JPS6122619A - Vapor-phase epitaxial growing device - Google Patents

Abstract

PURPOSE:To grow a number of crystal wafers with excellent working efficiency by a method wherein a device which performs temperature controlling function is provided in the vicinity of the source part of a source pipe, and said device is independently controlled. CONSTITUTION:The high speed heating-cooling furnaces 20, 21, 22 and 23, with which the temperature in the vicinity of the source part of a source pipe is controlled, are provided completely independent of the electric furnace 16 which controls the temperature of a reactor part. These furnaces have the rising and falling speed of temperature of + or -100 deg.C/sec or thereabout. Also, these high speed heating-cooling furnaces 20-30 are constructed in such a manner that they give no effect of heat induction on the adjoining furnaces. When four-layer structure is grown in a growing process, as the process wherein the metal source subsequent to the second sheet are saturated by chroride gas and the stand-by process to be performed after completion of the growth of the first layer can be omitted, the time required for growing process can be reduced to a little more than 1/3 of the time required for the conventional method.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a vapor phase epitaxial growth apparatus for growing compound semiconductor multilayer films.

(Prior Art) When manufacturing a semiconductor crystal with a multilayer structure, a highly accurate crystal growth technique is required, and methods for growing this compound semiconductor multilayer film include liquid phase growth, vapor phase growth, and the like. Among these growth methods, the vapor phase growth method is superior in terms of growth of high-purity crystals and mass productivity.

FIG. 1 shows a conventional hydride vapor phase epitaxy growth apparatus. Using the same growth apparatus, n-InP/n-InP/InGaA was grown on the 'I InP substrate 1.
Taking as an example the case of growing a crystal for an aP/InGaAs four-layer heterostructure Avalan 7E photodiode (hereinafter referred to as rAPDJ)9, the structure and growth procedure of the growth apparatus will be described.

In the figure, HCL, PH3, and AsH3 gases are used to supply raw materials, and their concentration is 10% on a hydrogen basis.
%, and the H2S gas is a dopant for making the InP fen type, and the hydrogen paste has a concentration of 10 ppm. Further, the flow rates of the H2 carrier gas flowing into the first growth chamber 5 and the second growth chamber 6 are 1001000c' and 15θ, respectively.
Occmm'.

Under the above conditions, the growth takes place according to the following steps. However, the flow rates of each gas are omitted.

Step 1: 25 minutes before the start of growth 1-1. The first In source tube 9 and the first. HCt gas is caused to flow through the Ga source tube 7 to chemically react with the first In source 1o and the first Ga source 8, and the first In source 1o and the first Ga source 8 are saturated with the InCt gas and GaCA gas.

Step 2: 5 minutes before the start of growth 2-1. AsH3 gas is passed through the Group 1 hydride gas introduction pipe 11.

2-2. In order to prevent thermal deterioration of the InP substrate 1, PH3 is supplied from the raw hydride gas introduction pipe 3 for preheating.

2-3. The InP substrate 1 on the substrate holder 2 is heated in the preheating area 4.
The temperature of the substrate 1 is raised to the growth temperature of 700°C.

Step 3: Growth of InGaAs first layer 3-1. The substrate 1 is moved to the first growth chamber 5 and grown for 15 minutes.

3-2. Five minutes before the end of the first layer growth, AsH3 gas is flowed into the second growth chamber 6 through the Group 2 hydride gas introduction pipe 14.

Step 4: End of 1st layer growth and start of 5th layer growth 4-1.
The substrate 1 is moved to the first growth chamber 5 or the second growth chamber 6, and
The source gas in the growth chamber 5 is allowed to flow for about 25 minutes until it reaches a steady state.

4-2. H to the 11n source tube 9 and the first Ga source tube 7.
Ct gas is supplied to the first In source 1o and the first In source 1o. The Ga sources 8 are saturated with InCA and GaCl, respectively.

4-3. A mixed gas of PH3 and AsHa is flowed from the Group 1 hydride gas inlet pipe 1.

Step 5: Growth of InGaAsP second layer 5-1.
The substrate 1 is moved from the second growth chamber 6 to the first growth chamber 5 and grown for 15 minutes.

5-2. HCt gas is caused to flow through the 21n source tube 12.

5-3. Change the AsJ (3 gas) flowing into the 2V group hydride gas introduction pipe 14 to PH3 gas.

Step 6: Growth of n-InP third layer and n--InP fourth layer 6-1. H2S is flowed from the doping tube 15 for about 5 minutes.

6-2. The substrate 1 is moved from the first growth chamber 5 to the second growth chamber 6.

6-3. Grow a third layer of n-InP for 5 minutes.

6-4. Close the valve of doping tube 15.

6-5. Grow a fourth layer of n-InP for 15 minutes.

Above, n-InP/n-InP/I for APD
A conventional vapor phase growth apparatus was explained using an nGaAsP/InGaAs four-layer structure as an example, but the following problems were encountered.

The (+) vapor phase growth method is a method in which a gas produced by chemically reacting each metal source with a halogen-based gas or the like is transported by a carrier gas to grow crystals. Therefore, it is necessary to create a sufficient amount of gas in advance by chemically reacting each metal source with a rogen-based gas or the like.

This preliminary work accounts for a large proportion of the time required for the entire process, even when growing a single crystalline sea urchin, and was the cause of the greatest reduction in work efficiency in conventional vapor phase growth methods. This can be said for all types of crystal growth using vapor phase growth, but for example, in the process of step], metal source 1
HCt gas was flowed for about 25 minutes to saturate 0 and 8 with chloride gas, but if the growth occurred before being saturated with chloride gas, the amount of chloride gas produced fluctuated during growth and the growth layer The chemical composition of the layer changes in the growth direction, deteriorating the crystallinity of the grown layer. Note that this step is performed using the above-mentioned n -InP/n
-InP/InGaAsP/InGaAs It occupies about 1/4 of the time required to grow a four-layer structure, and even when growing a large number of crystal wafers in succession, it is necessary each time, so it is difficult to use wafers by vapor phase growth. - When mass-producing a product, work efficiency was significantly reduced.

(II) Furthermore, n-InP/n can be grown using conventional growth equipment.
-InP/InGaAsP/InGaAs four-layer structure, two or more types of group elements (e.g., AL
, Gg, Jrl, etc.) and a binary compound semiconductor layer (e.g., GaAs,
When crystal-growing a multilayer film containing at least one layer of Garb, InP, etc., the following problems particularly occur.

(1) In order to make the n-TnP third layer and the n-InP fourth layer into crystals that are lattice-matched to the InP substrate 1, the Ga source is removed from the second growth chamber 6 and a growth chamber dedicated to InP is provided. There was a problem that I had to do it. Second
The first reason why lattice matching cannot be achieved when a Ga source is placed in the growth chamber 6 is that the Ga CL
Gas is produced and reacts with PI (3 gases, Tn, -q
This is because it contaminates the Evitaginyar Formation in the form of Gaq P (q is a trace amount). The second reason why lattice matching cannot be achieved is that GaCA gas, which was saturated and dissolved in the Ga source, is eluted and diffused into the growth chamber, and as a result reacts with PH3 gas during the growth of the third and fourth layers, causing the same Ink and GaqPO types should not be mixed into the epitaxial layer.

Therefore, although providing a dedicated chamber for InP improves lattice matching, it
The nGaAsP second layer must be grown in the same growth chamber, which significantly reduces work efficiency. That is, the preparation for waiting the substrate 1 in the second growth chamber 6 in step 3-2 and the preparation for waiting the substrate 1 in the second growth chamber 6 in step 4-1.
for about 15 minutes until the source gas in the first growth chamber 5 reaches a steady state.
The minute loading step is an unnecessary process unless a dedicated InP growth chamber is provided, and exposing the crystal wafer to high temperatures for a long period of time causes lattice defects to easily form, which deteriorates the crystallinity of the crystal wafer. This could be a factor.

(2) n7-InP/n-1nP/In
GaAs 1st layer InGaAs 4-layer structure grown”
-, the larger the difference in gearia concentration between n7TnP and n-InP, the higher the guard ring effect of APD becomes, which is desirable in terms of device characteristics. There is a problem in that when these are continuously grown in the same growth chamber, the difference in carrier concentration does not become large. This is because the doping gas H2S used during the growth of the third layer remains in the second growth chamber 6 even when the valve of the doping tube 15 is closed, and is incorporated into the crystal during the growth of the fourth layer.
This is for the purpose of

Therefore, the doping gas H2S is 3 cc-mm-'
.

When flowing, the carrier concentrations of the n-InP third layer and the n-InP fourth layer are 2 x 10"cm" and 1 x 1.016 cm-3, respectively, and the n-InP fourth layer
It was not possible to reduce the carrier concentration of the layer to a minimum value (0.5×10 16 α−3) determined by background impurities inherent in the growth apparatus.

As mentioned above, conventional vapor phase growth equipment has many problems with the process unique to vapor phase growth, which involves chemically reacting the metal source used for crystal growth with nitrogen-based gas, etc., and bringing the resulting gas into a saturated state. There is a problem in that it takes time and reduces work efficiency.

Furthermore, conventionally, when growing a multilayer film including at least one layer of a mixed crystal compound semiconductor layer and a binary compound semiconductor layer each composed of two or more types of group Ⅰ elements, crystalline sea urchins,
・There are concerns about deterioration in the quality of -, poor controllability of carrier concentration, which affects device characteristics, and decreased work efficiency due to the need to provide a dedicated growth chamber for growing binary compound semiconductor layers. there were.

(Object of the Invention) The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is aimed at improving the efficiency of the work specific to the vapor-phase epitaxial growth method using a vapor-phase epitaxial growth apparatus, and furthermore, to When crystal-growing a specific multilayer film containing an original compound semiconductor layer, the crystal can be grown so that lattice matching can be achieved between the substrate and the binary compound semiconductor layer. It is an object of the present invention to provide a vapor phase epitaxial growth apparatus that does not require a chamber, has good controllability of the carrier concentration, and can grow a large number of individual crystal wafers with high efficiency.

(Structure and operation of the invention) A feature of the present invention for achieving this object is that in a vapor phase epitaxial growth apparatus in which the growth chamber has at least two source tubes and is composed of at least one of the growth chambers, the source tube The temperature control function is provided in the vicinity of the source section of each of the two, and the temperature control function is configured to be able to be controlled independently.

The present invention will be described in detail below using the drawings.

FIG. 2 is an embodiment of a vapor phase epitaxy/Yano V growth apparatus according to the present invention. In the figure, 20, 21, 22, and 23 are fast heating and cooling furnaces that control the temperature near the source portion of the source tube. This fast heating and cooling furnace 20°21,2
2, 23 Electric furnace 16 that controls the temperature of a part of the beam actor
The temperature rise/fall rate is approximately ±100°C/sec. In addition, this fast heating and cooling furnace 20
, 21 , 22 , and 23 (hereinafter referred to as "furnaces") have a structure that does not affect adjacent furnaces due to heat induction. In addition, each source tube has an insulating structure between the source part and the growth chamber that suppresses heat conduction and heat radiation to prevent the temperature of the gas itself from decreasing due to heat loss and condensation of the chloride gas. There are many.

FIG. 3(a) is a cross-sectional view of the heat insulating structure, in which the source tube (hereinafter referred to as "inner tube") 25 is surrounded by a glass tube (hereinafter referred to as "outer tube") made of the same material as the inner tube 25 and having a larger diameter. )19
They are arranged concentrically and have a double structure with both ends sealed. In addition, the hollow portion of the inner pipe 25 and the outer pipe 19 is the exhaust pipe 2.
The atmosphere is evacuated from 6 to create a vacuum state, and this vacuum state prevents heat conduction.

Furthermore, a reflective film 27 is coated on the outer wall of the inner tube 25 to prevent heat radiation. Such a heat insulating structure is applied to each source tube 7, 9, 12 and 17.

FIG. 3(b) is a schematic diagram of a heat insulating structure using a heat pipe 28, in which the heat pipe 28 is spirally wound around the outer circumference of the inner tube 25. Incidentally, heat pipes 28 are also provided in each of the source tubes 7, 9, 12, and 17 in the same manner.

Next, as in the conventional example, n-InP/n-
The growth procedure using the growth apparatus according to the present invention will be explained by taking an InP/InGaAsP/InGaAs four-layer structure as an example. Note that for parts of the same procedure as in the conventional example, only the step numbers are given, and the details are omitted.

Step 1: Can be omitted in the present invention.

In the present invention, once the metal source is saturated with chloride gas, the saturated state can be frozen by rapidly cooling the temperature of each metal source in each furnace. This is because it is no longer necessary.

