JPH05179431A - Device for forming thin film - Google Patents

Abstract

PURPOSE:To prevent the lowering of the degree of vacuum during film formation due to degassing and to form a high quality thin film. CONSTITUTION:Positive bias potential impressed on a crucible 3 is made higher than the potential of an ionizing filament 10 so that the crucible 3 is directly irradiated with thermoelectrons emitted from the filament 10. The potential of an accelerating electrode 15a and that of a heat shielding plate 7 are made lower than the potential of a heating filament 6 and that, of the ionizing filament 10 so as to prevent the heating of the electrode 15a and the shielding plate 7.

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, and more particularly to a thin film forming apparatus for forming a high quality thin film by a cluster ion beam evaporation method (ICB method).

[0002]

2. Description of the Related Art Conventionally, high quality thin films such as optical thin films, magnetic films and insulating films have been formed by the ICB method. FIG. 3 is a schematic diagram showing a conventional thin film forming apparatus by the ICB method disclosed in Japanese Patent Publication No. 54-9592. In the figure, 1 is a vacuum chamber whose inside is maintained at a predetermined degree of vacuum, 2 is a vacuum exhaust system for exhausting the vacuum chamber 1 to a vacuum state, and 3 is a closed crucible placed in the vacuum chamber 1. There is at least one nozzle 4 on the upper part of the crucible 3. Reference numeral 5 is a vapor deposition substance filled in the crucible 3, 6 is a heating filament for heating the crucible 3, 7 is a heat shield plate for shielding heat from the heating filament 6, and 8 is a nozzle 4 for ejecting the vapor deposition substance. A cluster (lumpy atomic group) 9 formed by the above is a vapor generation source constituted by the crucible 3, the heating filament 6 and the heat shield plate 7.

Reference numeral 10 denotes an ionizing filament provided around the passage of the cluster 8 for emitting thermoelectrons (electron beams), 11 denotes an electron beam extraction electrode for extracting and accelerating thermoelectrons from the ionization filament 10, and 12 denotes an ionization filament 10. A heat shield plate 13 for blocking heat is an ionization means composed of an ionization filament 10, an electron beam extraction electrode 11 and a heat shield plate 12.

Reference numeral 14 is an ionization cluster ionized by the ionization means 13, 15a and 15b are acceleration electrodes and an earth electrode for accelerating the ionization cluster 14 with an electric field to give kinetic energy, and 16 is set in the vacuum chamber 1 and is placed on the surface. A substrate on which a thin film is formed.

Reference numeral 17 is a first for heating the heating filament 6.
AC power source, 18 is a first DC power source for biasing the potential of the crucible 3 positively with respect to the heating filament 6, 19 is a second AC power source for heating the ionizing filament 10, and 20 is an electron beam extraction electrode 11 for the ionizing filament 10. The second DC power supply biasing negatively with respect to the second, 21 is the crucible 3, the third DC power supply biasing the electron beam extraction electrode 11 and the acceleration electrode 15a positively with respect to the earth electrode 15b, 22 is the first AC power supply 17, The power supply device includes a first DC power supply 18, a second AC power supply 19, a second DC power supply 20, and a third DC power supply 21.

Next, the operation will be described. First, the vacuum chamber 1 is evacuated by the vacuum evacuation system 2 until the degree of vacuum reaches about 10 ⁻⁶ Torr. Next, the thermoelectrons emitted from the heating filament 6 are extracted by the electric field applied by the first DC power source 18, and the extracted thermoelectrons are made to collide with the crucible 3 so that the internal vapor pressure becomes several Torr. Heat crucible 3 until. By this heating, the vapor of the vapor deposition material 5 in the crucible 3 is jetted from the nozzle 4 into the vacuum chamber 1. When the vapor of the vapor deposition material 5 passes through the nozzle 4, the vapor is acceleratedly cooled by adiabatic expansion and condensed, thereby forming a cluster of massive atoms called a cluster 8.

A part of the cluster 8 is ionized by the electron beam emitted from the ionizing filament 10 to form an ionized cluster 14. This ionized cluster 14 (and the ionized vapor) is connected to the ground electrode.
Substrate 16 along with non-ionized neutral clusters 8 (and vapor) accelerated by the electric field applied at 15b
Hit the surface of. As a result, a thin film is formed on the substrate 16.

The functions of the DC power supplies in the power supply device 22 are as follows. The first DC power supply 18 causes the thermoelectrons emitted from the heating filament 6 to collide with the crucible 3. The second DC power supply 20 draws the thermoelectrons emitted from the ionized filament 10 into the electron beam extraction electrode 11. Third
The DC power supply 21 accelerates and controls the positively charged ionized clusters 14 by an electric field lens formed between the acceleration electrode 15a and the ground electrode 15b.

[0009]

In the conventional thin film forming apparatus configured as described above, when the number of thermoelectrons emitted from the heating filament 6 is increased to raise the temperature of the crucible 3, The extracted thermoelectrons are not only in the crucible 3 but also in the electron beam extraction electrode 11 having the same potential as the crucible 3.
Since the electron beam extracting electrode 11 and the accelerating electrode 15a are heated to a high temperature, the amount of gas released from the electron beam extraction electrode 11 and the accelerating electrode 15a is increased, and the degree of vacuum during film formation is lowered. There are problems that the quality of the film formed on the electron beam is deteriorated and the life of the electron beam extraction electrode 11 and the acceleration electrode 15a is shortened.

The present invention has been made to solve the above problems, and it is possible to prevent unnecessary heating of the portion other than the crucible, which results in a high deposition rate and a high deposition rate. It is possible to form a quality thin film,
Moreover, it is an object of the present invention to obtain a thin film forming apparatus capable of extending the life of parts.

[0011]

In the thin film forming apparatus according to the present invention, the thermoelectrons emitted from the ionizing filament are directly irradiated to the crucible, and the potential of the accelerating electrode is set to be equal to or lower than the potential of the heating and ionizing filaments. It was done.

[0012]

In the present invention, by directly irradiating the crucible with thermoelectrons emitted from the ionized filament,
By omitting the electron beam extraction electrode and setting the potential of the accelerating electrode to the potential for heating or less than that of the ionizing filament, heating of the accelerating electrode is prevented and only the crucible is heated to a high temperature.

[0013]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a thin film forming apparatus according to an embodiment of the present invention. The same or corresponding portions as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. In the figure, 23 is a fourth DC power supply for biasing the acceleration electrode 15a and the heat shield plate 7 to a negative potential with respect to the heating filament 6, and 24 is each DC power supply 18, 20, 21, 23 and each AC power supply 17, It is a power supply consisting of 19. Further, in this embodiment, the thermoelectrons emitted from the ionization filament 10 are directly irradiated onto the upper part of the crucible 3, so that the electron extraction electrode which has been conventionally used.
11 is omitted.

In the thin film forming apparatus of this embodiment having the above structure, the vacuum chamber 1 is used as in the conventional apparatus.
After evacuation of the inside by the vacuum evacuation system 2, the crucible 3 is heated by the heating filament 6 to form the cluster 8. A part of the cluster 8 is ionized by the electron beam irradiated from the ionizing filament 10 toward the periphery of the nozzle 4, and the ionized cluster is generated.
14 This ionized cluster 14 (and ionized vapor) is accelerated by the electric field applied by the acceleration electrode 15a and the ground electrode 15b, and collides with the surface of the substrate 16 together with the non-ionized neutral cluster 8 (and vapor). .. As a result, a thin film is formed on the substrate 16.

Here, in a normal operating region, the voltage applied to the heating filament 6 by the first DC power source 18 is larger than the voltage applied to the ionization filament 10 by the second DC power source 20, so that the ionization filament is
The potential of 10 is kept higher than that of the heating filament 6. Therefore, the potential of the ionized filament 10 becomes higher than the potentials of the acceleration electrode 15a and the heat shield plate 7.

Here, for the sake of clarity, the crucible 3
, The electric potential of the ionized filament 10 is Ei,
Assuming that the potential of the heating filament 6 is Eh, the potential of the heat shield plate 7 is Es, and the potential of the acceleration electrode 15a is Ea, the respective potentials in the above operating region are Ec>Ei>Eh> Es = E
It is kept like a.

As described above, in the above embodiment, the thermoelectrons emitted from the heating and ionizing filaments 6 and 10 are incident only on the crucible 3 and the accelerating electrode 15a is not heated. Since the electron extraction electrode 11 is omitted, only the crucible 3 is efficiently heated to a high temperature, a decrease in vacuum degree due to degassing is prevented, and a high quality thin film is formed. Also, the life of the acceleration electrode 15a can be extended. Further, since the crucible 3 is also heated by the thermoelectrons emitted from the ionization filament 10, the crucible 3 can be heated to a high temperature with a small electric power.

Further, in the above embodiment, the potential of the heat shield plate 7 is set lower than the potentials of the filaments 6 and 10, so that the heat shield plate 7 is prevented from being heated, which is more effective.

Even if the applied voltage of the fourth DC power supply 23 is 0, the same effect can be expected. Each potential in the operation region at this time is maintained as Ec>Ei> Eh = Es = Ea.

Example 2. FIG. 2 is a block diagram showing a thin film forming apparatus according to another embodiment of the present invention. In the figure, 25
Is a fifth DC power source for biasing the acceleration electrode 15a and the heat shield plate 7 to a negative potential with respect to the ionized filament 10,
Reference numeral 26 is a power supply device including each DC power supply 18, 20, 21, 25 and each AC power supply 17, 19. Other parts are the same as in the first embodiment.

The apparatus of this embodiment is an apparatus for depositing a vapor deposition material 5 having a particularly high vapor pressure. The voltage applied to the first DC power source 18 is set to 0, and the crucible 3 is heated by the radiant heat of the heating filament 6. Even in the case of heating, even when the bias voltage is applied to the first DC power supply 18 to heat the crucible 3 by thermoelectrons, the potential of the ionizing filament 10 is kept lower than the potential of the heating filament 6.

Therefore, since the respective potentials in the operating region at this time are kept as Ec ≧ Eh>Ei> Es = Ea, the thermoelectrons emitted from the ionizing filament 10 are incident only on the crucible 3, Only the crucible 3 is heated to a high temperature without heating the acceleration electrode 15a and the heat shield plate 7.

Further, the acceleration electrode 15a and the heat shield plate 7 may be kept at the same potential as the ionized filament 10. Each potential in the operating region at this time is Ec ≧ Eh> E
It holds as i = Es = Ea.

In each of the above embodiments, the acceleration electrode 15a and the heat shield plate 7 were set to the same potential, but different potentials are applied as long as the potentials for heating and the ionizing filaments 6 and 10 are maintained. You may.

[0025]

As described above, in the thin film forming apparatus of the present invention, the positive bias potential applied to the crucible is made higher than the potential of the ionizing filament, and the thermoelectrons emitted from the ionizing filament are made into the crucible. By directly irradiating and by setting the potential of the accelerating electrode to the potential for heating or less than the potential of the ionizing filament to prevent the accelerating electrode from being heated, it is possible to prevent the degree of vacuum during film formation from being lowered, which results in high Since a high quality thin film can be formed at a vapor deposition rate, the life of parts can be extended, and the crucible can be efficiently heated to a high temperature with a small electric power,
This has the effect of reducing running costs.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a thin film forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a thin film forming apparatus according to another embodiment of the present invention.

FIG. 3 is a configuration diagram showing an example of a conventional thin film forming apparatus.

[Explanation of symbols]

 1 Vacuum Tank 3 Crucible 5 Deposition Material 6 Heating Filament 8 Cluster 10 Ionizing Filament 14 Ionizing Cluster 15a Accelerating Electrode 16 Substrate

Claims (1)

[Claims] 1. A vacuum chamber for accommodating a substrate, a crucible provided in the vacuum chamber so as to face the substrate and filled with a vapor deposition material, and vapor of the vapor deposition substance ejected from the crucible to form clusters. A heating filament for heating the crucible to form, and provided between the crucible and the substrate,
A thin film forming apparatus including an ionizing filament that emits thermoelectrons for ionizing the cluster, and an accelerating electrode that is provided between the ionizing filament and the substrate and accelerates the ionized cluster toward the substrate. In, the positive bias potential applied to the crucible is made higher than the potential of the ionization filament, and the thermoelectrons emitted from the ionization filament are directly irradiated to the crucible,
A thin film forming apparatus wherein the potential of the accelerating electrode is equal to or lower than the potentials of the heating and ionizing filaments.