JPS5917190B2 - Formation method of boron film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to provide a method for forming a honey-uniform boron film having excellent mechanical properties such as a large elastic modulus on the surface of a heated substrate.

Chemical vapor deposition methods, in which boron is deposited on heated surfaces from gas mixtures containing boron compounds, such as boron trichloride or boron tribromide, are known and have gained in importance in recent years.

Pure boron separated from the gas phase in this way is important in the semiconductor industry and is also needed for wear-resistant coatings, acoustic materials, etc., and is used in threads produced by separating boron on tungsten. is useful as a reinforcing material for construction materials that are subject to heavy loads. All conventional chemical vapor deposition methods for forming boron films are performed using the following reaction.

2BX3+3H2→2B+6HX [In the formula, There is a low-pressure chemical vapor deposition method, which is superior to the normal-pressure chemical vapor deposition method in terms of the boron deposition rate, and in terms of the film thickness distribution and film quality of the produced film.

That is, when focusing on the quality of the film, including mechanical properties such as elastic modulus, it is possible to obtain a high-quality film by producing the film to the desired thickness using only the low-pressure chemical vapor deposition method. When using low pressure chemical vapor deposition, the film growth rate is considerably slower than when using normal pressure chemical vapor deposition.
The drawback was poor productivity. Another conventional method is physical vapor deposition, such as electron beam heated evaporation or sputter evaporation.

In the above method, the adhesion force to the substrate is weak, the bond between the crystal particles constituting the coating is weak, and the rate of deposition of boron onto the substrate is slower than in the chemical vapor deposition method. Therefore, the produced boron coating lacked honey properties and did not have sufficient mechanical properties such as elastic modulus. As described above, in the conventional method, the productivity of the coating is insufficient, the quality of the produced coating is insufficient, the abrasion resistance is insufficient, and the specific modulus of elasticity is not sufficient as a material for an acoustic component.

An object of the present invention is to provide a method for forming a boron film that eliminates the drawbacks of the above-mentioned conventional methods and is more productive.

Examples of the heather invention will be described below. First, the atmospheric pressure chemical vapor deposition method and the reduced pressure chemical vapor deposition method will be explained.

The precipitation reaction of boron to be used is based on the above-mentioned reaction formula, and normal pressure chemical vapor deposition is carried out in a normal pressure atmosphere, and reduced pressure chemical vapor deposition is carried out in an atmosphere having a degree of vacuum below normal pressure. In the method according to the present invention, the process of producing boron on a substrate consists of a first process of producing boron using a reduced pressure chemical vapor deposition method, and a second process of producing boron using an atmospheric pressure chemical vapor deposition method, A method for producing a boron film, characterized in that boron is produced on the substrate in a first step, and then, in a second step, boron is produced on the boron layer produced in the first step. be.

In the present invention, the raw material gas is a mixture of gaseous compounds, at least the gaseous compound containing boron.

Next, the heather invention will be specifically explained.

The figure is an example of a schematic configuration diagram of a chemical vapor deposition apparatus for carrying out the present invention. In the figure, 1 is a reaction vessel, 2 is a substrate, 3 is a heater for heating the substrate, 4 is a raw material gas introduction port, 5 is an exhaust port, 6 is a vacuum gauge, 7 is a flow rate regulator, 8 is a cylinder, etc.
A storage section or generation section for each component gas constituting the raw material gas, 9 a cooling trap provided if necessary, 10, 11,
12 is a valve for switching between reduced pressure and normal pressure chemical vapor deposition;
13 is a vacuum pump. The heather invention will be specifically explained using figures.

First, close the valve 11, open the valve 12, start the vacuum pump 13, adjust the valve 10 and other valves such as a flow rate regulator, and adjust the flow rate of the raw material gas to the reactor 1, the degree of vacuum inside the reactor 1, etc. The mixture ratio of each component gas constituting the raw material gas is adjusted, and the material is further heated to a temperature profile determined based on Basic 2, and a reduced pressure chemical vapor deposition method is performed. The raw material gas flowing into the reactor is decomposed by the high temperature, and boron is deposited on the substrate 2.

