JPH0763052B2 - Semiconductor crystal growth method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a semiconductor crystal growth method.

Configuration of Conventional Example and Problems Thereof Liquid crystal epitaxial growth and vapor phase epitaxial growth are typical representatives of semiconductor crystal growth methods that are usually performed. The slide board method is often adopted in liquid phase epitaxial growth.

The problems with the semiconductor crystal growth method include the following items.

It is difficult to avoid undesired impurities and dust particles of about micron size from entering the crystal growth member, and it is difficult to remove the mixed impurities.

Particularly in the case of liquid phase epitaxial growth, it is difficult to grow a growth layer having a film thickness of 1 μm or less with good reproducibility.

 There is a meltback problem.

As a method of solving the above problems, a method of placing a crystal plate 4 between a semiconductor single crystal growth plate 2 on a substrate holder 1 and a crystal growth solution 3 as shown in FIG. 1 has been attempted.
A slide boat 5 serves as a crystal growth solution reservoir. The arrow indicates the solution slide direction. Impurities and dust from the problems in the previous section are adhered to and removed from the crystal plate 4.
It is intended to adjust the degree of supersaturation by covering the crystal growth solution 3 with the crystal growth solution 3 and perform epitaxial growth to solve the problems as well as the problems, but it cannot be said that the problems (1) to (3) are sufficiently solved.

OBJECT OF THE INVENTION The present invention aims to solve all of the above-mentioned conventional problems.

In order to achieve the above object, the semiconductor crystal growth method of the present invention is a slide boat type liquid phase epitaxial growth method or vapor phase epitaxial growth method, in the side of the semiconductor single crystal plate, the depth of steps and grooves on the surface. 0.5μm or more, bitch 1μ
A crystal plate having irregularities of m or more in an inverted mesa shape is arranged, and a crystal growth solution or a crystal growth gas is passed over the crystal plate and then allowed to reach the semiconductor single crystal substrate.

Description of Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows an example of liquid phase epitaxial growth by the slide boat method. In the figure, 11 is a substrate holder, on which a semiconductor single crystal substrate 12, a crystal growth solution 13 and a crystal plate 14 are provided between them. 15
Is a slide boat that serves as the crystal growth solution reservoir.
The semiconductor single crystal substrate 12 and the crystal plate 14 are GaAs substrates. By the way, the surface of the crystal plate 14 has a depth of 1.5 μm.
Steps 14a with m and 200 μm pitch are provided in an inverted mesa shape. The growth temperature is 850 ° C. and is cooled at a cooling rate of 0.5 ° C./min or less to obtain a supersaturation degree of about 5 ° C., and the slide boat 5 is slid in the direction of the arrow in FIG.
The crystal growth solution 13 is coated on the top for 10 seconds and then further slid, so that the crystal growth solution 13 is coated on the semiconductor single crystal substrate 12, and in this manner, different crystal growth solutions are sequentially slid to perform multi-layer growth. . After crystal growth, the growth surface was observed and the film thickness of each layer of the multilayer epitaxial layer was measured.

FIG. 4 shows a typical surface condition after crystal growth. The following table is a quantification of their surface states, and the percentage of mirror growth on the entire surface is shown as a percentage. In addition, the following table shows the results of examining each of the 5 lots.

FIG. 4 (a) shows the case where a flat crystal plate is placed in front, and FIG. 4 (b) shows the case where a stepped crystal plate is placed instead of the crystal plate shown in FIG. 4 (a). In FIG. 4, the shaded portion indicates the cloudy portion and the white portion indicates the mirror surface. It can be seen that the ratio of mirror growth is better in (b) than in (a) for the semiconductor single crystal substrate. On the other hand, regarding the crystal plate, (a) is better, but there is no difference between (a) and (b). Other experiments have shown that the smaller the step depth of the crystal plate is 0.5 μm or more and the pitch is 1 μm or more, the smaller the effect is. The reverse mesa has a greater effect on the step between the forward mesa and the reverse mesa. There is. From the above, it was found that by providing the crystal plate 14 with the concavo-convex portion, stains during growth on the semiconductor single crystal substrate 12 can be effectively removed. It was also observed by photoluminescence measurement that the growth film on the semiconductor single crystal substrate 12 in the case of FIG.
It has been revealed that it also has a gettering effect for unwanted impurities. In this growth, a layer having a film thickness of 0.5 μm was grown, and the variation in film thickness at that time was reproduced as ± 0.2 μm by the method of FIG. 4 (a) and ± 0.1 μm by the method of FIG. 4 (b). The property has improved. Further, a step was also provided on the semiconductor single crystal substrate 12, and the influence of meltback on the presence or absence of the step structure on the crystal plate 14 was examined. It was observed that when the crystal plate 4 having a step structure is used, the meltback amount is reduced by about 30%, and the shape reproducibility after the meltback and the shape reproducibility of the epitaxial growth layer thereon are improved accordingly. The crystal plate 14 and the semiconductor single crystal substrate 12 are GaAs substrates, but other compound semiconductors such as GaP and InP, and semiconductors such as Si and Ge can be used.

FIG. 3 shows a vapor phase epitaxial growth method as a second embodiment of the present invention. In the figure, 21 is a susceptor (substrate holder), 22 and 23 are semiconductor single crystal substrates and crystals provided on the susceptor 21. A plate, 24 is a quartz reaction tube in which this is put, and 25 is a crystal growth gas inlet provided at one end of this quartz reaction tube 24. The crystal plate 23 has uneven portions such as steps on its surface and is located on the upstream side in the flow direction of the gas flowing in from the crystal growth gas inlet 23, and the semiconductor single crystal plate 22 is located on the lower side. As described above, after the crystal growth gas has passed over the crystal plate 23, the semiconductor single crystal plate 22
Even if it reaches, the same result as in the first embodiment can be obtained.

That is, the crystal plate 23 has a depth of 2 μm or 4 μm on its surface.
m, pitch steps are formed in an inverted mesa shape, and the growth temperature is 700
Vapor phase growth was performed under the conditions of a crystal growth condition of 0 ° C. and a total gas flow rate of 2 / min. The results are shown in Fig. 5 (a). It can be seen that good mirror surface growth is achieved over almost the entire surface of the semiconductor single crystal substrate 22. Further, FIG. 5B shows an example in which a flat crystal plate 23 having no surface irregularities is placed on the upstream side in the gas flow direction as viewed from the semiconductor single crystal substrate 22. In this case, the rate of mirror surface growth of the semiconductor single crystal substrate 22 is smaller than that in FIG. 5 (a).

Further, when the crystal plate 23 is not placed, the rate of further mirror growth is reduced as shown in FIG. 5 (c). In the following table, the results of examining 5 lots each under the conditions of FIGS. 5 (a) to 5 (c) are shown.

As is clear from the above, the stains and impurities contained in the crystal growth material in the gas are removed by the crystal plate 23, and the effect is particularly remarkable by providing grooves such as irregularities on the surface of the crystal plate 23. In addition, the mesa shape of the reverse mesa is
It turned out that the effect of removing dirt was great.

EFFECTS OF THE INVENTION The semiconductor crystal growth method of the present invention can be carried out as described above, and by providing the crystal plate with uneven portions (such as grooves) such as steps, it is possible to grow the semiconductor crystal on a semiconductor single crystal substrate. It can effectively remove dirt. In addition, it was found that the grown film on the single crystal substrate showed strong luminescence by means of fault luminescence measurement, etc., and it was found to have an effect of gettering impurities. Further, the meltback amount is also reduced, and the reproducibility of the shape after the meltback and the reproducibility of the shape of the epitaxial growth layer thereon are improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a conventional liquid phase epitaxial growth method by a slide boat method, and FIG. 2 (a) is an explanatory view showing a liquid phase epitaxial growth method by a slide boat method in the first embodiment of the present invention. b) is a plan view of a crystal plate used in the growth method, FIG. 3 is an explanatory view showing a vapor phase epitaxial growth method in a second embodiment of the present invention, FIGS. 4 (a) and (b) and FIG. 5 ( (a)-(c) is explanatory drawing which shows the surface state after crystal growth. 11 …… Substrate holder, 12 …… Semiconductor single crystal substrate, 13 ……
Crystal growth solution, 14 ... Crystal plate, 14a ... Step, 15 ... Slide boat, 21 ... Susceptor, 22 ... Semiconductor single crystal substrate, 23 ... Crystal plate, 24 ... Quartz reaction tube, 25 ... Gas inlet for crystal growth.

Claims (1)

[Claims] 1. A slide board type liquid phase epitaxial growth method or a vapor phase epitaxial growth method, wherein a depth of a step, a groove or the like on a surface of a semiconductor single crystal substrate is 0.5.
A semiconductor crystal growth method in which a crystal plate having concavities and convexities of μm or more and a bitch of 1 μm or more is arranged in an inverted mesa shape, and a crystal growth solution or a crystal growth gas is passed over the crystal plate and then reaches the semiconductor single crystal substrate. .