JPH031377B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for forming a cubic boron titanium film by reactive vapor deposition using hollow cathode discharge. [Prior Art] Conventionally, attempts have been made to synthesize cubic boron nitride (c-BN) using a high temperature/high pressure method or a gas phase method. The high-temperature, high-pressure method can yield highly perfect crystals. Furthermore, in the vapor phase method, attempts have been made to produce a cubic boron nitride film using an ion beam sputtering method, a method combining ion implantation and vacuum evaporation, and an activated reaction evaporation method. On the other hand, as a method for forming compound films by reactive vapor deposition using hollow cathode discharge, a patent application was filed in 1980-
43617 (Japanese Unexamined Patent Publication No. 43617), a part of the electrons present in large quantities in the plasma generated by hollow cathode discharge is drawn into the reactive gas inlet by an electric field, and the reactive gas is activated to improve reactivity in chemical vapor deposition. proposed a method to increase With this method, it was possible to obtain a current that was more than an order of magnitude larger than that of DC and RF glow discharge, and because the current was concentrated near the reactant gas inlet, it was observed that the plasma density increased dramatically. . [Problems to be solved by the invention] By the way, when cubic boron nitride (c-BN) is formed by a high temperature and high pressure method, highly perfect crystals can be obtained, but it is difficult to control the size and shape. is difficult and the manufacturing cost is high. On the other hand, films made using a method that combines ion implantation and vacuum deposition contain a hexagonal boron titanium (h-BN) phase, and the processing area is small considering the large scale of the equipment. Therefore, there are problems not only in productivity but also in reproducibility. In the ion beam sputtering method, since the plasma density is low, it is not possible to coat a large area with a high deposition rate. Furthermore, there have been no detailed reports regarding the formation of cubic boron nitride by activated reaction vapor deposition. A mesh-shaped electrode is sometimes used to accelerate ions, but since cubic boron nitride is an insulator, the insulator adheres to the mesh-shaped electrode, which changes the bias voltage and causes the coating to Obtaining membrane reproducibility is difficult. In addition, some of the ionized atoms are taken away by the mesh-shaped electrode, so the amount of ions incident on the substrate decreases.
For this reason, the generated plasma cannot be used effectively. Furthermore, when the electric power applied to the mesh-shaped electrode becomes large, the mesh-shaped electrode itself is spattered by ions, causing contamination with impurities contained in the film. Furthermore, when applying a DC bias to a processing object on which a cubic boron dioxide film is to be formed, the substrate current stops flowing once a BN film of about 100 Å is formed. Therefore, an object of the present invention is to provide a method for forming a cubic boron nitride film with excellent mass productivity and good crystallinity by applying the previously proposed method for forming a compound film by reactive vapor deposition using hollow cathode discharge. It's about doing. [Means for Solving the Problems] In order to achieve the above object, the method for forming a cubic boron nitride film according to the present invention applies a DC or AC bias voltage to a reaction gas introduction nozzle to form a high-density film. A high frequency voltage is applied to the object to be processed to form a cubic boron nitride film to form a high frequency electric field near the surface of the object. It is characterized in that a bias voltage effective for high-density plasma is applied to the object to be processed. The positive bias voltage applied to the reaction gas introduction nozzle can be supplied from a DC or AC power source. Furthermore, N ₂ or NH ₃ can be used as the reaction gas. [Function] In the method for forming a cubic boron nitride film according to the present invention, effective ion energy necessary for ion bombardment is generated by a high-frequency bias voltage applied to the workpiece on which a cubic boron nitride film is to be formed. As a result, ions present in large quantities in the high-density plasma generated by applying a DC or AC bias voltage to the reaction gas introduction nozzle can effectively enter the workpiece. , a cubic boron nitride film can be effectively formed on the object to be treated. [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 schematically shows an example of an apparatus for carrying out the method for forming a cubic boron titanium film according to the present invention. Inside the vacuum vessel 1, there is a water-cooled copper hearth containing boron, which is an evaporation source. 2, a workpiece 3 on which a cubic boron nitride film is to be formed, which faces the water-cooled copper hearth 2, a hollow cathode electron gun 4, and a reaction gas for introducing N ₂ or NH ₃ into the vacuum vessel 1. An introduction nozzle 5 and a heater 6 for the object to be processed 3 are arranged. A DC power supply 7 is connected between the water-cooled copper hearth 2 and the hollow cathode type electron gun 4 with the polarity shown in the figure for generating a hollow hot cathode discharge therebetween. A DC or AC power supply 8 is connected between the reactive gas introduction nozzle 5 and the hollow cathode electron gun 4 to generate an electric field that draws some of the electrons in the hollow cathode discharge space into the reactive gas introduction nozzle 5. Apply positive or alternating current voltage of several tens to hundreds of volts. Further, a high frequency power source 9 is connected to the workpiece 3 via a capacitively coupled matching element. The hollow hot cathode discharge generated between the water-cooled copper hearth 2 and the hollow cathode type electron gun 4 has a low voltage and a large current, and is also connected to the reaction gas introduction nozzle 5 and the hollow cathode by a DC or AC power source 8. Due to the positive bias voltage applied between the mold electron gun 4 and the hollow cathode discharge space, some of the electrons are transferred to the reaction gas introduction nozzle 5.
As a result, collisions occur between electrons and reactive gas molecules, resulting in a high-density discharge state. As a result, the reactant gas is partially ionized and activated to a neutral excited state. By applying a high frequency voltage to the workpiece 3 by the high frequency power supply 9, a high frequency electric field is generated in the vicinity of the workpiece 3, and a high density electric field is generated in the front surface of the water-cooled copper hearth 2 and the front surface of the reaction gas introduction nozzle 5. A bias voltage effective for plasma is applied to the object 3 to be processed. Due to this high frequency bias voltage, ions present in large quantities in the high-density plasma can be effectively incident on the object 3 to be processed. Next, a specific example of implementing the method of the present invention using the illustrated apparatus will be illustrated. As the deposition conditions, argon gas was supplied at a pressure of 0.13 Pa through the hollow cathode electron gun 4, nitrogen gas was introduced at a pressure of 0.05 Pa into the reaction gas introduction nozzle 5, and the hollow hot cathode discharge was set at 30 V and 150 A. The speed was set to 0.05 μm/min, the positive bias voltage applied to the reaction gas introduction nozzle 5 by the DC or AC power source 8 was set to 80 V, 2 A, and the high frequency power applied to the object to be processed 3 was set to 80 W. A quartz, silicon wafer, and Mo (molybdenum) substrate were used as material 3, and the temperature was set at 500° C. to form a cubic boron titanide film on the substrate. FIG. 2 shows the infrared absorption spectrum of the cubic boron titanium film thus formed. As seen from the graph in Figure 2, c-BN
A specific absorption of 1045 cm ^-1 is shown and 1350 cm
^-1 No absorption of h-BN near 750 cm ^-1 is observed. In addition, the lattice spacing of the cubic boron titanide film determined by electron beam diffraction and ASTM diffraction (X-ray diffraction)
A comparison with the data card is shown in the table below.

【table】

[Table] From the above table, it can be seen that the lattice spacing of the cubic boron titanide film determined by electron beam diffraction agrees with the ASTM diffraction (X-ray diffraction) data card. The composition of the obtained film was determined by an X-ray microanalyzer to be N/B=1. [Effects of the Invention] As explained above, according to the method of the present invention, cubic crystal formation with good crystallinity is achieved by using high-density plasma and high-frequency bias in reactive vapor deposition using hollow cathode discharge. Boron can be easily deposited on a workpiece at a high deposition rate over a large area. Therefore, the method of the present invention can be applied to coat cutting tools and the like to extend their lifespan, and can also be applied to electronic materials and the like by taking advantage of their high electrical insulation and high thermal conductivity.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an example of a reactive vapor deposition apparatus using hollow cathode discharge in which the method according to the present invention is carried out, and Fig. 2 is a cubic boron nitride film formed using the apparatus shown in Fig. 1. It is a graph showing an infrared absorption spectrum of. In the figure, 1: vacuum container, 2: evaporation source, 3: object to be processed on which cubic boron nitride film is to be formed, 4: hollow cathode electron gun, 5: reaction gas introduction nozzle, 6: heater, 7: DC power supply, 8: DC or AC power supply,
9: High frequency power supply.

Claims (1)

[Claims] 1. In a method for forming a cubic boron nitride film by reactive vapor deposition using hollow cathode discharge, a direct current or alternating current bias voltage is applied to the reaction gas introduction nozzle to generate high-density plasma, and the cubic boron nitride film is formed by applying a DC or AC bias voltage to the reaction gas introduction nozzle. A high-frequency electric field is formed near the surface of the workpiece by applying a high-frequency voltage to the workpiece to be processed, and the effective bias voltage for the high-density plasma in front of the evaporation source and the reaction gas introduction nozzle is set as above. A method for forming a cubic boron titanide film, characterized in that the film is coated on an object to be treated.