JPS59213699A - Process for liquid phase epitaxial growth - Google Patents

Abstract

PURPOSE:To form a clean epitaxial layer by attaching a dish contg. a wafer of a substrate slightly slantly to a cassette and carrying out liquid phase epitaxial growth with restricted rate of pushing and pulling of the dish into and out of the soln. of starting materials. CONSTITUTION:A carbon dish 3 contg. a wafer 4 is attached to a carbon cassette 2; the cassette 2 is pushed down to intrude into starting materials 5 for the epitaxial growth at the bottom of a carbon crucible; soln. 5 is poured onto the wafer 4 to cause liquid phase epitaxial growth. In this vertical dipping process, the rate of pushing down of said cassette 2 into the starting material soln. 5 and the rate of pulling up the cassette out of the starting material soln. 5 are controlled to <=1mm./min, and the dish 3 is pref. tilted by an angle 6 deg.+ or -2 deg. (theta), and the thickness l of the layer of the soln. above the wafer 4 is regulated, pref. to max. 1mm.. By this arrangement, uniform draining of the wafer 4 is possible and a clean epitaxial layer having a uniform thickness is formed on the wafer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a liquid phase epitaxial growth method.

(→ Background Art The horizontal sliding method and the digging method are known as conventional epitaxial growth methods.

FIG. 1 relates to the horizontal slide method, with (a) showing the state during epitaxial growth and (b) showing the state after epitaxial growth. Figure 2 relates to the tilting method in the dipping method, (a) before growth, (b) during growth,
(Q) shows the state after growth, and 1 is a wafer.

However, in the above conventional method, 1. Because the wafers are arranged in a flat shape, large-scale equipment is required for mass processing, making it uneconomical and not suitable for mass production. 2. Abnormal growth areas that occur around the wafers cause discontinuous movement of the upper jig. Therefore, there is a drawback that Ga remains on the epitaxial surface, resulting in uneven thickness of the epitaxially grown layer.

On the other hand, a cassette loaded with a stack of wafer plates is inserted into a crucible whose bottom contains epitaxial raw materials, dopants, etc., and the molten raw materials are poured onto the wafers to perform epitaxial growth. A mold dipping method is also known, and mass production is possible because wafers are stacked in multiple stages. The situation is shown in Figure 3.
In the figure, 1 is a carbon crucible, 2 is a carbon cassette, 3 is a carbon plate, 4 is a wafer of GaAs, GaP, etc.
5 is an epitaxial raw material such as Ga polycrystal + dopant. Figure 3(a) shows the state before epitaxial growth, showing the Ga doo polycrystal + placed in the bottom of the crucible.
Uniformize the dopant. Next, as shown in the state during epitaxial growth in (b), the cassette waiting at the top is inserted into the crucible. At this time, as shown in the exploded view of the carbon jig in (C), through the thin slit S provided in the cassette 2, the Ga polycrystalline dopant solution t rises and is uniformly poured onto the Ueno layer. . (d) At the end of the epitaxial process, the Ga polycrystalline dopant on the Ueno layer is collected into the crucible through a narrow slit provided in the cassette by the reverse operation to the above.

Although mass production is possible with this method as described above, the liquid is thick, for example, if the liquid thickness exceeds 111111, the Ga surface (
Polycrystals crystallize on the side opposite to the Ueno layer, resulting in variations in the thickness of the epitaxially grown layer. Furthermore, since the pressing down and pulling up speeds are fast, the solution remains on the wafer, causing variations in the thickness of the epitaxial layer.

C) Disclosure of the Invention The present invention relates to an improvement of the above-mentioned vertical dipping method, in which the dish in the cassette is tilted, and in particular, the tilt angle is set to 6±2.
The present invention provides a method for easily mass-producing clean epitaxial wafers by setting the vertical speed of the cassette in the crucible to 0°/min or more and 1-7 minutes or less.

