JP3006190B2 - Vacuum deposition method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a vacuum film forming method,
The present invention relates to a vacuum film forming method including a cleaning unit for performing a cleaning process on a substrate film forming surface.

[0002]

2. Description of the Related Art Techniques for forming a thin film on a substrate include an ion beam sputtering method, a sputtering method, an ion plating method, and a plasma CVD method. In addition, the ECR plasma CVD method is also practically used.

[0003] For example, a vacuum film forming apparatus using the ECR plasma CVD method includes a plasma chamber for generating plasma by microwave introduction, a magnetic circuit disposed around the plasma chamber, and a substrate on which a film is to be formed. And a film forming chamber to be formed. Such ECR plasma CVD
The apparatus is used for forming a diamond-like carbon film as a protective film for a magnetic disk, a magnetic head, an optical component, and the like.

[0004] During the film forming process by the ECR plasma CVD apparatus, a predetermined magnetic field is formed in the plasma chamber and a microwave is introduced into the plasma chamber. Then, in the plasma chamber, the frequency of the electron and the frequency of the microwave coincide, causing electron cyclotron resonance,
High-density plasma is generated. This plasma is drawn out along the diverging magnetic field and irradiated onto the substrate to perform a film forming process.

On the other hand, before the film forming process, a cleaning process of the substrate film forming surface may be performed for the purpose of improving the film adhesion to the substrate. For example, in the ECR plasma CVD apparatus, an argon gas as a cleaning gas is introduced into a plasma chamber to generate electron cyclotron resonance plasma of argon in the plasma chamber. By irradiating the substrate with the plasma flow, a cleaning process of the substrate deposition surface is performed. After the cleaning process, the argon gas is evacuated to a vacuum, and after the evacuation process, a film forming gas is introduced into the film forming chamber to cause electron cyclotron resonance in the same manner, thereby performing the film forming process.

However, in the conventional film forming process, the substrate is inactivated by the residual gas and the like and the introduced film forming gas during the evacuation of the argon gas, and as a result, There is a problem that the film adhesion to the substrate deposition surface is reduced.

An object of the present invention is to provide a vacuum film forming method capable of improving the film adhesion to a film forming surface of a substrate.

[0008]

According to the present invention, a plasma is generated by a plasma generating means in a vacuum chamber in which a substrate to be formed is disposed, and a cleaning gas ionized by the plasma is applied to the film forming surface of the substrate. After performing the cleaning process by irradiating, the film formation gas is introduced into the vacuum chamber, and the film formation surface is irradiated with the ionized film formation gas to perform the film formation process. In the film method, by stopping the supply of the cleaning gas into the vacuum chamber in a state where the plasma is continuously generated and simultaneously starting the supply of the film forming gas, the cleaning process and the film forming process are performed. It is characterized in that ions are continuously applied to the film formation surface of the substrate.

[0009]

According to the vacuum film forming method of the present invention, first, the film forming surface of the substrate is cleaned by using the ionized cleaning gas, and then the film forming surface of the substrate is formed by using the ionized film forming gas. Next, a film forming process is performed. Then, during the period from the cleaning process to the film forming process, the cleaning process is continuously shifted to the film forming process while continuously irradiating the film-forming surface of the substrate with ions.

In this case, ion irradiation is continuously performed on the substrate deposition surface from the cleaning process to the film forming process. This makes it difficult for the substrate to be inactivated,
The ions contributing to the film formation are implanted on the substrate film formation surface, and a layer having a strong adhesive force is formed.

[0011]

FIG. 1 shows an ECR plasma CVD apparatus as one embodiment of the present invention. In FIG. 1, a plasma chamber 1 contains an introduced microwave (frequency 2.45 GHz).
It is configured to be a cavity resonator for z).
The plasma chamber 1 is connected to a line 2 for introducing a gas for cleaning a substrate, for example, an argon (Ar) gas into the plasma chamber 1. Line 2 has a valve V
1, V2 and a mass flow controller (MFC) 1 are connected. Further, a waveguide 4 for microwave introduction is connected to the plasma chamber 1 via a microwave introduction window 3 made of quartz or the like. An electromagnetic coil 5 as a magnetic circuit for generating plasma is provided around the plasma chamber 1.
a, 5b are provided. These electromagnetic coils 5a,
By 5b, a diverging magnetic field diverging downward is formed.

Below the plasma chamber 1, a film forming chamber 6 is provided. In the film forming chamber 6, a substrate holder 8 for holding a substrate 7 on which a film is to be formed is arranged. The substrate holder 8 is supported by a support rod 9 connected to its lower part. The support rod 9 is a high-frequency power source 10 (frequency 13.56).
MHz). A shutter 11 is disposed above the substrate holder 8. The shutter 11 is openable and closable. The film forming chamber 6 is connected to a line 15 for introducing a film forming gas, for example, an ethylene (C ₂ H ₄ ) gas into the film forming chamber 6. Lines 15 include valves V3 and V4 and a mass flow controller (M
FC) 2 is connected. An exhaust hole 6 a is formed in a lower part of the film forming chamber 6. A line 16 for evacuating the inside of the film forming chamber 6 is connected to the exhaust hole 6a. The line 16 has a valve 17 and a variable conductance valve 1
8 and the pump 19 are connected. The opening of the variable conductance valve 18 is adjusted according to the detection result of a pressure sensor (not shown) connected to the film forming chamber 6.

The above-described device has a controller including a microcomputer, and each unit is controlled by the controller.

Next, the operation of the present apparatus will be described. From the state where the substrate 7 to be formed is held by the substrate holder 8,
First, by driving the pump 19, the plasma chamber 1 and the film forming chamber 6 are evacuated to a high vacuum and the chamber pressure is reduced to 5 × 10 ⁻⁶ T.
orr or less. Next, the following operation will be described with reference to the control flowchart of the controller (FIG. 2).

In step S1 of FIG.
Close. Next, in step S2, the variable conductance valve 18 is turned on. Next, in step S3, it is determined whether a predetermined timer time set in advance has elapsed. If the predetermined time has elapsed, the process proceeds to step S4. In step S4, the electromagnetic coils 5a and 5b are energized to turn on the electromagnetic coils 5a and 5b, and the plasma chamber 1
Is 875 gauss.

Next, at step S5, the valves V1, V
2 is opened, and argon gas for cleaning is introduced into the plasma chamber 1. At this time, the flow rate of the argon gas is M
Set by FC1. Next, in step S6, it is determined whether or not a predetermined timer time set in advance has elapsed. At this time, the pressure in the film forming chamber 6 is maintained at a predetermined pressure by the variable conductance valve 18. Next, in step S7, the microwave is turned ON, that is, a microwave having a frequency of 2.45 GHz is introduced from the waveguide 4 into the plasma chamber 1.

Then, in the plasma chamber 1, 875
The frequency of the electron rotating by the Gaussian magnetic field coincides with the microwave frequency of 2.45 GHz, and electron cyclotron resonance occurs. As a result, the electrons efficiently absorb energy from the microwave, and a high-density plasma is generated under a low gas pressure. This plasma is generated by the electromagnetic coil 5
a, 5b are drawn along the lines of magnetic force of the divergent magnetic field formed by the divergent magnetic field.

Next, in step S8, it is determined whether or not a predetermined timer time has elapsed. When the predetermined time has elapsed, the process proceeds to step S9. Step S
At 9, the shutter 11 is opened. Next, in step S10,
The high frequency (RF) power supply 10 is turned on, and a high frequency voltage of 13.56 MHz is applied to the substrate 7 via the support rod 9 and the substrate holder 8.

As a result, the substrate 7 is irradiated with the plasma flow drawn out of the plasma chamber 1 along the lines of magnetic force of the diverging magnetic field generated by the electromagnetic coils 5a and 5b. As a result, the substrate deposition surface 7a is cleaned by the argon plasma.

During the cleaning process, the flow rate of the argon (Ar) gas is kept constant as shown in FIG. 3 (see the straight line AB in FIG. 3).

Next, in step S11, it is determined whether or not a predetermined cleaning time (time T1 in FIG. 3) set in advance has ended. When the cleaning time has expired, the flow shifts to step S12. In step S12, the valve V1 is closed and the valves V3 and V4 are opened to start introduction of a film forming gas, for example, ethylene gas into the film forming chamber 6. At this time, the flow rate of the introduced ethylene gas is gradually increased by the MFC 2 (see the dotted line DC in FIG. 3). Next, in step S13, it is determined whether a predetermined timer time (time T2-T1 in FIG. 3) has elapsed. Note that this timer time is set to an extremely short time. If a predetermined timer time elapses, step Sl4
Move to In step S14, the valve V2 is closed, and the flow rate of the MFC2 is fixed (see point C in FIG. 3). Thus, the flow rate of ethylene (C ₂ H ₄ ) gas is as shown in FIG.
Is maintained constant as indicated by the dotted line CE, and the Ar gas flow rate gradually decreases as indicated by the CF line in FIG. That is, in FIG. 3, during the time T1 to T3, the Ar gas and the C ₂ H ₄ gas are mixed.

On the other hand, a microwave having a frequency of 2.45 GHz is continuously introduced into the plasma chamber 1 from the waveguide 4, and the electromagnetic coils 5a and 5b and the high-frequency power source 10 are in an ON state. Therefore, in the plasma chamber 1, the frequency of the electrons rotating by the magnetic field of 875 gauss matches the frequency of the microwave of 2.45 GHz, and the electron cyclotron resonance is continuously generated. Thereby, high-density plasma is generated. The plasma is extracted by magnetic lines of diverging magnetic field formed by the electromagnetic coils 5a and 5b, and irradiates the substrate 7. Thus, a carbon film is formed on the film formation surface 7a of the substrate 7.

In this case, since discharge is continuously generated from the cleaning process to the film forming process, the substrate is always irradiated with ions on the film forming surface. As a result, inactivation of the substrate hardly occurs, and ions contributing to the film formation are implanted into the substrate film formation surface, and a layer having a strong adhesive force is formed.

Next, in step S15, it is determined whether a predetermined film forming time (time T4-T2 in FIG. 3) has ended. When the film formation time has ended, the flow shifts to step S16.
In step S16, the shutter 11 is closed. Next, in step S17, the supply of the voltage from the high-frequency power supply 10 and the introduction of the microwave are stopped. Next, in step S18, it is determined whether a predetermined timer time has elapsed. If the predetermined timer time has elapsed, the process moves to step S19.
In step Sl9, the valves V3 and V4 are closed, and the supply of ethylene gas is stopped. Next, in step S20, the variable conductance valve 18 is fully opened. Next, in step S21, the inside of the film formation chamber 6 is evacuated to a high vacuum by the pump 19. In this way, a series of film forming processing ends.

Experimental Example Experimental conditions: Argon gas introduction amount 100 SCCM Deposition chamber pressure 4 × 10 ⁻³ Torr Plasma chamber magnetic flux density 875 G Microwave power 200 W (constant) Substrate self-bias voltage −400 V (constant) Substrate size 50 × 50 SUS316 Cleaning time 2 minutes Film formation time 50 minutes As a result of the above experiment, a diamond-like carbon film of about 5500 Å was formed on the entire surface of the substrate. The peeling load of this film was 11gf.

Comparative Example Experimental conditions: Argon gas introduction amount, film forming chamber pressure, magnetic flux density in plasma chamber, microwave power, self-bias voltage of substrate,
The cleaning time and the substrate to be used are the same as those in the experimental example. This comparative example is different from the previous embodiment in that after cleaning is completed, the high-frequency voltage, the microwave and the electromagnetic coil are turned off, the valves V1 and V2 are closed, and the argon gas is evacuated to a high vacuum (FIG. 4). reference). After high vacuum evacuation of argon gas, valve V
3 and V4 are opened, and ethylene gas is
SCCM is introduced (reaction pressure: 4 × 10 ⁻³ Torr). Thereafter, the electromagnetic coils 5a and 5b, the high-frequency power source 10 and the microwave were turned on, and a film forming process was performed for 50 minutes. Accordingly, as shown in FIG. 4, the discharge is stopped during the time t1 to t2.

When the substrate after the film forming process was taken out of the film forming chamber 6 and left in the atmosphere, the film peeling started.

In this embodiment, the cleaning process and the film formation process are performed in a state where plasma is constantly generated in the plasma chamber 1 and an RF bias voltage is applied to the substrate 7.
As a result, a layer having a low adhesive force is removed from the film formation surface 7a without inactivation of the substrate surface due to residual gas or the like in the film formation chamber 6. As a result, as shown in the experimental example, a thin film having a strong adhesive force is formed.

[Other Embodiments] In the above embodiment, a case where a diamond-like carbon film is formed using an ECR plasma CVD apparatus is taken as an example. However, the present invention is not limited to this. The same applies to formation.

[0030]

According to the vacuum film forming method of the present invention, since the substrate is irradiated with ions continuously from the cleaning process to the film forming process, the substrate is hardly deactivated. The ions contributing to the film formation are implanted into the substrate film formation surface, and a layer having a strong adhesive force is formed, so that the film adhesion force to the substrate film formation surface can be improved.

[Brief description of the drawings]

FIG. 1 shows an ECR plasma CV as one embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a D device.

FIG. 2 is a flowchart showing a part of a control flow by a controller of the apparatus of the embodiment.

FIG. 3 is a diagram for explaining the operation of the embodiment.

FIG. 4 is a diagram for explaining an operation of a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma chamber 2 Argon gas introduction line 4 Waveguide 5a, 5b Electromagnetic coil 6 Film formation chamber 7 Substrate 7a Film formation surface 10 High-frequency power supply 15 Film formation gas introduction line

Claims (1)

(57) [Claims] A cleaning process is performed by generating plasma in a vacuum chamber in which a substrate on which a film is to be formed is placed by a plasma generating means, and irradiating a cleaning gas ionized by the plasma to the film formation surface of the substrate. After performing, a film-forming gas is introduced into the vacuum chamber, and the ionized film-forming gas is irradiated on the substrate film-forming surface,
In the vacuum film forming method for performing the film forming process, the supply of the film forming gas is started simultaneously with stopping the supply of the gas for cleaning into the vacuum chamber in a state where the plasma is continuously generated. And a step of continuously irradiating the film formation surface of the substrate with ions throughout the film formation process.