JPH0850998A - Plasma processing device - Google Patents

Abstract

PURPOSE:To facilitate adjustment of each coil current as well as to increase flux density and to uniformalize the distribution of the flux density by composing a flat plate coil unit of plural coils. CONSTITUTION:A plate coil unit 13 is composed by arranging plate coils 14, 15, 16, 17 on each of the fan shaped planes obtained by dividing a top plate 12 into four pieces and it is connected to a high frequency power supply 19 through a variable capacitor 18. In such a composition, the capacitance of a variable capacitor 18 is adjusted, an inductance value and the degree of plasma coupling are made adjustable by changing a current flowing through the coils 14-17, so that the uniformity of plasma in a vacuum container 10 is accomplished easily. Furthermore, the impedance is reduced by parallel connection of the coils so as to suppress the plasma oscillation caused by the impedance, thereby a stable and uniform high density plasma can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus for supplying high frequency power by inductive coupling to generate plasma and utilizing the plasma to manufacture semiconductor elements.

[0002]

2. Description of the Related Art There are a capacitive coupling system and an inductive coupling system for supplying high frequency power to a vacuum container to generate plasma and give energy to the plasma. 2. Description of the Related Art In recent years, devices such as semiconductor manufacturing devices and LCD devices that use plasma for processing have been required to have a large processing capacity, and high density of generated plasma is required.

A typical configuration of the electrostatic coupling type plasma processing apparatus described above applies a high frequency power between parallel plate electrodes facing each other, and a high frequency is generated in plasma formed between the parallel plate electrodes. Since the high-energy ions and electrons in the plasma reach the object by the electric field,
There is a problem that not only the object to be treated is damaged but also the contamination from the electrode cannot be avoided.

On the other hand, in the inductively coupled plasma processing apparatus, as disclosed in Japanese Patent Application No. 1-338900, the electrons bound by the magnetic flux have low energy and the ions also have low energy. There are advantages that high-density plasma can be easily generated, damage to the object to be processed by electrons and ions is small, and the processing capacity can be greatly improved.

A conventional inductively coupled plasma processing apparatus will be described with reference to FIGS. 4 and 5.

A metal vacuum container 1 is provided, and a cover 2 made of a magnetically permeable material such as quartz, which covers the inner wall surface and the ceiling of the vacuum container 1, is fitted into the vacuum container 1. A coil 3 formed in a flat spiral shape is arranged on the ceiling upper surface of the cover 2, one end of the coil 3 is connected to the first high-frequency power source 4, and the other end is grounded. The bottom plate 5 that hermetically closes the lower end of the vacuum container 1 is provided with a processing table 7 facing the coil 3 and on which an object 6 to be processed is placed, and the processing table 7 is connected to a second high frequency power supply 8. Has been done.

High frequency power is supplied to the coil 3 from the first high frequency power supply 4, plasma is generated in the cover 2 by inductive coupling, and high frequency energy is supplied to the plasma. Since the plasma generated by the inductive coupling lacks anisotropy, high frequency power is applied to the processing table 7 from the second high frequency power source 8 to generate a high frequency bias. Thus, the object 6 to be processed is etched by the ions from the plasma.

[0008]

However, in the above-mentioned conventional inductively coupled plasma processing apparatus, the coil 3 formed in a flat plate spiral shape is used to form the induction magnetic field, and the coil 3 is generated. To make the plasma density uniform,
The shape of the vacuum container 1, the size of the object 6 to be processed, the shape of the coil that is appropriate for the correlation between the vacuum container 1 and the object 6 to be processed, etc. must be set, and enormous experiments are repeated each time manufacturing is performed. The coil shape and the number of turns.

Further, in determining the specifications of the coil, the impedance increases as the number of turns of the coil increases, and a high voltage is required to obtain a required high frequency current. Therefore, a high frequency power supply device and a coil terminal terminal corresponding thereto are required. Electrical insulation between them becomes difficult. Therefore, it becomes an expensive high-frequency power supply device.

Further, the larger the vacuum container 1, the higher the inductance of the spiral coil. For this reason, if the number of turns is reduced, the magnetic flux density distribution will be in accordance with the shape of the flat plate coil, and the density difference will become large. Since the plasma density distribution corresponds to the magnetic flux density distribution, plasma oscillation occurs and the plasma becomes unstable. This has a problem that electrons are accumulated on the processed material and the film quality is not uniform when a thin film of the processed material 6 is formed.

In view of the above situation, the present invention aims to easily obtain uniform high density plasma in an inductively coupled plasma processing apparatus.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a plasma is generated by applying high frequency power to a flat plate coil unit arranged to face an object to be processed, and the plasma is used to process the object to be processed. In the processing device, the flat plate coil unit is composed of a plurality of coils, or a current adjusting means is connected to each of the plurality of coils, or a plurality of coils are connected in parallel to a high frequency power source. It is a feature.

[0013]

[Function] By forming the flat coil unit with a plurality of coils, the magnetic flux density can be increased without increasing the impedance, and the magnetic flux density distribution can be made uniform.
Furthermore, the current flowing through each coil can be adjusted,
The state of magnetic flux generation for each coil can be adjusted, and uniform high-density plasma can be easily obtained.

[0014]

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

A processing table 11 is airtightly provided on the bottom of the vacuum container 10, and an object 6 to be processed is loaded on the processing table 11. The ceiling of the vacuum container 10 is composed of a ceiling plate 12 made of an insulating material such as quartz, glass, and anana ceramics, and a flat plate coil unit 13 is provided on an upper surface of the ceiling plate 12.
To be installed.

The flat plate coil unit 13 is composed of a plurality of flat plate coils 14, 15, 16 and 17, and the coils 14, 15, 16 and 17 are arranged in respective fan-shaped planes obtained by dividing the ceiling plate 12 into four. The variable capacitors 18
It is connected in parallel to the first high frequency power supply 19 via. The processing table 11 is grounded via a switch 20, and the processing table 11 is connected to a second high frequency power supply 22 via a DC blocking capacitor 21.

In the figure, 23 is a gas inlet for introducing a processing gas, and 24 is an exhaust port.

High frequency power is supplied from the first high frequency power supply 19 to the flat plate coil unit 13, plasma is generated in the vacuum container 10 by inductive coupling, and high frequency energy is supplied to the plasma.

In the processing table 11, the switch 20 is turned on to be grounded or a high frequency bias is applied from the second high frequency power source 22 according to the purpose of processing the object 6.

That is, when the switch 20 is turned on and grounded, a required thin film is formed on the object 6 to be processed, and when a high frequency bias is applied from the second high frequency power source 22, a film is formed on the object 6 to be processed. The etched thin film is etched.

The coils 14, 15, 16 and 17 are slightly different in inductance value and plasma coupling degree. The inductance value and the degree of plasma coupling can be adjusted by adjusting the electrostatic capacitance value of the variable capacitor 18 and changing the current flowing through the coils 14, 15, 16 and 17. The plasma density can be made uniform.

Further, as described above, when the size of the vacuum container 10 becomes large, the flat coil unit 13 becomes large. The flat coil unit 13 has a plurality of coils 14,
Since it is composed of 15, 16 and 17, the impedance is lowered, and further, a plurality of coils 14, 15, 16 and
The impedance is further reduced by connecting 17 in parallel. Thus, it is possible to suppress the plasma vibration caused by the lowered impedance.

Furthermore, by measuring the plasma density in the vacuum chamber 10 and adjusting the current flowing through the coils 14, 15, 16, 17 with the variable capacitor 18, a plurality of coils 14, 15, 16, 17 are obtained. The intensity of the magnetic flux generated by the above can be adjusted, and the magnetic flux density formed by the flat plate coil unit 13 as a whole can be made uniform. Therefore,
A stable and uniform plasma can be obtained without disturbing the plasma.

Incidentally, the method of dividing the flat plate coil unit 13,
Various arrangements of the coils are conceivable. For example, as shown in FIG. 3, a circular coil is arranged at the center and an arc-shaped coil is arranged around it.

The variable capacitor 18 may be any means for adjusting the current, and may be a variable resistor, a coil, or a combination of these.

[0026]

As described above, according to the present invention, since the flat coil unit is composed of a plurality of coils,
Impedance can be reduced without generating density difference in magnetic flux distribution, plasma oscillation can be suppressed, and uniform high-density plasma can be easily obtained by adjusting the current supplied to each coil. Be effective.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic plan view of the same embodiment.

FIG. 3 is a schematic plan view showing another embodiment of the present invention.

FIG. 4 is a schematic vertical sectional view showing a conventional example.

FIG. 5 is a schematic plan view of the prior art example.

[Explanation of symbols]

 6 Processing Object 10 Vacuum Container 13 Flat Coil Unit 14 Coil 15 Coil 16 Coil 17 Coil 18 Variable Capacitor 19 First High Frequency Power Supply 22 Second High Frequency Power Supply

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/31 C

Claims (3)

[Claims] 1. A plasma processing apparatus for applying high-frequency power to a flat plate coil unit arranged to face an object to be processed to generate plasma and using the plasma to process the object to be processed, A plasma processing apparatus comprising a coil unit composed of a plurality of coils. 2. The plasma processing apparatus according to claim 1, wherein a current adjusting means is connected to each of the plurality of coils. 3. A plasma processing apparatus according to claim 1, wherein a plurality of coils are connected in parallel to a high frequency power source.