JPH01281131A - Method and apparatus for treating exhaust gas generated from semiconductor production process - Google Patents

Abstract

PURPOSE:To prevent large fluctuation of flow rate by arranging a bypass piping between an inlet and outlet pipings of an absorbentpacked vessel so that an exhaust gas during an evacuation of a reaction chamber is allowed to bypass the absorbent-packed vessel and not to flow into it. CONSTITUTION:A process gas 1 is introduced into a highly evacuated reaction chamber 14 for semiconductor production, reacts with wafers, and an exhaust gas is pumped out by an exhaust equipment 5, sent to a dry absorbent-packed vessel 10 and treated to become harmless. An exhaust gas while evacuating the reaction chamber 14 after it has been returned to atmospheric pressure for the purpose of maintenance, etc., is ejected through a bypass piping 8 by opening a bypass valve 7. An exhaust gas remaining in the bypass piping 8 is replaced by purging it with an inert gas introduced through a piping 8 and sending it to the absorbent-packed vessel 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for treating exhaust gas from semiconductor manufacturing, and particularly to a treatment method suitable for treatment with a dry absorbent and its production.

[Conventional technology]

As dry processes such as plasma CVD and plasma etching are increasingly adopted in semiconductor manufacturing processes, the need for exhaust gas treatment is increasing. Particularly in recent years, there have been strong expectations for exhaust gas treatment by the dry method due to its simplicity and other reasons, and nine absorbents have been put into practical use for various gases.

By the way, if we examine the amount of gas emitted in the above process in detail, we find that the amount of gas emitted during wafer processing is approximately equal to the total flow rate of the gases used, which is approximately several times per minute. When evacuation is performed from atmospheric pressure, several thousand tons of gas are exhausted per minute, which corresponds to the rated displacement of the exhaust pump, albeit for a short period of time.

When exhaust gas from semiconductor manufacturing equipment is treated directly with a dry absorbent, it is necessary to use an absorbent that can be treated stably and safely even with such extremely large fluctuations in flow rate. That is, it is necessary to use an absorbent that exhibits almost no ventilation resistance even when a large flow of exhaust gas is passed through a packed layer of absorbent, and that can completely absorb the components of the gas to be treated within the filled layer.

However, in general, coarse absorbents have to be used in order to keep airflow resistance low, but as the particle size increases, the surface area involved in absorption or adsorption is relatively small, resulting in a decrease in absorption St. . For this reason, attempts have been made to improve the absorption Gt using porous absorbents, but these methods also have their limits, and in the end, it is necessary to fill the absorbent with a considerable amount to achieve the desired absorption Gt. The reality is that we have secured capacity. Additionally, some exhaust gases react with the absorbent to form solids, and in such cases, even if the absorbent is coarsened, the reaction products will gradually block the packed layer. Therefore, it is impossible to avoid an increase in ventilation resistance.

[Problem that the invention seeks to solve]

The present invention provides a method and a method that can avoid large fluctuations in the flow rate of exhaust gas when treating exhaust gas from semiconductor manufacturing equipment with a dry absorbent, and can safely and efficiently process the exhaust gas even when using an absorbent with a smaller particle size. The present invention provides such equipment.

[Means for solving problems]

The present invention provides a method for treating exhaust gas from semiconductor manufacturing equipment with a dry absorbent, in which a bypass pipe equipped with a bypass valve is provided between an inlet side pipe and an outlet side pipe of an absorbent-filled container, and the reaction chamber of the semiconductor manufacturing equipment is By opening the bypass valve, a large amount of exhaust gas generated when exhausting gas from atmospheric pressure is prevented from being introduced into the absorbent-filled container, and the gas to be treated that remains in the exhaust system before the bypass pipe is inertized in advance. It is characterized in that it is replaced with gas.

[Example 1] An example of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows the flow from the semiconductor manufacturing equipment to the exhaust gas absorbent filling container.

The semiconductor manufacturing equipment 2 may be of any type as long as it processes wafers under high vacuum such as plasma CVD or plasma etching, and therefore the type and flow rate of the process gas 1 may vary depending on the respective gross process. Good too.

Further, the type and amount of absorbent to be filled in the absorbent filling container 10, and the dimensions and shape of the filling container can be selected from known ones depending on each exhaust gas.

Generally, during wafer processing, process gas 1 is introduced into the reaction chamber 14 of semiconductor manufacturing equipment and reacts with the wafer, and the exhaust gas after the reaction is exhausted by the exhaust device 5 and sent to an absorbent-filled container to be rendered harmless. It is then discharged.

In addition, when the reaction chamber i4 of the semiconductor manufacturing equipment is returned to atmospheric pressure for wafer exchange or maintenance and then evacuated again by the exhaust device 5, a large amount of exhaust gas is absorbed by the bypass piping 8 by opening the bypass valve 7. The agent is discharged without passing through the agent filling container 10. At this time, since a large amount of exhaust gas is discharged only after the main pulp 5 is opened, the bypass valve 7 may be opened in advance based on a signal for opening the main pulp 5. However, since the main pulp 3 remains open up to t during etching, the bypass valve 7 also remains open. Therefore, a timer is set to close after a predetermined time, but the timer setting time at that time is such that the exhaust flow rate decreases and the absorbent filling container 10 closes.
The time may be any time sufficient for the zero inlet pressure to decrease and before the process gas is introduced into the reaction chamber.

(9) If a large amount of exhaust gas is directly introduced into the absorbent-filled container, the pressure on the inlet side of the container will increase, so this pressure increase may be detected by the pressure detector 9, and the bypass valve 7 may be opened in response to the signal. However, in this case, the inlet pressure will drop at the same time as the bypass valve 7 opens, the pressure detector 9 will sense this and close the bypass valve, and the pressure will rise again and the bypass valve will open. A hunting phenomenon may occur. Therefore, it is better to use Shitai-i and set the timer time to exhaust air until the exhaust flow rate decreases and the inlet pressure is low enough that the bypass valve will not open again even if the bypass valve is closed, and then close the bypass valve. Just do it.

In addition, since exhaust gas remains in the exhaust pipe 4 from the exhaust device 5 to the absorbent filling container immediately after wafer processing is completed, if a large amount of exhaust gas is discharged via the bypass valve, A situation arises in which a portion of the exhaust gas that should be treated is released untreated. Therefore, until the reaction chamber 14 is evacuated, the exhaust gas existing in the piping is purged with an inert gas introduced through the piping 6 and sent to the absorbent filling container 10, and then the bypass valve is opened to generate a large amount of gas. It is preferable to release the exhaust gas.

At this time, the inert gas for purging may be injected from within the exhaust device 5 or from an appropriate location immediately after it, and the period of careful injection may be either constant injection or only for a certain period of time immediately before exhausting the reaction chamber. But that's fine. Further, the amount of injection gas fi can be determined by taking into account the volume of the pipe to be purged, the injection time, etc. Note that the exhaust gas is exhausted through the exhaust pipe 12.

[Embodiment 2] Nine examples in which the present invention is applied to an etching apparatus iK will be described with reference to FIG.

Before the start of operation, the main pulp 3 is closed, the exhaust device 5 is constantly operated, and N and gas are constantly introduced through the pipe 6. Then, the bypass valve 7 is closed, the pressure detection device 9 is in the opy state, and the Ct, valve 15-
1 and N valves 15-2 are closed, and the reaction chamber 14 is at atmospheric pressure.

The operating method of this device is explained along with its functions: (1)
First, a wafer is placed in the reaction chamber 14, the lid is closed to seal it, and when the main pulp 5 is opened, the atmosphere of the reaction chamber 14 (20
t) is exhausted by the exhaust device 5. At this time, since the evacuation speed is high (for example, 1200 t/min), a large amount of air is introduced into the absorbent filling container 10 at the initial stage of evacuation.

The pressure loss of the absorbent-filled container is determined by the design flow rate of 0 to 50t/
Initial exhaust to the exhaust piping, which is designed in minutes I 12
When exhaust gas flows in at 0027 minutes, the pressure increases.

(2) Therefore, by opening the bypass valve 7 in advance in response to the open signal from the main pulp 5, or by opening the bypass valve 7 by detecting the pressure increase with a pressure detector, the initial large volume of exhaust gas is mainly bypassed. It is exhausted through the entire pipe 6.

At this time, the bypassed gas is a harmless gas, as will be clear from the explanation below.

Since the atmosphere in the reaction chamber 14 becomes dilute in a few seconds (1 to 10 seconds), no pressure rise occurs even if the bypass valve 7 is closed thereafter.

(3) Then, open the Ct valve 15-1 to introduce, for example, a Ct of α51317 into the reaction chamber 14 to carry out an etching reaction.

(After completing etching, Ct, close the valve 15-1, open the N8 valve 15-2, and open the reaction chamber 14, for example, a
After replacing with N2 gas for s sty, N! Opening valve 3-
2 is closed. Since the volume of gas in a vacuum is expanding, the displacement is completed in the order of several tens of seconds.

In this state, the pipe from the exhaust device to the adsorbent filling container (for example, it has a capacity of several tens of tons) is still at atmospheric pressure, so Ct and gas at atmospheric pressure remain, so we will move on to the next bypass. Cannot move to sequence. Therefore, while the next wafer is being installed, the residual Ct and gas introduced from the conduit 6 at 51/min, for example, are introduced into the absorbent-filled container 1o, and the residual C2-rich gas is evacuated in advance. This allows only harmless gas to be bypassed when starting the next operation. Then (!
) to (4).

[Action of the invention]

When the treatment method and apparatus of the present invention are used for the dry treatment of semiconductor manufacturing exhaust gas, it is possible to avoid large fluctuations in the flow rate of the exhaust gas, and even when using an absorbent with a smaller particle size, there is no increase in ventilation resistance. It becomes possible to perform processing efficiently and safely.

