JP2994591B2 - Evaporation method and apparatus for vacuum deposition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to evaporation for vacuum deposition, in which atoms or molecular beams generated by melting and sublimating or sublimating by heating are adhered to the surface of a substrate such as a semiconductor wafer disposed inside a vacuum chamber. Regarding methods and apparatus,
In particular, the present invention relates to an evaporation method and apparatus for vacuum evaporation for evaporating a plurality of materials.

[0002]

2. Description of the Related Art In vacuum deposition, an evaporation material disposed in a vacuum chamber is melted and evaporated or sublimated by heating to generate atomic or molecular beams. Separately, a semiconductor wafer or the like disposed in a vacuum chamber is disposed. A thin film is formed by cohesion on a substrate. Conventionally, as a means for evaporating the evaporating material necessary for forming such a thin film, a resistance heating method and an electron impact heating method are known. The resistance heating method is a method in which heat generated by an electric resistor is added to an evaporation source by radiation or heat conduction and heating is performed, and the heating source has a higher temperature than a thin film material. For this reason,
In some cases, impurities are mixed into the thin film material to be heated and evaporated, and the heating source reacts with the thin film material. In addition, there are restrictions due to the melting point of the heating source material.

On the other hand, the electron impact heating method is a method in which thermionic electrons generated by a hot cathode filament are accelerated so as to collide with an evaporating material for heating. As the evaporation source by such an electron impact heating method, the evaporation material is stored in a crucible, and the thermoelectrons generated by the hot cathode filament are electromagnetically induced in the evaporation material, accelerated by applying an accelerating voltage, and collided. Are the most common. Also, as another evaporation source,
There is also a method in which a thermoelectron generated from a hot cathode filament collides with the tip of a rod-shaped evaporation material, and the tip of the rod-shaped evaporation material is dissolved and evaporated by electron impact.

In recent thin film forming techniques, a compound semiconductor thin film or an alloy magnetic thin film that causes a plurality of different evaporation materials to evaporate at the same time to cause a chemical reaction or alloying on a deposition substrate has attracted attention. For example, a silicide iron compound, which is a binary substance of many non-rare substances found on the earth (for example,
β-FeSi 2) is considered promising as a semiconductor material for solar cells in the future. However, in order to form such a thin film made of a binary material, a plurality of evaporation sources must be arranged in the same vacuum chamber, and there is a problem that the apparatus becomes large.

In order to solve such a problem,
The present inventors wrapped a plate-shaped or linear iron around a silicon rod-shaped member, thereby forming an evaporation source composed of a plurality of evaporation materials of silicon and iron, and a plurality of evaporation materials at the tip of the rod-shaped evaporation material. An evaporator has already been proposed in which a thermoelectron generated by a hot cathode filament collides with a junction of the above, and the two impact materials are simultaneously melted and evaporated by the electron impact to generate a molecular beam.

[0006]

However, the means for evaporating a plurality of materials using the rod-shaped or plate-shaped evaporation source is replaced with beta iron silicide (β) which is one of the compound semiconductors.
When applied to the formation of a thin film of -FeSi2), the following problems were found to occur. That is, 2m in diameter
When a 0.15 mm thick iron plate is wrapped around a silicon rod (iron: silicon = 1: 2), this is placed in a vacuum, and its tip is heated and melted by electron impact. The temperature is much lower than the melting point of iron (1535 ° C.) and silicon (1414 ° C.)
Will dissolve. This is due to a physical phenomenon in which the melting point of the mixture drops due to the extremely high chemical activity of silicon at high temperatures. For this reason, when the rod-shaped droplet portion at the tip of iron and silicon is subjected to electron impact heating to a high temperature of 1600 to 1700 ° C., which is the vapor pressure temperature required for vapor deposition, the liquid droplet portion at the tip generated by melting of the evaporation material The temperature at the base of the base is also over a thousand hundred degrees Celsius. As a result, the solid portion dissolves more and more, the iron and silicon rods become shorter, and a molten ball at the tip grows, resulting in a large change in the evaporation rate.

In view of the above, the present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to evaporate a plurality of evaporation materials in a vacuum such as in a vacuum evaporation apparatus. It is an object of the present invention to provide an evaporation method and an evaporation apparatus for vacuum evaporation which can prevent the growth of a molten portion due to a physical phenomenon such as a decrease in melting point in a mixed mixture and can stably control an evaporation rate.

[0008]

Means for Solving the Problems The present inventor separately prepared a plurality of the above-mentioned iron rods and silicon rods as evaporation materials, and melted the tips of these rods by electron impact heating as described above. It was experimentally confirmed that the phenomenon that the melted beads grew rapidly did not occur at all. this is,
Even if the two kinds of evaporating materials are at a high temperature, if they do not come into contact with each other, the physical phenomenon of the melting point drop does not occur, and it is possible to suppress the growth of liquid droplets generated by dissolving a plurality of evaporating materials. It suggests that. The present invention has been made based on such attention by the inventor of the present invention, and a plurality of evaporating materials 200 and 300 are brought into contact only at a tip portion where the evaporating materials 200 and 300 melt and evaporate by electron impact, and at other portions, the evaporating materials 200 and 300 are Were not in contact with each other.

That is, the evaporation method for vacuum evaporation according to the present invention comprises a plurality of rod-shaped or plate-shaped different evaporation materials 200,
The plurality of different evaporating materials 200, 30 are arranged by disposing the evaporating materials 200, 300 such that their tips are substantially in contact with each other, and heating the contact portions of the evaporating materials 200, 300.
It is characterized by generating zero atom or molecular beam. The plurality of rod-shaped or plate-shaped different evaporation materials 200 and 300 are arranged in parallel or in a V shape. Then, the plurality of rod-shaped or plate-shaped different evaporation materials 200 and 300 come into contact with each other and are fed toward their front ends to be heated.

Further, the evaporating apparatus for vacuum vapor deposition according to the present invention comprises a plurality of rod-shaped or plate-shaped different evaporation materials 200, 3
00 are arranged in parallel or in a V-shape,
Heating means for heating the tips of the evaporating materials 200 and 300 are arranged so that their tips are almost in contact with each other, whereby a plurality of rod-shaped or plate-shaped tips of the different evaporating materials 200 and 300 are provided. It is characterized in that the part is heated to generate atomic or molecular beams of a plurality of different evaporation materials 200, 300. The heating means includes a hot cathode filament 25 that emits thermoelectrons toward the tips of the evaporation materials 200 and 300. The hot cathode filament is surrounded by a shield electrode 26.
Further, a monitoring means 27 for monitoring the intensity of generation of the electron beam and the molecular beam generated from the tips of the evaporation materials 200 and 300 is provided.

[0011] Such a plurality of evaporation materials 200, 300
In the method and apparatus for evaporating, a plurality of evaporating materials 200, 300
Are contacted only at the tip portion where they melt and evaporate due to the electron impact, and the evaporating materials 200 and 300 are not in contact with each other in other portions.
Even at high temperatures, the above-mentioned physical phenomenon of the melting point drop does not occur in portions other than the tip portions where they do not contact each other. Therefore, it is possible to suppress the growth of the liquid droplet generated by dissolving the plurality of evaporation materials 200 and 300.

Then, by feeding a plurality of rod-shaped or plate-shaped different evaporating materials 200, 300 toward their tips to be brought into contact with each other and heated, the plurality of evaporating materials 200, 300 are substantially It is possible to evaporate over the entire length. Further, since the periphery of the hot cathode filament is surrounded by the shield electrode, it is possible to prevent thermions, reflected electrons, or generated molecular beams from radiating around.
Further, by providing a monitoring means 27 for monitoring the intensity of generation of electron beams and molecular beams generated from the tips of the evaporation materials 200 and 300, the state of thermoelectrons, reflected electrons or generated molecular beams can be constantly monitored. Can be.

[0013]

Embodiments of the present invention will now be described specifically and in detail with reference to the drawings.
In FIG. 3, the evaporation material disposed inside the vacuum chamber is melted and evaporated or sublimated by heating to generate atomic or molecular beams, and the thin film is deposited on a substrate 100 such as a semiconductor wafer disposed inside the vacuum chamber. Is formed, that is, a part of a film forming apparatus. In this film forming apparatus, a vacuum chamber 1 is provided with an evaporator 2 for generating an atomic or molecular beam, and a substrate holder 3 having a built-in heater disposed below the evaporator 2, on which a substrate 100 is held. ing.

Here, a plurality of different evaporation materials 20 are used.
Since 0 and 300 are simultaneously evaporated to cause a chemical reaction on the substrate 100 to form a compound semiconductor thin film, beta iron silicide (β- An example in which FeSi2) is formed by vapor deposition will be described. By evaporating other evaporating materials,
It goes without saying that a compound thin film can be formed on a substrate in the same manner as described below.

