JPS63118073A - Gaseous reactant purging system - Google Patents

Abstract

PURPOSE:To easily purge a gaseous reactant and to improve the through-put by connecting a residual gas exhaust pipe connected to an exhaust pump to a gaseous reactant supply pipe before the connecting valve between a reaction furnace and a gaseous reactant charge pipe. CONSTITUTION:The gaseous reactants are supplied from N2, SiH4, N2O, CF4, and O2 supply sources 21, 31, 51, 61, and 71, and treatment such as CVD and dry etching is carried out in the reaction furnace 1. In such a vapor-phase reactor, the residual SiH4, N2O, CF4, etc., which are unfavorably left are purged after reaction respectively from gas supply pipes 30, 50 and 60. In this case, the valve 32, etc., between the gas supply pipes 30, etc., and the gas charge pipes 10 and 40 to the reaction furnace 1 are closed, and the insides of the gas supply pipe 30, etc., are evacuated by the exhaust pump 2 through the residual gas exhaust pipe 34, etc., connected before the valve 32, etc., and the residual gases are purged. An air bellows valve 35, etc., are closed until the reaction is resumed, and the vacuum in the pipes is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a reactive gas purging system. More specifically, the present invention relates to a reactive gas purge system that is modular in construction and capable of directing throughput.

[Prior Art] One of the methods widely used in the semiconductor industry for forming thin films is chemical vapor deposition (CVD).
Chemical Vapor Depos it
1on). CV I) refers to turning a gaseous substance into a solid substance through a chemical reaction and depositing it on a substrate.

Characteristics of CVD are that various thin films can be obtained at deposition temperatures considerably lower than the melting point of the thin film to be grown;
The electrical properties are stable even when the grown thin film has a high purity of Si or 5iL- thermal oxide film.
Widely used as a passivation film on the surface of conductors.

Thin film formation by CVD is performed by supplying a reactive gas (for example, SiH4+02. or SiH4+N20) to a wafer heated to, for example, about 500'C. l・
The reaction gas described above is blown onto the wafer in the reactor to form a thin film of 5i02 on the surface of the wafer.

Historically, gases such as CFq have been used to etch unnecessary portions of the oxide film to obtain a desired pattern, and to remove foreign matter adhering to the interior surface of the reactor.

[Problems to be Solved by the Invention] FIG. 2 shows a flow sheet of a gas supply system of a conventional gas phase reactor that performs processes such as [Problems to be Solved by the Invention] and dry etching.

As shown in Figure 2, in the conventional apparatus, after the reaction is completed,
Existing gases such as S i H41N 20 and CFq were diluted with N2 gas to make them safe before being discharged.

For example, from the N2 gas supply pipe 100 to the branch pipe 11
2 extends, and a diluted N2 gas mixing pipe 114 is further connected to a SiH4 supply pipe 120 from this branch pipe. The diluted N2 gas mixing vibe 114 is a reverse market valve CV 10
2 and air bellows valve K V 105.

In addition, the S r H4 supply pipe 120 has an air bellows valve A V 106 at the connection point with the diluted N2 gas mixing vibe 114, and a filter F2 at the end of the connection point.
, a mass flow controller MFC2 and an air bellows valve A V +04. SiH4 supply pipe 1
20 is connected to the first reaction gas feed pipe 150 at the end of this air bellows valve A V 104. Then, the exhaust pipe 1 is connected to the pipe section between the mass flow controller MFC2 and the air bellows valve A V +04.
16 branches. The exhaust pipe 116 carries an air bellows valve AV103 and a reverse j1 valve CVIOI.

After the reaction is completed, use the air bellows valve AV+06.
Close and turn off the supply of SiH4 to 11. The SiH4 remaining in the pipe 120 is removed by the diluted N2 gas mixing vibrator 11.
It is diluted with N2 gas sent from 4, and discharged from pipe 1.
16, or υE is discharged from the first reaction gas feed pipe 150 through the reactor 200.

However, in this case, N2 gas will always remain in the S i H4 supply pipe 120. Therefore, when starting the next reaction process, this residual N2 gas and SiH
4 was sent to the reactor 200 in a mixed state, and it took a long time until the flow rate of the d-flavor gas of S i H4 was stabilized.

In addition, if υ[ is discharged via a reactor, an excessive amount of time will be required for the discharge operation. As a result, the throughput of the entire iF conductor element manufacturing process is reduced.

These problems are caused by the pipe 130 for supplying N20.
The same applies to the pipe 140 for supplying CFq.

[Objective of the Invention] Therefore, the first object of the present invention is to purge the reaction gas in the supply pipe without mixing N2 gas into the reaction gas supply pipe such as 5i84 (and without passing it through the reactor). The goal is to provide the following.

[Means for Solving the Problems] As a means for solving the above-mentioned problems and achieving the objects of the present invention, the present invention provides a method for supplying a reaction gas to a reactor of a gas phase reactor. Each reaction gas supply pipe is connected to the pipe through a valve, and for the supply pipe of a gas that is undesirable to remain in the supply pipe, a residual gas discharge pipe is connected in front of the valve. The present invention provides a reaction gas purge system characterized in that this pipe is connected to an exhaust pump.

[Function] As mentioned above, in the reaction gas blow system of the present invention,
A residual gas υ [output pipe] is connected as a bypass from before this valve to a reaction gas supply pipe connected to the reaction gas inlet pipe via a valve, and the end of this υ1 output pipe is connected to an exhaust pump.

Thus, when the reaction process is completed, the valve at the connection point between the reaction gas inlet pipe and the reaction gas supply pipe is closed, and the exhaust pump is driven to eliminate the residual gas in the reaction gas supply pipe. The gas is transferred to the FJ without passing through the reactor.
It is expelled extremely quickly from the pipe via the r-exiting vibrator.

This discharge pipe is also provided with a valve, and by closing this valve after completion of discharge, the interior of the reaction gas supply pipe can be maintained in a vacuum state. Therefore, when starting the next reaction process, a predetermined gas flow rate of the reaction gas can be immediately sent to the reactor by opening the valve at the connection point.

As a result, throughput can be improved, and since there is no need to dilute with N2 gas, the overall configuration of the purge system is simple, leading to cost reduction.

[See the drawings below for examples! ! ((L) An embodiment of the reactive gas purge system of the present invention will be described in detail.

FIG. 1 is a flow sheet showing an example of the reaction gas purge system of the present invention.

As shown in FIG. 1, the reaction gas supply vibe 10 includes an N2 gas supply pipe 20 and a SiH4 gas supply pipe 30.
is connected to the reaction gas feed vibe 40, and an N20 gas supply pipe 50. cr;', gas supply vibro 0 and 02 gas supply pipes 70 are connected.

The reactant gas excessive pipe 10 has an on-off valve 12 and a filter 1.
It is connected to the reactor 1 via 4.

Similarly, the reactant gas oversized pipe 40 is connected to the reactor 1 via an on-off valve 42 and a filter 44.

The N2 gas supply pipe 20 is connected to an N2 gas supply pipe 21, and is connected to the reaction gas excess pipe 10 via an air bellows valve 22.

The SiH4 gas supply pipe 30 similarly has a supply source 31 and is connected to the reaction gas excess pipe 10 via an air bellows valve 32.

N20 gas supply pipe 50 + CF4 gas supply Vibro 0 and 02 gas supply pipe 70 also has supply sources 51, 61 and 71 respectively, and air bellows valve 52
．． It is connected to the reaction gas overflow pipe 40 via E32 and 72, respectively.

The gas supply pipes 20, 30, 50, 60 and 70 are each equipped with a mass flow controller 23, 33, 53 in the middle.
．． I hear 63 and 73.

The SiH4 gas supply pipe 30 is an air bellows valve 32
A residual gas discharge pipe 34 is connected between the mass flow controller 33 and the mass flow controller 33 . Similarly, a discharge pipe 54 is connected to the N20 gas supply pipe 50, and a discharge vibro 4 is connected to the CFqF gas supply vibro 0. These outlet pipes are merged into a discharge pipe 80, and this discharge pipe 8
0 is connected to the exhaust pump 2. This exhaust pump 2
Since υ of the reactor can also be used as a gas phase, an air bellows valve 4 is installed in the middle of the exhaust pipe 3 that connects the pump 2 and the reactor 1, and the υF delivery pipe 80 is connected to the air bellows valve 4. and the pump 2 are connected to the vibrator 3.

The exhaust pipe 34 has air bellows valves 35 and 2 and a reverse 11-valve 36. Similarly, the discharge pipes 54 and 64 are connected to the air bellows valves 55 and 65 and the reverse 11-valve 5.
6 and 6G.

Next, the specific operation of the reaction gas purge system of the present invention will be explained.

When the reaction process in the reactor is completed, first, the valve on the supply source side is closed to stop the gas supply.

If SiH4, N20 or CFqF gas is used, the valve on the connection point side is also closed at the same time.

Then, open the valve of the bypass outlet pipe and drive the exhaust pump. Since both the valves on the source side and the connection point side are closed, the residual gas in the pipes between them is exhausted by the exhaust pump via the exhaust pipe of this bypass. The valve 4 of the reactor exhaust pipe 3 can also be kept closed to facilitate the evacuation of residual gas.

Since the reactor and the supply pipe can be shut off or communicated by opening and closing the valves of each reaction gas supply pipe, unless there is a special case, the on-off valves 12 and 42 of the reaction gas supply pipe are normally closed. It is preferable to keep it in a time state. If the residual gas in the reactor needs to be diluted or replaced with N2 gas, the valve 22 of the N2 gas supply pipe can also be opened.

In order to prevent foreign matter from entering the reactor, it is preferable to provide filters (Fl to F5) between the mass flow controller of each reaction gas supply pipe and the supply source.

When using a toxic reactive gas other than those mentioned above, it is sufficient to simply add a supply pipe for that gas as shown in the diagram.

Regarding the supply pipes for N2 gas and 02 gas, pressure switches Psi and PS2 and reverse +L valve CV1.
It is also possible to arrange CV2 respectively. Furthermore, the gas control section can also be provided with a manifold solenoid valve connected to an air supply source. A pressure switch PS3 can also be provided here.

The reaction gas purge system of this invention can be controlled manually or sequentially. The ancillary equipment necessary for sequential control (eg, mass flow controller power supply, relay, pressure level indicator, noise filter, etc.) is well known to those skilled in the art.

[Effects of the Invention] As explained above, in the reactive gas purge system of the present invention, a residual gas exhaust pipe is connected to the reactive gas supply pipe connected to the reactive gas feed pipe via the valve as a bypass from the hand 1n of this valve. and connect the end of this exhaust pipe to the exhaust pump.

Thus, when the reaction process is completed, by closing the valve at the connection point between the reaction gas feed pipe and the reaction gas supply pipe and driving the exhaust pump, the gas remaining in the reaction gas supply pipe can be removed. It is extremely quickly discharged from the pipe through the discharge pipe without passing through the reactor.

This discharge pipe is also provided with a valve, and by closing this valve after completion of discharge, the interior of the reaction gas supply pipe can be maintained in a vacuum state. Therefore, when starting the next reaction process, by opening the valve at the connection point, a predetermined gas flow rate of the reaction gas can be immediately sent to the reactor, and the desired reaction process can be started quickly.

As a result, the throughput can be greatly improved, and since there is no need to dilute with NN2 gas, the entire purge system has a non-pure configuration, leading to cost reduction. In particular, compared to conventional systems, one valve for each discharge pipe can be omitted, the piping for that purpose can also be omitted, and the opening and closing operations of the valves can also be simplified.

The reaction gas purge system of the present invention is particularly preferably used for plasma or low pressure CVD thin film forming apparatuses in which the reactor itself is equipped with a powerful exhaust pump. others,
Naturally, it can also be used in gas phase reactors such as atmospheric pressure CVI) and dry enching.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing an example of the reaction gas purge/stylus of the present invention, and FIG. 2 is a flow sheet showing an example of a conventional reaction gas purge system. DESCRIPTION OF SYMBOLS 1...Reactor, 2...Exhaust pump, 3...Reactor exhaust pipe, 4...Valve, 10 and 40...Reaction gas feed pipe, 20...N2 gas supply pipe. 30...SiH4 gas supply pipe, 34.54 and 64...residual gas υ1 output pipe, 50...N20 gas supply pipe, 60...CFQ gas supply pipe.

Claims (3)

[Claims] (1) Each reaction gas supply pipe is connected via a valve to the pipe that feeds the reaction gas to the reactor of the gas phase reactor, and among these reaction gases, it is undesirable to remain in the supply pipe. A reaction gas purge system characterized in that the supply pipe is connected to a residual gas exhaust pipe before the valve, and this pipe is connected to an exhaust pump. (2) The reaction gas purge system according to claim 1, wherein the residual gas discharge pipe has a check valve and an air bellows valve. (3) The exhaust pump is also connected to the reactor via a valve, and the residual gas exhaust pipe is connected to the pump between this pump and the valve. Reactive gas purge system as described.