JPH02258972A - Thin film forming device - Google Patents

Abstract

PURPOSE:To form a thin film with extremely high adhesive strength onto a substrate in the vacuum chamber of a vapor deposition device for thin films by ionizing the vapor of material for vapor deposition by thermoelectron, accelerating the ions by a grid electrified positive and bringing the ions into collision against the substrate. CONSTITUTION:An inert gas, such as Ar, or active gas, such as O2 is filled into a bell-jar 2. The substrate 13 mounted to a counter electrode 12, the grid 10 impressed with a positive voltage, a filament 8 made of W and Mo, a grid- shaped target 6, and an evaporating source 4 consisting of a resistance wire coil are disposed therein. The target 8 is heated by the evaporating source 4 and is thereby partly evaporated; thereafter, the vapor is ionized by the thermoelectron released from the filament 8. The ions are accelerated by the grid 10 impressed with the high voltage which is positive with respect to the target 6 by a DC power source 18. The accelerated ions are passed through the grid 10 and are brought into collision against the substrate 13 with large energy. The thin film consisting of the target material or the compd. of the target material and the active gas, such as O2, is formed with the extremely high adhesive strength onto the substrate 13 impressed with the negative voltage.

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 multi-component thin films such as magnetic alloy thin films, oxide superconductor thin films, and semiconductor thin films.

[Conventional technology]

Conventionally, thin film forming equipment that uses CVD or PVD methods is well known. CVD equipment is highly reactive, while PVD equipment can form dense and strong thin films in high vacuum. It has the advantage of being able to

Various types of thin film forming apparatuses using CVD, PVD, etc. have been proposed in the past.
In either case, there is a problem in that the adhesion between the formed thin film and the substrate is poor.

Therefore, in order to solve this problem, a thin film forming apparatus developed from the above method generates a high-frequency electromagnetic field between the evaporation source and the object to be evaporated to ionize the material evaporated in active or inert gas. There are thin film forming apparatuses that use the so-called ion blating method, which performs vacuum evaporation and deposits evaporated substances on the object to form a thin film, and also applies a DC voltage between the evaporation source and the object to be evaporated. Thin film forming apparatuses using the DC ion blating method are known (for example, Japanese Patent Publications No. 52-29971 and Japanese Patent Publication No. 52-29091).

Also, as a further developed thin film forming device.

A substrate on which a thin film is to be formed is held by a counter electrode facing an evaporation source, a grid is arranged between the counter electrode and the evaporation source, and a filament for generating thermionic electrons is arranged between the grid and the evaporation source. However, an apparatus has been proposed in which a thin film is formed by setting the grid at a positive potential with respect to the filament (Japanese Unexamined Patent Publication No. 59-89763). In this thin film forming apparatus, the evaporated substance evaporated from the evaporation source is first , the ionized evaporated substance is ionized by thermionic electrons from the filament, and as it passes through the grid, it is accelerated by the action of the electric field from the grid to the counter electrode and collides with the substrate on which the thin film is to be formed, resulting in good adhesion. It has the characteristic that a thin film is formed.

[Problem to be solved by the invention]

By the way, in the conventional thin film forming apparatus described above, the adhesion of the formed film to the thin film forming substrate has been improved and is relatively strong. ! Furthermore, there were other problems such as difficulty in forming a film on a substrate with low heat resistance such as plastic.

In addition, conventional thin film forming equipment can be used to form various multi-component thin films such as magnetic alloy thin films, oxide superconductor thin films, and semiconductor thin films, especially ITO films, whose properties change significantly due to doping with trace elements. When forming a thin film with such properties, it is difficult to effectively incorporate these trace elements into the film.

There was a problem in that it was difficult to obtain a thin film with a desired composition ratio.

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 on which a thin film is to be formed, and also to form a thin film on a resinous substrate with low heat resistance. To provide a novel thin film forming apparatus that can be used as a substrate and can also effectively form various multi-component thin films such as magnetic alloy thin films, oxide superconductor thin films, and semiconductor thin films. The purpose is to

(Means for Solving the Problems) In order to achieve the above object, a thin film forming apparatus according to the present invention includes a vacuum chamber into which active gas, inert gas, or a mixture of these gases is introduced, and evaporation in this vacuum chamber. an evaporation source for evaporating a substance; a counter electrode that is placed in the vacuum chamber and holds a substrate on which the evaporation substance is deposited so as to face the evaporation source; and between the evaporation source and the counter electrode. a filament disposed between the grid and the evaporation source to ionize a portion of the evaporated substance;
A grid or flat target placed between the filament and the evaporation source, the potential of the grid being positive with respect to the potential of the filament, and the potential of the target being positive with respect to the potential of the filament. and means for setting a negative potential, and the material of the target is composed of a part of one or more single or compound elements constituting the thin film formed on the substrate.

Further, in the thin film forming apparatus having the above configuration, when the target disposed between the filament and the evaporation source is a flat plate, means for applying a magnetic field parallel to the target surface to the space above the surface of the target. may be provided.

Further, as another means for achieving the above object, instead of or in addition to the means of making the potential of the target negative with respect to the potential of the filament, an active gas is placed on the counter electrode side of the target. Alternatively, an ion source for generating an ion beam for colliding ions of an inert gas or a mixture of both gases may be provided.

[For production]

In the thin film forming apparatus according to the present invention, the grid includes:
It is placed between the evaporation source and the counter electrode, and is placed at a positive potential with respect to the potential of the counter electrode and the filament, so that an electric field from the grid toward the substrate exists in the vacuum chamber. .

An electric field is formed in the opposite direction from the grid toward the evaporation source.

Further, a filament for generating thermionic electrons is arranged between the grid and the evaporation source in the vacuum chamber, and the thermionic electrons generated by the filament are used to ionize a part of the evaporated substance.

Also, part of the evaporated material from the evaporation source is ionized into positive ions by electrons from the filament, and the partially ionized evaporated material passes through the grid,
Further, the ionized gas promotes ionization into positive ions, which are accelerated toward the substrate by the action of the electric field.

Here, the electrons from the filament are emitted from the filament with kinetic energy corresponding to the filament temperature, so they are not immediately attracted to the positive potential grid, but pass through it and are pulled back by the Coulomb force by the grid. Then, it passes through the grid, and so on, repeating the vibrational movement around the grid, and is finally absorbed by the grid. Therefore, the electrons from the filament do not reach the substrate, and the substrate is not subjected to electron bombardment.
This prevents the substrate from being heated and prevents the temperature of the substrate from rising. Therefore, a material with low heat resistance can also be used as the substrate material.

The material of the grid-like or plate-like target is composed of one or more single or compound elements that constitute the thin film formed on the substrate, and this target is placed closer to the evaporation source than the filament. The potential is at a lower potential than the filament potential and the grid potential.

Therefore, the target potential is at a lower potential than the potential between the grid and the filament. Therefore, ions positively ionized by hot electrons flying between the filament and the grid are diffused to the surface of the target by the electric field between the grid and the filament, collide with the surface of the target at high speed, and sputter the surface of the target. The particles constituting the grid-like or plate-like target sputtered by these ions diffuse into the substrate, reach the thin film to be formed, and become part of the thin film constituent material.

Further, in the thin film forming apparatus having the above configuration, when the target disposed between the filament and the evaporation source is flat, it is preferable to provide means for applying a magnetic field parallel to the target surface, and this magnetic field is It is perpendicular to the electric field between the grid and the target, and therefore some of the hot electrons generated from the filament are trapped in the space above the target surface by the action of the magnetic field, effectively ionizing the introduced gas (positively). These high-density ions are diffused to the target surface by the electric field between the grid and the filament, and collide with the target surface at high speed, making it possible to effectively sputter the target surface.

Furthermore, in the thin film forming apparatus having the above configuration, an ion source may be provided on the counter electrode side of the target in place of or in addition to the means for making the potential of the target negative with respect to the potential of the filament; in this case, This ion source is
It is used to collide gas ions of active gas, inert gas, or a mixture of both onto the target surface, and the ion beam is made to collide with the target at high speed with a preset incident angle, average kinetic energy, and density. It acts on Therefore, the target surface can be effectively sputtered.

(Example) Hereinafter, the present invention will be explained in detail based on the illustrated example.

FIG. 1 shows a schematic configuration 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. An active gas, an inert gas, or a mixture of both gases is introduced into the vacuum chamber.

The base plate 1 has an electrode 3°5.7 which also serves as a support.
.
．． 11 and base plate 1 are electrically insulated. In addition, a hole 1a drilled in the center of the base plate 1
is connected to a vacuum exhaust system (not shown).

A pair of support electrodes 3 located at the center of the base plate 1 support a resistance heating type evaporation source 4 formed by winding a metal such as tungsten or molybdenum into a coil between the electrodes. Note that instead of such a resistance heating type evaporation source, an evaporation source used in a conventional vacuum evaporation method, such as a beam type evaporation source, can be used as appropriate.

Now, a grid-like target 6 formed in a lattice shape, a mesh shape, etc. is supported on the support electrode S. In addition, tungsten or the like is used between the pair of electrodes 7 that also serve as supports. A filament 8 for generating thermoelectrons is supported, and the shape of this filament 8 is such that a plurality of filaments are arranged in parallel or in a mesh shape.

It is determined to cover the spread of the substance evaporated from the evaporation source 4. The grid-shaped target 6 is disposed between the evaporation source 4 and the filament 8.

A grid 10 is supported on the support electrode 9, and the grid 10 has a shape that allows the evaporated substance to pass through, and in this example, it has a mesh shape.

A counter electrode 12 is supported on the support electrode 11,
Below that, that is, on the side facing the evaporator [4] is the evaporator g4.
A substrate 13 on which the evaporated material is deposited is held in an appropriate manner. Note that when this state is viewed from the side of the evaporation source 4, the counter electrode 12 is placed behind the substrate 13.

Now, each of the support electrodes 3, 5, 7, 9゜11 is formed of a conductor and also serves as an electrode.
As shown in the figure, there are various t-sources 17.1 between the ends of these supporting electrodes 3, 5, 7°9.
8.19.20 are connected.

First, a pair of support electrodes 3 for the evaporation source 4 are connected to the evaporation voltage M17, and furthermore, in the illustrated example, the support electrode 9 that supports the grid 10 is connected to a DC voltage source. An electrode 11 that also serves as a support for supporting the dielectric stack 2 and the substrate 13 is connected to the negative terminal of the DC voltage power source 18, respectively. Further, a DC type 11i19 is connected to both sides of a pair of support electrodes 7 that support the filament 8. In the case of the example shown in Figure 1, the positive electrode of the DC power supply 19 is grounded.

The negative terminal of the DC power supply 19 may be grounded, and the DC type g
An AC power source may be used in place of 19. The negative electrode of a DC power source 20 is connected to the support electrode 5 that supports the grid-shaped target 6, and the positive electrode of this DC power source 20 is connected to the electrode 5 for supporting the grid-like target 6. It is connected to one end of the DC power supply 19.

Note that the grounding shown in the figure is not necessarily required.

In reality, these electrical connections include various switches, and the operation of these switches.

Although the film forming process is realized, these switches are not shown in the figure and are omitted.

One configuration of the thin film forming apparatus according to the present invention has been described above with reference to FIG. 1, but instead of the configuration shown in FIG. 1, the thin film forming apparatus may be configured as in the embodiment shown in FIG. 2.

Here, the configuration shown in FIG. 2 is an example in which a flat target 16 is used in place of the grid-shaped target 6 of the thin film forming apparatus shown in No. i@, and the other configurations are shown in FIG. 1. It is exactly the same as the device.

However, if a flat target 16 as shown in FIG. 2 is used instead of the grid-like target 6 in FIG. As shown in FIG. 3, the target 16 is disposed at a position laterally shifted from a position directly above the evaporation source 4 so as not to obstruct the evaporation source 4 from reaching the evaporation source 4. In addition, when using the grid-shaped target 6 as shown in FIG. 1, since the grid-shaped target 6 is formed in the shape of a lattice or mesh, it can be placed directly above the evaporation source 4.

Now, an example of the schematic configuration of the thin film forming apparatus according to the present invention has been shown above with reference to FIGS. 1 and 2, and the following.

Thin film formation using these devices will be explained. Incidentally, since the apparatus shown in FIG. 1 and the apparatus shown in FIG. 2 are different only in the grid-shaped target 6 and the flat plate-shaped target 16, the explanation will be provided so as to be applicable to the re-apparatus.

In FIG. 1 (or FIG. 2), after the substrate 13 is set on the counter electrode 12 as shown, the evaporation substance is transferred to the evaporation source 4.
hold it.

Here, the combination of the evaporated substance, the base material constituting the grid-like target 6 (or the flat target 16), and the gas species introduced into the vacuum chamber is determined depending on what kind of thin film is to be formed. It will be done.

For example, when forming an Fe-Ni alloy magnetic material, iron (Fe) is used as the evaporation substance and the grid-like target 6 (
Alternatively, nickel (Ni) can be selected as the base material of the flat target 16) and argon (Ar) can be selected as the introduced gas. Of course, Fe may be selected as the base material of the grid-shaped target 6 (or flat target 16) and Ni may be selected as the evaporation substance.

In addition, when forming a Y-Ba-Cu-0 oxide superconducting thin film, yttrium (Y) oxide cyzoa) and barium (Ba) are used as evaporation substances, and a grid-shaped target 6 (or flat target 16) is used. Copper (Cu) can be used as the base material, and oxygen (0) or a mixed gas of oxygen and an inert gas can be selected as the introduced gas.

Furthermore, when forming an indium oxide-based ITO thin film, indium (In) is used as the evaporation substance, and 1! is used as the base material of the grid-shaped target 6 (or flat target 16). (Sn), oxygen can be selected as the introduced gas.

Now, the inside of the vacuum chamber is set to a pressure of 101 to 10 torr in advance, and if necessary, an active gas, an inert gas, or a mixed gas thereof is added to the pressure of 10 to 10 torr.
It is introduced at a pressure of torr. Here, for the sake of concreteness of explanation, it is assumed that the introduced gas is an inert gas such as argon (Ar).

In this state, when the power source is activated, the evaporation source 4 is heated by the alternating current, a positive potential is applied to the grid 10, and a current is passed through the filament 8. The filament 8 is then heated by resistance heating and emits thermoelectrons.

Argon molecules in the vacuum chamber collide with thermionic electrons emitted from the filament 8, and their outer shell electrons are ejected and ionized into positive ions.

These ions reach the surface of the grid-like target 6 (or flat target 16) due to the electric field between the grid 10 and the filament 8. On the other hand, since a negative potential is applied to the grid-like target 6 (or the flat target 16), high-speed ions collide with the surface of the grid-like target 6 (or the flat target 16), and the grid-like target 6 (or the base material of the flat target 16) is sputtered. The particles thus sputtered and emitted fly toward the substrate 13 in the same way as the evaporation material evaporated by the resistance heating of the evaporation source 4.

The grid-like target 6 (or flat target 1
6) The particles emitted from the filament 8 spread and fly toward the substrate 13, but some of them and the introduced gas have outer shell electrons repelled by collision with thermionic electrons emitted from the filament 8. and ionized into positive ions.

In this way, the partially ionized evaporated material and sputtered particles pass through the grid 10;
Ionization is further promoted by the collision of the thermionic electrons vibrating up and down in the vicinity of 0 and the ionized introduced gas. The unionized portions of the evaporated substances and sputtered particles that have passed through the grid 10 are further ionized into positive ions by collision with the ionized introduced gas between the grid IO and the substrate 13. Ionization rate is increased.

In this way, the evaporated substance and sputtered particles ionized into positive ions are accelerated toward the substrate 13 by the action of the electric field from the grid 10 toward the counter electrode 12, and
It collides with 3 with high energy and sticks to it. As a result, a dense thin film with very good adhesion is formed on the substrate.

Incidentally, the majority of the thermoelectrons emitted from the filament 8 are eventually absorbed by the grid 10, and some of the thermoelectrons pass through the grid 10, but the grid 10 and the substrate 13
Since an electric field from the DC power supply 18 acts between the grid 10 and the substrate 13, the thermoelectrons passing through the grid 10 are decelerated by the electric field between the grid 10 and the substrate 13, and are pulled back toward the grid 10.

Therefore, even if some of the thermoelectrons reach the substrate 13, the thermoelectrons will not heat the substrate 13 because they are decelerated by the action of the electric field.

Therefore, in the thin film forming apparatus according to the present invention, even a substrate with weak heat resistance can be used as the substrate 13.

In addition, in the thin film forming apparatus according to the present invention, since the ionization of the evaporated substances is extremely high, by introducing an active gas alone or together with an inert gas into the vacuum chamber to form a film, it is possible to combine the evaporated substances and the active gas. Even when a compound thin film is formed by combining with a gas, a thin film having desired physical properties can be easily obtained.

Furthermore, since thermoelectrons generated by the filament effectively contribute to the ionization of the gas in the vacuum chamber, it is possible to ionize the evaporated substance even under a high vacuum with a pressure of 10-' Torr or less. It is also possible to make the thin film extremely dense, and although the density of a thin film is usually considered to be smaller than that of the bulk, the device of the present invention can obtain a density that is extremely close to that of the bulk. This is also one of its major features.

Furthermore, by forming the film under such a high degree of vacuum, the incorporation of gas molecules into the thin film can be extremely reduced, making it possible to obtain a highly pure thin film. Therefore, the thin film forming apparatus according to the present invention is suitable for forming magnetic alloy thin films and multi-component thin films, and is particularly suitable for forming semiconductor thin films such as ITO whose characteristics change depending on the presence of trace elements.

In the thin film forming apparatus of the present invention shown in FIGS. 1 and 2, for example, if a high-frequency electrode capable of generating a high-frequency electromagnetic field is installed between the grid electrode 0 and the counter electrode 12, the ionization can be effected in this manner. Further promoted by high frequency electromagnetic field,
The various effects mentioned above are increased and are more effective.

Furthermore, when a flat target 16 shown in FIG. 2 is used as a target, if a means for applying a magnetic field parallel to the surface of the target 16 is provided in the space above the surface of the target 16, gas ions can be used to generate the target. Sputtering can be performed more effectively.

More specifically, as shown in FIG. 4, a pair of permanent magnets 24 are installed at the bottom of a flat target 16 to constitute a flat magnetron, and a magnetron parallel to the target surface is placed in the space above the surface of the target 16. A magnetic field H is created. Note that an electromagnet may be used instead of a permanent magnet, and a coaxial magnetron may be used instead of a flat magnetron. Also, the magnet 24 is electrically insulated from the target 16, and the magnet 24 is electrically insulated from the target 16, so that the In order to avoid temperature rise, it is recommended to install a shield plate and water cooling means (not shown).

Now, as shown in FIG. 4, if a flat magnetron is placed below the target 16 and a magnetic field H parallel to the target surface is formed in the space above the surface of the target 16, this magnetic field H will be Since the electric field between the grid and the filament 8 is approximately perpendicular to the electric field, a part of the thermoelectrons that reach the space above the target 16 due to the electric field between the grid and the filament are trapped in this space, and a part of the introduced gas is effectively trapped. ionize (positively). Therefore, high-density gas ions exist in the space above the target 16, and these gas ions reach the surface of the target 16 due to the electric field between the grid and the filament.

On the other hand, since a negative potential is applied to the target 16,
High-speed gas ions accelerated by the electric field between the filament and the target collide with the surface of the target 16, and the base material of the target 16 can be effectively sputtered.

Next, FIG. 5 shows another embodiment of the thin film forming apparatus according to the present invention.

The basic configuration of the thin film forming apparatus shown in FIG. 5 is substantially the same as that of the thin film forming apparatus shown in FIG. 2, and the same members are denoted by the same reference numerals.

Here, the difference between the thin film forming apparatus shown in FIG. 5 and the thin film forming apparatus shown in FIG. 2 is that the electric potential M2 shown in FIG.
0, as shown in FIG. 5, ions 'g14 are provided closer to the counter electrode 12 than the target 16. This is for effectively colliding gas or a mixture of both gas ions onto the target 16 surface.

As the ion source 14, a cold cathode type such as a magnetron type or ECR, or a hot cathode type such as a Kauffman type is selected in consideration of compatibility with the vapor deposition substance and atmospheric gas.

Now, since the ion beam from this ion source 14 collides with the target 16 at high speed with a preset angle of incidence, average kinetic energy, and density, the base material of the target 16 can be effectively sputtered.

In addition to the configuration shown in FIG. 5, a DC power supply that biases the potential of the target 16 negatively may be provided.

The ion beam can be accelerated, and the sputtering yield can be further improved.

〔Effect of the invention〕

As described above based on the illustrated embodiment.

According to the present invention, strong reactivity, which is an advantage of the CVD method,
It is possible to provide a thin film forming apparatus that can simultaneously realize film formation in a high vacuum (formation of a dense and strong thin film), which is an advantage of the PVD method.

In addition, in the thin film forming apparatus according to the present invention, the evaporated substance is ionized and has high electrical energy (electron/ion temperature), so film formation that requires reactivity or crystallization is not possible. Since this can be achieved without applying thermal energy such as temperature (reaction temperature, crystallization temperature), it is possible to form a film at low temperatures, and therefore plastics and the like with low heat resistance can be used as substrate materials.

Further, in a thin film forming apparatus according to the present invention.

Since a grid-like or flat-like target is disposed between the evaporation source and the filament and the base material is a part of the thin film constituent elements, Fe-Ni magnetic alloy film, Y-
Multi-component thin films such as B a-Cu-0 based oxide superconducting thin films can be effectively formed.

In particular, we can effectively dope trace elements into thin films, such as tin doping into indium oxide semiconductor films (IT○) and aluminum doping into zinc oxide films, which greatly affect the properties of thin films. be able to.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a thin film forming apparatus showing one embodiment of the present invention, FIG. 2 is a schematic diagram of a thin film forming apparatus showing another embodiment of the present invention, and FIG. 3 is shown in FIG. FIG. 4 is a schematic plan view showing an example of the arrangement position of a flat target of a thin film forming apparatus; FIG. 4 shows another embodiment of the present invention; figure,
FIG. 5 is a schematic diagram of a thin film forming apparatus showing still another embodiment of the present invention. 1...Base plate, 2...Pelger, 3
゜5.7, 9, 11...Support electrode, 4...
・Evaporation source, 6... Grid-like target, 8...
・Filament, 10...First grid, 12...
... counter electrode, 13 ... substrate, 14 ... ion source, 16 ... flat target, 17 ... AC power supply, 18.19.20 ... DC power supply, 21...
...Backing, 24...Magnet, H...Magnetic field. 7 ruσ v)4

Claims (1)

[Claims] 1. 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 evaporated substance in the vacuum chamber, and an evaporation source disposed within the vacuum chamber. a counter electrode that holds the substrate on which the evaporation substance is deposited so as to face the evaporation source; a grid that is disposed between the evaporation source and the counter electrode and allows the evaporation substance to pass through; a filament disposed between the evaporation source and for ionizing a part of the evaporation substance; a grid-shaped or flat target disposed between the filament and the evaporation source; and a potential of the grid. and means for setting the potential of the target to be a negative potential with respect to the potential of the filament, and the material of the target is a thin film formed on the substrate. A thin film forming apparatus characterized in that it is composed of a part of one or more single or compound elements. 2. In the thin film forming apparatus according to claim 1, when the target disposed between the filament and the evaporation source is flat, means for applying a magnetic field parallel to the target surface in the space above the target surface. A thin film forming apparatus characterized by being provided with. 3. In the thin film forming apparatus according to claim 1, in place of or in addition to the means for making the potential of the target negative with respect to the potential of the filament, an active gas or an inert gas is placed on the counter electrode side of the target. 1. A thin film forming apparatus comprising an ion source for generating an ion beam for colliding ions of an active gas or a mixture of both.