JPH04103762A - Thin film forming device - Google Patents

Abstract

PURPOSE:To form a uniform thin film high in adhesion on a large-area substrate by controlling the amt. and energy of an ion to be injected into the substrate through a grid provided between a thermoelectron emitting filament and a counter electrode. CONSTITUTION:An active gas or an inert gas is introduced into a bell jar 1. A vaporization source 10 is then energized and heated to vaporize a vaporization material. The particles of the vaporized material expand and fly toward a substrate 100 on a counter electrode 14, and a part of the particles are positively ionized by the thermoelectron emitted from a filament 11. The vaporized material is passed through a first grid 12 and highly ionized. The ionized particles are passed through a second grid 13, accelerated, then decelerated by the electric field extending from the counter electrode 14 to the second grid 13, allowed to collide with the substrate 100 and deposited. Accordingly, the amt. and energy of the ion to be injected into the substrate 100 are controlled by adjusting the potential between the counter electrode 14 and the second grid 13.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is characterized by strong reactivity, which is an advantage of the CVD method (chemical vapor deposition method), and high vacuum deposition, which is an advantage of the PVD method (physical vapor deposition method). The present invention relates to a thin film forming apparatus that can simultaneously realize film formation and uniform thin film formation on a large-area substrate.

[Conventional technology]

Conventionally, thin film forming apparatuses that use CVD or PVD methods are well known for forming thin films on substrates on which thin films are to be formed.
A device using the PVD method has the advantage of being able to form a dense and strong thin film in a high vacuum.

Various types of thin film forming apparatuses using CVD methods, PVD methods, etc. have been proposed in the past, and the methods thereof are extremely diverse.

However, with conventional thin film forming apparatuses, the adhesion of the formed film to the substrate on which the thin film is formed (hereinafter referred to as the substrate) is weak, or the thin film cannot be formed on a substrate that does not have heat resistance. There have been problems such as difficulty in forming a uniform thin film on a large-area substrate.

Therefore, in order to solve these problems, the applicant first installed a grid between the evaporation source and a counter electrode that holds the substrate facing the evaporation source as a thin film forming apparatus, and proposed a device in which a filament for generating thermionic electrons is disposed between the grid and a thin film is formed by setting the grid at a positive potential with respect to the filament (Japanese Patent Publication No. 1-53351).
Publication No.).

In this thin film forming apparatus, the evaporated substance evaporated from the evaporation source is first ionized by thermionic electrons from the filament.
When the ionized evaporated substance 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 on the substrate. There is.

[Problem to be solved by the invention]

By the way, in forming a thin film, the effective incident energy of ions is considered to be several eV to several tens of eV. this is,
■Removal of impurities (such as H2C) physically attached to the substrate surface, ■Promotion of surface diffusion of the substance to be deposited on the substrate during film formation, and ■-Does not cause significant damage to the substrate or the surface of the film being formed. This value is estimated from the viewpoints that there is no significant self-sputtering and that the material to be deposited does not have significant self-sputtering.

However, in the thin film forming apparatus described above, it is not always easy to freely adjust the incident energy and amount of ions. In particular, it is difficult to sufficiently inject ions with such low energy (several eV to several tens of eV), and it has not been possible to adequately cope with the formation of thin films that do not like the incidence of high-energy gas ions.

The present invention has been made in view of the above circumstances, and it is possible to form a thin film with extremely strong adhesion to a substrate, and it is also possible to use non-heat resistant plastic or the like as a substrate. It is an object of the present invention to provide a novel thin film forming apparatus that can form a uniform thin film on a large area substrate.

[Means to solve the problem]

In order to achieve the above object, the thin film forming apparatus according to the present invention includes a vacuum chamber into which an active gas, an inert gas, or a mixture of these gases is introduced, and an evaporation source for evaporating an evaporable substance in the vacuum chamber. , a counter electrode arranged to face the evaporation source and holding the substrate, a filament for generating thermionic electrons arranged between the evaporation source and the counter electrode, and between this filament and the counter electrode. A first grid is arranged between the first grid and the counter electrode, and the second grid is arranged between the first grid and the counter electrode, and the second grid is arranged between the first grid and the counter electrode. and conductive means for electrically connecting the power source means and the inside of the vacuum chamber, the first grid being at a positive potential with respect to the filament, and the second grid being at a negative potential with respect to the first grid. By setting the counter electrode to a negative potential with respect to the first grid and a positive potential with respect to the second grid, it is possible to control the amount and energy of ions incident on the substrate.

[For production]

As described above, the thin film forming apparatus of the present invention includes a vacuum chamber,
It has an evaporation source, a counter electrode, a filament, first and second grids, power supply means, and conductive means.

The vacuum chamber is capable of introducing an active gas, an inert gas, or a mixed gas of an active gas and an inert gas into its internal space, and includes an evaporation source, a counter electrode, a filament, a first grid, and a first grid. Two grids are placed within this vacuum chamber.

An evaporation source that evaporates the evaporation substance and a counter electrode that also serves as a substrate support are arranged to face each other.

A filament for thermionic generation is placed between the evaporation source and the counter electrode.

The first grid, through which the vaporized substance passes, is interposed between the filament and the counter electrode, and is brought to a positive potential with respect to the filament by the power supply means.

The second grid allows the vaporized substance to pass therethrough, is interposed between the first grid and the counter electrode, and is brought to a negative potential with respect to the first grid by the power supply means.

The counter electrode is also placed at a negative potential with respect to the first grid and at a positive potential with respect to the second grid.

Therefore, in the thin film forming apparatus of the present invention, an electric field is generated from the first grid toward the filament and the second grid, and stable plasma is generated mainly in this space. Furthermore, by appropriately selecting the potentials of the counter electrode and the second grid, it is possible to control the incident energy and amount of ions incident on the substrate.

Note that these power supply means are 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 conductive means.

〔Example〕

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

The attached figure is a schematic diagram of a thin film forming apparatus showing an embodiment of the present invention.

In the figure, the reference numeral 1 indicates a Pelger, the reference numeral 2 indicates a base plate, and the reference numeral 3 indicates a backing. The Pelger 1 and the base plate 2 are integrated by a backing 3 to form a vacuum chamber. An active gas and/or an inert gas can be introduced by a known appropriate method as shown in FIG. Further, a hole 2A formed in the center of the base plate 2 is connected to a vacuum system (not shown).

The base plate 2 is provided with electrodes 20, 21, 22, 23 and 24 which also serve as supports while maintaining airtightness inside the vacuum chamber and electrical insulation from the base plate 2. , these electrodes 20.21.22°23,
Reference numeral 24 electrically connects the inside of the vacuum chamber and the outer flange, and constitutes conductive means together with other wiring fittings.

Among the above electrodes 20.21.22.23.24, code 20
A resistance heating type evaporation source 10 made of metal such as tungsten, molybdenum, tantalum, etc. and formed into a boat shape is supported between a pair of electrodes shown by . The shape of the evaporation source 10 may be a coil shape or a crucible shape instead of a boat shape. Note that instead of such evaporation source 10, an evaporation source used in a conventional vacuum evaporation method, such as an electron beam evaporation source, can be used as appropriate.

A filament 11 made of tungsten or the like for generating thermionic electrons is supported between a pair of electrodes 21, and the shape of the filament 11 may be a plurality of filaments arranged in parallel or a mesh shape. For example,
It is determined to cover the spread of particles of evaporation material evaporated from the evaporation source 10.

Further, a first grid 12 and a second grid 13 are supported on the electrodes 22 and 23, respectively, and these grids are shaped so that the evaporated substance evaporated from the evaporation source 10 can pass through to the counter electrode 14 side. In this example, it is mesh-like.

Further, the counter electrode 14 is supported at the tip of the electrode 24, and on the surface of the counter electrode 14 facing the evaporation source 10,
The substrate 100 is held using an appropriate support method.

A pair of electrodes 20 supporting the evaporation source 10 are connected to a heating AC power source 30, and one electrode (hereinafter referred to as a common electrode) is grounded in the illustrated example. Note that this power source 30 may be a DC power source instead of an AC power source, and in the case of a DC power source, the positive and negative directions may be either. Also,
The grounding shown in the figure is not necessarily required.

A pair of electrodes 21 supporting the filament 11 are connected to an AC power source 31, and one electrode of the pair is connected to the common electrode. This power source 31, like the power source 30 described above, is an AC,
Either direct current or direct current may be used.

The electrode 22 supporting the first grid 12 is connected to the positive side of a DC voltage power source 32, and the negative side of the power source is connected to a common electrode.

In the illustrated example, the electrode 23 supporting the second grid 13 is connected to the negative electrode side of a DC voltage power source 33, and the positive electrode side of the power source is connected to a common electrode. Note that the power source 33 may be used with its polarity reversed.

Therefore, the first grid 12 has a positive potential with respect to the filament 11 and the second grid 13, and the electric field is applied from the first grid 12 to the filament 11 and the second grid 13.
Head to.

The electrode 24 supporting the counter electrode 14 is connected to the positive side of a DC voltage power source 34, and the negative side of the power source is connected to a common electrode.

Note that, in reality, the above-mentioned electrical connections include switches that constitute part of the conductive means, and the vapor deposition process is executed by operating these switches, but these switches are not shown in the figure. .

Now, in the thin film forming apparatus having the above configuration, a stable plasma state can be created by adjusting the filament heating power source 31, the first grid power source 32, and the second grid power source 33. In addition, the counter electrode power supply 34 and the second grid 13 @ 33 make it possible to adjust the incident energy and amount of ions incident on the substrate 100, making it possible to freely set the film forming conditions suitable for producing a desired thin film. Can be set.

Thin film formation by the thin film forming apparatus having the above configuration will be described below.

First, open the Pelger 1 and insert the substrate 100 for thin film formation.
is held at the counter electrode 14 as shown in the figure, and the evaporated substance is held at the evaporation source 10. Note that the evaporative substance is selected depending on what kind of thin film is to be formed.

Next, the Pel Jar 1 is closed to seal the vacuum chamber, and the inside of the vacuum chamber is evacuated to a vacuum state using a vacuum exhaust system (not shown). A mixed gas of 10 to 10" Pa is introduced at a pressure of 10 to 10" Pa. For example, assume that the introduced gas is an inert gas such as argon (Ar).

Now, the apparatus is operated in this atmospheric state, the evaporation source 10 is heated, and the evaporation substance is evaporated. The particles of the evaporated substance fly while spreading toward the substrate 100,
A part of it and the introduced gas are ionized into positive ions by collision with thermionic electrons emitted from the filament 11.

In this way, the partially ionized vaporized substance passes through the first grid 12, but at this time, it collides with the thermoelectrons vibrating up and down in the vicinity of the first grid 12 and with the ionized introduced gas. , further ionized.

The portion of the evaporated material that has passed through the first grid 12 that has not yet been ionized is further ionized into positive ions by collision with the ionized introduced gas, thereby increasing the ionization rate.

In this way, the evaporated particles ionized into positive ions are accelerated by the action of the electric field from the first grid 12 toward the second grid 13, and pass through the second grid 13. That is,
The second grid 13 acts as an ion extraction electrode.

The ions that have passed through the second grid 13 are decelerated by the action of the electric field from the counter electrode 14 toward the second grid 13 and collide with the substrate 100 . That is, the counter electrode 14 is connected to the substrate 100
It acts as an electrode for adjusting the incident energy of ions colliding with the ions.

Therefore, in the thin film forming apparatus of the present invention, the amount and energy of ions incident on the substrate 100 can be controlled by adjusting the potentials of the counter electrode 14 and the second grid 13, thereby achieving a formation suitable for a desired thin film. Membrane conditions can be set freely. Furthermore, it is also possible to form a film using low-energy ions, which has been considered difficult in the past.

As described above, in the thin film forming apparatus of the present invention, a force in the direction of the electric field acts on the ions, so that the film thickness distribution and physical properties of the thin film are made uniform, and a uniform thin film can be formed on a large-area substrate. Formation can be carried out.

In addition, the incident energy and amount of incident ions can be adjusted, and film formation can be performed using low-energy ions, so the effect of the presence of charge and the effect of kinetic energy can be performed without damaging the substrate. By effectively utilizing this, it is possible to obtain a thin film with excellent adhesion to the substrate and crystallinity.

In addition, the ionization rate of the evaporated substances during film formation is extremely high and stable, so when forming a film by introducing an active gas alone or together with an inert gas,
By combining the evaporated substance with an active gas with good reactivity, a compound thin film having desired physical properties can be easily and reliably obtained.

For example, argon is introduced as an inert gas and oxygen is introduced as an active gas, and the pressure is adjusted to 10 to 10" Pa,
If aluminum is selected as the evaporator, an insulating thin film of aluminum oxide can be formed on the substrate, and if indium or tin is selected as the evaporator, conductive thin films such as indium oxide or tin oxide can be formed, respectively. Moreover, if yttrium, barium, and copper are selected as evaporation substances, a superconducting thin film can be obtained.

Now, in the thin film forming apparatus of the present invention, the thermoelectrons generated by the filament effectively contribute to the ionization of the evaporated substance and the introduced gas, so it is possible to ionize the evaporated substance even under a high vacuum with a pressure of 1F2Pa or less. ,For this reason,
Since the incorporation of excess gas molecules into the thin film can be extremely reduced, a highly pure thin film can be obtained. Furthermore, the structure of the thin film can be made extremely dense, and although the density of a thin film is normally considered to be smaller than that of the bulk, the present invention allows the density of the thin film to be extremely close to that of the bulk. One of the major features is that it can be obtained. That is, the thin film forming apparatus of the present invention is extremely suitable for forming semiconductor thin films that constitute ICs, LSIs, and the like.

〔Effect of the invention〕

As explained above, according to the thin film forming apparatus of the present invention,
Not only thin films made of a single element such as metal thin films on large-area substrates, but also compound thin films have good adhesion.
Because it can be produced in a state closer to stoichiometric thin film and with uniform film thickness and uniform physical properties,
It can also be used for mass production.

Further, according to the thin film forming apparatus of the present invention, since the evaporated substance and the introduced gas are activated, film formation that requires reactivity,
Film formation that requires crystallization can be achieved without applying thermal energy such as temperature (reaction temperature, crystallization temperature), making it possible to grow thin films at low temperatures.

[Brief explanation of the drawing]

The figure is a schematic configuration diagram of a thin film forming apparatus showing an embodiment of the present invention. 1...Pelger, 2...Base plate, 3
...Backing, 4...Gas introduction means, 1o
...Evaporation source, 11...Filament, 12...
...First grid, 13...Second grid, 14.
...Counter electrode, 20.21.22゜23, 24...
Electrode that also serves as support, 30.31...AC power supply, 32
．． 33.34...DC voltage power supply, 100... Board.

Claims (1)

[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 evaporation substance within the vacuum chamber, and a substrate disposed opposite to the evaporation source to hold the substrate. a counter electrode, a filament for thermionic generation disposed between the evaporation source and the counter electrode, a first grid disposed between the filament and the counter electrode and capable of passing the evaporated substance; a second grid disposed between the first grid and the counter electrode and capable of passing the evaporated substance; a power source means for achieving a predetermined electrical state in the vacuum chamber; conductive means for electrically connecting the first grid to the filament, the first grid to a positive potential with respect to the filament, the second grid to a negative potential with respect to the first grid, the counter electrode to a negative potential with respect to the first grid, and A thin film forming apparatus characterized in that the amount and energy of ions incident on the substrate can be controlled by setting the potential to be positive with respect to the second grid.