JPH04247868A - Thin film forming device - Google Patents

Abstract

PURPOSE:To allow sufficient dealing with in the case of the purpose for crystallization of a thin film, and to allow the detection and control of the quantity of the incident ions on a substrate to be formed with the thin film and the quantity of the incident ions on the substrate as well as the distribution thereof within the surface of the substrate. CONSTITUTION:A 2nd vacuum chamber is provided in a 1st vacuum chamber 51 and a discharge device which maintains the vacuum degree in the 1st vacuum chamber 51 higher than the vacuum degree in the 2nd vacuum chamber 52 is provided, and further, a grid 12 is disposed in the communicating part between the 1st vacuum chamber 51 and the 2nd vacuum chamber 52.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a thin film forming apparatus, and more particularly, to a thin film forming apparatus for forming a thin film using CVD (Chemical Vapor Depot).
The strong reactivity that is the advantage of the PVD (situation) method and the PVD (
Physical Vapor Deposit
The present invention relates to a thin film forming apparatus that can simultaneously realize film formation in a high vacuum (which allows formation of dense and strong films), which is an advantage of the on) method.

0002

[Prior Art] Japanese Unexamined Patent Publication No. 59-89763 discloses that a counter electrode is provided in a vacuum chamber to hold a substrate on which a thin film is to be formed facing an evaporation source that evaporates an evaporation substance, and a counter electrode that is connected to the evaporation source and the counter electrode. A thin film is formed by arranging a grid between them, further arranging a filament that generates thermoelectrons between the grid and the evaporation source, and setting the potential of the grid to be positive with respect to the potential of the filament. There is a forming device. In this thin film forming apparatus, the evaporation material (
The thin film forming material) is first ionized by hot electrons from the filament. When this ionized material passes through the grid, it is accelerated by the action of the electric field from the grid toward the counter electrode and collides with the substrate on which the thin film is to be formed, forming a film with good adhesion. In the above thin film forming apparatus, the conventional C
Compared to the VD method, it is possible to form thin films in high vacuum.

0003

However, the above-mentioned conventional thin film forming apparatus has the drawback that it cannot be used satisfactorily when the purpose is to crystallize a thin film. There is also the problem that it is difficult to detect and control the amount of ions incident on the substrate on which the thin film is formed and the distribution in the plane of the substrate.

0004

[Means for solving the problem] The invention of claim 1 provides the first
a vacuum chamber, a counter electrode disposed in the first vacuum chamber and holding a thin film forming material on which a thin film is to be formed, an active gas or an inert gas, and an active gas and an inert gas communicated with the first vacuum chamber. a second vacuum tank into which a mixed gas of the first vacuum tank and the first vacuum tank are introduced; 2. A grid that is disposed in a communication portion with the second vacuum chamber and is capable of passing the evaporation substance evaporated by the evaporation source;
a filament that is disposed between the evaporation source and the grid and generates thermoelectrons; a grid positive potential means that makes the potential of the grid positive with respect to the potential of the filament; and a vacuum degree of the first vacuum chamber. This thin film forming apparatus has an evacuation means that brings the degree of vacuum to a state higher than that of the second vacuum chamber.

A second aspect of the present invention is the thin film forming apparatus according to the first aspect, which includes an evaporation source positive potential setting means for making the potential of the evaporation source positive with respect to the potential of the filament.

[0006] The invention according to claim 3 provides a first vacuum chamber, a counter electrode disposed in the first vacuum chamber and holding a thin film forming material on which a thin film is to be formed, and an active electrode connected to the first vacuum chamber. a second vacuum chamber into which a gas or an inert gas and a mixed gas of an active gas and an inert gas are introduced; an evaporative substance supply means for supplying an evaporative substance in the form of vapor or mist into the second vacuum chamber; a heater for heating the evaporative substance supplied by the evaporative substance supply means; a plurality of small hole nozzles for uniformly releasing the evaporative substance in good direction; a grid disposed in a communicating portion with a second vacuum chamber and capable of passing the evaporation substance evaporated by the evaporation source; a filament disposed between the evaporation source and the grid and generating thermoelectrons; A thin film forming apparatus comprising: a grid positive potential means for making the potential of the filament positive with respect to the potential of the filament; and an evacuation means for making the degree of vacuum in the first vacuum chamber higher than the degree of vacuum in the second vacuum chamber. .

[0007] The invention according to claim 4 provides a first vacuum chamber, a counter electrode arranged in the first vacuum chamber and holding a thin film forming material on which a thin film is to be formed, and an active electrode connected to the first vacuum chamber. a second vacuum tank into which a gas or an inert gas and a mixed gas of an active gas and an inert gas are introduced; an evaporation source disposed in the second vacuum tank to evaporate an evaporable substance forming a thin film; a grid that faces the electrode and is disposed in a communication portion between the first vacuum chamber and the second vacuum chamber and allows the evaporation substance evaporated by the evaporation source to pass therethrough; and a grid disposed between the evaporation source and the grid. a filament that generates thermoelectrons; a grid positive potential means that makes the potential of the grid positive with respect to the potential of the filament; and a state in which the degree of vacuum in the first vacuum chamber is higher than the degree of vacuum in the second vacuum chamber. a plurality of annular electrodes disposed in a ring shape with one point as the center on the same plane parallel to the counter electrode and the grid between the counter electrode and the grid; This thin film forming apparatus has annular electrode potential setting means that sets a negative potential to the grid and makes the potential of the inner annular electrode lower than the potential of the outer annular electrode.

[0008]

According to the first aspect of the invention, an active gas, an inert gas, and a mixed gas of an active gas and an inert gas are introduced into the second vacuum tank, and the evaporative substance is evaporated by the evaporation source. Thermal electrons are generated by the filament, and since the grid has a positive potential with respect to the filament, the introduced gas is ionized in the space between the grid and a high-density plasma. The evaporated substance is ionized by electrons and gas ions in the plasma, and after passing through the grid, the ionized gas and evaporated substance are accelerated toward the film forming material held at the counter electrode by the action of the electric field. , together with non-ionized evaporated substances, contribute to the formation of a thin film. Furthermore, in the invention of claim 2, the potential of the evaporation source is made positive with respect to the potential of the filament by the evaporation source positive potential making means, and an electric field is also formed from the evaporation source to the filament. Ionization rate is increased.

In the invention of claim 3, an active gas or an inert gas and a mixed gas of an active gas and an inert gas are introduced into the second vacuum tank, and the second vacuum tank is
An evaporated substance in the form of steam or mist is supplied into the vacuum chamber. This evaporated substance is heated by a heater and uniformly discharged from a plurality of small hole nozzles toward the counter electrode. Thermionic electrons are then generated by the filament, and the introduced gas is ionized in the space between the filament and the grid, generating a high-density plasma. The evaporated substance is ionized by electrons and gas ions in the plasma, and after passing through the grid, the ionized gas and evaporated substance are accelerated toward the film forming material held at the counter electrode by the action of the electric field. , together with non-ionized evaporated substances, contribute to the formation of a thin film. In this thin film forming device,
Since the evaporated material supply means, the heater, and the plurality of small hole nozzles are provided, the evaporated material can be imparted with adjustable kinetic energy and uniformly sprayed toward the counter electrode.

[0010] In the invention of claim 4, claims 1, 2 and 3
In addition to the same operation as in the invention, the annular electrode potential setting means sets the annular electrode at a negative potential with respect to the grid, and the potential of the inner annular electrode is set lower than the potential of the outer annular electrode. Therefore, the electric field generated in the vacuum chamber is from the grid to the filament and the annular electrode, and from the counter electrode to the annular electrode, or from the annular electrode to the counter electrode, and from the outer annular electrode to the inner annular electrode, i.e. the annular electrode. This becomes a composite electric field of electric fields directed toward the center of the electrode.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. A first embodiment corresponding to the third aspect of the invention will be described. FIG. 1 shows a thin film forming apparatus 10 according to the first embodiment.
1 is shown. In the figure, numeral 2 indicates a base plate,
A bell jar 1 is attached to the base plate 2 via a packing 3, and a first vacuum chamber 51 is formed. A vacuum wall 5 is provided in the vacuum chamber 51, and the vacuum wall 5 is attached to the base plate 2 via the packing 3, forming a second vacuum chamber 52. vacuum wall 5
An opening 5a is formed in the upper surface of the vacuum chamber 5, and a mesh grid 12 is provided to close the opening 5a, and the first vacuum chamber 51 and the second vacuum chamber 52 communicate with each other through the grid 12. The grid 12 is attached to the vacuum wall 5 via an insulating packing 7 and is electrically insulated from the vacuum wall 5.

