JP2774541B2 - Thin film forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to strong reactivity which is an advantage of CVD (chemical vapor deposition), and high vacuum which is an advantage of PVD (physical vapor deposition). The present invention relates to a thin film forming apparatus that realizes film formation at the same time and also enables uniform thin film formation on a large-area substrate.

[Conventional technology]

As a thin film forming apparatus for forming a thin film on a thin film forming substrate (hereinafter, referred to as a substrate), various apparatuses utilizing a CVD method, a PVD method, and the like have been proposed, and the methods are also extremely diverse.

However, in the conventional thin film forming apparatus, the adhesion of the formed film to the substrate is weak, or it is difficult to form a thin film on a substrate having no heat resistance, or on a large area substrate. However, when a thin film is formed uniformly, it is difficult to form a uniform thin film.

Therefore, the present applicant has previously arranged, as a thin film forming apparatus, a counter electrode for holding a substrate facing an evaporation source in a vacuum chamber and a grid between the counter electrode and the evaporation source, and a grid. There has been proposed an apparatus in which a filament for generating thermoelectrons is disposed between a filament and an evaporation source, and a grid is formed at a positive potential with respect to the filament to form a thin film (JP-A-59-5959)
89763).

In this thin film forming apparatus, the evaporating substance evaporated from the evaporation source is first ionized by thermionic electrons from the filament, and the ionized evaporating substance passes through the grid and acts as an electric field from the grid to the counter electrode. And is collided with the substrate on which the thin film is to be formed, whereby a thin film having good adhesion is formed.

[Problems to be solved by the invention]

However, in the above-described thin film forming apparatus, when a thin film is formed on a large-area substrate, the film thickness distribution on the substrate surface tends to be uniform due to the action of an electric field from the grid as compared with general vacuum deposition. There is a problem that the positional relationship between the source and the counter electrode greatly affects the film thickness distribution, and the film thickness is not always uniform.

The present invention has been made in view of the above circumstances, can form a thin film having extremely strong adhesion to the substrate,
It is an object of the present invention to provide a novel thin film forming apparatus capable of using a plastic or the like having no heat resistance as a substrate and capable of forming a uniform thin film on a large-area substrate.

[Means for solving the problem]

In order to achieve the above object, a thin film forming apparatus according to the present invention includes a vacuum chamber into which an active gas or an inert gas or a mixed gas thereof is introduced, and an evaporation source for evaporating an evaporant in the vacuum chamber. A counter electrode that is disposed in the vacuum chamber so as to face the evaporation source and holds the thin film formation substrate; a filament for generating thermoelectrons disposed between the evaporation source and the counter electrode; A grid provided between the electrode and the counter electrode, through which evaporating substances can pass, power supply means for realizing a predetermined electrical state in the vacuum chamber, and electrically connecting the power supply means in the vacuum chamber with the power supply means Conductive means for making the grid have a positive potential with respect to the filament and adjusting the potential distribution in the grid plane.

[Action]

In the thin film forming apparatus according to the present invention, the vacuum chamber is
An active gas, an inert gas, or a mixed gas of both can be introduced into the internal space, and an evaporation source, a counter electrode, a filament, and a grid are provided in a vacuum chamber.

The counter electrode and the evaporation source provided in the vacuum chamber are disposed so as to face each other, and the counter electrode is configured to hold the thin film formation substrate on the side facing the evaporation source.

The grid is capable of passing an evaporating substance, is interposed between the evaporation source and the counter electrode, and is set to a positive potential with respect to the filament by a power supply means. Therefore, when a thin film is formed, the generated electric field travels from the grid to the filament. Further, the potential of the grid can be varied in the grid plane by power supply means or the like.

The filament is for generating thermoelectrons and is provided between the evaporation source and the grid.

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

Therefore, in the thin film forming apparatus having the above configuration, a stable plasma state can be created by heating the filament and adjusting the grid potential, and the direction of ions can be controlled by giving a distribution to the grid potential. Therefore, a uniform thin film can be stably supplied on the substrate.

〔Example〕

Hereinafter, the present invention will be described in detail based on one embodiment shown in the drawings.

FIG. 1 is a schematic configuration diagram of a thin film forming apparatus showing one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a bell jar, and reference numeral 2 denotes a base plate.
The bell jar 1 and the base plate 2 are integrated by a packing 3 to form a vacuum chamber, and an active gas and / or an active space is formed in the internal space by a known appropriate method such as a gas introduction pipe and a valve indicated by reference numeral 4. Inert gas can be introduced. A hole 2A formed in the center of the base plate 2 is connected to a vacuum exhaust system (not shown).

The base plate 2 keeps the confidentiality inside the vacuum chamber,
Further, electrodes 9, 10, 11, and 12, which also serve as a support while maintaining electrical insulation from the base plate 2, are provided. These electrodes 9, 10, 11, 12 electrically connect the inside and the outside of the vacuum chamber, and constitute conductive means together with other wiring members.

Among the above-mentioned electrodes, between a pair of electrodes 11, a resistance heating type evaporation source 8 in which a metal such as tungsten, molybdenum, tantalum or the like is formed in a board shape is supported. The shape of the evaporation source 8 may be a coil or a crucible instead of a boat. Instead of such an evaporation source, an evaporation source such as an electron beam evaporation source used in a conventional vacuum evaporation method can be appropriately used.

Further, between the other pair of electrodes 10, a filament 7 for generating thermoelectrons made of tungsten or the like is supported.
The shape of the filament 7 is determined such that a plurality of filaments are arranged in parallel or meshed to cover the spread of particles of the evaporated substance evaporated from the evaporation source.

A grid 6 is supported on the electrode 12, and the grid 6 is shaped so as to allow the evaporated substance to pass to the counter electrode 5 side. In this embodiment, the grid 6 has a mesh shape.

The counter electrode 5 is supported on the tip of the electrode 9, and the substrate 100 on which the thin film is to be formed is held on a surface of the counter electrode 5 facing the evaporation source 8 by an appropriate method. Although the electrode 9 is grounded as it is in the illustrated example, a DC power supply may be applied during this time to bias the counter electrode 5.

The electrode 11 supporting the evaporation source 8 is connected to an AC power supply 20 for heating. However, the power supply may be a DC power supply instead of the AC power supply. May be.

Further, the electrode 10 supporting the filament 7 is connected to a power supply 22.
Either of direct current may be used.

Further, the electrode 12 is connected to the positive electrode side of the DC voltage power supply 21,
The negative side of the power supply is connected to one side of the electrode 10 in the illustrated example. Therefore, the grid 6 has a positive potential with respect to the filament 7, and the electric field is directed from the grid 6 to the filament 7 between the grid 6 and the filament 7. In the illustrated example, the potential of the grid 6 can be changed in four by a variable resistor. However, the potential in the grid 6 can be changed by an arbitrary method, such as performing a potential change operation using different DC power supplies. It is sufficient that the potential distribution can be manipulated. The connection between the variable resistors in the figure is
It is attached to the periphery of the grid 6 so as not to affect the formation of the thin film, or is made thinner and smaller.

Here, one side of the power supply 21 in FIG. 1 is grounded as it is.
And / or the filament 7 may be biased.

 Note that grounding in the figure is not always necessary.

Also, in practice, the electrical connection between each of the electrodes and the power supply includes various switches constituting a part of the conductive means,
The vapor deposition process is performed by operating these switches, but these switches are not shown in the figure and are omitted.

Now, in the thin film forming apparatus having the above configuration,
A stable plasma state can be created by adjusting the filament heating power supply 22 and the grid DC power supply 21. In addition, by giving a distribution to the potential of the grid, the direction of ions can be controlled, and a uniform thin film can be stably supplied on a large-area substrate.

Next, the formation of a thin film by the thin film forming apparatus having the above configuration will be described in detail.

In FIG. 1, a thin film forming substrate (hereinafter, referred to as a substrate) 100 is held by a counter electrode 5 as shown in FIG. The evaporating substance is selected depending on what kind of thin film is formed.

Further, an active gas, an inert gas, or a mixed gas thereof is previously introduced into the vacuum chamber at a pressure of 10 to 10 ⁻³ Pa. In addition, in the explanation given, this introduced gas is
For example, let it be an inert gas such as argon.

Now, when the apparatus is operated under such conditions and the evaporation source 8 is heated, the evaporated substance is evaporated. The evaporating substance, that is, particles of the evaporating substance fly while spreading toward the substrate 100, and a part thereof and the introduced gas are ionized into positive ions by collision with thermionic electrons emitted from the filament 7. .

As described above, the partially ionized evaporating substance passes through the grid 6, but at that time, is further ionized by the thermal electrons oscillating vertically in the vicinity of the grid 6 and the collision with the ionized introduced gas.

The unionized portion of the evaporating substance that has passed through the grid 6 is further ionized into positive ions by collision with the ionized introduced gas, and the ionization rate is increased.

Thus, the evaporated substance ionized into positive ions is applied to the substrate by the action of an electric field from the grid 6 to the counter electrode 5.
It is accelerated toward 100 and collides and adheres to the substrate 100 at high speed. At this time, after the ionized evaporated particles which have jumped out of the evaporation source 8, a force is applied to the flying particles in the direction of the electric field by the action of the electric field directed from the grid 6 to the counter electrode 5, whereby the film is formed. Although the thickness distribution tends to be uniform, the electric field is changed by changing the electric potential in the grid plane to control the direction of the ionized evaporated particles.

2 (a) and 2 (b) show an example of a state inside the vacuum chamber when the grid potential is changed. FIG. 2 (a) shows a grid when a uniform potential is applied to the grid 6. FIG. 6B is a diagram showing an electric field from 6 to the counter electrode 5, and FIG. 7B is a diagram showing an electric field when the potential of the portion A is higher than that of the portion B in the grid plane.

2 (a) and 2 (b), the particles of the evaporating substance evaporated from the evaporating source 8 try to fly linearly as indicated by the arrows in the figure, and some of them are ionized on the way, and pass. Here, a portion A in the grid plane and a portion B
The potential of a different value can be given to the portion.

By the way, on the thin film forming surfaces a and b of the substrate attached to the counter electrode 5, in the case of normal vapor deposition (a state in which no potential is applied to the grid), when evaporating particles reach the thin film forming surface, Since the surface b is in a state close to normal incidence, the uniformity of the film is slightly impaired, but the surface a becomes an uneven film due to a difference in the incident angle and the distance.

Thus, by uniformly applying a potential to the grid 6 to create an electric field as shown in FIG. 2A and changing the flight direction of the ionized particles, the uniformity of the film on the b-plane is improved. , A-plane also approaches uniformity. Furthermore, in order to make the angle of incidence of the ionized vaporized particles on the a and b planes close to normal incidence,
By setting the potential of the portion A in the grid plane higher than that in the direction B for the ions incident on the a-plane, for which the flight direction needs to be largely changed, the electric field as shown in FIG. Is formed, and control is performed such that ions are incident perpendicularly to both the a-plane and the b-plane. Then, a uniform thin film is formed on the large-area substrate in this manner. It should be noted that, in the figure, the vacuum tank, holder, power supply, and the like are omitted.

Now, since the thin film thus formed is formed by the collision of the ion particles with the substrate 100, the thin film has excellent adhesion to the substrate 100, and has good crystallinity and crystal orientation.

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

In the thin film forming 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 obtained easily and reliably.

For example, if argon is introduced as an inert gas and oxygen is introduced as an active gas to adjust the pressure to 10 to 10 ^-2 Pa and aluminum is selected as the evaporating substance, an aluminum oxide insulating thin film can be formed on the substrate. Can be.

In this case, if silicon is selected as the evaporating substance, a silicon dioxide insulating thin film can be obtained. If indium or tin is selected as the evaporating substance, a conductive thin film such as indium oxide or tin oxide can be obtained. If nitrogen or ammonia is used together with argon as an active gas, and titanium or tantalum is selected as an evaporating substance, a thin film of titanium nitride or tantalum nitride can be obtained.

Since thermionic electrons from the filaments effectively contribute to the ionization of the vaporized substance and the introduced gas, the vaporized substance can be ionized even under a high vacuum at a pressure of 10 ^-2 Pa or less. Since the incorporation of gas molecules can be extremely reduced, a high-purity thin film can be obtained, and the structure of the thin film can be extremely dense. According to the present invention, it is said that the density is much smaller than that of the bulk. That is, the thin film forming apparatus of the present invention is an IC,
It is extremely suitable for forming a semiconductor thin film or the like constituting an LSI or the like.

〔The invention's effect〕

As described above, according to the embodiment shown in the drawings, according to the present invention, a thin film having extremely strong adhesion to a substrate can be formed, and film formation and crystallization that require reactivity are performed. Can be realized without applying thermal energy such as temperature, so that low-temperature film formation is possible, and a plastic or the like having no heat resistance can be used as a substrate. Further, a uniform thin film can be formed on a large-area substrate.

In addition to a thin film composed of a single element such as a metal thin film on a large-area substrate, a compound thin film and the like have good adhesion, and have a uniform thickness close to a stoichiometric thin film. Therefore, it is possible to sufficiently cope with mass production.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a thin film forming apparatus showing one embodiment of the present invention, and FIG. 2 is an example of a state inside a vacuum chamber when a grid potential is changed in the thin film forming apparatus having the configuration shown in FIG. FIG. 4A shows an electric field from the grid to the counter electrode when a uniform potential is applied to the grid, and FIG.
FIG. 4 is a diagram showing an electric field when the potential of the portion A is higher than that of the portion B in the grid plane. 1 ... bell jar, 2 ... base plate, 3 ... packing, 5 ... counter electrode, 6 ... grid, 7 ... filament, 8 ... evaporation source, 9, 10, 11, 12 ... electrode, 20 ... ... AC power supply, 21,22 ... DC power supply, 100 ... Film-forming substrate.

Claims (1)

(57) [Claims] 1. A vacuum chamber into which an active gas or an inert gas or a mixture thereof is introduced, an evaporation source for evaporating an evaporating substance in the vacuum chamber, and an evaporation source in the vacuum chamber. A counter electrode that is disposed to face the thin film formation substrate, a filament for generating thermoelectrons disposed between the evaporation source and the counter electrode, and is disposed between the filament and the counter electrode. A filament through which the evaporating substance can pass, a power supply for realizing a predetermined electrical state in the vacuum chamber, and a conductive means for electrically connecting the power supply with the vacuum chamber; For the grid to be at a positive potential,
A thin film forming apparatus characterized in that a potential distribution in a grid plane can be adjusted.