JP2951798B2 - Vapor phase growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for vapor-phase growing a thin film such as an amorphous silicon thin film which is a material for an amorphous silicon solar cell or an amorphous silicon thin film transistor on a substrate surface. A gas decomposition heater unit provided with a gas heater for heating and decomposing a compound gas containing thin film components, which is introduced into a reaction tank for forming a thin film, and a substrate heater for keeping a substrate at a predetermined high temperature. The present invention relates to a configuration of a vapor growth apparatus provided.

[0002]

2. Description of the Related Art Recently, the field of application of thin films has been expanding, especially in the semiconductor industry. Such thin films include amorphous silicon, polycrystalline silicon, silicon oxide, and silicon nitride. In general, a thin film is manufactured using a CVD technique, in which dissociation energy is applied to a compound gas as a raw material to deposit a thin film having an intended composition composed of decomposition products. For example, as a method for producing an amorphous silicon-based thin film, gas molecules of a silane-based source gas are excited using plasma discharge, heat energy or laser, light such as ultraviolet light, decomposed, deposited on a substrate, A method for forming a thin film is known. In addition, when an element other than silicon is added to the material of the thin film to form a compound semiconductor such as a-SiGe: H or a-SiC: H as an amorphous material having a desired optical band gap, a source gas is used. Besides silane (SiH ₄ ), germane (Ge
H ₄ ) or methane (CH ₄ ) is used. When doping the amorphous material with boron or phosphorus, diborane (B ₂ H ₆ ) or phosphine (PH ₃ ) is added to the reaction gas. When a reaction gas obtained by mixing such different types of source gases is used, the source gas is decomposed with energy so that the most difficult to decompose among the source gases can be decomposed. For this reason, a gas having a low decomposition energy cannot be dissociated under optimum conditions, and there is a problem that undesired radicals are generated. In order to solve this problem, as disclosed in Japanese Patent Application No. 2-9799, decomposition energy is given to each raw material gas independently, and each raw material gas is dissociated and decomposed under the most suitable optimum condition, and the substrate gas is decomposed. Research on depositing a thin film to form a thin film has been advanced.

FIG. 8 shows a vapor phase growth apparatus constructed based on the above-mentioned Japanese Patent Application No. 2-9799 as an example of this kind of vapor phase growth apparatus. Inside a reaction tank 1 formed as a vacuum vessel and having a carrier gas inlet 11 and a gas exhaust port 12, a substrate heater 2 for keeping the mounted substrate 3 at a predetermined high temperature is arranged. A plurality of compound gases each containing one component in the thin film formed on the surface of the substrate 3, for example, silane (SiH ₄ ), diborane (B ₂ H ₆ ), methane (CH ₄ )
Gas introduction pipes 51, 52, 53 for feeding
Extend from the gas inlets 41, 42, 43 formed in the ceiling plate of the vacuum vessel 4 provided in the upper part of the reaction tank 1 through the ceiling plate of the reaction tank 1 into the reaction tank 1. Each compound gas is blown onto the substrate 3 from the introduction tube. These compound gases are heated and decomposed by the heating resistance wire 71 wound in a coil shape around the quartz pipe 72 through which the gas introduction pipes 51, 52, and 53 are inserted, and radicals generated by the decomposition are converted as reaction products. The thin film is deposited on the substrate 3 to form a thin film. In the drawing, reference numeral 6 denotes a shielding tube for shielding the heat radiation in the radial direction from the heating resistance wire 71 and preventing diffusion of impurities from the heating resistance wire 71 into the reaction tank 1.
Is a temperature sensor for controlling the temperature of each of the gas introduction pipes 51, 52, 53 to a temperature at which each compound gas is dissociated and decomposed at an optimum temperature, and is a wound heater comprising a quartz pipe 72 and a heating resistance wire 71. 7, the shielding cylinder 6, and the temperature sensor 8 constitute a device body side of a gas decomposition heater unit for decomposing a compound gas at an optimum temperature.

