JP2972313B2 - Steam supply method and steam supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a steam supply method and a steam supply device, wherein the temperature of a piping system including piping other than water, a valve, and a mass flow controller is not significantly higher than the temperature of water in a water tank, and the mass flow is not increased. It is an object of the present invention to provide a steam supply method and a steam supply device capable of stably supplying steam without causing steam clogging in a controller, from a sealed water tank containing water to a vacuum vessel through a mass flow controller. When the steam is introduced and the pressure is reduced, the temperature of the water in the water tank, the temperature of the piping from the water tank to the mass flow controller, the temperature of the piping from the mass flow controller to the vacuum vessel, and the temperature of the mass flow controller are independently controlled. Control and the water temperature Tt in the water tank, and And conduit temperature Tp to the vacuum vessel from said mass flow controller and to the flow controller, the mass flow controller of the temperature Tm and the Tt ≦ Tp
≤ Tm.

[Industrial applications]

TECHNICAL FIELD The present invention relates to a steam supply method and a steam supply apparatus capable of flowing steam stably and with good control when processing a workpiece using steam in a vacuum or reduced pressure.

The steam supply device supplies steam to a vacuum vessel from a sealed water tank containing water through a mass flow controller.

In recent years, water vapor has been stabilized without causing the temperature of the piping system other than the water tank, piping, valves and mass flow controller to be significantly higher than the water temperature of the water tank water, and without causing steam clogging in the mass flow controller. There is a demand for a steam supply method and a steam supply apparatus that can supply the steam to the water.

[Conventional technology]

Conventionally, the method of supplying water vapor to a vacuum system is a water tank,
One in which a pipe and a mass flow controller are arranged in a thermostat so as to uniformly control the temperature. However, this method has a problem that the thermostat itself becomes very large, the cost is extremely high, and the temperature control is difficult.

Another conventional technique to solve this problem is to control the water temperature of the water tank to control the amount of steam evaporation,
There is a method in which the temperature is raised to such an extent that water vapor is not clogged by piping other than the water tank and the mass flow controller. Hereinafter, a specific description will be given with reference to the drawings.

FIG. 2 is a view for explaining a conventional steam supply method and a steam supply apparatus. The steam supply device shown in the figure is a low pressure CVD
Etc. can be applied. In FIG. 2, 31 is a water tank, 32a and 32b are temperature control means, 33a and 33b are valves, 34
Is a mass flow controller, 36 is a heater, and 37 is a vacuum vessel.

As shown in FIG. 2, the flow rate of the water tank 31 here is determined by the amount of water vapor (the amount of evaporation of water). In order to secure the amount of water vapor, the water tank 31 is double-bathed by the temperature control means 32a. The temperature is controlled by the method. Since the water vapor pressure curve is steeper than that of TEOS or the like, the temperature control means 32a
It is preferable that the temperature control of the water tank 31 is performed precisely.

And piping systems other than the water tank 31, piping 35, valve 33
a, 33b and the mass flow controller 34 are provided with a tubular heater 36 and a temperature control means 32b so that steam is not clogged.
Was raising the temperature. The heater 36 is provided so as to cover all of the pipe 35, the valves 33a and 33b, and the mass flow controller 34, and the temperature control means 32b is provided, for example, in the mass flow controller 34 so as to control the temperature of the pipe 35 covering these. Was.

[Problems to be solved by the invention]

As shown in FIG. 2, the above-described conventional steam supply device includes a piping system other than the water tank 31, a piping 35, valves 33a and 33b.
Further, the entire mass flow controller 34 is covered with the heater 36, and the temperature is controlled by one temperature control means 32b. In this steam supply device, for example, the water temperature in the water tank 31 required to supply steam at a flow rate of 600 cc / min is 50
° C. In order to prevent water vapor from being clogged in the piping system including the piping 35, the valves 33a and 33b, and the mass flow controller 34, it was necessary to raise the temperature of the piping system to 60 ° C or higher by the heater 36 and the temperature control means 32b. .

In addition, to supply steam at a flow rate of 900 cc / min, the water temperature in the water tank 31 had to be 55 ° C. At this time, the required temperature of the piping system other than the water tank 31 was 80 ° C. .

However, to supply steam at a flow rate of 1100 cc / min, the water temperature in the water tank 31 had to be 60 ° C. At this time, even if the temperature of the piping system other than the water tank 31 was 90 ° C, the mass flow There is a problem that water vapor is clogged at the controller 34. In this conventional steam supply device, due to the structure and heat capacity of the mass flow controller 34, the inner wall temperature of the steam passage portion of the mass flow controller 34 is slightly lower than the inner wall temperatures of the pipes before and after it, and as a result, dew condensation occurs. It is likely that it has occurred.

As described above, when it is desired to supply a large amount of steam having a flow rate of 1100 cc / min, the amount of evaporation of the steam from the water tank 31 increases exponentially. , Just increase the area of the water surface. However, there is a problem that the temperature of the piping system needs to be considerably high in order to prevent the steam from clogging in the piping system other than the water tank 31. In particular, when heating to 100 ° C. or higher, it becomes difficult to use resin as a piping material in terms of heat resistance. For this reason, it is conceivable to use metal instead of resin for the piping material.However, it is difficult to use metal because metal is generally eroded by steam and causes metal contamination when used in the manufacture of semiconductor devices. there were.

Therefore, the present invention does not raise the temperature of the piping system other than the water tank, the piping and the valve and the mass flow controller significantly higher than the water temperature in the water tank, and does not cause clogging of steam in the mass flow controller. It is an object of the present invention to provide a steam supply method and a steam supply device that can supply steam stably.

[Means for solving the problem]

The steam supply method according to the present invention achieves the above object,
When introducing steam from a closed water tank into a vacuum vessel through a mass flow controller and performing vacuum treatment,
The temperature of the water in the water tank, the temperature of the piping from the water tank to the mass flow controller, the temperature of the piping from the mass flow controller to the vacuum vessel, and the temperature of the mass flow controller are independently controlled, and the temperature in the water tank is controlled. water temperature
Tt, pipe temperature from the water tank to the mass flow controller and from the mass flow controller to the vacuum vessel
Tp and the temperature Tm of the mass flow controller, Tt ≦ Tp ≦ Tm
It is assumed that.

The steam supply device according to the present invention achieves the above object,
In a water vapor supply device for supplying water vapor from a sealed water tank to a vacuum vessel through a mass flow controller, a water tank having a temperature control means, a mass flow controller having a heater and a temperature control means, A pipe having a heater and a temperature control means from the mass flow controller to the vacuum vessel is provided to the controller, and the temperature of the water tank, the mass flow controller and the pipe can be independently controlled.

Vacuum container according to the present invention for reduced pressure CVD, for reduced pressure oxidation,
Vacuum containers for plasma generation (CVD, etching) and the like can be mentioned.

[Action]

The mass flow controller having the largest heat capacity in the steam supply device is the orifice portion in the mass flow controller where the narrowest passage of the steam passes. Therefore, the steam is most likely to be clogged in the orifice portion. The reason why the steam is easily clogged in the orifice portion in the mass flow controller is that a pressure difference is generated between the upstream and the downstream in the orifice portion, adiabatic expansion occurs, the temperature decreases, and the steam is easily liquefied. For this reason, only the orifice portion of the mass flow controller needs to be heated to the highest temperature in order to prevent the clogging of water vapor. For this reason, in the present invention, the water temperature Tt in the water tank, the pipe temperature Tp from the water tank to the mass flow controller and from the mass flow controller to the vacuum vessel, and the temperature Tm of the mass flow controller are represented by Tt ≦ Tp ≦ Tm and the conductance of each part is represented by The temperature was increased in ascending order.

Therefore, a temperature drop due to adiabatic expansion at the orifice portion in the mass flow controller is unlikely to occur, and it becomes difficult for water vapor to liquefy.

〔Example〕

 Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 is a view for explaining an embodiment of a steam supply method and a steam supply apparatus according to the present invention. The steam supply device in the illustrated example can be applied to reduced pressure CVD or the like. In FIG. 1, 1 is a closed water tank containing water, 2a, 2b, 2c.
Is a temperature control means, 3a and 3b are valves, 4 is a mass flow controller, 5 is a pipe, 6a, 6b and 6c are heaters, and 7 is a vacuum vessel.

As shown in FIG. 1, the steam supply device of the present embodiment supplies steam from a sealed water tank 1 to a vacuum vessel 7 through a mass flow controller 4. Water tank 1 with 2a
A mass flow controller 4 having a heater 6b and a temperature control means 2b, and a pipe 5 having heaters 6a, 6c and a temperature control means 2c from the water tank 1 to the mass flow controller 4 and from the mass flow controller 4 to the vacuum vessel 7. The temperature of the water tank 1, the mass flow controller 4, and the pipe 5 can be independently controlled.

 Next, a method of supplying steam will be described.

First, the flow rate of the water tank 1 is determined by the amount of water vapor. In order to secure the amount of water vapor, the temperature of the water tank 1 is controlled by the temperature control means 2a in a double bath system. And
A piping system other than the water tank 1, a piping 5 from the water tank 1 to the mass flow controller 4 and a piping 5 from the mass flow controller 4 to the vacuum vessel 7 are provided with heaters 6 a covering the piping,
The temperature is controlled by the temperature controller 6b and the temperature controller 2c, and the temperature of the mass flow controller 4 is controlled by the heater 6b and the temperature controller 2b covering the mass flow controller 4.

Specifically, for example, the water temperature in the water tank 1 required to supply steam at a flow rate of 1100 cc / min to the vacuum vessel 7 is 60 ° C.
When the temperature of the pipe 5 was set at 60 ° C. and the temperature of the mass flow controller 4 was set at 80 ° C., the clogging of water vapor occurred in the mass flow controller 4 within 5 minutes in the conventional case. Thus, steam could be supplied stably at about 1000 cc / min for 1 hour or more without causing steam clogging. Moreover, when the temperature of the pipe 5 is 60
℃, the temperature of the mass flow controller 4 can be set to 80 ℃, the temperature of the water in the water tank 1 (60 ℃) does not need to be significantly higher than in the conventional case, without using metals such as fluororesin Can be used for piping materials.

〔The invention's effect〕

According to the present invention, the temperature of the piping system other than the water tank, the piping and the valve and the mass flow controller is not significantly increased as compared with the water temperature in the water tank, and without causing clogging of steam in the mass flow controller. There is an effect that steam can be supplied stably.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a steam supply method and a steam supply device according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating a conventional steam supply method and a steam supply device. DESCRIPTION OF SYMBOLS 1 ... Water tank, 2a, 2b, 2c ... Temperature control means, 3a, 3b ... Valve, 4 ... Mass flow controller, 5 ... Piping, 6a, 6b, 6c ... Heater, 7 ... Vacuum container.

Continued on the front page (72) Inventor Tatsuya Takeuchi 3-1-135 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Inside Shinko Seiki Co., Ltd. (72) Kamasa Nakano 3-1-135 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Shinko Seiki Co., Ltd. (72) Inventor Yuuji Matoba 3-1-1, Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Shinko Seiki Co., Ltd. (56) References JP-A-1-294868 (JP, A)

Claims (2)

(57) [Claims] When water vapor is introduced from a closed water tank (1) containing water into a vacuum vessel (7) through a mass flow controller (4) to perform a decompression process, the water temperature in the water tank (1) and the water temperature in the water tank (1) are reduced. The temperature of the pipe (5) from the water tank (1) to the mass flow controller (4), the pipe (5) from the mass flow controller (4) to the vacuum vessel (7), and the temperature of the mass flow controller (4) are independently controlled. Controlling the water temperature Tt in the water tank (1) and the water tank (1)
From the mass flow controller (4) to the mass flow controller (4), the pipe temperature Tp from the mass flow controller (4) to the vacuum vessel (7), and the temperature Tm of the mass flow controller (4) by Tt.
A method for supplying steam, wherein ≤Tp≤Tm. 2. A steam supply device for supplying steam from a closed water tank (1) containing water to a vacuum vessel (7) through a mass flow controller (4), wherein the water tank (1) having a temperature control means (2a) is provided. ), A mass flow controller (4) having a heater (6b) and temperature control means (2b), from the water tank (1) to the mass flow controller (4), and from the mass flow controller (4) to the vacuum vessel (7). ) Having a heater (6a, 6c) and a temperature control means (2c). The water tank (1), the mass flow controller (4) and the pipe (5) are each independently temperature controlled. A steam supply device characterized in that it can be controlled.