A hole 2A and a hole 2B are formed in the base plate 2, and the hole 2A is formed in the first vacuum chamber 51 and the hole 2B is formed in the second vacuum chamber 51.
It is connected to the vacuum chamber 52. An evacuation device is connected to each of the holes 2A and 2B, and differential evacuation is performed by this evacuation device so that the degree of vacuum in the first vacuum chamber 51 is higher than the degree of vacuum in the second vacuum chamber 52. Reference numeral 4 indicates a gas supply device, and the gas supply device 4 supplies an active gas, an inert gas, and a mixed gas of an active gas and an inert gas into the second vacuum chamber 52 .

The base plate 2 is provided with electrodes 20a, 20b, 21a, 21b, 22, 2 while maintaining airtightness and electrical insulation inside the first vacuum chamber 51 and the second vacuum chamber 52.
3 is provided. These electrodes 20a, 20b, 2
1a, 21b, 22, and 23 electrically connect the inside and outside of the first vacuum chamber 51 and the second vacuum chamber 52.

The tip of the electrode 23 is bent in the horizontal direction, and the counter electrode 13 is provided at this tip. Counter electrode 13 faces grid 12 . A substrate 100 as a thin film forming material is held on the lower surface of the counter electrode 13 by means not shown. Electrode 22 is connected to grid 12 by lead wire 54 .

An evaporation source 10 is provided across the electrodes 20a and 20b, and this evaporation source 10 is disposed within a second vacuum chamber 52. The evaporation source 10 is for evaporating substances that are solid at room temperature, such as metals and semiconductors.
It has a boat shape. The shape of the evaporation source 10 may be a coil shape or a pot shape. It is also possible to use a conventionally used evaporation source such as a beam evaporation source as appropriate.

A filament 11 for generating thermoelectrons is provided across the electrode 21a and the electrode 21b. The filament 11 is formed by arranging a plurality of thin wires in parallel at regular intervals. In addition, the shape of the filament 11 may be any shape, such as a mesh shape or a spiral shape, as long as it can cover the spread of particles of the evaporation substance evaporated by the evaporation source 10.

The electrode 20a and the electrode 20b are connected via an AC power source 30. Further, the electrode 21a and the electrode 21b are connected via an AC power source 31. An electrode on one side of the AC power source 31 is connected to the electrode 20a. A DC power supply may be used instead of the AC power supplies 30 and 31.
Its polarity may be either. The electrode 22 is connected to the positive electrode side of a DC power source 32. Further, the negative electrode side of the DC power source 32 is connected to the electrode 20a. Furthermore, electrode 23 is connected to electrode 20a. Note that, although the above electrical connections actually include various switches for executing the vapor deposition process, illustration thereof is omitted.

Next, an embodiment of the thin film forming apparatus 101 will be described. The thin film forming apparatus 101 is operated, and the first vacuum chamber 51 and the second vacuum chamber 52 are heated to 10 to the negative 4th power Pa.
After evacuation to a certain level, Ar and O2 are introduced by the gas supply device 4, and evacuation is performed so that the first vacuum chamber 51 has a higher vacuum than the second vacuum chamber 52. The introduction of this gas causes the pressure in the second vacuum chamber 52 to change from 10 Pa to 10 −2 Pa, and the pressure in the first vacuum chamber 51 to 1 P.
This is done so that Pa becomes 10 to the power of minus 3 from a.

Furthermore, Al, which is an evaporation substance, is evaporated by the evaporation source 10. When Al is used, the substrate 100
An insulating thin film of aluminum is formed on. In addition,
If In is used as the evaporation substance, a transparent conductive thin film can be formed on the substrate 100. Grid 12 is at a positive potential with respect to filament 11 and counter electrode 13 . Therefore, the introduced gas is ionized and a high-density plasma is generated mainly between the filament 11 and the grid 12. Furthermore, Al evaporated by the evaporation source 10 is also used in the space between the filament 11 and the grid 12 and the grid 1.
2, it is ionized by electrons in the plasma and ionized gas. After passing through the grid 12, the ionized gas and vaporized material are accelerated toward the substrate 100 by the action of the electric field, and are subjected to the formation of a thin film together with the non-ionized vaporized material.