[0004]

As described above, when the compound gas is decomposed at the optimum temperature, and it is attempted to reach the substrate while maintaining the decomposition state, the gas heating of the gas decomposition heater unit is performed near the substrate surface. A heater (in the above-described example, the coil heater 7) is disposed, and the substrate temperature rises due to heat rays such as infrared rays emitted from the gas heater,
Independent control of the substrate temperature by only the substrate heater (2) cannot be performed, and the composition of the thin film deposited on the substrate changes, which is a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to control a substrate temperature independently to a predetermined temperature only by a substrate heater, and to deposit a decomposition product of a compound gas decomposed under an optimum temperature condition on the substrate. An object of the present invention is to provide a configuration of a vapor phase growth apparatus that does not change the composition of a thin film.

[0006]

In order to solve the above problems, the present invention provides a compound containing a thin film component, which is introduced into a reaction tank when a thin film is formed on the surface of a substrate disposed in the reaction tank. A gas phase growth apparatus comprising a gas decomposition heater unit having a gas heater for heating and decomposing gas and a substrate heater for keeping the substrate at a predetermined high temperature is provided. It is assumed that the apparatus is provided with heat shielding means for shielding heat irradiation from the gas heater.

As a specific configuration of a vapor phase growth apparatus based on such a configuration principle, a compound gas is introduced into a reaction vessel through a gas introduction pipe which penetrates a wall surface of the reaction vessel and protrudes into the reaction vessel. The heating unit for gas decomposition is a gas heater, and a heating heater is formed by winding a heating resistance wire in a coil shape around an infrared transmitting pipe through which the gas introduction pipe is inserted as a gas heating heater. A shield tube enclosing in a shape to shield radial heat radiation from the coil heater and preventing diffusion of impurities from the coil heater into the reaction tank; and a temperature sensor for detecting the temperature of the coil heater Wherein the heat shielding means for shielding the substrate from heat irradiation from the gas heater is a plate made of a low thermal conductivity material having a gas inlet through which the gas inlet tube can be inserted. In this case, the compound gas is introduced into the reaction vessel through the gas introduction pipe that penetrates through the wall of the reaction vessel and protrudes into the reaction vessel. In addition, the heating unit for gas decomposition is a heating resistance wire wound in a coil shape in a double cylindrical container in which the gas introduction pipe is inserted as a gas heater and the internal space of which is kept in a reduced pressure state. An infrared heater that seals the infrared heater _, a shielding cylinder that surrounds the infrared heater in a cylindrical shape from the outside to shield radial heat radiation from the infrared heater, and a temperature sensor that detects the temperature of the infrared heater. A heat shielding means for shielding the substrate from heat irradiation from the gas heater, comprising a plate made of a low heat conductive material and having a gas inlet through which the gas inlet tube can be inserted; The device is attached to the end of the gas introduction pipe, or the compound gas is introduced into the reaction vessel through the gas introduction pipe that penetrates the wall of the reaction vessel and protrudes into the reaction vessel. The decomposition heater unit has a built-in heating resistance wire inside a cavity with a mirror surface on the inner wall surface as a gas heater and an opening for drawing out the internal heat to the outside. A hollow heater to be heated, and a heat conducting rod whose inner peripheral surface functions as a total reflection surface for heat, which guides heat going from the opening of the cavity to the outside through the wall surface of the reaction tank to the end face of the gas introduction pipe in the reaction tank. And a temperature sensor for detecting the temperature of the end face of the gas introduction pipe, and it is preferable that the heat guide rod also serves as a heat shielding means for shielding the substrate from heat irradiation from the gas heater.

[0008] Of the above arrangements, the arrangement having a hollow heater is disclosed in Japanese Patent Application No. 3-255599 filed earlier by the present applicant.
This is a configuration described in the specification and is a reference means for the present invention. Further, the above-mentioned prior application discloses that the heat conducting rod is constituted by a metal pipe having an inner surface plated with gold as a heat conducting path. Further, in the above-mentioned prior application, in the case of an apparatus configuration using a plate made of a low heat conductive material as the heat shielding means, the heat shielding means is formed with a concave surface facing the substrate, and a gas inlet is provided in the concave portion. Is formed, and the concave portion is covered by an electrode plate made of a perforated plate or a mesh plate to which a high-frequency voltage is applied. In the present invention, the reaction tank is made of quartz, and a cylindrical member connected to a high-frequency power supply for forming a high-frequency electric field in a space between the plate-shaped heat shielding means and the substrate made of a low thermal conductivity material. The device is configured to be surrounded from outside by the shape electrode.

Here, the cylindrical electrode surrounding the reaction tank is:
It is preferable that the coil is formed by spirally winding the coil.

[0010]

As described above, the apparatus is provided with the heat shielding means for shielding the substrate from heat irradiation from the gas heater between the gas heater and the substrate. Is shielded and the substrate is no longer heated by the gas heater, so that the temperature of the substrate can be controlled solely by the substrate heater alone. Further, since the heat irradiation from the gas heater to the thin film deposited on the substrate is eliminated, a change in the thin film composition due to heating is prevented.

[0011] In order to concretely realize the vapor phase growth apparatus configured as described above, the compound gas is introduced into the reaction tank by introducing a gas that penetrates the wall of the reaction tank and protrudes into the reaction tank. Through the pipe, the heater unit for gas decomposition,
A coil heater formed by winding a heating resistance wire around an infrared transmitting pipe through which the gas introduction pipe is inserted as a gas heater; and a radial heat from the coil heater by surrounding the coil heater in a cylindrical shape from the outside. A shielding tube for shielding radiation and preventing diffusion of impurities from the coil heater into the reaction tank;
A gas inlet configured to use a temperature sensor for detecting the temperature of the coil heater and a heat shielding means for shielding the substrate from heat irradiation from the gas heater is formed so that the gas introduction pipe can be inserted therethrough. Further, when formed from a plate made of a material having a low thermal conductivity and attached to the end face of the gas introduction pipe of the coil heater, the plate-shaped heat shielding means can be used without obstructing the outflow of the compound gas toward the substrate. It can be provided in an arbitrary size in the reaction tank, and has a simple structure compared with the case where multiple reflectors are used as a heat shielding means, and can provide heat shielding even in a state where decomposition products of the compound gas are attached. It can be done effectively.

The introduction of the compound gas into the reaction tank is
The reaction is performed through a gas introduction pipe protruding into the reaction vessel through the wall of the reaction vessel, and the heater unit for gas decomposition is used as a gas heater, and a double cylindrical shape through which the gas introduction pipe is inserted. Heater that seals a heating resistance wire wound in a coil in a container that is kept at a constant temperature _, and radially radiates heat from the infrared heater by surrounding the infrared heater in a cylindrical shape from outside. A gas inlet configured to include a shielding cylinder and a temperature sensor for detecting a temperature of the infrared heater, and a heat shielding means for shielding a substrate from heat irradiation from a gas heater; Formed of a plate made of a low thermal conductive material,
When the infrared heater is attached to the end face of the gas introduction pipe, the impurity gas from the gas heater is confined in a small double cylindrical container and does not flow out into the reaction tank.
Impurity gas diffusion can be extremely reliably prevented, and film formation in a state in which the impurity gas is mixed can be reliably prevented. In addition, since the inner space of the double cylindrical container is kept in a reduced pressure state when the heating resistance wire is not energized, the inside of the container is maintained at a relatively low pressure even when the temperature rises during energization or when impurity gas is released. In addition, the container can be formed relatively lightweight without increasing the wall thickness, and the increase in the apparatus cost is small compared to the case where the diffusion of the impurity gas is prevented by the shielding cylinder.

Further, the introduction of the compound gas into the reaction tank is
While performing through the gas introduction pipe that penetrates the wall of the reaction tank and protrudes into the reaction tank, the heater unit for gas decomposition is
A cavity heater having a built-in heating resistance wire inside a cavity in which an inner wall surface is formed as a mirror surface and an opening for drawing out internal heat to the outside as a gas heater, and which is disposed outside the reaction tank; A heat conducting rod having an inner peripheral surface functioning as a total reflection surface of heat, and a heat conducting rod for guiding heat from the opening of the cavity to the outside through the wall surface of the reaction vessel to the end face of the gas introduction pipe in the reaction vessel; When configured using a temperature sensor that detects the temperature and the heat conducting rod also serves as a heat shielding unit that shields the substrate from heat irradiation from the gas heater, heat irradiation from the gas heater to the substrate is prevented. In addition, it is possible to completely prevent impurity gas from being mixed into the reaction tank from the heating resistance wire, and to obtain a thin film having better film quality.

Further, when the heat conducting rod is constituted by a metal pipe having an inner surface plated with gold as a heat conducting path, heat from the cavity heater is transmitted through the air space in the metal pipe, so that the heat conducting performance of the heat conducting rod and the heat shielding Performance is maintained unchanged. Furthermore, in the case of an apparatus configuration using a plate material formed of a low thermal conductivity material and formed with a gas introduction port through which a gas introduction tube can be inserted as the heat shielding means, the plate material is formed with a concave surface facing the substrate, If the gas introducing port is formed in the concave portion and the concave portion is covered by an electrode plate made of a perforated plate or a mesh plate to which a high-frequency voltage is applied, the gas introducing pipe from the gas introducing tube flowing into the concave portion is formed. The dissociated / decomposed gas flows out of the electrode plate formed of a perforated plate or a mesh plate at a uniform gas density, and a high-frequency voltage is applied to the dissociated / decomposed gas. The dissociation / decomposition gas to which the high-frequency voltage is applied further becomes a plasma state, and the optical band gap of the thin film deposited on the substrate is compared with the case where the gas that does not dissociation / decomposition is directly converted into plasma, as described in detail in the section of Examples. Becomes smaller. Accordingly, by setting the area of the concave portion to a size corresponding to the area of the substrate, a film having better characteristics and a more uniform thickness can be formed on a substrate having a larger area.

Further, the reaction vessel is formed of quartz, and the reaction vessel is surrounded by a cylindrical electrode from the outside so that a high-frequency electric field is formed in a space between the plate-shaped heat shielding means and the substrate. If this is connected to a high-frequency power supply, a large amount of gas molecules converted into plasma in this space will accumulate on the substrate surface and the peripheral wall of the reaction tank far from the substrate surface, and the substrate side of the plate-shaped heat shielding means will be concave. A thin film can be formed with less dust than in the case of forming and covering this concave portion with a porous electrode plate.

Here, if the cylindrical electrode surrounding the reaction tank from the outside is formed by spirally winding the coil, the axial length of the cylinder can be changed by changing the pitch of the spiral or the total length of the coil. Since it can be easily changed, it is possible to extremely easily set the length and the end face position of the electrode for effectively forming the high-frequency electric field between the plate-shaped heat shielding means and the substrate.

[0017]

FIG. 1 shows a first reference example of the present invention. In the drawing, the same members as those in FIG. 7 are denoted by the same reference numerals. Gas introduction pipes 51, 52, 5 for introducing a compound gas into the reaction tank 1.
When the heating temperature is, for example, 600 ° C. or more, a metal tube and a heat-resistant porcelain tube are used as the component 3,
The gas inlet 41, so that the inside of the reaction tank 1 becomes a heat-resistant porcelain tube,
42, 43. The gas heater for thermally decomposing the compound gas sent from the outside into the gas introduction pipes 51, 52, 53 is a wound heater 7 in which a heating resistance wire 71 is wound in a coil shape around a quartz pipe 72 that transmits infrared rays well. The height of the coil is set so that the gas is decomposed at the optimum temperature and most efficiently under the given gas flow rate and gas type. The shielding cylinder 6 is formed by using heat-resistant porcelain, and effectively shields the heat radiated outward from the coil heater 7 in the radial direction even when the decomposition products of the compound gas adhere to the inner and outer peripheral surfaces of the cylinder. Thus, the heating power supplied to the winding heater 7 is efficiently consumed for gas decomposition. Each gas introduction pipe 51,
The gas decomposition heater unit for decomposing the compound gas sent to the 52 and 53 at the optimum temperature is composed of a coil heater 7, a shielding cylinder 6, a temperature sensor 8, and a temperature controller (not shown).

The heat from the wire heater 7 to the substrate is shielded.
The gas introduction pipes 51, 5
A gas inlet that can insert 2, 53 was formed.
l_TwoO _ThreeA heat-resistant porcelain plate made of
It is large enough to prevent irradiation,
Gas introduction pipes on the end face of the gas introduction pipe
It is attached while inserted in the mouth.

The contact surfaces of the shield plate 9 made of heat-resistant porcelain and the shield tube 6 are finished to a smooth flat surface by grinding, and come into contact in a substantially adhered state in the assembled state.
The diffusion of the impurity gas from the reactor 1 into the reaction tank 1 is suppressed. According to the configuration of the present embodiment, the temperature Ta on the upper surface of the substrate heater 2 formed by casting a heating resistance wire into an aluminum ingot.
As a result of measuring the time change after the start of energization to the winding heater 7, as shown in FIG. 2, a high vacuum state (pressure P ₁ = 1 in the reaction tank 1) before the start of energization to the winding heater 7 was obtained as shown in FIG. .33
× 10 temperature Ta of ^-4 [Pa]) is, H ₂ into the reaction vessel 1
100% gas is supplied to the reactor at a pressure of P ₂ = 133 [Pa].
It was confirmed that the maximum temperature change ΔTa = 5 ° C. was small, and the temperature change was small, even after the flow was introduced at the following flow rate and the coil heater 7 was energized.

FIG. 3 shows a second embodiment of the present invention. In this reference example, the gas heater 10 accommodates an infrared lamp in which a filament for a light source is sealed in a vacuum vessel as a heating resistance wire in a cavity 10b formed using a metal plate and having a mirror-finished inner wall surface. The same number of gas introduction pipes 51, 52, and 53 are arranged outside the reaction tank 1. Then, the gas decomposition heater unit for decomposing each compound gas sent into the gas introduction pipe at an optimum temperature, respectively, transmits the heat of the infrared lamp through the cavity heater 10 and the opening formed in the cavity 10b to the gas introduction pipes 51,5.
2 and 53, the inner surface of the metal pipe is plated with gold to form a total reflection surface of infrared rays, and the heat guide rod 20 is sealed with a quartz plug at the end. 52 and 53 are constituted by a temperature sensor 8 for detecting the temperature of the tip portion. The cavity 10 of the cavity heater 10
Cooling water is sent from the outside into the inside of the casing 10a forming the inside b, thereby preventing an excessive rise in temperature on the wall surface of the cavity 10b due to the heat of the infrared lamp.

When the heater unit for gas decomposition is constructed in this manner, the inner peripheral surface of the heat conducting rod constitutes a total reflection surface of infrared rays, so that irradiation of the substrate with infrared rays is prevented, and heating of the substrate by the gas heater is prevented. Therefore, the substrate temperature can be easily controlled only by the substrate heater. In addition, impurities due to heating and heating of the heating resistance wire are not mixed into the reaction tank, and a thin film having better film quality can be formed on the substrate.

