JP2975817B2 - Diamond-like film forming method - 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 diamond-like coating on the surface of an electric razor blade or a semiconductor material for the purpose of improving its characteristics and protecting the surface.
The present invention relates to a method for forming a diamond-like coating by a CR (Electron Cyclotron Resonance) plasma CVD method.

[0002]

2. Description of the Related Art In recent years, as a method for forming a diamond-like film, an ECR plasma capable of forming a film at a lower temperature at a higher film forming rate than conventional methods such as an ion plating method using an electron gun and an ion beam sputtering method. The CVD method has been proposed as disclosed in Japanese Patent Application Laid-Open No. 3-175620, and has already been put to practical use.

The formation of a diamond-like film by the ECR plasma CVD method will be described with reference to FIG.
FIG. 6 is a schematic sectional view of a conventional ECR plasma CVD apparatus.

In FIG. 1, reference numeral 1 denotes a microwave supply means, and the microwave generated by the microwave supply means 1 is guided to a plasma generation chamber 4 through a waveguide 2 and a microwave introduction window 3. . Reference numeral 5 denotes a discharge gas introduction pipe for introducing a discharge gas such as argon (Ar) gas into the plasma generation chamber 4, and reference numeral 6 denotes a magnetic circuit for generating plasma arranged around the plasma generation chamber 4, and a high frequency electric field generated by microwaves. And a magnetic field from the magnetic circuit 6 acts to form high-density plasma in the plasma generation chamber 4. Then, the plasma is guided to the vacuum chamber 8 in which the substrate 7 is arranged along the divergent magnetic field generated by the magnetic circuit 6.

Reference numeral 9 denotes a reaction gas introduction pipe for introducing methane (CH ₄ ) gas as a source gas into the vacuum chamber 8, and the introduced CH ₄ gas is decomposed by the action of plasma. Reference numeral 10 denotes a high-frequency power supply (for example, 13.56 MHz) which applies a predetermined high-frequency voltage (RF voltage) to the substrate holder 11 to generate a negative self-bias on the substrate 7.
This utilizes the fact that ions move at a lower speed due to an electric field in the plasma than electrons, and thus follow the potential fluctuation during application of an RF voltage, but cannot follow ions. Therefore, by applying the RF voltage to the substrate 7, many electrons are emitted to the substrate 7,
, A negative self-bias is generated, positive ions in the plasma are attracted, and a diamond-like film is formed on the substrate 7.

[0006]

However, in the above prior art, the above ECR plasma CVD apparatus is used to supply a raw material gas from a reaction gas introduction pipe into a plasma flow of a discharge gas supplied from a discharge gas pipe. However, the conditions for forming a diamond-like film on the substrate surface are not disclosed, and it is not clear which condition is most suitable for forming a diamond-like film having a high hardness on the substrate surface. Was.

The present invention has been made in view of the above, and has as its object to form a diamond-like coating having high hardness on a substrate surface.

[0008]

According to the present invention, an Ar gas is supplied to a plasma generation chamber, an Ar plasma is generated by electron cyclotron resonance by introducing a microwave, and the Ar plasma is disposed in a vacuum chamber. Simultaneously irradiating the substrate with a predetermined high-frequency voltage and supplying a CH ₄ gas into the Ar plasma stream to form a diamond-like film on the substrate. The method is characterized in that the high-frequency voltage is applied so that the self-bias generated in the substrate becomes -20 V or less, and the substrate is irradiated with plasma intermittently. The present invention also supplied partial pressure of the Ar gas, and CH ₄ feed partial pressure of the gas 1.0 × 10 @ -4 Torr or more 2
A diamond-like film is formed on the substrate by setting the pressure to 0.0 × 10 −4 Torr or less.

[0009]

According to the present invention, a diamond-like coating having high hardness can be formed on the substrate surface by controlling the self-bias generated on the substrate during the formation of the diamond-like coating.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing one embodiment. FIG. 1 is a schematic sectional view showing an apparatus for forming a diamond-like film as one embodiment of the present invention. The same components as those in the above-described conventional example (FIG. 6) are denoted by the same reference numerals.

In FIG. 1, reference numeral 12 denotes a cylindrical substrate holder, which is rotatably provided around a shaft (not shown) which is vertically pivotally attached to the back surface of the vacuum chamber 8. 13
Is a substrate mounted on the peripheral side surface of the cylindrical substrate holder 12, and a plurality of substrates 13 are mounted at equal intervals.
In this embodiment, silicon (Si) as the substrate 13 is used.
Using a substrate, several tens are mounted on the peripheral side surface of the substrate holder 12.

The substrate holder 12 has an oscillation frequency of 1
The high frequency power supply 10 of 3.56MHz, maximum output 300W is connected,
By changing the output, an RF voltage for generating a desired negative self-bias on the substrate 13 is applied to the substrate holder 12.

Reference numeral 14 denotes a metallic cylindrical shield cover provided at a predetermined distance so as to surround the peripheral side surface of the substrate holder 12, and is connected to a ground electrode.

The shield cover 14 is provided to prevent a discharge from occurring between the substrate holder 12 and the vacuum chamber 8 other than where the film is formed due to the RF voltage applied to the substrate holder 12 when the film is formed. The distance between the substrate holder 12 and the shield cover 14 is smaller than the mean free path of electrons. That is, the gap between the substrate holder 12 and the shield cover 14 is set to be equal to or less than the average free path of electrons, that is, equal to or less than the average distance at which electrons generated for some reason can be accelerated by an electric field and move without colliding with gas atoms. This lowers the probability that electrons collide with gas atoms and prevents avalanche-induced ionization.

Therefore, in order to prevent the occurrence of electric discharge at a place other than the film forming portion, the substrate holder 12 and the shield cover 1 are required.
It is necessary to set the gap with the electron free path to a distance equal to or less than the mean free path of electrons, and this is particularly effective when the distance is equal to or less than 1/10 of the mean free path of electrons. In this embodiment, the substrate holder 1
The gap between 2 and the shield cover 14 was set to about 5 mm, which is 1/10 or less of the mean free path of electrons.

An opening 15 is provided in the cylindrical shield cover 14 below the plasma generating chamber 4, and the plasma flow drawn out of the plasma generating chamber 4 through the opening 15 is used for the cylindrical substrate 14. Substrate 1 mounted on holder 12
3 to be radiated. Reference numeral 16 denotes a reaction gas introduction pipe, which is provided above the opening 15. As shown in FIG. 2, the reaction gas introduction pipe 16 is provided with a gas introduction section 16a for introducing CH ₄ gas into the vacuum chamber 8 from outside.
And a gas discharge portion 16b connected in a T-shape to the introduction portion 16a. Then, the gas release unit 16
b is arranged perpendicular to the rotation direction of the substrate holder 12 and is mounted so as to be located above the opening 15 and on the upstream side in the rotation direction. In the gas discharge part 16b,
A plurality of holes 2 in a direction about 45 degrees downward toward the rotation direction.
1 (eight in the present embodiment) are formed, and the holes 2
The pitch of 1 is the largest on the gas introduction part 16a side, and gradually decreases as the distance from the gas introduction part 16a increases. Thereby, the CH ₄ gas introduced from the introduction section 16a is uniformly ejected from each hole 21 of the emission section 16b.

Next, a method of forming a diamond-like coating on the surface of the substrate 13 using the above-described apparatus will be described.

First, several tens of Si substrates 13 are mounted on the peripheral side surface of the substrate holder 12 at equal intervals. Then, the inside of the vacuum chamber 8 is evacuated to 10 ^-5 to 10 ^-7 Torr, and the substrate holder 12 is
Rotate at a speed of 10 rpm. Next, ECR plasma CV
The Ar gas is supplied from the discharge gas introducing pipe 5 of the D apparatus, and a microwave of 2.45 GHz and 200 W is supplied from the microwave supply means 1 so that the Ar gas formed in the plasma generation chamber 4 is formed.
Plasma is emitted to the surface of the substrate 13. At the same time,
An RF voltage of 13.56 MHz is applied to the substrate holder 12 from the high frequency power supply 10 so that a negative self-bias is generated in the substrate 13, and CH ₄ gas is supplied from the reaction gas introduction pipe 16.
Thereby, the CH ₄ supplied from the reaction gas introduction pipe 16 is
The gas is decomposed by the action of the plasma, and the carbon becomes highly reactive ions or a neutral active state, and is emitted to the surface of the substrate 13. By performing the above steps, a diamond-like coating is formed on the surface of the substrate 13.

FIG. 3 is a graph showing the relationship between the film forming time and the substrate temperature when a diamond-like film is formed on the surface of the substrate 13 by using the above-described film forming method. The self-bias generated on the substrate 13 is −50.
The RF voltage of 30 W output from the high-frequency power source 10 is applied to the substrate holder 12 so that the supply voltage of the Ar gas supplied from the discharge gas introduction pipe 5 is 5.7 × 10 ⁻⁴ Torr. The supply partial pressure of CH ₄ gas supplied from
Set to ^-3 Torr.

The three straight lines in the figure represent the case where the coating is formed with the above configuration, the case where the coating is formed without rotating the substrate holder 12 in the above configuration, and the case where the coating is formed without providing the shield cover 14 in the above configuration. Are shown respectively.

As shown in the figure, after the elapse of the film formation time of 15 minutes, about 40 ° C. in the above case and about 60 ° C. in the above case.
On the other hand, in the above case, the temperature is about 150 ° C., and when the film is formed without providing the shield cover 14 as described above, the space between the substrate holder 12 and the vacuum chamber 8 other than the film forming portion is formed. It can be seen that discharge occurred and the substrate temperature rose and became high. Also, shield cover 1
4, when the film is formed, the temperature rise is smaller when the substrate holder 12 is rotated than when the substrate holder 12 is stationary. Therefore, by surrounding the peripheral side surface of the substrate holder 12 with the shield cover 14 and performing the film forming process while rotating the substrate holder 12, it is possible to perform film formation while maintaining the substrate 13 at a low temperature. 1
There is no need to consider the heat resistance of No. 3.

Next, in the above-mentioned method for forming a diamond-like film, an RF voltage is applied so that a self-bias generated in the substrate 13 becomes -50 V, and the reaction gas introduction pipe 1 is formed.
The supply partial pressure of CH ₄ gas supplied from 6 was set to 3.0 × 10 ^-4 Torr,
FIG. 4 shows a change in coating hardness with respect to the supply partial pressure of the Ar gas supplied from the discharge gas introduction pipe 5 in the case of setting to 1.0 × 10 ⁻³ Torr or 1.3 × 10 ⁻³ Torr. Here, the film hardness represents Vickers hardness and was measured based on the standard of JIS G0202.

Ar supplied from the discharge gas introducing pipe 5
The gas supply partial pressure was set to 5.7 × 10 ^-4 Torr and the reaction gas introduction pipe 1
The coating hardness with respect to the self-bias when the supply partial pressure of the CH ₄ gas supplied from 6 is set to 1.0 × 10 ⁻³ Torr and the output of the high-frequency power supply 10 is varied to change the self-bias generated on the substrate 13 5 is shown in FIG.

The supply partial pressure of the Ar gas supplied from the discharge gas introduction pipe 5 and the C supplied from the reaction gas introduction pipe 16
Similar results were obtained in FIGS. 4 and 5 even when the supply partial pressure of the H ₄ gas was set to another value of 1.0 to 20.0 × 10 ⁻⁴ Torr.

As shown in FIG. 4, regardless of the partial pressure of the Ar gas supplied from the discharge gas introducing pipe 5,
000 Hv, and the same result is obtained when the supply partial pressure of the CH ₄ gas supplied from the reaction gas introduction pipe 16 is varied. That is, it can be seen from this figure that a diamond-like coating having a predetermined coating hardness is formed on the surface of the substrate 13 irrespective of the supply partial pressures of the Ar gas and the CH ₄ gas.

As shown in FIG. 5, when the self-bias generated on the substrate 13 is 0 V, the coating hardness is as low as about 500 Hv, and when the self-bias is 0 V to -20 V, the voltage increases to a negative value. As the film thickness increases, the self-bias has a high value of about 3000 Hv when the self-bias is -20 V, and when the self-bias is -20 V or less, there is almost no change, and the value is about 3000 Hv. Therefore, regardless of the supply partial pressures of the Ar gas and the CH ₄ gas, the RF voltage of the high-frequency power supply 10 is set so that the self-bias generated in the substrate 13 is −20 V or less. It can be seen that a diamond-like coating having a high hardness of 3000 Hv is formed.

[0027]

As described above, according to the present invention, the ECR
In a method for forming a diamond-like film on a substrate surface by supplying a CH ₄ gas into a plasma flow of Ar gas using a plasma CVD apparatus, the self-bias generated on the substrate is controlled to control the substrate surface. It is possible to form a diamond-like coating having high hardness.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an apparatus for forming a diamond-like film as one embodiment of the present invention.

FIG. 2 is a plan view of a reaction gas introduction pipe.

FIG. 3 is a diagram showing a relationship between a film formation time and a substrate temperature when a diamond-like film is formed on the surface of a substrate.

FIG. 4 is a diagram showing a change in coating hardness with respect to a supply partial pressure of Ar gas when the apparatus of FIG. 1 is used.

FIG. 5 is a diagram showing a change in film hardness with respect to an RF voltage applied to a substrate holder 12 when the apparatus of FIG. 1 is used.

FIG. 6 is a schematic sectional view showing a conventional ECR plasma CVD apparatus.

[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 7,13 Substrate 8 Vacuum chamber 9,16 Reaction gas introduction pipe 10 High frequency power supply 11 Substrate holder 12 Cylindrical substrate Holder 14 Cylindrical shield cover 15 Opening

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/31 H01L 21/31 C (72) Inventor Seiichi Kiyama 2-18 Keihanhondori, Moriguchi-shi, Osaka SANYO Electric Co., Ltd. In-company (56) References JP-A-4-329879 (JP, A) JP-A-4-139089 (JP, A) JP-A-653635 (JP, U) (58) Fields investigated (Int. . ^6, DB name) C23C 16/00 - 16/56 C01B 31/02 C30B 29/04 H01L 21/205 H01L 21/31

Claims (2)

(57) [Claims] An Ar gas is supplied to a plasma generation chamber, and a microwave is introduced to generate Ar plasma by electron cyclotron resonance. The Ar plasma is emitted to a substrate disposed in a vacuum chamber, and the Ar plasma is simultaneously emitted. A predetermined high-frequency voltage is applied to the substrate, and C is introduced into the Ar plasma flow.
By supplying H ₄ gas, a diamond-like carbon film forming method for forming a diamond-like coating on the substrate, the self-bias occurring in the substrate is to apply the high frequency voltage to be equal to or less than -20V both On the substrate
A method for forming a diamond-like film, wherein plasma irradiation is performed intermittently . 2. A method for forming a diamond-like coating on the substrate by setting the supply partial pressure of the Ar gas and the supply partial pressure of the CH ₄ gas to 1.0 × 10 −4 Torr or more and 20.0 × 10 −4 Torr or less. The method for forming a diamond-like film according to claim 1, wherein: