JPH059715A - Ion beam vapor deposition device - Google Patents

Abstract

PURPOSE:To form a vapor deposited film having extremely high purity on a substrate with good efficiency of the vapor deposition by separating and removing the gaseous raw materials incorporated into the gas ionized by a mass separator provided in the ion beam vapor deposition device. CONSTITUTION:The gaseous raw materials are introduced from an introducing port 1 into an ionizing chamber 2 and are ionized by a plasma discharge, etc. The ions are accelerated by an acceleration electrode 4 in an acceleration electrode chamber 3 and are passed as an ion beam 5 into an acceleration tube 6 to adjust and accelerate the magnetic field of the mass separator 20 constituted of the curved acceleration tube 6 and an electromagnet 8. The gas ions form the specific orbit determined by the charge and mass and only the ions having the same orbit as the curvature of the acceleration tube 6 among these ions enter a sample chamber 13 in a high-purity state. The thin film by the ions is thus deposited by evaporation on the substrate 12. First and second cooling cylinders 15, 16 using liquid N and liquid He are disposed in the acceleration tube 6 in such a case to cool, condense and remove the non-ionized gaseous raw materials. Only the ionized gas of high purity is introduced into the sample chamber 13. The vapor deposited film having the extremely high grade is thus formed on the substrate 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to thin film formation using an ion beam in a vacuum, and particularly to facilitating the manufacture of a device and improving the film formation efficiency.

[0002]

2. Description of the Related Art FIG. 3 shows an example of an ion beam vapor deposition apparatus. The material introduced as the source gas 1 through the gas inlet is dissociated and ionized in the ionization chamber 2 by a method such as plasma discharge. The ionized material substance is extracted by the accelerating electrode 4 in the accelerating electrode chamber 3 and flies through the accelerating tube 6 as an ion beam 5. Accelerating electrode chamber 3 and accelerating tube 6
A gate valve 7 is provided between the gate valve 7 and the start end of the. Accelerator tube 6
Are designed to pass through the magnetic field created by the electromagnet 8.

Since the ions are charged particles, they receive a force in a direction perpendicular to the direction of motion and the direction of the magnetic field, and the direction of motion can be bent. When the accelerating tube 6 is bent and the magnetic field is appropriately adjusted as shown in FIG. 3, the accelerating voltage is constant, so a specific orbit determined by the charge and mass is drawn. Of these, only those having the same orbit as the curvature of the acceleration tube 6 sequentially pass through the gate valve 9 and the bellows 10 and reach the sample chamber 13. That is, the electromagnet 8 and the acceleration tube 6 form a mass separator 20. Only high-purity ions having a desired mass can be guided to the sample chamber 13 by the magnetic field. The ions guided to the sample chamber 13 are focused on the substrate 12 while being decelerated by the deceleration electrode 11.

The feature of this vapor deposition method is that a film is formed with high-purity ions, so that the film has high purity and particles having momentum, so that a dense film can be obtained. On the other hand, the vacuum degree of the sample chamber 13 is important as a factor for improving the quality of the film.
If the degree of vacuum is poor, residual gas components may be trapped in the film,
Due to the scattering of ions, the dense and highly pure film as described above cannot be obtained.

[0005]

In the case of the above-mentioned conventional ion beam vapor deposition apparatus, since the raw material gas 1 is introduced into the ionization chamber 2, there is a drawback that the raw material gas 1 flows out into the accelerating tube 6 and the sample chamber 13. It was Accelerating tube 6 when raw material gas 1 flows out
The degree of vacuum in the interior and the sample chamber 13 becomes poor. When the degree of vacuum becomes poor, the film is adversely affected in the following points. (1) When the degree of vacuum in the sample chamber 13 deteriorates, gas molecules are adsorbed on the substrate 12 during film formation, and the purity and quality of the film deteriorate. Moreover, incident ions are scattered by gas molecules, the energy of the ions is lost, and the directions thereof are uneven, so that a dense film cannot be obtained. (2) When the degree of vacuum in the acceleration tube 6 decreases, gas molecules and ions collide with each other to cause various interactions. The main one of these is charge exchange between gas molecules and ions. As a result, the ions become neutral particles, and the neutral particles are not decelerated by the deceleration electrode 11 and sneak into the substrate 12 at a high speed. As a result, the atoms on the surface are knocked out or the arrays are projected, and the surface of the film becomes rough.

In order to prevent the raw material gas 1 from flowing out, a vacuum pump is usually installed in the ionization chamber 2, the front and rear of the acceleration tube 6, and the sample chamber 13.
In addition, orifices (small diameter portions) are provided at various places so that a gradient of the degree of vacuum is provided from the ionization chamber 2 to the sample chamber 13. However, if an orifice is provided, the efficiency of ion transport is reduced and the efficiency of film formation is deteriorated. Further, since the acceleration tube 6 is kept at a high voltage and has a complicated surrounding such as passing through an electromagnet, it is difficult to connect the vacuum exhaust system. Therefore, it is conceivable to extend the length of the accelerating tube to make the work easier, but this is not desirable because it increases the traveling distance of the ions and rather increases the chance of collision between the ions and gas molecules.

As described above, in the conventional technique, there is no good method for increasing the vacuum degree of the acceleration tube 6 and the sample chamber 13. An object of the present invention is to provide an ion beam vapor deposition apparatus which is easier to manufacture than the conventional method of adding a vacuum pump and an orifice and has a high film forming efficiency.

[0008]

According to the present invention, a cooled plate is placed in the accelerating tube 6 so that the gas in the accelerating tube 6 is condensed on the cooling plate to prevent the degree of vacuum in the accelerating tube 6 from deteriorating. prevent. As a result, the device can be manufactured more easily than before and the film forming efficiency can be improved. Further, according to the method of using the cooling plate of the present invention, the degree of vacuum can be improved as compared with the conventional method, so that the collision of gas molecules and ions in the accelerating tube 6 is reduced, and there is almost no chance that high-speed particles are incident on the substrate 12. No more, sample room 1
Since the gas flow into 3 is also reduced, it is possible to deposit on the substrate 12 a high-quality thin film with few impurities, which is dense and has no rough surface.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIG. 1 in which parts corresponding to those in FIG. In the present invention, the first cooling cylinder 15 and the second cooling cylinder 16 coaxially mounted in the first cooling cylinder 15 are coaxially arranged in the acceleration tube 6 of the ion beam evaporation apparatus. Vacuum container 17
The liquid nitrogen 18 and the liquid helium 19 contained therein cool the first and second cooling cylinders 15 and 16, respectively. The liquid nitrogen 18 and the first cooling cylinder 15 cooled by the liquid nitrogen 18 are placed outside in order to prevent evaporation of the liquid helium 19 due to the invasion of heat from the outside, and the liquid helium 1 is placed inside the liquid nitrogen 18.
9 and a second cooling cylinder 16 cooled thereby. The temperature of the liquid nitrogen 13 is 77K (-196 ° C), and the temperature of the liquid helium 14 is 4K (-269 ° C).

FIG. 2 shows the relationship between the vapor pressure of various gases and the temperature. As can be seen from FIG. 2, when the temperature drops, the vapor pressures of various gases drop rapidly and agglomerate on the cooling cylinders 15 and 16. Therefore, the inside of the acceleration tube 6 is maintained in a high vacuum, and the ions are
It is guided to the sample chamber 13 without colliding with gas molecules. Most of the gas molecules are captured by the first and second cooling cylinders 15 and 16, and the sample chamber 13 can be kept in a high vacuum.

[0011]

According to the present invention, the apparatus can be manufactured more easily than the conventional method of adding a vacuum pump or an orifice. Further, since the inside of the accelerating tube 6 and the sample chamber 13 can be maintained at a higher vacuum than in the conventional case, inflow of ions other than the selected ions into the sample chamber 13 can be suppressed and a high quality thin film can be formed.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between temperature and vapor pressure of various gases.

FIG. 3 is a principle configuration diagram of a conventional ion beam deposition apparatus.

Claims (1)

Claim: What is claimed is: 1. An ionization chamber for ionizing a source gas, an accelerating part for extracting ions from the ionization chamber at a high voltage, and a mass separator for mass-separating the extracted ions by an electromagnetic method. An ion beam vapor deposition apparatus comprising a decelerator for decelerating ions flying at a high speed to a desired energy and depositing ions on a substrate, wherein a cooled plate is placed in the mass separator and the mass separation is performed on the plate. An ion beam vapor deposition device characterized by aggregating the gas inside the chamber.