JPS612344A - Vapor growth equipment - Google Patents

Abstract

PURPOSE:To uniformize the film thickness of a vapor growth layer made to grow in vapor phase by a method wherein the air flow of raw gas is turned into a turbulent air flow by disposing a sample or by disposing a fluid obstacle and the vapor growth layer is formed on the sample in the turbulent air flow. CONSTITUTION:A source chain bar 3 and a liner tube 5 are provided in the interior of the reaction tube of the epitaxial growth equipment. The source chain bar 3 is provided with a source boat 6, wherein magnesium chloride is charged, and the gaseous magnesium chloride is made to generate by applying heat. This gas is included in the air flow of hydrogen gas and is sent onto a growing substrate 20 placed on a wafer boat 12 and a vapor growth is performed. Here, a block 21 is disposed in front of the growth substrate 20 in such a structure that the flow velocity of fluid gas is obstructed. This block 21 makes a turbulent air flow generate in the flow direction of the gas. As a result, the flow rate of the gas in the reaction tube is uniformized and the thickness of the film made to grow in vapor phase becomes uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION fal Technical Field of the Invention The present invention relates to a vapor phase growth apparatus, and more particularly to the configuration of a vapor phase growth apparatus that performs uniform vapor growth on a growth substrate.

(bl Technology background) In recent years, the vapor phase growth process has become extremely important in the manufacturing process of semiconductor devices. In particular, epitaxial growth is a process in which a single crystal with a desired resistivity and thickness is grown on a mirror-finished single crystal substrate. Since it can be grown in the same crystal direction, it is widely used in the manufacturing process of semiconductor devices.

In particular, magnesia spinel, which has recently begun to be used, is a high-voltage insulator, and it is known that high quality silicon can be grown on silicon substrates, and high quality silicon can also be grown on magnesia spinel. For this reason, it is attracting attention in various fields because it can be applied to dielectric isolation of semiconductor devices, but when growing it epitaxially, it is necessary to have a uniform film thickness and uniform properties over the entire surface of the film. There is a need for a film forming method that meets this demand.

(C) Prior Art and Problems The conventional epitaxial growth method will be explained below with reference to the drawings.

As a conventional example, a method of epitaxial growth of a magnesia spinel layer will be described, but it can be generally applied to a horizontal epitaxial growth furnace.

Figure 1 shows a conventional epitaxial growth apparatus for magnesia spinel. 1 is a heating furnace, and the heating method of this heating furnace is divided into three sections, each having independent temperature zones 1a, 1b, and 1c. 2 is a reaction tube made of quartz, and inside this reaction tube is a rectangular source chamber 3 that is partitioned into upper and lower layers, and There is a liner tube 5 that prevents objects from adhering directly.

In the upper stage 4 of this sauce chamber, there is a source port 6 loaded with magnesium chloride (MgC12), which is heated to about 800°C in the relatively high temperature part of the heating furnace 1b, and gaseous magnesium chloride is released. generated.

This magnesium chloride gas is mixed with the hydrogen gas flow introduced from the gas introduction hole 7 attached to the upper end of the source chamber 3 and sent onto the growth substrate 8 .

On the other hand, in the lower part of the source chamber 3, there is a source port 9 loaded with metal aluminum (AI), which is heated at 500° C. in a relatively low temperature zone 1a of the heating furnace.

Gas introduction holes 1 are also located at the lower end of the source chamber 3.
1 is installed, and a mixed gas of hydrogen gas and hydrogen chloride gas (HCI) flows through this introduction hole, and these gases and aluminum react chemically to form aluminum chloride gas. This gas is also sent onto the growth substrate 8.

Hydrogen gas and carbon dioxide gas (Co 2 ) are introduced as a mixed gas into the reaction tube through the gas introduction hole 1o, and this gas is similarly sent onto the growth substrate 8 through the outside of the source chamber 3.

The growth substrate is placed on the wafer boat 12, and the temperature ranges from 900'C to 100'C in the highest zone 1c of the heating furnace.
Heated at 0°C.

On this growth substrate, the following chemical reaction proceeds due to the above gas atmosphere and heating temperature.

MgCl2+2AICIFl+11co2+4H2=
FIGo ・812 0 3 + 8HC1+
4CO In this manner, a film of magnesia spinel (MgO.A1203) is grown on the growth substrate.

The conventional vapor phase growth apparatus in which this chemical reaction is carried out is horizontal, and the reaction tube is also horizontal, so the flow rate of the gas flowing inside the reaction tube is mainly large in the center of the reaction tube, and vice versa. There is a drawback that the flow velocity is low near the wall of the reaction tube and the flow rate is not constant.

Therefore, the amount of gas in contact with the growth substrate surface is large at the center of the growth substrate, and decreases toward both ends of the growth substrate. If we take a cross-section of the epitaxially grown film along section a-a, we can see that the film is grown with non-uniform thickness in the diametrical direction of the wafer, as shown by the p-line in Figure 2 (2). The thickness of the grown film was reduced by about 20% at both ends compared to the thickness at the center, which was extremely inconvenient in practice.

fdl Purpose of the Invention In view of the above-mentioned drawbacks of the conventional vapor phase growth apparatus, the present invention aims to increase the thickness of the film formed in the vapor phase by making the gas flowing in the reaction tube turbulent without significantly changing the structure of the conventional vapor phase growth apparatus. The purpose of the present invention is to provide a manufacturing method that achieves uniformity.

fel Structure of the Invention According to the present invention, the object is to provide a horizontal heating furnace, and a horizontal vacuum container that has an inflow hole and an outflow hole for a material gas inside the furnace and generates an airflow of a certain amount of the material gas. In a horizontal vapor phase growth apparatus, the vacuum vessel is equipped with a source chamber and a sample placement stage, and the sample is heated in an air flow of the material gas to perform vapor phase growth. The sample is placed in a turbulent flow, or a fluid obstruction that obstructs the flow of the material gas is placed near the sample to make the flow of the material gas turbulent. This can be achieved by providing a vapor phase growth apparatus characterized by forming a growth layer.

(f) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows the inside of the reaction tube in the vapor phase growth apparatus of the present invention.

The overall structure of the vapor phase growth apparatus is not particularly different from the conventional structure, and in order to equalize the flow rate of gas in the reaction tube, a fluid obstruction is installed to create turbulence in the flow direction of the material gas. ing.

FIG. 3 (1) is a schematic diagram of the side surface of the reaction tube, and the third
Figure (2) is a schematic plan view of the reaction tube. On the upstream side of the reaction tube where the gas flows in, there is a block 2 in front of the growth substrate 20 with a structure that obstructs the flow rate of the fluid gas.
1 is installed.

The size of this block can be determined by determining the most appropriate size to reduce the flow velocity of the fluid gas or to generate turbulence, but for example, a quartz block with a size of about 75n+m x 50mm x 5mm is used. be able to.

The magnesia spinel produced in this way by vapor phase epitaxy had a thickness reduced by 4% in the center compared to the thickness of the magnesia spinel layer produced by the conventional manufacturing method (i.e., slightly However, the film thickness distribution becomes the q-line film thickness distribution shown in Figure 2 (2), and the film thickness at both ends is about 8% different from the film thickness at the center. will be improved until it is recognized.

In the examples, a small rectangular parallelepiped was used as the block, but if there is no particular restriction on the shape and the flow of gas flowing inside the reaction tube is not significantly disturbed, blocks of other shapes such as a cylinder may also be used. The material of the fork may be any material that does not affect the composition of the growth atmosphere, such as quartz, graphite, graphite coated with silicon carbide, ceramic, and silicon.

FIGS. 4 to 6 are cross-sectional views of the growth substrate portion of the reaction tube, and FIG. In FIG. 5, the block 24 corresponding to that in FIG. 4 has a chevron shape, and in FIG. This is an example in which they are installed on both sides of the block 26 on the top surface.

In the above-mentioned vapor phase growth method, in order to grow a film with a uniform thickness on the substrate, it is said that creating a turbulent flow of the material gas will yield better results. When placed on the boat 12, the growth substrates can be placed on the boat 12 by arranging them not only parallel to the direction of the airflow (or by arranging them at an angle to the direction of the airflow, but also by arranging them approximately perpendicular to the direction of the airflow). It is possible to make the gas flow turbulent, and a similar effect can be obtained.

(gl) Effects of the Invention As explained in detail above, the present invention uses a vapor phase growth method to grow a film with a uniform thickness on a semiconductor substrate, thereby improving the performance of the semiconductor substrate. There are some things that have a great effect on improvement.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional vapor phase growth apparatus, Fig. 2 is a phase diagram showing the thickness distribution of a film formed on a growth substrate, and Figs. FIG. 2 is a cross-sectional view explaining the invention in detail. In the figure, 1 is a heating furnace, 2 is a reaction tube, 3 is a sauce chamber, 4 is the upper stage of the sauce chamber, 5 is a liner tube, and 6
．． 9 is source po 1~. 7 is a gas introduction hole, 8 is a growth substrate, 10.11 is a gas introduction hole, and 12 is a wafer of the growth substrate.
Boat, 20.23 is growth substrate, 21.22.24.2
5.26 is a block.

Claims (1)

[Claims] There is a horizontal heating furnace, and a horizontal vacuum container inside which has inflow and outflow holes for material gas to generate a certain amount of gas flow, and inside the vacuum container there is a source chamber and a sample. In a horizontal vapor phase growth apparatus that is equipped with a placement table and performs vapor phase growth by heating the sample in an airflow of the material gas, the sample is placed in the vacuum container or in the vicinity of the sample. A vapor growth apparatus characterized in that a fluid impediment that obstructs the airflow of the material gas is arranged to make the airflow of the material gas turbulent, and a vapor growth layer is formed on the sample in the turbulence. .