JP2001262342A - Method for depositing hard carbon film and device for depositing hard carbon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deposit a hard carbon film at a high film deposition rate and also at a low temperature in a method in which Ar plasma by electron cyclotron resonance is generated in a plasma generating chamber 4, the Ar plasma is applied on a substrate 9 arranged in a vacuum chamber 7, simultaneously, gaseous hydrocarbon is fed to the vacuum chamber 7, and a hard carbon film is deposited on the substrate 9. SOLUTION: As gaseous hydrocarbon, the one having an unsaturated bond such as gaseous ethylene and gaseous acetylene is used, the feeding flow rate of gaseous Ar is controlled to the one of gaseous hydrocarbon or below, the introducing power density of microwaves is controlled to the range of 0.02 to 0.15 W/cm3 per unit volume of the plasma generating chamber 4, and moreover, bias voltage substantially of -10 to -150 V is applied on the substrate 9.

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 a surface of a substrate such as an electric razor blade or a semiconductor. It relates to a method of forming.

[0002]

2. Description of the Related Art Hard carbon coatings are excellent in hardness, smoothness, etc., and are expected to be applied to various products as surface protective films. Some are already in practical use. For practical use, various approaches have been made. Among them, from the viewpoint of high-speed formation and low-temperature formation, hard carbon coatings have conventionally been formed by ECR plasma CVD. As the raw material gas, methane (CH ₄ ) gas or a mixed gas of methane gas, argon gas and / or hydrogen gas is used.

However, recently, Japanese Patent Laid-Open No.
As shown in -158050 discloses, ethylene (C ₂ H ₄₎ a method of forming the hard carbon film to use the gas has been proposed instead of the methane gas as a source gas. In this publication, the film formation rate is improved by optimizing the pressure of ethylene gas in the reaction chamber. However, the film formation rate was about 270 ° / min, which was still insufficient.

An object of the present invention is to provide a method and an apparatus for forming a hard carbon coating capable of forming a hard carbon coating at a high deposition rate and at a low temperature.

[0005]

According to the method of forming a hard carbon film of the present invention, Ar gas is supplied to a plasma generation chamber, and microwave power is introduced to generate Ar plasma by electron cyclotron resonance. A method of forming a hard carbon film on a substrate by simultaneously irradiating a plasma on a substrate on a substrate holder arranged in a vacuum chamber and supplying a hydrocarbon gas to the vacuum chamber to form a hard carbon film on the substrate. , A supply flow rate of the Ar gas is set to be equal to or less than a supply flow rate of the hydrocarbon gas, and a microwave input power density is set to 0.02 to 0.15 W / per unit volume of the plasma generation chamber.
cm ³ and substantially −10−−
It is characterized in that a bias voltage of 150 V is applied.

As the hydrocarbon gas having an unsaturated bond used in the present invention, specifically, ethylene (C
₂ H ₄ ) gas and acetylene (C ₂ H ₂ ) gas. In the present invention, the supply flow rate of the Ar gas is controlled to be equal to or less than the supply flow rate of the hydrocarbon gas. Further, an Ar gas is supplied into the plasma generation chamber, and a 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 supply flow rate of the Ar gas to be equal to or less than the supply flow rate of the hydrocarbon gas.

In addition, the input power density of the microwave is set to 0.02 to 0.15 W / cm per unit area of the plasma generation chamber.
By setting the range of ³ , a high film forming rate can be obtained without increasing the substrate temperature.

Further, the substrate is substantially -10 to -150 V
By applying the bias voltage, a hard carbon film having 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. By setting it in 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 −150 V.

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

The intermittent irradiation of the substrate with Ar plasma is as follows:
This 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.

Preferably, the hydrocarbon gas is introduced toward the inside of the shield cover. Thereby, the hydrocarbon gas is efficiently decomposed, and the film forming speed can be increased. In addition, mixing of hydrocarbon gas into the plasma generation chamber can be reduced, and adhesion of a film in the plasma generation chamber can be reduced.

The hard carbon film forming apparatus of the present invention is a hard carbon film forming apparatus for forming a hard carbon film on a substrate using a hydrocarbon gas having an unsaturated bond as a raw material gas. A vacuum chamber provided adjacent to the vacuum chamber, a plasma generation chamber for generating plasma for irradiating a substrate in the vacuum chamber, and an aperture provided between the vacuum chamber and the plasma generation chamber. And a microwave supply means for supplying microwaves to the plasma generation chamber, and a power supply for applying a bias voltage to the substrate.

In the apparatus for forming a hard carbon film according to the present invention, a partition plate having an aperture is provided between the vacuum chamber and the plasma generation chamber. For this reason,
The pressure in the plasma generation chamber can be increased, and Ar plasma can be generated and maintained with a smaller gas flow rate. In addition, since it is difficult for hydrocarbon gas to enter the plasma generation chamber, it is possible to reduce film adhesion in the plasma generation chamber. Therefore, maintenance including internal cleaning becomes easy. Further, since Ar plasma is introduced into the vacuum chamber through the aperture of the partition plate, A plasma is introduced.
The irradiation region of r plasma can be limited, and unnecessary temperature rise of the substrate and the substrate holder due to Ar plasma can be suppressed.

The apparatus for forming a hard carbon film of the present invention preferably has a rotatable cylindrical substrate holder for mounting a substrate on an outer peripheral surface, and an opening for introducing plasma from a plasma generation chamber. A shield cover for covering the substrate holder.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in more detail with reference to examples. However, the present invention is not limited to the following examples, and may be appropriately modified within the scope of the invention. It can be implemented by

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

In the vacuum chamber 7, a cylindrical substrate holder 8 is provided. The cylindrical substrate holder 8 is provided so as to be rotatable around an axis (not shown) vertically attached to the back surface of the vacuum chamber 7. A substrate 9 is mounted on the outer peripheral surface of the substrate holder 8,
A plurality of substrates 9 can be attached.

A high-frequency power supply 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 utilizes the fact that electrons follow the potential fluctuation during application of a high-frequency voltage because ions move at a slower speed due to an electric field in plasma than electrons, but ions cannot follow. Therefore, when a high frequency voltage is applied to the substrate 9, a negative bias voltage is generated in the substrate 9, positive ions in the plasma are attracted, and a hard carbon film is formed on the substrate 9.

A metallic 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
Are connected to a ground electrode.

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

An opening 12 is formed in the shield cover 11 below the aperture 14a of the partition plate 14. The plasma drawn out of the plasma generation chamber 4 is irradiated to the substrate 9 mounted on the substrate holder 8 through the opening 12. Here, when the substrate holder 8 rotates within the shield cover 11, the substrates 9 placed on the substrate holder 8 sequentially pass under the opening 12, and each substrate 9
, The plasma irradiated through the opening 12 is intermittently irradiated. Intermittent plasma irradiation can also 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 introduction pipe 13 for introducing ethylene gas as a source gas is provided in the vacuum chamber 7. The tip of the reaction gas introduction pipe 13 is located above the opening 12.

FIG. 2 is a plan view showing the vicinity of the tip of the reaction gas introduction pipe. As shown in FIG.
Reference numeral 3 denotes a gas introduction unit 13a for introducing a gas into the vacuum chamber 7, and a gas discharge unit 13b connected to the gas introduction unit 13a. Gas release unit 13
“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, since the gas is emitted toward the inside of the shield cover 11, the hole 21 is formed about 45 degrees below the gas emission portion 13b.
Eight are formed in the degree direction. By ejecting the source gas toward the inside of the shield cover 11 as described above, the source gas concentration in the vicinity of the substrate 9 is increased, the decomposition efficiency of the source gas is improved, and the diffusion of the source gas into the plasma generation chamber 4 is improved. As a result, decomposition of the source gas inside the plasma generation chamber 4 is reduced. For this reason, adhesion of the film to the inner wall of the plasma generation chamber 4 is reduced, which is effective for improving the utilization efficiency of the source gas and improving the maintenance.

Next, an experimental example in which a hard carbon film is formed on the surface of the substrate 9 using the apparatus shown in FIG. 1 will be described. [Experiment 1] First, a 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
^-6 Torr, and Ar gas is supplied from the discharge gas introducing pipe 5, and the microwave supply unit 1 supplies 2.45 to 2.45 Torr.
A microwave power of GHz was supplied to generate Ar plasma in the plasma generation chamber 4, and this plasma was applied to the substrate 9 through the aperture 14 a and the opening 12.
At this time, the substrate holder 8 was stopped without rotating. At the same time, ethylene (C
₂ H ₄₎ as well as introducing a gas, as the bias voltage of -50V to the substrate 9 is generated from the high frequency power source 10 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 / plasma generation chamber volume) was 0.1 W / cm ³
Set to. In FIG. 1, a 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 4
The flow rate of Ar gas was changed at a constant value of 0 sccm.
In Comparative Example 3, a mixed gas of an Ar gas and a C ₂ H ₄ gas was mixed at a flow rate as shown in Table 1 and supplied from the gas discharge pipe 13 into the vacuum chamber 7 to form a film. Table 1 shows the film forming rate under each condition.

Further, C ₂ H ₄ , C
Ar gas flow rate 20 sccm using ₂ H ₂ and CH ₄ ,
Film formation is performed under the condition of a hydrocarbon gas flow rate of 40 sccm,
The deposition rate at that time was determined. Table 2 shows the results. In each of the above film forming conditions, the degree of vacuum was 3 × 10 ⁻⁴ to 4
× 10 ⁻³ Torr.

[0028]

[Table 1]

[0029]

[Table 2]

As is clear from the results shown in Table 1, Ar
By separately introducing the gas and the C ₂ H ₄ gas, respectively, a high film forming rate is obtained. Further, by setting the supply flow rate of the Ar gas to be equal to or less 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 can be seen that a high film-forming rate can be obtained by using a hydrocarbon gas having an unsaturated bond, such as an ethylene gas or an acetylene gas, as the hydrocarbon gas.

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

The pressure inside the vacuum chamber was changed by controlling the exhaust valve while keeping the Ar gas flow rate and the C ₂ H ₄ gas flow rate constant. As a result, when the degree of vacuum is 1 × 10 ⁻⁴ Torr or less, it becomes difficult to maintain the plasma, and when the degree of vacuum is 1 × 10 ⁻² Torr or more, the Ar plasma is trapped in the plasma generation chamber and is not irradiated toward the substrate. Was. For this reason, the deposition rate is 100 ° at the maximum.
/ Min or less. These results show that the degree of vacuum is preferably in the range of 1 × 10 ⁻² to 1 × 10 ⁻⁴ Torr.

[Experiment 2] Next, a hard carbon film was formed by changing the bias voltage applied to the substrate while keeping the gas flow rate constant. Specific film forming conditions are as follows: Ar gas flow rate 20 s
Film formation was performed for 5 minutes while the substrate holder was fixed without rotating the substrate holder at ccm, a C ₂ H ₄ gas flow rate of 40 sccm, and a microwave power density of 0.1 W / cm ³ . The bias voltage applied to the substrate was varied from 0 to -200V. During the film formation, the substrate was not heated or cooled, and the substrate temperature after the film formation and the hardness of the formed film were measured. Table 3 shows the results.

[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. In Comparative Example 5 to which no bias voltage was applied, the hardness of the coating was extremely low, and a soft polymer carbon coating was formed. Further, since the hardness of the coating film sharply increases due to the application of the bias voltage, it can be seen that a coating film with high hardness can be formed by applying a substantially negative bias voltage. In Comparative Example 6 in which the bias voltage was -200 V, the hardness of the coating was low, but this is considered to be due to the effect of the rise 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 turns out that V is preferable.

[Experiment 3] Next, a hard carbon film was formed by changing the supplied microwave power while keeping the gas flow rate and the bias voltage constant. Specifically, the Ar gas flow rate was 20 sccm, the C ₂ H ₄ gas flow rate was 40 sccm, and the bias voltage was −50 V. The substrate holder was fixed without rotating, and a film was formed 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. As in Experiment 2, the substrate was not heated or cooled during the film formation, and the temperature of the substrate after the film formation and the hardness of the formed film were measured. Table 4 shows the results.

[0038]

[Table 4]

The microwave power density is set to 0.01 W / cm ³
In Comparative Example 7, the generation of plasma was difficult to maintain, and a film could not be formed. As is clear from the results shown in Table 4, it is understood that the film formation rate increases as the microwave power density increases. However, at the same time, the substrate temperature also rises, and when it reaches 0.2 W / cm ³ , the substrate temperature rises to 250 ° C., indicating that the hardness of the coating film has decreased due to this effect. Therefore, the microwave power density is 0.02 to 0.15 W / cm ³
It turns out that the range of is preferable.

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

As a result, a hard carbon film (having a hardness of about 3000 Hv) having a thickness of about 1 μm was uniformly formed on each Si substrate. The substrate temperature after film formation was about 50 ° C. Therefore, when a film is formed in a state where the position of the substrate is fixed without rotating the substrate holder 8 (Example 11 of Experiment 3)
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, a high-frequency voltage is applied to the substrate to generate a negative bias voltage. However, the same effect can be obtained when a 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 the 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 as viewed from above.

[Explanation of symbols]

 DESCRIPTION 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 ... Substrate holder 9 ... Substrate 10 ... High frequency power supply 11 ... Shield Cover 12 ... Opening 13 ... Reaction gas introduction pipe 14 ... Partition plate 14a ... Aperture 21 ... Gas release hole

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K030 AA09 AA10 CA02 CA04 FA02 GA07 JA05 JA16 JA17 KA12 LA22 5F058 BA12 BA20 BB10 BC14 BC20 BF08 BF26 BJ03

Claims (10)

[Claims] 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 on a substrate on a substrate holder disposed in a vacuum chamber. Simultaneously, supplying a hydrocarbon gas to the vacuum chamber to form a hard carbon film on the substrate, wherein a hydrocarbon gas having an unsaturated bond is used as the hydrocarbon gas; The supply flow rate is not more than the supply flow rate of the hydrocarbon gas, the input power density of the microwave is in the range of 0.02 to 0.15 W / cm ³ per unit volume of the plasma generation chamber, and the substrate is substantially coated with the microwave. Applying a bias voltage of -10 to -150V to the hard carbon film. 2. The method 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 film according to claim 1, wherein the thickness is in a range of 10 ⁻² to 1 × 10 ⁻⁴ Torr. 4. The method according to claim 1, wherein one of a high-frequency voltage and a pulse voltage is applied to the substrate.
4. The method for forming a hard carbon film according to any one of items 3 to 3. 5. The substrate according to claim 1, wherein the substrate is irradiated with the Ar plasma intermittently.
The method for forming a hard carbon film according to the above item. 6. The method according to claim 5, wherein the substrate is irradiated with Ar plasma intermittently by rotating the substrate holder. 7. The method according to claim 6, wherein the substrate holder is rotated within a shield cover having an opening. 8. The method according to claim 7, wherein the hydrocarbon gas is introduced toward the inside of the shield cover. 9. A hard carbon film forming apparatus for forming a hard carbon film on a substrate using a hydrocarbon gas having an unsaturated bond as a source gas, comprising: a vacuum chamber in which the substrate is disposed; A plasma generation chamber that is provided adjacent to the chamber and generates plasma for irradiating a substrate in the vacuum chamber; and a partition plate provided with an aperture and provided between the vacuum chamber and the plasma generation chamber. And a microwave supply means for supplying microwaves to the plasma generation chamber; and a power supply for applying a bias voltage to the substrate. 10. A rotatable cylindrical substrate holder for mounting the substrate on an outer peripheral surface, and a shield cover for covering the substrate holder, the shield cover having an opening for introducing plasma from the plasma generation chamber. The hard carbon film forming apparatus according to claim 9, further comprising: