JPH03224215A - Organic metal vapor phase deposition device - Google Patents

Abstract

PURPOSE:To manufacture the semiconductor elements of a complicated laser structure having excellent characteristics by a method wherein the material feed systems to epitaxially deposit a semiconductor layer on a semiconductor substrate are provided with multiple flow rate controllers. CONSTITUTION:Mixed material gas containing organic metal produced by material feed systems 20, 30, 40, 50, 60. 70 is led into a reactor 10 wherein the mixed material gas is reacted by thermal cracking process to epitaxially deposit a semiconductor layer on a semiconductor substrate 12. AN AsH2 material feed system 20, a PH2 material feed system 30, a TMI material feed system 50 and a TEG material feed system 60 are respectively provided with two each of mass flow controllers 22, three each of mass flow controllers 32, three each of mass flow controllers 51 and two each of mass flow controllers 61. In such a constitution, the composition can be transferred within a short time thereby enabling semiconductor elements of a complicated laser structure having excellent characteristics to be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an organometallic vapor phase growth apparatus with high composition controllability.

[Prior art; In the metal organic chemical vapor deposition (MOCVD) method, a desired raw material gas is heated by high-frequency induction heating or fed into an reactor, and a desired semiconductor is formed on a semiconductor substrate placed in the reactor by a thermal decomposition reaction. This is a growth method in which a layer is grown epitaxially, and its feature is that an epitaxial layer with good composition and film thickness can be easily obtained over a large area. This basic device is shown in FIG.

In the figure, 10 is a quartz glue actuator, 11 is a high-frequency induction heating coil, 12 is a semiconductor substrate such as InGa, 20 is an AsH, raw material supply system, 30 is a PH3 raw material supply system, 40 is a HlS, raw material supply system , 50 is an organometallic trimethylindium (TMI) raw material supply system, 60 is a triethyl gallium (TEG) raw material supply system, 70 is a diethyl diink (DEZ) raw material supply system that becomes a P-type dopant,
80 is a raw material supply system pipe, and 90 is a raw material supply pressure correction pipe. 100 is a rotary pump that maintains the inside of the quartz glue actuator 10 in a vacuum state, and 101 is a rotary ribbon knob 10.
This is a trap device that prevents contaminants such as oil from flowing back into the quartz glue actuator IO side. Here AsH,
The raw material supply system 20 is connected to an A5H3 cylinder 21 containing AsH=gas, a mass flow controller 22 that controls the flow of this gas, a raw material supply system pipe 80, and a raw material supply pressure correction pipe 90, and is connected to the mass flow The mass flow controller 22 is configured with valves 23 and 24 for introducing or not introducing the gas flow from the controller 22 into the reactor 10, and is connected to the mass flow controller 22 via the raw material supply pressure correction piping 90.
The flow rate of AsH3 was controlled by the quartz reactor 10.
It is designed to lead to. Similarly, the PH, raw material supply system 30 and Hls, raw material supply system 40 are connected to the PH3 cylinder 31.
, Hls, Bonhe 41, mass flow controller 32.
42, consisting of valves 33.34.43.44;
In the same manner, each raw material is guided to the quartz reactor 10. The TMI raw material supply system 50 also includes a mass flow controller 51 that controls the flow rate of hydrogen from a hydrogen gas supply source (not shown). Bubbling device 52 containing TMI raw material
, raw material supply system piping 80 and raw material supply pressure correction piping 90
consisting of bubbles 53 and 54 respectively connected to
Hydrogen whose flow rate is controlled by the mass flow controller 51 is guided into the Huffling device 52, where the hydrogen is bubbled within the TM+ raw material to create a gas containing the TMI raw material in the hydrogen, and this created gas is passed through the valve. 53 into the reactor 10.

The mass flow controllers 61, 71. It is composed of a bubbling device 62.72 and bubbles 63.64.73.74. A mass flow controller 81 is provided in each of the raw material supply system piping 80 and the raw material supply pressure correction piping 90.
- A predetermined amount of a mixed gas of hydrogen and nitrogen is supplied through the pipe 91, and it is configured to absorb changes in pressure occurring in these pipes by opening and closing bubbles connected to each raw material supply system. Note that 110 is a computer for controlling each mass flow controller and valve.

In such an apparatus, in order to grow an organometallic film on the semiconductor substrate 12 in a vapor phase, first, the rotary pump 1 is
00 is operated to bring the inside of the reactor 10 into a predetermined vacuum pressure state, and the high-frequency induction heating coil 11 is energized to heat the semiconductor substrate 12 inside the reactor 10 to a predetermined temperature, for example, 650°C. In this state, the flow and quantity of the AsHs raw material supply system 20, PH3 raw material supply system 30, Hz S - raw material supply system 40, TMI raw material supply system 50, TEG raw material supply system 60, and DEZ raw material supply system 70 are controlled by each mass flow controller. The mixed raw material gas guided to the quartz reactor 10 through the valves of each system and the raw material supply system piping 80 undergoes a thermal decomposition reaction here, and a predetermined amount is formed on the semiconductor substrate 12 by epitaxial growth. Organometallic films with different composition ratios are stacked. The composition ratio of the organic metal film formed by epitaxial growth is changed by controlling the flow rate and each knob of the mass flow controller using a program stored in the computer 110 in advance. The remaining gas resulting from the thermal decomposition reaction of the mixed raw material gas is discharged to an exhaust gas treatment device (not shown) via the rotary pump 100.

Such MOCVD method has been widely used in recent years. In particular, GaInAsP/I, which is important as a light source for optical communication,
MOCVD is an effective growth method for nP systems. G
A multi-quantum well laser with a separate confinement heterostructure (SCH) structure has been fabricated in the InAsP/InP system, and improvements in dynamic characteristics expected for quantum well lasers have been obtained.

[Problems with the Prior Art] A conventional MOCVD apparatus was equipped with - number of flow rate controllers for one raw material.

On the other hand, one of the semiconductor laser devices that can be produced using this MOCVD method is A A x Ga+-, As/GaAs system. In the case of this material system, there is almost no lattice mismatch between A i Xca+-xAsli and GaAsFi at the epitaxial growth temperature. Therefore, the GaAs layer, A 1
, Ga, −, As layer, GaAs layer, A 1 vGa+
-JS layer, GaAs layer, ^' zGa+-zAslii
When epitaxially growing multiple layers such as...
Although there is an NC transition layer with a different composition due to gas switching at each epitaxial growth interface, since the lattice mismatch between adjacent compositions is very small, it hardly affects the laser characteristics.

However, Gaxln+-xAsyP+-y/In
In the P system, if there are several to several dozen transition layers, Ga1
The crystallinity of the nAsP system deteriorates, affecting laser characteristics. In particular, this becomes more noticeable when the thickness of the -layer is very thin, from several tens to several hundreds, as in a quantum well laser device.

Furthermore, when GalnAsP layers having different compositions are controlled by one mass flow controller, a large flow rate is required, and composition controllability becomes a problem from the viewpoint of accuracy. Therefore, with conventional MOCVD equipment,
Regarding the Ga1nAsP/TnP system, it was not possible to epitaxially grow a complex layer structure, and it was limited to the SCH structure, and it was not possible to realize a reduction in threshold current density.

[Means for Solving the Problems] The present invention has been conceived up to this point, and its purpose is to:
MOCV enables production of semiconductor lasers with excellent characteristics
D apparatus is provided, and its specific configuration is to introduce a mixed raw material gas containing an organic metal produced by a plurality of raw material supply systems into a reactor, and cause the mixed raw material gas to undergo a thermal decomposition reaction within the reactor. In an organometallic vapor phase growth apparatus that epitaxially grows a semiconductor layer by
The metal-organic vapor phase growth apparatus is characterized in that at least one of the raw material supply systems is equipped with a plurality of flow rate side devices.

〔Example〕

An embodiment of the present invention is shown in FIG. In the figure, IO to 110 which are the same as those explained in FIG. 3 respectively indicate the same parts as shown in FIG. 3, and their functions are also the same. However, Hg5a raw material supply system 40 and DEZ raw material supply system 7
Each of the raw material supply systems 20 to 60 except for 0 differs in the following points. That is, the A s Hs raw material supply system pipe line is equipped with two mass flow controllers 22, and each mass flow controller 22 is equipped with valves 23 and 24 on the supply system pipe 80 and the raw material supply pressure correction pipe 90, respectively. . The PH3 raw material supply system 30 includes three mass flow controllers 32, and each mass flow controller 3
2 includes a supply system piping 80 and a raw material supply pressure correction piping 90.
and valves 33 and 34, respectively. However, in order to simplify the drawing, each device is shown in an overlapping manner (the same applies in the following explanation).The TMI raw material supply system 50 includes three mass flow controllers 51, and each mass flow A bubbling device 52 is connected to each controller 51, and each bubbling device 52 includes valves 53 and 54 connected to a raw material supply system pipe line 80 and a raw material supply pressure correction pipe 90, respectively. Similarly, 60 mass flow controllers 61, 2 bubbling devices 62, and valves 63 and 64 connected to each bubbling device 62 of the TEGI material supply yarn supply system.
It is equipped with

To actually use this device, first of all, as in the conventional case, the high-frequency induction heating coil 11 is energized, and the reactor 10 is energized.
The semiconductor substrate 12 inside is heated to a predetermined temperature, for example, 650°C. In this state, the ASH1 raw material supply system 20, P
H3 raw material supply system 30, Hz S-raw material supply system 40, TM
[The flow rate is controlled by one or more mass flow controllers of the raw material supply system 50, the TEG raw material supply system 60, and the DEZ raw material supply system 70, and each raw material supply system 20 to 70 is controlled through one valve of each system. A mixed raw material gas having a predetermined mixing ratio is supplied into the reactor 10 from the reactor 10, and an MOCVD reaction is caused in the reactor 10 as in the conventional method.

When changing the raw material composition to be supplied to the reactor 10 in this state, the flow rate of each raw material supply system to be supplied is individually controlled via other unused mass flow controllers, and the raw material supply pressure correction piping 90 By controlling the opening and closing of the valves of each raw material supply system in this state, the raw materials that have been supplied so far are discharged to the raw material supply pressure correction piping 90 side, and The raw material discharged to the raw material supply pressure correction piping 90 side is switched to the supply system piping 80 side. This makes it possible to instantly switch between appropriate amounts of each raw material that have been adjusted in advance. Therefore, a suitable amount and mixing ratio of raw material gas can be supplied into the reactor 10 in a very short period of time. These controls are sequentially performed each time each layer is formed by a computer 110 programmed in advance.

FIG. 2 shows a semiconductor laser device manufactured by this apparatus based on the conditions shown in the table below. In the figure, 121 is n-1
nP substrate, 122 is an n-1nP buffer layer, 123 is a quantum well active layer, 124 and 125 are each active layer 1
126 is a p-1nP cladding layer;
7 is a p-Ga1nAsP contact layer. The composition of the confinement layers 124 and 125 is 1.1.1.051.0 in terms of bandgap wavelength from the side closest to the active layer 123.
．． It was set to 0.95 μm. In addition, the quantum well active layer 123 includes a quantum well (thickness: 150 μm) having a composition of 1.32 μm in terms of band gap wavelength, and a barrier layer (thickness: 150 μm) having a composition of 1.1 μm in terms of band gap wavelength. It consists of

The threshold current density of the semiconductor laser device obtained in the table is 5. Full-surface electrode structure with a resonator length of 890 μm.
41KA/Cm", the lowest value ever reported.

[Effects of the Invention] As described above, the present invention introduces a mixed raw material gas containing an organic metal produced by a plurality of raw material supply systems into a reactor, and causes the mixed raw material gas to undergo a thermal decomposition reaction in the reactor. A metal organic vapor phase growth apparatus for epitaxially growing a semiconductor layer on a semiconductor substrate placed in a reactor, characterized in that at least one raw material supply system is provided with a plurality of independently settable flow rate controllers. This is a metal vapor phase growth device. This makes it possible to fabricate ultra-thin film heterojunctions of mixed crystal semiconductors with interface steepness on the order of single atoms, which requires precise compositional switching in a short period of time. This has an excellent effect of providing a semiconductor device with a structured structure.

[Brief explanation of drawings]

FIG. 1 is an MOCVD device according to an embodiment of the present invention, FIG. 2 is a schematic structural diagram of a semiconductor laser device manufactured using the device of the present invention, and FIG. 3 is a configuration diagram showing a conventional MOCVD device. . 10 is a quartz glue actor, 11 is a high-frequency induction heating coil, 12 is a semiconductor substrate, 20 is an AsH3 raw material supply system, 3
0 is the PH3 raw material supply system, 40 is H, S. A raw material supply system, 50 is an organometallic trimethylindium (TMI) raw material supply system, 60 is a triethyl gallium (T
EG) Raw material supply system, 70 is a DEZ raw material supply system, 80 is a raw material supply system piping, and 90 is a raw material supply pressure correction piping.

Claims (2)

[Claims] (1) A mixed raw material gas containing organic metals created by multiple raw material supply systems is introduced into the reactor, and the mixed raw material gas is subjected to a thermal decomposition reaction in the reactor, thereby forming a material on a semiconductor substrate placed in the reactor. A metal organic vapor phase growth apparatus for epitaxially growing a semiconductor layer, wherein at least one of the raw material supply systems is equipped with a plurality of flow rate controllers. (2) A plurality of flow rate controllers provided in one raw material supply system are provided with valves for introducing or not introducing the raw material gas whose flow rate is controlled by each flow rate controller into the reactor. The organometallic vapor phase growth apparatus according to claim 1.