JP2564572B2 - Plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a plasma processing apparatus used for manufacturing a semiconductor device and the like.

(Prior Art) Generally, a plasma processing apparatus is used for manufacturing a semiconductor device and the like, and performs etching, film formation, and the like by using plasma.

As such a plasma processing apparatus, several types of apparatuses have been conventionally known. However, the present inventors have conventionally proposed a system for generating a plasma by exciting a reaction gas by an electron beam (Electron beam excited plasma sys.).
tem). In this system, for example, a plasma is formed by glow discharge or the like, electrons are extracted from the plasma, accelerated and introduced into a predetermined reaction gas atmosphere, and the reaction gas is activated by the electron beam. To generate high-density plasma.

In this system, a magnetic field is formed along the traveling direction of the electron beam, and the magnetic field guides the electron beam.

(Problems to be Solved by the Invention) In recent years, for example, in the manufacture of semiconductor devices and the like, the diameter of semiconductor wafers tends to be increased to 6 inches, 8 inches, or the like. For this reason, in a plasma processing apparatus, there is an increasing need to form plasma with a larger diameter and more uniformly.

However, in the plasma processing apparatus described above, a magnetic field is formed along the traveling direction of the electron beam, and the magnetic field guides the electron beam. However, there is a problem that the diameter is concentrated at the central portion and the diameter of the formed plasma is reduced.

The present invention has been made in view of such a conventional situation, and is capable of forming a plasma having a large diameter and a uniform size as compared with the related art, and a plasma processing capable of performing a uniform processing even on a large-diameter wafer or the like. It is intended to provide a device.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention converts a predetermined reaction gas into a plasma by extracting, accelerating, and irradiating electrons from the plasma.
An object to be processed is processed by the plasma, and in a plasma processing apparatus having a magnetic field forming means for forming a magnetic field along the traveling direction of the electrons and guiding the electrons, the reaction gas is turned into plasma by the magnetic field forming means. A means for canceling a magnetic field formed in the region is arranged.

(Operation) In the plasma processing apparatus of the present invention having the above configuration, in order to guide the electrons, of the magnetic fields formed along the traveling direction of the electrons, the magnetic field formed in the region where the reaction gas is turned into plasma is used. There is a means to cancel. Therefore, the electrons that enter the region where the reaction gas is turned into plasma are spread outward as compared with the related art, and a large-diameter and uniform plasma can be formed.

Embodiment An embodiment in which the plasma processing apparatus of the present invention is applied to a dry etching apparatus will be described below in detail with reference to the drawings.

For example, one end of a cylindrical container 1 made of stainless steel or the like has a discharge gas introduction hole 2a for introducing a discharge gas such as an argon gas at a central portion. A cylindrical cathode electrode 2 is provided to protrude.

Further, a holder 4 having a shutter 3 and holding an object to be processed such as a semiconductor wafer is disposed at an end of the closed vessel 1 opposite to the cathode electrode 2.
An intermediate electrode 5, an intermediate electrode 6, an anode electrode 7, and an electron beam accelerating electrode 8 each having a through hole at a central portion are arranged between the first electrode 5 and the holder 4 in order from the cathode electrode 2 side. Around the intermediate electrode 5, the intermediate electrode 6, the anode electrode 7, and the electrode 8 for accelerating the electron beam, coils 9 to 12 each formed in a ring shape are arranged.
Further, an annular reverse magnetic field coil 13 for generating a magnetic field in a direction opposite to that of the coils 9 to 12 is disposed beside the coil 12.

The through-holes formed in the central portions of the intermediate electrodes 5 and 6, the anode electrode 7, and the electron beam accelerating electrode 8 have a diameter of about 7 mm for the intermediate electrode 5, about 30 mm in length, and about 15 mm for the intermediate electrode 6. , Length about 20mm, diameter in case of anode electrode 7
The electrode 8 has a diameter of about 8 mm, a length of about 15 mm, and a diameter of about 20 mm and a length of about 50 mm in the case of the electrode 8 for electron beam acceleration. An exhaust hole 14 is disposed between the intermediate electrode 6 and the anode electrode 7, an exhaust hole 15 is disposed between the anode electrode 7 and the electron beam acceleration electrode 8, an electron beam acceleration electrode 8 and the holder 4. Are differentially evacuated by an exhaust hole 16 arranged between the two, and the pressure between them can be adjusted.

