JPH05343198A - Plasma device - Google Patents

Abstract

PURPOSE:To form an electron beam exciting plasma into a sheet, enhance plasma density, and improve its uniformity. CONSTITUTION:In a processing chamber 3 to which electrons drawn from a plasma by the accelerating electrode 22a and ring coil 22b of an electron accelerating means 22 are emitted, a magnetic field forming means 25 for branching the electrode, and flatly compressing and transferring the electrons is arranged. 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 25c for transferring the flattened electrodes along a flat surface. Thus, the area of the sheet plasma excited by the emission of electrons to a reaction gas can be increased, the plasma density of the sheet plasma can be enhanced, and its uniformity 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,
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. Although it is possible to generate a sheet plasma having a large area and an area, only a sheet-shaped plasma in which the beam-shaped component at the center of the axis remains can be generated. It is not possible to obtain a uniform sheet-shaped plasma over the range.
It is not suitable for processing a target object having a large area such as a CD substrate, and is difficult to realize. This problem also occurs in plasma devices such as CVD devices and sputtering devices other than the plasma etching device.

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. Assuming a plasma device that converts the plasma into a plasma and treats the object to be processed with the plasma, electron accelerating means for drawing electrons into the processing chamber and the electrons drawn by the electron accelerating means are branched and compressed into a flat shape. And a magnetic field forming means for transferring.

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 branch the electrons drawn into the processing chamber and compress and transfer them into a flat shape, but preferably the electrons drawn from the magnetic field forming means. It is better to be composed of a pair of permanent magnets that face each other and that are compressed to flatten, and a solenoid coil that transports the flattened electrons along the flattened plane. In this case, the pair of permanent magnets that branch the electrons and compress them flatly can be formed by rectangular permanent magnets whose opposing surfaces have the same pole (N pole), and a plurality of pairs are arranged as necessary. It is also possible to do so. Further, the solenoid coil may be single, but it is preferable to have a plurality of coils in parallel in the electron transfer direction because the electrons can be transferred over a long distance.

[0012]

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 branching while maintaining the electron beam component and being compressed into a flat shape, it is transferred in the direction along the flat plane along the magnetic field lines formed by the solenoid coil to excite the reactive gas supplied into the processing chamber. To generate sheet-like plasma.

[0013]

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 the electron accelerating means and magnetic field forming means of the present invention, and FIG. 3 is a side view of FIG. The arrow G in the drawing indicates the direction of the magnetic field.

The plasma apparatus of the present invention uses 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 reactive 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 formed 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 area 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 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 activates the reaction gas by introducing the electrons accelerated by the acceleration electrode 22a of the electron acceleration 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 horizontally holding, and a magnetic field forming means 25 disposed on the electron accelerating means side for branching the electrons drawn from the electron accelerating means 22 and compressing and transferring them in a flat shape.
The magnetic field forming means 25 and the magnetic field focusing means 26 arranged on the wall side of the processing chamber facing the magnetic field forming means 25.

In this case, the magnetic field forming means 25 has a pair of rectangular cross-sections in which the cylindrical electron beam drawn from the electron accelerating means 22 is branched to the left and right and the N poles are opposed to each other in order to compress the electron beam. Permanent magnets 25a, 25b of
It is composed of a plurality of solenoid coils 25c (two are shown in the drawing) for transferring the plasma having flattened electrons along the plane. 25d is a cylindrical chamber. Further, the magnetic field focusing means 26 is provided with the poles (N) of the facing surfaces of the permanent magnets 25a and 25b of the magnetic field forming means 25.
It is formed by a rod-shaped permanent magnet having a rectangular cross section, which is arranged so that the opposite pole (S pole) to the inside of the processing chamber. In this case, the permanent magnets 25a and 25b have a length of 40 mm, the surface magnetic field is set to about 2 KG, the magnetic field focusing permanent magnet 26 is set to a length of 260 mm, the surface magnetic field is set to 2 KG, and the solenoid coil 25c The length is set to about 30 cm, and the magnetic field near the semiconductor wafer W is set to about 50G. 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 are used.
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. The axial component of the electron beam is pushed back by the magnetic force lines of the pair of permanent magnets 25a and 25b of the means 25, branched to the left and right, and compressed into a flat shape, and then a flat surface is formed along the magnetic force lines formed by the solenoid coil 25c. It is transported in the direction along and is focused by the magnetic field focusing permanent magnet 26 to form a sheet-like plasma region at a position near the upper side 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 applying 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 split left and right while maintaining the electron beam component by the pair of permanent magnets 25a and 25b of the magnetic field forming means 25, and are flatly compressed, and then formed by the solenoid coil 25c. The magnetic flux of the magnetic force causes the magnetic flux to move along the plane, and the focusing permanent magnet 26 focuses the end. In this state, the reaction gas Cl or Ar supplied into the processing chamber 3 is excited to generate plasma, and the sheet-like plasma is generated by the susceptor 24.
And at a position near the upper side of 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 these reactive species are accelerated in the plasma sheath on the surface of the semiconductor wafer W,
The semiconductor wafer W is etched by colliding with the accelerated ions.

In the above embodiment, the case where the magnetic field forming means 25 is formed by one set of permanent magnets 25a and 25b has been described, but the magnetic field forming means 25 need not necessarily be only one set of permanent magnets 25a and 25b. Alternatively, one set or a plurality of sets of permanent magnets 25a, 25b can be arranged on the downstream side of the set of permanent magnets 25a, 25b, that is, on the side of the magnetic field converging means. A magnetic field orientation can be formed and the uniformity of the sheet-shaped plasma can be improved.

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 device of the first aspect, since the electrons drawn by the electron accelerating means are branched by the magnetic field forming means and compressed and transferred in a flat shape,
It is possible to generate a sheet-like plasma having a high density and a uniform distribution in the radial direction of the object to be processed, and improve the processing accuracy.

2) According to another aspect of the plasma apparatus, the magnetic field forming means is flattened with a pair of permanent magnets that face each other so as to branch the electrons drawn by the electron accelerating means and compress them flatly. Since it is composed of a solenoid coil that transports electrons along a flat surface, it is possible to generate a sheet-like plasma having a high density and a high density in the radial direction of the object to be processed over a large area, so that a large object can be generated. Plasma treatment of the treatment object can be performed.

[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 and a magnetic field forming 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

─────────────────────────────────────────────────── ─── 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. A plasma apparatus comprising: an electron accelerating means for drawing electrons into the processing chamber; and a magnetic field forming means for branching the electrons drawn by the electron accelerating means and compressing and transferring the flattened electrons. 2. A pair of permanent magnets that face the magnetic field forming means so as to branch the electrons drawn in by the electron accelerating means and compress them flatly, and a solenoid coil for transferring the flattened electrons along the flat plane. The plasma device according to claim 1, wherein the plasma device is configured by: