JP3443381B2 - Method of forming hard carbon coating - 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 hard carbon film on the surface of a substrate such as an electric razor blade or a semiconductor, and particularly to a method for forming a hard carbon film by ECR (electron cyclotron resonance) plasma CVD method. It relates to a method of forming.

[0002]

2. Description of the Related Art Hard carbon coatings are materials that are expected to be applied to various products as surface protection coatings because they have excellent hardness and smoothness. Some have already been put to practical use. Various efforts have been made to put it into practical use. Above all, from the viewpoint of high-speed formation and low-temperature formation, a hard carbon film has been conventionally formed by the ECR plasma CVD method. As the raw material gas, methane (CH ₄ ) gas or a mixed gas of methane gas and argon gas and / or hydrogen gas is used.

However, in recent years, Japanese Unexamined Patent Publication No. Hei 8
As disclosed in JP-A-158050, a method for forming a hard carbon coating using ethylene (C ₂ H ₄ ) gas instead of methane gas as a raw material gas has been proposed. In this publication, the film formation rate is improved by optimizing the pressure of ethylene gas in the reaction chamber. However, the film forming rate was about 270 Å / min, which was still insufficient.

An object of the present invention is to provide a form how the hard carbon film capable of forming a hard carbon film is and at low temperature high deposition rate.

[0005]

According to the method for forming a hard carbon coating of the present invention, Ar gas is supplied to a plasma generating chamber and microwave power is introduced to generate Ar plasma by electron cyclotron resonance. plasma and simultaneously irradiating the substrate on the substrate holder was placed in a vacuum chamber and by supplying a hydrocarbon gas into the vacuum chamber, a method of forming the hard carbon film to form a hard carbon film on a substrate comprising a vacuum chamber Between the plasma generation chamber
A partition plate with an aperture is provided, and a hydrocarbon gas having an unsaturated bond is used as the hydrocarbon gas, the Ar gas supply flow rate is set to be equal to or lower than the hydrocarbon gas supply flow rate, and the microwave input power density is plasma-generated. It is characterized in that it is set in the range of 0.02 to 0.15 W / cm ³ per unit volume of the chamber and that a bias voltage of substantially -10 to -150 V is applied to the substrate.

The hydrocarbon gas having an unsaturated bond used in the present invention is specifically ethylene (C
₂ H ₄ ) gas, acetylene (C ₂ H ₂ ) gas and the like can be mentioned. In the present invention, the Ar gas supply flow rate is controlled to be equal to or lower than the hydrocarbon gas supply flow rate. Further, Ar gas is supplied into the plasma generation chamber and hydrocarbon gas is supplied into the vacuum chamber. According to the present invention, a high film forming rate can be obtained by separately supplying the Ar gas and the hydrocarbon gas and setting the Ar gas supply flow rate to be equal to or lower than the hydrocarbon gas supply flow rate.

The microwave input power density is 0.02 to 0.15 W / cm per unit area of the plasma generating chamber.
By setting the range to ³ , a high film formation rate can be obtained without raising the substrate temperature.

Also, the substrate is substantially -10 to -150V.
By applying the bias voltage of, a hard carbon coating with high hardness can be formed. In the present invention, the degree of vacuum in the vacuum chamber is 1 × 10 ⁻² to 1 × 10 ⁻⁴ T.
It is preferably within the range of orr. Within such a range, a particularly high film formation rate can be obtained.

In the present invention, by applying either a high frequency voltage or a pulse voltage to the substrate,
It is preferable to apply a bias voltage of -10 to -150V.

Further, in the present invention, the substrate may be intermittently irradiated with Ar plasma. By intermittently irradiating the substrate with Ar plasma, the temperature rise of the substrate during film formation can be suppressed, and damage to the substrate can be reduced.

The intermittent irradiation of Ar plasma on the substrate is
It may be performed by rotating the substrate holder. At this time, preferably, the substrate is intermittently irradiated with Ar plasma by rotating the substrate holder within a shield cover having an opening.

The hydrocarbon gas is preferably introduced toward the inside of the shield cover. As a result, the hydrocarbon gas is efficiently decomposed and the film formation rate can be increased. Further, it is possible to reduce mixing of hydrocarbon gas into the plasma generation chamber, and it is possible to reduce deposition of a film in the plasma generation chamber.

[0013]

[0014]

[0015]

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and may be appropriately modified within the scope of the invention. It is possible to carry out.

FIG. 1 is a schematic sectional view showing a hard carbon film forming apparatus of an embodiment according to the present invention. Referring to FIG.
The microwave generated by the microwave supply means 1 is guided to the plasma generation chamber 4 through the waveguide 2 and the microwave introduction window 3. A discharge gas such as argon (Ar) gas is introduced into the plasma generation chamber 4 through a discharge gas introduction pipe 5. A magnetic circuit 6 for plasma generation is provided around the plasma generation chamber 4. A high-density plasma is generated in the plasma generation chamber 4 by applying a high-frequency electric field generated by microwaves and a magnetic field from the magnetic circuit 6. This plasma is guided into the vacuum chamber 7 along the divergent magnetic field by the magnetic circuit 6 through the aperture 14 a of the partition plate 14.

Inside the vacuum chamber 7, a cylindrical substrate holder 8 is provided. The cylindrical substrate holder 8 is rotatably provided around an axis (not shown) mounted perpendicularly to the back surface of the vacuum chamber 7. A substrate 9 is mounted on the outer peripheral surface of the substrate holder 8,
It is possible to attach a plurality of substrates 9.

A high frequency power source 10 (frequency 13.56 MHz, maximum output 300 W) is connected to the substrate holder 8, and a desired negative bias voltage can be applied to the substrate 9 by changing the output. This is because the moving speed of the ions due to the electric field in the plasma is slower than that of the electrons, so that the electrons can follow the fluctuation of the potential during the application of the high frequency voltage, but the ions cannot. Therefore, by applying a high frequency voltage to the substrate 9, a negative bias voltage is generated in the substrate 9, positive ions in the plasma are drawn in, and a hard carbon film is formed on the substrate 9.

A metal cylindrical shield cover 11 is provided around the substrate holder 8 at a predetermined distance from the outer peripheral surface of the substrate holder 8. Cylindrical shield cover 11
Is connected to the ground electrode.

The shield cover 11 is provided in order to prevent discharge from occurring between the substrate holder 8 and the vacuum chamber 7 other than the film forming location due to the high frequency voltage applied to the substrate holder 8 during film formation. ing.
The gap between the substrate holder 8 and the shield cover 11 is preferably several mm to several cm, though it depends on the degree of vacuum. In addition,
In this embodiment, the distance is about 1 cm.

An opening 12 is formed in the portion of the shield cover 11 below the aperture 14a of the partition plate 14. The plasma drawn from the plasma generation chamber 4 passes through the opening 12 and irradiates the substrate 9 mounted on the substrate holder 8. Here, when the substrate holder 8 rotates within the shield cover 11, the substrate 9 installed on the substrate holder 8 sequentially passes under the opening 12, and each substrate 9
However, the plasma emitted through the opening 12 is intermittently emitted. The intermittent irradiation of plasma can be performed by providing a shutter between the opening 12 and the plasma generation chamber 4 and opening and closing the shutter.

A reaction gas introducing pipe 13 for introducing ethylene gas as a raw material gas is provided in the vacuum chamber 7. The tip of the reaction gas introducing pipe 13 is located above the opening 12.

FIG. 2 is a plan view showing the vicinity of the tip of the reaction gas introducing pipe. As shown in FIG. 2, the reaction gas introduction pipe 1
3 is composed of a gas introducing portion 13a for introducing gas into the vacuum chamber 7 and a gas releasing portion 13b connected to the gas introducing portion 13a. Gas release unit 13
The symbol b is for discharging a uniform gas to the substrate holder 8 and has a plurality of holes 21 formed therein. In the present embodiment, the gas is discharged toward the inside of the shield cover 11, so that the hole 21 is formed below the gas discharge portion 13b by about 45 mm.
Eight are formed in the degree direction. By injecting the source gas toward the inside of the shield cover 11 in this manner, the concentration of the source gas near the substrate 9 is increased, the decomposition efficiency of the source gas is improved, and the source gas is diffused into the plasma generation chamber 4. As a result, the decomposition of the raw material gas inside the plasma generation chamber 4 is reduced. Therefore, the adhesion of the film to the inner wall of the plasma generating chamber 4 is reduced, which is effective for improving the utilization efficiency of the source gas and the maintenance.

Next, an experimental example of forming a hard carbon film on the surface of the substrate 9 using the apparatus shown in FIG. 1 will be described. [Experiment 1] First, the substrate 9 made of Si was mounted on the outer peripheral surface of the substrate holder 8. Next, the inside of the vacuum chamber 7 is changed to 10
^The gas is exhausted to ^-6 Torr, Ar gas is supplied from the discharge gas introduction pipe 5, and the microwave supply means 1 to 2.45.
A microwave power of GHz was supplied to generate Ar plasma in the plasma generation chamber 4, and the plasma was irradiated onto the substrate 9 through the aperture 14a and the opening 12.
At this time, the substrate holder 8 was not rotated and was in a stopped state. At the same time, ethylene (C
₂ H ₄ ) gas is introduced and the high frequency power supply 10 to 13.
A high frequency voltage of 56 MHz was applied to the substrate holder 11. By performing the above steps for 5 minutes, a hard carbon film was formed on the substrate 9. The microwave power density (input power / volume of plasma generation chamber) was 0.1 W / cm ^3.
Set to. In FIG. 1, the region corresponding to the volume of the plasma generation chamber 4 is hatched.

As shown in Table 1, the flow rate of C ₂ H ₄ gas was changed to 4
The flow rate of Ar gas was changed while keeping it constant at 0 sccm.
In Comparative Example 3, a mixed gas of Ar gas and C ₂ H ₄ gas was mixed at the flow rates shown in Table 1 and supplied from the gas discharge tube 13 into the vacuum chamber 7 to form a film. Table 1 shows the film forming rates under the respective conditions.

Further, as the hydrocarbon gas, C ₂ H ₄ , C
₂ H ₂ and CH ₄ are used, Ar gas flow rate is 20 sccm,
A film is formed under the condition of a hydrocarbon gas flow rate of 40 sccm,
The film forming rate at that time was obtained. The results are shown in Table 2. Under each of the above film forming conditions, the degree of vacuum is 3 × 10 ⁻⁴ to 4
It was in the range of × 10 ^-3 Torr.

[0028]

[Table 1]

[0029]

[Table 2]

As is clear from the results shown in Table 1, Ar
By introducing the gas and the C ₂ H ₄ gas separately, a high film formation rate is obtained. Further, by setting the supply flow rate of the Ar gas to be equal to or lower than the supply flow rate of the hydrocarbon gas, a particularly high film formation rate is obtained.

From the results shown in Table 2, it is understood that a high film forming rate can be obtained by using a hydrocarbon gas having an unsaturated bond such as ethylene gas or acetylene gas as the hydrocarbon gas.

Under each of the above film forming conditions, the substrate temperature after film formation (the substrate temperature immediately after film formation and the maximum temperature raised by the film forming process) is 100 ° C. or less,
The hardness of each of the formed coatings was 3000 Hv or higher.

Further, the pressure in the vacuum chamber was changed by keeping the Ar gas flow rate and the C ₂ H ₄ gas flow rate constant and controlling the exhaust valve. As a result, it becomes difficult to maintain the plasma when the degree of vacuum is 1 × 10 ⁻⁴ Torr or less, and when the degree of vacuum is 1 × 10 ⁻² Torr or more, Ar plasma is trapped in the plasma generation chamber and is not irradiated to the substrate. It was Therefore, the film deposition rate is 100 Å at the maximum.
/ Min or less. From these results, it is understood that the vacuum degree is preferably in the range of 1 × 10 ^-2 to 1 × 10 ^-4 Torr.

[Experiment 2] Next, the gas flow rate was kept constant and the bias voltage applied to the substrate was changed to form a hard carbon film. The specific film forming conditions are Ar gas flow rate of 20 s.
ccm, C ₂ H ₄ gas flow rate of 40 sccm, microwave power density of 0.1 W / cm ³ , the substrate holder was fixed without rotation, and film formation was performed for 5 minutes. The bias voltage applied to the substrate was changed from 0 to -200V. During film formation, the substrate was not heated or cooled, and the substrate temperature after film formation and the hardness of the formed film were measured. The results are shown in Table 3.

[0035]

[Table 3]

From the results shown in Table 3, it can be seen that the substrate temperature after film formation increases as the absolute value of the bias voltage increases. Further, in Comparative Example 5 in which the bias voltage was not applied, it was found that the hardness of the coating was extremely low and a soft, polymeric carbon coating was formed. Further, since the hardness of the coating film is rapidly increased by applying the bias voltage, it can be seen that the coating film having high hardness can be formed by applying the substantially negative bias voltage. Further, in Comparative Example 6 in which the bias voltage is −200 V, the hardness of the coating film is low, which is considered to be due to the increase in the substrate temperature. From the above results, the substrate temperature is preferably 200 ° C. or lower, and the bias voltage is −10 to −150.
It can be seen that V is preferable.

[Experiment 3] Next, a hard carbon film was formed by keeping the gas flow rate and the bias voltage constant and changing the microwave power to be applied. The specific conditions were an Ar gas flow rate of 20 sccm, a C ₂ H ₄ gas flow rate of 40 sccm, and a bias voltage of -50V. The substrate holder was fixed without rotating and film formation was performed for 5 minutes. The microwave power density was changed in the range of 0.01 to 0.2 W / cm ³ as shown in Table 4. Similar to Experiment 2, the substrate was not heated or cooled during the film formation, and the substrate temperature after the film formation and the hardness of the formed film were measured. The results are shown in Table 4.

[0038]

[Table 4]

The microwave power density is 0.01 W / cm ³
In Comparative Example 7, it was difficult to maintain the generation of plasma, and the coating could not be formed. As is clear from the results shown in Table 4, increasing the microwave power density increases the film forming rate. However, at the same time, the substrate temperature rises, and when it reaches 0.2 W / cm ³ , the substrate temperature rises to 250 ° C., and it is understood that the hardness of the coating film is lowered due to this influence. Therefore, the microwave power density is 0.02 to 0.15 W / cm ³
It can be seen that the range is preferable.

[Experiment 4] 1 is attached to the outer peripheral surface of the substrate holder 8.
Zero Si substrates 9 were mounted at equal intervals, and a hard carbon coating was formed while rotating the substrate holder 8 at a speed of 5 rpm. The film forming conditions are microwave power density of 0.1 W / c.
m ³ and other conditions are the same as in Experiment 3 above,
The film was formed for 0 minutes.

As a result, a hard carbon coating (hardness: about 3000 Hv) having a film thickness of about 1 μm was uniformly formed on each Si substrate. The substrate temperature after film formation was about 50 ° C. Therefore, when the film is formed with the position of the substrate fixed without rotating the substrate holder 8 (Example 11 of Experiment 3)
The substrate temperature was lower than 70 ° C. Therefore, it can be seen that by rotating the substrate holder and intermittently irradiating the substrate with Ar plasma, the temperature rise of the substrate can be suppressed and damage to the substrate can be reduced.

In the above embodiment, the high frequency voltage is applied to the substrate to generate the negative bias voltage on the substrate. However, the same effect can be obtained when the pulse voltage is applied instead of the high frequency voltage. Have confirmed.

[0043]

According to the present invention, a hard carbon film can be formed at a high film forming rate and at a low temperature.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a hard carbon film forming apparatus according to the present invention.

FIG. 2 is a plan view of the vicinity of a reaction gas introduction pipe in the apparatus shown in FIG. 1 seen from above.

[Explanation of symbols]

1. Microwave supply means 2 ... Waveguide 3 ... Microwave introduction window 4 Plasma generation chamber 5 ... Discharge gas introduction pipe 6 ... Magnetic circuit 7 ... Vacuum chamber 8 ... Board holder 9 ... Substrate 10 ... High frequency power supply 11 ... Shield cover 12 ... Opening 13 ... Reaction gas introduction pipe 14 ... Partition board 14a ... Aperture 21 ... Gas release hole

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-64468 (JP, A) JP-A-7-62539 (JP, A) JP-A-8-158050 (JP, A) JP-A-2- 250976 (JP, A) JP-A-6-264246 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 16/00-16/56

Claims (8)

(57) [Claims] 1. An Ar gas is supplied to a plasma generation chamber and microwave power is introduced to generate Ar plasma by electron cyclotron resonance, and the Ar plasma is irradiated onto a substrate on a substrate holder arranged in a vacuum chamber. At the same time, a hydrocarbon gas is supplied to the vacuum chamber to form a hard carbon coating on the substrate, wherein an aperture is provided between the vacuum chamber and the plasma generation chamber.
A partition plate on which a char is formed is provided, and a hydrocarbon gas having an unsaturated bond is used as the hydrocarbon gas, and the supply flow rate of the Ar gas is set to be equal to or less than the supply flow rate of the hydrocarbon gas. Hard carbon characterized in that the density is set in the range of 0.02 to 0.15 W / cm ³ per unit volume of the plasma generation chamber, and a bias voltage of substantially -10 to -150 V is applied to the substrate. Method of forming coating film. 2. The method for forming a hard carbon coating according to claim 1, wherein C ₂ H ₄ and / or C ₂ H ₂ is used as the hydrocarbon gas having an unsaturated bond. 3. The degree of vacuum in the vacuum chamber is 1 ×
The method for forming a hard carbon coating according to claim 1, wherein the hard carbon coating is in the range of 10 ⁻² to 1 × 10 ⁻⁴ Torr. 4. A high frequency voltage or a pulse voltage is applied to the substrate.
4. The method for forming a hard carbon coating according to any one of 3 to 3. 5. The substrate according to claim 1, wherein the substrate is intermittently irradiated with the Ar plasma.
Item 8. A method for forming a hard carbon film according to item. 6. The method for forming a hard carbon coating according to claim 5, wherein the substrate holder is rotated to intermittently irradiate the substrate with Ar plasma. 7. The method for forming a hard carbon coating according to claim 6, wherein the substrate holder is rotated in a shield cover having an opening. 8. The method for forming a hard carbon coating according to claim 7, wherein the hydrocarbon gas is introduced toward the inside of the shield cover.