JPH06227892A - Production of single crystal thin film - Google Patents

Abstract

PURPOSE:To obtain a single crystal thin film at a low cost by enabling a substrate material therefor to be selected regardless of the material of the aimed single crystal thin film. CONSTITUTION:Firstly, a single crystal thin sheet 2 is stuck as seed crystal to a thin film substrate 1. The aimed single crystal thin film 4 is successively and continuously grown on the substrate 1 beginning with the single crystal thin sheet 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a single crystal thin film used as a material for various electronic devices, light emitting devices, light receiving devices and the like.

[0002]

2. Description of the Related Art Conventionally, various single crystal thin films have been used as materials for various electronic devices, light emitting devices or light receiving devices. In the production of this type of single crystal thin film, it is general to form the single crystal thin film on a single crystal substrate having the same crystal symmetry as the material forming the single crystal thin film.

Among the above thin film single crystals, the most widely used materials at present are light emitting diodes (hereinafter, LED) and laser diodes (hereinafter, LD).
III-V group compound semiconductors used in. For example, infrared LEDs used in remote control devices for televisions
Is a III-V compound semiconductor, gallium arsenide (Ga).
As) GaAs with a small amount of impurities added on a single crystal substrate
It is obtained by forming a single crystal thin film. Also,
An LD used in a small laser printer or the like is manufactured by forming an indium-gallium-aluminum-phosphorus (InGaAlP) single crystal thin film on the GaAs single crystal substrate.

Of the above, G on a GaAs single crystal substrate
The molecular beam thin film growth method (Molecul
ar Beam Epitaxy: hereinafter abbreviated as MBE method. ) Is used as an example to describe more specifically.

FIG. 4 is a schematic configuration diagram showing an apparatus for producing a single crystal thin film by the MBE method. Inside the vacuum chamber 41, a substrate holder 42 configured to rotate in a direction indicated by an arrow A is arranged. On one surface of the substrate holder 42, Ga for forming a single crystal thin film thereon is formed.
The As (100) single crystal substrate 43 is fixed.

On the other hand, so as to face the single crystal substrate 43,
Further, crucibles 44 and 45 are arranged near the side wall on the opposite side of the vacuum chamber 41 so that the opening faces the inside of the chamber 41. In the crucibles 44 and 45,
Contains arsenic and gallium. Crucible 44,45
900 due to the heaters 46 and 47 arranged around
It is configured to be heated to a temperature of about ° C. By this heating, arsenic and gallium are molecularized and a molecular beam is blown toward the single crystal substrate 43.

Note that shutters 48a and 48b are arranged in front of the crucibles 44 and 45. Shutter 4
8a and 48b are arranged to adjust the traveling direction of the molecular beam, and by adjusting the opening / closing degree of the shutters 48a and 48b, GaAs is formed on the single crystal substrate 43.
A single crystal thin film is formed. That is, a molecular beam of Ga and As that has been molecularized reaches the rotating single crystal substrate 43, and a GaAs single crystal is grown on the single crystal substrate 43 to form a GaAs single crystal thin film.

Besides the GaAs single crystal thin film,
For example, gadolinium gallium garnet (Gd ₃
Ga ₅ O ₁₂ , hereinafter abbreviated as GGG. ) Yttrium / iron / garnet (Y ₃ Fe ₅ O ₁₂ , below, on a single crystal substrate,
Abbreviated as YIG. ) A method for producing a single crystal thin film, a method for forming a silicon (Si) single crystal thin film on a sapphire single crystal (Si on Saphire, hereinafter abbreviated as SOS), a GaAs single crystal thin film on a silicon single crystal substrate. A method of manufacturing (GaAs on Si), a method of manufacturing a gallium nitride single crystal thin film (GaN) on a sapphire substrate, and the like are performed. Further, as a specific manufacturing method of the single crystal thin film, various methods are used in addition to the MBE method described above.

[0009]

However, what is common to the conventional methods for producing a single crystal thin film is that a single crystal substrate must be used as a substrate for growing a single crystal thin film. In addition, the single crystal substrate to be used may not be composed of any single crystal, and if physical properties such as constituent elements, crystal symmetry, lattice constant and coefficient of thermal expansion do not meet, A good single crystal thin film cannot be formed on it. On the contrary, it can be said that a good-quality thin film single crystal cannot be obtained when a good-quality single crystal substrate does not exist.

At present, very few single crystals can be used as a single crystal substrate for producing the above single crystal thin film.
i, GaAs, indium phosphide (InP), gallium phosphide (GaP), GGG, sapphire, strontium titanate (SrTiO ₃ , hereinafter abbreviated as ST), magnesium oxide (MgO) and the like. Therefore, the single crystal thin film that can be formed on the single crystal substrate is also very limited.

Further, since the production of the single crystal substrate used for producing the single crystal thin film as described above requires special equipment and technique, the cost of the single crystal substrate is high, which is inevitable. In addition, the price of the single crystal thin film formed on the single crystal substrate is inevitably high.

The object of the present invention is to solve the above-mentioned conventional drawbacks, and not only a single crystal substrate but also a substrate made of various materials can be used to form a single crystal thin film, and thus an inexpensive single crystal. It is to provide a method for producing a single crystal thin film, which can provide a thin film.

[0013]

In the method for producing a single crystal thin film of the present invention, a thin film support having a single crystal thin plate smaller than the thin film support and functioning as a seed crystal is prepared. And the starting point of the single crystal thin plate,
And a step of sequentially forming a single crystal thin film on the thin film support so as to be continuous with the single crystal thin plate.

In the method for producing a single crystal thin film of the present invention, a thin film support on which a single crystal thin plate as a seed crystal is fixed is first prepared. Then, starting from this single crystal thin plate, the single crystal thin films are sequentially formed so as to be continuous with the single crystal thin plate. The single crystal thin film forming process itself may be performed by any known method such as MBE, chemical vapor deposition (CVD), metal organic chemical vapor deposition (MOCVD), liquid phase epitaxy (LPE). Can be used.

However, in the present invention, since the single crystal thin plate acts as a seed crystal, the material can be selected regardless of the material of the thin film single crystal, as will be apparent from the examples described later. it can. Examples of the thin film support material that can be used include glass, quartz, metals, and the like, and it is also possible to use a conventionally used single crystal substrate.

[0016]

According to the present invention, a single crystal thin plate smaller than the thin film support is fixed as a seed crystal on the thin film support, and single crystal thin films are sequentially formed starting from the single crystal thin plate. Therefore, a thin film support made of a material selected from a wide range of materials such as glass can be used without considering the crystallinity of the target single crystal thin film. Therefore, conventionally, the types of single-crystal thin films that can be produced were limited due to restrictions from the single-crystal substrate, whereas the present invention produces a wider range of single-crystal thin films than the conventional method. can do.

In addition, by devising the shapes of the thin film support and the single crystal thin plate, it is possible to easily provide various types of single crystal thin films.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the present invention will be described with reference to FIG. In the method for producing a single crystal thin film of the present invention, the single crystal thin plate 2 processed into, for example, an elongated strip shape on the thin film support 1.
Prepare the one to which is fixed. Then, the single crystal thin film material 3 is used so that the single crystal thin plate 2 acts as a seed crystal.
Are sequentially supplied to the side of the single crystal thin plate 2 as schematically shown by an arrow B in the drawing, and a single crystal thin film 4 (shown by hatching with hatching) is grown so as to be continuous with the single crystal thin plate 2. . To increase the area of the single crystal thin film 4, the thin film support 1
1 may be moved in the direction of arrow C in FIG. 1, that is, in the direction orthogonal to the length direction of the single crystal thin plate 2. Alternatively, the thin film single crystal raw material 3 may be moved in the direction opposite to the arrow C direction in the figure. Alternatively, both of them may be moved as described above.

As described above, the single crystal thin film 4 is grown on the thin film support 1 so as to be continuous with the single crystal thin plate 2, and a single crystal thin film having a desired size can be obtained. in this case,
As the thin film support 1, various materials such as glass and quartz can be used regardless of the kind and material of the single crystal thin film 4 to be obtained. For the step itself of supplying the single crystal thin film material 3 so as to be continuous with the single crystal thin plate 2 to form the single crystal thin film 4, a conventionally known thin film forming method such as the MBE method can be used.

Next, the present invention will be clarified by explaining more concrete examples. Ga on the GaAs substrate
The case where an As single crystal thin film is manufactured using the MBE method will be described as an example.

An MBE device shown in FIG. 2 is prepared. This M
The BE device has a configuration similar to that of the device shown in FIG. 6 described in the section of the prior art. The difference is that the substrate holder 42 is configured to be rotatable in the apparatus shown in FIG. 6, but the substrate holder 12 is configured to be movable in parallel in the direction of arrow D in the apparatus used in this embodiment. ing. Further, in this embodiment, the substrate holder 12 is
A shutter 13 is arranged in front of. The shutter 13 has a slit extending in the direction of the paper surface-paper spine in the drawing, and the molecular beam reaches the substrate holder 12 side through the slit.

Since the other points are configured in the same manner as the apparatus shown in FIG.
The description thereof will be omitted by giving the corresponding reference numerals. In the device shown in FIG. 2, a glass substrate 14 is attached to the front surface of the substrate holder 12. On the front surface of the glass substrate 14, an elongated G is formed along the upper edge thereof.
An aAs single crystal thin plate 15 is attached.

First, the inside of the vacuum chamber 41 is heated to heat the glass substrate 14 having a clean surface to a temperature of 500.degree. At this time, the inside of the vacuum chamber 41 is about 10 ^-10 T
Evacuate to about orr. On the other hand, the crucible 44,
45 is heated by heaters 46 and 47 to heat gallium and arsenic inside to a temperature of 900 ° C., respectively. As a result, molybdenum and arsenic are molecularized, and the molecular beam is blown toward the substrate holder 12 side.

The molecular beam can be adjusted by shutters 48a and 48b placed immediately before the crucible,
Thereby, the GaAs thin film single crystal is formed so as to be continuous with the single crystal thin plate 15 on the glass substrate 14.

On the other hand, a shutter 13 is provided in front of the glass substrate 14, and the molecular beam reaches the glass substrate 14 through the slit 13a of the shutter 13 as shown in FIG. Has been done. Therefore,
The molecular beam E passing through the slit 13a reaches the position where the single crystal thin plate 15 as a seed crystal is connected, and by moving the substrate holder 12 upward, the GaAs single crystal is connected to the single crystal thin plate 15. The crystal thin film 16 can be sequentially formed.

According to a concrete experiment, when the GaAs single crystal thin film 16 was grown as described above, the obtained crystal had a thickness of 2.0 ± 0.1 μm over the entire surface. Controlled by a two-crystal X-ray diffractometer (first
As for the crystal, a very good single crystal thin film with a half width of 18 seconds was obtained from the rocking curve measurement by Ge (400).

Further, the glass substrate 14 is replaced with a substrate made of copper, and a p-type single crystal thin film and an n-type single crystal thin film are grown so as to be laminated to form a pn junction, and light is emitted as an LED. Infrared emission was observed, and LED
It was confirmed that it can work as.

In the above embodiments, the production of the GaAs single crystal thin film has been described, but the present invention can be applied to the production of a thin film single crystal made of any other material. Further, as the manufacturing method, not only the above-mentioned MBE method but also all other thin film single crystal manufacturing methods can be applied.

In the example shown in FIG. 1, the length of the single crystal thin plate as a seed crystal is the same as the width of the thin film support, that is, the single crystal thin plate is formed so as to reach the entire width of the thin film support. In the present invention, the single crystal thin plate as the seed crystal may be smaller than the width of the thin film support. For example, as shown in FIG. 4, the single crystal thin plate 2 as a seed crystal having a length shorter than the width of the glass substrate 21 along the center of one edge 21a of the glass substrate 21 as a thin film support.
When 2 is attached, guides 23a and 23b that are slanted from both ends of the single crystal thin plate 22 to the side edges 21b and 21c of the glass substrate 21 may be attached as illustrated. In this case, since the guides 23a and 23b are attached, when the single crystal thin films are successively grown so as to be continuous with the single crystal thin plate 22, the single crystal is sequentially grown in the hatched area X shown in the figure. A thin film is formed.
That is, by the action of the guides 23a and 23b, a single crystal thin film having a width finally reaching the entire width of the glass substrate 21 is formed.

Further, in the structure shown in FIG. 4, the guides 23a and 23b may be omitted. In that case, the glass substrate is cut and removed at the portion where the guides 23a and 23b are attached, and the glass substrate 21 is removed. By fixing the single crystal thin plate 22 having a width equal to that of the one end edge 21a which is shortened, a single crystal thin film finally reaching the entire width of the glass substrate 21 can be manufactured in the same manner.

Further, in each of the embodiments described above, the single crystal thin film is formed on one surface of the flat plate-shaped thin film support, but in the present invention, as shown in FIG. 5, for example, a cylindrical thin film support is formed. It is also possible to attach the elongated single crystal thin plates 32 reaching both end faces to the outer peripheral side surface of the body 31 and manufacture the single crystal thin film so as to be continuous with the single crystal thin plates 32. Thus, according to the present invention, on thin film supports of various shapes,
Since a good quality single crystal thin film can be formed, a good quality single crystal thin film can be formed not only on a flat plate or a cylinder but also on the surface of an object having a complicated shape.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining the principle of the present invention.

FIG. 2 is a schematic configuration diagram showing an apparatus for manufacturing a single crystal thin film in one embodiment of the present invention.

FIG. 3 is a side view for explaining a step of growing a single crystal thin film in the apparatus shown in FIG.

FIG. 4 is a perspective view for explaining a process of manufacturing a wide single crystal thin film on a flat plate-shaped thin film support using a small single crystal thin plate.

FIG. 5 is a perspective view for explaining an example of manufacturing a single crystal thin film on a cylindrical thin film support.

FIG. 6 is a schematic configuration diagram for explaining a conventional MBE method for manufacturing a single crystal thin film.

[Explanation of symbols]

 1 ... Thin film support 2 ... Single crystal thin plate 3 ... Single crystal material 4 ... Single crystal thin plate

Claims (1)

[Claims] 1. A step of preparing a thin film support, on which a single crystal thin plate smaller than the thin film support and functioning as a seed crystal is fixed, the single crystal thin plate being a starting point. A step of sequentially forming a single crystal thin film on the thin film support so as to be connected to a thin plate, the method for producing a single crystal thin film.