JPH1140544A - Reactive ion etching equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form plasma of high evenness for highly even etching, by allocating a plasma generating high frequency coil in parallel, providing high frequency electric power introduction and leading-out parts for the high frequency coil in symmetric about a center, and applying a high frequency electric power through a phase control coupling part. SOLUTION: High frequency antennas 3 for generating plasmas in a vacuum chamber 1 are symmetrically allocated in parallel, and connected to a plasma generating high frequency power source 5 through a phase control coupling part 4, for generating a discharge plasma in a plasma generating part 1a at the upper part of the vacuum chamber 1. A top plate 6 of the plasma generating part 1a at the upper part of the vacuum chamber 1 is tightly attached, sealed up, to an upper part flange of a side wall 2, while a gas introduction opening 7 for introducing etching gas in the vacuum chamber 1 is provided at a periphery part of the top plate 6. The gas introduction opening 7 is connected to an etching gas supply source through a gas supply channel and a gas flow rate controller for controlling the flow rate of etching gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As shown in FIG. 5, an inductively coupled discharge etching apparatus used in the prior art includes an antenna B having a single coil for generating discharge plasma in a vacuum chamber A, as shown in FIG. 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 transferred to the vacuum chamber A
To form a plasma at a low pressure, decompose the introduced gas, actively utilize the generated atoms, molecules, radicals, and ions, and apply a high-frequency electric field from a high-frequency power source E to the substrate electrode D in contact with the plasma. The substrate mounted on the substrate electrode D is etched.

FIG. 6 shows a magnetic neutral beam 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 shown in FIG. 6 having such a configuration 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 this case, a single-turn coil is generally used as the high-frequency antenna coil B. If the diameter is smaller than 300φ, double winding is possible, but if the substrate electrode is larger than 8 inches, the plasma source portion becomes large to obtain etching uniformity. When the diameter of the high-frequency antenna coil B becomes larger than 300φ, the high-frequency antenna coil B
Therefore, the matching condition cannot be obtained unless a single antenna is used. Therefore, 3OOφ
In an inductively coupled discharge device having a larger dielectric partition, a single antenna is used.

In the magnetic neutral wire discharge, a high-density plasma is formed in 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.

[0007]

If the antenna diameter is larger than 300φ, the matching condition cannot be obtained with a multiplex serial antenna because the antenna inductance increases. Therefore, a single antenna is generally used in an inductively coupled discharge device having a dielectric partition larger than 300φ. When a single antenna is used, the plasma uniformity at the power introduction / output portion to the antenna and the substrate etching uniformity become a problem. Previous experiments have shown that the density distribution of plasma when power is applied to the antenna is lower in the power input / output unit because there is a gap in the power input / output unit. It has also been pointed out by plasma simulations (Tadokoro, Okiokawa, Nabeda, Ito, Nakano, Petrovic, Makabe; Proceedings of the 44th JSAP Related Conference, 30p-N-7, (1997 )reference).

Accordingly, an object of the present invention is to provide a reactive ion etching apparatus which can solve the above-mentioned problems and can form a highly uniform plasma, thereby enabling a highly uniform etching. I have.

[0009]

In order to achieve the above object, in a reactive ion etching apparatus according to the present invention, antennas are arranged in parallel, and power introduction and output sections for each antenna are provided symmetrically with respect to the center. In order to control the phase up to the power introduction unit, the position of the branch unit can be adjusted, and high-frequency power is applied to the antennas arranged in parallel.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to one embodiment of the present invention, there is provided a plasma generator having a high-frequency coil for generating discharge plasma in a vacuum chamber and mainly comprising a halogen-based gas. The gas is introduced into the vacuum chamber, and the plasma is formed at a low pressure and the introduced gas is decomposed. The generated atoms, molecules, radicals, and ions are actively used, and the alternating or high-frequency electric field is applied to the substrate electrode in contact with the plasma. In a reactive ion etching apparatus that etches a substrate placed on an electrode by applying a voltage, a wall of a vacuum chamber portion provided with a plasma generator is formed of a cylindrical dielectric. A substrate electrode for applying a high-frequency bias is provided below the vacuum chamber portion made of The high-frequency coil for generating a plasma is arranged in parallel, provided the respective high-frequency power supply, deriving unit for high-frequency coil to the position of the center of symmetry, it is characterized by applying high-frequency power through a phase control coupling unit.

According to another embodiment of the present invention, a magnetic field generating means for forming an annular magnetic neutral line which is a position of a magnetic field continuously present in a vacuum chamber and having zero magnetic field, and the magnetic neutral line And a high-frequency coil for generating a discharge plasma in the magnetic neutral line by applying an alternating electric field along with a plasma generator having a halogen-based gas introduced into the vacuum chamber. Forming plasma at low pressure and decomposing the introduced gas, utilizing the generated atoms, molecules, radicals and ions positively, applying an alternating electric field or a high-frequency electric field to the substrate electrode in contact with the plasma and placing it on the electrode In a reactive ion etching apparatus that etches a substrate that has been etched, a wall of a vacuum chamber portion provided with a plasma generator is formed of a cylindrical dielectric and a plurality of walls are formed outside the dielectric. A magnetic field coil is arranged to form an annular magnetic neutral line in the vacuum chamber, and a substrate electrode for applying a high-frequency bias is provided below the vacuum chamber part made of a cylindrical dielectric, and the same as the magnetic neutral line High-frequency coils for generating plasma are arranged in parallel between the dielectric vacuum wall and the magnetic field coil in the plane, and the respective high-frequency power introduction and output parts are provided at centrally symmetric positions, and through the phase control coupling part It is characterized in that high frequency power is applied.

[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 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, which includes an upper plasma generating section 1a and a substrate electrode section 1b, and the substrate electrode section 1b is provided with an exhaust port 1c. The plasma generating section 1a has a cylindrical side wall 2. Outside the side wall 2, a high-frequency antenna 3 for generating plasma in the vacuum chamber 1 is arranged. It is connected to a high frequency power supply 5 for plasma generation via a control coupling section 4 so as to generate a discharge plasma in a plasma generation section 1a above the vacuum chamber 1. The top plate 6 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 7 for introducing an etching gas into the vacuum chamber 1 is provided around the top plate 6. The gas inlet 7 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. A substrate electrode 8 is provided in the substrate electrode portion 1b below the plasma generating portion 1a of the vacuum chamber 1 via an insulator member 9, and the substrate electrode 8 is connected to a high-frequency power source 10 for applying an RF bias. ing.

FIG. 2 shows another embodiment of the reactive ion etching apparatus of 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 at the upper part of the vacuum chamber 1 is made of a dielectric material, and outside the side wall 2 and outside the high frequency antenna 3 arranged in parallel and symmetrically, a vacuum chamber is provided. -1, three magnetic field coils 11, 12, 13 constituting magnetic field generating means for forming a magnetic neutral line are provided, and a magnetic neutral line is provided in a plasma generating portion 1a in an upper part of the vacuum chamber 1. Form 14. The high-frequency antenna 3 for plasma generation applies an alternating electric field along a magnetic neutral line 14 formed in the plasma generating section 1a at the upper part of the vacuum chamber 1 by three magnetic field coils 11 to 13 to apply the magnetic neutral line. To generate discharge plasma.

FIG. 3 is an enlarged cross-sectional view of the parallel symmetrically arranged antenna 3, and FIG. 4 is a schematic diagram of power introduction. When a single antenna is used, since there is a gap in the power input / output unit, power input to the plasma in that portion is weak, and the plasma density is low. However, as shown in FIG. 3, by supplying high-frequency power to the two antennas from opposite positions, it is possible to compensate for a decrease in plasma density in each power input / output unit. At this time, the important thing is 2
That is, the phase is controlled so as not to cause a phase shift between the antennas 3. The simplest method of phase control is to make the wiring length from the high frequency power supply to the antenna the same. However, since there is a stray capacitance as a practical problem, it is difficult to make the impedance in the wiring the same even if the wiring length is the same. Therefore, the impedance matching of each antenna unit can be adjusted by the capacitor and the inductance coil in the branch unit, that is, the phase control coupling unit 4. As a result, the uniformity of the plasma density is improved as compared with the conventional single-wound antenna.

In the apparatus shown in FIG. 2 configured as described above, the power of the plasma generating high-frequency power supply 5 (13.56 MHz) is
2.OkW, power of substrate bias high frequency power supply 10 (800kHz)
When 100 W, Ar 90 sccm (85%) and C ₄ F _{8 10} sccm (15%) were introduced and etched under a pressure of 3 mTorr, 750 nm was obtained.
It was found that an etching rate of / min was obtained and a very uniform etching distribution of ± 2% was obtained. When a single antenna is used, 560 nm / min ± 5 under the same conditions
%. It is considered that the increase in the etch speed is due to the fact that when power is applied to the two antennas 3 arranged in parallel and symmetrically, the impedance is reduced, the high-frequency power is increased, and the induction electric field is formed efficiently.

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 the same effect can be expected even when a plasma CVD apparatus is used.

[0017]

As described above, in the reactive ion etching apparatus according to the present invention, high-frequency coils for generating plasma are arranged in parallel, and the high-frequency power introduction / derivation sections for the high-frequency coils are mainly arranged. Since it is configured at a symmetrical position and configured to apply high-frequency power through the phase control coupling unit, by applying high-frequency power to the parallel symmetrically arranged antenna and controlling the phase between the antennas,
By etching in an appropriate power region, highly uniform plasma can be formed, and highly uniform etching can be performed. Accordingly, there is provided an apparatus which can greatly contribute 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 an enlarged partial view showing a configuration of a main part of the etching apparatus according to the present invention.

FIG. 4 is a schematic diagram showing a method of introducing power to a parallel symmetrically arranged antenna in the etching apparatus according to the present invention.

FIG. 5 is a schematic diagram showing a conventional inductively coupled discharge type etching apparatus.

FIG. 6 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: phase control coupling part 5: high frequency power supply for plasma generation 6: top plate 7: gas inlet 8: substrate electrode 9: insulator member 10: High frequency power supply 11-13: Magnetic field coil

Claims (2)

[Claims] 1. A plasma generator 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, and the plasma is generated in a low pressure chamber. Forming and decomposing the introduced gas, positively utilizing the generated atoms, molecules, radicals and ions, applying an alternating electric field or a high-frequency electric field to the substrate electrode in contact with the plasma to etch the substrate placed on the electrode In a reactive ion etching apparatus, a wall of a vacuum chamber portion provided with a plasma generator is formed of a cylindrical dielectric, and a substrate for applying a high-frequency bias to a lower portion of the vacuum chamber portion formed of the cylindrical dielectric An electrode is provided, and a high-frequency coil for generating plasma is arranged outside the vacuum wall of the vacuum chamber made of a cylindrical dielectric. A reactive ion etching apparatus which is arranged in a row, a high frequency power introduction / derivation unit for a high frequency coil is provided at a centrally symmetric position, and high frequency power is applied through a phase control coupling unit. 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 applying an alternating electric field along the magnetic neutral line to produce the magnetic field. It has a plasma generator equipped with a high-frequency coil for generating discharge plasma on the neutral wire, and introduces gas mainly composed of halogen-based gas into the vacuum chamber to form plasma at low pressure and introduce gas. Reactive ion etching that decomposes and positively utilizes the generated atoms, molecules, radicals, and ions, and applies an alternating electric field or a high-frequency electric field to the substrate electrode in contact with the plasma to etch the substrate placed on the electrode In the apparatus, a wall of a vacuum chamber portion provided with a plasma generator is formed of a cylindrical dielectric, and a plurality of magnetic field coils are arranged outside the dielectric to form a vacuum chamber. A ring-shaped magnetic neutral line is formed in the bar, and a substrate electrode for applying a high-frequency bias is provided below the vacuum chamber portion made of a cylindrical dielectric. A high-frequency coil for generating plasma is arranged in parallel between the vacuum wall and the magnetic field coil. Characteristic reactive ion etching equipment.