FIG. 1 shows an evaporation apparatus as one embodiment for carrying out the evaporation method for vacuum evaporation according to the present invention. For example, two through holes 23, 23 are formed in a bottom wall 22 of a copper conduction cooling body 21 having a substantially cylindrical outer shape, and these through holes 23, 23 are made of a first rod made of a silicon rod which is two kinds of rod-shaped evaporation materials. And the second evaporating material 300 made of an iron rod are arranged to penetrate. These evaporating materials 200 and 300 are sent out into an evaporating space 24 formed at the lower end of the conduction cooling body 21 by an unillustrated sending mechanism (each independent).

In the evaporating space 24, for example, as shown in FIG. 2, a hot cathode filament 25, which is an electron source for electron impact heating, is disposed so as to surround the two types of evaporating materials 200 and 300. . Although not shown, the hot cathode filament 25 is held around the lower ends of the first evaporative material 200 and the second evaporative material 300 by an electrode implanted in a part of the conduction cooling body 21. A heating current is supplied via a lead wire extended from the heater. Further, as shown in FIG. 1, the first evaporating material 200 and the second evaporating material 300 are arranged close to each other and substantially parallel to each other so that their lower ends are almost in contact with each other. Be placed. Alternatively, as shown in FIG. 4, the first evaporating material 200 and the second evaporating material 300 are arranged in a V-shape, and their tips are brought into contact.

As shown in FIG. 1, a first evaporating material 100 and a second evaporating material 2
00 and the shield electrode 26 so as to surround them except under the hot cathode filament 25 around the tip of the
Is provided. The first evaporating material 200 and the second evaporating material 300
A molecular beam intensity monitoring electrode in the form of a mesh for monitoring the generation intensity of atoms or molecules (for example, beta iron silicide molecules) generated by melting and mixing of the tips of the particles to cause a chemical reaction and evaporation or sublimation. 27 are provided.

In such an evaporator, first, a filament heating power supply (not shown), which is a heating power supply for the hot cathode filament 25, is adjusted, and the shield electrode 26 is heated by the hot cathode filament 25, and the gas is discharged. Do. next,
By switching a switch (not shown), the substrate holder 3
Then, the substrate 100 is heated by a heater, and necessary operations such as degassing are performed. Thereafter, a plurality of evaporation materials 20
The thermoelectrons generated from the hot cathode filament 25 are accelerated and collided with the tips of the hot cathode filaments 0 and 300, and the tips of the evaporation materials 200 and 300 are melted and evaporated or sublimated by the electron impact heating, so that these atoms or Generate a molecular beam. Then, these atomic beams and molecular beams are deposited on the surface of the substrate 100 disposed below the evaporating section 2 in the vacuum chamber 1 of the film forming apparatus.

At this time, the tips of the first evaporating material 200 and the second evaporating material 300 are heated and melted by the impact of the electron beams e and e from the hot cathode filament 25, but their lower ends are close to each other. As a result, the melted portions at the lower ends thereof fuse with each other to form a dot-shaped melted portion 400. In this case, the molten silicon and the iron mix or react with each other at the contact portion of the molten portion 400,
It sublimates to generate a molecular beam 500 of beta iron silicide (β-FeSi 2) (indicated by an arrow in the figure). However, the molten portion 400 does not grow due to the above-described melting point lowering phenomenon. Therefore, a plurality of deposition substances can be stably evaporated downward and supplied from the molten portion 400. For example, the molecular beam intensity monitor electrode 27
By controlling the supply current to the hot cathode filament 25 while monitoring the supply molecular weight, a plurality of evaporated molecular beams can be controlled stably, and a plurality of elements can be deposited on the surface of the substrate 100. .

When evaporating the evaporating materials 200 and 300, the feeding speed of the evaporating materials 200 and 300 is adjusted independently of each other, or the thickness of the evaporating materials 200 and 300 is varied. , Its mixing ratio can be adjusted. When three or more evaporating materials are further mixed, a coaxial composite material in which another evaporating material in the form of a plate or a line is wound around one of the two rod-shaped evaporating materials 200 and 300 is used. Can also. However, in this case, it is preferable to select and use materials that do not cause a melting point lowering phenomenon. Of course, three or more types of evaporating materials may be arranged in parallel or in a V-shape, and their tips may be brought into contact.

