JPH0671551B2 - Quantitative vaporization supply device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention precisely controls the gas component ratio in a mixed gas and precisely adjusts the total amount of the required mixed gas to obtain a predetermined concentration and amount. The present invention relates to a device for supplying a mixed gas provided.

[0002]

In the electronic industry, particularly in the technical field of semiconductor manufacturing processes, etc., a liquid component is vaporized and mixed in a gas,
The need for utilization as a mixed gas often arises. Conventionally, in a semiconductor manufacturing process, a bubbler has been used for the purpose of vaporizing a raw material liquid, introducing it into a reaction chamber, and forming a thin film or a thick film by a predetermined reaction. The bubbler is a vaporization supply device that uses the principle of vaporizing and mixing the liquid raw material into the carrier gas by blowing the carrier gas into the liquid raw material to form bubbles, but the liquid level in the bubbler is When the gas flow rate decreases due to consumption, the time during which the gas passes through the liquid raw material decreases even when the carrier gas flow rate is constant, and the resulting mixed gas component ratio changes.

Further, since the bubbles of the carrier gas burst at the liquid surface in the bubbler, the liquid film forming the bubbles scatters and atomizes, which mixes in the mixed gas as liquid droplets, and is discharged from the discharge port of the bubbler. Since it is condensed or vaporized earlier, it is difficult to control and obtain a mixed gas of constant concentration and fixed amount. By the way, it is possible, if not impossible, to prevent the occurrence of trouble due to mist by heating the tip of the outlet of the mixed gas from the bubbler to vaporize the liquid raw material in the mixed gas, and by that method It has been difficult to control the concentration of gas components and regulate the total amount of mixed gas.

Conventionally, when a vaporized liquid raw material is introduced into a depressurized reaction chamber and used, a mass flow meter is used for the cylinder containing the liquid raw material and the depressurized reaction chamber if the liquid raw material has an appropriate vapor pressure. A method has been performed in which the liquid raw material, which is communicated via the liquid, is introduced into the reaction chamber from the cylinder by utilizing the differential pressure and is supplied while adjusting the supply amount.

According to this method, it is possible to control the supply amount of the liquid raw material, but when the pressure in the reaction chamber is not sufficiently low, it is necessary to keep the vapor pressure of the liquid raw material sufficiently high. Since it is necessary to keep the liquid raw material and the mass flowmeter at a high temperature, it cannot be applied to a thermally unstable liquid raw material, and the heat resistance of the mass flowmeter is limited, so that it can be put to practical use. Was difficult.

[0006]

Therefore, the present invention is to vaporize and supply a liquid raw material to a depressurized reactor which can utilize only the non-controllable or high vapor pressure liquid raw material that is inherent in the known bubbler system as described above. It is an object of the present invention to develop and provide a new quantitative vaporization supply means and device capable of eliminating a narrow application range of a system.

[0007]

In order to achieve the above-mentioned object, the present invention has the respective constituent features as described below. (1) A first pipe system equipped with a first mass flow rate indicator controller for feeding carrier gas into the liquid raw material vaporization section while controlling the flow rate is connected to the vaporization section carrier gas introduction end,
A mass flow indicator is connected to a second pipe system that leads out the mixed gas from the evaporation section, and a third pipe system equipped with a second mass flow indicator controller is provided in the second pipe system. In addition to connecting to the mixed gas outlet side of the mass flow indicator, introducing a fixed amount of buffer gas into the same pipe system, and inputting the indicated values of the mass flow indicator and the first mass flow indicator controller to the electronic arithmetic control circuit. Then, the difference between the two indicated values is calculated to detect the flow rate of the evaporated substance of the liquid raw material, and

The first mass flow rate indicating controller is controlled by the circuit so that the mass flow rate of the vaporized substance becomes a predetermined constant value, and at the same time, the indicated value of the first mass flow rate indicating controller and the second mass flow rate are controlled. The indicated value of the indicating controller is input to each of the circuits, the sum is calculated, the total mass flow rate of the non-evaporated gas in the system is detected, and the total mass flow rate of the non-evaporated gas becomes a predetermined constant value. A quantitative vaporization and supply device characterized in that it comprises at least a process for controlling the second mass flow rate indicating controller by the circuit.

(2) A first pipe system provided with a first mass flow rate indicator controller for feeding carrier gas into the liquid raw material vaporization section while controlling the flow rate is connected to the vaporization section carrier gas introduction end. Then, the mass flow indicator is connected to the second pipe system that leads out the mixed gas from the evaporation section, and the third pipe system equipped with the second mass flow indicator controller is connected to the second pipe system. In addition to being connected to the mixed gas introduction side of the mass flow rate indicator provided in the above, a fixed amount of buffer gas is introduced into the same pipe system, and the indicated values and masses of the first mass flow rate indicator controller and the second mass flow rate indicator controller The indicated value of the flowmeter is input to each electronic arithmetic control circuit, and the sum of the indicated values of the first and second mass flow rate indicating controllers is subtracted from the indicated value of the mass flowmeter to evaporate the liquid raw material. While detecting the mass flow rate,

The first mass flow rate indicating controller is controlled by the circuit so that the mass flow rate of the vaporized substance becomes a predetermined constant value, and at the same time, the indicated value of the first mass flow rate indicating controller and the second mass flow rate are controlled. The indicated value of the indicating controller is input to each of the circuits, the sum is calculated, the total mass flow rate of the non-evaporated gas in the system is detected, and the total mass flow rate of the non-evaporated gas is set to a fixed value. The quantitative vaporization supply device is characterized by at least including a process of controlling the second mass flow rate indicating controller by the circuit so that

[0011]

FIG. 1 is a system diagram of a supply device according to the present invention.
The principle operation of the device of the present invention will be described with reference to FIG. 2 as follows. In the figure, 6 is a first tube system into which a carrier gas is introduced, and the tube system is connected with a first mass flow controller 1 capable of measuring the mass flow rate of the carrier gas and adjusting the flow rate. The outlet side communicates with the evaporation unit 4 containing the raw material liquid 10.

Then, by injecting a carrier gas into the raw material liquid 10, a part of the liquid is evaporated into the carrier gas to form a mixed gas, which passes through the pipe system 7 and the mass flowmeter 2
Will be introduced to. At this time, the mass flow rate measured by the mass flow controller 1 of the carrier gas introduced into the first pipe system is m ₁ g
/ Sec The mass flow rate of the mixed gas measured by the mass flowmeter ₂ is m ₂ g /
When sec, the mass flow rate newly increased by vaporization of the raw material liquid, m ₄ g / sec, is m ₄ g / sec = m ₂ g / sec −m ₁ g / sec according to the method shown in FIG. (1)
Is.

Further, 8 is a second pipe system into which the buffer gas (the same component as the carrier gas) is introduced, and the mass flow rate of the buffer gas can be measured in the pipe system 8 and the flow rate can be adjusted. A possible second mass flow rate indicator controller 3 is inserted, and its outlet side communicates with the outlet side terminal pipe system 9 of the mass flowmeter 2 in the system shown in FIG. 1, and the system shown in FIG. In the case of, it communicates with the pipe system 7. When adjusting the mass flow rate of the buffer gas to m ₃ g / sec,

According to the method shown in FIG. 2, m ₄ g / sec = m ₂ g / sec −m ₁
g / sec-m ₃ g / sec (2) The mass flow rate of the mixed gas in the terminal pipe system 9 of this device is m ₃ g / sec + m ₂ g / sec in the system of Fig. 1 (3) m ₂ g / sec in the system of Fig. 2 … (4).

The total mass flow rate of the carrier gas and the buffer gas in the terminal pipe system 9 of the present apparatus is m ₁ g / sec + m ₃ g / sec in both formulas. The calculation of these mass flow rate values is performed by the electronic calculation control unit 5, and the mass flow rate control signal is also added from the control unit 5 to the first and second mass flow rate controllers 1 and 3. The electronic calculation control unit 5 may be provided with a display for displaying measured values, calculated values, etc., if necessary.

(A) Means for changing only the gas component ratio to a predetermined value without changing the mass flow rate of the mixed gas in the terminal pipe system 9 as a predetermined value by this apparatus is as follows. That is, the ratio of the gas component generated by the vaporization of the raw material liquid 10 to the mixed gas passing through the terminal pipe system 9 is C.
Is represented by the following equation. In the method shown in FIG. 1, C = (m ₂ g / sec −m ₁ g / sec) / (m ₃ g / sec + m ₂ g / sec) (5) In the method shown in FIG. 2, C = (m ₂ g / sec −m ₁ g / sec −m ₃ g / sec) / (m ₂ g / sec) …… (6)

C is the carrier gas flow rate m ₁ g / sec.
Therefore, if m ₁ g / sec is increased and m ₃ g / sec is decreased while keeping the value of equation (3) or (4) constant, the mass flow rate of the mixed gas is not changed. , The vaporization component ratio can be increased, m ₁ g / sec can be decreased, and m ₃
If g / sec is increased, the vaporized component ratio can be decreased without changing the mass flow rate of the mixed gas.

(B) This device can maintain the vaporized component ratio at a predetermined value while changing the mass flow rate of the mixed gas in the terminal pipe system 9 to a predetermined amount. That is, m ₁ g / se
The mass flow rate of a mixed gas having a constant vaporization component ratio is obtained by reducing c and m ₃ g / sec in a balanced manner while keeping the value of C expressed by the equations (5) and (6) constant. Can be controlled. (C) Further, the sublimable solid whose vaporization area is likely to change and consequently the vaporization amount per hour is likely to change over time is vaporized,
It can also be used when stably obtaining a predetermined amount of a mixed gas having a predetermined vaporization component ratio. (D) Further, even when the vaporizer is a liquid vaporizer such as a bubbler and the ratio of the carrier gas to the vaporized component remarkably changes due to the fluctuation of the liquid surface, the predetermined vaporized component ratio; A mixed gas can be generated.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the quantitative vaporization supply device of the present invention will be described with reference to the drawings. However, the device described below merely describes one or two of the preferred embodiments of the present invention. Since the members constituting the embodiment may have various modifications within the technical level in the technical field at the time of the present application, only the constitution of the embodiment described below will be shown without any particular reason. A limited interpretation of the gist of the present invention should not be allowed on the basis of this.

(No. 1) FIG. 1 is a system diagram showing an embodiment of the device of the present invention, and its detailed structure is as described in detail in the above-mentioned [Operation], so it is omitted here. In the figure, the evaporator 4 was used as a bubbler, and the bubbler periphery was heated to warm the bubbler and its contents to 80 ° C. The raw material liquid 10 in the bubbler was tetraethoxysilane. The mass flow rate measured by the first mass flow controller (mass flow rate controller) 1 is m ₁ g / sec, and the mass flow rate measured by the second mass flow controller 3 is m ₃ g / sec. The mass flow rate measured by the mass flow meter 2. When the flow rate is m ₂ g / sec,

In the electronic operation control unit 5, each (m ₂ g
/ Sec −m ₁ g / sec) / (m ₃ g / sec + m ₂ g / sec) is calculated as C, and m ₁ g / sec + m ₃ g / sec is calculated and M is calculated.
When the value of C is about to decrease, the control valve of the first mass flow controller 1 is opened and m ₁ g / sec
Is increased by Δmg / sec, and at the same time, the control valve of the second mass flow controller 3 is closed, and m ₃ g / se
The circuit was designed so that the value of C can be maintained at a constant value and the value of M can be maintained at a constant value by instructing to decrease c by Δmg / sec.

When the value of C is about to increase, the control valve of the first mass flow controller 1 is closed and m ₁ g / sec is decreased by Δmg / sec, and at the same time, the control valve of the second mass flow controller 3 is turned on. When opened, m ₃ g / sec was increased by Δmg / sec so that the value of C could be kept constant and the value of M could be kept constant. The flow rate of the tetraethoxysilane gas was m ₂ g / sec −m ₁ g / sec in terms of helium conversion, and the measured value was obtained. In the electronic operation control unit 5, the value of M was set to 3 mg / sec and the value of C was set to 0.0196.

Then, helium was introduced from the buffer gas introduction pipe system 8, and after about 2 seconds, the indication value of the second mass flow controller 3 became 3 mg / sec, and then helium was introduced from the carrier gas introduction pipe system 6. did. After about 2 seconds, C
Value reaches 0.0196 and stabilizes, and M value is 3 mg / sec.
Stable in. Even when the bubbler ambient temperature was changed from 60 ° C to 100 ° C, the values of M and C were practically stable and did not change.

(Part 2) The system diagram of FIG. 2 shows another embodiment of the device of the present invention, and its detailed structure is described in the section of [Operation] as in the embodiment (Part 1). I will not repeat it. In the figure, the evaporator 4 was used as a bubbler, the surrounding was heated to heat the bubbler and its contents to 80 ° C., and the content of the bubbler was tetraethoxysilane, as in Example (No. 1). is there. In the electronic operation control unit 5, (m ₂ g / sec −m ₃ g / sec −m ₁ g / sec) / (m ₂ g
/ Sec) to C and m ₂ g / sec to M,

When the value of C is about to decrease, the control valve of the first mass flow controller 1 is opened to increase m ₁ g / sec by Δmg / sec, and at the same time, the second
The control valve of the mass flow controller 3 was closed and m ₃ g / sec was decreased by Δmg / sec so that the value of C could be kept constant and the value of M could be kept constant.

When the value of C is about to increase, the first
Close the control valve of the mass flow controller 1 to reduce m ₁ g / sec by Δmg / sec, and at the same time open the control valve of the second mass flow controller 3 to increase m ₃ g / sec by Δmg / sec, The value of C was kept constant and the value of M was kept constant. The flow rate of the tetraethoxysilane gas was a helium conversion flow rate, and the measured value was obtained as m ₂ g / sec −m ₁ g / sec.

In the electronic operation control unit 5, the value of M is set to 3 mg.
/ Sec and the value of C were set to 0.0196. Next, helium was introduced from the buffer gas introduction pipe system 8, and after about 2 seconds, the indication value of the second mass flow controller 3 was 3 mg /
After indicating sec, helium was introduced from the carrier gas introducing pipe system 6. After about 2 seconds, the value of C reached to 0.0196 and became stable, and the value of M became stable at 3 mg / sec. Even when the bubbler ambient temperature was changed from 60 ° C to 100 ° C, the values of M and C were practically stable and did not change. Further, the values of M and C were practically stable and did not change even when the content of the bubbler was reduced. Furthermore, in the same embodiment, the set value of M
Select between 0.5mg / sec and 15mg / sec, and set the value of C.
When it was taken from 0.002 to 0.09 and the stability of each M and C was confirmed, there was practically no change.

[0028]

As described above, according to the present invention, the level of the liquid raw material is changed to some extent in the vaporization supply device in which the liquid raw material required in the semiconductor manufacturing process is vaporized and mixed into the carrier gas. Even if the phenomenon occurs, or the phenomenon that the liquid film is atomized in the evaporator may occur, it is possible to control so that the gas component concentration of the supplied mixed gas is always at a desired ratio. ,
Further, it is possible to provide a device capable of maintaining a desired ratio regardless of the supply amount of the mixed gas.

Further, the apparatus of the present invention enables the above-mentioned supply control without heating the liquid raw material, the flowmeter, etc. to a very high temperature, and so on, which cannot be expected from a conventionally known bubbler. The action and effect of can be exhibited.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of a supply device of the present invention.

FIG. 2 shows a system diagram of another embodiment of the supply device of the present invention.

[Explanation of symbols]

 1 1st mass flow controller 2 Mass flow meter 3 2nd mass flow controller 4 Evaporation part 5 Electronic operation control device 6 Carrier gas introduction pipe system 7 Mixed gas derivation pipe system 8 Buffer gas derivation pipe system 9 Terminal pipe system 10 Raw material liquid.

Claims (2)

[Claims] 1. A first pipe system equipped with a first mass flow rate indicating controller for feeding a carrier gas into a liquid raw material vaporization section while controlling the flow rate thereof is connected to the vaporization section carrier gas introduction end. , A mass flow indicator is connected to a second pipe system for leading out the mixed gas from the evaporation section, and a third pipe system equipped with a second mass flow indicator controller is connected to the second pipe system. It is connected to the mixed gas outlet side of the provided mass flow rate indicator, and a fixed amount of buffer gas is introduced into the same pipe system, and the indicated values of the mass flow rate indicator and the first mass flow rate indicator controller are stored in the electronic calculation control circuit. By inputting and calculating the difference between the two indicated values to detect the flow rate of the vaporized substance of the liquid raw material, the first mass flow rate indicating controller is controlled by the circuit so that the mass flow rate of the vaporized substance becomes a predetermined constant value. The first mass flow rate indicating controller and the second mass flow rate finger are controlled at the same time. The indicated value of the indicating controller is input to each of the circuits and the sum is calculated, and the total mass flow rate of the non-evaporated gas in the system is detected to make the total mass flow rate of the non-evaporated gas a fixed value. A quantitative vaporization and supply device characterized in that it comprises at least a process for controlling the second mass flow rate indicating controller by the circuit. 2. A first pipe system equipped with a first mass flow rate indicating controller for feeding carrier gas into the liquid raw material vaporization section while controlling the flow rate thereof is connected to the vaporization section carrier gas introduction end. , A mass flow indicator is connected to a second pipe system for leading out the mixed gas from the evaporation section, and a third pipe system equipped with a second mass flow indicator controller is connected to the second pipe system. In addition to being connected to the mixed gas introduction side of the provided mass flow rate indicator, a fixed amount of buffer gas was introduced into the same pipe system, and the indicated value and mass flow rate of the first mass flow rate indicator controller and the second mass flow rate indicator controller Each of the indicated values of the meter is input to the electronic arithmetic control circuit, and the sum of the indicated values of the first and second mass flow rate indicating controllers is subtracted from the indicated value of the mass flow meter to calculate the evaporation material of the liquid raw material. The mass flow rate is detected and the mass flow rate of the evaporant becomes a fixed value. As described above, the first mass flow rate indicating controller is controlled by the circuit, and at the same time, the indication value of the first mass flow rate indicating controller and the indication value of the second mass flow rate indicating controller are respectively input to the circuit, The sum is calculated, the total mass flow rate of the non-evaporated gas in the system is detected, and the second mass flow rate indicator controller is controlled by the circuit so that the total mass flow rate of the non-evaporated gas becomes a predetermined constant value. Quantitative vaporization and supply device characterized by comprising a minimum number of processes.