JPH0774160A - Microwave plasma treating equipment - Google Patents

Abstract

PURPOSE:To provide a microwave plasma treating equipment that is capable of improving etching rate and obtaining excellent working characteristics at low cost. CONSTITUTION:A plasma chamber 1 is provided therein with a sample stage 2 to mount a workpiece 3 on. The sample stage 2 is connected with a high-frequency power supply 5 that applies a.c. voltage through a capacitor 4. The high-frequency power supply 5 generates a high frequency of 13.56MHz. The area surrounding the sample stage 2 is grounded through a grounding electrode 6. A waveguide 7, a microwave oscillation source 8, a d.c. power supply 9 and a magnet 10 are installed opposite the workpiece placement surface of the sample stage 2. These parts encircle the end 1a of the plasma chamber 1 on the workpiece placement surface side, and turn treatment gas into plasma to produce plasma 11 in the chamber 1. A gas feed port 12 is formed in proximity to the end 1a of the plasma chamber 1 to introduce treatment gas from a gas feed equipment to the chamber 1. There is an exhaust port on the side opposite to the end 1a, which leads to an exhaust equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus, and more particularly to a plasma processing apparatus suitable for etching a solid surface with ions in plasma.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 56-3731
As described in No. 1, there has been one that uses a plasma processing means using a microwave and a magnetic field and a means for applying an alternating voltage of 100 KHz to 10 MHz to the sample in combination to etch the sample. However, no consideration was given to the use of a high frequency of 10 MHz or more for the AC voltage.

[0003]

SUMMARY OF THE INVENTION The above-mentioned prior art is 10
No consideration is given to the one using an AC voltage with a frequency of MHz or more. In reality, due to the restrictions of the Radio Law and industrial technology, only an oscillation source in the low frequency region of 400 KHz or 800 KHz can be used, and etching is further performed. There was a problem that there was a limit in improving the speed.

An object of the present invention is to provide a microwave plasma processing apparatus which can improve the etching rate and obtain excellent processing characteristics at low cost.

[0005]

[Means for Solving the Problems] The above object is 100 KH.
This is achieved by changing the low frequency range of z to 10 MHz to the high frequency range of 13.56 MHz and applying an AC voltage to the sample.

[0006]

When the conventional low-frequency discharge is used, the atoms or molecules of the processing gas excited by microwaves in a high vacuum pressure have a long moving distance due to a long AC voltage cycle, which causes trapping. Reach the sample without being disturbed.
At this time, if the electric field lines of the low-frequency discharge act vertically on the sample, the probability that the ions will enter the sample perpendicularly increases, but the electric field lines act vertically on the sample. If not, it becomes difficult to give directionality to the sample.

When a high frequency discharge of 13.56 MHz is used as in the present invention, the moving distance of ions is shortened due to the short cycle of the AC voltage, and the ions are trapped.
Here, if a blocking capacitor is inserted between the sample stage and the high-frequency oscillation source and the sample stage is floated from the ground potential, the trapping phenomenon described above causes the DC potential to constantly exist in the sample stage. . An ion sheath is formed near the sample due to the difference between the DC potential (charged to the negative side with respect to the ground potential) and the plasma potential (positive potential), and the ions are collected regardless of the electric lines of force of the high frequency discharge. Will be incident perpendicularly to. Further, since the ions obtain kinetic energy due to this potential difference, the processing speed of the sample is improved as compared with the case of using low frequency discharge.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, a sample table 2 for placing a sample 3 is provided in a plasma chamber 1 which is a vacuum container. A high frequency power source 5 which is a high frequency voltage applying means for applying an alternating voltage via a capacitor 4 is connected to the sample table 2.

The high frequency power supply 5 oscillates a high frequency of 13.56 MHz. The other side of the high frequency power source 5 is grounded. A ground electrode 6 is provided around the sample table 2. The ground electrode 6 is grounded. A waveguide 7 is provided on the side of the sample table 2 facing the sample surface so as to surround the end 1 a of the plasma chamber 1. A microwave oscillation source 8 is attached to the end of the waveguide 7. A DC power supply 9 is connected to the microwave oscillation source 8. Microwave oscillation source 8
Oscillates a microwave of 2.45 GHz, for example. A magnet 10, which is a magnetic field generating means, is provided around the end 1 a of the plasma chamber 1 via a waveguide 7.

A gas introduction port 12 for introducing a processing gas into the end portion 1a of the plasma chamber 1 from a gas supply device (not shown) is provided near the end portion 1a of the plasma chamber 1. An exhaust port connected to an exhaust device (not shown) is provided on the opposite side of the end 1a of the plasma chamber 1.

With the above structure, the end portion 1a of the plasma chamber 1 is
In the state in which the processing gas is supplied to the plasma chamber 1 and the plasma chamber 1 is evacuated to a predetermined pressure, a microwave is oscillated from the microwave oscillation source 8. The microwave is guided to the waveguide 7 and passes through the end portion 1a of the plasma chamber 1 to enter the end portion 1a. The processing gas in the end 1a is excited by microwaves. At this time, the magnet 10 generates a magnetic field in the end 1a to generate a stronger plasma 11, and the plasma 11 is transported toward the sample 3 by controlling the magnetic field. By applying a high frequency voltage to the sample stage 2, a high frequency discharge is generated in the plasma transported in the vicinity of the sample 3 and a bias potential is generated in the sample stage 2. Due to the bias potential of the sample table 2, the ions in the plasma due to the high frequency discharge are vertically incident on the sample 3, and the sample 3 is etched.

Further, by controlling the electric power of the high frequency power source 5, the ion potential in the plasma can be controlled independently of the plasma 11 generated by the action of the microwave and the magnetic field by controlling the bias potential of the sample stage 2. .

FIG. 2 shows the case where an AC voltage of each frequency was applied to the sample stage 2 under the conditions that SF ₆ was used as the processing gas, the gas pressure was 5.2 × 10 ² Pa, and the microwave power was 250 W. The relationship between the applied voltage Vpp and the self-bias voltage Vdc is shown.

According to FIG. 2, as the total applied voltage Vpp increases, the self-bias voltage Vdc also increases. Further, for the same total applied voltage Vpp, the self-bias voltage Vdc also increases as the frequency increases. That is, the low frequency of 800 KHz to 10 MH
The self-bias voltage Vdc is higher for the same total applied voltage Vpp at 13.56 MHz, which is a higher frequency than z.

As described above, according to this embodiment, 13.56M
By using a high frequency of Hz, the same total applied voltage Vp
The self-bias voltage Vdc can be increased with respect to p, and accordingly, the energy for accelerating the ions is increased and the etching rate can be improved.
Conversely, ion acceleration can be controlled with a small input power.

Industrially, 800 KHz and 10 MH
Low frequency oscillators such as z are not generally available on the market, and high frequency oscillators with 13.56 MHz are available on the market.
The device cost of the 13.56 MHz high frequency oscillator is lower. Therefore, if a 13.56 MHz high frequency oscillator is used, the controllability of ions is improved and the apparatus can be made cheaper than a low frequency oscillator of 10 MHz or less.

Although the present embodiment describes the apparatus using the electron cyclotron resonance (ECR) discharge as the plasma generating means, the same effect can be obtained even if the plasma generating means uses the microwave discharge.

[0019]

According to the present invention, the frequency of 13.
By applying a high frequency voltage of 56 MHz, it is possible to improve the etching rate and obtain excellent processing characteristics at low cost.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a microwave plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a total applied voltage and a self-bias voltage.

[Explanation of symbols]

1 ... Plasma chamber 2 ... Sample stage 4 ... Capacitor 5 ... High frequency power source 8 ... Microwave oscillation source 10 ... Magnet

Claims (1)

[Claims] 1. A vacuum container, a gas supply device for supplying a processing gas into the vacuum container, an exhaust device for decompressing and evacuating the inside of the vacuum container to a predetermined pressure, and a plasma of the processing gas in the vacuum container. Means, a sample table provided in the vacuum container for supporting a sample, and a frequency of 13.56 MHz on the sample table
And a high frequency voltage applying means for applying the high frequency voltage of 1.