JPS6230880A - Deposited film forming device by plasma cvd method - Google Patents

Abstract

PURPOSE:To form a deposited film which is stable in electrical, optical and photoconductive characteristics and has uniform quality by providing a means for generating a magnetic field to the outside circumference of a reaction vessel and acting the magnetic field generated by the same to the excitation plasma in the vessel. CONSTITUTION:A gaseous raw material is introduced via a supply pipe 8 into a reaction chamber A. A microwave power source 6 is enegized to radiate microwaves via a dielectric window 4 and to excite the gaseous raw materials so that active species are formed. A coaxial magnetic field generating coil 13 provided to the outside circumference of the vessel is energized to act the force of the magnetic field by the magnetic lines D of force to the electric charge particles moving toward a perforated inside wall 3. The magnetic lines D of force are confined around a substrate 10 under rotation in the state shown by (c). More specifically, the microwave-excited plasma is generated in the atmosphere around the base body 10 shown by (c). Accordingly, the gaseous raw materials are formed as the stable particles, by which the utilizing efficiency thereof is improved and the deposited film having a uniform film thickness and uniform quality is formed.

Description

Detailed Description of the Invention [Technical Field to which the Invention Pertains] The present invention relates to a film deposited on a substrate, particularly a functional film, particularly a semiconductor device, a photosensitive device for electrophotography, a line sensor for image input, an imaging device, a photovoltaic device, etc. The present invention relates to an apparatus for forming an amorphous semiconductor film used in power devices and the like.

[Description of prior art]

Conventionally, amorphous silicon, such as hydrogen and/or halogen, has been used as an element member for semiconductor devices, photoreceptor devices for electrophotography, line sensors for image input, imaging devices, photovoltaic elements, and various other electronic devices and optical devices. (e.g. fluorine, chlorine, etc.) compensated amorphous silicon (hereinafter RA-31 (H,
X) Written as J. ) have been proposed, and some of them have been put into practical use.

These deposited films are formed by the plasma C77D method, which is a method in which raw material gas is decomposed by direct current, high frequency, or microwave glow discharge to form a thin deposited film on a substrate such as glass, quartz, stainless steel, or aluminum. It is known that this can occur, and various devices have been proposed to prevent this.

Such a conventional apparatus for forming a deposited film using the plasma CVD method typically has an apparatus configuration shown in the schematic cross-sectional view of FIG. In FIG. 2, 1 indicates the entire reaction vessel, 2 indicates the side wall, and 21 indicates the bottom wall. 3 is a multi-perforated inner wall,
4 is a dielectric window, 5 is a waveguide, 6 is a microwave power source, 61
7 is a microwave, 7 is an exhaust pipe, 71 is a valve, 8 is a source gas supply pipe, 81 is a valve, 9 is a substrate holding cylinder, 10 is a cylindrical substrate, 11 is a heater, and 12 is a support leg. Further, A indicates a reaction chamber, and B indicates a gas chamber.

Deposited film formation using such conventional deposited film forming equipment is
This is done as follows.

That is, the gas in the reaction chamber A of the reaction container 1 is evacuated through the exhaust pipe 7, and the cylindrical substrate 10 is
1 to heat and maintain the temperature at a predetermined temperature. Next, in the case of forming, for example, an a, -Si deposited film, a raw material gas such as silane is introduced into the gas chamber B via the raw material gas supply pipe 8; It is discharged into the reaction chamber A from a large number of holes in the multi-perforated inner wall filter. At the same time, microwaves are generated from the microwave power source 6, and the microwaves are introduced into the reaction chamber A through the waveguide section 5 and the dielectric window 4. In this way, the raw material gas introduced into the reaction chamber A is excited by the microwave energy and dissociated (excited speciation) to form radical particles, electrons, and ionic particles such as S Bi, SiH'' (representing an umbrella excited state), etc. are generated and react with each other to form a deposited film on the surface of the substrate 10.

The above-mentioned deposition film apparatus using the conventional plasma CVD method is
Although it is generally widely adopted as the optimal one, there are some operational problems.

That is, during the film deposition operation, the aforementioned radical particles, electrons, ion particles, etc. generated in the reaction chamber A diffuse into the space of the reaction chamber A, and are distributed not only to the multi-perforated inner wall 6 but also sometimes to the side wall 2, and even to the dielectric window. 4, and a deposited film is formed on the walls of those walls.

Neutral radical particles mainly contribute to the formation of the deposited film formed on the surface of the substrate 1o, and these neutral radical particles are sometimes present in large quantities on the above-mentioned wall surface. It is consumed in forming a deposited film, and as a result, the amount that flies to the surface of the substrate 10, which is important, is reduced by that amount, and at the same time, the utilization efficiency of the raw material gas and the radiation efficiency of microwaves are reduced. , and the substrate 1
This not only reduces the rate of film deposition on the zero surface, but also causes a deterioration in the quality of the formed film.

Furthermore, when the film deposited on the wall described above reaches a certain thickness, it may peel off in the form of flakes, scatter into the reaction chamber A, and adhere to the surface of the substrate 1o. In this case, the deposited film formed on the surface of the substrate 10 cannot be used as a product. As a means to solve these problems, in addition to regularly inspecting and replacing the multi-perforated inner wall 3 and the dielectric window 4, it is also possible to install a means to select specific parameters and operate the process in the equipment. However, none of these methods meet the requirements of regularly and efficiently producing deposited film products of stable quality and stably supplying them at a low cost.

On the other hand, various devices are becoming more diverse, and in other words, element materials that satisfy all the requirements such as various characteristics, are suitable for the target object and use, and in some cases have a large area. There is a social demand for a constant supply of stable deposited film products at low cost, and there is a situation in which there is a strong need for the development of methods and devices that meet this demand.

[Purpose of the invention]

The present invention solves the above-mentioned problems and meets the above-mentioned requirements regarding conventional apparatuses for forming deposited films used in photovoltaic elements, semiconductor devices, image input line sensors, imaging devices, electrophotographic photosensitive devices, etc. The purpose is to satisfy the following.

In other words, the main object of the present invention is to have electrical, optical, and photoconductive properties that are virtually always stable regardless of the usage environment, to have excellent light fatigue resistance, and to be durable even after repeated use. Excellent durability without causing deterioration even if
It is an object of the present invention to provide a deposited film forming apparatus for forming an improved deposited film that has moisture resistance and is uniform and homogeneous without causing the problem of residual potential.

Another object of the present invention is to improve the properties of the film formed.

We have developed a deposited film forming device that is suitable for large-area films, and can easily achieve improved film productivity and mass production, while improving film forming speed and reproducibility, and making the film quality uniform and homogeneous. It is about providing.

[Structure and effect of the invention]

The present inventor continued intensive research to overcome the above-mentioned problems in conventional apparatuses and achieve the above-mentioned objective, and found that the distance between the plasma interface and the surrounding wall of the reaction chamber primarily contributes to film formation. When the mean free path of the neutral radical particles is larger than the mean free path of the neutral radical particles, that is, when a dead ring for the neutral radical particles is formed near the surface of the inner wall,
It was found that the formation of a deposited film was observed only on the surface of the substrate without forming a deposited film on the surface. Still at that time, regarding forming the plasma interface and adjusting its position,
We also found that it is effective to use the power of a magnetic field. From these findings, we confirmed the following.

In other words, when charged particles such as electrons and ion species generated in the plasma are incident perpendicularly to the magnetic field lines formed parallel to the surrounding wall of the reaction chamber, they are directed from the substrate toward the surrounding wall of the reaction chamber. When they proceed, their orbits are forcibly bent by the force of the magnetic field, preventing them from approaching the surrounding wall of the reaction chamber. Therefore, if a magnetic field is created along the walls around the reaction chamber so that the magnetic lines of force form a barrier against the charged particles, the charged particles will move only in the space surrounded by the lines of magnetic force and will not fly out outside the lines of magnetic force. That is, it becomes possible to confine plasma in the space near the central axis by the magnetic field.

However, on the other hand, there is a problem in that only charged particles can be confined by the magnetic field, and the force of the magnetic field does not affect the movement of the neutral radical particles that contribute to the deposition of the a-3i (H,X) film. The present inventor discovered.

In order to solve this problem, the inventor continued further research and found that the mean free path of a neutral radical particle, that is, the flight distance until it first collides with another particle, is 10-" It was found that at the level of 5 torr, it is about 5 torr, and from this we obtained the following knowledge. ``In other words, if a neutral radical particle does not completely lose its kinetic energy in one collision, the average Film formation does not occur at a distance greater than the free path.Furthermore, neutral radical particles ejected from the plasma interface
Even if a new neutral radical particle is generated by colliding with the raw material gas particle at the location wR, energy is stolen when other neutral particles dissociate, so the excited state that contributes to a-3i film deposition is lost. The amount of sexual radical particles produced gradually decreases. That is, when the distance between the plasma interface and the peripheral wall of the reaction chamber is longer than the mean free path, almost no film is deposited on the peripheral wall of the reaction chamber. On the other hand, charged particles such as electrons and ion particles generated by collisions of neutral radical particles outside the plasma interface are pulled back into the plasma by the magnetic field and help decompose the source gas.

The apparatus of the present invention has been completed based on the above-mentioned findings, and includes a reaction vessel equipped with a reaction chamber and a plurality of gas flow chambers provided on the wall side of the reaction chamber to form a gas flow directed toward a film-forming space region. A gas introducing means having a gas blowing hole, a means for generating plasma within the reaction chamber, and a magnetic field generating means provided on the outer periphery of the reaction chamber for forming a magnetic field within the reaction chamber. This is a characteristic feature.

In the present invention, coaxial magnetic field generating coils and the like are preferably used as the magnetic field generating means.

In the apparatus of the present invention, a magnetic field is formed in the reaction chamber, whereby, for example, excited plasma by microwaves is confined near the substrate, and at the same time, the plasma interface is separated from the peripheral wall of the reaction chamber into a film. Since the neutral radical particles that contribute to deposition are moved away by a distance greater than the mean free path of the particles, this means that the reaction chamber side wall surface of the multi-perforated inner wall, which is the peripheral wall of the reaction chamber that has many holes that supply raw material gas, and the dielectric window. There is no chance of film formation on either the chamber side wall surface or the reaction chamber lower wall surface, and therefore most of the neutral radical particles are forced to gather near the substrate surface, which reduces the utilization efficiency of the raw material gas. The deposition of the film on the surface of the substrate is performed extremely efficiently, and it is possible to obtain a high-quality deposited film product that is always stable, uniform, and rich in properties.

Furthermore, the apparatus of the present invention is configured to form a magnetic field within the reaction chamber, whereby the microwave-excited plasma is confined near the substrate, and at the same time, the plasma interface contributes to film deposition from the peripheral wall of the reaction chamber. In addition to producing the above-mentioned effect by being separated by a distance equal to or greater than the mean free path of the neutral radical particles, charged particles such as electrons and ion particles generated by the collision of neutral radical particles outside the plasma interface are also affected by the magnetic field. This contributes to the excitation (radicalization) of the raw material gas that is entering the plasma region, so the film formation speed can be dramatically increased compared to the conventional plasma CVD deposited film forming apparatus. I can do it.

Furthermore, in the apparatus of the present invention, the exhaust pipe can be provided below the center of the reaction vessel and the substrate support can be rotated, so that the distribution of substances involved in deposited film formation within the film forming space is uniform. It is possible to efficiently form a deposited film that is uniform in quality and thickness.

The raw material gas used to form the deposited film by the apparatus of the present invention may be of the kind that can be excited by microwave energy and chemically interact with it to form the desired deposited film on the substrate surface. For example, when forming an a-3i (H, Gaseous silanes and halocarinated silanes, or gasified substances that can be easily gasified can be used.

These raw material gases may be used alone or in combination.
You may use more than one species in combination. In addition, these raw material gases are
It may be used after being diluted with an inert gas such as He or Ar.

Furthermore, the a-3i film can be doped with a p-type impurity element or an n-type impurity element, and a raw material gas containing these impurity elements as a component can be doped alone.
Alternatively, it can be mixed with the aforementioned raw material gas and/or diluting gas and introduced into the reaction space.

In addition, when two or more kinds of raw material gases are used, one or more of them may be excited and speciated in advance and then introduced into the reaction chamber. .

In the apparatus of the present invention, a plasma is formed in the reaction chamber,
The microwave used to excite the source gas mentioned above is one in which microwaves from a microwave power source are radiated into the reaction chamber via a three-way matching device, a rectangular waveguide, an isolator, etc. Although the frequency varies slightly depending on the scale of the equipment and the type of raw material gas, it is preferably 300 MI (z ~ 30
0 C) Hz, preferably 915 MHz to 245 MHz
It is desirable to set it to about 0 MH7°.

The substrate may be electrically conductive, semiconductive, or electrically insulating; specific examples include metal, ceramics, glass, etc. Can be mentioned.

The temperature of the substrate during the film forming operation is not particularly limited, but is generally in the range of 60 to 450°C, preferably 50 to 350°C.

In addition, when forming a deposited film, the pressure in the reaction chamber must be set to 5X10-6 Torr or less before introducing the raw material gas.
Preferably, the pressure in the reaction chamber is set to below IX 10'' Torr, and when the raw material gas is introduced, the pressure inside the reaction chamber is set to 1X 10-2
It is desirable to use a Torr stand.

In the apparatus of the present invention, a magnetic field is formed in the reaction chamber, thereby confining the microwave-excited plasma near the substrate,
In addition, in order to keep the plasma interface away from the peripheral wall of the reaction chamber by more than the mean free path of the active species contributing to film deposition, a coaxial magnetic field generating coil is used.
It is attached to the outer periphery of the reaction vessel so that the entire wall surface of the reaction chamber peripheral wall, ie, the multi-perforated inner wall, is completely covered and magnetic lines of force are formed parallel to the wall surface.

Therefore, in the apparatus of the present invention, the material of the reaction container is important, and the material of the reaction container is important because the magnetic field formed by the above-mentioned coil within the reaction container [ff! non-magnetic materials such as aluminum, non-magnetic stainless steel,
It is made of dielectric material, etc. However, if it is not possible to attach the coaxial magnetic field generating coil to the outer periphery of the reaction vessel due to installation design or other reasons, it may be possible to attach the coaxial magnetic field generating coil to the outer periphery of the reaction vessel by using a magnetic material such as iron or magnetic stainless steel as part of the reaction vessel. It is possible to compensate for deficiencies.

Hereinafter, the deposited film forming apparatus using the plasma CVD method of the present invention will be explained in more detail with reference to the embodiments of the drawings, but the deposited film forming apparatus of the present invention is not limited thereto.

FIG. 1 is a schematic cross-sectional view of an optimal example of a deposited film forming apparatus using the plasma CVD method of the present invention.

In the figure, components of the device having the same functions as those of the conventional device described above (shown in FIG. 2) are indicated by the same symbols as in FIG.

In the figure, 1 indicates the entire reaction vessel of the apparatus of the present invention. 2 is
The side wall of the reaction vessel, 21, is the bottom wall of the reaction vessel. 6
is erected so as to form a certain gap (gas chamber) with the inner surface of the side wall 2, and is a gas blowout that forms a gas flow toward the film-forming space within the reaction chamber A. It is a multi-perforated inner wall having holes 31, 61... The multi-perforated inner wall usually has no perforations at the lower end 3' and the upper end 6'' where the substrate 10 is not present at opposing positions in the reaction chamber A. 2 and the bottom wall 21 can of course be made into separate members, but
It is usually formed in one piece and in any case is made of a non-magnetic material, such as aluminum, non-magnetic stainless steel, dielectric, or the like. However, in some cases, some of the members of the side wall 2 may be made of iron, magnetic stainless steel, etc.
It can be made of magnetic material such as steel. 4
is a dielectric window made of a material such as titanium oxide, titanium oxide, or synthetic resin, which transmits and radiates the microwave 61 traveling from the microwave power source 6 through the waveguide 5 into the reaction chamber of the reaction container 1. .

The reaction chamber A is hermetically formed by the side wall 2, bottom wall 21, and dielectric window 4 described above. 7, one end is reaction vessel 1
The exhaust pipe opens into the reaction chamber A from the bottom wall 21 of the exhaust pipe, and the other end is connected to an exhaust system (not shown) via a valve means 71.

Usually, four are attached in the circumferential direction, but one may be attached. Reference numeral 8 denotes a raw material gas supply pipe, one end of which opens into the gas chamber B from the side wall of the reaction vessel 1, and the other end communicates with a raw material gas supply source (not shown) via a valve means 81. .

