JPS60215593A - Method for growing single crystal film - Google Patents

Abstract

PURPOSE:To grow a single crystal film of a desired compound without using a single crystal substrate, by forming the film of the desired compound on a substrate other than a single crystal, covering the compound film with a substance having the lowest melting point and vapor pressure in component substances constituting the compound film, and heat-treating the covered film under specific conditions. CONSTITUTION:A flat glass, metal plate or ceramic plate, etc. is used as a substrate 1, and a compound film 2, e.g. InP or GaAs, is formed on the substrate 1. The compound film 2 is then covered with a film 3 of a component substance, e.g. In in InP or Ga in GaAs, having the lowest melting point and vapor pressure in component substances constituting the compound film 2, and the compound film 2 covered with the film 3 is heated at a temperature within a range including the melting point of the compound film 2, cooled and converted into a single crystal.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a single crystal film growing method for growing a single crystal film of a desired substance on a substrate, and particularly relates to a method for growing a single crystal film of a desired compound on a single crystal substrate. It was designed to allow the plants to grow without any problems.

(Prior Art) Conventionally, in order to grow a single crystal film on a substrate, a method of epitaxially growing a desired material on a single crystal substrate of the desired material has generally been used. Furthermore, recently, attempts have been made to perform pm Ogura 7 O epitaxy on the surface of the substrate. However, in the former method, not only is the single crystal wafer used as a substrate expensive, but the thickness of the single-crystal wafer is required to be as small as one pass, and moreover, expensive materials are required for the cutting allowance when cutting the crystal. There were economic and resource disadvantages such as wastage. Furthermore, the latter method has the drawback that the manufacturing cost and labor required to provide fine-pitch grooves on the substrate cannot be ignored.

(Objective) The object of the present invention is to eliminate the above-mentioned conventional drawbacks, and without using an expensive single-crystal substrate or special processing on the substrate, it is possible to solve the problem of conventional glass plates, metal plates, and ceramic plates. To provide a method for growing a single crystal film of a desired compound using a substrate made of any material, such as a substrate made of a plastic plate, or a plastic plate if temperature conditions permit. It is in.

(Summary of the Invention) That is, the method for growing a single crystal film of the present invention includes the steps of producing a desired compound film on a desired substrate other than a single crystal substrate;
A process of covering the compound film with a film of a component material having the lowest melting point and vapor pressure among the component materials constituting the compound film, and covering the compound film covered with the film at the melting point of the compound film. growing a single-crystal film of the desired compound without using a single-crystal substrate by single-crystallizing the desired compound film through a process of heating to a temperature within a range including and then cooling; It is characterized by:

(Example) The present invention will be described in detail below with reference to the drawings.

First, FIG. 1 shows the basic structure of a single crystal film manufactured by the method of the present invention. In the figure, 1 is a substrate, 2 is a compound film, and 3 is a coating made from one of the constituent substances of the compound film 2. More specifically, the compound film 2 is, for example, InP I Ga
As l engineering nsb, Garb, GaP*I
nAs, etc., or In, Ga, etc. as a base with At added, for example, GaAtAs t InAtA
Ternary or quaternary GaAtAsP such as s, InA
It is made of a compound semiconductor such as MUSP. For example, the compound film 2 is made of InP.
, InSb.

If InAs is better, use In, or if the compound film 2 is GaP, Garb, or GaAs.
Any of these is formed by a substance having the lowest melting point and vapor pressure among the constituent substances of the compound film 2, such as Ga. That is, In and Ga have respective (3) melting points of 157°C and 30°C, which are the lowest among the constituent substances of the above-mentioned compound group, and also have a vapor pressure of 10''.
The respective temperatures required to reach Torr are 952℃,
Both have a high temperature of 1093° C., and therefore have the lowest vapor pressure among the constituent substances of the above-mentioned compound group.

In the illustrated configuration, for example, a υInP film 2 is deposited to a thickness of about 3 μm on a glass substrate 1 with a thickness of about 1 am by molecular beam evaporation (ultra-high vacuum deposition), and an In film 3 of about 3 μm is deposited thereon. 18
It adheres to μm.

In practice, these thicknesses are not strict values, and the values shown here may be slightly increased or decreased.
As shown in the figure. In the figure, 4 is a heater for heating the substrate, and 5 is a substrate. Further, 6 is a crucible containing one vapor deposition source material of the compound, for example, indium In, 7 is the other vapor deposition source material,
For example, it is a crucible containing phosphorus P. Furthermore, 8 is a cooling shroud filled with liquid nitrogen, 9 is a vacuum chamber, and 10 is an exhaust port to an ultra-high vacuum pump, such as a cryo (4) pump, ion pump, etc.

FIG. 3 shows an example of the relationship between the temperature change of the substrate 5 and the elapsed time in a series of steps of compound film deposition, component substance film deposition, and single crystallization treatment using the above-mentioned deposition apparatus. First, while keeping the temperature of the substrate 5 at 270°C,
Molecular beam deposition, that is, ultra-high vacuum deposition, is performed on the substrate 5 from deposition source crucibles 6 and 7 containing 1ne of indium In and red phosphorus P, respectively. The degree of vacuum before vapor deposition is 5.5
X 10-' Torr, and the degree of vacuum during vapor deposition was approximately 1.5 X 10-' Torr due to the vapor pressure of phosphorus P. Note that indium In was evaporated at 700 to 800°C, and phosphorus P was evaporated at about 300°C. In this way, the thickness is 3μ.
After performing the synthetic deposition of InP compound film 2 of m,
The temperature of crucible 7 is lowered to stop the evaporation of phosphorus P, and crucible 6
Continue to evaporate only indium from
A μm thick In film 3 is laminated on the compound film 2. The formation of the laminated layers 2 and 3 is performed while the temperature of the substrate 5 is maintained at 270° C. in the period b-c in the time chart shown in FIG. Subsequently, the temperature of the substrate 5 is temporarily changed to the area c.
After decreasing sequentially in -f, in interval f-h,
After rapidly raising the temperature of the substrate 5 to about 1000°C,
Natural heat radiation cooling allows the temperature to drop to room temperature. Since the melting point of the compound InP is 1060°C, the compound InP recrystallizes in the process of rapidly increasing the temperature to 1000°C.
As the crystal grains enlarge, the (111) plane parallel to the substrate 50 plane becomes dominant in all crystal grains. During recrystallization, if there are very few impurities in the pre-deposited InP compound, there will be very few impurities that form grain boundaries, and the grain boundaries will either be almost absent or only slightly present. Therefore, phosphorus P, which has a high vapor pressure and exists in the nP compound,
The phosphorus P tries to dissociate and escape, but since the surface is covered with an In film, some of the phosphorus P that can escape dissolves into the indium In. Then, as mentioned above, after the substrate temperature reaches the recrystallization temperature of about 1000°C, it is immediately lowered to room temperature by natural heat radiation. Zone melting occurs perpendicularly to the surface.During attachment and detachment, zone melting is performed perpendicularly to the film, thus making the InP compound film 2 more resistant. What should be noted here is that if the recrystallization temperature is 1000℃
If held for a long time, the In-nP compound 2 and the In coating 3
and are mutually diffused and eroded, making it impossible to form a desired film. As mentioned above, if the temperature is naturally cooled immediately after reaching the recrystallization temperature of 1000°C, in the process of temperature reduction, the underlying material, which is in a state of (,111) plane preferential orientation close to that of a single crystal or a single crystal, will be The InP compound film 2 is brought into contact with the melt of indium In into which phosphorus P has been dissolved as described above, and liquid phase epitaxial growth is performed, and crystal film purification is performed by zone melting. Conceivable.

In short, in the process of single-crystal film growth according to the present invention, InP is in a single-crystal or near-single-crystal state due to recrystallization, and has (iii) (7) plane preferential orientation parallel to the substrate surface. It is considered that the compound film serves as a seed single crystal film and liquid phase epitaxial growth of the InP compound is performed on the seed single crystal film, thereby promoting improvement in single crystallization. Furthermore, if the heater is installed only on one side of the substrate as described above, a temperature gradient perpendicular to the film surface will be generated through the cooling process to room temperature during recrystallization and subsequent liquid phase epitaxial growth, and zone melting will occur at the same time. An example of a reflected X-ray photograph of an InP single crystal film is shown in Figure 2. In creating the reflected X-ray Laue photograph shown in the figure, the irradiated X-ray beam is passed through a collimator with a diameter of 1 meter, so the irradiation area is equivalent to a circle with a diameter of 1 m, but the entire surface of the membrane with a #11 an angle is A spot pattern as shown in the figure was displayed over the entire area. As can be seen from the photograph, the film produced by the method of the present invention is a single crystal film having a (iii) plane parallel to the substrate, as can be seen from the 3-fold symmetrical arrangement of the spots. Note that 3(8)-e-f is the case where the InP compound film 2 and the In coating 3 are suddenly 1
- It is also possible to raise the substrate temperature up to 1000 degrees Celsius.

In addition, when the component element distribution in the stacking direction in an example of manufacturing a single crystal film by the method of the present invention was confirmed by line analysis using an There is a layer of indium In, and the indium I
The amount of n gradually increases until finally a surface layer with a thickness of about 1
It had a structure in which 8 μm thick In films were laminated. Furthermore, the lattice constant of the produced film measured by the bond method is cubic and 5.
It was measured as 889 A, A, S, T.

M, the lattice constant of the nP single crystal shown on the card 5,
It showed good agreement with 8691.

The In coating on the InP single crystal film produced as described above can be left as is and used depending on the configuration of the electronic device manufactured using the single crystal film, or the remaining part can be left as is. can also be removed by etching. In addition, in order to remove this In film, for example, the process n.
In order to prevent the P single crystal film 2 from dissolving and deteriorating and to keep the In film in a molten state, the substrate temperature is raised to about 200° C. and the In film is removed mechanically, or by sputter etching. For appropriate j, such as removing only the In film 3, InP can be epitaxially grown on the single crystal film in an undoped manner,
Alternatively, by epitaxially growing InP without doping with impurities, a second top film is formed on the InP single crystal according to the purpose of use, and a single crystal film of good quality is manufactured. Electronic devices, optical devices, etc. using crystal films can be manufactured.

In removing the In film 3 mentioned above, the exposed InP single crystal film 2 is used as a seed single crystal substrate (11). During the subsequent InP epitaxial growth, the surface of the seed single crystal substrate is exposed to carbon C contained in the air. In order to avoid contamination with oxygen and oxygen, it is extremely important to subsequently remove the In film 3 in an ultra-high vacuum without breaking the vacuum, and to subsequently grow epitaxially thereon. In other words, in conventional epitaxial growth, the surface of a single-crystal bulk substrate is polished, washed and etched, then placed in an ultra-high vacuum molecular beam epitaxy device, raised to a desired substrate temperature, and irradiated with As molecules or two molecules. Wash the surface O-? However, according to the present invention, a clean crystal surface can be obtained from the single crystal film stage instead of the substrate crystal, and it is extremely possible to consistently manufacture devices while maintaining crystal cleanliness. This has great advantages.

Further, as for the compound film 2, an example in which the film is formed using a three-temperature method has been described, but flash evaporation, Si' (12) As is clear from the above explanation, the present invention can also be used.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the basic structure of a single crystal film manufactured by the method of the present invention, FIG. 2 is a cross-sectional view showing the schematic structure of a molecular beam evaporation apparatus by the method of the present invention, and FIG. 3 is a cross-sectional view showing the basic structure of a single crystal film manufactured by the method of the present invention. FIG. 4 is a transfer diagram of a reflected X-ray Laue photograph of a single crystal film produced by the method of the present invention. 1... Substrate 2... Compound film 3... Coating 4... Substrate heating heater 5... Substrate 6.7... Evaporation source and crucible 8... Cooling shroud 9...・ Vacuum chamber 10... Vacuum exhaust port. 3 Figure 1 Publication date: GO-215593 (5) Figure 0 1 2 3 4 5 6 7 8 9 IQ progress bet fa diagram

Claims (1)

[Claims] (1) A process of forming a desired compound film on a desired substrate other than a single crystal substrate, and forming a film of a component material having the lowest melting point and vapor pressure among the component materials constituting the compound film. The desired compound film is single crystallized through a process of covering the film and a process of heating the compound film covered by the film to a temperature within a range including the melting point of the compound film and then cooling it. A method for growing a single crystal film, which is characterized in that, in particular, a single crystal film of a desired compound is grown without using a single crystal substrate. (2. In the growth method described in claim 1,
A method for growing a single crystal film, characterized in that schizone melting is performed by applying a temperature gradient in a direction perpendicular to the surface of the substrate.