JPH0456128A - Manufacture of group ii-vi compound semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate a lattice defect due to misalignment of a lattice, change of properties due to diffusion from a substrate to a grown layer by forming the substrate of a bulk crystal of group II-VI compound semiconductor containing Zn as a constituent element by a temperature difference method using Se-Te solvent, and epitaxially growing on the substrate by the method using Zn solvent. CONSTITUTION:Group II-VI compound semiconductor containing Zn such as ZnSe, ZnS, etc., as a constituent element is grown. Its substrate crystal 12 is disposed on a heat sink 26 for slicing formed bulk crystal in a wafer state, and secured by a substrate stopper 25. Solution 22 using Zn as solvent is contained on the crystal 12. Further, ZnSe crystal 23 to become a growing material is contained. An ampule is treated in an electric furnace having a temperature gradient. Melted crystal 23 for a source is transported in a temperature gradient, and epitaxially grown on the crystal 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing If-VIl interplanar compound semiconductor devices, and particularly to efficiently manufacture low-resistance ■-■ intergroup compound semiconductor devices. ■-■ Intergroup compound semiconductor device that can be used! Relating to a manufacturing method.

C. Prior Art] FIGS. 7(A) to (C) show cross-sectional structures of conventional semiconductor devices using zinc selenide (ZnSe), which is an I-VI intergroup compound. Such semiconductor devices emit light. Often used as a component of diodes. Although only an n-type region is shown, a diode structure can be formed by growing a p-type head region thereon or by forming a p-type head region in the topmost n-type region.

The semiconductor device shown in FIG. 7A is manufactured, for example, by the following manufacturing method. ZnS, Z as a substitute for e substrate
Gallium arsenide (GaAs) has a lattice constant relatively similar to n5e.
) is used as the substrate crystal 101. On this n-type GaAs substrate crystal 101, an n-type Zn5e crystal 102 is epitaxially grown using a temperature difference method using a Zn solvent.

The semiconductor device shown in FIG. 7(B) is manufactured, for example, by the following manufacturing method. First, crystals of n-type Zn5e 111 are grown on a heat sink below the solvent (at a low temperature [111) by a temperature difference method using a Zn solvent. This n-type Zn
On the 5e crystal 111, an n-type Zn5e crystal 112 is epitaxially grown by the temperature difference method using the same Zn solvent.

The solubility of Zn5e in Zn solvent cannot be said to be sufficiently high,
Obtaining high growth rates is not easy.

When Se is used as the solvent, the solubility is considerably improved.

When Te is used as the solvent, the solubility is significantly improved.

An intermediate solubility can be obtained with a mixed solvent of 5e-Te. On the other hand, the vapor pressure of these solvents is lowest for Te, somewhat higher for Zn, and extremely high for S e Chi.

The semiconductor device 1 shown in FIG. Add the Group to Group II elements, and
II) n-type Z n, by temperature difference method on the heat sink.
Crystal growth of S e 121 is performed.

[Problem to be solved by the invention] In the method for manufacturing a semiconductor device shown in FIG. 7(A) described above, since crystals with different constituent elements are used for the substrate, lattice defects due to lattice mismatch and transfer from the substrate to the growth layer occur. There is a change in the quality of the crystal layer due to the diffusion of

In the method for manufacturing the semiconductor device 1 shown in FIG. 7(B) described above, the growth rate when growing Zn5e, which becomes the substrate crystal, using a Zn solvent is slow (0.5 μm/hour or less), so the substrate must have an appropriate thickness. It takes time to obtain crystals.

In the method for manufacturing the semiconductor device shown in FIG. 7(C) described above, Se
Since the crystal is grown in a solvent containing a considerable amount of the crystal, the composition of the grown crystal deviates from the stoichiometric composition ratio (stoichiometry), so that the resistance of the grown crystal does not become low.

An object of the present invention is to provide a method for efficiently manufacturing a II-VII interlayer compound semiconductor device that is free from lattice defects and alterations in crystal layers and has low resistance! It is to provide.

[Means for Solving the Problems] According to the present invention, a group III or group VII element is added to a solvent in which Te and Se are mixed in an arbitrary ratio, and a source crystal is placed in a high temperature part, so that the temperature difference can be reduced. A first step of depositing a ■-■ group compound semiconductor containing Zn as a constituent element in a low-temperature region by a method, and an n-VI prepared in the first step.
a second step of forming the group compound semiconductor crystal into a flat plate;
Source crystals and group III or VI suitable for Zn solvent
- Containing Zn as a constituent element on the tabular crystal formed in the second step by adding a group I element and forming it by a temperature difference method.
A method for manufacturing a II-VII interlayer compound semiconductor device is provided, which comprises a third step of epitaxially growing a group II compound semiconductor.

Note that in the case of crystal growth containing S, such as ZnS and ZnSSe, S may be mixed with 5e-Te in the solvent.

[Effects of Zn5e compared to Zn solvent
With high solubility, high growth rates can be obtained.

Furthermore, as the mixing ratio of Te increases, the solubility increases and the vapor pressure decreases, but the amount of Te mixed into the crystal also increases.

According to the above-mentioned first step, a 1-2 group compound semiconductor crystal having Zn added with a group III or VII element as a constituent element can be obtained at a relatively high growth rate.

By forming this ■-■ group compound semiconductor crystal into a flat plate shape in the second step, a plurality of substrate crystals can be obtained.

In the third step, a suitable source crystal and II
Group I or Group VII elements are added and a group ■-■ group compound semiconductor having Zn as a constituent element is epitaxially grown on the tabular crystal formed in the second step. Therefore, the substrate crystal, which still had high resistance after the second step,
When the crystal is subjected to heat treatment, the stoichiometry of the crystal is improved and the resistance is lowered.

[Solid Line Example] As a specific example of the present invention, taking Zn5e, which is a ■-■ group compound semiconductor, as an example, the present invention will be explained below. It's a method.

The first step is to create an n-type crystal that will serve as a substrate. Referring to FIG. 1, a heat sink 6 made of a material with good thermal conductivity such as carbon is housed and fixed at the bottom of a crystal growth ampoule 1 made of quartz. On the heat sink 6, a solution obtained by mixing Se and Te in an arbitrary ratio is accommodated as the solvent 2. In solvent 2, III
Group or VII elements are added in appropriate amounts. Furthermore, a Zn5e crystal 3 serving as a growth material (source crystal) is accommodated. After the solvent 2 and source crystal 3 are placed in the growth ampoule 1, the inside of the ampoule is evacuated and sealed. An ampoule with such a configuration is shown in the figure with cloth 11'','
1.1 Temperature gradient as shown on the side (for example, ΔT=5-15℃/
3) placed in an electric furnace with Then, the source crystal 3 in the upper high-temperature part is dissolved and diffused in the solvent 2 until it reaches saturated solubility. The melted source crystal 3 is transported through a temperature gradient, and the top surface of the He-l-synchro is turned over by 71 inches. Since the temperature near the upper surface 7 of the lower heat sink 6 is lower than that of the upper portion, the solution becomes a supersaturated solution and bulk crystals grow on the upper surface 7 of the heat sink 6 . The upper surface 7 of the carbon heat sink 6 on which crystals are grown is formed into a flat and mirror surface.

The growth rate by this temperature difference method varies depending on the mixture ratio of Se:Te, the growth temperature Tg (the temperature near the upper surface 7 of the heat sink 6 where the crystal grows), the temperature gradient, etc. −
As an example, Se:Te=30 near 0, growth temperature Tg
FIG. 2 shows the dependence of the growth rate on the temperature gradient and T when the temperature is 950°C.

The heat sink is a carbon rod with a diameter of 8m and a length of 100m. The graph shows the growth rate near the periphery of a crystal growing in bulk. Compared to the growth rate when using Zn solvent, which is approximately 0.5 μm/'hour or less, the growth rate is approximately 10 times faster. It can be seen that the growth rate can also be easily obtained.

In addition, when the mixing ratio of S e - Te is changed, the growth rate changes with the amount of Te, for example, as follows.

Se:Te growth rate (m/hr) 10:90
6.0 30 near 0, 5. 045, ;55
As the amount of 3.8Te increases, the pressure inside the ampoule decreases and the growth rate increases, but Te is mixed into the crystal.

Although the amount of Te mixed can be reduced by increasing the amount of Se, the pressure inside the ampoule increases and the growth rate decreases. Zn,S
For the growth of compound semiconductors in the X--■ group, such as e, zns, etc., containing Z and n as constituent elements, a solvent mixed with an appropriate amount of S e-76 is preferable. In the case of crystals containing S, S is further mixed. It's okay.

The second step is a step of slicing the bulk crystal produced by the above-described growth method into C-shaped pieces using a slicing machine or the like. In FIG. 3, numeral 11 is a bulk crystal produced by the method shown in FIG. 1, and 12 is a hollow crystal substrate obtained by slicing the bulk crystal. The thickness of the slicing was set to 016 to 1.5 circles so that it could be easily handled in the process of epitaxial growth on it as a substrate and in the device fabrication process. In addition, the electrical characteristics of the crystal sliced into a wafer shape with an n-type ohmic tl[+ were investigated, but the resistance was high and no t current flowed.

The third and final step is a step of epitaxially growing an n-type crystal using the n-type wafer as a substrate.

Referring to FIG. 4, a heat sink 26 similar to that shown in FIG. 1 is housed and fixed at the bottom of a crystal growth ampoule 21 made of quartz. The substrate crystal 12 is placed on the heat sink 26!
The substrate crystal 12 is fixed by a substrate stopper 25-. The substrate crystal 12 is a wafer-shaped n-type, Z n Se crystal sliced in the second step.

The substrate stopper 25 is a ring made of quartz or the like similar to the growth ampoule 21. On the substrate crystal 12,
A solution 22 using Zn as a solvent is accommodated. Solution 2
A suitable amount of a group III or group VII element is added as an n-type impurity to the material. Furthermore, Zn, which is a growth raw material,
5e crystal 23 is accommodated. Since the diameter of the source crystal 23 is larger than the inner diameter of the substrate stopper 25, the source crystal 23 is held by the substrate stopper 25. After the substrate crystal 12, substrate stopper 25, solvent 22, and source crystal 23 are placed in the growth ampoule 21, the inside of the ampoule 21 is evacuated and sealed. An ampoule having such a configuration is placed in an electric furnace having a temperature gradient (for example, ΔT=5 to 15° C./■) as shown on the right side of FIG. do. Then, the source crystal 23 in the upper high-temperature part is dissolved and diffused in the solvent 22 until it reaches saturation solubility.

The melted source crystal 23 is transported through a temperature gradient and epitaxially grows on the upper surface of the substrate crystal 12.

FIG. 5 is a cross-sectional view of the n-type II-VI group compound semiconductor doped with group II or Vn group elements with a two-layer structure manufactured through the above steps. In FIG. 9, 31 is S6-T.
The substrate layer of the ■-■ group compound crystal is grown using the e-solvent growth method (Fig. 1), and 32 is the substrate layer grown using the Zn solvent growth method (Fig. 4).
Fig. 3 shows the layer of crystals of the ■-■ group compound according to Figure).

FIG. 6 is a graph showing the electrical characteristics (impurity density) of each layer of the n-type ■-■ group compound semiconductor having a two-layer structure manufactured in this way. Although the electrical properties vary depending on the growth conditions of each layer (amount of impurities added, growth temperature Tg, growth rate, etc.), one typical example is shown in the figure below. The growth conditions of No. 31 are growth temperature T
g = 950°C, temperature gradient ΔT = 10°C/■, iodine (■), a group II element, was used as an added impurity, and the concentration in the solution was 0.3 nolX. The conditions for growing the crystal layer 32 by the growth method using a Zn solvent (FIG. 4) are the growth temperature T g
= 1025°C, temperature gradient ΔT = 7.5°C/'■, iodine I, a group II element, was used as the added impurity, and the concentration in the solution was 1 x 10-41 olX.

As can be seen from FIG. 6, the crystal layer 32 is S e -
It can be seen that the crystal layer 31 grown in Te solvent has a low resistance, forming a two-layer low resistance n-type structure.

Although the present invention has been described above in accordance with the embodiments, it will be obvious to those skilled in the art that the present invention is not limited to these examples.6 For example, it will be obvious to those skilled in the art that various changes, improvements, combinations, etc.

[Effects of the Invention] As explained above, according to the present invention, the first step
A bulk crystal of a ■-■ intergroup compound semiconductor containing 2n as a constituent element is obtained by the temperature difference method using an e-Te solvent, and in the second step this is sliced to form a substrate, and in the third step Since the epitaxial growth is performed on this substrate by a temperature difference method using a Zn solvent, in the second step the substrate crystal, which had a high resistance, undergoes heat treatment in the Zn solvent. This improves the misalignment and lowers the resistance of the substrate itself. Furthermore, since the substrate is grown using a temperature difference method using a 5e-Te/g medium, bulk crystals can be obtained efficiently. These two layers are both the same ■−■
Since it is an intergroup compound semiconductor, there are no lattice defects due to lattice mismatch or alteration due to diffusion from the substrate to the growth layer.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the crystal growth apparatus used in the first step in an example of the present invention and a graph showing the temperature gradient. FIG. A graph showing the dependence of speed on temperature gradient; FIG. 3 is a cross-sectional view of the crystal for explaining the second step in the above example; FIG. 4 is a graph showing the crystal used in the third step in the above example. Growth outfit! A cross-sectional view of FIG. 5 shows a two-layer semiconductor device manufactured by the manufacturing method of the above example! FIG. 6 is a graph showing the electrical characteristics of a two-layer semi-conductor device manufactured by the manufacturing method of the above embodiment, and FIG. 7 is a cross-sectional view of a semiconductor device manufactured by the conventional manufacturing method. It is a diagram. In the figure, 1.21 2.22 3.23 Ampoule for growth Crystal heat sink for Zn solvent source Bulk crystal substrate Crystal substrate stopper Patent applicant Stanley Electric Co., Ltd. Representative Patent attorney Keisho Takahashi Figure 2 Figure 1 Temperature T

Claims (1)

[Claims] (1), in a solvent containing Te and Se in an arbitrary ratio.
a first step of adding a group III or group VII element, placing a source crystal in a high temperature part, and depositing a group II-VI compound semiconductor having Zn as a constituent element in a low temperature part by a temperature difference method; A second step is to form the II-VI group compound semiconductor crystal produced in the first step into a flat plate shape, and add an appropriate source crystal and a group III or VII element to the Zn solvent, and then process the above step by a temperature difference method. and a third step of epitaxially growing a II-VI group compound semiconductor having Zn as a constituent element on the flat crystal formed in step 2. .