JP2636577B2 - Method of forming titanium nitride film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a titanium nitride (TiN) film for use in, for example, improving the wear resistance of a substrate and the decoration of a substrate.

[0002]

2. Description of the Related Art A titanium nitride film (typically a thin film) having good crystallinity improves the abrasion resistance of a substrate such as a metal, a glass, and a resin and exhibits a gold color due to its hardness. Thus, it is suitable for use in various decorative purposes.

Hitherto, in order to improve the wear resistance of various substrates, several techniques for forming a hard titanium nitride thin film on the substrates have been proposed. For example, a chemical vapor deposition method (CV) in which a source gas containing a titanium element and a source gas containing a nitrogen element are reacted at a high temperature to form a titanium nitride thin film.
There is a disadvantage that the type is limited because the substrate is exposed to high-temperature conditions.

On the other hand, as a method of obtaining a titanium nitride thin film having high adhesion strength at a low temperature, there is a method of using both vacuum deposition and ion irradiation. This is a method of irradiating the substrate with nitrogen ions simultaneously with the vacuum deposition of titanium. According to this method, a titanium nitride thin film is formed on the substrate without particularly heating the substrate, and The vapor-deposited titanium atoms collide with the irradiation ions and are pushed into the substrate. As a result, a mixed layer of the constituent atoms of the substrate, the vapor-deposited atoms and the ions is formed near the interface between the substrate and the thin film, and adheres to the substrate. There is an advantage that a thin film having high strength is formed.

[0005]

However, in the above-mentioned method using both vacuum deposition and ion irradiation, although a hard titanium nitride thin film can be obtained, the reason has not been clarified yet, but the thin film has a gold color. There is a problem that it is often not presented. There is also a problem that the number of defects generated in the base by ion irradiation increases, and the strength of the base is deteriorated, or the temperature of the base is increased, and as a result, the base may be thermally damaged.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for forming a titanium nitride film having a high hardness, a golden color, and a high adhesion strength to a substrate without thermally damaging the substrate. I do.

[0007]

To achieve the above object, according to an aspect of forming a titanium nitride film of the present invention, to the substrate in a vacuum chamber, and deposition of titanium, nitrogen gas into the ion source
And irradiating the substrate with nitrogen ions to form a titanium nitride film on the surface of the substrate, wherein the energy of the nitrogen ions irradiating the substrate is 20 KeV.
The number ratio (Ti / N) of the number of titanium atoms to the number of nitrogen ions reaching the substrate is set to 0.7 or more and 2.0 or less, and the ionized light incident on the film-forming surface of the substrate in the vacuum vessel is formed. When the incidence frequency Z of unexposed nitrogen is defined as Z = 3.535 × 10 ²² × P / √ (MT) [pieces / s · cm ² ], where Ptorr is the pressure of the nitrogen gas in the vacuum vessel ( M is the molecular weight of the nitrogen molecule, T is the temperature of the substrate [K]), and this incidence frequency Z is 3.9 × 10 ¹⁵ ≦ Z
The film formation is performed by adjusting the pressure in the vacuum chamber during the film formation so that ≦ 2 × 10 ¹⁶ [ pieces / s · cm ² ] .

[0008]

The energy of the nitrogen ions applied to the substrate is 20
When it is larger than KeV, the number of defects caused to the substrate by the irradiation ions increases, the strength of the substrate is deteriorated, and the heat applied to the substrate becomes excessive, thereby generating thermal damage.

If the ratio of the number of titanium atoms to the base and the number of nitrogen ions (Ti / N) is smaller than 0.7, the damage to the film by the ions becomes excessive, and
Unbound nitrogen in the film adversely affects the color and hardness of the film. On the other hand, when the number ratio is larger than 2.0, the amount of titanium that does not bond with nitrogen in the film becomes excessive, which also adversely affects the color and hardness of the film.

Further, the incidence frequency Z is 2 × 10 ¹⁶ /
If it is larger than s · cm ² , the bond between the non-ionized nitrogen gas and the evaporated titanium cannot be ignored, which adversely affects the hardness of the film and the color development of gold. Incident frequency Z
If it is smaller than 3.9 × 10 ¹⁵ / s · cm ² ,
The amount of nitrogen gas that can be introduced into the ON source is small.
The irradiation dose of nitrogen ions is too low
And the time required for film formation is increased.
May not be irradiated.

[0011]

FIG. 1 is a schematic view showing an example of an apparatus for performing a method for forming a titanium nitride film according to the present invention.

A holder 2 for holding a substrate 4 is provided in a vacuum vessel (not shown).
And an ion source 14. In this example, a film thickness monitor 12 and an ion current monitor 18 are arranged near the holder 2 for measurement and control in this example.

In order to form a titanium nitride thin film, a desired substrate 4 is mounted on the holder 2 and the inside of the vacuum vessel is maintained at a pressure of, for example, 5 × 10 ⁻⁶ torr or less by a vacuum exhaust device (not shown). At this time, the pressure in the vacuum vessel is 5 × 10 ^-6
When the pressure is larger than torr, oxygen gas remaining in the vacuum vessel is taken into the formed thin film, and as a result, a part of the titanium nitride thin film is oxidized, and the hardness of the thin film is undesirably reduced.

Thereafter, the titanium material 10 contained in the evaporation source 8 is heated and vaporized to evaporate the titanium 10, and the titanium 10 is vacuum-deposited on the substrate 4. At this time, the evaporation material 9 containing titanium element
However, high-purity titanium is preferable, otherwise, impurities are taken into the film, making the color and hardness of the film unfavorable. Further, as the evaporation source 8, a method of heating an evaporation material by an electron beam or a high frequency or the like,
Other methods, for example, a method using sputtering may be used, and the method is not limited to a specific method.

Further, the step of introducing nitrogen gas 15 into the ion source 14, ionizing it in the ion source 14, accelerating it, and irradiating the substrate 4 with nitrogen ions 16 is performed simultaneously or alternately with the above-mentioned vacuum deposition. Done in The titanium nitride thin film 6 is formed on the surface of the substrate 4 by using the irradiation of the nitrogen ions 16 and the vacuum deposition of the titanium 10 in combination. At this time, as the ion source 14, an arbitrary source such as a bucket-type ion source using a cusp magnetic field for confining plasma or a Kauffman-type ion source is used.

In the above film formation, the energy of the nitrogen ions 16 applied to the substrate 4 is preferably larger than 0 eV and 20 KeV or less. If the energy of the nitrogen ions 16 is larger than 20 KeV, the number of defects caused by the irradiated nitrogen ions 16 to the substrate 4 increases, the strength of the substrate 4 deteriorates, and the heat applied to the substrate 4 becomes excessive, and It is not preferable because it causes serious damage.

The incident angle of the nitrogen ions 16 with respect to the substrate 4 is 0 ° to 90 ° with respect to the normal set on the film-forming surface of the substrate 4.
Any angle up to is used.

During film formation, the ratio of the number of evaporated titanium atoms reaching the substrate 4 to the number of nitrogen ions (hereinafter referred to as Ti)
/ N transport ratio) is preferably 0.7 or more and 2.0 or less. If the Ti / N transport ratio is smaller than 0.7, the damage to the film by the nitrogen ions 16 becomes excessive, and unbound nitrogen in the film adversely affects the color and hardness of the film. On the other hand, if the Ti / N transport ratio is larger than 2.0, the amount of titanium that does not bind to nitrogen in the film becomes excessive, which also adversely affects the color and hardness of the film.

With regard to the adjustment of the Ti / N transport ratio, for example, the amount of titanium 10 evaporated from the evaporation source 8 is controlled by using a film thickness monitor 12 composed of a quartz oscillator, etc. This can be performed by controlling the ion current of the nitrogen ions 16 extracted from the ion source 14 using the current monitor 18.

The present invention is further characterized in that it is possible to form a gold-colored titanium nitride thin film, which has not been clarified conventionally, in consideration of the following points.

That is, by introducing a nitrogen gas 15 into the ion source 14, the ion source 14
A part of the introduced nitrogen gas 15 inevitably flows out of the apparatus. As a result, the area around the film-forming surface of the substrate 4 is filled with non-ionized nitrogen gas. Then, the non-ionized nitrogen gas combines with the titanium atoms evaporated from the evaporation source 8. Originally, the film forming method of the present invention is intended to form the titanium nitride thin film 6 on the surface of the substrate 4 by combining the evaporated titanium atoms with nitrogen ions which have been ionized and accelerated to a predetermined energy. The titanium atoms are excited by the collision between the atoms and the irradiation ions, and a bond between the excited titanium atoms and the nitrogen ions is intended to form a hard and golden thin film. Therefore, after or during the arrival of the evaporated titanium 10 on the substrate 4, it combines with the non-ionized nitrogen gas around the substrate 4 to form titanium nitride, so that the effect of the irradiated ions is sufficiently reduced. The film is soft and does not exhibit a golden color.

The non-ionized nitrogen gas flies by thermal motion in the vacuum vessel and collides with the substrate 4. In this manner, the incidence frequency Z of non-ionized nitrogen incident on the film-forming surface of the substrate 4 is as follows. Is defined as Z = 3.535 × 10 ²² × P / √ (MT) [pcs / s · cm ² ], where P is the pressure of the nitrogen gas in the vacuum vessel (M is the molecular weight of the nitrogen molecule, T is the substrate 4
Temperature [K]. √ (MT) represents the square root of MT. ), The above-mentioned non-ionized nitrogen gas unless the film formation is performed by adjusting the pressure in the vacuum chamber during the film formation so that Z becomes 2 × 10 ¹⁶ / s ² or less. Experiments have shown that the bond between titanium and evaporated titanium is not negligible and adversely affects the hardness of the film and the coloration of gold. However, if the value of Z is too small ,
The amount of nitrogen gas that can be introduced into the
Therefore, the irradiation amount of the nitrogen ions 16 extracted from the ion source 14 and irradiated on the substrate 4 becomes too small. As a result, titanium in the case where the Ti / N transport ratio is adjusted to 0.7 or more and 2.0 or less is used. 10 decreases the amount of evaporation, increases the time required for film formation, and reduces the nitrogen in the ion source.
Nitrogen plasma in ion source due to too low gas pressure
In some cases , the nitrogen ions 16 may not be stably irradiated during the film formation due to the impaired stability. Therefore, it is preferable to appropriately adjust the above value so as not to exceed the above value. concrete
In the first embodiment described below, the incident frequency Z is 3.9 ×
The film deposition time was set to 10 ¹⁵ / s · cm ² at that value.
Since no inconvenience such as an increase occurred, the incidence frequency Z
Is preferably at least this value.

Next, a more specific embodiment according to the present invention and a comparative example equivalent to the conventional example will be described.

Example 1 Using the apparatus shown in FIG. 1, a cemented carbide (K10
After the seed was attached to the holder 2, the inside of the vacuum vessel was evacuated to 1 × 10 ⁻⁶ torr. afterwards,
Using an evaporation source 8 using an electron beam, a titanium pellet having a purity of 3N is vaporized using a titanium pellet having a purity of 3N as an evaporation material 9 to deposit titanium 10 on a substrate 4, and a nitrogen gas 15 having a purity of 5N is supplied to a bucket-type ion source. 14 to be ionized, and to convert nitrogen ions 16 with an energy of 2 KeV,
The substrate 4 was irradiated at an incident angle of 0 ° with respect to the substrate 4.
At this time, the pressure in the vacuum vessel was maintained at 1 × 10 ⁻⁵ torr. Further, the Ti / N transport ratio during the film formation was set to 1.0. Further, the temperature of the substrate 4 during film formation was kept at 25 ° C. by cooling the holder 2 with water. In this case, the ion source 14
The pressure in the vacuum vessel is 1 × by the nitrogen gas 15 introduced into
^10-5 torr, the incident frequency Z
Is 3.9 × 10 ¹⁵ / s · cm ² . Under these conditions, a titanium nitride thin film 6 of about 0.5 μm was formed on the base 4.

Example 2 The substrate 4 was irradiated with nitrogen ions 16 at an energy of 2 KeV while adjusting each value so that the Ti / N transport ratio became 1.5. Filmed. At this time, the temperature of the substrate 4 was 25 ° C., and the pressure in the vacuum vessel was 3 ×
It was 10 ^-5 torr. Therefore, the incident frequency Z at this time
Is 1.2 × 10 ¹⁶ / s · cm ² . All other conditions are the same as in the first embodiment.

