JPH0722323A - Vapor deposition device - Google Patents

Abstract

PURPOSE:To produce the multi-element semiconductor crystal having excellent evenness in the title vapor deposition device comprising a vertical reaction tube for compound semiconductor. CONSTITUTION:This vapor deposition device comprising vertical reaction tube having three each of gas leading-in ports 4, 5, 6 assuming the two 5, 6 of the three as the material gas introducing ports is provided with two each of conic material gas blowing-out ports (horns 7, 8) on the axis of the center of a reaction tube 1 concentrically as well as a gas diffusion bar 10 on the central part of the inner side blowing-out port (horn 7). Through these procedures, the concentration of the material gas in the central part during the low pressure growing step can be avoided by the gas diffusion bar 10. Furthermore, the length and thickness of the gas diffusion bar 10 can be arbitrarily changed thereby enabling the flow of the material gas to be arbitrarily adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase growth apparatus,
In particular, it relates to a vapor phase growth apparatus used for crystal growth of a compound semiconductor or the like using an organic metal.

[0002]

2. Description of the Related Art Various proposals have been made so far for a vapor phase growth apparatus used for crystal growth of a compound semiconductor or the like. As an example thereof, the vapor phase growth apparatus described in Japanese Patent Laid-Open No. 4-177721 will be cited and described with reference to FIG.

FIG. 8 is a sectional view of a conventional vapor phase growth apparatus. In this apparatus, a susceptor 82 is arranged in a vertical reaction tube 81, a substrate 83 is placed on the susceptor 82, and This is a vapor phase growth apparatus for growing a crystal thin film on a substrate 83, and has the following configuration. A conical horn (A) 87 having the center of the reaction tube 81 as an axis is installed on the substrate 83, and the conical horn (A) 87 is installed.
A raw material gas introduction port (A) 85 for introducing gas is provided inside, and further outside the conical horn (A) 87, a conical shape having a concentric opening with the horn (A) 87. A horn (B) 88 is provided, and a raw material gas inlet (B) 86 for introducing gas is provided in the conical horn (B) 88. In addition, 84 in FIG. 8 is a carrier gas inlet.

Next, a conventional method of growing a compound semiconductor crystal on the substrate 83 using the vapor phase growth apparatus will be described. Hydrogen is introduced from a carrier gas inlet 84 located at the upper part of the reaction tube 81, and a raw material gas inlet (A) 85 and a raw material gas inlet (B)
A mixed gas of a group III raw material such as indium and a group V raw material of arsine and phosphine is introduced into 86 and supplied onto a substrate 83 placed on a susceptor 82, and a substrate 83 is heated by a heating system (not shown).
Are heated to grow a compound semiconductor crystal on the substrate 83.

Raw material gas inlet (A) 85 and raw material gas inlet
The raw material gas introduced from (B) 86 is supplied to the substrate 83 as uniformly as possible on the horn (A) 87 and the horn (B) 88.
Is diffused with a velocity distribution as shown by the dotted line in FIG. Usually, the crystal is grown by rotating the susceptor 82 so that the raw material is more uniformly supplied onto the substrate 83. In order to obtain a compound semiconductor crystal with a uniform film thickness, the flow rates of the raw material gas introduction ports (A) 85 and (B) 86 into which the gas of the same component is introduced are independently controlled by the flow rate control system.

[0006]

The above-mentioned conventional vapor phase growth apparatus is disclosed in Japanese Patent Laid-Open No. 4-177721, which uses phosphine (PH ₃ ) and arsine (AsH ₃ ) as the group V gas. Therefore, the vapor phase growth apparatus is intended for growing a plurality of types of compound semiconductor crystals such as phosphorus (P) -based and arsenic (As) -based.

Although not explicitly described in the above publication, in order to grow a p-type crystal having generally good crystallinity, the raw material gas introduction ports (A) 85 and (B) 86 are used. It is necessary to form a laminar gas flow without turbulence onto the substrate 83. Therefore, the internal pressure of the reaction tube 81 is reduced to 30 to 70 Torr to increase the gas flow velocity in the reaction tube 81, thereby forming a stable laminar flow state.

In such a depressurized state, the horn
(A) The velocity distribution of the gas in 87 cannot be diffused with the velocity distribution shown by the dotted line in FIG.
The raw material gas introduced from (A) 85 reaches the substrate 83 while being concentrated in the center without spreading along the horn (A) 87. Therefore, the supply amount distribution of the source gas on the substrate 83 becomes large in the central portion of the substrate and becomes smaller in the outer peripheral portion.

As a result, the film pressure at the central portion of the substrate 83 becomes thicker, and there arises a problem that the uniformity of the film thickness cannot be obtained. Moreover, when the source gas is concentratedly supplied to the central portion of the substrate 83, the temperature of the central portion of the substrate is lower than that of the peripheral portion, and a temperature distribution is generated on the substrate surface.

In the conventional vapor phase growth apparatus, since the temperature distribution is generated on the substrate surface as described above, a crystal having a lattice constant distribution in the radial direction of the substrate grows in a crystal requiring lattice matching. It has drawbacks. In addition,
"Having a distribution of lattice constants" means "having a composition distribution".

In addition, the doping characteristics also have a distribution in the radial direction of the substrate. In such a state, there is a drawback that the degree of freedom of the crystal growth condition is lowered, and consequently a device having uniform characteristics cannot be obtained with a high yield.

Further, in the vapor phase growth apparatus shown in FIG.
According to the above-mentioned Japanese Patent Laid-Open No. 4-177721, it is described that "group V raw material and group III raw material are mixed and fed". When such a feeding means is adopted, the group V raw material and the group III raw material are mixed. There is also a problem that a good quality semiconductor crystal cannot be obtained because an intermediate reaction may occur depending on the kind.

The present invention has a technical object to solve the above problems and drawbacks in the conventional vapor phase growth apparatus, and in particular, a multi-element semiconductor crystal can be uniformly grown on a substrate. An object is to provide a vapor phase growth apparatus.

[0014]

According to the vapor phase growth apparatus of the present invention, (A) a group III source and a group V source are independently provided in two conical source gas outlets having the center of the reaction tube as an axis. (B) Of the two conical raw material gas outlets, a gas diffusion rod is provided at the center of the inner outlet end of the two conical source gas outlets, and (C) the two gas outlet ends. Of the above, the inner gas outlet end was moved away from the susceptor,
A vapor phase growth apparatus of the above-mentioned object is provided, which is characterized by having a structure.

That is, according to the present invention, "a susceptor is arranged in a vertical reaction tube having three gas inlets, two of which are raw material gas inlets, and a semiconductor substrate is mounted on the susceptor. Then, in the vapor phase growth apparatus for growing a semiconductor crystal on the substrate, two conical source gas outlets concentrically with the center of the reaction tube as an axis are provided, and the two source gas outlets The raw material gas blowing port on the inner side is separated from the susceptor, and a gas diffusion rod is arranged at the central portion of the opening end of the raw material gas blowing port on the inner side. " .

[0016]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a vapor phase growth apparatus which is an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

In the vapor phase growth apparatus shown in FIG. 1 (FIG. 2), a carbon susceptor 2 supported by a quartz tube 9 is arranged in a vertical quartz reaction tube 1, and a substrate 3 is placed on the susceptor 2. This is a vapor phase growth apparatus for mounting and growing a crystal thin film on the substrate 3, and two conical source gas outlets having the center of the reaction tube 1 as an axis, that is, a horn (A) 7 , (B) 8.

Of the horn (A) 7 and the horn (B) 8 having two concentric circular openings centered on the center of the reaction tube 1, the inner horn (A) 7 As for the distance between the open end and the substrate 3, as shown in FIG.
The quartz gas diffusion rod 10 supported by the horn (A) 7 is arranged at the center of the opening end of the horn (A) 7 inside the horn (A) 7.

Further, in the horn (A) 7 and the horn (B) 8,
A carrier gas introduction (A) 5 for introducing the raw material gas and a raw material gas introduction port (B) 6 are connected to each other, and a carrier gas for introducing only hydrogen (H ₂ ) gas is provided above the reaction tube 1. Mouth 4
Is arranged.

When a semiconductor crystal is grown on the substrate 3 by using the above vapor phase growth apparatus, arsine is introduced into the source gas introduction port (A) 5.
(AsH ₃ ), V group gas of phosphine (PH ₃ ) and silane (SiH ₄ )
Gas for the dopant is supplied. On the other hand, raw gas inlet
(B) 6 is fed with an organic metal as a Group III raw material and an organic metal for a dopant.

The susceptor 2 on which the substrate 3 is placed is rotated at a rotation speed of 10 to 20 rpm in order to improve the uniformity of the growing semiconductor crystal. The distance between the susceptor 2 and the horn (B) 8 is 600
In order to mitigate the effect of radiant heat from the susceptor 2 which is heated to ˜700 ° C., they are placed about 3.5 cm apart.

The diffusion rod 10 has a conical shape at both ends thereof, and is constructed so that the gas flow at the tip of the diffusion rod 10 becomes smooth. The tip of the diffusion rod 10 on the susceptor 2 side is 5 m from the end of the horn (B) 8 outlet.
m.

As shown in FIG. 2, the method for supporting the diffusing rod 10 is as follows. As shown in FIG. It is a structure that hangs and supports a notch 101 attached to. The diffusion rod 10 is removed by passing the notch 101 of the diffusion rod 10 through the notch.

In the vapor phase growth apparatus having the above structure, the group V source gas introduced from the source gas inlet (A) 5 is horn.
(A) Since the diffusion rod 10 is placed inside 7, this diffusion rod 1
0 forcefully spreads to the outer peripheral side of the reaction tube 1 and
(A) It is discharged in the width of the end of the outlet of 7. On the other hand, the group III raw material introduced from the raw material gas inlet (B) 6 is the horn (A)
After flowing to the lower end of 7, the group V raw material from the horn (A) 7 reaches the surface of the substrate 3.

While reaching the surface of the substrate 3, the group V raw material and III
Since the group raw materials diffuse into each other, II also appears in the center of the reaction tube 1.
The group I raw material wraps around and contributes to the growth of the central part of the substrate. The flow of raw material gas into the center of the substrate is
Since it occurs after the tip of the diffusion rod 10 on the substrate 3 side, the diffusion rod 10
It is possible to adjust the amount of raw material supplied to the center of the substrate, that is, the crystal growth rate, by adjusting the length. Therefore, the thickness distribution of the semiconductor crystal can be improved by adjusting the length of the diffusion rod 10.

(Example of Semiconductor Crystal Growth) Using a vapor phase growth apparatus having the above structure, a 2 inch GaAs (100) substrate (Al _X
A semiconductor crystal of Ga _1-x ) _0.5 In _0.5 P (x = 0.6) was grown.

The gas supply amount is as follows: H ₂ gas supplied from the carrier gas inlet 4: 2.5 SL
M, total amount of organic metal and carrier gas H ₂ gas supplied from gas inlet (B) 6: 2.5 SLM, V group raw material and H ₂ gas supplied from gas inlet (A) 5 Total amount of: 1.5 SLM.

The internal pressure of the reaction tube 1 is set to 30 Torr, and the growth temperature is
It was set to 650 ° C. Group III raw material is triethylgallium (TEG
a), trimethylaluminum (TMAl), and trimethylindium (TMIn) were used, and the flow rate ratio V / III = 400 of the group III and group V raw materials during crystal growth was set.

(Al _x Ga _{1 -x} ) _0.5 grown under the above conditions
Figure 3 shows the distribution of the growth rate of In _0.5 P crystals in the radial direction of the substrate.
Shown in. As is clear from FIG. 3, the distribution of growth rate is
It is within 5%.

When the lattice constant of the GaAs substrate is a ₀ and the lattice constant difference between the substrate and the grown semiconductor crystal is Δa, the distribution of the lattice matching degree Δa / a _{0 in} the radial direction of the substrate is shown in FIG. Shown in. As is clear from FIG. 4, the width of the distribution in the radial direction of the substrate is within 5 × 10 ^−4, which is a sufficient value in terms of device design.

Next, regarding the carrier concentration distribution, dimethyl zinc (DMZn) was used as the p-type dopant and was supplied from the source gas inlet (B) 6 together with the Group III source. on the other hand,
Silane (SiH ₄ ) was used as the n-type dopant and was supplied from the source gas introduction port (A) 5 together with the group V source material. The distribution in the radial direction of the substrate is shown in FIG. From Figure 5, 10% for both p-type and n-type
It has the following distribution.

(Manufacture of Semiconductor Laser) The semiconductor laser shown in FIG. 6 was manufactured using the vapor phase growth apparatus of the present invention. The structure of the semiconductor laser has the structure shown in FIG.
On the n-type GaAs (100) substrate 11, n-type GaAs buffer layer 12, n-type (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P cladding layer 13, and und Ga _0.5 In _0.5 P active layer 14, A type (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P clad layer 15, a p-type Ga _0.5 In _0.5 P layer 16, an n-type GaAs current blocking layer 17, were laminated by the first crystal growth.

Next, a resist mask is formed by the photolithography method, a stripe reaching the p-type Ga _0.5 In _0.5 P layer 16 is formed in the n-type GaAs current blocking layer 17, and then p-type GaAs is formed by the second crystal growth. Cap layer 18
Grew up. Subsequently, the electrodes 19 and 20 are formed, and the semiconductor laser is formed.
I made The.

FIG. 7 shows the distribution of the oscillation threshold current in the radial direction of the substrate of this semiconductor laser. As is apparent from FIG. 7, it can be understood that a semiconductor laser having a uniform oscillation threshold current is obtained from the center of the substrate to a radius of 20 mm.

In the above embodiments, an example of growing an AlGaInP based semiconductor crystal using the vapor phase growth apparatus of the present invention is described, but the same effect is obtained even in the case of other III-V group semiconductor crystals. Needless to say.

[0036]

As described above, in the vapor phase growth apparatus of the present invention, by introducing the group III source material and the group V source material into the reaction tube separately, the "flow rate control" which has been a concern in the conventional vapor phase growth apparatus. This has the effect of preventing the "intermediate reaction between the group III raw material and the group V raw material" between the system and the reaction tube.

Further, by providing the diffusion rod, it is possible to prevent the source gas from concentrating in the central portion of the semiconductor substrate, so that the temperature drop in the central portion of the substrate is almost eliminated, and the growth rate of the growing semiconductor crystal is reduced. The effect is that the inner distribution can be set to 5% or less, the in-plane distribution of the lattice matching degree can be set to 5 × 10 ⁻⁴ or less, and the carrier concentration distribution can be set to 10% or less.

The distribution of the oscillation threshold current of the AlGaInP type semiconductor laser manufactured by using the vapor phase growth apparatus of the present invention within the substrate surface is about 20 mm from the substrate center to a radius of about 20 mm.
The values are almost the same, and an effect that high-yield device manufacturing is possible is produced.

[Brief description of drawings]

FIG. 1 is a sectional view of a vapor phase growth apparatus that is an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view of growing a layer using the vapor phase growth apparatus of the present invention (Al
Distribution diagram of the growth rate of _0.6 Ga _0.4 ) _0.5 In _0.5 P in the radial direction of the substrate.

FIG. 4 is a plan view of growing a layer using the vapor phase growth apparatus of the present invention (Al
_0.6 Ga _0.4 ) _0.5 In _0.5 P lattice matching distribution in the radial direction of the substrate.

FIG. 5 shows the case of growing using the vapor phase growth apparatus of the present invention (Al
_0.6 Ga _0.4 ) _0.5 In _0.5 P p-type and n-type carrier concentration distribution diagram in the radial direction of the substrate.

FIG. 6 is a sectional view of a semiconductor laser grown by using the vapor phase growth apparatus of the present invention.

FIG. 7 is a diagram showing a distribution of an oscillation threshold current in a substrate radius direction of a semiconductor laser.

FIG. 8 is a sectional view of a conventional vapor phase growth apparatus.

[Explanation of symbols]

1, 81 Reaction tube 2, 82 Susceptor 3, 83 Substrate 4, 84 Carrier gas inlet 5,85 Raw material gas inlet (A) 6, 86 Raw material gas inlet (B) 7, 87 Horn (A) 8 , 88 horn (B) 9 Quartz tube 10 Gas diffusion rod 11 n-GaAs substrate 12 n-GaAs buffer layer 13 n- (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P Clad layer 14 And-Ga Ga _0.5 In _0.5 P Active layer 15 p- (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P clad layer 16 p-Ga _0.5 In _0.5 P layer 17 n-GaAs current blocking layer 18 p-GaAs cap layer 19 electrode 20 electrode 101 notch

[Procedure amendment]

[Submission date] June 1, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (1)

[Claims] 1. A susceptor is disposed in a vertical reaction tube having three gas introduction ports, two of which are source gas introduction ports, and a semiconductor substrate is placed on the susceptor, and the susceptor is placed on the substrate. In the vapor phase growth apparatus for growing a semiconductor crystal, two conical source gas outlets concentric with the center of the reaction tube as an axis are provided, and the source gas inside the two source gas outlets is provided. Keep the air outlet away from the susceptor,
A vapor phase growth apparatus characterized in that a gas diffusion rod is arranged at the center of the opening end of the raw material gas outlet inside this.