JPH05343197A - Plasma equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To form an electron beam excited plasma in a sheet shape and to make the plasma density uniform and improve the processing accuracy. A magnetic field forming means 25 for compressing and transferring the electrons into a flat shape is provided in the processing chamber 3 irradiated with the electrons drawn from the plasma by the electron accelerating means 22, and faces the magnetic field forming means 25. Magnetic field focusing means 2 on the terminal side of the processing chamber
6 is provided. The magnetic field forming means 25 is replaced with the electron accelerating means 22.
It is composed of a pair of permanent magnets 25a and 25b for compressing the electrons drawn in by a flat shape and a solenoid coil 25c for transferring the flattened electrons along the flat surface. The magnetic field focusing means 26 includes a magnetic field focusing magnet 26 a and the magnet 26.
It is composed of the electron guiding electrode 26b arranged on the magnetic field focusing surface side of a. Thereby, the area of the sheet-shaped plasma excited by the irradiation of the reaction gas with electrons can be increased, the plasma of the sheet-shaped plasma can be made uniform with high density, and the processing accuracy can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma device using an electron beam excited plasma.

[0002]

2. Description of the Related Art With recent advances in performance and miniaturization of semiconductor devices, fine processing is required also in plasma processing of objects to be processed such as semiconductor wafers, so that the degree of vacuum in the vacuum processing chamber can be further reduced. There is a growing need for more efficient plasma conversion of the reaction gas in the above state. As one of the plasma treatments, electrons are extracted from plasma, accelerated and irradiated to turn a predetermined reaction gas into plasma,
An electron beam excitation type plasma device for treating an object with this plasma is known, and the applicants have already tried to develop a plasma device of this type.

That is, the one disclosed in Japanese Patent Laid-Open No. 1-105539 discloses an electron beam plasma apparatus,
An example of using a deflection electrode to diffuse an electron beam is described. Further, Japanese Patent Application Laid-Open No. 1-105540 discloses an example of an electron beam plasma apparatus in which a magnetic field canceling means is provided to diffuse an electron beam. Further, Japanese Patent Application Laid-Open No. 63-190299 describes an example of fixing an electrode pair via a spacer in an electron beam plasma apparatus. Also,
Japanese Patent Laid-Open No. 64-53422 discloses a second plasma means for converting an etching gas into plasma by the first plasma in an electron beam plasma apparatus.

This plasma device, as shown in FIG.
For example, a cathode electrode 2 having an introduction hole 2a for ejecting a discharge gas for plasma generation such as argon (Ar) is provided at one end of a closed container 1 formed of, for example, stainless steel in a cylindrical shape. The wafer holder 4 for holding the semiconductor wafer W, which is the object to be processed, is arranged at the end of the processing chamber 3 on the side opposite to the cathode electrode 2. Further, between the cathode electrode 2 and the wafer holder 4, in order from the cathode electrode 2 side, first and second intermediate electrodes 5, 6 and an anode electrode 7 are coaxially provided with a through hole in the center.
And an electron beam accelerating electrode 9 between the anode electrode 7 and the accelerating space 8. In addition, outside the first and second intermediate electrodes 5 and 6, the anode electrode 7 and the electron beam accelerating electrode 9, outside the closed container 1, annular coils 13 to 16 for forming a magnetic field are arranged. There is. In addition, the intermediate chamber 17 of the discharge region 10 and the acceleration space 8
And the processing chamber 3 are provided with exhaust holes 18, 19 and 20, respectively, and a vacuum pump (not shown) is connected to each of the exhaust holes 18, 19 and 20, and the intermediate chamber 17, the acceleration space 8 and the processing chamber 3 are connected. The inside is maintained at a predetermined vacuum pressure.

With the above-mentioned structure, a discharge voltage V1 is applied between the anode electrode 7 and the cathode electrode 2 to cause discharge, so that plasma is generated in the discharge region 10 containing the cathode electrode 2. Further, when an electron beam acceleration voltage V2 is applied to the acceleration electrode 9, electrons are extracted from the plasma generated in the discharge region 10 and sent to the electron beam acceleration region 11 to accelerate the plasma treatment region 12 (specifically, the plasma treatment region 12). The reaction gas such as chlorine (Cl) or argon (Ar) introduced into the chamber 3) and introduced into the processing chamber 3 through the reaction gas introduction pipe 3a is activated to generate high density plasma. The plasma processing of the semiconductor wafer W can be performed. At this time, a DC voltage V3 is applied to the wafer holder 4, or the wafer holder 4 is floated to attract reactive species in the plasma, that is, reactive gas, ions and electrons to the semiconductor wafer W to improve the etching rate.

Further, in this type of plasma apparatus, prismatic permanent magnets are arranged on both sides of the electron beam introduced into the processing chamber 3 in order to make the plasma density uniform, and the magnetic lines of force of this permanent magnet generate plasma. A method of compressing and expanding to form a flat shape, that is, a sheet shape has also been developed (see JP-A-59-27499).

[0007]

However, in the conventional sheet-shaped plasma generating method, the cylindrical plasma generated by the discharge in the magnetic field is compressed by the pair of rectangular permanent magnets to be expanded to a certain thickness. It is possible to generate a sheet plasma having a surface area and an area, but it is not possible to obtain a uniform sheet-shaped plasma over a wide range, and the plasma density is lowered against the homogenization. It has been difficult to realize highly accurate processing of an object to be processed having a large area such as an LCD substrate or an LCD substrate. This problem is caused by C
The same problem occurs in plasma devices such as VD devices and sputtering devices.

The present invention has been made in view of the above circumstances, and makes it possible to form an electron beam excited plasma in a sheet shape over a wide range and to make the in-plane plasma density uniform to perform highly accurate processing. It is an object of the present invention to provide a plasma device.

[0009]

In order to achieve the above object, the plasma device of the present invention excites a predetermined reaction gas supplied into the processing chamber by extracting and accelerating electrons from plasma to irradiate them. Electron accelerating means for drawing electrons into the processing chamber and a magnetic field for compressing and transferring the electrons drawn in by the electron accelerating means on the premise of a plasma device for converting the plasma into plasma and treating the object with the plasma. And a magnetic field focusing means disposed on the terminal side of the processing chamber facing the magnetic field forming means.
The magnetic field focusing means is composed of a magnetic field focusing magnet and an electron guiding electrode arranged on the magnetic field focusing surface side of the magnet.

In the present invention, the electron accelerating means may have any structure as long as it can draw electrons into the processing chamber, but an annular coil forming a magnetic field for passing at least the anode electrode and the electron beam accelerating electrode. Must be provided.

The magnetic field forming means may have any structure as long as it can compress and transfer the electrons drawn into the processing chamber into a flat shape, but the electrons drawn by the magnetic field forming means are preferably flat. It is better to have a pair of permanent magnets facing each other for compression and a solenoid coil for transferring the flattened electrons along the flat surface. In this case, the pair of permanent magnets that compress the electrons into a flat shape have the same pole (N
It can be formed by a rectangular permanent magnet that serves as a pole. Also, the solenoid coil may be single,
It is preferable to have a plurality of coils arranged in parallel in the electron transfer direction because electrons can be transferred over a long distance.

Further, the magnetic field focusing magnet of the magnetic field focusing means is arranged at the end side of the processing chamber so as to focus the end side of the plasma compressed flatly by the magnetic field forming means inside the processing chamber. Although any magnet may be used, it is preferable to use a rectangular permanent magnet having a pole opposite to the pole on the facing surface of the permanent magnet of the magnetic field forming means.

In addition, the electron inducing electrode has a constant potential as long as it is capable of efficiently injecting the electrons drawn into the processing chamber by the electron accelerating means into the flat sheet-like plasma region. However, it is preferable that the potential is variable.

[0014]

According to the plasma apparatus of the present invention constructed as described above, electrons are drawn from the plasma into the processing chamber by the electron accelerating means, and the drawn electrons are generated by the magnetic fields of the pair of permanent magnets of the magnetic field forming means. After being compressed into a flat shape, it is transferred in the direction along the flat surface along the lines of magnetic force formed by the solenoid coil, focused by the magnet of the magnetic field focusing means, and formed into a sheet by the potential of the electrode for electron induction. Further, the amount of electrons in the plasma region is increased and a stable plasma region is formed.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. Here, in the case where the plasma device of the present invention is applied to a plasma etching device, the same parts as those of the conventional plasma device shown in FIG.

FIG. 1 is a schematic sectional view of an example of the plasma apparatus of the present invention, FIG. 2 is a schematic plan view of electron accelerating means, magnetic field forming means and magnetic field focusing means of the present invention, and FIG. 3 is a side view of FIG. Has been done.

The plasma apparatus of the present invention has plasma generating means 21 for converting discharge gas into plasma, electron accelerating means 22 for extracting electrons from the plasma and accelerating the extracted electrons, and accelerating by the electron accelerating means 22. The main part is constituted by the plasma processing means 23 which performs plasma processing by converting the reaction gas into plasma by the irradiation of the generated electrons.

In this case, the plasma generating means 21 supplies a discharge gas for plasma generation such as argon (Ar) to one end of the closed container 1 which is a device body formed in a cylindrical shape from stainless steel or the like. A cathode electrode 2 having a jetting introduction hole 2a, an anode electrode 7 arranged in an intermediate portion of the closed container 1, and first and second intermediate electrodes arranged between the anode electrode 7 and the cathode electrode 2. It is composed of 5 and 6. Further, an intermediate chamber 17 is formed between the second intermediate electrode 6 and the anode electrode 7, and the intermediate chamber 17 is formed.
A vacuum pump (not shown) is connected to an exhaust hole 18 provided in the lower part of the intermediate chamber 17 via an opening / closing valve 18a to maintain the inside of the intermediate chamber 17 at a predetermined degree of vacuum.

A discharge region 10 is between the cathode electrode 2 and the anode electrode 7. Also, the first and second
A closed container 1 outside the intermediate electrodes 5 and 6 and the anode electrode 7 of
The coils 13 to 15 each formed in an annular shape for forming a magnetic field are arranged outside the coil.

The electron accelerating means 22 draws out the electrons from the plasma in the discharge region 10 and the accelerating space 8 in which the electrons drawn from the plasma are transferred.
An electron beam accelerating electrode 22a (hereinafter referred to as an accelerating electrode) for accelerating the electrons in the plasma processing means 23 and introducing it into the processing chamber 3 of the plasma processing means 23, and a ring for forming a magnetic field arranged outside the accelerating electrode 22a It is composed of a coil 22b.
In this case, the inner diameter of the annular coil 22b is set to about 50 mm, and a current of 8 A to 15 A is applied. Further, a vacuum pump (not shown) is connected to an exhaust hole 19 provided in the lower portion of the acceleration space 8 via an opening / closing valve 19a so that the inside of the acceleration space 8 is maintained at a predetermined vacuum pressure. In addition,
The electron acceleration region 11 is between the anode electrode 7 and the acceleration electrode 22a.

On the other hand, the plasma processing means 23 activates the reaction gas by introducing the electrons accelerated by the accelerating electrode 22a of the electron accelerating means 22 and the annular coil 22b and the reaction gas such as Cl gas or Ar gas. A processing chamber 3 and an object to be processed, such as a semiconductor wafer W, which is disposed in the processing chamber 3.
A susceptor 24 for holding the electron horizontally, a magnetic field forming means 25 arranged on the electron accelerating means side for compressing and transferring the electrons drawn from the electron accelerating means 22 into a flat shape, and a magnetic field forming means 2
The magnetic field focusing means 26 arranged on the wall side of the processing chamber facing the No. 5
It consists of and.

In this case, the magnetic field forming means 25 has a pair of rectangular permanent magnets 25a, 25b having a rectangular cross section with N poles facing each other so as to compress the cylindrical electron beam drawn from the electron accelerating means 22. And a plurality of solenoid coils 25c (two are shown in the drawing) for transferring the flattened plasma having electrons along the plane. 25d is a cylindrical chamber. Further, the magnetic field focusing means 26 is the permanent magnet 25 of the magnetic field forming means 25.
a and 25b are opposite poles (N poles) and opposite poles (S poles).
(A pole) is formed of a rod-shaped permanent magnet 26a having a rectangular cross section disposed toward the inside of the processing chamber, and a non-magnetic material such as stainless steel disposed so as to cover the magnetic field focusing surface side of the permanent magnet 26a. And a plate-shaped electron guiding electrode 26b. In this case, the permanent magnets 25a and 25b of the magnetic field forming means 25 have a length of 160 mm and the surface magnetic field is about 1 mm.
~ 1.2 KG, magnetic field focusing permanent magnet 26a
Has a length of 260 mm, the surface magnetic field is set to 1 to 1.2 KG, the solenoid coil 25c is set to a length of about 30 cm, and a current of 3 A (ampere) is applied. Further, a power source 26c is connected to the electron guiding electrode 26b so that a potential of -100V to + 50V can be applied. The magnetic field forming means 25 and the magnetic field focusing permanent magnet 2
A plasma processing region 12 is between 6 and 6.

Therefore, the annular coil 22b of the electron accelerating means 22 and the permanent magnets 25a, 25 of the magnetic field forming means 25 are used.
b, solenoid coil 25c, and magnetic field focusing permanent magnet 2
Since the magnetic field configuration formed by the magnetic lines of force 6 forms the magnetic field G as shown in FIGS. 2 and 3, the electrons drawn into the processing chamber by the accelerating electrode 22a and the annular coil 22b of the electron accelerating means 22 are After being flatly compressed by the pair of permanent magnets 25a and 25b of the magnetic field forming means 25,
The magnetic field is formed by the solenoid coil 25c and is transferred in the direction along the flat surface and focused by the magnetic field focusing permanent magnet 26 to form a sheet-like plasma region near the susceptor 24 (FIG. 4). reference). At this time, the amount of electrons drawn into the plasma region is increased by changing the potential of the electron inducing electrode 26b, and the outside of the sheet plasma region, that is, the outside of the sheet plasma region and the magnetic field focusing permanent magnet 26a. It is possible to suppress the plasma from wrapping around to the rear wall side.

The susceptor 24 is connected to a high frequency power supply RF for drawing the reactive species (reactive gas, ions and electrons) in the excited plasma to the semiconductor wafer W side. The bias voltage of this high-frequency power supply RF is several MHz
Dozens of MHz (specifically 2-3 MHz-13.56 MH
z). The susceptor 24 is provided with a clamp ring 24b for fixing and holding the semiconductor wafer W around the upper surface side of a susceptor body 24a made of, for example, stainless steel, and ethylene glycol and water are provided in a coolant channel 24c provided in the susceptor body 24a. The supply pipe 27a and the discharge pipe 27b of the mixed refrigerant are connected to each other, and further, He gas or N2 gas is supplied / discharged to / from a backside gas reservoir (not shown) provided on the mounting surface side of the semiconductor wafer W. A pipe 28 is connected.

Next, the operation of the plasma device of the present invention configured as described above will be described. First, the discharge gas is introduced through the discharge gas introduction hole 2a, and the cathode electrode 2
Between the cathode electrode and the first and second intermediate electrodes 5, 6 and the anode electrode 7 in a state in which the pressure between the first intermediate electrode 5 and the first intermediate electrode 5 is exhausted to, for example, about 1.0 Torr. When a discharge voltage V1 is applied to generate a glow discharge, plasma is generated in the discharge region 10. In this case, the first and second intermediate electrodes 5 and 6 are for facilitating glow discharge at a low voltage. First, glow discharge occurs between the cathode electrode 2 and the first intermediate electrode 5. Then, the transition is made to the second intermediate electrode 6 and the anode electrode 7. After stable glow discharge is formed between the cathode electrode 2 and the anode electrode 7, the switches S1 and S2 are turned off.

The electrons in the plasma generated as described above are extracted into the accelerating space 8 by the application of the accelerating voltage V2 to the accelerating electrode 22a and are accelerated by the magnetic lines of force formed by the annular coil 22b. Transferred in. The electrons drawn into the processing chamber 3 are flatly compressed by the pair of permanent magnets 25a and 25b of the magnetic field forming means 25, and then transferred along the flat plane by the magnetic lines of force formed by the solenoid coil 25c. The end is focused by the magnetic field focusing permanent magnet 26a. In this state, the electrons excite the reaction gas Cl or Ar supplied into the processing chamber 3 to generate plasma, and the sheet-like plasma is formed at a position near the susceptor 24 and the semiconductor wafer W. At this time, the amount of electrons drawn into the plasma region is increased by changing the potential of the electron inducing electrode 26b, and at the same time, outside the sheet plasma region, that is, outside the sheet plasma region and the magnetic field focusing permanent magnet 2.
The wraparound of the plasma to the rear wall side of 6a is suppressed, and the plasma density is increased. And susceptor 2
Reactive species, that is, reactive gas, ions, and electrons are extracted from the sheet-shaped plasma region by the high-frequency voltage applied to 4, and these reactive species are accelerated in the plasma sheath on the surface of the semiconductor wafer W and collide as an ion beam. The semiconductor wafer W is etched.

In the plasma etching apparatus having the above structure, a comparative experiment was conducted between the case where the electron guiding electrode 26b was floated (comparative example) and the case where a potential was applied to the electron guiding electrode 26b (example). However, the following results were obtained.

Experimental conditions-Semiconductor wafer W: Poly-Si-Reactive gas: Ar-Circular coil 22b: 8A-Solenoid coil 25c: 3A-Electron induction electrode of the comparative example: Floating-Electron induction electrode 26b of the example: 0V (Grounding on the wall surface of the processing chamber 3) As a result of conducting an experiment under the above conditions, in the comparative example, the electron uptake amount was 3.8 A, the average etching rate was 13.2 angstrom / min (min). However, in the example, the electron uptake amount = 5.3 to 5.5 A, the average etching rate = 32.3 Angstrom / min (min)
Therefore, the electron amount can be increased about 1.4 times, and the average etching rate can be about 2.
A four-fold increase was achieved.

In the above embodiment, the case where the plasma apparatus of the present invention is applied to the plasma etching apparatus has been described.
It is needless to say that the present invention can be applied to other electron beam excitation type plasma apparatus such as an apparatus and a sputtering apparatus. Further, in the above embodiment, the case where the object to be processed is a semiconductor wafer has been described, but the object to be processed is not limited to the semiconductor wafer, and, for example, an LCD substrate or the like can be processed in the same manner.

[0030]

As described above, according to the plasma device of the present invention, which is configured as described above, the following effects can be obtained.

1) According to the plasma device of the first aspect, the electrons attracted by the electron accelerating means are compressed and transferred by the magnetic field forming means into a flat shape, and the end portions of the electrons are focused by the magnetic field focusing means. At the same time, since electrons can be effectively taken in by the potential of the electrode for electron induction, it is possible to generate a uniform and high-density sheet-shaped plasma in the radial direction of the object to be processed, and to improve the processing accuracy. You can

2) According to another aspect of the plasma device of the present invention, the magnetic field forming means has a pair of permanent magnets facing each other to compress the electrons drawn by the electron accelerating means into a flat shape, and the flattened electrons. Since it is composed of a solenoid coil that moves along a plane, it is possible to generate a sheet-shaped plasma having a uniform density in the radial direction of the object to be processed over a large area, and perform plasma processing of a large object to be processed. You can

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a plasma device of the present invention.

FIG. 2 is a schematic plan view showing an electron accelerating means, a magnetic field forming means and a magnetic field focusing means in the present invention.

FIG. 3 is a side sectional view of FIG.

FIG. 4 is a schematic perspective view showing a generation state of a sheet-shaped plasma region by the plasma device of the present invention.

FIG. 5 is a schematic sectional view showing a conventional plasma device.

[Explanation of symbols]

 22 electron accelerating means 22a electron beam accelerating electrode 22b annular coil 25 magnetic field forming means 25a, 25b permanent magnet 25c solenoid coil 26 magnetic field focusing means 26a magnetic field focusing permanent magnet 26b electron induction electrode 26c power source

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01L 21/302 B 8518-4M (72) Inventor Gensuke Miyoshi 72 Horikawa-cho, Kawasaki-shi, Kanagawa Prefecture Address Stock Company, Toshiba Horikawa-cho Factory (72) Inventor Haruo Okano 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Corporate Research Institute, Toshiba Research Institute (72) Inventor Katsuya Okumura Komukai, Kawasaki-shi, Kanagawa Prefecture Toshiba Town No. 1 Inside the Tama River Factory of Toshiba Corporation

Claims (2)

[Claims] 1. A plasma apparatus for extracting an electron from plasma and accelerating and irradiating the electron to excite a predetermined reaction gas supplied into the processing chamber into plasma, and processing the object to be processed by the plasma. An electron accelerating means for drawing electrons into the processing chamber, a magnetic field forming means for compressing and transferring the electrons drawn by the electron accelerating means into a flat shape, and a magnetic field forming means facing the magnetic field forming means are disposed on the end side of the processing chamber. A plasma apparatus comprising: a magnetic field focusing means, wherein the magnetic field focusing means comprises a magnetic field focusing magnet and an electron guiding electrode disposed on the magnetic field focusing surface side of the magnet. 2. The magnetic field forming means comprises a pair of permanent magnets facing each other so as to compress the electrons drawn by the electron accelerating means into a flat shape, and a solenoid coil for transferring the flattened electrons along the flat surface. The plasma device according to claim 1, wherein