JPH10317174A - Reactive ion etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute reactive ion etching without the occurrence of an etch stop in microprocessing by arranging parallel multiple wound high-frequency coils on the outer periphery of a cylindrical side wall consisting of a dielectric substance and converting gas mainly composed of gaseous halogen introduced from an upper part to plasma. SOLUTION: A cylindrical side wall 2 of a plasma generating section 1a of a vacuum chamber 1 is formed of a dielectric substance and a double wound high-frequency antenna 3 is arranged on the outer periphery thereof to convert the gas mainly composed of the gaseous halogen supplied from a gas introducing port 6 disposed at a top plate 5 is converted to the plasma. The etchant, such as positive ions, formed by this plasma is drawn out by a substrate electrode 7 which is arranged in a lower part and on which a high-frequency bias voltage is impressed and is bombarded to a substrate arranged thereon to effect reaction. The substrate is etched by prescribed patterns. As a result, the adhesion of deposits on the side wall 2 is suppressed and the pattern etching of submicron holes is made possible without the etch stop in microprocessing of <=0.3 μm.

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 As shown in FIG. 6, an inductively coupled discharge etching apparatus used in the prior art includes an antenna B composed of a single coil for generating discharge plasma in a vacuum chamber A and a vacuum chamber A. A high frequency power is applied from a high frequency power supply C for plasma generation to the high frequency antenna B, and an etching gas mainly composed of a halogen-based gas is introduced from the vicinity near the upper top plate A2 through a flow rate controller. And the gas is evacuated to vacuum chamber A
To form a plasma at a low pressure, decompose the introduced gas, actively use the generated atoms, molecules, radicals, and ions, and apply a high-frequency electric field from a high-frequency power source E to a substrate electrode D in contact with the plasma. The substrate mounted on the substrate electrode D is etched.

FIG. 7 shows a magnetic neutral ray discharge etching apparatus proposed by the present inventors in Japanese Patent Application Laid-Open No. 7-263192. The previously proposed device is a three-dimensional device mounted outside the dielectric cylindrical wall A1 at the top of the vacuum chamber A.
A magnetic neutral line I is formed inside the vacuum chamber A by the two magnetic field coils F, G, and H. Along this magnetic neutral line I, a single antenna B disposed inside the intermediate magnetic field coil G is formed. A ring-shaped plasma is formed by applying a high-frequency electric field from the high-frequency power source C for the antenna. The etching gas is introduced from around the upper top plate A2 through the flow controller, and the pressure is controlled by the aperture ratio of the contactance valve. High-frequency power is applied from a high-frequency power source E for bias to a substrate electrode D below the vacuum chamber A.

A magnetic neutral beam discharge etching apparatus having such a configuration and shown in FIG. 7 will be described. The etching gas is introduced from the vicinity of the upper flange of the vacuum chamber A, and plasma is formed by applying high-frequency power to a single antenna B disposed between the outside of the dielectric cylindrical wall A1 and the intermediate magnetic field coil G. Then, the introduced gas is decomposed. A high frequency power for bias is applied from a high frequency power supply for bias E to a substrate electrode D below the vacuum chamber A. The substrate electrode D, which is in a floating state due to the blocking capacitor, has a negative self-bias potential, and positive ions in the plasma are attracted to etch the substance on the substrate.

In the magnetic neutral wire discharge, a high-density plasma is formed at a portion of the magnetic neutral wire I formed in a ring shape in a vacuum, so that an induction formed along the ring magnetic neutral wire H is formed. The electric field is used effectively. By this method, a plasma having a charged particle density of 10 ¹¹ cm ^{−3 is} easily formed.

However, it has been found that when the method is applied to etching of a resist pattern having a fine structure using a halogen-based gas, there is a disadvantage that etching of fine holes cannot be sufficiently performed.

[0007]

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 the substrate material is etched. The shape control is becoming more important with the progress of the technology. 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 fine processing 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 for the etchant, the pores having a width of 0.3 μm or less are filled with the protective substance, so-called an etch stop occurs, and cannot be removed. Conversely, if the protective material is too low, the etchant will cut the sidewalls,
ng occurs and the 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 generating 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. At this time, the plasma is excited and maintained by the induced electric field in the azimuthal direction emitted from the antenna and the electric field formed by the potential of the antenna itself. The former discharge component is also called an H component, and the latter discharge component is called an E component. The E discharge is a discharge component due to so-called electrostatic coupling. The magnetic neutral discharge uses an induction electric field formed along the magnetic neutral line to form a high-density plasma in the magnetic neutral line formed in a ring in vacuum. 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. 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 those using a circular pipe. 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 the wall surface of the vacuum chamber is sputtered, an SiO compound or a substance polymerized on the surface, which is not desirable for fine processing, precipitates in the plasma and causes an etch stop. Also, 30
When a large-diameter plasma generation chamber corresponding to a wafer having a diameter of 0 mm is used, the diameter of a vacuum chamber portion made of a dielectric increases, and the antenna diameter also increases accordingly. As a result, the impedance of the antenna becomes high and the matching on the circuit cannot be obtained. Even if the matching is obtained, the antenna potential becomes undesirably high, and similarly, the wall surface of the dielectric material is ion-sputtered.

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

[0010]

In order to achieve the above object, a reactive ion etching apparatus according to the present invention is configured such that a plasma generating antenna is wound in multiple parallel turns to apply high frequency power.

[0011]

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 in which a substrate is placed on an electrode by applying a voltage, a part of a vacuum chamber is formed of a cylindrical dielectric, and a cylindrical vacuum formed of the dielectric is formed. A substrate electrode for applying a high-frequency bias is provided below the chamber portion, and a high-frequency coil for generating plasma outside the cylindrical vacuum chamber portion is provided. It is characterized in that were arranged in parallel multi-turn.

According to another embodiment of the present invention, there is provided 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. It has a plasma generating means provided with a high-frequency coil for generating a discharge plasma in the magnetic neutral line by applying an alternating electric field along the neutral line. Introduced to
It forms plasma at low pressure and decomposes the introduced gas,
Active use of the generated atoms, molecules, radicals, and ions to apply an alternating electric field or high-frequency electric field to the substrate electrode in contact with the plasma to etch the substrate mounted on the electrode. In the ion etching apparatus, a part of the vacuum chamber is formed of a cylindrical dielectric,
A plurality of magnetic field coils forming an annular magnetic neutral line are arranged inside the vacuum chamber portion outside the cylindrical vacuum chamber portion made of a dielectric, and a high frequency bias is applied to a lower portion of the cylindrical vacuum chamber portion. A substrate electrode to be applied is provided, and a parallel multiplex high-frequency coil for generating plasma is arranged between the magnetic field coil and the cylindrical vacuum chamber portion made of a dielectric material in the same plane as the magnetic neutral line. It is characterized by doing.

[0013]

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 the reactive ion etching apparatus of the present invention, which is configured as an inductive coupling type. In the illustrated etching apparatus, 1
Is a vacuum chamber having an upper plasma generating section 1a and a substrate electrode section 1b, and the substrate electrode section is provided with an exhaust port 1c. The plasma generating section 1a has a cylindrical side wall 2. Outside the side wall 2, a double-winding antenna 3 for generating plasma in the vacuum chamber 1 is disposed. Connected to the high frequency power supply 4,
Discharge plasma is generated in the plasma generation section 1a in the upper part of the vacuum chamber 1. The top plate 5 of the plasma generating section 1a at the top of the vacuum chamber 1 is hermetically fixed to the upper flange of the side wall 2, and a gas inlet 6 for introducing an etching gas into the vacuum chamber 1 is provided around the top plate 5.
The gas inlet 6 is connected to an etching gas supply source via a gas supply passage (not shown) and a gas flow controller for controlling the flow rate of the etching gas. Further, a substrate electrode 7 is provided in the substrate electrode portion 1b below the plasma generating portion 1a of the vacuum chamber 1 via an insulator member 8, and the substrate electrode 7 is connected to a high frequency power supply 9 for applying an RF bias. ing.

FIG. 2 shows another embodiment of the reactive ion etching apparatus according to the present invention. In this case, the apparatus is configured as a magnetic neutral discharge type. Parts corresponding to those of the apparatus of FIG. 1 are denoted by the same reference numerals. In this embodiment, the cylindrical side wall 2 of the plasma generating section 1a on the upper part of the vacuum chamber 1 is made of a dielectric material.
Outside, three magnetic field coils forming magnetic field generating means for forming a magnetic neutral line in the vacuum chamber-1
The magnetic neutral wire 13 is formed in the plasma generating section 1a at the upper part of the vacuum chamber 1 provided with 10, 11, and 12. The double wound antenna 3 for plasma generation has three magnetic field coils 10 to 12
As a result, an alternating electric field is applied along the magnetic neutral line 13 formed in the plasma generating section 1a in the upper part of the vacuum chamber 1 so as to generate discharge plasma in the magnetic neutral line.

In the apparatus shown in FIGS. 1 and 2 configured as described above, the plasma generating high-frequency power supply 4 (13.56 MHz)
Power of 2.OkW, substrate bias high frequency power supply 9 (800kHz)
Power of 500 W, Ar 90 sccm (90%), C ₄ F _{8 10} sccm (1
0%) and etched under a pressure of 3 mTorr, it was possible to etch the silicon oxide film in a substantially vertical shape with a diameter of 0.3 μm without an etch stop. In the etching under the same conditions in the conventional apparatus configuration, the etch stop occurred at a depth of about 0.5 μm, although there were some differences depending on the pattern width. Substances that adhere to the wall include
CF, CF ₂ , CF ₃ , C ₂ F ₂ , C ₂ F ₄ , C ₂ F ₅ , C
_{3 F 5, C 3 F 6} , advanced a compound or further decomposition of equal C
₂ F _X, there is a C ₃ F _X, compounds such as _{C 4 F X (x = 1~2} ). These compounds adhere to the wall to form a polymer film. If the surface potential of the antenna 3 is high, ion bombardment occurs, and these compounds and wall materials are sputtered and deposited in the gas phase as a substance that is 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 suppressed, it is sputtered at a low potential and again becomes a useful radical such as CF, CF ₂ , CF _3, etc. Jumps in and conversely becomes 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 illustrated embodiment, an example in which the present invention is applied to an etching apparatus has been described, but it is needless to say that a similar effect can be expected even when a plasma CVD apparatus is used. Further, in the illustrated embodiment, a parallel double-wound antenna is used, but as the number of turns increases, the impedance decreases accordingly, the potential generated on the antenna surface can be suppressed lower, and the potential in the center of the vacuum chamber is reduced. The induction electric field can be generated more effectively.

FIGS. 3 to 5 show a radial induction electric field in the plane of a conventional single-wound antenna and a radial induction electric field in an intermediate position of the parallel double-wound antenna according to the present invention. 1 is the position of the antenna. In FIG. 4, the parallel double-wound antenna of the present invention is at the position of Z = 0, whereas the position of the conventional single-wound antenna is flush with the antenna. The induced electric field near the antenna is 1
There is no significant difference between the heavy winding and the parallel double winding, but a difference occurs 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 of the antenna for plasma generation can be reduced and the inductive coupling component can be effectively increased. As a result, as compared with the conventional single-wound antenna, spatter on the inner wall of the dielectric inside the antenna is suppressed, and plasma can be effectively formed and maintained without lowering the plasma density. Therefore, since the electrostatic coupling component is reduced, the antenna diameter can be increased, and
Higher frequency power can be supplied by the reduced impedance. In addition, since the surface potential of the antenna for plasma generation decreases, Si which is not
Precipitation of an O compound or a substance polymerized on the surface by sputtering into plasma can be suppressed to a low level.

[0018]

As described above, in the reactive ion etching apparatus according to the present invention, since the plasma generating antenna is configured to apply multiple high-frequency power in parallel multiple turns, the 0.3 μm width is applied. In the following micromachining, high frequency power is applied to the parallel multiple winding antenna,
By etching in an appropriate power region, pattern etching of submicron holes can be performed without an etch stop. Therefore, it greatly contributes to the 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 diagram showing a calculation position of a vector potential in the etching apparatus according to the present invention.

FIG. 4 is a graph showing a radial distribution of a vector potential.

FIG. 5 is a graph showing the radial distribution of the vector potential in the Z direction at R = 0.8.

FIG. 6 is a schematic diagram showing a conventional inductively coupled discharge type etching apparatus.

FIG. 7 is a schematic diagram showing a conventional magnetic neutral beam discharge etching apparatus.

[Explanation of symbols]

 1: vacuum chamber 2: cylindrical side wall 3: double winding high frequency antenna 4: high frequency power supply for plasma generation 5: top plate 6: gas inlet 7: substrate electrode 8: insulator member 9: high frequency power supply 10 to 12: Magnetic field coil 13: magnetic neutral wire

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

Claims (2)

[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 an inductively coupled discharge type reactive ion etching apparatus, a part of a vacuum chamber is composed of a cylindrical dielectric, and a substrate electrode for applying a high-frequency bias is provided below a cylindrical vacuum chamber part composed of the dielectric. A high frequency coil for generating plasma is arranged in parallel multiple winding outside the cylindrical vacuum chamber portion. Reactive ion etching equipment. 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, a part of a vacuum chamber is formed of a cylindrical dielectric, and a part of the vacuum chamber is formed outside the cylindrical vacuum chamber formed of the dielectric. A plurality of magnetic field coils forming an annular magnetic neutral line are arranged in this vacuum chamber portion, and a substrate electrode for applying a high-frequency bias is provided at a lower portion of the cylindrical vacuum chamber portion, and in the same plane as the magnetic neutral line. A reactive ion etching apparatus characterized in that a parallel multiple high-frequency coil for generating plasma is arranged between a cylindrical vacuum chamber portion made of a dielectric and a magnetic field coil.