JPH10317175A - Reactive ion etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute reactive ion etching without causing an etch stop in microprocessing of a substrate on a substrate electrode by arranging parallel multiple wound high-frequency coils longitudinally on the disk-shaped dielectric substance at the apex of a vacuum chamber and converting gas mainly composed of gaseous halogen to plasma with a low pressure. SOLUTION: The apex of a vacuum chamber 1 is provided with the flat plate type dielectric barrier 2 and the parallel double wound high-frequency coils 3 for plasma generation are arranged longitudinally thereon. The substrate electrode 5 on which a substrate is placed is arranged on the lower part thereof. The reactive gas mainly composed of the gaseous halogen consisting of C4 F8 and Ar, etc., is introduced into this vacuum chamber 1 from a gas introducing port 8. An induction electric field is formed by the high-frequency coils 3 and negative bias potential is applied on the substrate electrode 5. As a result, the gas described above is converted to the plasma and cracked and the formed radicals, positive ions, etc., are drawn out and are bombarded against the substrate, by which the substrate is etched. At this time, the microprocessing of about >=0.3 μm in width is made possible without the etch stop by suppressing sputtering of the side wall, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a reactive ion etching apparatus for etching a substance on a semiconductor, an electronic component, or another substrate using plasma.

[0002]

2. Description of the Related Art The inventors of the present invention have previously proposed in Japanese Patent Application No. 7-217965 a flat permanent magnet type magnetic neutral beam etching apparatus as shown in FIG. 5 of the accompanying drawings as a permanent magnet type etching apparatus. did. In the device proposed earlier,
A magnetic neutral line is formed inside the vacuum chamber A by the two permanent magnets C and D mounted on the dielectric B on the upper part of the vacuum chamber A, and two permanent magnets C are formed along the magnetic neutral line. , D, a single antenna E having a circular cross section (diameter of about 10 mm) is arranged, a gas is introduced, and a high-frequency electric field is applied to this antenna to form a ring-shaped plasma. It was also proposed to use a flat antenna having a width of about 10 mm in place of the antenna having a circular cross section. In this case, if the width and the diameter were almost the same, the characteristics of the plasma formed were almost the same. Further, a high frequency power for bias is applied to the lower substrate electrode F from a high frequency power supply for bias G. There is also known an inductively coupled discharge type etching apparatus in which two permanent magnets C and D for forming a magnetic neutral line are removed from the configuration shown in FIG.

The operation of the magnetic neutral beam discharge etching apparatus shown in FIG. 1 will be described. The etching gas is introduced from a gas inlet H provided near the upper flange of the vacuum chamber A, and a high-frequency power is applied to an antenna E installed on the dielectric disk B to form a plasma to decompose the introduced gas. You. A high frequency power for bias is applied to the lower substrate electrode F from a high frequency power supply for bias G. The substrate electrode F, which is in a floating state by the blocking capacitor I, has a negative self-bias potential, and positive ions in the plasma are attracted to etch the substance on the substrate. At this time, the plasma is excited and formed by the induced electric field in the azimuthal direction radiated from the antenna E and the potential of the antenna E itself. The former discharge component is also called H discharge, and the latter discharge component is called E discharge. E
The discharge is a discharge due to so-called electrostatic coupling. In the magnetic neutral wire discharge, an induced electric field formed along the ring magnetic neutral wire is effectively used to form a dense plasma at the magnetic neutral wire formed in a ring in vacuum. And a plasma mainly composed of an H discharge component. This is achieved by using a pipe having a circular cross section which can reduce the capacity between the plasma and the antenna. Up to now, pipes having a diameter of 8 to 10 mm have been used as antennas. Even if a flat plate having a diameter approximately equal to the cross-sectional diameter of the pipe is used, the electrostatic coupling component is small and the inductive coupling component is large, so that the characteristics of the plasma are almost the same as when a pipe having a circular cross section is used. With this method, 1O ¹¹ cm easily
A plasma with a charged particle density of ^-3 is formed.

[0004]

In the etching, a substrate material is gasified by a reaction with the substrate material by irradiating the substrate with radicals and ions having high reactivity, and etching is performed. Accordingly, shape control has become more important. For this purpose, in addition to the etchant, a substance that adheres to the inner wall surface of the micropore and protects the side wall not exposed to ions must be generated in the plasma. In microfabrication with a width of 0.3 μm or less, the relative concentration of the etchant and the protective substance and the relative amount reaching the inside of the hole are important. If the amount of the protective substance becomes too large with respect to the etchant, the fine pores having a width of 0.3 μm or less are filled with the protective substance, so that a so-called etch stop occurs, and the fine pores cannot be removed. On the other hand, if the amount of the protective material is too small, the side wall is shaved by the etchant, causing bowing, and a desired shape cannot be obtained.

In the conventionally used inductively coupled discharge etching apparatus and magnetic neutral line discharge etching apparatus, high frequency power is applied to an antenna for forming plasma and an electrode in an electrically floating state for generating a bias voltage. Is done. When a halogen-based gas is introduced and plasma is formed, gas molecules are decomposed by plasma, and an etchant or a substance which is easily polymerized is generated. Magnetic Neutral Discharge uses an induction electric field formed along a ring-shaped magnetic neutral line to form a dense plasma in the ring-shaped magnetic neutral line in vacuum. And the plasma is mainly composed of H discharge components. This is achieved by using a pipe having a circular cross section that can reduce the capacitance between the plasma and the antenna. However, since it also includes an electrostatic coupling component, when the antenna power is increased, the potential of the antenna surface increases, and the dielectric wall surface of the vacuum chamber inside the antenna is ion-sputtered. When a large-diameter plasma generation chamber corresponding to a wafer having a diameter of 300 mm is used, the thickness of the dielectric partition at the top of the vacuum chamber is increased, and accordingly, the input power is increased. As a result, the potential generated on the antenna surface becomes undesirably high, and the dielectric wall of the vacuum chamber is subjected to ion sputtering. When the wall surface is sputtered, an SiO compound or a material polymerized on the surface, which is not desirable for fine processing, precipitates in the plasma and causes an etch stop.

Accordingly, an object of the present invention is to provide a reactive ion etching apparatus capable of solving the above-mentioned problem and performing etching without generating an etch stop in fine processing of 0.3 μm or less in width.

[0007]

In order to achieve the above object, in a reactive ion etching apparatus according to the present invention, an effective induction electric field is generated by applying a high frequency power by arranging a plasma generating antenna in parallel multiple turns. It is configured so that it can be formed.

[0008]

According to one embodiment of the present invention, there is provided a plasma generating means provided with a high-frequency coil for generating discharge plasma in a vacuum chamber, and mainly comprises a halogen-based gas. A gas is introduced into a vacuum chamber to form a plasma at a low pressure and decompose the introduced gas.The generated atoms, molecules, radicals, and ions are actively used, and an alternating electric field or a high-frequency electric field is applied to a substrate electrode in contact with the plasma. In an inductively coupled discharge type reactive ion etching apparatus for applying a voltage to etch a substrate placed on an electrode, the top of the vacuum chamber is made of a disk-shaped dielectric, and the top of the vacuum chamber made of the dielectric is formed. A feature is that a high frequency coil of a parallel parallel multiplex for generating a discharge plasma is arranged above.

According to another embodiment of the present invention, there is provided a magnetic field generating means for forming an annular magnetic neutral line at a position of zero magnetic field continuously present in a vacuum chamber, A plasma generating means comprising a high-frequency coil for generating a discharge plasma in this magnetic neutral line by applying an alternating electric field along the neutral line, and a gas mainly containing a halogen-based gas is placed in a vacuum chamber. Introduce, form plasma at low pressure, decompose the introduced gas, and actively use the generated atoms, molecules, radicals and ions,
In a magnetic neutral line discharge type reactive ion etching apparatus that applies an alternating electric field or a high-frequency electric field to a substrate electrode in contact with plasma and etches a substrate mounted on the electrode,
The top of the vacuum chamber is made of a disc-shaped dielectric, and a small disk or donut is formed on the top of the vacuum chamber made of the dielectric to form a circular magnetic neutral line in the vacuum chamber. And a magnetic field generating means comprising a permanent magnet having a larger inner diameter than the permanent magnet and a magnetic neutral line formed substantially corresponding to an intermediate position between the two permanent magnets. In addition, a parallel multiplex high-frequency coil for generating discharge plasma is provided. In this case, parallel high-frequency coils for generating discharge plasma are arranged vertically or horizontally.

[0010]

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 of an etching apparatus according to the present invention configured as an inductively coupled discharge type. In the illustrated apparatus, reference numeral 1 denotes a cylindrical vacuum chamber forming a process chamber having an exhaust port 1a, and the upper surface thereof is covered with a flat dielectric partition 2. On the outer surface of the flat dielectric partition 2, a parallel double-winding high-frequency coil 3 for plasma generation is vertically arranged, and the parallel double-winding high-frequency coil 3 is connected to a high-frequency power supply 4 for plasma generation.
A high-frequency power is applied from a high-frequency power supply 4 for plasma generation to generate discharge plasma in the vacuum chamber 1. A substrate electrode 5 is provided in the vacuum chamber 1 via an insulator member 6, and the substrate electrode 5 is connected to a high-frequency power source 7 for applying an RF bias. Reference numeral 8 denotes a gas inlet.

FIG. 2 shows another embodiment of the etching apparatus according to the present invention configured as a magnetic neutral discharge type. In the illustrated apparatus, reference numeral 11 denotes a cylindrical vacuum chamber forming a process chamber having an exhaust port 11a, and the upper surface thereof is covered with a flat dielectric barrier 12. A disk-shaped or donut-shaped permanent magnet 13 and a donut-shaped plate-shaped permanent magnet 14 having an inner diameter larger than that of the permanent magnet 13 and having the same polarity as that of the permanent magnet 13 are concentrically provided on the outer surface of the flat dielectric partition 12. These permanent magnets 13 and 14 constitute a magnetic field generating means for forming a magnetic neutral line in the vacuum chamber 11. Between the disk-shaped or donut-shaped permanent magnet 13 and the donut-shaped plate-shaped permanent magnet 14, a parallel double-turned plasma generating high-frequency coil 15 is vertically arranged.
Is connected to the high frequency power supply 16 for plasma generation, and the permanent magnet 1
An alternating electric field is applied along the magnetic neutral line formed in the vacuum chamber 11 by 3 and 14 to generate discharge plasma in the magnetic neutral line. Further, a substrate electrode 17 is provided via an insulator member 18 at a position parallel to and separated from the surface of the magnetic neutral wire formed in the vacuum chamber 1,
This substrate electrode 17 is connected to a high-frequency power supply 19 for applying an RF bias. Further, a gas inlet 20 is provided near the inner peripheral portion of the flat dielectric partition 12 of the vacuum chamber 11.

FIG. 3 shows a modification of the magnetic neutral beam discharge type etching apparatus shown in FIG. In this example, the parallel double-turned plasma generating high-frequency coil 15 provided between the disk-shaped or donut-shaped permanent magnet 13 and the donut-shaped plate-shaped permanent magnet 14 is arranged laterally, and the other components are It is substantially the same as the case of FIG.

Using the apparatus having the structure shown in FIG. 3, the power of the plasma generating high-frequency power supply 16 (13.56 MHz) is set to 2.OkW, the substrate bias high-frequency power supply 19 (8OOkHz) is set to 1 kW, and the pressure is set to 3 mTor.
When r and argon were 80 sccm and C ₄ F ₈ was 20 sccm, the etching rate of the silicon oxide film was about 70 nm / min, and a vertical etching shape was obtained. In the etching under the same conditions in the conventional apparatus configuration, the etch stop occurred at a depth of 0.5 μm, although there were some differences depending on the pattern width.

The substances adhering to the wall include CF, CF ₂ ,
Compounds such as CF ₃ , C ₂ F ₂ , C ₂ F ₄ , C ₂ F ₅ , C ₃ F ₅ , C ₃ F ₆ , and further decomposed C ₂ F _X , C ₃ F _X , C ₄ F _X
(X = 1 to 2). These compounds adhere to the wall to form a polymer film. If the surface potential of the antenna, that is, the parallel high frequency coil 15 for plasma generation is high, ion bombardment occurs, and these compounds and wall materials are sputtered and deposited in the gas phase as substances that are not desirable for fine processing. However, when the ion bombardment is suppressed, not only the deposition of undesired substances is reduced, but even if the ion bombardment is not sufficiently suppressed, it is sputtered at a low potential and again becomes a useful radical such as CF, CF ₂ , or CF _3. It jumps into the gas phase, and on the contrary, is considered to be a desirable etchant. By effectively forming the induced magnetic field component in this manner, a submicron hole pattern can be etched without an etch stop even in a condition where an etch stop has occurred in the conventional apparatus configuration.

In the embodiment, the case where the present invention is applied to a magnetic neutral line discharge type etching apparatus has been exemplified. However, similar effects can be obtained with the inductively coupled discharge type etching apparatus shown in FIG. I have. A similar effect can be expected when an inductively coupled discharge CVD apparatus or a magnetic neutral discharge plasma CVD apparatus is used.

