JPS61257232A - Method for generating gaseous liquid material - Google Patents

Abstract

PURPOSE:To always obtain a stable amount of evaporation by cooling the gaseous liquid material generated by bubbling upto the temp. approaching nearly the saturated vapor pressure on the way of the conveyance. CONSTITUTION:The carrier gas controlled in a prescribed flow rate is flowed into a liquid material such as silicon tetrachloride which is stored in a bubbler tank 1 maintained at the prescribed temp. T1 and used for the production of a semiconductor or the like to perform the bubbling. The generated gaseous liquid material is introduced into a buffer tank preset at the temp. T2 wherein the gaseous material obtained on the basis of the bubbled amount of the carrier gas reaches the saturated vapor pressure and the temp. T1 and it is cooled nearly upto the saturated vapor pressure. The gas liquefied by the cooling is returned to the bubbler tank and the gaseous liquid material being preset in the saturated vapor pressure is conveyed to a semiconductor production apparatus side together with the carrier gas. Thereby the gaseous material of the required amount can be obtained with the less amount of the carrier gas to be bubbled by presetting the temp. of the liquid material close to b.p. and a stable amount to be evaporated can be obtained even when the various errors and fluctuations are caused.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention involves bubbling silicon tetrachloride, germanium tetrachloride, and other liquid (liquefied) materials used in the production of optical fibers, semiconductors, etc. This invention relates to a method of generating material gas.

"Prior Art" Conventionally, a liquid material gas generation device is already known that generates liquid material gas (steam) whose vapor pressure is controlled to a predetermined vapor pressure by bubbling carrier gas whose flow rate is controlled by a control device.

This type of configuration will be explained based on FIG. 2. Reference numeral 1 denotes a bubbler tank made of quartz glass, stainless steel, or other corrosion-resistant material, around which a rubber heater 2 is placed.
The liquid material in the tank 1 is heated and maintained at a predetermined temperature.

Reference numeral 3 denotes an inlet tube for a carrier gas made of nitrogen or other inert gas, the opening of which is positioned in the liquid material in the bubbler tank l, and a carrier gas flow rate control valve 4 is interposed in the middle of the inlet tube 3. , the flow rate of the liquid material gas is controlled by controlling the flow rate of the carrier gas based on the set temperature of the liquid material in the tank l.

That is, in order to stabilize the amount of evaporation of the material gas generated by the bubbling, it is necessary to bring the vapor pressure of the generated material gas close to the saturated vapor pressure. The flow rate of the carrier gas at the saturated vapor pressure (known) at the set temperature is set, and the amount of evaporation of the liquid material approaches the saturated vapor pressure.

"Problems to be Solved by the Invention" However, in this type of device, the apparent detected temperature of the temperature detection tube inserted into the liquid material decreases due to absorption of latent heat of vaporization caused by bubbling and other reasons. It is difficult to detect the correct temperature of the liquid material, and pressure fluctuations are also likely to occur due to the bubbling. Therefore, it is impossible to set up an arithmetic circuit that takes all of these fluctuation factors into consideration. It was not possible to obtain a material gas with a stable evaporation amount.

In addition, in general, the saturated vapor pressure of this type of liquid material rises rapidly near the boiling point, and the amount of change in saturated vapor pressure becomes large with a slight temperature change. Therefore, in order to obtain a stable evaporation amount, it is necessary to It is necessary to set the liquid material temperature at a much lower temperature than that (temperature range where the amount of change in saturated vapor pressure due to temperature fluctuation is small), but with this configuration, conversely, it is necessary to increase the amount of carrier gas for bubbling. As a result, the undulation of the liquid surface due to bubbling becomes extremely large, leading to the problem that the fractional stability factor increases.

Furthermore, as is clear from Figure 3, which shows the time course of bubbling and evaporation, in this device, thermal equilibrium with the rubber heater 2 cannot be achieved due to the absorption of latent heat of vaporization in the early stage of bubbling, and evaporation continues until a steady state is reached. It also has the problem of a sudden drop in the amount.

"Means for Solving the Problems" The present invention provides a method for flowing a carrier gas controlled at a predetermined flow rate into a liquid material maintained at a predetermined temperature and generating a liquid material gas by bubbling the carrier gas after bubbling. A technical means is provided in which a stable evaporation amount can be obtained by cooling the liquid material gas on the way to a predetermined manufacturing equipment side together with the gas, and bringing the vapor pressure of the material gas to the saturated vapor pressure or close to the saturated vapor pressure. suggest.

In this case, the cooling means is placed directly above the bubbling location, specifically, the cooling means is placed above the bubbler tank 1, and the liquefied portion generated by cooling the liquid material gas is configured to return to the bubbler tank 1. It is preferable to do so.

"Operation" According to this technical means, in order to cool the liquid material gas generated by bubbling to the saturated vapor pressure or a temperature close to the saturated vapor pressure, even if the set temperature of the liquid material in the bubbler tank 1 is Even if measurement errors, liquid surface temperature drop due to latent heat of vaporization, and pressure fluctuations occur, the liquid material gas can be set to around the saturated vapor pressure regardless of these errors, so a stable evaporation amount can always be maintained. You can get it.

Therefore, according to the present technical means, even if bubbling is performed when the set temperature of the liquid material is near the boiling point, a stable amount of evaporation can be obtained by subsequent cooling, and as a result, a stable and desired amount of carrier gas can be obtained with a small amount of bubbling of the carrier gas. Material gas can be obtained.

Furthermore, according to the present technical means, by cooling the liquid material gas after bubbling, even during the period when thermal equilibrium cannot be achieved at the initial stage of bubbling, the material gas temperature T2 can be increased to the position shown by the dotted line in FIG. 3 (above the saturated vapor pressure). By dropping the
A stable evaporation amount corresponding to the saturated vapor pressure can always be obtained.

Furthermore, according to the present technical means, the liquefied portion generated by cooling the liquid material gas is returned into the bubbler tank, thereby making it possible to eliminate unstable factors that occur during the bubbling. Become.

"Embodiments" Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the components described in this example are not intended to limit the scope of this invention, but are merely illustrative examples. It's nothing more than that.

FIG. 1 shows a liquid material gas generation device according to an embodiment of the present invention, and the differences from the previous embodiment will be mainly explained. Reference numeral 6 denotes a constant temperature chamber placed on a load cell 22, and the constant temperature chamber B A bubbler tank 1 is housed inside via a rubber heater 2.

The bubbler tank 1 includes, from above, a bubble tube 7, a temperature detection tube 5. and a liquid replenishment tube 8 are inserted, respectively, so that their tip openings are located in the liquid material, and the bubble tube 7 has a plurality of small holes 7a in its front end circumference in order to enhance the bubbling effect. I'm letting you do it.

A mixed gas outlet pipe 8 is located in the tank 1 above the upper limit position of the liquid material in the bubbler tank 1.

The outlet pipe 9 extends vertically upward outside the tank 1, with a flow rate control valve 10 and a buffer tank 11 interposed therebetween,
It is configured to be led into, for example, semiconductor manufacturing equipment via an on-off valve 12 attached to the outlet side. A heater 13 that can be controlled by a temperature control unit 14 is wound around the outer circumference of the buffer tank 11, and the internal temperature T2 of the tank 10 is lower than or equal to the set temperature T1 of the liquid material in the bubbler tank 1, specifically, higher than the bubbler tank 1. The introduced material gas is set at a saturated vapor pressure or a temperature close to the saturated vapor pressure (for example, around 35° C. when the set temperature T1 of the liquid material is 40° C.).

The bubble pipe 7 is connected to the carrier gas introduction pipe I via the on-off valve 15.
B, and the introduction pipe 1B has a flow control valve 17.
, and flow rate detection sensor (mass flow controller) 1
8 to a carrier gas source. Further, the liquid replenishment pipe 8 is connected to a liquid material source via an on-off valve 19 and a flow rate control valve 20.

2! is an arithmetic circuit sequencer, and the load cell 22,
The flow rates of various gases and liquid materials and the temperatures of various heaters 13 are controlled based on various input signals from the temperature detection tube 5, the flow rate detection sensor 18, and the temperature control section 14 of the heater 13.

According to this configuration, first, the temperature T2 at which the material gas reaches the saturated vapor pressure is determined by the flow rate detection sensor 18 and the temperature detection tube 5 based on the temperature T1 inside the bubbler tank l and the bubbling amount of the carrier gas, and then the temperature T2 is determined by the heater 13. The buffer tank 11 is heated to the temperature T2, which is naturally lower than the bubbler tank 1 internal temperature 〒1.

After the internal temperature of the buffer tank 11 reaches a predetermined temperature, the carrier gas is flowed into the bubbler tank 1 to start bubbling.

Due to the bubbling, a mixed gas of liquid material gas and carrier gas is guided into the outlet pipe 9, and the buffer tank 1
In Step 1, the liquid material gas is cooled until the gas reaches the saturated vapor pressure or less, and the material gas liquefied by the cooling is returned to the bubbler tank 1 together with unstable molecules, and then the liquid material gas under saturated vapor becomes the carrier gas. It will be transported to the semiconductor manufacturing equipment side together with the gas.

When the liquid material in the bubbler tank l decreases, the arithmetic circuit sequencer 21
A predetermined signal is input to the refill tube 8, and a predetermined amount of liquid material source is supplied from the liquid replenishment pipe 8.

According to such an embodiment, the above-described effects of the present invention can be smoothly achieved.

"Effects of the Invention" As described above, according to the present invention, it is possible to absorb errors caused by temperature detection of the liquid material and pressure fluctuations in the bubbler tank 1, and obtain a stable amount of evaporation.

Further, according to the present invention, even if the set temperature of the liquid material is set near the boiling point, a stable amount of evaporation can be obtained by subsequent cooling, and as a result, a stable and desired amount of carrier gas can be obtained with a small amount of bubbling of the carrier gas. Material gas can be obtained.

Furthermore, according to the present invention, even during the period when the thermal equilibrium cannot be achieved at the initial stage of bubbling, the material gas is cooled down to the temperature T2 as shown in FIG. In addition to the basic effect of zero, which allows you to obtain a stable evaporation amount even in the early stage of bubbling, the amount of material gas transported after cooling is almost at the saturated vapor pressure, so the amount of material gas transported is calculated in advance. It can be calculated with a circuit sequencer and is extremely useful for automatic control of semiconductor generators and other devices.It is extremely versatile as it can be applied to all liquid materials with known vapor pressures. It also has various practical effects, such as being usable for liquid materials with boiling points ranging from room temperature to high temperatures (approximately 200°C).

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing a liquid material gas generating device according to an embodiment of the present invention, FIG. 2 is a schematic explanatory diagram showing a liquid material gas generating device according to the prior art, and FIG. 3 is a detailed diagram of the liquid material gas generating device according to the present invention. It is a graph diagram for explanation. Figure 1

Claims (1)

[Claims] 1) In a method of flowing a carrier gas controlled at a predetermined flow rate into a liquid material maintained at a predetermined temperature and generating a liquid material gas by bubbling, the liquid material is transported with the carrier gas after bubbling. 2) A method for generating a liquid material gas, characterized in that the liquid material gas is cooled at a position directly above the bubbler tank, and the vapor pressure of the material gas is brought close to approximately saturated vapor pressure or near the saturated vapor pressure. A method for generating a liquid material gas according to claim 1, characterized in that the method is performed by: