JPS63227009A - Vapor growth method - Google Patents

Abstract

PURPOSE:To obtain an abrupt boundary in doping characteristics by introducing gas which does not contain reaction gases at least from two directions to the upstream side of a susceptor. CONSTITUTION:Gases which do not contain reaction gases are introduced from gas inlet tubes 22 of at least two directions to the upstream side of a susceptor 4. Accordingly, it can not only prevent a reaction substance from adhering to the upstream side of the susceptor 4 of a quartz furnace tube 2, but improve the disconnection of the gas in the tube 2. Thus, when the GaAs of an undoped layer, an N-type layer, a P-type layer, and an Al0.3Ga0.7As layer are continuously grown, the transition regions of the impurity, the composition in the boundaries are 20Angstrom or less to obtain an abrupt boundary with good reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vapor phase growth method used for growing crystals of compound semiconductors and the like on a substrate.

Background of the Invention In recent years, vapor phase epitaxial growth methods for III-V and ■-■ group compound semiconductors, particularly metal-organic vapor phase epitaxy (M
OV P Tt ; Metal Organic V
Apor PhaseEp (taxy) has attracted attention due to its uniformity over a large area, mass productivity, and controllability of film thickness and composition, and research and development are being actively conducted in various places.

Conventionally, an apparatus used for this type of vapor phase growth method was as shown in FIG. 1 is the inlet of the reactant gas, for example GaA.
For the growth of trimethylgallium T M G ((
This serves as an inlet for OH, ), Ga), arsine AsH, and carrier gas H2. 2 is a quartz furnace core tube, 3 is a susceptor support rod, 4 is a susceptor, and 6 is a substrate, for example, a GaAs substrate. The substrate 5 is connected to the susceptor 4 by, for example, a high frequency coil 6 provided outside the crystal growth chamber, that is, the quartz furnace core tube 2.
is heated and held at the desired temperature. Reaction gas is inlet 1
When passing over the substrate 6 which has been introduced from the source and heated to a predetermined temperature, part of it contributes to crystal growth, and the rest is exhausted. When the reaction gas is introduced from the inlet 1, the heat of the susceptor 4 is also transmitted to the upstream side of the susceptor, and a large amount of deposits are also attached to the quartz furnace core tube 2 on the upstream side of the susceptor 4. In order to prevent this deposit, a quartz furnace core tube as shown in FIGS. 7 and 8 has been used. The quartz hearth tube shown in Figure 7 is a double tube.
There are countless small holes inside, as shown by the arrows <N2
The structure was such that an inert gas was fed in to form a protective gas layer on the inner surface of the tube wall 8, and to prevent the reaction gas from flowing toward the quartz furnace core tube wall 8. Also, in Fig. 8, there is a double pipe on the upstream side of the sassefuri 4, the reaction gas is introduced into the inside (g), and the outside (g) is
'2' N2 or an inert gas having a faster flow rate than gl was fed to prevent the reaction gas from moving toward the inner wall of the quartz furnace core tube.

Problems to be Solved by the Invention As described above, in the commonly used crystal growth chamber shown in FIG. The attached deposits have a negative effect on the next crystal growth.

First, the inside of the quartz furnace core tube 2 becomes completely invisible. These are
This adversely affects the gas flow during the next crystal growth, making it impossible to obtain a steep interface, especially in terms of doping characteristics.

Further, the furnace core tubes shown in FIGS. 7 and 8 both have a double structure, which makes the interior of the quartz furnace core tube extremely complicated and inconvenient to handle. Furthermore, in the structure shown in FIG. 7, it is difficult to maintain the gas flow coming out of the countless holes provided in the tube wall 8 evenly with respect to the flow of the reaction gas, and it is difficult to realize a laminar flow on the substrate. It is difficult.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a vapor phase growth method in which a gas not containing a reaction gas can be introduced into the upstream side of a susceptor from at least two directions. be.

action The effect of this technical means is as follows.

The gas introduction method according to the present invention not only prevents deposits from adhering to the inner wall of the quartz furnace core tube on the upstream side of the susceptor by introducing a gas that does not contain a reaction gas from at least two directions around the reaction gas introduction tube. , to improve gas drainage in the quartz furnace core tube.

The device is very simple, laminar flow can be easily obtained on the susceptor, and ultra-thin films such as superlattices can be created with good controllability.

Example A specific embodiment according to the present invention is shown in FIG.

21 is an inlet for reactant gas and hydrogen gas for carrier gas, that is, a reactant gas introduction pipe; 22 is an inlet for a gas not containing reactant gas, such as N2. The introduction pipe for N2 or inert gas, etc., 2 is a quartz furnace core pipe. FIG. 2 shows, for example, a flange 23 in which gases not containing a reaction gas are introduced from four directions. A reaction gas is supplied from an inlet pipe 21 at the center. This is made of stainless steel, can be welded to the flange 23 immediately, has a simple structure, and is very easy to work with. Also, the quartz furnace core tube does not have a double structure. If a quartz glass tube is attached to the tip of the reactant gas and the gas introduction tubes 21 and 22 that do not contain the reactant gas so that the stainless steel tube does not appear at the tip, since the thermal conductivity of the quartz glass tube is low, The tips of the gas introduction pipes 21 and 22 do not rise much due to the heat from the susceptor. That is, it is not necessary to water-cool the 7-lunge 23. In addition, by integrating the gas introduction pipes without a reaction gas stand outside the crystal growth chamber, gas can be supplied to each introduction pipe within the crystal growth chamber at the same pressure.

Furthermore, since the tip of the gas introduction tube that does not contain a reaction gas is located on the upstream side compared to the reaction gas introduction tube, the reaction gas
This has the effect of not only preventing the gas from flowing toward the flange 23, but also preventing it from adhering to the reaction gas introduction pipe.

Crystal growth was actually performed using the vapor phase growth method of the present invention and good results were obtained, so details including the growth conditions will be described below. undopad layer 42. n-type layer 43, p-type layer 4
4 GaAs is continuously grown and further undoped.
We grew a d-layer (Jo, 5G2L0.7, S-layer 4!5, and obtained good results with very small dopant and compositional transition layers.The reaction gas used was TMG for the group II). Remethylaluminum TMA ((aH3)3A#),
Group V is AsHs (6%), p-type dopant is
Dimethyl zinc DM Z ((OH3)2Zn), n
Hydrogen selenide H2Se was used as a type dopant.

The carrier gas is H2. GaAs layer and layer. ,3
When growing Ga, ', As layers, TMG, TMA, DM
Z.

H2Se (1ooppm) H, and tD flow rates are 30cc/min, 1 occ/min, and 200cc, respectively.
/min.

is cc/min, 6 cc7min, 2 l/
It is min. The growth temperature was 760°C, and the growth rate at this time was 171 m/m1n (in the case of a GaAs layer).
1.2 μm/m1n (in the case of a layer of Ga, Ga, and As). For gas inlet pipes that do not contain reactive gases,
Only 3 d/min of H2 was introduced. undoped
Layer 42. n-type layer 43° p-type layer 44 GaAs layer and layer
o,'s G2Lo, 7As layer 46 each 100
The specimens were grown and the steepness of the interface was evaluated by SIMS.

If hydrogen is not passed through a gas inlet pipe that does not contain reactant gas,
It can be seen that not only the quartz furnace core tube 2 but also the flange 23 are covered with deposits, which not only makes the quartz furnace core tube dirty but also does not drain the gas well. By simply flowing hydrogen at 2 d/min into the gas introduction pipe that does not contain a reaction gas, the shaded area 2 in Figure 3
As shown in Figure 4, no deposits after the reaction were visible on the upstream side of the susceptor. In this case, since hydrogen is introduced from four directions with good symmetry, the deposits also form a ring shape with good symmetry.

