JPH0819523B2 - High hardness boron nitride synthesis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for synthesizing cubic boron nitride having high hardness,
In detail, not only has extremely high hardness, but also has high thermal conductivity, is chemically stable, and in addition to diamond,
Since it has excellent resistance to iron group metals, it relates to a method for depositing cubic boron nitride, which is used as a tool material for cutting tools, wear resistant tools, etc. is there.

<Prior Art> Conventionally, as a method for producing boron nitride, (1) a boron molecule is vapor-deposited on a substrate from an evaporation source containing boron, and at the same time an ion generation source for generating ion species containing at least nitrogen is formed on the substrate. And a method for producing a boron nitride film in which boron nitride is deposited on the substrate by irradiating the substrate with the ion species (JP-B-60-181262).

(2) Method for producing cubic boron nitride by chemically transporting boron by H ₂ + N ₂ plasma (Journa
l of material science letters 4, (1985), P51 ~ 5
Four).

(3) Hollow Anod while evaporating boron with HCD gun
A method of ionizing N ₂ from e and radiating it to the substrate, applying a high frequency to the substrate and producing a cubic boron nitride with a self bias effect (Proceeding, 9th, Symposium on Ion so
urce Ion Asisted Technology Anode 85, Tokyo (198
Five)).

(4) A method of forming cubic boron nitride on the surface of a substrate by exposing boron to a solid containing boron atoms to evaporate boron and then injecting a gas containing nitrogen atoms to simultaneously ionize boron and nitrogen. (Vacuum, Vol. 28, No. 7, 1985).

Are known.

<Problems to be Solved by the Invention> However, the above method (1) is disadvantageous in that the ion beam generating apparatus and the focusing apparatus are expensive, and the method (2) uses high-power RF plasma. Since it is used for film formation, impurities from the reaction system are easily mixed. Like the method (1), the method (3) has drawbacks that an apparatus for generating an ion beam and its focusing apparatus are expensive, and that atoms of an inert gas are taken into the deposited boron nitride. Further, in the method (4), since boron has a melting point and a boiling point close to each other, boron has a drawback that bumping is likely to occur and control is difficult by applying EB.

<Means for Solving Problems> The present invention has been found as a result of investigations to obtain a method for synthesizing boron nitride which solves the above-mentioned drawbacks of the conventional method.

That is, according to the present invention, a gas containing a boron atom and a gas containing a nitrogen atom are decomposed by an excimer laser CVD method and brought into an excited state, and then passed through a high frequency plasma to obtain 800
It is an object of the present invention to provide a method for synthesizing high-hardness boron nitride, which is characterized in that it is introduced into the surface of a substrate heated to ˜2000 ° C. to precipitate cubic boron nitride.

<Operation> In the present invention, a mixed gas of a boron atom-containing gas and a nitrogen atom-containing gas is passed through an excimer laser to be decomposed and excited to generate excited boron atoms and nitrogen atoms. Further, the excited boron atoms and nitrogen atoms are further passed through the high-frequency plasma to generate cubic boron nitride having a higher energy and on the heated substrate.

As described above, in the present invention, the excimer laser and the high frequency plasma are used as the film forming process.

In the above, when only the excimer laser or only the high frequency plasma is used as the film forming means, the reaction energy is insufficient to cause sp ³ bond between the boron atom and the nitrogen atom, which are the source materials, so that the amorphous nitriding is performed. Easy to make boron and hexagonal boron nitride.

On the other hand, when the two film forming means of the excimer laser and the high frequency plasma are used in combination, sufficient reaction energy can be obtained for the boron atoms and the nitrogen atoms to cause sp ³ bond with each other.

In the above, the excimer laser output is preferably in the range of 1 to 100 w. If it is less than 1 w, the film formation rate becomes very low, and it is insufficient to excite the source material.
If it is larger than 100w, the life of the medium gas is shortened, so that the output is significantly attenuated and a stable output cannot be obtained.

Next, the output of the high frequency plasma is preferably 100 w or more. This is because if it is smaller than 100 w, the energy is insufficient to cause the excited boron atom and the excited nitrogen atom to sp ³ bond with each other.

When the substrate temperature is lower than 800 ° C., the boron atoms and nitrogen atoms in the excited state are insufficient as thermal energy for sp ³ bonding to each other, and when the substrate temperature is higher than 2000 ° C., nitrogen escapes from the formed boron nitride film, 800 to 2000 ° C is preferable.

In the present invention, ArF, KrF, F ₂ gas or the like is used as the medium gas of the excimer laser used.

The ratio of the number of boron atoms in the boron atom-containing gas and the number of nitrogen atoms in the nitrogen atom-containing gas is preferably B / N = 0.1 to 10. This is because when B / N <0.1, an amorphous boron nitride film is likely to be deposited, and when B / N> 10, boron is excessive and amorphous boron is easily formed. .

Examples of the boron atom-containing gas include B ₂ H ₆ , BCl ₃ , BBr ₃ , B ₃ N ₃ H _{6 and the} like, and examples of the nitrogen atom-containing gas include N ₂ and NH ₃ .

In the present invention, when synthesizing high hardness boron nitride,
The manufacturing apparatus shown in the drawing or FIG. 2 as a schematic is used. 1 is a type in which the substrate is heated by a heater, and FIG. 2 is a type in which the substrate temperature can be adjusted by the plasma intensity because the substrate is positioned in the high frequency plasma.

In both figures, 1 is a boron atom-containing gas supply device, 2 is a nitrogen atom-containing gas supply device, 3 is an excimer laser generator, 4 is a reaction chamber, 5 is an excimer laser guide, 6 is an excimer laser, 7 is a substrate, and 8 is a substrate. Is a substrate support, 9 is a heater, 10 is a high frequency coil, 11 is a high frequency power supply, 12 is a cock, 13 is an exhaust device, and 14 is an exhaust port.

<Examples> The present invention will be described in detail below with reference to Examples.

Example 1 Using the manufacturing apparatus shown in FIG. 1, a silicon wafer was used as a substrate, and diporane and nitrogen were fed as source gases at 20 cc / min and 10 cc / min, respectively. Pressure in the reaction tube is 0.1 Tor
It was adjusted to r and the substrate temperature was set to 900 ° C. An ArF laser was used as the excimer laser, and the laser output was 20w. The high frequency is 13.56MHz, the high frequency output is 500w,
The film formation time was 4 hours.

After the film formation is completed, a boron nitride film of about 6 μm is deposited, and X
As a result of evaluation by line diffraction, a sharp peak was detected near 2θ = 43.2 °, and it was identified as cubic boron nitride.

Example 2 Using the manufacturing apparatus shown in FIG. 2, a silicon wafer was used as a substrate, and boron chloride and nitrogen were used as source gases, respectively.
Flowed at 8cc / min and 16cc / min.

The pressure in the reaction tube was adjusted to 0.3 Torr, and the substrate temperature was 1100 ° C.
did. Use a KrF laser as an excimer laser,
The laser output was 30w. The high frequency is 13.56MHz,
The high frequency output was 1 kw and the film formation time was 7 hours.

After the film formation, a boron nitride film having a thickness of about 12 μm was deposited, and when evaluated by Raman analysis, sharp peaks were detected near 1310 cm ⁻¹ and 1055 cm ⁻¹ , which could be identified as cubic boron nitride.

Example 3 The manufacturing apparatus shown in FIG. 1 was used.

Molybdenum was used as a substrate, and boron fluoride and ammonia were supplied as source gases at 10 cc / min and 30 cc / min, respectively. The pressure in the reaction tube was adjusted to 0.2 Torr, and the substrate temperature was 800 ° C. The excimer laser was not used as the film forming means, only the high frequency plasma was used, the high frequency frequency was 13.56 MHz, the high frequency output was 400 w, and the film forming time was 5 hours.

After the film formation is completed, a boron nitride film of about 5 μm is deposited and X
When evaluated by line diffraction, broad peaks were detected near 2θ = 26.7 ° and 43.2 °, respectively, and it was confirmed that the thin film was a mixture of hexagonal boron nitride and cubic boron nitride.

Example 4 A WC-based cemented carbide using the conditions of Examples 1 to 3 above.
Using TNMG432 as a chip, coating was performed on the chip and a cutting test was performed.

For comparison, uncoated tip and CV
A cutting test was also performed on the chips coated with TiN by method D.

All coatings had a coating layer thickness of 3 μm. The cutting test conditions are shown in Table 1. The results of the cutting test are shown in Table 2.

From the above table, it was found that when cubic boron nitride was used as a coating layer for the chip, all the examples of the present invention had excellent wear resistance.

Further, when the cutting performance of the CBN coated chip obtained by the present invention in steel turning was examined by the relationship between the cutting speed and the life time, the results shown in FIG. 3 were obtained, and further, the cutting time to impact and the number of impacts in cast iron cutting were obtained. The relationship shown in Fig. 4 was obtained and the results shown in Fig. 4 were obtained.

<Effects of the Invention> As described above, according to the present invention, a cubic boron nitride film excellent in thermal shock resistance, thermal conductivity, hardness, wear resistance and resistance to iron group metals at high temperatures is deposited from the vapor phase. It is a new synthesis method, and when it is used as a coating film for cutting members, wear-resistant members and heat-resistant parts, it has been found to show a great effect as shown in FIGS. 2 and 3.

[Brief description of drawings]

1 and 2 are schematic explanatory views of a manufacturing apparatus used in the method of the present invention, and FIGS. 3 and 4 are cutting of chips having a cubic boron nitride coating film obtained by the method of the present invention as a coating film. It is a chart showing performance. 1 ... Boron atom-containing gas supply device 2 ... Nitrogen atom-containing gas supply device 3 ... Excimer laser generator 4 ... Reaction chamber, 6 ... Excimer laser 7 ... Substrate, 9 ... Heater 10 ... High frequency coil , 11 …… High frequency power supply

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C23C 16/50 H01L 23/373

Claims (1)

[Claims] 1. A boron atom-containing gas and a nitrogen atom-containing gas are decomposed by an excimer laser CVD method to be in an excited state and then passed through a high frequency plasma to obtain 800
A method for synthesizing high-hardness boron nitride, which comprises introducing cubic boron nitride to the surface of a substrate heated to ~ 2000 ° C to precipitate it.