JPH1133345A - Removing device for semiconductor manufacture exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove deposit exhaust gas and cleaning exhaust gas exhausted out of a sheet type CVD while taking the time period by one device in the manufacture of semiconductors. SOLUTION: A reaction cylinder for the oxidative heat destruction of semiconductor manufacture exhaust gas is provided. Deposit exhaust gas pipings D1 -D4 and cleaning gas pipings C1 -C4 are connected with respective treatment elements E1 -E4 of the sheet type CVD through valves. The deposit exhaust gas pipings D1 -D4 from respective treatment elements E1 -E4 are joined to one deposit exhaust gas collecting piping Dt, while cleaning exhaust gas pipings from respective elements E1 -E4 is joined to one cleaning exhaust gas collecting piping Ct. The deposit exhaust gas collecting piping Dt and the cleaning exhaust gas collecting piping Ct are connected with the reaction cylinder, and atmosphere can be introduced into the reaction cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abatement apparatus that can remove a deposit exhaust gas and a cleaning exhaust gas discharged from a VD by one unit.

[0002]

2. Description of the Related Art The productivity of silicon wafer high-order processing has been improved by using single-wafer CVD. When single wafer CVD is used, a deposition gas such as SiH ₄ and a cleaning gas such as NF ₃ are exhausted from each element (chamber) at time intervals.

[0003] In other words, since each processing element sequentially advances the process while taking a time lag, a deposit exhaust gas is discharged from one processing element and a cleaning exhaust gas is discharged from another processing element.

For example, when the processing elements are four chambers E _{1 to} E ₄ , CVD proceeds by repeating the depositing process and the cleaning process stepwise from the processing element E _{1 to the} processing element E ₄ . That deposit process is performed in the processing element E ₁ first stage, N ₂ purge is performed by the processing element E ₂ in the second stage in the processing element E ₁ with deposit process is performed. The first 3 N ₂ purged with processing elements E ₂ with deposit process in the processing element E ₃ in step is performed is performed, a cleaning process is performed by the processing element E _1. In a further fourth step, the processing element E ₄
And the processing element E ₃
, An N ₂ purge is performed, and a cleaning step is performed in the processing element N ₂ . Thereafter, the respective steps are similarly performed in a stepwise manner.

Here, since the mixed gas of the SiH ₄ / NF ₃ / N ₂ system forms an explosive composition in a wide range of SiH ₄ concentration of 0.66 to 95.3%, the exhaust gas from each processing element must be collectively and simultaneously detoxified. Can not.

[0006] Therefore, conventionally, each exhaust gas is received in a separate line and processed by a plurality of abatement devices, or each exhaust gas is included in N ₂ gas and mixed with each other so as not to mix with each other. It was sent in and processed by the "curtain combustion method".

[0007] In each case, the processing efficiency is low, the equipment cost is increased, and the processing cost is increased.

Further, it is sometimes impossible to discharge the deposit exhaust gas and the cleaning exhaust gas at the same interval in the same pipe due to the high pressure gas control law.

Means for removing exhaust gas from semiconductor production include deposition exhaust gas and cleaning exhaust gas, respectively, for adsorption and detoxification by a solid adsorbent, removal of heat by a flame combustion method, and oxidation and detoxification by an electrothermal heating method. Are used.

[0010] Among them, the adsorption method has a small abatement capacity, and is problematic in that the cost associated with replacement of the adsorbent is high. Also, use cost and safety of H ₂ or propane as the fuel in the case of flame combustion mode becomes a problem.

[0011] Even in the electrothermal heating system, a separate abatement system for the deposit exhaust gas and the cleaning exhaust gas requires a plurality of abatement devices, and has various problems associated with equipment cost and equipment complexity.

[0012]

Therefore, it is possible to simultaneously remove harmful deposit exhaust gas and cleaning exhaust gas discharged from a single-wafer type CVD by a single unit, and furthermore, in a pipe leading to a reaction tube, each exhaust gas has a single composition. There is a need for a method and apparatus for removing semiconductor manufacturing exhaust gas by an electric heating method which is discharged in a state and has no danger of explosion.

[0013]

According to the first aspect of the present invention, there is provided a semiconductor production exhaust gas abatement apparatus (1) having reaction tubes (2) and (3) for oxidizing, heating and decomposing semiconductor production exhaust gas. This is a detoxification apparatus, and a pipe for deposit exhaust gas (for example, D _{1 to} D ₄ ) is provided to each processing element (for example, E _{1 to} E ₄ ) of the single wafer CVD.
And a cleaning exhaust gas pipe (for example, C _{1 to} C ₄ ) are connected via a valve, and each processing element (E ₁ to
The pipe (D _{1 to} D ₄ ) for deposit exhaust gas from E ₄ ) joins one deposit exhaust pipe (Dt), and the pipe for cleaning exhaust gas from each processing element (E _{1 to} E ₄ ) The cleaning exhaust gas collecting pipe (Ct) merges with one cleaning exhaust gas collecting pipe (Ct). The deposit exhaust gas collecting pipe (Dt) and the cleaning exhaust gas collecting pipe (Ct) are connected to a reaction tube, and the reaction tube can introduce external air. It is characterized by the following.

According to a second aspect of the present invention, there is provided the abatement apparatus for a semiconductor manufacturing exhaust gas according to the first aspect, wherein the deposit exhaust gas collecting pipe is connected to the reaction tube via a water scrubber (5a). The cleaning exhaust gas collecting pipe is directly connected to the reaction tube without passing through the water scrubber (5a), and the connection point between the cleaning exhaust gas collecting pipe (Ct) and the reaction cylinder is the deposit exhaust gas collecting pipe (Dt). It is characterized by being downstream from a connection point with the reaction tube.

According to a third aspect of the present invention, there is provided the abatement apparatus for a semiconductor manufacturing exhaust gas according to the first or second aspect, wherein the reaction cylinder is an outer cylinder and an inner cylinder disposed in the outer cylinder. A strip for scraping off dust adhering to the inner cylinder surface by rotating in a non-contact state with the inner cylinder along at least one of the inner surface and the outer surface of the inner cylinder and stirring the gas in the reaction cylinder Characterized by having a plate of

[0016]

DETAILED DESCRIPTION OF THE INVENTION The abatement apparatus of the present invention is a single-wafer CVD.
Although not limited to the number of processing elements described above, a case where the number of elements is 4 will be described below as an example. FIG.
FIG. 3 is a diagram showing connections between a detoxification apparatus and piping of each processing element when a single-wafer CVD system including four processing elements is used. E ₁ to E ₄ in the figure is a pump for each processing element, P ₁ to P ₄ are N ₂ purge (cleaning).

[0017] The device for removing exhaust gas from semiconductor production of the present invention (1)
Are pipes for deposit exhaust gas and pipes D _{1 to} D ₄ for discharging exhaust gas discharged from each processing element (E _{1 to} E ₄ ) of the _single- wafer CVD separately into a deposit exhaust gas and a cleaning exhaust gas. the cleaning gas pipe C ₁ -C ₄ provided, piping deposit exhaust gas through a valve switching at tunes electrically controlled gas species time supplied into the CVD Dn and cleaning the exhaust gas pipe Cn
(If the number of processing elements is 4, n is 1 to 4).

Therefore, at a specific time, the deposit exhaust gas is discharged to the deposit exhaust pipe Dn, and the cleaning exhaust gas is discharged to the cleaning exhaust pipe Cn. The deposit exhaust pipes D _{1 to} D ₄ join together to form a deposit exhaust pipe Dt, and the cleaning exhaust pipes C _{1 to} C ₄ join to form a cleaning exhaust pipe Ct. The deposit exhaust gas collecting pipe Dt and the cleaning exhaust gas collecting pipe Ct are connected to a reaction tube of the abatement apparatus, so that each gas can be introduced into the reaction tube.

That is, a pipe for a deposit exhaust gas and a pipe for a cleaning exhaust gas are connected to each processing element of the single wafer CVD, so that a pipe having a multiple of the number of elements is connected to the CVD side. Further, the pipes for the deposit exhaust gas merge into one collective pipe Dt for exhaust gas, and the pipes for cleaning exhaust gas also merge into one collective pipe Ct for cleaning exhaust gas. The number of piping is two regardless of the number of processing elements of CVD.

[0020] introducing the N ₂ gas as always N ₂ purge when switching deposit process and a cleaning process in each processing element. Thereby, the gas is discharged from the processing element used in the previous process so that both gases are not mixed in the next process.

For example, if the deposition process has been performed with SiH ₄ gas, N
_In order to flow the ₂ gas as cleaning inside the pipe, N ₂ gas mixed with a small amount of SiH ₄ gas is discharged in the initial stage,
_{2 The} single gas will be introduced into the deposit exhaust pipe.

Then, the N ₂ gas is shut off and the electric switching valve is operated to close the deposit exhaust pipe, the cleaning exhaust pipe is opened, and the cleaning exhaust gas of, for example, NF ₃ alone is discharged, and the discharge is completed. After that, the substrate is washed with N ₂ gas.

The pipes D _{1 to} D ₄ and the collective pipe Dt discharge only the deposit exhaust gas and the N ₂ gas for purging at the time of switching the pipes, and the pipes C _{1 to} C ₄ and the collective pipe Ct discharge the clean exhaust gas and the collective pipe at the time of the pipe change. , Only the purge N ₂ gas is discharged. Therefore, only in the reaction tube of the detoxification apparatus in which the collective pipe Dt and the collective pipe Ct are connected, the deposit exhaust gas and the cleaning exhaust gas may coexist.

Then, in the reaction tube, in the presence of external air, the oxidative heat decomposition of the deposit exhaust gas (in some cases, the cleaning exhaust gas) proceeds for the first time. Therefore, the two gases do not mix in the piping before the reaction tube is introduced, there is no danger of explosion in the mixed system of SiH ₄ / NF ₃ / N ₂ , and there is no conflict with the high-pressure gas control law and safety. Is high.

The deposit exhaust gas to be abated by the abatement system of the present invention is SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , T
Also included are organosilicon compounds such as EOS, and dopant gases such as PH ₃ and B ₂ H ₆ , which are oxidized and decomposed as deposit exhaust gas alone or in the presence of cleaning exhaust gas to form SiO ₂ , P ₂ O ₅ , B abated becomes ₂ 0 oxide such as _3.

On the other hand, the cleaning exhaust gas contains NF ₃ , S
Single or CVD of fluorinated compounds such as F ₆ , C ₂ F ₆ and CF ₄
Exhausted as decomposition gas in the chamber, for example, SiF ₄ , F ₂ ,
CO _X , N _2, etc. are introduced into the abatement apparatus in the presence of undecomposed fluorinated compounds.

FIG. 2 is a diagram schematically showing the overall configuration of the abatement apparatus (1). In the reaction tube of the abatement apparatus (1), a cylindrical ceramic heater as an inner tube (3) is arranged at the center of the outer tube (2). This ceramic heater has a surface covered with alumina or mullite, and has a heating wire inside.

The outer cylinder (2) has a structure in which the inner surface is covered with a ceramic made of alumina or mullite.
In some cases, it may be constituted by a ceramic heater. In this case, since both the outer cylinder (2) and the inner cylinder (3) are composed of ceramic heaters, the efficiency of heat radiation and heat conduction of the exhaust gas introduced into the space of the reaction cylinder is extremely high.

An exhaust fan is provided downstream of the discharge pipe of the abatement apparatus.
(7) is installed, and the inside of the abatement apparatus is depressurized by the function of the exhaust fan (7), and exhaust gas from each processing element of CVD is introduced.

It is effective to connect the deposit exhaust gas collecting pipe Dt to the reaction tube via the water scrubber (5a) on the inlet side. That is, the deposit exhaust gas collecting pipe Dt is connected to the upper part of the water scrubber (5a), and the deposit exhaust gas is a water-soluble component (for example, NH ₃ ), a hydrolysis component (eg, NH ₃ ) in the exhaust gas while passing through the water scrubber (5a). For example, SiH ₂ C
l ₂ ) The gas is washed off and then enters the reaction tube.

External air is always introduced into the lower part of the inlet water scrubber (5a) through the external air introduction pipe (4) in an amount at least twice as much as the theoretical amount required for the oxidative decomposition of the gas to be treated. Is done.

The deposit exhaust gas sucked into the space between the outer cylinder (2) and the inner cylinder (3) of the reaction cylinder forms a spiral while being mixed with the external air introduced from the external air introduction pipe (4). And proceed upward along the surface (tube wall) of the ceramic heater, during which most of the deposit exhaust gas components undergo oxidative thermal decomposition.

On the other hand, the cleaning exhaust gas collecting pipe Ct is connected directly above the heater of the reaction tube without passing through the water scrubber (5a). This position is located downstream of the joint of the deposit exhaust gas collection pipe in terms of the flow of the gas to be treated in the reaction tube, and the cleaning exhaust gas is introduced to a position where the deposit exhaust gas has been mostly oxidatively decomposed.

Therefore, in the SiH ₄ / NF ₃ / N ₂ mixed system, NF ₃ is mixed in the composition region where the SiH ₄ concentration is extremely reduced.

From that position, the inner space of the inner cylinder (3) as the heater is drawn downward from above. During that time, the cleaning exhaust gas (for example, NF ₃ ) is decomposed into components.

Temperature of ceramic heater (surface contact temperature)
Is 600 to 1000 ° C. as a standard. While passing through the space set at this temperature, the deposit exhaust gas and the cleaning exhaust gas are oxidized, heated and decomposed.

In the cleaning exhaust gas, CF ₄ may not be completely removed at a heater temperature of 1000 ° C.
Temperatures between 1000 ° C and 1300 ° C are sometimes used.

The exhaust gas that has passed through the reaction tube passes through a separately provided water scrubber (5b) on the outlet side, undergoes cooling and washing, and is discharged to the atmosphere from an exhaust port (8). In the water scrubber (5b), fluorinated water-soluble gas such as F ₂ and HF generated by elimination of oxide dust and cleaning gas generated in the reaction tube, hydrolyzable gas and dust are removed. Washed and harmed. (6) in the figure is a washing water tank.

In the above description, the positions of introduction of the deposit exhaust gas, the external air, and the cleaning exhaust gas into the reaction tube are merely examples, and the present invention is not necessarily limited to such examples.

Meanwhile, in the oxidative decomposition of the deposit exhaust gas, dust containing SiO ₂ as a main component is generated and adheres to the surface of the ceramic heater, thereby reducing the heat transfer effect and increasing the ventilation resistance of the exhaust gas. As a result, the abatement efficiency is reduced.

In order to avoid this, as in the abatement apparatus described in Japanese Patent Application No. 9-38318, the state of non-contact with the inner cylinder along the inner and outer surfaces of the inner cylinder ceramic heater inside the reaction cylinder is considered. It is effective to provide a mechanism for rotating and removing the dust adhering to the inner cylinder surface.

For scraping off, it is preferable to use a plate made of an alumina or mullite hard ceramic strip (thickness: 2 to 3 mm), and the distance between the inner cylinder ceramic heater and the inner cylinder surface is about 2 mm. desirable.

Since the scraping means generates a turbulent flow by rotation, it agitates the space near the heater in the reaction tube and contributes to the exhaust gas itself or the mixing and stirring of the exhaust gas and external air.

A water scrubber (5b) on the outlet side for washing and removing at least one of a hydrolyzable gas, a water-soluble gas and dust generated by the heat oxidation treatment in the reaction tube is provided with a reaction tube and an exhaust port (8). Is provided between

Hereinafter, the present invention will be described with reference to examples. [Example 1] Single-wafer CVD composed of four processing elements was used, and SiH ₄ (100% composition) was 1 liter / min as a deposit exhaust gas flowing into a collecting pipe Dt.
Gas water scrubber carrier N ₂ is discharged at a flow rate of 200 l / min (introduced gas SiH ₄ concentration 5000 ppm) (5a)
At the upper part of the inlet of the water scrubber (5a), and at the lower part of the water scrubber (5a), external air was added at 35 liter / min.
It passed through the space between the inner cylinder ceramic heater (3) and the outer cylinder (2) set at 0 ° C.

A cleaning exhaust gas containing NF ₃ (100% composition) of 2.5 L / min and carrier N ₂ of 120 L / min (introduction gas NF ₃ concentration of 2%) from the upper portion of the inner ceramic heater (3). Was spirally introduced from the tangential direction of the inner cylindrical ceramic heater (3).

Further, three 2 mm thick, 10 × 120 mm plates made of alumina are suspended around the outer circumference and inner circumference of the inner cylindrical ceramic heater (3), respectively, and are suspended around the inner cylindrical ceramic heater at a rotation speed of 20 rpm. Was rotated while maintaining a distance of 2 mm from the heater surface.

