JPS5815218A - Liquid phase epitaxial growth apparatus - Google Patents

Abstract

PURPOSE:To provide highly efficient liquid phase epitaxial growth of a single crystal thin film on a single crystal substrate by preventing a local decrease in temperature at the boundary surface of a solution by means of a crucible which is made movable between a heating and a pre-heating room. CONSTITUTION:A solution 1 at room temperature in a crucible 2 is initially heated to approx. 1,200 deg.C in a pre-heating room 10C. Before reaching a saturation temperature at which the temperature lowering operation is to be started towards a growing temperature, an agitator 19 is lowered to agitate the solution while lowering its temperature so as to keep the solution temperature even. After a specified growing temperature is reached, the agitator 19 is lifted up, a heat shielding plate 17 is extracted and the crucible 2 is moved to a heating room 10a for epitaxial growth through a crucible moving mechanism 22. When the crucible reaches the heating room 10a a crystal substrate 9 supported by a supporter 8 is submerged in the solution for the growth, then, after the growth, it is lifted up. The crucible 2 is returned to the pre-heating room 10C at the completion of the growth by means of the moving mechanism 22. This temperature cycle of up- keep-down is repeated.

Description

[Detailed Description of the Invention] The present invention is directed to a liquid phase epitaxial growth apparatus, which is capable of liquid phase epitaxial growth of high-quality crystalline films on single crystal substrates with high quality and high efficiency. It is.

Conventional liquid phase epitaxial growth equipment, such as I! A device having the structure shown in Figure 1 is employed. That is, in the figure, 1 is a melt consisting of a crystal component and 7 lux, 2 is a platinum crucible containing this melt 1, 3 is a heater arranged in a spiral shape, and 4 is the interior of the spiral heater 3. The cylindrical heat soaking tube %S, which accommodates the platinum crucible 2 and is arranged, is a rounded annular heat shielding plate that obtains the distribution of the melt at 10 points in the crucible 2, and 6 is a heat shielding plate that shields external cold air. An opening hole provided in the center of the outside air shielding plate 60 in the form of a disk, is a round support for immersing the crystal substrate 9 in the direction of the arrow to neutralize the melt and move it up and down once in the direction of the arrow. It is.

When crystal growth is performed using a liquid phase epitaxial growth apparatus configured in this way, a cycle of raising the melt 1, holding it at a high temperature, lowering the temperature, and growing the melt 1 is performed, and during the growth period, the melt 1
He held the temperature below the saturation temperature of the melt 1 and repeated the process of introducing the crystal substrate 9 into the melt 1, growing it, and pulling the crystal and plate 9 one or several times. usually appears.

However, if a local 1llWIL decrease occurs at the interface of the melt 1, for example at the surface of the melt 1 or at the contact surface with the crucible 2, during the temperature cycle described above, minute precipitates may form in the melt 1. It is known that crystal defects occur, hinder normal growth, and cause crystal defects.

Therefore, in the liquid phase epitaxial growth apparatus having the above configuration, heat dissipation from the opening hole 7 for penetrating the charging support 8 of the crystal substrate 9 is performed.
The first problem is that it is structurally difficult to prevent the temperature from dropping by 1 degree.
Along with this, Mud 2 had the disadvantage that the temperature raising/lowering cycle required about 10 times as much time as the growing period, reducing the overall working efficiency.

Therefore, the present invention provides a heating chamber for creating the necessary temperature distribution in the melt, a preheating chamber provided on one or both sides of this heating chamber, and a stirrer provided above this preheating chamber. A liquid phase epitaxial growth apparatus is configured by a heat shielding plate that is detachably installed at the boundary between the heating chamber and the preheating chamber, and a crucible moving mechanism for moving the crucible to both the heating chamber and the preheating chamber. By,
It is an object of the present invention to provide a liquid phase epitaxial growth apparatus that eliminates the above-mentioned conventional drawbacks and allows high-quality crystal growth experiments to be obtained with high efficiency. That is, in the present invention, in order to prevent the temperature drop on the melt surface, it is necessary to form an m1 atmosphere above the melt surface with a temperature of 91 degrees or more, and k to improve the melt temperature distribution is It is especially effective to stir the melt during the temperature-lowering cycle, and the trap that sets the cycle time is to alternately mix multiple melts! It is efficient to use

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a cross-section 1i showing an example of a liquid phase epitaxial boat building apparatus according to the present invention. In Figure 11, the same symbols as in Figure 1 represent the same elements, and their explanation will be omitted. In Figure 2, 10 is composed of a heat insulating box body 11 for producing the necessary degree distribution in the melt 1, and a heat insulating cylinder body 12 housing the spiral heater 3 and soaking tube 4. In this heating chamber 1110, the box body 11 is divided into three in the vertical direction, and an epitaxial growth heating chamber IQa and preheating chambers *10b and 10o are formed on both sides of the heating chamber IQa. 13°14, Is is each heating chamber 10m of this box body 11,
10b, 10° heater wound around the inner surface, 18,1
7. A heating chamber 10a for track growth and a preheating chamber 10b, 10a are partitioned from each other.
Insulating heat shield plate such as os, 18.11t'i preheating chamber Iob.

