JPH05335243A - Liquid bubbling apparatus - Google Patents

Abstract

PURPOSE:To stably supply material gas when liquid organic metal or liquid material of metal mercury, etc., is vaporized by bubbling and supplied in a vapor growth. CONSTITUTION:A horizontal plate 5 made of a porous material is provided in a bubbler 1 in which liquid material 2 is charged, bubbles of gas for bubbling are divided into small bubbles, and supplied into the material 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid bubbling apparatus used for vapor phase growth of a film on a semiconductor substrate.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional liquid bubbling apparatus shown in, for example, a publication, "Semiconductor Epitaxy Technology", written by Takashi Kawatoda, Sangyo Tosho. In the figure, a bubbler 1 contains a liquid raw material 2 such as liquid organic metal or metallic mercury. A bubbling gas introduction pipe 3 is inserted into the liquid raw material 2 in the bubbler 1. A raw material gas outlet pipe 4 for leading out the vaporized raw material gas is connected to the upper portion of the side surface of the bubbler 1.

A conventional liquid bubbling apparatus is constructed as described above, and a bubbling gas (carrier gas) such as hydrogen is used.
Is introduced into the bubbler 1 through the bubbling gas introduction pipe 3,
It is supplied as bubbles from the tip of a bubbling gas introduction pipe 3 provided in the liquid raw material 2 in the bubbler 1. Liquid raw material 2
Is vaporized into bubbles, reaches a saturated vapor pressure, and is then discharged from the source gas discharge pipe 4 and supplied into the reaction furnace. The bubbler 1 is usually immersed in a constant temperature bath and kept at a constant temperature, and the molar concentration of the raw material gas in the bubbles can be adjusted by adjusting the temperature of the constant temperature bath to change the saturated vapor pressure of the raw material. is there.

[0004]

In the conventional liquid bubbling apparatus as described above, when a liquid having a large specific gravity is used as the liquid raw material 2, bubbles are intermittently supplied to the liquid raw material 2 so that vaporization occurs. There is a problem that the supply of the raw material gas to the reaction furnace becomes unstable, and the composition and film thickness of the obtained crystal become uneven. Further, when the liquid raw material 2 is consumed and the liquid level drops, the vaporization of the liquid raw material 2 into the bubbles becomes insufficient, and the raw material is supplied to the reaction furnace before reaching the saturated vapor pressure in the bubbles. There is a problem that it is difficult to accurately grasp the molar concentration of gas. Further, when the liquid raw material 2 having a high saturated vapor pressure is used, there is a problem that the raw material gas is supplied to the reaction furnace with insufficient vaporization into bubbles.

The present invention has been made to solve the above-mentioned problems, and can stabilize the supply of the raw material gas into the reaction furnace, and further has a limited bubbler. An object of the present invention is to obtain a liquid bubbling device capable of increasing the efficiency of vaporization of a liquid raw material in the space.

[0006]

In the liquid bubbling apparatus according to the invention of claim 1, a horizontal plate which divides the inside of the bubbler into a plurality of vertical chambers to divide gas bubbles into small chambers is provided in the bubbler. It is provided.

In the liquid bubbling apparatus according to the second aspect of the present invention, a liquid level adjusting container for keeping the liquid surface of the liquid raw material constant is connected by a conduit to any one of the chambers filled with the liquid raw material. Is.

In the liquid bubbling apparatus according to the third aspect of the present invention, the inside of the bubbler is divided into a plurality of lateral chambers by a vertical plate, and the upper chamber of the upstream chamber and the lower chamber of the downstream chamber are divided. Is connected by a communication pipe, and the bubbler has a multi-layered structure.

[0009]

In the present invention, the bubbles of the bubbling gas are divided and reduced by the horizontal plate provided in the bubbler. Therefore, the pressure fluctuation of the source gas is reduced. Also,
By dividing the bubbles into small parts, the ratio of the total surface area of the bubbles contacting the liquid raw material in the bubbler to the total volume of the bubbles is increased, and the efficiency of vaporizing the liquid raw material into the bubbles is improved. Further, by keeping the liquid surface of the liquid raw material in the bubbler constant, the process in which the bubbles act on the liquid raw material becomes constant.

[0010]

【Example】

Example 1. FIG. 1 is a sectional view showing a liquid bubbling device according to an embodiment of the present invention. Reference numerals 1, 2, 3 and 4 are the same as those of the conventional device. In the figure, in a bubbler 1, a horizontal plate 5 made of a porous material that allows only gas to pass selectively is provided. The horizontal plate 5 divides the inside of the bubbler 1 into upper and lower two chambers.

In the liquid bubbling apparatus constructed as described above, the liquid raw material 2 and the bubbling gas introduction pipe 3 are provided.
By providing a horizontal plate 5 (partition plate) made of a porous material between and, the bubbling gas is divided into very small bubbles and then supplied into the liquid raw material 2. Therefore, continuous and stable supply of the raw material gas is possible, and the ratio of the total surface area (the area where the bubbles are in contact with the liquid raw material 2) to the total volume of the bubbles is large, so that the efficiency of vaporizing the liquid raw material 2 into the bubbles is also increased. Get higher As a result, the supply of the raw material gas to the reaction furnace can be stabilized, and the composition and film thickness of the obtained crystal can be made uniform.

Example 2. In Example 1 described above, one horizontal plate 5 made of a porous material was provided between the liquid raw material 2 in the bubbler 1 and the gas introduction pipe 3 for bubbling.
In addition to the first embodiment, as shown in FIG. 2, an upper horizontal plate 6 made of a porous material is provided between the upper part of the liquid raw material 2 and the raw material gas outlet pipe 4. The upper part and the lower part sandwiching the upper horizontal plate 6 are communicated with each other through a small hole, and the periphery of the small hole is surrounded by a protective plate 7 so that air bubbles do not escape to the upper part from this small hole.

The bubbles divided into small pieces by the horizontal plate 5 gradually become larger due to the effect that the bubbles are combined with each other as they rise to the liquid surface and the effect that the pressure applied to the bubbles is reduced and the bubbles expand. However, in the second embodiment, since the upper horizontal plate 6 is provided, the bubbles that have grown are redivided. Therefore, the pressure fluctuation of the raw material gas becomes small and the stable supply of the raw material gas becomes possible.

Example 3. FIG. 3 shows a baffle plate 8 provided with a large number of small holes which are sufficiently smaller than the size of bubbles as a horizontal plate (partition plate) for dividing bubbles. By providing in the liquid raw material 2, the bubbles are divided into sufficiently small parts, and the same effect as that of the first embodiment is expected.

Example 4. The fourth embodiment is the same as the first embodiment.
In addition, as shown in FIG. 4, an upper lid 9 made of a porous material, a liquid level adjusting container 10 connected by a conduit to a room sandwiched between the horizontal plate 5 and the upper lid 9, and an upper part of the liquid level adjusting container 10 And a liquid raw material reservoir 11 connected to the liquid level adjusting container 10 by a conduit. The bubbler 1 is divided into a bubbling gas introduction pipe 3 side and a source gas discharge pipe 4 side by an upper lid 9 without any gap, and the horizontal plate 5 and the upper lid 9 are separated.
The inside of the bubbler 1 sandwiched between the liquid level adjusting container 10 and the liquid source reservoir 11 is filled with the liquid source 2. The bottom of the liquid raw material reservoir 11 is installed at a position higher than the lower portion of the upper lid 9.

With such a structure, the liquid raw material 2 in the bubbler 1 is consumed when bubbling is performed for a long time, but as long as the liquid raw material 2 is in the liquid raw material reservoir 11, it is constantly replenished,
The liquid level of the liquid raw material 2 in the bubbler 1 is always kept constant. Therefore, the process in which the bubbles pass through the liquid raw material 2 is always constant, and the stable supply of the raw material gas is possible regardless of the passage of time.

Embodiment 5. The fifth embodiment is the same as the first embodiment.
In addition to this, as shown in FIG. 5, a liquid level adjusting container 10, a liquid raw material reservoir 11, and a liquid level adjusting float 12 floating on the liquid surface of the liquid raw material in the liquid level adjusting container 10 are provided. As the material of the liquid level adjusting float 12, a material having a specific gravity sufficiently smaller than that of the liquid raw material 2 is selected, and the liquid level adjusting float 12 is selected.
Make sure that buoyancy is applied to.

Further, the liquid level adjusting container 10 is filled with the liquid raw material 2 without leaving a space, and the inner diameter of the conduit connecting the liquid level adjusting container 10 and the liquid raw material reservoir 11 is compared with the diameter of the liquid level adjusting float 12. And make it small enough. As a result, the liquid level adjusting float 12 is pressed against the upper part of the liquid level adjusting container 10 by buoyancy, and the liquid level adjusting container 10 and the liquid raw material reservoir 11 are weakly shut off from each other. Further, although the liquid level height in the bubbler 1 is set higher than the position of the lower end of the liquid level adjusting float 12 in the liquid level adjusting container 10, the liquid level height of the liquid raw material in the bubbler 1 and the liquid level It is assumed that the difference in the liquid level height of the raw material reservoir 11 is h and the forces applied to the liquid level adjusting float 12 are balanced.

If bubbling is performed for a long time, the liquid raw material 2 in the bubbler 1 is consumed and the liquid level in the bubbler 1 drops. Then, the difference between the liquid level inside the bubbler 1 and the liquid level of the liquid raw material reservoir 11 becomes large, and the vertically downward force applied to the liquid level adjusting float 12 becomes large, and the liquid level adjusting float 12 descends. Then, the liquid raw material 2 flows from the liquid raw material reservoir 11 into the liquid level adjusting container 10,
The difference in liquid level height becomes h again and stabilizes.

At this time, the liquid level in the bubbler 1 is slightly lowered due to the consumption of the liquid raw material 2 and a decrease in the total amount of the liquid raw material. However, if the horizontal cross-sectional area of the liquid raw material reservoir 11 is made large enough, Since the change in the liquid level of 11 is very small, the change in the liquid level in the bubbler 1 is also very small. Therefore, the process in which the bubbles pass through the liquid raw material 2 is substantially constant regardless of the passage of time, and it becomes possible to supply the raw material gas more stably.

Further, in the conventional liquid bubbling apparatus, since the inner wall of the bubbler 1 becomes cloudy due to the adsorption of the raw material gas during long-term use, it is difficult to accurately grasp the liquid level from the outside, and the consumed liquid raw material 2 It was difficult to supply the liquid to make the liquid level inside the bubbler 1 constant. However, in the liquid bubbling device having this structure, since the liquid surface height in the bubbler 1 can be adjusted by the liquid surface height of the liquid raw material reservoir 11, the liquid raw material 2 is adjusted so that the liquid surface height of the liquid raw material reservoir 11 becomes constant. It is possible to keep the liquid level inside the bubbler 1 constant by paying attention to the supply of the liquid.

Embodiment 6. The liquid bubbling apparatus shown in FIG. 6 is one in which the inside of the bubbler 1 is divided by a vertical plate 13 into two lateral chambers, a first chamber 14 and a second chamber 15.
The outlet pipe 16 from the chamber 14 and the inlet pipe 17 to the second chamber 15 are connected. In addition, the outlet pipe 16 and the inlet pipe 17
The communication pipe 18 is constituted by.

With such a structure, the bubbling gas supplied from the bubbling gas introducing pipe 3 is the same as that in the first embodiment.
Similarly to the above, after being divided into small bubbles by the horizontal plate 5 using a porous material, they are supplied into the liquid raw material 2 and exit from the outlet pipe 16 as a raw material gas. This source gas is used in the first chamber 1
It is supplied again into the bubbler 1 (second chamber 15) from the introduction pipe 17 to the second chamber 15 connected to the outlet pipe 16 from 4. After passing through the above process again, this gas is supplied to the reaction furnace through the raw material gas supply and discharge pipe 4.

Further, a space is provided between the upper portion of the horizontal plate 5 and the lower portion of the vertical plate 13, and the upper lid 9, the liquid level adjusting container 10 and the liquid raw material reservoir 11 described in the fourth embodiment are provided, whereby each chamber 14 is provided. , 15 is always kept constant.
Needless to say, the method described in Example 5 may be used as a method for keeping the liquid level in each chamber constant.

By providing the bubbling process in two stages in this way, the process of passing the bubbling gas through the liquid raw material is doubled, and the vaporization efficiency of the liquid raw material 2 in the limited space in the bubbler 1 is increased. Can be increased.

In the sixth embodiment, the bubbler 1 has 2
Although it is divided into chambers, this effect is further enhanced by providing a plurality of vertical plates to increase the number of small chambers and providing more bubbling steps. Also, the horizontal and vertical plates are
It suffices if the inside of the bubbler can be divided vertically and horizontally, and it is not necessary to arrange the bubblers completely horizontally or vertically.

