JPH01291421A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE:To bring a crystalline substrate into close contact with a carbon susceptor and to form a thin uniform film by forming a spot facing part for holding the substrate in a reaction vessel, and providing a susceptor formed with a groove on the periphery of the facing part and heating means for heating the susceptor to a predetermined temperature. CONSTITUTION:A carbon susceptor 5 supported by a supporting rod 7 is mounted substantially at the center of a reaction tube 1. A spot facing part 8 slightly larger than a crystalline substrate 3 is formed on the susceptor 5, and the depth of the facing part 8 is formed substantially equally to the thickness of the substrate 3. A groove 11 deeper than the facing part 8 is formed on the periphery of the facing part 8. Thus, since reactive product is dropped and collected in the groove 1, the substrate 3 is always brought into contact with the susceptor 5, heat is preferably transferred from the susceptor 5 heated to a predetermined temperature by using a high frequency coil 4, and the temperature distribution of the substrate 3 can be uniformly kept at the predetermined temperature. Thus, the thickness of the thin film grown on the substrate 3 can be made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a vapor phase growth apparatus used for manufacturing compound semiconductors and the like.

(Prior Art) A vapor phase growth apparatus commonly used in the past for manufacturing heterostructure compound semiconductors will be explained with reference to FIG. 3. A quartz reaction tube 1 is supported by a support rod 7 There is a carbon susceptor 5, on which a crystal substrate 3 is placed. Normally, the carbon susceptor 5 is heated to 700 to 800°C by the high frequency coil 4, and the crystal substrate 3 is heated to 700 to 800°C.
are also kept at the same temperature. A reaction gas is introduced therein from the gas inlet 2, and reacts and grows on the crystal substrate. However, not all of the reaction gas reacts and grows here, and the remaining reaction gas mainly adheres to the reaction tube wall surface 9 and lower part 6 as reaction products. A counterbore portion 8 is provided on the surface of the carbon susceptor 5 to hold the crystal substrate, and the counterbore surface has approximately the same depth as the thickness of the crystal substrate 3 and is flat.The reason for this is that the carbon susceptor 5 This is to uniformly transfer the heat to the crystal substrate 3. Since the diameter of the counterbore portion 8 is slightly larger than that of the crystal substrate 3, there is a gap lO as shown in FIG.
occurs. The reaction products also enter these gaps and accumulate slightly. When the vapor phase growth is completed and the crystal substrate 3 is replaced and another crystal substrate is similarly placed on the carbon susceptor 5, if reaction products are deposited around the counterbore portion 8, the crystal substrate 3 will be placed on the counterbore surface. There is a drawback that it does not stick tightly. FIG. 4 shows an enlarged cross-section of essential parts of the crystal substrate 3 and the counterbore portion 8. As shown in FIG. If the crystal substrate 3 and the counterbore portion 8 are not in close contact with each other, heat will not be uniformly transferred from the carbon susceptor 5 to the crystal substrate 3, and the temperature distribution of the crystal substrate 3 will become uneven, making it impossible to obtain a thin film with a uniform thickness.

(Problem to be solved by the invention) As mentioned above, due to reaction products slightly deposited in the counterbore for holding the crystal substrate, the crystal substrate does not come into close contact with the susceptor, resulting in uneven temperature distribution of the substrate. Therefore, there is a problem that a thin film having a uniform thickness cannot be obtained.

The present invention has been made in view of the above circumstances, and its purpose is to provide a vapor phase growth apparatus capable of forming a thin film with a uniform thickness distribution by having a structure in which a crystal substrate is closely attached to a carbon susceptor. be.

[Structure of the invention]

(Means for Solving the Problems) The vapor phase growth apparatus of the present invention includes: a reaction vessel; and a gas introduction port for introducing a reaction gas into the reaction vessel.

A gas outlet for discharging gas to the outside of the reaction vessel and a counterbore for holding a substrate on which an i-film is formed are formed,
It is characterized by comprising a susceptor in which a groove is formed around the counterbore, and a heating means for heating the susceptor to a predetermined temperature.

(Function) With this structure, even if reaction products enter the gap between the substrate and the susceptor, the reaction products will fall into the groove formed around the counterbore. It will be supplemented. As a result, reaction products do not accumulate in the counterbore, the substrate and susceptor are always in close contact, and heat conduction is good on both sides, making the temperature distribution of the substrate uniform and achieving a homogeneous thin film. .

(Example) The present invention will be described in detail below with reference to the drawings.

1 and 2 show a cross-sectional view and an enlarged view of essential parts of a vapor phase growth apparatus according to a first embodiment of the present invention, and the same parts as in FIGS. 5 and 6 are given the same reference numerals. I will omit the explanation 0
A carbon susceptor 5 supported by a support rod 7 is attached approximately at the center of the reaction tube 1 . A counterbore 8 slightly larger than the crystal substrate 3 is formed in the carbon susceptor 5, and the depth of the counterbore 8 is approximately equal to the thickness of the crystal substrate 3. A groove 11 deeper than the counterbore 8 is located around the counterbore 8.
is formed.

In the vapor phase growth apparatus configured in this manner.

A reaction gas is introduced from the gas inlet 2 of the reaction tube 1 to the substrate 3.
Although a thin film is formed on the carbon susceptor 5, the excess reaction gas also adheres to the surface of the carbon susceptor 5 as a reaction product. The counterbore portion 8 of the carbon susceptor 5 is formed to be slightly large to allow for the shape error of the substrate 3, and the reaction product enters the counterbore portion 8 through the gap between the counterbore portion 8 and the substrate 3. This reaction product falls into the groove 11 provided around the counterbore 8 and is collected.

In the conventional structure in which this groove portion 11 is not provided, reaction products accumulate at the bottom of the counterbore portion 8 and prevent the substrate 3 and the carbon susceptor 5 from coming into close contact with each other.

In the case where the groove 11 is provided in the counterbore 8 as in the present invention, the reaction products fall and are collected in the groove 11, so that the substrate 3 and the carbon susceptor 5 are always in close contact with each other, and the high frequency coil 4 Heat transfer from the heated carbon susceptor 5 to the substrate 3 is performed well, and the temperature distribution of the substrate 3 can be maintained uniformly at a predetermined temperature. This makes it possible to make the thickness of the thin film grown on the substrate 3 uniform.

3 and 4 show a second embodiment of the present invention, in which a hollow susceptor support 3 for revolution is shown in a reaction tube 31.
5 is provided, and this susceptor support 35 is provided.

It is supported by a support shaft 38 and allowed to rotate by a bearing 39. The susceptor support 35 has, for example, a polygonal pyramid shape so as to be able to hold a plurality of substrates, and its outer peripheral slope is arranged so as to be almost parallel to the reaction gas flowing along the reaction tube 31. A plurality of susceptors 34 and substrates 33 are mounted in the inner peripheral direction substantially parallel to the inner wall. This susceptor 34 is supported by a support shaft 41, and a bevel gear 42 is attached to the other end of the support shaft 41. The bevel gear 42 is fixed to the support shaft 38 and meshes with the gear 43 .

A pinion gear 44 attached to the revolution motor 36 and a rack 45 formed at the lower part of the susceptor support 35 are engaged with each other. By driving the revolution motor 36, the susceptor support 35 is rotated. As a result, the base plate 33 revolves, but the bevel gear 42 and the bridge also rotate at the same time due to the action of the gear 43.

In the above configuration, the bevel gear 42 and the bearing gear 43 for rotating the substrate 33 are connected to the susceptor support 35.
Since the inside of the tube is hollow and placed inside, reaction products are less likely to adhere to it. These bevel gears 42, the receiver is the gear 4
The susceptor support 35 can be easily incorporated into the interior by having a structure in which the susceptor support 35 can be divided into two parts, for example.

Further, as in the previous embodiment, the counterbore portion 38 of the susceptor 34 is
A groove 51 is provided around the periphery of the reaction product, and the reaction products fall into the groove 51 and are collected.

In the structure in which the substrate 33 is held diagonally in this way, the substrate 33 is only held by the susceptor 34 around the counterbore 38, and in particular, as in this embodiment, the substrate 33 cannot be rotated or rotated. When the susceptor 34 and the substrate 33 are rotated, the substrate 33 is likely to fall. Therefore, the adhesiveness between the susceptor 34 and the substrate 33 is further required, and the effect of the groove portion 51 is important.

Note that the reaction products collected in the grooves are removed during maintenance.

In the above embodiments, a vertical vapor phase growth apparatus in which the reaction gas flows from above to below has been described, but the present invention is not limited thereto and can be applied to a horizontal vapor phase growth apparatus. That is, various modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

As described in detail above, according to the present invention, the susceptor and the substrate are always kept in close contact with each other, so that heat transfer from the susceptor to the substrate is performed well, and a homogeneous thin film can be grown.

[Brief explanation of the drawing]

1 and 2 are a sectional view and an enlarged sectional view of essential parts showing one embodiment of the vapor growth apparatus of the present invention, and FIGS. 3 and 4 are sectional views of another embodiment of the invention. 5 and 6 are a sectional view and an enlarged sectional view of the main part of a conventional vapor phase growth apparatus. 1.31...Reaction tube 3,33...Substrate 4.
32... High frequency coil 5, 34... Susceptor 8.
38... Counterbore 11.41... Mizobe's agent Patent attorney Nori Chika Ken Yudo Mitsuyuki Matsuyama '1 Figure 2

Claims (1)

[Claims] A reaction vessel, a gas inlet for introducing a reaction gas into the reaction vessel, a gas outlet for discharging the gas outside the reaction vessel, and holding a substrate on which a thin film is formed. A counterbore is formed for
A vapor phase growth apparatus comprising: a susceptor having a groove formed around the counterbore; and heating means for heating the susceptor to a predetermined temperature.