After operating for 1 hour under these conditions, the exhaust gas after the water scrubber (5b) treatment on the outlet side was analyzed.
iH ₄ was 1 ppm or less, and NF ₃ was 3 ppm. That is, in single wafer CVD, each treatment element is introduced into the abatement system through an exhaust gas pipe independent of the treatment element, and both gases of SiH ₄ and NF ₃ are safely reduced to a value below TLV (exhaust standard) without an explosion phenomenon. It could be harmed.

The amount of water stored in the washing water tank (6) is 70 liters, and the amount of circulating water in the water scrubber is 10 liters / min.
Gas cleaning was performed.

After the operation for one hour, the power was turned off, and after the temperature of the heater was lowered, the apparatus was disassembled and examined. The outer surface, the inner surface, and the inner surface of the outer cylinder were almost completely accumulated with the SiO ₂ powder. Was not found.

Example 2 Using a single-wafer type 6-element CVD, TEOS was vaporized by an evaporator as a deposit gas, diluted with a N ₂ carrier gas, and the air volume was 200 liter / min, and the TEOS concentration was 2,000 ppm. Was discharged. Then, as in Example 1, the reaction tube was introduced between the inner and outer cylinders.

The external air was mixed with the deposit exhaust gas at a flow rate of 105 liter / min, and oxidized and decomposed by heating with a heater set at a surface temperature of 900 ° C.

Meanwhile, using a C ₂ F ₆ gas as a cleaning gas, 0.75 L / min at the 100% gas N ₂
3,000 ppm diluted with carrier gas at 250 l / min
The solution was sent to the collecting pipe at a concentration, and was introduced spirally from the upper part of the reaction tube in the tangential direction of the heater surface of the inner cylinder, and was thermally oxidized and decomposed while being in contact with the heater.

The dust generated on the inner and outer surfaces of the inner cylinder was scraped off by the same stirring mechanism as in the first embodiment.

After operating for 1 hour under the above conditions, the composition of the gas released from the atmosphere was analyzed. As a result, TEOS was 2 ppm and C ₂ F ₆ was 5 ppm.
It was 0 ppm. No abnormal phenomenon including explosion occurred during the treatment process.

[0056]

As described above, according to the present invention, it is possible to remove a deposit exhaust gas and a cleaning exhaust gas discharged from a single-wafer-type CVD in a time cycle in a semiconductor manufacturing process with a single abatement apparatus. Became.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing connection of pipes between a single-wafer CVD and an abatement apparatus.

FIG. 2 is a diagram showing an outline of a configuration of an abatement apparatus.

[Explanation of symbols]

(1) Abatement equipment (2) Outer cylinder (3) Inner cylinder (ceramic heater) (4) External air inlet pipe (5a) Water scrubber (inlet side) (5b) Water scrubber (outlet side) (6) Wash water Liquid tank (7) Exhaust fan (8) Exhaust port (C ₁ ) to (C ₄ ) Cleaning exhaust pipe (Ct) Cleaning exhaust pipe (D ₁ ) to (D ₄ ) Deposit exhaust pipe (Dt) Deposit exhaust gas Collective piping (E ₁ ) to (E ₄ ) Single wafer CVD element

Claims (3)

[Claims] An abatement apparatus having a reaction tube for oxidizing, heating, and decomposing exhaust gas from semiconductor production, comprising a single-wafer CVD.
A deposit exhaust pipe and a cleaning exhaust pipe are connected to each processing element via a valve.
The pipe for deposit exhaust gas from each processing element joins one deposit exhaust pipe, and the pipe for cleaning exhaust gas from each processing element joins one cleaning exhaust pipe. And a cleaning exhaust gas collecting pipe connected to a reaction tube, wherein the reaction tube can introduce external air. 2. The exhaust gas collecting pipe is connected to the reaction tube via a water scrubber, and the cleaning exhaust gas collecting pipe is directly connected to the reaction tube without passing through a water scrubber. 2. The exhaust gas abatement apparatus according to claim 1, wherein a connection point with the reaction tube is downstream of a connection point of the deposit exhaust gas collection pipe with the reaction tube. 3. The reaction cylinder comprises an outer cylinder and an inner cylinder disposed in the outer cylinder. The reaction cylinder rotates along at least one of the inner surface and the outer surface of the inner cylinder in a non-contact state with the inner cylinder. 3. The apparatus according to claim 1, further comprising a strip-shaped plate for scraping off dust adhering to the surface and agitating the gas in the reaction tube.