JPH0364458A - Thin film forming device - Google Patents

Abstract

PURPOSE:To deflect the ions formed right above a crucible and to prevent the ions from being concentrated to the center of a base plate for forming a thin film by providing a deflection electrode between an evaporation source and an ionizing means and forming a deflecting electric field. CONSTITUTION:In a device for forming a thin film by a cluster-ion beam method, the deflection electrodes 27a, 27b are provided so as to hold the cluster- beams emitted through a nozzle 26 right above an evaporation source 8. When impulse voltage for heating a crucible in the evaporation source 8 is regulated to about 1kV, deflection voltage of DC is impressed to the deflection electrodes 27a, 27b at several hundreds V or more. The initial energy of ions formed right above the crucible 4 is regulated to several hundreds from several tens and therefore these ions are greatly deflected by the deflecting magnetic field of 1kV potential difference formed between the electrodes 27a, 27b and inhibited from being passed through an ionizing means. Accordingly, the ions formed right above the crucible 4 can be prevented from being concentrated in the center of a base plate 18 for forming the thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thin film forming apparatus for forming a homogeneous vapor deposited film on a thin film forming substrate.

[Conventional technology]

Figure 3 shows, for example, the 1980s. FIG. 4 is a cross-sectional view showing a conventional thin film forming apparatus disclosed in Publication No. 9592, and FIG. A tank 2 is an exhaust passage for evacuating the inside of the vacuum tank 1, and this is connected to a vacuum exhaust device (not shown). 3 is a vacuum valve that opens and closes the exhaust passage 2; 4 is a closed crucible equipped with a nozzle 26 having a diameter of 1 mm to 21 mI, and a vapor deposition raw material 5, for example, aluminum A↓ is accommodated in this crucible. A heating ficimen 1-1 for heating the crucible 4 is a heat shield plate that blocks radiant heat from the heating filament 6, and the crucible 4, the heating filament 6, and the heat shield plate 7 An evaporation source 8 is configured to eject the evaporation raw material 5 into the vacuum chamber ↓ to generate clusters. Incidentally, reference numeral 3a indicates thermionic electrons emitted from the heating ficimen 1-6, 19 an insulating support member that supports the heat shield plate 7, 20 a support stand that supports the crucible 4, and 25
is an insulating support member that fixes the support base 20 to the vacuum chamber. Further, 9 is an ionizing filament 1-110 that emits thermionic electrons 13b for ionization, an electron extraction electrode that accelerates thermionic electrons 13b emitted from the ionizing filament 9, and 11 is a heat seal 1 that blocks radiant heat from the ionizing filament 9. The ionization filament 9, the electron extraction electrode 10, and the heat shield plate 11 constitute an ionization means 12 for ionizing the clusters from the evaporation source 8. Note that 23 is an insulating support member that supports the heat shield plate 11.

Reference numeral 14 denotes an acceleration electrode as an acceleration means for accelerating the ionized cluster ions 6 and colliding them together with the non-ionized neutral clusters 5 against the thin film forming substrate 18 to deposit a thin film. This has a structure in which a potential can be applied between it and the electron extraction electrode 10. In addition, 24 is an insulating support member that supports the accelerating electrode 14, 22 is a substrate holder that supports the substrate top 8, 21 is an insulating support member that supports the substrate holder 22, and F is an insulating support member that supports the cluster ions 16 and the neutral cluster 15. This is a cluster beam.

Next, the operation will be explained.

To explain the case of vapor depositing an aluminum thin film on the thin film forming substrate 18, first, the vapor deposition raw material 5 made of aluminum is filled into the crucible 4, and the vacuum chamber 1 is brought to a vacuum level of about 10-6 Torr using a vacuum evacuation device. do. Next, the heating filament 6 is energized to generate heat, and thermionic electrons 13a emitted from the heating filament 6 or radiated heat are caused to collide with the crucible 4, that is, the vapor deposition in the crucible 4 is caused by electron impact. Raw material 5 is heated and evaporated. When the crucible 4 is heated to a temperature where the vapor pressure of aluminum becomes O0↓ to several tens of TorrFit degrees, aluminum vapor is ejected from the nozzle 26. At this time, adiabatic expansion occurs due to the pressure difference between the inside of the crucible 4 and the top of the vacuum chamber, and a cluster beam 17 is formed, which is a lumpy atomic group in which a large number of atoms called a cluster are loosely bonded.

This cluster bee 1117 collides with the thermoelectron]-3b extracted from the ionized filament 9 by the electron extraction electrode 10, so one atom of some of the clusters is ionized and becomes cluster ion 1.
It becomes 6. These cluster ions 6 are moderately accelerated by the electric field formed between the accelerating electrode 14 and the electron extraction electrode 10, and the non-ionized neutral clusters 15
The kinetic energy generated when the liquid is ejected from the crucible 4 collides with the thin film forming substrate 18, thereby forming an alumina 11 thin film on the M film forming substrate 18 by vapor deposition.

[Problem to be solved by the invention]

Since the conventional thin film forming apparatus is configured as described above, the electrons that shock-heat the crucible 4 are transmitted through the nozzle 26 of the crucible 4.
Since the nearby area is irradiated, ions are formed directly above the crucible 4, and the ions formed near the central axis of these beams travel almost straight and concentrate at the center of the thin film forming substrate 18, causing the thin film to form. There was a problem that the ion current density distribution in the central part of the formation substrate 18 became extremely large, making it impossible to form a homogeneous thin film over the entire surface of the thin film formation substrate 18. In particular, when using an evaporative substance with a small work function such as barium Ba, even if no electron impact heating is performed and no thermoelectrons are present, it is possible that the evaporation material may come into contact with the inner surface of the crucible 4 heated to a high temperature or the wall surface of the nozzle 26. There was a problem that ions were formed due to the surface ionization phenomenon of the steam, and these ions were concentrated in the center of the thin film forming substrate 18. A thin film forming apparatus in which deflection electrodes 27a and 27b are provided between the accelerator electrode 4 and the thin film forming substrate 18 has been proposed, but in this configuration, ions near the beam center axis cannot be sufficiently deflected. In order to make the ion distribution uniform, large deflection electrodes 27a and 27b and deflection electrode 27 are required.
It is necessary to apply a high voltage comparable to the acceleration charge of the cluster ions to a and 27b, which increases the size of the device and requires the use of a large and expensive deflection control power source. There were issues such as:

This invention was made to solve the above-mentioned problems, and can prevent the ions of the cluster ion beam from locally concentrating, and can form a homogeneous thin film with a uniform ion current density distribution. The object of the present invention is to obtain a thin film forming apparatus that can form a thin film on a substrate.

[Means to solve the problem]

A thin film forming apparatus using a cluster ion beam method according to the present invention is provided with a deflection electrode that forms a deflection electric field between an evaporation source that forms a cluster beam and an ionization means that ionizes the cluster beam. be.

[Effect]

The deflection electrode in this invention deflects ions formed directly above the crucible to prevent ions from concentrating on the center of the thin film forming substrate.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, reference numerals 27a and 27b are deflection electrodes provided directly above the evaporation source 8 so as to sandwich the cluster beam from the nozzle 26. When the impact voltage for heating the crucible in the evaporation source 8 is 1 kV, the deflection electrodes 27a and 27b have
Provides a direct current deflection voltage of several hundred volts or more. In this embodiment, without using a power supply exclusively for deflection, one of the potentials of the heating filament 6 and the other of the potential of the crucible 4 is set to 1 kV.
It applies a deflection voltage of . These deflection electrodes 27a,
A small size 27b is sufficient, and the dimensions of the electrodes are appropriately selected from 10 to 50 nm in width and 1 to 30 nm in height, with a distance between opposing electrodes of 10 to 50 nm.

Further, 41 is a mounting plate for mounting the heating filament 6 via the filament mounting base 30a and the insulating support member 31a, and a heat shield plate 7 is connected to this mounting plate. 42 is an electrode mounting plate with deflection electrodes 27a and 27b attached, 43 is a shield plate, and 44 is an ionizing filament 9.
The ficimen 1 is attached via the mounting base 30b and the insulating support member 31b (J plate, each of these plates is the insulating member 23b.

23 a, 24 c, 24 b, 24 a
Peripheral parts (end parts) are successively interposed between each of the parts, and are attached to the plurality of pillars 32 by poles 1 to 45 passing through them. In addition, these columns 32 are each fixed on the base plate 28 via insulating bosses 25b with screws 46 from Pol I, and the bolts installed on this base plate 28 are attached to the mounting base 29 with screws 47 to Pol 1. A support stand 20 for the crucible 4 is attached via an insulating boss 25a.

Next, the operation will be explained.

Since the initial energy key of the ions formed directly above the crucible 4 is from several tens to several hundred V, these ions are greatly concentrated by the deflection electric field with a voltage difference of LkV formed between the deflection electrodes 27a and 27b. Passage of the ionizing means is prevented. Therefore, the thin film-forming phase of ions formed directly above the pot 4 1. (It is possible to prevent concentration in the center of the plate 18. Although FIG. 1 shows the case where the ionization means 12 with a small opening diameter of the nozzle 26 is used, it is possible to prevent the ionization means 12 with a large opening diameter. When used, although the deflected ions may pass through the ionization means 2, the ions will not be concentrated at the center of the thin film forming substrate 18.Specifically, for example, the deflection electrodes 27a, 27b length] is 1
0mm, the distance d between the electrodes is 25nWI+, the initial energy V of the ions is 500V, and the deflection voltage Vd is 1kV.
Assuming that a uniform deflection electric field is formed only between the deflection electrodes 27a and 27b, the deflection angle O is calculated as shown in the following equation.

tan&=Vd・1/2v−d=0.4,°,
θ=21.8 (degrees) Since the angle at which the cluster ion beam is used is about 15 degrees, the deflected ions do not reach the thin film forming substrate 18.

FIG. 2 shows a thin film forming apparatus according to an embodiment of the present invention, in which the dimensions of deflection electrodes 27a and 27b are 10 m long and 2 m wide.
5+nm and an inter-electrode distance of 25 mm, the results of measuring the ion current density distribution on the thin film forming substrate 18 are shown in comparison with the ion current density distribution obtained by a conventional thin film forming apparatus. Note that FIG. 2 shows the deflection electrodes 27a, 27
In order to determine only the effect of b, the results were measured without operating the ionization means ↓2. According to this, in the case of the conventional thin film forming apparatus that does not use the deflection electrodes 27a and 27b, ions are concentrated in the center of the thin film forming substrate 18, as shown by the distribution indicated by the dashed line in FIG. , the half-value width of the distribution was 51'lWn, but the deflection electrodes 27a, 27
By using b, the half width is 30+ as shown by the solid line.
+m+, the ion content was almost uniform.

In the above embodiment, a conventional power supply is used to set one of the deflection electrodes 27a and 27b at a heating filament potential and the other at a crucible potential, and a dedicated power supply is not used. By providing a power source, the deflection voltage may be made variable to further equalize the ion distribution. Furthermore, by using a low frequency or high frequency power source instead of a DC power source as a deflection power source, the cluster beam scans the thin film forming substrate 18, thereby making the ion current density distribution uniform on the thin film forming substrate 18. At the same time, it is also possible to effectively utilize the ions formed directly above the crucible 4. At this time, the same effect can be achieved even if two or more pairs of deflection electrodes are used.

〔Effect of the invention〕

As described above, according to the present invention, a deflection electrode is provided between the evaporation source that forms a cluster beam and the ionization means that forms cluster ions, and the ions formed directly above the crucible are deflected to form a thin film. Since the structure is configured so that the ion current density is not concentrated in the center of the formation substrate, the ion current density distribution on the thin film formation substrate can be made uniform, and a homogeneous thin film can be formed on the thin film formation substrate. be. In addition, as a power source for the deflection electrode, it is possible to supply power from the impact power source of the evaporation source, and a conventional power source can be used.
Even when using a power supply exclusively for deflection, the deflection potential can be at most 1,000 volts, which has the effect of suppressing the power supply voltage 1 to 1 compared to a thin film forming apparatus equipped with a conventional deflection electrode.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of a thin film forming apparatus according to an embodiment of the present invention, and FIG. 2 is a front view showing a thin film forming apparatus according to an embodiment of the present invention and a thin film forming substrate in a conventional thin film forming apparatus. Figure 3 is a cross-sectional view of a conventional thin film forming apparatus, Figure 4 is a partially cutaway perspective view of the main parts of a conventional thin film forming apparatus, and Figure 5 is a characteristic diagram showing the ion current density distribution at . 1 is a sectional view showing another conventional example of a thin film forming apparatus. 1 is a vacuum chamber, 4 is a crucible, 5 is a deposition raw material, 8 is an evaporation source,
]-2 is an ionization means, 14 is an acceleration electrode, soil 8 is a substrate for forming a thin film, and 27a and 27b are deflection electrodes. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. ]2” JP-A-3 64458 (6) Fig.

Claims (1)

[Claims] A vacuum chamber maintained at a predetermined degree of vacuum and a crucible provided in the vacuum chamber are used to eject the vapor of the vapor deposition raw material to be deposited onto the thin film forming substrate into the vacuum chamber. an evaporation source that generates clusters of loosely bonded atoms, an ionization means that ionizes the clusters, and an ionization means that accelerates the ionized cluster ions to form the thin film together with non-ionized neutral clusters. In a thin film forming apparatus comprising an accelerating electrode for depositing a thin film by bombarding a substrate, a deflection electrode for deflecting ions formed directly above the crucible is provided between the evaporation source and the ionization means. A thin film forming apparatus characterized by: