JPH09202960A - Formation of thin film and thin film forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the infiltration of impurity oxygen into a boron nitride film, to improve the production capacity, to decrease the frequency of maintenance and to reduce the cost. SOLUTION: A boron thin film or a boron compd. thin film is formed on a substrate 9 in a vacuum vessel 1. A turbo molecular pump 2 and a cryopump 4 are provided to the vacuum vessel 1 respectively through valves 3 and 5, the vessel is evacuated by the turbo molecular pump 2 and cryopump 4 before the film is formed, the valve 5 on the cryopump 4 side is closed while the film is formed, and the vessel is evacuated only by the turbo molecular pump 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming method and a thin film forming apparatus for forming a boron film or a boron compound film on a substrate in a vacuum container.

[0002]

2. Description of the Related Art A conventional thin film forming method and thin film forming apparatus of this type are disclosed in, for example, Japanese Patent Application Laid-Open No. 60-63372 (C23.
C 16/34), a boron nitride (BN) thin film is formed on a substrate by combining vacuum deposition in which a substance containing boron is heated and vaporized with N ion irradiation. In addition, there is an advantage that a high-hardness boron nitride thin film is formed with good adhesion.

Boron nitride is excellent in hardness, chemical stability, thermal conductivity and the like, and in order to improve the wear resistance and corrosion resistance of boron nitride, not only the means disclosed in the above publication but also sputtering and It has been industrially tried to synthesize a thin film by ion plating or the like to form a boron nitride thin film on a substrate.

However, when synthesizing a boron nitride film, when the vacuum deposition method of the above-mentioned publication is used, impurities such as oxygen are mixed in the boron nitride film, often causing deterioration of the film quality of the boron nitride film. Occur. The oxygen impurities are often generated by evaporation of water adsorbed on the wall surface of the vacuum container.

As a means for solving this problem, Japanese Patent Laid-Open No. 63-63
As disclosed in JP-A-26349 (C23C 14/06), vapors of Al and Ti are generated in a vacuum container, oxygen impurities are captured in the vapors, and impurity oxygen is prevented from entering the boron nitride film. ing.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the case of JP-A-26349, since the process of generating vapors of Al and Ti requires a large amount of time for production, the production amount is low, and an evaporation source for evaporating Al and Ti is required. There is a problem that the price becomes high.

By the way, it is advantageous to use a cryopump as a main pump for vacuum evacuation in order to efficiently exhaust the water in the vacuum container. The cryopump has a surface cooled to an extremely low temperature installed in the pump. The gas molecules are adsorbed on the cooling surface and exhausted, and the exhaust speed for water molecules is high, which is convenient for preventing oxygen impurities from being mixed into the boron nitride film.

However, in the case of a film forming method using boron or a boron compound as an evaporation substance, during the film formation of a cryopump, the vapor of boron or a boron compound is inevitably adsorbed inside the cryopump, and this vapor is absorbed by water inside the pump. There is a problem that it reacts with molecules, boron oxide is adsorbed on the cooling surface of the pump, the exhaust capacity of the cryopump deteriorates, and industrial problems such as an increase in the number of times maintenance is required occur. .

As a means for solving this problem, it is conceivable to use a turbo molecular pump in which the adsorption of boron oxide in the pump does not occur. However, this pump is inferior to the cryopump in the exhaust capacity of water molecules, and therefore, the vacuum pump is used. Moisture during film formation in the container is not sufficiently removed, and there is concern that oxygen impurities may be mixed into the boron nitride film.

Therefore, as shown in Japanese Patent Application Laid-Open No. 4-175475 (F04B 37/16), it is conceivable to use an exhaust pump which is a combination of a low temperature trap and a turbo molecular pump. Since the substances are adsorbed, the exhaust capacity of the low temperature trap is immediately lowered, and there is a problem that it is necessary to remove the pump and perform maintenance each time.

In consideration of the above points, the present invention can prevent the mixing of oxygen impurities during film formation into the boron nitride film, improve the production capacity, and reduce the number of maintenances.
It is an object to provide an inexpensive thin film forming method and apparatus.

[0012]

In order to solve the above problems, a thin film forming method according to claim 1 of the present invention is a thin film forming method for forming a boron film or a boron compound film on a substrate in a vacuum container. , A turbo molecular pump and a cryopump are individually attached to the vacuum container via valves, respectively, before the film is formed, the turbo molecular pump and the cryopump are evacuated, and during the film formation, the valve on the cryopump side is closed and the turbo molecular pump is closed. The pump is used only for exhausting.

Therefore, since the film is evacuated by the cryopump and the turbo molecular pump before the film formation, the adsorbed water in the vacuum container is sufficiently removed, and the generation of oxygen impurities generated by the volatilization of water is prevented. Since the valve on the cryopump side is closed inside and the gas is exhausted only by the turbo molecular pump, the incorporation of boron vapor into the cryopump side is prevented, and the adsorption of boron vapor onto the cooling surface of the cryopump is prevented, The early exhaust capacity of the cryopump is prevented from being lowered, and the maintenance frequency of the cryopump is reduced.

Further, since there is no step for generating Al and Ti vapors, the cost is low and the production capacity is improved.

Further, in the thin film forming method according to claim 2 of the present invention, a turbo molecular pump is attached to the vacuum container via a valve, and a cryopump is attached to the vacuum container via a conductance valve, and a turbo is used before film formation. The film is evacuated by a molecular pump and a cryopump, and is evacuated by a turbo molecular pump during film formation, while the evacuation speed of the cryopump is controlled by a conductance valve.

Therefore, since the pump is evacuated by both pumps before the film formation, the adsorbed water in the vacuum container is sufficiently removed, and while the film is formed by the turbo molecular pump, the conductance valve controls the evacuation speed of the cryopump. Because of the control, even if oxygen impurities are generated by the adsorbed water from the vacuum container, they are removed, and the inflow of boron vapor to the cryopump side is small, and the prevention of oxygen impurities from entering the film during film formation is further strengthened. As a result, a high-quality film quality is obtained, and deterioration of the cryopump is prevented.

According to a third aspect of the present invention, in a thin film forming apparatus, a turbo molecular pump is attached to a vacuum container via a valve, a pipe for circulating a cooled refrigerant is provided in the vacuum container, and a pipe is provided inside the pipe. It is provided with a deposition preventive plate.

Therefore, during the film formation, the turbo molecular pump evacuates and the refrigerant cooled in the vacuum container is circulated through the pipe, so that the water adsorbed in the vacuum container is adsorbed on the pipe and the film formation is performed. Mixing of oxygen impurities in the boron nitride film is prevented.

Furthermore, the deposition preventive plate prevents the vapor of boron from being adsorbed on the pipe as boron oxide, and the number of maintenance of the trap of water molecules due to low temperature is reduced.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described with reference to FIGS. (Mode 1) First, in FIG. 1 showing a cut-away front view of Mode 1, 1 is a vacuum container, 2 is a valve 3 on the right side of the vacuum container 1.
It is a turbo molecular pump attached via a gas turbine, and the gas molecules are discharged to the outside of the vacuum container 1 by a rotating blade that rotates at a high speed. 4 is a cryopump mounted on the left side of the vacuum container 1 via a valve 5, 6 is provided on the right side of the bottom surface of the vacuum container 1, and is an ion source for irradiating nitrogen ions, and 7 is vaporized by heating boron or a boron compound. It is an evaporation source and is provided on the left side of the bottom surface of the vacuum container 1. Reference numeral 8 is a substrate holder provided in the center of the upper portion of the vacuum container 1, and 9 is a substrate installed in the holder 8.

Next, the film forming method will be described. First, the substrate 9 is set on the substrate holder 8, the substrate holder 8 is inserted into the vacuum container 1, both valves 3 and 5 are opened, and the inside of the vacuum container 1 is set to a desired vacuum degree by the turbo molecular pump 2 and the cryopump 4. Exhaust.

Next, the valve 5 on the side of the cryopump 4 is closed, the inside of the vacuum container 1 is evacuated only by the turbo molecular pump 2, and the evaporation source 7 heats and vaporizes boron or a boron compound to form a boron film on the substrate 9. At the same time as formation, exchange, or film formation, nitrogen ions are irradiated from the ion source 6. Then, after the film formation is completed, the valve 3 is closed, the inside of the vacuum container 1 is vented, and the substrate 9 is taken out.

Therefore, since the pumps 2 and 4 are evacuated to vacuum before the film formation, the adsorbed water in the vacuum container 1 is sufficiently removed, and the generation of oxygen impurities generated by the volatilization of water is prevented. During the film formation, the valve 5 is closed and exhausted only by the turbo molecular pump 2, so that the boron vapor is prevented from being taken into the cryopump 4 side and the boron vapor is prevented from being adsorbed to the cooling surface of the cryopump 4. As a result, a reduction in the early exhaust capacity of the cryopump 4 is prevented.

(Mode 2) Next, Mode 2 will be described with reference to FIG. 2 showing a cut front view. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding ones, and the difference is that the cryopump 4 is attached to the left side of the vacuum container 1 via a conductance valve 10.

In the case of the first embodiment, the exhaust of the cryopump 4 is completely stopped during the film formation, so that oxygen impurities may be mixed due to the desorption of adsorbed water from the vacuum container 1 or the like. As a means for preventing the inclusion of oxygen impurities, when high-purity film quality is particularly required, both pumps 2 and 4 are evacuated to vacuum before film formation, and the turbo molecular pump 2 is evacuated during film formation, Conductance valve 10
Thus, the exhaust speed of the cryopump 4 is controlled, and the inflow of boron vapor to the cryopump 4 side is reduced as much as possible to form a film.

Therefore, although it is not possible to completely prevent the boron vapor from flowing into the cryopump 4, it is possible to sufficiently remove the adsorbed water in the vacuum chamber 1 during film formation, so that a film of oxygen impurities during film formation is formed. Prevention of mixture into the inside is further strengthened, high quality film quality is obtained, and deterioration of the cryopump 4 is prevented.

(Mode 3) In FIG. 3, which is a cutaway front view of mode 3, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, and the different points are as follows. 11
Is a refrigerating device having a refrigerator provided on the left side of the vacuum container 1, 12 and 13 are supply pipes and discharge pipes, one end of which is connected to the refrigerating device 11, and 14 is an upper portion and a peripheral portion of the vacuum container 1. Is a pipe provided on the side, both ends of which are connected to the other ends of the supply and discharge pipes 12 and 13, and is a refrigerant cooled by the refrigerating device 11, such as liquid nitrogen, liquid helium, alternative CFC substances, ammonia, etc. Various liquids and gases are circulated in the vacuum container 1 through the pipe 14. Reference numeral 15 denotes an adhesion preventive plate provided inside the pipe 14, which prevents the vapor of boron from being adsorbed to the pipe 14 as boron oxide.

During film formation, the turbo molecular pump 2 evacuates and the refrigerating apparatus 11 is placed in the vacuum container 1.
By circulating the refrigerant cooled by the pipe 14, the adsorbed water in the container 1 is adsorbed to the pipe 14,
Mixing of oxygen impurities into the boron nitride film during film formation is prevented. Next, after the film formation, when refrigerating the inside of the vacuum container 1, the refrigerating apparatus 11 is stopped and the circulation of the refrigerant is stopped.

In the case of the above-mentioned modes 1, 2 and 3, the method for forming a boron nitride film using ion irradiation has been described as an example, but other boron compounds such as titanium boride, zirconium boride and boride are used. It can also be applied to sputtering, ion plating, and various CVD methods for forming a film using boron such as chromium or carbon boride.

[0030]

Since the present invention is constructed as described above, it has the following effects. In the thin film forming method according to claim 1 of the present invention, the turbo molecular pump 2 and the cryopump 4 are individually attached to the vacuum container 1 via the valves 3 and 5, respectively, and before the film formation, the turbo molecular pump 2 and the cryopump are attached. 4 and the valve 5 on the side of the cryopump 4 is closed during film formation so that the turbo molecular pump 2 alone evacuates the film. Of the adsorbed water can be sufficiently removed to prevent generation of oxygen impurities generated by volatilization of water, and during film formation, the valve 5 on the side of the cryopump 4 is closed and exhausted only by the turbo molecular pump 2, It is possible to prevent the intake of the vapor of the vapor into the cryopump 4 side, to prevent the adsorption of the boron vapor to the cooling surface of the cryopump 4, and to quickly discharge the cryopump 4 It is possible to prevent a decrease in capacity, it is possible to reduce the frequency of maintenance of the cryopump 4. Furthermore, since there is no step for generating Al and Ti vapors,
It is inexpensive and can improve the production capacity.

Further, the thin film forming method according to claim 2 is
A turbo molecular pump 2 is attached to the vacuum container 1 via a valve 3, and a cryopump 4 is attached to the vacuum container 1 via a conductance valve 10. The cryopump 4 is evacuated before film formation and the turbo pump is formed during film formation. Since the conductance valve 10 controls the pumping speed of the cryopump 4 while exhausting with the molecular pump 2, the pumps 2 and 4 are vacuum-exhausted before the film formation, and the adsorbed water in the vacuum container 1 is sufficiently removed. During the film formation, while the turbo molecular pump 2 exhausts oxygen impurities, the conductance valve 10 controls the exhaust speed of adsorbed water such as the vacuum container 1 of the cryopump 4 so that oxygen impurities due to adsorbed water from the vacuum container 1 are removed. Even if it is generated, it is removed, and the film is formed by minimizing the inflow of boron vapor into the cryopump 4 side. Can be, it is possible to strengthen the prevention of contamination into the membrane of the oxygen impurities in the film formation, it is possible to obtain the quality of the high quality, it is possible to prevent deterioration of the cryopump 4.

In the thin film forming apparatus according to the third aspect of the present invention, the turbo molecular pump 2 is attached to the vacuum container 1 via the valve 3 and the pipe 14 for circulating the cooled refrigerant in the vacuum container 1 is provided. , Anti-adhesion plate 15 inside the pipe 14
Since the turbo molecular pump 2 is evacuated during the film formation, and the coolant cooled in the vacuum container 1 is circulated through the pipe 14, the pipe 14 is provided.
Adsorbed water in the vacuum container 1 can be adsorbed on the substrate, and oxygen impurities during film formation can be prevented from entering the boron nitride film.

Further, the deposition preventive plate 15 can prevent the adsorption of boron vapor on the pipe 14 as boron oxide,
It is possible to reduce the maintenance frequency of the trap of water molecules due to low temperature.

[Brief description of drawings]

FIG. 1 is a cut front view of a first embodiment of the present invention.

FIG. 2 is a cut front view of a second embodiment of the present invention.

FIG. 3 is a cut front view of a third embodiment of the present invention.

[Explanation of symbols]

 1 vacuum container 2 turbo-molecular pump 3 valve 4 cryopump 5 valve 9 substrate 10 conductance valve 14 pipe 15 deposition plate

Claims (3)

[Claims] 1. A thin film forming method for forming a boron film or a boron compound film on a substrate in a vacuum container, wherein a turbo molecular pump and a cryopump are individually attached to the vacuum container through valves to form a film. The thin film forming method is characterized in that the vacuum is evacuated by the turbo molecular pump and the cryopump before, and the valve on the cryopump side is closed during the film formation and the gas is evacuated only by the turbo molecular pump. 2. A thin film forming method for forming a boron or boron compound film on a substrate in a vacuum vessel, wherein a turbo molecular pump is attached to the vacuum vessel via a valve and a conductance valve is attached to the vacuum vessel. A cryopump is attached by means of vacuum pumping before film formation by the turbomolecular pump and the cryopump, and during film formation, the turbomolecular pump exhausts air while the conductance valve controls the pumping speed of the cryopump. A thin film forming method characterized by the above. 3. A thin film forming apparatus for forming a boron film or a boron compound film on a substrate in a vacuum container, wherein a turbo molecular pump is attached to the vacuum container via a valve and cooled in the vacuum container. A thin film forming apparatus comprising: a pipe for circulating a refrigerant; and an anti-adhesion plate provided inside the pipe.