JPS5926328B2 - Gas phase reactor - Google Patents

Description

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

In vapor phase growth reactions, 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 by taking into account the shape of the reaction chamber, the direction of the gas to be introduced, etc. Conventionally, gas-phase chemical reactions are used to generate reaction products. When depositing on the object to be formed,
This was carried out by introducing a mixed gas in which reactive components were added to a base carrier gas through a gas injection device into a reaction chamber in which the object to be formed was installed and the temperature was raised to an appropriate reaction temperature.

FIG. 1 shows a schematic cross-sectional view of a conventional vapor phase growth apparatus, and the flow of gas injected from the gas injection apparatus 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. also becomes a dog. 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 is heated to a temperature at which the object to be formed 6 is placed and a gas phase chemical reaction j is carried out. The heat reaches the susceptor 8 heated 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 reacts on the formation object 6 and the susceptor 8, and the reaction products are deposited thereon.

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. 5
That is, 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 gas does not contain the reaction components introduced into the reaction chamber 4. However, only a portion of the mixed gas reaches the formation target 6, resulting in the following drawbacks.

(1) Components of the convective gas that reaches the formation target 6 include the introduced mixed gas component, by-product gas already generated by gas phase reaction on the susceptor 8, and impurity gas generated in the reaction chamber 4, for example. Components generated by the reaction between adsorbed gas and mixed gas components emitted from the susceptor 8 and the formation target 6 heated to high temperatures and the formation target 6, such as hydrogen in alumina during SOS (silicon on sapphire) crystal growth. Since it contains various miscellaneous components such as aluminum oxide (Al2O, AlO) generated by the reduction action in the carrier, the purity of the reaction product deposited on the object 6 is not necessarily limited to the target substance. It doesn't necessarily mean something 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 apparatus from the gas outlet 10 located below the vapor growth apparatus. Ru.

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 aimed at solving these drawbacks, and the present invention will be explained below with reference to Examples and drawings.

FIG. 2 shows a schematic cross-sectional view of a gas phase reactor showing one embodiment of the present invention.

The gas injection device 11 is disposed at the center of the lower part of the reaction device, and has a gas inlet 12, and a gas shielding plate 22 is provided at the tip opposite to the gas inlet 12, and is perpendicular to the gas introduction direction. It is arranged so as to close one end of the injection device 11.
Further, a plurality of gas ejection ports 13 are provided on the side surface of the gas injection device 11 near the gas shielding plate 22 . The injection speed of the gas injected into the reaction chamber 14 from the gas outlet 13 is lower than that of the gas inlet 12 because the total opening area of the gas outlet 13 is smaller than the opening area of the gas inlet 12.
The rate of introduction of the mixed gas of the reaction components and the base carrier gas is higher than the rate of introduction of the mixed gas. Therefore, the mixed gas introduced through the gas inlet 12 travels upward from below the gas injection device 11, and then is injected from the gas injection port 13 into the reaction chamber 14 in a substantially lateral direction at a high speed. Most of the injected mixed gas is heated to a high-frequency heating device 17 at a temperature at which the formation target 16 is placed and a gas phase chemical reaction is carried out.
The heat reaches the susceptor 18, which serves as a base, and is heated by this process. The susceptor 18 is supported by a susceptor support base 19 and rotates horizontally around the gas injection device 11. The reaction component in the mixed gas is the object to be formed 1
The reaction is carried out on the susceptor 18 and the reaction product is deposited. Thereafter, the gas flow traveling on the susceptor 18 collides with a gas flow control wall 21 as a gas flow control section disposed near the inner wall of the Persian 15. The gas flow control wall 2
1 has a partition wall part 23 in the shape of a truncated right cone having openings with a large diameter and a small diameter, and a partition wall part 24 in the shape of a disk having a circular through hole in the small opening of the partition wall part 23. The partition wall 23 has a large diameter opening facing the lower surface of the reaction chamber 14. The mounting height of the large diameter opening of the gas flow control wall 21 is equal to the mounting height of the susceptor 18 and the gas injection device 11.
It is between the highest height position of . Also, the gas flow control wall 2
The elevation angle of the right circular truncated cone shape of the partition wall portion 23 is preferably 45 walls or less. The diameter of the opening of the partition wall 24 is suitably between % and 1 times the outer diameter of the susceptor 18. The gas flow that collides with the gas flow control wall 21 and the inner wall of the Persian 15 is converted from a lateral flow to a downward flow and is transferred to the susceptor 18.
It passes through the gap formed by the inner wall of the gas phase reactor 15 and is discharged from the gas phase reactor from the gas exhaust port 20 located below the reactor. That is, the gas flow control wall 21 has the effect of preventing or suppressing the gas flow on the susceptor 18 from becoming convection. Note that the gas flow control section may be an exhaust port provided on the side wall of the Persian 15 other than the one in this embodiment.

The effects of the gas phase reactor of the present invention will be described below.

(1) The mixed gas containing the reaction components introduced into the reaction chamber 14 does not cause convection as described in the conventional example, and is constantly supplied with fresh mixed gas due to the effects of the gas flow control wall and the gas injection device. Since it covers the object to be formed and the susceptor 18, it is possible to obtain a clean reaction product with good uniformity. In other words, it is possible to prevent autodoping from the object to be formed and the incorporation of impurities from out-diffusion, susceptors, or Persians, so that it is possible to prevent the vapor phase growth of a substrate and a foreign material, such as growing silicon on a sapphire substrate. It is particularly effective for (2) Most of the mixed gas containing reaction components introduced into the reaction chamber flows near the object to be formed and the susceptor, so most of the reaction components react, so the reaction products are efficiently transferred onto the object to be formed. Can be deposited.

(3) As described in item (2) above, since most of the mixed gas flows near the object to be formed and the susceptor, when the reaction products are limited to a predetermined amount, the reaction temperature and the reaction in the mixed gas If the reaction is carried out under the same conditions as the conventional device, such as component concentration and mixed gas flow rate, the deposition rate will be higher than that of the conventional device, and the time required for deposition can be shortened, so even if the reaction products are reduced, the reaction will be the same as the conventional device. can be deposited.

In addition, because the deposition rate is high, the same deposited layer as that obtained with conventional equipment can be obtained even if the reaction temperature is lowered, so autodoping and outdiffusion from the object to be formed can be suppressed. A deposited layer with a steep impurity distribution can be obtained. 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 gas mixture containing the reactants, thereby reducing the danger in reactions involving toxic or flammable substances. (4) As described in item (3) above, with the apparatus of the present invention, it is possible to obtain the same deposited layer as in the conventional method in a short time. It becomes possible to save resources such as gas.

As described above, the gas phase reactor according to the present invention is of high value industrially, particularly in the semiconductor industry.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a conventional gas phase reactor, and FIG. 2 is a schematic cross-sectional view of an embodiment of the gas phase reactor of the present invention. 11...Gas injection device, 12...Gas inlet, 13...Gas spout, 14...
・Reaction chamber, 15... Persian 16...
...Object to be formed, 17...High frequency heating device, 1
8...Base, 19...Susceptor support stand, 20...Gas exhaust port, 21...Gas flow control unit, 22...・Gas shielding plate.

Claims (1)

[Claims] 1. A base on which an object to be formed by vapor phase growth is placed;
a gas injection device having a gas jetting port for ejecting a reaction gas to the object to be formed; and a gas flow control unit that guides the reaction gas so that the reaction gas that has passed through the object does not come into contact with the object again. A gas phase reactor characterized in that a gas phase reactor is formed in a reaction chamber. 2. The gas injection device is made of a tubular body, and has a gas shielding plate at one end of the tubular body having an area larger than the opening area of one end of the tubular body, and a plurality of gas shielding plates are provided on a side wall of the tubular body near the gas shielding plate. 2. The gas phase reactor according to claim 1, characterized in that the device has two gas jet ports. 3. The gas phase reactor according to claim 1, wherein the gas flow control section is formed of a tubular body with both ends open so that the opening area becomes larger toward the bottom, and is provided on the wall of the reaction chamber. .