JP2002194548A - Gas feeding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas feeding method which prevents a partial pressure drop of a raw gas supplied into a chamber and improves treatment efficiency. SOLUTION: A gas feeding device comprises, a treatment unit 11 for carrying out a predetermined treatment after introducing a raw gas including at least one of a gas containing fluorine and a gas containing oxygen, a first gas introduction part and a second gas introduction part, the first exhaust outlet 15 for introducing and exhausting a gas from the treatment unit through the first gas introduction part, the second exhaust outlet 16 for exhausting a gas from the first exhaust outlet outside, and the first piping section 18, 21, 24 for feeding a part of gas exhausted from the first exhaust outlet to the treatment unit. The feeding method comprises introducing at least one part of the raw gas introduced to the treatment unit, from the second gas introduction part of the first exhaust outlet, and feeding the raw gas exhausted from the first exhaust outlet to the treatment unit through the first piping section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas supply method in a gas circulation processing apparatus for circulating and reusing a processing gas.

[0002]

BACKGROUND OF THE INVENTION CF ₄ used in the cleaning of the chamber such as a CVD apparatus, C ₂ F _6, NF ₃ or the like gas,
Known as global warming gas, it is required to reduce the amount of use and emission. In order to reduce the amount of used gas and the amount of discharged gas, it is effective to circulate and reuse gas.

When the above-described gas circulation method is used, the activated processing gas (active species) generated in the chamber also flows into a gas circulation exhaust device (for example, a turbo molecular pump). Therefore, in order to prevent corrosion of the exhaust system by the active species, it is necessary to purge and dilute the exhaust system in a non-corrosive gases, in addition to N ₂ and the like of the processing gas for cleaning as described above It is necessary to supply a large amount of the inert gas. However, when circulating cleaning is performed at a high circulation rate, the partial pressure of the processing gas for cleaning decreases with time, and the cleaning speed decreases.

In Japanese Patent Application Laid-Open No. 10-122178, an inert gas is directly introduced as a purge gas into an exhaust device for gas circulation to prevent corrosion in the exhaust device. However, even with this method, a large amount of the inert gas introduced into the gas circulation exhaust device flows into the circulation path together with the processing gas, so that the processing gas supplied into the chamber is diluted and the partial pressure is reduced. It is difficult to avoid the problem that the cleaning speed is lowered.

[0005]

As described above, a method of introducing an inert gas as a purging gas into the exhaust system has been proposed in order to prevent corrosion in the exhaust system for gas circulation. However, there is a problem that the processing gas re-supplied into the chamber through the circulation path is diluted by the inert gas, which causes a reduction in cleaning efficiency and the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and can prevent corrosion in an exhaust device for gas circulation and suppress a decrease in a partial pressure of a processing gas supplied into a chamber. It is an object of the present invention to provide a gas supply method capable of improving the processing efficiency.

[0007]

According to the present invention, there is provided a gas supply method comprising: a processing section for performing a predetermined processing by introducing a processing gas containing at least one of a fluorine-containing gas and an oxygen-containing gas; And a second gas introduction unit, a first exhaust unit for introducing and exhausting the gas from the processing unit from the first gas introduction unit, and a gas from the first exhaust unit to the outside. A second exhaust unit that exhausts air, a back pressure adjusting unit that is provided between the first exhaust unit and the second exhaust unit, and adjusts a back pressure of the first exhaust unit; A first piping section that supplies a part of the gas discharged from the exhaust section to the processing section, and a gas supply method in the gas circulation processing apparatus, wherein at least the processing gas introduced into the processing section is provided. Part of the gas is introduced from the second gas introduction section of the first exhaust section, and a portion is introduced from the first exhaust section. The discharged process gas and supplying to the processing unit through said first pipe section.

In the above invention, the processing gas to be introduced into the processing section may be exclusively supplied from the first exhaust section via the first pipe section.

Further, in the above invention, a second piping section for introducing a processing gas into the processing section is further provided, and the processing gas introduced into the processing section is supplied to the first exhaust section and the second piping section. It may be supplied from a unit.

According to the present invention, the processing gas used for the processing in the processing section is supplied to the first exhaust section, so that the processing gas can be used as a purge (diluting) gas in the first exhaust section. Can be used. As described above, by making the processing gas also function as a purging gas, there is a problem when only an inert gas is used as a purging gas as in the related art, that is, the partial pressure of the processing gas is reduced by the inert gas. Can be prevented, and the efficiency of predetermined processing such as cleaning can be improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration example of a gas circulation system according to an embodiment of the present invention. Hereinafter, a cleaning process in a parallel plate type plasma CVD apparatus will be described as an example.

An upper electrode 12 serving as a shower head and a high-frequency electrode, and a lower electrode 13 having a heater and a wafer transfer mechanism are provided in a chamber 11, and discharge is generated between the upper electrode 12 and the lower electrode 13. By activating the generated processing gas, film deposition on a sample (such as a semiconductor wafer) mounted on the lower electrode 13 and cleaning of the chamber are performed.

Processing gases used for cleaning the inside of the chamber include, for example, CF ₄ , C ₂ F ₆ , C ₃ F ₈ , N
A gas such as F ₃ or O ₂ can be used. By activating such a processing gas, a silicon oxide film (SiO 2 film) or the like attached to the inside of the chamber 11 can be removed by etching. In general, a gas containing at least one of a fluorine-containing gas and an oxygen-containing gas can be used as the processing gas for cleaning.
Further, an inert gas such as N ₂ or Ar may be added to such a processing gas.

A pressure adjusting valve 1 is provided in the chamber 11.
4 is connected, and the pressure in the chamber 11 can be kept constant by adjusting the opening of the valve 14.

An exhaust device 15 for gas circulation is connected to the gas exhaust side of the chamber 11.
An exhaust device 16 for discharging gas to the outside is connected to 5. For example, a turbo molecular pump or a Roots type pump can be used as the exhaust device 15, and a dry pump can be used as the exhaust device 16, for example. A gas supply pipe 15a is connected to the exhaust device 15, and a processing gas or the like can be supplied into the exhaust device 15 from the gas supply pipe 15a.

Between the exhaust device 15 and the exhaust device 16,
A valve 17 for adjusting the back pressure of the exhaust device 15 is provided. The pipe 18 on the gas discharge side of the exhaust device 15 is branched at a branch point 19 into a pipe 20 to the exhaust device 16 and a pipe (gas circulation pipe) 21 for gas circulation, and a valve for adjusting the back pressure. The gas circulation rate can be adjusted by adjusting the opening 17. When performing the deposition process (film deposition process) in the chamber 11, the back pressure adjusting valve 17 is controlled to be fully opened.

The gas circulation pipe 21 is connected to a gas supply pipe 23 and a gas introduction pipe 24 at a junction 22. A valve 26 is provided near the junction 22 of the gas supply pipe 23.
Is provided, and a processing gas can be supplied from the gas supply pipe 23 as needed. That is, when the valve 26 is closed, only the processing gas from the gas circulation pipe 21 is introduced into the chamber 11 from the gas introduction pipe 24. In a state where the valve 26 is opened, the processing gas from the gas circulation pipe 21 and the processing gas supplied from the gas supply pipe 23 merge at a junction 22 to form a gas introduction pipe 24.
From the chamber 11. Gas circulation pipe 21
A valve 25 is provided in the middle of the process, and the back pressure of the gas circulation exhaust device 15 is set to be higher than the pressure of the gas junction 22 with the valve 25 opened during gas circulation.

When only the processing gas from the gas circulation pipe 21 is used, the gas supply pipe 23 may not be provided, and the gas circulation pipe 21 and the gas introduction pipe 24 may be connected continuously. .

The upstream side of the gas supply pipe 23 (before the valve 26 (referred to as valve a)) is branched, and the branched pipe is connected to the gas supply pipe 15a via a predetermined valve (referred to as valve b). In addition, a predetermined valve (referred to as a valve c) may be provided in the middle of the gas circulation pipe 21 and near the junction 22. If you do this,
In the case of performing gas circulation, all new processing gases can be supplied from the exhaust device 15 via the gas supply pipe 15a by closing the valve a and opening the valves b and c. When the gas circulation is not performed, the valve a is opened and the valves b and c are closed, whereby all the new processing gas can be supplied from the gas supply pipe 23 to the chamber 11. In the latter case, N ₂ gas or the like may be introduced from the gas supply pipe 15a to the exhaust device 15 as a purge gas.