That is, in the liquid phase epitaxial growth method using the vertical dipping method, the present invention reduces the pushing down speed of a cassette containing a substrate wafer into a raw material solution and the pulling up speed from the raw material solution to less than 1 mm per minute, and The present invention relates to a liquid phase epitaxial growth method characterized by tilting a wafer mounting plate. .

An outline of the method of the present invention is shown in FIG. 4, where (a) shows the state before epitaxial growth, (1)) shows the state during growth, and (C) shows the state after growth, and the numbers have the same meanings as in FIG. 3. , θ is the inclination angle of the carbon plate.

In the present invention, the number of ueno sheets can be stacked within the range allowed by the soaking length of the furnace, and currently up to 100 ueno sheets (stages) are possible.

The method of the present invention provides the following effects.

(1) Since the Ueno material to be epitaxially deposited is set in a layered manner, the carbon plate can be made thinner, and small size and mass processing are possible.

(2) The inclination angle of the carbon plate is constant throughout, and the JGa is evenly separated from the epitaxial wafer by gravity, allowing all the Eno to drain uniformly.

(3) The clearance between the crucible and the cassette is Q,
It has a filter effect because it is narrow with only one sieve. Since Ga passes through the narrow slit and is injected onto the wafer, thin films and precipitates generated on the raw material Ga are removed when the Ga passes through the slit, and clean Ga without scum is injected into the wafer. - Injected upwards. If this clearance is large, Ga saturated with GaAs will enter between the crucible and the cassette, and GaAs polycrystals will crystallize from the Ga that entered between the crucible cassette during slow cooling for epitaxial growth, making it difficult to pull smoothly. .

B) Best Mode for Carrying Out the Invention Embodiment 55 55 (1oo)-plane wafers of Sl doped n-type GaAs of φ 50 are loaded with a plate spacing of 2W+.
Deaf, Ueno - thickness 600μ, upper space 700μ), cassette push-down speed 1WmZ or less, growth start temperature 95
A GaAs epitaxial growth layer with a thickness of 80 to 100 μm ± 10 μm was formed on the above wafer under conditions of 0 to 900°C, cooling rate of 1 to b°C (the cassette is pulled up to remove the solution), and a pulling rate of 11 m/min or less. was gotten.

(e) Field of application of the invention The method of the present invention applies to GaP, GaAs, engineering nP.
Single layer or multilayer liquid phase epitaxial growth such as s
It can be effectively used for epitaxial growth of 1-doped GaAs for infrared light emission.

[Brief explanation of drawings]

Figures 1, 2, and 3 are diagrams showing the conventional epitaxial growth method, and Figure 1 relates to the horizontal slide method (a
) shows the state during epitaxial growth, (b) shows the state during epitaxial growth, and Figure 2 relates to the inclined dipping method, (a) shows the state before epitaxial growth, (b) shows the state during growth,
(C) shows the state after growth, regarding the third step Id' vertical dipping method, (a) before epitaxial growth, (b)
) shows the state during growth, (d) shows the state after growth, and (C) shows an exploded view of the carbon jig. FIG. 4 is a diagram showing the epitaxial growth method of the present invention, in which (a) shows the state before epitaxial growth, (b) shows the state during growth, and (C) shows the state after growth. Figure 1 (a) (b) Figure 2 (CI-) (b) (b)3. ,
3rd - (ω) 4th (CL)

Claims (3)

[Claims] (1) In the liquid phase epitaxial growth method using the vertical dipping method, the pushing down speed of the cassette containing 5 substrates into the raw material solution and the pulling up speed from the raw material solution are set to 11 EIl per minute or less, and A liquid phase epitaxial growth method characterized by tilting a phenol-mounting plate in a cassette. (2) The liquid phase epitaxial growth method according to claim 1, wherein the maximum solution thickness on each dish is 1w+. (3) The liquid phase epitaxial growth method according to claim 1, wherein the ueno-mounting device in the cassette is tilted at an angle of 6±2°.