JPH111776A - Gas treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of a formed film by uniformizing the surface temp. distribution of a body to be treated and to inhibit the generation of particles by preventing the occurrence of corrosion of a feeder for a resistance heating wire, a terminal, etc. SOLUTION: A feeder 35 is drawn out from a resistance heating wire 33 which is buried in a ceramic heater 22 of a support base for the purpose of heating a wafer as a body to be treated. The feeder 35 is allowed to penetrate through the wall of a treatment chamber and extended to the outside of the treatment chamber. A sheath bellows 38 holding the feeder 35 in an insulated state is provided between the ceramic heater 22 and the bottom plate part 24 of the treatment chamber 20. An end piece 39 of the sheath bellow 38 is joined to the ceramic heater 22 by means of a screw 40. Further, the screw 40 is so attached that it can allow for the thermal expansion of the sheath bellows 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention improves the uniformity of film formation by making the surface temperature distribution of an object to be treated uniform, and prevents corrosion of power supply lines and terminals, etc., to the heating means, and reduces particle generation. The present invention relates to a gas processing apparatus capable of suppressing generation of gas.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, a CVD (Chemical Vap) is used to form an integrated circuit on a semiconductor wafer (hereinafter, referred to as "wafer") such as silicon.
or Deposition) or a film forming process such as sputtering. In such a film forming process, it is necessary to uniformly heat and maintain the entire surface of the wafer at a predetermined temperature in order to uniformly process the thin film on the wafer.

One of the methods for heating the wafer is a film forming apparatus using a ceramic heater. In this processing apparatus, a processing gas for film formation is supplied into a processing chamber maintained in a vacuum.
A ceramic body which also serves as a wafer mounting table and in which a resistance heating element is embedded is arranged.

[0004] Such a processing apparatus is disclosed in Japanese Patent Application Laid-Open No. H08-2181.
FIG. 7 is an enlarged view of a main part of a ceramic body disclosed in Japanese Patent Publication No. 72-72. Inside the ceramic body 1, resistance heating wires 2, 2 are buried, and the resistance heating wires 2, 2 are connected to a pair of terminals 3, 3, and the terminals 3, 3 are provided with an insulating tube. Feeding lines 4 and 4 covered by 5, 5 are connected. These power supply lines 4 extend through the bottom wall of the processing chamber and extend outside the processing chamber.

The power supply lines 4 and 4 are surrounded by a sheath bellows 6 made of stainless steel or the like, and an end piece 7 made of stainless steel or the like is provided at an upper end of the sheath bellows 6. Is formed by gold brazing, and this ring body 8 is also gold brazed to the ceramic body 1.
Further, a protection tube 9 made of quartz is provided radially outward of the sheath bellows 6. The protection tube 9 is for supplying an inert gas such as nitrogen gas into the protection tube 9 for purging. Are connected. Further, a thermocouple 11 for measuring the temperature of the ceramic body 1 is also accommodated in the sheath bellows 6 and extends to the outside.

As described above, the terminals 3 and 3 and the power supply lines 4 and 4 are surrounded by the sheath bellows 6 and the like, and the inert gas is purged into the protective tube 9.
In addition, the terminals 3 and 3 and the power supply lines 4 and 4 can be made to be in an inert gas atmosphere without exposing the power supply lines 4 and 4 to a highly corrosive gas such as a halogen gas. Can be prevented.

Further, when cleaning the processing chamber example ClF _3, NF ₃ gas, an inert gas in a quartz in the protection pipe 9 purged, in an inert gas atmosphere without exposing the sheath bellows 6 to the cleaning gas Because it is possible, sheath bellows 6
Corrosion can be prevented.

Further, a molybdenum ring 8 is interposed between the end piece 7 of the sheath bellows 6 and the ceramic body 1 and brazed by gold. The use of molybdenum having a coefficient of thermal expansion close to that of 1 prevents, for example, cracks or the like from occurring at the junction between the ring body 8 and the ceramic body 1 at a high temperature (600 ° C. to 700 ° C.) during the film forming process. It is.

