JPH0287619A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To stably obtain a thin epitaxial layer by a liquid epitaxial growth operation by a method wherein the lower part of a bath is formed to be a slit shape which is sufficiently narrower than a width of a substrate. CONSTITUTION:After an InP layer has been grown in a first bath 13, a substrate 12 is placed in a first standby position 14 under an InP substrate used to prevent a thermal deterioration of the surface. Then, a slider 11 is pulled again; the substrate 12 is passed under a second bath and a third bath 15, 16, and is shifted to a second standby position 17 under the InP substrate. While the substrate is passed under the baths 15, 16 whose lower part has been made narrow to be a slit shape, thin films of InGaAs and InGaAsP are grown individually. Then, the substrate 12 is shifted reversely to the first standby position 14 from the second standby position 17. While the substrate is passed under the baths 15, 16, thin films of InGaAs and InGaAsP are grown individually. When this operation is repeated a plurality of times, a multiple-quantum-well structure of InGaAs and InGaAsP can be formed by a liquid growth operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming extremely thin layers in liquid phase epitaxial growth.

[Conventional technology]

Conventionally, methods for forming long and extremely thin liquid-phase epitaxially grown films for semiconductor devices have been carried out by either minimizing the growth time or reducing the control speed by reducing the degree of supersaturation of the solution. .

[Problem to be solved by the invention]

In the conventional liquid phase epitaxial growth method described above, even if the growth time is to be kept as short as possible, the slide plate holding the growth substrate is mechanically moved safely and securely and stopped directly under the bathtub even if the growth time is short. Therefore, it was difficult to form a layer with a current of several hundred amperes or less. Furthermore, even if the growth substrate is simply passed through the bath without being stopped directly under the bath, there is a drawback that hundreds to several hundreds of layers will grow. On the other hand, if the supersaturation degree of the solution is set to a very small value, it is certainly possible to obtain a thin growth layer, but at the same time, meltback is likely to occur and the flatness of the interface between the substrate and the growth layer deteriorates. There is a drawback.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention involves forming an extremely thin epitaxial growth layer by making the width of the bathtub sufficiently narrow compared to the width of the substrate and moving the substrate at high speed under the narrow slit-shaped bathtub. It is characterized by

〔Example〕

Next, the present invention will be explained with reference to the drawings. 1 and 2 are cross-sectional views for explaining a first embodiment of the present invention. Here, I nG using a carbon boat
aAs Active Layer A method for forming a double heteroepitaxial layer including an active layer having an emission wavelength of 1.55 μm using an nP-based liquid phase epitaxial growth method will be described. Set the board 2 on the slider 1 and bathtubs 3, 4, 5.6
In and the required amounts of InP, GaAs, and InAs, respectively.
Put in. With the slider 1 in the position shown in Figure 1, these were held at 630°C for 1 hour, and incubated in each bath.
Sufficiently dissolve P, Ga, and As inside. Next, the temperature of the entire system is lowered at a rate of 0.5°C per minute. When the temperature has dropped to a predetermined temperature, the slider 1 is pulled to move the substrate 2 to the lower part of the first bath 3, and an InP layer is epitaxially grown for a predetermined period of time. Thereafter, the slider 1 is pulled again to move the substrate 2 to the lower part of the second bath 4, and the InGaAsP active layer is epitaxially grown for a predetermined period of time. Further, the slider 1 is pulled and the substrate 2 is moved to the lower part of the fourth bath 6 to grow an InP layer.

When InP is grown on an active layer having an emission wavelength of 1.55 μm in this manner, a melt-back phenomenon occurs in which the active layer is dissolved in a solution. Therefore, after growing the active layer, a thin layer having a composition intermediate between that of the InGaAs active layer and InP is grown on the active layer to prevent the active layer from melting back. This layer is called the anti-meltback layer and is 1.5
It is an essential layer in D H epitaxial growth with a 5 μm active layer.

Since this anti-meltback layer prevents meltback of the active layer, the growth solution must be highly supersaturated, and the layer sandwiched between the active layer and the cladding layer must be as thin as possible. is more desirable in terms of characteristics. The solution for growing this anti-meltback layer is in the bath 5.
It's in.

The bottom of this bathtub has a narrow slit shape, and the substrate 2
The time during which the substrate 2 is in contact with the solution when it passes through the lower part of the bath M5 is extremely short. As a result, even if the supersaturation degree of the solution is kept high enough to prevent the active layer from melting back, the effective growth time is extremely short.
0 anti-meltback layer was obtained, and InP on top of it was obtained.
The layer can be easily grown and a high quality HD epitaxial layer can be obtained.

FIG. 3 is a sectional view for explaining a second embodiment of the present invention. The substrate 12 initially placed on the slider 11 is placed in a first standby position 14 under the InP substrate for preventing thermal deterioration of the surface after an InP layer is grown in a first bath 13. Next, pull the slider 11 again to move the substrate 12 to the second position. Third
The substrate is moved to the second standby position 17 under the InP substrate. At this time, thin films of InGaAs and InGaAsP grow as they pass under the bathtubs 15 and 16, each of which has a narrow slit-like bottom. Next, the substrate 12 is moved reversely from the second standby position 17 to the first standby position 14. At this time bathtub 16.1
InGaAsP and I, respectively, when passing under 5
A thin film of nGaAs is grown. By repeating these actions multiple times, a multiple quantum well structure of InGaAs and InGaAsP can be formed by liquid phase growth. Furthermore, the slider 11 is pulled out and placed on top of this by the next bathtub 18.
By growing a P cladding layer, a DH epitaxial layer having a multiple quantum well structure can be obtained.

〔Effect of the invention〕

As explained above, the present invention has the effect that a thin epitaxial layer can be stably obtained by liquid phase epitaxial growth by forming the lower part of the bath into a slit shape that is sufficiently narrower than the width of the substrate.

[Brief explanation of drawings]

1 and 2 are cross-sectional views for explaining a first embodiment of the present invention, and FIG. 3 is a cross-sectional view for explaining a second embodiment of the present invention. 1.11...Slider, 2,12...Substrate, 3゜13...First bathtub, 4.15...Second bathtub, 5
゜6...Third bathtub, 6. 8... Fourth bathtub,... First standby position, 7... Second standby position.

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device, which comprises forming an extremely thin epitaxially grown film by passing a substrate at high speed under a slit-shaped bathtub that is sufficiently narrow compared to the width of the substrate.