In other words, this step 1 is an operation specific to vapor phase growth using a vapor phase epitaxial growth apparatus, and by omitting this step, the operating efficiency is greatly improved.

Step 2: 5 minutes before the start of growth 2-4. The first In source 10 and the first Ga source 8 are heated to a high temperature of 830° C. 1 using the furnace 22 and the furnace 23, and HCt gas is passed through them.

Step 3: Growth of InGaAs first layer 3-1.
Grow for 15 minutes as before.

3-2. Five minutes before the end of the first layer growth, the temperature of the second In source 13 and the second Ga source 18 is rapidly heated to 830° C. in the furnace 20 and the furnace 21.

3-3. HCt gas is caused to flow through the second In source tube 12 and the second Ga source tube 17.

3-4. PHa and A in the 2V group hydride gas introduction pipe 14.
Flow a mixed gas of SH3 gas.

Steps 3-2 to 3-4 5 minutes before the end of the first layer growth are InG
This is a preparatory work for growing the aAsP second layer in the second growth chamber 6, and was not included in the conventional process.

In other words, conventionally, the first and second layers could only be grown in the same growth chamber, making it impossible to prepare in advance for growing the second layer, and transferring the substrate 1 to another growth chamber after the first layer was grown. Standby (1
5 minutes) and did these preparations. Therefore,
In the present invention, the conventional step 4 can be omitted, so
Work efficiency is improved.

Step 4: End of first layer growth, start of fifth layer, and is omitted in the present invention for the reasons mentioned above.

Step 5: Growth of InGaAsP second layer 5-1.
The substrate 1 is moved to the second growth chamber 6 and grown for 15 minutes. Conventionally, the growth is performed in the first growth chamber 5, and during this period preparations are made to grow the third and fourth layers in the second growth chamber 6, which is a growth chamber dedicated to InP. Since this method does not require a growth chamber, the subsequent steps are slightly different from conventional methods.

5 2, 8! ! Rapidly cool the I Ga source 8 to room temperature in the furnace 23, and stop the HCt gas in the first Ga source tube 7 and the AsH3 gas in the lv group hydride gas introduction tube 110 5-3. The flow rate of HCA gas in the first Insuance pipe 9 is changed.

5-4. PH3 is passed through the first group V hydride gas introduction pipe 11.

5-5. The flow rate of H2 carrier gas flowing into the first growth chamber 5 is changed.

5-6. Immediately before the second layer growth is completed, the first doping tube 24
Flow H2S gas from the

The above steps 5-2 to 5-6 are performed in the first growth chamber 5 with n-I
This is advance preparation for growing the nP third layer.

Step 6: 1- Growth of InP third layer 6-1. The substrate l is moved to the first growth chamber 5.

6-2. The second Ga source 18 is rapidly cooled to room temperature in the furnace 21, and the HCt gas in the second Ga source tube 17 and the A8H3 gas in the Group 2 hydride gas introduction tube 14 are stopped.

By rapidly cooling the first Ga source 8 to room temperature in this step and step 5-2, the n-InP third layer and n'-
- When growing the fourth InP layer, the influence of GaCl gas, which was a cause of lattice mismatch, can be almost ignored. That is, conventionally, the problem of lattice mismatch was solved by removing the Ga source in the second growth chamber 6 and making it a dedicated InP chamber, but in this embodiment, the first G source in the first growth chamber 5
By rapidly cooling the source 8 to room temperature (step 5-2), the unreacted HCl gas from the first In source 10 is removed. Chemical reaction with the F i Ga source 8 is suppressed.

Therefore, in the present invention, crystal growth with lattice matching can be performed without providing a dedicated growth chamber for InP.

6-3. A third InP layer is grown for 5 minutes.

6-4. HCL gas in the second In source tube 12 and the second In source tube 12
The PH3 gas flow rate of the group hydride gas inlet pipe 14 is changed.

6-5. Change the carrier gas current in the second growth chamber 60H2. Note that the steps 6-4 and 6-5 are preliminary preparations for growing the fourth layer in the second growth chamber 6, and this preliminary preparation can be completed while the third layer is being grown for 5 minutes.

Step 7: Growth of the fourth layer of n-InP (conventionally, this is a step that was performed continuously after the third layer was completed in step 6.) Step 7 - 1. Move the substrate 1 to the second growth chamber 6 .

7-2. I) The first In source 10 is rapidly cooled to room temperature using the furnace 22, and the HCt gas in the first In source tube 9 and the PH3 gas in the Group 1V hydride gas introduction tube 11 are stopped.

7-. 3. A fourth n-InP layer is grown for 15 minutes.

As in step 6, when growing the fourth layer, the Gg source 18 in the second growth chamber 6 is rapidly cooled to room temperature.
Crystal growth with good lattice matching with the engineered nP substrate 1 can be achieved. In addition, the difference in carrier and solubility between the n--InP fourth layer and the n-InP third layer is the minimum that can be achieved with this growth apparatus, since the third and fourth layers can be grown in separate growth chambers. Value (0,5x
10"cm").

Step 8: After completion of 4th layer growth 8-1. Pull out the board 1.

8-2. The 21n source 13 is rapidly cooled down to room temperature by the furnace 20, and the HCt gas in the second In source tube 12 is stopped. The process of step 8 is intended to omit the conventional process of step 1 when a large number of crystal wafers are continuously grown.

In the example described above, n-InP/n-InP
/ InGaAs P / InGaAs Although the crystal growth of the four-layer structure has been explained, it is important to understand that two or more types of group III elements (
For example, a mixed crystal compound semiconductor composed of 〃-Ga, In, etc.) and a binary compound semiconductor layer (for example, GaAs, In, etc.).
This applies to the vapor phase growth of a multilayer film containing at least one layer of (Garb, InP, etc.), and the vapor phase growth method can also be applied not only to the above-mentioned hydride method but also to the chloride method.

Furthermore, although this embodiment describes a vapor phase growth apparatus consisting of two growth chambers, it is sufficient to have one or more growth chambers.
Moreover, it can be applied to all vapor phase growth apparatuses in which one growth chamber has at least two source tubes.

(Effects of the Invention) As described above, using the vapor phase growth apparatus according to the present invention,
I explained the growth process of the layered structure, but normally it takes about 80 to 90 divisions to grow one sheet of this four-layered structure.
In the present invention, the process of saturating the second and subsequent metal sources with chloride gas (step 1), which takes about 20 minutes, and the waiting process (step 4), which takes about 15 minutes, can be omitted. The time required for conventional growth can be reduced by over 1/3, and work efficiency can be significantly improved. Furthermore, there is no need to provide a growth chamber exclusively for InP, and the problem of Ga contamination is eliminated, so the degree of freedom in the multilayer structure that can be realized with the vapor phase growth apparatus according to the present invention is extremely large. Furthermore, the controllability of the carrier concentration, which influences the characteristics of the device, is also improved, making it possible to grow high-quality crystals for devices.

As described above, the present invention not only improves the work efficiency inherent in vapor phase growth using a conventional vapor phase epitaxy growth apparatus, but also makes it possible to grow a compound semiconductor multilayer film with good crystal properties in the crystal growth of a specific multilayer film. In addition, crystal wafers with excellent properties for making optical devices can be mass-produced, and the effect is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a schematic longitudinal sectional view of a conventional hydride vapor phase growth apparatus, Fig. 2 is a longitudinal sectional view showing the schematic structure of the hydride vapor phase growth apparatus according to the present invention, and Figs. 3(a) and 3(b) are FIG. 3 is a diagram showing a heat insulation structure between a metal source and a growth chamber. 1... InP substrate, 2... substrate holder, 3...
■Hydrogenated gas introduction pipe for preheating, 4...preheating area, 5.
6...1st and 2nd growth chamber, 7.17...1st and 2nd G
a source tube, 8th, 18th...] and a second Ga source,
9.12...first and second In source tubes, 10, 13
...1st and 21n sources, 11, 1.4...1st and 2nd group hydride introduction pipes, 15, 24...2nd
and 1st Dorvi/G tube, 16...Reactor part electric furnace, 1
9...Outer tube, 20.22.Fast heating and cooling furnace for second and 11th n source, 21, 23...Fast heating and cooling furnace for second and first Ga source, 25...Inner tube, 26... Exhaust pipe,
27... Reflective film, 28. Heat pipe.

Claims (1)

[Claims] In a vapor phase epitaxial growth apparatus equipped with a growth chamber having at least two source tubes, each of the source tubes is provided with an individual temperature control function near the source, and each of the temperature control functions is configured to be independently controllable. A vapor phase epitaxial growth apparatus characterized by: