JPS63164310A - Formation of compound semiconductor multiplayered film - Google Patents

Abstract

PURPOSE:To enhance the steepness in compositional change as well as to contrive accomplishment of sharp improvement in characteristics by a method wherein, after a non-doped semiconductor layer has been formed in the reaction furnace in which films are formed using an organic metal heat decomposition method, said semiconductor layer is once moved to outside the reaction furnace, dopants to be used for formation of conductive type are ion-implanted, and the mixture of the raw gas to be used for the semiconductor layer formed subsequently can be prevented. CONSTITUTION:A p-type GaAs substrate 3 is placed on the surface of a susceptor 2, and after a reaction furnace 1 has been evacuated, a susceptor 2 and the substrate 3 are heated up to the prescribed temperature using a coil 4 to be used for high frequency heating. Then, arsine and trimethylgallium are introduced into the reaction furnace 1 respectively using hydrogen gas as carrier gas, and a non-doped GaAs semiconductor layer is deposited on the surface of the substrate 3. Subsequently, the substrate 3 is once picked out from the reaction furnace 1, and an ion-implanting operation is performed in the furnace to be used for other ion-implantation. The substrate 3 is brought back to the reaction furnace 1 again, and first, an annealing treatment is performed. After the annealing treatment is finished and the temperature of the substrate 3 has been dropped to the prescribed temperature, a p-type GaAlAs semiconductor layer 23 is grown. Through these procedures, the n-type semiconductor layer and the like of high steepness such as the current constriction layer and the like effectively used in a semiconductor layer can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for producing G on a substrate such as GaAs using an organic metal as a raw material.
The present invention relates to a method for forming a compound semiconductor multilayer film in which a compound semiconductor layer such as aA I As is grown in a vapor phase.

[Prior art]

GaA I As, GaA is grown on a substrate such as GaAs or InP by epitaxial growth using an organic metal as a raw material.
I Organometallic thermal decomposition method (MOCVI method: Meta
l Organic Chemical Vapor
The uniformity of film thickness, Ijl
Its practical application is being studied because it has excellent properties such as thickness controllability and ease of mass production.

FIG. 4 is a schematic diagram showing how a compound semiconductor multilayer film is formed by the conventional MOCVD method. While heating the substrate 3 to a predetermined temperature, the reactor l is heated.
The raw material gas is supplied through the supply pipe 5 connected to one end of the reactor 1, and the exhaust pump 6a is driven to exhaust the raw material gas from the exhaust pipe 6 connected to the other end of the reactor 1. A compound semiconductor layer such as GaAs is grown on the surface of the substrate 3 by vapor phase epitaxial growth in the process of flowing the current in the direction of the white arrow.

With such equipment, for example, GaA of p-type conductivity can be
n-type GaAs semiconductor layer, p-type GaA IA on s substrate
When forming a compound semiconductor multilayer film formed by laminating S layers, first, arsine (A31
3), H2S, which is an n-type dopant, and trimethylgallium (TMG) using hydrogen as a carrier gas are introduced into the reactor 1 to form an n-type GaAs layer to the required thickness. Dopants dimethylzinc (DMZ) and trimethylaluminum (TMA)
) is introduced into a reactor l and p-type GaAIAs is grown.

[Problem that the invention seeks to solve]

By the way, in the conventional MOCVD method for forming a compound semiconductor multilayer film, the compound semiconductor layer is grown by thermally decomposing a gaseous organic metal, so the growth is governed by a thermal equilibrium state, and the raw material It is necessary to make various conditions such as gas component ratio and temperature uniform over the entire surface of the substrate, and the response of the controller etc. is slow especially at the initial stage of growth or when switching, such as when growing a GaAsN film on a GaAs film. Therefore, mixing of the raw material gas components is unavoidable, resulting in insufficient steepness of the components, resulting in problems such as affecting product characteristics.

FIG. 5 is a graph showing the carrier concentration profile of each layer in a compound semiconductor multilayer film manufactured by a conventional method, and the horizontal axis shows the dimensions (μm) of each part in the depth direction from the layer surface.
), and the vertical axis shows the carrier concentration (am −3”).As is clear from this graph, the n-type G
p-type GaA j! formed on the aAs layer. It can be seen that n-type GaAs carriers are mixed in the As layer.

The present invention has been made in view of the above circumstances, and its object is to provide a compound semiconductor multilayer film that can significantly increase the steepness of carriers between layers formed in a stacked state next to each other. To provide a method for forming.

[Means for solving problems]

In the method of the present invention, a non-doped semiconductor layer is formed in a reactor in which formation/destruction is carried out by an organometallic thermal decomposition method, and then this is temporarily transferred outside the reactor to add a dopant for forming a conductivity type. Implant ions.

[Effect]

Depending on the method of the present invention, there are no carriers for the previously formed semiconductor layer in the reactor, and mixing with the raw material gas for the subsequently formed semiconductor layer does not occur, which can increase the steepness of the composition change. .

〔Example〕

The method of the present invention will be specifically explained below based on the drawings. FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention,
In the figure, 1 is a reactor, 2 is a susceptor, 3 is a substrate, 4 is a high-frequency heating coil, 5 is a raw material gas supply pipe, 6 is an exhaust pipe,
6a indicates an exhaust pump.

The reactor l is equipped with a susceptor 2 for placing a substrate 3 therein,
Further, a high-frequency heating coil 4 for heating the susceptor 2 and the substrate 3 is disposed outside facing the location of the susceptor 2, and furthermore, a source gas supply pipe 5 is provided at one end, and a source gas supply pipe 5 is provided at the other end. An exhaust pipe 6 connected to an exhaust pump 6a is connected to each of the exhaust pipes 6.

The supply pipe 5 has flow rate controllers 10a, 10b, 1
Pipe lines 11a, llb, each equipped with 0c...10g.
...l1g are connected respectively. One end of line 11a is connected to a source of hydrogen sulfide (H2S), one end of line 11b is connected to a source of arsine (Ad3), and one end of line 11b is connected to a source of arsine (Ad3).
One ends of c to l1g are all connected to a hydrogen gas (H2) source.

On the other hand, the i ends of the pipes 11a, llb, and llc are in a state where they are merged with each other, and the other end of the pipe lid is in a state where they are joined with the pipes 7a, 8a, and 9a of the bubbler 7.8.9, which will be described later. Then, the other end of the pipe lie ~ 11. is a bubbler 7.8
．． They are respectively connected to the supply pipes 5 via pipes 9 in a state where they merge with the other end of the pipe lid.

The bubbler contains an organic compound such as trimethyl gallium (TMG), the bubbler 8 contains trimethyl aluminum, and the bubbler 9 contains dimethyl zinc. Hydrogen gas is used as a carrier gas to selectively enter the reactor 1. It is now being supplied.

Next, as shown in FIG. 2, a GaAs substrate (Zn TODO-M: I
C1m-') 21, a GaAs semiconductor layer 22 of n-type conductivity is formed with a thickness of 0.6 μm1, and a p-type GaAs
A process of manufacturing a semiconductor device in which IAs semiconductor layers 23 having a thickness of 0.2 μm are laminated in this order using the MOCVD method will be described.

First, a p-type GaAs substrate 3 is placed on the surface of the susceptor 2, and after evacuating the reactor 1 through the exhaust pump 6a and exhaust pipe 6, the susceptor 2 and substrate 3 are heated using a high-frequency heating coil 4. Heat to the specified temperature.

Next, trimethylgallium is introduced into the reactor 1 from the bubbler 7 using hydrogen gas controlled by the flow rate controller 10c as a carrier gas and arsine controlled by the flow rate controller 10b and hydrogen gas controlled by the flow rate controller 10e as carrier gases. At the same time, a non-doped GaAs semiconductor layer is deposited on the surface of the substrate 3 by introducing hydrogen gas controlled by a flow rate controller 10d for dilution. Undoped GaAs to the required thickness
After forming the semiconductor layer, each flow controller is closed, the substrate 3 is temporarily taken out from the reactor 1, and ions are implanted in another ion implantation furnace.

In the ion implantation process, 54, for example, is used as an n-type dopant, and it is irradiated with 2×lQ' under a power of 200 keV.
This is done by injecting at the rate of csi-'.

During the implantation, for example, the ion current is detected and the implantation is terminated when the ion current reaches a predetermined value. Return the substrate 3 to the reactor l again,
First, an annealing process is performed. The conditions for the annealing treatment are, for example, such that the substrate 3 is heated and held at 800° C. for 30 minutes by high-frequency heating by the coil 4 in an arsine atmosphere. After the annealing process is completed, wait until the temperature of the substrate 3 drops to a predetermined temperature, and then heat the p-type GaA IA.
s semiconductor layer 23 is grown.

First, arsine controlled by the flow rate controller 10b and hydrogen controlled by the flow rate controller 10f and Log are used as carrier gases, and trimethylaluminum is introduced from the bubbler 8, and dimethylzinc, which is a p-type dopant, is introduced into the reactor 1 from the bubbler 7. to be introduced. By this, n
A p-type GaA I As semiconductor layer 23 is formed on the GaAs-type semiconductor layer 23 .

The carrier concentration profile in the compound semiconductor device manufactured in this way is as shown in FIG.
In the figure, the horizontal axis represents the dimension (μm) from the surface to each part in the depth direction, and the vertical axis represents the carrier concentration (C11-'').

As is clear from this graph, the n-type Ga at the interface between the n-type GaAs semiconductor layer and the p-type GaA 1^S semiconductor layer
It can be seen that the carrier concentration of the As semiconductor layer is zero, and its steepness is extremely good.

Such a highly steep n-type semiconductor layer is effective as, for example, a current confinement layer in a semiconductor laser.

〔effect〕

As described above (in the case of the method of the present invention, the steepness of the components at the interface between adjacent eyebrows is high, and it has an excellent effect that can be applied to the manufacture of various semiconductor devices to significantly improve the characteristics. .

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, FIG. 2 is a cross-sectional structural diagram of a semiconductor device manufactured by the method of the present invention, and FIG. 3 is a carrier concentration profile in the semiconductor device as shown in FIG. FIG. 4 is a schematic diagram showing an implementation state according to the conventional method, and FIG. 5 is a carrier concentration profile in a semiconductor device manufactured by the conventional method.

Claims (1)

[Claims] 1. In the process of stacking a plurality of compound semiconductor layers on a compound semiconductor substrate by an organometallic thermal decomposition method in a reactor for vapor phase growth, the compound semiconductor layer is formed in the reactor. a step of ion-implanting a dopant having a p-type or n-type conductivity into the compound semiconductor layer outside the reactor; and a step of annealing the semiconductor layer within the reactor after the ion implantation. A method for forming a compound semiconductor multilayer film, comprising: 2. The method for forming a compound semiconductor multilayer film according to claim 1, wherein the compound semiconductor layer is a compound of Group III-V of the periodic table. 3. The method for forming a compound semiconductor multilayer film according to claim 1, wherein the p-type dopant is Zn, Mg, or Be. 4. The method for forming a compound semiconductor multilayer film according to claim 1, wherein the n-type dopant is Si, Te, Se, or S. 5. The method for forming a compound semiconductor multilayer film according to claim 1, wherein the annealing step is performed in a source gas atmosphere in the reactor.