JPH0987864A - Dry etching equipment - Google Patents

Abstract

(57) An object of the present invention is to increase the amount of plasma in a chamber and increase the amount of plasma moving in the direction of a substrate so that etching processing can be performed at high speed. An electron shield electrode is provided above the magnetic neutral line discharge plasma, and an electron shield electrode is provided at an intermediate position between the magnetic neutral line discharge plasma and a substrate. , A potential −Vb that is a negative bias with respect to the plasma potential Vp is applied. This allows
The electrons flying vertically in the space inside the chamber 1 are repelled in the vicinity of the electron shield electrodes 14 and 15 and pushed back toward the generation region of the magnetic neutral wire discharge plasma 13, contributing to the promotion of ionization of the introduced gas. To do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus that performs a dry etching process using magnetic neutral line discharge plasma.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a conventional dry etching apparatus using magnetic neutral line discharge plasma. In the figure, 1 is a quartz plasma generating cylindrical chamber (hereinafter,
2, 3, 4 are first, second, and third magnetic field generating coils arranged in parallel in the vertical direction around the outer periphery of the chamber 1, and 5 is the first magnetic field generating coil 2 and the first magnetic field generating coil 2. 3, a high frequency coil disposed inside the magnetic field generation coil 3 located in the middle of the magnetic field generation coil 4 and at the outer periphery of the chamber 1, 6 is a high frequency power source for applying a high frequency to the high frequency coil 5, and 7 is a process gas. Inlet, 8 is evacuation outlet, 9
Is a vacuum pump, 10 is a substrate stage separated from the chamber 1, 11 is a substrate placed on the substrate stage 10, 1
Reference numeral 2 denotes a high frequency power source for applying a high frequency to the substrate stage 10.

In this dry etching apparatus, first, the vacuum pump 9 is used to evacuate the chamber 1 to a high vacuum. Then, the process gas is introduced into the chamber 1 through the gas inlet 7 and maintained at about 10 ^-1 to 10 ^-2 Pa. After such a state, currents of the same magnitude are made to flow through the magnetic field generating coils 2 and 4 in the same direction. Then, "Reference: Jpn.J.
Appl.Phys.Vol.33 (1994) pp.L43-L44 ”, an annular magnetic neutral line with zero magnetic field strength is formed at the intermediate position between the magnetic field generating coils 2 and 4. To be done.

Next, when a current in the opposite direction to the current flowing through the magnetic field generating coils 2 and 4 is passed through the magnetic field generating coil 3, the magnetic neutral line is spatially separated into two, one of which is inside the chamber 1. The other is formed outside the chamber 1. After such a state, when a high frequency is applied to the high frequency coil 5 using the high frequency power supply 6, an electric field (high frequency electric field) is formed along the magnetic neutral wire formed in the chamber 1. As a result, the electrons in the vicinity including the magnetic neutral wire formed in the chamber 1 obtain energy by the high frequency electric field, ionize the introduced gas and flow a discharge current (high frequency induction discharge current), and the inside of the chamber 1 A plasma (magnetic neutral line discharge plasma) 13 composed of electrons and ions is formed in the vicinity space including the magnetic neutral line. These electrons and ions move toward the inner wall of the chamber 1, but since the magnetic lines of force are oriented in the vertical direction, they mainly move and diffuse in the vertical direction.

Next, a high frequency power source 12 is attached to the substrate stage 10.
When a high-frequency electric field is applied using, the magnetic field formed by the magnetic field generating coils 2, 3, 4 among the ions and electrons in the magnetic neutral line discharge plasma 13 formed in the chamber 1 and the substrate stage 10 are Ions and electrons moving toward the substrate stage 10 due to the formed electric field collide with the substrate 11. As a result, when the process gas introduced into the chamber 1 is an inert gas, the sputter etching progresses on the substrate 11, and when the process gas is a reactive gas, the reactive etching progresses on the substrate 11. .

The dry etching apparatus has a feature that plasma can be easily generated in a pressure region of 10 ^-1 Pa or less where normal discharge is difficult to generate. this is,
The existence of a kind of magnetic well, which is a closed curve with zero magnetic field strength,
This is due to the effect that the scattered electrons are retained on the spot and a lot of seeds of the discharge are stored.

[0007]

However, in such a dry etching apparatus, a part of the introduced gas is ionized into a plasma continuously on and near the magnetic neutral line by the high frequency induction electric field, and electrons are generated. In addition, the main component of the ion is that the electrons easily move along the magnetic field, so that it is influenced by this and diffuses in the vertical direction. Therefore, if it is left as it is, it simply becomes a spatial diffusion in the vertical direction, and the ionization due to the collision between the electrons and the introduced gas cannot be performed more efficiently.

Further, the ions, which are the main players of the etching reaction, cannot be effectively injected into the substrate 11 by the free diffusion of the ions which move downward together with the electrons.

The first object of the present invention is to:
Efficiently utilize the electrons diffused from the magnetic neutral line discharge plasma for ionization of the introduced gas, enrich the amount of plasma in the chamber, increase the amount of plasma moving toward the substrate, and perform high-speed etching processing. It is to provide a dry etching apparatus capable of performing. Another object of the second invention is, in addition to the object of the first invention, is to provide a dry etching apparatus capable of aligning the incidence of ions to the substrate and making the processing uniform.

[0010]

In order to achieve such an object, a first invention (an invention according to claim 1) is to provide an upper position of a magnetic neutral line discharge plasma, a magnetic neutral line discharge plasma and a substrate. An electron shielding electrode to which a potential that is a negative bias with respect to the plasma potential is applied is provided at an intermediate position between and. According to the present invention, the electrons that diffuse from the magnetic neutral line discharge plasma and fly vertically in the space inside the chamber are pushed back toward the magnetic neutral line discharge plasma generation region by the electron shield electrode.

A second aspect of the invention (the invention according to claim 2) is to provide an electron shield electrode to which a negative bias with respect to the plasma potential is applied, above the magnetic neutral line discharge plasma. An ion accelerating electrode to which a potential that is a negative bias with respect to the plasma potential is applied is provided at an intermediate position between the discharge plasma and the substrate. According to the invention,
Electrons that diffuse from the magnetic neutral line discharge plasma and fly upward and downward in the space inside the chamber are pushed back toward the generation region of the magnetic neutral line discharge plasma by the electron shielding electrode and the ion acceleration electrode, Ions (positive ions) due to the potential difference between the ion acceleration electrode and the plasma potential
Are accelerated, and ions with good directivity can be obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments. [Embodiment 1: First Invention] FIG. 1 is a configuration diagram of a dry etching apparatus showing a first embodiment of the present invention.
3, the same reference numerals as those in FIG. 3 denote the same or equivalent components, and a description thereof will be omitted. In this embodiment,
An electron shield electrode 14 is provided above the magnetic neutral line discharge plasma 13, and an electron shield electrode 15 is provided at an intermediate position between the magnetic neutral line discharge plasma 13 and the substrate 11.
DC power supplies 16 and 17 are connected to 4 and 15 to apply a potential -Vb (eV) that is a negative bias to the plasma potential Vp (eV) (Vp> -V).
b).

In this dry etching apparatus, first, the vacuum pump 9 is used to evacuate the chamber 1 to a high vacuum. Then, the process gas is introduced into the chamber 1 through the gas inlet 7 and maintained at about 10 ^-1 to 10 ^-2 Pa. After such a state, currents of the same magnitude are made to flow through the magnetic field generating coils 2 and 4 in the same direction. Then, an annular magnetic neutral wire having a magnetic field strength of zero is formed at an intermediate position between the magnetic field generating coils 2 and 4.

Next, when a current in the direction opposite to the current flowing through the magnetic field generating coils 2 and 4 is passed through the magnetic field generating coil 3, the magnetic neutral line is spatially separated into two, one of which is inside the chamber 1. The other is formed outside the chamber 1. After such a state, when a high frequency is applied to the high frequency coil 5 using the high frequency power supply 6, an electric field (high frequency electric field) is formed along the magnetic neutral wire formed in the chamber 1. As a result, the electrons near the magnetic neutral wire formed in the chamber 1 gain energy by the high frequency electric field, ionize the introduced gas and flow the discharge current (high frequency induction discharge current), and the electrons in the chamber 1 A plasma (magnetic neutral line discharge plasma) 13 composed of electrons and ions is formed in a nearby space including the magnetic neutral line.

While the high frequency induction discharge current continues to flow in the magnetic neutral line discharge plasma 13, plasma (ions, electrons) is generated, overflows, and diffuses to the surroundings. Since the mass of electrons in this plasma is much smaller than that of ions, its temperature (electron temperature) is extremely high and the frequency of collision between particles is low. Therefore, the electrons in the magnetic neutral wire discharge plasma 13 are largely diffused in the vertical direction along the vertical magnetic field created by the magnetic field generating coils 2, 3 and 4.

Here, in this embodiment, the potential -Vb (eV), which is a negative bias with respect to the plasma potential Vp (eV), is applied to the electron shield electrodes 14 and 15. The electrons flying vertically in the space are repelled in the vicinity of the electron shield electrodes 14 and 15 and pushed back toward the generation region of the magnetic neutral wire discharge plasma 13. Among these electrons, the electrons that have reached the generation region of the magnetic neutral line discharge plasma 13 contribute to the promotion of ionization of the introduced gas by the action of the electric field and the magnetic field formed in this generation region, that is, electron-neutral. The frequency of atom collision increases, and the amount of ions generated in the magnetic neutral line discharge plasma 13 increases. As a result, the amount of plasma in the chamber 1 is abundant as compared with the conventional dry etching device (the dry etching device of FIG. 3) in which the electron shielding electrodes 14 and 15 are not built in the chamber 1. In the magnetic neutral line discharge plasma 13, ions are also generated due to ion-neutral atom collision, but the ionization efficiency is low as compared with electron-neutral atom collision. Therefore, it is a good idea to effectively use the electrons in the plasma, and in this embodiment, based on such an idea, the behavior of the electrons in the plasma is focused, and the electrons are diffused from the magnetic neutral line discharge plasma 13. I try to push back the incoming electrons.

In this state, the substrate stage 10
When a high-frequency electric field is applied to the substrate using a high-frequency power source 12, among the ions and electrons in the magnetic neutral line discharge plasma 13 formed in the chamber 1, the magnetic field generated by the magnetic field generating coils 2, 3, 4 and the substrate The ions moving toward the substrate stage 10 due to the electric field formed on the stage 10 collide with the substrate 11. As a result, when the process gas introduced into the chamber 1 is an inert gas, sputter etching proceeds on the substrate 11,
When the reaction gas is used, the reactive etching proceeds on the substrate 11. Here, in this embodiment, since the amount of plasma in the chamber 1 is abundant, the amount of plasma moving toward the substrate is increased, and etching can be performed at high speed.

In this embodiment, the DC power supplies 16 and 17 are connected to the electron shield electrodes 14 and 15 to apply the potential -Vb. However, in some cases, the DC power supplies 16 and 17 are omitted and grounded. It may be a potential. In this embodiment, the high frequency power source 12 is connected to the substrate stage 10 to apply the high frequency bias.
In some cases, a configuration may be adopted in which a DC bias is applied.

[Second Embodiment: Second Invention] FIG. 2 is a block diagram of a dry etching apparatus showing a second embodiment of the present invention. 3, the same reference numerals as those in FIG. 3 denote the same or equivalent components, and a description thereof will be omitted. In this embodiment, an electron shield electrode 18 is provided above the magnetic neutral line discharge plasma 13, a DC power supply 19 is connected to the electron shield electrode 18, and a negative bias is applied to the plasma potential Vp (eV). The potential -Vb (eV) is applied (Vp> -Vb). Further, one mesh-shaped ion acceleration electrode 20 is provided at an intermediate position between the magnetic neutral line discharge plasma 13 and the substrate 11, and the ion acceleration electrode 20 is
The DC power supply 21 is connected to apply a potential -Ve (eV) that is a negative bias to the plasma potential Vp (eV) (Vp> -Ve).

In this dry etching apparatus, magnetic neutral line discharge plasma 13 is formed in chamber 1 as in the first embodiment. This magnetic neutral line discharge plasma 1
While the high frequency induction discharge current continues to flow in 3, the plasma (ions, electrons) is generated and overflows, and diffuses to the surroundings. At this time, electrons having a temperature higher than that of the ions and a mass much smaller than that of the ions have a small frequency of collision between particles, and therefore, a large amount of electrons are diffused in the vertical direction along the vertical magnetic field generated by the magnetic field generating coils 2, 3 and 4. Go.

Here, in this embodiment, the plasma potential Vp is applied to the electron shield electrode 18 and the ion acceleration electrode 20.
A potential that becomes a negative bias with respect to (eV) -Vb (eV)
And -Ve (eV) are applied, the chamber 1
The electrons flying upward and downward in the inner space are repelled in the vicinity of the electron shield electrode 18 and the ion acceleration electrode 20, and pushed back toward the generation region of the magnetic neutral wire discharge plasma 13. Among these electrons, the electrons that have reached the generation region of the magnetic neutral line discharge plasma 13 contribute to the promotion of ionization of the introduced gas by the action of the electric field and the magnetic field formed in this generation region, that is, electron-neutral. The frequency of atom collision increases, and the amount of ions generated in the magnetic neutral line discharge plasma 13 increases. As a result, the amount of plasma in the chamber 1 is abundant as compared with the conventional dry etching device (the dry etching device of FIG. 3) in which the electron shielding electrodes 14 and 15 are not built in the chamber 1.

Further, in this embodiment, the potential −Ve (eV), which is a negative bias with respect to the plasma potential Vp (eV), is applied to the ion accelerating electrode 20. Reach 11 That is, when a potential of −Ve (eV) is applied to the ion acceleration electrode 20, the ions (positive ions) are accelerated by the potential difference of Vp + Ve (eV).

In this embodiment, the chamber 1 has a structure shown in FIG.
Since it is possible to generate abundant plasma as compared with the conventional dry etching apparatus shown in (1), it is possible to obtain a larger amount of ions, which enables high-speed etching. Further, since ions having a good directivity can be obtained, it becomes possible to make the incidence of ions on the substrate 11 uniform and prevent variations in processing.

In this embodiment, since the ions are obtained from the magnetic neutral line discharge plasma 13 by the ion accelerating electrode 20, the high frequency power source 12 used in FIG. 1 can be omitted depending on circumstances. Further, in this embodiment, DC power supplies 19 and 21 are connected to the electron shielding electrode 18 and the ion accelerating electrode 20, and the potentials −Vb and −V are obtained.
Although e is applied, the DC power supplies 19 and 21 may be omitted and may be grounded in some cases.

Further, in this embodiment, one mesh-shaped electrode is used as the ion accelerating electrode 20, but two or three electrodes used in various ion sources may be similarly mounted. it can. Further, in this embodiment, since the ions are uniformly incident on the substrate 11, the substrate stage 10
If is arranged diagonally to the incident angle of ions,
It is possible to realize diagonal processing and three-dimensional processing.

[0026]

As is apparent from the above description, according to the present invention, in the first invention, the plasma is provided above the magnetic neutral line discharge plasma and at the intermediate position between the magnetic neutral line discharge plasma and the substrate. Since an electron shield electrode with a negative bias applied to the potential is provided, the electrons that diffuse from the magnetic neutral line discharge plasma and fly up and down in the space inside the chamber are attracted by the electron shield electrode. Electrons that have been pushed back toward the generation region of the discharge plasma and have reached the generation region of the magnetic neutral line discharge plasma among these electrons are due to the action of the electric field and magnetic field formed in this generation region. It contributes to the promotion of ionization of the introduced gas and increases the amount of ions generated in the magnetic neutral line discharge plasma.
As a result, the amount of plasma in the chamber becomes abundant, the amount of plasma moving toward the substrate increases, and the etching process can be performed at high speed.

