JP2002184770A - Substrate processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively form a DLC film by increasing the frequency of a voltage applied to a substrate without using an expensive RF power supply. SOLUTION: Plasma in an ECR discharge chamber 20 is drawn into a film forming chamber 10, and a hydrocarbon gas is introduced into the chamber, and the gas is discharged and ionized. Substrate 4
1 is applied with a high-frequency waveform voltage generated by ringing a pulse voltage from a pulse power supply 31 of a voltage application device 30 in a ringing generation circuit 32, and charge-up by ions deposited on the surface of the substrate 41 is performed. A film is formed on the surface of the substrate 41 while being prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a substrate processing apparatus for performing an etching process and a film forming process on a substrate in plasma.

[0002]

2. Description of the Related Art A DLC film (carbon-based diamond-like thin film) can be formed by CVD if CnHm gas is introduced into plasma and ionized and deposited on the substrate surface.
If the energy is increased by introducing nFm gas, the substrate surface can be etched. The DLC film formed from this CnHm gas has excellent wear resistance, and is used as a surface protective layer of a magnetic disk or a magnetic head of a magnetic recording device.

When processing a substrate in plasma as described above, it is necessary to apply a bias voltage to the substrate. However, when the substrate is an insulator, or when an insulating layer is formed even if it is not an insulator substrate, it is necessary to apply a bias voltage to the substrate. Cannot apply DC. Therefore, in a CVD apparatus for forming an insulating film, a bias is conventionally applied by inducing an RF voltage to be dielectric by electrostatic coupling.

[0004]

However, in the case of the RF bias, an expensive RF power source must be used as a power source, and in order to effectively supply power to the load, the RF bias needs to be adjusted according to the load (in accordance with the gas pressure). The problem is that impedance matching must be performed (dynamically).
Further, in order to apply an RF bias, an electrode must be arranged on the back surface of the substrate and the substrate and the electrode must be electrostatically coupled, so that simultaneous processing (simultaneous film formation and simultaneous etching on both surfaces) on both surfaces of the substrate cannot be performed. That is also a problem.

In view of the above, the present invention provides a bias applying apparatus which improves bias application, eliminates the need for an expensive RF power source, eliminates the need for impedance matching, and enables simultaneous double-sided processing.
It is an object to provide a substrate processing apparatus.

[0006]

In order to achieve the above object, in a substrate processing apparatus according to the present invention, there is provided a vacuum chamber for generating plasma, a gas introduction system for introducing gas into the chamber, And a bias applying device for applying a bias voltage to the substrate disposed therein.
The bias applying device is characterized by comprising a pulse generating circuit and a ringing generating circuit to which an output of the pulse generating circuit is input.

When a gas is introduced into the plasma in the chamber, the gas is discharged, ionized and ionized. Since a bias voltage is applied to the substrate by the bias applying device, ionized gas molecules are attracted to the substrate. Since the bias applying device includes the pulse generating circuit and the ringing generating circuit, the pulse voltage is distorted by the ringing generating circuit, and the voltage having the distorted waveform is applied to the substrate. Therefore, a voltage having a waveform that oscillates at a frequency higher than the original pulse frequency is applied to the substrate, and similarly to when RF is applied, charge-up due to ions reaching the substrate can be prevented, and a desired film quality can be obtained. Good substrate processing such as film formation is possible. Since a voltage peak higher than the original voltage value can be obtained even if the original pulse waveform is distorted by ringing, there is no need for a pulse generation circuit for generating a high voltage. Expensive RF
Since a power supply is not required, cost can be reduced. The impedance matching at the time of RF bias is not required, and simultaneous processing on both surfaces of the substrate is possible.

If a CnHm gas is used as a gas to be introduced into the plasma in the chamber, a DLC film can be formed on the substrate. Also in this case, a DLC film can be simultaneously formed on both surfaces of the substrate, and furthermore, impedance matching at the time of RF bias is not required, and an expensive RF power source is not required, so that the cost can be reduced.

