JP3156858B2 - Liquid feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid material supply apparatus for vaporizing a liquid material contained in a tank and supplying the vaporized liquid material to a reaction furnace.

[0002]

2. Description of the Related Art In the field of semiconductors, thin films are formed by a CVD method. The CVD method is one of important methods for vapor phase epitaxial growth.

[0003] Materials for Si epitaxial growth include SiH ₄ , SiH ₂ Cl ₂ , SiHCl ₃ , and SiH ₄ .
Cl ₄ is commonly used. Of these, SiCl ₄ and SiHCl ₃ , which are of high purity and can be obtained at low cost, are widely used industrially. These two kinds of raw materials are liquid at normal temperature and normal pressure. A liquid source supply device is used to vaporize these liquid sources and supply them to the reaction furnace of the Si epitaxial growth apparatus.

In a conventional liquid material supply apparatus, a large amount of bubbling gas such as H ₂ is introduced into a liquid material, and the material is vaporized (saturated) in the bubbling gas. The flow rate control of the raw material is performed by detecting the flow rate ratio between the bubbling gas and the saturated bubbling gas with a ratio detector. Since the saturated vapor pressure varies greatly depending on the temperature of the liquid, the liquid temperature must be controlled to be constant in order to keep the raw material supply amount constant.

The heat of vaporization of the liquid raw material is 47% for SiHCl _3.
al / g and SiCl ₄ are considerably large at 46 cal / g. Therefore, a heater such as a tape heater is attached to the liquid container, and the liquid in the liquid container is directly heated to prevent a decrease in the liquid temperature. For example, Japanese Patent Application Laid-Open No. 1-2406
See No. 63.

[0006]

However, a large amount of raw materials,
For example, when it is desired to evaporate a raw material of 50 g per minute and supply it as a raw material gas, external heating of about 2500 cal / min is required. It is technically difficult to stabilize the temperature of the liquid raw material by balancing the amount of heating and the heat of vaporization deprived.

It is conceivable to increase the flow rate of the mixed gas to be introduced in order to increase the supply amount of the liquid raw material. However, this may increase the amount of inflow gas, decrease the ratio of the source gas, and cause variations in thin film growth.

[0008] In addition, the apparatus for this must be large.

As described above, it is difficult to supply a large amount of raw materials with the conventional apparatus.

[0010] For the same reason, it is difficult to stably supply raw materials over a long period of time with the conventional apparatus.

Attempts have been made to reduce the bubbles by adjusting the blast holes for injecting the bubbling gas into the liquid raw material. However, since the depth of the liquid raw material fluctuates in the long term, sufficient effects can be obtained. Did not.

Furthermore, it is difficult to control the mixing ratio between the liquid raw material and the other gas in the conventional apparatus. That is, the increase / decrease of the supply amount of the liquid coincides with the increase / decrease of the bubbling gas, and it becomes difficult to accurately control the composition ratio with other gases.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the prior art and to provide an apparatus for supplying a liquid raw material which can vaporize a liquid raw material and constantly and stably supply a high-concentration raw material gas. It is.

[0014]

SUMMARY OF THE INVENTION One solution of the present invention is to provide a tank for containing a liquid material and a tank for feeding the liquid material.
Flow rate adjusting means for adjusting the flow rate of incoming liquid raw material;
The liquid raw material sent through the flow control means is heated.
Vaporizing means for vaporizing the raw material gas, and vaporizing by the vaporizing means.
Before the raw material gas is introduced into the reactor,
Mass flow controller for adjusting flow rate and for liquid raw materials
Said flow rate adjusting means, said mass flow controller for raw material gas
A control system for controlling at least one of the controller and said vaporizing means.
Control means is provided, and the vaporizing means
A heater for vaporization, (a) a number of thin tubes, (b)
Coiled tube, (c) large diameter tube with mesh, or
(D) a large-diameter tube and a medium-diameter porous material contained therein;
A liquid material supply device having a tube .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the outline of the illustrated embodiment will be briefly described.

[0016]Outline of illustrated example  The apparatus of the present invention vaporizes the liquid raw material stored in the tank.
Liquid feeder to feed the liquid to the reactor
To adjust the flow rate of the liquid raw material 35 sent from the tank 21
Through the flow rate adjusting means 23 and the flow rate adjusting means 23
To heat and evaporate the liquid material 35 sent
Means 29 for monitoring the supply status of the vaporized raw material and monitoring
The flow rate adjusting means 23 and the vaporizing means 2 based on the visual result
9 is provided with control means for controlling at least one of them.
This is a liquid raw material supply device.

There are various methods or means for removing the liquid raw material 35 from the tank 21. The raw material and an inert gas (H ₂ , N _2, etc.) are introduced into the airtight tank 21 to adjust the pressure in the tank to a predetermined value, and the liquid raw material is sent out from the discharge pipe 22 at that pressure. I do. Or you may make it the structure taken out by natural fall.

A carrier gas may be combined with the raw material taken out of the tank 21. This is convenient because the carrier gas can be heated to the same temperature.

As the flow rate adjusting means 23, a valve, a flow meter, a liquid flow rate adjuster (liquid mass flow meter) or the like is used, and these are automatically (manually) adjustable.

It is desirable to provide a buffer tank 32 in the vaporizing means 29 or at a subsequent stage so that the pressure in the raw material tank does not fluctuate rapidly due to a volume change when the liquid raw material is vaporized. A plurality of buffer tanks may be provided.

It is desirable to install a flow controller, that is, a mass flow controller 34, for controlling the flow rate of the vaporized source gas, and to accurately control the flow rate of the source gas by the mass flow controller 34.

A carrier gas pipe 11 is provided at the subsequent stage of the mass flow controller for adjusting the flow rate of the vaporized source gas, and the carrier gas is introduced so that the source gas is quantitatively and constantly sent to the next-stage reactor. Can be.

The control means 50 controls the flow rate and temperature of the raw material gas,
Alternatively, the flow rate and the temperature of the mixed gas including the carrier gas and the dopant gas are detected, and one of the heating operation of the vaporizing means 29, the operation of the flow rate adjusting means 23, the operation of the carrier gas supply means 27, etc. Alternatively, it is advantageous to adopt a configuration in which two or more components are comprehensively controlled.

The raw material heating section is used to improve thermal efficiency.
(A) winding a pipe in a coil shape; (b) bundling a large number of pipes having the same radius in parallel; (c) providing a multi-stage mesh portion in the pipe; and (d) providing a porous filter. By performing one or more, the efficiency of heat transfer to the liquid is improved and the vaporization can be stabilized.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0026]Detailed explanation of illustration example  FIG. 1 shows a liquid source supply device 14 according to the present invention,
FIG. 2 is a conceptual diagram showing a state applied to a dial device.

The Si epitaxial apparatus 10 has a reaction furnace 15 made of a heat insulating material. A heating unit 19 for heating an object is provided in the reaction furnace 15. A high-frequency induction coil 18 for heating is incorporated in the heating unit 19. The susceptor 16 is provided above the heating unit 19.

A tube 7 for introducing a raw material gas is inserted into the reaction furnace 15, and an opening 6 thereof is located substantially at the center of the reaction furnace 15. The opening 6 is provided with a large number of small holes so that the source gas can be uniformly supplied to the object, but the small holes are omitted in the drawing.

A discharge pipe 5 for discharging gas is provided around the lower part of the reaction furnace 15. The discharge pipe 5 joins a pipe 17 connected to an exhaust device (not shown).

The pipes 8, 11, and 12 are connected upstream of the pipe 7 so that the source gas, the H ₂ gas, and the dopant gas are sent, respectively. A liquid source supply device 14 is connected upstream of the pipe 8. Liquid raw material supply device 1
4 is connected to a pipe 9 for supplying H ₂ gas. A mass flow controller 13 is provided in the middle of the pipes 11 and 12.

FIG. 2 is a conceptual diagram showing the liquid material supply device 14. The liquid material supply device 14 includes a liquid material tank 21,
The apparatus includes a flow rate adjusting unit 23, a mass flow controller 34, and a control unit 50.

The liquid material tank 21 is formed airtight as a whole. The tank 21 is provided with a gas pipe 24 for pressure feed and a raw material take-out pipe 22. One end of the gas pipe 24 for pressure feeding is opened at the upper part of the tank 21, and one end of the raw material take-out pipe 22 is opened at the bottom of the tank 21, that is, in the liquid raw material 35. A pumping gas supply device 25 is connected to the other end of the pumping gas pipe, and a pumping gas of a predetermined pressure, for example, N ₂
The gas is sent into the tank 21. At the other end of the raw material take-out pipe 22, a flow control valve 23 as a flow control means is set. The flow control valve 23 is for sending the liquid raw material 35 at a predetermined flow rate to the vaporization means 29 in the next stage. The flow regulating valve 23 and the vaporizing means 29 are connected by a pipe 28.

The vaporizing means 29 has a structure in which a number of parallel thin tubes 36 are bundled and a heater 30 is arranged around the bundle. Then, the liquid raw material is vaporized by heating to a temperature higher than the boiling point. The thin tubes 36 may have the same diameter or different diameters.

The heating means 29 may have the structure shown in FIGS. 3 to 5 in addition to the structure shown in FIG.

In FIG. 3, the coiled tube 37 is connected to the heater 30.
Is located within.

In FIG. 4, a large-diameter tube 38 has a large number of meshes 39.

In FIG. 5, the medium diameter tube 4 is placed inside the large diameter tube 40.
1 is inserted, one end of which is open toward the raw material inlet and the other end is closed. The medium-diameter tube 41 is formed of a porous material. Therefore, the inside of the vaporizing means looks like a kind of filter. Thus, the vaporizing means is configured to improve the heat transfer efficiency.

Referring again to FIG. 2, one end of the carrier gas pipe 9 joins the pipe 28 connecting the vaporizing means 29 and the flow control valve 23. A carrier gas supply device 22 is connected to the other end of the pipe 9 so as to supply a carrier gas for transporting vaporized raw material at a predetermined flow rate.

A buffer tank 32 is connected downstream of the vaporizing means 29 via a pipe 31. The buffer tank has a buffering function for alleviating a sudden change in the pressure in the raw material tank 21 due to the vaporization of the raw material.

A mass flow controller 34 is connected downstream of the buffer tank 32 via a pipe 33.
Thus, the flow rate of the source gas is accurately controlled. The tube 8 is connected to the mass flow controller 34, and the other end is connected to the reactor. A heater 30 is also provided around the pipe 31, the buffer tank 32, and the pipe 33 to keep the temperature and heat. The heater in this portion has a function of vaporizing the raw material that is not completely vaporized and a function of preventing the vaporized raw material from being liquefied.

The liquid material supply device 14 is provided with control means 50 for comprehensively adjusting the operation.

The control means 50 shown in FIG. 6 is configured to detect the output from the mass flow controller 34, for example, the concentration and flow rate of the raw material, and to feedback control the vaporization operation of the liquid raw material based on the detection result. I have. Then, a source gas having a predetermined concentration can be supplied to the reaction furnace at a predetermined flow rate.

The control means 50 has an arithmetic unit 51 for performing a predetermined logical calculation. The detection result of the mass flow controller 34 is input to a computing unit 51, and based on the output of the computing unit 51, the carrier gas supply unit 27, the flow rate adjusting valve 23 for the liquid raw material, the pressure of the pipe 33 and the operation of the heater 30 are controlled, The vaporization operation of the liquid raw material is comprehensively adjusted.

[0044]motion  Next, the operation of the liquid material supply device shown in FIG. 2 will be described.
You.

By operating the gas feed device 25 for pressure feed, a gas for pressure feed such as N ₂ is supplied into the liquid raw material tank 21. The liquid raw material 35 in the tank 21 is supplied to the flow control valve 23 under the pressure of the gas for pressure feeding. Then, the liquid raw material 35 whose flow rate has been adjusted by the flow rate adjusting valve 23 is sent to the vaporizing means 29. The liquid raw material is efficiently heated and vaporized by the heater 30 while passing through the many parallel narrow tubes 36 in the vaporizing means 29. The vaporized raw material is sent to a mass flow controller 34 through a pipe 31, a buffer tank 32, and a pipe 33. Then, the gaseous raw material whose flow rate has been adjusted by the mass flow controller 34 is appropriately mixed with a dopant gas or H ₂ gas and sent to the reactor. At this time, the operation of the liquid material supply device is controlled by the control means 50 as described above.

[0046]Experimental example  Epitaxy is performed on the wafer using the Si growth apparatus shown in FIG.
An experiment of Shar growth was performed. The liquid material supply device is shown in FIG.
The ones shown were adopted.

In Experimental Examples 1 and 2, the raw material supply amount was 40 g / m
in and 80 g / min. The source gas is SiHC
a l ₃ was used. H ₂ gas was used as the gas for pumping, and the pressure in the tank was adjusted to 5 atm.

On the other hand, an experiment was also conducted on two comparative examples in which a raw material tank was heated and a raw material tank was not heated, using a raw material supply device of a bubbling method.

In the comparative example, the initial raw material supply amount was 40 g / m
set to be in. Other conditions were the same as in the experimental example of the present invention.

First, a test for flowing only the raw material was performed, and the temperature in the raw material tank and the actual supply amount of the raw material were measured. Table 1 shows the results.

In Comparative Examples 1 and 2, the raw material supply device was set so that the initial raw material supply amount was 40 g / min, and the conditions were not changed thereafter. Then, each one
Epitaxial growth was attempted using 0 lots (20 wafers per lot). Then, the yield of the wafer, the variation in the film thickness, and the average growth rate of the film were examined. Table 2 shows the results.

[0052]

[Table 1] As is clear from Table 1, in Comparative Examples 1 and 2, even if the initial raw material supply amount was set to 40 g / min, the supply amount increased or decreased.
Raw materials could not be supplied stably. Also, it was difficult to set the initial supply amount of the raw material to 80 g / min.

On the other hand, in Experimental Examples 1 and 2 of the present invention,
By setting the raw material supply amounts to 40 g / min and 80 g / min, the raw material could be stably supplied for 20 minutes.

[0054]

[Table 2] Further, as is clear from Table 2, in the experimental example of the present invention, the variation in the film thickness was small and the average yield was good as compared with the comparative example. However, the reason why the average growth rate of the film was the same in Experimental Example 1 and Comparative Examples 1 and 2 is probably because the increase or decrease in the raw material supply amount in Comparative Example did not significantly affect the film growth rate.

[0055]

According to the liquid raw material supply apparatus of the present invention, the liquid raw material can be vaporized and supplied stably at a high concentration. When the apparatus of the present invention is applied to, for example, a vapor phase growth apparatus, it is possible to form a high-quality thick film at a higher speed and at a constant growth rate as compared with the related art. Therefore, product quality and yield can be improved. Also, the mixture composition ratio of the source gas and the carrier gas or the dopant gas can be freely changed. Therefore, product quality and yield can be further improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a state in which a liquid source supply apparatus of the present invention is applied to a Si epitaxial apparatus.

FIG. 2 is a conceptual diagram showing an embodiment of a liquid material supply device according to the present invention.

FIG. 3 is a conceptual diagram showing an embodiment of a vaporizing means used in the apparatus of the present invention.

FIG. 4 is a conceptual diagram showing another embodiment of the vaporizing means used in the apparatus of the present invention.

FIG. 5 is a conceptual diagram showing still another embodiment of the vaporizing means used in the apparatus of the present invention.

FIG. 6 is a flowchart showing an outline of control means used in the apparatus of the present invention.

[Explanation of symbols]

 14 Liquid material supply device 21 Tank 23 Flow rate adjusting means 29 Vaporizing means 34 Mass flow controller 35 Liquid raw material 50 Control means ◆

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Akai 8231−5 Tokuyama Ceramics Co., Ltd., Tokuyama City, Tokuyama City, Yamaguchi Prefecture (72) Inventor Kenro Hayashi 8231 Eguchi Development, Tokuyama, Tokuyama City, Yamaguchi Prefecture -5 Tokuyama Ceramics Co., Ltd. (56) References JP-A-61-254242 (JP, A) JP-A-2-261153 (JP, A) JP-A-63-98349 (JP, U) (58) Investigated Field (Int.Cl. ⁷ , DB name) B01J 4/00 103 B01J 7/02 C30B 25/14

Claims (4)

(57) [Claims] 1. A tank for containing a liquid material, the tank
Flow adjustment to adjust the flow rate of the liquid raw material sent from the reservoir
Means and a liquid source sent through the flow control means.
To produce raw gas by heating and vaporizing the feedstock
Means, and the raw material gas vaporized by the vaporizing means is supplied to the reaction furnace.
Mass flow that regulates the flow rate of source gas before it is introduced
A controller, the flow rate adjusting means for a liquid raw material, and a raw material
The mass flow controller for gas and the vaporizing means
Control means for controlling at least one of the
The vaporizing means includes a heater for vaporizing the liquid raw material.
A liquid material supply device having a large number of thin tubes . 2. A tank for containing a liquid material, the tank
Flow adjustment to adjust the flow rate of the liquid raw material sent from the reservoir
Means and a liquid source sent through the flow control means.
To produce raw gas by heating and vaporizing the feedstock
Means, and the raw material gas vaporized by the vaporizing means is supplied to the reaction furnace.
Mass flow that regulates the flow rate of source gas before it is introduced
A controller, the flow rate adjusting means for a liquid raw material, and a raw material
The mass flow controller for gas and the vaporizing means
Control means for controlling at least one of the
The vaporizing means includes a heater for vaporizing the liquid raw material.
Liquid raw material supply device having a coiled tube
Place . 3. A tank for containing a liquid material, the tank
Flow adjustment to adjust the flow rate of the liquid raw material sent from the reservoir
Means and a liquid source sent through the flow control means.
To produce raw gas by heating and vaporizing the feedstock
Means, and the raw material gas vaporized by the vaporizing means is supplied to the reaction furnace.
Mass flow that regulates the flow rate of source gas before it is introduced
A controller, the flow rate adjusting means for a liquid raw material, and a raw material
The mass flow controller for gas and the vaporizing means
Control means for controlling at least one of the
The vaporizing means includes a heater for vaporizing the liquid raw material.
Liquid source having a large-diameter tube having a mesh
Feeder . 4. A tank for containing a liquid material,
Flow adjustment to adjust the flow rate of the liquid raw material sent from the reservoir
Means and a liquid source sent through the flow control means.
To produce raw gas by heating and vaporizing the feedstock
Means, and the raw material gas vaporized by the vaporizing means is supplied to the reaction furnace.
Before it is introduced, the mass flow to adjust the flow rate of the raw material gas
A controller, the flow rate adjusting means for a liquid raw material, and a raw material
The mass flow controller for gas and the vaporizing means
Control means for controlling at least one of the
The vaporizing means includes a heater for vaporizing the liquid raw material.
Large diameter tube and medium diameter porous material tube
A liquid raw material supply device .