JPH0426758A - Thin film forming device - Google Patents

Abstract

PURPOSE:To form a thin film which is dense and has a good adhesive property and reactivity on a substrate by providing a magnet near a grid to generate a magnetic field near the grid surface and applying spiral motion to the electrons from a filament. CONSTITUTION:The evaporating material evaporated from an evaporating source 4 is ionized by the thermions from a filament 6 and is accelerated toward a counter electrode 12 by the grid 8 to form the thin film on a substrate 13. The permanent magnet 17 having the length below the diameter of the grid 8 and a suitable thickness is installed near the grid 8 in such a manner that the N pole and S pole are positioned on the electrode 7 side of the grid 8 and another side, respectively. The grid 8 is disposed within the space inclusive of the N and S pole faces of the magnet 17. The electrons heading toward the grid 8 are spirally moved by the magnetic field and are easily captured. The gases introduced into a vacuum chamber are ionized near the same, by which the ionization of the evaporating metal is enhanced. The dense thin film having the good adhesive property and reactivity is formed on the substrate 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film forming apparatus based on a vacuum evaporation method. The present invention relates to a thin film forming apparatus that can be applied to forming transparent conductive thin films such as O, or Fe--N nitride magnetic thin films.

[Conventional technology]

Various types of thin film forming apparatuses have been known in the past, and their methods are also wide-ranging. For example, vacuum evaporation method,
rf magnetron sputtering method, ion blating method, CVD (Chemical VaporDepo
position) method, MBE (Molecular
r Beam Epitaxy) method, etc.

In recent years, thin films have been fabricated using these methods in conjunction with a method of ionizing the introduced gas into a plasma state, such as high-frequency electric field method and electron cyclotron resonance method. Reactive film formation, such as ionization to create an oxide film, is being carried out.

[Problem to be solved by the invention]

However, conventional thin film forming apparatuses have problems such as weak adhesion between the formed thin film and the substrate on which the thin film is formed, or difficulty in forming a thin film on a substrate that is not heat resistant. there were.

Therefore, in order to solve these problems, the applicant first developed a thin film forming apparatus in which a substrate is held on a counter electrode facing an evaporation source, and a grid is placed between the counter electrode and the evaporation source. At the same time, they proposed an apparatus in which a filament for generating thermionic electrons is arranged between the grid and the evaporation source, and the grid is set at a positive potential with respect to the filament to form a thin film (Japanese Patent Laid-Open No. 89763/1983). .

In this thin film forming apparatus, the evaporated substance evaporated from the evaporation source is first ionized by thermionic electrons from the filament.
This ionized evaporated substance has the characteristic that when it 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, forming a thin film with good adhesion.

The purpose of the present invention is to improve the ionization rate of the introduced gas and the evaporated substance, thereby further improving the adhesion between the thin film and the substrate, making the film denser, and improving the ionization rate of the introduced gas and the evaporated substance based on the thin film forming apparatus according to the prior art. An object of the present invention is to provide a thin film forming apparatus that can lower the substrate temperature.

[Means and effects for solving the problems] In order to achieve the above object, the thin film forming apparatus of the present invention includes a vacuum chamber into which an active gas, an inert gas, or a mixture of these gases is introduced, and a an evaporation source for evaporating the evaporated substance in the vacuum chamber; a counter electrode arranged to face the evaporation source in the vacuum chamber and holding the thin film forming substrate; and a counter electrode disposed between the evaporation source and the counter electrode. a filament for generating thermionic electrons; a grid disposed between the filament and the counter electrode to allow the evaporated substance to pass; a power supply means for achieving a predetermined electrical state in the vacuum chamber; The apparatus is characterized in that it has a conductive means that electrically connects the inside of the tank and the power supply means, and that a magnet is provided near the grid, and the magnet generates a magnetic field near the grid surface.

Hereinafter, the configuration and operation of the thin film forming apparatus according to the present invention will be explained in more detail.

The thin film forming apparatus on which the present invention is based is the apparatus described in the above-mentioned publication, and its configuration and principle will be explained.

This thin film forming apparatus has a vacuum chamber, a counter electrode, a grid, a filament for generating thermionic electrons, and an evaporation source, and an active gas, an inert gas, or a mixture of these gases is introduced into the vacuum chamber. .

