JP2002008982A - Plasma cvd system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma CVD system which provides a stable plasma for forming a high quality silicon film with few defects and with high productivity. SOLUTION: The body of the plasma CVD apparatus is composed of conductive materials, such as stainless steels. It has a reaction chamber, capable of keeping its interior vacuum, a means for feeding a reactive gas such as silane gas into the reaction chamber, a means for turning the reactive gas fed into the chamber a plasma to generate a reactive gas plasma of a high electron density and means for holding a substrate for forming a thin film on its surface. At least a part of the portions in the chamber which come into contact with the reactive gas plasma is electrically insulated from the chamber body, by means of covering these portions with insulators, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma CVD apparatus and a method for forming a thin film using the apparatus.

[0002]

2. Description of the Related Art Conventionally, thin films such as amorphous silicon, fine grain silicon, silicon oxide and silicon nitride have been widely used for semiconductor devices such as thin film transistors, photoelectric conversion devices and the like. In particular, among these, amorphous silicon has excellent electrical properties such as high photoconductivity and low dark conductivity, and has high durability, and is therefore used for photoelectric conversion elements such as solar cells. .

As a general method for forming such an amorphous silicon thin film, a CVD (chemical vapor deposition) method, for example, a high-frequency plasma CVD method, an optical CVD method, an electron cyclotron resonance (ECR) CVD method And a thermal CVD method.

Among these methods, a high-frequency plasma CVD method, which is a type of capacitively coupled plasma, suppresses the generation of structural defects such as dangling bonds (unbonded hands) and reduces the three-dimensional silicon network structure. It is widely used because it can be formed efficiently.

According to this method, a raw material gas such as monosilane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is introduced into a vacuum reaction chamber while being accompanied by a hydrogen gas for dilution.
A high-frequency electric power is applied between two electrodes arranged opposite to each other in a vacuum reaction chamber to generate a high-frequency electric field. In this electric field, electrons collide with neutral molecules of a raw material gas, and a high-frequency plasma is generated. Is formed to decompose the raw material gas and form a silicon thin film on the surface of the base material provided on one of the electrodes.

In this high frequency plasma CVD method, a relatively high quality film is easily obtained because the plasma density is low, for example, 10 ⁹ cm ⁻³ or less, and the silicon thin film formation speed is low. However, since a high gas pressure is required, a decomposition reaction in the form of a polymer is generated by a secondary reaction in the gas phase, contamination by substances adhering to the chamber wall due to discharge in the reaction chamber, or contamination of the electrode. There is a possibility that the quality of the thin film may be deteriorated due to contamination by the adhered substance.

For this reason, recently, instead of capacitively coupled plasma, an inductively coupled plasma CVD method using inductively coupled plasma has been used. In the inductively coupled plasma method, high-frequency power is applied to a high-frequency coil (RF antenna) to generate inductively-coupled plasma, and a silicon thin film is formed on a base material arranged opposite to the high-frequency coil. Is the way. In this inductively coupled plasma method, for example, ¹⁰ 10 ~10 ¹² cm ^{- 3} about a high plasma density can be obtained, are also possible to generate more effective radical species (SiH ₃ radicals) by adjusting the plasma generating conditions . In addition, the generation of ions which are considered to have a bad influence on the growth surface of the thin film or the interface at the time of lamination is small, and the reaction can be performed at a low pressure of, for example, 0.1 to 50 mTorr.

In addition, unlike the conventional capacitively coupled plasma CVD apparatus, this inductively coupled plasma CVD apparatus does not require the use of a counter electrode, and thus has a high degree of freedom in the space inside the apparatus. For this reason, for example, it is possible to increase the effective utilization rate of the reaction gas by installing a reaction gas supply nozzle facing the substrate stage.

As a method using such an inductively coupled plasma method, Japanese Patent Application Laid-Open No. Hei 10-27762 discloses a method in which a spiral high-frequency coil is arranged on the upper part of the outside of a reaction chamber and the surface thereof does not contain oxygen. A dielectric window of quartz material with the film deposited is formed at the top of the reaction chamber,
An inductively coupled plasma CVD apparatus having a gas supply nozzle formed in a ring shape between the dielectric window and the substrate is disclosed.

However, in such an inductively coupled plasma CVD apparatus, a high-frequency coil is provided outside the reaction chamber to induce a high frequency through a dielectric window. 10 ^{- 2} for Torr not able to induce a high frequency to be relatively high, the gas mist (powder) tends to occur in the plasma, as a result,
Impurities were mixed into the silicon thin film on the surface of the base material, and it was still insufficient to form a uniform, high-quality silicon thin film with few defects.

In this case, since a high-frequency coil is provided outside the reaction chamber to induce high-frequency waves through the dielectric window, the transmission of high-frequency waves is not good, and the speed of deposition on the surface of the base material is low. But the production efficiency was not good.

On the other hand, "Low Temperature Growth of Amor
phous and Polycrystalline Silicon Films from a Mod
ified Inductively Coupled Plasma '', M. Goto et al., Jpn.
J. Appl. Phys. Vol. 36 (1997), pp. 3714-3720,
In the inductively coupled plasma CVD method, a high frequency coil (RF antenna) is disposed inside a reaction chamber, and an internally excited inductively coupled plasma capable of generating a stable plasma at a low reaction pressure at a low voltage. A CVD apparatus is disclosed.

[0013]

However, according to studies by the present inventors, in the above-described inductively coupled plasma CVD apparatus having an RF antenna disposed therein, the reactive gas plasma flashes and becomes unstable depending on manufacturing conditions. It has been clarified that there is a problem that the reaction gas becomes difficult to form, or a reactive gas plasma is hardly formed, and it is difficult to stably obtain a high-quality thin film. When a film is formed using this apparatus, it is common practice to temporarily shut off the contact between the reaction gas plasma and the base material using a shutter in order to accurately control the film thickness. However, when the shutter is opened and closed between the base material and the plasma, the problem that plasma instability is particularly likely to occur, and furthermore,
Changing the distance between the base material and the high-frequency coil or the distance between the chamber wall and the high-frequency coil to change the film production conditions,
It became clear that there was a problem that the emission intensity of the reactive gas plasma changed.

Therefore, the present invention provides a plasma CVD apparatus capable of efficiently producing a high-quality thin film, and more specifically, a plasma CVD apparatus capable of generating a stable high-density reactive gas plasma. The purpose is to provide.

[0015]

In view of such circumstances, the present inventors have attempted to obtain stable plasma easily when using inductively coupled plasma for producing a thin film.
We worked diligently. As a result, when a treatment for electrically insulating the part in contact with the reaction gas plasma from the reaction chamber by, for example, coating the part in contact with the reaction gas plasma in the reaction chamber with an insulator such as ceramics, a stable operation is achieved. It has been found that inductively coupled plasma can be generated. Further investigations have shown that when a silicon film is deposited using a CVD apparatus which has undergone such treatment, a silicon film can be obtained at a high speed of about 10 nm / sec. I came to.

That is, according to a first aspect of the present invention, there is provided a reaction chamber having a main body made of a conductive material and capable of maintaining the inside thereof in a vacuum state, and a reaction gas supply for supplying a reaction gas into the reaction chamber. Means, a reaction gas plasma generating means for generating a reaction gas plasma having a high electron density by converting the reaction gas supplied into the reaction chamber into plasma, and for holding a substrate on which a thin film is formed on the surface thereof A plasma CVD apparatus having a base material holding means, wherein at least a part of a portion of the reaction chamber in contact with the reaction gas plasma is electrically insulated from the reaction chamber body. .

Although the present invention is not limited by theory, in a conventional plasma CVD apparatus, the ionized electrons in the plasma have a reaction chamber body (usually grounded) made of a conductive material such as metal. ), The plasma potential drops, and it is difficult to generate stable plasma. On the other hand, in the plasma CVD apparatus of the present invention, the electrons in the reaction gas plasma It is considered that the reaction gas plasma was stabilized because the quenching became difficult to occur. In addition, in the plasma CVD apparatus of the present invention, even when plasma comes into contact with the reaction chamber, the ionized electrons are hard to disappear, so that the volume of the reaction chamber can be reduced. Furthermore, in the aspect of the plasma CVD apparatus of the present invention, which has a shutter for controlling contact and non-contact between the reaction gas plasma and the substrate by moving the same, the shutter is activated at the start of forming the reaction gas plasma. Even in the closed state, the plasma can be formed stably, and the state of the plasma does not change when the shutter is opened and closed. There is also an advantage that there is no need to adjust.

Among the plasma CVD apparatuses of the present invention, an inductively coupled plasma CVD apparatus in which a high-frequency applying coil is installed in a reaction chamber is used to supply a high-frequency power to the coil to supply the reaction to the reaction chamber. The generation efficiency of the inductively coupled plasma generated with the gas is improved, and the reaction pressure of the reaction gas can be reduced.
This is characterized in that a high-quality thin film having a uniform quality and few defects can be formed at a high speed because the generation of a thin film is difficult.

A second invention is a method for producing a thin film, comprising forming a thin film on a substrate using the plasma CVD apparatus of the present invention.

According to the production method of the present invention, a reactive gas plasma having a high electron density can be stably obtained.
The decomposition efficiency of the source gas is improved, and a high-quality thin film can be manufactured at a high film-forming speed.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A plasma CVD apparatus according to the present invention
A reaction chamber whose main body is formed of a conductive material, the inside of which can be maintained in a vacuum state; a reaction gas supply means for supplying a reaction gas into the reaction chamber; and a reaction gas supplied into the reaction chamber. It has a reaction gas plasma generating means for generating a reaction gas plasma having a high electron density by converting a gas into plasma, and a base material holding means for holding a base material on which a thin film is formed on its surface.

The plasma CVD apparatus of the present invention uses a conventional high electron density plasma, except that at least a part of the portion of the reaction chamber where the reaction gas plasma comes into contact is electrically insulated from the reaction chamber body. Inductively coupled plasma CVD equipment, electron cycloton resonance (EC
R) There is no particular difference from the CVD apparatus and the like.

For example, the main body of the reaction chamber is S
The container is not particularly limited as long as the container is made of a conductive material such as stainless steel such as US304 and the inside thereof can be maintained in a vacuum state by an exhaust means such as a vacuum pump. A well-known reaction chamber used in a conventional plasma CVD apparatus such as a (spherical) container having a spherical shape can be used. The reaction chamber may have a chamber opened in the reaction chamber, such as a reaction gas plasma generation chamber, depending on the structure of the reaction gas plasma generation means.

The reaction gas supply means is not particularly limited as long as it is a means for supplying a reaction gas, which is converted into plasma and reacts as a raw material of a thin film, into the reaction chamber, but is usually a gas such as a gas cylinder (cylinder). This is a pipe for introducing a reaction gas from the storage container into the reaction chamber via a pressure regulating valve or a flow controller and, if necessary, a gas mixer or a temperature controller. Here, the reaction gas means a gas (raw material gas) which is a direct raw material of the thin film or a gas obtained by diluting the gas. The gas (raw material gas) directly serving as a raw material for the thin film is appropriately determined depending on the type of the thin film to be produced.
For example, a silane-based gas is used for forming a silicon film, and a hydrocarbon-based gas is used for forming a diamond film. In addition, hydrogen, helium, argon, or the like is used as the diluent gas.

Further, the reaction gas plasma generating means includes:
There is no particular limitation as long as it is a means for generating a reaction gas plasma having a high electron density by converting the reaction gas supplied into the reaction chamber into plasma. Here, the high-electron-density reactive gas plasma is a reactive gas plasma having an electron density of about 10 ¹⁰ to 10 ¹² cm ⁻³ , and is an inductively coupled plasma capable of generating such an electron-density plasma. A mechanism, an ECR plasma generation mechanism, and the like correspond to the reaction gas plasma generation means. The electron density of the plasma can be measured by performing a plasma diagnosis using the Langmuir probe method.

The above-mentioned inductively-coupled plasma generation mechanism is as follows.
A high-frequency power is applied to a high-frequency application coil disposed inside or outside the reaction chamber so as to face the base material, and the reaction gas existing in the vicinity of the high-frequency application coil is turned into plasma to reduce a pressure difference or a diffusion phenomenon. The reaction gas plasma is guided to the base material by utilizing. Also, ECR
The plasma generating mechanism is classified into a permanent magnet type and a divergent magnetic field type (generating a magnetic field by an electromagnet) according to the means for generating a magnetic field. The reaction gas is turned into plasma by the emitted microwave. In the case of a divergent magnetic field type, a reactive gas existing in a divergent magnetic field formed by an electromagnet is irradiated with microwaves to convert the reactive gas into a plasma, and the generated reactive gas plasma is guided to the base material by the magnetic field. Things. In the divergent magnetic field type, it is usually called a plasma chamber (or a plasma generation chamber), and a gas for generating plasma in a chamber provided with an opening portion facing the base material (hereinafter, also referred to as a plasma generation gas). Usually, hydrogen, helium, or argon is used.) Or, when the reaction gas is converted into plasma and converted into plasma using a plasma generating gas, the reaction gas is introduced into the plasma, which is further converted into plasma to form a reaction gas plasma. I have.

The substrate holding means included in the plasma CVD apparatus of the present invention is not particularly limited as long as it can hold a substrate on which a thin film is formed. A base material setting section (stage) for setting is supported in the reaction chamber by a support member fixed to the reaction chamber main body, or slidable up and down or the like (vacuum in the reaction chamber). For example, one having a structure supported by a support member penetrating the reaction chamber main body (so that it can be moved while maintaining the degree) can be exemplified. In a conventional plasma CVD apparatus,
The support member and the base member installation part are usually made of a conductive material such as a metal for the reason of easiness of processing at the time of manufacturing.

Further, the plasma CVD apparatus of the present invention may further have a shutter for controlling contact and non-contact between the reaction gas plasma and the substrate by moving the apparatus. By having such a shutter, the deposition time can be controlled without being affected by instability at the start of plasma formation. The structure of the shutter is not particularly limited as long as it functions as described above. A typical shutter, for example, is slidable on the reaction chamber body (the degree of vacuum in the reaction chamber). The shutter may be a plate-shaped body supported by a support member provided so as to be able to move back and forth or rotate while maintaining the state. In the shutter, the plate-like body has an area larger than the base material, and the plate-like body exists between the reaction gas plasma generating means and the base material such that the projection completely covers the base material. In this case, the contact between the reactive gas plasma and the substrate is physically blocked, and the support member is moved back and forth or rotated so that the projection of the plate-like body does not cover the substrate. Thereby, the contact between the reaction gas plasma and the substrate can be restored. In addition, the conventional plasma CVD
In the device, these support members and shutters are
Usually, it is made of a conductive material such as metal for reasons such as ease of processing at the time of fabrication.

In the plasma CVD apparatus of the present invention, in addition to the shutter, a substrate temperature adjusting means for controlling the temperature of the substrate (for example, by using a sheathed heater or passing a cooling medium, A mechanism for heating or cooling the substrate, or a mechanism for heating the substrate with an infrared heater), a load lock chamber for taking in and out the substrate to be treated into this equipment, and a base with a vacuum maintained. Substrate transfer equipment for setting and removing materials into and from the reaction chamber (a remotely operable rod for moving the substrate through this, a gate valve installed between the load lock chamber, etc.) Etc. may be provided.