[0027]

As described above, in the liquid bubbling apparatus according to the first aspect of the present invention, the horizontal plate that divides the inside of the bubbler into a plurality of vertical chambers to divide the gas bubbles into small chambers is provided in the bubbler. Since it is provided in the above, it is possible to continuously and stably supply the raw material gas, and the efficiency of vaporizing the liquid raw material is increased. As a result, the supply of the raw material gas to the reaction furnace can be stabilized, and the composition of the crystal, There is an effect that the film thickness can be made uniform.

Further, in the liquid bubbling apparatus of the second aspect of the invention, the liquid level adjusting container for keeping the liquid surface of the liquid raw material constant is connected to any one of the chambers filled with the liquid raw material by a conduit. Therefore, in addition to the effect of the invention of claim 1, the bubbling process can always be made constant regardless of the consumption amount of the liquid raw material, and the supply of the raw material gas can be further stabilized. ..

Further, in the liquid bubbling apparatus of the third aspect of the present invention, the inside of the bubbler is divided by a vertical plate into a plurality of lateral chambers, and the upper chamber of the upstream side and the lower chamber of the divided chamber are divided. Since the bubblers are connected to each other by a communication pipe and the bubbler has a multi-layered structure, in addition to the effect of the invention of claim 1, the effect of further improving the efficiency of vaporization of the liquid raw material into the bubbles can be obtained. Play.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a liquid bubbling device according to an embodiment of the invention of claim 1. FIG.

FIG. 2 is a configuration diagram showing a liquid bubbling device according to another embodiment of the invention of claim 1.

FIG. 3 is a configuration diagram showing a liquid bubbling device according to still another embodiment of the invention of claim 1.

FIG. 4 is a configuration diagram showing a liquid bubbling device according to an embodiment of the invention of claim 2.

FIG. 5 is a configuration diagram showing a liquid bubbling device according to another embodiment of the invention of claim 2.

FIG. 6 is a configuration diagram showing a liquid bubbling device according to an embodiment of the inventions of claims 2 and 3.

FIG. 7 is a configuration diagram showing an example of a conventional liquid bubbling device.

[Explanation of symbols]

 1 Bubbler 2 Liquid Raw Material 3 Bubbling Gas Inlet Pipe 4 Raw Material Gas Outlet Pipe 5 Horizontal Flat Plate 6 Upper Horizontal Plate 8 Baffle Plate (Horizontal Plate) 10 Liquid Level Adjusting Container 13 Vertical Plate 14 First Chamber 15 Second Chamber 18 Communication Pipe

Claims (3)

[Claims] 1. A bubbler for containing a liquid raw material, a bubbler gas introduction pipe connected to the bubbler for introducing a bubbling gas into the liquid raw material, and a bubbler connected to the bubbler for feeding the raw material gas from the inside of the bubbler. A raw material gas outlet pipe to be led out, and a horizontal plate provided so as to divide the inside of the bubbler into a plurality of chambers in the vertical direction, and a horizontal plate having a large number of small holes for dividing bubbles from the bubbling gas inlet pipe into small chambers. A liquid bubbling device characterized by being provided. 2. A bubbler containing a liquid raw material, a bubbler gas introducing pipe connected to the bubbler for introducing a bubbling gas into the liquid raw material, and a bubbler connected to the bubbler to feed the raw material gas from the inside of the bubbler. A raw material gas outlet pipe to be led out, a horizontal plate provided so as to divide the inside of the bubbler into a plurality of chambers in the vertical direction, and a horizontal plate having a large number of small holes for dividing the bubbles from the bubbling gas inlet pipe into small chambers, A liquid bubbling device, comprising: a liquid level adjusting container which is connected to any one of the chambers filled with the liquid raw material by a conduit and keeps the liquid surface of the liquid raw material constant. 3. A bubbler containing a liquid raw material, a bubbler gas introduction pipe connected to the bubbler for introducing a bubbling gas into the liquid raw material, and a bubbler connected to the bubbler for feeding the raw material gas from the inside of the bubbler. A raw material gas outlet pipe to be led out, a horizontal plate provided so as to divide the inside of the bubbler into a plurality of chambers in the vertical direction, and a horizontal plate having a large number of small holes for dividing bubbles from the bubbling gas inlet pipe into small chambers, A vertical plate provided so as to divide the inside of the bubbler into a plurality of lateral chambers, and a communication pipe communicating between an upper part of the upstream chamber and a lower part of the downstream chamber divided by the vertical plate. A liquid bubbling device comprising: