JPH0461686B2 - - Google Patents

Description

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

[Conventional technology]

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

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 around several minutes per minute, whereas When evacuation is performed from atmospheric pressure, several thousand gases 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 a semiconductor device 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. In other words, 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 exhaust gas to be treated within the packed layer. . However, in general, coarse absorbents have to be used to keep airflow resistance low; however, as the particle size increases, the surface area involved in absorption or adsorption becomes relatively small, resulting in a decrease in absorption capacity. . For this reason, attempts have been made to improve the absorption capacity by using porous absorbents, but these methods also have limitations, and in the end, it is not possible to secure the specified absorption capacity by filling a considerable amount of absorbent. The reality is that Additionally, some exhaust gases react with absorbents to form solids, and in such cases, even if the absorbent is coarsened, the reaction products will gradually fill the packed layer. Since it becomes blocked, it is impossible to simulate 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 using 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. By opening the bypass valve, a large amount of exhaust gas generated when the reaction chamber is evacuated 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 removed. It is characterized in that the gas is replaced with an inert 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 can be of any type as long as it processes wafers under high vacuum, such as plasma CVD or plasma etching, and the type and flow rate of the process gas 1 can also be determined according to each process. It's okay. 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 14 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 can be removed by opening the bypass valve 7 and moving the bypass piping 8. The absorbent is discharged without passing through the absorbent filling container 10. At this time, since a large amount of exhaust gas is discharged only after the main valve 3 is opened, the bypass valve 7 may be opened in advance based on a signal for opening the main valve 3. However, since the main valve 3 remains open during etching, the bypass valve 7 also remains open. Therefore, the timer is set to close after a predetermined time, but the timer setting time at that time is sufficient time for the exhaust flow rate to decrease and the inlet pressure of the absorbent filling container 10 to be low, and also for the reaction chamber to be closed. Any time before the process gas is introduced may be used.

In addition, when a large amount of exhaust gas is directly introduced into the absorbent-filled container, the pressure on the inlet side of the container increases, so this pressure increase is detected by the pressure detector 9,
The bypass valve 7 may be opened by the signal.
However, in this case, at the same time as the bypass valve 7 opens, the inlet pressure drops, the pressure detector 9 senses this and closes the bypass valve, and then the pressure rises again and the bypass valve opens, which is a hunting phenomenon. may occur. Therefore, if you use a timer and set the timer to close the bypass valve after exhausting until the inlet pressure is low enough that the bypass valve will not open again even if the exhaust flow rate decreases and the bypass valve is closed. good.

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. It is preferable to release a large amount of 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 injection period may be either constant injection or only for a certain period of time immediately before exhausting the reaction chamber. good. Further, the flow rate of the injection gas may be determined by taking into account the volume of the piping to be purged, the injection time, etc. Note that the exhaust gas is exhausted through the exhaust pipe 12.

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

Before the start of operation, the main valve 3 is closed, and the exhaust system 5 is constantly operated, and the exhaust gas is
_N2 gas is constantly introduced. Then, the bypass valve 7 is closed, the pressure detection device 9 is turned off, and the Cl ₂ valve 13-1 and the N ₂ valve 13-
2 is closed, and the reaction chamber 14 is at atmospheric pressure.

The operation method of this apparatus will be explained together with its functions: (1) First, a wafer is placed in the reaction chamber 14, and the lid is closed and the main valve 3 is opened. Exhausted by. At this time, since the evacuation speed is high (for example, 1200/min), a large amount of air is introduced into the absorbent-filled container 10 at the initial stage of evacuation.

The pressure loss of the absorbent-filled container is the design flow rate of 0.
~30/min, so when exhaust gas flows into the exhaust piping at an initial displacement rate of 1200/min, the pressure increases.

(2) Therefore, by opening the bypass valve 7 in advance in response to a signal indicating that the main valve 3 is open, or by opening the bypass valve 7 by detecting the pressure increase with a pressure detector, it is possible to The portion is mainly exhausted through the bypass pipe 8.

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) Next, open the Cl ₂ valve 13-1 and, for example,
0.5 Sl/min of Cl ₂ is introduced into the reaction chamber 14 to carry out an etching reaction.

(4) After etching is completed, close the Cl ₂ valve 13-1 and open the N ₂ valve 13-2 to replace the reaction chamber 14 with N ₂ gas of, for example, 0.5 Sl/min, and then close the N ₂ valve. 13-2 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-filled container (for example, it has a volume of several dozen) is still at atmospheric pressure, so atmospheric pressure Cl ₂ gas remains, so if this continues, the next bypass sequence will be carried out. cannot move to. Therefore, for example, 5
By introducing the residual Cl ₂ gas into the absorbent-filled container 10 with N ₂ /min and evacuating the residual Cl ₂ gas in advance, only harmless gas can be bypassed when starting the next operation. Then
Repeat steps (1) to (4).

[Action of the invention]

When the treatment method and apparatus of the present invention are used for dry oven treatment of semiconductor manufacturing exhaust gas, large fluctuations in the flow rate of the exhaust gas can be avoided, and even if an absorbent with a smaller particle size is used, an increase in ventilation resistance can be avoided. This makes it 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 considerably. Even if the reaction efficiency is increased by increasing the surface area, the ventilation resistance remains small. Therefore, the burden placed on the exhaust device for evacuating the reaction chamber is reduced, allowing safe processing.

Additionally, because the gas flow rate is low, the contact time with the absorbent is longer, which greatly improves the efficiency of absorbent utilization, and reduces the amount of absorbent required for a given process. The container can also be made compact. Furthermore, even if solids are produced that are good for the reaction between the exhaust gas and the absorbent, the gas flow rate is extremely small, so this does not result in a large ventilation resistance.

In addition, by using inert gas to purge the exhaust system and piping system at all times or immediately before exhausting the reaction chamber, not only can the components to be treated be completely delivered to the absorbent-filled container, but also the exhaust system and piping system can be purged using inert gas. can 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 described above, when processing semiconductor manufacturing exhaust gas, a large amount of exhaust gas is discharged when the reaction chamber is evacuated from atmospheric pressure by bypass piping without passing through the absorbent-filled container, and moreover, at that time, there is a large amount of exhaust gas that remains in the piping system. A number of advantages are obtained by previously purging the gas components to be treated with an inert gas up to the absorbent-filled vessel.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a flow from a semiconductor manufacturing apparatus to a container filled with an absorbent for exhaust gas, and FIG. 2 is a diagram for explaining an example in which the present invention is applied to an etching apparatus. 1...Process gas, 2...Semiconductor manufacturing equipment,
3... Main valve, 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.

Claims (1)

[Scope of Claims] 1. When exhausting a 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 downstream of the exhaust system, 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 exhausted. By opening the bypass pipe installed between the inlet side piping and the outlet side piping of the post-absorbent filling chamber, a large amount of exhaust gas is bypassed until the reaction chamber reaches a predetermined pressure, and the absorbent filling chamber and exhaust system are A method for treating semiconductor manufacturing exhaust gas, characterized by avoiding a rise in pressure within the interior. 2. Claim 1, in which the bypass valve is opened based on a signal to open the main valve installed between the reaction chamber and the exhaust device for evacuating the reaction chamber.
A method for treating semiconductor manufacturing exhaust gas as described in . 3. The semiconductor manufacturing exhaust gas recited in claim 1, wherein an increase in inlet pressure is detected by a pressure sensor on the inlet side piping of the absorbent-filled container, and a bypass valve is opened in response to the detected pressure increase signal. Processing method. 4. When evacuating 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 the reaction chamber is evacuated. The semiconductor according to claim 1, 2 or 3, wherein the gas components to be treated are introduced and present in a pipe leading from an exhaust device to an absorbent filling chamber and are detoxified by being sent to an absorbent filling container. How to treat 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 filling container filled with a dry absorbent,
A main valve is provided between the reaction chamber of the semiconductor manufacturing equipment and the exhaust device, a bypass pipe with a bypass valve is provided between the inlet side pipe and the outlet side pipe of the absorbent filling container, and the main valve and an electric circuit for opening and closing a bypass valve. 6. The semiconductor manufacturing exhaust gas processing apparatus according to claim 5, wherein the bypass valve is opened by a signal from a pressure sensor 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 period of 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 detector, the bypass valve is closed after a predetermined period of time.