A stirrer is disposed above 10c so as to be able to rise, fall and rotate freely in the direction of the arrow, and 2' is a crucible placed in the preheating chamber lQb and containing a melt 1' equivalent to the melt 1. , 20.21 is equipped with a crucible 2.2', and serves as a growth heating chamber 10a and a preheating chamber 10b.

It is a plywood moving mechanism that moves the plywood and the 22.23Fi base plate 20.21 in the direction of the arrows in the direction of the arrow. Among the heaters 14 in 10, the upper heater 14a is a heater that heats the surface of the melt 1 in the crucible 2, and when the lower sO heater/14bti growth heating @10bO lower part 0112 is held,
Preheating 1! 10b* Heaters 13, 15 in 10a
Fi, this preheating 1! The lubricity placed and placed in 10b, 10a is 11 when giving the necessary IIrIIL distribution to the melt 1' of 2'.

Next, a liquid phase epitaxial growth apparatus 0I with the above configuration is used.
I will explain the 11th work. ? -O, crucibles 2 and 2'
Since cycles similar to Fi and li are repeated alternately, the operation of crucible 2 will be explained here. Melt 1 in crucible 2
First, the temperature is raised from room temperature to approximately 1200°C in the preheating chamber 10a.
After that, he homogenized for 5 to 40 hours and cultivated m1it.
Before reaching the saturation temperature where the temperature is lowered toward ', for example, around 50 degrees Celsius above the saturation temperature, the stirrer 19 is lowered and stirred in parallel with the temperature drop of the melt to make the melt temperature uniform. keep.

After reaching a predetermined growth temperature, the stirrer 19 is raised and the heat shield plate 1T is removed. , the crucible is moved to the growth heating chamber 10a via the base plate 20 by the crucible moving mechanism 22. In this case, it goes without saying that the temperature of the growth heating chamber 10aU melt 1 is set under conditions that do not cause folds. After the crucible 2 reaches the growth heating chamber 10aK, the crystal substrate 90 support 8 is lowered, immersed in the melt 1 and grown, and then raised. Then, the crucible 2 that has been grown is moved to the preheating chamber 10aKM by the moving mechanism 22.
L, Heat shield plate 17t - Insert and repeat the cycle of increasing temperature, maintaining high ugliness, and decreasing temperature. In this case, it is clear from the above description that the movement of the other crucible 2' is carried out at the same time as the beginning of the lifting cycle of the crucible 2.

According to the liquid phase epitaxial growth apparatus configured in this way, in the preheating chamber 10b or 10o, the entire circumference of the crucibles 2, 2' can be maintained at a temperature higher than the melt temperature, so that By stirring the melt by the stirring mechanisms 22 and 23, which can prevent local temperature drops,
The temperature distribution within the melt can be kept extremely uniform. In addition, the heat radiation from the upper opening when moving to the growth heating chamber IQa is offset by the heating by the heater 141L,
The melt temperature does not change. In addition, since the temperature separation due to convection of the melt itself has a large time constant for stabilization due to convection, the waiting time 1, for example, several minutes before introducing the crystal substrate can be ignored. Furthermore, since two crucibles are used alternately, the temperature raising/lowering cycle time can be used effectively, resulting in a significant improvement in efficiency.

Furthermore, according to the above-mentioned embodiment, it is extremely easy to suppress the temperature distribution within the melt to within ±l''C, and the cycle time can be halved to about 1/2 of the conventional temperature distribution. .

In the above embodiments, the case where two crucibles are used has been described, but it is clear that the same effect as described above can be obtained even in an illumination in which a preheating chamber is provided on only one side of the growth heating chamber.

As explained above, according to the present invention, the temperature of the melt can be reduced to 111 m, which is necessary for crystal growth! It is possible to correctly match the m degree distribution in the melt and to maintain it within ±1°C, 2, and to prevent micro-precipitation from occurring in the melt during temperature raising/lowering cycles, further eliminating unreasonable growth preparation time. Therefore, an extremely excellent effect can be obtained in which a high quality crystal growth film can be grown by liquid phase epitaxial growth with high efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS Figure #1 is a cross-sectional configuration diagram of essential parts showing an example of a conventional liquid phase epitaxial growth apparatus, and Figure #2 is a cross-sectional configuration diagram of essential parts showing an example of a liquid phase epitaxial growth apparatus according to the present invention. 1.1'...melt, 2.2'...melt, 3.
... Heater, 4 ... Soaking tube, 8 ... Stirrer,
9...Crystal substrate, 10...Heating chamber, 10m...
・・Growth heating chamber, IQbjOc・・・Preheating chamber,
11...Box body, 12...Cylinder body, 13.14.1
4a, 14b, 15----Heater, 16.17...
... Heat shield plate, 18.19 ... Stirrer, 20. -2
1... Base plate, 22.23... Moving mechanism. Figure 1 Figure 2

Claims (1)

[Claims] A crucible containing a melt for crystal growth K11i, a heating chamber for creating a temperature distribution necessary for the melt, and a crystal substrate support disposed above the crucible so as to be able to move up and down once. A liquid phase epitaxial growth apparatus comprising: a preheating chamber provided on at least four sides of the heating chamber; a stirrer for the melt provided above the preheating chamber; The method is characterized in that a heat shield plate is provided at the boundary of the preheating chamber so as to be freely inserted and removed, and a moving mechanism is provided for freely moving the crucible between the heating chamber and the preheating chamber. Liquid phase epitaxial growth equipment.