JPH0222465A - Thin film forming device - Google Patents

Abstract

PURPOSE:To excellently form an electrically insulated thin film on a base plate by charging positive potential in a grid against a filament and impressing AC potential to an electrode for holding the base plate in a vacuum vessel. CONSTITUTION:DC power sources 22, 21 are connected with a filament 7 and a grid 6 in a vacuum vessel and the grid 6 is charged with positive potential against the filament 7. Further AC power sources 23, 20 are connected with a counter electrode 5 and an evaporation source 8. In this constitution, active gas and/or inert gas are introduced into the vacuum vessel and evaporation substance held in the evaporation source 8 is evaporated. The particles of the evaporation substance are flown toward a base plate 100 and ionized into positive ions by the thermions of the filament 7 and passed through the grid 6 and a thin film is formed on the base plate 100. At this time, when the thin film is electrically insulated, the surface of this thin film is made a state charged to positive by the positive ions but this positive charge is destaticized by the electrons which are accelerated following the positive ions and reach the base plate side. Thereby excess charge is prevented from being built-up on the thin film and the excellent insulating thin film is formed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a thin film deposition apparatus.

[Conventional technology] to a counter electrode placed opposite the evaporation source.

A substrate on which a thin film is to be deposited is held, a filament and a grid are arranged between the evaporation source and the substrate from the evaporation source side to the substrate side, and the potential of the grid is set to both the counter electrode and the filament. An apparatus for forming a film at a positive potential is known (Japanese Patent Application Laid-Open No. 59-89783).

In this device, the evaporated substance evaporated from the evaporation source is first ionized by thermionic electrons from the filament, and when it passes through the grid, it is accelerated toward the substrate by the electrode moving from the grid to the counter electrode, collides with the substrate at high speed, and A thin film with good adhesion is formed on top.

[Problems to be Solved by the Invention] The above-mentioned thin film forming apparatus has no problems when the thin film formed on the substrate is conductive, but when trying to form an electrically insulating thin film, the following problems occur. occurs.

That is, when the film is formed as described above, the insulating film formed at the initial stage of film formation covers the substrate surface and the counter electrode surface. In such a state, the surface of the formed film becomes electrically insulated. Since the evaporated substances fly as cations and are deposited on this surface, the surface of the coating becomes positively charged with the deposition, and this obstructs the flying of the cations of the evaporated substances, thereby significantly slowing down the film formation rate. Also,
In some cases, the charged potential of the formed film may exceed the dielectric strength voltage of the thin film, and the formed thin film may be damaged due to dielectric breakdown.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a novel thin film deposition apparatus that can reliably deposit even insulating thin films.

[Means to solve the problem] The present invention will be explained below.

The thin film deposition Jdf of the present invention includes a vacuum chamber, an evaporation source, a counter electrode, a filament, a grid, a power supply means, and a conductive means.

The vacuum chamber is designed to have active gas, inert gas, or a mixture of active gas and inert gas introduced into it, and the evaporation source, counter electrode, filament, and grid are placed inside this vacuum chamber. Deployed.

The evaporation source is for evaporating the evaporation substance in this vacuum chamber, and any conventionally known evaporation source for vacuum evaporation methods, such as a resistance heating type or a beam heating type, can be used as appropriate.

A counter electrode is disposed in the vacuum chamber so as to face the evaporation source, and holds a substrate on which a thin film is to be formed.

a filament is disposed between the evaporation source and the counter electrode;
It is used to generate thermoelectrons.

The grid is disposed between the filament and the counter electrode and is structured to allow passage of the evaporated material, ie, evaporated material particles evaporated from the evaporation source.

The power supply means is a means for realizing a predetermined electrical state within the vacuum chamber, and the power supply means and the inside of the vacuum chamber are electrically connected by a conductive means.

The power source means is configured to cause the grid to have a positive potential with respect to the filament, and to apply an alternating current potential to the counter electrode.

[Function] In the thin film deposition apparatus of the present invention, an alternating current potential is applied to the counter electrode by the power supply means. Thus, the counter electrode alternately attracts ions and electrons of the vaporized substance.

