JPH02225671A - Hard carbon film manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a hard carbon film used as a protective film for, for example, a magnetic disk 5, a magnetic head, and an optical component.
Cyclotron Resonance (two-electron cyclotron resonance) relates to a technology for producing a hard carbon film by a plasma CVD method.

[Conventional technology]

A diamond-like film (a hard carbon film) is used as a protective film for magnetic disks, magnetic heads, and optical components.
(hereinafter referred to as DLCM) is used.

Conventional methods for manufacturing this DLC film include ion beam sputtering and ion blating.

and plasma CVD methods are used.

On the other hand, the ECR plasma CVD method has recently been developed as a type of plasma CVD method, and is already in practical use. This ECR plasma CVD method causes electron cyclotron resonance in an ECR ion source, thereby generating high-density plasma, and uses a diverging magnetic field to irradiate the plasma stream onto a sample such as a substrate to form a film. It is something to do.

[Invention tries to solve! III) Recently, using this ECR plasma CVD method, DLCJI
It is considered to generate I. However, using the ECR plasma CVD method, DI, CI! When attempting to produce 1, film formation conditions are very important.

In particular, it is greatly influenced by the power of the microwave introduced into the plasma chamber, the self-bias generated in the substrate, and the reaction pressure.

Among these conditions, the power of the microwave needs to be increased to a certain extent because it is necessary to decompose the reaction gas, but if it is increased too much, for example, when methane gas is used as the reaction gas, the methane gas may be decomposed too much. A large amount of H radicals are generated and taken into the film, making it impossible to form a DLC film.

Regarding the self-bias, it is necessary to increase the self-bias to some extent because it is necessary to increase the acceleration energy of ions, but if it is made too large, the film may become graphitized and become graphite-like.

Furthermore, the reaction pressure needs to be set to a certain level in order to promote the reaction; if it is too low, the same phenomenon as when the microwave power is too high will occur, making it difficult to form a DLC film. .

As described above, depending on the conditions (microwave power, self-bias, reaction pressure), a DLC film cannot be formed on the substrate, and a polymer film or a graphite film may be formed.

An object of the present invention is to provide a technique for stably manufacturing a hard carbon film such as a DLC film using the ECR plasma CVD method.

[Means to solve the problem]

The method for manufacturing a hard carbon film according to the present invention is a method for manufacturing a hard carbon film using the ECR plasma CVD method, in which the power of microwaves introduced into a plasma chamber is reduced to 2.
00W or less, and the self-bias generated in the substrate is 130W or less.
A high frequency voltage is applied to the substrate so that it is 0V or more and -100V or less, and the reaction pressure in the sample chamber is increased to 8X 10-'Tor.
r or more.

[Effect]

In the hard carbon film manufacturing method according to the present invention, plasma is generated in a plasma chamber by electron cyclotron resonance, and this plasma flow is irradiated onto a substrate.

At this time, the microwave power is 200W or less and the reaction pressure is 8X 10-'Torr or more, so
For example, when a hydrocarbon gas is used as the reaction gas, generation of a large amount of H radicals due to excessive decomposition of the hydrocarbon gas is prevented.

In addition, the self-bias generated in the board can be reduced by -300V or more.
Since a high frequency voltage is applied so that it is 100V or less,
Graphitization of the film is prevented.

〔Example〕

First, the ECR plasma CVD apparatus to which the present invention is applied will be explained with reference to the drawings.
In Figure 6, which is a cross-sectional configuration diagram of the plasma CVD apparatus,
l is the microwave to be introduced (frequency 2.45 GHz
) is a plasma chamber configured to be a cavity resonator. A waveguide 3 for introducing microwaves is inserted into the plasma chamber l through a microwave introduction window 2 made of quartz or the like.
is connected. Further, around the plasma chamber 1, an electromagnetic coil 4a54b is arranged as a magnetic circuit for generating plasma. The strength of the magnetic field by the electromagnetic coils 4a and 4b is determined so that the conditions for electron cyclotron resonance by microwaves are satisfied inside the plasma chamber 1. A diverging magnetic field that diverges downward is formed by the electromagnetic coils 4a and 4b.

A sample chamber 5 is provided below the plasma chamber 1 .

At the top of the sample chamber 5, an annular gas introduction pipe 6 is provided for introducing a hydrocarbon gas such as methane gas (CH4) as a reaction gas. A plurality of holes (not shown) are formed in the gas introduction pipe 6, and the reaction gas introduced from the outside is ejected from the plurality of holes. Below the gas introduction pipe 6, a holder 8 holds a substrate 7, which is irradiated with a plasma flow M drawn from the plasma chamber 1. A support shaft 9 is attached to the substrate holder 8 . This support shaft 9 can be raised and lowered by a moving mechanism 12 provided outside the device. Further, a high frequency power source (eg, frequency 13.degree. 56 MHz) 11 is connected to the substrate holder 8 via a mobile device trio, so that a predetermined high frequency voltage is applied to the substrate 7. Therefore, as the high frequency power source 11, one whose voltage can be changed is used.

Note that the substrate holder 8 is equipped with a jacket (not shown) through which cooling water circulates. In addition, the gas introduction pipe 6
A shutter (not shown) is provided between the substrate holder 8 and the substrate holder 8, so that the irradiation of the plasma flow M onto the substrate 7 can be restricted.

An exhaust hole 5a is formed in the lower part of the sample chamber 5, and this exhaust hole 5a is connected to an exhaust system (not shown). Further, the vacuum pressure and reaction pressure within the sample chamber 5 are measured by a vacuum gauge (not shown).

Next, while explaining the function of this device, we will explain the hard carbon film,
In particular, a method for manufacturing a DLC film will be explained.

First, the plasma heavy equipment and the sample chamber 5 are brought into a vacuum state using an exhaust system (not shown), and then a reaction gas (CH,) is introduced into the sample chamber 5 from the gas introduction pipe 6 . Then, the electromagnetic coils 4a and 4b provided around the plasma chamber 1 are energized so that the magnetic flux density within the plasma chamber 1 becomes 875 Gauss.

Next, microwaves with a frequency of 2.450)lz are introduced into the plasma chamber l via the waveguide 3. The power of this microwave is set to be 200W or less.

Under these conditions, in the plasma chamber 1, 8
The frequency of electrons rotated by a magnetic field of 75 Gauss matches the frequency of microwaves, 2.45 GH2, causing electron cyclotron resonance. Therefore, electrons efficiently absorb energy from microwaves, causing low gas pressure. high-density plasma is generated. At this time, since the power of the microwave is set to 200 W or less, excessive decomposition of the reaction gas is suppressed and generation of a large amount of H radicals is prevented. The plasma generated in the plasma chamber 1 is transferred to the electromagnetic coil 4a.
, 4b along the lines of magnetic force of the diverging magnetic field. At this time, if you open the ishatta (not shown),
The extracted plasma flow M is irradiated onto the substrate 7 in the sample chamber 5 .

At this time, since a high frequency voltage is applied to the substrate 7 via the moving mechanism 10, the voltage is periodically positive.

A negative potential is applied. On the other hand, in plasma, the mobility of ions due to the electric field is slower than that of electrons. Therefore, electrons follow the potential fluctuations during application of this high-frequency voltage, but ions cannot.

Therefore, the substrate 7 is irradiated with many electrons, and a negative self-bias is generated in the substrate. Regarding the negative self-bias generated in this substrate 7, -300V or more -
Adjust the high frequency power so that it is 100V or less. Due to this negative self-bias generated in the substrate 7, positive ions in the plasma are drawn in, and a film is formed on the substrate 7. Furthermore, by setting the self-bias within the above range, reactions between the film surface and the film are promoted, and the film formed on the substrate is prevented from becoming graphitized.

Also, during film formation, the reaction pressure in the sample chamber was 8×10
Introduce the reaction gas so as to maintain the temperature above -'Torr. Therefore, excessive decomposition of the reaction gas is suppressed, and generation of a large amount of H radicals is prevented.

Note that during film formation, the substrate holder 8 is raised and lowered by the movement mechanism 10 so that the film thickness distribution on the substrate 7 is made good.

Using the above-mentioned equipment, methane gas is pumped at 20 sccm (sta
ndard cubic per s+1nutes)
The microwave power was set to 200V, the self-bias generated on the substrate was set to -200V, and the reaction pressure was set to 2x.
The pressure was set at 10-'Torr. Furthermore, a silicon wafer with a diameter of 4 inches was used as the substrate.

After 50 minutes, a film with a thickness of about 1 μm was deposited on the entire surface of the substrate. 1
The hardness of 11 is Hz (Knoop altitude) ζ1500kg
/-1, the refractive index is 2.18, and the H/C atomic ratio is approximately 0.
It was 25. DL from other IR (infrared absorption) measurements
It was determined that it was CII (hard carbon l1l).

81 shadows Using the apparatus of Example 1, 8Qscc of methane gas was
Microwave power was 150W, substrate self-bias was -200cm, reaction pressure was 6X10-
'Torr. Further, as in Example 1, a silicon wafer with a diameter of 4 inches was used as the substrate.

After about 1 hour, a film of about 0.5 μm was deposited on the entire surface of the substrate.

The hardness of the film is 2,000 kg / the refractive index is 2.1.
, H/C atomic ratio was approximately 0.2. From these results and IR (infrared absorption) measurements, it was determined that it was a DLC film.

Next, the following comparative experiment was conducted using the same apparatus as in Example 1.2.

The power of the flaming microwave was 500WS, the self-bias of the substrate was 200V, and the reaction pressure was 2X10-'T.

It was set as rr. The hardness of the film produced at this time was measured using a microhardness meter DUH-50 manufactured by Shimadzu Corporation, and was found to be D) l-646. Based on these results and the presence or absence of scratches caused by sanding, it was determined that the produced film was not a DLC film.

Comparison 1 When the microwave power was set to 500W, the self-bias of the substrate was set to OV, and the reaction pressure was set to 2X10-'Torr,
The measured value of Comparative Example 1 using a hardness meter was a Da piece of 100, which was only about the same hardness as an aluminum film.

Stop comparison ■The power of the main microwave is 250W, the self-bias of the substrate is -300■, and the reaction pressure is 1X10-3T.

When I changed it to rr, it became DH-630. Based on these results and the presence or absence of scratches caused by sanding, it was determined that the produced film was not a DLC film.

In this example, a DLC film was manufactured using an ECR plasma CCD apparatus under predetermined conditions of microwave power, substrate self-bias, and sample chamber reaction pressure. Generation of a large amount of H radicals due to excessive decomposition of methane gas is suppressed, and as a result, it is possible to prevent a large amount of H radicals from entering the film and softening the film. Furthermore, the film does not turn into graphite, so that a DLC film can be stably produced.

Further, since the substrate holder can be raised, the film thickness distribution on the substrate can be made good.

[Other Examples]

(a) In the embodiment described above, the gas introduction tube 6 was provided in the sample chamber 5 to introduce the reaction gas into the sample chamber 5 side, but this may also be introduced into the plasma chamber 1 side.
Further, the frequency of the high frequency power source 11 is not limited to 13.56 M)12.

(3) The reactive gas is not limited to methane gas, but may be any other hydrocarbon gas as long as it can form a hard carbon film.

〔Effect of the invention〕

According to the hard carbon film manufacturing method according to the present invention, EC
Using R plasma CVD equipment, microwave power,
The self-bias of the substrate and the reaction pressure of the sample chamber were set to predetermined conditions to generate a hard carbon film.
A hard carbon film can be stably produced.

[Brief explanation of the drawing]

The drawing is a cross-sectional configuration diagram of a hard carbon film manufacturing apparatus to which the present invention is applied. ■...Plasma chamber, 3...Waveguide, 4a, 4b...
...Electromagnetic coil, 5...Sample chamber, 6...Reaction gas introduction tube, 7...Substrate, 8...Substrate holder 10...
- Moving mechanism, 11...high frequency power supply.

Claims (1)

[Claims] (1) Microwaves are introduced into the plasma chamber to generate plasma by electron cyclotron resonance, and a predetermined high-frequency voltage is applied to a substrate placed in the sample chamber to irradiate the substrate with ions in the plasma. A method for manufacturing a hard carbon film, the method comprising: forming a hard carbon film on the substrate using a microwave power of 20
0W or less, and the self-bias generated in the substrate is -3
The high frequency voltage is applied so that the voltage is 00 V or more and -100 V or less, and the reaction pressure in the sample chamber is set to 8 x 10^-^4T.
A method for manufacturing a hard carbon film that is more than orr.