JPH0118152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a gas introduction method for introducing a minute flow rate of gas into a reduced pressure container in semiconductor manufacturing equipment or the like with good high-speed response.

[Prior art] In the conventional gas introduction method, a minute flow rate of gas is introduced into the fourth
The introduction into the reaction vessel 1 under reduced pressure was controlled using the configuration shown in the figure. The details will be explained below.

In FIG. 4, the reaction vessel 1 is evacuated by the exhaust pump 3 via the exhaust valve 2 and is in a reduced pressure state. The gas is introduced into a flow rate controller 11 via an inlet valve 10, and is controlled to a predetermined flow rate by a flow rate control valve 12 provided in the flow rate controller 11,
It is introduced into the reaction vessel 1 via the outlet valve 13.

Control for introducing or stopping the introduction of gas into the reaction vessel 1 is performed by the outlet valve 13 and the inlet valve 1.
This is done by opening and closing 0 or by adjusting the flow rate passing through the flow rate control valve 12 to a predetermined value or zero.

Further, as shown using the dotted line in FIG. 4, by introducing the carrier gas into the gas flow path via the carrier gas introduction valve 31, the flow rate is increased and the gas is introduced into the reaction vessel 1. Efforts were made to improve response.

[Problem that the invention seeks to solve]

However, the conventional introduction control for introducing or stopping the introduction of gas into the reaction vessel 1 using the configuration shown in FIG. Since the flow rate passing through the valve 12 was set at a predetermined value and zero, the temporal change in the flow rate of the gas introduced into the reaction vessel 1 had a characteristic as shown in FIG. That is,
As shown using solid lines, the outlet valve 13 and the inlet valve 1
0 is in the open state or the flow rate of gas passing through the flow rate control valve 12 is set to a predetermined flow rate value and gas is introduced into the reaction vessel 1 (in the figure), and then the stable predetermined gas shown in the figure is set. A time Δt ₁ was required before a flow rate could be introduced into the reaction vessel 1.
Time Δt ₃ in the figure indicates the time during which the gas is introduced into the reaction vessel 1 for a predetermined period of time. Then, after closing the outlet valve 13 or the inlet valve 10 or setting the gas flow rate passing through the flow rate control valve 12 to zero to stop the introduction of gas (as shown in the figure), the gas flow rate shown in the figure is adjusted. It took time Δt ₂ for it to become zero. The time Δt ₁ until the gas flow rate stabilizes at the beginning of introduction, and the time Δt ₂ until the gas introduction stops are determined by the characteristics of the flow rate controller 11,
1, the internal volume of the piping, and the set flow rate, etc., but especially when the flow rate to be controlled is minute, the times Δt ₁ and Δt ₂ are smaller than the apparent flow rate control time Δt ₃ . This caused the problem that it became too large to be ignored, and that it was not possible to control the introduction of a minute flow rate of gas at high speed.

Furthermore, a configuration is adopted in which a carrier gas introduction valve 31 shown using the dotted line in FIG. Attempts are being made to quickly control the introduction of As a result, as shown by the dotted line in Figure 5, it is possible to slightly reduce the time Δt ₂ ' from when gas introduction starts (in the figure) until the flow rate reaches a stable state. There was a problem in that it could not be made sufficiently small and that so-called overshooting and hunting of the gas flow rate occurred at the beginning of gas introduction, making it impossible to introduce and stop a predetermined flow rate at high speed.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas introduction method that rapidly introduces and stops gas at a small flow rate without depending on the characteristics of a flow rate controller, the internal volume of piping, etc., and the set flow rate.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a first
As shown in the figure, there is an outlet valve A13 for introducing the gas whose flow rate is controlled by the flow rate controller 11 into the depressurized reaction vessel 1, and a carrier gas for introducing the carrier gas into the connecting portion between the flow rate controller 11 and the outlet valve A13. Inlet valve 20, flow rate controller 11 and outlet valve A13
an outlet valve B14 for exhausting the gas introduced into the connection part with the carrier gas; and this outlet valve B14.
A throttle valve B15 is provided to control the flow rate of the exhaust gas exhausted by the reaction vessel 1. When introducing gas into the reaction vessel 1, first, the outlet valve A13 is closed and the outlet valve B1 is closed.
4 is opened at least, the gas introduced from the flow rate controller 11 is exhausted using the outlet valve B14 and the throttle valve B15, and the outlet valve A1 is opened.
The pressure at the inlet of No. 3 is set to a predetermined value P, and secondly,
Gas is introduced into the reaction vessel 1 by opening the outlet valve A13 and closing the outlet valve B14.

[Effect]

Adopting the configuration shown in FIG. 1, first, the flow rate control valve 12 is used to set the gas flow rate to a predetermined value, the outlet valve A13 is closed, the outlet valve B14 is opened,
Then, open the carrier gas introduction valve 20, adjust the throttle valve B15, and set the pressure at the inlet of the outlet valve A13 to a predetermined value P (outlet valve A13 and outlet valve B14).
The exhaust pump B16 is used to evacuate the air so that it is set to a value that does not change when the pump is opened and closed alternately.

