JPS5819638B2 - Silicon gallium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a gallium arsenide single crystal using a boat growth method, which enables doping with impurities other than silicon over a wide range of concentrations, and produces a single crystal with a low dislocation density. This provides a useful method that can be used to

First, a typical example of a conventional method for producing gallium arsenide will be given, and its problems will be described.

FIG. 1 is a diagram showing the configuration of a so-called two-temperature horizontal Bridgman method crystal growth furnace, a temperature distribution diagram in the furnace, and a crystal growth container.

The horizontal axis shows the position inside the growth furnace, and the vertical axis shows the temperature inside the furnace.

Temperatures T, , T3 are respectively T1 = 1250° - 1270
℃.

T3=605°-620°C.

Also, Tm is the melting point of gallium arsenide, which is approximately Tm = 123
It is 8℃.

In FIG. 1, 1 is a high-purity quartz container containing a high-purity quartz boat 6 that holds a gallium arsenide melt 2;
3 is a small amount of grown gallium arsenide single crystal or a high purity gallium arsenide seed crystal, and 4 is excess arsenic for controlling the vapor pressure of arsenic (As).

7 and 9 schematically show an electric furnace divided into a high temperature heating section A and a low temperature heating section C.

The quartz container 1 is sealed in advance in a high vacuum of 10-5 mHg or less, but when the container reaches a steady state after being inserted into the furnace, the container is filled with arsenic vapor due to the excess arsenic 4 and maintained at approximately 1 atm. dripping

In this state, gallium arsenide can be single crystallized by moving the electric furnace 7.9 to the left relative to the quartz container 1 at a speed of 5 to 50 m/hr.

Here, a high temperature heating section (temperature Tt) and a low temperature heating section (temperature T3)
The temperature gradient G between ) is as large as 10 to 50°Ch.

Therefore, during the cooling process after solidification, a large temperature difference occurs in the longitudinal direction within the crystal.

When a humidity difference occurs, a difference in thermal expansion (difference in lattice constant) causes strain, and when the amount of strain exceeds the elastic limit of the crystal, plastic deformation occurs and dislocations are generated or multiplied.

In particular, just below the melting point of gallium arsenide, plastic deformation is likely to occur. Therefore, in this method where the humidity gradient G is large just below the melting point, the dislocation density increases, and even crystals with a small cross-sectional area (5 cm or less) are usually 2X103crrl. -2 or more.

If the cross-sectional area is 10cm/unit, it exceeds 1×104crrl-2.

It is also known that the following reaction occurs between gallium arsenide melt (including doped silicon) and quartz boats.

4Ga (in GaAs melt) + 5i02 (solid) = 2G
a20 (gas) + s i・one song −・(1) Si+5i0
2 (solid) -2SiO (gas) (2
)3Ga20 (gas) + A s 4 (gas) -〇a20
a (solid) + 40aAs (solid)
・・・・・・・・・(3) SiO (gas) = SiO(
(solid) ・・・・・・・・・(4) When considering trace amounts of silicon contamination, mainly equation (1) and (
Three components contribute to the reaction.

Gallium monoxide (Ga20) vapor diffuses from the high-temperature heating section to the low-temperature heating section and is condensed by the reaction of equation (3), resulting in a decrease in PGa2o.

When PGa2o decreases, the reaction of equation (1) proceeds to the right, and so-called "wetting" in which the melt and the quartz boat react progresses.

As a result, good quality single crystals cannot be obtained. The present invention solves the above-mentioned difficulties and reduces the residual silicon concentration of the grown gallium arsenide single crystal to about 2 x 1015Crrl-3 or less, and the concentration of impurities to be doped other than silicon to about 3 x 1015C.
It is an object of the present invention to provide a manufacturing method that can control the Wl-3 to 5 x 1019 cm-3 and make it possible to reduce the dislocation density to about 2 x 10'' cm-2 or less.

The present invention is an improved method of the two-humidity horizontal Bridgman method.

The three-temperature horizontal bridge method previously proposed by the present applicant (see Japanese Patent Publication No. 48-35861) is as follows: ℃ intermediate temperature heating section and a low humidity heating section that heats the vapor pressure of arsenic to approximately 1 atm; (b) A quartz boat is used as a boat to accommodate gallium arsenide, and the quartz boat is accommodated. A sealed container is installed between the chamber housing the boat, the chamber housing the arsenic, and the chambers, allowing the flow of arsenic vapor, but preventing the diffusion of gallium oxide or silicon oxide vapor. (c) on the distance between the boundary between the pore and the arsenic storage chamber and the lowest temperature position of the intermediate temperature heating section;

) is approximately equal to or longer than the total length (Ll) of the boat, and (d) silicon or a non-oxide compound containing silicon, an impurity other than silicon to be doped,
And in the method of manufacturing by adding oxygen or oxides (including raw material oxides) into the sealed container, the temperature of the intermediate temperature heating section is set to 1100'-1200°C, and the temperature of the intermediate temperature heating section and the intermediate temperature By setting the humidity gradient G (Fig. 2) between the heating section and the heating section to about 2 to 10 VCrn and the crystal growth rate to about 2 to 10 mm/hour, the residual silicon concentration in the single crystal can be reduced to about 2×. 1015Cnl-3 or less, the concentration of impurities to be doped other than silicon is approximately 3×10Cr
A method for producing a gallium arsenide single crystal doped with an impurity other than silicon and having a low dislocation density, which is characterized by controlling the dislocation density to be within the range of rl to 5×1019crrl-3 and making the dislocation density less than about 2×10”z”. It provides:

According to the present invention, the cross-sectional area of the single crystal is 5c77f (diameter 35
mm) or more, a gallium arsenide single crystal doped with impurities other than silicon and having a low dislocation density can be produced.

As mentioned above, in the conventional method, the cross-sectional area is 5c4 (diameter 35m
Even in a GaAs crystal with a small cross section of less than 2 m semicircle, the dislocation density is 2.
×1O-3Crn-2 or more, and the cross-sectional area is 10 crrt (
I x 10'cm-2
Only GaAs crystals with dislocation densities above the above have been obtained.

As will be described later, GaAs crystals are generally grown in the (111) direction, so a cross-sectional area of 5 crA corresponds to a (100) cross-sectional area of about 9 cm, and a cross-sectional area of 10 cd corresponds to a (100) cross-sectional area of about 15 cd.

Also T, S, Plaskett et al, The
Effect of Growth
tation on the Crystal P
Erfection of Ho-rizontal
Bridgman Grown GaAs,”
Journal of Electrochemi
cal 5o-city, Jan, (1971)
PP, 115-117. According to , only crystals grown in the <013> direction have a dislocation density of about 1000 Crrl-2 even in a small semicircular crystal with a diameter of about 15 mm (cross-sectional area 0.9tyA).
It is said that it became below.

On the other hand, according to the present invention, the cross-sectional area is 5 cm-2 (diameter 3 cm-2).
Even in a large-area GaAs crystal with a diameter of 5 mm or more (a semicircle of 5 mm), the dislocation density can be reduced to 2×10 3 Crn-2 or less with good reproducibility.

Furthermore, in the present invention, after the single crystal has finished growing and the entire single crystal has been placed in the intermediate temperature heating section, it is appropriate to stop the crystal growth furnace and lower the temperature of the furnace for slow cooling. .

The present invention will be explained in detail below using examples.

Example 1 Figure 2 shows a configuration diagram of a three-temperature horizontal Bridgman method crystal growth furnace, a temperature distribution diagram in the furnace, and a crystal growth container for manufacturing gallium arsenide single crystals according to an example of the present invention. FIG.

The horizontal axis shows the position inside the growth furnace, and the vertical axis shows the temperature inside the furnace.

Temperature T1. T2. T3 is T1=1245°−1 respectively
270°C, T2=1100°-1200°C, T3=60
5°-620°C, especially 610°C.

However, if the amount of excess arsenic 4 is extremely small, T3 becomes T2
Since the vapor pressure of arsenic is approximately 1 atm even when heated to a certain degree, the C furnace can be omitted in some cases.

In FIG. 2, 1 is a high-purity quartz container containing a high-purity quartz boat 6 that holds a gallium arsenide melt 2;
3 is a small amount of grown gallium arsenide single crystal and a high purity or silicon-doped gallium arsenide seed crystal, and 4 is excess arsenic for controlling the vapor pressure of arsenic (As).

Quartz boat 6 is shown in its simplest form, but when using seed crystals to perform so-called seeding, see Takashi Suzuki, “Production and Problems of Compound Semiconductors,” Lecture Sponsored by the Japan Economist Center. Materials, October 20th-10th
A thin seed crystal can be placed on the shelf of a so-called shelf boat, which has been adopted since it was published in May 21, 1970, PP, 1-16.

Reference numeral 5 denotes a pore, which allows the flow of arsenic vapor, but serves to inhibit the diffusion of gallium oxide and silicon oxide vapor.

7, 8 and 9 schematically show an electric furnace divided into a high temperature heating section A1, an intermediate temperature heating section B, and a low temperature heating section C, respectively.

Further, G is the temperature gradient between the high wetness heating section A and the intermediate temperature heating section B, which was approximately 2 to 10°C Δ.

Inside boat 6, gallium (purity 99.9999%) was initially
) and 15mgr of high purity silicon.

and 800mgr of high-purity tellurium are stored in the low humidity part of the quartz container 1.
) and 50 mgr of high purity arsenic trioxide (As203).

After connecting the molten gallium arsenide produced in the boat 6 and the silicon-doped gallium arsenide seed crystal having the (111) As direction in the longitudinal direction of the boat 6, the electric furnace t is placed.

8.9 to the left relative to the quartz container 1 by about 2~
It was moved at a speed of 10 mm/hour.

After all the molten gallium arsenide crystals have solidified, 30~b Rejected.

In this way, a large and long gallium arsenide single crystal with a cross-sectional area of 6 to 10 cm (100 cm) and a length of about 30 to 40 cm is obtained, and the boat side of this crystal is The gloss was very good, and no trace of "wetting" between the boat and the melt could be discerned.

In addition, in order to obtain a high quality crystal over the entire length of the crystal, the second
In the figure, it was necessary to set L2≧L1.

Also, the ratio of the temperature gradient G (2 to 10 C/l, *) and the crystal growth rate R (2 to 10 mm/hour), so-called G/R, is LO
It is desirable that it be larger than G, hour/1yrt':z)□
G≧10℃? 772. R210mm7 o'clock, G/R≦1
0℃.

In the case of 2 o'clock/C shoulder, low dislocation density G with a cross section of 5c shoulder or higher
aAs crystals are difficult to obtain.

The (111) Ga plane perpendicular to the longitudinal direction of this crystal is 3H2
Using S04:lH2O□:lH2O, about 10
The bundle was etched for minutes and the etch pit density was measured.
It was found that the dislocation density was approximately 1000 cm-2 at the tip of the crystal and approximately 1500 cm-2 at the rear end.

Furthermore, when the (100) plane of this crystal was etched with molten KOH for about 8 minutes and the etch pit density was measured, very similar results were obtained.

Furthermore, as a result of measuring the Hall coefficient of this crystal by the van der Para method, the carrier concentration at 295° was 1 x 1018 CrrI-3 at the tip and 3 x 10 at the rear end.
It turned out to be 18 cm.

As a result of mass spectrometry, the silicon concentration is approximately 1 x 1015 m
Met.

Example 2 A manufacturing method similar to Example 1 was adopted.

However, instead of the high-purity tellurium in Example 1, 400 mg of high-purity chromium was stored in the boat 6.

The obtained results show that the dislocation density is approximately 1200 at the tip of the crystal.
cm-2, and approximately 1600 CWl'' at the rear end.

Also, the specific electrical resistivity at 295° is 1 throughout the crystal.
A semi-insulating gallium arsenide single crystal of 0.06 ohm-tm or higher was obtained.

As a result of mass spectrometry, the chromium concentration is approximately 4 x 1015 cm-
3. The silicon concentration was approximately 1×10 15 Crrl-3, and the oxygen concentration was approximately 1×10 17 Crrl-3.

The effects of Examples 1 and 2 are explained as follows.

■ Temperature gradient G between high temperature heating section and low temperature heating section is 2 to 10
°G is small compared to the conventional method, so the temperature difference in the longitudinal direction within the crystal is small during the cooling process after solidification, and the growth rate is small at 2 to 10 W/hour, so the temperature difference in the radial direction within the crystal is small. Since the temperature is also small, thermal strain is small and dislocations do not occur or multiply.

(2) Since the cooling rate after solidification is as low as approximately 0°C/hour, the temperature difference in the 9'+ part of the crystal is small, so there is little thermal strain and no dislocations occur or multiply.G).

(1) The vapor of gallium monoxide (Ga 2Q) in formula (1) does not condense because the temperature T2 of the intermediate temperature heating section is as high as 1100°-1200°C.

That is, (because the ternary does not proceed to the right, no decrease in PGa2o occurs.

As a result, equation (g) does not proceed to the right, so it is considered that "wetting" does not occur.

Figure 3 shows the role of this intermediate watershed zone.

FIG. 3 is a diagram explaining the range in which the concentration of residual silicon in gallium arsenide can be controlled by the present invention. The activity of silicon in the liquid (aSi) is shown, and the vertical axis on the right is the concentration N of residual silicon in the obtained crystal.
・It shows S.

The straight line 10-a in the figure is (42), and the straight line 10-b is (3)
It shows the equilibrium relationship of Eq.

To control the residual silicon concentration, T2 must be 1045°C<
It is necessary that T 2 (yx −p −) be in the range of 1050°C <T
2. It was necessary that the temperature be 1200℃.

In particular, in order to obtain a high quality single crystal in which the residual silicon concentration Nsi in the crystal is approximately 2.times.10@15 cm@-3 or less according to the present invention, it is found that the temperature T2 must be approximately 1100'-1200 DEG C.

In addition to the tellurium (Te) and chromium (Cr) mentioned in the Examples, the method of the present invention can also be used as impurities to be doped.
Zinc (Zn), tin (Sn), cadmium (Cd),
It can also be applied to doping with iron (Fe), C, etc.

As detailed above, the method of the present invention reduces the residual silicon concentration in the crystal to approximately 2×10 15 Cr in the production of a gallium arsenide single crystal doped with impurities other than silicon.
l-3 or less, the concentration of impurities to be doped other than silicon can be controlled over the range of about 3 x 10'5 cm'' to 5 x 1019 cm-3, and the dislocation density can be controlled to about 2 x 103 c.
The purpose is to provide a method that can reduce the amount of energy to less than m-2.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a configuration diagram of a crystal growth furnace, a temperature distribution diagram in the furnace, and a crystal growth container when manufacturing gallium arsenide crystals by a conventional method. FIG. 2 is a diagram showing a configuration diagram of a crystal growth furnace, a temperature distribution diagram in the furnace, and a crystal growth container when producing gallium arsenide crystals according to an embodiment of the present invention. FIG. 3 is a diagram illustrating the range in which the concentration of residual silicon in gallium arsenide can be controlled by the present invention. In the figure, 1 is a quartz container, 2 is a gallium arsenide melt,
3 is crystallized gallium arsenide, 4 is excess arsenic, 5 is a pore section, 6 is a quartz boat, 7 is a high temperature heating section, 8 is an intermediate temperature heating section, and 9 is a low humidity heating section.

Claims (1)

[Claims] 1. A gallium arsenide single crystal is grown using the three-humidity horizontal Bridgman method: It is equipped with an intermediate-temperature heating section and a low-temperature heating section that heats the vapor pressure of arsenic to approximately 1 atm; (b) A quartz boat is used as a boat for accommodating gallium arsenide, and a sealed vessel for accommodating the quartz boat is provided. A container is provided between the chamber containing the boat and the chamber containing arsenic, which allows the flow of arsenic vapor, but prevents the diffusion of gallium oxide and silicon oxide vapor. (c) The law L 2 ) between the boundary line of the pore with the arsenic storage chamber and the lowest -r=1 position of the intermediate temperature heating section is defined as the total length of the boat. (L,) approximately equal to or longer than (d) silicon or a non-oxide compound containing silicon in the boat, an impurity to be doped other than silicon;
And in the method of manufacturing by adding oxygen or oxides (including raw material oxides) into the sealed container, the temperature of the intermediate humidity heating section is set to 1100° to 1200°C, and the temperature of the intermediate humidity heating section and the intermediate temperature By setting the temperature gradient G (Fig. 2) between the heating part and the heating part to about 2 to 10 C/lyn and the crystal growth rate 4 to about 2 to 10 m/hour, the residual silicon concentration in the single crystal can be reduced to about 2 to 10 m/hour. 2 x 1015 cm" or less, the concentration of impurities to be doped other than silicon is approximately 3 x 10 C.
A method for producing a gallium arsenide single crystal doped with an impurity other than silicon and having a low dislocation density, characterized by controlling n1 to 5 x 1019 cm-3 and making the dislocation density less than about 2 x 103 cm''. .