Reference numeral 9 denotes a holding portion for the base body 10, which is installed in the reaction chamber A and supported by support legs 12. The base body holding part 9 has a built-in heater 11 and is usually cylindrical in shape.
The substrate 10 placed on its surface can be rectangular, in which case it is juxtaposed to the surface of the cylindrical holder. However, normally, the base body 10 is of an integral cylindrical shape. Although the substrate holder 9 can be installed at an appropriate position on the bottom wall of the reaction chamber A, it is most effective to install it at the center position. In addition, the base body holding part 9 mechanically connects the support legs 12 to 5 drive means (not shown), and
It can be configured to rotate during the film forming operation via a driving means. Alternatively, the base body holding part 9 may be fixed,
It is also possible to rotate the reaction container 1 around the support legs 12.

In addition, when the base body 10 is cylindrical, the base body holding part 9 has 1
It is not necessarily necessary to use a type that supports only the cylinder, but depending on the case, there may be several base holders coaxially spaced at equal intervals on a circular stage. . can do.

Reference numeral 13 denotes a coaxial magnetic field generating coil attached to the outer circumference of the side wall 2 of the reaction vessel 1. The coil is of an electric type and is of a type whose output can be adjusted.
, magnetic field lines are formed parallel to the wall surface of the reaction chamber A, and the pressure inside the system is, for example, 1O-2T.
0, the magnetic field causes the microwave-excited plasma in the reaction chamber A to be kept at a distance of 5 m or more from the multi-perforated inner wall and confined near the substrate 10, and at the same time, active species contributing to diffuse deposition are removed as indicated by C. It is mounted in such a way that it is located close to the base body 10 so that it does not exist near the wall surface of the multi-perforated inner wall 6 or near the bottom surface of the dielectric window 4. The coaxial magnetic field generating coil 13 does not necessarily have to be a plurality of coaxial magnetic field generating coils, but it is preferable that the coaxial magnetic field generating coil 13 be formed so that the magnetic field lines are in the reaction chamber A and are parallel to the wall surface of the multi-perforated inner wall 6, as shown by D. For this purpose, it is preferable to use a plurality of them because a desired distribution of lines of magnetic force can be obtained.

In the deposited film forming apparatus using the plasma C''-'D method of the present invention having the above-mentioned apparatus configuration, the raw material gas introduced into the reaction chamber A through the raw material gas supply pipe 8 is exposed to microwaves emitted therein. is decomposed and excited by active species, i.e., electrons,
Charged particles that generate ion particles, neutral radicals, etc., and move toward the inner wall of the multi-perforation are subjected to the force of a magnetic field in a direction perpendicular to the direction of incidence due to magnetic field lines, so that The track groove is forcibly broken and no longer approaches the multi-perforated inner wall, and the magnetic field lines are
Because it is formed coaxially with and surrounding it,
It becomes confined in the state shown by C around the base body 10. That is, the microwave-excited plasma is generated in the atmosphere around the substrate 10, indicated by C, and the interface of the plasma is, for example, when the system pressure is adjusted to about 10-2 Torr, Due to the effect of the controlled magnetic field from the coaxial magnetic field generating coil 13, the neutral radical particles are positioned at a distance of at least 5 mm from the multi-perforated inner wall 6, so that neutral radical particles temporarily pass through the plasma interface. Even if it progresses toward the inner wall, its mean free path is short compared to the distance between the plasma interface and the inner wall, and it also passes through the gas flow holes 31 in the multi-perforated inner wall A to the reaction chamber. They may collide with particles of the raw material gas introduced into A, becoming stable particles that do not lose energy, and are pulled back into the plasma by the exhaust flow and excited again to become active species, so that the raw material gas Utilization efficiency will be extremely high. In addition, in the apparatus of the present invention, the active species that are the center of generation are high-energy lower-order particles (e.g., Si'', Si
H", etc.), even if there are neutral particles that have lost energy in the system, there is a very small chance that polysilicon powder will be generated, and even if there were such a case,
Because the raw material gas flows toward the base under pressure, it almost never approaches the multi-perforated inner wall 6.
Therefore, the function of releasing the raw material gas and the function of the inner wall as the peripheral wall of the reaction chamber are always stably maintained.

Furthermore, the apparatus of the present invention does not have gas flow holes in the upper part of the multi-perforated inner wall 3 corresponding to the upper space of the reaction chamber A where no substrate is present at the opposing position, and even if there is a magnetic field line there. Since the dielectric window for introducing microwaves is formed on the side wall surface of the reaction chamber A, there is almost no chance of a film being deposited on the side wall surface of the reaction chamber A, so that the function of the window is maintained stably at all times.

Next, an example of forming a deposited film by operating the apparatus of the present invention will be described.

In this example, one substrate holder 9, shown in FIG.
It is a T-plate cylinder, and has a plurality of coaxial magnetic field generating coils 1 and 1.
5... was used. Furthermore, 5j-F4 gas and SiH4, H2 gas were used as raw material gases.

Valve 8 was closed and valve 71 was opened to degas the inside of reaction chamber A, and the system pressure was adjusted to below I x 10-6 Torr. Next, the heater 11 is energized to lower the temperature of the base 10 to 2.
The temperature is 00℃. Then, the valve 81 is opened and the raw material gas is supplied through the raw material gas supply pipe 8 until the system pressure reaches I x 10"-
At the same time, the microwave power supply 6 is energized to radiate microwaves with a frequency of 2450 MH2 through the dielectric window 4, and the coaxial magnetic field generating coil 1 is energized to 0.2 Torr. The magnetic field having a magnetic flux density of approximately 600 nm was made to extend as far as 6 ranB degrees inside from the multi-perforated inner wall 6. At this point, the supply and exhaust of the raw material gas were adjusted by adjusting the valves 81 and 71 to keep the pressure in the system constant, and while the substrate 10 was being rotated, a film forming operation was performed at a predetermined time. Thereafter, the operation was stopped, the substrate was allowed to cool, and then the substrate was transported out. The same operation was repeated on nine other new substrates to obtain a total of 10 film-formed substrates. 10・
When we tested the deposited films deposited on the surface of book substrates, we found that all of them had an extremely dense composition, were homogeneous throughout the film, and had a uniform thickness. It had extremely excellent conductive properties.

[Summary of effects of the invention]

The apparatus of the present invention is provided with a large number of gas flow holes between a reaction vessel and a base disposed inside the reaction vessel, through which lines of magnetic force generated by a magnetic field generating means such as a coaxial magnetic field generating coil provided on the outer periphery of the reaction vessel are provided. By forming the plasma parallel to the central axis so as to cover the peripheral wall of the reaction chamber, the plasma excited by microwaves or the like is confined around the substrate, and the plasma interface is separated from the wall by more than the mean free path of the active species. This prevents film deposition on the front wall surface.

- Furthermore, in the apparatus of the present invention, the raw material gas is used only for film formation on the substrate, so the raw material gas utilization efficiency is extremely high.

Furthermore, since the apparatus of the present invention uses microwave-excited plasma, it is not limited by the shape of the reaction vessel or the substrate, and has an extremely high degree of freedom in its configuration.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an optimal example of a deposited film forming apparatus using the plasma CVD method of the present invention. FIG. 2 is a schematic cross-sectional view of a deposited film forming apparatus using a conventional plasma CVD method. In the figure, 1... Reaction container, 2... Side wall, 21... Bottom wall, 3
...Multi-perforated inner wall, 31...Gas circulation hole, 3', 3''
... Non-porous part, 4... Dielectric window, 5... Waveguide part, 6
... Microwave power supply, 7 ... Exhaust pipe, 71 ... Valve, 8 ... Raw material gas supply pipe, 81 ... Valve, 9
... Substrate holding part, 10 ... Base, 11 ... Heater, 12 ... Support leg, 13 ... Coaxial magnetic field generating coil, A ... Reaction chamber, B ... Gas chamber, C ...Microwave excited plasma region, D...Magnetic field line region, 61.-Microwave.

Claims (3)

[Claims] (1) a reaction vessel including a reaction chamber; a gas introduction means provided on the wall side of the reaction chamber and having a plurality of gas blowing holes through which a gas flow toward a film forming space is formed; and plasma in the reaction chamber. A deposited film forming apparatus using a plasma CVD method, comprising: a means for generating a magnetic field; and a magnetic field generating means provided on the outer periphery of the reaction chamber for forming a magnetic field within the reaction chamber. (2) A deposited film forming apparatus using a plasma CVD method according to claim 1, wherein the means for generating plasma is a microwave discharge generating means. (3) The plasma C according to claim 1, wherein at least a portion of the reaction vessel is formed of a non-magnetic material.
Deposited film forming device using VD method.