JP2743471B2 - (III)-Vapor phase growth apparatus for Group V compound semiconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for vapor-phase growth of a group III-V compound semiconductor. More specifically, the present invention relates to a group III element chloride and a group V source which are alternately supplied to each other. The present invention relates to a vapor phase epitaxial growth apparatus for a III-V compound semiconductor capable of controlling the growth film thickness in units of molecular layers.

[Prior art and its problems] In order to realize a structure such as a quantum well laser and a modulation doping structure of a group III-V compound semiconductor, it is necessary to establish an ultra-thin film crystal growth technique. In recent years, an atomic layer epitaxial (ALE) method of alternately supplying source gases of a group III element and a group V element has been performed as a new growth technique. This A
Since the LE method can precisely control the thickness of a single molecular layer unit, a steep hetero interface can be formed. The growth temperature is 400 ℃
Because of the following low values, it has advantages such as that the interdiffusion of atoms at the heterointerface is unlikely to occur.

In order to realize the ALE method, it is necessary to cut off and switch the source gas sharply. For example, the ALE method using chloride as a group III raw material is disclosed in Japanese Journal of Applied Physics (Jpn. J. Appl. Phys., 25, L2
12 (1986)).

FIG. 4 shows a schematic configuration diagram of an apparatus used for this method. Taking the growth of GaAs as an example, AsH ₃
Using a gas, hydrogen chloride (HCl) is supplied to a gallium (Ga) source 61 as a group III element raw material, and a reaction product (G
a + HCl → GaCl + 1 / 2H ₂ ) gallium chloride (GaCl) is used. In this method, a plurality of growth chambers 63a,
63b is provided to supply group III and group V element raw materials to separate growth chambers 63a and 63b.

The growth procedure is as follows. First, GaCl is adsorbed on the surface of the substrate crystal 65 in the growth chamber 63a. Next, the substrate moving mechanism 66
As a result, the substrate crystal 65 is moved to the growth chamber 63b to supply an AsH ₃ gas, thereby growing a monolayer of GaAs. This series of operations is repeated to form a predetermined film thickness.

As described above, the conventional ALE apparatus using chloride requires a reaction tube provided with a plurality of growth chambers for switching the source gas to the substrate crystal and a growth apparatus provided with a moving mechanism capable of moving the substrate crystal between the growth chambers. I am using it. For this reason, the growth apparatus has a drawback that it becomes huge and requires a complicated moving mechanism.

Further, AsH ₃ and PH ₃ are used as group V raw materials. Since these substances are very toxic, they require equipment with sufficient safety measures, exhaust gas treatment equipment, and the like.

The present invention eliminates the above-mentioned drawbacks of the prior art, has no complicated moving mechanism, can control the growth with a film thickness of a single molecular layer unit, and can use a low-toxic solid group V material to form a single molecule. It is an object of the present invention to provide an apparatus for vapor-phase growth of a group III-V compound semiconductor in which growth can be controlled by the film thickness of each layer.

[Means for Solving the Problems] The present invention provides an apparatus for vapor-phase growth of a group III-V compound semiconductor in which a group III source gas and a group V source gas are alternately supplied onto a substrate crystal in a reaction tube to grow a crystal. In, a gas inlet for a carrier gas and an impurity source gas disposed from the upper part of the substrate toward the substrate, and a group III source gas disposed on the periphery of the substrate crystal in the reaction tube with the substrate interposed therebetween. Independent outlets for the group V source gas, exhaust ports for the source gases disposed near the respective outlets, and an exhaust adjustment mechanism disposed in a pipe leading to the exhaust ports. And a III-V compound semiconductor vapor phase growth apparatus characterized by comprising: III-V source gas and III-V source gas are alternately supplied onto a substrate crystal in a reaction tube to perform crystal growth. In a vapor growth apparatus for a group V compound semiconductor, Gas inlets for the carrier gas and the impurity source gas disposed in the direction, and independent for the group III source gas and the group V source gas disposed on the periphery of the substrate crystal in the reaction tube with the substrate interposed therebetween. An outlet, an exhaust port for each of the source gases disposed near each of the outlets, an exhaust adjusting mechanism disposed in a pipe leading to each of the exhaust ports,
A group V raw material reaction tube, which is disposed on the upstream side of a group raw material gas ejection port and has two kinds of temperature regions therein, and a solid group V raw material placed in the group V raw material reaction tube, A III-V compound semiconductor vapor phase growth apparatus, comprising: a moving mechanism for moving between three types of temperature regions.

[Operation] FIG. 1 is a schematic configuration diagram of a vapor phase growth apparatus showing a basic configuration thereof also serving as an embodiment of the present invention.

A substrate crystal 15 is placed in a reaction tube 26 for performing crystal growth, and a gas inlet 18 for supplying a carrier gas and an impurity source gas near the substrate crystal 15 is provided above the substrate crystal 15. ing. In the peripheral portion of the substrate crystal 15, a jet port 16a of a group III source gas and a jet port 16b of a group V source gas are provided with the substrate crystal 15 interposed therebetween. As the group III source gas, for example, GaCl generated by the Ga source 19 and HCl is supplied to the substrate crystal 15 from the ejection port 16a by the carrier gas. On the other hand, as for the group V source gas, for example, AsH ₃ is supplied from the ejection port 16b to the substrate crystal 15 by the carrier gas,
Alternatively, as shown in FIG. 1, for example, As gas evaporated from solid arsenic 21 is supplied to the substrate crystal 15 from the jet port 16b in the group V raw material reaction tube 17 provided on the upstream side of the jet port 16b. Exhaust ports 11a, 11b provided with opening / closing valves 13a, 13b are arranged near the jet ports 16a, 16b.

In the present invention, the group III and group V source gases can be alternately supplied onto the substrate crystal 15 by opening and closing the respective opening / closing valves 13a and 13b provided in the exhaust ports 11a and 11b. For example, when the opening / closing valve 13a is closed, the group III source gas ejected from the ejection port 16a flows on the substrate crystal 15, and the carrier gas ejected from the gas introduction port 18 and the exhaust port 11a.
Exhausted from b. Further, when the opening / closing valve 13a is opened, the group III source gas ejected from the ejection port 16a is exhausted from the exhaust port 11a. In this operation, the group III source gas on the substrate crystal 15 is purged by the carrier gas at the gas inlet 18.

On the other hand, when the opening / closing valve 13b is closed, the group V source gas ejected from the ejection port 16b flows on the substrate crystal 15, and the gas introduction port
The exhaust gas is exhausted from the exhaust port 11a together with the carrier gas ejected from the exhaust gas. When the open / close valve 13b is opened, the group V source gas ejected from the ejection port 16b is exhausted from the exhaust port 11b. By this operation, the group V source gas on the substrate crystal 15 is supplied to the gas inlet 18.
Purged by the carrier gas from

By repeating the above operations, the group III and group V source gases flowing on the substrate crystal can be alternately supplied, rapidly cut off, and switched.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG. 1 is a schematic configuration diagram of one embodiment of the present invention.

In this embodiment, the growth of GaAs will be described as an example. As a Group III raw material, GaCl generated by reacting Ga19 with HCl supplied from the HCl inlet 20 was used, and as a Group V raw material, solid arsenic (As) 21 was used. The source boat 22 for As21 is placed in the group V raw material reaction tube 17 upstream of the jet port 16b, and is moved by the moving mechanism 23. The (100) plane GaAs crystal is used as the substrate crystal 15, and the substrate crystal 15 is set in the reaction tube 26 through the outlet 10. The temperature of the Ga source 19 was set to 750 ° C., the evaporation region 24 of the group V raw material reaction tube 17 was set to 400 ° C., and the standby region 25 was set to room temperature. The growth temperature of the substrate crystal 15 was 450 ° C. Group III source gas outlet
H ₂ was constantly supplied as a carrier gas from the gas inlet 16 a on the substrate crystal 15 and the jet port 16 b of the group V source gas 16 a. The flow conditions are shown below.

HCl 1 cc / min H ₂ 2,000 cc / min from each injection port of Group III source gas and Group V source gas H ₂ 4000 cc / min H ₂ from the gas inlet on the substrate crystal Standby source boat 22 of solid arsenic (As) 21 While moving to the region 25, the substrate crystal 15 is placed in the reaction tube 26, and the opening and closing valves 13a and 13b of the exhaust ports 11a and 11b are opened to raise the temperature of the reaction tube 26. When the temperature is stabilized, HCl is supplied from the HCl inlet 20 onto the Ga source 19. The GaCl generated by the reaction with the Ga source 19 blows out from the outlet 16a, and then the exhaust port 11a
More exhausted. The source boat 22 for As21 is 400
It moves to the evaporation region 24 of ° C. to evaporate As. As evaporated
Is ejected from the ejection port 16b and exhausted from the exhaust port 11b.
The carrier gas ejected from the gas inlet 18 on the substrate crystal 15 is dispersed into the exhaust port 11a and the exhaust port 11b and exhausted.
When the atmosphere was stabilized, the following growth procedure was performed.

The opening / closing valve 13a is closed for 5 seconds, and the GaCl spouted from the spout 16a flows on the substrate crystal 15 and is discharged from the exhaust port 11b together with the carrier gas spouted from the gas inlet 18. By this operation, GaCl is adsorbed on the surface of the substrate crystal 15.

Opening / closing valve 13a is opened for 10 seconds, and GaCl is discharged from exhaust port 11a. With this operation, GaCl on the substrate crystal 15 is
Purge from 18 with carrier gas.

The on / off valve 13b is closed, and the evaporated As flows on the substrate crystal 15 and is discharged from the exhaust port 11a together with the carrier gas ejected from the gas inlet 18. With this operation, GaAs is formed on the surface of the substrate crystal 15.

The opening / closing valve 13b is opened for 10 seconds, and As on the substrate crystal 15 is purged by the carrier gas at the gas inlet 18.

As a result of repeating the above operation 500 times, the film thickness becomes about 1400 mm, and the film thickness per ALE cycle is 2.8 mm.
It was calculated. This value is almost equal to the atom of the monolayer on the GaAs (100) plane, and it has been found that the ALE growth can be easily realized by the device according to the present invention.

FIG. 3 shows a graph of hydrogen selenide (H ₂ S
FIG. 9 is a schematic cross-sectional view showing a structure when a doping layer is formed on a GaAs layer using e) as an impurity.

As the substrate crystal 31, high resistance GaAs was used. 45 growth
The temperature is set to 0 ° C., and the above operation is repeated 35 times on the substrate crystal 31 by using the above-described growth apparatus (FIG. 1) and the growth procedure to grow the first GaAs layer 32. The doping layer is formed by introducing H ₂ Se gas into the growth gas from the gas inlet 18 on the substrate crystal.
Supply at a flow rate of 0.2 cc per minute, doping layer 33 of Se
Was formed. Further, the above-described growth procedure was repeated 100 times to grow the second GaAs layer 34, thereby forming a structure as shown in FIG.

As a result of measuring the sheet carrier concentration of this structure by Hall measurement, a value of 7 × 10 ¹² / cm ⁻² was obtained with good reproducibility.

Embodiment 2 FIG. 2 is a schematic configuration diagram of another embodiment of the present invention. The apparatus shown in FIG. 1 is the same as the apparatus shown in FIG. 1 except that there is no group V raw material reaction tube and a moving mechanism, and the group V raw material gas introduction pipe is directly connected to the jet port. Is the same as

In the present embodiment, the growth of GaAs using AsH ₃ as a group V source material and GaCl generated by a reaction between Ga and HCl as a group III source material will be described as an example. (100) GaAs is used as the substrate crystal 41, and the substrate crystal 41 is set from the outlet 40. The temperature of the Ga source 42 was 750 ° C., the decomposition temperature of the AsH ₃ gas was 750 ° C., and the temperature of the substrate crystal 41 was 450 ° C. Group III source gas outlet 43
a, H ₂ was always supplied as a carrier gas from a group V source gas outlet 43 b and a gas inlet 45 on the substrate crystal 41. The flow conditions are shown below.

AsH ₃ gas 5 cc / min HCl 1 cc / min on Ga source H ₂ 2000 cc / min from group III and V side jet ports H ₂ 4000 cc / min from gas inlet on substrate crystal Install substrate crystal 41 Then, the temperature of the reaction tube 46 is raised with the open / close valves 49a and 49b of the exhaust ports 47a and 47b of the reaction tube 46 opened.
When the temperature stabilizes, the HCl inlet 51 upstream of the Ga source 42
Supply more HCl. GaCl generated by the reaction with the Ga source 42 is spouted from the spout 43a and exhausted from the exhaust port 47a. AsH ₃ gas is supplied from a group V source gas introduction pipe 52. AsH ₃ gas decomposes into As ₄ and blows out from outlet 43b,
The air is exhausted from the exhaust port 47b. Gas inlet 4 on substrate crystal 41
H ₂ carrier gas ejection from 5 outlet 47a and the exhaust port
Dispersed in 47b and exhausted. When the atmosphere was stabilized, the growth procedure of Example 1 was repeated 300 times. As a result, the grown film thickness was about 850 °, and the film thickness per ALE cycle was almost equal to the monolayer thickness of the GaAs (100) plane. Å was calculated.

[Effects of the Invention] As described above, according to the present invention, II
By switching the flow of the source gas of the group I element and the group V element, the film thickness per ALE cycle can be easily controlled in the unit of a monolayer, and a low-toxic solid source is used for the group V element. A vapor phase growth apparatus for a group III-V compound semiconductor that can be used is provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of one embodiment of the present invention, FIG. 2 is a schematic configuration diagram of another embodiment of the present invention, and FIG. 3 is an example of a growth layer obtained by using the apparatus of the present invention. FIG. 4 is a schematic configuration diagram of a conventional vapor phase growth apparatus. 10,40 ... Outlet 11a, 11b, 47a, 47b ... Exhaust port 13a, 13b, 49a, 49b ... On / off valve 15,41,65 ... Substrate crystal 16a, 16b, 43a, 43b ... Outlet 17 Group V raw material reaction tube 18, 45 Gas inlet 19, 42, 61 Gallium (Ga) source 20, 51 HCl inlet 21 Solid arsenic, 22 Source boat 23 Move Mechanism, 24, evaporation region 25, standby region, 26, 46, 62, reaction tube 31, high-resistance GaAs substrate 32, first GaAs layer 33, Se doping layer 34, second GaAs layer 52: V-group source gas introduction pipes 63a, 63b: Growth chamber, 66: Substrate moving mechanism

Claims (2)

(57) [Claims] An apparatus for growing a group III-V compound semiconductor in which a group III source gas and a group V source gas are alternately supplied onto a substrate crystal in a reaction tube to grow the crystal. Gas inlets for the carrier gas and the impurity source gas disposed toward the substrate, and independent gas sources for the group III source gas and the group V source gas disposed on the periphery of the substrate crystal in the reaction tube with the substrate interposed therebetween. A discharge port, an exhaust port for each of the raw material gases disposed in the vicinity of each of the discharge ports, and an exhaust control mechanism disposed in a pipe communicating with each of the exhaust ports. III-V compound semiconductor vapor phase growth equipment. 2. A III-V compound semiconductor vapor phase growth apparatus in which a group III source gas and a group V source gas are alternately supplied onto a substrate crystal in a reaction tube to grow a crystal. Gas inlets for the carrier gas and the impurity source gas disposed toward the substrate, and independent gas sources for the group III source gas and the group V source gas disposed on the periphery of the substrate crystal in the reaction tube with the substrate interposed therebetween. An outlet, an exhaust port for each of the source gases disposed near each of the outlets, an exhaust control mechanism disposed in a pipe leading to each of the exhaust ports,
A group V raw material reaction tube, which is disposed on the upstream side of a group raw material gas ejection port and has two kinds of temperature regions therein, and a solid group V raw material placed in the group V raw material reaction tube, A III-V compound semiconductor vapor phase growth apparatus, comprising: a moving mechanism for moving between three kinds of temperature regions.