JPH04218665A - Apparatus for forming thin film - Google Patents

Abstract

PURPOSE:To efficiently and stably form high quality of vapor-deposited film on a base plate by constituting an ionizing device in a cluster ion beam vapor- depositing device with a nozzle, cathode and anode having the specific structure. CONSTITUTION:A crucible 3 charging depositing material 2 is heated in a vacuum vessel 17 by energizing a filament 5 and vapor in the vapor-depositing material 2 is ejected from the nozzle 4 in the crucible 3 to form the cluster 7. Simultaneously, the ionizing filament 22 is energized and heated and thermal electrons are discharged toward the anode 23 and collided with the cluster 7 to make the ionized cluster 12. Further, by fitting a magnetic field impressing device 24, since the magnetic field in a vertical direction perpendicular to an electric field formed with the ionizing filament 22 and anode 23 is formed, the electrons are spirally moved and ionizing efficiency is improved and high quality of vapor-deposited film can be formed on the base plate 16.

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

0002

[Prior Art] Conventionally, semiconductor films, optical thin films, magnetic films,
High quality thin films such as insulating films are formed by the ICB method. FIG. 2 is a sectional view schematically showing a conventional thin film forming apparatus disclosed in, for example, Japanese Patent Publication No. 54-9592.

In the figure, 1 is a steam generation source that generates vapor of a vapor deposition material 2, 3 is a crucible containing the vapor deposition material 2,
4 is a nozzle formed on the top of crucible 3, 5 is crucible 3
A heating filament 6 is a first heat shield plate that blocks heat from the heating filament 5, and 6 is a first heat shield plate that blocks heat from the crucible 3, the heating filament 5, and the first heat. The shield plate 6 constitutes a steam generation source 1.

7 is a cluster (massive atomic group) generated from the vapor of the vapor deposition material 2 spouted upward from the nozzle 4; 8 is an ionization device installed above the steam generation source 1 to ionize the cluster 7; 9 is an electron 10 is a grid-shaped electron extraction electrode that extracts electrons from the ionization filament 9 and accelerates them toward the cluster 7; 11 is a second heat shield plate that blocks heat from the ionization filament 9; The filament 9, the electron extraction electrode 10, and the second heat shield plate 11 constitute the ionization device 8.

Reference numeral 12 denotes an ionized cluster ionized by the ionizer 8, 13 an accelerator which is provided above the ionizer 8 and accelerates the ionized cluster 12 toward a substrate 16, which will be described later, and 14 and 15 an acceleration electrode and a ground. Among the electrodes, the earth electrode 15 is at ground potential, and the accelerating electrode 14 is at a positive potential with respect to this, and both constitute an accelerator 13.

A substrate 16 is provided above the accelerator 13 and is at ground potential. Reference numeral 17 denotes a vacuum chamber which maintains the interior under vacuum and accommodates the upper parts 1 to 16. Reference numeral 18 denotes a vacuum evacuation system which evacuates the vacuum chamber 17 to bring it into a vacuum state.

Next, the operation will be explained. First, the inside of the vacuum chamber 17 is evacuated by the evacuation system 18 until the vacuum level reaches about 10<-6 >Torr. A voltage is applied so that the potential of the crucible 3 is positive with respect to the heating filament 5. Electricity is applied to the heating filament 5 to heat it, and the emitted electrons are drawn toward the crucible 3 by an electric field and collided with it, thereby heating the crucible 3 to a temperature where the vapor pressure within the crucible 3 becomes several Torr.

By this heating, the vapor deposited substance 2 in the crucible 3
is evaporated and the vapor is ejected upward from the nozzle 4. When this vapor passes through the nozzle 4, it is acceleratedly cooled by adiabatic expansion and condensed, forming a cluster 7.

In the ionization device 8, the potential of the electron extraction electrode 10 is kept positive with respect to the ionization filament 9. The ionized filament 9 is heated with electricity, and electrons emitted from the filament 9 are extracted by an electron extraction electrode 10. Some of the electrons are captured by the electron extraction electrode 10, but the other part flies through the grid-like gaps.
It collides with the cluster 7 and knocks out electrons with its energy, producing an ionized cluster 12 having a positive charge.

In the accelerator 13, the ionized clusters 12 are accelerated upward, ie, toward the substrate 16, by an electric field formed between an accelerating electrode 14 and a ground electrode 15, and the ionized clusters 12 are accelerated together with the neutral clusters 7 that are not ionized. 16 and forms a thin film (not shown) of the vapor deposited substance 2 on its surface.

[0011]

[Problems to be Solved by the Invention] Since the conventional thin film forming apparatus is configured as described above, when a vapor deposition substance having good wettability with the crucible material such as silicon (Si) or aluminum (Al) is used. , the molten deposition material creeps up the inner wall of the crucible and seeps out, and as it evaporates, the impedance between the crucible and the heating filament decreases, making it impossible to apply voltage between them. Therefore, it becomes impossible to operate the thin film forming apparatus stably.

[0012] Furthermore, some vapor deposition substances exhibit strong reactivity with the materials constituting the apparatus, and parts that are wet with the vapor deposition substance due to seepage or vapor condensation, especially the electron extraction electrode and the first
There have been problems in that the second heat shield plate and the like are corroded, resulting in an extremely shortened service life, or that these parts must be cleaned periodically to prevent this.

[0013] Among the electrons emitted from the ionized filament, those that contribute to the ionization of the cluster are:
Only the electrons that passed through the gaps between the grid-shaped electron extraction electrodes, and the electrons captured by the electron extraction electrodes, do not contribute to ionization, and therefore the ionization efficiency is low.

Furthermore, when attempting to control the properties of the thin film formed on the substrate by controlling the acceleration of the clusters by changing the potential difference (accelerating voltage) between the accelerating electrode and the earth electrode, it is possible to control the properties of the thin film formed on the substrate. As a result, the amount of ionized clusters drawn out also changes, and in particular, when the accelerating voltage is reduced, the amount of ionized clusters that reach the substrate becomes extremely small, making it possible to form a high-quality thin film that takes advantage of the characteristics of ionized clusters. Can not.

Furthermore, when the accelerating voltage is reduced to approach 0, the electric field between the accelerating electrode and the ground electrode becomes weaker, and the electrons ejected from the ionized filament are allowed to enter the substrate, causing damage. There was a problem.

The present invention was made to solve the above-mentioned problems, and aims to provide a thin film forming apparatus with good performance that can operate stably and efficiently and form high quality thin films. shall be.

[0017]

[Means for Solving the Problems] A thin film forming apparatus according to the present invention includes an ionization device including a cathode provided at a position facing a nozzle, and an anode surrounding the cathode, a crucible, and a heating device. It is. Further, the accelerator includes an accelerating electrode, an extraction electrode having a negative potential with respect to the accelerating electrode, and a control electrode having a potential intermediate between the potentials of the accelerating electrode and the extracting electrode.

[0018]

[Operation] In the thin film forming apparatus according to the present invention, the vicinity of the nozzle of the crucible is heated by the heat from the cathode, so that even if the molten vapor deposition material creeps up, it evaporates and suppresses the creeping up. Further, since the anode surrounds the crucible and the heating device, the anode is heated to a high temperature by these, and the vapor deposition material does not adhere thereto, thereby preventing corrosion caused by the vapor deposition material.

Furthermore, since the electrons emitted from the cathode are directly irradiated onto the cluster without passing through the grid-like electrode, ionization efficiency is improved.

Furthermore, the amount of ionized clusters incident on the substrate is maintained above a certain required level by the potential difference between the accelerating potential and the extraction electrode, and at the same time, the amount of ionized clusters is maintained by the potential difference (accelerating voltage) between the accelerating electrode and the control electrode. Acceleration can be controlled.

Furthermore, since the potential of the extraction electrode is negative with respect to the acceleration electrode, the electric field formed near the extraction electrode causes
Electrons are prevented from jumping out from the ionized filament toward the substrate.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a thin film forming apparatus according to an embodiment of the present invention.
12, 16 to 18 are the same as in the case of FIG. 2, so their explanation will be omitted. Reference numeral 1 denotes a steam generation source that generates the vapor of the vapor deposition material 2, and is composed of a crucible 3 and a heating filament 5.

21 is an ionization device provided above the steam generation source 1 to ionize the cluster 7; 22 is an ionization filament serving as a cathode provided at a position facing the nozzle 4; the ionization filament is heated with electricity to emit electrons; . 23 is an anode provided so as to surround the ionization filament 22, the crucible 3, and the heating filament 5, and the ionization filament 22 and the anode 23 constitute the ionization device 21. 24 is a magnetic field application device provided outside the ionization device 21.

Reference numeral 25 denotes an accelerator which is provided above the ionizer 21 and accelerates the ionized cluster 12 toward the substrate 16, 26 an acceleration electrode integrally connected to the anode 23, 27 an extraction electrode, and 28 a control electrode. As a ground electrode, it is at ground potential. The accelerating electrode 26, the extracting electrode 27, and the grounding electrode 28 are disposed in this order at positions farther away from the nozzle 4, and the accelerating electrode 26 has a positive potential and the extracting electrode 27 has a negative potential with respect to the grounding electrode 28. That is, the extraction electrode 27 has a negative potential with respect to the acceleration electrode 26, and the ground electrode 28 has a potential intermediate between the potentials of the acceleration electrode 26 and the extraction electrode 27. The three electrodes 26, 27, and 28 constitute an accelerator 25.

Next, the operation will be explained. As in the case of FIG. 2, the crucible 3 is heated with the heating filament 5, and the vapor of the vapor deposition substance 2 is ejected from the nozzle 4 to form the cluster 7. Further, the ionizing filament 22 is heated with electricity, and electrons are emitted from the filament 22 toward the anode 23, collide with the cluster 7, and ionize it. During this time, since the electrons do not need to pass through the grid-like gaps of the electron extracting electrode 10 as shown in FIG. 2, the electrons are effectively utilized. Further, in this embodiment, a magnetic field applying device 24 is provided, which forms a magnetic field in the vertical direction perpendicular to the electric field (left, right, and depth directions in the figure) formed by the ionization filament 22 and the anode 23. The particles move in a spiral manner, further improving ionization efficiency.

Furthermore, since the ionized filament 22 heats the vicinity of the nozzle 4, that is, the upper part of the crucible 3,
The molten vapor deposition substance 2 creeps up the inner wall of the crucible 3 and evaporates at the upper part of the crucible 3. Furthermore, since the anode 23 surrounds the heating filament 5 and the crucible 3, the anode 23 is kept at a high temperature, so that the vapor of the vapor deposition material 2 does not condense and adhere to the crucible 3 and the heating filament 3. There is no possibility that steam will build up between the points 5 and 5 and the impedance between them will drop.

The positively charged ionized clusters 12 ionized by the ionization device 21 are moved to the ionization device 2 by the electric field formed by the acceleration electrode 26 and the extraction electrode 27.
1 toward the substrate 16. The ionized cluster 12 passes between the extraction electrode 27 and the earth electrode 28, but since the earth electrode 28 has a positive potential with respect to the extraction electrode 27, the ionization cluster 12 is decelerated during this time. As a result, the ionized cluster 12 is given kinetic energy according to the potential difference (acceleration voltage) between the acceleration electrode 26 and the earth electrode 28.

Therefore, the acceleration electrode 26 and the extraction electrode 27
While maintaining the amount of ionized clusters 12 drawn out from the ionization device 21 above a certain required level due to the potential difference between them, the acceleration of the ionized clusters 12 can be controlled by the acceleration voltage. It becomes possible to form a thin film that takes advantage of its properties by securing the amount of .

Further, electrons flying out from the ionized filament 22 and heading toward the substrate 16 are prevented from entering the substrate 16 by the electric field formed by the negative potential extraction electrode.

In the above embodiment, the crucible 3 is heated by the heating filament 5, but the ionizing filament 22 may also be used as a heating device, and the crucible 3 may be heated by this. Further, although the magnetic field application device 24 is provided, the present invention can also be applied to a case where this is not provided.

[0031]

As described above, according to the present invention, the ionization device is constituted by the cathode provided at a position facing the nozzle, and the anode surrounding the cathode, the crucible, and the heating device. Electrons are directly irradiated to the cluster, improving ionization efficiency, and the vicinity of the nozzle of the crucible and the cathode are heated to high temperatures, preventing the deposited material from seeping out around the crucible or adhering to the anode.
Therefore, corrosion caused by the deposited material and a decrease in impedance between the crucible and the heating device are prevented.

[0032] Furthermore, since it is composed of an accelerating electrode, an extracting electrode having a negative potential with respect to the accelerating electrode, and a control electrode having a potential intermediate between the potentials of the accelerating electrode and the extracting electrode, the amount of ionized clusters can be increased beyond a certain level. It is possible to control the acceleration of the substrate while maintaining it, and furthermore, it is possible to prevent the electrons from entering the substrate and causing damage. As a result of the above, it is possible to obtain a high-performance thin film forming apparatus that can operate stably and efficiently and form high-quality thin films.

[Brief explanation of the drawing]

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

FIG. 2 is a sectional view showing a conventional thin film forming apparatus.

[Explanation of symbols]

2 is a deposition substance, 3 is a crucible, 4 is a nozzle, 5 is a heating filament, 7 is a cluster, 12 is an ionization cluster, 16 is a substrate, 21 is an ionization device, 22 is an ionization filament, 23 is an anode, 25 is an accelerator , 26
27 is an acceleration electrode, 27 is an extraction electrode, and 28 is a ground electrode.

Claims (2)

[Claims] 1. A crucible containing a vapor deposition material, a heating device for heating the crucible and ejecting vapor of the vapor deposition material from a nozzle formed in the crucible, and an ionization device for ionizing clusters generated from the vapor of the vapor deposition material. and a thin film forming apparatus comprising an accelerator for accelerating the ionized clusters toward the substrate on which the thin film is formed, the ionization device is provided at a position facing the nozzle and is heated to emit electrons. 1. A thin film forming apparatus comprising: a cathode for emitting light; and an anode surrounding the cathode, a crucible, and a heating device. 2. A crucible containing a vapor deposition material, a heating device for heating the crucible and ejecting vapor of the vapor deposition material from a nozzle formed in the crucible, and an ionization device for ionizing clusters generated from the vapor of the vapor deposition material. In a thin film forming apparatus equipped with an accelerator for accelerating the ionized clusters toward a substrate on which a thin film is formed, the accelerator includes an accelerating electrode, an extraction electrode having a negative potential with respect to the accelerating electrode, and a thin film forming apparatus comprising a control electrode having a potential intermediate between the acceleration electrode and the extraction electrode, and the acceleration electrode, extraction electrode, and control electrode are arranged in the order farther away from the nozzle.