According to such a configuration, it is possible to prevent the pressure in the new gas supply path and the pressure in the gas circulation path from interfering with each other, and to simplify the configuration of the gas introduction section to the chamber. Furthermore, when performing gas circulation, it is possible to prevent the exhaust device from deteriorating without reducing the partial pressure of the processing gas.

FIG. 2 is a diagram schematically showing an example of a turbo-molecular pump used as the exhaust device 15. The gas discharged from the chamber 11 is introduced into the turbo molecular pump from the main inlet 15b, and passes through the path g1 to the outlet 15b.
The gas is exhausted from c to the pipe 18. Further, the processing gas is supplied to the purge inlet 15d from the gas supply pipe 15a, and is exhausted from the outlet 15c to the pipe 18 through the path g2.

The aforementioned CF ₄ , C ₂ F ₆ , C ₃ F ₈ ,
The cleaning gas such as NF ₃ or O ₂ becomes corrosive by being activated by plasma or the like, but does not dissociate with ordinary heat energy, and therefore does not corrode the exhaust device 15. Can be Therefore, it is sufficiently possible to use these gases as gases for purging (diluting) the exhaust device 15. From such a viewpoint, in the present invention, the processing gas for cleaning is directly introduced into the exhaust device 15 from the introduction port 15d, and this is also used as the gas for purging.

FIG. 3 shows a case where an inert gas is supplied together with the processing gas from the normal gas supply pipe 23 (a), and the processing gas is supplied from the gas supply pipe 23 and the inert gas is supplied from the purge gas supply pipe 15a. This is a result of examining the etching film thickness in the chamber 11 when only the cleaning gas is supplied (b) and when all of the cleaning processing gas is supplied from the purge gas supply pipe 15a (c).

When the inert gas is supplied from the purge gas supply pipe 15a (b), the etching rate is improved as compared with the case (a), but the gas supply pipe 15
Since the partial pressure of the processing gas is reduced by a large amount of the inert gas supplied from a, it is difficult to increase the etching rate (cleaning rate). On the other hand, in the case (c) of the present invention, since the processing gas for cleaning is supplied as a purge gas from the gas supply pipe 15a, a decrease in the partial pressure of the processing gas due to the inert gas is prevented, and the etching is performed. The speed (cleaning speed) can be improved.

In terms of cleaning efficiency,
It is desirable to supply all of the processing gas from the purge gas supply pipe 15a into the exhaust device 15. However, if all of the processing gas is supplied from the gas supply pipe 15a, the apparatus is overloaded, which hinders the operation of the apparatus. May come. In such a case, the gas supply pipe 15a and the gas supply pipe 2
3 may be supplied, and also in this case, the cleaning efficiency can be improved as in the case where all the processing gases are supplied from the gas supply pipe 15a.

FIG. 4 is a diagram showing a modification of the gas circulation system shown in FIG. The basic configuration is the same as that of FIG. 1, and the components corresponding to the components shown in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

The example shown in FIG. 1 relates to a CVD apparatus for activating a processing gas in a chamber.
The present modification relates to a down-flow type CVD apparatus for activating a processing gas outside a chamber. That is, as shown in FIG. 4, a processing gas is introduced from the gas introduction pipe 24 into the activation unit 31 (for example, composed of a cavity or the like that generates microwaves), and the processing gas activated by the activation unit 31 is discharged. It is supplied into the chamber 11.

Also in this embodiment, similarly to the embodiment shown in FIG. 1, by supplying all or a part of the processing gas into the exhaust device 15 from the purge gas supply pipe 15a, the embodiment shown in FIG. It is possible to achieve the same effect as described above.

