JPS5920381B2 - Gas phase reactor - Google Patents

Description

[Detailed description of the invention] The present invention relates to a gas phase reactor.

In a vapor phase growth reaction, the flow conditions of the gas containing the reactant introduced into the reaction chamber have a large effect on the reaction efficiency, the purity of the reaction product, and the uniformity of the film thickness and film quality of the reaction product. For this reason, it is important to design a gas phase reactor with sufficient consideration given to the internal shape of the reaction chamber, the ejection direction of the introduced gas, and the like. Conventionally, when a reaction product is deposited on an object to be formed using a gas phase chemical reaction, a mixed gas in which a reaction component is added to a carrier gas serving as a base is added to an appropriate place where the object to be formed is placed. This was carried out by introducing gas into the reaction chamber heated to the reaction temperature via a gas injection device.

FIG. 1 shows a schematic cross-sectional view of a conventional gas phase reactor, and the flow of gas injected from a gas injection device 1 will be explained using the same figure. A mixed gas containing reaction components introduced from the gas inlet 2 at the lower part of the gas injection device 1 is ejected into the reaction chamber 4 from the gas outlet 3 on the opposite side to the gas inlet 2. Since the opening area of the gas outlet 3 is smaller than the opening area of the gas inlet 2, the injection velocity of the gas injected into the reaction chamber 4 is lower than the velocity of the gas introduced into the gas inlet 2. Becomes large. After the gas ejected into the reaction chamber 4 reaches the upper part of the Persian 5, it is guided to the lower part of the reaction chamber 4, and a part of the gas places the object 6 to be formed and reaches a temperature at which a gas phase chemical reaction can be carried out. It reaches onto the susceptor 8 whose temperature has been raised by the high frequency heating device 7. The susceptor 8 is rotated and supported by a susceptor support base 9. The mixed gas containing the reaction components is transferred to the formation target 6 and the susceptor 8.
The reaction is carried out on the surface and the reaction product is deposited. Thereafter, the gas flows toward the center of the susceptor 8 and is again engulfed by the gas ejected from the gas injection device 1 located at the center, and is again guided to the upper part of the persier 5. In other words, the flow of gas in the reaction chamber 4 in the conventional vapor phase growth apparatus is in a convection state from the center of the reaction chamber 4 toward the inner wall of the Persian 5, and the reaction components introduced into the reaction chamber 4 are Since only a part of the mixed gas contained reaches the formation target 6, the following drawbacks have occurred. 'i(1) The components of the convective gas that reaches the formation target 6 include the introduced mixed gas component, the by-product gas already generated by the gas phase reaction on the susceptor 8, and the impurities generated in the reaction chamber 4. Gas, for example, adsorbed gas and mixed gas components emitted from the susceptor 8 or the object to be formed 6 heated to a high temperature, and a component generated by the reaction between the object to be formed 6 and the object to be formed, such as SOS.
(Silicon on Sapphire) Contains various miscellaneous components such as aluminum oxide (At2O, AtO) generated by the reduction action of alumina's hydrogen carrier during crystal growth, so reaction products deposited on the formation target 6 are Purity does not necessarily mean that only the intended substance is clean.

(2) A part of the mixed gas introduced into the reaction chamber 4 passes through the gap between the inner wall of the Persian 5 and the susceptor 8, and is discharged to the outside of the device from the gas exhaust port 10 provided below the vapor growth device. be done.

The flow of the mixed gas in the reaction chamber 4 causes the object to be formed 6
Since it does not contribute to the deposition of reaction products on top, the efficiency of utilization of the introduced mixed gas is poor. The present invention provides a gas phase reactor capable of solving these drawbacks, and the present invention will be explained below using examples and drawings.

FIG. 2 shows a schematic cross-section of a gas phase reactor in one embodiment of the present invention.

