JP2603919B2 - Method for producing boron nitride film containing cubic boron nitride crystal grains - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a boron nitride film, particularly a high hardness boron nitride film containing cubic boron nitride crystal grains.

[Conventional technology]

As a conventional method of fabricating a boron nitride film, when depositing metallic boron on a substrate, a part of the evaporated substance is ionized in a nitrogen gas atmosphere, and energy is given to this by an electric field, and this is not ionized. Ion plating method to deposit on the substrate together with other evaporates, CVD method to decompose and activate boron-based and nitrogen-based gas molecules in the chamber by means such as thermal excitation, and deposit this on the substrate There is.

[Problems to be solved by the invention]

However, in conventional methods such as ion plating and CVD, it is known that cubic boron nitride crystal grains are not included in the produced boron nitride film. There is a problem that a boron nitride film cannot be obtained.

Accordingly, an object of the present invention is to provide a method for manufacturing a high-hardness boron nitride film containing cubic boron nitride crystal grains.

[Means for solving the problem]

According to the method for producing a boron nitride film of the present invention, boron evaporated from an evaporation source is vapor-deposited on a substrate in a vacuum, and at the same time, a cusp magnetic field is provided at a location different from the evaporation source to confine plasma. Extract nitrogen ions from a bucket-type ion source and irradiate them directly to the same substrate without passing through mass separation means. It is characterized by the following.

[Action]

By forming a film under the above conditions, a high-quality boron nitride film having a high hardness containing nitrided cubic boron nitride and having a smooth film surface was obtained.

〔Example〕

FIG. 1 is a schematic view showing an example of an apparatus for performing the method for producing a boron nitride film according to the present invention. A substrate (for example, a silicon substrate) 2 is attached to a holder 1 and housed in a vacuum vessel (not shown), and an evaporation source 4 and an ion source 7 are arranged toward the substrate 2. The evaporation source 4 is, for example, an electron beam evaporation source, has a boron metal 5 as an evaporation material, and deposits boron (boron vapor) 6 on the substrate 2. The ion source 7 is a so-called bucket type ion source, and can ionize the supplied nitrogen gas G and irradiate the substrate 2 with uniform and large-area nitrogen ions 8. The bucket type ion source refers to an ion source that uses a multipole magnetic field, more specifically, a cusp magnetic field, for confining plasma. Reference numeral 9 denotes a thickness monitor of the boron nitride film 3 formed on the substrate 2.

At the time of film formation, the inside of the vacuum vessel is evacuated to, for example, about 10 ^-7 Torr, and then boron 6 from the evaporation source 4 is deposited on the substrate 2 while nitrogen ions 8 from the ion source 7 are deposited.
Is irradiated on the substrate 2. At this time, if necessary, holder 1
A cooling medium W such as cooling water is supplied to the substrate 2 to cool the substrate 2.

The energy of the nitrogen ions 8 in the above case is 0.5 to 5 Ke
Low energy within the range of V. This is because according to the experimental results, the boron nitride film 3 was not produced below 0.5 KeV,
On the other hand, if it is 5 KeV or more, even if the boron nitride film 3 is manufactured, a smooth film surface cannot be obtained due to the sputtering action of the nitrogen ions 8 and the damaged portion such as a defect portion increases in the boron nitride film 3. This is because a high quality boron nitride film 3 cannot be obtained.

Further, at the time of film formation, the particle ratio (composition ratio) of boron B deposited on the substrate 2 and nitrogen ions N irradiated on the substrate 2 is represented by B /
It is preferable to select N to an appropriate value, for example, in the range of about 0.7 to 2.0.

The features of the film forming method as described above are as follows.

Even when the low energy nitrogen ions 8 are used, a boron nitride film 3 having high hardness including cubic boron nitride crystal grains, for example, having the same hardness as that of ordinary cubic boron nitride can be obtained.

Since the low-energy nitrogen ions 8 are used, a high-quality boron nitride film 3 having less roughness due to sputtering, having a very smooth film surface, and having few damaged portions such as defects inside the film can be obtained.

Since low-energy nitrogen ions 8 are used, the cost of the ion source 7 and related devices such as a power supply are reduced, and the operation and handling of the various devices are facilitated. Therefore, the advantage in industrial application is great.

Since a bucket-type ion source is used as the ion source 7, uniform and large-area nitrogen ions 8 can be obtained, so that the composition in the boron nitride film 3 becomes more uniform.

Since the individual processing conditions of boron deposition and nitrogen ion irradiation can be adjusted, the controllability on the composition ratio B / N during film formation is good.

The following is a specific example. With the silicon substrate kept at room temperature, irradiation of nitrogen ions (3 KeV, 15 mA) and boron deposition (using 99.5% metal boron as the deposition material, deposition rate of about 1 mm / sec) were performed simultaneously to form a boron nitride film on the substrate. About 1
μm was deposited. At that time, the composition ratio B / N was about 1.1.

In the above boron nitride film, a Vickers hardness Hv of 4730 [kg / mm ² ] was obtained with a load of 10 g. Incidentally, in this case, since the film thickness is about 1 μm, the silicon substrate (Hv
(2000),
The hardness is at least twice as high as that of the substrate, and the hardness of the boron nitride film itself is considered to be about the same as the hardness of normal cubic boron nitride (Hv ≒ 8000). As a result of measuring the infrared absorption spectrum of this film, absorption indicated by cubic boron nitride was observed at around 1100 cm ^-1 . When the boron nitride film was observed under a microscope of about 10,000 times, almost no irregularities on the surface were observed.

〔The invention's effect〕

The present invention is configured as described above, and has the following effects.

Cubic boron nitride that exhibits excellent performance as a high-hardness layer is metastable, and if there are many damaged parts such as defects in the boron nitride film, it is difficult to grow due to these damaged parts. Since low energy nitrogen ions of 0.5 KeV or more and less than 5 KeV are used, it is possible to suppress the generation of defects in the film due to irradiation ions and obtain a high hardness boron nitride film containing many cubic boron nitride crystal grains. it can.

Since low-energy nitrogen ions of 0.5 KeV or more and less than 5 KeV are irradiated, the surface of the film is very smooth with little roughness due to sputtering due to ion irradiation, and high quality nitridation with few damaged parts inside the film. A boron film is obtained.

Since low-energy nitrogen ions are used, the cost of equipment such as an ion source and a power supply associated with the ion source is reduced, and the operation and handling of the various equipment are facilitated. Therefore, the advantage in industrial application is great.

The bucket-type ion source uses a cusp magnetic field for plasma confinement, and can confine large-area plasma with good uniformity, so that uniform and large-area nitrogen ions can be obtained. Therefore, by using such an ion source, a boron nitride film having a large area and high composition uniformity can be obtained, so that a high-quality boron nitride film can be manufactured with high productivity. Therefore, its industrial value is high.

Since nitrogen ions are extracted from the ion source and are irradiated on the substrate without passing through the mass separation means, a decrease in the amount of ions caused by passing through the mass separation means can be avoided, and the productivity of the boron nitride film is high. Moreover, since no mass separation means is required, the size and cost of the apparatus can be reduced accordingly. In particular, in order to obtain large area ions, when mass separation means is used, the size must be increased, but according to the present invention, there is no such problem.

There is also a thought that an evaporation source is provided at the back of the ion source and the two are integrated, but in such a case, the evaporation material from the evaporation source adheres to the extraction electrode of the ion source, and the extraction electrode is contaminated or clogged. Clogging is likely to occur and ions cannot be stably extracted for a long time. On the other hand, in the present invention, since the evaporation source and the ion source are provided at different positions from each other, contamination and clogging of the extraction electrode by the evaporating substance do not occur, and therefore, ions can be stably extracted for a long time. it can. Therefore, productivity is high and industrial utility value is high.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus for performing the method for producing a boron nitride film according to the present invention. 2 ... substrate, 3 ... boron nitride film, 4 ... evaporation source, 6 ...
... boron, 7 ... ion source, 8 ... nitrogen ion.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-227163 (JP, A) JP-A-60-63372 (JP, A) JP-A-58-81967 (JP, A)

Claims (1)

(57) [Claims] 1. A bucket type ion beam, which is provided on a substrate in a vacuum and which is vapor-deposited with boron from an evaporation source, and which is provided at a location different from the evaporation source and uses a cusp magnetic field for confining plasma. It is characterized by extracting nitrogen ions from the source and irradiating the same substrate without passing through the mass separation means, and in this case, the energy of the nitrogen ions irradiating the substrate is in a range of 0.5 KeV or more and less than 5 KeV. To produce a boron nitride film containing cubic boron nitride crystal grains.