JPS5940905B2 - Vapor phase growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vapor phase growth apparatus for obtaining a clean reaction product with uniform film thickness and film quality in a vapor phase growth reaction.

When depositing a reaction product onto a target object using a gas phase chemical reaction, a mixed gas consisting of a reaction component gas mixed with a base carrier gas is placed on the target object and maintained at the reaction temperature. This is done by introducing the gas into a reactor using a gas injection device.

An example of this conventional vapor phase growth apparatus will be explained with reference to FIGS. 3 and 4. FIG. 3 shows a gas injection device 1 used in a conventional vapor phase growth apparatus.

This gas injection device 1 has a tubular shape, has a gas inlet 2 at the lower part, and has a gas ejection part 3 having a pipe diameter that gradually becomes thinner at the tip. A gas spout 4 is provided at the tip of the gas spout 3 . FIG. 4 shows a schematic cross section of a vapor phase growth apparatus using the gas injection apparatus 1, and will be explained based on the flow of gas. Reference numeral 5 denotes a persian forming a reaction chamber 6, in which the gas ejection device 1 is disposed at the center of the reaction chamber 6.

T is the target of the reaction, and is placed on the susceptor 8, and the temperature is raised to a temperature at which a gas phase chemical reaction occurs. Reference numeral 9 denotes a through hole provided in the center of the susceptor, to which the gas ejection port 4 of the gas ejection device 1 corresponds.

Reference numeral 10 denotes a gas exhaust port provided below this vapor phase growth apparatus.

A mixed gas of a reaction component gas and a carrier gas is introduced from the gas inlet 2 of the gas injection device 1, as shown by the solid arrow in FIG. is injected into. After the injected mixed gas reaches the upper part of the Persian 5, it is guided to the lower part of the reaction chamber 6, and a portion of the mixed gas reaches the object T on the susceptor 8. Further, the remaining part of the mixed gas passes through the gap between the susceptor 8 and the Persian 5 and is discharged from the gas exhaust port 10 located below the vapor growth apparatus. The mixed gas that has reached the susceptor 8 reacts on the target object T and the susceptor 8, and a reaction product is deposited on the target object T. The mixed gas after the reaction flows toward the center of the susceptor 8, and is guided again to the upper part of the Persian 5 together with a new mixed gas by the gas injection device 1 located in the center of the susceptor 8. It will be destroyed. That is, in this conventional vapor phase growth apparatus, the flow of the mixed gas is in a convection state in which the flow moves from the center of the reaction chamber 6 upward and further outward. As a result, it had the following drawbacks. First, objective 7
The components of the convective gas that reach the top have already undergone a gas phase reaction with the new mixed gas introduced into the gas injection device 1 through the susceptor 8, and the by-product gas and reaction chamber 6 generated thereby. It consists of impurity gases generated. This impurity gas is, for example, aluminum oxide (Al2O3) generated by hydrogen carriers on a sapphire (Al2O3) substrate during silicon-on-sapphire crystal growth.
．． These include gases containing AlO) and the like, and adsorbed gases emitted from the object 7 and susceptor 8 that are kept at high temperatures. In this conventional apparatus, since the above-mentioned impurities are incorporated into the reaction product deposited on the object 7, it is difficult to obtain a clean reaction product deposited layer. Furthermore, part of the mixed gas introduced into the reaction chamber 6 becomes convection as described above, and the remaining part is discharged from the gas outlet 10 at the bottom of the apparatus without contributing to a gas phase chemical reaction.
The utilization efficiency of the introduced mixed gas was poor, and therefore the rate of deposition due to reaction was slow.

In order to solve the above-mentioned conventional drawbacks, the present invention provides a vapor phase growth apparatus that controls the flow of gas introduced into a reaction chamber to obtain a uniform and clean reaction product. One embodiment will be explained with reference to FIG.

FIG. 1 shows a gas injection device 11. FIG.

