JP2000277442A - Vapor-phase growth device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of gas flow disturbance at both side ends of a tip end part of a partition plate, which causes a whirl, etc., by providing the partition plate parallel to a substrate surface in a reactive tube on the upper stream side of the substrate forming a thin-film, with a cut part provided at both side ends of the tip end part of the partition plate. SOLUTION: Related to a reactive tube 1, a gas guide part 2 is provided at one end while a gas discharge part 3 at the other end, a susceptor 5 which holds a substrate 4 is provided at a central part, and on the upper stream side of the substrate 4, in short, on the gas guide part 2 side, two partition plates 6 which vertically partition the tnterior of the reactive tube 1 into three layers are horizontally arranged in parallel. On the outer periphery of the reactive tube 1, a high-frequency coil 7 which heats the substrate 4 through the susceptor 5 is provided. The partition plates 6 gradually widen from the gas guiding part 2 side to the substrate 4 so as to correspond to the inner-surface form of the reactive tube. Related to the tip end part of the substrate 4 side, a cut part 10 is provided on both side ends so that a central part 11 protrudes on the substrate 4 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase growth apparatus, and more particularly to a horizontal vapor phase growth apparatus for forming a thin film on a substrate surface by flowing various gases in parallel with the substrate surface.
In particular, the present invention relates to a vapor phase growth apparatus for forming a compound semiconductor thin film of two or more components on a substrate surface.

[0002]

2. Description of the Related Art As a vapor phase growth apparatus for forming a good compound semiconductor thin film of two or more components having few defects, for example, an apparatus described in Japanese Patent Publication No. 7-27868 is known. In this vapor phase growth apparatus, a partition plate parallel to the substrate surface is disposed in a reaction tube on the upstream side of the substrate surface to divide the inside of the reaction tube into upper and lower portions. The above source gases are introduced. For example, when two partition plates are provided, ammonia is introduced into the substrate side (lower layer), organic metal and hydrogen are introduced between the partition plates (middle layer), and nitrogen is introduced into the uppermost portion (upper layer). Thus, a gallium nitride binary compound semiconductor thin film can be formed on the substrate surface.

[0003] However, in a vapor phase growth apparatus having such a partition plate, defects due to particles may be present in the obtained thin film depending on the operating conditions, for example, the growth temperature, the type of raw material gas flowing through each layer, the gas flow rate, and the like. Occasionally, the growth rate may be reduced, or the reproducibility may be reduced. In particular, it often occurs when the gas flow velocity difference between the layers separated by the partition plate is large.

[0004] In view of the above, the present applicant has proposed to form the partition plate so as to continuously reduce the thickness at its tip end in order to solve these problems (Japanese Patent Application Laid-Open No. Hei 10 (1998)).
-223543).

[0005]

As described above, most of the above-mentioned problems could be solved by making the leading end of the partition plate thinner. However, even if this countermeasure is taken, depending on the operating conditions. In some cases, the gas flow was disturbed and the uniformity of the obtained thin film was reduced.

Accordingly, the present inventors have made various studies and found that
It has been found that, depending on the flow velocity and pressure of each gas above and below the partition plate, a turbulence occurs in the gas flow at both ends of the leading end of the partition plate, thereby causing a vortex or an uneven gas flow. The present invention has been made based on such knowledge, and the setting range of the gas flow rate of each layer separated by the partition plate and the setting range of the gas pressure can be widened, and the gas flow rate of each layer is affected. To provide a vapor phase growth apparatus capable of efficiently forming a thin film of good quality and excellent uniformity without deteriorating the raw material use efficiency, particularly, a compound semiconductor thin film of two or more components without lowering the raw material use efficiency. It is intended to be.

[0007]

In order to achieve the above object, a vapor phase growth apparatus according to the present invention comprises a partition plate parallel to a substrate surface in a reaction tube upstream of a substrate on which a thin film is formed. In the phase growth apparatus, notches are provided at both ends of the tip of the partition plate, and further, the thickness of the tip portion of the partition plate is formed to be continuously reduced. .

