JPH05192534A - Method and apparatus for making semiconductor exhaust gas harmless - Google Patents

Abstract

PURPOSE:To stably and continuously treat harmful and explosive semiconductor exhaust gas in a low running cost by once sucking the exhaust gas from a semiconductor producing apparatus to introduce the same into vacuum space and gradually drawing out the exhaust gas from the vacuum space to subject the same to heat treatment. CONSTITUTION:In a semiconductor producing apparatus such as a CVD apparatus, exhaust lines L are led out to be respectively connected to two vacuum tanks 14, 14 arranged in parallel. When raw exhaust gas 3a is introduced into a main vacuum tank 14 through the exhaust line L, the exhaust gas is diffused into the tank 14 to be diluted and an explosive component such as hydrogen or diborane and a component having strong toxity such as arsine or phosphine become lower limits or less. When the exhaust gas is heated by a heater 4 through an outlet changeover valve K2, the oxygen-containing harmful oxidizing component in the raw exhaust gas 3a is reacted. By this method, effective treatment for making exhaust gas harmless is safely and inexpensively performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing harmful exhaust gases, and more particularly to an effective method for removing harmful harmful and explosive exhaust gases for semiconductor manufacturing, and an apparatus therefor.

[0002]

Exhaust gas for semiconductor manufacturing includes explosive silane-based gas (eg, SiH ₄ or SiH ₂ cl ₂ ), toxic phosphorus-based gas (eg, PH ₃ ), arsenic-based gas (eg, AsH). ₃ ), boron-based gas (for example, B ₂ H ₆ ) and the like are used. These semiconductor manufacturing gas is supplied to the semiconductor manufacturing apparatus, various chemical reactions occur in the apparatus to process semiconductor wafers, and then exhaust gas is discharged from the apparatus.
Unreacted gas remains in the exhaust gas, and also contains harmful components newly generated by the reaction in the apparatus. Therefore, it is extremely dangerous to release the reaction exhaust gas to the atmosphere as it is, and conventionally, by diluting it with a large amount of nitrogen gas so that the exhaust gas concentration falls below the explosion lower limit, and then mixing a large amount of air. The method of releasing into the atmosphere as it was was taken. However, from the viewpoint of environmental protection, atmospheric emission has come to be regulated, and it has become impossible to emit diluted air as in the past.

Therefore, recently, it has become necessary to remove the harmful substances in the factory, but as the semiconductor becomes highly integrated, the manufacturing site is required to have a higher degree of cleanliness, and the harmful substances are also removed. It has been installed along with semiconductor manufacturing equipment and has come to be used in a clean room. Method 1
To give an example, prepare multiple cartridges filled with chemicals, pass the exhaust gas in order through them to react the chemicals in the cartridges with the harmful components in the exhaust gas, remove the harmful substances, and remove the used cartridges. There is a batch method of exchanging with a new cartridge. In this way, with the batch type abatement system, the used cartridge must be replaced with a new cartridge in a clean room.However, when this cartridge is replaced, harmful components, especially dust, leak from the used cartridge and There was a serious problem of soiling. Further, in the batch method, there is a problem that it is complicated because it is necessary to always grasp the consumption state of the cartridge. Therefore, at the semiconductor manufacturing site, it has been desired to develop an abatement method and an apparatus therefor, which is low in running cost and is not a batch-type abatement method, and is capable of treating exhaust gas stably and continuously. ..

[0004]

The problem to be solved by the present invention is that the running cost is low, and dangerous semiconductor exhaust gas that is harmful and explosive is stable and continuous, especially in a clean room. The purpose of the present invention is to propose a semiconductor exhaust gas abatement method and apparatus capable of treating the room without polluting the room.

[0005]

In order to solve the above-mentioned problems, according to the method of the present invention, as shown in claim 1, after exhaust gas discharged from a semiconductor manufacturing apparatus (1) is sucked into a vacuum space, a vacuum is generated. The exhaust gas gradually drawn out from the space (14) is heated to oxidize harmful oxidizing components contained in the exhaust gas. As a result, harmful and explosive semiconductor manufacturing exhaust gas can be effectively removed after it is vacuum diluted to the lower limit of explosion or lethal amount.

According to a second aspect of the present invention, the exhaust gas discharged from the semiconductor manufacturing apparatus (1) is treated in a vacuum space.
After sucking into the (14), the exhaust gas gradually drawn out from the vacuum space (14) is heated to oxidize the harmful oxidizing components contained in the exhaust gas, and then shower water (2) is sprayed onto the treated exhaust gas for treatment. The feature is that the solid matter contained in the exhaust gas is collected in the shower water (2) to clean the exhaust gas, and the cleaning water in which the solid matter is collected is collected and the clean exhaust gas is discharged. As a result, it is possible to effectively remove harmful and explosive exhaust gas for semiconductor production.

A semiconductor exhaust gas abatement apparatus according to a third aspect is an apparatus for carrying out the method, which comprises a vacuum tank (14) for sucking the exhaust gas discharged from the semiconductor manufacturing apparatus (1) and a vacuum tank ( Shower water (2) to the heating device (4) that gradually draws out the exhaust gas sucked into 14) and heats it to oxidize the oxidative harmful components in the exhaust gas, and the treated exhaust gas (3b) that has produced dust due to the oxidation reaction. The shower cleaning unit (5) for injecting the water and the shower cleaning unit (5) are disposed below the shower cleaning unit (5) and have a through hole in the center.
A morning glory shower receiver (7) in which (6) is bored, and a funnel which is arranged below the morning glory shower receiver (7) and has a throat hole (8) for passing a jet in the central portion. -Shaped part (9), skirt-shaped part (10) formed by connecting downward from throat hole (8) of funnel-shaped part (9), and morning glory shower receiver (7)
An intake air gap (12) formed between the funnel-shaped part (9) and the funnel-shaped part (9) and having an opening / closing means (11) capable of introducing outside air; and a water tank (13) arranged below the skirt-shaped part (10). It is characterized by being composed of.

According to a third aspect of the present invention, in the semiconductor gas abatement system of the third aspect, a pump pump (PY) is arranged in the water receiving tank (13), and the pump pump (PY)
The pumping pipe (22) derived from (Y), the skirt portion (10),
Shower (5) in the shower washing section (5) is passed through the throat hole (8) of the funnel-shaped portion (9) and the through hole of the morning glory shower receiver (7).
It is a feature connected to a). This allows pumping pipes (22)
The shower water (2) flows down along the pumping pipe (22) around the area in a spiral and dense state, and dust can be more effectively collected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus of the present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 is an overall flow diagram of a semiconductor manufacturing line including the device of the present invention, and FIG. 2 is a sectional view of the device of the present invention. In FIG. 1, (1) is a semiconductor manufacturing apparatus such as a CVD apparatus, in which an exhaust line (L) is drawn out and arranged in parallel.
It is connected to each of the base vacuum tanks (14) and (14 ').
One of the vacuum tanks (14) and (14 ') is a spare and both are equipped with a vacuum meter (P1), and the degree of vacuum inside the vacuum tanks (14) and (14') is checked. . (15) is an inert gas supply unit for supplying an inert gas such as nitrogen, which is connected to the vacuum tanks (14) and (14 ') via the valve (b1), and the vacuum tank (14) ( When the degree of vacuum inside 14 ') decreases and outside air enters inside, the vacuum tank (14) (1
It is used for emergency maintenance such as supplying a large amount of nitrogen gas to 4 ') to prevent the explosion of suction exhaust gas.

The exhaust line (L) led out from the vacuum tanks (14) and (14 ') once enters the outlet side switching valve (K2) and merges, then splits again, and then enters the flame arrester (16). Join together. Open / close valves for each of the flow dividing lines (BL1) (BL2)
(17), a vacuum pump (P2) and a check valve (18) are provided respectively so that the flow paths can be switched. The diversion line (BL1) is mainly used, the diversion line (BL2) is a spare, and is switched and used when the diversion line (BL1) fails.

The flame arrestor (16) is a cooling device for flashback prevention. The exhaust line (L) derived from the flame arrester (16) is connected to the heating device (4) and is heated there. As shown in FIG. 2, a large number of thin conduits (19) are arranged in the heating device (4), and the raw exhaust gas (3)
a) is designed to flow in the conduit (19), and hot gas flowing outside the conduit (19) or an electric heating coil wound around the conduit (19)
The raw exhaust gas (3a) is heated while flowing through the conduit (19) by means (not shown).

Further, a high-pressure inert gas supply means (20), for example, high-pressure nitrogen pipe is connected to the upstream side of the heating device (4), and high-pressure nitrogen gas is fed into the conduit (19) of the heating device (4). The inside of the pipe (19) can be cleaned by spraying intermittently. It is also used as a means for diluting raw exhaust gas (3a). Heating equipment (4)
The exhaust line (L) derived from the downstream end of the jet scrubber (J) is connected to the shower scrubber (5) of the jet scrubber (J). (30)
Is a bypass circuit that bypasses the heating device (4).

The jet scrubber (J) is a shower cleaning unit.
(5), scrubber tower (T), exhaust (H) and water tank (13). The shower cleaning section (5) is installed on the scrubber tower section (T), the shower (5a) is installed in the center of the interior, and the high-pressure shower water (2) is jetted downward. (21) is an inspection window that can be opened and closed. The shower cleaning section (5) is installed at the upper end of the scrubber tower section (T), and the bottom of the shower cleaning section (5) has a through hole (6) in the center. Shower receiver (7) is installed. As a result, the high-pressure shower water (2) is squeezed and flows downward along the circumference of the pumping pipe (22) through the central through hole (6). In addition, the casing (5b) of the shower cleaning section (5) is provided with an outside air introduction pipe (23) with an opening / closing valve, and the opening / closing valve (23a) is opened to open the outside air inside the casing (5b) if necessary. It can be taken into. This makes it possible to supplement oxygen when the raw exhaust gas (3a) does not contain oxygen or when the oxygen content is low.

A funnel-shaped portion (9) is installed below the morning glory shower receiver (7), and a throat hole (8) for passing a jet is formed in the center of the funnel-shaped portion (9). .. Furthermore, a skirt-shaped portion (10) is formed so as to extend downward from the throat hole (8) of the funnel-shaped portion (9) so as to extend downward.
The treated exhaust gas (3b) is narrowed down at (8).
In addition, an intake gap (12) that can be opened and closed to the outside air is formed between the morning glory shower receiver (7) and the funnel-shaped portion (9), and the outside air is sucked and treated exhaust gas ( It is designed to be mixed with 3a). As an opening / closing method, a well-known air supply opening / closing means (11) such as an opening / closing door is adopted.

A water receiving tank (13) is installed at the lower end of the scrubber tower (T), and the liquid medicine (2a) is stored in the water receiving tank (13). An overflow pipe (24) and a water supply pipe (25) are connected to the upper part of the water receiving tank (13), and a drain pipe (2
6) is connected. A pumping pump (PY) is installed in the receiving tank (13), and a pumping pipe derived from the pumping pump (PY).
The shower (5a) in the shower cleaning unit (5) is passed through the skirt-shaped portion (10), the throat hole (8) of the funnel-shaped portion (9) and the through hole (6) of the morning glory shower receiver (7). ) Is connected.

In the case of FIG. 1, the mist separator (27) is erected in parallel with the scrubber tower (T) on the water receiving tank (13) and is connected to the exhaust fan (HF). Further, (28) is a pH meter, which measures the pH of the chemical liquid (2a) in the water receiving tank (13) and, if necessary, activates the pump (P3) to provide the chemical liquid supply tank (29) installed side by side. A pH adjusting solution such as an acidic solution or an alkaline solution is supplied from the manufacturer to adjust the pH. The fresh chemical liquid (2a) is supplied from the water supply pipe (25) according to the overflow.

The embodiment of FIG. 2 is smaller than that of FIG. 1 and is devised so that it can be mainly used indoors. An exhaust duct is provided above the scrubber tower (T).
(D) is connected, and the outlet of the exhaust duct (D) is connected to the exhaust fan (HF). If necessary, a pH meter or a chemical solution supply tank can be installed as in the case of FIG. Also, the one shown in FIG. 1 can be used indoors.

The chemical liquid (2a) to be showered is selected according to the kind of the exhaust gas (3a), and water, alkaline water, or acidic water is appropriately used. There are various kinds of exhaust gas (3a), such as phosphine, diborane, silane, arsine, hydrogen selenide, hydrogen, hydrochloric acid gas, ammonia gas, etc., which are toxic, explosive, corrosive and other dangerous. It has various properties.

The raw exhaust gas (3a) discharged from the semiconductor manufacturing apparatus (1) is introduced into the main vacuum tank (14) through the exhaust line (L). A sufficient degree of vacuum is maintained in the vacuum tank (14), and the sucked exhaust gas is the vacuum tank (14).
It diffuses and dilutes inside, hydrogen, diborane, phosphine,
Exhaust gas containing explosive components such as arsine is below the lower limit of explosion, and exhaust gas containing highly toxic components such as arsine, phosphine, diborane and hydrogen selenide is below the lower limit of lethal dose and below the lower limit of other indicators. It becomes the concentration of. The vacuum tank (14) is evacuated to a vacuum by the vacuum pump (P2). In addition, when a failure occurs in the main vacuum tank (14), the switching valve (K1) on the inlet side allows quick switching to the auxiliary vacuum tank (14 ').
At the same time, a large amount of nitrogen gas is supplied to the main vacuum tank (14) to quickly dilute the exhaust gas inside the vacuum tank (14) and prevent the exhaust gas from exploding in contact with the outside air.

When the raw exhaust gas (3a) is sucked into the main vacuum tank (14) and diluted, it is drawn out from the main vacuum tank (14) at the diluted concentration and is heated through the outlet side switching valve (K2). (Four)
Connected to. Supply to the heating device (4) is usually a diversion line
(BL1) is used and supplied to the heating device (4) for heating. Here, the raw exhaust gas (3a) discharged from the semiconductor manufacturing apparatus (1) may contain oxygen in the form of a simple substance or a compound although it is usually a trace amount, and the raw exhaust gas (3a) in the heating device (4). )
By heating the oxygen, the oxygen contained in the raw exhaust gas (3a) and the reaction components in the raw exhaust gas (3a) are oxidized. A large amount of dry dust is generated by this reaction and accumulates in the conduit (19). A large amount of dust accumulated in the conduit (19) is intermittently discharged by the high pressure inert gas supply means (20).
It is blown off by ejecting (for example, nitrogen),
It will be sent to the shower cleaning unit (5) together with the treated exhaust gas (3b).

An example of the dry oxidation reaction is shown below. (1) Including silane-based gas SiH ₄ + 2O ₂ → Si 0 ₂ (dust) + 2H ₂ 0 (2) Including halogenated silane SiH ₂ cl ₂ + 0 ₂ → Si0 ₂ (dust) + 2Hcl (neutralize with alkaline solution) ) (3) Including phosphorus compound PH ₃ + 4O ₂ → P ₂ O ₅ + 3H ₂ O (4) Including arsenic compound AsH ₃ + 3O ₂ → As ₂ O ₃ + 3H ₂ O (5) Including boron compound B ₂ H ₆ + 3O ₂ → B ₂ O ₃ + 3H ₂ O

In this way, the treated exhaust gas (3b) containing a large amount of dust by the oxidation reaction enters the shower cleaning section (5), and the high pressure shower (5a) collects the dust in the shower spray (5). . The high-pressure shower water (5) is sprayed toward the morning glory shower receiver (7) having a through hole (6) in the center, is squeezed by the through hole (6) and passes through at an increased flow rate. . At this time,
The chance of contact between the shower jet (5) and the dust is increased, and it is effectively collected. In the present embodiment, when the pumping pipe (22) is erected in the center, the high-pressure shower water (5) passes in a spiral shape around the pumping pipe (22) as a center, The contact is measured at high density.

