JP3236928B2 - Dry etching equipment - Google Patents

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 for performing dry etching using magnetic neutral discharge plasma.

[0002]

2. Description of the Related Art FIG. 3 shows the configuration of a conventional dry etching apparatus using magnetic neutral beam discharge plasma. In FIG. 1, reference numeral 1 denotes a quartz plasma-generating cylindrical chamber (hereinafter, referred to as a cylindrical chamber).
2, 3, and 4 are first, second, and third magnetic field generating coils arranged in a vertical direction around the outer periphery of the chamber 1, and 5 are 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 generating coil 3 and at an outer periphery of the chamber 1 at an intermediate position with respect to the magnetic field generating coil 4; 6, a high-frequency power supply for applying a high frequency to the high-frequency coil 5; Inlet, 8 is vacuum exhaust, 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 supply for applying a high frequency to the substrate stage 10.

In this dry etching apparatus, first, the inside of the chamber 1 is evacuated to a high vacuum using a vacuum pump 9. Then, a process gas is introduced into the chamber 1 from the gas inlet 7 and kept at about 10 ^-1 to 10 ^-2 Pa. After such a state, currents of the same magnitude are applied to the magnetic field generating coils 2 and 4 in the same direction. Then, "Literature: Jpn.J.
As described in Appl. Phys. Vol. 33 (1994) pp. L43-L44, an annular magnetic neutral line at which the magnetic field intensity becomes zero is formed at an intermediate position between the magnetic field generating coils 2 and 4. Is done.

Next, when a current having a direction opposite to the current flowing through the magnetic field generating coils 2 and 4 is passed through the magnetic field generating coil 3, this magnetic neutral ray is spatially separated into two, one of which is in 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 source 6, an electric field (high-frequency electric field) is formed along the magnetic neutral line formed in the chamber 1. As a result, electrons in the vicinity including the magnetic neutral line 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). A plasma (magnetic neutral discharge plasma) 13 composed of electrons and ions is formed in a nearby space including the magnetic neutral line. These electrons and ions move toward the inner wall of the chamber 1, but mainly move and diffuse in the vertical direction because the magnetic lines of force are directed in the vertical direction.

Next, a high frequency power supply 12 is
When a high-frequency electric field is applied by using the magnetic field-generating coils 13, the magnetic field generated by the magnetic field generating coils 2, 3, 4 and the substrate Ions and electrons that move in the direction of the substrate stage 10 due to the formed electric field collide with the substrate 11. Accordingly, when the process gas introduced into the chamber 1 is an inert gas, the sputter etching proceeds on the substrate 11, and when the process gas is a reactive gas, the reactive etching proceeds on the substrate 11. .

[0006] This dry etching apparatus has a feature that plasma can be easily generated in a pressure range of 10 ^-1 Pa or less where discharge is not easily generated. this is,
The existence of a kind of magnetic well with a closed curve with zero magnetic field strength,
This is due to the effect that the scattered electrons stay at the place and contain many kinds of discharge.

[0007]

However, in such a dry etching apparatus, a part of the introduced gas is continuously ionized on the magnetic neutral line and its vicinity by the high-frequency induction electric field to form plasma. In addition, the main components of the ions are diffused in the vertical direction under the influence of the electrons, since the electrons easily move along the magnetic field. Therefore, if it is left as it is, it is merely a spatial diffusion in the vertical direction, and ionization due to collision between the electrons and the introduced gas cannot be performed more efficiently.

[0008] In addition, ions that are the main players in the etching reaction also cannot be effectively diffused into the substrate 11 only by free diffusion of ions that move downward together with electrons.

An object of the first invention of the present invention is as follows.
Effectively use the electrons diffused from the magnetic neutral discharge plasma for ionizing 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. It is to provide a dry etching apparatus which can be used. It is another object of the present invention to provide a dry etching apparatus capable of aligning the incidence of ions on a substrate and imparting uniformity to processing, in addition to the object of the first invention.

[0010]

In order to achieve the above object, a first invention (the invention according to claim 1) is directed to a position above a magnetic neutral discharge plasma, a magnetic neutral discharge plasma and a substrate. And an electron shielding electrode to which a potential that becomes a negative bias with respect to the plasma potential is applied. According to the present invention, the electrons diffused from the magnetic neutral beam discharge plasma and fly vertically in the space in the chamber are pushed back toward the magnetic neutral line discharge plasma generation region by the electron shielding electrode.

According to a second invention (an invention according to claim 2), an electron shielding electrode to which a potential having a negative bias with respect to the plasma potential is applied is provided above the magnetic neutral wire discharge plasma, An ion accelerating electrode is provided at an intermediate position between the discharge plasma and the substrate, to which a potential having a negative bias with respect to the plasma potential is applied. According to the invention,
Electrons that diffuse from the magnetic neutral discharge plasma and fly upward and downward in the space in the chamber are pushed back toward the magnetic neutral discharge plasma generation region 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
Is accelerated, and ions with good directivity are obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 shielding electrode 14 is provided at a position above the magnetic neutral discharge plasma 13, and an electron shielding electrode 15 is provided at an intermediate position between the magnetic neutral discharge plasma 13 and the substrate 11.
DC power supplies 16 and 17 are connected to 4 and 15 so that a potential -Vb (eV) which becomes a negative bias with respect to the plasma potential Vp (eV) is applied (Vp> -V).
b).

In this dry etching apparatus, first, the inside of the chamber 1 is evacuated to a high vacuum using the vacuum pump 9. Then, a process gas is introduced into the chamber 1 from the gas inlet 7 and kept at about 10 ^-1 to 10 ^-2 Pa. After such a state, currents of the same magnitude are applied to the magnetic field generating coils 2 and 4 in the same direction. Then, an annular magnetic neutral line having a magnetic field intensity of zero is formed at an intermediate position between the magnetic field generating coils 2 and 4.

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, this magnetic neutral line is spatially separated into two, 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 source 6, an electric field (high-frequency electric field) is formed along the magnetic neutral line formed in the chamber 1. Thereby, the electrons near the magnetic neutral line 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). A plasma (magnetic neutral 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 through the magnetic neutral discharge plasma 13, the plasma (ions, electrons) is generated, overflows, and diffuses to the surroundings. In the plasma, electrons have much lower mass than electrons, so that the temperature (electron temperature) is extremely high, and the frequency of collision between particles is low. For this reason, the electrons in the magnetic neutral beam discharge plasma 13 are widely diffused in the vertical direction along the vertical magnetic field generated by the magnetic field generating coils 2, 3, 4.

In this embodiment, since the potential -Vb (eV) which becomes a negative bias with respect to the plasma potential Vp (eV) is applied to the electron shielding electrodes 14 and 15, Electrons that fly up and down the space are rebounded in the vicinity of the electron shielding electrodes 14 and 15 and are pushed back toward the generation region of the magnetic neutral discharge plasma 13. Among these electrons, those that have reached the region where the magnetic neutral discharge plasma 13 is generated contribute to the promotion of ionization of the introduced gas by the action of the electric field and magnetic field formed in this region, that is, electron-neutral. The frequency of atomic collisions increases, and the amount of ions generated in the magnetic neutral discharge plasma 13 increases. As a result, the amount of plasma in the chamber 1 is increased as compared with a conventional dry etching apparatus in which the electron shielding electrodes 14 and 15 are not built in the chamber 1 (the dry etching apparatus in FIG. 3). In the magnetic neutral beam discharge plasma 13, ions are also generated by ion-neutral atom collision, but the ionization efficiency is lower than that of electron-neutral atom collision. Therefore, it is advisable to use the electrons in the plasma effectively. In this embodiment, based on such a concept, attention is paid to the behavior of the electrons in the plasma, and the electrons diffused from the magnetic neutral discharge plasma 13. They try to push back the coming electrons.

In this state, the substrate stage 10
When a high-frequency electric field is applied to the substrate by using a high-frequency power supply 12, the magnetic field formed by the magnetic field generating coils 2, 3, and 4 among the ions and electrons in the magnetic neutral discharge plasma 13 formed in the chamber 1 and the substrate Ions that move toward the substrate stage 10 due to the electric field formed on the stage 10 collide with the substrate 11. Accordingly, when the process gas introduced into the chamber 1 is an inert gas, sputter etching proceeds on the substrate 11,
When a reactive 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 increases, so that high-speed etching can be performed.

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

[Second Embodiment: Second Invention] FIG. 2 is a configuration 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 shielding electrode 18 is provided above the magnetic neutral ray discharge plasma 13, a DC power supply 19 is connected to the electron shielding electrode 18, and a negative bias is applied to the plasma potential Vp (eV). The following potential -Vb (eV) is applied (Vp> -Vb). A mesh-like ion accelerating electrode 20 is provided at an intermediate position between the magnetic neutral discharge plasma 13 and the substrate 11.
The DC power supply 21 is connected to apply a potential -Ve (eV) which becomes a negative bias with respect to the plasma potential Vp (eV) (Vp> -Ve).

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

In this embodiment, the plasma potential Vp is applied to the electron shielding electrode 18 and the ion accelerating electrode 20.
Potential −Vb (eV) that becomes a negative bias with respect to (eV)
And -Ve (eV) are applied, the chamber 1
Electrons that fly upward and downward in the internal space are bounced back near the electron shielding electrode 18 and the ion accelerating electrode 20 and are pushed back toward the region where the magnetic neutral discharge plasma 13 is generated. Among these electrons, the electrons that have reached the generation region of the magnetic neutral discharge plasma 13 contribute to the promotion of ionization of the introduced gas by the action of the electric field and magnetic field formed in this generation region. The frequency of atomic collisions increases, and the amount of ions generated in the magnetic neutral discharge plasma 13 increases. As a result, the amount of plasma in the chamber 1 is increased as compared with a conventional dry etching apparatus in which the electron shielding electrodes 14 and 15 are not built in the chamber 1 (the dry etching apparatus in FIG. 3).

In this embodiment, since the potential -Ve (eV) which becomes a negative bias with respect to the plasma potential Vp (eV) is applied to the ion accelerating electrode 20, ions having good directivity are deposited on the substrate. Reach 11. That is, when a potential of −Ve (eV) is applied to the ion acceleration electrode 20, ions (positive ions) are accelerated by a potential difference of Vp + Ve (eV).

In this embodiment, FIG.
Since a richer plasma can be generated as compared with the conventional dry etching apparatus shown in (1), a larger amount of ions can be obtained as a result, thereby enabling high-speed etching. In addition, since ions having good directivity can be obtained, the incidence of ions on the substrate 11 can be uniformed, and variations in processing can be prevented.

In this embodiment, since ions are obtained from the magnetic neutral discharge plasma 13 by the ion acceleration electrode 20, the high frequency power supply 12 used in FIG. 1 can be omitted in some cases. In this embodiment, DC power supplies 19 and 21 are connected to the electron shielding electrode 18 and the ion accelerating electrode 20 so that the potentials -Vb and -V
Although e is applied, the DC power supplies 19 and 21 may be omitted and the ground potential may be applied in some cases.

In this embodiment, a single mesh 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 incidence of ions on the substrate 11 is uniform, the substrate stage 10
Is placed obliquely to the angle of incidence of the ions,
Oblique processing and three-dimensional processing can be realized.

[0026]

As is apparent from the above description, according to the present invention, in the first invention, the plasma is located at a position above the magnetic neutral discharge plasma and at an intermediate position between the magnetic neutral discharge plasma and the substrate. Since an electron shielding electrode to which a potential that is negatively biased with respect to the potential is applied is provided, electrons that diffuse from the magnetic neutral discharge plasma and fly up and down the space in the chamber are subjected to magnetic neutral radiation by the electron shielding electrode. These electrons are pushed back toward the discharge plasma generation region, and among these electrons, the electrons reaching the magnetic neutral discharge plasma generation region are acted upon by the electric and magnetic fields formed in this generation region. This contributes to promoting the ionization of the introduced gas, and increases the amount of ions generated in the magnetic neutral 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 present invention, an electron shielding electrode to which a potential having a negative bias with respect to the plasma potential is applied is provided above the magnetic neutral wire 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, so that electrons that diffuse from the magnetic neutral discharge plasma and fly upward and downward in the space in the chamber are:
The electron shielding electrode and the ion accelerating electrode are pushed back toward the magnetic neutral discharge plasma generation region, while
The ions (positive ions) are accelerated by the potential difference between the ion accelerating electrode and the plasma potential, and ions having good directivity reach the substrate, so that the etching process can be performed at a high speed and the ions are incident on the substrate. And the processing can be made uniform.

[Brief description of the drawings]

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

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

FIG. 3 is a configuration diagram of a conventional dry etching apparatus using magnetic neutral beam 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 supply, 7 ... process gas inlet, 8 ... vacuum exhaust port, 9
... Vacuum pump, 10 ... Substrate stage, 11 ... Substrate, 12
... High frequency power supply, 13 ... Magnetic neutral discharge plasma, 14,
15, 18 ... electron shielding electrodes, 16, 17, 19, 21 ...
DC power supply, 20 ... Ion acceleration electrode.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Daijiro Uchida 2500 Hagizono, Hagizono, Chigasaki City, Kanagawa Prefecture, Japan Inside of Vacuum Engineering Co., Ltd. (56) References JP-A 9-22796 (JP, A) JP-A 63- 156535 (JP, A) JP-A-63-213345 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23F 4/00 H01L 21/3065 H05H 1/46

Claims (2)

(57) [Claims] 1. A plasma generating chamber made of a dielectric material, first to third magnetic field generating coils arranged around the plasma generating chamber, a first magnetic field generating coil and a third magnetic field A high-frequency coil disposed inside a second magnetic field generating coil located at an intermediate position between the generating coil and the outer periphery of the plasma generation chamber;
And a current in the same direction to the third magnetic field generating coil
A current in the opposite direction is applied to the magnetic field generating coil, and the introduced gas is ionized by applying a high frequency to the high frequency coil, and the magnetic neutral discharge plasma generated in the plasma generating chamber is disposed below. A dry etching apparatus for performing a dry etching process on the substrate by moving in a direction toward the substrate, wherein the substrate is located at a position above the magnetic neutral discharge plasma and at an intermediate position between the magnetic neutral discharge plasma and the substrate. A dry etching apparatus, comprising: an electron shielding electrode to which a potential having a negative bias with respect to a plasma potential is applied. 2. A plasma generating chamber made of a dielectric material, first to third magnetic field generating coils disposed around the plasma generating chamber, a first magnetic field generating coil and a third magnetic field. A high-frequency coil disposed inside a second magnetic field generating coil located at an intermediate position between the generating coil and the outer periphery of the plasma generation chamber;
And a current in the same direction to the third magnetic field generating coil
A current in the opposite direction is applied to the magnetic field generating coil, and the introduced gas is ionized by applying a high frequency to the high frequency coil, and the magnetic neutral discharge plasma generated in the plasma generating chamber is disposed below. In a dry etching apparatus that performs dry etching processing on the substrate by moving in the direction of the substrate, electrons having a negative potential with respect to the plasma potential applied to a position above the magnetic neutral discharge plasma. Dry etching, wherein a shielding electrode is provided, and an ion accelerating electrode to which a potential having a negative bias with respect to the plasma potential is applied is provided at an intermediate position between the magnetic neutral discharge plasma and the substrate. apparatus.