JPH04154962A - Thin film forming device - Google Patents

Abstract

PURPOSE:To allow the use of a substrate having small heat resistance and the formation of a compd. thin film by allowing the introduction of gases into the grid of the device having the grid and filament between an evaporating source and the counter electrode for holding the substrate. CONSTITUTION:The counter electrode 5 for holding the substrate facing the evaporating source 8 is disposed in a vacuum chamber 1' into which the active or inert gas is introduced. The filament 7 for generating thermions is disposed between the counter electrode 5 and the evaporating source 8 and the grid 6 allowing the passage of evaporated matter is disposed between this filament and the counter electrode 5. Power source means 20 to 22 for attaining the prescribed electric state in the vacuum chamber and the inside of the vacuum chamber are electrically connected by electrodes 9 to 12 in common use as supports. The grid 6 is maintained at the positive potential with the filament 7 and is made into, for example, a two-layered mesh structure. The stagnation and pool of the introduced gases are formed by a pipe 4 between the same. The gaseous molecule density in the vicinity of the grid 7 is increased in this way and such increased density contributes effectively to reaction.

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 also easily form compound thin films.

[Conventional technology]

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

A variety of thin film forming apparatuses have been proposed using CVD, PVD, etc., and the methods are extremely diverse. There have been problems such as being weak or difficult to form a thin film on a substrate with no heat resistance, or difficult to obtain a thin film of any compound.

Therefore, in order to solve these problems, we developed a thin film forming apparatus that developed the above method by generating a high-frequency electromagnetic field between the evaporation source and the target material 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 target object to form a thin film, and also applies a DC voltage between the evaporation source and the target object. There are well-known thin film forming apparatuses using the DC ion blating method (for example, Japanese Patent Publication No. 52-29971, Japanese Patent Publication No. 52-29971,
2-29091).

In addition, as a further developed thin film forming apparatus, the present applicant first holds a substrate on which a thin film is to be formed on a counter electrode facing an evaporation source, and arranges a grid 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 Application 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 vaporized substance.

By passing 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 thin film with good adhesion.

[Problem to be solved by the invention]

By the way, with the above-mentioned conventional thin film forming apparatus, it is possible to form a compound thin film of the evaporated substance and the gas introduced into the vacuum chamber, but the gas molecules introduced into the vacuum chamber diffuse and Since the reaction spreads over the entire area, there is a problem in that it is difficult to say that the introduced gas molecules contribute effectively to the reaction with a high probability.

In addition, in the conventional thin film forming apparatus described above, when forming an insulating thin film, the insulating thin film covers the counter electrode and the inside of the vacuum chamber, causing arc discharge due to the electric field directed from the grid toward the counter electrode and the inside of the vacuum chamber. In some cases, the plasma was unstable and a good thin film could not be obtained.

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, it is possible to use non-heat resistant plastics, etc. as a substrate, and it is also possible to form a thin film with extremely strong adhesion to a substrate. It is an object of the present invention to provide a novel thin film forming apparatus that facilitates thin film formation.

[Means to solve the problem]

In order to achieve the above object, the thin film forming apparatus according to claim 1 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 an evaporation substance is evaporated in the vacuum chamber. an evaporation source for evaporation, a counter electrode disposed to face the evaporation source in the vacuum chamber and holding the thin film forming substrate, and a thermoelectron generator disposed 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 source means for achieving a predetermined electrical state in the vacuum chamber; The present invention is characterized in that it has a conductive means that electrically connects the filament with a conductive means, the electric potential of the grid is set to be a positive electric potential with respect to the filament, and gas can be introduced into the grid.

The thin film forming apparatus according to claim 2 of the present invention further 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 evaporation substance in the vacuum chamber. a counter electrode that is arranged to face the evaporation source in the vacuum chamber and holds the thin film forming substrate; a filament for generating thermionic electrons that is disposed 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 realizing a predetermined electrical state in the vacuum chamber, and an electrical connection between the inside of the vacuum chamber and the power supply means. The filament has a conductive means connected to the vacuum chamber and the grid so that the electric potential of the filament is negative with respect to the vacuum chamber and the grid, and gas can be introduced into the grid.

[For production]

In the thin film forming apparatus according to the present invention, the vacuum chamber is configured such that an active gas, an inert gas, or a mixed gas of an active gas and an inert gas can be introduced into the internal space of the vacuum chamber, and an evaporation source and a Electrodes, filaments, and grids are placed in a vacuum chamber.

The counter electrode and the evaporation source are arranged to face each other, and the counter electrode is configured to hold the thin film forming substrate on the side facing the evaporation source.

The grid allows the evaporated substances to pass through,
It is interposed between the evaporation source and the counter electrode, and is brought to a positive potential with respect to the filament by power supply means.

In addition, when the grid and the vacuum chamber are made to have the same potential, the electric potential of the filament becomes a negative electric potential with respect to the vacuum chamber and the grid.

Therefore, when forming a thin film, the electric field generated is directed from the grid (and vacuum chamber) to the filament.

In addition, there is an inlet gas outlet on the grid or near the grid, which increases the density of gas molecules in the vicinity, and its shape is a multilayer structure such as a mesh, etc.
During this time, gas is effectively introduced to form a gas reservoir.

The filament is for thermionic generation and is placed between the evaporation source and the grid.

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.

〔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 invention.

In FIG. 1, reference numeral 2 indicates a base plate, reference numeral 3 indicates a backing, and reference number 1 indicates a Pelger. Pelger 1 and base plate 2 are integrated by a backing 3 to constitute a vacuum chamber 1''. 'In the internal space of ', by a known appropriate method as shown by the symbol 4,
It is possible to introduce active gas and/or inert gas. Further, a hole 2A bored in the center of the base plate 2 is connected to a vacuum system (not shown).

The base plate 2 is provided with electrodes 9, 10° 11, 12 which also serve as supports while maintaining airtightness inside the vacuum chamber 1' 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 1', and together with other wiring fittings constitute a conductive means.

Among the electrodes 9, 10, 11, 12, a resistance heating type evaporation source 8 made of metal such as tungsten, molybdenum, tantalum, etc. formed into a boat shape is supported between a pair of electrodes indicated by reference numeral 11. There is. The shape of the evaporation source 8 may be a coil shape or a crucible shape instead of a boat shape. still,
Instead of such evaporation source 8, an evaporation source used in a conventional vacuum evaporation method, such as an electron beam evaporation source, can be used as appropriate.

A filament 7 made of tungsten or the like for generating thermionic electrons is supported between a pair of electrodes denoted by 10.
The shape of the filament 7 is determined so as to cover the spread of the evaporated substance evaporated from the evaporation source 8 by arranging a plurality of filaments in parallel or forming a mesh shape.

A grid 6 is supported on the electrode 12, and this grid 6 has a shape that allows the evaporated substance to pass through to the counter electrode 5, and in this example, it has a two-layer mesh structure. A gas introduction pipe 4A or the like is connected between the two layers, making it possible to introduce gas into the grid section.

Note that the electrode 12 and the pipe 4A are electrically insulated by an appropriate method.

A counter electrode 5 is supported at the tip of the electrode 9, and a thin film forming substrate 10 is supported on the surface of the counter electrode 5 facing the evaporation source 8.
0 is held by an appropriate support method.

Further, although the electrode 9 is directly grounded in the figure, a DC power source may be applied during this period to apply a bias to the counter electrode 5.

The electrode 11 supporting the evaporation source 8 is connected to an AC power source 20 for heating.
It is connected to the. The power source may be a DC power source instead of an AC power source, and in the case of a DC power source, either positive or negative direction may be used.

The electrode lO supporting the filament 7 is connected to a power source 22, which, like the power source 20 described above, is powered by an alternating current,
Either direct current or direct current may be used.

The electrode 12 is connected to the positive side of the DC piezoelectric @21, and the negative side of the same power source is connected to one side of the electrode 10 in the illustrated example. Therefore, the grid 6 is at a positive potential with respect to the filament 7, and between the grid 6 and the filament 7, the electric field is directed from the grid 6 to the filament 7. Further, although the grid 6 has a two-layer mesh structure in the example shown in FIG. 1, it may have another structure as long as the evaporated substance can pass therethrough and gas can stagnate or collect therebetween.

Here, one side of the power supply 21 in the illustrated example is grounded as it is, but during this time, the DC power is turned on and the evaporation source 8
, and/or the filament 7 may be biased. Note that the grounding shown in the figure is not necessarily required.

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 22 and the grid DC power source 21. In addition, the thermoelectrons generated by the filament are used to ionize some of the introduced gas and evaporated substances, but they are attracted by the electric field from the grid and are eventually absorbed by the grid, so they do not reach the substrate. There is no heating due to electron impact on the substrate. In addition, at this time, the density of gas molecules is high near the grid, so ionization is further promoted.
During reactive film formation, the reaction becomes easier, and when an inert gas is introduced, the ionization of gas molecules progresses, and as a result, the ionization of the evaporated substance also progresses.

Next, FIG. 2 is a schematic diagram of a thin film forming apparatus showing an embodiment of the invention as claimed in claim 2.

The apparatus shown in FIG. 2 includes a vacuum chamber 1' and a grid 6.
In contrast, the device is characterized in that the potential of the filament 7 is set to a negative potential, but the other configuration is exactly the same as the device shown in FIG.

That is, in the device shown in FIG. 2, one side of the electrode 10 is connected to the negative electrode side of a DC voltage power source 21, and the positive electrode side of the same power source is connected to the electrode 12 and the electrode 13 in the illustrated example.

Therefore, the filament 7 is connected to the grid 6 and the vacuum chamber 1'
The electric field is negative between the grid 6 and the vacuum chamber 1'' and the filament 7.
' to filament 7.

Here, one side of the power supply 21 in the illustrated example is grounded as it is, but during this time, the DC power is turned on and the evaporation source 8
You can apply a bias to Note that the grounding shown in the figure is not necessarily required.

Now, in the thin film forming apparatus having the configuration shown in FIG. 2, a stable plasma state can be created by adjusting the filament heating power source 22 and the grid DC power source 21. Also,
Since hot electrons from the filament 7 contribute to ionization, a stable plasma state can be maintained and reproduced, and a high-quality thin film can be stably supplied.

In addition, in the case of the configuration shown in FIG. 2, since the potential of the filament 7 is set to be negative with respect to the vacuum chamber 1' and the grid 6, ions may collide with the inner wall of the vacuum chamber 1', etc. Since the sputtering phenomenon that occurs is almost eliminated, a thin film of higher purity can be obtained, and in particular, it can be easily adapted to large-area and mass production of insulating thin films.

In the apparatus shown in FIG. 1 and Part 2, the electrical connections mentioned above actually include switches that constitute a part of the conductive means, and the vapor deposition process is executed by operating these switches. , these switches are omitted from illustration.

Next, thin film formation using the thin film forming apparatus having the configuration shown in FIG. 1 will be described.

In FIG. 1, first, the Pel jar 1 is opened, and the thin film forming substrate 100 is held on the counter electrode 5 as shown, and the evaporation substance is held on the evaporation source 8.

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 1', and after evacuating the inside of the vacuum chamber 1' to a vacuum state using a vacuum exhaust system (not shown), an active gas or an inert gas is added to the vacuum chamber 1''. Active gas or mixed gas of 10 to 1O-3P
Introduce at a pressure of a. In the present description, this introduced gas is assumed to be an inert gas such as argon.

Now, when the apparatus is operated in the above atmospheric condition and the evaporation source 8 is heated, the evaporation substance evaporates.

The evaporated material, that is, the particles of the evaporated material, spread and fly toward the thin film forming substrate 100, but some of them and the introduced gas are converted into positive ions by collision with thermionic electrons emitted from the filament 7. Ionized.

In this way, the partially ionized evaporated material is transferred to the grid 6.
At that time, the thermoelectrons vibrating up and down in the vicinity of the grid collide with the ionized introduced gas, and are further ionized. At this time, the gas molecule density is increasing near the grid 6, so ionization progresses further.

The portion of the evaporated material that has passed through the grid 6 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 substance ionized into positive ions is accelerated toward the deposition substrate 100 by the action of the electric field from the grid 6 toward the counter electrode 5, collides with the deposition substrate 100 at high speed, and adheres to the substrate as desired. Forms a thin film.

Next, the case of the thin film forming apparatus shown in FIG. 2 will be explained.

In FIG. 2, first, the Pel jar 1 is opened, and the thin film forming substrate 100 is held on the counter electrode 5 as shown, and the evaporation substance is held on the evaporation source 8.

Note that the evaporative substance is selected depending on what kind of thin film is to be formed.

Next, the Pelger 1 is closed to seal the vacuum chamber 1', and the vacuum chamber 1' is evacuated to a vacuum state using a vacuum exhaust system (not shown). Active gas or a mixture of these gases at 10 to 1 O-jP
Introduce at a pressure of a. In the present description, the introduced gas is assumed to be an active gas such as oxygen.

Now, when the apparatus is operated in the above atmospheric condition and the evaporation source 8 is heated, the evaporation substance evaporates.

The evaporated substance, that is, the particles of the evaporated substance fly while spreading toward the thin film forming substrate 100, and the grid 6
However, some of it remains as it is or becomes a compound and adheres to the grid 6 and the inside of the vacuum chamber.

On the other hand, thermionic electrons are emitted from the filament 7. The emitted thermionic electrons are accelerated by the electric field of the grid 6 and the vacuum chamber 1', and fly toward the grid 6 and the vacuum chamber 1', and the introduced gas molecules , and when collided with the evaporated particles, they are ionized.

In this way, a plasma state is generated in the space near the filament 7.

Evaporated particles and ionized evaporated particles fly out from the evaporation source 8 with energy during evaporation, so the counter electrode 5
It flies in the direction of , collides with the thin film forming substrate 100 , and forms a desired thin film on the thin film forming substrate 100 .

Note that if a negative potential is applied to the counter electrode 5 at this time, an electric field is generated from the grid or the like toward the counter electrode 5, and the ionized evaporated particles are accelerated by the electric field and are deposited on the thin film forming substrate 100. The particles collide with each other in an accelerated state, forming a thin film with better adhesion.

As described above, the thin film formed by the apparatus shown in FIGS. 1 and 2 is formed by the collision of ion particles with the substrate, so it has excellent adhesion to the substrate 100 and has good crystallinity. In good condition.

Further, 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. In addition, in the apparatus 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.

In particular, in the apparatus shown in Fig. 2, even thin films of insulating compounds can be coated.
It can be obtained stably, easily and reliably.

Next, to give an example of thin film formation using the thin film forming apparatus of the present invention, for example, argon is introduced as an inert gas, oxygen is introduced as an active gas, the pressure is adjusted to 10 to 1 O-2 Pa, indium is If tin, zinc, etc. are selected, a thin film of indium oxide, tin oxide, zinc oxide, etc. can be formed on the substrate, and if aluminum is selected as the evaporation material, an insulating thin film of aluminum oxide can be formed on the substrate. can be formed. Moreover, if silicon or -silicon oxide is selected as the evaporation substance, a silicon dioxide insulating thin film can be obtained.

Further, by introducing a gas such as nitrogen or ammonia as an active gas and using a metal such as titanium, tantalum, or iron as an evaporator, a thin film of titanium nitride, tantalum nitride, iron nitride, or the like can be obtained. Moreover, if gold, aluminum, etc. are used together with argon gas, a dense thin film of gold, aluminum, etc. can also be obtained.

By the way, in the thin film forming apparatus of the present invention, thermionic electrons generated by the filament effectively contribute to the ionization of the evaporated substance and the introduced gas, so that the ionization of the evaporated substance can be achieved even under a high vacuum with a pressure of 1O-3Pa or less. As a result, the incorporation of gas molecules into the thin film can be extremely reduced, making it possible to obtain a thin film of high purity and making it possible to make the structure of the thin film extremely dense. Although it is generally said that the density of a thin film is smaller than that of a bulk film, one of the major features of the present invention is that a density very close to that of a bulk film can be obtained. That is, the thin film forming apparatus of the present invention can be applied to IC, LSI
Part 1 of the semiconductor thin film that constitutes etc.! It is extremely suitable for J-' formation.

〔Effect of the invention〕

As explained above, according to the thin film forming apparatus of the present invention,
It is applicable to a wide range of thin film production, not only thin films composed of a single element such as metal thin films, but also compound thin films, which have good adhesion and can be produced in a state closer to stoichiometric thin films. can.

In addition, when the filament is set to have a negative potential with respect to the vacuum chamber and the grid as in the thin film forming apparatus according to claim 2, spatter caused by ions colliding with the inner wall of the vacuum chamber, etc. Since this phenomenon is almost eliminated, it is possible to obtain a thin film with higher purity, and it is also possible to easily cope with increasing the area and mass production of insulating thin films.

Further, according to the present invention, since the evaporated substance is ionized and electrically has high energy, film formation that requires 1 reactivity and film formation that requires crystallization is performed at a temperature (reaction temperature, crystallization temperature). Since this can be achieved without applying thermal energy, low-temperature film formation becomes possible.

[Brief explanation of the drawing]

1 is a schematic configuration diagram of a thin film forming apparatus showing an embodiment of the invention as claimed in claim 1, and FIG. 2 is a schematic diagram of a thin film forming apparatus showing an embodiment of the invention as claimed in claim 2. . 1...Pelger, 1'...Vacuum chamber, 2...
・Pace plate, 3...Backing, 4,4A...
... Gas introduction pipe, 5... Counter electrode, 6... Grid, 7... Filament 8... Evaporation source, 9.
10.11.12... Electrode, 20.22... AC power supply, 21... DC power supply, 100... Thin film formation substrate.

Claims (2)

[Claims] 1. 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. a grid capable of causing the filament to have a grid, a power supply means for realizing a predetermined electrical state in the vacuum chamber, and a conductive means for electrically connecting the inside of the vacuum chamber and the power supply means; A thin film forming apparatus characterized in that the potential of the grid is set to be a positive potential and gas can be introduced into the grid. 2. 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. a grid that can be connected to the vacuum chamber, power supply means for realizing a predetermined electrical state in the vacuum chamber, and conductive means for electrically connecting the inside of the vacuum chamber and the power supply means; On the other hand, a thin film forming apparatus characterized in that the electric potential of the filament is set to a negative electric potential and gas can be introduced into the grid.