JP2630603B2 - Plasma processing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma processing apparatus, and more particularly, to a plasma processing apparatus having a magnetic field generating mechanism.

[Prior Art] FIG. 3 is a sectional view of a conventional plasma processing apparatus. In the figure, reference numeral 3 denotes a vacuum container. In the vacuum vessel 3,
High frequency electrode for applying high frequency power (hereinafter referred to as cathode)
2 and a counter electrode (hereinafter, referred to as an anode) 1 that is disposed to face the cathode 2. On the cathode 2,
The high frequency power supply 6 is connected via the blocking capacitor 7. The anode 1 is grounded. The vacuum vessel 3 is provided with a gas inlet 4 for introducing a gas, and further provided with a gas exhaust pipe 8 for discharging a used gas.

 Next, the operation of the plasma device will be described.

A reactive gas is introduced from the gas inlet 4 into the vacuum vessel 3. On the other hand, air is exhausted from the exhaust port 8 and the vacuum vessel 3
The inside is maintained at a predetermined gas pressure. Next, high frequency power is applied from the high frequency power supply 6 into the vacuum vessel 3. As a result, active ionic species and radicals of the gas are generated. The plasma treatment, for example, etching of the sample 5 is performed by the active ion species and radicals.

[Problems to be Solved by the Invention] A conventional plasma processing apparatus is configured as described above. Therefore, in the impedance matching circuit between the plasma and the high-frequency power supply 6, the blocking capacitance 7 for reducing the net DC current to 0 is sandwiched. A self-bias voltage (Vdc) is generated. In a conventional plasma processing apparatus, the self-bias voltage (Vdc) is controlled by changing the power of the high frequency power supply 6 or by changing the gas pressure and the gas flow rate. However, in order to change the etching shape, the etching rate, the selectivity, etc., it is necessary to change the output of the high-frequency power supply 6 or the gas pressure and the gas flow rate. In this case, the above-mentioned self-bias voltage is generated, and as a result, there is a problem that radiation damage is caused on the surface of the etched sample.
In addition, the conventional plasma processing apparatus cannot follow the fluctuation of the self-bias voltage due to the turbulence of the plasma or the like, and as a result, it is difficult to control the ion energy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and a plasma processing method capable of reducing radiation damage on the surface of an etched sample and following a fluctuation of a self-bias voltage due to plasma turbulence or the like. It is intended to provide a device.

[Means for Solving the Problems] A plasma processing apparatus according to the present invention includes a vacuum vessel for introducing a sample therein and plasma-treating the sample using ion species, and supplying high-frequency power to the vacuum vessel. A cathode to be applied and an anode arranged to face the cathode are provided. A magnetic field generating mechanism is provided which is capable of changing its magnetic field strength so as to generate lines of magnetic force in a direction perpendicular to the direction of the electric field applied to the cathode. The plasma processing apparatus includes a self-bias measurement mechanism that measures a self-bias voltage generated on the surface of the cathode.
The plasma processing apparatus further interlocks the magnetic field generation mechanism and the self-bias measurement mechanism, and adjusts the magnetic field strength of the magnetic field generation mechanism based on the value of the self-bias voltage measured by the self-bias measurement mechanism. And a self-bias control mechanism for controlling the self-bias voltage to a desired value.

[Operation] As described above, the plasma processing apparatus according to the present invention
The magnetic field generation mechanism and the self-bias measurement mechanism are linked, and the magnetic field strength of the magnetic field generation mechanism is changed based on the value of the self-bias voltage measured by the self-bias measurement mechanism, whereby the self-bias voltage is set to a desired value. Since the self-bias control mechanism for controlling the self-bias voltage constantly is provided, the self-bias voltage generated on the surface of the cathode can be stably maintained constant and can be freely changed.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a plasma processing apparatus according to one embodiment of the present invention. In the figure, 3 is a vacuum container,
A high-frequency electrode (hereinafter, referred to as a cathode 2) for applying high-frequency power and a counter electrode (hereinafter, referred to as an anode 1) arranged to face the cathode 2 are arranged in the vacuum vessel 3. A sample 5 is placed on the cathode 2. A high frequency power source 6 is connected to the cathode 2 via a blocking capacitor 7. The anode 1 is grounded. The vacuum vessel 3 is provided with a gas inlet 4 for introducing a gas, and a gas exhaust pipe 8 for discharging an etching gas. Outside the vacuum vessel 3,
A magnetic field generating mechanism such as an electromagnet 9 is provided so that magnetic lines of force are generated in a direction orthogonal to the direction of application of the electric field applied from the high frequency power supply 6. The magnetic field strength of the electromagnet is configured to be changed.

Next, a method of controlling a self-bias voltage generated on the surface of the cathode 2 using the plasma processing apparatus will be described.
The magnetic field strength is changed by changing the coil current of the electromagnet 9. When the magnetic field intensity is changed, the self-bias voltage generated on the surface of the cathode 2 changes. The self-bias voltage is measured by a DC voltmeter or the like, and feedback is applied to the coil current. By doing so, the self-bias voltage can be controlled to a desired value.

FIG. 2 illustrates how the self-bias voltage changes when the magnetic field strength of the electromagnet is changed. Second
As is apparent from the figure, the self-bias voltage can be controlled by controlling the magnetic field strength. If the self-bias voltage can be controlled freely, ion energy can be controlled freely, and radiation damage on the surface of the etched sample can be reduced.

[Effects of the Invention] As described above, according to the plasma processing apparatus of the present invention, the magnetic field generation mechanism and the self-bias measurement mechanism are linked, and the value of the self-bias voltage measured by the self-bias measurement mechanism is used. Since a self-bias control mechanism that changes the magnetic field strength of the magnetic field generation mechanism and controls the self-bias voltage to a desired value is provided, the self-bias voltage generated on the surface of the cathode can be controlled, and thus the ion energy is controlled. become able to. As a result, radiation damage on the surface of the etched sample can be reduced. Further, the fluctuation of the self-bias voltage due to the disturbance of the plasma can be stabilized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a plasma processing apparatus according to one embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the magnetic field strength and the self-bias voltage when the coil current of the electromagnet is changed. FIG. 3 is a sectional view of a conventional plasma processing apparatus. In the figure, 1 is an anode, 2 is a cathode, 3 is a vacuum vessel, 5 is a sample, 6 is a high frequency power supply, and 9 is an electromagnet. In the drawings, the same reference numerals indicate the same or corresponding parts.

Continued on the front page. (72) Inventor Hisakusaku Nishioka 4-1-1 Mizuhara, Itami-shi, Hyogo Mitsubishi Electric Machinery Co., Ltd. LSI Research Institute (72) Inventor Nobuo Fujiwara 4-1-1 Mizuhara, Itami-shi, Hyogo Mitsubishi Electric (56) References JP-A-61-163639 (JP, A) JP-A-60-94725 (JP, A) JP-A-59-232420 (JP, A)

Claims (1)

(57) [Claims] 1. A vacuum container for introducing a sample into the sample and plasma-treating the sample using ionic species, a cathode for applying high-frequency power in the vacuum container, and disposed opposite to the cathode. An anode, a magnetic field generating mechanism installed to generate magnetic field lines in a direction orthogonal to the direction of an electric field applied to the cathode, and capable of changing the magnetic field intensity; and a magnetic field generating mechanism generated on the surface of the cathode. A self-bias measurement mechanism for measuring a self-bias voltage to be applied, and the magnetic field generation mechanism and the self-bias measurement mechanism are linked to each other, and the magnetic field generation mechanism is based on a value of the self-bias voltage measured by the self-bias measurement mechanism. A self-bias control mechanism for controlling the self-bias voltage to a desired value by changing the magnetic field intensity.