JP7489171B2 - Plasma Generator - Google Patents

Description

The present invention relates to a plasma generating device.

In the semiconductor manufacturing process, plasma is used for film formation and etching of semiconductor wafers. Plasma is generated, for example, using a plasma generating device equipped with a plasma tube in which a material gas is introduced and plasma is generated. When plasma is generated, the inside of the plasma tube becomes hot. For this reason, the plasma tube needs to be cooled. Patent Document 1 discloses a plasma generating device in which the cooling effect is enhanced by winding a metal wire for air cooling in a spiral shape around the plasma tube.

Japanese Patent Application Laid-Open No. 10-241893

Quartz is generally used as the material for plasma tubes, but quartz has low thermal conductivity. For this reason, when cooling a plasma tube by wrapping a metal wire around it as in Patent Document 1, heat dissipation is good in the area where the metal wire is in contact with the plasma tube, but heat dissipation is not good in other areas. As a result, the entire plasma tube cannot be cooled well.

This disclosure has been made in light of these circumstances, and its purpose is to provide a plasma generating device that can effectively cool the entire plasma tube.

The plasma generating device according to the present disclosure is a plasma generating device including a plasma tube into which a material gas is introduced and plasma is generated inside, and a heat transfer film containing a material having a higher thermal conductivity than the material of the plasma tube is formed on the entire outer periphery of a part or all of the plasma tube.

In the present disclosure, a heat transfer film made of a material with a higher thermal conductivity than the plasma tube is formed on the outer circumferential surface of the plasma tube. Therefore, the heat of the plasma tube is dissipated by heat exchange between the heat transfer film and the surrounding air.

In the plasma generating device according to the present disclosure, the plasma tube includes a sealing member disposed on the outer periphery of the heat transfer film, and the heat transfer film is formed to include the position where the sealing member is disposed.

In the present disclosure, the plasma tube is provided with a seal member, and a heat transfer film is formed between the plasma tube and the seal member. Therefore, the seal member does not come into direct contact with the plasma tube, and heat does not concentrate on the seal member.

In the plasma generating device according to the present disclosure, a cooler is provided around the end of the plasma tube, and the heat transfer film is formed to include at least a portion of the periphery of the cooler.

In the present disclosure, a cooler is provided at the end of the plasma tube, and the heat transfer film is formed at a portion that is at least partially in contact with the cooler. Therefore, the end of the plasma tube is cooled through the heat transfer film.

In the plasma generating device according to the present disclosure, the plasma tube is provided with a coil wound around the outer circumference to form a magnetic field inside the plasma tube, and the heat transfer film is formed between the end of the plasma tube and the portion around which the coil is wound.

In the present disclosure, a heat transfer film is formed from the end of the plasma tube to the portion that does not contact the coil. Therefore, heat from the end of the plasma tube is dissipated through the heat transfer film. Also, no heat transfer film is formed on the portion where the coil is wound. Therefore, discharge between the coil and the heat transfer film is suppressed.

In the plasma generating device according to the present disclosure, the plasma tube is provided with a coil wound around the outer periphery to form a magnetic field inside the plasma tube, the heat transfer film is conductive and formed over the entire length of the outer periphery of the plasma tube, and an insulating film covering the heat transfer film is formed on the portion of the plasma tube around which the coil is wound.

In the present disclosure, a conductive heat transfer film is formed over the entire length of the outer circumferential surface of the plasma tube. Therefore, the entire plasma tube is cooled by both the coil and the cooler. Furthermore, an insulating film that covers the heat transfer film is formed on the portion of the plasma tube where the coil is wound. Therefore, discharge between the coil and the heat transfer film is suppressed.

In the plasma generating device according to the present disclosure, the plasma tube is provided with a coil wound around the outer periphery to form a magnetic field inside the plasma tube, the heat transfer film includes a first heat transfer film having electrical conductivity and a second heat transfer film having electrical conductivity, and is formed over the entire length of the outer periphery of the plasma tube, and the second heat transfer film is formed on the portion of the plasma tube around which the coil is wound.

In the present disclosure, a conductive heat transfer film and a non-conductive heat transfer film are formed on the entire length of the outer circumferential surface of the plasma tube. Therefore, the entire plasma tube is cooled by both the coil and the cooler. Furthermore, the heat transfer film formed on the portion of the plasma tube where the coil is wound is a non-conductive portion. Therefore, discharge between the coil and the heat transfer film is suppressed.

In the plasma generating device according to the present disclosure, the plasma tube is provided with a coil wound around the outer periphery to form a magnetic field inside the plasma tube, the heat transfer film is conductive, and a slit extending in the longitudinal direction is formed in part of the circumferential direction of the heat transfer film.

In the present disclosure, a slit is formed in a portion of the conductive heat transfer film formed on the outer circumferential surface of the plasma tube. Therefore, the heat transfer film is not continuous in the circumferential direction of the plasma tube.

In the plasma generating device according to the present disclosure, the plasma tube is provided with a coil wound around the outer periphery to form a magnetic field inside the plasma tube, and a heat-resistant and insulating protective film is formed at the end of the plasma tube so as to cover the heat transfer film in the circumferential direction.

In the present disclosure, a protective film having heat resistance and insulating properties is formed to cover the heat transfer film at the end of the plasma tube. Therefore, the heat transfer film at the end of the plasma tube is protected.

According to the present disclosure, heat from the plasma tube is dissipated through heat exchange between the entire surface of the heat transfer film formed on the outer periphery and the surrounding air, allowing the entire plasma tube to be efficiently cooled.

1 is a block diagram showing a configuration of a plasma generation device according to a first embodiment. FIG. 2 is a perspective view showing a configuration of a plasma generating device. FIG. 2 is a perspective view showing the configuration of a plasma tube and a coil. FIG. 2 is a side cross-sectional view showing the connection state of the ends of the plasma tube. 10 is a side cross-sectional view showing the configuration of an end portion of a plasma tube provided in a plasma generating device according to a second embodiment. FIG. 11 is a side cross-sectional view showing the configuration of a plasma tube provided in a plasma generation device according to a third embodiment. FIG. 13 is a side cross-sectional view showing the configuration of a plasma tube provided in a plasma generation device according to a fourth embodiment. FIG. FIG. 13 is a perspective view showing a configuration of a plasma tube provided in a plasma generation device according to a fifth embodiment. 13 is a side cross-sectional view showing the configuration of an end portion of a plasma tube provided in a plasma generating device according to a sixth embodiment. FIG.

Hereinafter, an embodiment of the present invention will be described.
(Embodiment 1)
FIG. 1 is a block diagram showing the configuration of a plasma generator according to the first embodiment. The plasma generator according to the first embodiment is an inductively coupled plasma (ICP) type plasma generator. The plasma generator includes a plasma tube 1 and a coil 2. The plasma tube 1 is a tube made of a non-conductive material such as quartz, and includes an inlet 1a for a material gas at one end in the longitudinal direction and an outlet 1b for sending out a plasma gas at the other end. The coil 2 is configured by winding a conductor made of a conductive material such as copper for an appropriate length around the center of the longitudinal direction of the plasma tube 1, and is connected to a high-frequency power source 3 via an impedance matching circuit 4.

In such a plasma generating device, a high-frequency current supplied from a high-frequency power source 3 flows through an impedance matching circuit 4 to a coil 2 wound around a plasma tube 1. The inside of the plasma tube 1 is kept at a high vacuum, and a material gas is supplied to the inside from an inlet 1a. The material gas inside is converted into plasma by inductive coupling caused by the high-frequency current flowing through the coil 2, and plasma is generated. The generated plasma is sent through an outlet 1b to, for example, a plasma processing chamber (not shown), and used for various processes (etching, etc.). The frequency of the high-frequency current flowing through the coil 2 is, for example, about 1 to 3 MHz.

Figure 2 is a perspective view showing the configuration of the plasma generating device. Coil 2 is an edgewise coil using a conductor wire with a rectangular hollow cross section. A refrigerant pipe 2a passes through the hollow part of the conductor wire, and the refrigerant flows from one end of coil 2 to the other end.

A cooler 5 is provided at both ends of the plasma tube 1. The cooler 5 is made of a material with high thermal conductivity, such as metal. The cooler 5 has a cylindrical portion 51 and a flange portion 52 provided around one end of the cylindrical portion 51, and is attached to the plasma tube 1 with the cylindrical portion 51 facing inward. A refrigerant tube 5a, through which a refrigerant flows, is wound around the boundary between the cylindrical portion 51 and the flange portion 52. The refrigerant tube 5a goes almost completely around the cylindrical portion 51 and is pulled out along the flange portion 52. A slit 53 extending in the longitudinal direction is formed in part of the circumferential direction of the cylindrical portion 51.

Figure 3 is a perspective view showing the configuration of the plasma tube 1 and the coil 2. The plasma tube 1 has small-diameter extensions 11 at both ends. A heat transfer film 8 is formed on the outer circumferential surface of the plasma tube 1 from the tip of the extension 11 to the part that does not contact the coil 2. The formation range of the heat transfer film 8 is shown by hatching in Figure 3. The heat transfer film 8 is a film made of a material that has a higher thermal conductivity than the material of the plasma tube 1, and is formed by a film formation method such as thermal spraying or vapor deposition. The part of the plasma tube 1 where the heat transfer film 8 is formed may be polished to improve the adhesion of the heat transfer film 8. The formation range of the heat transfer film 8 is limited to the part that does not contact the coil 2 in order to suppress discharge between the heat transfer film 8 and the coil 2 through which a high-frequency current flows when the heat transfer film 8 is conductive.

In the plasma generating device according to this embodiment, heat is generated inside the plasma tube 1 when plasma is generated. According to the above configuration, a heat transfer film 8 made of a material having a higher thermal conductivity than the material of the plasma tube 1 is formed on both ends of the outer circumferential surface of the plasma tube 1. Therefore, the heat of the plasma tube 1 is dissipated at the ends by heat exchange between the entire surface of the heat transfer film 8 and the surrounding air, and the plasma tube 1 can be cooled well.

The plasma tube 1 also includes a cooler 5 that is in contact with the heat transfer film 8 formed on both ends. The cooler 5 acts as a heat dissipation fin. Furthermore, by passing a refrigerant through the inside of the refrigerant tube 5a provided in the cooler 5, heat exchange with the refrigerant is performed, thereby improving the cooling performance of the plasma tube 1.

In addition, the coil 2 also functions as a cooler by passing a refrigerant through the inside of the refrigerant tube 2a. Therefore, the heat of the plasma tube 1 is dissipated by the coil 2 in the center and by the heat transfer film 8 in the other parts, so that the entire plasma tube 1 can be cooled effectively.

Furthermore, slits 53 are formed in the cylindrical portion 51 of the cooler 5. If the material of the cooler 5 is conductive, there is a risk that eddy currents induced by the magnetic field generated by the coil 2 will flow in the cooler 5. The slits 53 provided in the cylindrical portion 51 can block the current path and prevent eddy currents from flowing.

The plasma tube 1 constructed as described above is connected to the plasma processing chamber on one side and to the inlet for the material gas on the other side. Figure 4 is a side cross-sectional view showing the connection state of the ends of the plasma tube 1. The flange 52 of the cooler 5 is used as a connection flange, and the plasma tube 1 and the plasma processing chamber (not shown) are connected by aligning the flange 52 with the mating flange 6 provided on the plasma processing chamber.

A seal member 7 is wound around this connection. The seal member 7 is, for example, an O-ring, wound around the extension 11 and elastically contacts the step on the base end side of the extension 11 and a groove provided on the inner periphery of the flange 6, sealing the gap between the flange 52 and the flange 6 airtight. The seal member 7 is made of an elastic material such as rubber, and may harden or deform due to overheating, causing the sealing function to be impaired. A heat transfer film 8 is formed on the outer periphery and step of the extension 11 with which the seal member 7 contacts, and the heat generated inside the plasma tube 1 is dispersed and dissipated in the area where the heat transfer film 8 is formed, as described above, thereby suppressing overheating of the seal member 7 and preventing a decrease in the sealing function.

In this embodiment 1, an example in which the cooler 5 is provided at both ends has been described, but the cooler 5 may be provided only at one end, or the end may not have a cooler 5. The shape of the cooler 5 is also an example and is not particularly limited.

In addition, an edgewise coil made of a conductor with a rectangular cross section has been exemplified as coil 2, but the cross-sectional shape of the conductor that constitutes coil 2 is not particularly limited and may be any other shape. In addition, in this embodiment, an ICP type plasma generator that utilizes inductive coupling of coil 2 has been exemplified, but the plasma generator may be a device of another form.

