JPS6021956B2 - Liquid phase growth method for semiconductor layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus and method for liquid phase epitaxial formation of various semiconductor layers on a semiconductor substrate containing phosphorus (P).

One of the semiconductor substrates containing phosphorus, for example ln
P substrates are extremely susceptible to thermal decomposition, and P evaporates from the surface of a single substrate even when heated at 6500 C for 30 minutes.

For this reason, many small ball-shaped ln are left on the surface of the 1st stem plate, and the flatness of the substrate crystal surface is significantly impaired. Therefore, in order to smooth out such roughness on the crystal surface, it is necessary to introduce a process to slightly dissolve the surface of the lnP substrate immediately before epitaxial growth, or to form another semiconductor layer on the lnP substrate. They had no choice but to resort to methods such as
The purpose of the present invention is to keep the substrate exposed to P vapor until just before the start of liquid phase epitaxial growth.

The simplest method, for example, in the case of a single substrate, is to place a single crystal piece of the same type as a cover on the opposite side to prevent the evaporation of P that occurs during heating of the crystal, and to prevent the substrate crystal from evaporating. This allows liquid phase epitaxial growth to occur without causing any change in the surface state of the substrate. The cover may be made of any material that releases phosphorus vapor when heated, but in order to avoid contamination of the substrate with impurities, it is preferable to use one crystal power balance for one cape substrate. From the point of view of exposing the substrate to P vapor, the recess 7 of the device
Of course, it is also possible to separately feed P vapor into the lnP substrate to prevent P from being released from the lnP substrate. However, in practice, the equipment is large-scale. Hereinafter, the present invention will be explained in detail according to Examples.

FIG. 1 is a sectional view of a device explaining an embodiment of the present invention.
A slide plate 6 is made of graphite and has a recess 7 in which a growth substrate is to be placed.

A substrate containing phosphorus, for example, an n-type substrate 1 is placed in the recess 7.
is accommodated. Further, a one-book cover crystal 2 is installed on the n-type one-book storage crystal 1. The distance between the substrate crystal 1 and the lnP cover crystal 2 is preferably approximately 0.1 skin or less. on the other hand,
The solution receiver 5 is made of graphite and stores the following solutions. The first solution 3 is ln5, GaAs25, 1nA
Heat o of s260 and o of lnP51 to 7000C,
It was prepared by melting all the melt and then cooling it. The second solution 4 was added to Zno. 3 of 9, lnP5
Five females were brought into contact with each other. The whole boat, which is set up in a similar manner, is kept at a constant temperature, for example, 65
Heating was carried out at 0°C for 30 minutes, followed by cooling at a rate of 0.30°C per minute. Move the slide plate during cooling,
The substrate crystal 1 was sequentially brought into contact with the first solution 3 and the second solution 4, and a GainAsP layer and a P-type single layer were successively grown. In this way, we were able to obtain an extremely good epitaxial growth layer. In the present invention, since a cover crystal is provided in substrate 1, the surface condition of substrate crystal 1 does not change even during heating at 6500C for 3 minutes, and a growth layer of uniform thickness can be obtained.

Using this crystal, for example, a laser diode with a Gal melon P/lnP double heterostructure was prototyped, and as a result, a device capable of continuous operation at room temperature with good reproducibility was obtained.

In the above embodiment, a liquid phase growth layer was formed on a flat substrate crystal, but according to the present invention, since the surface state of the substrate crystal does not change due to high temperature heating, intentional irregularities are provided on the substrate crystal surface. Needless to say, even in such a case, a liquid phase growth layer can be formed on the surface while maintaining the uneven shape.

On the other hand, a comparative experiment was conducted using a graphite cover instead of the lnP cover crystal 2, and the surface state of the crystal was observed.

As a result, when the present invention in which an lnP cover was provided on a single substrate crystal was used, there were almost no irregularities, and a substrate suitable for liquid phase epitaxial use was obtained. On the other hand, when a cover made of graphite was used, many deep irregular irregularities were formed on the crystal surface, making it impossible to use it as an epitaxial substrate. The effects when the present invention is used in manufacturing a semiconductor laser will be explained.

If the number of lattice defects that occur in an epitaxial substrate is extremely large, it cannot be used as a substrate for the same purpose, and even if an epitaxial layer is grown, the defects will be inherited in the epitaxial layer, causing the same defects as in '1'. This causes an increase in leakage current, which has an adverse effect on the '21 lifespan and a decrease in reliability. When a semiconductor laser device with specifications similar to those of the above-mentioned embodiments is manufactured, the yield rate is 0% without a cover, but with a single cover, it is possible to secure a rate of 80 to 100%. Also, when using a quartz cover, it does not exceed 50%. Furthermore, when comparing the median value of the deterioration rate (rate of fluctuation in operating current) as an indicator of reliability, it is about 1%/kh when using an lnP cover, and 10%/kh when using a board with defects. It differs by about one order of magnitude from the kh level. In the above embodiments, a liquid phase growth apparatus having the simplest configuration has been illustrated, but it goes without saying that there are various modifications.

However, for any of the apparatuses, effects can be obtained by providing and holding a cover made of a single stem plate facing the substrate during soaking and holding immediately before the start of liquid phase epitaxial growth according to the present invention.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a liquid phase growth apparatus. 1... Substrate, 2... Cover that releases phosphorus vapor, 3
, 4...Solution, 5...Solution reservoir, 6.
...Sliding board. Aoi diagram

Claims (1)

[Claims] 1. A holding plate for accommodating a semiconductor substrate for liquid phase epitaxial use containing phosphorus and a solution reservoir for accommodating a solution. A liquid phase growth method for forming an epitaxial growth layer, characterized in that a cover made of an InP substrate is provided facing the substrate during soaking and holding before the start of liquid phase epitaxial growth. A liquid phase growth method for a semiconductor layer.