JPH07257988A - Method for growing ternary compound semiconductor crystal - Google Patents

Abstract

PURPOSE:To control effect due to lattice discrepancy of a seed crystal with a growing crystal and obtain a high-quality ternary compd. semiconductor crystal almost free from defects. CONSTITUTION:A binary seed crystal 4 consisting of elements A and B is brought into contact with a binary melt 3 consisting of the same elements A and B as the seed crystal 4 and then the seed crystal 4 is pulled up while feeding a binary compd. semiconductor CB consisting of elements B and C into the melt 3 to grow the objective ternary compd. semiconductor crystal 6 consisting of the elements A, B and C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal growth method for a ternary compound semiconductor, and more particularly to a crystal growth method for a ternary compound semiconductor using the CZ (Czochralski) method.

Conventionally, in manufacturing a compound semiconductor device, a binary crystal is used as a substrate on which a crystal layer of a compound semiconductor of two or more elements (for example, a ternary compound semiconductor crystal layer) is grown. It had been. However, since there is a problem of lattice mismatch due to the difference in lattice constant between the binary substrate and the ternary crystal, it is necessary to form a growth layer between the two to ensure lattice matching. The formation of this growth layer causes an increase in the cost of manufacturing the compound semiconductor device.

Therefore, a ternary compound semiconductor substrate is needed to avoid the formation of a growth layer required between the binary substrate and the ternary crystal. Because of this, CZ
A method of growing a ternary compound semiconductor crystal by using the (Czochralski) method and producing a ternary compound semiconductor substrate from the grown crystal has been performed. There was a defect due to the lattice mismatch of the. Therefore, in order to manufacture a high quality ternary compound semiconductor substrate, it is necessary to suppress the influence of lattice mismatch.

[0004]

2. Description of the Related Art FIG. 4 is a diagram showing a conventional example, and is a diagram showing a configuration of a crystal pulling growth apparatus for a ternary compound semiconductor which has been used conventionally.

In the figure, 11 is a crucible, 12 is a crucible rotating means for rotating the crucible 11, 13 is a melt of a semiconductor raw material,
Reference numeral 14 is a seed crystal, 15 is a crystal pulling means for bringing the seed crystal 14 into contact with the melt 13 and pulling the crystal of the ternary compound semiconductor while rotating, and 16 is a growing ternary compound semiconductor crystal.

A method for growing a crystal of a ternary compound semiconductor using the crystal pulling and growing apparatus shown in FIG. 4 will be described below. The case where InGaAs is crystal-grown as a ternary compound semiconductor is taken as an example.

First, a mixed melt of GaAs and InAs (ternary melt) is used for the melt 13, and Ga is used for the seed crystal 14.
A single crystal of As is used. InGaAs crystal growth is
The temperature of the solid-liquid interface between the crystal 16 and the melt 13 is gradually cooled according to the temperature profile calculated from the phase diagram, and the seed crystal 14 is immersed in the melt 13 and pulled up using the crystal pulling means 15. .

[0008]

FIG. 5 is a diagram showing an outline of the composition distribution in the crystal according to the conventional example, in which a GaAs single crystal is used as a seed crystal and the pulling growth apparatus shown in FIG. 4 is used. the change in the value of the composition x of in grown crystal _{in x Ga (1-x)} as is a diagram depicting relative changes in the distance from the seed crystal.

From FIG. 5, the seed crystal of the GaAs single crystal (se
The value of the composition x of In in ed) is naturally 0, but it is a grown crystal (bulk) of In _x Ga _(1-x) As.
The value of the composition x of In in the inside rapidly rises from 0 to 0.03 at the interface between the seed crystal (seed) and the grown crystal (bulk), and within the grown crystal (bulk), a constant value 0.03 is obtained. You can see that it is kept at.

In the conventional ternary compound semiconductor crystal growth method, since the ternary melt is used from the start of crystal growth,
As shown in FIG. 5, a step difference in composition occurs at the interface between the seed crystal (seed) and the growing crystal (bulk). As a result, there is a problem in that strain is generated due to the lattice mismatch between the seed crystal and the grown crystal, and defects are likely to be introduced into the grown crystal.

The present invention solves the above problems and suppresses the influence due to the lattice mismatch between the seed crystal and the growing crystal to obtain a good quality ternary compound semiconductor crystal with few defects. It is an object of the present invention to provide a crystal growth method of a ternary compound semiconductor, particularly a crystal growth method of a ternary compound semiconductor using the CZ (Czochralski) method.

[0012]

In order to achieve the above object, the ternary compound semiconductor crystal growth method according to the present invention is configured as follows.

(1) A ternary compound semiconductor crystal using the Czochralski method in which a seed crystal is brought into contact with a melt of a semiconductor raw material in a crucible and then the seed crystal is pulled to grow the semiconductor crystal. A growth method, wherein a binary seed crystal containing a first element and a second element is contacted with a binary melt containing the same first element and a second element as the binary seed crystal. And then the second element and the third element are added to the melt.
The seed crystal is pulled up while supplying the original compound semiconductor, and is composed of the first element, the second element, and the third element.
It is configured to grow an original compound semiconductor crystal.

(2) A ternary compound semiconductor crystal using the Czochralski method in which a seed crystal is brought into contact with a melt of a semiconductor raw material in a crucible and then the crystal is grown by pulling the seed crystal. A growth method, wherein a binary seed crystal containing a first element and a second element is contacted with a binary melt containing the same first element and a second element as the binary seed crystal. After that, while feeding the ternary compound semiconductor composed of the first element, the second element, and the third element into the melt, the seed crystal is pulled up, and the first element and the second element are added. A ternary compound semiconductor crystal composed of the third element is grown.

(3) In the above (1) or (2),
After the composition of the grown ternary compound semiconductor reaches a predetermined value, a ternary compound semiconductor crystal is grown while replenishing the melt with a binary compound semiconductor composed of a first element and a second element. To configure.

(4) In one of the above (1) to (3), the first element and the third element are group III elements, and the second element is a group V element. To do.

(5) In one of the above (1) to (3), the first element is Ga, the second element is As, and the third element is In.

[0018]

In the following, in order to avoid complication, the first element, the second element, and the third element used in the "means for solving the problem" are replaced by element A, element B, and And element C will be described.

In the present invention, the melt at the start of crystal growth is a binary melt having the same composition AB as the seed crystal AB, and a binary source having a composition CB containing another element C is supplied during the crystal growth. The composition of the melt is gradually changed. As a result, it becomes possible to grow a ternary compound semiconductor crystal having a continuous composition gradient in the initial stage of crystal growth.

That is, in the present invention, a melt having a composition of AB is replenished with a binary source having a composition of CB,
By gradually changing the composition value x of the element C of the ternary melt C _x A _(1-x) B during crystal growth from 0 to a predetermined value x _t , a binary seed crystal having a composition of AB can be obtained. Predetermined composition C
up to a ternary compound semiconductor crystal with x _t A _(1- x _t) B,
The composition value x of the element C can have a continuous gradient.

As a result, since the lattice constant also changes continuously, it becomes possible to suppress the generation of defects due to the lattice mismatch at the interface between the seed crystal and the growing ternary compound semiconductor crystal. It is possible to obtain a few good quality ternary compound semiconductor crystals.

Further, the melt at the start of crystal growth is used as a seed crystal AB.
A binary melt having the same composition AB as
The composition of the melt may be gradually changed by replenishing a ternary source having a composition of B. By doing this,
It is possible to mitigate various effects caused by heat.

Further, the melt at the start of crystal growth is used as a seed crystal A.
A binary melt of the same composition AB as B was prepared, and during the crystal growth,
A binary source having a composition of CB or a ternary source having a composition of CAB is replenished to gradually change the composition of the melt, and crystal growth of the ternary compound semiconductor CAB is performed. After reaching the value of element A
There is also a method of replenishing the binary compound semiconductor AB composed of the element B and the element B. This makes it possible to grow crystals of the ternary compound semiconductor CAB having a uniform composition in the pulling direction.

[0024]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, and is a diagram showing the configuration of a crystal pulling growth apparatus for a ternary compound semiconductor used for implementing the present invention.

In the figure, 1 is a crucible, 2 is a crucible rotating means for rotating the crucible 1, 3 is a melt of a semiconductor raw material, 4 is a seed crystal, and 5 is a seed crystal 4 which is brought into contact with the melt 3 and rotated. While pulling crystal of ternary compound semiconductor, 6
Is a growing ternary compound semiconductor crystal, 7 is a replenishing source, and 8 is a source feeding means for feeding the source 7 into the melt 3.

A method for growing a crystal of a ternary compound semiconductor using the crystal pulling and growing apparatus shown in FIG. 1 will be described below. InGaAs was grown as a ternary compound semiconductor.

First, Ga is placed in the crucible 1 having an inner diameter of 80 mmφ.
As118 g was put and the temperature of the furnace was heated to 1500 ° C. to prepare a GaAs melt 3. Next, set the furnace temperature to 1430
After the temperature is lowered to ℃, the GaAs seed crystal 4 fixed to the crystal pulling means 5 is brought into contact with the GaAs melt 3 and the temperature of the furnace is gradually cooled while the crystal pulling means 5 is moved to 2 mm / h.
The diameter of the crystal 6 was gradually increased by pulling up at a speed of.

When the diameter of the crystal 6 reaches 15 mmφ,
InA with a cross-sectional area of 9 mm □ fixed to the source feeding means 8
The s source 7 is fed into the melt 3 at a rate of 4.4 mm / h, and the InGaAs crystal 6 is grown while being gradually cooled (eg, 4.4 ° C./h) according to the temperature profile calculated from the phase diagram. It was

FIG. 2 is a diagram showing an outline of the composition change of the melt during the growth according to one embodiment of the present invention, which is performed by the crystal growth method of the ternary compound semiconductor according to the present invention described above.
_{n x Ga (1-x)} As In in the melt during crystal growth
The state of change of the composition value x with respect to the elapsed time is shown. From FIG. 2, it can be seen that the In composition value x in the melt gradually increases from 0 with the passage of time.

FIG. 3 shows the inside of a crystal according to an embodiment of the present invention.
It is a figure showing the outline of composition distribution, and it is related with the above-mentioned present invention.
The crystal was grown by the crystal growth method of the ternary compound semiconductor.
In _xGa_(1-x)I in the bulk of As
The composition value x of n is the distance from the interface with the seed crystal (seed).
Is plotted against. From FIG. 3, In_xG
a_(1-x)The composition value x of In in the As crystal (bulk) is
From 0 as the distance from the interface with the seed crystal increases
Increasing gradually, In produced by the conventional method_xGa
_(1-x)Unlike As crystals, seed crystals and In
_xGa_(1-x)I at the interface with the As crystal (bulk)
It can be seen that there is no step in the composition value x of n.

As described above, since the ternary compound semiconductor crystal produced by the method for growing a ternary compound semiconductor crystal according to the present invention has no compositional step at the interface with the seed crystal, the lattice constant is not matched. Occurrence of defects resulting from this is suppressed. As a result, according to the present invention, a good quality ternary compound semiconductor crystal can be obtained.

In the above-described embodiment, an example of crystal growth of InGaAs using a GaAs seed crystal has been shown, but the present invention is not limited to this, and In, Ga, As, and P are used.
Using a binary seed crystal composed of a group III-V compound semiconductor selected from the group III and V groups such as
It can be applied to the growth of any ternary compound semiconductor crystal selected from group III and group V such as a, As, and P.

[0033]

In the crystal growth method for a ternary compound semiconductor according to the present invention, a binary compound semiconductor containing other elements is replenished in the binary melt while pulling up the crystal growth to obtain a binary seed. Since it is possible to continuously change the composition between the crystal and the pulled ternary compound semiconductor crystal, it is possible to suppress the occurrence of defects due to the abrupt change in the composition.

As a result, according to the present invention, a good quality ternary compound semiconductor crystal can be obtained. In addition, the ternary compound semiconductor prepared by the method of crystal growth of the present invention 3
Since a ternary compound semiconductor substrate can be obtained directly from the original compound semiconductor crystal, a high-performance compound semiconductor device can be manufactured using this.

As described above, the present invention largely contributes to the performance improvement of the compound semiconductor device.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a change in composition of a melt during growth according to an example of the present invention.

FIG. 3 is a diagram showing an outline of a composition distribution in a crystal according to an example of the present invention.

FIG. 4 is a diagram showing a conventional example.

FIG. 5 is a diagram showing an outline of a composition distribution in a crystal according to a conventional example.

[Explanation of symbols]

 1 Crucible 2 Crucible Rotating Means 3 Melt 4 Seed Crystal 5 Crystal Pulling Means 6 Crystals 7 Replenishing Source 8 Source Injecting Means

Claims (5)

[Claims] 1. Crystal growth of a ternary compound semiconductor using the Czochralski method in which a seed crystal is brought into contact with a melt of a semiconductor raw material in a crucible and then the crystal is grown by pulling the seed crystal. The method comprises contacting a binary seed crystal composed of a first element and a second element with a binary melt composed of a first element and a second element which is the same as the binary seed crystal. Then, while feeding the binary compound semiconductor composed of the second element and the third element into the melt, the seed crystal is pulled up to separate the first element, the second element and the third element. A method for growing a crystal of a ternary compound semiconductor, comprising: 2. Crystal growth of a ternary compound semiconductor using the Czochralski method in which a seed crystal is brought into contact with a melt of a semiconductor raw material in a crucible and then the crystal is grown by pulling the seed crystal. The method comprises contacting a binary seed crystal composed of a first element and a second element with a binary melt composed of a first element and a second element which is the same as the binary seed crystal. After that, while feeding the ternary compound semiconductor composed of the first element, the second element, and the third element into the melt, the seed crystal is pulled up, and the first element, the second element, and the A method for growing a crystal of a ternary compound semiconductor, which comprises growing a ternary compound semiconductor crystal composed of 3 elements. 3. The grown 3 according to claim 1 or 2.
Characteristic of growing a ternary compound semiconductor crystal while supplying a binary compound semiconductor composed of a first element and a second element into a melt after the composition of the original compound semiconductor reaches a predetermined value And a method for growing a crystal of a ternary compound semiconductor. 4. The ternary element according to claim 1, wherein the first element and the third element are group III elements and the second element is a group V element. Crystal growth method of compound semiconductor. 5. The method according to claim 1, wherein the first element is Ga, the second element is As, and the third element is In.
A method for growing a crystal of a ternary compound semiconductor, comprising: