JPH05343196A - Plasma device - Google Patents

Abstract

PURPOSE:To form an electron beam exciting plasma into a sheet, uniform plasma density, and improve processing precision. CONSTITUTION:A magnetic field forming means 25 for flatly compressing and transferring electrons is arranged in a processing chamber 3 to which the electrons drawn from a plasma is emitted by the accelerating electrode 22a and ring coil 22b of an electron accelerating means 22, and a magnetic field focusing means 26 is arranged on the processing chamber terminal end side opposed to the magnetic field forming means 25. The magnetic field forming means 25 is formed of a pair of permanent magnets 25a, 25b for flatly compressing the electrons drawn by the electron accelerating means 22 and a solenoid coil for transferring the flattened electrons along a flat surface. Thus, the area of the sheet plasma excited by the emission of electrons to a reaction gas can be increased, and the uniforming in plasma density and improvement in processing precision of the sheet plasma can attained.

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,
Techniques for diffusing an electron beam using deflecting electrodes have been shown. Further, Japanese Patent Application Laid-Open No. 1-105540 discloses a technique of diffusing an electron beam by providing a magnetic field canceling means in an electron beam plasma device. Further, Japanese Patent Application Laid-Open No. 63-190299 discloses a technique of fixing an electrode pair via a spacer in an electron beam plasma device. Also,
Japanese Unexamined Patent Publication No. 64-53422 discloses a technique relating to 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 large area and an area, but it is not possible to obtain a uniform sheet plasma over a wide range, and for example, an object to be processed having a large area such as a semiconductor wafer or an LCD substrate. However, it was difficult to realize. This problem is related to CV
The same problem occurs in plasma devices such as D 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. It is provided with a forming means and a magnetic field converging means arranged on the end side of the processing chamber facing the magnetic field forming means.

In the present invention, the electron accelerating means may have any structure as long as it can draw electrons into the processing chamber, but it is required to have at least an annular coil for forming a magnetic field.

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.

The magnetic field focusing means is arranged on the terminal side of the processing chamber to focus the plasma compressed flatly by the magnetic field forming means on the terminal side of the processing chamber. It can be formed by a rectangular permanent magnet having a pole opposite to the pole on the opposite surface.

[0013]

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 magnetic lines of force formed by the solenoid coil and focused by the magnetic field focusing means. Therefore, the electrons drawn into the processing chamber by the electron accelerating means excite the reaction gas supplied into the processing chamber to generate sheet-like plasma.

[0014]

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 a 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 arrow G in the drawing indicates the direction of the magnetic field.

The plasma apparatus according to the present invention includes 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 generating plasma such as argon (Ar) to one end of the closed container 1 which is a main body of the apparatus and is 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 out 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 vacuum pump (not shown) is connected to the exhaust hole 19 provided in the lower portion of the acceleration space 8 via the opening / closing valve 19a so that the inside of the acceleration space 8 is closed. Is maintained at a predetermined vacuum pressure. The anode electrode 7 and the acceleration electrode 22a
An electron acceleration region 11 is located between and.

On the other hand, the plasma processing means 23 introduces electrons accelerated by the acceleration electrode 22a and the annular coil 22b of the electron acceleration means 22 and a reactive gas such as Cl gas or Ar gas to activate the reactive 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 rod-shaped permanent magnets 25a, 25b having N-poles facing each other and 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 a permanent magnet 25a of the magnetic field forming means 25,
The pole (S pole) opposite to the pole (N pole) of the facing surface of 25b is formed by a rod-shaped permanent magnet having a rectangular cross section, which is arranged toward the inside of the processing chamber. In this case, the permanent magnets 25a, 2
5b and the magnetic field focusing permanent magnet 26 have a length of 150 mm, the surface magnetic field is set to about 2 KG, and the solenoid coil 25
The length of c is set to about 30 cm, and the magnetic field near the semiconductor wafer W is set to about 50 G. The plasma processing region 12 is between the magnetic field forming means 25 and the magnetic field focusing permanent magnet 26.

Therefore, the annular coil 22b of the electron accelerating means 22 and the permanent magnets 25a, 25 of the magnetic field forming means 25.
b, solenoid coil 25c, and magnetic field focusing permanent magnet 2
Since the magnetic field configuration formed by each magnetic field line 6 is formed as shown in FIGS. 2 and 3, the electrons drawn into the processing chamber by the accelerating electrode 22a of the electron accelerating means 22 and the annular coil 22b form a magnetic field. After being flatly compressed by the pair of permanent magnets 25a and 25b of the means 25, the permanent magnets 25a and 25b are transferred in the direction along the flat surface along the magnetic lines of force formed by the solenoid coil 25c, and are focused by the magnetic field focusing permanent magnet 26. A sheet-shaped plasma region is formed near the upper portion of the susceptor 24 (see FIG. 4).

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 focusing permanent magnet 26. In this state, electrons are supplied into the processing chamber 3 as a reaction gas Cl or Ar.
Are excited to form plasma, and the sheet-like plasma is formed in a position near the susceptor 24 and the semiconductor wafer W.

Then, the high-frequency voltage applied to the susceptor 24 extracts reactive species, that is, reactive gas, ions and electrons from the sheet-shaped plasma region, and the reactive species are accelerated in the plasma sheath on the surface of the semiconductor wafer W,
The semiconductor wafer W is etched by collision as an ion beam.

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.

[0028]

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 apparatus 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. Therefore, it is possible to generate the sheet-shaped plasma having a uniform density in the radial direction of the object to be processed and to improve the processing accuracy.

2) According to the plasma device of the second aspect, the magnetic field forming means and the pair of permanent magnets facing each other so as to compress the electrons drawn by the electron accelerating means into a flat shape, and the flattened electrons are distributed. 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 permanent magnet (magnetic field focusing means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gensuke Miyoshi 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Horikawa-cho factory (72) Inventor Haruo Okano Komukai-Toshiba, Kawasaki-shi, Kanagawa No. 1 Incorporated company Toshiba Research Institute (72) Inventor Katsuya Okumura No. 1 Komukai Toshiba-cho, Kawasaki-shi, Kanagawa Kanagawa Prefecture Tamagawa factory, Incorporated company

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 device comprising a magnetic field focusing means. 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