JPH03177562A - Vaporization source device - Google Patents

Abstract

PURPOSE:To heat the upper part of a crucible with a coil and to prevent the clogging of a small hole for injecting a vaporized material by providing the coil close to the small hole at the upper part of the crucible in a vapor deposition device and connecting the coil and crucible and an electron-bombardment hot cathode for heating the coil to a power source in series. CONSTITUTION:A material 3 to be vapor-deposited is placed into the crucible A made of C or W, the electron-bombardment hot cathode 5 provided around the crucible A is energized by the power source 6 to emit a thermoelectron which heats the crucible A, hence the material 3 is vaporized, and the vapor of the material 3 is injected from the small hole 1 of the upper lid 2 of the crucible A and deposited on a substrate. In this case, the small hole 1 and upper lid 2 are cooled by the adiabatic expansion due to the injection of the vapor from the small hole of the upper lid 2, the vapor of the material 3 is solidified, and the small hole 1 is clogged. Accordingly, a heating filament 4 is arranged close to the small hole 2, connected to the power source 7 in series with the crucible A and heated, and the upper part of the crucible and the small hole 1 are heated by the heat. As a result, the material is not solidified in the small hole, and the vapor deposition is not stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in evaporation source devices used in vacuum evaporation, cluster ion beam evaporation, and the like.

2. Description of the Related Art Conventionally, a deposition source device used for vacuum evaporation, cluster ion beam evaporation, etc., in which a solid substance is heated and evaporated at room temperature and deposited on a deposition substrate to form a thin film, has a configuration as shown in FIG. That is, a cylindrical crucible (Knudsen cell) 23 with a small hole 21 formed in the center of the upper part 122;
The hot cathode 5 for electron bombardment is installed outside the crucible 23 parallel to the side circumferential surface of the crucible 23 to heat this side circumferential surface.

The crucible 23 generally has a single-layer structure made of carbon, tungsten, or the like. The hot cathode 5 for electron bombardment is formed by forming a homogeneous wire material such as tungsten or tantalum with a uniform cross-sectional area into a coil shape, and the helical pitch is constant. 6 is a hot cathode heating power source for applying a voltage to the hot cathode 5 and heating it; 24 is a hot cathode heating power source for applying a voltage between the crucible 23 and the hot cathode 5 to extract thermoelectrons from the hot cathode 5 heated to a high temperature; , is a crucible heating power source for heating the crucible 23 by electron bombardment by colliding the thermoelectrons with the crucible 23.

The film forming process using the evaporation source device is as follows.

After accommodating the vapor deposition material 3 inside the crucible 23, a vacuum chamber (not shown) in which the crucible 23 was installed is set to a predetermined degree of vacuum,
The crucible 23 is heated by electron bombardment to evaporate the deposition material 3. The vapor 25 of the vapor deposition material 3 is ejected from the small hole 21 in the direction of the arrow in the figure due to the pressure difference between the vacuum chamber and the crucible, and at this time it expands adiabatically and is supercooled. Therefore, the vapor 25 is condensed and becomes a beam of a lumpy atomic group in which 500 to 2000 atoms are loosely bonded to each other, that is, a cluster beam, which collides with a substrate (not shown) to form a deposited film.

Problems to be Solved by the Invention As mentioned above, the hot cathode coil 5 for electron bombardment, which is installed outside the crucible 23 in parallel with the side circumferential surface of the crucible 23, has a uniform wire diameter and a uniform wire. It is formed into a coil shape with a helical pitch, and the conventional evaporation source device heats the side surface of the crucible 23 with a uniform heat flux using the hot cathode 5 for electron bombardment.

Therefore, the upper part of the crucible 23 receives the same heat input as the central part.

However, since the cylindrical crucible 23 has a circular upper surface portion (crucible lid 22), the amount of heat dissipated from the upper portion is larger than from the central portion of the crucible.

Therefore, a temperature distribution occurs along the axial direction of the crucible 23, with the temperature being high at the center of the crucible and decreasing at the upper part including the crucible 122. For this reason, (1) the temperature near the small hole in the upper surface of the crucible decreases, the vapor of the vapor deposition material condenses near the small hole, and a spitting state in which the condensed liquid is spouted out in the form of droplets tends to occur. As a result, the quality of the deposited film becomes poor and the small pores become clogged.

(2) The temperature of the evaporation material changes depending on the amount of evaporation material accommodated in the crucible, that is, the filling height of the evaporation material, and the evaporation rate is not uniform and the evaporation rate also changes. Therefore, the stability of vapor deposition is poor.

There were problems such as.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an evaporation source device that can stably produce a high-quality vapor deposited film by uniformizing the temperature distribution along the axial direction of a crucible. The purpose is to

Means for Solving the Problems An evaporation source device according to the present invention includes a crucible that accommodates a substance to be evaporated, a hot cathode for electron bombardment for heating the side circumferential surface of the crucible, and a small hole in the upper lid of the crucible. In the evaporation source device having a heating filament arranged in electrical series with the crucible, the heating filament is provided close to the small hole in the upper lid.The effects obtained by the above-described configuration are as follows.

When an anode (corresponding to a crucible) at a positive potential is placed against a hot cathode heated to a high temperature in a vacuum, thermionic electrons extracted from the hot cathode collide with the crucible, and the crucible is heated by electron bombardment. . If a heating filament is provided close to the small hole formed in the upper lid of the crucible, and the heating filament is electrically arranged in series with the crucible, the industrial current due to thermionic electrons will flow through the heating filament. Become,
The heating filament becomes hot. The small hole formed in the upper lid of the crucible is heated by thermal radiation from this heating filament.

From the above, the temperature drop in the small hole where the steam inside the crucible ejects while expanding adiabatically is compensated for, and the temperature distribution in the crucible becomes uniform in the axial direction. As a result, a spitting state is less likely to occur, making it possible to form a high-quality film. In addition, small pores are not blocked, and stable film formation becomes possible.

EXAMPLES The evaporation source device of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a power source device according to one embodiment of the present invention. A is a crucible (Knudsen cell) made of carbon and having a single layer structure in which small holes 1.1 with a diameter of about 1 mm are formed at two locations on the upper M2, and the vapor deposition material 3 is housed inside this crucible A.

In this embodiment, a small hole heating filament 4 as a heating filament is inserted into the crucible A through one small hole 1 and pulled out from the crucible A through the other small hole 1. Note that the filament 4 for heating near the small hole is attached to the upper lid 2.
Hold it so that it does not come into contact with it. The filament 4 for heating near the small hole is made of a homogeneous tungsten wire with a wire diameter of 0.08 mm. Then, the filament 4 for heating near the small hole is electrically arranged in series with the crucible A,
The structure is such that an emission current due to thermionic electrons colliding with the crucible A flows through the heating filament 4 near the small hole.

For example, when an industrial tension current of about iA flows through the filament 4 for heating near the small hole, the temperature of the filament 4 for heating near the small hole becomes about 2200°C.

5 is a hot cathode for electron bombardment for heating the crucible A. The wire diameter of the hot cathode 5 for electron bombardment is 0.7~
Tungsten wires or tantalum wires with varying wire diameters in the range of 1.0 mm are formed into coils with varying helical diameters, and the length of the coil is longer than the length to the crucible.

Since the wire diameter is -like, the temperature of the hot cathode 5 is constant in its length direction. Two hot cathodes 5 are electrically connected in series and placed parallel to the central axis of the cylindrical crucible A on the outside of the crucible.

Note that the heat input to the crucible A can be easily increased by increasing the number of hot cathodes 5 connected in series.

6 is a hot cathode heating power source for applying a voltage to the hot cathode 5 and heating it; 7 is a hot cathode heating power source for applying a voltage between the crucible A and the hot cathode 5 to emit thermoelectrons from the hot cathode 5 heated to a high temperature; drawer,
This is a crucible heating power source for heating the crucible A by electron bombardment by colliding the thermoelectrons with the crucible A. Further, due to this crucible heating power source 7, an emission current due to thermoelectrons flows through the filament 4 for heating near the small hole, and the filament 4 for heating near the small hole becomes high temperature. Further, 8 is a support stand that supports the crucible A, and 9 is an insulating support member that fixes the support stand 8 to a vacuum chamber (not shown).

