JPH02254168A - Production of boron nitride - Google Patents

Abstract

PURPOSE:To increase BN-forming velocity and c-BN content by forming a plasma by using NaBH4 and N2 or NH3 as raw materials and also using high frequency induction heating together with heat filament heating in a plasma CVD method. CONSTITUTION:A raw-material compound consisting of a mixture of NaBN4 and N2 or NH3 is prepared. Boron nitride is deposited on a base material by using the above raw-material compound by a plasma CVD method. At this time, as a means of forming plasma, high frequency induction heating and heat filament heating are combinedly used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing boron nitride by so-called cVDt. This boron nitride (BN) is cubic boron nitride (
(hereinafter referred to as c-BN) or BN containing this, and is used for semiconductor heat dissipation substrates, corrosion-resistant and wear-resistant coating materials for mechanical parts, cutting materials, etc.

[Conventional technology]

BN includes soft hexagonal boron nitride (hereinafter referred to as hBN) and highly hard c-BN. CBN has been obtained by processing h-BN at high temperature and high pressure for a long time.
In recent years, a method of manufacturing from boron-containing a-compounds using the CVD method has also been proposed.

The method conventionally known as the CVD method uses polyamino polymer, borane, diborane, tetraborane, B
Cρ3, B3N3H6, etc. are known, and microwave, high frequency, arc discharge, hot filament methods, etc. are known as CVD methods (Japanese Unexamined Patent Publications No. 60-81009, No. 62-184869, No. 62-40376, No. 60). -5
874.11i161-174378, 631998
71).

[Problem to be solved by the invention]

This means increasing the c-BN content, increasing the BN production rate, and ensuring that the raw material compounds are non-toxic and easy to remove.

In addition, when depositing BN in a film form on a substrate and using it for semiconductor heat dissipation substrates, cutting tools, and wear-resistant mechanical materials,
It is important that the BN film on the substrate adheres closely and does not peel off easily.

The conventional methods described above have not yielded satisfactory results in these respects.

One object of the present invention is the production rate of BN and c-B in it.
The object of the present invention is to produce BN with a high aG-ratio of H and high adhesion of the BH film to the substrate.

[First Step to Solve the Problems] The present invention was developed as a result of searching for various raw material compounds and researching the plasma conversion method for producing BN by the plasma CVD method. BN is deposited on the substrate I- by a plasma CVD method that uses a mixture of NaB H4 and N2 or N H3 and a combination of high-frequency induction heating and hot filament heating as a plasma conversion method. It's a method.

NaBH4 has a melting point of about 4()0°C, and is heated to evaporate, mixed with N2 or NH3 gas, and turned into plasma. The mixing ratio expressed as the atomic ratio of B and N is in the range of 0.1 to 0.9, preferably 0.3 to 0.9.
It is 7. When using N2 gas, N a B H4
It is desirable to further mix hydrogen gas into the mixed gas so that the atomic ratio of N and H is about 1:3. N H3
The gas decomposes and generates nascent hydrogen gas, which is BN.
It is thought that N2 is involved in the production of N2.
Alternatively, better results have been obtained in that the production L1 of BN is higher than when using a mixed gas of N2 and N2.

A suitable mixed gas pressure is 1.0 to 640 Pa.

High-frequency induction heating for generating plasma is a well-known method, and the frequency is, for example, 13.5 GMIIz, and the output varies depending on the size of the device, but in the device of the example described later, it is 50 to 20
0W is suitable. Together with the heating of the hot filament, the plasma temperature is maintained at a high temperature.

A tungsten filament is usually used as the hot filament, and its temperature is suitably 1300 to 2100°C, preferably 1500 to 1900°C. The hot filament converts hydrogen in the raw material gas into atomic hydrogen, etc. This is necessary to make zeta-like hydrogen, and although the effect of this hydrogen is not clear, unless a hot filament is used, BN, especially BN with a high content of c-BN, will not be produced. In addition, the hot filament alone does not generate enough plasma, and similarly the generation of BN is small.

The substrates on which BN is deposited are St, W, Mo, and T.
Metals such as a, ceramics such as SiC sintered bodies, Si3N4 sintered bodies, cemented carbide chips, cermet, etc. can be used, and the shape can be plate-shaped (substrate), curved, or cylindrical without any restriction. can.

The temperature of the substrate is suitably 300-1000°C, preferably 500-900°C.

Next, one example of an apparatus for implementing the present invention will be shown and specifically explained. Figure 1 is a schematic cross-sectional view showing a raw material 4 in a quartz tube 1.
(N a B H4), an Si substrate 6 is provided. In the figure, N a B H4 is heated and evaporated using the filament 2, but a separate heating device for evaporation is provided.
The filament may be brought closer to the substrate.

A heating furnace 7 is provided outside the quartz tube to adjust the temperature of the substrate and the temperature inside the quartz tube. 3 converts gas into plasma using an i4% frequency coil. It is also possible to move this coil closer to the substrate than the one shown. 8 is a high frequency power supply, 9, 1
0 is an AC power source.

Quartz'=g is housed in a case adjusted to a predetermined pressure. A gas such as NH3 is flowed into the quartz tube from the gas inlet 5 of the case, mixed with the evaporated NaBH4 gas, turned into plasma, and deposited on the substrate as BN.

Exhaust gas exits from the other end of the quartz tube and is discharged through the exhaust gas of the case.

By the method of the present invention, the production rate of BN is determined by the film thickness from 0 to 0.
The number of people per minute is several times that of B2H6, which is the most commonly used raw material. Also c-BN
The average 3-hitting rate is 50-80%, which is higher than that of conventional methods, and by increasing the high-frequency output, it can be further improved to 80%.
It is also possible to go back to 0% twice.

Another feature of the present invention is that the density between the substrate and the BN film is high. This is advantageous when the film is used with the film attached to the substrate. The BN of the Ikemizu invention can also be separated from the substrate, crushed, and used as grinding abrasive grains.

[Example, comparative example]

An experiment was conducted using the apparatus shown in FIG. The quartz tube has a diameter of 2.7cm5
The length is 18cm. N H3 gas is 3 fl 1 minute CNT
(converted to P). The temperature of the Tangste Schiff 5 filament was 1800°C, and the high frequency output was 150W. A Si wafer is used as the substrate, and its temperature is 800℃.
And so. The amount of evaporated residue of N a B I (4) is thought to be 3 f!/min (N T P replacement valve) from the weight loss before and after the experiment, and the N/B atomic ratio is 1. is 2[]Pa.

Under this condition 0.51. The large-scale experiment continued during Ii. For comparison, NaBH was removed from the quartz tube and 821:'i63 was used instead.
0% SN H8096, H21,09b (capacity 9 each
The experiment was carried out in the same manner as in Example 1, except that 6 fl 1 minute (NTP equivalent) of the mixed gas of 6) was supplied to the quartz tube. These results are shown in Table 1.

(Margins below) 0 in the table indicates that no peeling was observed in the scratch test.
△ indicates that there was some peeling in the same test.

〔effect〕

According to the present invention, the rate of BN generation is variable.

The c-BH content in BH is high. The degree of adhesion between the BH film and the substrate is high. Moreover, the BH film is dense. Therefore, it will not get scratched even if you scratch it with a carbide ballpoint pen.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing one example of an apparatus used to carry out the method of the present invention. 1. Quartz tube 2. Filamen] 3.
・High frequency coil 6...Si substrate

Claims (1)

[Claims] In a method of depositing boron nitride on a substrate from a raw material compound by plasma CVD method, N is used as a raw material compound.
A method characterized by using aBH_4 and N_2 or NH_3 and using high frequency induction heating and hot filament heating together as a plasma generation method.