JPH10139590A - Structural body having diamond thin film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structural body having diamond thin films enhanced in the adhesion property to a substrate and a method for producing the same. SOLUTION: An embedment region 3 consisting of a material having the adhesiveness higher than the adhesiveness of diamond to the front surface of the supporting substrate 1 is formed atop the supporting substrate 1. Diamond particles 2 are embedded in the embendment region 3. These diamond particles 2 are distributed like islands within the front surface of the supporting substrate 1 and their surfaces are partly exposed on the surface of the embedment region 3. The diamond thin film 4 is directly formed on the embedment region and the diamond particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure having a diamond thin film and a method for manufacturing the same. Diamond is the hardest material on earth and has excellent wear resistance. Furthermore, it has excellent properties not found in other materials, such as chemical stability, thermal conductivity, optical properties, and semiconductor properties. For this reason, diamond thin films are used for wear-resistant coatings, bonding tools for semiconductor integrated circuit chips,
Application to heat sinks and the like is expected.

[0002]

2. Description of the Related Art Plasma-excited chemical vapor deposition (PE-C)
A technique for forming a diamond thin film by VD) is known.

However, a diamond thin film synthesized in a vapor phase by PE-CVD has poor adhesion to a substrate, and is difficult to apply to a tool or the like that requires mechanical strength. Further, the surface of a bonding tool and a heat sink for a semiconductor integrated circuit chip needs to be polished after the diamond thin film is formed. If the adhesion between the diamond thin film and the substrate is poor, the diamond thin film may peel off during polishing. Therefore, application to a bonding tool, a heat sink, and the like is not easy.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure having a diamond thin film having improved adhesion to a substrate, and a method of manufacturing the same.

[0005]

According to one aspect of the present invention, a support substrate having an upper surface, and a stronger adhesion than the diamond to the upper surface of the support substrate, the support substrate being formed on the upper surface of the support substrate. A buried region made of a material having, diamond particles embedded in the buried region, distributed in an island shape in the upper surface of the support substrate, a part of the surface is exposed on the surface of the buried region, A diamond thin film structure is provided having the buried region and a diamond thin film formed directly on the diamond particles.

The diamond particles are buried in the buried region and firmly adhere to the substrate. The diamond film is strongly bonded to the diamond particles.

According to another aspect of the present invention, a step of supplying a diamond raw material onto a supporting substrate and forming diamond particles distributed in an island shape on the surface of the supporting substrate on the surface of the supporting substrate; Metal particles or ceramic particles are sprayed on the substrate to form a buried region made of metal or ceramic on a region of the surface of the support substrate where the diamond particles are not formed. A method of forming a diamond thin film, comprising: a step of exposing a portion of the diamond particle; and a step of depositing a diamond thin film on the surface of the diamond particle with a part of the surface exposed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a diamond thin film according to an embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1A, a substrate 1 made of a material that can withstand a diamond synthesis temperature of 700 to 1100 ° C., for example, a metal, a metal composite material, or a ceramic material is prepared.

As shown in FIG. 1B, the surface of the substrate 1 is irradiated with a plasma jet containing a diamond material. For example, a plasma jet of methane and a carrier gas is applied. Before the diamond nuclei attached to the surface of the substrate 1 are turned into a film, the irradiation of the plasma jet is stopped. Diamond particles 2 distributed in an island shape are formed on the surface of the substrate 1.

As shown in FIG. 1C, metal particles or ceramic particles are sprayed on the surface of the substrate 1. Substrate 1
A buried region 3 made of metal or ceramic is formed on a region of the surface where no diamond particles 2 are formed. The thickness of the buried region 3 is set so that a part of the surface of the diamond particle 2 is exposed on the surface of the buried region 3.

Metals which do not form a solid solution with carbon, such as Ti, Zr, Hf, V, Nb, Ta, M
o, W, or the like, or a metal composite material thereof can be used. However, there is no problem even if a metal that forms a solid solution with carbon, for example, Ni, Co, Fe, or the like is added as an additive to the sprayed particles so as to have a concentration of 10% or less. These additives may increase the adhesion between the buried region 3 and the substrate 1 in some cases. You may.

After the buried region 3 is deposited, the surface of the substrate 1 is heated by a plasma jet of argon or the like to perform sintering. Since the substrate is heated by the plasma jet, the temperature of the spray particles can be raised to the sintering temperature in a short time. Therefore, a strong bond can be generated between the spray particles or between the spray particles and the substrate before the carbonization of the diamond occurs.

As shown in FIG. 1D, a diamond material, for example, methane, is supplied together with a carrier gas to deposit a diamond thin film 4 on the surface of the substrate where a part of the surface of the diamond particles 2 is exposed. . The diamond thin film 4 is firmly bonded to the diamond particles 2. The diamond particles 2 are buried in the buried region 3, and the buried region 3 is strongly bonded to the surface of the substrate 1, so that the diamond particles 2 are firmly fixed to the substrate 1.

When a diamond thin film is directly deposited on the surface of the substrate 1, the adhesion between the diamond thin film and the substrate surface is weak. As shown in FIG. 1 (D), the diamond thin film 4 is strongly bonded to the diamond particles 2 embedded in the buried region 3 having a high adhesion to the surface of the substrate 1 so that the degree of adhesion of the diamond thin film to the substrate surface is improved. Can be increased.

Next, an evaluation experiment in which a diamond thin film is formed using the method for forming a diamond thin film according to the above embodiment will be described.

FIG. 2 is a schematic diagram of a DC plasma jet CVD apparatus used in the evaluation experiment. Manipulator 12
Thereby, the substrate holder 13 is supported in the chamber 10 so as to be able to move up and down. At the time of film formation, the substrate 14 is placed on the upper surface of the substrate holder 13. A cooling water passage is provided in the substrate holder 13 so that the substrate holder 13 and the substrate 14 can be water-cooled.

The plasma torch 20 is placed on the substrate holder 13.
Is arranged. The plasma torch 20 includes the center conductor 2
1. It includes a cylindrical inner conductor 22 and a cylindrical outer conductor 23. The inner conductor 22 surrounds the outer periphery of the center conductor 21, and the outer conductor 23 further surrounds the outer periphery of the inner conductor 22. The end of the outer conductor 23 inside the chamber 10 is shaped like a nozzle.

A positive DC bias 24 is applied to the center conductor with respect to the inner conductor 22 and the outer conductor 23. A source gas for diamond film formation is supplied into the internal cavity of the internal conductor 22. Arc discharge occurs between the tips of the center conductor 21 and the inner conductor 22, and plasma of the source gas is generated. The inside of the chamber 10 is set to a reduced pressure atmosphere, and a plasma of a source gas is injected into the chamber 10, and a plasma jet of the source gas irradiates the surface of the substrate 14. The residual gas is exhausted from the exhaust pipe 11 to the outside.

The spray particles are supplied together with the carrier gas into the cavity between the inner conductor 22 and the outer conductor 23. The sprayed particles are melted by the arc discharge generated at the tip of the plasma torch 20 and ejected into the chamber 10 from the nozzle-like tip of the outer conductor 23. The thermal spray particles collide with and adhere to the surface of the substrate 14.

The temperature of the substrate 14 is kept constant by heating the substrate 14 by the collision of the plasma jet or spray particles and cooling by the cooling water. The substrate temperature can be controlled by adjusting the distance between the substrate holder 13 and the plasma torch 20 by the manipulator 12. For example, when the substrate holder 13 is brought closer to the plasma torch 20, the temperature of the substrate 14 rises, and when it gets farther away, it falls.

Hereinafter, the evaluation experiment will be described with reference to FIGS. First, a first evaluation experiment will be described. As a substrate 1 shown in FIG. 1A, an equilateral triangular molybdenum (M) having a side length of 10 mm and a thickness of 2 mm is used.
o) was used.

In the step shown in FIG. 1 (B), an argon gas having a flow rate of 30 slm and a flow rate of 3
0 slm hydrogen gas and a volume concentration of 0.5 for hydrogen
% Methane gas was used. The diamond particles were formed for about 6 minutes under the conditions that the pressure in the chamber 10 was 30 Torr, the discharge output was 10 kW, and the substrate temperature was 900 ° C. Argon gas is a carrier gas, and hydrogen gas has an effect of removing graphite formed during the growth of diamond. The diameter of each diamond particle 2 formed under the above conditions was about 2-3 μm.

In the step shown in FIG. 1C, a mixed gas of argon and hydrogen is supplied to the cavity in the inner conductor 22 of FIG.
Mo particles having an average particle diameter of about 0.8 μm were supplied to the cavity between the inner conductor 22 and the outer conductor 23 together with the argon gas, and spraying was performed for about 5 minutes. Thereafter, the supply of the Mo particles is stopped, and the manipulator 12 is adjusted to adjust the substrate temperature to 1500.
C. and sintering was performed for about 30 seconds. About 2 ~
The Mo buried region 3 having a thickness of 3 μm was formed.

In the step shown in FIG. 1D, a diamond thin film is deposited under the same conditions as in FIG.
A diamond thin film 4 having a thickness of 0 to 20 μm was formed.

A cutting test was performed using a Mo bite tip having a diamond thin film formed thereon. As work material, A
An l-Si alloy (Si concentration 12%) (AC8A-T6) was used. The cutting method is continuous turning on the outer circumference, cutting speed is 10
00m / min, feed 0.2mm / rotation, cut 0.5
mm. When cutting was performed for 10,000 m under the above conditions, the flank wear width was about several μm, and no peeling of the diamond thin film occurred.

On the other hand, when the same cutting was carried out using a commercially available sintered diamond bite tip, the flank wear width was about several tens μm. This is because the surface of the bite chip formed by the first evaluation experiment is a polycrystalline diamond thin film, while the commercially available diamond bite tip is a sintered diamond.

As can be seen from the above-mentioned first evaluation experiment, it is possible to form a diamond thin film having high hardness and hard to peel off.

Next, a second evaluation experiment will be described.
As the substrate 1 shown in FIG. 1A, the length of one side is 10 m.
An equilateral triangular tungsten carbide (WC) bit tip having a thickness of 2 mm and a thickness of 2 mm was used. Note that this byte chip contains several% of Co as a binder. Prior to the formation of diamond particles, Co present on the bite chip surface was removed by etching using concentrated sulfuric acid. This is because if Co remains, it becomes difficult for diamond to grow.

The step shown in FIG. 1B is the same as in the first evaluation experiment. In the step shown in FIG. 1 (C), W particles having an average particle diameter of about 0.8 μm were sprayed for about 5 minutes, and thereafter sintering was performed at a substrate temperature of 2000 ° C. for 30 seconds. Under these conditions, a W buried region 3 having a thickness of about 2 to 3 μm was formed.

The process shown in FIG. 1D is the same as in the first evaluation experiment. Next, a third evaluation experiment will be described. The substrate used was a WC byte chip similar to that used in the second evaluation experiment. As in the second evaluation experiment, the concentration of Co2
Was removed by etching.

The process shown in FIG. 1B is the same as in the first evaluation experiment. In the step shown in FIG. 1C, mixed particles of Mo particles and Co particles having an average particle diameter of about 0.8 μm (mixing ratio of Mo and Co is 85:15) are sprayed for about 5 minutes, and then the substrate temperature is reduced. At 1500 ° C. for 30 seconds. Under these conditions, an embedded region 3 of MoCo having a thickness of about 2 to 3 μm was formed. Since Co acts as a binder, the adhesion between the buried region 3 and the substrate 1 can be further enhanced.

The step shown in FIG. 1D is the same as in the first evaluation experiment. Next, a fourth evaluation experiment will be described. The substrate used was a WC byte chip similar to that used in the second evaluation experiment. Prior to the step shown in FIG. 1B, Mo particles having an average particle diameter of 0.8 μm were sprayed to deposit a Mo thin film having a thickness of about 2 to 3 μm. Since the Mo thin film is deposited, it is not necessary to etch Co on the surface of the bite chip.

The process shown in FIG. 1B is the same as in the first evaluation experiment. In the step shown in FIG. 1C, Mo particles having an average particle diameter of about 0.8 μm were sprayed for about 5 minutes, and thereafter, sintering was performed at a substrate temperature of 1500 ° C. for 30 seconds. Under these conditions, a Mo buried region 3 having a thickness of about 2 to 3 μm was formed.

The step shown in FIG. 1D is the same as in the first evaluation experiment. Next, a fifth evaluation experiment will be described. The substrate used was a WC byte chip similar to that used in the second evaluation experiment. As in the second evaluation experiment, the concentration of Co2
Was removed by etching.

The step shown in FIG. 1B is the same as in the first evaluation experiment. In the step shown in FIG. 1C, a mixed particle of WC particles and Co particles having an average particle diameter of about 0.8 μm (mixing ratio of WC and Co is 85:15) is sprayed for about 5 minutes, and then the substrate temperature is increased. At 2000 ° C. for 30 seconds. Under this condition, a buried region 3 of WCCo having a thickness of about 2 to 3 μm was formed.

The step shown in FIG. 1D is the same as in the first evaluation experiment. A cutting test similar to that of the first evaluation experiment was performed using a bite chip manufactured by the method according to the second to fifth evaluation experiments. As in the case of the first evaluation experiment, peeling of the diamond thin film did not occur. Did not occur. Also,
The flank wear width was also about the same.

The diameter of the diamond particles distributed in the form of islands formed in the above-described evaluation experiment was about 2 to 3 μm, but the particle diameter that can be produced differs depending on the type of substrate, production conditions and the like. From various experimental results, it is considered that the diameter of the diamond particles is about 0.5 to 10 μm.

In the above evaluation experiment, the case where the surface of the bite tip is coated with the diamond thin film has been described. However, the surface of a tool other than the bite tip, for example, the surface of a drill blade, end mill blade or the like may be coated with the diamond thin film. . The life of the tool can be prolonged by coating with a diamond thin film having a high degree of adhesion. Further, the surface of the inner lead bonding tool may be covered with a diamond thin film. Since the degree of adhesion of the diamond thin film is high, polishing can be performed after the formation of the thin film, and the surface flatness can be improved.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0041]

As described above, according to the present invention,
The degree of adhesion of the diamond thin film formed on the substrate surface to the substrate can be increased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a substrate for explaining a method of forming a diamond thin film according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a DC plasma jet CVD apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Diamond particle 3 Embedding area 4 Diamond thin film 10 Chamber 11 Exhaust pipe 12 Manipulator 13 Substrate holder 14 Substrate 20 Plasma torch 21 Central conductor 22 Internal conductor 23 External conductor

Claims (3)

[Claims] A support substrate having an upper surface; an embedded region formed on the upper surface of the support substrate, the embedded region being made of a material having stronger adhesion than diamond to the upper surface of the support substrate; Diamond particles that are buried in and distributed like islands in the upper surface of the support substrate and a part of the surface is exposed on the surface of the buried region; and formed directly on the buried region and the diamond particles. And a diamond thin film structure. 2. A step of supplying a diamond raw material on a support substrate and forming diamond particles distributed in an island shape on the surface of the support substrate on the surface of the support substrate; and forming metal particles or ceramics on the support substrate. Spraying the particles, forming a buried region made of metal or ceramic on the region of the surface of the support substrate where the diamond particles are not formed, and exposing a part of the surface of the diamond particles. And a step of depositing a diamond thin film on the surface of the diamond particles with a part of the surface being exposed. 3. The step of forming the buried region includes, after spraying metal particles or ceramic particles, irradiating the surface of the substrate with a plasma jet to heat the buried region to a temperature equal to or higher than the sintering temperature of the buried region. Claim 2
3. The method for forming a diamond thin film according to item 1.