Example 3 Nitrogen ions 16 were applied to the substrate 4 at an energy of 500 eV while adjusting each value so that the Ti / N transport ratio became 1.5.
To form a film on the same substrate 4 as in Example 1. At this time, the temperature of the substrate 4 was 25 ° C., and the pressure in the vacuum vessel was 3 ° C.
× 10 ^-5 torr. Therefore, the value of the incidence frequency Z at this time is 1.2 × 10 ¹⁶ / s · cm ² . All other conditions are the same as in the first embodiment.

EXAMPLE 4 Nitrogen ions 16 were applied to the substrate 4 at an energy of 500 eV while adjusting each value so that the Ti / N transport ratio became 0.9.
To form a film on the same substrate 4 as in Example 1. At this time, the temperature of the substrate 4 was 25 ° C., and the pressure in the vacuum vessel was 3 ° C.
× 10 ^-5 torr. Therefore, the value of the incidence frequency Z at this time is 1.2 × 10 ¹⁶ / s · cm ² . All other conditions are the same as in the first embodiment.

Example 5 Nitrogen ions 16 were applied to the substrate 4 at an energy of 20 KeV while adjusting each value so that the Ti / N transport ratio became 1.5.
To form a film on the same substrate 4 as in Example 1. At this time, the temperature of the substrate 4 was 25 ° C., and the pressure in the vacuum vessel was 3 ° C.
× 10 ^-5 torr. Therefore, the value of the incidence frequency Z at this time is 1.2 × 10 ¹⁶ / s · cm ² . All other conditions are the same as in the first embodiment.

Example 6 Using a substrate (resin substrate) 4 having a heat-resistant temperature of 100 ° C., as in Example 1, while adjusting each value so that the Ti / N transport ratio becomes 1.0, a 500 eV The substrate 4 was irradiated with nitrogen ions 16 with energy to form a film. The substrate 4 at this time
Is 25 ° C., and the pressure in the vacuum vessel is 3 × 10 ^−5.
torr. Therefore, the value of the incidence frequency Z at this time is 1.2 × 10 ¹⁶ / s · cm ² . All other conditions are the same as in the first embodiment.

COMPARATIVE EXAMPLE 1 As in Example 1, the substrate 4 was irradiated with nitrogen ions 16 at an energy of 2 KeV while adjusting each value so that the Ti / N transport ratio became 1.0. A film was formed on the same substrate 4 as above. At this time, the temperature of the substrate 4 was 25 ° C., and the pressure in the vacuum vessel was 8 × 10 ⁻⁵ torr. Therefore, the value of the incident frequency Z at this time is 3.0 × 10 ¹⁶ / s · c
become m ^2. All other conditions are the same as in the first embodiment.

COMPARATIVE EXAMPLE 2 While adjusting each value so that the Ti / N transport ratio becomes 1.0, nitrogen ions 16 were applied to the substrate 4 at an energy of 500 eV.
To form a film on the same substrate 4 as in Example 1. At this time, the temperature of the substrate 4 was 25 ° C., and the pressure in the vacuum vessel was 8 ° C.
× 10 ^-5 torr. Therefore, the value of the incidence frequency Z at this time is 3.0 × 10 ¹⁶ / s · cm ² . All other conditions are the same as in the first embodiment.

COMPARATIVE EXAMPLE 3 While adjusting each value so that the Ti / N transport ratio becomes 2.5, nitrogen ions 16 were applied to the substrate 4 at an energy of 500 eV.
To form a film on the same substrate 4 as in Example 1. At this time, the temperature of the substrate 4 was 25 ° C., and the pressure in the vacuum vessel was 3 ° C.
× 10 ^-5 torr. Therefore, the value of the incidence frequency Z at this time is 1.2 × 10 ¹⁶ / s · cm ² . All other conditions are the same as in the first embodiment.

COMPARATIVE EXAMPLE 4 While adjusting each value so that the Ti / N transport ratio becomes 0.6, nitrogen ions 16 were applied to the substrate 4 at an energy of 500 eV.
To form a film on the same substrate 4 as in Example 1. At this time, the temperature of the substrate 4 was 25 ° C., and the pressure in the vacuum vessel was 3 ° C.
× 10 ^-5 torr. Therefore, the value of the incidence frequency Z at this time is 1.2 × 10 ¹⁶ / s · cm ² . All other conditions are the same as in the first embodiment.

COMPARATIVE EXAMPLE 5 As in Example 6, using a substrate 4 having a heat-resistant temperature of 100.degree. C., while adjusting each value so that the Ti / N transport ratio becomes 0.9, nitrogen ions were used at an energy of 30 KeV. 16 was applied to the substrate 4 to form a film. At this time, the temperature of the substrate 4 is 25
° C and the pressure in the vacuum vessel was 3 × 10 ^-5 torr. Therefore, the value of the incidence frequency Z at this time is 1.2 × 1
It becomes ¹⁶ pieces / s · cm ² . All other conditions are the same as in the first embodiment.

Table 1 shows the results of the above Examples and Comparative Examples.
The following shows the hardness and color of the titanium nitride thin film 6. In this case, the hardness of the film was measured with a 10 g Vickers microhardness tester.

[0036]

[Table 1]

The films of Examples 1 to 6 all have a high hardness and a golden color, indicating that they are suitable as wear-resistant or decorative films. No peeling was observed on any of the films.

On the other hand, those of Comparative Examples 1 and 2 correspond to Examples 1 and 3, however, since the value of the incidence frequency Z was beyond the range of the present invention, the hardness of the film was lower than that of Examples 1 and 2. Inferior to that of No. 3, and the color of the film became black. Further, those of Comparative Examples 3 and 4 correspond to Example 3,
Since the i / N transport ratio was beyond the range of the present invention, the hardness of the film was inferior to that of Example 3, and the color of the film became black. Comparative Example 5 corresponds to Example 6, but since the acceleration energy of nitrogen ions 16 was beyond the range of the present invention, the temperature of substrate 4 during film formation was kept at 25 ° C. The strength and the like of the film formation surface are deteriorated due to physical and thermal damage given by ion irradiation during film formation, and as a result, the film hardness is inferior to that of Example 6 and the crystallinity of the film is further reduced. It became worse and its color became black.

[0039]

As described above, according to the present invention, the number ratio (Ti / N) of titanium atoms and nitrogen ions reaching the substrate during film formation is limited to the above range, and ionization incident on the substrate is achieved. By limiting the incidence frequency Z of nitrogen not performed to the above range, it is possible to form a titanium nitride film having high hardness and exhibiting a golden color ,
The amount of nitrogen gas that can be introduced is too small
Therefore, the irradiation amount of nitrogen ions becomes too small and
It takes a lot of time and nitrogen ions are
Can prevent the inconvenience of not being shot
You . Moreover, by limiting the energy of the nitrogen ions irradiated to the substrate to the above range, thermal damage to the substrate is small, and therefore, the material that can be used for the substrate is not limited.

Also, by using both vacuum deposition and nitrogen ion irradiation, a mixed layer composed of both constituent atoms is formed near the interface between the substrate and the film, thereby forming a film having strong adhesion strength. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus for performing a method for forming a titanium nitride film according to the present invention.

[Explanation of symbols]

 Reference Signs List 4 substrate 6 titanium nitride thin film 8 evaporation source 10 titanium 14 ion source 16 nitrogen ion

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Takashi Mikami, the inventor 47-store, Takanecho Umezu, Ukyo-ku, Kyoto-shi Inside Nissin Electric Co., Ltd. (56) References JP-A-4-314485 (JP, A)

Claims (1)

(57) [Claims] 1. A titanium nitride film is formed on a surface of a base by performing titanium deposition and irradiation of nitrogen ions obtained by introducing nitrogen gas into an ion source on the base in a vacuum vessel. In the method, the energy of nitrogen ions applied to the substrate is set to 20 KeV or less, and the ratio of the number of titanium atoms to the number of nitrogen ions reaching the substrate (Ti / N)
Is set to 0.7 or more and 2.0 or less, and the incidence frequency Z of non-ionized nitrogen incident on the film-forming surface of the substrate in the vacuum vessel is set to the pressure of the nitrogen gas in the vacuum vessel to Ptorr.
When Z = 3.535 × 10 ²² × P / √ (MT) [pieces / s · cm ² ] (M is the molecular weight of nitrogen molecules, T is the temperature of the substrate [K]), the incidence frequency Z is 3.9 × 10 ¹⁵ ≦ Z
A method for forming a titanium nitride film, wherein a film is formed by adjusting a pressure in a vacuum container during film formation so that ≦ 2 × 10 ¹⁶ [ pieces / s · cm ² ] .