The cathode electrode 2 is configured, for example, as shown in FIG. That is, a round bar-shaped auxiliary cathode 2b having a discharge gas introduction hole 2a at the center and made of a material such as tantalum is supported at one end by a support member 2c made of a ceramic or the like. Note that the tip of the auxiliary cathode 2b is preferably formed in a tapered shape in order to easily generate a glow discharge. Then, in the vicinity of the tip of the auxiliary cathode 2b, the annular made of a material for example LaB _6, etc. are the main cathode 2d are arranged, these surroundings are covered by a cylindrical member 2e made of a material such as molybdenum or the like .

Since the temperature of each electrode and the holder 4 becomes high, the dry etching apparatus of this embodiment is configured to provide a cooling water flow path for cooling (not shown) in each electrode and the holder 4 so as to perform cooling.

In the dry etching apparatus of this embodiment having the above configuration,
The discharge region 20 is defined between the cathode electrode 2 and the anode electrode 7, the electron beam acceleration region 21 is defined between the anode electrode 7 and the electron beam acceleration electrode 8, and the discharge region 20 is defined between the electron beam acceleration electrode 8 and the holder 4. The space between them is an etching region 22.

In the discharge region 20, a discharge gas such as an argon gas is introduced from the charge gas introduction hole 2a, and the gas is evacuated so that the pressure between the cathode electrode 2 and the intermediate electrode 5 becomes, for example, about 1.0 Torr. , A cathode electrode 2, an intermediate electrode 5,
A glow discharge is generated by applying a discharge voltage Vd to the anode electrode 7. During operation, the degree of vacuum is increased so that the pressure between the cathode electrode 2 and the intermediate electrode 5 becomes, for example, about 0.6 Torr.

The intermediate electrodes 5 and 6 are for facilitating the glow discharge to occur at a low voltage. First, a glow discharge is generated between the cathode electrode 2 and the intermediate electrode 5, and thereafter, the glow discharge is transferred to the intermediate electrode 6 and the anode electrode 7. I will do it. After a stable glow discharge is formed between the cathode electrode 2 and the anode electrode 7, the switches S1 and S2 are turned off.

This glow discharge occurs first at the tip of the auxiliary cathode 2b, but when the temperature rises to about 1500 ° C. due to the discharge, the main cathode 2d, which has excellent emission characteristics at high temperatures,
Move to

The pressure in the electron beam acceleration region 21 is, for example, about 10 ⁻⁴ Torr, and an electron beam acceleration voltage Vacc is applied to the electron beam acceleration electrode 8. Then, electrons are extracted from the plasma generated in the discharge region 20, accelerated, and introduced into the etching region 22.

The etching region 22 is supplied with an etching gas such as a chlorine gas or an argon gas through the etching gas introduction hole 17 and exhausted from the exhaust hole 16 to a pressure of, for example, 10 ^-4 .
A voltage of about 10 ^-3 is applied between the electron beam accelerating electrode 8 and the holder 4. Then, the electron beam acceleration area 21
The plasma is generated by activating the etching gas by the electron beam introduced from the substrate.

At this time, the coils 9 to 12 are energized to guide the electron beam by the magnetic field B formed in the direction of the arrow shown in the figure. Also,
The reverse magnetic field coil 13 forms a magnetic field in a direction opposite to the magnetic field B, and acts so as to cancel the magnetic field B formed in the etching region 22, thereby diffusing the electron beam outward in the etching region 22. To generate a large-diameter plasma.

Then, the ions in the plasma are accelerated in a plasma sheath formed on the surface of the target such as a semiconductor wafer held by the holder 4, and blast the target as an ion beam to etch the target. At this time, the processing time is controlled by turning on / off the shutter 3 or the electron beam acceleration power supply.

In the plasma processing apparatus of this embodiment described above, the reversed magnetic field coil 13 cancels out the magnetic field B formed in the etching region 22 by the coils 9 to 12, and diffuses the electron beam outward in the etching region 22; Generates large-diameter plasma. Then, the etching gas is activated by the diffused electron beam to generate high-density plasma. Therefore, for example, without increasing the length of the etching region 22, it is possible to form a plasma having a large diameter and uniformity as compared with the related art, and it is possible to uniformly process a large-diameter wafer or the like.

As shown in FIG. 3, for example, a plurality of permanent magnets 30 may be arranged so as to surround a peripheral portion in the etching region 2, and the plasma may be confined by a multipolar magnetic field. When a multipole magnetic field is formed in this way, as shown in FIG. 4, a small-diameter multipole magnetic field is formed by a plurality of permanent magnets 30a on the electron beam accelerating electrode 8 side.
A plurality of multi-pole magnetic fields having different diameters can be formed on the holder 4 side by forming a large-diameter multi-pole magnetic field using the plurality of permanent magnets 30b.

In the above embodiment, the reverse magnetic field coil 13 is used to cancel the magnetic field B formed in the etching region 22. However, as shown in FIG. 5, for example, as shown in FIG. For example, 40 may be arranged in the etching region 22. In this case, the holder 4 separated from the annular permanent magnet 40
In the position (1), the magnetic field B 'by the annular permanent magnet 40
(Indicated by a dotted line in the figure) is formed so as to cancel the magnetic field B as in the case where the permanent magnet 40 is one dipole having no hollow portion in the center. As shown in FIG. 6, a magnetic shield such as a cylindrical metal 50 surrounding the outside of the etching region 22 may be provided. In this case, a cylindrical metal 50 which is a magnetic material
The magnetic field lines are concentrated in the region, and the magnetic field in the etching region 22 can be weakened.

Furthermore, in the above embodiment, an example in which the present invention is applied to a dry etching apparatus has been described. However, the present invention is not limited to such an embodiment, and for example, a film forming apparatus, etc.
Of course, it can be applied to other plasma processing apparatuses.

[Effects of the Invention] As described above, in the plasma processing apparatus of the present invention, a plasma having a large diameter and uniformity can be formed as compared with the conventional plasma processing apparatus, and a large-diameter wafer or the like can be uniformly processed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a plasma processing apparatus according to one embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing a cathode electrode, and FIGS.
FIG. 6 is a configuration diagram showing a main part of a plasma processing apparatus according to another embodiment. 1 ... closed container, 2 ... cathode electrode, 2a ... discharge gas introduction hole, 3 ... shutter, 4 ... holder, 5,6 ...
Intermediate electrode, 7: Anode electrode, 8: Electrode for accelerating electron beam, 9 to 12: Coil, 13: Reverse magnetic field coil, 14 to
16 ... exhaust hole, 17 ... etching gas introduction hole, 20 ... discharge region, 21 ... electron beam acceleration region, 22 ... etching region.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsunobu Aoyagi, Inventor 2-1 Hirosawa, Wako-shi, Saitama Pref. (72) Inventor Susumu Namba 2-1 Hirosawa, Wako-shi, Saitama Pref. ▲ Yoshi ▼ Nagataka 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Tokyo Electron Co., Ltd. (72) Inventor Yoichi Araki 1-26-2-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Tokyo Electron Co., Ltd.

Claims (4)

(57) [Claims] An electron is extracted from a plasma, accelerated and irradiated, and a predetermined reaction gas is turned into a plasma. The object to be processed is processed by the plasma, and a magnetic field is formed along the traveling direction of the electron to generate the electron. A plasma processing apparatus having a magnetic field forming means for guiding, wherein means for canceling a magnetic field formed in a region where the reaction gas is turned into plasma by the magnetic field forming means is arranged. 2. The plasma processing apparatus according to claim 1, wherein the means for canceling the magnetic field is a reverse magnetic field coil disposed near the outside of a region where the reaction gas is turned into plasma. . 3. The magnetic field shield according to claim 1, wherein the means for canceling the magnetic field is a magnetic field shield disposed outside the region where the reaction gas is turned into plasma so as to surround the region. Item 6. The plasma processing apparatus according to item 1. 4. The plasma processing apparatus according to claim 1, wherein said means for canceling said magnetic field is a ring-shaped magnet arranged in a region where said reaction gas is turned into plasma.