Next, the outlet valve A13 is opened and the outlet valve B14 is closed, and the gas controlled at a predetermined flow rate by the flow rate control valve 12 is introduced into the reaction vessel 1 through the outlet valve A13. The subsequent control of introducing and stopping the gas into the reaction vessel 1 is performed using the outlet valve A13 and the outlet valve B1.
4 alternately open and close.

As described above, the outlet valve B14 and the throttle valve B15
By adopting a configuration in which a bypass flow path is provided using the exhaust pump B16 and the outlet valve A13 and the outlet valve B14 are alternately opened and closed to switch the gas flow path, the structure of the flow rate controller 11 is not affected. This makes it possible to control the introduction and stop of gas at minute flow rates with good high-speed response.

〔Example〕

Next, using FIG. 1 and FIG.
The configuration and operation of the embodiment will be explained in detail.

In FIG. 1, a reaction vessel 1 is evacuated by an exhaust pump A3 through an exhaust valve 2 and is in a reduced pressure state. Gas is introduced into the reaction vessel 1 via the inlet valve 10, the flow control valve 12 constituting the flow controller 11, and the outlet valve A13. A carrier gas is introduced into the inlet portion of the outlet valve A13 via a carrier gas introduction valve 20, and is exhausted to a predetermined pressure P by an exhaust pump B16 via an outlet valve B14 and a throttle valve B15. These outlet valves B
14, Throttle valve B15 and exhaust pump B16
constitutes a bypass flow path, and the outlet valve A13
By alternately opening and closing the outlet valve B14 and the outlet valve B14, the gas flow path can be switched.

Next, the operation of the configuration shown in FIG. 1 will be explained in detail using FIG. 2. The horizontal axis in Figure 2 shows time;
The vertical axis indicates the gas flow rate f introduced by the flow control valve 12. The dotted line curves and in the figure represent the introduction characteristics in the preparation before introducing the gas into the reaction vessel 1, and the solid line curves in the figure represent the introduction stop characteristics when introducing the gas into the reaction vessel 1.

In the figure, the outlet valve B14 is opened, the outlet valve A13 is closed, the carrier gas introduction valve 20 is opened, the inlet valve 10 is opened, and the flow rate control valve 12 is set to a predetermined flow rate.
A state in which exhaust is started using the exhaust pump B16 is shown. Note that there is a slight delay between opening and closing each valve and the like until the air is exhausted as shown in the figure, but this is omitted here for the sake of explanation.

In the figure, exhaust pump B16, throttle valve B15,
This shows a state in which the gas in each valve and the pipe is exhausted through a bypass flow path constituted by the outlet valve A14 and the outlet valve A14, and the pressure at the inlet of the outlet valve A13 is stably set to a predetermined value P. This is the outlet valve A
13 and outlet valve B14 are alternately opened and closed to introduce gas whose flow rate is controlled by the flow rate control valve 12 into the reaction vessel 1, or to exhaust the gas through the bypass channel. This means that the throttle valve B15 is adjusted and set to a predetermined pressure P in order to prevent the pressure at the inlet portion of the outlet valve A13 from fluctuating. In detail,
The pressure P at the inlet of the outlet valve A13, which is exhausted by the flow path consisting of the outlet valve A13, the reaction vessel 1, the exhaust valve 2, and the exhaust pump A3, and the outlet valve B
14, throttle valve B15, and exhaust pump B16
For example, the throttle valve B15 is adjusted so that the pressure P at the inlet of the outlet valve A13, which is exhausted by the bypass flow path consisting of It is determined depending on the exhaust characteristics of exhaust pumps A and B. In the figure, Δ _i represents the time from the start of gas introduction until a predetermined flow rate of gas is stably introduced into the inlet portion of the outlet valve A13.

As described above, the pressure P at the inlet of the outlet valve A13 is stably maintained at a predetermined value, and a predetermined flow rate of gas set by the flow rate control valve 12 is supplied to the bypass flow path (outlet valve B14, throttle valve B15). The gas is then evacuated via the exhaust pump B16), and preparations for opening the outlet valve A13 and introducing the gas into the reaction vessel 1 are completed.

Next, the characteristics of stopping the introduction of gas into the reaction vessel 1 will be explained.

In Fig. 2, outlet valve A13 is opened and outlet valve B is opened.
14 is closed, and the gas and carrier gas flowing in the bypass flow path are switched to the flow path consisting of the outlet valve A13, the reaction vessel 1, the exhaust valve 2, and the exhaust pump A3.

The figure shows a state in which a predetermined flow rate of gas is introduced into the reaction vessel 1 in a stable state. The time Δt ₁ required for gas to be introduced into the reaction vessel 1 under this stable state is extremely short compared to the conventional time Δt ₁ shown in FIG. 5. This means that in this embodiment, the gas flowing through the outlet valve B14 is transferred to the outlet valve A1.
Since the gas is controlled to be introduced into the reaction vessel 1 by simply switching the gas flow path so that the gas flows through the reaction vessel 1, delays in gas introduction, overshooting, hunting, etc. (as shown in the figure) This is because the characteristic curve shown by the dotted line shown in the figure is prevented from occurring. Note that Δt ₃ in the figure represents the time during which the gas is stably introduced into the reaction vessel 1.