Therefore, when forming an electrically insulating thin film on a substrate, positive ions and electrons effectively eliminate static electricity from each other.

[Examples] Hereinafter, specific examples will be described with reference to the drawings.

In the diagram showing one embodiment of the present invention, a Pelger 1, a base play 1-2, and a backing 3 that integrates these are shown.
constitutes a vacuum chamber.

An active gas and/or an inert gas can be introduced into the thus constructed vacuum chamber by a known appropriate gas introduction means 4.

A hole 2A bored in the center of the base plate 2 is connected to a vacuum system (not shown).

Electrodes 9.10 and 11.12, which also serve as supports, are disposed on the base plate 2 while maintaining airtightness inside the vacuum chamber and electrical insulation from the base plate 2.

These electrodes 9, 10, 11, and 12 electrically connect the inside and outside of the vacuum chamber, and together with other wiring devices constitute conductive means.

A resistance heating type evaporation source 8 made of metal such as tungsten or molybdenum and formed into a boat shape is supported between the pair of electrodes 11 . Of course, a coil-shaped one may be used instead of a boat-shaped one.

Further, between the pair of electrodes 10, a filament 7 made of tungsten or the like for generating thermoelectrons is supported. The shape of the filament 7 is determined so as to cover the spread of particles of the evaporated substance evaporated from the evaporation source 8 by arranging a plurality of filament materials in parallel or forming a mesh. .

A grid 6 is supported on the electrode 12 . grid 6
The shape is determined so that the evaporated substance can pass to the counter electrode 5 side, and in this example, it has a mesh shape.

A counter electrode 5 is supported by the tip of the electrode 9, and a substrate 100 on which a thin film is to be formed is held by the counter electrode 5 so as to face the evaporation source 8. The method of retention is appropriate.

Now, in this embodiment, the power source means is an AC power source 20.
23 and DC power supplies 21 and 22.

The AC power supply 20 is for heating the evaporation source 8 and is connected to the power supply 6ml. This AC power source 20 may be replaced with a DC power source, and in that case, either positive or negative direction may be used.

A DC power supply 22 connected to the electrode 10 is a power supply for heating the filament 7 and generating thermoelectrons. Also,
The DC type g21 is a power source for applying a constant potential to the grid 6, and its positive side is connected to the electrode 12, and its negative side is connected to one side of the electrode 11. Therefore, the grid 6 has a positive potential with respect to the filament 7, and the electric field between the grid 6 and the filament 7 is directed from the grid 6 to the filament 7. In this embodiment, one side of the power supply 21 is directly grounded, but during this period Turn on the power and turn on the evaporation source 8 and/or
Alternatively, the filament 7 may be biased, and
The ground shown in the figure is not necessarily required.

Note that an AC power source may be used instead of the DC power source 22 for heating the filament 7. In that case,
The effective value may be smaller than the grid voltage. Setting the grid at a positive potential with respect to the filament includes such a case.

An AC power source 23 is connected to the electrode 9 and applies an AC potential to the counter electrode 5.

Furthermore, in reality, the above-mentioned electrical connection includes a switch that constitutes a part of the conductive means, and the film forming process is executed by operating the stiff switch.

These switches are omitted from illustration.

Now, the thin film is formed by the apparatus of the embodiment as follows.

The substrate 100 is held on the counter electrode 5 as shown in the figure, and the evaporation source 8
is allowed to retain evaporated substances. The material to be evaporated will, of course, be determined depending on what kind of film is to be formed. In the vacuum chamber, an active gas such as oxygen, an inert gas, or a mixture of both gases is introduced into the vacuum chamber by the gas introducing means 4 at a concentration of 10 to 1 O.
It is introduced at a pressure of -3 Pa.

In this state, when the held evaporation material is evaporated from the evaporation source 8, the evaporation material particles generated by the evaporation fly toward the substrate 100 while spreading.

On the other hand, thermionic electrons are emitted from the filament 7. These thermionic electrons fly toward the grid 6 while being accelerated by the electric field between the grid 6 and the filament 7, and when they collide with evaporated material particles and introduced gas molecules on the way, they are ionized into positive ions. do. In this way, a plasma state is formed in the space near the grid 6.

The counter electrode 5 periodically takes on positive and negative potentials due to the alternating current g23, and when the potential is negative with respect to the grid 6, the electric field moves from the grid 6 to the counter electrode 5, and when the potential is positive with respect to the grid 6, the electric field is directed to the counter electrode 5. , the electric field is directed from the counter electrode 5 towards the grid.

1 when the potential of the counter electrode 5 is negative with respect to the grid 6
The electric field between the two accelerates positive ions toward the substrate 100, and when the potential of the counter electrode 5 is positive with respect to the grid 6, the electric field between the two accelerates electrons toward the substrate 100.

When the positive ions are accelerated toward the substrate 100, these positive ions collide with the substrate 100 to form a desired thin film on the substrate 100. At this time, if the thin film is electrically insulating, the surface of the thin film will be positively charged by the cations, but this positive charge will be eliminated by the electrons that are accelerated following the cations and reach the substrate side. .

In the end, positive ions and electrons alternately arrive at the substrate 100 and eliminate each other's charges, so that no excessive charge is deposited on the thin film that is being formed, and no dielectric breakdown of the film occurs. A thin film will be formed well.

The frequency of the AC power supply 23 is commercial 50Hz or 60t.
+z is fine, but 1 to several hundred KHz or even 13.56M
It is effective to apply a high frequency voltage of Hz.

The thin film thus formed is formed by ion bombardment with the substrate, and therefore has excellent adhesion to the substrate 100 and good crystallinity and crystal orientation.

Furthermore, when film formation is performed by introducing an active gas alone or together with an inert gas as the introduced gas, the evaporated substance is combined with the active gas, and a compound thin film can be formed by this combination.

For example, if argon is introduced as an inert gas and oxygen is introduced as an active gas, the pressure is adjusted to 10 to 10-'Pa, and aluminum is selected as the evaporation material, an insulating thin film of aluminum oxide can be formed on the substrate. . Also, if silicon or -silicon oxide is selected as the evaporation material instead of aluminum, an insulating thin film of silicon dioxide can be obtained, and if indium or tin is selected as the evaporation material, a conductive film such as indium oxide or tin oxide can be obtained. A thin film can also be formed. Further, by using nitrogen or ammonia together with argon as the active gas and selecting titanium or tantalum as the evaporator, a thin film of titanium nitride or tantalum nitride can be obtained.

[Young fruit of the invention] As described above, according to the present invention, a novel thin film deposition apparatus can be provided. Since this apparatus is configured as described above, it is possible to form not only a conductive thin film but also an electrically insulating thin film with good adhesion and in a state closer to stoichiometric thin film. Also, in the device of the present invention.

Since the ionization rate of the evaporated substance is extremely high and stable, a compound thin film having desired physical properties can be easily and reliably obtained.

Furthermore, for the ionization of evaporated substances and introduced gases.

Since thermionic electrons from the filament contribute effectively, 1O-
It is possible to ionize the evaporated substance even under a high vacuum of 3 Pa or less, and therefore the incorporation of gas molecules into the thin film can be extremely reduced, making it possible to obtain a highly pure thin film. Also,
The structure of the thin film can also be made extremely dense, and it is possible to obtain a thin film with a density extremely close to the bulk density.

Therefore, the thin film deposition apparatus of the present invention is suitable for manufacturing semiconductor thin films and the like that constitute ICs, L units, and the like.

[Brief explanation of the drawing]

The figure shows one embodiment of the present invention.

Claims (1)

[Scope of Claims] A vacuum chamber into which an active gas, an inert gas, or a mixture of these gases is introduced; an evaporation source for evaporating an evaporable substance in the vacuum chamber; a counter electrode arranged to face the evaporation source and holding a substrate on which a thin film is to be formed; a filament for generating thermionic electrons arranged between the evaporation source and the counter electrode; a grid disposed between the filament and the counter electrode and capable of passing the evaporated substance; a power supply means for achieving a predetermined electrical state in the vacuum chamber; conductive means connected to the filament, and the power supply means is configured so that the grid has a positive potential with respect to the filament and an alternating current potential is applied to the counter electrode. , thin film deposition equipment.