[0009]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows, as an example of a substrate processing apparatus to which the present invention is applied, a film forming apparatus for simultaneously forming a DLC film on both surfaces of a substrate. In FIG. 1, a film forming chamber 1
0 is sucked in vacuum by the gas exhaust system 11. The gas exhaust system 11 is composed of a main pump composed of, for example, a turbo molecular pump and a roughing pump (RP), and a pressure (for example, several mT) suitable for film formation in the film formation chamber 10.
orr). The film forming chamber 10 contains an argon gas (or a rare gas such as a Kr gas or an Xe gas or an inert gas such as a nitrogen gas), a CnHm gas (for example, a hydrocarbon gas such as methane or ethylene), or a vaporized carbon. Gas introduction system 1 for introducing hydrogen liquid, CF gas, etc., whose flow rate can be controlled by mass flow
2 are provided.

[0010] ECRs are provided at both ends of the film forming chamber 10.
(Electron Silotron Resonance) Discharge chambers 20 are respectively installed. The ECR discharge chamber 20 has a cylindrical shape, and a quartz window 21 made of a quartz glass plate is provided at an end of the ECR discharge chamber 20, and a cylindrical or rectangular waveguide 22 is attached through the quartz window 21. ing.
Microwaves are introduced into the ECR discharge chamber 20 through the waveguide 22. The quartz window 21 allows only microwaves to pass while maintaining a vacuum state in the ECR discharge chamber 20.

A magnet coil 23 for generating a magnetic field satisfying the ECR condition is wound along the outer periphery of the cylindrical ECR discharge chamber 20. Waveguide 22
When the frequency of the introduced microwave is 2.45 GHz, the strength of the magnetic field satisfying the ECR condition is 875 Ga
uss. This magnetic field distribution is designed so that the strength of the magnetic field decreases from the microwave introduction side toward the inside of the film forming chamber 10. The ECR discharge chamber 20 is usually designed as a TE11n mode cylindrical resonator.

At a substantially central position of the film forming chamber 10, a substrate 41 for forming a DLC film on both sides is set by an appropriate substrate transport mechanism (not shown). A bias voltage supplied from the voltage applying device 30 through a coaxial cable is applied to the substrate 41. The voltage application device 30 includes a pulse power supply 31 and a ringing generation circuit 32.

The pulse power supply 31 generates a pulse having a waveform as shown in FIG. 2, for example. The pulse shown in FIG.
The frequency is 0 Hz (30 Hz in the figure), of which about 95% is -200 V and about 5% is 0 V. The ringing generation circuit 32 generates a damped oscillation. That is, the transient phenomenon causes vibration at the rising portion of the input pulse waveform to distort the waveform. Thus, a voltage having a waveform as shown in FIG. 3 is obtained.

The ringing generating circuit 32 comprises a parallel circuit of a winding resistor 33 and a variable capacitance 34 in this example. Since the winding resistor 33 has an L component and an R component in high frequency, the circuit 32 is an RLC combining circuit. By changing the variable capacitance 34, the frequency of the ringing and the decay time can be adjusted. That is, the decay time of the ringing waveform has a correlation with the Q value of the RLC synthesis circuit, and the higher the Q value, the smaller the ridge attenuation of the waveform (the longer the decay time). Generally, when the R component is reduced, the decay time becomes longer. The frequency of ringing is substantially determined by the resonance frequencies of L and C.

ECR discharge chamber 2 through waveguide 22
When a microwave of 2.45 GHz is introduced into 0 and a magnetic field along the axis of the chamber 20 is formed by the magnet coil 23 at the same time, the ECR conditions are adjusted and an active ECR plasma is generated. With an appropriate magnetic field formed in the film forming chamber 10 by the magnet coil 23, the ECR
Plasma is drawn into the deposition chamber 10. This plasma discharges the hydrocarbon gas introduced into the film formation chamber 10, generates high-density plasma, and generates positive carbon ions, hydrogen ions, and hydrocarbon ions. The substrate 4 in which the positive ions are negatively biased by a voltage having a ringing waveform as shown in FIG.
It is drawn into 1 and accumulates. The deposition of the DLC film by this deposition is performed on both surfaces of the substrate 41. That is, the ringing waveform is -200V (or a minus side)
And 0V (or more positive side), but its frequency is sufficiently high. Therefore, the positive ions cannot follow the change and are drawn into the substrate 41 in response to the average voltage. Among the ions drawn into the substrate 41, a part of the hydrogen component returns to vacuum due to the impact of continuously arriving ions, and is exhausted as hydrogen gas or recombined with hydrocarbon ions in the plasma.

Since the quality (eg, hardness) of the DLC film to be formed greatly changes depending on the hydrogen (H) component in the film, it is necessary to control the hydrogen component in the film.
This is a very important point for the LC film forming apparatus. The hydrogen component in the film has a strong correlation with the substantial energy of the ions reaching the substrate 41. The higher the energy, the greater the rate at which the hydrogen component adhering to the substrate 41 returns to vacuum, so the hydrogen component in the film decreases. If the energy is too large, the action of breaking the sp2 or sp3 bond of the DLC film becomes large, so the bias application voltage needs to be set to an appropriate value. Generally -50
It is set according to the desired properties of the DLC film formed between V and -500V.

The DLC film formed on the substrate 41 is an insulating film. When a large number of positively charged ions accumulate on the insulating film, the surface of the substrate 41 is charged up and the ions become Energy does not deposit on the substrate 41, and it becomes impossible to form a film having a desired film quality. Here, not only is a pulsed voltage applied to the substrate 41 to keep it at 0 V for a period of about several percent, but also it is swung to 0 V or a positive side by several rebounds of ringing to draw electrons into the substrate 41 to charge up. Try to prevent. That is, the same effect as when the RF voltage is applied is realized without using the RF power supply.

The frequency, amplitude, and decay time of the vibration waveform caused by ringing can be adjusted as described above. The first negative peak of ringing is more negative than -200V. That is, since the voltage is larger than the negative pulse voltage value set by the pulse power supply 31, a large voltage can be effectively obtained with a small voltage setting. If the decay time is short, the focus of the vibration is fast and focuses to -200V before being pulled back to 0V. Based on such considerations, the R and R of the ringing generation circuit 32 are set according to the desired film quality.
L and C will be adjusted.

The ringing generation circuit 32 is connected to the R
Not only the C parallel circuit, but also various combinations of L, R, and C are conceivable. The variable element is not limited to the capacitance, but may be a resistance or an inductance. It is sufficient that one or more of these elements can be changed.

Further, in the above description, the DLC film forming apparatus has been described as an example, but the present invention is also applicable to a plasma etching apparatus. The plasma etching apparatus may have the same configuration as described above, and use CnFm gas as the introduced gas to increase energy. The ECR discharge is used in the above to generate a discharge. In addition, an RF (for example, 13.56 MHz) is applied to a parallel flat plate to cause a discharge, or electrons are emitted from a hot filament as a cathode to form an anode and a discharge. Various configurations can be employed, such as discharging between the two or applying a magnetic field thereto.

In addition, the specific configuration and the like can be variously changed without departing from the spirit of the present invention.

[0022]

As described above, according to the present invention, by applying a bias voltage to a substrate using a pulse generation circuit and a ringing generation circuit, the same as when an expensive RF power supply is used, Effective processing of the substrate can be performed, such as good film formation. Further, there is no need to perform impedance matching, and both-side simultaneous processing can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart showing a pulse voltage waveform output from a pulse power supply 31.

3 is a time chart showing a voltage waveform that has passed through a ringing generation circuit 32. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Film-forming chamber 11 Gas exhaust system 12 Gas introduction system 20 ECR discharge chamber 21 Quartz window 22 Waveguide 23 Magnet coil 30 Voltage application device 31 Pulse power supply 32 Ringing generation circuit 33 Winding resistance 34 Variable capacitance

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05H 1/46 H01L 21/302 B

Claims (2)

[Claims] A vacuum chamber in which a plasma is generated;
A gas introduction system for introducing a gas into the chamber; and a bias application device for applying a bias voltage to a substrate disposed in the chamber, wherein the bias application device includes a pulse generation circuit, and a pulse generation circuit. A substrate processing apparatus, comprising: a ringing generation circuit to which an output is input. 2. A vacuum chamber in which a plasma is generated;
A gas introduction system for introducing CnHm gas into the chamber;
A bias application device for applying a bias voltage to a substrate disposed in the chamber, the bias application device including a pulse generation circuit, and a ringing generation circuit to which an output of the pulse generation circuit is input; DLC on substrate
A substrate processing apparatus for forming a film.