In other words, a large amount of exhaust gas when the reaction chamber is evacuated from atmospheric pressure is discharged by bypass, so only a few gases are introduced into the absorbent-filled container every minute, and the particle size of the absorbent can be reduced by a considerable amount. Even if it is made finer to increase the surface area and increase the reaction efficiency, the ventilation resistance remains small. Therefore, the burden placed on the exhaust device for evacuating the reaction chamber is reduced, allowing safe processing.

In addition, since the gas flow rate is low, the contact time with the absorbent is longer, which greatly improves the efficiency of absorbent use, and reduces the amount of absorbent required for a given process. The filling container can also be made compact. Furthermore, even if solid matter is generated by the reaction between the exhaust gas and the absorbent, the gas flow rate is extremely small, so it does not cause much ventilation resistance.

In addition, by constantly purging the exhaust system and piping system using inert gas or immediately before exhausting the reaction chamber, it is possible to not only completely send the components to be treated into the absorbent-filled container, but also to purge the exhaust system and piping system with inert gas at all times or immediately before exhausting the reaction chamber. The piping system can also be kept clean at all times, making it possible to protect the entire device from dangers such as corrosion. In addition, the exhaust system or piping system may be disconnected for inspection or repair, but in such cases, purging can be performed, allowing work to be carried out safely without leaking dangerous gases. can.

As mentioned above, in order to treat semiconductor manufacturing exhaust gas,
When the reaction chamber is evacuated from atmospheric pressure using bypass piping, a large amount of exhaust gas is discharged without passing through the absorbent-filled container, and at the same time, the gas components remaining in the piping system to be treated are preliminarily filled with inert gas into the absorbent-filled container. There are many benefits to purging until

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a flow from a semiconductor manufacturing device to a container filled with an absorbent for exhaust gas, and FIG. 2 is a diagram for explaining nine examples in which the present invention is applied to an etching device. 1... Process gas, 2... Semiconductor manufacturing equipment, 5.
... Main pulp, 4... Exhaust piping, 5... Exhaust device, 6... Purge gas, 7... Bypass valve, 8...
・Bypass piping, 9...Pressure detector, 10...Absorbent filling container, 11...Electric circuit, 12...Exhaust pipe Patent applicant Ebara General Research Institute Ebara Corporation Ebara Corporation Infilco Co., Ltd.

Claims (1)

[Claims] 1. When exhausting the reaction chamber of an apparatus configured to treat exhaust gas from semiconductor manufacturing equipment with a dry absorbent from atmospheric pressure to a predetermined degree of vacuum, An inert gas for gas replacement is introduced into the downstream side of the chamber, and the gas components to be treated that exist in the exhaust system from the exhaust device to the absorbent filling chamber are sent to the absorbent filling chamber, where they are detoxified and then exhausted. After that, the bypass pipe installed between the inlet side piping and the outlet side piping of the absorbent filling chamber is opened to bypass a large amount of exhaust gas until the reaction chamber reaches a predetermined pressure, and the absorbent filling chamber and the exhaust gas are bypassed. A method for treating semiconductor manufacturing exhaust gas characterized by avoiding a pressure increase in the system. 2. Processing of semiconductor manufacturing exhaust gas according to claim 1, in which a bypass valve is opened based on a signal to open a main valve installed between a reaction chamber and an exhaust device for exhausting the reaction chamber. Method. 3. Semiconductor manufacturing exhaust gas according to claim 1, wherein an increase in inlet pressure is detected by a pressure detector on the inlet side pipe of the absorbent-filled container, and a bypass valve is opened in response to the detected pressure increase signal. processing method. 4. When exhausting the reaction chamber of semiconductor manufacturing equipment from atmospheric pressure to a predetermined pressure, in advance, after the exhaust system of the semiconductor manufacturing equipment, inert gas for purging is constantly supplied or immediately before exhausting the reaction chamber. The method according to claim 1, 2 or 3, wherein the gas component to be treated existing in the piping from the exhaust device to the absorbent filling chamber is sent to the absorbent filling container and rendered harmless. A method for treating semiconductor manufacturing exhaust gas. 5. In a semiconductor manufacturing exhaust gas processing equipment equipped with an exhaust device for exhausting exhaust gas from semiconductor manufacturing equipment and an absorbent-filled container filled with a dry absorbent, there is a main air supply between the reaction chamber of the semiconductor manufacturing equipment and the exhaust device. A valve is provided, a bypass pipe having a bypass valve is provided between the inlet side pipe and the outlet side pipe of the absorbent filling container, and an electric circuit for opening and closing the main valve and the bypass valve is provided. Semiconductor manufacturing exhaust gas treatment equipment. 6. The semiconductor manufacturing exhaust gas processing apparatus according to claim 5, wherein the bypass valve is opened by a signal from a pressure detector provided on the inlet side pipe of the absorbent-filled container. 7. The semiconductor manufacturing exhaust gas processing apparatus according to claim 5, wherein the electric circuit includes a timer, and after opening the main valve and the bypass valve, the bypass valve is closed after a predetermined time. 8. The semiconductor manufacturing exhaust gas processing apparatus according to claim 6, wherein the electric circuit is equipped with a timer, and after opening the bypass valve in response to a signal from the pressure sensor, the bypass valve is closed after a predetermined period of time.