JPH0412097A - Compound semiconductor and method for growing the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to compound semiconductors such as ■-v group, ■-■ group, IV-IV group, etc. grown on a porous silicon substrate and a method for manufacturing the same. .

(Prior Art) Attempts have been made to grow compound semiconductors on silicon substrates because they are easy to grow in area, lightweight, have high thermal conductivity, and are inexpensive.

However, since there is a difference in crystal lattice constant of about 4% between silicon and GaAs, for example, when performing heteroepitaxial growth of compound semiconductors with different lattice constants on a silicon substrate, it is difficult to use the normal growth method. However, it is not possible to obtain a good crystal using this method, and methods using, for example, an off-angle silicon substrate whose angle is slightly shifted with respect to the plane index of the substrate single crystal, and a silicon substrate having a Ge buffer layer have been attempted.

Furthermore, rsolid 5tate Technolo
gy (+988-1) Japanese version p, 41-49'', a silicon substrate heat-treated at a high temperature of about 850-900°C is heated at a low temperature of about 400-450°C for 200°C.
A two-step temperature growth method has also been attempted in which a thin GaAs layer of Å or less is grown and then normal high-temperature growth is performed, but it has not always been possible to grow a good crystal. In addition, attempts have been made to use a silicon substrate with a GaAs strained superlattice, but the residual dislocations in the grown layer are only 1.
It has only decreased to about 0.087 cm'. FIG. 4 is an explanatory diagram of temperature control in the above method, and FIG. 3 is a cross-sectional view of the obtained GaAs semiconductor.

Furthermore, “Applied Physics Vol. 57 No. 11 (1988) No. 1
1, pages 0 to 1720, a porous layer with micropores is formed on the surface of a silicon substrate by anodization, and GaAs is deposited on the contact layer, with the aim of alleviating strain stress near the interface due to heteroepitaxial growth. Attempts were made to grow the epitaxial layer, but the crystallinity of the epitaxial layer was not as good as that of the bulk crystal.

(Problems to be Solved by the Invention) The present invention aims to eliminate the above-mentioned drawbacks and provide a compound semiconductor with excellent crystallinity formed on a porous silicon substrate and a method for growing the same.

(Means for Solving the Problems) The present invention provides a compound semiconductor grown on a porous silicon substrate, in which a compound semiconductor layer with a thickness of 10 to 5000 layers is grown by low temperature growth on the surface metamorphic layer of the porous silicon substrate. , a compound semiconductor characterized by further having a compound semiconductor single crystal layer grown at high temperature thereon, and a manufacturing method for growing a compound semiconductor on a porous silicon substrate, in which a silicon single crystal is grown into a porous layer by an anodization method. 200 to 500℃ on top of the surface metamorphic layer of the silicon substrate.
This method of manufacturing a compound semiconductor is characterized by growing a compound semiconductor layer with a thickness of 10 to 5,000 thick by low-temperature growth, and then growing a compound semiconductor single crystal layer on the contact layer at high temperature by a normal growth method.

(Function) Conventionally, a compound semiconductor single crystal layer is grown on a silicon substrate by a two-step growth method, or a compound semiconductor single crystal layer is grown on a porous silicon substrate in which a porous layer is formed on the silicon surface by an anodization method. However, it has not been possible to obtain good crystallinity with low dislocation density.

The present inventors conducted intensive research on a method for directly growing compound semiconductors from the above-mentioned porous silicon substrate without removing the surface metamorphic layer. , by growing a thin compound semiconductor layer with the same composition as the target compound semiconductor at low temperature, and then growing the target compound semiconductor single crystal layer on top of it at high temperature using the usual method, a compound semiconductor with excellent crystallinity can be produced. succeeded in obtaining it. The thin low-temperature growth layer mentioned above is
In addition to having an amorphous or unstable crystal structure, the lattice constant of the target compound semiconductor itself is maintained, so the lattice mismatch between silicon and the compound semiconductor is alleviated, and the compound semiconductor single crystal layer has a low dislocation density and good crystallinity. This seems to make it possible to grow. In addition, the porous silicon layer has a Young's modulus of about 10 compared to normal silicon.
Because of its high flexibility, even when a growth layer of compound semiconductors with significantly different coefficients of thermal expansion is cooled from the growth temperature to room temperature, the strain in the amounts of the two substances is absorbed, resulting in a reduction in the amount of compound semiconductors. Dislocations and residual stress in the conductor growth layer can be significantly reduced.

