JP2001189277A - Piping cleaning method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piping cleaning method and its apparatus for cleaning a exhaust pipe and the like, by removing a reactive product generated at a gas treatment unit effectively without hazards. SOLUTION: In this piping cleaning method and apparatus, a exhaust gas containing the reactive product from a gas treatment unit 1 is discharged through a pipe 2, using a vacuum pump 4. A trap 3 is provided at the disc pipe 2 between the gas treatment unit 1 and the vacuum pump 4, and the reactive product in the gas is trapped as a deposited material. At the non-treatment time of the gas treatment unit 1, ClF3 gas is fed to the solid deposited material through the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a plasma CVD.
The present invention relates to a processing apparatus for processing a semiconductor wafer or the like using a gas such as (chemical vapor deposition), ion implantation, or gas etching. The present invention relates to a method and apparatus for cleaning a pipe to be prevented.

[0002]

2. Description of the Related Art For example, when a SiN film is formed on a semiconductor wafer by plasma CVD, SiH is used as a material gas.
_The combination of ₄ and NH ₃ is often used,
Unlike the case where a thin film is formed by thermal CVD, a reaction product such as (NH ₄ ) ₂ SiF ₆ containing silicon hydride is deposited on an exhaust pipe. Among them, silicon hydride is chemically active and may ignite when it comes into contact with air or water, and there have been accidents in the past. In addition, ammonium hexafluorosilicate generated in the step of cleaning the thin film deposited on the CVD apparatus also deposits on the exhaust pipe, but since it is nonflammable, there is no danger of ignition or the like. Hexafluorosilicic acid is white, while silicon hydride-based reaction products have a reddish brown color. Therefore, if the deposit color is white-yellow, it will not ignite, but if it becomes orange, it is dangerous. Have been done. Since the hydrogenated silicon-based reaction product is solid at room temperature, it begins to accumulate from the exhaust pipe on the upstream side of the vacuum pump, and when the amount of production is large, it accumulates in the pump and further on the exhaust pipe downstream from the pump. Sisters,
Leaving it will cause the problem of blockage of the tube.

When impurities are implanted into a semiconductor wafer by ion implantation, a gaseous substance such as solid phosphorus or arsenic vaporized, or PH ₃ , AsH ₃ , or BF ₃ is used as a source material. Even when a gas body is used, it is decomposed in the process of ionization and becomes a vapor of phosphorus, arsenic, and boron. Although the melting points or sublimation temperatures of these substances differ depending on the crystal system, they are almost solid at room temperature, and they precipitate at various points in the exhaust system including the inner wall of the ion implanter. All of these substances are highly reactive, especially phosphorus, which may ignite spontaneously in the atmosphere. In addition, arsenic is highly toxic, and there is concern about the safety of workers during maintenance work.

In the case of aluminum etching, a chlorine-based gas or the like is used, but the etching rate of the resist is high, and an organic chlorine-based compound is generated during the reaction. Of these, those having a relatively high molecular weight are deposited and deposited in the immediate vicinity of a chamber of an exhaust pipe connected to a vacuum chamber. Recently, etching has been performed under a higher vacuum, and a turbo molecular pump has been attached.In such a case, these substances are deposited in the turbo molecular pump,
There is also a risk that the pump will stop. In general, organochlorine compounds are highly toxic, and sufficient safety must be taken into account when removing the sediment.

[0005]

Conventionally, in these pipe cleaning methods, the deposits of reaction products in the exhaust gas deposited on the exhaust pipe are cleaned by removing the exhaust pipe when the process is stopped, or by removing the exhaust pipe. It is often removed by replacing pipes. However, in such a conventional method for cleaning deposits of reaction products in exhaust gas, the cleaning efficiency is poor, and some of the deposits of reaction products are toxic as described above, and thus are not provided to workers. It can be dangerous.

[0006] The present invention has been made in view of the above circumstances, and efficiently reacts a reaction product generated in a gas processing section.
It is another object of the present invention to provide a method and an apparatus for cleaning a pipe which can be cleaned from an exhaust pipe or the like without danger.

[0007]

According to a first aspect of the present invention, there is provided a method for cleaning a pipe, comprising the steps of: performing a reaction from the gas processing section by a vacuum pump through an exhaust pipe connected to the gas processing section; A method for cleaning a pipe for exhausting exhaust gas containing products, wherein a trap device is disposed on the exhaust pipe between the gas processing unit and the vacuum pump, and a reaction product in the exhaust gas is trapped as a deposit. The deposit is removed by supplying ClF ₃ gas to the deposit through the exhaust pipe when the gas processing unit is not treating.

[0008] Thus, the reaction products in the exhaust gas are trapped and accumulated in the trap device, and when the gas treatment section is not being treated, a strongly oxidizing ClF ₃ gas is supplied to the gas treatment section so that ignitability, toxicity, etc. Reacts with the deposit having the above, and the deposit is oxidized to a stable gaseous substance, and this gaseous substance is sucked by a vacuum pump and exhausted through an exhaust pipe. Therefore, the deposits of the exhaust gas can be efficiently cleaned without disassembling the exhaust pipe. Also,
Since the deposit can be easily cleaned when the gas processing section is not being processed, a high cleaning effect can be obtained, and the worker can be prevented from coming into contact with the dangerous deposit.

According to a second aspect of the present invention, in the method for cleaning a pipe according to the first aspect, the ClF ₃ gas is introduced into the gas processing section, and the ClF ₃ gas is supplied from the gas processing section to the trap device through the exhaust pipe. Is supplied. Thereby, the deposits deposited in the gas processing section can be cleaned at the same time.

[0010] According to a third aspect of the present invention, there is provided an apparatus for cleaning a pipe, comprising: a gas processing unit configured to perform processing using a gas; an exhaust pipe connected to the gas processing unit; and a vacuum pump. A trap device for trapping a reaction product in the exhaust gas, in the exhaust pipe between the gas treatment unit and the vacuum pump, for exhausting exhaust gas from the gas processing unit by a pipe, And a means for supplying a ClF ₃ gas for removing the deposited material. This makes it possible to add a cleaning device that safely and reliably removes deposits of reaction products without making significant changes to the existing piping system.

[0011] The method of cleaning pipes according to claim 4, the supply means of the ClF ₃ gas, the inlet is provided in the gas treatment unit, flowing through the ClF ₃ gas to the trap apparatus from the exhaust pipe It is characterized by the following.

[0012] According to a fifth aspect of the present invention, there is provided the pipe cleaning apparatus,
The ClF is connected to the exhaust pipe on the downstream side of the trap device._ThreeMoth
It is equipped with a cooling trap device that traps heat
And This makes it easy to react with the cooling trap
ClF_ThreeGas is condensed and trapped
It is. By reusing this, ClF _Three
Efficient use of gas can be achieved. Also, ClF
_ThreeOnly gas decomposed by gas is sent to the abatement system
Therefore, it is possible to reduce the burden of the abatement process of the abatement equipment.
You.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment when the present invention is applied to a plasma CVD apparatus. The plasma CVD apparatus includes a vacuum chamber (gas processing unit) 1 and an exhaust pipe 2 connected to the vacuum chamber 1. In the exhaust pipe 2, a cooling trap device (trap device) 3, a vacuum pump 4, a second cooling trap device 5, and an abatement device 6 are sequentially provided from the vacuum chamber 1 side.
Is installed. The vacuum chamber 1 contains SiH ₄ , N
H ₃ and ClF ₃ gas supply pipes 7, 8 and 9 are connected respectively.

In this plasma CVD apparatus, SiH ₄ and NH ₃ as source gases are supplied into the vacuum chamber 1 through supply pipes 7 and 8, and these gases are discharged in the vacuum chamber 1 under reduced pressure to form a plasma plasma state. And a precursor radical is generated. A certain amount of this precursor radical is adsorbed while repeatedly adsorbing and desorbing on the surface of the base film of the semiconductor wafer, and is deposited on the surface,
A thin film of SiN is formed. At this time, silicon hydride, which is a reaction product, is generated as a gas.

The silicon hydride is sucked as exhaust gas by the vacuum pump 4 and flows through the exhaust pipe 2. At this time, the silicon hydride is cooled by the cooling trap device 3,
The solid is intensively deposited in the cooling trap device 3 as a solid.
Then, when the thin film forming process is not performed, the ClF ₃ gas is supplied into the vacuum chamber 1 through the supply pipe 9,
Further, it is sucked by the vacuum pump 4 and reaches the inside of the cooling trap device 3 through the exhaust pipe 2. And this ClF ₃
The gas is a strongly oxidizing gas, and silicon hydride deposited in the cooling trap device 3 is oxidized to a stable gaseous substance such as SiF ₄ . ClF ₃ gas in the gas and unreacted ₄ etc. These SiF is sent to the second cooling trap device 5 through the exhaust pipe 2, wherein unreacted ClF ₃
Only gas is condensed and trapped. The trapped ClF ₃ is separated from the exhaust pipe 2, circulated as ClF ₃ gas supplied to the vacuum chamber 1, and reused. Only a stable gas such as SiF ₄ is sent to the harm removal device 6, where the harm removal process is performed, and then the plasma CVD is performed.
It is exhausted outside the device.

Further, ammonium hexafluorosilicate generated in the step of cleaning the thin film deposited on the plasma CVD apparatus also deposits on the exhaust pipe 2. This ammonium hexafluorosilicate also reacts with ClF ₃ gas to form SiF ₄ because the or N ₂ gas body, also this deposit can be cleaned simultaneously.

In the above embodiment, the ClF ₃ gas is supplied to the vacuum chamber 1 and supplied to the cooling trap device 3 through the exhaust pipe 2, but the ClF ₃ gas is supplied from the upstream of the cooling trap device 3. For example, the supply pipe 9 </ b> A in FIG. 1 may supply the gas to the exhaust pipe 2 on the upstream side of the cooling trap device 3 and on the downstream side of the vacuum chamber 1.

While the ClF ₃ gas is being supplied,
It is preferable to stop the cooling of the cooling trap device 3 or to increase the temperature or pressurize it in some cases to promote the reaction.

FIG. 2 is a configuration diagram showing an embodiment in which the present invention is applied to an ion implantation apparatus. The ion implantation apparatus includes a vacuum chamber (gas processing unit) 11 and an exhaust pipe 12 connected to the vacuum chamber 11. In the exhaust pipe 12, in order from the vacuum chamber 11 side,
A turbo molecular pump 13, a cooling trap device (trap device) 14, a vacuum pump 15, and an abatement device 16 are provided. The vacuum chamber 11 contains PH ₃ , AsH ₃ or B
A supply pipe 17 for a gas such as F ₃ and a supply pipe 18 for a ClF ₃ gas are connected to each other.

In this ion implantation apparatus, the source
PH as quality_Three, AsH_ThreeOr BF _ThreeSupply and distribution of gas
The gas is supplied into the vacuum chamber 11 through a pipe 17 and
Is ionized in the vacuum chamber 1 and this ion
Is accelerated by the electric field and is driven into the surface of the semiconductor wafer.
And surplus phosphorus generated by decomposition in the process of ionization,
Arsenic or boron vapor is supplied to the turbo molecular pump 13 and
The air is sucked by the empty pump 15 and flows through the exhaust pipe 12.
At this time, the vapor such as phosphorus is cooled by the cooling trap device 14.
And is concentrated in the cooling trap device 14 as a solid.
accumulate.

When the ion implantation process is not being performed, ClF ₃ gas is supplied into the vacuum chamber 11 through the supply pipe 18, further sucked by the turbo molecular pump 13 and the vacuum pump 15, and cooled through the exhaust pipe 12. It reaches the inside of the trap device 14. Then, the phosphorus and the like deposited in the cooling trap device 14 are fluorinated by the strong oxidizing ClF ₃ gas to become a gas and are stabilized at the same time. This stabilized gas such as phosphorus and unreacted Cl
The F ₃ gas is sent to the abatement apparatus 16 through the exhaust pipe 12, where the abatement processing is performed, and then the F ₃ gas is exhausted outside the ion implantation apparatus.

FIG. 3 is a block diagram showing an embodiment in which the present invention is applied to an aluminum etching apparatus. This aluminum etching apparatus has a vacuum chamber (gas processing unit) 2
1 and an exhaust pipe 22 connected to the vacuum chamber 21.
It has. In the exhaust pipe 22, a turbo molecular pump 23, a cooling trap device (trap device) 24, a vacuum pump 25, and an abatement device 26 are sequentially provided from the vacuum chamber 21 side.
Is installed. The vacuum chamber 21 is connected to supply pipes 27 and 28 for BCl ₃ and Cl ₂ as source gases for etching and a supply pipe 29 for ClF ₃ gas for cleaning.

In this aluminum etching apparatus, BCl ₃ and Cl ₂ are supplied as an etching gas to the supply pipe 2.
The gas is supplied into the vacuum chamber 21 through the vacuum chambers 7 and 28, and these gases are converted into plasma by the high-frequency electric field in the vacuum chamber 1, which causes a surface chemical reaction to etch the resist and aluminum. The organochlorine compound, which is a reaction product generated in the etching process, is sucked by the turbo molecular pump 23 and the vacuum pump 25 and flows through the exhaust pipe 22. At this time, the organic chlorine compound is cooled by the cooling trap device 24 and accumulates in the cooling trap device 24. The turbo molecular pump 23
In order to minimize the accumulation of organic chlorine compounds on
It is preferable that the turbo molecular pump 23 is heated.