FIG. 4 shows that, when the same input high-frequency power is applied to the conventional single antenna and the parallel dual antenna as an example of the present invention, a radial vector transformer of Z = 0.5 in the Z direction. 2 shows a tension distribution. The vector potential is proportional to the induced electric field excited by the antenna, and the graph shows the peak value of each distribution and the value of the induced electric field. It can be seen that the induction electric field excited by the parallel dual antenna according to the present invention is much more efficient than the conventional one, and the plasma generation efficiency is improved. Also, as described in the section of the problem to be solved by the invention, when the same input high-frequency power is applied to the parallel multiplex antenna, the current flowing through the antenna is generally higher than that of the conventional single or multiple series antenna. And the ground potential difference can be reduced to several minutes. Thus, the present invention can effectively suppress unwanted electrostatic fields in the process. In FIG. 4, R = 1 is the position of the antenna. The difference between the induction electric field in the vicinity of the antenna and the single winding or the parallel double winding is small, but the difference is generated at a position farther from the antenna position.
In the case of the parallel double winding, an induced electric field component is formed farther away. This means that the surface potential can be lowered to effectively increase the inductive coupling component. As a result, compared to the conventional single-wound antenna,
In addition to suppressing spatter on the dielectric inner wall surface of the vacuum chamber inside the antenna, plasma can be formed and maintained effectively without lowering the plasma density. Therefore, since the electrostatic coupling component is reduced, it is possible to increase the antenna diameter and to supply high-frequency power because of the reduced impedance. Further, since the surface potential of the antenna is reduced, deposition of a SiO compound or a substance polymerized on the surface by sputtering into plasma, which is not desirable for fine processing, can be suppressed.

[0017]

As described above, in the reactive ion etching apparatus according to the present invention, an effective induction electric field can be formed by applying a high frequency power by arranging a plasma generating antenna in parallel multiple turns. Sub-micron hole pattern etching can be performed without an etch stop by etching in an appropriate power region. Therefore, the present invention greatly contributes to a reactive ion etching process used for processing semiconductors and electronic parts.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is a schematic diagram showing another embodiment of the present invention.

FIG. 3 is a schematic diagram showing a modification of the apparatus shown in FIG. 2;

FIG. 4 is a graph showing radial distributions of vector potentials in a conventional single-wound antenna and the parallel double-wound antenna of the present invention.

FIG. 5 is a schematic diagram showing a conventional magnetic neutral beam discharge etching apparatus.

[Explanation of symbols]

 1: cylindrical vacuum chamber 2: flat plate-type dielectric partition wall 3: parallel double-winding high-frequency coil for plasma generation 4: high-frequency power supply for plasma generation 5: substrate electrode 5 6: insulator member 7: high-frequency power supply 8: gas Inlet 11: Cylindrical vacuum chamber 12: Flat dielectric barrier 13: Disc-shaped or donut-shaped permanent magnet 14: Donut-shaped plate-shaped permanent magnet 15: High-frequency coil for parallel double winding plasma generation 16: For plasma generation High frequency power supply 17: Board electrode 18: Insulator material 19: High frequency power supply 20: Gas inlet

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Daijiro Uchida 2500 Hagizono, Chigasaki-shi, Kanagawa Japan Vacuum Engineering Co., Ltd.

Claims (4)

[Claims] 1. A plasma generating means having a high-frequency coil for generating discharge plasma in a vacuum chamber, wherein a gas mainly composed of a halogen-based gas is introduced into the vacuum chamber to form plasma at a low pressure. At the same time, the introduced gas is decomposed and the generated atoms, molecules, radicals, and ions are positively used, and an alternating electric field or a high-frequency electric field is applied to the substrate electrode in contact with the plasma to etch the substrate mounted on the electrode. In the inductively coupled discharge type reactive ion etching system, the top of the vacuum chamber is made of a disk-shaped dielectric, and the top of the vacuum chamber made of the dielectric is multiplexed in parallel to generate discharge plasma. A reactive ion etching apparatus, wherein a high-frequency coil is disposed. 2. A magnetic field generating means for forming an annular magnetic neutral line which is a position of zero magnetic field continuously present in a vacuum chamber, and an alternating electric field is applied along the magnetic neutral line. It has a plasma generating means provided with a high-frequency coil for generating discharge plasma in this magnetic neutral wire, and introduces a gas mainly composed of a halogen-based gas into a vacuum chamber to form plasma at a low pressure. Decomposes the introduced gas, actively utilizes the generated atoms, molecules, radicals, and ions, applies an alternating electric field or high-frequency electric field to the substrate electrode in contact with the plasma, and etches the substrate mounted on the electrode. In a radiation discharge type reactive ion etching apparatus, the top of a vacuum chamber is made of a disk-shaped dielectric, and a vacuum chamber is placed on the top of the vacuum chamber made of a dielectric. A magnetic field generating means including a disk-shaped or a donut-shaped permanent magnet having a small diameter for forming an annular magnetic neutral line and a permanent magnet having a larger inner diameter than the permanent magnet is provided substantially in the middle of the two permanent magnets. A reactive ion etching apparatus characterized in that a parallel multiple radio frequency coil for generating discharge plasma is provided on a top of a vacuum chamber at a position above a magnetic neutral line formed corresponding to the position. 3. The reactive ion etching apparatus according to claim 2, wherein parallel high-frequency coils for generating discharge plasma are vertically arranged. 4. The reactive ion etching apparatus according to claim 2, wherein parallel high-frequency coils for generating discharge plasma are arranged horizontally.