JPS624314A - Susceptor for vapor growth apparatus - Google Patents

Abstract

PURPOSE:To heat an entire semiconductor substrate uniformly by providing a spouting-out part of high temperature inert gas so as to surround the circumference of a wafer mounting surface formed into a concave shape. CONSTITUTION:After a susceptor is placed in an airtight container and a semiconductor substrate W is mounted on the top surface of a wafer mounting part 2, high-temperature inert gas is supplied into a high-temperature gas passage 3b from a gas passage 3d. Then, the high-temperature inert gas supplied into the high-temperature gas passage 3b is spouted out into the space above the wafer mounting part through an annular porous substance 3a to heat the semiconductor substrate W directly. After the temperature of the semiconductor substrate W reaches the temperature at which vapor growth takes place and becomes constant, the supply of the high-temperature inert gas is controlled and reactive gas such as SiH4 gas is supplied into the apparatus through a gas supply tube to form a vapor growth layer on the surface of the semiconductor substrate W.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a susceptor for a vapor phase growth apparatus for forming a vapor phase growth layer (including an epitaxial layer) on the surface of a semiconductor substrate, and more particularly relates to a susceptor for a vapor growth apparatus for forming a vapor phase growth layer (including an epitaxial layer) on the surface of a semiconductor substrate. The present invention relates to a susceptor that uses a high temperature gas heating method regardless of the heating method.

[Technical Background of the Invention 1 Currently, the most widely used vapor phase growth apparatus in the manufacturing process of semiconductor devices is a so-called vertical vapor growth apparatus. In this device, a semiconductor wafer is mounted on a rotating disc-shaped susceptor installed in a closed container called a bell jar, and while slowly rotating the susceptor, a reactive gas such as 5iH4, Si C1a, etc. is introduced into the bell jar. On the other hand, the susceptor is heated by induction using a high-frequency coil installed in the susceptor, and a vapor phase growth layer is formed on the semiconductor wafer while indirectly heating the semiconductor wafer by heat conduction from the susceptor.

[Problems with the background art] The method of heating a semiconductor substrate in a conventional vertical vapor phase growth apparatus is an indirect heating method using heat conduction from an induction-heated susceptor, so it is difficult to uniformly heat the entire surface of the semiconductor substrate. As a result, internal stress due to non-uniform heat distribution is generated within the semiconductor substrate, causing the semiconductor substrate to warp or causing dislocations (i.e., crystal defects) called slip lines.

3 and 4 show the cross-sectional shape of the wafer placement part in the susceptor 1 of a conventional vertical vapor phase growth apparatus. In the susceptor shown in FIG. 3, the wafer placement surface 1a is configured as a flat surface. In the susceptor shown in FIG. 4, the wafer mounting surface 1a is configured as a concave curved surface (note that C in the figure is the central axis of the susceptor 1).
.

The temperature distribution of the semiconductor wafer W in the conventional susceptor 1 shown in FIGS. 3 and 4 is shown in FIGS. 5 and 6, respectively. (This is the temperature distribution of the susceptor in Figure 4).

4 and 5, the horizontal axis represents the radial position R with the central axis C of the susceptor 1 at its apex, and the vertical axis represents the temperature T of the semiconductor wafer placed on the mounting surface 1a. The curve in represents the temperature distribution within the wafer.

As mentioned above, in the conventional vertical vapor phase growth apparatus, after the susceptor is heated by induction, the semiconductor substrate is heated by contact heat conduction from the susceptor, so the semiconductor substrate is not heated uniformly, and as a result, internal stress Warpage and crystal defects were likely to occur.

[Object of the Invention] An object of the present invention is to provide a susceptor with a novel structure that can heat the entire semiconductor substrate as uniformly as possible without causing warpage or crystal defects in the semiconductor substrate. Another object of the present invention is to provide a susceptor for a wafer direct heating type vapor phase growth apparatus that can replace the conventional induction heating type susceptor for a vapor phase growth apparatus.

[Summary of the Invention] A susceptor according to the present invention includes a wafer placement surface formed into a concave curved surface, and a high-temperature inert gas ejection section disposed to surround the wafer placement surface. This device is characterized in that a semiconductor wafer placed on a wafer mounting surface is directly heated by a high-temperature inert gas.

[Embodiment of the Invention] FIG. 1 shows a first embodiment of the invention, and is a sectional view of a portion of a susceptor that covers one wafer. In the figure, reference numeral 2 denotes a wafer mounting portion whose upper surface is formed into a concave curved surface, and a semiconductor substrate W is placed on the upper surface of the mounting portion 2 as shown by the two-dot chain line. An annular high-temperature gas jetting section 3 surrounding the wafer mounting section 2 is provided around the wafer mounting section 2, and the height of the top of the high-temperature gas jetting section 3 is equal to the top of the mounting section 2. It is higher than the surface, that is, the wafer mounting surface. The upper part of the cylindrical wall surrounding the wafer placement part 2 is made of a porous body 3 having a large number of pores.
This porous body 3a constitutes an annular nozzle that spouts high-temperature gas into the space above the wafer placement section 2. The high temperature gas ejection part 3 outside the porous body 3a
A high-temperature gas passage 3b is provided inside the porous body 3a, and the high-temperature gas passage 3b extends radially with respect to the central axis of the wafer mounting portion 2, and the high-temperature gas passage 3b communicates with the pores within the porous body 3a. The high-temperature gas passage 3b branches from a gas passage 3d connected to a high-temperature inert gas (for example, H2) supply pipe 5 at a position near the outer periphery of the high-temperature gas jetting portion 3. gas passage 3d
Another high temperature gas passage 3c, 3e branching from
Porous bodies (not shown) for second and third wafers
are connected to each other. The gas supply pipe 5 is provided with a valve 7 as shown, and the valve 7 is opened and closed in a predetermined sequence to keep the temperature of the wafer constant.

