JPH07221027A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a steep hetero interface on a quantum fine line structure or a quantum box structure. CONSTITUTION:Temperature distribution is formed by generating a holographic interference pattern on a first compound semiconductor layer 4 by light in the crystal growing chamber of a crystal growing device, and a quantum fine line structure is formed by the first compound semiconductor layer 4 by changing the mole ratio of the elements that compose the first compound semiconductor layer 4. Then, an Al GaAs clad layer 7, which is a second compound semiconductor layer, is crystal-grown without taking out the semiconductor device from the crystal growing chamber. The structure provided with the buried quantum fine line structure that has a steep hetero interface is formed in the series of crystal growing processes in the crystal growing chamber without oxidizing the quantum fine line structure nor making physico-chemical damages due to etching and ion implantation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device having a compound semiconductor layer having a quantum structure such as a quantum wire structure or a quantum box structure.

[0002]

2. Description of the Related Art A semiconductor device having a quantum wire structure or a quantum box structure using a compound semiconductor, when applied to an active layer of a semiconductor laser, has a lower threshold current than a currently realized quantum well structure. It is expected that the temperature dependence of the threshold current will be reduced, the relaxation oscillation frequency will be improved, and the spectral line width will be narrowed. In addition, when applied to electronic devices, not only speedup of conventional electronic devices but also application to devices in the mesoscopic region such as an electron wave interference device or a single electronic device can be expected. An example of a method of manufacturing a semiconductor device having a quantum wire structure or a quantum box structure using a compound semiconductor, which has been reported so far, will be shown below.

The first method is to grow a compound semiconductor layer in a crystal, take it out of a crystal growth apparatus into the atmosphere, form a quantum wire structure or a quantum box structure by etching, and then recrystallize it to grow a quantum wire structure or a quantum box structure. This is a method of embedding the structure.

In the second method, a compound semiconductor layer is crystal-grown and taken out from the crystal growth apparatus into the atmosphere to form an insulating film (SiO2 or SiO2) in a region where a quantum wire structure or a quantum box structure is formed.
SiN, etc. pattern is formed, and the crystal is selectively grown on the part where the insulation film is not formed, and then the crystal growth conditions are changed to perform the embedded crystal growth, or the insulation film is removed by etching in the air. After that, it is a method of performing buried recrystallization growth.

The third method is to form irregularities in a region where a quantum wire structure or a quantum box structure is formed on a substrate in advance, and then,
This is a method of growing crystals.

The fourth method is to grow a quantum well structure and perform ion implantation using a focused ion implantation apparatus.
This is a method of locally destroying the quantum well structure and then subjecting it to a liquid crystal by applying heat treatment to form a quantum wire structure or a quantum box structure.

[0007]

In the first and second methods described above, since the quantum wire structure or quantum box structure is exposed to the atmosphere once during the formation, the side wall of the quantum wire structure or quantum box structure is It is oxidized and the interface collapses. As a result, there is a problem that the ideal quantum effect does not appear. Further, in the third and fourth methods, there is no fear that the side wall of the quantum wire structure or the quantum box structure is exposed to the atmosphere, but the interface of the quantum structure is not blurred and steep, and the ideal quantum effect is obtained. There was a problem that it did not appear.

The present invention has been made in view of the above problems.
An object of the invention is to provide a method of manufacturing a semiconductor device capable of forming a steep hetero interface having an ideal quantum effect in a quantum wire structure, a quantum box structure, or another quantum structure.

[0009]

In order to achieve the above object, a method of manufacturing a semiconductor device according to a first aspect of the present invention comprises a first compound semiconductor layer having a quantum wire structure or a quantum box structure,
In a method of manufacturing a semiconductor device having a second compound semiconductor layer formed on the first compound semiconductor layer, holographic interference of light or particle beams with the first compound semiconductor layer in a crystal growth chamber of a crystal growth apparatus. A pattern or surface electromagnetic wave is generated to form a temperature distribution, and the molar ratio of the elements forming the first compound semiconductor layer is changed to form the first compound semiconductor layer into a quantum wire structure or a quantum box structure. It is characterized in that the second compound semiconductor layer is crystal-grown without taking the semiconductor device out of the crystal growth chamber.

According to a second aspect of the method of manufacturing a semiconductor device, a first compound semiconductor layer having a quantum wire structure or a quantum box structure, and a second compound semiconductor layer formed on the first compound semiconductor layer. In the method for manufacturing a semiconductor device having: a temperature distribution is formed by generating a holographic interference pattern or a surface electromagnetic wave by light or a particle beam at a formation position of the first compound semiconductor layer in a crystal growth chamber of a crystal growth device, After the crystal growth is performed while changing the molar ratio of the elements forming the first compound semiconductor layer to form the first compound semiconductor layer having the quantum wire structure or the quantum box structure, the semiconductor device is placed outside the crystal growth chamber. The present invention is characterized by including a step of crystal-growing the second compound semiconductor without taking it out.

Furthermore, a method of manufacturing a semiconductor device according to a third aspect is a method of manufacturing a semiconductor device in which a compound semiconductor layer using an organic metal is crystal-grown, wherein the compound semiconductor layer is exposed to light or light in a crystal growth chamber. It is characterized by forming a holographic interference pattern by a particle beam or a temperature distribution by a surface electromagnetic wave to change the molar ratio of the elements constituting the compound semiconductor layer.

[0012]

The method of manufacturing a semiconductor device according to the present invention is performed in a crystal growth chamber in which a compound semiconductor crystal using an organic metal is grown.
After growing the first compound semiconductor layer on the semiconductor substrate, the holographic interference pattern or surface electromagnetic wave using light or particle beam on the first compound semiconductor layer with the semiconductor substrate kept in the crystal growth chamber. Causes the first
After forming the quantum wire structure or the quantum box structure by forming a periodic temperature distribution on the compound semiconductor layer, the second compound is formed on the quantum wire structure or the quantum box structure with the semiconductor substrate being placed in the crystal growth chamber. It is characterized by growing a semiconductor layer.

Taking the case of forming an In _x Ga _1-x As quantum wire structure as an example, if a periodic temperature distribution is formed on the first compound semiconductor layer, the organic metal contained in the first compound semiconductor layer is formed. , Trimethylindium (TMI), and trimethylgallium (TMG) are thermally decomposed at their own temperatures to form indium and gallium, which combine with arsenic to form InGaAs crystals. The molar ratio of indium and gallium can be periodically changed in the first compound semiconductor layer. As a result, In _x Ga _1-x As, In _y Ga _{1-y is} formed in the first compound semiconductor layer.
A structure (quantum wire structure or quantum box structure) in which portions with different molar ratios such as As are periodically formed can be formed. In addition, the already formed first compound semiconductor layer can have not only a quantum wire structure or a quantum box structure but also a quantum wire structure or a quantum box structure with a periodic temperature distribution formed on the semiconductor substrate. It is also possible to grow the first compound semiconductor layer that it has.

Further, the quantum wire structure or the quantum box structure forming step and the second compound semiconductor layer forming step are continuously performed in the crystal growth chamber, whereby the interface of the quantum wire structure or the quantum box structure, or those interfaces. Oxidation of the interface between the quantum structure and the second compound semiconductor layer can be prevented, and a steep hetero interface can be formed.

[0015]

EXAMPLE FIGS. 1 and 2 show an example of a semiconductor laser using a quantum wire structure. FIG. 1 is a perspective view showing the structure of a semiconductor laser, in which a GaAs buffer layer 2, AlGa
In _x forming the As clad layer 3 and the first compound semiconductor layer 4
Ga _1-x As quantum wire type active layer 5, In _y Ga _1-y As type barrier layer 6, AlGaAs cladding layer 7 which is the second compound semiconductor layer,
FIG. 2 shows a structure in which the GaAs contact layer 8 is sequentially crystal-grown. FIG. 2 is a perspective view showing an In _x Ga _1-x As quantum wire structure of a semiconductor laser. When high density electrons and holes are generated in a semiconductor laser, a light amplification phenomenon called stimulated emission occurs in In _x.
Since Ga _1-x As occurs in the quantum wire type active layer 5, this In _x Ga
_{If a} reflection surface is provided perpendicularly to the _1-x As quantum wire type active layer 5, the light is amplified while it travels back and forth between the reflection surfaces to emit a laser beam.

FIG. 3 is a schematic view of a crystal growth apparatus used in the method of manufacturing a semiconductor device of the present invention. As the crystal growth apparatus, a normal metal organic vapor phase epitaxy (MOVPE) apparatus or a metal organic molecular beam epitaxy (MOMBE) apparatus is used, and the semiconductor substrate 1 placed on the sample stage 10 in the crystal growth chamber 9 is used.
1 is an apparatus in which an optical system 13 capable of forming a holographic interference pattern by using a laser 12 is incorporated. Figure 3
As shown in FIG. 1, the optical system 13 includes, for example, a laser 12 that emits a laser beam and a lens 14 that focuses the laser beam.
a, 14b, pinhole 1 for removing excess laser beam
5, a beam splitter 16 for separating the laser beam into two beams, mirrors 17a and 17b for changing the irradiation position of the laser beam, and an opening 9 formed in the crystal growth chamber 9.
Viewport 1 fixed on a and transmitting laser light
8 and.

Next, FIG. 4 shows a crystal growth mechanism in the present invention. (A) is a diagram showing the relationship between the light intensity of the holographic interference pattern and the position on the semiconductor substrate. By thus periodically forming the holographic interference pattern on the semiconductor substrate, a temperature distribution according to the light intensity distribution can be formed on the semiconductor substrate.

FIG. 4B is a diagram showing the relationship between the molar ratio of the group III element composing the compound semiconductor layer corresponding to the light intensity of the holographic interference pattern and the position of the semiconductor substrate.
It is shown that portions having different molar ratios are alternately formed corresponding to the period of light intensity. In this embodiment, FIG.
And, as shown in FIG. 2, the molar ratio of the group III elements is different.
The In _x Ga _1-x As quantum wire type active layers 5 and the In _y Ga _1-y As type barrier layers 6 are alternately formed.

In the case of not irradiating the holographic interference pattern, the In _x Ga _1-x As quantum wire type active layer 5 and the In _y Ga _1-y As
The type barrier layer 6 is a layer made of the same material, but when the holographic interference pattern is applied to the first compound semiconductor layer 4 to form a light intensity distribution, a so-called temperature distribution, on the semiconductor substrate, a group III group is formed. Raw materials such as organic metal, trimethylindium (TMI), and trimethylgallium (TMG) are thermally decomposed at their own temperatures, and become indium and gallium, which are combined with arsenic to form an InGaAs crystal.
The decomposition efficiency of indium and gallium is modulated by the formation of the temperature distribution according to the light intensity, and In _x Ga _1-x As, In _y Ga _1-y
Different compound semiconductor layers such as As grow. here,
Since the temperature characteristics of decomposition efficiency of indium and gallium are different, by forming a temperature distribution corresponding to the light intensity,
Since it is possible to change the molar ratio of indium and gallium, which can greatly change the refractive index of the compound semiconductor material, it is possible to control the quantum confinement effect by locally irradiating light. . On the other hand, the period Λh of In _x Ga _1-x As and In _y Ga _1-y As alternately formed by the holographic interference pattern is the wavelength λ of the laser and the angle θ of irradiation on the semiconductor substrate (from the vertical direction). It is determined by the incident angle of the laser beam (see FIG. 3) and is expressed by the following equation.

[0020]

[Equation 1]

Using a laser beam of short wavelength, angle θ
It is also possible to form a quantum wire structure with a shorter period by reducing

5 and 6 show different embodiments of a semiconductor laser having a quantum box structure formed by using the method for manufacturing a semiconductor device of the present invention. 5 is a perspective view showing the structure of the semiconductor laser, and FIG. 6 is a perspective view showing the quantum box structure of the semiconductor laser. The semiconductor laser shown in FIG. 5 has GaAs on a GaAs substrate 19.
In _x Ga _1-x As quantum box type active layer 23 constituting the buffer layer 20, the AlGaAs cladding layer 21, and the first compound semiconductor layer 22.
And In _y Ga _1-y As barrier layer 24, AlGaAs cladding layer 2
5. The GaAs contact layer 26 is sequentially grown.

The crystal growth apparatus is the same as that shown in FIG.
is there. Ordinary metal-organic vapor phase epitaxy (MOVPE) equipment or
Using metalorganic molecular beam epitaxy (MOMBE) equipment,
Holographic interference with a laser beam on a semiconductor substrate.
This is a device incorporating an optical system capable of forming a pattern.
Differences from the case of constructing the quantum wire structure shown above
The point has a quantum box structure by using an s-polarized laser beam.
It is the point that is formed. Holographic interference period Λh
, The period Λ of the surface electromagnetic wave generated orthogonally to
r is In_xGa_1-xAs real part of dielectric constant of active layer material, imaginary number
Ε for each ₁, Ε₂Will be shown as follows
It (Jpn.J.Appl.Phys.Vol.32 (1993) 1308).

[0024]

[Equation 2]

As in the above equation, the period Λ r of the surface electromagnetic wave is determined by the wavelength λ, and the quantum wire structure with a shorter period can be formed by using a laser with a short wavelength.

In the above embodiments, an example of forming an InGaAs quantum structure on a GaAs semiconductor substrate was described as an example using a III-V group compound semiconductor, but the present invention is limited to the materials shown in the examples. Not AlGaAs,
Materials such as InGaAsP and InGaP, or II-VI such as ZnSe
It can also be applied when a group compound semiconductor material is used. Further, in the embodiment, the holographic interference pattern or the surface electromagnetic wave is generated by light, but it may be configured to be generated by a particle beam such as an electron beam or X-ray.

[0027]

As described above, according to the method of manufacturing the semiconductor device of the first or second aspect, the quantum wire structure or the quantum box structure is not exposed to the atmosphere to be oxidized, and etching is performed. It is possible to form a structure with a quantum wire structure or a quantum box structure embedded in a series of crystal growth steps in a crystal growth chamber without causing physicochemical damage such as ion implantation or ion implantation. You can

Further, according to the method for manufacturing a semiconductor device of the third aspect, the compound semiconductor layer on which the crystal is grown is not exposed to the atmosphere to be oxidized, and physicochemical damage such as etching and ion implantation is given. It is possible to form a structure in which a compound semiconductor layer having a steep hetero interface is embedded by a series of crystal growth steps in the crystal growth chamber without the need.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a semiconductor laser formed by using a method for manufacturing a semiconductor device according to the present invention.

2 is a perspective view showing an In _x Ga _1-x As quantum wire structure of the semiconductor laser shown in FIG. 1. FIG.

FIG. 3 is a configuration diagram showing a schematic configuration of an example of a crystal growth apparatus used in a method for manufacturing a semiconductor device according to the present invention.

FIG. 4 is a diagram illustrating a crystal growth mechanism of a method for manufacturing a semiconductor device according to the present invention.

FIG. 5 is a perspective view showing another embodiment of a semiconductor laser formed by using the method for manufacturing a semiconductor device according to the present invention.

6 is a perspective view showing an In _x Ga _1-x As quantum box structure of the semiconductor laser shown in FIG.

[Explanation of Codes] 4 First Compound Semiconductor Layer 7 AlGaAs Clad Layer (Second Compound Semiconductor Layer) 9 Crystal Growth Chamber

Claims (3)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: a first compound semiconductor layer having a quantum wire structure or a quantum box structure; and a second compound semiconductor layer formed on the first compound semiconductor layer. In the crystal growth chamber, a holographic interference pattern by light or particle beams or a surface electromagnetic wave is generated in the first compound semiconductor layer to form a temperature distribution, and the molar ratio of the elements forming the first compound semiconductor layer is changed. After the first compound semiconductor layer has a quantum wire structure or a quantum box structure, the second compound semiconductor layer is crystal-grown without taking the semiconductor device out of the crystal growth chamber. Production method. 2. A method of manufacturing a semiconductor device, comprising: a first compound semiconductor layer having a quantum wire structure or a quantum box structure; and a second compound semiconductor layer formed on the first compound semiconductor layer. In the crystal growth chamber of the first compound semiconductor layer, a holographic interference pattern by light or a particle beam or a surface electromagnetic wave is generated at the formation position of the first compound semiconductor layer to form a temperature distribution, and the moles of elements constituting the first compound semiconductor layer are formed. Crystal growth is performed while changing the ratio to form the first compound semiconductor layer having a quantum wire structure or a quantum box structure, and then a second compound semiconductor is crystal grown without taking the semiconductor device out of the crystal growth chamber. A method for manufacturing a semiconductor device, comprising: 3. A method for manufacturing a semiconductor device in which a compound semiconductor layer using an organic metal is crystal-grown, wherein the compound semiconductor layer is holographically interfering with light or a particle beam in the crystal growth chamber, or by a surface electromagnetic wave. A method of manufacturing a semiconductor device, comprising the step of forming a temperature distribution and changing the molar ratio of the elements forming the compound semiconductor layer.