JPS6229396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid phase epitaxial growth apparatus that can produce uniform, high-quality epitaxial growth layers on a large number of semiconductor substrates at once.

In general, there are two types of liquid phase epitaxial growth apparatuses: vertical and horizontal types. The vertical type, as shown in FIG. ,
In order to process a large number of semiconductor substrates 109, 109, . . . at the same time, it is common to support the semiconductor substrates 109, 109, . . . substantially horizontally as shown in the figure. On the other hand, in the case of a horizontal type, as shown in FIG.
A solution 112 is placed in a container 101 in which 09... is held and attached.
At this time, the semiconductor substrate 109,
If the semiconductor substrates 109... are placed on a slide plate (not shown), etc., it will not be possible to process a large number of them at the same time.
9, 109... are generally supported vertically.

In either case, these devices are connected to a reaction tube (vertical type,
The horizontal type name is based on the installation type of the reaction tube), and the solution 112,1 is heated in a furnace or high-frequency heater, etc.
Liquid phase epitaxial growth is performed by heating or slowly cooling a material such as No. 12. At this time, the solution 112,
112 has a thick liquid layer, so the temperature is 600 degrees or more.
When heated to 1300 degrees, there is a temperature gradient of 1 to 7 degrees.
A variation in impurity concentration of 1.2 to 3.4 times occurs in the depth direction in both cases. This causes differences in the growth thickness of the epitaxial growth layer and its impurity concentration.
In the vertical device shown in FIG. 1, there is little unevenness in the growth of each semiconductor substrate, but there is an extreme difference between semiconductor substrates located in deep layers and those located in shallow layers. When 109... is a light emitting diode, the luminous efficiency differs by about ±90%.

The horizontal type shown in Figure 2 is slightly better than the vertical type because there is a slight convection of the solution 112 in the vertical direction, but the growth thickness of one semiconductor substrate is
Taking a 5.0cm semiconductor substrate as an example, the lower part is 40μm.
When it grows, the upper part reaches 100 μm.

Also, the luminous efficiency at this time differs by about ±50%. Furthermore, in each of these semiconductor substrates, areas where epitaxial growth has progressed have a high impurity concentration and a rough surface, while areas where growth has been delayed have a low impurity concentration and a mirror-like surface. , both have low crystal quality.

The present invention has been devised to overcome these drawbacks, and enables uniform, high-quality epitaxial growth to be performed on a large number of semiconductor substrates at once.The present invention will be described in detail below.

FIG. 3 is a cross-sectional view of an epitaxial growth apparatus according to an embodiment of the present invention, with the reactor and equipment attached outside the reactor being omitted. Reference numeral 1 denotes a rotatable container made of carbon, quartz, etc., which has a rotating shaft 2 that can be operated from outside the reactor, and the inside of the container is divided into a solution reservoir 3 and a growth chamber 4. Reference numeral 5 denotes a slidable partition plate, which has a through hole 6. If the through hole 6 is positioned to match the liquid injection port 8 provided in the partition wall 7 of the solution reservoir 3, the solution reservoir 3 and the growth chamber are connected. 4, and if the partition plate 5 is inserted with the through hole 6 and the liquid injection port 8 not aligned as shown in the figure, both the solution reservoir 3 and the growth chamber 4 become closed chambers. A substrate holder 10 is installed in the growth chamber 4 to hold a large number of semiconductor substrates 9, 9, . . . substantially vertically. The substrate holder 10 is made by connecting a number of support plates 11, 11, etc. made of carbon or quartz, and the semiconductor substrates 9, 9, etc. are pasted with an adhesive or a material that has an equivalent function, or the support plates 11, 11 are provided with claws or the like to lock and hold the semiconductor substrates 9, 9....

Gallium phosphide (GaP) is used as the semiconductor substrate 9, 9...
The process using the apparatus of the present invention will be described by taking as an example the case where an n-type substrate is used and a p-type epitaxial layer is grown.

Solution reservoir 3 contains solution 1 in which impurities zinc (Zn) and gallium oxide (Ga ₂ O ₃ ) are dissolved in a solvent consisting of gallium (Ga) and gallium phosphide (GaP).
The entire device containing 2 is placed in a reactor and heated to approximately 1050°C. The hook 13 engaged with the diaphragm plate 5 is operated to slide the diaphragm plate 5 so that the through hole 6 of the diaphragm plate 5 and the liquid injection port 8 are aligned with each other as shown in FIG. As a result, the solution 12 in the solution reservoir 3 moves to the growth chamber 4 and comes into contact with the semiconductor substrates 9, 9, . . . . Thereafter, the hook 13 is operated to return the partition plate 5 to its original position, and the cooling is performed at a rate of 3° C. per minute. During cooling, the rotating shaft 2 was operated at a rate of half a revolution every 5 minutes. As a result, the container 1 becomes in the state shown in FIG. 5 or upside down as shown in FIG. 6, and the temperature distribution of the solution 12 becomes uniform, and the impurity concentration becomes uniform. The impurity that is particularly prone to segregation is zinc in this example, and it tends to precipitate above the container 12, but as this rotation changes the precipitation position and at the same time changes the temperature distribution, it dissolves into the solution again, causing a high concentration. While maintaining the distribution, the distribution is made uniform. Furthermore, the solution in contact with the semiconductor substrates 9, 9, . . . is renewed each time the rotation is performed. During this rotation, even when the growth chamber 4 is turned upside down as shown in FIG. 6, the solution 12 will not leak from the growth chamber 4 because the growth chamber 4 is closed by the partition plate 5. Repeat this to stop cooling at 840°C, and in the state shown in Figure 6, operate the hook 13 to slide the partition plate 5, align the through hole 6 and the liquid injection port 8 again, and pour the solution 12 into the solution reservoir. Move to 3.

When the epitaxial growth layer thus formed was measured, the thickness of the growth layer was 62 μm in the thin part and 62 μm in the thick part on the entire semiconductor substrate 9, 9... with a diameter of 5.0 cm.
77 μm, and the so-called flat portion of 70 μm±5 μm accounted for about 80%. In addition, since the semiconductor substrate 9 has good crystallinity and little variation in impurity concentration,
9. The light emitting diode using... has a luminous efficiency of 4.1
%, and the variation was small, within ±18%.

In the above-described embodiment, the rotating shaft 2 may be rotated half a rotation every few minutes (preferably half a rotation every 2 to 20 minutes), or may be rotated constantly using a low-speed motor or the like. Further, although the container 1 has a cylindrical shape in the figure, it is not limited to this, and the solution reservoir 3 may have an opening rather than a closed chamber, and may include a drainage reservoir in addition to the container 1. good.

As described above, the present invention provides a growth chamber in which a solution containing impurities can be stored at least temporarily (that is, during epitaxial growth) and can be rotated while the solution is stored; Tame and
During epitaxial growth, it is equipped with a partition plate that makes the growth chamber a closed room, and a substrate holder that holds a plurality of semiconductor substrates approximately vertically in the growth chamber, so that a large number of semiconductor substrates can be grown at once. Uniform, high-quality epitaxial growth can be performed on semiconductor substrates.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of a liquid phase epitaxial growth apparatus, FIG. 3 is a sectional view of an embodiment of the present invention, and FIG.
5 and 6 are explanatory diagrams of an epitaxial process using the apparatus of the present invention. DESCRIPTION OF SYMBOLS 1... Container, 2... Rotating shaft, 3... Solution reservoir, 4... Growth chamber, 5... Separation plate, 6... Through hole, 9, 9... Semiconductor substrate, 10... Substrate holder.

Claims (1)

[Claims] 1. A rotatably supported container, a growth chamber provided in the container and capable of storing a solution containing impurities during at least epitaxial growth, and a growth chamber provided in the container adjacent to the growth chamber. It is equipped with a solution reservoir, a partition plate that separates the growth chamber from the solution reservoir and makes the growth chamber a closed room during epitaxial growth, and a substrate holder that is housed in the growth chamber and holds a plurality of semiconductor substrates substantially vertically. A liquid phase epitaxial growth apparatus characterized by: