JP2611627B2 - Thin film forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus using a pulsed electron beam.

[0002]

2. Description of the Related Art Conventionally, a target is radiated by using a pulsed high energy density beam to evaporate or plasmatize the target (this is called ablation), and scattered particles formed by the irradiation are deposited on a substrate. When a thin film is formed by such a method, an excimer laser has been typically used as an energy source.

[0003] This method is generally called laser PVD, and FIG. 4 is a schematic diagram of a thin film forming apparatus using the method.

In this thin film forming apparatus, a laser beam 12 emitted from an excimer laser light source 10 is condensed by a lens 14 and then introduced into a vacuum vessel 4 in which the target and the substrate 2 are stored through an optical window 16 to thereby form the target. 6.

[0005] Since the laser beam 12 is condensed and radiated onto the target 6 at a very high peak power density, the surface of the target 6 is evaporated or turned into plasma. Because of the incidence and collision, a thin film having good adhesion is formed on the substrate 2.

[0006]

However, the laser beam 12 from the excimer laser light source 10 has a small energy per shot of about 0.3 J to 0.5 J (pulse width of about 20 ns), and has a low energy per second. Even if the number of shots is increased, the energy per shot is small,
The average output is as small as about 30 W to 100 W.
The target 6 is usually a metal, but the metal target has a large reflection of the laser beam 12 and therefore has a low energy absorption rate, and a considerable portion is reflected and is not absorbed by the target 6. For these reasons, the substrate 2
However, there is a problem that the film forming speed is low.

Further, since the laser light 12 is condensed and irradiated to the target 6 considerably, the area for evaporating or turning the target 6 into a plasma is small, so that the area where the thin film is formed on the substrate 2 is relatively small. In addition, there is a problem that the uniformity is poor because the film thickness is different between the central part and the peripheral part.

Further, if the operation is performed for a long time, the scattered particles 8 from the target 6 adhere to the optical window 16, so that the transmittance of the laser beam 12 at the optical window 16 is reduced, thereby decreasing the film forming speed. There is also a problem.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a thin film forming apparatus capable of forming a film at a high speed, with a large area and with good uniformity of the film thickness, and which does not cause a decrease in the film forming speed due to long-time operation. And

[0010]

In order to achieve the above object, a thin film forming apparatus according to the present invention comprises: a vacuum container; a cathode and an anode provided in the vacuum container so as to face each other; A high-voltage pulse power supply for applying a high-voltage pulse between the pulsed electron source and a target provided in a vacuum vessel at a position irradiated with a pulsed electron beam generated from a cathode and extracted through an anode. It is characterized in that scattered particles produced by evaporating or plasma-forming a target by a beam are incident and deposited on a substrate.

[0011]

According to the above arrangement, when a high voltage pulse is applied between the cathode and the anode from a high voltage pulse power supply, a pulsed electron beam is generated from the cathode and is extracted through the anode to irradiate the target. As a result, the target is evaporated or turned into plasma, and the scattered particles generated thereby are incident on and deposited on the substrate to form a thin film.

In this case, the pulsed electron beam can easily increase the energy per shot and the average output, and have a very high absorption rate at the target. Therefore, the target can be evaporated or turned into a plasma in a large area and in a large amount as compared with the excimer laser.
In addition, since the pulsed electron beam is generated in the vacuum vessel, there is no need to pass through an object such as an optical window.

[0013]

FIG. 1 is a schematic sectional view showing a thin film forming apparatus according to one embodiment of the present invention. This thin film forming apparatus includes a vacuum vessel 4, a cathode 20 and an anode 22 provided in the vacuum vessel 4 so as to face each other, and a high voltage for applying a high voltage pulse between the cathode 20 and the anode 22. A pulse power source 26 and a target 6 provided in the vacuum vessel 4 at a position irradiated with a pulsed electron beam 28 generated from the cathode 20 and extracted through the anode 22 are provided, and face the target 6. The substrate 2 is arranged at the position.

The vacuum vessel 4 has a cylindrical shape in this example, and is evacuated by a vacuum exhaust device (not shown). In addition, one end side is partitioned inside and outside by an insulating partition wall 24.

The cathode 20 is a cold cathode, and in this example, has a cylindrical shape, and is supported by the partition wall 24.

Although the anode 22 is in the form of a perforated plate in this example, it may be in the form of a mesh or a metal foil. In short, the anode 22 allows most of the pulsed electron beam 28 generated from the cathode 20 to pass therethrough. Is fine. In this example, a high voltage pulse is applied to the anode 22 from a high voltage pulse power supply 26 via the vacuum vessel 4.

The high-voltage pulse power supply 26 is composed of, for example, a DC power supply and a high-voltage pulse generator such as a Marx generator that generates a high-voltage pulse using a DC voltage from the DC power supply. However, it is not limited to such a configuration.

An operation example will be described. When a high voltage pulse is applied from the high voltage pulse power supply 26 between the cathode 20 and the anode 22 while the cathode 20 side is negative , the electric field causes the anode 22 of the cathode 20 to be turned off. Electrons are emitted from the surface opposite to. At this time, the surface of the cathode 20 has many small protrusions called whiskers when viewed microscopically due to the roughness, and electrons are intensively emitted from the whiskers. A plasma is generated in between.
The electrons in the plasma are accelerated by the electric field between the anode 22 and the cathode 20, and most of the electrons pass through a number of holes in the anode 22 and are extracted as a pulsed electron beam 28.

The pulsed electron beam 28 thus extracted is irradiated on the target 6, whereby the surface of the target 6 is vaporized or turned into plasma (ablation). Thus, a thin film is formed.

In this case, the pulsed electron beam 28 can easily increase the energy per shot. For example, it is easy to realize energy of about 500 J to 1 kJ per one shot (pulse width is about 50 to 100 ns). This is because the energy conversion efficiency when generating a pulsed electron beam is extremely high (for example, an excimer laser is about several percent, while a pulsed electron beam is as easy as about 50%). is there. Further, since the pulsed electron beam 28 has a high energy per shot as described above, the average output can be easily increased. For example, it is easy to realize about 500 W to 1 KW.

Moreover, the pulsed electron beam 28 hardly reflects on the target 6, and the absorption rate of the pulsed electron beam 28 on the target 6 is almost 100%, which is very high.

As described above, since the pulsed electron beam 28 has a large energy and a very high absorption rate at the target 6, the pulsed electron beam 28
It is possible to irradiate a considerably large area as compared with a laser without converging to the above one point. In this case, the peak power density of the pulsed electron beam 28 is lower than the maximum value of the excimer laser, but the target 6 can be sufficiently evaporated and turned into plasma.

As a result, the target 6 can be evaporated and turned into a plasma in a large area and in a large amount compared with the excimer laser, so that a large-area and high-speed thin film can be formed on the substrate 2.

Further, since the scattering particles 8 can be generated from a wide area, the uniformity of the thickness of the thin film formed on the substrate 2 is also improved.

Further, since the pulsed electron beam 28 is generated in the vacuum vessel 4, it is not necessary to pass through an optical window unlike the case of the excimer laser. Not even.

FIG. 2 is an enlarged sectional view showing a target portion of a thin film forming apparatus according to another embodiment of the present invention.
The difference from the embodiment of FIG. 1 will be mainly described. In this embodiment, the target 6 is a cone, and the pulsed electron beam 28 is irradiated from the vertex thereof. More specifically, the target 6 has, for example, a conical shape, but may have a pyramid shape.

According to this embodiment, scattered particles 8 are generated from the side surface of the cone-shaped target 6 in a plurality of directions, so that a thin film can be formed on a plurality of substrates 2 at the same time.

FIG. 3 is a schematic sectional view showing a thin film forming apparatus according to still another embodiment of the present invention. The difference from the embodiment of FIG. 1 will be mainly described. In this embodiment, the target 6 is a foil having a thickness equal to or less than the range of the pulsed electron beam 28 in the target material. I have. For example, when the energy of the pulsed electron beam 28 is 100 KeV and the material of the target 6 is aluminum, the range of the pulsed electron beam 28 in aluminum is about 50 μm, so that the thickness of the foil-shaped target 6 is about 50 μm or less. You can do it. Reference numeral 30 denotes a support plate that supports such a foil-shaped target 6.

When the thickness of the foil-shaped target 6 is set as described above, the pulsed electron beam 28 reaches the entire region of the target 6 in the depth direction.
It is possible to evaporate and plasmatize all the targets 6 in the region irradiated with. Therefore, the scattered particles 8 from the target 6 spread in all directions, and the substrate 2 can be arranged not only in front of the target 6 but also behind it, and thin films can be formed on a plurality of substrates 2. Become. In addition, unlike the front side, there is no need to pass the pulsed electron beam 28 unlike the front side, so there is no space limitation, so that a film can be formed on a larger substrate 2.

In addition, in the case of a target having a normal thickness, droplets (sprays of a molten target which do not reach evaporation and plasma conversion) are generated and adhere to the substrate 2, whereby the film thickness becomes uniform. In this embodiment, the target 6 in the area irradiated with the pulsed electron beam 28 is basically entirely evaporated and converted into plasma. The number of droplets is greatly reduced. as a result,
A high-quality thin film can be formed.

[0031]

As described above, according to the present invention, a pulsed electron beam is used as a high energy beam source.
Since the pulsed electron beam can easily increase the energy per shot and the average output, and have a very high absorption rate at the target, the target can be vaporized or turned into a plasma in a larger area and in a larger amount than an excimer laser. Therefore, it is possible to form a film at a high speed, with a large area and with a uniform film thickness. In addition, since the pulsed electron beam is generated in the vacuum vessel, there is no need to pass through an object such as an optical window.

If a target is made into a cone and a pulsed electron beam is irradiated from the vertex thereof, a thin film can be simultaneously formed on a plurality of substrates.

If the target is formed into a foil having the above-mentioned film thickness, a thin film can be formed on a plurality of or larger substrates. Moreover, the number of droplets is greatly reduced, and a high-quality thin film can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a thin film forming apparatus according to one embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a target portion of a thin film forming apparatus according to another embodiment of the present invention.

FIG. 3 is a schematic sectional view showing a thin film forming apparatus according to still another embodiment of the present invention.

FIG. 4 is a schematic view showing an example of a conventional thin film forming apparatus.

[Explanation of symbols]

 2 Substrate 4 Vacuum container 6 Target 8 Scattered particles 20 Cathode 22 Anode 26 High voltage pulse power supply 28 Pulsed electron beam

Claims (3)

(57) [Claims] 1. A vacuum vessel , a cathode and an anode, which are cold cathodes provided so as to face each other in the vacuum vessel, and a cathode side between the cathode and the anode is negative.
Apply a high voltage pulse to the cathode and anode
A plasma is generated in between, and electrons in this plasma are anodized.
Comprising a high-voltage pulse power source to draw a pulsed electron beam through over de, a target which is provided at a position pulse electron beam extracted through A node a vacuum chamber is irradiated, evaporated target by a pulsed electron beam Alternatively, a thin film forming apparatus is characterized in that scattered particles formed by plasma are incident and deposited on a substrate. 2. The thin film forming apparatus according to claim 1, wherein the target is a cone, and the pulsed electron beam is irradiated to the cone from the vertex thereof. 3. The thin film forming apparatus according to claim 1, wherein the target is a foil having a thickness equal to or less than a range of the pulsed electron beam in the target material.