In the plasma CVD apparatus of the present invention,
It is essential that at least a part of the reaction gas plasma contact portion in the reaction chamber is electrically insulated from the reaction chamber body. If all parts of the reaction chamber that come into contact with the reaction gas plasma are electrically connected to the reaction chamber body, stable reaction gas plasma cannot be obtained, and the intended purpose may be achieved. Can not. From the viewpoint of the effect, it is most preferable that all of the portions of the reaction chamber that come into contact with the reaction gas plasma are electrically insulated from the reaction chamber main body. It is preferable that the part and the reaction chamber main body are electrically insulated, and when a shutter is further provided, it is particularly preferable that the shutter is also electrically insulated from the reaction chamber main body. Further, with respect to the inner wall surface of the reaction chamber, 70% or more, particularly 9%, of the total area of the portion where the reaction gas plasma comes into contact (including the inner surface of the plasma generation chamber when the plasma CVD apparatus has the chamber).
Preferably, 0% or more is electrically insulated from the reaction chamber body.

The method of electrically insulating at least a part of the reaction gas plasma in the reaction chamber from the reaction chamber body is not particularly limited, and at least a part of the reaction gas plasma contacting part is an insulator. Or a method in which an insulator is interposed between at least a part of the contact portion of the reaction gas plasma and the reaction chamber body. When at least a part of the contact portion of the reactant gas plasma is made of an insulator, the entire member of the portion to be insulated may be made of an insulator, or may be coated by a method such as coating with an insulator. Only the surface layer may be made of an insulator. The insulator used at this time is not particularly limited, and ceramics such as alumina, silica, and aluminum nitride; glass and the like can be used.

In the plasma CVD apparatus of the present invention, a reactive gas plasma having a stable and high electron density can be obtained. Therefore, when a thin film of silicon, diamond or the like is formed by the plasma CVD method using the apparatus, a high plasma is obtained. A high-quality thin film can be obtained stably with good reproducibility and at high speed.
Except for using the plasma CVD apparatus of the present invention, the film forming method at this time is not particularly different from the case of using the conventional plasma CVD apparatus.

Hereinafter, a plasma CVD apparatus of the present invention employing an inductively coupled plasma generating mechanism in which a high frequency application coil is installed in a reaction chamber as a reaction gas generating means (hereinafter, also referred to as an inductively coupled plasma CVD apparatus of the present invention). The plasma CVD apparatus of the present invention and the method of manufacturing a thin film of the present invention will be described in further detail by taking, as an example, the case of manufacturing a silicon thin film using FIG.

The inductively coupled plasma CVD apparatus 10 of the present invention shown in FIG. 1 is made of a conductive material such as stainless steel such as SUS304 and has a cylindrical reaction chamber 12 maintained in a vacuum state. By connecting to a vacuum source such as a vacuum pump through an exhaust port 13 formed in the bottom wall 16 of the reaction chamber 12, a constant vacuum state is maintained. The portion of the inner wall of the reaction chamber 12 that comes into contact with the reaction gas plasma is coated with an insulator made of ceramics such as alumina or aluminum nitride.

In the inside of the reaction chamber 12, a substrate setting section (stage 14) for setting a substrate A on which a thin film such as a silicon thin film is deposited on the surface is disposed. The position of the stage 14 can be adjusted by penetrating the bottom wall 16 of the reaction chamber 12 and supported by a support member 15 that can slide up and down by a drive mechanism (not shown). For example, the base material A can be heated by a heating mechanism such as a sheath heater. Although not shown, the support member 1
The sliding part between the bottom 5 and the bottom wall 16 includes the reaction chamber 1
A seal member such as a seal ring is provided in order to secure a degree of vacuum in 2. And the stage 14
Is that its surface is covered with an insulator such as ceramics (as another mode not shown, the support member 15 and the bottom wall 1
6 Insulation such as ceramic should be interposed between
This provides electrical insulation from the chamber body.

On the other hand, a ring-shaped high frequency application coil 18 is provided above the reaction chamber 12, and its base end portions 20 and 22 pass through the top wall 17 of the reaction chamber 12, and It is connected to a high-frequency power supply 24 provided outside. A matching circuit (not shown) is provided between the high-frequency application coil 18 and the high-frequency power supply 24 so that the high frequency generated by the high-frequency power supply 24 can be transmitted to the high-frequency application coil 18 without loss.

The diameter of the high frequency application coil 18 is usually 3 to
It is 30 cm, preferably 5 to 20 cm. With such a coil diameter, it is possible to avoid that the thickness of the thin film is not thin near the center of each coil, and it is possible to increase the film forming speed. FIG. 1 shows an embodiment in which one ring-shaped coil is installed as a high-frequency application coil. However, the coil may have another shape such as a spiral shape, and the number of installed coils may be two or more.

The material of the high-frequency coil 18 may be selected from metals, for example, stainless steel such as SUS304, copper, aluminum and the like, which can be easily processed, and is not particularly limited. The surface of the high-frequency coil 18 may be covered with an insulator such as alumina or aluminum nitride.

When the coil is heated, for example, in order to make the adhered silicon film difficult to peel off, for example, a heating means for embedding a sheathed heater inside the high-frequency coil 18 or silicone oil as a heat medium is circulated through the coil. It is, of course, possible to heat the high-frequency coil by such a method.

The reaction chamber 12 has a shower nozzle shape having a plurality of gas blowing holes so as to pass through the top wall 17 of the reaction chamber 12 and pass through the center of the ring-shaped high-frequency applying coil 18. Or ring)
The reaction gas introduction nozzle 25 is provided, and a reaction gas is introduced from the reaction gas introduction nozzle 25 from a reaction gas supply source (not shown) through a flow meter (not shown).

As a reaction gas supply source, for example, a raw material gas such as monosilane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is supplied as it is, or mixed with a diluting gas such as hydrogen, helium, argon, xenon, or the like. It is equipped with various gas cylinders, pressure regulators and, if necessary, gas mixers.

A shutter 19 is provided between the high-frequency coil 18 and the stage 14, and the opening and closing of the shutter 19 controls the deposition time. The surface of the shutter 19 is coated with a ceramic such as alumina or aluminum nitride. In another mode (not shown), or by sandwiching an insulator (such as a insulator) such as a ceramic on a support member of the shutter. Good｝ Electrical insulation can be obtained from the reaction chamber body.

Further, on the side of the reaction chamber 12,
There is a gate valve (not shown) through which a gate valve (not shown) for loading and unloading the substrate A to be processed is connected.

Inductively coupled plasma CVD using the inductively coupled plasma CVD apparatus of the present invention configured as described above.
Hereinafter, a method for producing a thin film by the method will be described.

First, the inside of the reaction chamber 12 is maintained in a vacuum state by operating a vacuum source such as a vacuum pump to exhaust air through the exhaust port 13. By setting the inside of the reaction chamber 12 to a high vacuum, oxygen, carbon, nitrogen, and the like serving as an impurity source of the silicon film can be removed. The pressure at this time is preferably set to 1 × 10 ⁻⁶ Torr or less.

Next, in a pressure adjustment chamber connected to the side of the reaction chamber 12, for example, a glass substrate
After the base material A made of a metal substrate or the like is carried in, the pressure in the pressure adjustment chamber is adjusted to the same degree of vacuum as the pressure in the reaction chamber 12. Then, the gate valve is opened, and the substrate A is placed on the stage 14 in the reaction chamber 12.

The high frequency power supply 24 provided outside the reaction chamber 12 applies a high frequency to the high frequency application coil 18, and a reaction gas supply path (not shown) formed in the high frequency application coil 18 from the reaction gas supply source. The reaction gas is supplied into the reaction chamber 12 through the reaction chamber. Thus, an inductively coupled plasma is generated by the high frequency applied to the high frequency application coil 18, and a silicon thin film is deposited and formed on the surface of the substrate A mounted on the stage 14.

The pressure (reaction pressure) in the reaction chamber 12 at this time is preferably 0.3 to 100 mTorr.
r, more preferably 5 to 30 mTorr. By controlling to such a pressure, generation of gas mist (powder) in plasma can be prevented, and a uniform, high-quality silicon thin film with few defects can be formed. However, the reaction chamber configuration and gas introduction /
Since the generation of gas mist (powder) in the plasma slightly changes depending on the method of exhaustion, the reaction pressure cannot be uniquely determined.