[0008]

1 to 4 show one embodiment of a vapor phase growth apparatus according to the present invention. FIG. 1 is a plan view of a cross section of a reaction tube in the vapor phase growth apparatus, and FIG. Front view,
FIG. 3 is a plan view of the partition plate, and FIG. 4 is a front view of the same. FIGS. 5 and 6 show other examples of the shape of the partition plate.
FIG. 5 is a plan view, and FIG. 6 is a front view. FIG. 7 is a front view showing a modification of the partition plate.

A reaction tube 1 in this vapor phase growth apparatus has a gas introduction part 2 at one end, a gas discharge part 3 at the other end, and a susceptor 5 for holding a substrate 4 at the center.
On the upstream side of the substrate 4, that is, on the side of the gas introduction unit 2, two partition plates 6 for dividing the inside of the reaction tube 1 into upper and lower three layers are arranged in parallel in the horizontal direction. An RF (high frequency) coil 7 for heating the substrate 4 via the susceptor 5 is provided on the outer periphery of the reaction tube 1.

As shown in FIGS. 3 and 4, the partition plate 6
It has a shape that becomes wider from the gas introduction unit 2 side toward the substrate 4 so as to correspond to the inner surface shape of the reaction tube 1, and the front end of the substrate 4 side has cutouts at both ends. 1
0 is provided, and the central portion 11 is formed so as to protrude toward the substrate 4 side.

The width W and the depth D of the notch 10 are the thickness T and the total width Wt of the partition plate itself, the tip shape of the central portion 11, the thickness of the upper and lower layers separated by the partition plate 6, the gas phase, Usually, the width W is set to 1 depending on the gas conditions at the time of growth.
mm or more, preferably about 5 to 10 mm, and the depth D is effectively equal to or more than the thickness T of the partition plate 6, preferably about 10 to 20 mm. That is, if the width W is less than 1 mm, the effect of the provision of the notch 10 is hardly obtained, and if the width W is too large, the gas flow may be disturbed at the side edge of the notch 10. Further, even if the depth D is less than the thickness T, the effect of the notch 10 is difficult to obtain, and if the depth D is too large, the support of the central portion 11 tends to be unstable.

The tip 12 of the notch 10 may be cut off at a right angle as shown in FIGS. 3 and 4, but as shown in FIG. 5, FIG. 6 or FIG. The portion 13 reaching the tip 12 may be formed to have a continuously reduced thickness, or may be rounded. The same applies to the side surface portion 14 of the notch 10.

As described above, by providing the notches 10 on both side ends of the leading end of the partition plate 6, the gas flow at the connection between the leading end of the partition plate 6 and the reaction tube 1 can be stabilized. A uniform gas flow can be obtained by suppressing the generation of eddies and drifts.

Further, the tip of the central portion 11 protruding toward the substrate 4 is also formed so as to have a continuously reduced thickness, so that the turbulence of the gas flow in this portion can be suppressed. Therefore, the uniformity of the gas flow over the entire distal end portion of the partition plate 6 can be greatly improved in addition to the effect of the cutout portion 10. At this time, since the notch portions 10 are provided at both ends of the distal end portion of the partition plate 6, when the partition plate 6 is welded to the inner wall of the reaction tube 1, the influence of the processing distortion of the thin portion at the distal end is reduced. Can be smaller. For this reason, the central part 1
1 has the secondary effect of also stabilizing the gas flow.

Therefore, by providing the notches 10 on both side ends of the tip of the partition plate 6 in which the thickness of the tip is continuously reduced, uniformity and reproducibility in film formation can be remarkably improved. Further, variation in growth reproducibility among the production lots of the reaction tube 1 can be reduced.

According to the present invention, two or more kinds of source gases are introduced from each layer separated by a partition plate in a direction parallel to the substrate surface to form a compound semiconductor thin film of two or more components on the substrate surface. The type of the thin film to be grown and the type of the source gas are not particularly limited, and at least one type of gas to be introduced into each layer separated by the partition plate is optimal. A combination of a vapor growth gas containing a source gas and an inert gas not containing a source gas (eg, only hydrogen gas, only nitrogen gas, etc.) is also included.

The above-mentioned two-component or more compound semiconductor thin film is a III-V compound semiconductor thin film or a II-VI compound semiconductor thin film, for example, a two-component thin film such as GaN (gallium nitride), Part of Ga is Al (aluminum)
And a three-component thin film such as AlGaN, and a multi-component thin film containing In (indium). Further, the source gas is an individual component gas that contributes to a vapor phase growth reaction, and is, for example, one of ammonia, silane, trimethylgallium, trimethylindium, or a mixture thereof, and is, for example, a GaN thin film on a sapphire substrate. Is used, ammonia is used as a nitrogen source, and trimethylgallium is used as a gallium source. When the source gas is introduced into the reaction tube, the source gas may be introduced as it is, but usually, the source gas is introduced after being diluted with an inert gas such as hydrogen, helium, or nitrogen.

[0018]

EXAMPLE 1 The shape shown in FIGS. 3 and 4 was such that the thickness T was 1.5 mm, the total width Wt was 70 mm, and the angle α (see FIG. 4) of the continuously thinned center portion was 10 degrees. In the partition plate, the width W is 5 mm and the depth D is 0 mm (no notch) on both sides of the tip,
A partition plate having four types of notches of 5 mm, 10 mm, and 15 mm was prepared, and two plates were mounted in the reaction tube as shown in FIGS. 1 and 2 to form a three-layer structure. Then, on a sapphire substrate with a diameter of 50 mm, a general growth method, that is, GaN of 25 nm is grown at 550 ° C.
A GaN film to which Mg was added was formed at 0 ° C., and the film thickness uniformity and the Mg concentration uniformity were measured.

Table 1 shows the growth conditions, Table 2 shows the measurement results of the uniformity when the film thickness was measured at intervals of 2 mm except for 3 mm from the edge of the substrate, and Table 3 shows the Mg concentration measured at intervals of 5 mm from the center of the substrate. The results of the measurement of the in-plane uniformity are shown below.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

Example 2 A partition plate provided with a notch having a width W of 5 mm and a depth D of 10 mm at both ends of a tip portion, and a partition plate having no notch were used. The added GaN film was grown, and the amount of Mg was measured at the center of the substrate and at a position 10 mm from the center of the substrate. The growth conditions were the same as in Example 1. Table 4 shows the measurement results and the standard deviation.

[0024]

[Table 4]

[0025]

As described above, according to the vapor phase growth apparatus of the present invention, the gas flow rate setting range and gas pressure setting range of each layer separated by the partition plate can be widened, and the gas flow rate of each layer can be reduced. Unaffected, good quality and uniform thin films, especially
A compound semiconductor thin film of two or more components can be manufactured efficiently and with good reproducibility.

[Brief description of the drawings]

FIG. 1 is a sectional plan view of a reaction tube showing one embodiment of a vapor phase growth apparatus of the present invention.

FIG. 2 is a sectional front view of the same.

FIG. 3 is a plan view of a partition plate.

FIG. 4 is a front view of the same.

FIG. 5 is a plan view showing another example of the shape of the partition plate.

FIG. 6 is a front view of the same.

FIG. 7 is a front view showing a modification of the partition plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reaction tube, 2 ... Gas introduction part, 3 ... Gas discharge part, 4 ... Substrate, 5 ... Susceptor, 6 ... Partition plate, 7 ... RF coil, 10
... Notch, 11 ... Center

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuki Tokunaga 1-16-7 Nishi-Shimbashi, Minato-ku, Tokyo Nippon Sanso Corporation (72) Inventor Isao Matsumoto 1-16-7, Nishi-Shimbashi, Minato-ku, Tokyo Japan 4K030 AA11 BA54 BA55 BA56 BA57 EA05 5F045 AA04 AB09 AB14 AB17 AB21 AC01 AC07 AC08 AC12 AC15 AC17 AD09 AD14 AF09 BB02 BB04 DP04 EF14

Claims (2)

[Claims] In a vapor phase growth apparatus having a partition plate parallel to a substrate surface provided in a reaction tube upstream of a substrate on which a thin film is formed, notches are provided at both ends of a front end portion of the partition plate. A vapor phase growth apparatus characterized by the above-mentioned. 2. The vapor phase growth apparatus according to claim 1, wherein the partition plate is formed such that a thickness of a tip portion is continuously reduced.