Further, the wafer platform 2 is configured to be able to rotate about its own central axis, and is connected to a rotation mechanism (not shown).

When forming a vapor phase growth layer on the surface of a semiconductor substrate W using the susceptor of the present invention having the above-described structure, the susceptor is installed in a closed container, and the semiconductor substrate W is placed on the top surface of the wafer mounting section 2. After placing the
When gas) is supplied, the high-temperature inert gas supplied into the high-temperature gas passage 3b passes through the annular porous body 3a and is ejected into the space above the wafer platform, directly heating the semiconductor substrate W.

After the temperature of the semiconductor substrate W reaches the temperature at which vapor phase growth occurs and the temperature of the semiconductor substrate becomes constant, the supply of high-temperature inert gas is controlled, and sr Ha gas is introduced into the apparatus from a reaction gas supply pipe (not shown). A vapor phase growth layer is formed on the surface of the semiconductor substrate W by supplying a reactive gas such as the following.

In this case, the wafer mounting section 2 may be rotated about its central axis, but it is not necessary to rotate it.

FIG. 2 is a schematic diagram of a second embodiment of the susceptor of the present invention. Note that in FIG. 2, the parts indicated by the same reference numerals as in FIG. 1 are the same parts as those of the susceptor in FIG. 1, so a description of these same parts will be omitted.

In the susceptor of the embodiment shown in FIG. 2, a rotation drive device 2b, such as a boot, is attached to a shaft 2a formed integrally with the wafer placement section 2. In addition, a large number of holes 2C are opened in the top surface (i.e., wafer mounting surface) of the wafer placement part 2, and a large number of gas flow paths 2d connected to the holes 2C are formed in the wafer placement part 2. A gas flow path 2e communicating with the gas flow path 2d is provided at the center of the shaft 2a, and a rotary piping joint 2f is connected to the end of the shaft 2a. A gas passage 2e within the shaft 2a is configured to communicate with an external high temperature inert gas supply pipe 4 and is controlled by a valve 6. The high-temperature inert gas supply pipe 4 is connected to the gas passage 3 in the high-temperature gas jetting section 3.
It may be common to the high temperature inert gas supply pipe 5 communicating with C.

In the susceptor shown in FIG. 2, high-temperature inert gas is ejected from the top surface of the wafer placement section 2, that is, the wafer placement surface, and the wafer placement section 2 is configured to be rotated. Therefore, the temperature distribution of the wafer can be made more uniform than in the susceptor of the embodiment shown in FIG.

When rotating the wafer platform 2 in the embodiment of the present invention as described above (FIGS. 1 and 2), the rotation speed is 0.1.
It has been found that when rp1 or more, a remarkable effect can be obtained in making the temperature distribution within the wafer uniform. In addition, in the case of this example (Figures 1 and 2), the temperature difference inside the wafer is 1°C.
I was able to do it within.

In the above embodiment, the wafer mounting surface may be formed of a porous material, or an annular nozzle may be used instead of the annular porous material 3a. Further, any number of radial gas passages 3b may be provided, and an annular gas chamber may be provided in place of the radial gas passages 3b.

[Effects of the Invention] As is clear from the above embodiments, the susceptor of the present invention can make the temperature distribution within the wafer more uniform than the conventional susceptor using high-frequency induction heating. The risk of warping or dislocation occurring in the semiconductor substrate during the process is reduced, and as a result, the yield of semiconductor devices is improved, and semiconductor devices with good electrical characteristics and high reliability can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the susceptor of the present invention;
FIG. 2 is a sectional view showing a second embodiment of the susceptor of the present invention;
3 and 4 are cross-sectional views of the vicinity of the wafer mounting section in a susceptor of a known vertical vapor phase growth apparatus, and FIG. 5 shows the temperature distribution of the semiconductor substrate placed on the wafer mounting section shown in FIG. 6 is a temperature distribution diagram of the semiconductor substrate placed on the wafer placement section shown in FIG. 4. 1... Susceptor, 1a... Wafer placement surface, W.
... Semiconductor substrate, 2... Placement section, 2d... High temperature gas flow path, 3... High temperature gas ejection section, 3a... Porous body, 3b... High temperature gas passage, 4, 5 ...High temperature inert gas supply pipe. M2FIJ Daiichi 31i! 4th m R Figure 5 Figure 6 3

Claims (1)

[Claims] 1 In a susceptor used in a vapor phase growth apparatus that forms a film on the surface of a semiconductor substrate by chemical reaction in the gas phase, thermal decomposition, etc., there is a mounting part for mounting the semiconductor substrate, and a susceptor that surrounds the mounting part. 1. A susceptor for a vapor phase growth apparatus, characterized in that the semiconductor substrate is heated by the high temperature inert gas ejected from the ejection part, and the semiconductor substrate is heated by the high temperature inert gas ejected from the ejection part.