JPH0525640A - Formation of metallic nitride thin film - Google Patents

Abstract

PURPOSE:To provide the method for forming the metallic nitride thin film of desired compsn. ratios over the entire surface of a large-sized base material having intricate three-dimensional shapes installed in a vacuum chamber. CONSTITUTION:Ammonia is used as a gaseous raw material which is a nitrogen source and while the large-sized base material 12 having the intricate three- dimensional shapes and installed in the vacuum chamber 1 is uniformly heated at a prescribed temp. by a heating source 9, a low DC voltage is impressed between the chamber 1 and the base material 12 and the film is formed by the low DC plasma power at the time of supplying at least the gaseous raw material as the nitrogen source and the gaseous raw material as a metal source into the above-mentioned chamber 1, generating plasma in the chamber 1 to bring the respective gaseous raw materials mentioned above into reaction in the chamber 1 and forming the metallic nitride thin film on the surface of the base material 12.

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 metal nitride thin film, and more particularly to an improvement in a method for forming a metal nitride thin film on a large-scale complex three-dimensional base material such as a rolling roll or a screw by plasma CVD.

[0002]

2. Description of the Related Art Conventionally, a thermal CVD method has been adopted as a method for forming a metal nitride thin film, for example, a TiN thin film on a three-dimensional base material. This method is a method in which a raw material gas is caused to undergo a chemical reaction by heat energy in a vacuum chamber to form a thin film on the base material placed in the chamber. The thermal CVD method is characterized in that a tough thin film can be formed on the three-dimensional base material with good adhesion and throwing power. However, since the chemical reaction required for forming a thin film is usually performed at a high temperature of 1000 ° C. or higher, the material constituting the base material is restricted. For example, it is difficult to apply the thermal CVD method to a base material made of a material that is easily damaged by heat or a material that is easily changed in size by thermal expansion.

Under these circumstances, a physical vapor deposition method (PVD method) such as a sputtering method or an ion plating method has been developed in recent years, and it has become possible to form a metal nitride thin film at a low temperature. However, the PVD method has a problem that the deposition property of the vapor deposition substance on the three-dimensional substrate is low. Particularly, in the case of a large-sized complex three-dimensionally shaped substrate, the throwing power is remarkably deteriorated, so that it is practically difficult to apply the PVD method.

Therefore, the good throwing power of the CVD method and P
A plasma CVD method has been developed which has both advantages of forming a thin film at a low temperature in the VD method. This plasma CVD
The method makes it possible to form a thin film at a low temperature by substituting a part or all of the thermal energy required for the chemical reaction of the raw material gas with electric energy by plasma.
In the plasma CVD method, as in the conventional thermal CVD method, the source gas in the vacuum chamber is supplied through a nozzle, and direct current or high frequency is applied to the three-dimensional base material arranged in the chamber to cause glow discharge. To generate plasma. At this time, the source gas supplied into the chamber becomes active excited species such as ions, radicals, atoms and molecules when passing through the plasma. It is considered that these excited species are capable of forming a thin film on the three-dimensionally shaped substrate at a low temperature because the reaction proceeds at a low temperature.
Therefore, the plasma CVD method can form a thin film having good throwing power on a three-dimensional substrate at a low temperature.

By the way, the above-mentioned conventional plasma CVD
In the case of forming a metal nitride thin film on a large-sized three-dimensional base material by the method, the base material is installed in a vacuum chamber equipped with a heater and at least a raw material gas as a nitrogen source and a raw material gas as a metal source. Is supplied to the chamber, and D
C plasma is applied. In this case, in order to form a metal nitride thin film having good film quality, it becomes necessary to apply a high DC voltage. However, when a film is formed on a large-scale complex three-dimensional base material having remarkable irregularities, a strong glow discharge is locally generated on the surface of the base material, and the base material temperature becomes non-uniform. It becomes difficult to form a nitride thin film.

The present invention has been made in order to solve the above-mentioned conventional problems, and plasma CV is formed on the entire surface of a large-scale complex three-dimensional base material installed in a vacuum chamber having a heating source.
An object of the present invention is to provide a method capable of forming a metal nitride thin film having a desired composition ratio by D with a uniform thickness.

[0007]

According to the present invention, at least a raw material gas as a nitrogen source and a raw material gas as a metal source are supplied into a vacuum chamber, and plasma is generated in the chamber so that the plasma is generated in each of the chambers. When forming a metal nitride thin film on the surface of a large-scale complex three-dimensional base material installed in the chamber by reacting the raw material gas, ammonia is used as a raw material gas as a nitrogen source, and the base material is heated to a predetermined temperature by a heating source. The method for forming a metal nitride thin film is characterized in that a low DC voltage is applied between the chamber and the base material while being uniformly heated to form a film with a DC low plasma power. Examples of the source gas as the metal source include T
iCl ₄ or the like can be used.

It is desirable that each source gas be supplied into the chamber together with a carrier gas. As such a carrier gas, for example, hydrogen or an inert gas such as He or Ar can be used.

It is desirable that the DC plasma applied voltage during the film formation is in the range of 600 to 1400V, and the substrate temperature by the heating source is in the range of 480 to 600 ° C.
This is due to the following reasons. When the voltage applied to the DC plasma is less than 600V, the film forming rate is lowered, while when the voltage applied to the DC plasma exceeds 1400V, a strong strong glow is locally generated on the surface of the large-scale complex three-dimensionally shaped substrate and the substrate is overheated. Therefore, uniform film formation may be difficult. If the substrate temperature deviates from the above range, it becomes difficult to form a metal nitride thin film having a uniform thickness and a uniform composition ratio.

[0010]

The present inventors have found from the knowledge described below that a metal nitride thin film having a desired composition ratio and a uniform thickness is formed on the entire surface of a large-scale complex three-dimensional base material at a low temperature with good throwing power. I found a way to get it.

That is, as in the above-mentioned conventional method, two or more kinds of source gases are supplied through a nozzle into a vacuum chamber having a heating source in which the substrate is installed, and the DC plasma generated in the chamber causes It has been clarified that when a thin film is formed on the surface of a base material, the characteristics of the thin film (for example, film forming rate, hardness, etc.) are not constant between the central portion and the end portion of the base material, but change. The reason for this is not clear at this time, but strong glow is locally generated on the large-scale complex three-dimensional base material by the applied DC plasma, and the base material is locally overheated to prevent uniform film formation. It is estimated that this is due to

From the above, the inventors of the present invention have supplied at least the source gas as the nitrogen source and the source gas as the metal source into the vacuum chamber, and at the same time generate the plasma in the chamber so that the plasma is generated in the chamber. When forming a metal nitride thin film on the surface of a large-scale complex three-dimensional base material installed in the chamber by reacting each raw material gas, highly reactive ammonia is used as the raw material gas that is a nitrogen source,
DC is applied by applying a low DC voltage between the chamber and the substrate while uniformly heating the substrate at a predetermined temperature with a heating source.
A method for forming a metal nitride thin film having a uniform composition ratio over the entire surface of the base material with good reproducibility without forming strong glow locally on the base material by forming a film with low plasma power was found. It was

[0013]

Embodiments of the present invention will now be described in detail with reference to FIG.

FIG. 1 shows the plasma CV used in this embodiment.
It is a schematic diagram showing a D device. 1 in the figure is, for example, a diameter of 1.
200 mm vacuum chamber. A rotary flat plate-shaped electrode 2 is installed below the chamber 1. A DC power supply 3 is connected to the electrode 2. An exhaust pipe 4 is provided at the bottom of the chamber 1, and a vacuum pump 5 is connected to the other end of the exhaust pipe 4.

Inside the chamber 1, a large number of gas ejection ports are opened on the inner peripheral surface, for example, a diameter of 900 mm and a diameter of 700.
Annular nozzles 6 and 7 of mm are arranged so as to be vertically shifted so as to surround a large-sized complex three-dimensional base material installed on the electrode 2. One end of a composite gas introducing pipe 8 having a double pipe structure is connected to the annular nozzles 6 and 7. The annular nozzle 6 is connected to the inner pipe 8a of the composite gas introduction pipe 8, and the tubular nozzle 7 is connected to the inner pipe 8a and the outer pipe 8b of the composite gas introduction pipe 8, respectively. The other end of the introduction pipe 8 extends through the sidewall of the chamber 1 to the outside of the heater 9 arranged on the outer periphery of the chamber 1, and is branched into an inner pipe 8a and an outer pipe 8b. There is. Valves 10a and 10b and mass flow controllers 11a and 11b are sequentially inserted in the inner pipe 8a and the outer pipe 8b located outside the heater 9, respectively. Example A thin film forming method using the plasma CVD apparatus described above will be described.

First, the diameter of the bulging portion in the horizontal direction on the rotating electrode 2 in the vacuum chamber 1 is 400 mm, and the diameter of the hollow portion is 1.
A large complex three-dimensional substrate 12 made of SKH51 having a size of 00 mm and a height of 600 mm was installed so as to be inserted into the annular nozzles 6 and 7. Subsequently, the vacuum pump 5 is operated to exhaust the gas in the chamber 1 through the exhaust pipe 4, and the mixed gas of NH ₃ and H ₂ (NH ₃ ; 150 scc) whose flow rate is adjusted by the mass flow controller 11 and the valve 10.
m, H ₂ ; 2000 sccm) through a composite gas introducing pipe 8 (between the inner pipe 8a and the outer pipe 8b) having a double pipe structure,
It was supplied into the chamber 1 from an annular nozzle 6 (00 mm). Then, the base material 12 is heated to 500 ° C. by the heater 9.
While the electrode 2 is rotated in a state of being heated to a high temperature, a DC voltage of −800 V is applied from the DC power source 3 to the chamber 1
Plasma was generated inside to clean the surface of the substrate 12.

Then, the mass flow controller 11b and the valve 10b are continuously supplied with the mixed gas.
Mixed gas of TiCl ₄ and H ₂ (TiC
l ₄ ; 50 sccm, H ₂ ; 2000 sccm) is supplied into the chamber 1 from the annular nozzle 7 having a small diameter (700 mm) through the inner pipe 8 a of the composite gas introduction pipe 8, and the temperature of the substrate 12 is 500 ° C. Pressure in 1 is 1t
Plasma TiN was performed for 2 hours under the condition of orr to form a TiN thin film on the surface of the large-sized complex three-dimensional substrate 12. Comparative example

First, on the rotary electrode 2 in the vacuum chamber 1, a large complex three-dimensional base material 12 made of SKH51 having a horizontal bulging portion having a diameter of 400 mm, a hollow portion having a diameter of 100 mm, and a height of 600 mm is prepared. It was installed so as to be inserted into the annular nozzles 6 and 7. Subsequently, the vacuum pump 5 is operated to exhaust the gas in the chamber 1 through the exhaust pipe 4,
A mixed gas of N ₂ and H ₂ (N ₂ ; 100 scc) whose flow rate is adjusted by the mass flow controller 11 and the valve 10.
m, H ₂ ; 2000 sccm) through a composite gas introducing pipe 8 (between the inner pipe 8a and the outer pipe 8b) having a double pipe structure,
It was supplied into the chamber 1 from an annular nozzle 6 (00 mm). Then, the base material 12 is heated to 500 ° C. by the heater 9.
While the electrode 2 was rotated in a state of being heated to 1, a DC voltage of -1500V was applied from the DC power source 3 to generate plasma in the chamber 1 to clean the surface of the substrate 12.

Then, the mass flow controller 11b and the valve 10b are continuously supplied with the mixed gas being supplied.
Mixed gas of TiCl ₄ and H ₂ (TiC
l ₄ ; 50 sccm, H ₂ ; 2000 sccm) is supplied into the chamber 1 from the annular nozzle 7 having a small diameter (700 mm) through the inner pipe 8 a of the composite gas introduction pipe 8, and the temperature of the substrate 12 is 500 ° C. Pressure in 1 is 1t
Plasma TiN was performed for 2 hours under the condition of orr to form a TiN thin film on the surface of the large-sized complex three-dimensional substrate 12.

With respect to the TiN thin film formed on the large-sized complex three-dimensional base material according to this example and the comparative example, the film thickness and hardness at multiple points at 10 mm intervals were measured using a fluorescent X-ray film thickness meter and a micro Vickers hardness meter. It was measured. As a result, in the example, it was confirmed that the film thickness was 3.1 ± 0.2 μm, the Vickers hardness at a load of 10 g was 1900 ± 300, and that a TiN thin film having a uniform thickness and a uniform thickness was formed. . On the other hand, in the comparative example, the film thickness was 1.6 ± 1.5 μm and the Vickers hardness was 1400 ± 800, and it was difficult to form a TiN thin film having a uniform thickness and a uniform thickness.

Further, in the present embodiment, the TiN thin films formed on the 10 large-sized complex three-dimensional substrates all had a golden color, and X-ray analysis was performed on each of them.
All had a TiN composition. On the other hand, in the comparative example, the TiN thin film formed on the 10 large-sized complex three-dimensional base materials had a golden color at the bulging portion, but had a dark brown color at the hollow portion, which was obtained by X-ray analysis of the dark brown color portion. Although the result shows the TiN composition, a large amount of chlorine was detected.

[0022]

As described above in detail, according to the present invention, a method for forming a metal nitride thin film having a desired composition ratio at a low temperature over the entire surface of a large-scale complex three-dimensional base material installed in a vacuum chamber. Can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view showing a plasma CVD apparatus used in an example of the present invention.

[Explanation of symbols]

1 ... Vacuum chamber, 2 ... Rotating electrode, 3 ... DC power supply, 4 ...
Exhaust pipe, 6, 7 ... Annular nozzle, 8 ... Composite gas introduction pipe, 1
2 ... Large complex three-dimensional base material.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiro Ishii             1-7-2 Nishishimbashi, Minato-ku, Tokyo LA Inc.             Within IMS (72) Inventor Kuniaki Kobayashi             1-7-2 Nishishimbashi, Minato-ku, Tokyo LA Inc.             Within IMS (72) Inventor Yoshikazu Yaginuma             3-4-6 Sumiyoshi-cho, Fuchu-shi, Tokyo JEOL             Fuchu Factory, Industrial Co., Ltd. (72) Inventor Yoshiyuki Funaki             3-4-6 Sumiyoshi-cho, Fuchu-shi, Tokyo JEOL             Fuchu Factory, Industrial Co., Ltd.

Claims (2)

[Claims] 1. A chamber in which at least a source gas as a nitrogen source and a source gas as a metal source are supplied into a vacuum chamber, and plasma is generated in the chamber to cause the source gases to react in the chamber. When forming a metal nitride thin film on the surface of a large-scale complex three-dimensional base material installed in the chamber, ammonia is used as a source gas as a nitrogen source, and the base material is uniformly heated by a heating source at a predetermined temperature in the chamber. A method for forming a metal nitride thin film, characterized in that a low DC voltage is applied between the base material and the base material to form a film with a low DC plasma power. 2. A DC plasma applied voltage of 600 to 1 for film formation.
The method for forming a metal nitride thin film according to claim 1, wherein the method is carried out under the conditions of a substrate temperature of 480 to 600 ° C. by a heating source of 400V.