JPH1083897A - Plasma generating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently introduce an induced electric field into a position of magnetic neutral beams and form highly efficient magnetic neutral beam plasma by arranging a high frequency coil in the approximately the same plane of the magnetic neutral beams generated by permanent magnets in a vacuum chamber. SOLUTION: A substrate electrode 8 to be connected to a RF bias power source 9 is arranged in a process chamber of a vacuum chamber 1 and ring magnetic neutral beams of a magnetic field O continuously existing by a magnetic field generating means are generated in the chamber. This magnetic field generating means comprises a doughnut-like or disk-like inside permanent magnet installed in the outside face of a flat type metal upper part wall 2 of the vacuum chamber 1 and a doughnut-like outside permanent magnet 4 having a large diameter and the same polarity as the magnet 3 and a concentrically circular shape. Further, a single layer or more of a high frequency coil 6 is installed in the outside of a cylindrical dielectric body side wall 5 approximately the same plane as the plane on which magnetic neutral beams are formed and high frequency power is supplied from a high frequency power source 7 to form an induced electric field. Consequently, an alternating electric field is applied along the magnetic neutral beams to generate discharge plasma at high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generating apparatus used in an etching apparatus for etching a substance on a substrate, such as a semiconductor or an electronic component, using plasma, and a plasma CVD apparatus for depositing a film on the substrate. It concerns the device.

[0002]

2. Description of the Related Art Conventionally, for example, in an etching apparatus or a plasma CVD apparatus, a magnetron type using a magnet, an ECR discharge type using an electron cyclotron resonance, and a helicon type plasma generating apparatus using a helicon wave are mainly used. I have been.

[0003] More recently, magnetic field generating means by three solenoid coils for forming a magnetic neutral line in a vacuum chamber, and an electric field along the magnetic neutral line formed in the vacuum chamber by the magnetic field generating means. A plasma generator has been proposed which is provided with a magnetic field generating means for generating discharge plasma in this magnetic neutral line (see Japanese Patent Application No. 5-183899), which is applied to an etching apparatus and the like (Japanese Patent Application No. 6-
52420 and Japanese Patent Application No. 7-116154).

Further, there has been proposed an example in which a permanent magnet is used instead of a coil as a magnetic field generating means for forming a magnetic neutral line (see Japanese Patent Application No. 7-217965). The present invention relates to an improvement of a magnetic neutral line discharge plasma device using the permanent magnet.

That is, in the plasma generating apparatus proposed in Japanese Patent Application No. 7-217965, as shown in FIG. 7 of the accompanying drawings, plasma is generated in a vacuum chamber A whose upper surface A1 is dielectric. A discharge plasma apparatus, wherein a donut-shaped or disc-shaped permanent magnet B is formed on a dielectric upper surface A1 to form an annular magnetic neutral line at a position of zero magnetic field continuously present in a vacuum chamber A. Also, a donut-shaped permanent magnet C having a large inner diameter is disposed, and an alternating electric field is applied along the magnetic neutral line formed in the vacuum chamber A by the permanent magnets B and C to discharge plasma to the magnetic neutral line. Are disposed between the permanent magnets B and C. The diameter of the magnetic neutral wire and the distance from the magnet surface are determined by the magnetic permeability of the two permanent magnets B and C and the length of the gap between them. When the magnetic permeability of the two permanent magnets B and C is equal, the two permanent magnets B and C
A magnetic neutral line is formed inside the vacuum chamber A at an intermediate position of C. FIG. 8 shows an equipotential map calculated in the magnet arrangement of FIG. The distance from the magnet surface of the formed magnetic neutral line increases as the distance between the two magnets B and C increases, and does not depend on the magnetic field strength. Then, a high-frequency electric field is applied by a high-frequency coil D provided on the upper dielectric surface A1 parallel to the surface on which the magnetic neutral line is formed, thereby generating a plasma by applying a high-frequency electric field. Since there is a portion where the magnetic field is zero, a highly efficient plasma can be generated at a low gas pressure.