In the figure, outlet valve A13 is closed and outlet valve B is closed.
14 is opened, the gas flow path is switched to the bypass flow path, and the introduction of gas into the reaction vessel 1 is stopped.

The figure shows a state in which the flow rate of gas introduced into the reaction vessel 1 has become zero. In the figure, time Δt ₂ indicates the time from when gas introduction is started to when gas introduction is stopped.

As described above, the outlet valve A13 and the outlet valve B1
4 is alternately opened and closed, and the gas and carrier gas introduced into the inlet of the outlet valve A13 are controlled to be alternately switched to the bypass flow path and the flow path containing the reaction vessel 1, thereby controlling a minute flow rate of gas. It becomes possible to introduce and stop the reaction in a stable state in the reduced pressure reaction vessel 1 with good high-speed response.

Next, the configuration and operation of another embodiment will be explained using FIG. The configuration shown in FIG. 3 is in addition to the configuration shown in FIG. 1 in that a predetermined flow rate of carrier gas is introduced into the outlet portion of the outlet valve A13 through the throttle valve A21. Other gas introduction and stop controls are almost the same as those shown in FIG. 1, so explanations will be omitted. The pressure _P1 at the inlet of the outlet valve A13 may be set to a predetermined value by controlling the amount of carrier gas introduced using the throttle valve A21, or by controlling the amount of carrier gas introduced by the throttle valve B15 and the throttle valve B15. This may be done using the throttle valve A21.

By introducing the carrier gas to the outlet side of the outlet valve A13 in this way, the velocity of gas particles in the flow path between the outlet valve A13 and the reaction vessel 1 is increased, and the responsiveness of introducing the gas into the reaction vessel 1 is increased. In addition to improving the response, even if the outlet valve A13 is closed, the carrier gas is introduced through the throttle valve A21, so the gas adsorbed on the outlet valve A13 and piping can be quickly removed by the carrier gas. It becomes possible to purge to

From the above, it becomes possible to further shorten the time Δt ₁ required to introduce the gas at a stable flow rate and the time Δt ₂ required to stop the introduction of the gas. In particular, the outlet valve A13 and the reaction vessel 1
This is effective when the length of piping between the

In addition, in Fig. 1 and Fig. 3, exhaust pump A3
and exhaust pump B16, but the exhaust pump B16 is omitted and exhaust valve 2 and outlet valve B are used instead of exhaust pump A3.
14 may be switched for control. Further, in this embodiment, for example, hexagonal tungsten gas is used as the gas, and an inert gas such as helium gas is used as the carrier gas.

〔Effect of the invention〕

As explained above, according to the present invention, by setting the pressure P at the inlet of the outlet valve A13 to a predetermined value and switching the gas flow path by alternately opening and closing the outlet valve A13 and the outlet valve B14, Gas to reaction vessel 1
Since the flow rate controller 1 is controlled to be introduced into
A small flow rate of gas can be introduced into the reaction vessel 1 with good high-speed response without being affected by the structure and characteristics of the reaction vessel 1.
Can be stopped.

[Brief explanation of drawings]

Fig. 1 is a block diagram of one embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of the configuration shown in Fig. 1, Fig. 3 is a block diagram of another embodiment of the present invention, and Fig. 4 is a conventional introduction method. FIG. 5 is an explanatory diagram of the operation of the configuration shown in FIG. 4. In the figure, 1 is a reaction vessel, 2 is an exhaust valve, 3 and 16 are exhaust pumps, 10 is an inlet valve, 11 is a flow rate controller,
12 is a flow control valve, 13, 14...outlet valve, 15,
21 represents a throttle valve, and 20 represents a carrier gas introduction valve.

Claims (1)

[Claims] 1. A gas introduction method for introducing a predetermined flow rate of gas into a reduced pressure reaction vessel, comprising: a flow rate controller that controls the flow rate of the gas to be introduced; and a flow rate controlled by the flow rate controller. An outlet valve A that introduces the carrier gas into the depressurized reaction vessel, a carrier gas introduction valve that introduces the carrier gas into the connection between the flow rate controller and the outlet valve A, and a carrier gas introduction valve that introduces the carrier gas into the connection between the flow rate controller and the outlet valve A. Outlet valve B for exhausting gas and carrier gas
and a throttle valve B for controlling the flow rate of the exhaust gas exhausted through this outlet valve B, and when introducing gas into the reaction vessel, first, the outlet valve A is closed and the outlet valve B is at least opened. ,
The gas introduced from the flow rate controller is exhausted using the outlet valve B and the throttle valve B, and the pressure at the inlet of the outlet valve A is set to a predetermined value.
A gas introduction method characterized in that the gas is controlled to be introduced into a reaction vessel by opening an outlet valve B and closing an outlet valve B.