JPS6314488A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To prevent crystal defects at the interfaces between a semiconductor buried layer and other layers, by utilizing a crystal growing solution having solid phases therein and growing crystals under conditions that temperatures are distributed within the solution such that the solution has the highest temperature in its region contacted with the substrate when the semiconductor buried layer is formed on the structure of a semiconductor element having steps. CONSTITUTION:In order to grow crystals, arrangement within a core tube 8 is made such that a substrate 11 on which the crystals are to be grown is present on the side of the lower tube wall and a growing solution 12 is present on the side of the center of the tube. Temperatures in the growing selution 12 held by a solution holder 10 are distributed such that the region contacted with the surface of the substrate 11 has the highest temperature. When the growing process is started under these growing conditions, the crystal growing solution 12 once melts the surface of the substrate 11 to an extremely small depth before the growth of crystals starts. Therefore, any defects on the surface of the substrate 11 caused by exposing it to a high temperature before starting the growth can be removed automatically. Thus, crystal defects at the interface of a buried layer can be prevented and, as a result, deterioration of element characteristics can be obviated.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and more specifically, in a method for manufacturing a semiconductor device in which a buried semiconductor layer is grown as a crystal on a structure having a one-step difference. The present invention relates to an improved manufacturing method for reducing defects formed near the interface of the growth surface during growth.

[Conventional technology]

As an example of a conventional semiconductor device having this type of embedded structure, here we will introduce the Applied Physics
Applied Physics Letter
r) Mao1. FIG. 3 shows a schematic configuration of a buried laser diode (BH-LD) shown in In4 337-339.

That is, in the conventional configuration shown in FIG. 3, the symbol l is n.
”-1np substrate, 2 is n-IMP cladding layer, 3 is p-
INFN layer, 4 rnGaAsP active layer, 5 p
+-InGaAsP=+ 7 tact layers, 6 is n-1nP
The buried layer 7 is a p-InP buried layer, and 14 is a damaged portion occurring between the p-InP buried layer 7 and each layer interface.

However, in the case of this conventional configuration, the n''-1np substrate 1
By applying a forward voltage between the P'' and InGaAsP contact layers 5, carriers are injected into the InGaAsP active layer 4, and the ?+-INP cladding layer 2 and
Electrons and holes are confined within the InGaAsP active layer 4 due to the difference in refractive index and band gap with the p-IMP cladding layer 3, and the n-1nP buried layer 8. A resonator should be formed in a cleavage or the like so that the p-TnP buried layer 7 confines the electrons and holes in the lateral direction, and the electrons and holes are radiatively recombined and the light propagates in the vertical direction as shown in FIG. For example, laser oscillation will occur when the current exceeds a certain value.

In the case of this type of semiconductor laser device, n
-1nP buried layer 6. Since the p-1nP buried layer 7 is crystal-grown on the surface of the substrate with steps formed, the surface is damaged by being left at a high temperature before the start of growth, and the p-1nP buried layer 7 is particularly susceptible to p-I
Since crystal defects in the nP buried layer 7 and damaged portions 14 at the interfaces of each layer adversely affect device characteristics, sufficient care must be taken to protect the substrate surface before buried growth.

[Problem that the invention seeks to solve]

In this way, in the conventional semiconductor laser device,
The surface of the substrate with one step formed during buried growth is
Since the crystal is damaged by being left at a high temperature before the growth starts, crystal defects occur near the interface between the step part of the substrate and the buried layer, which has the disadvantage of deteriorating the device characteristics, and this should be avoided. For example, conventionally,
There is a method of bringing an unsaturated solution into contact with the substrate immediately before crystal growth to dissolve the surface, but in this case, it is difficult to control the amount dissolved per surface, and after dissolution, a part of the solution may reach the substrate surface. There were problems such as remaining particles mixed into the buried layer growth solution, making it impossible to control the composition of the buried layer.

This invention was made in order to solve these conventional problems, and its purpose is to eliminate damage to the substrate surface caused by leaving it at high temperatures before growing a semiconductor buried layer. In addition to preventing crystal defects from occurring between the interfaces of each layer, the composition of the buried layer itself can be controlled with sufficient reproducibility. It is an object of the present invention to provide a method for manufacturing this type of semiconductor device.

[Means for solving problems]

In order to achieve the above object, a method for manufacturing a semiconductor device according to the present invention uses a solution in which a solid phase exists as a solution for growing semiconductor crystals on a step structure, and the temperature distribution in the solution is Crystal growth is performed under conditions where the temperature is highest at the part that contacts the growth substrate.

[For production]

Therefore, in the case of the method of this invention, the semiconductor crystal growth solution is applied after the growth starts, and once the surface of the substrate to be grown is extremely thinly dissolved, the damaged parts of the substrate surface caused by being left at high temperatures before the start of growth are removed. 1, this, and 1 that are grown as crystals after being removed
This makes it possible to prevent crystal defects from occurring at the buried layer interface.

〔Example〕

Hereinafter, one embodiment of the method for manufacturing a semiconductor device according to the present invention will be described in detail with reference to FIGS. 1 and 2.

Fig. 1 is a cross-sectional view schematically showing the general structure of a buried laser diode to which this embodiment method is applied, and Fig. 2 shows the general structure of a growth port in a growth reactor according to the above method and its growth state. FIG.

In the structure of the embodiment shown in FIG. 1, the same reference numerals as in the conventional structure shown in FIG. 3 indicate the same or equivalent parts, and in FIG. A slide port 10 serves as a holder for a substrate 11 to be grown, and 10 is a solution holder on this slide port 8;
2 is a semiconductor crystal growth solution held in this solution holder 10, and 13 is a solid phase in the solution 12.

During crystal growth, as shown in FIG. 2, a growth target substrate 11. By arranging the growth solution 12 so that it exists on the center side of the furnace, the temperature distribution within the growth solution 12 held in the solution holder 10 can be adjusted to the part that contacts the surface of the growth substrate 11. Therefore, under these growth conditions, after the start of growth, the crystal growth solution 12 reaches the highest temperature.
Once the surface of the substrate 11 to be grown is melted in an extremely thin area, the desired crystal growth is performed, so that the damaged portion 14 on the surface of the substrate 11 caused by being left at high temperatures before the start of growth is automatically removed. Therefore, it is possible to prevent crystal defects from occurring at the buried layer interface, and as a result, deterioration of device characteristics can be avoided.

Look at the growth solution mentioned above! In order to make the temperature distribution of 2 so that the temperature is highest at the part that contacts the surface of the growth substrate 11, it is necessary to use the above structure; This can also be achieved by arranging a heater or the like. Furthermore, the solid phase 13 in the semiconductor crystal growth solution 12 is prepared in advance so that the supersaturation degree of the crystal growth solution 12 is 2.
This can be achieved by using a solution whose temperature exceeds 0°C or by adding a sufficiently large amount of compound crystals containing the components of the crystal growth solution 12.

In addition, in the above-mentioned example method, the case of the device configuration in which the semiconductor buried layer is grown as a crystal on the n''-1np substrate is described, but it can be similarly applied to the case where the crystal is grown on the p''-1np substrate. In the method of the embodiment, the case of InGaAsP active layer 5-based semiconductor material was described, but the same applies to other semiconductor materials. Although the case of a semiconductor laser device in which crystal layers are grown has been described, it goes without saying that the present invention can be similarly applied to other laser devices having a buried structure, LED devices, light receiving devices, electronic devices, etc.

〔Effect of the invention〕

As described in detail above, when using the method of the present invention, when crystal-growing a semiconductor buried layer on a structure having steps of a semiconductor element, as a solution for crystal growth on the step structure,
We used a solution in which a solid phase exists, and the crystal growth was performed under conditions where the temperature distribution in the solution was the highest at the part in contact with the growth substrate, so under the growth conditions set in this way, After the start of growth, the crystal growth solution first dissolves the surface of the substrate to be grown in a very thin area, and then the target semiconductor crystal grows. Damaged parts of the substrate surface caused by high-temperature storage are automatically removed, thereby preventing the occurrence of crystal defects at the buried layer interface, and as a result, deterioration of device characteristics can be avoided. Also, unlike the method of dissolving the substrate surface with an unsaturated solution immediately before crystal growth,
It has excellent features such as the ability to easily control the composition of the buried layer and, therefore, the ability to grow crystals of the buried layer itself with sufficient reproducibility.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing the general structure of a buried laser diode to which an embodiment of the semiconductor device manufacturing method according to the present invention is applied, and FIG. FIG. 3 is a cross-sectional view schematically showing the general structure and its growth state, and FIG. 3 is a cross-sectional view schematically showing the general structure of a conventional buried laser diode. 1...n"-Inp board, 2...n-INPN
Chikudo layer, 3...p-IMP cladding layer, 4...
・InGaAsP active layer 5'' ・・P+-InGaA
sP=+ 7 tact layers, 8-...-n-1nP buried layers, ? ... p-1nP buried layer, 8 ... reactor core tube,
3...Slide port, 10...Solution holder, 11...Growth substrate, 12...Semiconductor crystal growth solution, 13...Solid phase in the semiconductor crystal growth solution . Agent Masuo Oiwa +3. Written amendment to the procedure for Figure 3, which has been in decline for a long time (voluntary), Showa 6 yen, November 19, 2, Title of the invention: Method for manufacturing semiconductor devices 3, Representative of the person making the amendment: Moriya Shiki 4 , Agent 5, Subject of amendment (1) Column 6 of detailed explanation of the invention in the specification, Contents of amendment (1) Change rn”-TnpJ on page 2, line 7 and line 13 of the specification to “
Correct as n+-InPJ. (2) r n-INPJ on page 2, lines 7 and 16 of the same book as rn
Correct it to -1nPJ. (3) r p-INPJ on page 2, lines 8 and 16 of the same book.
Correct it to -1nPJ. (4) rn”-1 npJ on page 7, line 10 of the same book
Correct with nPJ. (5) r p”-TnpJ in the same book, page 7, line 12, rp”-
Correct with InPJ. (8) rn'-1npJ on page 9, line 11 of the same book as rn''-I
Correct with nlJ. (7) r n-INPJ on page 9, line 11 of the same book as rn-1n
Correct with PJ. (8) r p-INPJ on page 9, line 12 of the same book as r p-1
Correct with nPJ. (9) Figures 1 and 3 of the drawings will be corrected as shown in the attached sheet. Figure 3 above

Claims (1)

[Claims] (1) When crystal-growing a semiconductor buried layer on a structure with steps of a semiconductor element, a solution in which a solid phase exists is used as the solution for crystal growth on the step structure, and the temperature distribution in the solution is controlled. A method for manufacturing a semiconductor device, characterized in that crystal growth is performed under conditions such that the highest temperature is reached at the part that contacts the growth target substrate.