[0009]

However, as described above, since the ring body 8 made of molybdenum is gold brazed to the end piece 7 of the sheath bellows 6 and the ceramic body 1, the gold brazing portion is interposed therebetween. As a result, the heat of the ceramic body 1 is transmitted to the sheath bellows 6 and escapes, and the surface temperature distribution of the ceramic body 1 becomes non-uniform. As a result, during the film forming process, the uniformity of the film formation may be hindered. .

Further, as described above, the quartz protection tube 9 is provided, and an inert gas such as nitrogen gas is purged into the protection tube 9 to protect the sheath bellows 6 and the molybdenum ring body 8 and the like. However, the molybdenum ring member 8 is subjected to a heat cycle during the film forming process and the cleaning process.
The gold brazed portion may be damaged, and at the time of cleaning, the gold brazed portion may be corroded by a cleaning gas such as ClF ₃ or NF ₃ gas. Therefore, through this damaged or corroded gold brazed part, ClF ₃ , N
The cleaning gas of the F ₃ gas leaks into the molybdenum ring body 8 and diffuses back, and the molybdenum ring body 8 is also corroded and peeled off, and the terminals 3 and 3 and the power supply lines 4 and 4 are removed.
May be corroded, and as a result, particles may be generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made to improve the uniformity of film formation by making the surface temperature distribution of an object to be uniform, and to provide a power supply line and a terminal to a heating means. It is an object of the present invention to provide a gas processing apparatus capable of preventing the generation of particles by preventing corrosion such as corrosion.

[0012]

According to a first aspect of the present invention, there is provided a processing chamber for performing processing on a processing target with a processing gas, and a processing chamber provided in the processing chamber for mounting the processing target. A mounting table made of an insulator, a resistance heating element buried in the mounting table, and for heating the object to be processed, and one end connected to the resistance heating element and the other end penetrating the wall of the processing chamber. A power supply line extending outside the processing chamber, a power supply line stored in an insulated state, a metal pipe interposed between the mounting table and a wall of the processing chamber, and a screw joining the metal pipe to the mounting table. A gas processing device comprising:

According to a second aspect of the present invention, in the first aspect, in the processing chamber, a film forming process is performed on the object to be processed by a CVD method using a film forming gas, and then cleaning is performed with a cleaning gas containing chlorine and fluorine. And a mounting table, wherein the mounting table is made of an insulating ceramic material.

According to a third aspect of the present invention, in any one of the first and second aspects of the present invention, the screwing means includes a screw formed so that a gap is formed between an end of the metal tube and the mounting table. Provided is a gas processing device, wherein a part of a tip of a shaft is screwed into a mounting table.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the metal tube has a hole through which a screw shaft of the screw means is inserted, and the diameter of the hole is larger than the diameter of the screw shaft. The present invention provides a gas processing apparatus characterized by the following.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the metal tube is surrounded, and a protective tube made of a corrosion-resistant nonmetallic material is interposed between the mounting table and the wall of the processing chamber. A gas processing device is provided.

According to a sixth aspect of the present invention, there is provided the gas processing apparatus according to any one of the first to fifth aspects, further comprising an inert gas supply means for supplying an inert gas into the metal tube. .

According to the first aspect, since the metal tube is joined to the mounting table using the screwing means, the mounting table is heated to a predetermined temperature by the resistance heating element as compared with the case where the metal tube is joined by gold brazing. This makes it difficult for the heat to escape to the metal tube, and the surface temperature distribution of the mounting table can be made uniform to improve the processing uniformity.

According to the second invention, when a cleaning gas containing chlorine and fluorine, such as ClF ₃ , which is extremely corrosive, is used in the CVD film forming apparatus, the metal tube is joined to the mounting table by screwing means. Therefore, the problem of corrosion as in the case of joining by gold brazing does not occur, and the use of an insulating ceramic material that is resistant to corrosion as the mounting table prevents generation of particles.

According to the third and fourth aspects of the present invention, since the thermal expansion of the metal tube can be tolerated by the screwing means, the joint portion between the metal tube and the mounting table can be made smaller than in the case of joining by gold brazing. During cleaning, the cleaning gas does not leak into the metal tube during cleaning, preventing corrosion of the power supply line and suppressing generation of particles.

According to the fifth aspect of the present invention, since the protection tube made of a corrosion-resistant nonmetallic material is provided between the mounting table and the wall of the processing chamber, the metal tube is removed from the highly corrosive cleaning gas during cleaning. Can be protected, and corrosion of the metal tube can be prevented.

According to the sixth aspect of the present invention, since the inert gas is purged from the inside of the metal tube, reverse diffusion of a highly corrosive gas into the metal tube can be prevented. By supplying the active gas, the surroundings of the metal tube can be made inert gas atmosphere to prevent corrosion.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a gas processing apparatus according to an embodiment of the present invention will be described with reference to the drawings. This embodiment exemplifies a CVD film forming apparatus. FIG.
1 is a schematic sectional view of a CVD film forming apparatus according to an embodiment of the present invention.

As shown in FIG. 1, a gate valve G for opening and closing a loading port and a loading port of a wafer W (object to be processed) is provided on a side wall of an airtight processing chamber 20 made of, for example, aluminum.
1 and G2, and above the processing chamber 20, for example, TiCl ₄ sent out from the gas supply pipes 21a and 21b, respectively.
A gas supply unit 21 for separately supplying gas and NH ₃ gas into the processing chamber 20 is provided.

In the processing chamber 20, a ceramic heater 2 serving as a wafer mounting table is opposed to the gas supply unit 21.
The ceramic heater 22 is made of a ceramic body made of an insulator such as aluminum nitride (AlN), silicon nitride (SiN), or aluminum oxide (Al ₂ O ₃ ). The ceramic heater 22 is supported by a bottom plate 24 of the processing chamber 20 via a support rod 23.

A pusher pin 25 used for transferring a wafer W between the ceramic heater 22 and a transfer arm (not shown) is provided on the bottom plate portion 24 of the processing chamber 20.
Is configured to be able to move up and down by an elevating mechanism 26. The pusher pins 25 are disposed so as to support three points of the wafer W, and are provided so as to pass through the inside of the ceramic heater 22. Further, around the ceramic heater 22, for example, an electrode 27 for generating plasma used for cleaning the inside of the processing chamber 20 is provided, and a high-frequency power supply E is provided between the electrode 27 and the wall of the processing chamber 20. To apply a high-frequency voltage.

Further, an exhaust port 29, which is an opening at one end of an exhaust pipe 28, is formed in the center of the bottom plate 24 of the processing chamber 20, and the exhaust pipe 28 is extended downward to be a turbo molecular pump. 30. An exhaust pipe 3 connected to a dry pump (not shown) is provided on the side of the turbo molecular pump 30.
1, a jack mechanism 32 is provided below the turbo molecular pump 30. That is, the bottom plate 24 of the processing chamber 20 is detachably and air-tightly joined to the lower end of the side wall, so that the bottom plate 24 can be moved up and down by the jack mechanism 32.

FIG. 2 is a schematic sectional view showing the ceramic heater and the wiring structure shown in FIG.
FIG. 3 is a schematic cross-sectional view in which main parts of FIG. 2 are enlarged. As shown in FIGS. 2 and 3, the ceramic heater 22 contains tungsten (W), molybdenum (Mo), tantalum (Ta), or nickel-chromium (Ni-Cr).
A resistance heating wire 33 (resistance heating element) made of, for example, is embedded, and the resistance heating wire 33 is connected to terminals 34, 34 made of a metal having a thermal expansion coefficient similar to that of a ceramic body, for example, molybdenum. These terminals 34, 34
Feeding lines 35, 35 covered with an insulating tube are connected, and the feeding lines 35, 35 extend to the outside through the bottom plate portion 24. A thermocouple 36 for measuring the temperature in the ceramic heater 22 is provided between the terminals 34, 34, and a wiring 37 for the thermocouple 36 is arranged between the power supply lines 35, 35. It has been extended outside.

The terminals 34, 34, thermocouple 36, power supply lines 35, 35, and wiring 37 are housed in a sheath bellows 38 (metal tube) made of stainless steel, Hastelloy (trademark), Inconel (trademark), or the like. . The sheath bellows 38 is preferably formed of Hastelloy from the viewpoint of corrosion resistance. The sheath bellows 38 has an end piece 39 made of corrosion-resistant Hastelloy at the upper end thereof. As shown in FIG. 3, the end piece 39 includes a tubular portion 39a embedded in direct contact with the ceramics heater 22, and a ring-shaped seat portion 39b extending radially outward from the tubular portion 39a. It consists of A seat 39b provided at an end of the end piece 39 includes:
A hole 41 through which a screw 40 (screw means) is inserted is formed, and only a tip end of a screw shaft 40 a of the screw 40 is screwed to the ceramic heater 22.
A gap is formed between the seat portion 39b and the ceramic heater 22. As described above, only the tip of the screw shaft 40a is screwed, and most of the screw shaft 40a is not fixed, and a gap is formed between the seat portion 39b and the ceramics heater 22, so that the heat cycle Thermal expansion of the end piece 39 is allowed.

FIG. 4 is a schematic cross-sectional view in which a ceramic heater and a wiring structure according to a modification are enlarged.
As shown in FIG. 4, the seat portion 39b of the end piece 39
The hole 41 is formed larger than the diameter of the screw shaft 40a, such as a long hole or an elliptical hole. Therefore, the screw 40 can be displaced so as to allow the thermal expansion of the end piece 39 even more.

Further, as shown in FIG. 2, the sheath bellows 38 has a ring piece 42 inserted at the lower end thereof through the bottom plate portion 24. The ring piece 42 is connected to an inert gas supply unit (not shown), and ejects an inert gas, for example, nitrogen gas from below, and supplies the inert gas into the upper sheath bellows 38 for purging. Further, an inert gas is spouted from the sheath bellows 38 to the outside at the upper end of the ring piece 42 so that a protective tube 4 described later is formed.
Jet holes 43, 43 for purging inert gas into
Are formed.

A protective tube 44 made of a corrosion-resistant non-metallic material, for example, quartz, is provided around the sheath bellows 38 so as to surround the sheath bellows 38 with a gap therebetween. The protection tube 44 may be formed of another material, for example, ceramics. The upper end of the protection tube 44 may be joined to the ceramics heater 22 by a screw or the like, and is lightly contacted with the ceramics heater 22 so that the inert gas in the protection tube 44 can flow into the processing chamber 20. There may be. Also, at the lower end of the protective tube 44,
A ring body 45 is provided, and a spring 46 is interposed below the ring body 45, and the spring 46 is held on its side by a ring body 47 on the outside thereof. The protection tube 44 is urged upward by the spring 46. Further, the ring body 45 is provided with a discharge hole 48 for allowing the inert gas in the protection tube 44 to flow into the processing chamber 20. Reference numeral 49 denotes a nut for sealing the sealing surface of the ring body 47.

Next, the operation of the present embodiment will be described. The wafer W is introduced into the processing chamber 20 by a transfer arm (not shown) through the gate valve G1, and is placed on the ceramic heater 22 as a mounting table. Electric power is supplied to the heating wire 33 to heat the ceramics heater 22 to heat the wafer W to a predetermined temperature. Further, a processing gas such as TiCl ₄ gas and NH ₃ gas is introduced into the processing chamber 20 through the supply unit 21 at a predetermined flow rate, and the processing gas is exhausted by the turbo molecular pump 30 through the exhaust pipe 28 so as to be processed. The inside is maintained at a predetermined degree of vacuum, and a TiN film is formed on the surface of the wafer W.

On the other hand, during such a film forming process, for example, nitrogen gas is supplied into the sheath bellows 38 from below in an upward direction from an inert gas supply means (not shown). As a result, as shown in FIG. 2, the inside of the sheath bellows 38 is purged with the inert gas, and the inert gas is jetted into the protective tube 44 via the jet holes 43, 43. Purge by inert gas. Further, the inert gas is ejected into the processing chamber 20 through the ejection holes 48.

A cleaning gas such as ClF ₃ or NF ₃ gas is periodically introduced into the processing chamber 20 from the gas supply unit 21, and a high-frequency voltage is applied between the plasma electrode 27 and the wall of the processing chamber 20. Is applied to turn the ClF ₃ and NF ₃ gases into plasma, and the reaction by-products adhering to the walls of the processing chamber 20, the ceramic heater 22 or the protective tube 44 are removed by etching. A nitrogen gas is supplied into the sheath bellows 38 from an inert gas supply unit that does not use the nitrogen gas. However, the inert gas may be, for example, an Ar gas, a He gas, or the like, and the ClF ₃ and NF ₃ gases do not necessarily need to be turned into plasma.

As described above, in the present embodiment, the sheath bellows 38 are strongly corrosive ClF ₃ and NF ₃ during cleaning by the protective tube 44 interposed between the ceramics heater 22 and the wall of the processing chamber 20. The sheath bellows 38 can be protected from a cleaning gas such as a gas, and the corrosion of the sheath portion loin 38 can be prevented. In addition, as described above, the inside of the sheath bellows 38 is purged with the inert gas, and at the same time, the inert gas is spouted into the protection tube 44 through the ejection holes 43, 43, so that the inside of the protection tube 44 is also inactive. Since the inert gas is purged by the active gas and the inert gas is jetted into the processing chamber 20 through the jet hole 48, it is possible to prevent the back diffusion of the highly corrosive gas into the sheath bellows 38, Further, the surroundings of the sheath bellows 38 can be made inert gas atmosphere to prevent corrosion, and generation of particles can be suppressed.

Only the tip of the screw shaft 40a of the screw 40 is screwed to the ceramic heater 22, and the screw shaft 40a
Are not fixed, and a gap is formed between the seat portion 39b and the ceramic heater 22, so that the thermal expansion of the end piece 39 due to the heat cycle is allowed.
Therefore, compared with the case of joining by gold brazing, the ceramic heater 22 heated to a predetermined temperature by the resistance heating wire 33 from the end piece 39 and the sheath bellows 38
The surface temperature distribution of the ceramic heater 22 can be made uniform, and the uniformity of film formation on the wafer W can be improved.

Further, since the screw 40 allows the thermal expansion of the end piece 39 due to the heat cycle, the joint portion between the end piece 39 and the ceramic heater 22 may be damaged as compared with the case of joining by gold brazing. In addition, at the time of cleaning, a cleaning gas such as a ClF ₃ gas or an NF ₃ gas does not leak into the end piece 39 and reversely diffuse. Therefore, corrosion of the terminals 34, the power supply lines 35, 35, and the like can be prevented, and generation of particles can be suppressed.

Further, when performing maintenance on the CVD film forming apparatus, as shown in FIG. 5, screws (not shown) of the bottom plate 24 and the side wall of the processing chamber 20 are removed, and the bottom plate 24 is moved by the jack mechanism 32. It is lowered together with the exhaust pipe 28 and the turbo molecular pump 30, and the internal components mounted on the bottom plate 24, for example, the ceramics 22, the drive mechanism 26 of the pusher pin, the plasma electrode 27 for cleaning, and the wiring structure of the ceramics heater are drawn out. So you can
Maintenance can be performed extremely easily as compared with a structure in which the processing chamber 20 is dismantled.

The present invention can be variously modified without being limited to the above embodiment. For example, the object to be processed is not limited to the wafer, and the gas processing apparatus is not limited to the thermal CVD film forming apparatus.
It may be a VD film forming apparatus, and is not limited to the film forming apparatus, but may be an etching apparatus.

[0041]

EXAMPLE The in-plane temperature distribution of a ceramic heater to which the present invention was applied was measured. As a comparative example, the in-plane temperature distribution of a ceramic heater was measured for the case shown in FIG. .

In the measurement of the in-plane temperature distribution, the heater set temperature was set to 600 ° C. and the pressure in the processing chamber was set to 150 mTorr in both the examples and the comparative examples. As a measurement result, FIG. 6A shows a comparative example, and FIG. 6B shows an example. Each numerical value in FIGS. 6A and 6B indicates a difference between the “average temperature of nine measuring points” and the “temperature of each measuring point”. As a result, in the comparative example, the in-plane temperature distribution was ± 1.5
While the spread was 2%, in the embodiment, ± 0.6% was obtained.
It could be reduced to 3%. The in-plane temperature distribution is expressed by adding ± to the calculated value of (in-plane maximum temperature-in-plane minimum temperature) × 100 / (in-plane average temperature × 2). As described above, according to the present invention, since the surface temperature distribution of the ceramic heater 22 can be made uniform, the uniformity of film formation on the wafer W can be improved.

[0043]

As described above, according to the first aspect,
Because the metal tube is joined to the mounting table using screwing means,
Compared to the case of joining by gold brazing, it is difficult for heat to escape from the mounting table heated to a predetermined temperature by the resistance heating element to the metal tube, and the surface temperature distribution of the mounting table is made uniform to improve the processing uniformity. be able to.

According to the second aspect of the present invention, when a cleaning gas containing chlorine and fluorine such as ClF ₃ which is extremely corrosive is used in a CVD film forming apparatus, a metal tube is joined to the mounting table by screwing means. Therefore, the problem of corrosion as in the case of joining by gold brazing does not occur, and the use of an insulating ceramic material that is resistant to corrosion as the mounting table prevents generation of particles.

According to the third and fourth aspects of the present invention, since the thermal expansion of the metal tube can be tolerated by the screwing means, the joining portion between the metal tube and the mounting table can be formed as compared with the case of joining by gold brazing. During cleaning, the cleaning gas does not leak into the metal tube during cleaning, preventing corrosion of the power supply line and suppressing generation of particles.

According to the fifth aspect of the present invention, since the protection tube made of a corrosion-resistant nonmetallic material is provided between the mounting table and the wall of the processing chamber, the metal tube is removed from the highly corrosive cleaning gas during cleaning. Can be protected, and corrosion of the metal tube can be prevented.

According to the sixth aspect of the present invention, since the inert gas is purged from the inside of the metal tube, the back diffusion of the highly corrosive gas into the metal tube can be prevented. By supplying the active gas, the surroundings of the metal tube can be made inert gas atmosphere to prevent corrosion.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a CVD film forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a ceramic heater and a wiring structure shown in FIG.

FIG. 3 is an enlarged schematic sectional view of a main part of FIG. 2;

FIG. 4 is an enlarged schematic cross-sectional view of a ceramic heater and a wiring structure according to another embodiment.

FIG. 5: CVD in a state where the bottom plate of the processing chamber is lowered
FIG. 2 is a schematic cross-sectional view of a film forming apparatus.

FIG. 6 is a diagram showing measurement results of in-plane temperature distribution of ceramic heaters according to a comparative example and an example.

FIG. 7 is a schematic sectional view showing a conventional ceramic heater and a wiring structure.

[Explanation of symbols]

 20 processing chamber 22 ceramic heater (mounting table) 33 resistance heating wire (resistance heating element) 34 terminal 35 power supply line 38 sheath bellows (metal tube) 39 end piece (metal) Tube) 39b Seat 40 Screw 40a Screw shaft 41 Hole 43 Spout hole 44 Protective tube 48 Spout hole

Claims (6)

[Claims] 1. A processing chamber for performing processing on an object to be processed by a processing gas, a mounting table provided in the processing chamber and made of an insulator for mounting the object to be processed, and embedded in the mounting table. A resistance heating element for heating the object to be processed, a power supply line having one end connected to the resistance heating element and the other end penetrating through the wall of the processing chamber and extending out of the processing chamber, and an insulated state of the power supply line. A gas processing apparatus, comprising: a metal pipe housed in the above, and interposed between a mounting table and a wall of a processing chamber; and screwing means for joining the metal pipe to the mounting table. 2. The process chamber includes a CV using a film forming gas.
2. The gas according to claim 1, wherein the object to be processed is subjected to a film forming process by a method D, and then cleaned by a cleaning gas containing chlorine and fluorine, and the mounting table is made of an insulating ceramic material. Processing equipment. 3. The screwing means screws a part of the tip of the screw shaft to the mounting table so that a gap is formed between the end of the metal tube and the mounting table. The gas processing apparatus according to claim 1 or 2, wherein 4. The metal tube according to claim 1, wherein the metal tube has a hole through which the screw shaft of the screw means is inserted, and the hole diameter is larger than the diameter of the screw shaft. A gas processing apparatus according to the item. 5. The metal tube according to claim 1, wherein a protective tube made of a non-metallic material having corrosion resistance is interposed between the mounting table and a wall of the processing chamber. 2. The gas processing apparatus according to claim 1. 6. The gas processing apparatus according to claim 1, further comprising an inert gas supply unit that supplies an inert gas into the metal tube.