JP3776576B2 - Semiconductor manufacturing exhaust gas abatement apparatus and abatement method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for removing exhaust gas generated in the manufacture of semiconductors, liquid crystals and the like.
[0002]
[Prior art]
Methods for removing exhaust gas generated in semiconductor manufacturing include dry (adsorption), combustion (flame decomposition using fuel), thermal oxidative decomposition (electric heating method), and wet (absorption dissolution or decomposition using water or chemicals). However, it has advantages and disadvantages, but the superiority of the thermal oxidative decomposition method is evaluated from the viewpoint of safety, abatement, compactness, controllability, and cost of the device.
[0003]
However, in the heat oxidative decomposition method, for example, SiO ₂ for SiH _{4 and} P ₂ O ₅ for PH ₃ , dust as exhaust gas oxide is by-produced inside the decomposition cylinder after treatment. The gas flow resistance increases as it accumulates in various parts of the gas passage.
[0004]
Therefore, normally, the operating time of the abatement device is determined, and after the specified time has elapsed, the heater energization of the abatement device is stopped once, and the temperature inside the decomposition cylinder is lowered (for example, after 100 ° C. or less), a water shower is provided from the top The dust accumulated in various places including the heater surface was washed off, or the disassembly cylinder was disassembled and the inside was manually cleaned. In any case, since the abatement machine stops during that time, the semiconductor production by CVD connected thereto is stopped, and the reduction in productivity is obvious.
[0005]
[Problems to be solved by the invention]
The present invention solves such problems and makes it possible to safely and continuously perform exhaust gas elimination without affecting the CVD operation in the semiconductor manufacturing process, and increase the productivity of the semiconductor by the continuous operation. Means are sought.
[0006]
[Means for Solving the Problems]
The semiconductor exhaust gas abatement apparatus of the present invention has water scrubbers at the exhaust gas introduction part and the treated discharge part, respectively, and two or three electric heats between the introduction part water scrubber and the discharge part water scrubber. A decomposition cylinder of the type oxidation heating is provided, and the decomposition cylinder operating for exhaust gas treatment can be switched.
[0007]
The semiconductor exhaust gas abatement method of the present invention uses the semiconductor exhaust gas abatement apparatus according to claim 1, and by-product dust accumulates in the operating decomposition cylinder, and the gas passage resistance is a predetermined value or more. Or after operating the decomposition cylinder for a predetermined time, switch the active decomposition cylinder to the standby decomposition cylinder. It is characterized in that exhaust gas can be removed continuously by making it stand by.
[0008]
The abatement apparatus of the present invention is provided with water scrubbers on the inlet side and the outlet side along the flow of the processing gas, respectively, as in the abatement apparatus described in JP-A-7-323211, and electrothermal oxidation pyrolysis at the center. It has a cylinder. Further, in the present invention, two to three decomposition cylinders are provided, exhaust gas treatment and by-product dust removal are simultaneously performed in separate decomposition cylinders, and they are sequentially switched every predetermined time.
[0009]
That is, for the decomposition cylinder that removes by-product dust, cut off the introduction of exhaust gas, stop energization, cool to room temperature, and then use either pressurized air, N ₂ gas spray, or water spray Remove dust, and if necessary, clean the entire disassembly cylinder by dismantling. After the interior is sufficiently dried, it is put on standby as the next decomposing cylinder for detoxification. By stopping the CVD operation, exhaust gas can be removed by such a method of using the remover.
[0010]
In the process of repeating deposition and cleaning by CVD, if there is a risk of explosion by mixing both gases, such as SiH ₄ and NF ₃ , for example, a triple decomposition system is used. Is effective.
[0011]
In this case, if each decomposition cylinder is A, B, and C, the decomposition cylinder C can be used as a deposit cleaning standby cylinder if the decomposition cylinder A is treated for depositing and the decomposition cylinder B is treated for cleaning. . In accordance with the operation of the CVD, exhaust gas is appropriately introduced into the decomposition cylinder A and the decomposition cylinder B by switching the valves, and the detoxification is performed separately.
[0012]
Since dust generation occurs only in the decomposition cylinder A that processes the exhaust gas for deposit, the decomposition cylinder C becomes a standby cylinder for the decomposition cylinder A. B usually does not need to be cleaned. In this way, by using the decomposition cylinder A and the decomposition cylinder C alternately to perform detoxification and cleaning of the exhaust gas for deposit, the exhaust gas can be detoxified without stopping the CVD operation.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to preferred embodiments.
[Example]
FIG. 1 is a conceptual diagram of the abatement apparatus of the present invention. The heating oxidation decomposition cylinders A (A) and B (B) having the same dimensions and the same functions are accommodated in the cabinet (1). The exhaust gas enters from the left side of the figure, and the treated gas is released from the right side. The throughput of the decomposition cylinders A and B was 1000 liters / min. (2) is a water spray section for water cleaning of each disassembly cylinder.
[0014]
FIG. 2 is a diagram for explaining the operation timing of the abatement apparatus. The decomposition cylinders A and B are alternately in a resting state, and the cleaning water is injected when the decomposition cylinders A and B are in a resting state. In the figure, W indicates a detoxification operation, and M indicates maintenance, that is, a cleaning operation. The heater temperature is set to 700 ° C. during detoxification work and 100 ° C. during maintenance. At the time of switching, since the switching is performed after raising the heater temperature of the stand-by disassembly cylinder to 700 ° C., the detoxification work can be switched smoothly.
[0015]
[Example 1]
When using LP-CVD (low pressure CVD), SiH ₄ is 1.2 liters / min (gas concentration is 100%, unless otherwise noted), NH ₃ is 1 liter / min, PH ₃ (N ₂ balance is 0.5%) A mixed gas of 1.2 liter / min, H ₂ of 1 liter / min, and N ₂ of 308 liter / min was supplied, and the exhaust gas from the mixed gas was discharged to a detoxifier.
[0016]
This exhaust gas was passed through a spray section with a water amount of 10 liters / min of supply water, and introduced into an oxidation pyrolysis cylinder equipped with a heater having an electric capacity of 13.5 kW. Here, external air was supplied at a rate of 52 liters / min by a pump in a separate system from the exhaust gas introduction pipe, and was mixed in the decomposition cylinder for oxidative detoxification. The decomposed gas was discharged to the outside after shower-washing with 10 liter / min feed water at the outlet under the same conditions as the inlet. The surface temperature of the electric heater was set to 700 ° C.
[0017]
In the cabinet, a separate disassembly cylinder having the same shape and capacity as this disassembly cylinder is installed.
[0018]
Under such circumstances, when the continuous use was continued for one week, the initial pressure of 0.5 kPa reached 1 kPa in the static pressure gauge displaying the state of the ventilation resistance inside the disassembly cylinder used for the detoxification. .
[0019]
The inside of the exhaust gas introduction path was cleaned and switched to a stand-by decomposition cylinder in which the heater temperature was kept at 700 ° C., and the abatement apparatus was operated without any change in the CVD operation.
[0020]
The disassembly cylinder that had been used for detoxification was de-energized and cooled to room temperature, and then water was sprayed from the water spray nozzle installed at the top of the disassembly cylinder to wash away the dust accumulated inside. . After confirming that there was no accumulation of white dust as seen from the viewing window, it was dried through pressurized air, and it was confirmed that it was 0.5 kPa as a result of static pressure measurement under standard gas flow rate.
[0021]
The disassembled cylinder cleaned in this way is prepared for the next switching as a standby cylinder. One week later, the disassembly cylinder was switched by the same operation as described above. During these operations, CVD did not stop and productivity was not reduced at all. In addition, SiH ₄ in the atmospheric emission gas was 1 ppm or less, and PH ₃ was not detected at all.
[0022]
[Example 2]
In the present embodiment, an apparatus in which three disassembly cylinders A, B, and C are installed in the abatement apparatus having the same configuration as that of the first embodiment is used.
[0023]
In P-CVD (plasma CVD), TEOS (tetraethoxysilane) is 1 liter / min, NH ₃ is 4 liter / min, H ₂ is 5 liter / min, and N ₂ is 95 liter / min. Further, in the cleaning process, a mixed gas having NF ₃ of 4 liter / min, Ar of 0.5 liter / min, and N ₂ of 80 liter / min was used.
[0024]
Deposited exhaust gas was introduced into the decomposition cylinder A, and cleaning exhaust gas was introduced into the decomposition cylinder B. The heater surface temperature of the decomposition cylinders A and B was set to 800 ° C. Switching of the gas introduction path to the decomposition cylinders A and B was performed by automatic control of a valve at the CVD outlet.
[0025]
Although SiO ₂ dust stagnated in the decomposition cylinder A, no trace of dust was observed in the decomposition cylinder B. Most of NH ₃ was dissolved and removed in water in the water scrubber on the inlet side.
[0026]
As in the case of Example 1, after one week of continuous operation, the disassembly cylinder A was switched to the stand-by disassembly cylinder C, and the disassembly cylinder B was used as it was. In the process of switching, the operation could be continued without affecting the productivity of CVD. Note that TEOS in the released gas was 1 ppm or less, and NF ₃ was 0.5 ppm or less.
[0027]
【The invention's effect】
As described above, according to the present invention, exhaust gas removal can be continuously performed without affecting the CVD operation in the semiconductor manufacturing process, and the productivity of the semiconductor by the continuous operation can be improved.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an abatement apparatus of the present invention.
FIG. 2 is a diagram for explaining the operation timing of the abatement apparatus.
[Explanation of symbols]
(1) Cabinet
(2) Water spray section
(A) Heat oxidation cracking cylinder
(B) Heat oxidation decomposition cylinder

Claims (2)

Each of the exhaust gas introduction part and the treated discharge part has a water scrubber, and two or three electrothermal oxidation heating decomposition cylinders are provided between the introduction part water scrubber and the discharge part water scrubber. A semiconductor manufacturing exhaust gas abatement apparatus characterized in that a disassembly cylinder operating for exhaust gas treatment can be switched. Using the semiconductor manufacturing exhaust gas abatement apparatus according to claim 1,
When the by-product dust accumulates in the operating decomposition cylinder and the gas passage resistance exceeds a predetermined value, or after the decomposition cylinder has been operated for a predetermined time, the operating decomposition cylinder is changed to a standby decomposition cylinder. The disassembly cylinder that has been switched off and stopped is used to remove the by-product dust and wait for the next disassembly cylinder switchover so that the exhaust gas can be removed continuously. Detoxification method.

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