(Embodiment 2)
The plasma generator according to the second embodiment differs from the first embodiment in the manner in which the heat transfer film 8 is formed. Fig. 5 is a side cross-sectional view showing the configuration of the end of the plasma tube 1 provided in the plasma generator according to the second embodiment. The same components as those in the first embodiment are given the same reference numerals and detailed descriptions thereof are omitted.

In the plasma generating device according to the second embodiment, a heat transfer film 8 is formed on the outer peripheral surface of the extension 11 of the plasma tube 1. According to the above configuration, the heat of the plasma tube 1 is dissipated by the heat transfer film 8 at the ends and by the coil 2 at the center, so that the entire plasma tube 1 can be cooled well. In addition, because the seal member 7 does not come into direct contact with the plasma tube 1, deterioration or damage to the seal member 7 can be prevented.

(Embodiment 3)
The plasma generator according to the third embodiment differs from that according to the first embodiment in the manner in which the heat transfer film 8 is formed. Fig. 6 is a side cross-sectional view showing the configuration of the plasma tube 1 provided in the plasma generator according to the third embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The plasma generator according to the third embodiment includes a heat transfer film 8 formed over the entire length of the outer circumferential surface of the plasma tube 1. The heat transfer film 8 is made of a conductive material such as copper or aluminum. Furthermore, an insulating film 9 is formed over the entire circumference of the portion of the plasma tube 1 where the coil 2 is wound, so as to cover the heat transfer film 8. The material of the insulating film 9 is, for example, ceramic, alumina (aluminum oxide), etc.

With the above configuration, the heat of the plasma tube 1 is dissipated over the entire length of the outer circumferential surface. Furthermore, the heat transfer film 8 transfers the cooling action of the coil 2 and the cooler 5 to the entire plasma tube 1, so the entire plasma tube 1 can be cooled well. In addition, an insulating film 9 is formed on the wound portion of the coil 2, which can prevent discharge from occurring between the coil 2 and the heat transfer film 8.

(Embodiment 4)
The plasma generator according to the embodiment 4 is different from the embodiment 1 in the formation of the heat transfer film 8. Fig. 7 is a side cross-sectional view showing the configuration of the plasma tube 1 provided in the plasma generator according to the embodiment 4. The same components as those in the embodiment 1 are denoted by the same reference numerals and detailed description thereof will be omitted.

The plasma generator according to the fourth embodiment includes a heat transfer film 8 formed over the entire length of the outer circumferential surface of the plasma tube 1. The heat transfer film 8 includes a first heat transfer film 81 made of a conductive material and a second heat transfer film 82 made of a non-conductive material such as alumina. The first heat transfer film 81 is formed over the entire circumference from both ends of the plasma tube 1 to the portion where the coil 2 is wound. The second heat transfer film 82 is formed over the entire circumference of the portion of the plasma tube 1 where the coil 2 is wound.

According to the above configuration, the heat of the plasma tube 1 is dissipated over the entire length of the outer circumferential surface. Furthermore, the cooling action of the coil 2 and the cooler 5 is transmitted to the entire plasma tube 1 by the heat transfer film 8, so that the entire plasma tube 1 can be cooled well. In addition, the second heat transfer film 82 located in the portion where the coil 2 is wound is non-conductive, and there is a distance between it and the conductive first heat transfer film 81, so that discharge between the coil 2 and the first heat transfer film 81 can be suppressed. Note that the second heat transfer film 82 made of a non-conductive material may be formed over the entire length of the outer circumferential surface of the plasma tube 1, but forming the heat transfer film 8 from a conductive material as in embodiment 1 has a higher thermal conductivity.

(Embodiment 5)
In the plasma generator according to the fifth embodiment, a slit 83 is formed in a part of the heat transfer film 8. Fig. 8 is a perspective view showing the configuration of the plasma tube 1 provided in the plasma generator according to the fifth embodiment. The same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted.

The heat transfer film 8 has a slit 83 extending in the longitudinal direction formed in a portion of the circumference of the plasma tube 1. If the material of the heat transfer film 8 is conductive, there is a risk that eddy currents induced by the magnetic field generated by the coil 2 will flow in the heat transfer film 8. With the above configuration, the slit 83 provided in the heat transfer film 8 can block the current path and prevent eddy currents from flowing.