Although the embodiment described above relates to a cleaning process using a cleaning gas as a processing gas, the present invention can be similarly applied to an etching process using an etching gas as a processing gas. It is possible.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the gist thereof. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining the disclosed constituent elements. For example, even if some constituent elements are deleted from the disclosed constituent elements, they can be extracted as an invention as long as a predetermined effect can be obtained.

[0032]

According to the present invention, the partial pressure of the processing gas can be prevented from lowering by introducing the processing gas into the exhaust device for circulating the gas and using it as a purge gas. Prevention and improvement of processing efficiency can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a gas circulation system according to an embodiment of the present invention.

FIG. 2 is a diagram showing details of a part of the configuration shown in FIG. 1;

FIG. 3 is a diagram showing an effect of the gas circulation system according to the present invention.

FIG. 4 is a diagram showing a modified example of the gas circulation system according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Chamber 12 ... Upper electrode 13 ... Lower electrode 14 ... Valve for pressure adjustment 15 ... Exhaust device for gas circulation 15a ... Gas supply piping 15b ... Main inlet 15c ... Outlet 15d ... Inlet for purge 16 ... External discharge Exhaust device 17 ... Back pressure adjusting valve 18,20 ... Pipe 19 ... Branch point 21 ... Gas circulation pipe 22 ... Merging point 23 ... Gas supply pipe 24 ... Gas introduction pipe 25,26 ... Valve 31 ... Activation part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigehiko Kaji 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Yokohama office (72) Inventor Itako Sakai 8-six Shin-Sugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Takashi Yoda (72) Inventor Takashi Yoda 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa F-term (reference) 4G068 AA01 AA07 AB01 AC05 AC14 AD21 AD39 AD49 AF01 AF22 AF29 AF36 4G075 AA24 AA53 AA57 AA61 BA01 BC04 BC06 BD10 CA05 CA15 CA25 CA62 EA05 EB01 EB42 EC21 EE12 4K030 DA06 EA12 JA09 5F004 AA15 AA16 BA00 BB18 BB28 BC04 BD04 DA00 DA01 DA02 DA03 DA15 DA16 DA17 DA18 DA19 DA20 DA26 DA27 DA28 AF13 EBA EA03

Claims (6)

[Claims] A processing unit for introducing a processing gas containing at least one of a fluorine-containing gas and an oxygen-containing gas to perform a predetermined process; a first gas introduction unit and a second gas introduction unit; A first exhaust unit that introduces gas from the processing unit through the first gas introduction unit and exhausts the gas, a second exhaust unit that exhausts gas from the first exhaust unit to the outside, and the first exhaust unit. A back pressure adjusting unit provided between an exhaust unit and a second exhaust unit, the back pressure adjusting unit adjusting a back pressure of the first exhaust unit; and the processing of a part of gas exhausted from the first exhaust unit. And a first piping unit for supplying a gas to the processing unit. A gas supply method in a gas circulation processing device, comprising: a first piping unit configured to supply at least a part of a processing gas introduced to the processing unit to a second pipe of the first exhaust unit. A processing gas introduced from a gas introduction unit and discharged from the first exhaust unit is passed through the first piping unit. Gas supply method, characterized by supplying to the processing unit and. 2. The process gas introduced into the processing section is supplied to the first gas.
The gas supply method according to claim 1, wherein the gas is supplied exclusively from the exhaust section through the first pipe section. 3. A processing apparatus further comprising a second piping section for introducing a processing gas into the processing section, wherein the processing gas introduced into the processing section is supplied from the first exhaust section and the second piping section. The gas supply method according to claim 1, wherein: 4. The processing section has a chamber into which a processing gas is introduced from the first piping section, and an activating section provided in the chamber and activating the introduced processing gas. The gas supply method according to any one of claims 1 to 3, wherein 5. The processing unit includes a chamber and an activating unit provided outside the chamber and activating a processing gas introduced from the first piping unit and supplying the activated processing gas to the chamber. The gas supply method according to any one of claims 1 to 3, wherein 6. The back pressure adjusting section is a back pressure adjusting valve,
The gas supply method according to any one of claims 1 to 5, wherein when performing the film forming process in the processing unit, the back pressure adjustment valve is controlled to be in a fully opened state.