In the above-described embodiment, the plurality of evaporating materials 200 and 300 are illustrated as rods. However, the evaporating materials 200 and 300 are not limited to such rods. Instead, for example, as shown in FIG. 5, a plurality of evaporating materials 200 ′ and 300 ′ may be formed in a plate shape. Then, these are evaporated materials 200 ′, 300 ′.
Are disposed substantially parallel to each other, and are disposed so that the lower ends thereof are substantially in contact with each other, or the evaporating materials 200 ′ and 300 ′ are abutted in a V-shape to bring the lower ends into contact. You may do so. In this case, since the plurality of melted portions 400 ′ are spread linearly in parallel, nonuniformity of the deposited film, particularly in the lateral direction, is eliminated, and a plurality of materials can be uniformly deposited.

Also in the above-described embodiment, the feeding speed of the evaporating materials 200 'and 300' is adjusted independently of each other, or the thickness of the evaporating materials 200 'and 300' is different. By doing so, the mixing ratio can be adjusted. Further, when mixing three or more types, one of the two plates is
A multilayer board to which a plurality of materials are attached may be used. Also in this case, it is preferable to select a material that does not cause a melting point decrease phenomenon for the multilayer plate. Of course 3
More than one type of evaporating material may be arranged in a parallel or V-shape, and their tips may be in contact.

[0023]

As is apparent from the above description, according to the present invention, in evaporating a plurality of evaporating materials in a vacuum such as in a vacuum evaporation apparatus, the melting portion of the mixture due to physical phenomena such as melting point drop is reduced. Growth can be suppressed and the evaporation rate can be controlled stably.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of an evaporation apparatus for vacuum deposition according to one embodiment of the present invention.

FIG. 2 is a partially enlarged view for explaining a partially detailed structure of the evaporator.

FIG. 3 is a side view of a film forming apparatus provided with a vacuum evaporation apparatus of the present invention inside.

FIG. 4 is an explanatory diagram illustrating a plurality of evaporations in the multiple evaporation device of the present invention.

FIG. 5 is an explanatory diagram illustrating a plurality of evaporations in a plate-shaped multiple evaporation device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Evaporation part 3 Substrate holder 21 Conduction cooler 24 Evaporation space 25 Hot cathode filament 26 Shield electrode 27 Molecular beam intensity monitor electrode 100 Substrate 200 First evaporation material 200 'First evaporation material 300 Second evaporation Material 300 'Second evaporation material 400 Melted part at the tip of evaporation material

Claims (6)

(57) [Claims] A plurality of different evaporating materials (200), (3)
00) is heated and melted or sublimated in a vacuum chamber, and the evaporation materials (200), (3)
In the evaporation method for vacuum deposition in which the atomic or molecular beam of (00) is adhered onto the surface of the substrate (100) arranged inside the vacuum chamber, a plurality of rod-shaped or plate-shaped different evaporation materials (200), (300) Are parallel to each other or V
And the evaporating materials (200), (30) are arranged such that their tips are almost in contact with each other.
An evaporation method for vacuum evaporation, wherein the contact portion of (0) is heated to generate atoms or molecular beams of the plurality of different evaporation materials (200) and (300). 2. A plurality of rod-like or plate-like different evaporation material (200), (300), according to claim 1, characterized in that given the feed towards their tip in contact with each other, are heated 4. The evaporation method for vacuum deposition according to 1. 3. A plurality of different evaporative materials (200), (3)
00) is heated and melted or sublimated in a vacuum chamber, and the evaporation materials (200), (3)
A plurality of rod-shaped or plate-shaped different evaporating materials (200), (300) in an evaporating apparatus for vacuum evaporation for adhering the atomic or molecular beam of (00) on the surface of a substrate (100) arranged in a vacuum chamber. Are parallel to each other or V
And the evaporating materials (200), (30) are arranged such that their tips are almost in contact with each other.
A heating means for heating the tip portion of (0) is provided, whereby a plurality of rod-shaped or plate-shaped different evaporation materials (20) are provided.
0) An evaporating apparatus for vacuum evaporation characterized in that the tip of (300) is heated to generate atoms or molecular beams of a plurality of different evaporation materials (200) and (300). 4. The heating means (20)
4. The evaporating apparatus for vacuum evaporation according to claim 3 , comprising a hot cathode filament (25) for emitting thermoelectrons toward the contacted end of (0), (300). 5. A so as to surround the periphery of the hot cathode filament (25), for vacuum evaporation evaporator according to claim 3 or 4, characterized in that a shield electrode (26). 6. A monitor means for monitoring the intensity of generation of electron beams and molecular beams generated from the tips of the evaporation materials (200) and (300).
The evaporating apparatus for vacuum deposition according to any one of claims 3 to 5 .