Next, FIG. 4 shows the results of SIMS of the crystals produced under the conditions shown above, together with the results obtained when no gas was flowed through the gas introduction tube that did not contain the reaction gas. From the SrMS results in FIG. 5, it can be seen that the transition region is 20 Å or less when the gas is flowed into the gas introduction pipe that does not contain the reaction gas, indicating that the gas is extremely well cut (solid line part). It can be seen that when the gas is not flowed into the gas introduction pipe that does not contain the reactant gas, the transition region is 408 or more, which indicates that the gas is not well drained (broken line area).

That is, by providing a gas inlet that does not contain a reactive gas, not only was the quartz furnace core tube upstream of the susceptor not contaminated, but the IJ-effect of 5s-1pZn was almost completely eliminated.

Furthermore, although the above description has been made regarding AgGaAs/GaAs, it goes without saying that the present invention can also be applied to InGaAsP/InP, A%aInP/GaAs, ZuSe/ZuS, and the like. Furthermore, it is applicable not only to organometallic vapor phase growth methods but also to other vapor phase growth methods.

Effects of the Invention According to the present invention, by introducing a gas that does not contain a reactive gas into the upstream side of the susceptor from at least two directions, it is possible not only to prevent the adhesion of reactive substances to the upstream side of the susceptor of the quartz furnace core tube, but also to The gas in the furnace core tube is better drained, resulting in an undoped layer.

CaAs and klo, Gao, n-type layer and p-type layer
When the As layer is continuously grown, the transition region of impurities and composition at each interface is 20 Å or less, and a steep interface can be obtained with good reproducibility.

Therefore, it is extremely effective in producing devices using Quantum Well v-za or superlattices. Furthermore, since a high-quality crystal can be obtained with good uniformity over a large area, it is possible to significantly reduce the cost of devices made from this crystal, which has a very large practical effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an apparatus used in the method of one embodiment of the present invention, FIGS. 2(a) and (b) are schematic plan and side views of the gas introduction part in the method of this embodiment, and FIG. A schematic cross-sectional view of the quartz furnace core tube after crystal growth in the method of this example, FIG. 4 is a cross-sectional view of the epitaxial film produced using the method of this example, and FIG. 6 shows the SIMS results of the epitaxial film. The characteristic diagrams, FIGS. 6, 7, and 8 are schematic cross-sectional views showing the crystal growth chamber in the conventional method. 1...Inlet, 2...Quartz furnace core tube (crystal growth chamber) 4...Susceptor, 6...Substrate, 21...P-reaction Gas introduction pipe, 22...
Gas introduction pipe that does not contain reactive gas. Name of agent: Patent attorney Toshio Nakao and 1 other person2-
5 Sara・Kojoo Figure 2 (.+ (1)) ”'-” 77
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Claims (6)

[Claims] (1) When introducing a reactive gas into the crystal growth chamber and forming a thin film on the substrate on the susceptor placed in the crystal growth chamber, the reactive gas is not included at least on the upstream side of the susceptor from at least two directions. A vapor phase growth method that involves introducing gas. (2) The vapor phase growth method according to claim 1, wherein the inlets for the gas not containing the reactant gas are arranged at equal intervals on a plane cut perpendicular to the gas flow in the crystal growth chamber. (3) The vapor phase growth method according to claim 1, wherein the inlet for the gas that does not contain the reactive gas is oriented in the direction of gas flow within the crystal growth chamber. (4) The vapor phase growth method according to claim 1, wherein a quartz glass jig is provided at the tip of the inlet for the gas that does not contain the reactant gas inside the crystal growth chamber. (5) The vapor phase growth method according to claim 1, wherein the gas that does not contain a reactive gas is hydrogen, nitrogen, argon, or a mixture of at least two of the above gases. (6) The vapor phase growth method according to claim 1, wherein the gas inlets that do not contain the reaction gas are connected to a single pipe outside the crystal growth chamber, or each gas is supplied independently. (7) The vapor phase growth method according to claim 1, wherein the tip of the gas inlet that does not contain a reactive gas in the crystal growth chamber is at least upstream of the tip of the reactive gas inlet.