at a position corresponding thereto when viewed from the thickness direction. Here, nine openings 223о are formed to correspond to the three antennas 3 (ie, the nine conductor elements 31).

The plasma processing apparatus 100 of the present embodiment may include a holding frame cooling mechanism (not shown) for cooling the holding frame 223. The holding frame cooling mechanism may cool the holding frame 223 by, for example, water cooling or air cooling means. In the case of water cooling, the holding frame 223 may be configured to be cooled by having a hollow structure having a flow path through which the coolant can flow. In the case of air cooling, the holding frame 223 may be cooled by blowing air from a fan or the like.

Further, in the plasma processing apparatus 100 of the present embodiment, as shown in FIG. 3, the diameter of the antenna 3 (specifically, the diameter of each conductor element 31) D (mm) and the central axis of the antenna 3 (specifically, the central axis of the antenna 3) (specifically). , The central axis of each conductor element 31) and the distance h (mm) between the surface of the metal plate 221 on the antenna 3 side so that the antenna 3 satisfies the following equations (1) and (2). The position of is set.
h-D / 2> 0.7 (1)
15 ≧ h−D / 2 (2)
The value of "hD / 2" in the above equations (1) and (2) is at the position where the distance between the surface of the antenna 3 and the surface of the metal plate 221 on the antenna 3 side is the shortest. , H (mm) and D (mm) are used for calculation.

<Effect of this embodiment>
According to the plasma processing apparatus 100 of the present embodiment configured in this way, a part of the window member 22 forming the magnetic field transmission window 5 is made of a metal material having a toughness higher than that of a dielectric material such as ceramics. Therefore, the thickness of the magnetic field transmission window 5 can be reduced as compared with the case where the magnetic field transmission window 5 is formed only by the dielectric material. As a result, the distance from the antenna 3 to the processing chamber 1 can be shortened, and the high-frequency magnetic field generated from the antenna 3 can be efficiently supplied into the processing chamber 1.
Further, since the metal plate 221 is provided so as to close the opening 211 of the container body 21, all the members surrounding the processing chamber 1 which is the plasma generation space can be electrically grounded. As a result, the influence of the voltage of the antenna 3 on the plasma can be reduced, and the electron temperature and the ion energy can be reduced.

<Other modified embodiments>
The present invention is not limited to the above embodiment.

In the above embodiment, the metal plate 221 has a flat plate shape, but the present invention is not limited to this. In another embodiment, as shown in FIG. 7, the surface on which the dielectric plate 222 is placed may be configured to be located closer to the substrate W than the upper wall 21a of the container body 21. With such a configuration, the antenna 3 can be brought closer to the processing chamber 1, so that the plasma density formed in the processing chamber 1 can be further improved.

In the above embodiment, the angle θ _s formed by the slit 221 s and the antenna 3 is about 90 °, but the angle is not limited to this. In other embodiments, the angle theta _s is about 30 ° or more, it may be any angle theta _s of less than about 90 °. The angle θ _s is more preferably about 60 ° or more and about 90 ° or less, and most preferably about 90 °.

In another embodiment, as shown in FIG. 8, in addition to the slit 221s in which the angle θ _s formed with the antenna 3 is about 30 ° or more and about 90 ° or less, the angle formed with the antenna 3 is about 0 ° or more. A slit 221t of less than about 30 ° may be further formed in the metal plate 221. In this case, the angle formed by the slit 221t with the antenna 3 is preferably 0 °. Further, it is preferable that the slit 221t is formed so as to be located directly below the antenna 3.

In the above embodiment, the slits 221s are formed so as to be parallel to each other, but the present invention is not limited to this. The slits 221s may be formed so that the angles formed with the antenna 3 are different from each other.

The slit 221s may not be formed at a constant pitch length d _p. For example, when the width dimension d _w of the slit 221 s is constant, the pitch length d _p and the inter-slit length d _s are increased in the vicinity of the center position in the longitudinal direction of the antenna 3 (specifically, the conductor element 31). The pitch length d _p and the slit length d _s may be reduced as the antenna 3 approaches both ends in the longitudinal direction. In this way, the plasma density along the length direction of the antenna 3 can be made uniform in the processing chamber 1.

Further, each of the width _{d w} of the slit 221s may not be the same. For example, if the slit 221s is formed at a constant pitch length d _p, the center vicinity in the longitudinal direction of the antenna 3, to reduce the width dimension d _w (i.e., increased inter-slit length d _s), The width dimension d _w may be increased (that is, the interslit length d _s may be decreased) as the antenna 3 approaches both ends in the longitudinal direction. In this way, the plasma density along the length direction of the antenna 3 can be made uniform in the processing chamber 1.

In the above embodiment, only one second flow path portion 91y is formed between the adjacent slits 221s, but the present invention is not limited to this, and a plurality of second flow path portions 91y may be formed. Further, the flow path 91 is not limited to the one formed without branching from one opening 91a to the other opening 91b, and may be formed so as to branch in the middle. Further, the openings 91a and 91b do not have to be provided at both ends of the flow path 91, and may be provided in the middle of the flow path 91.

The plasma processing apparatus of the above embodiment includes, but is not limited to, one metal plate 221. In another embodiment, a plurality of metal plates 221 stacked in the thickness direction may be provided. In this case, the constituent materials of the metal plates 221 may be different from each other, or may be the same constituent material.

In the above embodiment, the window member 22 is attached to the upper surface 21b of the container body 21, but the present invention is not limited to this. In another embodiment, it may be attached to a flange or the like provided on the upper surface of the container body 21.

In the above embodiment, a plurality of openings 223о of the holding frame 223 are formed at positions corresponding to the respective conductor elements 31, but the present invention is not limited to this. In another embodiment, one opening may be formed so as to surround all the conductor elements 31 when viewed from the thickness direction.

The plasma processing device 100 of the above-described embodiment is provided with a plurality of antennas 3, but the present invention is not limited to this, and only one antenna 3 may be provided.

In the plasma processing apparatus 100 of the above-described embodiment, the antenna 3 includes a plurality of conductor elements 31 and a capacitor 32 which is a quantitative element electrically connected in series with the conductor elements 31 adjacent to each other. Not limited to. In other embodiments, the antenna 3 may include only one conductor element 31 and not the capacitor 32.

In the plasma processing apparatus 100 of another embodiment, as shown in FIG. 9, an opening is formed in the side surface 2211 of the metal plate 221 and the side plate 92 may be fitted so as to close the opening. Then, a part of the inner side wall of the flow path 91 (here, the first flow path portion 91x) may be formed by the side surface 921 of the side plate. Such a flow path 91 forms a second flow path portion 91y by cutting from the side surface 2211 of the metal plate 221 along the longitudinal direction of the slit, and cuts along the direction orthogonal to the longitudinal direction of the slit. As a result, the first flow path portion 91x can be formed, and the side plate 92 can be provided so as to close the opening formed on the side surface 2211 by the cutting process. Of course, the flow path 91 may be formed by another method.

In the above embodiment, the antenna 3 is a linear conductor, but the antenna 3 is not limited to this, and may be a spiral type conductor or a dome-shaped coil.

In addition, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

<Evaluation of high frequency magnetic field strength>
The effect on the high frequency magnetic field due to the difference in the specifications of the metal plate 221 (slit length d _s , slit angle θ _s , slit width d _w , plate thickness, etc.) in the above-mentioned plasma processing apparatus 100 was evaluated experimentally. It should be noted that the present invention is not limited by the following experimental examples, and it is possible to carry out the present invention with modifications to the extent that it can be adapted to the above and the following purposes, and all of them are within the technical scope of the present invention. Included.

(1) Effect of slit length d _{s The} effect of slit length d _{s on} a high-frequency magnetic field was evaluated. Specifically, six metal plates having a thickness of 10 μm made of a stainless alloy (SUS316) were prepared. Each metal plate, a slit width of 0.5 mm, the slit length between _{d s} is set to be different each (respectively 0mm, 5mm, 15mm, 45mm, 70mm, 140mm) were formed. The slits formed in each metal plate were set so that the angle θ _s formed with the antenna to be set later was 90 °. Then, a high-frequency magnetic field is supplied to each metal plate from an antenna provided on one surface side, and the parallel magnetic field strength of the high-frequency magnetic field transmitted to the opposite surface side (processing chamber side) is measured using a one-turn pickup coil. did. Here, 150 W of high frequency power (frequency: 13.56 MHz) was supplied to the antenna to generate a high frequency magnetic field. Then, the ratio of the parallel magnetic field strength in each metal plate (magnetic field strength ratio) to the parallel magnetic field strength in the metal plate having a slit length of 0 mm was calculated. The result is shown in FIG.

From the results shown in FIG. 10, it was found that the shorter the slit length, the more efficiently the high-frequency magnetic field generated from the antenna can be supplied to the processing chamber side. In particular, it was found that the parallel magnetic field strength became stronger when the slit length was about 15 mm or less, and further strengthened when the slit length was about 5 mm or less.

(2) Effect of slit angle θ _{s The} effect of the slit angle θ _s on the high-frequency magnetic field was evaluated. Specifically, four metal plates having a thickness of 10 μm made of a stainless alloy (SUS316) were prepared. Slits having a constant width dimension (0.5 mm) were formed in parallel on each metal plate with a constant pitch length (5 mm). Here, the slits formed in each metal plate have different angles θ _s (slit angles θ _s ) with the antenna to be set later (90 °, 60 °, 45 °, and 30 °, respectively). Then, the parallel magnetic field strength on the processing chamber side of each metal plate was measured by the same procedure as in (1) above. Then, the ratio of the parallel magnetic field strength in each metal plate (magnetic field strength ratio) to the parallel magnetic field strength in the metal plate having the slit angle θ _s of 90 ° (that is, the slit is orthogonal to the antenna) was calculated. The result is shown in FIG.

From the results shown in FIG. 11, it was found that the high-frequency magnetic field generated from the antenna can be efficiently supplied to the processing chamber side at any slit angle θ _s from 30 ° to 90 °. It was found that the larger the slit angle θ _s , that is, the closer to the right angle to the antenna, the more efficiently the high-frequency magnetic field can be supplied. In particular, it was found that the parallel magnetic field strength became stronger when the slit angle θ _s was set to about 45 ° or more, and further strengthened when the slit angle θ _s was set to about 60 ° or more.

(3) evaluated the effect of the high-frequency magnetic field by the slit width d _w due slit width d _w. Specifically, three metal plates (Cu) having a thickness of 1 mm were prepared. Slits having different width dimensions (1 mm, 3 mm, 5 mm) were formed on each metal plate with a predetermined inter-slit length (5 mm). That is, the pitch lengths of the slits in each metal plate were set to 6 mm, 8 mm, and 10 mm, respectively. The slits formed in each metal plate were set so that the angle θ _s formed with the antenna to be set later was 90 °. Then, the parallel magnetic field strength on the processing chamber side of each metal plate was measured by the same procedure as in (1) above. Further, a metal plate having a slit pitch of 0 mm (that is, the slits were formed so as to be continuous and completely opened) was prepared, and the parallel magnetic field strength was measured by the same procedure. The ratio of the parallel magnetic field strength in each metal plate (magnetic field strength ratio) to the parallel magnetic field strength in the metal plate having a slit pitch of 0 mm was calculated. The result is shown in FIG.

From the results shown in FIG. 12, it was found that the high-frequency magnetic field generated from the antenna can be efficiently supplied to the processing chamber side regardless of the slit width of 1 mm to 5 mm. It was found that the larger the slit width, the more efficiently the high-frequency magnetic field can be supplied.

(4) Effect of thickness of metal plate The effect of the thickness of the metal plate on the high-frequency magnetic field was evaluated. Specifically, a metal plate (Cu) having a thickness of 1 mm and a metal plate (Cu) having a thickness of 3 mm were prepared. A slit having a width dimension of 3 mm was formed in each metal plate with a pitch length of 8 mm. The slits formed in each metal plate were set so that the angle θ _s formed with the antenna to be set later was 90 °. Then, the parallel magnetic field strength on the processing chamber side of each metal plate was measured by the same procedure as in (1) above. Here, the parallel magnetic field strength was measured by changing the high frequency power supplied to the antenna by 50 W from 100 W to 300 W. Then, for each magnitude of the high-frequency power to be supplied, the ratio of the parallel magnetic field strength in the metal plate having a thickness of 3 mm (magnetic field strength ratio) to the parallel magnetic field strength in the metal plate having a thickness of 1 mm was calculated. The result is shown in FIG.

From the results shown in FIG. 13, the parallel magnetic field strength of the metal plate having a thickness of 1 mm was larger than the parallel magnetic field strength of the metal plate having a thickness of 3 mm, regardless of the magnitude of the high-frequency power supplied to the antenna. From this, it was found that the smaller the thickness of the metal plate, the more efficiently the high-frequency magnetic field generated from the antenna can be supplied to the processing chamber side.

<Evaluation of plasma emission intensity>
(1) Effect of the magnitude of high-frequency power on the plasma emission intensity In the plasma processing apparatus 100 of the above-described embodiment, the high-frequency magnetic field generated from the antenna 3 is transmitted through the magnetic field transmission window 5 to transmit the plasma P into the processing chamber 1. It was confirmed that it could occur as follows.

Specifically, a metal having a plate thickness of 3 mm made of a Cu alloy in which a plurality of slits 221 s (width dimension d _w is 3 mm, length dimension d _l is 30 mm, and interslit length d _s is 3 mm) is formed in the thickness direction. A plate 221 and a dielectric plate 222 having a plate thickness of 0.6 mm were prepared, and these were held by the holding frame 223 in the same manner as in the above embodiment and attached to the container body 21. An antenna 3 having a diameter D of 6 mm was used, and the antenna 3 was provided so that the distance h between the central axis of the antenna 3 and the surface of the metal plate 221 on the antenna 3 side was 4.5 mm. Then, after the vacuum vessel 2 was evacuated, the pressure in the processing chamber 1 was adjusted to 18 × 10 ^-3 Torr while introducing 7.0 sccm of Ar gas. Then, high-frequency power (frequency: 13.56 MHz) was supplied to the antenna 3 while changing the power value, and the emission intensity of the plasma P generated in the processing chamber 1 was measured by an emission spectroscopic analyzer. The result is shown in FIG. As can be seen from FIG. 14, the high-frequency magnetic field generated from the antenna 3 is transmitted through the magnetic field transmission window 5 by covering the metal plate 221 on which the slit 221s is formed with the dielectric plate 222 to form the magnetic field transmission window 5. It was confirmed that plasma P can be generated in the processing chamber 1.

(2) Effect of distance between the central axis of the antenna and the surface of the metal plate on the plasma emission intensity Next, in the plasma processing apparatus 100 used in the evaluation of (1) above, the central axis of the antenna 3 and the surface of the metal plate 221 are The effect of this on the plasma emission intensity was evaluated by changing the distance between them. Specifically, the distance h between the central axis of the antenna 3 and the surface of the metal plate 221 on the antenna 3 side is changed from 4.5 mm to 11 mm, and 1000 W of high frequency power is supplied to the antenna 3. The emission intensity of the plasma P generated in the processing chamber 1 was measured by an emission spectroscopic analyzer. The result is shown in FIG. As can be seen from FIG. 15, the emission intensity of the plasma P generated in the processing chamber 1 is generally proportional to the reciprocal of the distance h between the central axis of the antenna 3 and the surface of the metal plate 221 on the antenna 3 side, and the distance h. It was found that the shorter the value, the stronger the emission intensity of the plasma P. Further, when the emission intensity at h = 4.5 mm is set as a reference value (100%) and the emission intensity of 25% is set as the lower limit for vacuum processing, the distance h at the lower limit is about 18 mm, and "h-". The value of "D / 2" was about 15 mm.

100 ・ ・ ・ Plasma processing device 1 ・ ・ ・ Processing room 21 ・ ・ ・ Container body 211 ・ ・ ・ Opening 221 ・ ・ ・ Metal plate 221s ・ ・ ・ Slit 222 ・ ・ ・ Dielectric plate 3 ・ ・ ・ Antenna 4 ・ ・・ High frequency power supply 5 ・ ・ ・ Magnetic field transmission window

Claims (13)

A plasma processing device that vacuum-processes an object to be processed placed in a processing chamber using plasma.
A container body having an opening in the wall forming the processing chamber,
A metal plate provided so as to close the opening and having a slit penetrating in the thickness direction.
A dielectric plate that is supported in contact with the metal plate and closes the slit from the outside of the processing chamber.
An antenna provided outside the processing chamber so as to face the metal plate and connected to a high-frequency power source to generate a high-frequency magnetic field is provided.
A plasma processing device that satisfies the following equation (1).
h-D / 2> 0.7 (1)
Here, h is the distance (mm) between the central axis of the antenna and the surface of the metal plate on the antenna side, and D is the diameter (mm) of the antenna. The plasma processing apparatus according to claim 1, further satisfying the following formula (2).
15 ≧ h−D / 2 (2) The plasma processing apparatus according to claim 1 or 2, wherein the slit is formed so as to be located between the antenna and the processing chamber when viewed from the thickness direction. The antenna has a linear shape.
The plasma processing apparatus according to any one of claims 1 to 3, wherein the plurality of slits are formed in parallel with each other. The plasma processing apparatus according to any one of claims 1 to 4, wherein a flow path through which a cooling fluid can flow is formed inside the metal plate. The plasma processing apparatus according to claim 5, wherein the flow path is formed so as to pass at least between slits adjacent to each other. A window member is provided which is attached to the container body so as to close the opening and forms a magnetic field transmission window for transmitting a high-frequency magnetic field generated from the antenna into the processing chamber.
The plasma processing apparatus according to any one of claims 1 to 6, wherein the window member includes the metal plate, the dielectric plate, and a holding frame for holding the metal plate and the dielectric plate. The plasma processing apparatus according to any one of claims 1 to 7, wherein the angle formed by the slit and the antenna when viewed from the thickness direction is 30 ° or more and 90 ° or less. The plasma processing apparatus according to claim 8, wherein the angle formed by the slit and the antenna is 45 ° or more and 90 ° or less. The plasma processing apparatus according to any one of claims 1 to 9, wherein the width dimension of the slit is equal to or less than the thickness of the metal plate. The plasma processing apparatus according to claim 10, wherein the width dimension of the slit is ½ or less of the plate thickness of the metal plate. The plasma processing apparatus according to claim 4, wherein the width dimension of the metal plate between the slits adjacent to each other is 15 mm or less, or claims 5 to 11 quoting claim 4. The plasma processing apparatus according to claim 12, wherein the width dimension of the metal plate between the slits adjacent to each other is 5 mm or less.