JP3224443B2 - Helicon wave plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus used for film formation or etching in a semiconductor process or the like, and more particularly to a plasma processing apparatus for generating helicon wave plasma and performing plasma processing using plasma particles by the plasma. The present invention relates to a helicon wave plasma processing apparatus for performing the following.

[0002]

2. Description of the Related Art For example, when an integrated circuit is formed on a semiconductor substrate, film formation, etching,
Substrate processing such as sputtering is performed. Conventionally, an RIE plasma processing apparatus, E
Although a CR plasma processing apparatus and the like are known, a helicon wave plasma processing apparatus which is the object of the present application is a plasma processing apparatus aiming to generate a higher density plasma, and is attracting attention as an effective apparatus for a semiconductor process. Have been. The helicon wave plasma device generates an initial plasma by electric field excitation by electromagnetic induction, a wave (helicon wave) generated in the plasma is excited by an applied magnetic field, and the energy of the electric field is reduced in the plasma by Landau damping of the wave. It has the characteristic that it can be effectively given to electrons and can generate high-density plasma even under a low magnetic field.
Plasma processing equipment using this helicon wave plasma
As described above, since high-density plasma can be obtained under a low magnetic field, there is an advantage that control is easy and the diameter of plasma processing can be increased. Hereinafter, a conventional configuration of the helicon wave plasma processing apparatus will be described. FIG. 3 is a schematic diagram showing a basic configuration of a conventional helicon wave plasma processing apparatus 30 configured as a plasma etching apparatus. In FIG. 3, an RF antenna 32 for applying a high-frequency power from a high-frequency power source 36 is arranged in the reaction chamber 31 at an outer peripheral position of a reaction chamber 31 formed of a dielectric material such as quartz glass in a cylindrical shape. A magnetic coil 3 for applying a magnetic field in the axial direction in the reaction chamber 31
3, 34 are arranged. A gas introduction port 35 is provided at an upper portion of the reaction chamber 31, and a process chamber 37 is provided at a lower portion thereof.
Communicates within. The reaction chamber 31 and the process chamber 37 form a vacuum container that is evacuated from the exhaust port 40. The mounting table 3 arranged in the process chamber 37
A substrate 39 to be processed is placed on the substrate 8. In the above configuration, the high-frequency power applied to the reaction chamber 31 generates a helicon wave in the magnetic field, and the processing gas introduced into the reaction chamber 31 from the gas introduction port 35 is converted into a helicon wave plasma by Landau damping of the wave. , To generate high density plasma. Plasma particles such as ions generated by the plasma are transported from the reaction chamber 31 to the process chamber 37 along the direction of the magnetic field, and the substrate 39 is efficiently etched.

[0003]

In the conventional helicon wave plasma processing apparatus, the magnetic coil is disposed as described above, and the RF antenna is disposed at a position where the magnetic field intensity is large. Helicon wave plasma is generated in a magnetic field. In the helicon wave plasma device, the plasma density also increases at a position where the magnetic field intensity is high, and the following problems occur when an RF antenna is provided at that position. Antenna circuit typically to include an inductor and a capacitor <br/> Sa, high frequency high voltage is generated in the RF antenna. In the conventional configuration, the position where the RF antenna is disposed is the position where high-density plasma is generated, so that electrons with a high response speed are accelerated and negative DC current is generated because the glass under the antenna is charged. Voltage occurs. Due to the potential difference between the DC potential and the plasma, ions in the plasma are accelerated toward the RF antenna, and as a result, the reaction chamber walls are sputtered by the ions. When the reaction chamber is formed of quartz, impurities such as silicon (Si) and oxygen (O) for performing plasma processing are released into the reaction chamber. For example, aluminum (A)
When the etching of l) is performed, an alumina (Al2O3) film is formed on the aluminum surface by the impurities, and the etching process is stopped by the strong alumina film. Conventionally, in order to suppress the formation of such an alumina film or the like, a measure has been taken by mixing a gas for suppressing the formation of alumina into the processing gas. Also, FIG.
Improved plasma that can solve various problems
2 shows a processing device. Details of this device will be described later.
However, even in this improved plasma processing system,
Many ions in the reactor collide with the reaction chamber walls,
There was a problem with the generation of pure products. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an antenna configuration that does not cause a gas to be mixed into a processing gas and that does not generate impurities in a reaction chamber due to the influence of a DC potential generated in an RF antenna. And a helicon wave plasma processing apparatus.

[0004]

Means adopted by the present invention to achieve the above object is to apply a high-frequency power from an RF antenna and a magnetic field from a magnetic coil to the vacuum vessel, In a helicon wave plasma processing apparatus for converting a processing gas introduced into a plasma into a plasma and subjecting an object to be processed disposed at a predetermined position in the vacuum vessel to plasma processing by the plasma, the RF antenna comprises a plasma.
Outside the vacuum generation area and substantially away from the vacuum vessel
A position, configured as a helicon wave plasma processing apparatus characterized by comprising disposed at a position capable of applying a high-frequency power to the plasma generation region.

[0005]

According to the present invention, high-frequency power is applied to the plasma generation region by electromagnetic induction the RF antenna from outside the generated area away Succoth from the vacuum chamber is a magnetic coil arrangement position high-density plasma is generated . Therefore, even if a high-frequency potential is generated in the RF antenna, the RF antenna is far from the plasma generation region where high-density plasma is generated, so that the number of plasma ions at the position where the RF antenna is provided is small.
The generation of impurities by sputtering quartz or the like forming a vacuum vessel (reaction chamber) is reduced.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. The following embodiments are examples embodying the present invention and do not limit the technical scope of the present invention. Here, FIG. 1 is a schematic diagram showing a configuration of a helicon wave plasma processing apparatus according to the actual施例schematic view, FIG. 2 is the invention showing a structure of a background to become helicon wave plasma processing apparatus of the present invention. In FIG. 1, a helicon wave plasma processing apparatus 1 according to the present embodiment
Is a vacuum vessel including a reaction chamber 2 and a process chamber 3 formed by a quartz glass tube, a magnetic coil 4 for applying a magnetic field in the reaction chamber 2 in an axial direction, and applying a high-frequency power to the reaction chamber 2. It comprises an RF antenna 9 and a mounting table 7 arranged in the process chamber 3. By evacuating the inside of the vacuum vessel from an exhaust port 6 provided in the process chamber 3, a predetermined vacuum state can be obtained.
A processing gas is introduced from the gas introduction port 5 into the vacuum vessel. An exciting current is supplied from a DC power supply (not shown) to the magnetic coil 4, and a high-frequency power supply 10 is supplied to the RF antenna 9.
Is supplied via the matching circuit 11 from the predetermined frequency. With the above configuration, the vacuum vessel (reaction chamber 2,
The processing gas introduced into the process chamber 3) is turned into plasma by electric field excitation by an electromagnetic induction action from the RF antenna 9, and then is applied with a magnetic field applied from the magnetic coil 4, so that a helicon wave ( (Whistler wave). By exciting the helicon wave in the plasma, electrons in the plasma obtain electric field energy and higher energy by the action of Landau damping, so that high-density plasma is generated. Plasma particles generated by the plasma in the reaction chamber 2 are transported to the process chamber 3 along the direction of the magnetic field, and are etched, deposited, and the like on a substrate (object to be processed) 8 mounted on a mounting table 7. Can be performed. In the helicon wave plasma processing apparatus 1 having this configuration , the RF antenna 9 is disposed at a position distant from the magnetic coil 4 as shown in the figure, and high-frequency power is supplied from outside the plasma generation region 12 where high-density plasma is generated. It is applied to the plasma generation region 12.
Therefore, the collision of ions in the high-density plasma with the reaction chamber 2 due to the generation of a high-frequency potential at the RF antenna 9 is reduced, the walls of the reaction chamber 2 are sputtered, and impurities are released into the reaction chamber 2. Defects in the plasma treatment due to contamination by impurities are prevented.

