JPS61291489A - Method of heteroepitaxial crystal growth of semiconductor - Google Patents

Abstract

PURPOSE:To grow and to form a high-quality single crystal semiconductor layer on a different substrate in a short time, by growing and forming a semiconductor layer on the different substrate under conditions of growth temperature and growth speed to show binary single crystal growth mode. CONSTITUTION:A first layer single crystal semiconductor layer is grown and formed on different single crystal substrates under conditions of growth temperature and growth speed to show a binary single crystal growth mode in such a way that lattice unconformity between the different single crystal substrate and the first layer single crystal semiconductor layer is larger than critical thickness which can be relaxed by dislocation to occur newly in the first layer single crystal semiconductor layer. Then, a second layer single crystal semiconductor layer, which is of the same kind as that of the first layer single crystal semiconductor layer, is grown and formed on the first layer single crystal semiconductor layer under conditions of growth temperature and growth speed to show a binary single crystal growth mode. Mass productivity and economic efficiency can be raised by the above-mentioned crystal growth method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for growing semiconductor heteroepitaxial crystals.

Conventionally, as a method for forming a semiconductor layer on a heterogeneous substrate, a vapor phase epitaxy method, a vacuum evaporation method, a sputtering method, etc. have been used. Semiconductor layers formed on foreign substrates by these methods contain many electrically and optically active crystal defects such as dislocations due to differences in crystal structure and lattice constant from the substrate. Therefore, the characteristics of a device developed using this semiconductor layer are extremely inferior to those developed using a semiconductor layer formed on the same type of substrate. Therefore, in order to realize a semiconductor device with excellent characteristics using a semiconductor layer formed on a different type of substrate, it is essential to form a high-quality semiconductor layer.

Generally, it is known that the crystallinity of a semiconductor layer formed on a different substrate improves with the thickness. Attempts have been made to form semiconductor layers on heterogeneous substrates at high temperatures where growth rates can be expected. However, according to this method, the semiconductor layer exhibits a three-dimensional crystal growth pattern, and the resulting semiconductor layer has extremely poor surface smoothness, making it unsuitable for device formation. On the other hand, when forming a semiconductor layer on a heterogeneous substrate at low temperatures where a two-dimensional crystal growth pattern can be expected, it is easy to obtain a semiconductor layer with excellent surface smoothness, but it is difficult to obtain a sufficiently thick layer with few crystal defects. It takes a long time to form a semiconductor layer and is not a practical method.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a semiconductor heteroepitaxial crystal growth method that allows a high-quality single-crystal semiconductor layer to be grown on a heterogeneous substrate in a short time. It is in.

[Summary of the invention]

In order to achieve all of the above objectives, the present inventors have conducted various experiments and found that if a semiconductor layer is grown on a different type of substrate under conditions of growth temperature and growth rate that exhibit a two-dimensional single crystal growth pattern, A semiconductor layer with an extremely smooth surface can be obtained, and the crystallinity of the obtained semiconductor layer gradually improves with increasing film thickness, and the lattice mismatch with the foreign substrate is alleviated by newly generated dislocations. When the critical thickness to be obtained is about five times or more, the improvement effect by the crystalline film thickness becomes saturated. It has been discovered that if the layer is grown under conditions of growth temperature and growth rate exhibiting a two-dimensional crystal growth pattern, a high-quality semiconductor layer with an extremely smooth growth surface can be realized in a short period of time.

This discovery is based on the fact that when a first single-crystal semiconductor layer is grown on a heterogeneous single-crystal substrate at a growth temperature and growth rate that exhibits a two-dimensional single-crystal growth mode, the lattice mismatch with the heterogeneous single-crystal substrate a second layer having the same composition as the first single crystal semiconductor layer on the surface of the first single crystal semiconductor layer; The present invention proposes a method for growing a semiconductor heteroepitaxial crystal, which comprises a step of growing a single crystal semiconductor layer under growth temperature and growth rate conditions exhibiting a two-dimensional single crystal growth pattern.

[Embodiments of the invention]

Embodiments of the present invention will be described below, taking as an example a case where a darmanium semiconductor layer is grown and formed on a silicon substrate using a vacuum evaporation apparatus as a crystal growth apparatus. It should be noted that this embodiment is merely an illustration, and it goes without saying that the present invention can be applied to other crystal growth apparatuses and crystal growth using other materials without departing from the spirit of the present invention.

FIG. 1 shows a cross section of a dalmanium semiconductor layer formed on a silicon substrate with a plane orientation of [100]. 1 is a silicon substrate as an example of a heterogeneous single crystal substrate; 2 is a first layer as an example of a first layer single crystal semiconductor layer grown under conditions of growth temperature and growth rate exhibiting a two-dimensional single crystal growth pattern; The germanium layer 3 is a second-layer germanium layer as an example of a second-layer single-crystal semiconductor layer grown under conditions of growth temperature and growth rate exhibiting a two-dimensional single-crystal growth mode, and under the conditions described below. It was formed with. First, the silicon substrate 1 is cleaned and then loaded into the vacuum evaporation apparatus described above.

Next, the silicon substrate 1 is heat-treated in a temperature range of 800° C. to 900° C. under a high vacuum condition of 10 Torr or less to remove the natural oxide film formed on the surface of the silicon substrate 1. Next, a first germanium layer 2 is grown on the silicon substrate 1 by evaporating the dalmanium source using an electron beam evaporation source. At this time, the experiment was conducted while changing the temperature of the silicon substrate 1 in the range of 400° C. to 850° C. and the growth rate of germanium in the range of IX/sec to 100° C./sec. As a result, the temperature of the silicon substrate 1 is 5
When the growth rate is 5X or less per second at 50°C or lower, the dahmanium layer 2 exhibits a two-dimensional single-crystal growth mode, and a single-crystal germanium layer with an extremely smooth growth surface is obtained.
Furthermore, as a result of investigating the relationship between the crystallinity and film thickness of the obtained dalmanium layer 2 using X-ray diffraction, TEM, etc., it was found that the thickness of the dalmanium layer 2 is 100 OX, which is the critical thickness at which the mismatch can be relaxed by newly generated dislocations in the dalmanium layer 2
When the thickness becomes thicker than , the lattice constant of the dalmanium layer 2 approaches the intrinsic value of 5,658X, and the crystallinity gradually improves, and when it exceeds about 5 times the critical thickness, the improvement due to film thickness increases. It became clear that the effect was saturated. Therefore, the thickness of the first single crystal semiconductor layer formed on the heterogeneous single crystal substrate should be equal to or greater than the critical thickness determined by the lattice mismatch between the heterogeneous single crystal substrate and the first single crystal semiconductor layer. is desirable. Next, a second germanium layer 3 was grown on the surface of the first germanium layer 2, which had an extremely smooth growth plane, and the growth temperature was 800°C or less and the growth rate was 501°C/sec. Under the following conditions, the germanium layer 3 exhibited a two-dimensional single crystal growth pattern, and a single crystal germanium layer with an extremely smooth growth surface was obtained. Furthermore, when the crystallinity of the second germanium layer 3 thus obtained was evaluated, it was found that the quality was higher than that of the first germanium layer 2. From this, it has become clear that even when the second germanium layer 3 is grown under conditions of higher growth temperature and higher growth rate than the first germanium layer 2, high-quality crystallinity can be obtained. .

In the above examples, both the first germanium layer and the second germanium layer are grown using a vacuum evaporation device. For forming the germanium layer, it is also possible to use a CVD apparatus that can be expected to have a high growth rate and mass productivity.

In addition, in the above embodiments, the experimental results of the growth and formation of a germanium semiconductor layer on a silicon substrate were described as an example, but the growth and formation of a silicon darmanium mixed crystal semiconductor layer on a silicon substrate and the m-v of gallium arsenide, etc. An attempt was made to grow a group compound semiconductor layer, and the same effects as in the previous example were obtained.

〔Effect of the invention〕

As explained above, according to the semiconductor heteroepitaxial crystal growth method according to the present invention, it is possible to grow a high-quality semiconductor layer on a heterogeneous single crystal substrate in a short period of time. This brings about both sex and economy.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a cross section of a germanium semiconductor layer formed on a silicon substrate with a plane orientation of [100]. In the figure, 1 is a silicon substrate, 2 is a first layer of dalmanium grown on the surface of silicon, and 3 is a layer of 1K.
This is a second germanium layer grown on the surface of the germanium layer. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Claims] A first single-crystal semiconductor layer is grown on a heterogeneous single-crystal substrate at a growth temperature and growth rate that exhibits a two-dimensional single-crystal growth mode, and the lattice mismatch with the heterogeneous single-crystal substrate is relaxed by newly generated dislocations. a step of forming a second single crystal semiconductor layer of the same type as the first single crystal semiconductor layer on the surface of the first single crystal semiconductor layer in a two-dimensional single crystal structure; 1. A method for growing a semiconductor heteroepitaxial crystal, comprising a step of growing under conditions of a growth temperature and growth rate that exhibit a growth pattern.