FIG. 4 shows a third embodiment of the present invention. The internal space of the gas heater of the gas decomposition heater unit 73 is maintained at a reduced pressure. Here, an infrared heater 70 is used in which a heating resistance wire 71 wound in a coil shape is sealed in a double cylindrical container 74 made of quartz, and gas introduction pipes 51, 52, and 53 are provided in the center of the infrared heater 70 in the axial direction. Insert. The shielding plate 19 that shields the substrate 3 from heat irradiation from the infrared heater 70 is made of heat-resistant porcelain, and has a concave surface facing the substrate 3. This concave portion is covered with an electrode plate 20 composed of a perforated plate in which many pores are uniformly distributed or a mesh plate in which fine meshes are uniformly formed.
The high frequency power supply 15 is connected via the current introduction terminal 16.

The compound gas fed into the reaction tank 1 through the gas introduction pipes 51, 52, 53 during film formation is supplied to an infrared heater.
Due to 70, they are dissociated and decomposed at their respective optimum temperatures, flow into the recesses of the shielding plate 19, and further pass through the electrode plate 20 and flow out at a uniform gas density. The released dissociated / decomposed gas is
In a high-frequency electric field between the electrode plate 20 and the substrate 3, a plasma state is established, and a thin film is formed on the surface of the substrate 3 heated to a predetermined high temperature by the substrate heater 2.

FIG. 5 shows the optical bandgap value Eg (eV) in the case where the a-Si: H film is formed by converting the previously decomposed compound gas into plasma. Substrate heating temperature T _S
Was maintained at 220 ° C. constant, varying the temperature T _P of the infrared heater 70, the optical band gap value T _P = 300 ° C. or higher is rapidly reduced, the temperature T _P = 500 ° C. Infrared heaters
, A low value of the optical band gap value Eg of 1.68 eV is obtained. In contrast, the conventional high-frequency plasma CV
As and D, without prior thermal decomposition of a compound gas, in the case of direct plasma was formed a-Si: optical band gap values Eg of the H film, as shown in FIG. 6, the substrate temperature T _S
= 220 ° C., infrared heater temperature T _P in FIG.
= 300 ° C. or lower. In order to lower the optical bandgap value Eg below this, the substrate temperature T _S must be set to 220 ° C.
Must be raised above ℃. Conventionally, the substrate temperature T _S has been set high in order to obtain a low optical band gap value Eg. However, in the case of the a-Si: H film, the substrate temperature T _S = 200 ° C. to 25 ° C.
Since a thin film having the best film quality can be obtained at 0 ° C., there is a limit in increasing the substrate temperature T _S , and therefore, there is a limit in decreasing the optical band gap value Eg.

FIG. 7 shows an embodiment of the present invention. The reaction tank 1 is formed of quartz, which is an insulator. In the present embodiment, a coil heater is provided in a double cylindrical container 74 whose internal space is kept in a reduced pressure state in a gas heater for decomposing gas. An infrared heater 70 in which the heating resistance wire 71 is sealed is used. A high frequency electrode 21 having a coil wound spirally for forming a high frequency electric field in the space between the shielding plate 9 and the substrate 3 attached to the substrate side elbow surface of the infrared heater 70 is provided outside the reaction tank 1. Is provided so as to surround the reaction tank 1.
1 is a shield box 2 for preventing radio interference
3 inside. When a high-frequency voltage is applied from the high-frequency power supply 15 to the high-frequency electrode 21, a high-frequency electric field is formed between the high-frequency electrode 21 and the substrate 3. The lines of electric force forming the electric field are perpendicular to the conductor surface on the conductor surface,
By appropriately setting the axial length and the end face position of the high-frequency electrode 21, a high-frequency electric field that effectively gasifies gas between the shielding plate 9 and the substrate 3 is generated between the shielding plate 9 and the substrate 3. In the space. As a result, a large amount of gas molecules dissociated and decomposed by the infrared heater 70 and converted into plasma by the high-frequency electric field are deposited on the substrate 3 and the peripheral wall of the reaction tank 1 far from the substrate 3, and film contamination on the substrate surface from the high-frequency electrode side is reduced. Less.

[0026]

As described above, according to the present invention, the following effects can be obtained. According to the invention of claim 1,
Since the heat from the gas heater to the substrate is shielded and the substrate is not heated by the gas heater,
The temperature of the substrate can be controlled solely by the substrate heater alone, which facilitates temperature control for maintaining the substrate at a predetermined high temperature. At the same time, heat irradiation from the gas heater to the thin film deposited on the substrate is eliminated, so that a change in the thin film composition due to heating is prevented, and a plate-shaped heat shielding means that can reliably obtain a thin film having an intended composition. Can be provided in an arbitrary size in the reaction tank without obstructing the outflow of the compound gas in the direction of the substrate, and has a simpler structure than in the case of using multiple reflectors as heat shielding means, and The heat shielding can be effectively performed even in a state where the decomposition product of the compound gas is attached, the effect can be achieved at a low cost, the reaction tank is formed of quartz, the plate-shaped heat shielding means and the substrate Since the high-frequency electrodes for converting the gas in the space between them into plasma are arranged outside the reaction tank, a large amount of plasma gas molecules are deposited on the substrate surface and the peripheral wall of the reaction tank far from the substrate, and from the high-frequency electrode side. Less membrane contamination Film formation is possible in the state. According to the second aspect of the present invention, since the heat from the gas heater to the substrate is shielded and the substrate is not heated by the gas heater, the temperature of the substrate can be controlled solely by the substrate heater alone. Temperature control for maintaining the substrate at a predetermined high temperature becomes easy. at the same time,
Since the heat irradiation from the gas heater to the thin film deposited on the substrate is eliminated, the change of the thin film composition due to the heating is prevented, and the thin film of the desired composition can be reliably obtained. Since the heating resistance wire is sealed in a depressurized double cylindrical closed container, impurity gas generated from the heating resistance wire is confined in the closed container,
It is possible to reliably prevent the formation of a film in a state in which the impurity gas is mixed without diffusing into the reaction tank, and to form a thin film having good film quality. Further, since the heating resistance wire does not come into contact with the thermally decomposed compound gas, it is possible to reliably prevent the life from being shortened due to the reaction with the compound gas. These effects are
In contrast to the apparatus configuration of claim 1, the high-frequency electrode for converting the gas in the space between the plate-shaped heat shielding means and the substrate into a plasma, which is obtained with only a small increase in cost and is made of quartz, is provided. Since it is arranged outside the reaction tank, a large amount of gas molecules converted into plasma accumulate on the surface of the substrate and on the peripheral wall of the reaction tank far from the substrate, and the film can be formed with less film contamination from the high-frequency electrode side. .

[0027]

[0028]

[0029]

[0030]

[0031]

[Brief description of the drawings]

FIGS. 1A and 1B show a device configuration of a first reference example of the present invention. FIG. 1B is a longitudinal sectional view of a main part of the device, and FIG.
Sectional view along line AA of FIG.

FIG. 2 is a diagram showing a temperature change showing a time change of a substrate heater upper surface temperature in the apparatus having the configuration shown in FIG. 1 after the gas heater is energized;

FIG. 3 is a longitudinal sectional view showing a main part of a device having a device configuration according to a second embodiment of the present invention;

4A and 4B show a device configuration of a third reference example of the present invention, wherein FIG. 4B is a longitudinal sectional view of a main part of the device, and FIG.
Sectional view along line AA of FIG.

FIG. 5 shows a-S formed using the apparatus having the configuration shown in FIG.
i: Diagram showing temperature dependency of optical band gap value of H film on gas heater (infrared heater) while maintaining substrate heating temperature constant at 220 ° C.

FIG. 6 is a diagram showing the substrate temperature dependence of the optical band gap value of an a-Si: H film formed by applying a high-frequency voltage directly to a compound gas that is not thermally decomposed in advance and forming a plasma.

7 shows an embodiment of a vapor phase growth apparatus according to the present invention, wherein FIG. 7 (b) is a longitudinal sectional view of a main part of the apparatus, and FIG. Sectional view along line A

FIG. 8 shows an example of a vapor phase growth apparatus configuration,
FIG. 1B is a longitudinal sectional view of a main part of the apparatus, and FIG. 1A is a sectional view taken along line BB of FIG. 1B.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Substrate heater 3 Substrate 6 Shielding tube 7 Winding heater 8 Temperature sensor 9 Shielding plate (Heat shielding means) 15 High frequency power supply 19 Shielding valve (Heat shielding means) 20 Electrode plate 21 High frequency electrode (Cylindrical electrode) 51 Gas introduction pipe 52 Gas introduction pipe 53 Gas introduction pipe 70 Infrared heater 71 Heating resistance wire 72 Quartz pipe (Infrared transmission pipe) 73 Heater unit for gas decomposition 74 Container

Claims (3)

(57) [Claims] 1. A gas decomposition heater unit having a gas heater for heating and decomposing a compound gas containing a thin film component, which is introduced into the reaction tank when a thin film is formed on the surface of a substrate disposed in the reaction tank. And a substrate heater that keeps the substrate at a predetermined high temperature, and a heat shielding means for shielding the substrate from heat irradiation from the gas heater between the gas heater and the substrate. The introduction of the compound gas into the reaction vessel is performed through a gas introduction pipe penetrating the wall of the reaction vessel and protruding into the reaction vessel, and the gas decomposition heater unit is used as a gas heater as the gas introduction pipe. A winding formed by winding a heating resistance wire in a coil shape around an infrared transmitting pipe through which is inserted, and surrounding the winding heater in a cylindrical shape from the outside to shield radial heat radiation from the winding heater and Winding A heat shielding means comprising a shielding cylinder for preventing diffusion of impurities from the heater into the reaction tank, and a temperature sensor for detecting the temperature of the coil heater, and for shielding the substrate from heat irradiation from the gas heater; Is formed of a plate made of a material having a low thermal conductivity in which a gas inlet through which the gas inlet tube can be inserted is formed, and is attached to a gas inlet tube end face side of a wire-wound heater. In order to form a high-frequency electric field in the space between the substrate and the plate-shaped heat shielding means made of quartz and made of a low thermal conductivity material, it must be surrounded from outside by a cylindrical electrode connected to a high-frequency power supply. Characteristic vapor phase growth equipment. 2. A gas decomposition heater unit having a gas heater for heating and decomposing a compound gas containing a thin film component, which is introduced into the reaction tank when a thin film is formed on the surface of a substrate disposed in the reaction tank. And a substrate heater that keeps the substrate at a predetermined high temperature, and a heat shielding means for shielding the substrate from heat irradiation from the gas heater between the gas heater and the substrate. The introduction of the compound gas into the reaction vessel is performed through a gas introduction pipe penetrating the wall of the reaction vessel and protruding into the reaction vessel, and the gas decomposition heater unit is used as a gas heater as the gas introduction pipe. An infrared heater in which a heating resistance wire wound in a coil shape is sealed in a container in which the internal space is kept in a depressurized state, and the infrared heater is formed into a cylindrical shape from the outside. Surround the infrared A shielding tube to shield the radial thermal radiation from over data, it comprises a temperature sensor for detecting the temperature of the infrared heater, and heat shielding means for shielding the substrate from thermal radiation from the gas heater is,
A gas inlet through which the gas inlet tube can be inserted is formed;
In a vapor phase growth apparatus made of a plate made of a material having a low thermal conductivity and attached to an end face of a gas introduction pipe of an infrared heater, a plate-shaped heat shielding means made of quartz and a substrate made of a material having a low heat conductivity and a substrate are provided. A vapor phase growth apparatus, which is surrounded from outside by a cylindrical electrode connected to a high frequency power supply for forming a high frequency electric field in a space between the apparatus and the device. 3. The vapor phase growth apparatus according to claim 1, wherein the cylindrical electrode surrounding the reaction vessel is formed by spirally winding a coil. .