JPS6258642A - Liquid-phase epitaxial growth equipment - Google Patents

Abstract

PURPOSE:To product uniform crystals on the surface of a substrate by a method wherein a substrate arrangement region and a melt material region are separated in the interior of an ampul and a melt material is so contrived as to flow to the substrate arrangement region passing through a fine tube. CONSTITUTION:There is a fine tube forming block 12 made of quartz in the interior of a growth ampul 11 formed of quartz and there are a substrate 13 and a melt material region 15 to house a melt material 14 in the upper and lower parts on both sides. Then, a fine tube 16 having its diameter changing along the long direction is provided between the region where the substrate is arranged and the melt material region 15, and when a liquid-phase growth is executed, a growth material in the growth ampul 11 is faced to the lower side and is heated to 500 degrees by an electric furnace, and HgCdTe which is the growth material is melted and liquefied. Then, the ampul 11 is made to rotate 180 deg., the melt material 14 is faced to the upper side and melt solution is made to flow into the region where the substrate is arranged passing through the fine tube.

Description

[Detailed Description of the Invention] [M Required] The present invention is a closed-tube liquid phase epitaxial growth apparatus, in which a melt material melted at high temperature is passed from a high place to a low place through a thin tube with a varying diameter toward a substrate. By pouring it into the
The melt material liquid is stirred to uniformly grow crystals on the substrate.

[Industrial Field of Application] The present invention relates to a liquid phase epitaxial growth apparatus, and particularly to a structure for homogenizing a molten melt material.

Recently, liquid phase epitaxial growth has been widely adopted as an epitaxial growth method, and is used, for example, to generate crystals of mercury, cadmium, and tellurium (HgCdTe) used in infrared elements.

However, in conventional closed-tube liquid-phase epitaxial growth equipment that is carried out in an ampoule, the growth substrate is simply immersed in the melt material. There is a disadvantage that the composition is non-uniform, and there is a demand for improvement of this problem.

[Prior Art] FIGS. 3(a) to 3(b) show a side sectional view and a front sectional view, respectively, of a conventional liquid phase epitaxial crystal growth apparatus.

As an example, a case will be described in which Hg Cd Te is grown on a cadmium and tellurium (CdTe) substrate.

Inside the quartz ampoule l, a substrate 2 is supported from both sides by quartz melt holders 3, and initially Hg Cd T
The growth material in e is sealed in vacuum, but when performing liquid phase epitaxial growth, the growth ampoule is inserted into an electric furnace with the substrate facing up and the growth material facing down, and the temperature of the ampoule is set to approximately When heated to 500℃, Hg Cd
T e is melted and becomes a liquid melt material 5 .

Next, the growth ampoule is rotated and the substrate is immersed in the liquid H g Cd Te melt material, and the immersion is performed at a predetermined temperature and for a predetermined time to grow liquid phase epitaxial crystals on the substrate surface. will be held.

After the required crystal growth is completed, the growth ampoule is returned to its initial state of 180 degrees anti-axis inversion, and epitaxial growth is completed.

In such conventional methods, epitaxial growth is performed while the melt material in the ampoule is HgCdTe, and the melt material is stationary because the specific gravity of Hg is about twice that of Cd or Te. , mercury precipitates on the bottom surface, and the growth rate is particularly high at the beginning of the epitaxial growth period, and it is important that each component of HgCdTe at that point is a uniform melt solution, but conventional methods do not necessarily produce a uniform melt solution. The drawback is that it was not.

[Problems to be Solved by the Invention] A problem with conventional liquid phase epitaxial growth is that the melt material becomes non-uniform due to differences in specific gravity, and uniform crystals cannot be grown.

[Means for Solving the Problems] The present invention proposes a liquid phase epitaxial growth apparatus for solving the above problems. The melt material region is connected with a thin tube whose diameter changes in the length direction, and the melt material liquid passes through the thin tube and flows into the substrate placement area, thereby creating a turbulent flow of the melt material liquid. As a result, the melt materials with different specific gravity compositions become uniform as they are injected into the substrate area.
This enables liquid phase epitaxial growth with uniform crystals.

[Function] In a melt material such as HgCdTe, the uniformity deteriorates due to the size of the precipitate due to the difference in specific gravity. As a countermeasure, the melt solution is passed through a thin tube to create a turbulent flow.
By imparting a stirring effect to the melt material, the melt material is homogenized and liquid phase epitaxial growth is performed. For example, by using a thin tube with a variable diameter, even more effective stirring can be achieved. As a result, excellent crystal growth with a uniform composition can be achieved.

[Example 1] FIG. 1 is a side sectional view showing an example of the liquid phase epitaxial growth apparatus of the present invention.

Inside the growth ampoule 11 made of quartz, there is a thin tube forming block 12 made of quartz, and at the upper and lower portions of both sides there are melt material regions 15 in which a substrate 13 and a melt material 14 are stored, and the substrate is arranged. A thin tube 16 whose diameter varies in the longitudinal direction is provided between the region where the melt material is formed and the melt material region.

FIG. 2 shows a front sectional view of the liquid phase epitaxial growth apparatus of the present invention, corresponding to the reference numerals in FIG. 1.

The cross section of the thin tube 16 has a large diameter at the portion where it joins the substrate placement area and the melt material area, and is thinner at the center thereof, but the ratio may be approximately 2:1.

When performing liquid phase growth, the growth material in the growth ampoule is placed on the lower side, and the temperature is raised to 500°C in an electric furnace to melt the growth material, HgCdTe, into a liquid. As shown, the ampoule is rotated 180 degrees, with the melt material facing upward, and the melt solution flows through the capillary into the area where the substrate is located.

FIG. 1 shows the state in which the melt material 14 is flowing in the capillary tube 16, and the melt material flowing in the capillary tube indicated by the arrow flows in a turbulent flow within the capillary tube whose diameter changes.

When the melt material has sufficiently flowed out of the melt material region, the substrate region is filled with the melt material, the substrate is completely immersed in the melt material, and crystal growth is performed by performing treatment at a predetermined temperature and time.

As a result, the tart solution of HgCdTe, which was non-uniform due to the specific gravity of each component, was sufficiently stirred during the process of passing through the capillary and being injected onto the substrate area, and was almost completely dissolved. becomes a null 1-material of uniform composition.

During crystal growth, it is essentially possible that Hg, which has a high specific gravity, will precipitate downward over time. If you stir it thoroughly first,
Overall, the negative effects of Hg precipitation are less pronounced.

A substrate immersed in such a uniform melt material will grow extremely uniform crystals.

[Effects of the Invention] As described above in detail, by employing the liquid phase epitaxial growth apparatus of the present invention, uniform crystals are generated on the surface of the substrate, and an excellent semiconductor substrate can be provided. There is.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the liquid phase epitaxial growth apparatus of the present invention, FIG. 2 is a front view showing an embodiment of the liquid phase epitaxial growth apparatus of the present invention, and FIG. 3 is a conventional liquid phase epitaxial growth method. In the cross-sectional view showing an embodiment of the device, 11 is a quartz ampoule, 12 is a capillary forming block 13
14 indicates a substrate, 14 indicates a melt material region, I5 indicates a melt material region, and I6 indicates a thin tube. Banquet number one! ! I! Flute 2 diagram

Claims (1)

[Claims] In the ampoule (11) of the liquid phase epitaxial growth apparatus, a region where the substrate (13) is placed and a region where the melt material (14) is placed are separated, and the diameter between these regions changes in the length direction. tubule (1
6), so that the melt material (14) passes through the capillary (16) and flows into a region where the substrate is placed.