JPS62149883A - Chemical vapor deposition device - Google Patents

Abstract

PURPOSE:To form a stable vapor deposited film having uniform quality over the entire surface of a substrate by constituting the titled device in such a manner that the gaseous raw material introduced into a reaction chamber does not collide against the gaseous raw material making natural convection in the reaction chamber. CONSTITUTION:A gaseous raw material supply member is constituted of a gaseous raw material ejection pipe 22 having a Venturi shape, a jacket 23 on the outside thereof and a joint pipe 24. A tray-shaped flow regulating plate 18 is mounted around the substrate 9. The tray-shaped flow regulating plate 18 consists of a horizontal part 18b in proximity to the periphery of the substrate 9 and a peripheral edge part 18a curving upward. The gaseous raw material 12 is supplied via a nozzle holder 21 to the pipe 22.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a chemical vapor deposition apparatus used, for example, for forming a film on a substrate.

Generally, when forming a film of silicon carbide, silicon nitride, etc. on the surface of graphite, metal, etc. by chemical vapor deposition, a chemical vapor deposition apparatus as shown in the cross-sectional view of FIG. 1 is used. That is, the chemical vapor deposition apparatus has an outer cylinder 4a on top of a disk-shaped stainless steel chamber pace 1.
A quartz 2M work coil cover 4 consisting of an inner cylinder 4b and a ceiling portion 4c is installed, and a copper work coil 5 for high frequency induction heating is housed within the work coil cover 4. The work coil 5 has a shape in which it is wound around the inner circumference of the inner Hj 4 b in a circular spiral shape on the same horizontal plane, and both ends 5
a and 5b are hole portions 1 provided in chamber space 1;
A high frequency oscillator (not shown) which is a heating source passes through a and Ib.
is connected to the heating means.

Next, the structure of the raw material gas supply member will be explained. Reference numeral 7 denotes a lower base material holder inserted into the central hole 1c and the inner cylinder 4b of the chamber pace 1, and an upper base material holder 8 having a collar 8a is connected thereto. A plate-shaped base material 9 having holes is placed horizontally. Although not shown, the lower part 8 holder 7 is connected to the motor 30.
The upper substrate holder 8. rotates at a low speed below rpm. The base material 9 rotates horizontally. Lower base material holder 7
A nozzle holder 10 is inserted into an axial hole inside the upper substrate holder 8, and a nozzle 11 is joined thereon with a clearance fit. The nozzle 11 has an upper end sealing part 11
a and a large number of jet ports 11b are provided radially in the horizontal direction.

Note that the lower base material holder 7 is made of quartz, ceramic, or the like having electrical insulation and heat insulation properties.
0 is graphite, alumina, SiC, etc. that have heat resistance of 1000 to 1600℃, and nozzle holder]0 is quartz,
The nozzle 11 is made of graphite, alumina, SiC, or the like.

Furthermore, the reaction chamber 2 is a dome-shaped chamber made of stainless steel or quartz, and the outside of the chamber 2 is covered with a water cooling jacket 3 made of stainless steel or quartz. The lower end of the chamber 2 comes into contact with a ring-shaped protrusion 1d provided on the outer circumferential side of the Nayanbar pace 1 via an O-ring 6 and is gas-sealed.

The chamber 2 is cooled by the cooling water 15 flowing from the cooling water port 3a toward the outlet 3b.

Chemical vapor deposition is the process of converting volatile metals, organic compounds, hydrocarbon compounds, etc. into gold through gas-phase chemical reactions at high temperatures, such as thermal decomposition, hydrogen reduction, and substitution reactions. This is a method of forming vapor deposits of high melting point metals, carbides, borides, silicides, nitrides, etc. on the surface, and the vapor deposited layer is formed by the raw material gas coming into contact with the heated base material surface to generate nuclei, which become crystals. It is formed by the growth of Therefore, the growth rate of the crystal is controlled by the rate at which the substance reaches the surface of the substrate from the gas phase, ie, the rate of movement of the substance in the gas phase, and the rate at which the substance is assembled into a crystal structure, ie, the surface reaction rate. The rate of movement of substances in the gas phase is mainly determined by the degree of supersaturation of the substance in the gas phase and the flow state of the gas near the surface of the substrate, whereas the rate of reaction on two surfaces is mainly influenced by the reaction temperature. . If the above-mentioned reaction temperature is set high enough, the surface reaction rate becomes constant, but on the other hand, the flow state of the dregs near the surface of the substrate is complicated and poses a problem in forming a stable vapor deposited layer. That is, near the surface of the base material, there is not only a laminar boundary layer in which the raw material gas flows in a layered manner without disturbance, but a turbulent boundary layer filled with irregular vortices called turbulence. In this turbulent boundary layer, a larger amount of substances can be brought to the substrate surface than in a laminar boundary layer, but at the same time, the largest amount is taken out from the substrate surface, making it difficult to form stable crystals. In addition, heat transfer is active, and there is a problem in that thermal stress remains inside the crystals of the film, which grows while undergoing rapid temperature changes.

The above will be specifically explained in the case of the conventional chemical vapor deposition apparatus shown in FIG. Downflow which is natural convection 13. Rise 1
13a, sloping rise DK 13b occurs, but the raw material gas 12
The ejected flow 12a collides with the upward flow 13a, the oblique upward flow 13b, etc., and a part of the oblique upward flow 13b also collides with the side surface 9 of the base material 9.
bK directly collides and the surrounding airflow becomes disturbed. Due to the above-mentioned flow state, the aforementioned turbulent boundary layer is generated, and an inhomogeneous crystalline film is formed on most of the substrate surface 9a or on the center and side surfaces 9b (in addition, the exhaust gas 14 after the 9 reaction
is discharged to the outside through the exhaust port 1e).

The object of the invention is to provide a chemical vapor deposition apparatus which does not have the above-mentioned disadvantages.

The present invention includes a reaction chamber for carrying out a chemical vapor phase reaction.

A raw material gas supply member for supplying raw material gas to the reaction chamber, and a heating means for heating a substrate disposed in the reaction chamber such that the surface to be treated is horizontal; In the chemical vapor deposition apparatus which is installed vertically through the hole provided in the center of the base material, 1 the fertilizer raw material gas supply member is connected to the Venturi! It has a wedge-shaped hollow part, and a plurality of holes are provided on the side surface of the reduced diameter part below the hollow part, and a raw material gas jetting pipe having a spouting opening at the upper end is provided, and a gap is formed on the outer periphery of the raw material gas jetting pipe. The jacket is provided with a flange extending outwardly in a curved manner at the lower end, and a trumpet tubular shape extending upward, with a plurality of holes, the lower edge of which is connected to the ejection opening of the raw material gas ejection pipe. on the outside and a joint pipe whose upper edge is connected to the inside of the upper end of the jacket, and further around the base material, a horizontal part that is close to the periphery and is at the same level or slightly higher than the top surface of the base material, and a curved part facing upward. The present invention relates to a chemical vapor deposition apparatus comprising a dish-shaped baffle plate having a peripheral edge.

The present invention will be explained below with reference to the drawings.

FIG. 2 is a cross-sectional view schematically showing an embodiment of the chemical vapor deposition apparatus with a chamber diameter of 360 g according to the present invention, in which the source gas supply member is a venturi-shaped source gas ejection pipe 22.
It consists of a jacket 23 with an inner diameter of 35 mm and a joint pipe 24 provided on the outside thereof.

18 is a dish-shaped rectifying plate. FIG. 3 is an enlarged sectional view illustrating the raw material gas supply member in FIG. 2.

The chemical vapor deposition apparatus shown in the above embodiments of the present invention may be used depending on the design conditions such as the surface area of the substrate, the amount of raw material gas supplied, and the size of the space in the chamber. This is used when it is necessary to move the raw material gas flowing on the surface of the base material as parallel as possible to the center of the base material. In the figure, 22 is a nozzle holder 21
Outer diameter 15mm connected with a clearance fit (screwed connection is also acceptable)
The raw material gas jetting pipe 22 has a venturi-shaped hollow part 22a, and eight holes 22 in two stages are formed on the side surface of the reduced diameter part 22b (for inner diameter 4) of the hollow part 22a.
A spout opening 22d with an inner diameter of 10 mm is also provided at the upper end of c. The fc23 is 10m around the outer circumference of the raw material gas ejection pipe 22.
It has a collar part 23a which is provided at an interval of m and expands outward in a curved manner at the lower end, and the upper end is a jacket higher than the ejection opening 22d of the raw material gas ejection pipe 22 (height: 120 m).
+n). Further, 24 is a joint tube which is shaped like a trumpet tube and extends upward and has eight vertical holes 24a.

The upper edge of the joint pipe 24 is connected to the upper inner side K of the jacket 23, and the lower edge is connected to the ejection opening 22d of the raw material gas ejection pipe 22. Note that the jacket 23 and the joint pipe 24 may be formed integrally. The upper end of the jacket 23 is assembled as close as possible to the inner wall of the central part of the ceiling of the chamber 2. In this example, it was set to 511nI11. Graphite is used for the jacket 23 and the joint tube 24.

In FIG. 2, reference numeral 18 denotes a circular dish-shaped rectifier plate with an outer diameter of 345 m and an inner diameter of 180 mm attached around the circular base material 9. 18b, an upwardly curved peripheral edge 18 with a radius of 50 mm;
Consists of a. Note that 18c is a cylindrical leg section provided below the dish-shaped rectifying plate, which allows the above-mentioned horizontal section 18b to
is the base material surface 9. of the base material 9. ．． 3 Placed at the same height or slightly higher. The height of the dish-shaped rectifying plate 18 is 53 m.
Although the base material 9 is a one-piece product, it may be divided into a plurality of parts on the circumference depending on the size of the base material 9. Furthermore, the materials used include heat-resistant quartz, alumina porcelain, and graphite.

The configuration of FIG. 2 other than the above is the same as that of FIG. 1.