As mentioned above, since the small hole heating filament 4 inserted into the small hole 1.1 formed in the upper lid 2 of the crucible A becomes high temperature, the heat radiation from the small hole heating filament 4 causes The vicinity of the small hole 1 and (2) formed in the upper M2 of the crucible A is heated.

From the above, the temperature drop in the first part of the small hole where the steam inside the crucible A blows out while expanding adiabatically is compensated for, and the temperature distribution in the crucible A becomes uniform in the axial direction. As a result, a spitting state is less likely to occur, making it possible to form a high-quality film. Further, the small holes 1 are not blocked, and stable film formation becomes possible.

Furthermore, according to this embodiment, a separate power source is not required compared to a case where a heater or a hot cathode for heating the surface of the crucible and a dedicated power source are provided near the top surface of the crucible. It is possible to provide a compact evaporation source device with a simple configuration.

In the above example, a hot cathode for electron bombardment was shown in which a wire material such as tungsten or tantalum was formed into a coil shape with a spiral diameter of -. It can also be used in the case of a hot cathode for electron bombardment formed into a shape.

FIG. 2 shows an evaporation source device according to another embodiment of the present invention. B is a crucible (Knudsen cell) made of carbon and having a single layer structure in which a small hole 10 with a diameter of about 2 mm is formed in the center of the upper IEII, and the vapor deposition material 3 is housed inside this crucible B. In this embodiment, a filament 12 for heating the upper surface of the crucible is provided above the small hole 10 of the crucible B as a heating filament. Note that the filament 12 for heating the upper surface of the crucible is held so as not to come into contact with the upper M11. In addition, the filament 12 for heating the top surface of the crucible has a wire diameter of 0.081TI11.
A homogeneous tungsten wire rod is formed into a coil shape. The filament 12 for heating the crucible top surface is electrically arranged in series with the crucible B, and an emissive current caused by thermionic electrons colliding with the crucible B flows through the filament 12 for heating the crucible top surface.

With the above configuration, the filament 12 for heating the crucible top surface provided above the small hole 10 of the crucible B becomes high temperature, and the entire surface of the top lid 11 of the crucible B is heated by radiation from the filament 12 for heating the crucible top surface.

From the above, the temperature drop in the small hole where the steam inside the crucible B blows out while expanding adiabatically is compensated for. As a result, the spitting state is less likely to occur, and the small holes 10 are also prevented from being blocked, making it possible to form a high-quality and stable film.

Effects of the Invention As described above, the evaporation source device according to the present invention includes a crucible that accommodates a substance to be evaporated, a hot cathode for electron bombardment for heating the side peripheral surface of the crucible, and a small hole in the upper lid of the crucible. This evaporation source device has a heating filament arranged in electrical series with the crucible at a position that heats the small hole in the top lid, so there is no need for a separate heating power source.
Moreover, the spitting state is less likely to occur, making it possible to produce a stable vapor deposited film of high quality.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an evaporation source device according to an embodiment of the present invention, and FIG.
The figure is an explanatory diagram of an evaporation source device according to another embodiment of the present invention, and FIG. 3 is an explanatory diagram of a conventional evaporation source device. A, B-・--・-Crucible 1, lO-・--・Small hole 2.11--Top lid

Claims (3)

[Claims] (1) An evaporation source device comprising a crucible containing a substance to be evaporated and a hot cathode for electron bombardment for heating a side peripheral surface of the crucible, and having a small hole in the upper lid of the crucible,
An evaporation source device with a heating filament arranged in electrical series with the crucible at a position that heats a small hole in the top lid. (2) The evaporation source device according to claim 1, wherein the heating filament is a filament for heating near the small hole, which is inserted through the small hole and provided in a U-shape through the upper lid. (3) The evaporation source device according to claim 1, wherein the heating filament is a crucible upper surface heating filament disposed above the small hole of the crucible.