The shower spray (5) passing through the through hole (6) and the washed exhaust gas (3c) pass through the throat hole (8) in a state where the passing speed is increased, and the shower spray (5) also passes through this portion. The chances of contact with the dust increase, and the cleaning of the exhaust gas (3c) proceeds further. When the concentration of the exhaust gas (3b) is high, the opening / closing means (11) is opened to the atmosphere to suck the outside air from the intake gap (12), and a large amount of the outside air is mixed to dilute the high-concentration exhaust gas (3b), Then, it is introduced into the skirt-shaped portion (10) through the throat hole (8).

Since the skirt-shaped portion (10) becomes wider toward the lower side, the exhaust gas flow velocity decreases, and at the same time, the droplets coalesce into larger droplets and enter the water receiving tank (13). Water tank
The chemical solution (2a) in (13) is pumped up by the pumping pump (22) and sprayed again under high pressure by the shower (5a). In this way the drug solution (2a)
Since it is circulated and used, the amount of dust and soluble harmful components gradually increase and the drug solution (2a) becomes dirty. Therefore, a part of the old chemical liquid (2a) is discharged through the overflow pipe (24) and at the same time, the same amount of the new chemical liquid (2a) is supplied. In this way, the chemical solution (2a) is sequentially updated.

Further, the pumping pipe (22) has a through hole as described above.
(6), the throat hole (8) and the center of the skirt (10), so pressure spray (5) centered on the pumping pipe (22)
Will pass around it in a dense vortex state, and as described above, it will enhance the dust collection effect.

When the raw exhaust gas (3a) does not contain a trace amount of oxygen, the open / close valve (23a) for introducing the outside air is opened to accelerate the oxidation of the raw exhaust gas (3a), and the shower cleaning section is opened. Outside air is introduced into the casing (5b) of (5) to promote oxidation in the casing (5b). In this case, it goes without saying that the raw exhaust gas (3a) must be diluted with an inert gas to the lower limit of explosion.

The exhaust gas (3a) treated in this way becomes a clean exhaust gas (3c) and is released into the atmosphere by the exhaust section (H). As described above, the exhaust gas treatment can be continuously performed. In particular, if it is downsized as shown in FIG. 2, it can be used in a one-to-one correspondence with the semiconductor manufacturing apparatus (1) in a clean room.

[0028]

As described above, according to the method of the present invention, since the semiconductor exhaust gas discharged from the semiconductor manufacturing apparatus is sucked into the vacuum space, the exhaust gas concentration is instantaneously diluted according to the degree of vacuum, and the lower limit of explosion and lethality are lethal. The concentration will be below the lower limit of the amount and other indicators. Therefore, it is not necessary to dilute the exhaust gas with a large amount of nitrogen gas as in the conventional case, the cost of nitrogen gas can be reduced, and the running cost can be reduced. Further, since the exhaust gas diluted in this vacuum space is gradually drawn out and heated and oxidized, the harmful components are removed at this stage, and the effective harmful treatment as a whole can be safely performed.

In addition, in the second aspect, in addition to this, since the exhaust gas gradually drawn out from the vacuum space is heated to oxidize the harmful oxidizing component contained in the exhaust gas, the harmful component is removed at this stage and then showered. Therefore, all the dust and the like contained in the treated exhaust gas is collected in the shower water and becomes clean air. Since continuous processing is possible in this way, there is no need to replace the used cartridge in the clean room as in the batch method of the conventional example, and it is possible to keep the clean room clean at all times. There is an advantage that you can.