The flow of the raw material gas in the above four examples will be explained.

In FIG. 3, the pressure energy of the raw material gas 12 is converted into velocity energy when it passes through the reduced diameter part 22b, and the pressure is reduced in this part, so that it approaches the base material surface 9a through the plurality of holes 22c on the side surface. A part of the flowing gas 25 (horizontal flow of the raw material gas jet flow 12a) is sucked into the raw material gas jet pipe 2, and is mixed with the raw material gas 2 while flowing into the raw material gas jet pipe 2.
2, changes its course horizontally and radially due to the effect of the curved surface of the joint pipe 24, and descends along the inner wall of the chamber 2 as a downward flow 25a. Then, the direction is changed by the peripheral edge 18a of the dish-shaped rectifier plate 18, and reaches the horizontal portion 18b, resulting in a horizontal flow 25 that is uniformly rectified in the horizontal direction. On the other hand jacket 2
Since the space 23b between the joint pipe 24 and the raw material ejection pipe 22 is at a very high temperature, an active upward flow 251) is generated, and the hole 24. It is discharged from I and flows radially in the horizontal direction together with the aforementioned raw material gas jet flow 12a. The space 23b between the jacket 23 and the raw material ejection pipe 22 has the function of sufficiently sucking the horizontal flow 25 of natural convection gas to the center of the substrate surface 9a.

Next, a comparison will be made between the characteristics of deposited layers formed using the chemical vapor deposition apparatus according to the present invention and those formed using a conventional apparatus.

EXPERIMENTAL EXAMPLE OF THE INVENTION The apparatus shown in FIG.
A disk-shaped graphite base material of m+n is arranged, and 8
12 x 10-3 mol each of iCla and CC14
Pour 7 minutes into the chamber together with carrier gas H (30//min) 2 Reaction temperature 1500°C (±20°C) 2
A SiC layer was formed on the surface of the graphite base material under the condition that the reaction time was 60 minutes.

Comparative Experimental Example On the other hand, a disk-shaped graphite substrate having the same specifications as the above-mentioned inventive experimental example was placed in the conventional apparatus shown in FIG. A vapor deposited SiC film was formed on the surface of the graphite base material under the same conditions as in the example.

According to the above experimental example, the average size of crystal grains in the deposited film is about 20 μm in the conventional method.

In the case of the present invention, crystal growth of about twice or more was observed with an average diameter of about 50 μm. Next, in the case of the conventional method, crystals that are abnormally protruded in a columnar manner are deposited in the I\I circle of the hole on the surface of the base material and at the corner of the outer periphery of the surface of the base material, but in the case of the present invention. In this case, the above phenomenon was not observed. Furthermore, the above steam S
A heat cycle test was conducted on the base material on which the layer was formed. That is, as a result of a test in which the above-mentioned substrate was heated to 400°C in a heating furnace and then dropped into water at 20°C, cracks appeared in the vapor deposited layer on the fourth drop in water using the conventional device, but with the present invention. In the case of , a crack appeared for the first time at the 133rd time. (All results were based on visual observation) Therefore, it was found that the thermal shock resistance of the vapor deposited layer of the present invention was improved compared to that of the conventional apparatus.

As described above, according to the present invention, there is no collision between the raw material gas introduced into the reaction chamber of the chemical vapor deposition apparatus and the raw material gas introduced earlier and undergoing natural convection within the reaction chamber, so that the upper surface of the substrate is coated with the raw material gas. Since the raw material gas can be uniformly flowed in parallel without any turbulence, it is possible to form a homogeneous and stable vapor deposition layer on the entire surface of the base material, which is extremely effective.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional chemical vapor deposition apparatus, Fig. 2 is a sectional view schematically showing an embodiment of the chemical vapor deposition apparatus of the present invention, and Fig. 3 is a raw material gas supply in Fig. 2. It is an enlarged sectional view explaining a member. Explanation of symbols

Claims (1)

[Claims] 1. Heating a reaction chamber for carrying out a chemical vapor phase reaction, a raw material gas supply member that supplies raw material gas to the reaction chamber, and a base material placed in the reaction chamber so that the surface to be treated is horizontal. In the chemical vapor deposition apparatus, the source gas supply member is provided with a heating means, and in which the source gas supply member is erected through a hole provided in the center of the base material, wherein the source gas supply member has a venturi shape. A raw material gas ejection pipe having a hollow part, a plurality of holes on the side surface of the reduced diameter part below the hollow part, and an ejection opening at the upper end, and a gap around the outer periphery of the raw material gas ejection pipe. It is provided with a jacket having a flange extending outwardly in a curved shape at the lower end, and a trumpet tube shape extending upward, and having a plurality of holes, the lower edge of which extends outward from the ejection opening of the raw material gas ejection pipe. a joint pipe whose upper edge is connected to the inside of the upper end of the jacket, and a horizontal part that is close to the periphery of the base material and is the same as or slightly higher than the top surface of the base material, and a peripheral edge that curves upward. A chemical vapor deposition apparatus comprising a dish-shaped rectifying plate.