When the aluminum etching process is not performed, the ClF ₃ gas is supplied into the vacuum chamber 21 through the supply pipe 29 and the turbo molecular pump 23
Then, the air is sucked by the vacuum pump 25 and reaches the cooling trap device 24 through the exhaust pipe 22. Then, the organic chlorine-based compound deposited in the cooling trap device 24 is fluorinated by the strong oxidizing ClF ₃ gas, and C _n F
It becomes a fluorocarbon compound such as _{2n + 2} and vaporizes. The ClF ₃ gas that has not reacted with the gas of the fluorocarbon compound is sent to the harm removal device 26 through the exhaust pipe 22, where the harm removal treatment is performed, and then the gas is exhausted outside the aluminum etching device.

In the embodiment of FIGS. 2 and 3, similarly to the embodiment of the plasma CVD apparatus, the ClF ₃ gas may be supplied from the upstream of the cooling traps 14 and 24. For example, the turbo molecular pump 12, the supply pipes 18A and 29A shown in FIGS.
The gas may be supplied to the exhaust pipes 12 and 22 on the upstream side of the pipe 22.

In the embodiment shown in FIGS. 2 and 3, similarly to the embodiment of the above-mentioned plasma CVD apparatus, the detoxification is performed on the downstream side of the cooling trap units 14, 24, for example, with the vacuum pumps 15, 25. A second cooling trap device may be provided in the exhaust pipes 12 and 22 between the devices 16 and 26 to condense and trap unreacted ClF ₃ gas and reuse it. As a result, the ClF ₃ gas can be reused, and the burden on the abatement apparatus can be reduced.

[0027]

As described above, according to the present invention,
The reaction products in the exhaust gas are trapped in the trap device and deposited intensively, and when the gas processing section is not being processed, a strong oxidizing ClF ₃ gas is supplied to the trapped product so that the deposits are stable gaseous substances. And can be exhausted. As a result, the reaction products of the exhaust gas can be cleaned efficiently and without danger.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment when the present invention is applied to a plasma CVD apparatus.

FIG. 2 is a configuration diagram showing an embodiment when the present invention is applied to an ion implantation apparatus.

FIG. 3 is a configuration diagram showing an embodiment when the present invention is applied to an aluminum etching apparatus.

[Description of Signs] 1,11,21 Vacuum chamber (gas processing unit) 2,12,22 Exhaust pipe 3,14,24 Cooling trap device (trap device) 4,15,25 Vacuum pump 5 Second cooling trap device 6,16,26 Abatement system 13,23 Turbo molecular pump

Claims (5)

[Claims] 1. A method of cleaning a pipe for exhausting exhaust gas containing a reaction product from the gas processing section by a vacuum pump through an exhaust pipe connected to the gas processing section, wherein the gas processing section and the vacuum pump A trap device is arranged in the exhaust pipe between the above and the reaction product in the exhaust gas is trapped as a deposit, and ClF ₃ gas is supplied to the deposit through the exhaust pipe when the gas processing unit is not processing. Removing the deposit by performing the cleaning. 2. The piping according to claim 1, wherein the ClF ₃ gas is introduced into the gas processing unit, and the ClF ₃ gas is supplied from the gas processing unit to the trap device through the exhaust pipe. Cleaning method. 3. An exhaust system comprising a gas processing section for processing using a gas, an exhaust pipe connected to the gas processing section, and a vacuum pump, wherein exhaust gas from the gas processing section is removed by the exhaust pipe. A trap device for trapping a reaction product in the exhaust gas in the exhaust pipe between the gas processing unit and the vacuum pump to be evacuated, and a ClF ₃ gas for removing deposits trapped in the trap device. A pipe cleaning device comprising a supply unit. 4. A feed means of the ClF ₃ gas, wherein said gas treatment unit that the inlet is provided, wherein the is from the exhaust pipe which circulates the ClF ₃ gas to the trap apparatus Item 4. A pipe cleaning device according to item 3. 5. The pipe cleaning device according to claim 3, further comprising a cooling trap device for trapping the ClF ₃ gas in the exhaust pipe downstream of the trap device.