JPH04347408A - Method of burning fluid - Google Patents

Abstract

PURPOSE:To burn silane completely when an abnormal state develops and monitor the combustion in a system of burning silane gas that is discharged from a vapor growth device. CONSTITUTION:A silane gas that is discharged from a vapor growth device (the gas is diluted in ordinary operation and it is not, therefore, discharged) is burned completely by supplying air to a nozzle provided inside a combustion cylinder 21. However, in an abnormal state that the air supplied from the plant line is stopped also, a sensor works and the supply is continued, but the volume and speed of the air is controlled by passing it through a flow rate resisting section 25 of a combustion assisting fluid. As a result complete combustion is almost achieved, and the generation of oxides is suppressed as much as possible. Safety can be, therefore, secured.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] The present invention applies to silane and dichlorosilane (hereinafter, the term silane will also include dichlorosilane).
Regarding CVD equipment and related auxiliary equipment that use
In particular, this combustion method is suitable for forcibly burning exhaust fluid when an abnormal situation occurs such as a stoppage of the supply of nitrogen gas line or an increase in the flow rate of silane gas at a factory due to an operational error.

0003

2. Description of the Related Art When semiconductor elements are fabricated on semiconductor substrates, it is common to coat them with a CVD layer, that is, a vapor-phase growth layer, which can be coated at a relatively low temperature, using a special equipment. Fluid with a risk of explosion is burned and removed by a separately provided combustion tube. This system will be explained with reference to the system diagram of FIG. 1.

[0004] In the main body of the vapor phase growth apparatus, which handles fluids that may potentially explode, an interlock function is used to stop the fluid supply to the subsequent process process as a countermeasure in the event that the supply of high-pressure gas is stopped. There is.

The vapor phase growth apparatus 1 in such a system connects the main duct 2 and the inlet 4 of the combustion tube 3 with piping, further connects the outlet of the combustion tube 3 with the water shower tank 5, and furthermore, A water shower tank 5 and a main duct 2 are connected with a pipe. The water shower tank 5 utilizes the property of silane to dissolve in water to prevent silane from being discharged into the duct. The combustion tube 3 that burns toxic or explosive fluids is connected to line air 6 supplied from a factory line and cylinder air 7 piping for use in case of an emergency when the line air supply is stopped. The line air 6 piping includes a residual pressure sensor 8 with alarm, MV (air operated manifold valve) 9, pressure valve (RG) 10, and vacuum valve 11.
and the check valve 12 are arranged in sequence, and finally the flow meter F.
M13 and differential pressure valve P. Connect to H14. A flow meter 13 with an alarm controls the amount of fluid flowing into the combustion tube 3, and a differential pressure valve P with an alarm connected to the main duct 2 and the combustion tube 3 controls the amount of fluid flowing into the combustion tube 3. H14 plays the role of monitoring the difference in the pressure inside the two pipes.

Furthermore, a residual pressure sensor 15 with an alarm, a pressure valve 16, a pressure sensor 17 for low pressure, an MV and a check valve 19 are attached to the air piping supplied from the cylinder 7, and finally a differential pressure valve with an AL is installed. P. Connect to H14.

The dotted line connecting the residual pressure sensor 8 with an alarm installed in the line air 6 piping and the MV 18 of the air for the cylinder 7 is used to prepare for the situation where the supply of the line air 6 in the factory is stopped. This is a backup air system installed to back up the air for cylinder 7. In addition,
The FD attached to the vapor phase growth apparatus 1 is a damper corresponding to a safety valve against fire.

Further, nitrogen gas is supplied to the vapor phase growth apparatus 1 to prevent the possibility of explosion, and a flow meter 13' with an alarm is installed to control the supply amount.

As described above, since the combustion tube 3 attached to the conventional vapor growth apparatus 1 dilutes the fluid to be discharged, the fluid is discharged into the atmosphere from the main duct 2 after passing through the water shower tank 5. do.

Al-1 in FIG. 1 operates when the factory air stops or drops below the set pressure, and Al-2 operates when the factory air is stopped or the pressure drops below the set pressure.
Activates when the factory reserve air stops or drops below the set pressure. Al-3 monitors the differential pressure between the duct and the combustion cylinder, and activates when either is clogged. Al-4 activates when the pressure in the combustion cylinder becomes clogged. Operates when the air flow rate to be sent is below the set value, A
1-5 monitors the outer wall temperature of the combustion cylinder and operates when the temperature exceeds a set value, and Al-6 operates when a fire damper installed in the gas cylinder stocker is closed.

[0011]

Problems to be Solved by the Invention In a system surrounding such a vapor phase growth apparatus 1, 1. There is a risk that the silane gas discharged from the water shower tank 5 will react with oxides in the main duct 2 and cause combustion, resulting in a catastrophe; 2. Due to an operational error, raw silane was discharged and 1. It can also be assumed that combustion similar to that occurs. 3. When the nitrogen gas supply stops,
Silane and other substances may be emitted without dilution and burn, causing fire or explosion.

The method of the present invention was developed under these circumstances, and in particular, when an abnormal situation occurs, the silane gas discharged from the vapor growth apparatus is completely combusted in the combustion cylinder by the operation of a sensor. The purpose is to be able to monitor the data as well.

[Configuration of the invention]

[0014]

[Means for solving the problem] When a flammable fluid or a toxic fluid is forcibly burned in a combustion tube and discharged from a connected duct, together with combustion auxiliary fluid introduced from a flow velocity resistor that is integrally attached to the combustion tube. After burning flammable or toxic fluids,
The fluid combustion method according to the present invention is characterized in that the fluid is discharged into a duct via a water shower.

[0015]

[Operation] When the vapor phase growth device is operating normally, the silane gas is diluted and is not emitted, but in preparation for abnormal situations, special modifications are made to the combustion tube. That is, even if the supply of air from the factory line is stopped, the flow rate resistance component is installed integrally with the combustion cylinder to ensure smooth air supply, and since the amount and speed can be controlled, complete combustion can be expected. Therefore, the safety of a vapor phase growth apparatus that uses toxic or explosive fluids can be ensured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 2 to 4, which are given new numbers.

FIG. 2 shows a system diagram of the exhaust gas combustion system, FIGS. 3a and 3b show cross-sectional views of the flow resistance section installed in the combustion tube, and FIG. 4 shows a system diagram of the air unit. Further, the air backup system shown in FIG. 1 is also applied to the method of the present invention.

As is clear from the system diagram of the exhaust gas combustion system shown in FIG.
3, the exhaust gas from the water shower chamber 22 is guided to the main duct 24 and then discharged into the atmosphere, and a flow velocity resistance section 25 for auxiliary combustion fluid is installed at the entrance of the combustion tube 21. It is.

That is, for example, a stainless steel pipe 26 connecting the vapor growth device 20 and the combustion tube 21 is connected to the vapor growth device 20.
Exhaust pipes 27 made of stainless steel, for example, connected to the exhaust pipes 27 are arranged along the flow direction of the fluid, and the fluid discharged from the vapor growth apparatus 20 is introduced into the combustion tube 21. In addition, the stainless steel pipe 23 installed at the outlet of the combustion tube 21 has a flange 28.
Maintain airtightness.

A polycarbonate cylinder 29 is arranged at the end of a stainless steel pipe 23 connecting the water shower chamber 22 and the combustion cylinder 21, and a fluid such as silane is introduced through an introduction pipe 30. Further, the water shower room 22 is attached to a pedestal 31 and discharged to the duct 24 through a discharge pipe 32 installed at the upper stage of the water shower room 22 .

As shown in FIGS. 3a and 3b,
Flow velocity resistance part 2 for combustion assisting fluid attached to the inlet of the combustion tube 21
5 is installed between the combustion tube 21 and a reservoir 30 for, for example, air, that is, combustion-assisting fluid, supplied from an air unit to be described later. Then, a metal wool 32 made of, for example, stainless steel (similar to a metal scrubbing brush for kitchen use) is filled between the air partition plates 31 and 31 having countless holes, and further fixed together by a fixing part 33. The installation location is near the entrance of the combustion tube 21 and is formed around the pipe 26.

Since the filled metal wool 32 is thin and can be bent freely, there are voids 34 between each, as shown in the cross-sectional view of FIG. Since it reaches the open air partition plates 31, 31, the fluid can freely pass through. Another feature is that the conductance of the auxiliary combustion fluid can be adjusted by adjusting the packing density and length of the metal wool 32.

Next, a system diagram of an air unit incorporating an air backup system will be explained with reference to FIG. 4. The piping installed in the air tank 34 includes a valve 35 and a pressure gauge
, a valve 37, a filter/pressure gauge 38, and an MV 39 are installed.

On the other hand, a filter/pressure gauge 40, a joint 41, a valve 42, a pressure sensor 43 for low pressure, a check valve 44, and a joint 45 are installed in the piping from the line air. Then, MV39 connects to joint 41 and joint 45, and further connects joint 4 to joint 4.
5 is connected to the flow meter 46 and then to the combustion cylinder 21. Therefore, when the factory airline stops, air is automatically supplied from the air tank and flows into the combustion tube for a certain period of time, functioning as an airbag system. Note that Al-1 to Al-6 shown in FIG. 1 are also installed in the airline system according to the present invention and function in the same way, but are omitted from the drawing. The amount of auxiliary combustion fluid to be supplied to the exhaust gas combustion system having such a configuration was determined from the following formula based on experimental results.

Q=[SiH4 flow rate (100%)×2+NH3 flow rate (100%)×7/4]×air amount conversion 5×4 Further, the flow rate is adjusted to 0.15 m/s or less. As a result, the auxiliary combustion fluid flows from the reservoir 30 to the combustion tube 21 via the flow velocity resistance section 25.
After the silane introduced from the vapor growth apparatus 20 is burned, it is discharged from the duct 24 via the introduction pipe 30, the water shower chamber 22, and the discharge pipe 32.

[0026] Since the amount of oxides generated by this combustion method is extremely small, there is almost no risk of accidents in the duct.
Even if it cannot be removed in the shower room, it will be collected by a scrubber installed in the factory.

[0027]

As described above, the method of the present invention greatly contributes to safety measures for plants, such as explosive or toxic silane gas.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a conventional silane gas treatment system.

FIG. 2 is a system diagram showing main parts of the exhaust gas combustion system according to the present invention.

FIG. 3 is a sectional view showing an enlarged main part in the system diagram of FIG. 2; FIG. 3a is an enlarged vertical cross-sectional view of a flow velocity resistance portion of combustion assisting fluid. FIG. 3b is a longitudinal cross-sectional view of the combustion assisting fluid flow rate resistance section with a different cutting direction from FIG. 3a.

FIG. 4 is a system diagram of an auxiliary combustion fluid system in the method of the present invention.

[Explanation of symbols]

20: Vapor phase growth device, 21: Combustion cylinder, 22: Shower room, 24: Duct, 25: Combustion aid fluid flow velocity resistance part 32: Metal wool.

Claims (1)

[Claims] Claim 1: When a flammable fluid or a toxic fluid is forcibly burnt in a combustion tube and then discharged from a connected duct, the combustible fluid or a A method of burning a fluid, which is characterized in that after the toxic fluid is combusted, it is discharged into a duct through a water shower.