This gas injection device 11 has a double pipe structure including an outer gas injection pipe 11a and an inner gas injection pipe 11b, both of which are straight pipes. Further, the central axes of the outer gas injection pipe 11a and the inner gas injection pipe 11b are aligned, and the lower portions of each of the outer gas injection pipes 11a and 11b are gas inlet ports 12a and 12b.
It becomes b. At the tip of the outer gas injection pipe 11a, a disk-shaped gas shielding plate 13a larger than this pipe diameter is provided to close the pipe, and on the wall of the outer gas injection pipe 11a near the gas shielding plate 13a, A plurality of through holes are provided, and these are used as gas jet ports 14a. The inner gas injection pipe 12
b is longer than the outer gas injection pipe 11a, and its upper tip protrudes upward through the gas shielding plate 13a, and is fixed by welding at this penetrating portion to provide airtightness, so that the inner and outer gas injection pipes are integrated. It is becoming. Inner gas injection pipe 12b
A disk-shaped gas shielding plate 13b is provided at the tip of the tube to close the pipe, and this gas shielding plate 13b is parallel to the gas shielding plate 13a of the outer gas injection pipe 11a and has a large diameter. A plurality of through holes are provided in the tube wall of the inner gas injection tube 11b between the two gas shielding plates 13a and 13b, and these are used as gas injection ports 14b. The hole diameter and number of the gas outlet 14a and the gas outlet 14b are determined in consideration of the gas flow rate introduced from the gas introduction ports 12a and 12b, and the flow velocity of gas ejected from these gas outlet ports 14a and 14b, respectively. It can be determined freely. Further, the interval between the two gas shielding plates is determined by the gas jetting port 14b of the inner gas jetting pipe 11b.
A suitable size is 2 to 10 times the pore diameter. Next, FIG. 2 shows a cross section of a vapor phase growth apparatus using the gas injection apparatus 11. 1
Reference numeral 5 denotes a quartz or water-cooled metal Persian that forms a reaction chamber 16, in which the gas injection device 11 is disposed at the center of the reaction chamber 16.

A susceptor 18 is provided around the gas injection device 11 and below the positions of the gas injection ports 14a and 14b to place the reaction object 17 and maintain the reaction temperature, for example, 950 to 1050'C. do the work.

This susceptor 18 is held at the above height by a susceptor holder 19 having a rotation mechanism, and is rotated in the horizontal direction. Reference numeral 20 denotes a gas exhaust port disposed below this vapor phase growth apparatus.

Here, the gases used will be explained using a silicon on sapphire (SOS) crystal growth reaction as an example.

This SOS crystal growth is caused by silane (S), which is a reactive component gas.
sapphire (AI) using the thermal decomposition reaction of iH4) gas
2O3) A method for growing silicon single crystals on a substrate. At this time, a carrier gas is used to dilute the reaction component gas to an appropriate concentration and to inject it at an appropriate flow rate, and is used as a mixed gas. As a carrier gas, use a component that does not have a negative effect on the vapor growth reaction, such as hydrogen gas that has been purified to a high purity through a palladium permeable membrane, or high-purity helium (He) or high-purity argon (Ar).
Rare gases such as In Figure 2, the flow of a mixed gas of a reaction component gas and a carrier gas is indicated by a solid arrow, and a gas having the same composition as the carrier gas (hereinafter referred to as carrier component gas) is shown.
The flow is shown by dashed arrows. Outer gas injection pipe 11a
The mixed gas is introduced into the respective tubes from the gas inlet 12a of the inner gas injection tube 11b, and the carrier component gas is introduced into the respective tubes from the gas inlet 12b of the inner gas injection tube 11b. The gas is vigorously ejected into the reaction chamber 16 as a slightly upward gas flow.
Here, the direction of the flow of ejected gas is slightly upward because
The gas flow in the inner and outer gas injection pipes 11a, 11b is from bottom to top, and the opening direction of each gas injection port 14a, 14b is horizontal, so the gas flow is in this gas injection port 14a. , 14b by nearly 900, and it is thought that at this time, an inertial action of the fluid occurs, resulting in a slightly upward gas flow. In this way, each gas outlet 14a
, 14b flows on the susceptor 18 from its center outward. Outer gas injection pipe 11a
The reaction component gas in the mixed gas injected from the gas outlet 14a reacts on the heated reaction object 17,
The vapor phase growth reaction progresses by depositing the product on the reaction object 17. The above-mentioned mixed gas reacts with the reactive component gases and flows in close proximity to the high-temperature susceptor 18, so it is heated and expands in volume, reducing its density, and the gas injection direction mentioned above is slightly upward. Due to these factors, the susceptor 18 rises near the outer periphery and receives a force in a direction that causes convection within the reaction chamber 16. On the other hand, the carrier component gas is injected from the gas outlet 14b of the inner gas injection pipe 11b, and on the susceptor 18 there is a two-layer gas flow with the mixed gas, i.e., the lower susceptor 11.
There is a mixed gas flow in the vicinity of 8, and an upper carrier component gas flow. The latter carrier component gas stream has a lower temperature than the heated mixed gas stream and is therefore heavier than the mixed gas stream, so it suppresses the upward force of the mixed gas mentioned above and suppresses the by-product gas and other gases caused by the reaction. Prevents convection of mixed gas containing impurities. At this time, since the diameter of the gas shielding plate 13b of the inner gas injection pipe 11b located above is larger than the gas shielding plate 13a of the outer gas injection pipe 11a, the initial slightly upward injection direction due to the inertia of the carrier component gas is The shielding plate 13b provides a horizontal direction, which acts as a force to suppress the rise of the above-mentioned mixed gas. Furthermore, the upper part of the reaction chamber 16 is constantly filled with the clean carrier component gas ejected from the gas outlet 14b, which prevents convection of the mixed gas and prevents the reaction chamber 16 from absorbing the mixed gas, that is, the reaction component gas.
6 can be made smaller. Each of the gases is then discharged out of the apparatus from a gas outlet 20 provided below the reaction chamber 16. Here, the gas flow of the mixed gas in the reaction chamber 16 changes depending on the respective flow rates and flow rates of the introduced mixed gas and carrier component gas.

That is, the gas flow of the mixed gas in the reaction chamber 16 is
By changing the flow rate and flow velocity of the carrier component gas injected from 4b, it is possible to control the carrier component gas to an optimum state. According to experiments, the ratio of the flow rates of the mixed gas introduced into the outer gas injection pipe 11a and the carrier component gas introduced into the inner gas injection pipe 11b is between mixed gas flow rate/carrier gas flow rate -0.5 to 2. was also suitable for controlling the progress of the reaction. In addition, the total flow rate of the mixed gas and carrier component gas per minute is 2 to
The uniformity of the reaction product was good at 6 times. According to the above embodiment, the susceptor 18 and the reaction target 17
Since the flow of the mixed gas containing the reactant gases above the reactor can be freely controlled, optimal reaction conditions can be achieved, and reaction products with uniform film thickness and quality can be deposited with good reproducibility. Is possible.

In addition, since the carrier component gas flows horizontally in the upper layer of the mixed gas and the upper part of the reaction chamber 16 is filled with the carrier component gas, the mixed gas is prevented from becoming a convection, and the effective content for the mixed gas is Since the product is small,
Impurity components in the by-product gas generated by the reaction, the reaction object 17, and the adsorbed gas emitted from the susceptor 18 can be quickly removed from the reaction object 17, and these impurities can be removed from the reaction object 17. less of it is incorporated into the reaction products deposited on the surface. That is, a clean reaction product deposited layer with little outward diffusion can be obtained. Furthermore, since the effective internal volume of the reaction chamber 16 is small and the mixed gas containing the reaction component gas flows close to the susceptor 18, most of the introduced reaction component gas contributes to the reaction and the reaction efficiency is improved. Therefore, it has become possible to increase the deposition rate of reaction products. Although the case of silicon-on-sapphire crystal growth has been described above, similar effects can be achieved with other crystal growth, high-resistance epitaxial growth, etc. As described above, the present invention provides an internal gas injection system for a gas injection device which includes a table on which a reaction target is placed in a reaction chamber, and which consists of two tubes arranged in a double-tube shape at the center of the table. The tube passes through a first gas shielding plate provided to block the tip of the outer gas injection tube and is fixed together with the second gas shielding plate provided to block the tip of the inner gas injection tube. a gas shielding plate and the first
By providing a gas outlet on the side of the inner gas injection tube between the gas shield plate and the side of the outer gas injection tube, the flow of gas introduced into the reaction chamber can be easily controlled. Possible-C: Providing an industrially superior vapor phase growth device that can vapor phase grow homogeneous and clean reaction products with good reproducibility, and can also increase the deposition rate to improve reaction efficiency. It is something to do.

[Brief explanation of drawings]

Fig. 1 shows a gas injection device in one embodiment of the vapor phase growth apparatus of the present invention, A is a plan view thereof, B is a front view, Fig. 2 is a sectional view of the main part of the same vapor phase growth apparatus, and Fig. 3 FIG. 3A is a plan view of a conventional gas injection apparatus, FIG. 3A is a front view thereof, and FIG. 11...Gas injection device, 11a...Outer gas injection pipe, 11b...Inner gas injection pipe, 1
3a, 13b... Gas shielding plate, 14a, 14b
...Gas outlet, 16...Reaction chamber, 1
8... Susceptor.

Claims (1)

[Scope of Claims] 1. A stage for placing a reaction object is provided in a reaction chamber, and a carrier component gas is injected from a gas injection device consisting of two pipes arranged in a double-tube shape at the center of the stage. The inner gas injection tube through which the reaction component gas flows passes through a first gas shielding plate provided to block the tip of the outer gas injection tube through which the reaction component gas flows, and is fixed to the inner gas injection tube to block the tip of the inner gas injection tube. A gas ejection port is provided on a side surface of the inner gas injection pipe and a side surface of the outer gas injection pipe between the second gas shielding plate and the first gas shielding plate, which are provided so that the gas is ejected from the outer gas injection pipe. A vapor phase growth apparatus characterized in that a flow of a reaction component gas is controlled by a flow of a carrier component gas ejected from the inner gas injection pipe. 2. The vapor phase growth apparatus according to claim 1, wherein the diameter of the second gas shielding plate is larger than the diameter of the first gas shielding plate.