JPS63137436A - Liquid phase epitaxial growing system - Google Patents

Abstract

PURPOSE:To prevent abnormal yielding of a crystal at the peripheral parts of a substrate when slanted type liquid phase epitaxial growing is performed, by providing crystal thin films composed of the same material as that of the substrate at the periphery of a substrate holder beforehand. CONSTITUTION:A substrate supporting tool 13 composed of cylindrical quartz, in which a recess part 12 is provided by cutting at the central part, is provided so as to contact with a heat resisting quartz tube 11 having a bottom. An epitaxially growing substrate 15 composed of CdTe is mounted on a substrate holder 14 in the recess part 12 along the central axis of the supporting tool 13 so that the substrate is contacted with facing surfaces 16A and 16B with the recess part 12 in-between. The holder 14 is formed by using substrate composed of sapphire or the like. Crystal layers comprising the same material as that of the epitaxial growing substrate 15 are deposited on the peripheral parts 14A on both sides of the holder, which are not contacted with the supporting tool 13, by a sputtering method and the like beforehand. A epitaxially growing melt 18 composed of Hg, Cd and Te is contained at the lower part of the holder 14. The melt 18 is fused and the device is rotated in the direction B. The substrate is contacted with the melt and the temperature is decrased. Thus an epitaxial layer is formed. At this time abnormal epitaxial growing is yielded on the CdTe crystal layers 17 at the peripheries of the holder 14. The epitaxial layer having the uniform thickness along the entire surface is obtained on the substrate 15.

Description

[Detailed Description of the Invention] [Summary] A tilted liquid phase epitaxial growth apparatus, in which the periphery of a substrate holder, which is held by a substrate support while supporting a substrate, is made of the same material as that of the substrate crystal. By forming the crystal in a thin layer in advance using a sputtering method or the like, this thin crystal layer prevents abnormal growth of the epitaxial crystal at the peripheral edge of the substrate during epitaxial growth. A liquid phase epitaxial growth device that forms an epitaxial layer.

[Industrial application field]

The present invention relates to a tilted liquid phase epitaxial growth apparatus, and more particularly to a liquid phase epitaxial growth apparatus that prevents abnormal growth.

Mercury-cadmium-tellurium (Hg+-1CdxTe) crystals with a narrow energy band gap are used in infrared detection elements and photoelectric conversion elements such as infrared laser elements.

When such Hg1-x Cdw Te crystals are epitaxially grown on a cadmium telluride (CdTe) substrate, since mercury is a material that evaporates easily, a sealed tube is used to prevent the evaporation of mercury and the molten Hg+-3Cd
A tilted liquid phase epitaxial growth apparatus, which forms an epitaxial layer on a substrate by bringing an XTe melt into contact with the substrate, is often used because the apparatus is simple and the growth rate of the epitaxial layer is fast.

In such an epitaxial growth method, it is necessary to ensure that the epitaxial crystal layer formed on the substrate has a uniform thickness.

[Conventional technology]

A conventional liquid phase epitaxial growth apparatus like this will be explained with reference to the explanatory diagram of FIG.

As shown in the figure, inside a heat-resistant bottomed quartz tube 1, there is a substrate support made of cylindrical quartz that is inscribed in the quartz tube 1 and has a recess 2 cut in the center thereof. 3 is installed.

In the recess 2 of the substrate support 3, an epitaxial growth substrate 5 made of CdTe placed on a substrate holder 4 made of a quartz plate is placed along the central axis of the substrate support 3 and facing oppositely across the recess 2. It is installed on surfaces 68 and 6B.

Furthermore, an epitaxial growth melt 7 made of materials such as mercury, cadmium, and tellurium is housed in the lower part of the substrate holder 4.

After evacuating the inside of the quartz tube 1 in this state, a support rod 8 for rotating the device is installed at the other end of the quartz tube 1 and sealed.

Next, as shown in FIG. 4 (al), this device is inserted into a quartz furnace core tube (not shown), and the furnace core tube is heated to melt the melt 7 housed in the quartz tube 1.

Next, the device is rotated 180 degrees in the direction of arrow A, and the fourth
The board 5 installed in the board holder 4 as shown in Figure (b)
Bringing the surface of the tube into contact with the molten epitaxial growth melt 7, lowering the temperature of the heating furnace that heats the furnace core tube,
Epitaxial crystals were formed on the substrate by lowering the temperature of the melt.

[Problem that the invention seeks to solve]

However, in such a conventional device, as shown in FIG. 5, there is a phenomenon in which epitaxial crystals grow abnormally on the peripheral edges 5A on both sides of the substrate 5 that are not in contact with the support 3, and in this way, the abnormal growth occurs. If a substrate on which such crystals are formed is used as a material for forming an infrared sensing element, there is a problem that the characteristics of the element are poor and the yield of element formation is reduced.

The reason why crystals grow abnormally in this peripheral area is considered to be that the amount of melt supplied to the peripheral area of the substrate is larger than that in the central area.

The present invention solves the above-mentioned problems, and aims to provide a liquid phase epitaxial growth apparatus that prevents abnormal growth of crystals on the peripheral edges on both sides of a substrate that are not in contact with a substrate support.

[Means for solving problems]

The liquid phase epitaxial growth apparatus of the present invention includes a substrate support that is inscribed in a heat-resistant sealed tube and holds a substrate for epitaxial growth and a substrate holder that supports the substrate, and a melt for epitaxial growth accommodated in the lower part of the substrate holder. The structure is characterized in that a thin layer of crystal made of the same material as the substrate crystal is provided in advance on the peripheral edge of the substrate holder.

[Effect]

In the liquid phase epitaxial growth apparatus of the present invention, thin crystal layers are formed in advance from the same material as the substrate on the peripheral edges of both sides of the substrate holder that are not in contact with the substrate support.

By growing crystals that are formed by abnormal growth on the periphery on both sides of the substrate in this thin crystal layer region, the crystal layer is prevented from abnormally growing on the periphery on both sides of the substrate. Make it.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an explanatory diagram of the liquid phase epitaxial growth apparatus of the present invention.

As shown in the figure, inside the heat-resistant bottomed quartz tube 11,
A substrate support 13 made of cylindrical quartz is installed so as to be inscribed in the quartz tube 11 and has a recess 12 cut in the center thereof.

In the recess 12 of the substrate support 13, an epitaxial growth substrate 15 made of CdTe placed on the substrate holder 14 of the present invention is placed along the central axis of the substrate support 13.
Moreover, it is installed so as to be in contact with the surfaces 16A and 16B that face each other with the recess 12 in between.

The structure of this substrate holder 14 is shown in the plan view of FIG.

As shown in the figure, the substrate holder 14 of the present invention is formed using a sapphire or gallium arsenide (GaAs) substrate, and has peripheral edges 1 on both sides that are not in contact with the substrate support tool 3.
A crystal layer of CdTe, which is the same material as the epitaxial formation substrate 15, has been deposited on the substrate 4A in advance by sputtering or the like.

Further, the lower part of this substrate holder 14 contains mercury, cadmium,
An epitaxial growth melt 18 made of tellurium is housed therein.

By inserting such an epitaxial growth apparatus of the present invention into a furnace core tube (not shown) and heating the furnace core tube, melt 1
The melt 18 is melted on the substrate 15 by rotating the growth apparatus 180 degrees in the direction of the arrow B as described above.
to form an epitaxial layer on the substrate by lowering the temperature of the heating furnace.

In this way, the CdTe crystal layer 17 previously formed on the peripheral edge portions 14A on both sides of the substrate holder 14 described above.
Abnormal epitaxial growth begins to occur on the
Abnormal crystal growth does not occur at the peripheral edges on both sides of the substrate 15.

Therefore, an epitaxial layer with a uniform thickness is formed on the entire surface of the substrate 15, and when an element is formed using this substrate 15, an element with uniform characteristics can be obtained, which improves the yield of the element. An effect that also connects occurs.

〔Effect of the invention〕

As described above, according to the liquid phase epitaxial growth apparatus of the present invention, the thickness of the epitaxial crystal layer formed on the substrate becomes uniform, and such an epitaxial crystal can be used to form an element such as an infrared sensing element. This has the effect of providing a high-quality infrared sensing element with stable characteristics.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of the device of the present invention, FIG. 2 is a plan view showing the main parts of the device of the present invention, FIG. 3 is an explanatory diagram showing the structure of the conventional device, and FIG. ) and FIG. 4(b) are explanatory diagrams of the operation of the conventional apparatus, and FIG. 5 is an explanatory diagram of an unfavorable state of a substrate formed by the conventional apparatus. In the figure, 11 is a quartz tube, 12 is a recess, 13 is a substrate support, 14 is a substrate holder, 15 is a substrate, 16A, 16B are the surfaces of the substrate support, 17 is a CdTe crystal layer, 18 is a melt, B
Figure 1 shows the equipment lid for the main part of the equipment. J

Claims (1)

[Claims] A substrate holder (14) that is inscribed in the heat-resistant sealed tube (11) and supports an epitaxial growth substrate (15) and the substrate (15).
) and a substrate support (13) that holds the substrate holder (
In the structure consisting of an epitaxial growth melt (18) housed in the lower part of the substrate holder (14), the substrate (1
A liquid phase epitaxial growth apparatus characterized in that a crystal (17) made of the same material as in 5) is provided in a thin layer.