JPH01168032A - Vapor phase growth equipment - Google Patents

Abstract

PURPOSE:To obtain a thick film crystal having no abnormal crystal, no powder like crystal and preferable crystallinity even when a thick film polycrystalline material is grown by supplying substantially in parallel material gases having components of small diffusion coefficients along the face of a substrate, and feeding gases having components of large diffusion coefficients perpendicularly to the face of the substrate. CONSTITUTION:A substrate is so provided as to form four faces in a reaction vessel 21. Zn nozzles 23a, 23b are provided near the ends of substrates 24a, 24b. An H2Se introduction tube 22 is provided at the center of the vessel 21, and H2Se nozzles 22a, 22b are so formed as to feed material gases toward the face of the substrate perpendicularly to the faces of the substrates 24a, 24b. Accordingly, the H2Se gas having large diffusion coefficient flows substantially perpendicular to the face of the substrate. The gas containing Zn vapor of small diffusion coefficient flow from the nozzles 23a, 23b substantially in parallel along the faces of the substrates 24a, 24b. These gases are chemically reacted on the substrates 24a, 24b, thereby forming ZnSe crystals 25a, 25b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for growing crystals on a substrate by chemical vapor deposition from two or more source gases.

[Prior Art] For example, Zn5e and ZnS are grown as crystals grown on a substrate by chemical vapor deposition from two or more raw material gases.
There are thick film polycrystalline materials used as infrared optical component materials such as. In this case, when using a component of an element in group (1) of the periodic table, such as Zn, the vapor of Zn is often contained in a carrier gas such as hydrogen or argon to form a raw material gas. Further, for elements in group (I) of the periodic table, such as Se and S, hydride gases thereof are often used as raw material gas. like this,
A raw material gas containing each component is introduced onto the substrate surface, and a chemical reaction is caused on the substrate surface to deposit a desired compound on the substrate.

FIG. 2 is a schematic sectional view showing an example of a conventional device.

The apparatus shown in FIG. 2 is a horizontal vapor phase growth apparatus. A substrate 4 is placed inside the reaction vessel 1 . Board 4
are provided on the four sides surrounding the inside, but the second
In the figure, the substrates on the back side of the drawing and the front side of the drawing are omitted. Near the substrate 4, an H2Se nozzle 2 and a Zn
A nozzle 3 is provided. A heater 6 is provided around the reaction vessel 1 to heat the substrate.

H2Se gas is supplied onto the substrate 4 from the H2Se nozzle 2, and gas containing Zn vapor in a carrier gas is supplied onto the substrate 4 from the Zn nozzle 3. A chemical reaction occurs on the substrate 4, and Zn5e crystals 5 are deposited on the substrate 4.

The reaction raw material gas is discharged in the direction indicated by the thick arrow. Note that thin arrows indicate the flow of H2Se gas, and medium-thick arrows indicate the flow of gas containing Zn vapor.

FIG. 3 is a schematic cross-sectional view showing another example of the conventional apparatus, and shows a vertical crystal growth apparatus. A substrate 14 is installed in the reaction container 11 so as to form a four-sided structure surrounding the interior. In FIG. 3, the substrates on the back side of the drawing and on the front side of the drawing are omitted. An H2Se nozzle 12 and a Zn nozzle 13 are provided near the substrate 14. A heater 16 is provided around the reaction vessel 11 to heat the substrate 14. H emitted from H2Se nozzle 12
The 2Se gas and the source gas containing Zn vapor in the carrier gas discharged from the Zn nozzle 13 undergo a chemical reaction on the substrate 14, and Zn5e crystal 15 is grown on the substrate 14.

[Problems to be Solved by the Invention] However, in such a conventional device, as shown in FIG.
may precipitate and cause blockage at the tip. When the Zn nozzle 3 is clogged in this way, the state of the flow of the raw material gas supplied onto the substrate changes, and abnormal growth occurs in the crystals deposited on the substrate, or powdery fine crystals are taken in. As a result, a problem arises in that the crystal properties as a material for infrared optical components are significantly deteriorated.

The cylindrical Zn5e polycrystal at the tip of the Zn nozzle, which causes such problems, is thought to be due to the large difference in diffusion coefficient between Zn vapor gas and H2Se present in the carrier gas.

In particular, polycrystalline materials with a thickness of 10 mm or more are often manufactured as materials for infrared optical components, and the manufacturing time requires a long time, for example, 100 hours or more, so that such blockage of the Zn nozzle tip is likely to occur. Even if a complete blockage state is not reached, it is not preferable for the flow state of the raw material gas to change over time in terms of obtaining uniform crystals.

Furthermore, in the conventional apparatus, in order to obtain a large-area crystal with a uniform thickness, the substrate length is required to be extremely long compared to the opening length of the substrate. This is also because the thickness of the crystal is affected by the position of the nozzle for the source gas.

Therefore, an object of the present invention is to provide a crystal that can obtain thick film crystals with good crystallinity without abnormal crystals or powdery crystals even when growing thick film polycrystalline materials such as Zn5e and ZnS. Our goal is to provide growth equipment.

[Means for Solving the Problems] The vapor phase growth apparatus of the present invention introduces two or more raw material gases whose contained components have different diffusion coefficients onto a substrate in a reaction vessel through separate nozzles, and performs chemical vapor deposition. An apparatus for growing crystals on a substrate by a phase deposition method, in which a nozzle for a source gas having a component with a small diffusion coefficient is provided so as to flow the source gas almost parallel to the substrate surface, A nozzle for a source gas having a component is provided to flow the source gas toward the substrate surface in a direction substantially perpendicular to the substrate surface.

[Operation] According to the vapor phase growth apparatus of the present invention, the source gas having a component with a small diffusion coefficient flows relatively close to the substrate surface along the substrate surface. Further, the source gas having a component with a large diffusion coefficient flows from a position relatively far away from the substrate surface gradually approaching the substrate surface. The distance between the nozzle for the source gas with a component with a small diffusion coefficient and the nozzle for the source gas with a component with a large diffusion coefficient is greater than the distance between conventional nozzles, so crystals are formed at the tip of the nozzle. Precipitates less easily and does not cause blockages. Therefore, even if the crystal is grown for a long time, the flow of the raw material gas can be stabilized, and there will be no abnormal growth or precipitation of fine grain crystals in the crystal deposited on the substrate, resulting in a highly uniform thick film. Crystals can be obtained.

[Implementation] FIG. 1 is a schematic cross-sectional view showing an embodiment of the present invention, and shows an example in which the present invention is applied to a vertical vapor phase growth apparatus. Inside the reaction vessel 2, substrates are provided so as to form four surfaces. In FIG. 1, the substrates on the back side and the front side of the drawing are not shown, but they are constructed in the same way.

A Zn nozzle 23a is provided near the end of the substrate 24a. The Zn nozzle 23a is provided so that the raw material gas flows in a direction substantially parallel to the substrate surface of the substrate 24a. Similarly, a Zn nozzle 23b is provided near the end of the substrate 24b.

An H2Se introduction tube 22 is provided in the center of the reaction vessel 21, and its tip extends to the other end of the substrates 24a and 24b. Substrate 24a of this H2Se introduction tube 22
A large number of H2Se nozzles 22a are formed on the side. Similarly, on the substrate 24b side, a large number of H2Se nozzles 2
2b is formed.

An exhaust port 27 is formed at the tip of the reaction vessel 21 to exhaust the raw material gas inside the reaction vessel 2. Exhaust air is forcibly exhausted by a rotary pump. Reaction container 2
] A heater 26 for heating the substrate is provided around the board.

The H2Se nozzles 22a and 22b each have a substrate 24a.
, 24b so that the raw material gas flows toward the substrate surfaces in a direction substantially perpendicular to the substrate surfaces. Therefore, H2Se gas, which is a component with a large diffusion coefficient, flows in a direction substantially perpendicular to the substrate surface. Gas containing Zn vapor, which is a raw material gas having a component with a small diffusion coefficient, flows from Zn nozzles 23a and 23b to substrates 24a and 24.
It flows approximately parallel to the substrate surface of b. These gases chemically react on the substrates 24a and 24b, and the Zn5e crystal 2
5a and 25b are formed.

Using the apparatus of this example, the substrate temperature was 800'C1Zn.
Gas introductionff15 S LM, H2S e introductionffi
A 2nSe crystal was grown under conditions of a pressure of 20 Torr in a 5sLM1 reaction vessel. As Zn gas, Zn
A gas carried by hydrogen gas from a melting furnace was used. As a result, it was confirmed that continuous production for 200 hours or more was possible with the apparatus of this example.

In addition, the substrate length is 50 crn, and the substrate opening area is 900 cm2.
(30 cm on each side) was used for crystal growth. As a result, a Zn5e crystal with a thickness of 30 mm could be obtained over almost the entire surface of the substrate. Further, the thickness distribution over the entire surface of the substrate was within ±5% with respect to a thickness of 30 mm. Furthermore, the abnormal growth and formation of fine powder crystals, which are frequently observed in conventional apparatuses, did not occur at all, and it was possible to obtain highly uniform crystals with flat crystal surfaces.

[Effects of the Invention] As explained above, according to the vapor phase growth apparatus of the present invention, when growing a thick film polycrystalline material such as Zn5e or ZnS, it is possible to achieve good crystallinity without abnormal crystals or powdery crystals. thick film crystals can be obtained.

Furthermore, since nozzle clogging is less likely to occur, source gas can be stably supplied onto the substrate for a long period of time, and crystals with uniform thickness can be obtained. Furthermore, since it is easy to obtain crystals with a uniform thickness, it is easy to deposit the crystals on a large area substrate.

Further, unlike conventional devices, deposition can be performed on a large-area substrate without using a very long substrate in the direction in which the raw material gas flows, making it possible to downsize the entire device.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing one embodiment of the present invention. FIG. 2 is a schematic sectional view showing an example of a conventional device. FIG. 3 is a schematic sectional view showing another example of the conventional device. FIG. 4 is a side view showing a closed state of the source gas nozzle. In the figure, 21 is a reaction vessel, 22 is an H2Se introduction pipe,
22a, 22b are H2Se nozzles, 23a, 23b are Z
n nozzle, 24a, 24b are substrates, 25a, 25b are Z
n5e crystal, 26 a heater, and 27 an exhaust port. Figure 1 =

Claims (1)

[Claims] (1) In a vapor phase growth apparatus in which two or more source gases with different diffusion coefficients of contained components are guided onto a substrate in a reaction vessel from separate nozzles, and crystals are grown on the substrate by chemical vapor deposition. The nozzle for the raw material gas having a component with a small diffusion coefficient is provided to flow the raw material gas in a direction substantially parallel to the substrate surface, and the nozzle for the raw material gas having a component with a large diffusion coefficient is provided to flow the raw material gas in a direction substantially parallel to the substrate surface. A vapor phase growth apparatus that is installed to allow a vapor to flow toward a substrate surface in a direction substantially perpendicular to the substrate surface.