If necessary, to remove oxides etc. on the surface of the base 2,
Prior to performing vacuum chemical vapor deposition, the substrate 2 is heated and H2 is introduced into the reactor. After forming a boron layer of an appropriate thickness on the substrate by the reduced pressure chemical vapor deposition method, the valves 10 and 12 are formed.
, open the valve 11, adjust the flow rate of the raw material gas to the reactor 1, and the mixing ratio of each component gas constituting the raw material gas,
Furthermore, the substrate 2 is heated to a defined temperature profile to perform atmospheric pressure chemical vapor deposition.

In this way, boron is newly deposited on the boron layer formed by the reduced pressure chemical vapor deposition method. By doing this, as mentioned above, the deposition rate of the boron film is slow in the low pressure chemical vapor deposition method, and the quality of the produced film is insufficient in the atmospheric pressure chemical vapor deposition method, and the overall production rate of the boron film is improved. However, it has now become possible to obtain a boron film that is sufficiently large and of good quality.

Moreover, in the method according to the present invention, it is more preferable that switching between the reduced pressure chemical vapor deposition method and the normal pressure chemical vapor deposition method is performed continuously in the same atmosphere.

That is, when a film is formed by low-pressure chemical vapor deposition, then taken out into the air and then subjected to normal-pressure chemical vapor deposition again, the effect of the heather invention is small, and at the time of switching,
It is not preferable to lower the substrate temperature, nor is it preferable to rapidly increase the gas amount. The effect of the present invention was observed when the thickness of the boron layer formed by the above-mentioned reduced pressure chemical vapor deposition method was about 1000 Å or more.

In addition, from the viewpoint of the formation rate of the boron layer according to the present invention,
The deposition time of boron on the substrate by vacuum chemical vapor deposition should be short, and therefore a reasonable thickness of the boron layer by vacuum chemical vapor deposition was about 0.01 to 1 μm. (Upper limit is 1
The reason why the value is μm is because the deposition rate of the film is slow in the reduced pressure chemical vapor deposition method, so it is meaningless to use more than this value. ) According to the present invention, a boron coating having excellent mechanical properties such as a homogeneous film with honey and an elastic modulus equal to or higher than that of the conventional film and an even greater adhesion to a substrate has been obtained. Moreover, the rate of formation of the boron film was almost the same as that of the conventional method.
The above can be considered as follows.

That is, by low-pressure chemical vapor deposition, a honey-uniform boron coating with a suitable thickness, strong adhesion to the substrate, and excellent mechanical properties such as elastic modulus is formed on the substrate.
When boron is deposited only by reduced pressure chemical vapor deposition,
This effect was obvious. Thereafter, a boron coating is formed by atmospheric pressure chemical vapor deposition at a considerable deposition rate. In other words, the overall rate of formation of the boron film is almost the same as that of the conventional method, and the boron layer formed by atmospheric pressure chemical vapor deposition on a uniform honey film is faster than that of other types of substrates. Compared to the boron layer deposited on top, it appears to be more uniform in honey and have superior elastic modulus. As the raw material gas, a mixture of gaseous compounds can be used, at least the gaseous compound containing boron, but preferably a mixed gas of boron trichloride BCl3 and hydrogen H2, a mixture of boron tribromide BBr3 vapor and H2 Gas, mixed gas of BBr3 vapor and argon Ar etc. as carrier gas, BCl3
A single gas or a mixed gas of a hydride such as diborane and Ar as a carrier gas is used.

When the mixed gas was composed of BCl3 and H2 from the viewpoint of ease of handling and the properties of the obtained boron film, the preferred flow ratio was 1:20 to 1:1.

In the case of the present invention (in terms of film properties and formation rate), the degree of vacuum in the reactor is between 500T0rr and 0.5T0rr in the case of reduced pressure chemical vapor deposition.
It was 1T0rr.

A degree of vacuum in this range can be obtained in a short time using ordinary equipment, resulting in high productivity, and is also suitable for forming chemical vapor deposition films. In view of the film quality, adhesion force, elastic modulus, etc. of the obtained boron coating, it was more preferably 20T0rr to 0.1T0rr. In the case of atmospheric pressure chemical vapor deposition, the reactor was, of course, at atmospheric pressure. Methods for heating the base material include heating using the Joule heat of a heater, heating using an infrared lamp, high-frequency induction heating, or, if the base is metal, heating using the own Joule heat by passing an electric current through the base. Alternatively, an appropriate method was used depending on the material.

A suitable substrate temperature was 800°C to 1100°C.

In the present invention, in the process of low pressure chemical vapor deposition, 800°C to 90°C
In the process of 0℃, normal pressure chemical vapor deposition, the temperature is 900℃~1100℃.
℃ was more preferable in terms of film properties and deposition rate. Here, the temperature was set at 800°C to 900°C in the process of low-pressure chemical vapor deposition because if the temperature is lower than 800°C, the deposition rate will be low, productivity will be poor, and the strength of the deposited film will be reduced. This is because if the temperature is high, the reaction with the substrate will be large and the smoothness and strength of the deposited film will deteriorate. In addition, the temperature of 900°C to 1100°C in the atmospheric pressure chemical vapor deposition process was 9
This is because even if the temperature is lower than 00°C or higher than 1100°C, the deposition rate will be low and productivity will be poor. The base materials used in the present invention include carbon fiber, titanium, tungsten, molybdenum, tantalum, quartz nickel, copper,
It was platinum etc.

In this way, the boron membrane obtained by the present invention was honey-free, void-free, and void-free compared to that of the conventional method.

Furthermore, in terms of mechanical properties, those according to the heather invention are equivalent or superior. For example, the elastic modulus was approximately 10 (Ff) or more greater than that obtained by conventional chemical vapor deposition. It was about 15% larger than that by sputter first physical vapor deposition. Furthermore, the boron film formation rate is almost the same as that of conventional chemical vapor deposition, and is much faster than that of physical vapor deposition.

In the case of the present invention, the adhesion force of the precipitated boron to the substrate is as follows:
The results were comparable and superior to those obtained by conventional chemical vapor deposition.

The adhesion force of the physical vapor deposition method is considerably inferior to that of the present invention. The present invention has been described above mainly with reference to the drawings, but the present invention is not limited thereto.
As described above, the heather invention had a large adhesion force to the substrate and excellent mechanical properties such as elastic modulus.

A uniform boron coating with no pores can be obtained,
Moreover, it is possible to provide a method for forming a boron coating that is productive, and the present invention will make a great contribution in the fields of wear-resistant coatings, acoustic components, etc.

[Brief explanation of drawings]

The figure is a schematic diagram of an apparatus for carrying out the boron film forming method of the present invention. 1...Reaction container, 2...Substrate, 3...
... Heater 4 ... Raw material gas inlet, 5.
...Exhaust port, 6...Vacuum gauge, 7...
...Flow rate regulator, 8...Cylinder, 9...
- Cooling trap, 10, 11, 12... switching valve, 13... vacuum pump.

Claims (1)

[Claims] 1. The process of producing boron on a substrate is carried out at a vacuum degree of 500 To
A first step of generating boron using a reduced pressure chemical vapor deposition method at rr ~ 0.1 Torr and a base temperature of 800 ° C. ~ 900 ° C.;
It consists of a second process of producing boron using an atmospheric pressure chemical vapor deposition method with a substrate temperature of 900°C to 1100°C, in which boron is produced on the substrate in the first process, and then in the second process, A method for forming a boron film, characterized in that boron is further produced on the boron layer produced in the first step. 2. The method for forming a boron coating according to claim 1, wherein the thickness of the boron layer formed in the first step is 1 μm or less.