JPS5922120Y2 - Vapor phase growth equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vapor phase growth apparatus for Ill-■ intergroup compounds, II-VI intergroup compounds, and mixed crystals.

In the vapor phase growth of the compound, mixed crystal, etc., the concentration distribution of the constituent components in the gas in the growth region has a distribution in the gas flow direction because the constituent components are deposited on the substrate.

Moreover, in the commonly performed vapor phase growth, the ratio of constituent components in the gas when it flows into the reaction tube (for example, As/G
In a), the growth is performed in a state that is greatly different from the ratio of the compound to be grown.

Therefore, since growth is performed depending on the composition of the compound in the growth region, not only the concentration of the constituent components in the gas phase but also the concentration ratio changes greatly in the gas flow direction.

Therefore, when growth is performed using conventional methods, it is difficult to make the thickness distribution of the grown layer uniform within the wafer, and it is also difficult to grow a large number of wafers at the same time.

As described above, since the concentration of the constituent components in the gas is not constant, the crystallinity within a wafer or between wafers differs significantly.

The present invention is intended to correct such drawbacks of vapor phase growth.

The above will be explained in detail using figures.

Taking GaAs vapor phase growth as an example, FIG. 1 shows a conventional growth apparatus using trimethyl gallium (hereinafter referred to as TMG) 3 and arsine (hereinafter referred to as ASH 3) as raw materials.

Figure 1b shows the Ga concentration 6, As concentration 5, and the ratio of As concentration to GS concentration (A
s/Ga) 7 is shown with respect to the gas flow direction.

The As/Ga ratio in the gas when introduced into the reaction tube 1 is in the range of 2 to 10.

This moderate TMG, N2 gas containing AsH3 or N
2 gas (any inert gas will do) or on the GaAs substrate.

At this time, if the GaAs substrate is maintained at 600'C to 900C, Ga and As will be deposited on the GaAs substrate 2 at a ratio of 1:1.

Therefore, the concentrations of Ga and As in the gas decrease as shown in FIG.

Furthermore, since the As concentration 5 in the gas is greater than the Ga concentration 6, As/Ga 7 in the gas increases as GaAs is deposited on the substrate.

As described above, since the As and Ga concentrations in the gas decrease in the gas flow direction, the growth rate of GaAs decreases in the gas flow direction.

Also, as As/Ga7 in the gas increases in the gas flow direction, the crystallinity of the grown layer (carrier mobility, carrier density when grown undoped, deviation from stoichiometric composition, etc.) changes. I'll come.

This proposal is intended to prevent the concentration of As and Ga in the gas in the gas flow direction from changing in the growth region.

In other words, a part of the gas in the growth region is extracted or the gas in the growth region is directly measured by infrared spectroscopy or mass spectrometry to measure the concentration of Ga, As, or both in the gas, and then a supply pipe placed in the growth region is used. , Ga, As, or both are supplied to keep the concentrations of Ga and As in the gas phase constant in the growth region.

Next, using the diagram, TMG-AsH3-N2 system GaAs
An example will be shown using vapor phase growth as an example.

As shown in Figure 2a, the growth apparatus is a conventional TMG-As
This is an H3-based growth apparatus with a gas detection device and a gas replenishment device added to the growth region.

TM due to the composition carried out from the main stream inlet 23 of the gas.
Gases 3 and 4 containing G and AsH3 are flowed into the growth region 8.

In this case, as described above, since GaAs grows, the concentration 17.19 of Ga and As in the gas phase decreases.

In order to replenish this decreased amount, each component gas of the reaction raw material gas is added to Capilano (1), 11 and (2), (
12 for measurement, and the results are returned to each structure e, a replenishment capillary valve (1) installed in the replenishment pipe connected to the gas source.

(2), (3), (4) (13, 14, 15, 16
) and automatically adjust Ga.

Increase the concentration of As 17.19.

In this example, as shown in FIG.
As the concentration of s 17.19 decreases, As/Ga
Since the concentration ratio 21 becomes high, in order to keep this concentration ratio constant, the replenishment capillary valve 13. which adjusts the TMG is required.
Supply capillary valve 1 to adjust 15 and AsH3
4.16 for each machine rf7 based on the above detection results:
The rfi was adjusted separately for every 9, and each concentration of As and Gs and the As/Ga concentration ratio were kept constant.

When GaAs is grown using a conventional vapor phase growth apparatus, the wafers cannot be grown side by side in the gas flow direction, and the thickness distribution within the wafer is at most ±10%.

By using the growth apparatus of the present invention, undoped Ga
Growing As, the thickness of the grown layer is ±4% within one wafer.
, it was possible to control within ±5% between wafers.

Furthermore, the carrier mobility, which indicates crystallinity, could be controlled within ±5% between wafers.

The vapor phase growth apparatus according to the present invention can be applied to the Ga-AsC1□-N2 system or the Ga-AsCl2-N2 system.

Also, the crystals to be grown are all II such as GaP and InP.
Crystals with excellent uniformity in the vapor phase growth of IV intercalary compound crystals, mixed crystals between them, and all ■■-v I group intercycle compound crystals such as ZeSe, ZeTe, etc. can be grown in large quantities.

The same applies to mixed crystal systems of group IV elements, such as 5i-Ge.

It is clear that this method is particularly effective for mixed crystals that can be mixed in the entire composition range.

The method of detecting and replenishing components in the gas can also be performed in a variety of applications, as shown in FIG.

In FIG. 3a, the detection capillary and the replenishment capillary are brought closer together to speed up the replenishment response.

In Figure 3, the outlet of the replenishment capillary was oriented horizontally, so that the replenished gas could be quickly uniformized.

FIG. 3C shows a replenishment capillary with a large number of holes so as to maintain uniformity both in the gas flow direction and in the lateral direction.

Further, any number of detection capillaries and supply capillaries may be used, and the larger the number, the better.

This proposal can be applied to furnaces using all heating methods, including high-frequency induction heating, resistance heating, and lamp heating.

[Brief Description of the Drawings] Figure 1a is a schematic diagram of a conventionally used GaAs vapor phase growth apparatus. A distribution diagram of the concentration of Ga and As and their ratio in the gas flow direction. Figure 2a is a schematic diagram of the vapor phase growth apparatus of the present invention. Figure 2 shows the reaction when using the vapor phase growth apparatus of the present invention. Distribution diagram of the concentration of Ga and As in the pipe gas and their ratio in the gas flow direction, Figure 3 a, l)
, c, and d are diagrams showing application examples of a detection capillary and a replenishment capillary. DESCRIPTION OF SYMBOLS 1... Reaction tube, 2... Substrate, 3... Trimethyl gallium, 4... Arsine 5... As, 6... G
a, 7...As/Ga. 8...Growth area.

Claims (1)

[Scope of utility model registration request] A reaction raw material gas is introduced into a reaction vessel in which a semiconductor substrate is arranged along the flow direction of the reaction raw material gas, and an I
In a method for growing II-V intergroup compound crystals, II-VI intergroup compound crystals, or mixed crystals in a vapor phase, one end is divided into a plurality of parts, each of which has a separate flow rate adjustment means for each component gas source in the reaction raw material gas. A supply pipe that is connected to the supply pipe and whose other end opens at any point in the flow direction of the reaction raw material gas in the reaction vessel, and a supply pipe that is connected to each other in the reaction raw material gas provided near the opening of the supply pipe in the reaction vessel. Structure e, means for detecting the concentration of the component gas, and means for adjusting the flow rate of each component gas flowing through the supply pipe in order to maintain the concentration of each component gas in the reaction vessel at a predetermined concentration based on the detection result. A vapor phase growth apparatus comprising: