JPH1179884A - Liquid phase epitaxial growth apparatus and growing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a uniform epitaxial growth layer on a semiconductor substrate by dipping a semiconductor substrate into a solution, separating the semiconductor substrate from the solution near the substrate, arranging the other solution at the part around a shielding member and cooling the solution to effect the growth of a crystal on the semiconductor substrate. SOLUTION: A substrate holder 16 holding a semiconductor substrate 17 is inserted into a shielding member 19 and held in a holding chamber 13. The holding chamber 13 is set to a liquid phase epitaxial apparatus in such a manner as to close an opening 12a with a wall part 16a and a solution tank 14 is charged with a solution component material 18' to be subjected to epitaxial growth. The material 18' is heated to form a solution 18 and the substrate holder 16 is pulled into the solution tank 14 to effect the contact of the semiconductor substrate 17 with the solution 18. Thereafter, the shielding member 19 is moved into the solution tank 14, the solution 18a in the shielding member 19 is shielded from the solution 18b out of the shielding member 19 and the substrate holder 16 is moved to an epitaxial growth position and cooled to effect the epitaxial growth on the semiconductor substrate 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid phase epitaxial growth apparatus for growing a semiconductor crystal on a semiconductor substrate in a semiconductor solution.

[0002]

2. Description of the Related Art FIG. 4 is a view showing a conventional liquid phase epitaxial growth apparatus and a growth process. As shown in FIG. 4A, the housing 51 has a partition plate 52 at the center thereof, and is divided into a growth tank 53 and a solution tank 54. A piston 55 for pushing the solution from outside the housing 51 is attached to the solution tank 54. The liquid phase epitaxial growth apparatus 50 is generally formed of graphite that has been subjected to high purity processing.

A growth tank 53 contains a semiconductor substrate 57 supported by a graphite substrate folder 56. On the other hand, the solution tank 54 contains a material 58 'to be a material of the epitaxial growth layer. As the semiconductor substrate 57, for example, a GaAs substrate is used.
As 8 ', Ga, GaAs polycrystal, dopant and the like are used.

In this state, the liquid-phase epitaxial growth apparatus 50 is put into a growth furnace in a hydrogen gas atmosphere, and
The temperature is raised to about 00 ° C. Then, the substance in the solution tank is dissolved to form a solution 58 as shown in FIG. In this state, the temperature is kept constant for a while, and the temperature of the liquid phase epitaxial growth apparatus 50 is stabilized.

[0005] Next, the piston 55 is moved in the direction of the partition plate 52. Then, as shown in FIG.
8 moves over the partition plate 52 toward the growth tank 53. The substrate holder 56 and the semiconductor substrate 57 placed vertically on the substrate holder 56 are immersed in the solution 58. In this state, the component is gradually cooled, and the components of the solution 58 are epitaxially grown on the semiconductor substrate 57.

[0006]

In the liquid phase epitaxial growth method, two processes of growth are carried out: a process of transporting a grown material to a growth interface and a process of depositing the transported material as crystals. However, one of the factors that influence the former growth process is the state of heat radiation when the temperature of the solution is lowered. The heat radiation state depends on the shape of the growth tank and the temperature characteristics of the material and the solution in it. The difference is affecting.

That is, since Ga, which is the solvent of the solution, has a lower thermal conductivity than the liquid phase epitaxial growth apparatus for graphite, a temperature difference occurs near the inner wall of the growth tank and near the center of the growth tank during the cooling process. That is, the reaction to the cooling operation tends to grow quickly near the inner wall of the growth tank, but the reaction to the cooling operation is slow and hard to grow near the center of the growth tank.

Further, in the case of a structure in which semiconductor substrates are arranged vertically as shown in the conventional example of FIG. 4, in order to process as many semiconductor substrates as possible at once, the distance between the substrates is made as small as possible. In the central part of the substrate, it is difficult to supply the solute, and the growth rate is reduced. On the other hand, the periphery of the substrate is also a solute supply source since the solution also surrounds the periphery from the outer peripheral direction of the substrate, and the growth rate increases.

As described above, in the conventional liquid phase epitaxial growth apparatus, the peripheral portion is thicker than the central portion of the semiconductor substrate, and the epitaxial growth film thickness is not uniform.

The present invention has been made in view of the above problems, and has as its object to provide a liquid phase epitaxial growth apparatus capable of forming a uniform epitaxial growth layer on a semiconductor substrate.

[0011]

According to a first aspect of the present invention, there is provided a liquid phase epitaxial growth apparatus for growing a crystal on a semiconductor substrate in a solution in which a semiconductor material is melted. It has a shielding member for isolating it from the surrounding solution.

In the liquid phase epitaxial growth apparatus according to a second aspect of the present invention, the outside of the shielding member is in contact with the solution during epitaxial growth.

A liquid phase epitaxial growth method according to a third aspect of the present invention is a liquid phase epitaxial growth method for growing a crystal on a semiconductor substrate in a solution in which a semiconductor material is melted, wherein the semiconductor substrate is immersed in the solution. Later, while isolating the solution near the semiconductor substrate together with the semiconductor substrate,
Other solutions are placed around the shielding member and cooled,
A crystal is grown on the semiconductor substrate.

[0014]

FIG. 1 is a schematic sectional view showing a liquid phase epitaxial growth apparatus according to an embodiment of the present invention.
In FIG. 1, the casing 11 is divided into two parts by a partition plate 12, one of which is a storage chamber 13 for storing a shutter 19, and the other is a solution tank 14. The partition plate 12 is provided with an opening 12a through which a shutter 19 as a shielding member is moved. The shutter 19 is moved between the storage chamber 13 and the solution tank 14 by operating the connecting rod 20. be able to. Shutter 19
Is fitted with the opening 12a, and the shutter 19
The solution does not leak from the gap between the opening 12a.

A substrate holder 16 for holding the substrate is provided at a position facing the shutter 19, and the semiconductor substrates can be vertically arranged at a predetermined interval in the substrate holder. The substrate holder 16 is attached to the end of the connecting rod 15,
5, the substrate holder 16 moves the opening 1
It is possible to move between the storage chamber 13 and the solution tank 14 via 2a. Further, the substrate holder 16 is attached to the wall 16.
a and a wall portion 16b, and the wall portion 16a has an opening 12a when the substrate holder 16 moves to the storage room 13.
The wall 16b has a function of preventing the solution from entering the space inside the shutter 19 in the storage chamber 13 when the substrate holder moves to the solution tank 14.

The above-described liquid phase epitaxial growth apparatus 10
Is formed from graphite that has been subjected to high purity processing. The semiconductor substrates 17 are vertically arranged at predetermined intervals in the substrate holder 16.

FIG. 2 is a process chart of the epitaxial growth using the liquid phase epitaxial growth apparatus, and FIG. 3 is a graph showing the temperature control in the process.

In FIG. 2A, the shutter 19 is located in the storage room 13, and the substrate holder 1 is located in the shutter 19.
6 has been inserted. For example, Ga
A large number of semiconductor substrates 17 made of As material are fixed at predetermined intervals in the vertical direction.

The substrate holder 16 is located on the storage chamber 13 side, and is set so as to close the opening 12a with the wall 16a. The solution tank 14 is filled with a material 18 'such as Ga, GaAs polycrystal, or dopant, which is a component of a solution to be epitaxially grown.

In this state, the liquid phase epitaxial growth apparatus 1
0 was put into a growth furnace in a hydrogen gas atmosphere, and the temperature was controlled as shown in FIG. 3 to raise the temperature to 800 to 1000 ° C., thereby obtaining the material 1 as shown in FIG.
8 ′ is melted into solution 18. Subsequently, as shown in FIG. 3, the temperature is maintained (held) for a predetermined period of time (about 1 to 3 hours) so that a solution having a uniform composition as a whole is obtained.

Subsequently, as shown in FIG. 2C, the connecting rod 15 is operated to move the substrate holder 16 to the semiconductor substrate 1.
The semiconductor substrate 17 is brought into contact with the solution 18 together with the solution 7 into the solution tank 14 filled with the solution 18. At this time, when the solution 18 flows into the shutter 19, the solution tank 1
There is a fear that the liquid level of 4 drops and the solution 18 does not contact the surface of the semiconductor substrate 17. However, shutter 19
Since the substrate holder 16 inside is fitted to the shutter 19 by the wall portion 16b, it is possible to prevent the solution 18 from flowing into the space inside the shutter 19.

Subsequently, as shown in FIG. 2D, the shutter 19 is moved into the solution tank 14 by operating the connecting rod 20. The solution around the shutter 19 is seen, and the solution 18a inside the shutter 19 and the solution 18b outside the shutter 19 are shut off. The liquid used for crystal growth is only the solution 18a inside the shutter 19, and is limited to a minimum solution necessary for crystal growth. Further, the solution 18b outside the shutter 19 is not used for growing the epitaxial layer.

Subsequently, as shown in FIG. 2E, the connecting rods 15 and 20 are operated to operate the substrate holder 16.
To the epitaxial growth position.

As shown in FIG. 3, FIG.
After completion of the operations (d) and (e), cooling is performed,
/ Min to 3 ° C / min at a cooling rate of 500 ° C to 700 ° C
The crystal is grown by lowering the temperature to ° C., and an epitaxial layer is formed on the semiconductor substrate 17. At this time, most of the outside of the shutter is in contact with the solution 18b, and the temperature of the graphite shutter 19 having good thermal conductivity does not drop sharply compared with the solution 18 during the cooling process.

Thereafter, the liquid phase epitaxial growth apparatus is taken out of the growth furnace, and the liquid phase epitaxial growth apparatus is disassembled into parts, and the semiconductor substrate and the solution are taken out.

In the epitaxial growth method shown in the conventional example, the thickness of the epitaxial growth layer in the peripheral portion is about 20% thicker than the thickness of the epitaxial growth layer in the central portion of the substrate. Could be suppressed.

The periphery of the shutter 19 is filled with the solution 18b, and the temperature difference between the shutter 19 and the solution in the cooling process is reduced, so that the temperature distribution of the solution in the shutter 19 approaches uniformity. A uniform epitaxial layer can be formed.

Further, the solution used for epitaxial growth is limited to the solution in the shutter, and solutes are not supplied from the outer peripheral direction of the substrate. Therefore, it is possible to prevent the peripheral portion of the substrate from growing more than the central portion. A uniform epitaxial layer can be formed.

[0029]

According to the liquid phase epitaxial growth apparatus according to the first aspect of the present invention, there is provided a liquid phase epitaxial growth apparatus for growing a crystal on a semiconductor substrate in a solution in which a semiconductor material is melted. Having a shielding member for isolating the semiconductor substrate from the surrounding solution can prevent the peripheral portion of the semiconductor substrate from growing more than the central portion, and can form a uniform epitaxial layer on the semiconductor substrate.

Further, according to the liquid phase epitaxial growth apparatus of the second aspect of the present invention, the outside of the shielding member is in contact with the solution during epitaxial growth, and the outer solution is the shielding member. In order to prevent heat radiation from the semiconductor substrate, the temperature difference between the shielding member and the solution near the semiconductor substrate is reduced, and a uniform epitaxial layer can be formed on the semiconductor substrate.

According to a third aspect of the present invention, there is provided a liquid phase epitaxial growth method for growing a crystal on a semiconductor substrate in a solution in which a semiconductor material is melted. After soaking,
While isolating the solution near the semiconductor substrate together with the semiconductor substrate, arranging other solutions around the shielding member to perform cooling, and growing crystals on the semiconductor substrate, a uniform epitaxial layer is formed on the semiconductor substrate. Can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a liquid phase epitaxial growth apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a step of epitaxial growth by a liquid phase epitaxial growth apparatus according to an embodiment of the present invention.

FIG. 3 is a graph showing temperature control of the liquid phase epitaxial growth apparatus.

FIG. 4 is a schematic sectional view showing a conventional liquid phase epitaxial growth apparatus and a growth process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Liquid-phase epitaxial growth apparatus 11 Housing 12 Partition plate 12a Opening (of partition plate) 13 Storage room 14 Solution tank 15 Connecting rod 16 Substrate holder 16a, 16b Wall of substrate holder 17 Semiconductor substrate 18 Solution 18a (of shutter) Solution 18b (inside) Solution 19 (outside shutter) 19 Shutter 20 Connecting rod

Claims (3)

[Claims] 1. A liquid phase epitaxial growth apparatus for growing a crystal on a semiconductor substrate in a solution in which a semiconductor material is melted, comprising a shielding member for isolating a solution near the semiconductor substrate from a solution around the semiconductor substrate. Liquid phase epitaxial growth equipment. 2. The liquid phase epitaxial growth apparatus according to claim 1, wherein the outside of said shielding member is in contact with a solution during epitaxial growth. 3. A liquid phase epitaxial growth method for growing a crystal on a semiconductor substrate in a solution in which a semiconductor material is melted, wherein the solution near the semiconductor substrate is isolated together with the semiconductor substrate after the semiconductor substrate is immersed in the solution. And a liquid phase epitaxial growth method comprising arranging another solution around the shielding member and performing cooling to grow a crystal on the semiconductor substrate.