JPH0259863B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a high-hardness boron nitride film, and more particularly to a method for manufacturing a high-hardness boron nitride film (hereinafter, boron nitride is abbreviated as BN), which is comprised of a vacuum deposition method and an ion irradiation method. BN includes cubic boron nitride (hereinafter abbreviated as CBN), hexagonal close-packed boron nitride (hereinafter abbreviated as WBN), and hexagonal boron nitride (hereinafter abbreviated as HBN).
There are three crystal structures, among which CBN and WBN
Thermal shock resistance, thermal conductivity, hardness and abrasion resistance,
It also has excellent resistance to iron group metals at high temperatures, so it is attracting attention for a wide variety of applications.
Along with this, research is being conducted into the production of high-quality CBN and WBN. As a known manufacturing technique, there is a method that uses expensive equipment to synthesize at ultra-high pressures and extremely high temperatures of tens of thousands of atmospheres and thousands of degrees Celsius, but recently, vapor phase growth methods have been used to synthesize substrates. Research is also being conducted on the efficient synthesis of CBN and WBN on surfaces to produce thin films. Thin film formation techniques are broadly classified into chemical vapor deposition and physical vapor deposition, and physical vapor deposition using ions has become the mainstream in research on BN films. This method involves the ion beam deposition method, in which ionized atoms are accelerated and then decelerated to deposit them on the substrate, and the method in which cluster ions are accelerated and collided with the substrate to deposit a large number of atoms at once. There are cluster ion plating methods called cluster ion plating methods, and ion beam sputtering methods in which atoms sputtered with ionized and accelerated rare gases are deposited on a substrate. In this method, the kinetic energy of the ions is from several eV to several hundred eV, and the ion species are rarely implanted into the interior of the substrate.
Therefore, the adhesion between the thin film and the substrate was not sufficient. Furthermore, in the ion mixing method, when a substance is deposited on a substrate and then irradiated with an ionic species such as a rare gas with a kinetic energy of several hundred KeV or more, the atoms of the deposited substance are reacted by collisions of the ionic species. As a result, a new thin film composed of both components is formed between the substrate and the deposited layer, and the remaining deposited film is then removed by a chemical method. Then, a new thin film is formed on the substrate surface, and according to this,
Even if the energy of the ion species increases, there is no need to increase the ion current, and a large amount of foreign atoms can be implanted close to the substrate surface. Difficult to keep constant. Therefore, even in the thin film formation technology using ions as described above, the synthesis of CBN and WBN has not yet been reported. In view of the above circumstances, the present inventors conducted intensive research and found that a substrate is first vapor-deposited and ion-irradiated using an evaporation source containing boron and an ion source that generates ion species consisting of at least nitrogen. We have found that high quality CBN and WBN can be formed by this method. The present invention was completed based on the above findings, and its purpose is to provide a novel method for producing a high-hardness BN film by synthesizing a thin film made of high-quality CBN or WBN on a substrate. Another object of the present invention is to produce the above-mentioned high quality CBN.
An object of the present invention is to provide a method for forming a thin film made of or WBN on a substrate at a high film formation rate. Another object of the invention is to provide high energy efficiency;
An object of the present invention is to provide a method by which a high quality boron nitride film can be formed on a substrate. According to the present invention, a boron component is evaporated onto a substrate from an evaporation source containing boron, and the ion species is irradiated onto the substrate from an ion generation source that generates ion species containing at least nitrogen. A method for producing a BN film in which BN is produced, the method comprising:
At the same time, the ion acceleration energy of the ionic species is set to 5 to 100 KeV per atom of the ionic species, and the deposition and irradiation are performed in an atmosphere of nitrogen atoms or nitrogen compounds activated to a lower energy level than the ionic species. , there is provided a method for producing a high hardness BN film, characterized in that a negative bias voltage is applied to the substrate. The present invention will be explained in detail below. In the present invention, by depositing the vapor deposition substance onto the substrate from an evaporation source containing boron, and at the same time irradiating the substrate with ion species from an ion generation source that generates ion species consisting of at least nitrogen, CBN and WBN are synthesized.
Moreover, after the vapor deposition substance is vapor-deposited on the substrate,
Synthesize CBN and WBN by irradiating the ion species,
It is also possible to increase the thickness of the high hardness BN film by alternately repeating the formation of the vapor deposited layer and the ion irradiation in this way. According to this, at the same time as forming the vapor-deposited boron film,
Or, after its formation, due to the sinking effect of the implanted nitrogen atoms and the thermal effect of the energy generated when the ions come to rest in the film, a highly excited state resembling tens of thousands of atmospheres and thousands of degrees Celsius is instantaneously created. Boron atoms and nitrogen atoms, which are essential for the production of CBN and WBN, are produced in a targeted and localized manner.
An SP ³ hybrid orbital is formed. Based on this phenomenon, such boron atoms and nitrogen atoms form SP ³ bonds, which become crystal nuclei of CBN and WBN, and CBN
and WBN. The evaporation source containing boron includes metal boron or boron compounds (boron titanide, boron oxide,
boron sulfide, phosphorus boride, hydrogen borohydride, metal borides containing aluminum or magnesium,
One or more types of transition metal borides are used. The ion species may be any ion species as long as it has a predetermined ion acceleration energy and acts on the evaporation source containing B to form a thin film of CBN.
Specifically, nitrogen atom ions (N ⁺ ); nitrogen molecule ions (N ₂ ⁺ ); nitrogen compound ions such as ammonia ions (NH ₃ ⁺ ); boron nitride ions (BN ⁺ )
or an inert gas ion (for example, Ar ⁺ ). Furthermore, B ₃ N ₃ H ₆ or Al ₂ B ₂ N ₄ or the like can be ionized and used as the ion species. Furthermore, ionic species such as boron ions (B ⁺ ) and borohydride ions (B ₂ H ₆ ⁺ ) can also be used in combination with the above-mentioned nitrogen-containing ion species. Such ion species are created by an apparatus to be described later, and if necessary, are magnetically selected using a magnetron for mass spectrometry and supplied to the substrate surface. The substrate may be made of any material such as ceramics, cemented carbide, cermet, or various metals or alloys, and the material thereof does not matter. However, if the substrate is an electrical insulator, the characteristics of the deposited film will differ between charged and uncharged areas, and variations in the properties of the entire film are likely to occur. Preferably, it is an electrical conductor. However, even if the material is an electrical insulator, a thin film of an electrical conductor may be formed on its surface by a conventional method. In the present invention, it is important that the ion acceleration energy of the ion species is 5 to 100 KeV per atom of the ion species. The ion acceleration energy of this ion species is 5KeV
If it is less than
When the temperature exceeds 100 KeV, the ion species are implanted considerably deeper than the deposited layer on the substrate surface, so CBN is added to the deposited layer.
High hardness BN, which is mainly composed of CBN and WBN, becomes difficult to generate, and the temperature of the deposited layer becomes too high, and the formation of HBN becomes dominant, resulting in high hardness mainly composed of CBN.
BN becomes difficult to generate. Note that if BN is used as an evaporation source containing boron, the required ion acceleration energy is small and a thin film of CBN or WBN can be grown efficiently. In addition, in the present invention, it is also important that the above-described vapor deposition and ion species irradiation treatments be performed in an atmosphere of nitrogen atoms or nitrogen compounds activated to a lower energy level than the ion species. That is, in the present invention, under conditions where a boron-containing evaporation source and a high-energy nitrogen-containing ionic species coexist, nitrogen atoms activated to a lower level than the ionic species also become CBN and/or WBN.
This is based on the new finding that it is effectively involved in the production of The ionic species used in the ionization synthesis method of the present invention are:
As already pointed out, it has a high energy of 5 to 100 KeV per atom. On the other hand, the kinetic energy of ions used in conventional thin film formation techniques such as ion beam deposition, cluster ion plating, and ion beam sputtering is much lower than that of ionization synthesis, several eV.
It is on the order of ~ several hundred eV. In the present invention, by allowing such low-level excited nitrogen atoms and nitrogen compounds to coexist in the atmosphere for ionization synthesis, we compensate for the significant lack of nitrogen atoms in the evaporation source and ionic species. This enabled the formation of a high-quality BN film. Moreover, according to the present invention, by setting the B/N atomic ratio in the evaporation source and ionic species to a range of 0.2 to 10, an extremely high quality BN film can be formed, as shown in the example described later. Furthermore, it is clear from the examples described later that the film formation rate per unit time is significantly increased by supplementing nitrogen atoms from the atmosphere. Furthermore, the energy efficiency of film production can also be significantly improved by utilizing ionic species irradiation primarily for immersion and thermal effects and replenishing the reactants as an atmosphere excited to low energy levels. In the present invention, various means can be employed to form an atmosphere of nitrogen or nitrogen compounds excited to a low energy level in the vicinity of the substrate surface. The simplest method is to generate nitrogen atoms and nitrogen compounds activated to a low energy level together with high energy ion species from the ion source mentioned above.
It is to supply it to the surface of the substrate. Alternatively, arc discharge can be generated in a stream of nitrogen gas or nitrogen compounds to form low levels of activated nitrogen atoms or nitrogen compounds, which can then be introduced into the deposition and irradiation area. . As mentioned above, ion irradiation and vacuum deposition are performed in an atmosphere of nitrogen atoms and nitrogen compounds activated at a low energy level, and a high-quality BN film is formed by naturally supplementing the nitrogen content that is lacking in the atmosphere. be able to. Furthermore, in the present invention,
It is important to apply a negative bias voltage to the substrate. That is, based on the new knowledge that the atmosphere of nitrogen atoms and nitrogen compounds activated to a low energy level is positively charged as a whole, a negative bias voltage was applied to the substrate as shown in the examples below. By doing so, the atmosphere is attracted, nitrogen components can be actively taken into the substrate surface, and the atmosphere can effectively contribute to the formation of the BN film. When such a bias voltage is applied, components of boron evaporated from the evaporation source and ionized during ion irradiation are also generated, accelerated and attracted to the substrate surface, which is effective for forming a BN film. It acts on Furthermore, since the ion species generated from the ion source are scattered during ion irradiation, some of the scattered ion species disappeared without participating in the formation of the BN film, but these scattered ion species attracted to,
Useless ion irradiation can be avoided. The inventors have experimentally confirmed that the bias voltage applied to the substrate is optimally set within the range of -100V to -10KV, although it is also related to the ion acceleration energy of the -ion species. be. Furthermore, with the application of such a bias voltage, the complementation of nitrogen atoms from the atmosphere progresses more easily, further increasing the film formation rate per unit time, and causing the ion species irradiation to have a sinking effect and a thermal effect. It has been experimentally determined that the energy efficiency of film production can also be significantly improved by utilizing the reactants primarily and efficiently replenishing the reactants as an atmosphere excited to low energy levels. In the present invention, a highly hard BN film can be formed if the atomic ratio of boron to nitrogen (B/N atomic ratio) in the evaporation source and ionic species is set to 0.2 to 1.0. It becomes easier. When the B/N atomic ratio is less than 0.2, amorphous BN tends to be formed, and when it exceeds 10, boron becomes excessive and amorphous boron is easily formed in the film. It has been experimentally confirmed that this optimum condition is in the range of 0.5 to 5. In the present invention, as the ion acceleration energy of the ion species is set within a predetermined range, the dose rate (ion current per unit area of the base) of the ion species to the substrate can be adjusted by irradiating the ion species to the base. The amount of heat generated per unit area (cm ² ) of the base is
It is important to set the power between 0.01 and 20W. If the power exceeds 20W, the boron vapor deposition layer becomes too hot and HBN formation becomes dominant, resulting in CBN and WBN.
On the other hand, if it is less than 0.01 W, the penetration effect and thermal effect of the ionic species cannot be obtained, making it difficult to synthesize CBN and WBN. Furthermore, in the present invention, the temperature of the substrate is -200
It is best to set the temperature to ~700℃. When the temperature of the substrate is set between -200 and 700℃, the locally and instantaneously generated highly excited state is easily maintained, and at the same time, the generated CBN and
WBN can be frozen to prevent conversion to HBN. If the substrate temperature is less than -200℃, the BN film formed on the substrate surface will easily peel off, and if it exceeds 700℃, the generated CBN and WBN will be removed.
Easier to convert to HBN. It has been experimentally confirmed that the optimum temperature of this substrate is 0 to 400°C. Next, an apparatus used for manufacturing a high hardness BN film according to the present invention will be explained with reference to FIG. First, a gas to be ionized, such as N ₂ , is introduced into the ion source 2 via the leak pulp 1, where it is ionized, and then accelerated by the accelerator 3 to be given a predetermined ion acceleration energy. The ions are then introduced into the analysis magnet 4, where only the desired ion species are magnetically selected and supplied to the reaction chamber 5. The reaction chamber 5 is maintained at a high vacuum of 10 ⁻⁵ Torr or less by a vacuum pump (for example, a turbomolecular pump) 6 . The substrate 7 is fixed to a substrate holder 8, and is irradiated with the above-mentioned ion species. During irradiation, the ion species are passed through the collection lens 9 in order to uniformly irradiate the substrate with the ion species. 10 is a vapor deposition device placed under the base 7. As a heating method for the device, an appropriate method such as electron beam heating or laser beam heating is used. This contains an evaporation source containing B. The amount and rate of evaporation of the evaporation source containing B may be measured by a vibrating film thickness meter 11 using, for example, a quartz plate, which is disposed beside the substrate holder 8. Further, the number of atoms of the ion species, that is, the ion current can be accurately measured by a current integrator 13 equipped with a secondary electron repulsion electrode 12. Furthermore, an arc discharge chamber 14 is provided in order to form an atmosphere of nitrogen atoms activated to a low level,
_N2 gas is supplied to this discharge chamber, and nitrogen atoms excited by differential pumping are guided into the reaction chamber 5. A bias power supply 15 whose voltage can be adjusted is connected between the base body 7 and the secondary electron repulsion electrode 12 so as to apply a negative bias voltage to the base body 7 . In such an apparatus, the substrate 7 is set at a predetermined position, the interior of the reaction chamber 5 is maintained at a predetermined degree of vacuum, the vapor deposition device 10 is operated to deposit a predetermined amount of an evaporation source containing boron onto the substrate 7, and By irradiating a predetermined ion species with a predetermined ion acceleration energy and simultaneously applying a predetermined negative bias voltage to the substrate 7, a thin film of high hardness BN mainly composed of CBN and WBN is formed on the substrate surface. Ru. At this time, both the evaporation source and the ion species containing B are evaporated or irradiated from only one direction of the substrate, so when forming a high hardness BN thin film mainly composed of CBN and WBN on the entire surface of the substrate, this method is necessary. The base body may be subjected to motion such as rotation or rocking. Examples of the present invention will be described below. Example 1 High purity N ₂ gas was introduced into the PIG type ion source 2 from the leak pal 1 using the apparatus shown in the figure. Various acceleration energies were applied to the generated ions using an accelerator 3. This ion beam was subjected to mass analysis using an analysis magnet 4, and only N ₂ ⁺ was magnetically selected. On the other hand, a silicon plate was used as the substrate, and this was set in the substrate holder 8, and the inside of the reaction chamber 5 was maintained at a vacuum of 1×10 ^-5 Torr by a turbo molecular pump at 650/sec. Next, a negative bias voltage is applied to the substrate 7 by the bias power supply 15, and the electron beam evaporator 10 containing the metal B is activated to evaporate the metal B, and the silicon plate 7 is simultaneously irradiated with N ₂ ⁺ ions. was deposited on top. At this time, analysis of the gas in the reaction chamber 5 revealed that it was an activated nitrogen gas atmosphere. The amount of B evaporated and the evaporation rate were measured with a vibrating film thickness meter 11, and the number of N ₂ ⁺ ions was measured with a current integrator 13 to calculate B/N. Thin films were formed by changing the bias voltage, changing the ion acceleration energy of N ₂ ⁺ ions, and changing the amount of B vapor deposited. Acceleration energy of N ₂ ⁺ ions is 35KeV, B/N=
1.5, a bias voltage of -1 KV, a substrate temperature of 200° C., and a vacuum degree of 0.5×10 ⁻⁵ Torr for 2 hours to form a BN film with a thickness of 2.5 μm. When the obtained BN film was analyzed by X-ray diffraction, peaks that could be identified as CBN (111) and WBN (002) were confirmed, and their existence was confirmed. Furthermore, when we measured the Vickers hardness of this BN film, we found that
We were able to obtain a significantly large value of 6900Kg/mm ² . Comparative Example 1 In the above-mentioned Example 1, a film was formed with a thickness of 2 μm for 2 hours under the same conditions as in the Example except that no bias was applied to the substrate and B/N was set to 10. BN
A film was formed. When the BN film thus obtained was analyzed by X-ray diffraction, peaks that could be identified as CBN (111) and WBN (002) were confirmed. Furthermore, when the Bitkers hardness was measured, a value of 4850 Kg/mm ² was obtained. In the comparative example, when calculating the B/N ratio, the amount of nitrogen component supplied from the atmosphere is not included, and is calculated only from irradiated ions. On the other hand, in Example 1, the ion current is the sum of the irradiated ions and other low-energy ion species, so the ion current is 5 to 6 times higher than that of the comparative example, reaching a value that is actually involved in the reaction. There is. Therefore, even if the reaction when synthesizing CBN or WBN is about the same in Example 1 and Comparative Example, the former will be 1.5 and the latter will be 10 when expressed in terms of the B/N ratio parameter of the synthesis conditions. The only difference is that the activated atmosphere is actively BN to a lower energy level.
By allowing it to participate in film formation, we were able to achieve better quality and improve hardness. Example 2 Change B/N ratio (bias voltage -1.0KV)

[Table] BN films were formed by changing the B/N ratio in Experiment Nos. 1 to 8 (other conditions were the same as in Example 1). The results are shown in Table 1. If the B/N ratio exceeds 10, the electrical resistance and hardness will decrease, and if the B/N ratio is lower than 0.2, the formation of HBN will become significant and the hardness will decrease. Example 3 Difference in ion current due to presence or absence of bias

[Table] Experiment numbers 1 to 4 applied a bias voltage of 0 KV, experiment numbers 5 to 8 applied a bias voltage of -1.0 KV,
Table 2 shows the changes in ion current when the N ₂ ⁺ ion acceleration voltage was varied from 25 to 40 KV. It can be seen that approximately five times as much current flows by applying a negative bias. It can be seen that this significantly increases the film formation speed. Example 4 Effect of temperature Using TiC-TiN cermet, ionic species
35KeV, bias voltage 1.0KV and B/N ratio 1.5
A BN film was formed in the same manner as in Example 1 except that the temperature of the substrate was changed. The results are shown in Table 3.

【table】 [Brief explanation of drawings]

The attached drawing is a layout diagram of the BN film manufacturing apparatus used in the present invention. 2... Ion source, 7... Substrate, 10... Evaporation source, 14... Arc discharge chamber, 15... Bias power supply.

Claims (1)

[Scope of Claims] 1. Depositing a boron component onto a substrate from an evaporation source containing boron, and irradiating the substrate with ion species from an ion generation source that generates ion species containing at least nitrogen. A method for manufacturing a boron nitride film in which boron nitride is produced on the ion species, the ion acceleration energy of the ion species being 5 to 100 KeV per atom of the ion species, and the deposition and irradiation being performed at a lower energy level than that of the ion species. 1. A method for producing a high-hardness boron nitride film, characterized in that the process is carried out in an atmosphere of activated nitrogen atoms or nitrogen compounds, and at the same time, a negative bias voltage is applied to the substrate. 2. High hardness boron nitride according to claim 1, wherein the atomic ratio of boron to nitrogen contained in the evaporation source and the ion species (B/N) is set to 0.2 to 10. Membrane manufacturing method. 3. The method of manufacturing a high hardness boron nitride film according to claim 1, characterized in that the temperature of the substrate is set at -200 to 700°C. 4 The irradiation of the ion species is carried out at a temperature of 0.01 to 20 W per 1 cm ² of heat generated in the substrate due to the irradiation of the ion species.
2. The method of manufacturing a high hardness boron nitride film according to claim 1, wherein the method is set so that