JP2001152338A - Manufacturing apparatus for diamond-like high conductivity carbon(dlc) thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus to form a DLC thin film high in hardness, excellent in flatness of the surface of the thin film, and high in conductivity by an RF-PECVD method. SOLUTION: In the apparatus for manufacturing the DLC thin film by applying the high frequency electric field to a raw material gas at a predetermined degree of vacuum introduced between a cathode electrode 6 by which a substrate 15 is held and an anode electrode 2 opposite thereto, and depositing carbon on the substrate, a means to control the temperature of the peripheral atmosphere of the plasma 8 generated between the electrodes comprises a cylindrical anode chamber 1 having a jacket of the size that the anode electrode 2 provided with a gas feeder 30 is stored, and the plasma 8 generated between the electrodes is housed and with the cathode electrode 6 side open, a heater 4 wound around the anode chamber 1, an in-jacket cooling pipe 3 of the anode chamber 1, and a temperature sensor 5 to measure the wall temperature of the anode chamber 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for producing a diamond-like carbon (hereinafter, simply referred to as DLC) thin film.
F-PECVD (Radio Frequency Plasma Enhanced Ch)
The present invention relates to an apparatus for producing a DLC thin film having high conductivity by using an emical vapor deposition (high frequency plasma CVD) method.

[0002]

2. Description of the Related Art Conventionally, dies, cutting tools, sliding members,
A DLC thin film is used as a magnetic head surface protective film or a magnetic tape surface protective film. DL like this
One of the techniques for manufacturing a C thin film is RF-PECVD, in which a high-frequency electric field is applied while introducing a raw material at a predetermined degree of vacuum between a cathode electrode holding a substrate and an anode electrode opposed thereto. A DLC thin film is formed by generating plasma and depositing carbon on the substrate. FIG. 1 shows a typical RF-PECVD conventionally used.
It is the schematic of an apparatus.

In the figure, reference numeral 1 'denotes a vacuum chamber for keeping the inside at a predetermined pressure, 2' an anode electrode installed in the vacuum chamber 1 and grounded, and 3 'for introducing a raw material gas into the vacuum chamber 1'. The reaction gas inlets 4 'are cathode electrodes connected to a high frequency power supply 6' (frequency is generally 13.56 MHz) via a matching box 5 '. The operation of the vacuum chamber 1 'will be described. The internal pressure of the vacuum chamber 1' is increased from about 5 mTorr to 100 mTorr, and the opening of the gate valve 7 'and the flow meter (MFC: MassFlow C
ontroller) 8 'controls the gas flow rate.

If the pressure in the vacuum chamber 1 'is less than 5 mTorr, sputtering may occur.
The film is formed under the aforementioned pressure. A high-frequency power supply 6 ′ is connected between the anode electrode 2 ′ and the cathode electrode 4 ′.
A high frequency of 13.56 MHz is applied through a matching box 5 'for high frequency impedance matching, and the source gas is dissociated into chemically active ionized ions and atoms or molecules during this period. Here, when the carbon reaches the base material 9 ′ held on the cathode 4 ′, D
An LC thin film is deposited.

[0005] The RF-PECVD method can form a DLC thin film over a wide area of a substrate, and can form a DL under a low temperature environment.
There is an advantage that a C thin film can be formed on a substrate. However, the above-mentioned conventional RF-PECVD apparatus for forming a DLC thin film can only obtain a DLC thin film having a low conductivity, and the DLC thin film inherently has a high resistance. There is a problem that the film quality is degraded by the resulting discharge, and there is a limit in applying the obtained DLC thin film as a conductive hard protective film. The high-conductivity DLC thin film has already been realized by the arc method or the sputtering method, but the DLC thin film obtained by both methods has poor film quality such as surface flatness.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made in view of the problem of RF-RF.
An object of the present invention is to establish a technique capable of forming a DLC thin film having high hardness, good flatness of the thin film surface, and high conductivity by the PECVD method.

[0007]

As a result of repeated studies, the present inventor has found that, when a DLC thin film or the like is manufactured by the RF-PECVD method, means for keeping the temperature of the reaction atmosphere as constant as possible is provided. Makes it easier to control operating factors such as self-bias voltage, and provides high conductivity (low resistance)
Can be formed.

Thus, according to the present invention, as a basic invention, a high-frequency electric field is applied to a raw material gas introduced at a predetermined degree of vacuum between a cathode electrode holding a base material and an anode electrode facing the cathode electrode. An apparatus for producing a DLC thin film by depositing carbon on a substrate by generating a plasma, wherein means for controlling the temperature of the atmosphere around the plasma generated between the electrodes is provided. D
An apparatus for manufacturing an LC thin film is provided.

In a preferred embodiment of the apparatus for manufacturing a DLC thin film according to the present invention, the means for controlling the temperature of the atmosphere around the plasma contains an anode electrode provided with a gas supply device and wraps the plasma generated between the electrodes. A cylindrical anode chamber with a jacket having a size and an open cathode electrode side, a heater wound around the anode chamber, cooling water flowing in a jacket of the anode chamber, and a wall temperature of the anode chamber. Consists of a temperature sensor to measure.

Further, the apparatus for producing a DLC thin film of the present invention
In a preferred embodiment, the distance between the anode electrode and the cathode electrode can be changed. In a particularly preferred embodiment, the means for controlling the temperature of the atmosphere around the plasma as described above is movable in the vertical direction. This allows the distance between the anode electrode and the cathode electrode to be changed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Although it is extremely difficult to measure and control the temperature of the plasma itself as generated in the RF-PECVD method, the present invention cools and / or heats the periphery of the plasma generation region. By controlling the temperature, the RF-PECVD method can be stably performed, and a highly conductive DLC thin film can be manufactured with good reproducibility.

Further, the present invention relates to a conventional RF-PECV
As in the method D, a sheath generated near the cathode is used as bias (self-biasing) means, and high frequency power applied to the cathode is not only changed as bias voltage control means but also generated near the cathode as bias means. It is also added that the spacing between the anode electrode and the cathode electrode can be changed as a bias voltage control means using a sheath.

When the distance between the anode electrode and the cathode electrode is changed as described above, the bias voltage (self-bias voltage) can be controlled, and as a result, the temperature of the plasma and its surrounding atmosphere can be easily controlled. The RF-PECVD method can be stably performed at a temperature of, and a DLC thin film having high conductivity can be obtained.

The means for controlling the temperature of the surrounding atmosphere of the plasma generated between the anode electrode and the cathode electrode used in the apparatus for manufacturing a DLC thin film of the present invention is not particularly limited. It suffices if it is possible to measure the temperature of the peripheral portion of the device and to heat and / or cool it. In the DLC thin film manufacturing apparatus of the present invention, the means for changing the distance between the anode electrode and the cathode electrode is also not particularly limited, and one or both of the anode electrode and the cathode electrode are mechanically moved. It suffices if the distance between them changes.

Hereinafter, the present invention will be described with reference to the preferred embodiments of the present invention shown in the drawings. FIG. 2 is a schematic view of a preferred example of the high conductivity DLC thin film forming apparatus of the present invention. 1
0 is a vacuum chamber for evacuating the inside, 12 is an exhaust pump for evacuating the vacuum chamber 10, and 15 is a D pump on the surface.
The base material such as glass on which the LC thin film is formed is held by the cathode electrode 6.

Reference numeral 1 denotes a cylindrical anode chamber having a jacket, and this anode chamber houses an anode electrode provided with a gas supply device 30. Then, as shown in the figure, the anode chamber 1 has a plasma 8 generated between the electrodes.
And has a size (inner volume) that encloses the, and its cathode side is open. A heater (for example, a nichrome wire) 4 is wound around the anode chamber 1, a cooling water pipe 3 is provided in the jacket to allow cooling water to flow, and a temperature sensor for measuring the wall temperature of the anode chamber 1 (For example, a thermocouple) is attached, and the cylindrical anode chamber 1, the heater 4, the cooling water pipe 3, and the temperature sensor 5 constitute a means for controlling the temperature of the atmosphere around the plasma.

In a particularly preferred embodiment of the apparatus for producing a DLC thin film of the present invention, as described above, the plasma surrounding atmosphere comprising the anode chamber 1, the anode electrode 2 having the gas supply device 30, the heater 4, the cooling water pipe 3, and the temperature sensor 5 is provided. The temperature control means is movable in the vertical direction (up and down direction) as a whole, whereby the anode electrode 2 and the cathode electrode 6 (therefore, the base material 1 held by the
5) becomes variable, and the bias voltage (self-bias voltage) applied to the base material or the cathode electrode can be changed.

FIG. 6 shows an example of a movable device of such a plasma peripheral atmosphere temperature control means. In the drawing, reference numeral 31 denotes a lifting column fixed to the anode chamber 1 and the anode electrode 2, which accommodates a part of the gas supply device 30. A rack is screwed on the support 31, and the rack meshes with a pinion screwed on the handle 32. Thus, by rotating the handle 32, the column 31 is moved up and down, and accordingly, the plasma ambient atmosphere temperature control means including the anode chamber 1, the anode electrode 2, the heater 4, the cooling water pipe 3, and the temperature sensor 5 is vertically moved as a whole. Direction (up and down direction). The mechanism for operating the ambient temperature control means around the plasma includes:
The mechanism is not limited to the rack-pinion mechanism as described above, and any other mechanism, such as a cam mechanism or a slider crank mechanism, may be used as long as the rotation of the handle 32 can be changed to the linear movement (elevation movement) of the column 31. It is also possible.

The heater 4 is connected to an anode temperature controller 9 installed outside the vacuum chamber 10 so that the heating output is adjusted. A gas supply device 30 connected to the anode electrode 2 is connected to a gas flow control device (MFC) 17 installed outside the vacuum chamber 10 to supply various source gases (reaction gases), for example, a mixed gas such as methane and nitrogen. It can be supplied. Further, a cooling water pipe 3 provided in the jacket of the anode chamber 1
Is flowing water so as to be lower than the desired anode electrode temperature when the heater 4 is not operating,
Thereby, the temperature setting of the anode electrode 2 becomes easy,
The temperature of the atmosphere around the plasma generated between the electrodes can also be quickly controlled.

On the other hand, the cathode electrode 6 is water-cooled by a cathode cooling water pipe 11 and its outer periphery is covered with a cathode shield 7 for suppressing excess plasma. Reference numeral 13 denotes a matching box for the purpose of impedance matching between a cathode electrode, which tends to have a relatively low impedance, and a high-frequency power supply having a normal output impedance of 50Ω. Reference numeral 14 denotes a high-frequency power source whose frequency is generally 13.56 MHz.
z. Reference numeral 23 denotes a DC voltmeter for measuring a cathode bias voltage, which cuts high frequency components by a filter circuit (not shown).

In manufacturing a DLC thin film by operating the DLC thin film manufacturing apparatus configured as described above, first,
After the inside of the vacuum chamber 10 is evacuated to a predetermined degree of vacuum (for example, about 1 × 10 ⁻⁶ Torr) by the exhaust system 12,
Main gas, for example, methane gas (C
H ₄ ) is adjusted to a predetermined flow rate (for example, 1
(Approximately 00 sccm). Thereafter, the opening degree of the gate valve 16 connected to the exhaust system 12 is adjusted so that the pressure in the vacuum chamber 10 is set to several mTorr to 10 mTorr. Subsequently, if necessary, the methane gas opening / closing valve 20
The pressure in the vacuum chamber 10 is adjusted to several mTorr to 10 mTorr by adjusting the MFC 18 with a doping gas, for example, a nitrogen gas as shown in FIG. Thereafter, the methane gas opening / closing valve 20 is opened. By this operation, the methane gas and the nitrogen gas are mixed at a fixed ratio, and are supplied from the gas supply device 1 into the vacuum chamber 10. At this time, if necessary, a diluting gas such as argon (Ar) may be mixed. A preferred example of the main gas for generating DLC is methane, but is not limited to this, and other gas composed of carbon atoms and hydrogen atoms (for example, acetylene)
Can be used as well.

After a predetermined gas is introduced into the vacuum chamber 10 and a predetermined degree of vacuum is secured, a high frequency power of 13.56 MHz is supplied from a high frequency power source. As a result,
A high-frequency electric field is induced between the anode electrode 2 and the cathode electrode 6 to generate a high-frequency glow discharge, and a weakly ionized non-equilibrium plasma 8 is generated. The electrons accelerated by the high-frequency electric field dissociate, excite, and ionize gas components. ing. For example, when methane is used, the dissociation reaction by electron collision CH ₄ + e → C + 2H ₂ and CH ₄ + e → CH + H ₂ + in plasma.
H, CH ₄ + e → CH ₂ + 2H, CH ₄ + e → CH ₃ +
H is thought to be occurring, C, CH, C
H ₂ and CH ₃ are chemically active, and these active species reach the base material 15 held on the cathode electrode 6 to form a DL.
A C film grows. Since a cathode sheath is formed between the plasma 8 and the cathode electrode 6 and the anode electrode 2 is grounded, the cathode electrode 6 is negatively self-biased.

In the production of a thin film such as DLC to which the present invention is directed, a high-frequency electric field is applied to a cathode electrode holding a substrate for the purpose of positively utilizing the ion bombardment due to the self-bias of plasma. Thus, a large-area film can be formed. Then, a cathode shield 7 is arranged so as to cover the cathode electrode 6, and the gap with the cathode electrode is maintained at a short distance of 1 mm to 2 mm and grounded. When high-frequency power is applied to the cathode electrode 6, a high-frequency electric field exists between the cathode electrode 6 and the cathode shield 7, which causes ionization of the mixed gas. However, since the distance between them is short, sufficient energy cannot be given to electrons or charged particles, and D
Plasma unnecessary for LC deposition is not generated, and the shield is secured.

DLC of RF-PECVD method as described above
When the thin-film device is operated, the raw material gas is ionized by high-frequency power and ionized to form plasma, and a part thereof is dissociated into chemically active excited atoms or molecules. Here, it is known that the constituent ratio of the ionized charged particles, excited atoms and excited molecules which affect various properties of the finally obtained DLC thin film is closely related to the plasma temperature. Further, the self-bias voltage of the cathode electrode is closely related to the energy applied to the ions. Thus, the plasma temperature and the self-bias voltage of the cathode
It is considered to be an important factor affecting the quality of the thin film.
In the conventional RF-PECVD method, these are not actively controlled.

For example, although cooling of the cathode electrode has been carried out, no attempt has been made to control the temperature of the plasma in the reaction zone. As a means, a sheath generated near the cathode is used, and only a high-frequency power applied to the cathode is changed as a means for controlling a bias voltage. That is, in the conventional RF-PECVD apparatus, since a film is formed while setting operating conditions on a random basis, a high-quality DLC thin film cannot be obtained with good reproducibility, and in particular, high conductivity (low resistance) A DLC thin film was not obtained, and it was not suitable for industrial equipment.

On the other hand, if the DLC thin film apparatus of the present invention, which has means for controlling the peripheral temperature of the plasma and can change the distance between the anode and the cathode, is used, the temperature of the plasma can be reduced as much as possible. By keeping constant
The RF-CVD method can be performed while reliably changing the operating conditions such as the self-bias voltage over a wide range. As a result, a high-conductivity (low-resistance) DLC thin film not found in the conventional RF-CVD method is obtained. Can be obtained.

For example, FIG. 3 shows that the size of the electrodes (anode electrode and cathode electrode) is 125 mm in diameter and the inside diameter of the anode chamber is 200 mm, and as shown in FIG. Using the movable DLC thin film manufacturing apparatus of the present invention, the degree of vacuum is 10 mTorr.
r, under the condition of a high-frequency electric field (13.56 MHz) output of 200 W, the temperature of the atmosphere around the plasma was reduced to about 10 from a raw material gas (nitrogen fraction: 0.3) composed of methane and nitrogen.
The relationship between the self-bias and the resistivity of the DLC thin film in an experiment conducted by changing the self-bias voltage of the cathode electrode by changing the interval between the anode electrode and the cathode electrode to 10 mm to 20 mm while maintaining 0 ° C. It was done. As shown in the figure, the resistivity is clearly lower at a specific voltage, and a DLC thin film having a very low resistivity can be obtained by using the apparatus of the present invention.

FIG. 4 shows the same operation as above, but shows the relationship between the nitrogen fraction and the resistivity of the DLC thin film when the DLC thin film was formed while maintaining the cathode self-bias voltage at -1100 V. Show. By controlling the ambient temperature of the plasma using the apparatus of the present invention, it is possible to manufacture a DLC thin film by RF-PECVD by changing the nitrogen fraction over a wide range which has not been possible in the past. A DLC thin film of conductivity (low resistivity) is obtained.

FIG. 5 shows an example of a Raman spectrum of the DLC thin film obtained as described above, measured by a Raman spectrophotometer. G near 1574 cm ^-1
The peak, a D peak near 1380 cm ⁻¹ , shows a pattern unique to DLC, and it can be confirmed that a DLC thin film is formed.

According to the present invention, the resistivity is 10 (oh)
m-cm) or less, and a DLC thin film having an extremely high conductivity of about 0.1 (ohm-cm) can be obtained. Table 1 shows DLC by RF-RECVD using nitrogen as doping gas.
The following is an example of a report on the production of a thin film. DL of the present invention
It is understood that the use of the C thin film device can provide a DLC thin film having extremely high conductivity.

[0031]

[Table 1]

[0032]

As described above, the apparatus for manufacturing a DLC thin film according to the present invention comprises the means for controlling the temperature around the plasma and the means for controlling the self-bias of the cathode electrode, thereby facilitating the generation of charged particles, excited atoms and excited molecules. Therefore, there is an effect that a high-conductivity DLC thin film can be easily formed. Thus, according to the present invention, a new type of DLC which is excellent in surface flatness by RF-PECVD and has a low resistivity of about 0.1 (ohm-cm), and is useful for various uses.
A thin film is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a typical example of a conventional DLC thin film manufacturing apparatus.

FIG. 2 is a sectional view of a preferred example of a DLC thin film manufacturing apparatus of the present invention.

FIG. 3 is a graph showing a relationship between a cathode electrode bias voltage and a resistivity of a DLC thin film when a DLC thin film is formed using the apparatus of the present invention.

FIG. 4 is a graph showing the relationship between the nitrogen fraction and the resistivity of a DLC thin film when a DLC thin film is formed using the apparatus of the present invention.

FIG. 5 is an example of a Raman spectrum of a DLC thin film obtained according to the present invention.

FIG. 6 is a cross-sectional view showing one example of a movable device of the plasma ambient atmosphere temperature control means of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode chamber 2 Anode electrode 3 Cooling water pipe 4 Heater 5 Temperature sensor 6 Cathode electrode 8 Plasma 10 Vacuum chamber 15 Substrate 30 Gas supply device

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoichi Iseri 144-1, Omiya Kawamiya, Fagawa, Fukuoka F-term (reference) 4K030 AA09 AA10 AA18 BA28 FA03 JA03 KA14 KA20 KA23 KA25 KA26 KA30 KA39 KA41

Claims (4)

[Claims] 1. A high-frequency electric field is applied to a raw material gas introduced at a predetermined degree of vacuum between a cathode electrode holding a base material and an anode electrode facing the cathode electrode to generate plasma and carbon on the base material. An apparatus for manufacturing a DLC thin film by depositing, comprising means for controlling a temperature of an atmosphere around a plasma generated between the electrodes, the apparatus being provided with a DLC thin film. 2. A jacket, wherein said means for controlling the temperature of the ambient atmosphere of said plasma accommodates an anode electrode provided with a gas supply device and is sized to wrap the plasma generated between the electrodes, and has a cathode electrode side opened. A cylindrical anode chamber, a heater wound around the anode chamber, cooling water flowing in a jacket of the anode chamber, and a temperature sensor for measuring a wall temperature of the anode chamber. Item 1. A DLC thin film manufacturing apparatus according to Item 1. 3. The apparatus according to claim 1, wherein the distance between the anode electrode and the cathode electrode can be changed.
Or the DLC thin film manufacturing apparatus according to claim 2. 4. The apparatus according to claim 1, wherein the means for controlling the temperature of the atmosphere surrounding the plasma is vertically movable, so that the distance between the anode electrode and the cathode electrode can be changed. Item 3. A DLC thin film manufacturing apparatus according to Item 3.