To explain the present invention specifically, by anodizing in a solution such as hydrofluoric acid at a current density of 0.1 to 200 mA/cm', porous pores having a pore diameter of 20 to 300 pores are formed near the surface of a silicon substrate. After forming a quality layer with a thickness of 5 to 300 um, a growth temperature of 200 to 500 um was applied to the silicon substrate.
A low-temperature grown compound semiconductor layer with a thickness of 10 to 5,000 layers is grown at 100 to 5000 degrees Celsius, and then the growth temperature is raised to 400 to 8QQ degrees Celsius, and the desired compound semiconductor single crystal layer is grown at high temperature using the usual method. .

The thickness and growth temperature of the low-temperature growth layer can be appropriately selected within the above range depending on the compound semiconductor to be grown and the type of growth method. For example, when growing GaAs by the OMVPE method, the thickness is preferably 50 to 2,000 layers, and more preferably 100 to 1,500 layers. Further, the growth temperature can be 200 to 500°C, but in the case of GaAs, 300 to 450°C is suitable.

The temperature for high-temperature growth can be selected between 400 and 800° C., or needs to be at least higher than the temperature for low-temperature growth from the viewpoint of lattice mismatch relaxation.

The high temperature growth temperature for GaAs is 450-700'
C is suitable, and from the point of view of improving crystallinity, 500~
It is preferable to choose 700”C.

(Example) A porous layer was formed on a silicon substrate, and a GaAs single crystal thin film was grown on it by a two-step temperature growth method (without removing the metamorphic layer on the surface of the porous layer) to improve its crystallinity. Examined.

First, to form a porous layer on a silicon substrate, the surface of the silicon substrate is brought into contact with a hydrochloric acid solution, and the current density is set to 20 m^.
/cm' and anodized to form a porous layer with a thickness of 30 μm. In this state, the surface of the porous layer has a thickness of 5
There were 00 metamorphic strata. On this porous silicon substrate, a 150 μm thick GaAs layer was grown by OMVPE at a growth temperature of 420°C, and then a 2.5 μm thick layer was grown in the same manner with the growth temperature raised to 65°C. G
An aAs single crystal thin film was grown.

The dislocation density of the obtained GaAs single crystal thin film is IXIO5
cm-'.

(Comparative Example) A GaAs layer with a thickness of 150 μm by low temperature growth and a GaAs single crystal thin film with a thickness of 2.5 μm by high temperature growth were grown on the surface of a conventional silicon substrate in the same manner as in the example, and the dislocation density was reduced. When investigated, it showed a large value of 4XI07cm-''.

(Effects of the Invention) By adopting the above configuration, the present invention allows compound semiconductors with different lattice constants and coefficients of thermal expansion to grow with good crystallinity even when using a porous silicon substrate that still has a metamorphic layer. Furthermore, even when the growth temperature is cooled to room temperature, residual stress in the compound semiconductor grown single crystal layer can be kept low, thereby providing a compound semiconductor single crystal thin film with low dislocation density and excellent crystallinity. Now I can do it.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a GaAs single crystal grown by a two-step temperature growth method on a porous silicon substrate with a metamorphic layer;
FIG. 2 is an explanatory diagram of temperature control for growing the GaAs single crystal shown in FIG. 1, and FIG. 3 is a cross-sectional view of a GaAs single crystal grown by a two-step temperature growth method on a conventional silicon substrate.
FIG. 4 is an explanatory diagram of temperature control for growing the GaAs single crystal shown in FIG. 3. Figure 1 Figure 2 Time

Claims (2)

[Claims] (1) In a compound semiconductor grown on a porous silicon substrate, a compound semiconductor layer with a thickness of 10 to 5000 Å grown at low temperature is formed on the surface metamorphic layer of the porous silicon substrate, and a compound semiconductor layer grown at high temperature is added on top of the compound semiconductor layer grown at a low temperature. A compound semiconductor characterized by having a crystal layer. (2) In a manufacturing method of growing a compound semiconductor on a porous silicon substrate, 20%
A method for manufacturing a compound semiconductor, comprising growing a compound semiconductor layer with a thickness of 10 to 5000 Å by low-temperature growth at 0 to 500°C, and growing a compound semiconductor single crystal layer on the layer at high temperature by a normal growth method. .