According to the second aspect of the invention, an electron shield electrode to which a negative bias with respect to the plasma potential is applied is provided above the magnetic neutral line discharge plasma, and the magnetic neutral line discharge plasma and the substrate are provided. An ion accelerating electrode applied with a potential that is a negative bias with respect to the plasma potential is provided at an intermediate position of, so that electrons that diffuse from the magnetic neutral discharge plasma and fly up and down in the space in the chamber are
The electron shield electrode and the ion accelerating electrode push the magnetic neutral line discharge plasma back toward the generation region, while
Ions (positive ions) are accelerated by the potential difference between the ion accelerating electrode and the plasma potential, and ions having a good directivity reach the substrate, so that the etching process can be performed at high speed and the ions are incident on the substrate. It becomes possible to make uniform and to have uniformity in processing.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a dry etching apparatus showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a dry etching apparatus showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional dry etching apparatus using magnetic neutral line discharge plasma.

[Explanation of symbols]

1 ... chamber (cylindrical chamber for plasma generation), 2,
3, 4 ... Magnetic field generating coil, 5 ... High frequency coil, 6 ... High frequency power source, 7 ... Process gas inlet, 8 ... Vacuum exhaust port, 9
... vacuum pump, 10 ... substrate stage, 11 ... substrate, 12
… High frequency power supply, 13… Magnetic neutral line discharge plasma, 14,
15, 18 ... Electron shield electrodes, 16, 17, 19, 21 ...
DC power supply, 20 ... Ion acceleration electrode.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Taijiro Uchida 2500 Hagizono, Chigasaki City, Kanagawa Japan Vacuum Technology Co., Ltd.

Claims (2)

[Claims] 1. A plasma generating chamber made of a dielectric material, first to third magnetic field generating coils arranged around the outer periphery of the plasma generating chamber, the first magnetic field generating coil and the third magnetic field. A high frequency coil disposed inside the second magnetic field generating coil positioned in the middle of the generating coil and outside the plasma generating chamber;
And a current in the same direction is applied to the second magnetic field generating coil in the second direction.
A reverse current is applied to the magnetic field generating coil, and a high frequency is applied to the high frequency coil to ionize the introduced gas, and the magnetic neutral wire discharge plasma generated in the plasma generating chamber is arranged below. In a dry etching apparatus that performs a dry etching process on the substrate by moving in the direction of the substrate, the magnetic neutral line discharge plasma is positioned above the magnetic neutral line discharge plasma and at an intermediate position between the magnetic neutral line discharge plasma and the substrate. A dry etching apparatus characterized in that an electron shielding electrode is provided to which a negative bias is applied with respect to the plasma potential. 2. A plasma generating chamber made of a dielectric material, first to third magnetic field generating coils arranged around the outer periphery of the plasma generating chamber, the first magnetic field generating coil and the third magnetic field. A high frequency coil disposed inside the second magnetic field generating coil positioned in the middle of the generating coil and outside the plasma generating chamber;
And a current in the same direction is applied to the second magnetic field generating coil in the second direction.
A reverse current is applied to the magnetic field generating coil, and a high frequency is applied to the high frequency coil to ionize the introduced gas, and the magnetic neutral wire discharge plasma generated in the plasma generating chamber is arranged below. In a dry etching apparatus for performing a dry etching process on the substrate by moving it toward the existing substrate, an electron having a negative bias with respect to the plasma potential is applied above the magnetic neutral line discharge plasma. A dry etching, wherein a shield electrode is provided, and an ion acceleration electrode to which a potential that is a negative bias with respect to the plasma potential is applied is provided at an intermediate position between the magnetic neutral line discharge plasma and the substrate. apparatus.