In this case, the high frequency power is 10 W to
It is 3 KW, and the frequency of the high frequency is preferably 5 MHz to 200 MHz, more preferably 10 MHz, in consideration of adjustment by a matching circuit.
It is desirable to set it to １００100 MHz.

As a reaction gas introduced into the reaction chamber 12, for example, when a silicon thin film is formed,
Monosilane (SiH ₄ ), disilane (Si ₂ H ₆ ) or the like, or hydrogen, argon, helium,
A reaction gas accompanied by a diluting gas such as neon or xenon can be used. Further, chloro-containing silane gas represented by SiH _X Cl _4-X (where X is an integer of 0 to 3) is used as a reaction gas by accompanying with a hydrogen gas for dilution. It is desirable because it is possible to form a silicon thin film having high light stability such that the deposited silicon film can maintain the light degradation resistance and the photoelectric characteristics for a long time. In particular, dichlorosilane (SiH ₂ C
l ₂ ) is easy to handle because its boiling point is about 10 ° C.
It is preferable to use this.

As the introduction amounts of the raw material gas and the dilution gas,
Although the case where the source gas is introduced into the reaction chamber alone and the case where the source gas is introduced together with the diluent gas into the reaction chamber are different, the total amount is considered in consideration of the introduction amount at which a deposition rate of 20 Å / sec or more is obtained. It is preferable that the introduction amount is 30 cc / min to 3000 cc / min. The mixing ratio between the source gas and the diluent gas is not particularly limited. However, when the flow ratio of the diluent gas to the reaction gas (diluent gas / source gas) exceeds 10, the structure of the silicon film changes. . When the flow ratio of the dilution gas is smaller than 10, the deposition of amorphous silicon is dominant, and when it is 10 or more, the deposition of a crystalline silicon film is dominant. However, since the structural change of the silicon film is greatly related to other deposition conditions, that is, high-frequency power, substrate temperature, and the like, it is difficult to uniquely define only the flow rate ratio. In general,
The higher the high-frequency power, the higher the dilution ratio, and the higher the substrate temperature, the more the deposition of the crystalline silicon thin film becomes dominant.

The distance L between the base material A and the high-frequency coil 18 is set to SiH which is considered to be a main deposition precursor.
₃ Considering the lifetime of neutral radicals, ₃ cm to 30 cm
It is desirable to be within the range.

Further, the substrate A is heated to about 150 to about 300 ° C. by a heating device provided on the stage 14 so that a high-quality silicon thin film is easily deposited.

In this way, a silicon thin film is deposited and formed on the surface of the substrate A mounted on the stage 14 by the inductively coupled plasma generated by the high frequency applied to the high frequency application coil 18.

The time for forming the thin film depends on the use of the substrate and the form of the apparatus.
The reaction may be performed for about 00 seconds.

As described above, the inductively coupled plasma CVD of the present invention
The method and the embodiment of the inductively coupled plasma CVD apparatus have been described mainly with respect to an example of forming a silicon thin film.
It can be applied to other thin films such as a silicon germanium film (SiGe), a silicon carbide film (SiC), a silicon nitride film (SiN), a silicon oxide film (SiO ₂ ), and a diamond-like carbon film (DLC). is there. In addition, although the vertical type device has been described, it is a matter of course that various changes can be made such as changing to a horizontal type device.

[0057]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 Using the CVD apparatus of the present invention shown in FIG. 1 in which the inner wall surface, the substrate installation portion, and the surface of the shutter that come into contact with the reaction plasma in the reaction chamber are covered with an insulator, (Quartz glass substrate, thickness: 0.5 mm, dimensions: 10 cm
(× 10 cm) The substrate was set on the stage. The coil diameter of the high-frequency application coil is 10 cm.

As a reaction gas, a pure gas of 100% monosilane gas was supplied into the reaction chamber without dilution.
The flow rate of the monosilane gas was 100 cc / min, and the pressure in the reaction chamber was maintained at 20 mTorr.
A high frequency was supplied from a high frequency power supply of 600 Hz with an output of 600 W. The substrate was heated to 200 ° C. The reaction gas plasma was generated by closing a shutter provided with an insulating treatment above the substrate stage, and then opening the shutter to form a film. An extremely stable plasma was obtained, and the stability of the plasma was maintained even after the shutter was opened. 2
1.19 μm (film formation speed: 9.
(9 nm / sec) amorphous silicon thin film was obtained on the substrate.

The thickness distribution of the obtained silicon film was measured. The results are shown in Table 1. The measurement of the film thickness distribution was performed by using a spectroscopic ellipsometer “DVA-36VM”.
(Manufactured by Mizojiri Optical Co., Ltd.). The thickness unevenness ratio was determined by expressing the value obtained by dividing the difference between the center thickness and the end thickness by the end thickness in%. Generally, when the reactive gas plasma flickers or becomes unstable, the thickness unevenness ratio increases. Further, when the plasma becomes unstable, the film forming speed decreases.

[0061]

[Table 1]

Example 2 A thickness of 1.07 μm (film formation speed: 8.9 nm) was carried out in the same manner as in Example 1 except that the inner wall surface of the reaction chamber 12 was not coated with an insulator. /
Second), and the thickness distribution of the obtained silicon film was measured. Table 1 shows the results.

Example 3 The procedure of Example 1 was repeated, except that a stage without insulation treatment was used.
m (film formation rate: 3.7 nm / sec), an amorphous silicon thin film was formed, and the thickness distribution of the obtained silicon film was measured. Table 1 shows the results. In addition, the flickering of the plasma was not observed so as to be visually confirmed from the insulating window provided in the reaction chamber during the film formation. Compared with Examples 1 and 2, the film forming speed is slightly slower, and the thickness unevenness ratio is a slightly larger value. However, it can be seen that both values are better values as compared with the values of Comparative Examples shown below.

COMPARATIVE EXAMPLE 1 Plasma C in which none of the inner wall surface of the reaction chamber, the base member installation portion, and the surface of the shutter were coated with an insulator.
Using a VD apparatus, a thickness of 0.13 μm was obtained in the same manner as in Example 1.
An amorphous silicon thin film having a thickness of m (film formation speed: 1.1 nm / sec) was formed, and the thickness distribution of the obtained silicon film was measured. Table 1 shows the results.

In this comparative example, it is difficult to generate plasma when the shutter is closed, and when the shutter is opened even after the shutter is generated, the output of the reflected wave greatly increases and the blinking of the plasma is visually observed. Was done.

[0066]

According to the plasma CVD apparatus of the present invention,
It is possible to generate a stable reaction gas plasma having a high electron density, and by using this apparatus, it is possible to form a thin film such as a silicon film with little reproducibility and few defects at high speed.

[Brief description of the drawings]

FIG. 1 is an inductively coupled plasma CVD of the present invention.
It is the schematic of an apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Inductively-coupled plasma CVD apparatus 12 Reaction chamber 13 Exhaust port 14 Stage A base material 15 Support member 16 Bottom wall 17 Top wall 18 High frequency application coil 19 Shutter 20, 22 Base end part 24 High frequency power supply 25 Reaction gas introduction nozzle

Claims (3)

[Claims] A reaction chamber having a main body made of a conductive material and capable of maintaining the inside thereof in a vacuum state; a reaction gas supply means for supplying a reaction gas into the reaction chamber; A reaction gas plasma generating means for generating a reaction gas plasma having a high electron density by turning the reaction gas supplied to the plasma into a plasma, and a substrate holding means for holding a substrate on which a thin film is formed on its surface A plasma CVD apparatus having a plasma CVD apparatus, wherein at least a part of a portion of the reaction chamber in contact with the reaction gas plasma is electrically insulated from the reaction chamber body. 2. The plasma CVD apparatus according to claim 1, further comprising a shutter for controlling contact and non-contact between the reactant gas plasma and the substrate by moving. 3. A method for producing a thin film, comprising forming a thin film on a substrate using the plasma CVD apparatus according to claim 1.