JPH0631199B2 - Method for manufacturing compound semiconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method for producing a compound semiconductor, and particularly to Ga.
The present invention relates to a method for pulling a compound semiconductor single crystal of P, GaAs, InP or the like.

(Prior Art) GaP, GaAs, InP, etc. III. The group V compound semiconductor single crystal is pulled up from the melt through a liquid sealant covering the melt in a high-pressure inert gas atmosphere by a pulling device as shown in FIG. This device is equipped with a pulling shaft in a high-pressure vessel (1) pressurized with an inert gas (2).
(6) and the crucible (2) is provided in a vertically movable and rotatable state, the raw material melt (9) in the crucible (2), and a liquid sealant (4) covering the upper layer thereof. Is thrown in. The crucible (2) is kept at a temperature suitable for pulling up by a heater (7) and a heat insulating cylinder (8) provided so as to surround the crucible (2). When pulling the single crystal, the pulling shaft (6) and the crucible (2) having the seed crystal attached to the tip thereof are rotated in the opposite directions at constant speeds. Once the seed crystal once immersed in the crucible is pulled up by the pulling shaft (6), the pulling shaft (6)
A single crystal grows sequentially from the seed crystal at the tip of.

(Problems to be solved by the invention) However, when the compound semiconductor single crystal is pulled by the above method, the raw material melt (9) is covered with a liquid sealant (4), and an inert gas (3) is added. Since it is performed under pressure, it is easily affected by the heat conduction of the liquid sealant (4), and heat convection due to high pressure is likely to occur. Therefore, the thermal environment in the high-pressure vessel (1) changes remarkably during the pulling of the single crystal, and there is a problem in the quality of the pulled single crystal, particularly in the homogeneity between the early stage and the late stage of pulling.

That is, since it is generally bound to optimize the growth conditions in the initial stage of pulling, the solid-liquid interface part of the melt (9) is reduced by the heat dissipation and the decrease in the melt volume as the pulling volume increases. The shape becomes unstable, and some unevenness appears in the melt (9). As a result, about 40% of the pulled crystal is polycrystallized.

The present invention has been made to improve the above object, the object is to stabilize the solid-liquid interface portion shape of the melt with the increase of the pulling amount and the decrease of the melt amount in pulling the compound semiconductor single crystal Provided is a method for producing a compound semiconductor single crystal, which obtains a high quality compound semiconductor single crystal.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, the crucible is melted from a melt of a compound semiconductor in a crucible in a high-pressure inert gas atmosphere through a liquid sealant coating the melt. When pulling a single crystal while rotating the pulling shaft and the pulling shaft in opposite directions, the relative rotation number between the crucible and the pulling shaft is gradually increased with the progress of pulling.

(Operation) As described above, by gradually increasing the relative rotational speed between the crucible containing the melt and the pulling shaft as the pulling amount of the single crystal increases, The shape of the solid-liquid interface with the liquid is stable. As a result, even if the pulling progresses and the melt amount decreases, the temperature in the vicinity of the solid-liquid interface portion becomes constant, and polycrystallization of the pulling body in the latter stage of pulling can be prevented.

(Example) FIG. 2 is a diagram showing the relationship between the length of a single crystal in pulling a single crystal which is an example of the present invention and the relative rotation number of the crucible and the pulling shaft. The parts of the pulling device that are the same as the conventional parts are as shown in FIG. Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2.

First, a crucible in which Ga and As as raw materials are placed in a high-pressure container (1) and a liquid sealant (9) such as B ₂ O ₃ is placed thereon.
Place (2). Then, the inside of the high-pressure container (1) is pressurized to 35 to 45 atm with an inert gas (3) such as N ₂ gas and heated by a heater (7) to turn Ga and As into a melt. Crucible
When the inside of (2) becomes the GaAs melt (9), the pressure of the inert gas (3) is reduced to about 15 to 25 atm, and the GaAs melt is melted.
A seed crystal for growing a GaAs single crystal is immersed in (9). Ga
After the seed crystal has become accustomed to the As melt (9), pull up the seed crystal (6)
3-5 r. p. Pulling is performed at a pulling speed of 6 to 8 mm / H while rotating at a constant speed of about m. At this time, the crucible (2) containing the GaAs melt (9) moved in the direction opposite to the rotation direction of the pulling shaft (6) for 5 to 10 r. p. In order to rotate at a speed of m, the relative rotation speed is 8 to 15 r. p. We are pulling up with m. And the grown GaAs single crystal
Pulling was continued under the same conditions until the length of (5) reached about 40 mm for the seed crystal, and when it reached about 40 mm as shown in FIG. 2, it was 1 r.p.m. for every 2 to 4 mm of rotation of the crucible. p.
It was increased at a rate of m until the crystal growth was completed.
When the length of the GaAs single crystal (5) reaches about 40 mm from the seed crystal, the number of rotations of the crucible (2) is increased by increasing the pulling amount when the length becomes 30 to 50 mm. This is because the shape of the pulling body of the GaAs single crystal (5) and the solid-liquid interface (10) of the melt (9) begins to become unstable due to the decrease in the melt volume, and the temperature in the melt becomes uneven. is there. By pulling in this way, GaAs that is 100% single crystal
A semiconductor single crystal can be obtained.

When pulling the single crystal from the GaAs melt (9) as described above, by gradually increasing the rotation speed of the crucible (2) containing the melt, the pulling body and the melt (9) The shape of the solid-liquid interface (10) is stable, and the temperature in the melt can be kept constant. As a result, the single crystallized region of the pulling body is increased, and a high quality GaAs semiconductor single crystal can be obtained. FIG. 3 shows the results obtained by continuously pulling 20 GaAs single crystals by the conventional pulling method and the pulling method of the present invention. According to this, in the conventional method, the lot having a good single crystallization rate was 80%, and the lot having a bad single crystallization rate was 30%, and the average single crystallization rate was 57%. On the other hand, in the pulling according to the present invention, most lots have 100% single crystallized regions, and even in the bad lots, 60%, so that a higher quality GaAs semiconductor single crystal can be obtained by the pulling method according to the present invention. You can see that you can.

In this embodiment, the length of the single crystal is 40 mm from the seed crystal.
When the length is shorter than about a certain amount, the melt (9) in the crucible (2) is large and there is no temperature unevenness, so the crucible (2) and the pulling shaft (6) are pulled single crystals at a constant rotation. However, if the amount of pull-up is different, the timing of increasing the relative rotational speed is determined according to the amount. The same applies when the relative rotation number of the crucible (2) and the pull-up shaft (6) is increased for removal from the initial stage of pulling. In this embodiment, in order to increase the relative rotation speed, only the rotation speed of the crucible (2) is increased in consideration of workability, but the rotation speed of the pulling shaft rotating in the opposite direction is increased. Good.

[Effects of the Invention] When the compound semiconductor single crystal is pulled as described above in detail, the relative rotational speed between the crucible and the pulling shaft is changed with the increase of the pulling amount and the decrease of the melt amount. Since the amount is increased, the shape of the solid-liquid interface is stabilized, and the temperature unevenness in the melt is eliminated. Therefore, a high quality compound semiconductor single crystal having a high single crystallization ratio can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pulling apparatus for a compound semiconductor single crystal, FIG. 2 is a diagram showing a relationship between a single crystal length and a relative rotation number of a crucible and a pulling shaft, showing an embodiment of the present invention, and FIG. It is a result figure showing the crystallization ratio when pulling up by a conventional example and an example. 1 ...... high pressure vessel, 2 ...... crucible, 3 ...... inert gas, 4 ...... liquid sealant _{(B 2 O 3), 5} ...... GaAs single crystal, 6 ...... pulling member, 7 ...... heating Container, 8 ... Insulating cylinder, 9 ... GaAs melt, 10 ... Solid-liquid interface part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Sho 59-13480 (JP, B2) Sho 53-29677 (JP, B2) Sho 57-27077 (JP, B2)

Claims (1)

[Claims] 1. A step of introducing a compound semiconductor raw material and a liquid sealant into a crucible in a high-pressure container, a step of pressurizing the inside of the high-pressure container with an inert gas, and heating the inside of the pressurized high-pressure container. And the step of melting the compound semiconductor raw material, the pulling shaft provided through the high-pressure container and the crucible are respectively rotated in opposite directions, and the relative rotation speeds of both are sequentially increased while the crucible inside the crucible is increased. And a step of pulling a single crystal from a compound semiconductor solution.