The first gas injection device 11A injects a mixed gas containing a reaction component gas and a base carrier gas, and is disposed at the center of the bottom of the reaction device.
2A, and at the tip opposite to the gas inlet 12A,
A gas shielding plate 22A is disposed perpendicular to the gas introduction direction to close one end of the gas injection device 11A. Further, a plurality of gas injection ports 13A are provided on the side surface of the gas injection device 11A near the gas shielding plate 22A. The gas outlet 13A is opened so that its total opening area is smaller than the area of the gas inlet 12A.
The injection velocity of the mixed gas injected from 3A is considered to be higher than the velocity of the gas introduced into the gas introduction port 12A. A susceptor 18 serving as a base is disposed below the position of the gas injection port 13A, and the susceptor 18 is supported by a susceptor support stand 19 equipped with a rotation mechanism and rotates around the gas injection device 11A. Rotate horizontally as . Below the susceptor 18, the susceptor 18
A high frequency heating device 17 for raising the temperature to the reaction temperature is arranged parallel to the susceptor 18 and concentrically with the gas injection device 11A. In addition, on the bottom of the reaction chamber 14,
A gas outlet 20 is provided for discharging gas. Incidentally, on the side wall of the Persian 15 constituting the reaction chamber 14, a gas similar to the carrier gas in the mixed gas injected from the gas injection device 11A, or argon,
Does not contain reactive gases like inert gases such as helium,
A second gas injection device 11B is provided for injecting a gas that does not directly contribute to the reaction itself and does not have any adverse effects (hereinafter such a gas will be referred to as a non-reactive carrier gas in this explanation). There is. The gas injection device 11B is
A gas inlet 12B is provided at the tip outside the reaction chamber 14, and a gas shielding plate 22B is provided at the other end inside the reaction chamber 14 to seal off one end of the gas injection device 11B. The gas shielding plate 22B is arranged to face and be parallel to the gas shielding plate 22A of the gas injection device 11A. Gas shielding plate 22
A plurality of gas ejection ports 13B are opened in the gas injection device 11B near B. The total opening area of the gas outlet 13B is smaller than the area of the gas inlet 12B, and the injection velocity of the non-reactive carrier gas injected from the gas outlet 13B is such that the It is designed to be faster than the speed at which it is introduced. If the regions of the gas injection ports 13A and 13B of the gas injection devices 11A and 11B are referred to as gas injection tubes, the gas injection tubes of the gas injection devices 11A and 11B are arranged coaxially with each other. The gas flow within the reaction chamber 14 of the gas phase reactor having such a configuration will be explained.

First, to simplify the explanation, a case will be described in which gas is introduced only into the first gas injection device 11A. The injection direction of the mixed gas injected from the gas injection port 13A of the gas injection device 11A is the horizontal direction outward from the center of the reaction chamber 14, but the gas traveling direction inside the gas injection device 11A is from the bottom to the top. Because of the direction, the flow flows slightly upward from the horizontal direction due to inertia and advances over the upper part of the susceptor 18. The susceptor 18 places the formation target 16 and is heated to the reaction temperature, and the reaction components in the mixed gas injected from the rotating gas injection device 11A are transferred to the susceptor 18.
The reaction is carried out by raising the temperature above, and the reaction product is deposited on the formation object 16 and the susceptor 18.
Also, the gas flow of the mixed gas expands as it is heated,
As the density decreases, it acts in the direction of causing convection within the reaction chamber 14, and due to the gas injection direction (slightly upwards than horizontal), etc., after colliding with the inner wall of the Persian 15, it rises along the inner wall of the Persian 15. Convection flows downward from the top. Since the internal volume of the reaction chamber 14 is constant, the gas flow causes convection, but a flow rate of gas substantially equal to the flow rate of the introduced gas is discharged from the reaction chamber 14 through the gas outlet 20 to the outside of the apparatus. As described above, it can be seen that the gas flow causes convection within the reaction chamber 14 when gas is introduced only into the gas injection device 11A.

Next, a description will be given of the gas flow in the reaction chamber 14 when gas is introduced into the first gas injection device 11A and a non-reactive carrier gas is also introduced from the second gas injection device 11B.

The non-reactive carrier gas introduced from the gas inlet 12B of the gas injection device 11B travels from above to below in the reaction chamber 14, and then flows into the reaction chamber 14 from a plurality of gas ejection ports 13B in a lateral gas flow. It is ejected at a high speed. The gas flow of the non-reactive carrier gas flows over the susceptor 18 so as to oppose the gas flow of the mixed gas injected from the gas injection device 11A, and the upper part of the reaction chamber 14 is constantly filled with clean non-reactive carrier gas. flows to Thereafter, the gas flows down the reaction chamber 14 along the inner wall of the gas chamber 15 and is then discharged from the gas outlet 20 to the outside of the apparatus.
In other words, the effects of the carrier gas B injected into the reaction chamber 14 from the gas injection device 11B are: (1) the effect of a curtain on the mixed gas (same as a commonly seen air curtain); and (2) the internal volume of the reaction chamber 14. The purpose of this is to effectively reduce
Convection is prevented, and the mixed gas containing the reaction components flows parallel to and close to the susceptor 18. The gas phase reaction apparatus of the present invention allows the gas flow within the reaction chamber to be freely controlled by the flow rate ratio of the mixed gas flow rate and the non-reactive carrier gas or the total gas flow rate.

Actually, as a ratio of the mixed gas injected from the first gas injection device 11A and the non-reactive carrier gas injected from the second gas injection device 11B, the non-reactive carrier gas is 1 to the mixed gas. A value between .5 and 4 times was appropriate.

In addition, the total flow rate of the mixed gas and non-reactive carrier gas should be 2 to 6 times the internal volume of the reaction chamber 14 per minute in terms of uniformity of the reaction products. It was good and warm. Due to the effects of the present invention described below, the gas phase reactor of the present invention has great value industrially, particularly in the semiconductor industry.

(1) Since the gas flow flowing over the susceptor and the object to be formed is parallel and the flow velocity is high, it is possible to deposit and form a reaction product with good uniformity in film thickness and film quality with good reproducibility.

(2) Since the gas flow of the mixed gas containing the reaction components flowing over the susceptor and the object to be formed does not form convection, the by-product gas generated by the reaction or the impurities in the adsorbed gas emanating from the object to be formed or the susceptor are generated by the reaction. It is less likely to be incorporated into things.

That is, since it is possible to deposit and deposit a clean reaction product with little autoping or out-diffusion, when growing a substrate and a different material, such as growing silicon on a sapphire substrate, by vapor phase, This is particularly effective since it is possible to obtain a deposited layer with a steep impurity distribution.

(3) Since the gas flow of the mixed gas containing the reactive components flows close to the upper surface of the susceptor, the reaction efficiency of the reactive component gas is improved, and most of the reactive components contribute to the reaction, resulting in deposition. The formation speed is faster than before. That is,
Because the deposition rate is high, the time required for deposition can be reduced compared to conventional equipment, and the electric power required to heat the reaction temperature can be reduced.
Resources such as reactants and carrier gas can be saved. (4) When trying to obtain the same deposited layer with the same reaction rate as before, in addition to lowering the reaction temperature, it is also possible to reduce the concentration of the mixed gas containing the reaction components, so it is possible to reduce the amount of toxic substances. The danger is reduced in reactions involving combustible materials or flammable materials.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a conventional gas phase reactor, and FIG. 2 is a schematic cross-sectional view showing an embodiment of the gas phase reactor of the present invention. 11A, 11B... Gas injection device, 12A, 1
2B...Gas inlet, 13A, 13B...
...Gas outlet, 14...Reaction chamber, 15...
... Persian, 16 ... Formation object, 17
...High frequency heating device, 18 ... Susceptor, 19 ... Susceptor support base, 20 ...
...Gas exhaust port, 22A, 22B...Gas shielding plate.

Claims (1)

[Claims] 1. A base on which an object to be formed by vapor phase growth is placed;
a first gas injection device having a gas ejection port for ejecting a reactive gas to the object to be formed; and a first gas injection device installed above the first gas injection device to emit a non-reactive gas in the direction of the main surface of the object to be formed. A gas phase reaction device characterized in that a second gas injection device provided with an ejection port is formed in a reaction chamber. 2 The parts of the first and second gas injection devices provided with the ejection ports are formed of tubular bodies, are arranged opposite to each other, and have one end of the tubular body having an area larger than the opening area of one end of the tubular body. 2. The gas phase reactor according to claim 1, further comprising a gas shielding plate having a gas shielding plate.