JPH0361360A - Thin film forming device - Google Patents

Abstract

PURPOSE:To obtain the thin film forming device capable of reducing the radiant heat from a filament and capable of forming a thin film at low temp. by forming at least one of a vapor-deposition material heating filament and an ionization filament with a material for radiating an electron having a higher current density at low temp. than that from a W wire. CONSTITUTION:The heating filament 21 for heating a crucible 4 by electron impact and vaporizing the vapor-deposition material 5 is provided around the crucible 4. Meanwhile, the ionization filament 22 for radiating an electron to ionize a part of the vaporized material 5 is furnished above the crucible 4. The filaments 21 and 22 are formed respectively with a W/Ba wire obtained by applying Ba on the surface of an electron radiating wire such as a W wire and heating the coating to cause mutual diffusion. The W/Ba wire radiates an electron having a higher current density at low temp. than that from a W wire. Accordingly, the radiant heat from the filaments 21 and 22 is reduced, a thin film is formed at low temp., and further the temp. of a substrate is easily controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film forming apparatus, for example, an RI film forming apparatus such as a cluster ion beam evaporation apparatus.

[Prior Art] FIG. 2 is a block diagram showing a conventional cluster ion beam evaporation apparatus disclosed, for example, in Japanese Patent Publication No. 54-9592.

In the figure, symbol (1) is a vacuum chamber, and (2) is a vacuum chamber (1
This is a substrate as a material to be evaporated, on which a evaporated thin film (3) is formed.

(4> is a crucible made of a conductive material, which is provided in the vacuum chamber (1), and this crucible (4) is provided with a nozzle hole (4a). (5) is a vapor deposition material contained in the crucible (4), (6> is a heating filament provided around the crucible (4) and heats the crucible (4) by electron impact; By heating the filament (6), the deposition substance (5>) is evaporated and ejected from the nozzle hole (4a).The heating filament (6) is made of a tungsten wire.

(7) is provided above the crucible (4), and the vapor deposition material (5)
This is an ionization filament that emits electrons to ionize a part of the ionization filament (7) into a positive charge by electron collision, and the ionization filament (7) is made of tungsten wire. This is a grid that accelerates the emitted electrons and causes them to collide with the ejected deposition material (5).

(9) is an accelerating electrode for accelerating the ionized deposition material (5) with an electric field, (io) is a heating filament (6)
), and this heat shield plate (10) is kept at the same potential as the heating filament (6).

(11> is the first AC power supply for emitting electrons to the heating filament (6), and (12) is the heating filament (6>) that connects the crucible so that the electrons emitted from the crucible collide with the crucible (4). 4〉, a first DC power source for keeping the accelerating filament (6〉) at a negative potential, and (13) a second DC power source for making the ionization filament (7) emit electrons.
(14) is a second DC power source for keeping the ionization filament (7) at a negative potential with respect to the grid (8), (15) is the accelerating electrode (9) with respect to the grid (8). ) is a third DC power supply for keeping the voltage at a negative potential.

Next, the operation will be explained. Heating filament (6
The electrons emitted from the crucible (4) collide with the crucible (4) at a positive potential, thereby heating the crucible (4) and the vapor deposition material (5) inside the crucible (4).

The heated vapor deposition substance (5) evaporates into the nozzle hole (4a).
) to erupt from. The ejected vapor deposition material (5) becomes supersaturated due to supercooling due to temporary expansion near the nozzle hole (4a), and condenses to form clusters.

After this, a part of the vapor deposited material (5) that has become a cluster is positively ionized by electrons from the ionization filament (7>.The cluster of this vapor deposited material (5>) is then transferred to the accelerating electrode (9). It is accelerated by the electric field of and impinges on the surface of the substrate 2), thereby forming a deposited thin film (3).

[Problems to be Solved by the Invention] In the conventional cluster ion beam evaporation apparatus configured as described above, the heating and ionization filament 1
- Since (6) and (7) are made of tungsten wire, when emitting electrons, each of these filaments (6)
) and (7) reach a considerably high temperature, and the radiant heat heats the substrate (2). For this reason, for example, a substrate (2) made of a plastic film 18 or an organic material, etc.
When using this method, there were problems such as deformation of the substrate (2), which made it difficult to form a thin film, and a separate device for cooling the substrate (2) was required. In addition, except for those made of the above-mentioned materials, - in general, the substrate (2)
Since the vaporized S thin film (3) is more firmly formed at a higher temperature, some devices have a means to keep the substrate (2) at a certain temperature;
There is a problem in that it becomes difficult to adjust the temperature of the substrate 2) due to the influence of radiant heat from 6) and (7), and there is a problem that the above problems must be solved. Ta.

This invention was made in order to solve the above-mentioned problems, and it is a thin film that reduces radiant heat from the filament, enables thin film formation at low temperatures, and facilitates temperature adjustment of the substrate. [Means for Solving the Problems] A thin film forming apparatus according to the present invention is characterized in that at least one of the heating filament and the ionizing filament is made of a wire that emits electrons at a higher current density at a lower temperature than a tungsten wire. It is something that

[Function] In the present invention, radiant heat from the filament is reduced by using a filament made of a wire that emits electrons with a higher current density at a lower temperature than a tungsten wire.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a cluster ion bee 11 vapor deposition apparatus which is an embodiment of the present invention, and the same or equivalent parts as in FIG. 2 are given the same reference numerals and their explanations will be omitted.

In the figure, reference numeral (21) is provided around the crucible (4), and the crucible (4) is heated by electron bombardment, and vaporization (22) is provided above the crucible (4), and the evaporated deposition material (5) is placed above the crucible (4). This is an ionization filament that emits electrons to ionize a part of the heating and ionization filler (21).

(22) is a W/B a made by coating barium on the surface of a tungsten wire and heating it to cause mutual diffusion.
Each is made of wire.

Here, the W/Ba wire as described above and the conventional tungsten wire are each 0.1 A/c.
When obtaining the electron emission current density of x'', the respective temperatures are as follows.

Tungsten wire...T, = 2400 KW/
Batij material...T2-1100 at this time,
The relationship among the energy E of radiant heat transferred to the substrate (2), the emissivity ε, and the filament temperature T is expressed by the following equation.

ECCε·T4 Assuming that ε in the formula is the same for the above two types of materials, the following formula is obtained.

However, E is the radiant heat transfer energy when a tungsten wire is used, and E2 is the radiant heat transfer energy when a W/Ba wire is used.

Therefore, the energy transferred by the radiant heat by the heating and ionizing filaments (21) and (22) in this embodiment is 1/23 that of the conventional example, which is greatly reduced.

Therefore, it is possible to form a thin film at a low temperature, and even on the substrate (2) which is susceptible to aging, the thin film can be formed without using a cooling device. Furthermore, even when forming a thin film by heating the substrate (2), the influence of radiant heat is reduced, making it easier to control the temperature of the substrate (2).

In the above example, W is made by heating the tungsten wire 0 surface coated with barium to cause interdiffusion.
Although the W/Ba wire was used, the W/Ba wire may be made by mixing several percent of barium into tungsten and then forming the mixture into a wire.

In addition, in the above example, W/Ba wire was used as the material for the heating and ionizing filaments (21) and (22), but it is also possible to use a wire that emits electrons at a higher current density at a lower temperature than a tungsten wire. If there is, it may be something else.

For example, as shown in R Vacuum Handbook J, 1982 edition, pages 136 to 139, published by Japan Vacuum Technology Co., Ltd., W/C manufactured in the same way as W/Ba wire
Even if it is S wire, W/Th wire, Ta/Th wire, LaB5 wire, etc., the work function ψ is lower than that of tungsten wire, and it is easier to emit thermoelectrons, so radiant heat can be reduced to low temperature. It is possible to suppress the amount of heat electrons and emit sufficient thermoelectrons.

Further, in the above embodiment, the present invention was applied to both the heating filament (21) and the ionizing filament (22), but it may be applied to either one of them.

Furthermore, although the above embodiment shows a cluster ion beam evaporation apparatus having both heating and ionization filaments (21) and (22), the present invention is applicable to a cluster ion beam evaporation apparatus having either one of them. .

In addition, although a cluster ion beam evaporation apparatus is shown as a thin film forming apparatus in the above embodiment, other thin film forming apparatus such as a vacuum evaporation apparatus may be used as long as it has at least one of heating and ionizing filaments. There may be.

[Effects of the Invention] As explained above, the thin film forming apparatus according to the invention includes a wire that emits electrons at a lower temperature and higher current density than a tungsten wire in at least one of the heating filament and the ionization filament. Since a filament is used, radiant heat from the filament is reduced, making it possible to form a thin film at a low temperature, and also making it possible to easily adjust the temperature of the substrate.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. In the figure, (5) is a vapor deposition material, (21) is a heating filament, and (22) is an ion substitute filament. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In a thin film forming apparatus having at least one of a heating filament for heating and evaporating a deposition material and an ionization filament for ionizing the deposition material, at least one of the heating filament and the ionization filament is , a thin film forming apparatus comprising a wire that emits electrons with a higher current density at a lower temperature than a tungsten wire.