JPH06151339A - Apparatus and method for growth of semiconductor crystal - Google Patents

Abstract

PURPOSE:To obtain a susceptor shape wherein the crystallinity of an epitaxial layer and the uniformity of a film thickness are excellent when an epitaxial growth operation is performed by using an MOCVD apparatus. CONSTITUTION:A susceptor 6 is divided into a main body 61 and a component 62 for wafer arrangement use. By changing the shape of the component 62 for wafer arrangement use, the shape of the susceptor is changed, and the angle at which a reaction gas 5 strikes a wafer 3 is made variable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to MOCVD (Metal Organic Chemicai) used for manufacturing compound semiconductor devices.
The present invention relates to a Vapor Deposition) device, and more particularly to improvement of a member called a susceptor for supporting a wafer and a crystal growth method using the susceptor.

[0002]

2. Description of the Related Art Conventionally, as a method for growing a thin film of a III-V group compound semiconductor or the like, a gaseous compound is introduced onto a substrate such as a silicon wafer and a chemical reaction such as decomposition, oxidation or reduction is carried out in the gas or on the surface of the substrate. In addition, there is a MOCVD method for forming a desired thin film on a substrate. FIG. 3 is a schematic configuration diagram of a conventional MOCVD apparatus used for carrying out the MOCVD method, particularly a reaction chamber of a barrel-type furnace in which a susceptor supporting a wafer has a trapezoidal shape. 2 is a trapezoidal wafer susceptor made of graphite silicon or the like, and is configured to be rotatable inside the reaction tube 1. 3 is a substrate to be processed on which crystals are grown, 4 is an RF coil for inductively heating the susceptor 2, and 5 is a carrier gas containing a source gas.

Next, the operation of the MOCVD apparatus is changed to AlGaAs.
A case where a system crystal is epitaxially grown on a substrate to be processed will be described as an example. First, a susceptor 2 having a GaAs substrate crystal 3 as a substrate to be processed placed at a predetermined position is inserted into a reaction tube 1, and a high frequency current is passed through an RF coil 4 to make a carbon susceptor 2 which is a conductor. Induction heating. Further, the carrier gas 5 containing the source gas is used as a source gas such as trimethylgallium (TMG) and trimethylaluminum (T) which are organic compounds of Group III elements.
(MA) and arsine (AsH3) as a group V element and are supplied together with a carrier gas from a gas inlet.

Next, the susceptor 2 is heated to 700 by induction heating.
After heating to about 800 ° C., a source gas whose flow rate is precisely controlled by a mass flow controller (not shown) is introduced and exhausted from the exhaust port below the reaction tube 1.
Then, the source gas supplied into the reaction tube 1 is deposited as AlGaAs by the thermal decomposition reaction on the surface of the GaAs substrate 3 heated to a high temperature.

Since the susceptor rotates during the growth in epitaxial growth using a barrel furnace, the crystal thickness and specific resistance of the obtained crystal are better than in a horizontal furnace.
In recent years, it has come to be used instead of a horizontal furnace.

[0006]

The conventional semiconductor crystal growth apparatus and crystal growth method are configured as described above,
The crystallinity, uniformity, etc. of the epitaxial growth layer are determined by the temperature, gas flow rate, etc. during growth, but are greatly influenced by the shape of the susceptor. That is, when the gas flow rate is changed to change the composition ratio of the crystal, or when a thin film made of a different material is grown, the arrangement angle with respect to the reaction gas flow of the substrate to be processed may not always be optimal. Even when the optimum growth condition is required, the conventional susceptor is integrally configured, so that a new susceptor must be manufactured to change its shape. There was a point.

The present invention has been made in order to solve the above problems, and only a part of the susceptor is replaced without newly producing the susceptor itself according to the required growth conditions. The purpose is to obtain a semiconductor crystal growth apparatus that can obtain the optimum growth conditions.
Further, it is another object of the present invention to provide a method for crystal growth using this apparatus under more optimal growth conditions.

[0008]

In the semiconductor crystal growth apparatus according to the present invention, the wafer arranging portion of the susceptor is removable, and the wafer arranging angle is changed by attaching various shapes of wafer arranging parts. It was made to let.

In the semiconductor crystal growth method according to the present invention, the crystal growth is performed with the flow rate of the reaction gas and the shape of the susceptor, that is, the angle of the flow of the reaction gas with respect to the wafer as parameters.

[0010]

According to the present invention, wafer placement components having various shapes are prepared, and a desired one is selected from these components and attached to the susceptor body, so that a reaction for hitting the wafer can be made without replacing the susceptor body. The gas angle can be variable.

Further, by performing crystal growth using the angle of the wafer with respect to the flow of the reaction gas and the flow rate of the reaction gas as parameters, crystal growth can be performed under optimum conditions.

[0012]

【Example】

Example 1. A semiconductor crystal growth apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the MOCV of the present invention.
FIG. 4 is a schematic configuration diagram of a reaction chamber of the apparatus D, the same reference numerals as those in FIG. 3 denote the same or corresponding parts, 6 denotes a wafer susceptor, and a susceptor main body 61 and a side surface of the susceptor main body 61 that is detachably attached The susceptor body 61 is attached and is composed of a carbon wafer placement component 62 similar to the susceptor body 61.

Next, similar to the conventional example, the case where the AlGaAs crystal is epitaxially grown according to the present invention will be described as an example. First, a wafer placement component 62 having an angle such that the reaction gas 5 hits the GaAs substrate 3 at a desired angle is attached to the susceptor body 61.
The GaAs substrate 3 is placed on top. Then, the susceptor 6 is inserted into the reaction tube 1, the susceptor 6 is heated to about 700 to 800 ° C. by induction heating using the RF coil 4, and then the source gas 5 is introduced through a mass flow controller (not shown). Then, the source gas (AsH3, TMG, TMA) 5 is thermally decomposed on the GaAs substrate 3, and the AlGaAs layer is grown on the GaAs substrate 3 by the chemical reaction shown below. 2AsH3 + Ga (CH3) 3 + Al (CH3) 3 → A
lGaAs + 6CH4

By the way, when an attempt is made to change the composition ratio of crystals by changing the flow rate of the reaction gas, or when an attempt is made to grow a thin film having a different composition by changing the kind of the reaction gas, the substrate to be processed is changed. It may be necessary to change the angle with respect to the reaction gas. In such a case, however, as shown by the broken line in FIG. By attaching the component 62 'to the susceptor body 61 and placing the substrate 3 to be processed thereon, the reaction gas can be applied to the substrate to be processed at a predetermined angle.

As described above, according to this embodiment, the susceptor 6 is
Since a desired one of a plurality of wafer placement components 62, 62 'having different shapes is detachably attached to the main body 61, the angle of the reaction gas 5 hitting the wafer 3 can be changed only by replacing the components. Therefore, it is possible to provide the optimum situation according to the required growth conditions, and it is possible to improve the crystallinity of the crystal layer and the uniformity of the film thickness.

Example 2. Next, a semiconductor crystal growth method according to an embodiment of the present invention will be described. Although the crystallinity of the epi layer and the uniformity of the film thickness are improved by changing the shape of the susceptor in the above embodiment, the gas flow rate and the susceptor shape (the angle of the wafer with respect to the flow of the reaction gas) are changed in this embodiment. Is used as a parameter to obtain the optimum conditions to further improve the crystallinity and the uniformity of the film thickness.

That is, FIG. 2 shows an example in which the gas flow rate and the film thickness variation of the epi layer are graphed. Even if the gas flow rate is the same by using susceptor parts A and B having different shapes,
There is a variation in the film thickness, and in this figure, it can be seen that the variation is smaller when the component B is used. Further, even if the same parts are used, it is found that the film thickness varies when the flow rate of the reaction gas is different, and the flow rate of the reaction gas has an optimum value. Therefore, the growth condition (gas flow rate, susceptor shape) with the least variation can be found from this graph.

[0018]

As described above, according to the semiconductor crystal growth apparatus of the present invention, the detachable wafer arranging component is used in the susceptor body, and the wafer is arranged on the arranging component for crystal growth. Therefore, the angle of the reaction gas hitting the wafer can be changed only by exchanging the parts, and there is an effect that the optimum reaction conditions can always be easily obtained in performing the epi growth.

Further, by changing the shape of the susceptor, changing the gas flow rate, and selecting the optimum condition from these two parameters for crystal growth, the uniformity of crystallinity and film thickness is further improved. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a MOCVD apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a correlation between a wafer arrangement component and a gas flow rate for explaining a semiconductor crystal growth method according to an embodiment of the present invention.

FIG. 3 is a block diagram of a conventional MOCVD apparatus.

[Explanation of symbols]

 1 Quartz Reaction Tube 2 Wafer 3 Wafer 4 RF Coil 5 Carrier Gas Containing Raw Material Gas 6 Susceptor 61 Susceptor Main Body 62 Wafer Arranging Parts 62 ′ Wafer Arranging Parts with Different Shapes

Claims (2)

[Claims] 1. A semiconductor crystal growth apparatus comprising: a susceptor for supporting a wafer; and a reaction tube for accommodating the susceptor and for performing crystal growth on the wafer by utilizing a thermal decomposition reaction of a reaction gas, The susceptor is composed of a susceptor body and a wafer placement component that is detachable from the susceptor body, and the angle of the reaction gas hitting the wafer is changed by using the wafer placement component having different shapes. Semiconductor crystal growth apparatus. 2. A semiconductor crystal growth method for growing a crystal on a wafer by utilizing a thermal decomposition reaction of a reaction gas, wherein the flow rate of the reaction gas and the angle of the reaction gas hitting the wafer are used as parameters to obtain a crystal to be obtained. A semiconductor crystal growth method, wherein crystal growth is performed by selecting a gas flow rate and an angle at which variations in film thickness are minimized.