JPH0697081A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE:To provide a vapor growth apparatus capable of forming a crystalline thin film with high quality and reproducibility through a substrate surface concerning the vapor growth apparatus. CONSTITUTION:In a bubbler 101, a reactant gas is generated by a carrier gas supplied from the outside and a liquid material 102 stored in the inside. In the bubbler 101, a pressure detector 107 is directly installed and a pressure of the reactant gas is detected. A pressure controller 108 directs instructions to a pressure control valve 109 according to the pressure detected by the pressure detector 107 and thereby the pressure of the reactant gas is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase growth apparatus, and more particularly to a vapor phase growth apparatus for forming a crystalline thin film in a semiconductor material or the like.

Recently, as a method for forming a crystalline thin film in a semiconductor material or the like, MOCVD (Metalorganic Che
The crystal growth method based on the mical vapor deposition method is often used.

This is because the properties of the thin film to be formed can be controlled by adjusting the composition and flow rate of the gas supplied to the reactor, and the vapor phase growth apparatus for realizing this method has a simple structure and is mass-produced. It is suitable for the above, and because the crystal growth progresses pyrolytically, it is possible to epitaxially grow even on the surface of a different substrate.

However, because of the above properties, the quality of the produced semiconductor wafer or the like is greatly affected by the composition of the gas supplied to the reaction furnace and the adjustment accuracy of the flow rate.

Therefore, it has been desired to provide a vapor phase growth apparatus in which the composition and flow rate of the gas supplied to the reaction furnace can be adjusted with high accuracy.

[0006]

2. Description of the Related Art FIG. 4 shows an example of a conventional vapor phase growth apparatus, which is a first reaction gas supply system 1 using hydrogen as a carrier gas.
00 and a second reaction gas supply system 200, a dilution gas supply system 300, and a reaction furnace system 400 for thinning a mixed gas of each reaction gas supplied from these gas supply systems by thermal decomposition. .

Next, the configuration and operation of the two reaction gas supply systems will be described. Since both have the same configuration and operation, only the first reaction gas supply system will be described. It should be noted that the reference numerals shown in parentheses immediately after the reference numerals in the first reaction gas supply system indicate the portions that perform the same operation in the second reaction gas supply system.

The bubbler 101 (201) is the main part of the first reaction gas supply system 100 (200). Bubbler 10
1 (201) has a relatively high vapor pressure near room temperature
Liquid raw material 102 (20) such as alkylated group III element
2) is held inside.

In the bubbler 101 (201), a carrier gas such as hydrogen supplied from the outside through the carrier gas supply pipe 103 (203) and the liquid raw material 102 (2).
02) is combined with to generate a reaction gas, which is supplied to the reaction furnace system 400.

At this time, in order to precisely control the concentration of the compound in the reaction gas, the carrier gas and the liquid raw material 1
02 (202) temperature, carrier gas inflow pressure (hereinafter referred to as “primary pressure”), bubbler 101 (20
1) Pressure of the reaction gas inside (hereinafter, “secondary pressure”)
It is necessary to adjust each of the above).

Therefore, the carrier gas and the liquid raw material 1
02 (202) to regulate the temperature
(204) is provided. The constant temperature bath 104 (204) is filled with the constant temperature holding liquid 105 (205), and is configured to always maintain the same temperature by a temperature stabilizing means (not shown).

Since the bubbler 101 (201) is constantly immersed in the constant temperature holding liquid 105 (205) holding the same temperature, the carrier gas and the liquid raw material 1
The temperature of 02 (202) is the temperature of the constant temperature holding liquid 105 (20
It can be controlled by adjusting the temperature of 5).

A mass flow controller 106 (206) is provided at the inlet of the carrier gas supply pipe 103 (203) in order to adjust the primary pressure. Therefore, the primary pressure is the mass flow controller 106.
It can be controlled by adjusting (206).

Further, in order to adjust the secondary pressure, 2
A pressure detector 107 (207) for detecting the secondary pressure and a pressure control device 1 for instructing the secondary pressure to be a predetermined pressure.
08 (208) and a pressure control valve 109 (209) that controls the outflow amount of the reaction gas to the reaction furnace system 400 based on an instruction from the pressure control device 108 (208).

The pressure detector 107 (207) is connected in the middle of the reaction gas supply pipe 110 (210), and the
Measure the next pressure. The measured current secondary pressure is communicated to the pressure controller 108 (208). Pressure control device 1
08 (208) instructs the pressure control valve 109 (209) to close or open the valve so that a predetermined secondary pressure is obtained.

As described above, the first reaction gas supply system 10
0 and the second reaction gas supply system 200 are controlled to determine the mixing ratio of the first reaction gas and the second reaction gas.

Further, the dilution gas supply system 300 sets the concentration of the entire reaction gas by adjusting the mass flow controller 301 to control the outflow amount of the carrier gas to the reaction furnace system 400.

In the reaction furnace system 400, the first reaction gas and the second reaction gas supplied from the first reaction gas supply system 100, the second reaction gas supply system 200, and the dilution gas supply system 300, respectively. Reactor 4 using gas and diluent gas
Fill 01 and mix.

Inside the reaction furnace 401 is provided a heater 403 on which a substrate 402 for growing a crystal film is placed. The temperature of the heater 403 is controlled by a temperature control device 404 provided outside the reaction furnace 401.

Therefore, a predetermined crystalline thin film is formed on the surface of the substrate 402 by heating the substrate 402 by the heater 403 and thermally decomposing it while the reaction furnace 401 is filled with the reaction gas.

[0021]

However, in the above-described conventional vapor phase growth apparatus, a pressure detector for detecting the secondary pressure is connected to the reaction gas supply pipe to control the pressure of the reaction gas flowing out to the outside. Since it has been detected, there is a problem that the secondary pressure including the pressure drop due to the outflow of the reaction gas is detected, and the value is slightly different from the secondary pressure inside the bubbler, which is the object of detection.

Therefore, the accuracy of the concentration of the compound of the carrier gas and the liquid raw material in the reaction gas generated in the reaction gas supply system is lowered, and the quality of the crystalline thin film formed on the substrate surface is lowered. However, there is a problem that it is difficult to form a crystalline thin film having the same crystal composition.

The present invention has been made in view of the above points, and a gas phase capable of forming a high-quality crystalline thin film on the substrate surface by strictly detecting the secondary pressure inside the bubbler. The purpose is to provide a growth apparatus.

[0024]

FIG. 1 shows the principle of the vapor phase growth apparatus according to the present invention.

In the figure, the carrier gas supply pipe 103 has a mass flow controller 106, and the mass flow controller 106 controls the supply amount of the carrier gas. The bubbler 101 stores a liquid raw material 102 inside, and is supplied with a carrier gas from the carrier gas supply pipe 103 to generate a reaction gas.

The pressure detector 107 detects the pressure of the generated reaction gas. The reaction gas supply pipe 110 has a reaction gas flow rate control unit 111, and the reaction gas flow rate control unit 111 supplies the reaction gas to the reaction furnace 401 based on the pressure of the reaction gas detected by the pressure detector 107. Make the supply constant.

In the present invention, the pressure detector 107 is used.
Is directly attached to the bubbler 101.

[0028]

According to the above construction, since the pressure detector is directly attached to the bubbler, the pressure of the reaction gas can be strictly detected. Therefore, compared with the case where the pressure detector is connected to the reaction gas supply pipe, the accuracy of the concentration of the compound of the carrier gas and the liquid raw material in the reaction gas can be increased.

[0029]

EXAMPLE FIG. 2 shows an example of the vapor phase growth apparatus according to the present invention. In the figure, the same components as those in FIGS. 1 and 4 are designated by the same reference numerals, and the description thereof will be omitted. Also, 10
0a is a first reaction gas supply system, 200a is a second reaction gas supply system, 103a and 203a are temperature stabilization pipes, 112 and 212 are vacuum pumps, 113 and 213 are carrier gas introduction pipes. , Respectively.

Also in FIG. 2, the first reaction gas supply system 100a and the second reaction gas supply system 200 are almost the same as the conventional one.
a, a diluent gas supply system 300 and a reaction furnace system 400.

Then, the first reaction gas supply system 100a,
Second reaction gas supply system 200a, dilution gas supply system 300
Is supplied with hydrogen as a carrier gas.
In the first reaction gas supply system 100a and the second reaction gas supply system 200a, respective liquid raw materials are vaporized in hydrogen to form a reaction gas, which is the dilution gas supply system 30.
After being mixed with hydrogen from 0, it is fed to the reactor system 400.

In the reaction furnace system 400, the reaction gas mixed as described above is pyrolyzed by the heater 403 provided inside the reaction furnace 401, and a crystalline thin film is formed on the surface of the substrate 402 mounted on the heater 403. Let it form.

Next, the structure and operation of the first reaction gas supply system 100a will be described. Since the first reaction gas supply system 100a and the second reaction gas supply system 200a have the same configuration except for the liquid raw material, only the reference numerals of the second reaction gas supply system 200a are shown and the description thereof is omitted.

A carrier gas supply pipe 103 (20) for feeding hydrogen as a carrier gas into the bubbler 101 (201).
Part of 3) is a temperature stabilizing pipe 103a (203a).
Is provided and is immersed together with the bubbler 101 (201) in the constant temperature holding liquid 105 (205) which is kept at a constant temperature by the constant temperature bath 104 (204).

Further, the bubbler 1 is installed in parallel with the pressure detector 107 (207) directly attached to the bubbler 101 (201).
01 (201) vacuum pump 112 for discharging the gas
(212) and hydrogen, which is a carrier gas, are directly attached to the portion 10
Carrier gas introduction pipe 1 introduced into 7a (207a)
13 (213) is connected to the bubbler 101 (201).

Since there is a pipe for supplying hydrogen to the dilution gas supply system 300, a total of five pipes are provided for supplying hydrogen.

A reaction gas supply pipe 110 (210) is connected to the bubbler 101 (201).
The reaction gas generated in (201) is fed into the reaction furnace system 400. The reaction gas supply pipe 110 (210) is provided with a pressure control valve 109 (209) so that the outflow amount of the reaction gas to the reaction furnace system 400 is controlled to be constant.

That is, the pressure in the bubbler 101 (201) detected by the pressure detector 107 (207) is transmitted to the pressure control device 108 (208). Pressure control device 1
08 (208) is a pressure control valve 10 based on this pressure.
9 (209) is adjusted so that the outflow amount of the reaction gas into the reaction furnace system 400 becomes constant.

In the dilution gas supply system 300, the mass flow controller 301 controls the outflow amount of hydrogen to the reactor system 400 to be constant.

As described above, the first reaction gas supply system 100
a, second reaction gas supply system 200a, dilution gas supply system 3
The gas supplied from 00 so that the outflow amount becomes constant is in a mixed state in the reaction furnace 401.

A heater 403 on which a substrate 402 is placed is enclosed in the reaction furnace 401, and is heated to a constant temperature by a temperature control device 404 outside the reaction furnace 401.

Therefore, the reaction gas mixed in the reaction furnace 401 is thermally decomposed by the heater 403, and the substrate 4
A crystalline thin film grows on the surface of 02.

The structure, operation and effect of the main part of the present invention are as follows.

First, the pressure detector 107 (207) is directly connected to the bubbler 101 (201) instead of being connected to the reaction gas supply pipe 110 (210).

Thus, the pressure in the bubbler 101 (201) can be directly detected without detecting the secondary pressure including the pressure drop caused by the outflow of the reaction gas as in the conventional case. It became possible to measure the pressure precisely.

Therefore, by using the pressure value strictly measured as described above, the accuracy of the concentration of the compound of the carrier gas and the liquid raw material in the reaction gas is increased to improve the quality of the crystalline thin film formed on the substrate surface. The reproducibility can be improved more than ever before.

Second, the carrier gas supply pipe 103 (20
The temperature stabilizing pipe 103a (203a) is provided in a part of 3), and the temperature-controlled bath 104 together with the bubbler 101 (201).
Constant temperature holding liquid 10 kept at a constant temperature in (204)
5 (205).

As a result, the carrier gas supplied to the bubbler 101 (201) is cooled by the temperature stabilizing pipe 103a.
Liquid raw material 10 which is heated (or cooled) when passing through (203a) and is always held in bubbler 101 (201) when entering into bubbler 101 (201).
2 (202) and almost the same temperature.

Therefore, the carrier gas is bubbler 101.
Since there is no heat exchange when entering (201), there is no fluctuation in the saturated vapor pressure in the bubbler 101 (201), that is, fluctuation in the pressure of the reaction gas, and the quality of the crystalline thin film formed on the substrate surface is reproduced more than before. It can be improved with good performance.

Thirdly, the pressure detector 107 (207) and the bubbler 101 (201) are directly attached to each other 107a (207).
Vacuum pump 112 for forcibly discharging the gas in a)
(212) and the carrier gas introduction pipe 113 (21) for introducing the carrier gas into the direct attachment portion 107a (207a).
3) is included.

As described above as the first main part, by directly attaching the pressure detector 107 (207) to the bubbler 101 (201), the pressure inside the bubbler 101 (201) can be strictly measured.

However, this direct mounting portion 107a (2
In 07a), no gas flow occurs, so that impurity gas such as the outside air that has entered when the bubbler 101 (201) is replaced is retained, which adversely affects the inside of the reactor during operation of the device. New problems arise.

Therefore, as described above, the vacuum pump 112
(212) and the carrier gas introduction pipe 113 (213) are provided and operated as described below to remove the impurity gas accumulated in the direct attachment part 107a (207a).

FIG. 3 is a diagram showing a processing flow of the vacuum pump of FIG. In the figure, the same components as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. Also, 10
-19 show each step number, and in the following explanation, the step number is described in parentheses in the corresponding explanation.

In FIG. 3, the pressure detector 107 (20
7) The pressure detector 107 (207) is closed by closing all the valves of the pipes connected to the direct attachment part 107a (207a).
And the direct attachment part 107a (207a) is isolated from other parts. Then, only the valve between the vacuum pump 112 (212) and the vacuum pump 112 (212) is opened, and the pressure detector 107 (207) and the direct attachment portion 107a (207a) and the vacuum pump 112 are opened.
The connection with (212) is established (11).

Next, the vacuum pump 112 (212) is operated to operate the pressure detector 107 (207) and the direct mounting part 1.
The gas in 07a (207a) is discharged (12). The pressure is detected by the pressure detector 107 (207) during the discharge, and the vacuum pump 112 is kept until the pressure becomes a predetermined pressure or less.
The gas discharge according to (212) is continued (13).

As a result, the pressure detector 107 (20
7) and the impurity gas that may remain in the direct attachment portion 107a (207a) can be discharged.

When it is confirmed that the pressure inside the pressure detector 107 (207) and the direct attachment portion 107a (207a) has become lower than a predetermined pressure, the pressure detector 107 (207) and the direct attachment portion 107a (207a) and the vacuum are removed. Pump 112 (2
12) and the valve between the pressure detector 107 (2)
07) and the direct attachment part 107a (207a) and the vacuum pump 112 (212) are disconnected, and the vacuum pump 112 (212) is stopped (14).

Then, the valve between the pressure detector 107 (207) and the direct mounting portion 107a (207a) and the carrier gas introducing pipe 113 (213) is opened to open the pressure detector 107 (207) and the direct mounting portion. 107a (207
The inside of a) and the carrier gas introduction pipe 113 (213) are connected (15), and the carrier gas is supplied to the pressure detector 107.
(207) and the direct attachment portion 107a (207a). This is continued until the pressure value detected by the pressure detector 107 (207) becomes a predetermined value or more (1
6).

As a result, the pressure detector 107 (20
7) and the inside of the direct attachment portion 107a (207a) are filled with a carrier gas containing no impurity gas.

When the pressure exceeds a predetermined value, the pressure detector 10
7 (207) and the valve between the direct attachment part 107a (207a) and the carrier gas introduction pipe 113 (213) are closed, and the pressure detector 107 (207) and the direct attachment part 1 are connected.
07a (207a) and carrier gas introduction pipe 113 (2
13) and the pressure detector 107 (20
7) and the inside of the direct attachment portion 107a (207a) and the bubbler 1
01 (201) and open the valve, pressure detector 107
(207) and the direct attachment portion 107a (207a) and the bubbler 101 (201) are connected (17).

In this way, the pressure detector 107 (20
7) and the inside of the direct attachment portion 107a (207a) filled with a carrier gas containing no impurities,
The bubbler 101 (201) is put into a normal operating state and operated as a vapor phase growth apparatus (18).

Therefore, before starting the operation of the apparatus, all the gas in the direct attachment part 107a (207a) is once exhausted,
After that, the carrier gas is directly attached to the portion 107a (207a)
By directly flowing into the inside, the direct attachment part 107a (207
The inside of a) can be cleaned and initialized. For this reason,
It is possible to prevent the yield of the crystalline thin film produced by the impurity gas such as the outside air accumulated in the direct attachment portion 107a (207a) from being lowered, and the productivity can be improved.

[0064]

As described above, according to the first aspect of the invention, the concentration of the compound of the carrier gas and the liquid raw material in the reaction gas is higher than that in the case where the pressure detector is connected to the reaction gas supply pipe. Since the accuracy can be increased, the quality of the crystalline thin film formed on the surface of the substrate can be improved more reproducibly than before.

According to the second aspect of the present invention, the carrier gas reaches the same temperature as the liquid raw material while passing through the temperature stabilizing pipe, and heat exchange is not performed when entering the bubbler. There is a feature that the fluctuation of the saturated vapor pressure due to the exchange, that is, the fluctuation of the pressure of the reaction gas can be eliminated, and the quality of the crystalline thin film formed on the substrate surface can be improved more reproducibly than before.

According to the third aspect of the invention, before the operation of the apparatus is started, the gas in the directly attached portion of the pressure detector and the bubbler is completely exhausted, and then the carrier gas is introduced into the directly attached portion. By doing so, the inside of the direct attachment part can be cleaned and initialized, so that it is possible to prevent the yield of the crystalline thin film produced by contaminating the inside of the reaction furnace due to the impurity gas accumulated in the direct attachment part from decreasing. The advantage is that productivity can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of a vapor phase growth apparatus according to the present invention.

FIG. 2 is a diagram showing an embodiment of a vapor phase growth apparatus according to the present invention.

FIG. 3 is a diagram showing a processing flow of the vacuum pump of FIG.

FIG. 4 is a diagram showing an example of a conventional vapor phase growth apparatus.

[Explanation of symbols]

 100a 1st reaction gas supply system 200a 2nd reaction gas supply system 300 Diluting gas supply system 101,201 Bubbler 102,202 Liquid raw material 103,203 Carrier gas supply pipe 103a, 203a Temperature stabilization piping 104,204 Constant temperature bath 105, 205 Liquid for holding constant temperature 106, 206, 301 Mass flow controller 107, 207 Pressure detector 107a, 207a Direct attachment part 108, 208 Pressure control device 109, 209 Pressure control valve 110, 210 Reactive gas supply pipe 111 Reactive gas flow rate control Means 112,212 Vacuum pump 113,213 Carrier gas introduction pipe 400 Reaction furnace system 401 Reaction furnace 402 Substrate 403 Heater 404 Temperature control device

Claims (3)

[Claims] 1. A carrier gas supply pipe (103, 203) having a mass flow controller (106, 206) for controlling a supply amount of a carrier gas, and a liquid raw material (102, 202) stored therein. A bubbler (10) which is supplied with a carrier gas from a gas supply pipe (103, 203) and generates a reaction gas
1, 201), a pressure detector (107, 207) for detecting the pressure of the generated reaction gas, and a reaction furnace based on the pressure of the reaction gas detected by the pressure detector (107, 207). A reaction gas supply pipe (110, 110) having a reaction gas flow rate control means (111) for making the supply amount of the reaction gas to (401) constant.
210), the pressure detector (107, 207) is connected to the bubbler (10).
1, 201) directly attached to the vapor phase growth apparatus. 2. The carrier gas supply pipe (103, 20)
3) a temperature stabilizing pipe (103a, formed in a part of
203a), and the bubbler (101, 201) and the temperature stabilizing pipes (103a, 203a) are connected to a constant temperature bath (104, 20).
4) The constant temperature holding liquid (10
The vapor phase growth apparatus according to claim 1, wherein the vapor phase growth apparatus is configured to be dipped in the substrate. 3. A direct attachment part (107a,) between the pressure detector (107, 207) and the bubbler (101, 201).
Vacuum pumps (112, 212) for forcibly discharging the gas in 207a) and carrier gas introduction pipes (113, 21) for flowing the carrier gas into the direct attachment parts (107a, 207a).
3), the direct attachment part (107)
a, 207a) the gas in the vacuum pump (112, 2)
12) and then the carrier gas is introduced by the carrier gas introducing pipes (113, 213) into the direct attachment part (107a, 2).
The vapor phase growth apparatus according to claim 1, wherein the vapor phase growth apparatus is configured to flow into the inside of 07a).