JPS6247472A - Formation of cubic boron nitride film - Google Patents

Abstract

PURPOSE:To easily obtain a cubic boron nitride film having a large area and satisfactory crystallizability by utilizing high density plasma and high frequency bias during reaction and vapor deposition by electric discharge with a hollow cathode. CONSTITUTION:DC or AC bias voltage is applied to a reactive gas introducing nozzle 5 from a power source 8 to generate high density plasma. High frequency voltage 9 is then applied to a body 3 to be processed to form a high frequency electric field around the body 3. By the electric field, bias voltage effective on the high density plasma is applied to the body 3. Thus, a cubic boron nitride film having a large area is obtd. at a high rate of deposition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a cubic boron nitride film by reactive vapor deposition using hollow cathode discharge.

[Conventional Technique 4IFI] 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 cubic phosphorus nitride 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 a compound film by reactive vapor deposition using hollow cathode discharge, Japanese Patent Application No. 60-43617 (Japanese Unexamined Patent Application Publication No. 1983-1989) previously described the method of forming a compound film by using the electrons present in the plasma generated by hollow cathode discharge. We proposed a method to activate the reactive gas by drawing a part of it into the reactive gas inlet using an electric field to increase the reactivity in chemical vapor deposition. With this method, it is possible to generate a current that is more than an order of magnitude larger than that of DC and R glow discharges, and because the current is concentrated near the reactant gas inlet, the plasma density can dramatically increase. Admitted.

[Problem t1 to be solved by the invention] By the way, cubic boron nitride (c-BN
), it is possible to obtain a highly perfect crystal, but it is difficult to control the size and shape, and the manufacturing cost is also high. On the other hand, films made using a method that combines ion implantation and vacuum deposition contain hexagonal boron nitride (
Since the h-BN) phase is mixed, and the processing area is small considering the large size of the device, 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 at a high deposition rate. Furthermore, there have been no detailed reports regarding the formation of cubic boron nitride by activated reactive vapor deposition.

A mesh-like electrode is sometimes used to accelerate ions, but since cubic boron nitride is an insulator,
An insulator adheres to the mesh-like electrode, which causes the bias voltage to fluctuate, making it difficult to obtain reproducibility of the coating film. Furthermore, since some of the ionized atoms are taken away by the mesh-like electrode, the amount of ions rAm entering the substrate decreases, making it impossible to use the generated plasma effectively. Furthermore, if the electric power applied to the mesh-like electrode becomes too low, the mesh-like electrode itself will be sputtered by ions, causing contamination with impurities contained in the film. In addition, when applying a DC bias to the workpiece for forming cubic boron nitride, 100
Once the 3N film is formed, no substrate current will flow.

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 Problem U] 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 the reaction gas introduction nozzle to form a high-density A high-frequency voltage is applied to the object to be processed to form a cubic boron nitride film, a high-frequency electric field is formed near the surface of the object, and the 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 is
It can be supplied from DC or AC power.

Further, N2 or NH3 can be used as the reaction gas.

[Function] In the method for forming a cubic boron nitride film according to the present invention, the effective ion energy necessary for ion bombardment is generated by the high-frequency bias voltage applied to the workpiece on which the cubic boron nitride film is to be formed. As a result, ions existing at large ω 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 workpiece.

[Example] Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 schematically shows an example of an apparatus implementing the method for forming a cubic boron nitride film according to the present invention. 2, a material 3 to be treated to form cubic boron nitride ml facing the water-cooled copper hearth 2, a hollow cathode electron gun 4, and N2 or NH3 introduced into the vacuum volume 1. Reaction gas introduction nozzle 5 and heater 6 for the object to be treated 3
and are arranged. Water-cooled copper hearth 2 and hollow l! 2h
A DC power source 7 is connected to the type electron gun 4 with the polarity shown in the figure for generating a hollow hot cathode discharge therebetween.

DC or AC power supply 8 (:t, hollow cathode) In order to generate an electric field that draws some of the electrons in the discharge space into the reaction gas introduction nozzle 5, the reaction gas introduction nozzle 5 and the hollow cathode type electron gun 4 are connected.
A positive DC or AC voltage of several tens to hundreds of volts is applied. Further, a high frequency power source 9 is connected to the workpiece 3 via a matching element of each side coupling type.

The hollow hot cathode discharge generated between the water-cooled copper hearth 2 and the hollow cathode electron gun 4 has a low voltage and a large current.
A part of the electrons in the hollow cathode discharge space are drawn into the reaction gas introduction nozzle 5 by a positive bias voltage applied between the reaction gas introduction nozzle 5 and the hollow cathode type electron gun 4 by the DC or AC power supply 8. , which causes collisions between electrons and reactive gas molecules, resulting in a high-density M electric state. Due to its binding, 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 near the workpiece 3, and a high-density plasma is generated in the front surface of the water-cooled copper hearth 2 and the front surface of the reactive gas introduction nozzle 5. An effective bias voltage is applied to the object 3 to be processed. By this high-frequency bias voltage, ions present in the seedlings in the high-density plasma can be effectively incident on the object 3 to be treated.

Next, a specific example of implementing the method of the present invention using the illustrated apparatus will be illustrated.

As a deposition condition, argon gas is supplied at a pressure of 0.13 Pa through the hollow cathode electron gun 4, and the reaction gas introduction nozzle 5
Nitrogen gas was introduced at a pressure of 0.05 pa, the hollow hot cathode voltage was set to 30 V and 150 Δ, the deposition rate was 0.05 μm/min, and the voltage was applied to the reaction gas introduction nozzle 5 by a DC or AC power source 8. The positive bias voltage applied was 80V, 2Δ, the high frequency power applied to the object 3 to be processed was 80W, and the object 3 to be processed was quartz, a silicon wafer, and a Mo (molybdenum) substrate.
The temperature was set at 500° C., and a cubic boron nitride film was formed on the substrate. FIG. 2 shows the infrared absorption spectrum of the cubic boron nitride film thus formed.

As seen from the graph in Figure 2, the C-BN-specific 1
The absorption of 045cs-1 is shown and is 1350cm-
The absorption of h = [3N around 1750 crm-' is not observed.

Further, Table F shows a comparison between the lattice spacing of the cubic boron nitride film determined by electron beam diffraction and the ΔSTM diffraction (X-ray diffraction) data card.

From the above table, it can be seen that the lattice spacing of the cubic boron nitride film determined by electron beam diffraction is consistent 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 boron nitride with good crystallinity is produced by using high-density plasma and high-frequency bias in reactive vapor deposition using hollow cathode discharge. A film can be easily formed on a large area at a high deposition rate relative to the object to be processed. Therefore, the method of the present invention can be applied to coat cutting tools and the like to extend the gap 1ω, and can also be applied to electronic materials and the like by taking advantage of its 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 shows cubic boron nitride formed using the apparatus of Fig. 1. It is a graph showing an infrared absorption spectrum of a film. In the figure, 1: vacuum container, 2: evaporation source, 3: object to be treated on which a 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. Figure 1 Figure 2

Claims (1)

[Claims] In the method of 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 to form a cubic boron nitride film. A high-frequency electric field is formed near the surface of the object to be processed by applying a high-frequency voltage to the object to be processed, and a bias voltage effective for the high-density plasma in front of the evaporation source and the reaction gas introduction nozzle is applied to the object. A method for forming a cubic boron nitride film, characterized in that the film is coated on a processed material.