JPH0521358A - Manufacture of silicon carbide - Google Patents

Abstract

PURPOSE:To obtain silicon carbide in which a plurality of silicon carbide layers are formed on the same substrate, and to form many shapes with high controllability. CONSTITUTION:In the first step, gas to become a silicon source, a carbon source is so added with gas for third element as to dope suitable amount of third element when silicon carbide layers 3A, 3B are formed, and reacted on regions on a substrate 1. Thus, the layer 3A is grown on the outer periphery of the substrate 1, and the layer 3B is grown on the central part. The gas composition of the third element used in the first step, is variably selected in response to many shapes to be formed. In the second step to be conducted next, the above grown layers 3A, 3B are held in an environment having an atmosphere, pressure or temperature responsive to the many types to be formed, and crystallized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a silicon carbide body which can be used in a semiconductor device such as an LED and in which silicon carbide layers having different polymorphisms are formed in a plurality of regions on a substrate. It is a thing.

[0002]

2. Description of the Related Art Silicon carbide is a highly durable material which is excellent in acid resistance and alkali resistance and is hardly damaged by high energy rays, and is also used as a semiconductor material. The use of silicon carbide for semiconductor materials has long been
This has been done since before the 960's, because silicon carbide has a characteristic of polymorphism described later, and the band gap can be arbitrarily selected from 2.2 eV to 3.3 eV according to the polymorphism, and it can operate. This is because the wide temperature range is extremely wider than other materials. Here, the polymorph means a phenomenon having the same chemical composition but different crystal structures, or a material exhibiting the phenomenon.

By the way, in order to industrially utilize silicon carbide, it is necessary that it is a high quality single crystal having a certain size. Therefore, conventionally, a single crystal is grown to a target size by using a chemical reaction called Acheson method, or a sublimation recrystallization method called Rayleigh method, or obtained by these methods. A method has been adopted in which a single crystal of silicon carbide is used as a substrate, and a single crystal layer of silicon carbide is grown on the substrate by a vapor phase epitaxial growth method or a liquid phase epitaxial growth method to obtain a target single crystal. ..

[0004]

However, in the case of the above-mentioned conventional method, it was not possible to form polymorphs of silicon carbide having different forbidden band widths on the same substrate with good controllability. Further, when trying to form different polymorphic silicon carbide layers on the same substrate, it is difficult to perform fine control by the above-mentioned conventional method.

The present invention has been made to solve such problems, and it is possible to obtain a silicon carbide body in which a plurality of silicon carbide layers are formed on the same substrate, and moreover, polymorphism is formed with good controllability. An object of the present invention is to provide a method for producing a silicon carbide body that can be manufactured.

[0006]

A method of manufacturing a silicon carbide body according to the present invention is a method of manufacturing a silicon carbide body in which silicon carbide layers having different polymorphisms are formed in a plurality of regions on a substrate. A first step of growing a silicon carbide layer on each region by varying the composition or content of the third element contained in the silicon carbide layer formed in the region, and crystallizing each silicon carbide layer obtained in the first step And a second step of causing the reaction to be achieved, whereby the above object is achieved.

[0007]

In the first step of the present invention, the gas for the third element is doped so that the gas serving as the silicon source and the carbon source is doped with an appropriate amount of the third element when the silicon carbide layer is formed. Is added to each region of the substrate to be reacted. Thereby, the silicon carbide layer grows. The gas composition of the third element used in the first step is variously selected according to the desired polymorph. In the subsequent second step, the silicon carbide layer grown as described above is crystallized while being held in an environment having an atmosphere, pressure or temperature according to the desired polymorphism.

The polymorphism may be formed by repeating the first step and the second step, or by performing the first step a plurality of times and then performing the second step. ..

[0009]

EXAMPLES Examples of the present invention will be described below.

Example 1 FIG. 1 is a sectional view showing a silicon carbide body manufactured by the method of the present invention. This silicon carbide body has, for example, a structure in which a silicon carbide layer 3B containing boron is formed on a central portion of a circular substrate 1 and a silicon carbide layer 3A containing aluminum is formed on an outer peripheral portion of the substrate 1. Is becoming

The method of the present invention when applied to the above silicon carbide body will be described. First, as shown in FIG. 2, a mask layer 2 made of, for example, silicon nitride is formed on the central portion of the substrate 1,
This was set inside a reaction furnace (not shown), for example, a reaction furnace provided with a high frequency induction coil on the outer periphery. As the substrate 1, for example, a silicon carbide single crystal having a 6H structure obtained by a chemical reaction method called the above-mentioned Acheson method was used.

Then, for selective epitaxial growth on the substrate 1 excluding the mask layer 2, for example, a gas prepared by mixing propane, silane and trimethylaluminum containing about 1% hydrogen chloride gas with the reaction furnace is used. 3A in which the silicon carbide layer 3A containing aluminum is contained at about 3% by atomic ratio as shown in FIG.
Were grown on the outer periphery of the substrate 1.

Next, as shown in FIG. 4, after removing the mask layer 2, the above-mentioned silicon carbide layer 3A containing aluminum is formed.
Mask layer 4 made of, for example, silicon nitride so as to cover
Was formed (see FIG. 5).

Then, a mixed gas of propane, silane and diborane containing, for example, about 1% hydrogen chloride gas is fed into the reaction furnace and reacted at a temperature of 1400 ° C., as shown in FIG. A silicon carbide layer 3B containing boron at an atomic ratio of about 1% was grown on the central portion of the substrate 1 on which the silicon carbide layer 3A was not formed.

Then, the mask layer 4 was removed as shown in FIG. By the above first step, a silicon carbide body before crystallization was obtained in which two types of silicon carbide layers 3A and 3B were grown in different regions of the central portion and the outer peripheral portion of substrate 1.

Next, the second step is performed. In this process,
As shown in FIG. 8, the inside C of the reaction furnace was set to a nitrogen atmosphere of 0.2 MPa, the temperature was set to 2500 ° C., and the silicon carbide body before crystallization was reacted for 100 hours. By the second step, silicon carbide layer 3A and silicon carbide layer 3B are crystallized to obtain the silicon carbide body shown in FIG.

After that, when the obtained silicon carbide body was examined for polymorphism of the silicon carbide layer 3A and the silicon carbide layer 3B by X-ray diffraction, the region of the silicon carbide layer 3A containing aluminum had a 4H structure. And a silicon carbide layer 3B containing boron
It was confirmed that the region of 6 had a 6H structure.

(Embodiment 2) The silicon carbide body before crystallization obtained in the first step in the above-mentioned Embodiment 1 is treated with 1.0MP
When the reaction was performed for 100 hours in the reaction furnace in which the temperature was set to 2500 ° C. in the nitrogen atmosphere of a, the region of the silicon carbide layer 3A containing aluminum had a 4H structure and the region of the silicon carbide layer 3B containing boron was 3C. The structure was confirmed. That is, by changing the state of the nitrogen atmosphere of the reaction furnace, the area of the silicon carbide layer 3A is changed to the same as in the first embodiment.
The region of the silicon carbide layer 3B can be changed from the 6H structure of Example 1 to the 3C structure while maintaining the H structure.

(Example 3) Instead of the gas used in the first step in Example 1 described above, when a silicon carbide layer was formed, the concentration of aluminum was 1% in atomic ratio and the concentration of boron was in atomic ratio. Gases each having a composition adjusted to 1% were used. Thereby, the aluminum concentration of the silicon carbide layer 3A formed on the outer peripheral portion of the substrate was changed from 3% to 1%, and the silicon carbide layer 3B formed on the central portion of the substrate was the same.

Thereafter, this silicon carbide body was reacted in a reactor having a temperature of 2500 ° C. in a nitrogen atmosphere of 0.2 MPa under the same conditions as in Example 1, and the area containing 1% of aluminum contained 3 C. It was confirmed that the region having a structure and containing 1% of boron had a 6H structure. That is, the region containing aluminum having a different concentration is set as in Example 1.
It is possible to change from the 4H structure to the 3C structure.

(Example 4) Instead of the gas used in the first step in Example 1, when a silicon carbide layer was formed, the concentration of aluminum was 1% by atomic ratio and the concentration of aluminum was 3% by atomic ratio. A gas whose composition was adjusted so that Thereby, the aluminum concentration of the silicon carbide layer 3A formed on the outer peripheral portion of the substrate is changed from 3% to 1%, the third element of the silicon carbide layer 3B formed on the central portion of the substrate is changed from boron to aluminum, and the concentration is changed. It was changed from 1% to 3%.

Then, the silicon carbide body thus obtained was reacted for 100 hours in a reactor having a temperature of 2500 ° C. in a nitrogen atmosphere of 0.5 MPa, and a region having an aluminum concentration of 1% had a 3C structure. Therefore, it was confirmed that the region having an aluminum concentration of 3% had a 4H structure. That is, the polymorphisms of the two regions can be different from those in the first embodiment.

Therefore, according to the present embodiment, it is possible to form different polymorphic silicon carbide layers in the two regions on the substrate, and it is easy to change the control conditions required for the formation, and it is possible to control with good controllability. A shape can be formed.

The above-mentioned Examples 1 to 4 are some of the embodiments of the method of the present invention. The method of the present invention is such that the gas composition used in the first step, the atmosphere of the reaction furnace in the second step, the pressure or By changing the temperature and the like, it is possible to manufacture different ones from the above-mentioned several kinds of silicon carbide bodies.

Further, in the above description, the region on the substrate is divided into two, and two types of silicon carbide layers are formed, but the present invention is not limited to such a configuration, and there are three or more regions on the substrate. The present invention can also be applied to the case where a silicon carbide body is manufactured by dividing and making the polymorphism different in each region, or making some of them the same polymorphism.

[0026]

According to the present invention, polymorphs of silicon carbide having different forbidden band widths can be manufactured on the same substrate with good controllability, and semiconductors that cannot be seen by the conventional method. It becomes possible to provide an element structure, which can contribute to the development of a high-density functional element and a functional element having a three-dimensional structure.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a silicon carbide layer obtained in Example 1.

FIG. 2 is a sectional view showing a manufacturing process of a first step.

FIG. 3 is a sectional view showing a manufacturing process of a first step.

FIG. 4 is a sectional view showing a manufacturing process of a first step.

FIG. 5 is a cross-sectional view showing the manufacturing process of the first step.

FIG. 6 is a cross-sectional view showing the manufacturing process of the first step.

FIG. 7 is a sectional view showing a manufacturing process of a first step.

FIG. 8 is a cross-sectional view showing the manufacturing process of the second step.

[Explanation of symbols]

 1 Substrate 2 Mask Material 4 Mask Material 3A Silicon Carbide Layer 3B Silicon Carbide Layer

Claims (1)

Claim: What is claimed is: 1. A method of manufacturing a silicon carbide body in which a plurality of silicon carbide layers having different polymorphisms are formed in a plurality of regions on a substrate, the method comprising the step of adding to a silicon carbide layer formed in each region. Carbonization including a first step of growing a silicon carbide layer on each region with a different composition or content of the third element to be caused, and a second step of crystallizing each silicon carbide layer obtained in the first step Method for manufacturing silicon body.