JPS625994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chemical vapor deposition method, and more particularly to an improvement in a chemical vapor deposition method using a reaction tube.

In the manufacturing process of semiconductor devices, chemical vapor deposition (CVD) is often used to form a desired semiconductor layer or insulating layer on a substrate to be processed such as a semiconductor substrate. The CVD method can be roughly divided into two methods: methods that use a reaction tank such as a Belgear, and methods that use a reaction tube such as a quartz tube.

Among these methods, methods using reaction tubes are generally characterized by excellent mass productivity and relatively inexpensive equipment. However, in this method, the reaction gas is introduced from one end of the reaction tube and exhausted from the other end, so the thickness of the grown layer is affected by the gas flow, and the thickness of the grown layer varies between substrates depending on the placement location ( The variation in the thickness of the grown layer depending on the position within a single substrate (in-plane distribution) is quite large.

Although the above-mentioned problem of being influenced by gas flow has been alleviated considerably with the advent of the reduced pressure CVD method in which the inside of the reaction tube is brought into a reduced pressure state, it is still far from being fully satisfactory.

An object of the present invention is to solve the above-mentioned problems and provide a chemical vapor deposition method using a reaction tube in which the thickness of the growth layer is extremely uniform. Substrates to be processed are arranged in parallel in a direction intersecting the length direction of the reaction tube, and a thin tube having a plurality of small holes in the tube wall is inserted between the substrates to be processed and the inner wall surface of the reaction tube. This is accomplished by disposing the thin tube along the length of the tube and supplying a desired reaction gas into the reaction tube through the small hole while rotating the thin tube around the substrate to be processed.

The present invention will be specifically explained below using examples.

1 to 3 are diagrams showing one embodiment of the present invention. FIG. 1 is a sectional view showing the main parts of the reduced pressure epitaxial apparatus used in the above embodiment, and FIG. 3 is a curve diagram showing the film thickness distribution shown for explaining the effects of this embodiment.

First, the low pressure epitaxial growth apparatus used in this example will be explained with reference to FIGS. 1 and 2. 1 in the diagram
is a quartz tube (reaction tube), 2 is a silicon (Si) wafer as a substrate to be processed, 3 is a circular susceptor with Si wafers 2 mounted on both sides, and 4 is one end of the quartz tube 1 via an O-ring 5 (Fig. The cap 6 is attached to the left end (hereinafter referred to as the left end) and seals the end, and the cap 6 is a high frequency coil for inductively heating the susceptor 3.The above configuration is the same as that of a conventional low pressure epitaxial growth apparatus. In this embodiment, a thin tube 11 and a driving device 12 for this thin tube are further provided.

The thin tube 11 is made of quartz and is bent into two stages as shown in the figure, and includes a gas blowing section 14 having a large number of small holes 13 in the tube wall, a shaft section 15 passing through the thin tube driving device 12, and a connecting section connecting the two. is formed into a modified "Z" shape or a modified "S" shape. The gas blowing section 14 is connected to the susceptor 3 and the quartz tube 1.
is disposed along the length of the quartz tube between the inner wall surfaces of the quartz tube, the end 17 of which is closed, and the small hole 13
is opened almost toward the center of the quartz tube 1. The shaft portion 15 is disposed substantially in line with the extension line of the central axis of the quartz tube 1, penetrates the outer walls 19, 20 of the gear box 18 of the thin tube drive mechanism 12, and is led out to the outside, and its end portion 21 is connected to the reaction It is open to introduce gas.

The gearbox 18 is attached to the end of the quartz tube 1 via an O-ring 22, and together with the cap 4 seals the quartz tube 1. Inside the gearbox 18, a gear 23 whose central axis is the shaft portion 15 of the thin tube 11 and another gear 24 that meshes with the gear are provided.The central axis of the gear 24 penetrates the outer wall 20 and is guided outside. A pulley 27 is attached to the end via a collector chuck 25 and an electromagnetic clutch 26. This pulley 27 is connected to a pulley 30 directly connected to a motor 29 via a belt 28.
is connected to.

Furthermore, 31 is an exhaust port connected to the exhaust system.
In this embodiment, the exhaust port 31 is provided in the gearbox 18, but it may also be provided in the cap 4 or the quartz tube 1.

In the reduced pressure epitaxial apparatus configured in this way, the rotation of the motor 29 is controlled by the pulleys 27 and 3.
0 is transmitted to the shaft portion 15 of the thin tube 11 via the electromagnetic clutch 26, gears 24, 23, etc., and rotates the shaft portion 15. Therefore, the blowing portion 14 of the thin tube 11 rotates in the circumferential direction along the inner wall surface of the quartz tube 1.

FIG. 2 shows the pattern. By reversing the rotational direction of the motor 29 at a predetermined position, the blowing portion 14 moves along the inner wall surface of the quartz tube 1 around the susceptor 3, that is, around the Si wafer 3. Rotate in the direction of line A. The reaction gas introduced from the open end 21 of the shaft portion 15 is blown out from the small hole 13 toward the center of the Si wafer 2 as shown by the arrow B. Since the Si wafer 2 is rotated, the reaction gas is supplied from each direction of the Si wafer 2. Therefore, when averaged over one cycle, the reactive gas is supplied almost equally to each part of the Si wafer.

In this example, monosilane diluted to a hydrogen (H ₂ ) concentration of 4% ( SiH ₄ ) was supplied into the quartz tube 1 with an inner diameter of about 200 mm at a flow rate of about 8/min, and the pressure inside the tube was controlled to about 1 Torr by exhausting from the exhaust port 31, and the temperature was about 950 mm.
Epitaxial growth was performed at [°C] for about 20 [minutes] on a Si wafer 2 with a diameter of about 100 mm. At this time, the rotation speed of the thin tube was approximately once per minute. Susceptor 3 is made of carbon coated with SiC and has a diameter of approximately 140 mm. In addition, the above-mentioned reaction tube 1 and thin tube 1
1. Size of small hole 13, susceptor 3, etc., and SiH ₄
The flow rate, rotation speed of the thin tube 11, etc. are determined by the Si wafer 2.
It should be selected appropriately depending on the diameter of the layer, the required thickness of the growth layer, etc.

FIG. 3 is a curve diagram showing the results. The horizontal axis is the wafer number, with the leftmost wafer in FIG. Indicates the thickness [unit: μm]. In FIG. 3, a solid line curve C shows the growth layer thickness and in-plane distribution for each wafer obtained in this example, and a dash-dotted line curve D shows the film thickness and in-plane distribution obtained by the conventional method. show. In addition, the variation E shown by the broken line
is the in-plane distribution when epitaxial growth is performed with the thin tube 11 fixed using the aforementioned low-pressure epitaxial growth apparatus, and is listed for comparison with this example.

From the figure, it can be seen that the thickness of the epitaxially grown layer obtained in this example has small variations in both the inter-wafer distribution and the in-plane distribution, and is extremely uniform. Note that even if the above-mentioned device is used, if the thin tube 11 is fixed, the broken line E
As can be seen in the figure, the variation within the wafer surface becomes large. From this, the effect of rotating the thin tube 11 back and forth around the wafer 2 can be understood.

As described above, the effects of this embodiment are extremely large, but the present invention is not limited to the above-mentioned embodiment, and can be implemented with various modifications.

For example, in the above embodiment, the thin tube 11 is rotated regularly, but this does not necessarily have to be regular.

Furthermore, the present invention is not limited to the low-pressure epitaxial growth method using monosilane (SiH ₄ ), and any reaction gas may be used at normal pressure, and the substrate to be processed is also limited to semiconductor substrates. It can be applied to all chemical vapor deposition methods.

Furthermore, in carrying out the present invention, various drive mechanisms for the thin tube 11 can be selected, and heating methods other than induction heating, such as a heater heating method using an electric furnace or an infrared lamp heating method, may also be used. There is no need to specifically explain that the substrates to be processed may be arranged without using a susceptor.

As explained above, the present invention provides a chemical vapor deposition method that uses a reaction tube and has an extremely uniform film thickness distribution, thereby making it possible to achieve both mass productivity and uniformity of the film thickness distribution in the chemical vapor deposition process.

[Brief explanation of the drawing]

Figures 1 and 2 are side sectional views of essential parts and sectional views taken in the direction of the - arrow, and Figure 3 shows the effects of the above embodiment. It is a curve diagram. In the figure, 1 is a reaction tube, 2 is a substrate to be processed, 1
Reference numeral 1 indicates a thin tube; 13, 14, 15, and 16 each indicate a small hole, a blowout portion, a shaft portion, and a connecting portion of the thin tube; 12 indicates a thin tube drive mechanism; and 31 indicates an exhaust port.

Claims (1)

[Claims] 1 Arrange the substrates to be processed in a reaction tube in parallel in a direction intersecting the length direction of the reaction tube, and introduce a desired reaction gas into the reaction tube to grow reaction products on the surface of the substrates to be processed. In the chemical vapor deposition method, a thin tube having a plurality of small holes in the tube wall is disposed along the inner wall of the reaction tube between the inner wall of the reaction tube and the substrate to be processed, and the thin tube is connected to the substrate. A chemical vapor deposition method characterized in that a desired reaction gas is supplied into the reaction tube through the small hole while rotating around the processing substrate.