When an Si substrate with an oxide film is etched using the apparatus shown in FIG. 7, when a 100 kHz high-frequency power source is used for RF bias, the pressure of cyclooctane fluorinated gas is 0.67 Pa. , RF bias power is 500W,
600nm / min ± 7% when RF antenna power is 1500W
High etching rate and high etching uniformity. The magnetic neutral ray discharge plasma device that has been proposed as described above is a discharge plasma device that generates plasma in a vacuum chamber having a dielectric top surface,
A donut-shaped or disk-shaped permanent magnet arranged on the top surface of the dielectric to form an annular magnetic neutral line that is a position of zero magnetic field that exists continuously in the vacuum chamber, and a donut-shaped one having a larger inner diameter than that of the permanent magnet An alternating electric field is applied from the middle of the two permanent magnets along the magnetic neutral line formed in the vacuum chamber by the two permanent magnets and the magnetic field generating means to generate a discharge plasma in the magnetic neutral line. For this reason, the plasma generator is composed of multiple high-frequency coils including a single coil. And it was also confirmed that such a magnetic neutral discharge plasma apparatus is superior to inductively coupled plasma as well as being able to obtain a high efficiency magnetic neutral discharge plasma.

[0007]

However, a magnetic neutral line is formed by a donut-shaped or disc-shaped permanent magnet and two donut-shaped permanent magnets having a larger inner diameter than the two permanent magnets. Is a method of installing a high-frequency coil that gives a high-frequency electric field that gives an alternating electric field to
There is a problem that the induced electric field at the position of the magnetic neutral line is weak and the expected plasma density cannot be obtained.

SUMMARY OF THE INVENTION The present invention solves the problems with these conventional devices, and provides an efficient magnetic neutral discharge plasma device by efficiently introducing an induction electric field at the position of a magnetic neutral line. It is an object.

[0009]

According to the present invention, there is provided, in accordance with the present invention, a method for forming an annular magnetic neutral line which is a position of zero magnetic field, which is continuously present in a vacuum chamber. A donut-shaped or disk-shaped permanent magnet and two donut-shaped permanent magnets having an inner diameter larger than the donut-shaped permanent magnet are provided on the upper surface of the chamber, and the magnetic field generating means moves along a magnetic neutral line formed in the vacuum chamber. In order to generate a discharge plasma in the magnetic neutral line by applying an alternating electric field, in a plasma generating apparatus provided with a single and multiple high-frequency coils, the high-frequency coil is placed on substantially the same plane as the surface on which the magnetic neutral line is formed. At the position shown in FIG. 3 so that the induction electric field can be efficiently introduced.

[0010]

DETAILED DESCRIPTION OF THE INVENTION According to one embodiment of the present invention, an annular magnetic field is located at a position of zero magnetic field that is continuously present in a vacuum chamber having a top wall, a bottom wall, and side walls. On the outer surface of the upper wall of the vacuum chamber to form the
A magnetic field generating means composed of a donut-shaped or disk-shaped first permanent magnet and a donut-shaped second permanent magnet having a larger inner diameter than the first permanent magnet is arranged, and the magnetic field generated in the vacuum chamber by the magnetic field generating means is provided. In order to generate an electric discharge plasma on this magnetic neutral line by applying an alternating electric field along the neutral line, the surface on which the magnetic neutral line is formed outside the side wall composed of the dielectric material of the vacuum chamber is formed. It is characterized in that multiple high-frequency coils including a single coil are arranged at substantially the same position on a plane to form magnetic neutral plasma. According to another embodiment of the present invention, a donut-shaped or disk-shaped first permanent magnet and a donut-shaped second permanent magnet constituting the magnetic field generating means are provided.
May consist of a plurality of permanent magnets, each arranged concentrically.

[0011]

In the plasma generator according to the present invention having the above-described structure, the high-frequency coil is installed in substantially the same plane as the surface on which the magnetic neutral line is formed. The electric field is effectively introduced, and the induced electric field can effectively accelerate the electrons gathered in the magnetic neutral line, and a highly efficient magnetic neutral line discharge plasma can be formed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an embodiment in which the plasma generating apparatus according to the present invention is applied to an etching apparatus. In the illustrated apparatus, reference numeral 1 denotes a cylindrical vacuum chamber forming a process chamber, the upper surface of which is covered with a flat metal partition 2.
On the outer surface of the flat metal partition 2, a disk-shaped inner permanent magnet 3 having a polarity as shown above and below, and an inner diameter larger than that of the disk-shaped inner permanent magnet 3 and having the same polarity as the inner permanent magnet 3. A donut-shaped outer permanent magnet 4 is mounted concentrically, and these permanent magnets 3 and 4 constitute a magnetic field generating means for forming a magnetic neutral line in the vacuum chamber 1. As shown, the disk-shaped inner permanent magnet 3 is arranged at the same height position as the donut-shaped outer permanent magnet 4. On the outside of the side wall 5 of the cylindrical vacuum chamber 1, there are arranged a plurality of single high-frequency coils 6 constituting an electric field generating means, and this high-frequency coil 6 is connected to a high-frequency power source 7 having a frequency of 13.56 MHz. An alternating electric field is applied along the magnetic neutral line formed in the vacuum chamber 1 by the permanent magnets 3 and 4 to generate discharge plasma in the magnetic neutral line. A substrate electrode 8 is provided at a position parallel to and separated from the surface of the magnetic neutral line formed in the vacuum chamber 1, and the substrate electrode 8 is a high-frequency power source 9 having a frequency of 13.56 MHz for applying an RF bias. It is connected to the.

Next, how the current flowing through the high-frequency coil 6 acts on the magnetic neutral line will be described. The electric field induced when a current flows through the loop antenna is obtained as follows by obtaining a vector potential. Further, when the high-frequency current I is applied to the antenna 6 according to the present invention, the boundary condition is set as follows in the evaluation of the induced electric field strength. 1) The antenna 6 is a thin conductor or the current density J flowing through the antenna is uniform in the cross section of the conductor. 2) The dimensions of the antenna 6 are much shorter than the applied radio frequency and the wavelength of the electromagnetic waves excited by it (for example, 10
%Less than). Becomes Here, the direction of the vector potential A is the same as dl. FIG. 2 is a schematic diagram when the current I is applied to the single circular antenna 6, and FIG. 3 is a projection view of the vector potential at the point P in the space XY plane. It is represented by Here, K (k) and E (k) are first and second types of complete elliptic integrals. FIG. 4 shows the relative distribution of the induced electric field intensity distribution in the 1/4 quadrant on the vertical plane of the one-turn coil calculated using the above equation. In the calculation, a = 1 and I = 1. In the example of FIG. 7, the distance between the antenna and the magnetic neutral line is 60
If the radius of the magnetic neutral line is 120 mm in mm and the distance is expressed as a relative value, then 60 mm / 120 mm = 0.5. The point indicated by xb in FIG. 4 is the value of the vector potential (about 1.8 × 10 ⁻⁷ ) in the example of FIG. On the other hand, the relative distance of the magnetic neutral line in the embodiment of the present invention shown in FIG. 1 is 120 mm / 150 mm = 0.8 when the radius of the magnetic neutral line is 120 mm and the diameter of the antenna is 150 mm. . This point is indicated by xa in FIG. 4, and the value of the vector potential is about 3.6 × 10 ⁻⁷ . Since the induced electric field is proportional to the vector potential, in the embodiment of the present invention shown in FIG. 1 as compared with the example shown in FIG. 7, the induced electric field in the magnetic neutral line is twice as large, that is, twice as efficient.

FIG. 5 is a schematic diagram of a system for supplying high-frequency power from the side according to the present invention. FIG. 6 is a schematic diagram of a system for supplying high frequency power from above in the conventional example as shown in FIG.

In the embodiment shown in FIG.
A high-frequency power of 6 MHz is applied, a high-frequency power of 13.56 MHz is also applied to the substrate electrode, and an Si substrate with an oxide film applied to “reactive ion etching” is used, under the same conditions as the apparatus shown in FIG. Cyclobutane octafluoride gas pressure is 0.67
As a result of conducting an experiment under the conditions of Pa and RF bias power of 1500 W), an etching rate of 800 to 1000 nm / min higher than that of the conventional apparatus (FIG. 7) was obtained.

In the embodiment, the permanent magnets 3 and 4 constituting the magnetic field generating means are each composed of a single magnet, but are instead composed of a plurality of permanent magnets arranged concentrically. You can also. Further, the position where the antenna 6 is arranged does not necessarily have to be in the same plane as the plane of the magnetic neutral line, and a sufficient effect can be obtained even in a position slightly shifted up and down as understood from FIG.

Further, a high frequency of 13.56 MHz is used for the high frequency coil 6 for introducing a high frequency electric field, but the present invention is not limited to this frequency. Similarly, the high frequency applied to the substrate electrode 8 is not limited to 13.56 MHz. When power supplies of the same frequency are used for the antenna and the substrate electrode, a phase control circuit for adjusting the phase between the two power supplies is generally required. In the illustrated embodiment, the case where the plasma generating apparatus of the present invention is applied to an etching apparatus has been described. However, a similar effect can be obtained in a sputtering apparatus and a CVD apparatus.

[0019]

As described above, according to the present invention, a donut-shaped or disc-shaped permanent magnet forming a magnetic neutral line and two donut-shaped permanent magnets having a larger inner diameter than the permanent magnet are formed. In the conventional magnetic field structure, the high-frequency antenna is located almost on the same plane as the magnetic neutral line and outside the magnetic neutral line. Can be generated,
The induced electric field formed by the magnetic field can effectively act on the electrons gathered in the magnetic neutral line, and it has become possible to form a magnetic neutral line discharge plasma with high efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic layout diagram showing an embodiment in which a plasma generator according to the present invention is applied to a magnetic neutral beam discharge etching apparatus.

FIG. 2 is an explanatory diagram when a current I is applied to an antenna in the device shown in FIG.

FIG. 3 is an explanatory diagram showing a vector potential in a space of the device shown in FIG. 1;

FIG. 4 is a diagram in which a calculated value of a vector potential formed by a one-turn loop antenna is plotted with a radius (R) and a height (Z).

FIG. 5 is an explanatory diagram showing an arrangement of a magnetic neutral wire and a high-frequency coil according to the present invention.

FIG. 6 is an explanatory view showing the arrangement of a magnetic neutral wire and a high-frequency coil in a conventional device (FIG. 7).

FIG. 7 is a schematic view of a conventional magnetic neutral beam discharge etching apparatus in which two permanent magnets are arranged on the same surface.

8 is a graph showing a calculation result of equipotential lines by a finite element method in the magnetic field arrangement of FIG. 7;

[Explanation of symbols]

 1: vacuum chamber 3: inner permanent magnet 4: outer permanent magnet 5: dielectric side wall 6: high frequency coil 7: high frequency power supply

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[Procedure amendment]

[Submission date] September 11, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG. 1 is a schematic layout view showing an embodiment in which a plasma generator according to the present invention is applied to a magnetic neutral discharge etching apparatus. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 25, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

[0014]

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuichi Ogawa 45, Yakinoji-cho, Ichigaya, Shinjuku-ku, Tokyo 2-301 Residence of Yaouji (72) Inventor Daijiro Uchida 2500 Hagizono, Chigasaki-shi, Kanagawa Prefecture Japan Vacuum Engineering Co., Ltd.

Claims (2)

[Claims] 1. An outer surface of a top wall of a vacuum chamber for forming an annular magnetic neutral line which is a position of zero magnetic field that is continuously present in the vacuum chamber having a top wall, a bottom wall, and a side wall. A magnetic field generating means comprising a donut-shaped or disk-shaped first permanent magnet and a donut-shaped second permanent magnet having a larger inner diameter than the first permanent magnet is arranged on the upper side, and formed in the vacuum chamber by the magnetic field generating means. A magnetic neutral line is formed outside the side wall composed of the vacuum chamber dielectric to apply an alternating electric field along the magnetic neutral line and generate a discharge plasma in the magnetic neutral line. A plasma generator characterized in that multiple high-frequency coils including a single coil are arranged at a position substantially on the same plane as a surface to be formed to form magnetic neutral plasma. 2. The doughnut-shaped or disk-shaped first permanent magnet and the donut-shaped second permanent magnet constituting the magnetic field generating means are each composed of a plurality of permanent magnets arranged on concentric circles. Characteristic plasma generator.