Further, in the semiconductor exhaust gas abatement system according to the third aspect, since the exhaust gas discharged from the semiconductor manufacturing apparatus is sucked into the vacuum space as described above, the exhaust gas concentration has a lower explosion limit in accordance with the degree of vacuum, It will be instantly diluted to a concentration below the lower limit of lethal dose and other indicators, and not only can you reduce running costs by saving nitrogen gas, but also because you have a heating device in the next step, vacuum It is possible to safely heat the exhaust gas taken out in a diluted state from the tank to oxidize harmful components in the exhaust gas to render it harmless, and since it has a shower cleaning section, it is possible to remove the dust generated by the oxidation reaction. . In addition, the shower spray flow below the shower cleaning section and the funnel-shaped section located below the morning shower shower can narrow the shower spray flow twice, so that the contact between dust and spray is efficient. The dust is effectively collected, and a high exhaust gas cleaning effect can be obtained. Furthermore, since the intake gap is formed between the morning glory shower receiver and the funnel-shaped portion, it is possible to dilute the high-concentration exhaust gas as necessary,
The method of the present invention can be carried out.

In the third aspect of the present invention, the shower pipe in the shower washing section is provided with the pumping pipe led out from the pumping pump in the receiving tank through the throat holes of the skirt-shaped portion, the funnel-shaped portion and the morning glory-shaped shower receiver. Since the sprayed shower water swirls around the pumping pipe and flows down at a high density and is squeezed by the through hole and the throat hole, the shower water is effectively contacted with dust. There is an advantage that the cleaning effect of exhaust gas can be enhanced.

[Brief description of drawings]

FIG. 1 is a flowchart of a first embodiment of the device of the present invention.

FIG. 2 is a flowchart of a second embodiment of the device of the present invention.

FIG. 3 is a cross-sectional view of the pumping pipe and the skirt portion according to the present invention.

[Explanation of symbols]

 (1)… Semiconductor manufacturing equipment (2)… Shower water (3)… Exhaust gas (4)… Heating device (5)… Shower cleaning part (6)… Through hole (7)… Morning glory shower receiver (8)… Throat Hole (9) ... Funnel-shaped part (10) ... Squard-shaped part (11) ... Opening / closing means (12) ... Intake gap (13) ... Water tank (14) ... Vacuum tank (20) ... High pressure inert gas supply means

Claims (4)

[Claims] 1. A semiconductor characterized in that after exhaust gas discharged from a semiconductor manufacturing apparatus is sucked into a vacuum space, the exhaust gas gradually extracted from the vacuum space is heated to oxidize harmful oxidative components contained in the exhaust gas. Exhaust gas abatement method. 2. The exhaust gas discharged from the semiconductor manufacturing apparatus is sucked into the vacuum space, and the exhaust gas gradually drawn out from the vacuum space is heated to oxidize harmful oxidizing components contained in the exhaust gas, and then shower water is added. Characterized by spraying the treated exhaust gas, collecting the solids contained in the treated exhaust gas in the shower water to purify the exhaust gas, collecting the cleaning water that has collected the solid substances, and releasing the purified exhaust gas. Semiconductor exhaust gas abatement method. 3. A vacuum tank for sucking exhaust gas discharged from a semiconductor manufacturing apparatus, and a heating device for gradually drawing out and heating the exhaust gas sucked into the vacuum tank to oxidize oxidative harmful components in the exhaust gas. A shower cleaning unit that injects shower water into the treated exhaust gas that has generated dust due to oxidation reaction, a morning glory shower receiver that is located below the shower cleaning unit and has a through hole in the center, and a morning glory A funnel-shaped portion which is arranged below the shower receiver and has a throat hole for passing a jet in the central portion, a skirt-shaped portion formed by connecting the throat hole of the funnel-shaped portion downwardly, and a morning glory shower Semiconductor exhaust gas removal characterized by comprising an intake gap formed between a receiver and a funnel-shaped portion and having an opening / closing means capable of introducing outside air, and a water tank arranged below the skirt-shaped portion. Harm device. 4. The semiconductor gas abatement system according to claim 2, wherein a pump is arranged in the receiving tank, and the pumping pipe led out from the pump is used as a skirt hole, a throat hole of a funnel shape and a morning glory shower receiver. A semiconductor exhaust gas abatement device characterized by being connected to a shower in a shower cleaning section through a through hole.