A counter electrode is placed within the vacuum chamber and holds the substrate facing the evaporation source.

The grid allows passage of evaporated material from the evaporation source, is disposed between the evaporation source and the counter electrode, and is placed at a positive potential relative to the potential of the filament and the counter electrode. Therefore, an electric field from the grid toward the substrate and an electric field from the grid toward the evaporation source are formed in opposite directions in the vacuum chamber.

A filament for generating thermionic electrons is placed closer to the evaporation source than the grid in the vacuum chamber, and the thermoelectrons generated by the filament are used to ionize a portion of the evaporated substance.

In the thin film forming apparatus having the above configuration, a part of the evaporated substance from the evaporation source is ionized into positive ions by electrons from the filament. The partially ionized evaporated substances pass through the grid, are further ionized into positive ions by the ionized gas, are accelerated toward the substrate by the action of the electric field, and collide with the substrate to form a thin film. Form.

Note that the electrons from the filament are emitted from the filament with kinetic energy corresponding to the filament temperature, so they pass through the positive potential grid without being absorbed immediately, are pulled back by the Coulomb force of the grid, and then pass through the grid. Then, the vibrational motion is repeated around the grid, and finally it is absorbed by the grid, so it does not reach the substrate, and the substrate is not subjected to electron bombardment by thermionic electrons, so there is almost no heating effect from it.

Now, in the present invention, in order to further reduce the influence of these thermoelectrons on the substrate and to further increase the ionization rate of the introduced gas and evaporated substance, a magnet is installed near the grid portion of the apparatus having the above configuration. By installing this magnet, the electrons move spirally due to the magnetic field applied by the magnet, which increases the number of collisions with gas and evaporated substances, and at the same time increases the time the electrons stay near the filament, so they are eventually captured by the grid. It becomes easier to get caught.

The magnetic field is applied parallel to the grid surface and the counter electrode using a permanent magnet, or an electromagnet is used.
A magnetic field is applied perpendicular to the grid plane. In this case, the magnetic field may be an alternating current.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a thin film forming apparatus showing an embodiment of the present invention.

In FIG. 1, a base plate 1 and a Pelger 2 are integrated via a backing 21 to form a vacuum chamber. The base plate 1 includes electrodes 3, 5, 7.
Although it is penetrated by 9, the support electrode 3,
The penetration portions 5 and 7.9 are airtight, and furthermore, these support electrodes 3 degrees 5, 7.9 and the base plate 1 are electrically insulated. Further, a hole IA formed in the center of the base plate 1 is connected to a vacuum exhaust system (not shown).

Here, the pair of support electrodes 3 support the resistance heating type evaporation source 4, but an electron beam heating type evaporation source may be used instead of the resistance heating type evaporation source. Furthermore, a filament 6 made of tungsten or the like for generating thermoelectrons is supported between the pair of electrodes 5 that also serve as supports. The shape of the filament 6 is determined so as to cover the spread of the substance evaporated from the evaporation source 4 by arranging a plurality of linear filaments in parallel or forming a mesh.

A grid 8 is supported on the support electrode 7, and the grid 8 has a shape that allows the evaporated substance to pass through, and in the illustrated example, it has a mesh shape.

A counter electrode 12 is supported on the support electrode 9, and a substrate 13 for forming a thin film is held on the surface of the counter electrode 12 facing the evaporation source 4.

In FIG. 1, numerals 14, 15, and 16 indicate power supplies for realizing a predetermined electrical state in the vacuum chamber, 14 is an AC power source for the evaporation source, 15 is an AC power source for heating the filament, 16 connects the grid 8 to the filament 6 and the counter electrode 12
These power supplies are electrically connected to each support electrode by wiring. Although not shown, the wiring includes switches.

In the vicinity of the grid 8, a permanent magnet 17 is installed, which has a length less than the diameter of the grid 8 and an appropriate thickness, and has an N pole and an S pole on the electrode 7 side and the other side of the grid 8, respectively. The grid 8 is placed in a space including the N and S pole faces of the magnet 17. Due to this. Electrons approaching the grid 8 are rotated by the magnetic field and are easily captured.

Therefore, the gas introduced into the vacuum chamber is further ionized in this vicinity.

In addition, an electromagnet may be used as the magnet 17 so that the magnetic field can be changed, and in this case, it is placed in the same position as a permanent magnet,
Apply a magnetic field perpendicular to the grid plane.

Furthermore, when using an electromagnet, it is recommended to flow cooling water around the magnet to prevent the temperature of the electromagnet from rising. In this case as well, the ionization rate can be increased.

Next, an example will be described in which an oxide superconducting thin film is manufactured using the thin film forming apparatus having the above-described configuration.

As an evaporation method, an electron beam heating method is used as an evaporation source. As the evaporated substance, Y2O31BajCu was put into the hearth of the electron gun of Odai, and after the inside of the vacuum chamber was evacuated, oxygen gas was introduced and the atmosphere inside the vacuum chamber was adjusted to an oxygen gas pressure of 1 to 5.
Set to X10-'torr. At this time, Ar gas was
% may be mixed.

When current is passed through the filament 6 in this state to generate thermoelectrons, part of the oxygen gas is ionized by collision with the thermoelectrons. Next, the evaporated substance is evaporated at a predetermined evaporation rate, and the film composition on the substrate 13 is Y:Ba:Cu=1:2:3.
The ratio should be as follows.

Note that the substrate 13 is 5rTiO3 (110), MgO
A ceramic single crystal such as (100) is used.

Further, the substrate 13 is heated in advance within the range of 400°C to 650°C.

Next, when a voltage of several hundred volts is applied between the grid 8 and the counter electrode 12, the electrons are pulled toward the grid 8 side. At this time, the magnet 17 installed near the grid 8
When a magnetic field of 0 to 2000 e is applied, electrons near the grid 8 move in a spiral manner, further ionizing oxygen gas and evaporated metal, and since they remain in the grid for a long time, they are eventually absorbed by the grid 8. Therefore, due to the action of the electric field between the counter electrode 12 and the grid 8 and the magnetic field, the thermoelectrons from the filament 6 do not reach the substrate 13.

Note that the magnet is not limited to the vicinity of the grid;
If it is installed in a wide area between the filament 6 and the counter electrode 12, such as between the filament 6 and the grid 8, the ionization of oxygen gas and evaporated metal will be further enhanced.

Now, in the apparatus of the present invention, the ionization of oxygen gas and evaporated metal is enhanced as described above, so that the metal ions and gas ions cause a reaction near the substrate, and the metal ions hit the substrate by the electric field. A dense, highly adhesive, and highly reactive thin film can be produced on a substrate, and an oxide superconducting thin film with a high critical temperature can be produced even when the substrate temperature is low.

〔Effect of the invention〕

As explained above, in the thin film forming apparatus according to the present invention, it is possible to fabricate a thin film that is dense and has good adhesion at a low substrate temperature, and is particularly effective in reactive film formation while introducing a gas. Oxide thin film, e.g. Y-Ba-Cu
-0 superconducting thin film, In.

Application to the formation of transparent conductive thin films such as No. 03, Fa-N nitride magnetic thin films, etc. is possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a thin film forming apparatus showing an embodiment of the present invention. 1...Base plate, 2...Pelger, 3
゜5.7.9... Electrode that also serves as support, 4... Evaporation source, 6... Filament, 8... Grid, 1
4,15.16...power supply, 17...magnet, 21
····backing.

Claims (1)

[Claims] a vacuum chamber into which an active gas or an inert gas or a mixture of these gases is introduced; an evaporation source for evaporating the evaporation substance within the vacuum chamber; and an evaporation source disposed in the vacuum chamber so as to face the evaporation source. a counter electrode that holds the substrate on which the thin film is to be formed; a filament for generating thermionic electrons disposed between the evaporation source and the counter electrode; and a filament disposed between the filament and the counter electrode that passes through the evaporated substance. The grid has a power source means for realizing a predetermined electrical state in the vacuum chamber, a conductive means for electrically connecting the inside of the vacuum chamber and the power source means, and a conductive means in the vicinity of the grid. A thin film forming apparatus characterized in that a magnet is provided, and the magnet generates a magnetic field near a grid surface.