JPH0480384A - Plasma etching device - Google Patents

Abstract

PURPOSE:To uniformalize etching and also to prevent etching defective by annularly arranging the respective magnet poles of a multipolar electromagnet having even pieces of magnetic poles in the prescribed intervals to the external periphery of the cylindrical side wall of an etching chamber and regulating the adjacent magnetic poles to reverse polarities with each other in a plasma etching device. CONSTITUTION:The respective magnetic poles of a multipolar electromagnet 14 having even pieces of magnetic poles 13 are annularly arranged in the prescribed intervals to the external periphery of the cylindrical side wall 1 of an etching chamber 2. The adjacent magnetic poles 13 are regulated to the reverse polarities 13. Plasma is generated by discharge caused between a counter electrode 5 and a base plate electrode 8. This plasma receives the effect of the magnetic field of a double annular electromagnet 6 and is made to high density in the vicinity of the counter electrode 5 and etches a base plate 7 at high velocity. The plasma is contained into the space between the counter electrode 5 and the base plate electrode 8 by a cusp field formed by the multipolar electromagnet 14 arranged to the external periphery of the cylindrical side wall 1 of the etching chamber 2. Dissociation of gas in this space is advanced and homogenizing of plasma in the space is caused and uniformity of etching is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a plasma etching apparatus in which a multipolar electromagnet having an even number of magnetic poles is arranged around the outer periphery of a cylindrical side wall of an etching chamber.

(Prior Art) A conventional plasma etching apparatus is shown in FIG. 6, in which the upper part of an etching chamber 2 having a cylindrical side wall 1 is covered with a top plate 3. A flat counter electrode 5 at ground potential that also serves as the gas outlet 4 is provided at the bottom, and a double annular electromagnet 6 is provided at the top of the top plate 3. An annular electromagnet 6 is located there. The double annular electromagnet 6 has two annular yokes 6b and 6c having different diameters arranged concentrically around a central yoke 6a.
It has a structure in which coils 6d and 6e are provided between the annular yoke 6a and the annular yoke 6b, and between the annular yoke 6b and the annular yoke 6c, respectively.

A flat substrate electrode 8 on which a substrate 7 is placed is located below the etching chamber 2, and the substrate electrode 8 faces a flat counter electrode 5 at a distance within the etching chamber 2.

The gas flows into the counter electrode 5 from the gas introduction part 9, and is ejected from the gas outlet 4 of the counter electrode 5 in the direction of the substrate electrode 8. In the figure, lO is a cooling unit that cools the substrate electrode 8, and 11 is a cooling unit 13 for cooling the substrate electrode 8.
This is a high frequency power source that applies high frequency power of 5'6 MHz.

In such a plasma etching apparatus, a discharge occurs between the counter electrode 5 and the substrate electrode 8, and plasma is generated.
Under the influence of the magnetic field, the density is high near the counter electrode 5. Ions in this high-density plasma are then attracted to the substrate electrode 8 and collide with the substrate 7 on the substrate electrode 8, etching the substrate 7 at a high speed.

(Problems to be Solved by the Invention) The conventional plasma etching apparatus is designed so that the ions in the high-density plasma generated under the influence of the magnetic field of the double ring electromagnet 6 as described above etch the substrate at high speed. However, since the magnetic field of the double ring electromagnet 6 is not uniform but non-uniform, a problem arose in that the etching was not uniform. Therefore, the distance between the counter electrode 5 and the substrate electrode 8 cannot be narrowed, and as a result, the etching rate is limited, or the distance between the electrodes becomes wide, and the substrate 7
The ion bombardment on the substrate increased, causing problems such as deterioration of the electrical characteristics of the integrated circuit substrate. Furthermore, when plasma is generated under the influence of the magnetic field of the double ring electromagnet 6, the pressure is on the order of 10-3 Torr, so the plasma spreads outside the counter electrode 5 and the substrate electrode 8, resulting in etching. This has resulted in problems such as a decrease in the efficiency of etching, or deposition due to repolymerization on the outside of the counter electrode 5 and substrate electrode 8, which adheres to the substrate and forms a mask, resulting in etching residue. Furthermore, problems such as sputtering of the cylindrical side wall 1 of the etching chamber 2 by the plasma spreading outside the counter electrode 5 and the substrate electrode 8 have occurred, and the particles thereof are mixed into the substrate 7 as impurities.

The purpose of this invention is to provide a plasma etching apparatus that solves the conventional problems, makes etching uniform, eliminates ion bombardment, and enables high-speed etching without etching defects due to contamination due to deposition or contamination from surrounding sidewalls. Our goal is to provide the following.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a plasma etching apparatus as described above, in which a multi-pole etching device having an even number of magnetic poles is provided on the outer periphery of the cylindrical side wall of the etching chamber. Each magnetic pole of the electromagnet is arranged in a ring shape at a predetermined interval, and adjacent magnetic poles are made to have opposite polarity to each other, allowing the multipolar electromagnet to confine discharge and control the multipolar magnetic field formed by the multipolar electromagnet. It is characterized by this.

(Function) In the plasma etching apparatus of the present invention, the magnetic poles of a multipolar electromagnet having an even number of magnetic poles are arranged in a ring shape at predetermined intervals around the outer periphery of the cylindrical side wall of the etching chamber, and adjacent magnetic poles are arranged in a ring shape at predetermined intervals. Since the polarities are opposite to each other, a cusp magnetic field is formed.

Therefore, the plasma generated by the discharge between the counter electrode and the substrate electrode is affected by the cusp magnetic field, suppressing the plasma from spreading to the surroundings, and causing the plasma to concentrate between the counter electrode and the substrate electrode. . As a result, etching efficiency has been improved, uniform etching has become possible, and deposition and sputtering around the substrate has been eliminated, and contamination of impurities into the substrate has been suppressed. Furthermore, by controlling the multipolar magnetic field formed by the multipolar electromagnet, it is possible to change the strength of the cusp magnetic field and change the area where the discharge is concentrated, making it possible to obtain a discharge area that matches the substrate. Became.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the same figure, the same reference numerals as in FIG. By improving the technique, each magnetic pole of a multipolar electromagnet 14 having an even number of magnetic poles 13 is arranged in a ring shape at a predetermined interval on the outer periphery of the cylindrical side wall l of the cutting chamber 2, and adjacent magnetic poles 13 are arranged in a ring shape. They have mutually opposite polarities. As shown in FIGS. 2 and 3, the magnetic pole 13 is formed by extending a portion of the yoke 15 inward at equal intervals.
It is made by winding 6. When the polarity of the magnetic pole 13 is reversed, it is done by reversing the winding of adjacent coils or by reversing the direction of the current applied to the coils.

In such an embodiment, plasma is generated by the discharge between the counter electrode 5 and the substrate electrode 8, as in the conventional case, but the plasma is influenced by the magnetic field of the double ring electromagnet 6. , the etching density becomes high near the counter electrode 5, making it possible to etch the substrate 7 at a high speed. However, in this embodiment, unlike the conventional etching chamber 2, plasma is caused to flow into the space between the counter electrode 5 and the substrate electrode 8 due to the cusp magnetic field formed by the multipolar electromagnet 14 disposed around the outer periphery of the cylindrical side wall 1 of the etching chamber 2. The gas is confined, gas dissociation progresses in that space, the plasma becomes homogenized in that space, and the uniformity of etching improves. In addition, because the plasma is prevented from spreading outside the space between the counter electrode 5 and the substrate electrode 8 due to the influence of the cusp magnetic field, there is no sputtering or deposition on the cylindrical side wall l of the etching chamber 2. This also suppresses impurities from entering the substrate 7. Furthermore, by controlling the current value flowing through the coil 16 of each magnetic pole 13 of the multipole electromagnet 14, it is possible to control the strength of the cusp magnetic field. It became possible to obtain a discharge area according to the

By the way, in the above embodiment, a high frequency power of 1356 MHz is applied to the substrate electrode 8 and the counter electrode 5 is set to the ground potential. Electric power may also be applied. Further, as shown in FIG. 4, the counter electrode 5 and the cylindrical side wall 1 of the etching chamber 2 are insulated by an insulator I7, one of which is set at ground potential, and a high frequency power of 13.56 MHz is applied to the other. And 100KHz to substrate electrode 8
High frequency power of 600 KHz or 13.56 MHz may be applied. Furthermore, a multipole electromagnet structure as shown in FIG. 5 may be used.

(Effects of the Invention) As described above, the present invention arranges the magnetic poles of a multipolar electromagnet having an even number of magnetic poles in a ring shape at predetermined intervals on the outer periphery of the cylindrical side wall of the etching chamber. Since the polarities are mutually opposite and the discharge is confined by the multipolar electromagnet, and the multipolar magnetic field formed by the multipolar electromagnet can be controlled, the following effects are achieved.

(1) A cusp magnetic field is formed by a multipole electromagnet, and plasma is confined in the space between the counter electrode and the substrate electrode,
Gas dissociation progresses in that space, plasma becomes homogenized within that space, and etching uniformity improves.

(2) Due to the effect of the cusp magnetic field, the plasma is prevented from spreading outside the space between the counter electrode and the substrate electrode, so there is no sputtering or deposition on the cylindrical side wall of the etching chamber, and there is no deposition on the substrate. The contamination of impurities is suppressed.

(3) By controlling the multipolar magnetic field formed by the multipolar electromagnet, it is possible to change the area where the discharge is concentrated by changing the strength of the cusp magnetic field, and it is possible to obtain a discharge area according to the substrate. It becomes possible.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of this invention, and FIG.
3 is a perspective view showing a part of the magnetic poles of the multipolar electromagnet shown in FIG. 1, FIG. 4 is an explanatory view showing another embodiment of the present invention, and FIG. FIG. 5 is an explanatory diagram of a multipolar electromagnet used in another embodiment of the present invention. FIG. 6 is an explanatory diagram showing a conventional plasma etching apparatus. In the figure, l... Cylindrical side wall 2 of the etching chamber...
Etching chamber 4... Gas outlet 5... Counter electrode 6... Double annular electromagnet 7... Substrate 8... Substrate electrode 11... High frequency Power supply 13... Magnetic pole of multipolar electromagnet 14... Multipolar electromagnet 15 ・ 5a l 6 ・ I 7 ・ ・Yoke, yoke overhang, coil, insulator

Claims (4)

[Claims] 1. A flat counter electrode with an electromagnet behind it and a substrate electrode, which is also a flat plate, are placed facing each other at a distance in an etching chamber with a cylindrical side wall, and gas is injected from the gas outlet of the flat counter electrode. In a plasma etching apparatus that etches the substrate on the substrate electrode with plasma ejected in the direction of a flat substrate electrode and generated by discharge, a multipole having an even number of magnetic poles is installed on the outer periphery of the cylindrical side wall of the etching chamber. Each magnetic pole of the electromagnet is arranged in a ring shape at a predetermined interval, and adjacent magnetic poles are made to have opposite polarity to each other, so that the above discharge is contained by the multipolar electromagnet, and the multipolar magnetic field formed by the multipolar electromagnet can be controlled. A plasma etching device characterized by: 2. 2. The plasma etching apparatus according to claim 1, wherein said electromagnet is a double annular electromagnet. 3. 13 on either one of the counter electrode and the substrate electrode.
．． 3. The plasma etching apparatus according to claim 1, wherein a high frequency power of 56 MHz is applied, and the other end is set at ground potential. 4. The above-mentioned counter electrode and the cylindrical side wall of the etching chamber are insulated, one of them is set to ground potential, and the other is set to 13.56 MHz.
high frequency power of 100 KH is applied to the above substrate electrode.
3. The plasma etching apparatus according to claim 1, wherein a high frequency power of 13.56 MHz or 13.56 MHz is applied.