JPS6077193A - Apparatus for epitaxial growth of crystal in liquid phase - Google Patents

Abstract

PURPOSE:To make it possible to grow a crystal of good quality epitaxially in the liquid phase, by means of an adsorption plate for adsorbing and removing contaminants provided in a path for leading a melt for epitaxial growth to a substrate. CONSTITUTION:A melt 4 is passed from a melt inlet port 10 through a path 9 and fed onto a substrate 6 contained in a substrate holder 5, and the melt 4 at a height of a melt discharging outlet 11 provided at a position a little higher than the surface of the substrate 6 is held on the substrate 6. The excess melt 4 is then discharged from the discharging outlet 11 to a melt reservoir 12. The melt 4 introduced from the melt inlet port 10 is passed over adsorption plates 15 and 16 for contaminants until the melt 4 reaches the top of the substrate 6, and oxides in the melt 4 and powder of carbon which is a boat material are easily removed by the adsorption plates 15 and 16 and scarcely reach the top of the substrate 6 for growth. Therefore, the clean melt 4 is brought into contact with the surface of the substrate 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Encapsulation of the Invention] This invention relates to improvements in liquid phase epitaxial crystal growth equipment.

[Prior art]

FIG. 1(a) is a plan view showing an example of a conventional liquid phase epitaxial crystal growth fft called a sliding boat;
FIG. 1(b) is a cross-sectional view taken along line IB-IB. In the figure, (1) is the main body, (2) is a slider placed on the main body +I+ and configured to be slidable in the directions of arrows X and Y in the figure, (31 is a slider (provided on 2+, and the open bottom is on the main body +I+). .1 melt pail covered with the top surface of (
4) is the melt 1a (melt housed in 31, (5j
is a substrate holder consisting of a concave portion provided on the top surface of the main body (1), (6) is a substrate holder (substrate housed in the fil), (7) is a hole provided in the moving part of the slider (2), (8)
) is an operating rod that is inserted into the hole (7) and slides the slider (2) in the directions of arrows X and Y.

Next, the operation of the above-mentioned conventional apparatus will be explained by taking as an example the case where a gallium arsenide (GaAs) layer is grown on a gallium arsenide (GaAs) substrate. Melt (4) consisting of Ga, At and A8 is charged into melt at3+. The ratio of the charged components is determined depending on the composition of the crystal layer to be grown, and a required amount of p-type or n-type impurity is added as necessary. A GaAs substrate for growth (61) is housed in the substrate holder (6).These are placed in a preheated furnace (not shown) and kept until the temperature becomes stable. After that, slide the slider (2) in the X direction using the operating rod (8) so that mel)fm[31 is placed above the board (6). This causes the melt (4) to flow onto and rest on the substrate (6).

The temperature of the furnace is then reduced at an appropriate rate. As a result, supersaturated GaAtA3 is precipitated, and liquid phase epitaxial crystal growth is performed. After obtaining the required growth H4 thickness, return the slider (2) to its original position using the rr1 operating rod (8) and remove the melt (4) on the substrate (6).
Pull out this liquid phase epitaxial crystal growth apparatus from the furnace 7
, if you take out the substrate (61), GaA on the GaAp base,
! A wafer in which As crystal is grown by liquid phase epitaxial growth is obtained.

However, with this conventional device, the melt (4) contains contaminants such as oxides and carbon powder produced by scraping carbon, which contaminates the surface of the substrate (61). When the melt (4) is placed on the substrate (6), these contaminants quickly adhere to the surface of the substrate (61), causing poor crystal growth and crystal defects.

[Summary of the invention]

This invention has been made in view of the above points, and provides an apparatus capable of growing high-quality liquid phase epitaxial crystals by providing a suction plate that adsorbs and removes contaminants in the path that carries the melt to the substrate holder. This is what we provide.

[Embodiments of the invention]

FIG. 2(a) is a plan view showing the configuration of an embodiment of the present invention, and FIG. 2(b) is a cross-sectional view taken along the uB- and [lB lines.
The same symbols as in FIG. 1 indicate the same parts. (9) is a passage through which the melt (4) flows, and a substrate holder (5) for accommodating the substrate (6) is provided facing this passage (9). (
1111 is the melt inlet opening on the upper surface of the main body (1) of the channel (9), and H is the melt inlet opening on the top surface of the main body (1) of the channel (9).
The melt outlet opens at a position slightly higher than the top surface of the (1)
(2) are melt reservoirs for storing the used melt (4) discharged from the melt outlet (11), o4 and (I);
4) is a suction plate holder portion which is provided between the melt inlet (101) of the passageway (9) and the substrate holder (5) and accommodates the contaminant fi!r suction plates (161 and θG), respectively. It is preferable that the substrate 11 be made of the same material as the substrate (6) or the growing crystal layer.

In this S'-11A example, aah
This will be explained using an example of growing Lhel. Melt cypress (Jt) is filled with melt (4) containing Ga, At, and AS in a narrow component ratio of θ, as in the case of the conventional example, with no impurities ≤ (not shown), and after the temperature stabilizes, slide the slider (2) in the X direction using the operating rod (8) to move the melt cypress (3) directly above the melt inlet (lO). let

As a result, the melt (4) is supplied from the melt inlet (10) through the passage (9) onto the substrate (6) housed in the substrate holder (5), and the melt outlet (ol is located at a slightly higher position). Since the melt (4) is provided at that height above the substrate (6), the excess melt (4) is removed from the melt outlet (from the river to the melt reservoir (121).
leaks to.

Melt (4) introduced from this melt inlet (lO)
Before reaching the substrate (6), it passes over the contaminant adsorption plate (In, (l!), and the oxides in the melt (4) and the carbon powder that is the port material are absorbed by this contaminant. The substance adsorption plate 05) is easily adsorbed and removed by the θ smell and hardly reaches the top of the growth substrate (6).
The clean melt (4) comes into contact with the surface of 6).

Hereafter, as in the conventional example, by lowering the furnace temperature, G
GaAtAsQ liquid phase epitaxial growth is performed on the aAθ substrate (6), and when the required thickness is obtained, the apparatus is pulled out from the furnace, and after cooling, the substrate wafer (6) is taken out.

If the surface of the pollutant adsorption plate is made uneven, such as wavy or serrated, to increase the surface area, the adsorption capacity will be dramatically increased.

In the above example, the case where a GaAtAs layer is grown on a GaAs substrate was explained, but it is of course applicable to crystal growth of other materials. The present invention can also be applied to a case where a plurality of melt tanks are provided to perform multilayer liquid phase epitaxy growth, and the present invention can also be applied to an apparatus of a type in which melt is guided onto a substrate by a so-called bush-out method.

〔Effect of the invention〕

As explained above, in the liquid phase epitaxial crystal growth apparatus according to the present invention, since a contaminant adsorption plate is provided in the passage leading the crystal growth melt onto the growth substrate, the contaminants in the melt are adsorbed and removed and the melt is cleaned. A high quality melt is supplied onto the substrate, resulting in a high quality epitaxial growth layer.

[Brief explanation of drawings]

Figure 1(a) is a plan view showing an example of a conventional liquid phase epitaxial crystal growth apparatus, and Figure 1(b) is its ■B-IB
2(a) is a plan view showing an embodiment of the present invention, and FIG. 2(b) is a sectional view taken along line rlB-rlB. In the figure, (1) is the main body, (2) is the slider, (3)
(4) is a melt tank, (4) is a melt), +51 is a substrate holder, (6) is a substrate, (9) is a passage, (1151 is a melt inlet, an O hammer, and 061 is a contaminant adsorption plate. The same numbers in the middle indicate the same or equivalent parts. Agent Masuo Oiwa

Claims (5)

[Claims] (1) In the method of growing the desired crystal layer by covering the substrate with a melt having a composition corresponding to the composition of the crystal layer to be epitaxially grown on the substrate, the melt is deposited on the substrate. A liquid phase epitaxial crystal growth apparatus characterized in that a contaminant adsorption plate for adsorbing and removing contaminants from the melt is provided in the passage. (2) The liquid phase epitaxy crystal growth apparatus according to claim 1, wherein the contaminant adsorption plate is made of a material having the same composition as the substrate. (3) The liquid phase epitaxial crystal growth apparatus according to claim 1, wherein the contaminant adsorption plate is made of a material having the same composition as the crystal layer to be grown. (4) Claim 1, characterized in that the contaminant adsorption plate has a large surface area by providing unevenness on its layer surface.
The liquid phase epitaxial crystal growth apparatus according to item 2, item 2, or item 3'8J. (5) Paragraphs 1 to 4 of Box 9 of the patent design characterized in that contaminants @e and attached plates are provided above and below the melt passage.
The liquid phase epitaxial crystal growth apparatus according to any one of Items 1 to 9.