JPS6184379A - Production of high-hardness boron nitride film - Google Patents

Abstract

PURPOSE:To produce efficiently a high-hardness BN film on the surface of a base body by installing the base body in a reaction chamber, introducing a gas for forming BN into the chamber, generating plasma and projecting laser light thereby accelerating the bond between B and N. CONSTITUTION:An N-contg. gas such as N2 is introduced through the 1st introducing pipe 4 into the reaction chamber 1 in which a magnetic field is applied by a coil 2 for an electromagnet. A microwave is introduced at the same instant through a waveguide 3 into the chamber to generate the plasma. A voltage is impressed to the plasma by an ion accelerating electrode 13 consisting of an earth electrode 14 and a bias electrode 15 to form an ion beam in a deposition chamber 5. Said beam is irradiated to the base body 7 on a sample base 6. A B-contg. gas such as B2H6 is ejected toward the body 7 from the 2nd introducing pipe 8 at the same instart to grow the BN in a vapor phase on the body 7. The laser 10 in a 7.5-12mum wavelength region is scanned from a laser light projecting source 9 on the body 7 via an introducing window 11 and a reflecting plate 12. The high-hardness BN film consisting essentially of CBN and WBN is thus formed on the base body 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a boron nitride film (hereinafter, boron nitride is abbreviated as BN) that achieves high hardness using laser light.

[Industrial application field]

BN has the following crystal structures: cubic boron nitride (hereinafter abbreviated as CBN), hexagonal close-packed boron nitride (hereinafter abbreviated as WBN), and hexagonal boron nitride (hereinafter abbreviated as HBN).
Among these, CBN and WBN are attracting attention for a variety of wide-ranging applications due to their excellent thermal shock resistance, thermal conductivity, hardness and wear resistance, as well as resistance to iron group metals at high temperatures. Research is being conducted on manufacturing methods for high-quality CBN and WBN.

[Conventional technology]

As a well-known manufacturing method, there is a method that uses expensive equipment and can be synthesized under ultra-high pressure and ultra-high temperature of tens of thousands of atmospheres and tens of hundreds of degrees Celsius, but recently, vapor phase growth method has been used to efficiently coat the surface of the substrate. Research has also been conducted into synthesizing CBN and WBN and producing thin films thereof.

[Problem that the invention seeks to solve]

Plasma CVD method, reactive ion blating method, etc.
Therefore, the synthesis of CBN and WBN has not been reported yet, and recently, relatively high quality CBN has been produced using ionization synthesis method.
There are only reports that a film of or WBN could be synthesized. According to this ionization synthesis method, a CBN or V/BN film can be formed on the substrate by evaporating boron by electron bombardment and simultaneously irradiating it with nitrogen ions. be.

[Means to solve the problem]

In addition to the previously proposed ionization synthesis method, the present inventor has discovered that CBN
In developing a new vapor phase growth method suitable for the synthesis of BN and WBH, as a result of intensive research, we found that high hardness BN can be produced by utilizing electron cyclotron resonance excited plasma and supplying energy by projecting laser light into the plasma. It was discovered that a film could be formed.

The present invention was completed based on the above knowledge, and its purpose is to support CBN and WBI! The object of the present invention is to provide a new method for producing a high hardness BN film by efficiently synthesizing the J film.

Another object of the present invention is to further improve the hardness properties by promoting the production of CBN and vllBN, and to
- To provide a method for forming a film on a substrate at a high film formation rate.

According to the present invention, BN is added to the reaction chamber in which the substrate is installed.
CBN is deposited on the surface of the substrate by chemical vapor deposition by introducing a generation gas and generating plasma inside the reaction chamber.
A method for producing a BN film that produces high hardness BN, characterized in that a laser beam is projected into the plasma inside the reaction chamber to promote the bonding of boron atoms and nitrogen atoms.
A method of making a membrane is provided.

The present invention will be explained in detail below.

In the present invention, a BN film is formed using an electron cyclotron resonance discharge device shown in FIG. It is characterized by the fact that it supplies energy.

In Figure 1, an electromagnetic coil (2) is placed outside the reaction chamber (1) to apply a magnetic field inside the reaction chamber (1), and microwaves (2.45 GHz) are transmitted through the waveguide (3). The lever is introduced into the reaction chamber (1). According to this device, when using a nitrogen atom-containing gas and a boron atom-containing gas as the BN generating gas, a nitrogen atom-containing gas such as N2 or NHs (hereinafter abbreviated as N-containing gas) is introduced into the first inlet pipe (4). ) is introduced into the reaction chamber (1) at the same time, electron cyclotron resonance occurs, and the electrons collide with the N-containing gas and discharge,
A plasma is generated, and an ion accelerating voltage is applied to the plasma to form an ion beam in the deposition chamber (5), and the ion beam is irradiated onto the substrate (7) placed on the sample stage (6). BIH6, (
A boron atom-containing gas (hereinafter abbreviated as B-containing gas) such as C2Hb)aB, BCJa, and ``BBrs'' is ejected through a second introduction pipe (8) provided in one part of the precipitation chamber (5). and CBN and W'BN are this substrate (7)
This is grown in the vapor phase. During this vapor phase growth, laser light αω having a predetermined wavelength range is introduced from the laser light source (9) into the precipitation chamber (5) through the laser light introduction window (111), and this laser light 0 Plasma atmosphere (for irradiation, it is preferable to scan the surface of the substrate (7) by reflecting it with a reflection plate [13] having a scanning function.

That is, the cyclotron frequency f of electrons causes cyclotron motion based on the electric charge (B: magnetic flux density), and when this frequency f matches the frequency of microwaves (2.45 GHz), it resonates, and as a result, the electron collides with molecules, ions, and radicals of the N-containing gas, and the highly excited state discharge phenomenon increases significantly, further increasing the ionization rate in the plasma.

Since the plasma ion density is thus high, the gas pressure can be set to 10 to 10 torr, and the pressure can be significantly reduced compared to the ionization synthesis method, so a plasma of high purity and high ion density is generated.

In the present invention, the plasma generated in the reaction chamber (1) as described above is turned into an ion beam in the deposition chamber (5) and is made to collide with the substrate (7) installed on the sample stage (6). It is important to blow out the contained gas toward the substrate (7) at a predetermined flow rate. In other words, the ion accelerating electrode 11 (
By applying a bias voltage to the ion accelerating electrode (support), an ion accelerating voltage is applied to the plasma. It consists of a porous bias electrode (113) that partitions the room (5) and serves as the ion beam emission site. It is recommended to apply the bias voltage within the range.If this bias voltage is less than 50V, the CB
The characteristics of CBN and WBN in the BN film formed on the substrate become small due to a lack of nitrogen source necessary for the generation of N and WBN, and when the voltage exceeds 5000 V, the film formation rate decreases and production efficiency deteriorates. . Therefore, this bias voltage is between 50 and 5000 V, preferably between 200 and 1000 V.
Good. Then, the positive ions of the plasma are irradiated with an ion beam onto the base (7), thereby forming a CBN@W
The nitrogen source for BN production becomes high energy, and the substrate (7)
At the same time, the B-containing gas flows into the second inlet pipe (8).
When ejected onto the base (7) through CBN, WB
In order for N to be synthesized, each of the N atom and B atom is SP
It becomes a highly excited state with a hybrid orbital.

In order to efficiently synthesize CBN and WBN from N atoms and B atoms with such SP hybrid orbitals, a reaction chamber (
It is important to specify the atomic ratio of N atoms and B atoms contained in each of the N-containing gas and B-containing gas introduced into 1) and the precipitation chamber (5). It is preferable to set the atomic ratio of atoms to be in the range of 1/10 to 10 2 , and if it deviates from this setting range, the content of CBN or WBN will be considerably reduced during precipitation. It has been experimentally confirmed that this optimum condition is in the range of 1/2 to 3.

The substrate (7) needs to be maintained at a temperature within a predetermined range during the precipitation of BN, so that the CBN and WBN grown in a vapor phase can be adhered to the substrate (7) while maintaining their structures. The substrate temperature is preferably between -100 and 500°C; outside this range, the amount of amorphous and hexagonal BN increases, resulting in a high-quality N film made of CBN or WEN. The temperature is preferably 0 to 250°C.

Note that (1G) is an outlet for exhaust gas that is no longer needed for the production of CBN and WBN.

Furthermore, in the present invention, it is important to project a laser beam having a predetermined wavelength range into the plasma atmosphere in order to efficiently synthesize CBN and WBN from N atoms and B atoms having SP hybrid orbitals as described above. It is.

That is, the inventor has determined that the wavelength range of this laser light is from 7.5 to
It was found that when the thickness was set within the range of 12 μm, BN formed at a high film formation rate exhibited remarkable high hardness characteristics, and
When projecting this laser light into the plasma atmosphere,
It is desirable to irradiate laser light toward the substrate (7) so that it can be deposited along with BN bonding.

It can be seen that such a wavelength region corresponds to the absorption peak of the infrared absorption spectrum of CBN and WBN, as shown in FIG. Therefore, it is considered that this laser light serves as a source of bonding energy for N atoms and B atoms, and promotes the bonding reaction.

This BN bonding reaction can be explained as follows with reference to FIG.

a indicates the unbonded energy potential of B atoms and N atoms with SP hybrid orbitals, and when the activation energy ET is supplied by repeated laser beam irradiation, the energy potential exceeds the energy potential of X without producing CBN or WBN. It becomes a BN bond of b. However, if inappropriate activation energy E is supplied, it is thought that the energy potential C will exceed the energy potential Y and result in HBN. In other words, N
In order for atoms and B atoms to combine to form OBN and WBN, it is necessary to overcome the activation energy barrier of E7. However, with conventional excitation methods, such as heating and plasma ionization, all degrees of freedom of the reacting molecules, i.e., translational motion and internal energy level, are uniformly excited and the reaction occurs. Therefore, in addition to the generation of CBN and WBN, HBN is also generated. On the other hand, if a laser beam with good monochromaticity is used, the level at which the molecule is excited can be selected, so it becomes possible to directly excite the internal energy level of the molecule using the laser's light energy. Therefore, it is necessary to irradiate a laser beam having a wavelength range of 7.5 to 12 ttm, which corresponds to the activation energy E7, and the present inventor has experimentally determined that the optimal wavelength range of the laser beam is 9 to 10 μm. It was confirmed by

In the present invention, the above-mentioned laser beam is 7.5~
Any laser having a wavelength range of 12 μm can be used, such as CO+l gas laser, E(F' gas L/- laser, Pb5nTe, Pb5nSe
, Hg, CI're, Pb5nSeTe, P
There are semiconductor lasers such as b5nsse.

〔Effect of the invention〕

Thus, according to the method for manufacturing a high-hardness BN film according to the present invention, while setting the N atoms contained in the N-containing gas to a predetermined atomic ratio, an electron cyclotron is used to cause the gas to collide with electrons by sounding to cause a discharge. This method efficiently generates high-purity plasma, forms an ion beam with a large beam diameter from this plasma, irradiates high-energy positive ions onto a substrate at a set temperature, and at the same time irradiates B atoms in a predetermined range. The B-containing gas contained therein is ejected to the substrate,
Furthermore, by irradiating the laser beam having a predetermined wavelength range, a highly hard N film made of CBN or WBN can be formed at a high film formation rate.

Furthermore, since the substrate was heated by ion beam irradiation,
Not only is there no longer a need for a heat source to heat the substrate, but also no heat source for plasma generation such as a filament is used, so the formation of a high-hardness BN film is not hindered by defects in the heat source, and stable production can be maintained. also has
As a result, high hardness B suitable for mass production and highly reliable
We were able to provide a method for manufacturing N membrane.

Next, examples of the present invention will be described.

[Example 1] Using the above-mentioned electron cyclotron resonance type discharge device,
First, N2 gas was introduced at a flow rate of 0.1 through the first introduction pipe (4).
m1i- was introduced into the reaction chamber (1). As a result, when the pressure inside the reaction chamber (1) is always set at 10 torr, a magnetic field is applied inside the reaction chamber (1) by the electromagnetic coil (2), and a microwave (2-45GHH) is applied.
z) into the reaction chamber (1) via the waveguide (3),
Generates electron cyclotron resonance plasma. Next, by applying a bias voltage of 900 V to the ion accelerating electrode (j3), an ion beam is formed, and when this ion beam is irradiated onto the silicon substrate (7), an 82F ( 6 gases at a flow rate of 0.05 t
It was introduced into the precipitation chamber (5) at a rate of nl/m. In this case, the atomic ratio of N atoms to B atoms is 2. Furthermore, 9.6 μF is generated from the laser projection source (9) consisting of a CO2 gas laser.
A laser beam having a wavelength of 71 is projected onto the reflector u3 with the output power shown in the first table, and the laser beam is scanned over the surface of the substrate (7) while operating the reflector 0 for scanning. I strained it by 1.

When the thus 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.

The film formation rate and Vickers hardness Hv were as shown in Table 1.

Table 1 Samples marked with ・are outside the scope of the present invention.

As is clear from Table 1, by irradiating with laser light, the film formation speed and hardness were significantly increased compared to sample number 9 (no laser light was irradiated and all other manufacturing conditions were kept the same). It can be seen that it has improved.

[Example 2] A semiconductor laser having the wavelength shown in Table 2 was used with an output power of 35
A BN film was formed using the same manufacturing conditions as in Example 1, except that a laser projection source was set at 0 mw/ea l.

When the BN film thus obtained was analyzed by X-ray diffraction, OBN (111) was found for sample numbers 11 to 14.
A peak that could be identified as WBN (002) was confirmed, and its existence was confirmed. Furthermore, the Vickers hardness HV of these films is as shown in Table 2.

Table 2 From Table 2, it can be seen that all the samples exhibit remarkable high hardness characteristics, and sample No. 12.13 has extremely high hardness, indicating that it is an N film.

As described above, the method for producing a high-hardness BN film of the present invention utilizes electron cyclotron resonance excited plasma and further uses an appropriate energy supply method using laser light to produce a high-quality BN film made of OBN or WBN. The film could be formed on the substrate at the same speed.

Note that the present invention is not limited to the above-mentioned method for producing a BN film using electron cyclotron resonance excited plasma, and may include ionization synthesis methods, unless the gist of the present invention is exempted.
It is obvious to those skilled in the art that this method can also be applied to other BN film manufacturing methods such as ion blating and sputtering.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of an electron cyclotron resonance discharge device for forming cubic boron nitride (CBN) and hexagonal close-packed boron nitride (WBN), and Figure 2 is a diagram showing the infrared absorption spectra of CBN and wBN. , Figure 3 shows boron CB)
FIG. 2 is a diagram showing the energy potential of a bonding reaction between nitrogen (N) and nitrogen (N). (1) Reaction chamber (2) Electromagnet coil (3) Waveguide (4) First introduction pipe (5) Precipitation chamber (7)・Base (8)...Second introduction pipe (9)...Laser light source

Claims (3)

[Claims] (1) Boron nitride, in which boron nitride generation gas is introduced into a reaction chamber in which a substrate is installed, and plasma is generated inside the reaction chamber to generate boron nitride on the surface of the substrate by chemical vapor deposition. 1. A method for producing a high hardness boron nitride film, the method comprising: projecting a laser beam into the plasma inside the reaction chamber to promote bonding between boron atoms and nitrogen atoms. (2) The method for producing a high hardness boron nitride film according to claim 1, wherein the laser beam is within a wavelength range of 7.5 to 12 μm. (3) The method for producing a high hardness boron nitride film according to claim 1, wherein the plasma is generated by electron cyclotron resonance discharge using microwaves.