Furthermore, since most of the introduced gas that has passed through the grid 12 and has not been ionized is exhausted from the holes 2A, only gas ions and evaporated substances (including ionized ones) contribute to thin film formation. I will do it. When a thin film is formed in this way, the first vacuum chamber 51, which is a film forming chamber, is kept at a higher vacuum than in the case of a normal gas introduction process, so it has excellent adhesion to the substrate 100 and has low crystallinity. A good thin film can be obtained. Furthermore, since the ionization rate of the evaporated substance is extremely high and stable, the reactivity of the substance forming the thin film is improved, making it possible to easily and reliably obtain a thin film with desired composition and physical properties.

Next, another embodiment will be explained. Since the thin film forming apparatus according to the other embodiments has parts having the same structure as the thin film forming apparatus 101 according to the first embodiment, parts having the same structure are given the same reference numerals as those in the first embodiment. Therefore, a description of its structure and operation will be omitted. A second embodiment corresponding to claim 2 will be described. FIG. 2 shows a thin film forming apparatus 102 according to a second embodiment. Electrode 20a is connected to the positive electrode of DC power supply 33. Further, the electrode 21a is connected to the negative electrode of a DC power source 33.

In the thin film forming apparatus 102, an electric field is also formed from the evaporation source 10 toward the filament 11, and high-density plasma is also generated in the space between the evaporation source 10 and the filament 11. Therefore, the evaporated substance is evaporated from the evaporation source 10
It is ionized by electrons that enter the space and gas ions in that space. Furthermore, similar to the thin film forming apparatus 101 of the first embodiment, ionization is also performed in the space between the filament 11 and the grid 12 and in the vicinity of the grid 12. Therefore, the thin film forming apparatus 102 is more efficient than the thin film forming apparatus 101.
It is possible to increase the ionization rate of the evaporated substance.

A third embodiment corresponding to claim 3 will be explained. FIG. 3 shows a thin film forming apparatus 103 according to a third embodiment.
shows. In the thin film forming apparatus 103, a material supply case 110 is arranged below the filament 11 instead of the evaporation source 10 of the thin film forming apparatuses 101 and 102 of the above embodiments. A material supply pipe 120 is attached to the material supply case 110. This material supply pipe 120 is connected to a material supply device (not shown), and the evaporation material constituting the thin film is supplied in the form of vapor or mist into the material supply case 110 through the material supply pipe. There is. A plurality of small hole nozzles 110a are provided on the upper surface of the material supply case 110, and the material supply case 110
A heater 110b is provided on the side surface. Furthermore, the second
As in the thin film forming apparatus 102 of the embodiment, the material supply case 1
10 may be configured to have a positive potential with respect to the filament 12.

When the thin film forming apparatus 103 is operated, the first
After evacuating the vacuum chamber 51 and the second vacuum chamber 52 to about 10 −4 Pa, the gas supply device 4 supplies Ar
and H2 are introduced, and the first vacuum chamber 51 is replaced by the second vacuum chamber 5.
2, evacuation is performed to create a high vacuum. The introduction of this gas is performed so that the pressure inside the second vacuum chamber 52 ranges from 10 Pa to 1 Pa.
0 to the minus square power Pa, and the pressure inside the first vacuum chamber 51 is changed from 1 Pa to 10 to the minus third power Pa. In the thin film forming device 103, S is supplied from the material supply device.
iH4 is supplied into the material supply case 110 through the material supply pipe 120 in the form of steam or mist. Then, it is heated by the heater 110b. This heater 110b
The pressure inside the material supply case 110 can be adjusted depending on the degree of heating. Therefore, the pressure difference between the inside and outside of the material supply case 110 can be adjusted, and the kinetic energy of SiH4 can be adjusted. Therefore, SiH4 can be uniformly and efficiently discharged toward the counter electrode 13 from the plurality of small hole nozzles. The substrate 100 is made of a-Si or p-Si.
A thin film composed of -Si is formed.

[0025] If CH4 is used as a thin film forming material,
A carbon thin film or a diamond thin film can be formed. In addition, N2 or Ar or N2 and A are introduced as gases.
using SiH4+N as the evaporation material.
If H3 is used, a thin film made of SiNx can be constructed.

A fourth embodiment corresponding to claim 4 will be described. FIG. 4 shows a thin film forming apparatus 104 according to the fourth embodiment.
shows. This thin film forming apparatus 104 is provided with annular electrodes 14a, 14b, and 14c between the counter electrode 13 and the grid 12. As shown in FIG.
4b and 14c are ring-shaped, and their diameter is the same as that of the annular electrode 1.
4a, the annular electrode 14b, and the annular electrode 14c become smaller in this order. The annular electrodes 14a, 14b, 14c are the counter electrode 1
3 and the grid 12, and are arranged concentrically on the same plane. Annular electrodes 14a, 14b, 1
4c are fixedly supported by support electrodes 64a, 64b, and 64c, respectively. These supporting electrodes 64a, 64b, 6
4c is connected to terminals 24a, 24b, and 24c of the electrode 24.

The terminals 24a, 24b, and 24c are connected to a DC power source 34 and a DC power source 35 via ammeters 65a, 65b, and 65c, respectively. The annular electrodes 14a, 14b, 14c are connected to the grid 12 by the DC power supply 35.
It is designed to have a negative potential with respect to the potential of . Further, potentials are distributed by the DC power supply 34 so that the electric field is directed toward the center of the annular electrodes 14a, 14b, and 14c. Note that the method of connecting the annular electrodes 14a, 14b, 14c and the DC power source is not limited to this, as long as the above state can be obtained.

The ring-shaped annular electrodes 14a, 14b,
14c, as shown in FIG. 6, a combination of a ring-shaped annular electrode 74a and a square annular electrode 74b, and as shown in FIG. 7, a combination of an octagonal annular electrode 84a and this annular electrode 84a.
A combination of a smaller octagonal annular electrode 84b and a ring-shaped annular electrode 84c, a square annular electrode 94a, a square annular electrode 94b one size smaller than this annular electrode 94a, and a square annular electrode 94b one size smaller than this annular electrode 94b. A combination with annular electrode 94c may also be used. Further, the shape, number, and combination of the annular electrodes are determined as appropriate depending on the shape of the device used, and the structure is not limited to those shown in FIGS. 5 and 6.

In the thin film device 104, A is used as the introduced gas.
Using r and O2, the gas introduced into these is transferred to the second vacuum chamber 5.
The pressure in the first vacuum chamber 51 is from 1 Pa to 10 to the minus 3 power P.
Introduce it so that it becomes a. And Al as an evaporated substance
By using this method, a high-quality aluminum insulating thin film can be formed. Furthermore, if In is used as the evaporative substance 7, a transparent conductive thin film can be formed.

After passing through the grid 12, the gas ions and ionized evaporated substances are accelerated toward the substrate 100 by the action of the electric field and are incident on the substrate 100. At this time, the incident energy of the ions is approximately determined by the potential difference between the counter electrode 13 and the grid 12. Annular electrode 1
In the absence of 4a, 14b, and 14c, ions fly while being spread out due to the space charge effect. Furthermore, because the electric field at the end of the electrode becomes weak due to the end effect of the electrode, the current density distribution of ions incident on the substrate 100 is not uniform.
, 65c can detect the in-plane distribution of the ion current density, so by adjusting the installation positions of the annular electrodes 14a, 14b, 14c and the voltage of the DC power supply 34, the in-plane distribution of the ion current density with respect to the counter electrode 13 can be detected. It can be made uniform. Moreover, the annular electrodes 14a, 14b
, 14c also act as electrodes for extracting ions from the vicinity of the grid, so it is also possible to adjust the amount of ions incident on the counter electrode 13 by adjusting the voltage of the DC power supply 35. Therefore, the physical properties of the thin film can be made uniform and the physical properties can be easily controlled.

[0031]

As described above, according to the present invention, it is possible to form a thin film under a high degree of vacuum, and it becomes possible to obtain a highly pure thin film in which very few gas molecules are incorporated. Normally, the density of a thin film is considered to be lower than that of the bulk, but now it is possible to obtain a density that is very close to that of the bulk. Therefore, it can now be used not only for thin films for insulation, protection, passivation, etc., but also for thin film crystallization.
It is possible to provide a thin film forming apparatus that is extremely suitable for forming semiconductor thin films constituting C, LSI, and the like. Furthermore, it becomes possible to easily detect and control the amount of ions incident on the substrate on which the thin film is formed and the distribution in the plane of the substrate.

Furthermore, the low-temperature thin film forming material is not limited to a thin film composed of a single element such as a metal thin film, but also a film having uniform thickness and physical properties and having a closer stoichiometry. It is also possible to create high-quality chemical thin films with good adhesion and less incorporation of impurities. Moreover, it can sufficiently cope with mass production.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a thin film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a thin film forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a thin film forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a thin film forming apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a plan view of an annular electrode installed in a thin film forming apparatus according to a fourth embodiment.

FIG. 6 is a plan view of an annular electrode having another shape.

FIG. 7 is a plan view of an annular electrode having another shape.

FIG. 8 is a plan view of an annular electrode having another shape.

[Explanation of symbols]

101 Thin film forming device 102 Thin film forming device 103 Thin film forming device 104 Thin film forming device 4 Gas introduction device 10 Evaporation source 12 Filament 13 Grid 110 Material supply case 120 Material supply pipe 100　　　　　　　　　　　　 51 First vacuum chamber 52 Second vacuum chamber 14a　　　　　　Annular electrode 14b Ring-shaped electrode 14c　　　　　　　Annular electrode 74a　　　　　　　Annular electrode 74b Annular electrode 84a　　　　　　　Annular electrode 84b Annular electrode 84c Annular electrode 94a　　　　　　Annular electrode 94b Ring-shaped electrode 94c Annular electrode

Claims (4)

[Claims] 1. A first vacuum chamber; a counter electrode disposed in the first vacuum chamber and holding a thin film forming material on which a thin film is to be formed;
A second vacuum chamber is connected to the first vacuum chamber and into which an active gas or an inert gas and a mixed gas of an active gas and an inert gas are introduced.
a vacuum chamber; an evaporation source disposed in the second vacuum chamber for evaporating an evaporation substance forming a thin film; a grid through which the evaporation material evaporated by the evaporation source can pass; a filament disposed between the evaporation source and the grid and generating thermoelectrons; and a grid positive potential means for controlling the degree of vacuum of the first vacuum chamber to a second level.
A thin film forming apparatus having an evacuation means that brings the degree of vacuum to a level higher than that of a vacuum chamber. 2. The thin film forming apparatus according to claim 1, comprising means for making the evaporation source positive potential for making the potential of the evaporation source positive with respect to the potential of the filament. 3. A first vacuum chamber; a counter electrode disposed in the first vacuum chamber and holding a thin film forming material on which a thin film is to be formed;
A second vacuum chamber is connected to the first vacuum chamber and into which an active gas or an inert gas and a mixed gas of an active gas and an inert gas are introduced.
a vacuum chamber; an evaporative substance supply means for supplying the evaporative substance in the form of vapor or mist into the second vacuum chamber; a heater for heating the evaporative substance supplied by the evaporative substance supply means; a plurality of small hole nozzles for discharging well and uniformly; and a plurality of small hole nozzles arranged opposite to the counter electrode and in a communicating portion between the first vacuum chamber and the second vacuum chamber to discharge the evaporation material evaporated by the evaporation source. a filament that is disposed between the evaporation source and the grid and generates thermoelectrons; grid positive potential means that makes the potential of the grid positive with respect to the potential of the filament; A thin film forming apparatus comprising: exhaust means for bringing the degree of vacuum of the vacuum chamber to a higher degree of vacuum than the degree of vacuum of a second vacuum chamber. 4. A first vacuum chamber; a counter electrode disposed in the first vacuum chamber and holding a thin film forming material on which a thin film is to be formed;
A second vacuum chamber is connected to the first vacuum chamber and into which an active gas or an inert gas and a mixed gas of an active gas and an inert gas are introduced.
a vacuum chamber; an evaporation source disposed in the second vacuum chamber for evaporating an evaporation substance forming a thin film; a grid through which the evaporation material evaporated by the evaporation source can pass; a filament disposed between the evaporation source and the grid and generating thermoelectrons; and a grid positive potential means for controlling the degree of vacuum of the first vacuum chamber to a second level.
an evacuation means for bringing the vacuum level higher than that of the vacuum chamber; and a plurality of evacuating means arranged in an annular manner with one point as the center on the same plane parallel to the counter electrode and the grid between the counter electrode and the grid. A thin film forming apparatus comprising: a ring-shaped electrode; and ring-shaped electrode potential setting means for setting the ring-shaped electrode at a negative potential with respect to the grid, and setting the potential of the inner ring-shaped electrode to be lower than the potential of the outer ring-shaped electrode.