When the cooler 5 has slits 53 and the heat transfer film 8 is formed between the cooler 5 and the plasma tube 1, it is advisable to align the slits 53 of the cooler 5 with the slits 83 of the heat transfer film 8 in the circumferential direction.

(Embodiment 6)
In the plasma generator according to the sixth embodiment, a protective film 10 is further formed on a part of the heat transfer film 8. Fig. 9 is a side cross-sectional view showing the configuration of the end of the plasma tube 1 provided in the plasma generator according to the sixth embodiment. The same components as those in the first embodiment are given the same reference numerals and detailed description thereof will be omitted.

In the plasma generating device according to the sixth embodiment, a protective film 10 is formed on the outer periphery of the heat transfer film 8. The protective film 10 is provided at the end of the plasma tube 1 with a narrow width to cover the heat transfer film 8. The protective film 10 may be formed to cover the end face of the plasma tube 1. The protective film 10 is made of a material with excellent heat resistance and insulating properties, such as alumina.

At the end of the plasma tube 1, when the material gas flows in and the plasma gas flows out, the gas may flow around the outer periphery of the extension 11 and come into contact with the heat transfer film 8 formed on the outer periphery of the extension 11. In particular, at the gas outlet side, the plasma gas particles are very fine, so there is a high possibility that they will flow around to the outer periphery of the extension 11. With the above configuration, a protective film 10 is formed at the end, which prevents damage to the heat transfer film 8.

In each of the above embodiments, it is desirable to form a Faraday shield film on the portion of the plasma tube 1 where the coil 2 is wound in order to weaken the degree of electrostatic coupling between the coil 2 and the plasma. Furthermore, when a Faraday shield film is formed, an insulating film may be formed to suppress discharge between the coil 2 and the Faraday shield film.

In addition, in each of the above embodiments, if a conductive material comes into contact with a non-conductive material, a heterogeneous bond may result, making it difficult to form a coating over a wide area. In such cases, it is desirable to form an intermediate layer made of a functionally gradient material having intermediate physical properties between the conductive material and the non-conductive material, between each of the conductive and non-conductive materials.

The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and equivalents to the scope of the claims.

REFERENCE SIGNS LIST 1 plasma tube 2 coil 5 cooler 7 seal member 8 heat transfer film 9 insulating film 10 protective film 81 first heat transfer film 82 second heat transfer film 83 slit

Claims (6)

A plasma generating apparatus including a plasma tube into which a material gas is introduced and into which plasma is generated,
The plasma tube includes a coil wound around an outer periphery thereof to form a magnetic field inside the plasma tube;
The plasma tube has a heat transfer film formed on the entire outer periphery thereof, the heat transfer film including a material having a higher thermal conductivity than the material of the plasma tube;
The heat transfer film includes a first heat transfer film having electrical conductivity and a second heat transfer film having electrical conductivity, and is formed on the entire length of the outer circumferential surface of the plasma tube;
The plasma generating device, wherein the second heat transfer film is formed on a portion of the plasma tube where the coil is wound. A plasma generating apparatus including a plasma tube into which a material gas is introduced and into which plasma is generated,
The plasma tube includes a coil wound around an outer periphery thereof to form a magnetic field inside the plasma tube;
A plasma generating device in which a heat transfer film containing a material with a higher thermal conductivity than the material of the plasma tube is formed around the entire outer surface only between the tip of the end of the plasma tube and the portion around which the coil is wound. The plasma tube includes a seal member disposed on an outer periphery of the heat transfer film,
The plasma generating device according to claim 1 or 2, wherein the heat transfer film is formed to include a position where the seal member is disposed. A cooler is provided around the end of the plasma tube,
The plasma generating device according to claim 1 , wherein the heat transfer film is formed to include at least a part of a circumferential position of the cooler. The plasma generating device according to claim 1 , wherein the first heat transfer film has a slit extending in a longitudinal direction formed in a part of a circumferential direction. The plasma generating device according to any one of claims 1 to 5, wherein a protective film having heat resistance and insulating properties is formed on a tip of the end of the plasma tube so as to cover the heat transfer film in a circumferential direction.

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