[0007] Measured data comparing the effect of preventing the plasma processing failure with a specific configuration will be described below.
The reaction chamber 2 was formed of a quartz tube having a diameter of 60 mm and a length of 1000 mm, an air-core coil was arranged as the magnetic coil 4, and the magnetic field intensity at the center of the magnetic coil 4 was set to 100 Gauss. Further, 13.5 of the m = 0 mode is transmitted from the RF antenna 9.
A high frequency power of 6 MHz and 1.2 kW was applied. Further, the emission spectrum of plasma generated when 3 mTorr of argon (Ar) gas was introduced as a processing gas from the gas introduction port 5 was observed near the tube wall of the reaction chamber 2 at the center of the magnetic coil 4. Oxygen ion emission intensity (wavelength: 4414)
・) And emission intensity of argon ion (wavelength: 4348 ・)
The relative intensity ratio (O / Ar) with the RF antenna 9 when the RF antenna 9 is inside the magnetic coil 4 (corresponding to the conventional configuration) and when the RF antenna 9 is 200 mm away from the end face of the magnetic coil 4 (example configuration:
As a result of comparison with FIG. 1), when the RF antenna 9 was inside the magnetic coil 4, O / Ar = 0.420. On the other hand, in the case of the embodiment in which the RF antenna 9 is separated from the magnetic coil 4, O / Ar = 0.120. This is because argon ions generated by the plasma are attracted and accelerated by the DC potential generated in the RF antenna 9, and the quartz tube of the reaction chamber 2 is sputtered to release impurities (oxygen atoms) into the reaction chamber 2. Effect. The results of operating the helicon wave plasma processing apparatus 1 as an etching apparatus based on the results of the above emission spectroscopy are shown below. 100% chlorine gas as processing gas, 1
The aluminum plate is etched by introducing mTorr.
At this time, when the RF antenna 9 was disposed in the magnetic coil 4, an alumina film was formed on the surface of the aluminum plate due to mixing of oxygen atoms, and etching was impossible.
On the other hand, when the RF antenna 9 was separated from the magnetic coil 4, etching could be performed at an etching rate of 800 nm / min. In the above plasma processing equipment
When the RF antenna 9 is separated from the magnetic coil 4,
2 outside the plasma generation region, the RF
High density due to generation of high-frequency potential on antenna 9
The collision of ions in the plasma with the reaction chamber 2 is reduced,
The walls of the chamber 2 are sputtered and impurities are released into the reaction chamber 2
Is the time each other is reduced. However, also in this case, RF
The antenna 9 is wound around the vacuum chamber that is the reaction chamber.
Therefore, ions in the plasma collide with the walls of the reaction chamber 2
It cannot be completely prevented . Implementation of the present invention shown in FIG.
In the plasma processing apparatus according to the embodiment, the point is improved.
Have . That is, in the plasma processing apparatus shown in FIG.
The antenna 9 is substantially separated from the reaction chamber 2 and
Except for the point provided outside, the conventional projector shown in FIG.
It is the same as the plasma processing device. Therefore, the embodiment shown in FIG.
1, the same elements as those of the processing apparatus of FIG.
Use a number. In FIG. 2, the RF antenna 9 is disposed at a position away from the reaction chamber 2a. Since the reaction chamber 2a is formed to have a width approximately equal to the arrangement width of the magnetic coil 4, R
The F antenna 9 applies high frequency power into the reaction chamber 2a from the end of the reaction chamber 2a . According to this configuration, FIG.
Since the collision of ions in the plasma with the wall of the reaction chamber 2a is further reduced as compared with the configuration of the conventional apparatus shown , generation of impurities in the reaction chamber 2a can be further reduced.

[0008]

As described above, according to the present invention, the RF from the position where the magnetic coil where the high-density plasma is generated is provided.
The antenna is separated, and high-frequency power is applied to the plasma generation region from outside the plasma generation region. Therefore, even if a DC potential is generated in the RF antenna, the amount of plasma ions at the position where the RF antenna is disposed is small, and the generation of impurities by sputtering quartz or the like forming the vacuum vessel (reaction chamber) is reduced. Therefore, an advantage is obtained in that the features of the helicon wave plasma processing apparatus capable of generating high-density plasma in a low magnetic field environment can be sufficiently exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a plasma processing apparatus which is a premise of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a helicon wave plasma processing apparatus according to one embodiment of the present invention.

FIG. 3 is a schematic diagram showing a configuration of a helicon wave plasma processing apparatus according to a conventional example.

[Explanation of symbols]

 Reference Signs List 1, 13 Helicon wave plasma processing apparatus 2, 2a Reaction chamber (vacuum vessel) 3 Process chamber (vacuum vessel) 4 Magnetic coil 5 Gas introduction port 6 Exhaust port 7 Mounting table 8 Substrate (processed 9) RF antenna 10 ... High frequency power supply 12 ... Plasma generation area

Continued on the front page (72) Inventor Yasuhiro Horiike 2-22-703 Matsukawa-cho, Minami-ku, Hiroshima-shi, Hiroshima Global Matsukawa (72) Inventor Tadashi Shoji Nishisakuta 12-72, 72-72 Inventor Satoshi Narai 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Research Institute (56) References JP-A-55-91980 (JP, A) JP-A-3-68773 (JP, A)

Claims (1)

(57) [Claims] 1. A high-frequency power is applied from an RF antenna to a vacuum container and a magnetic field is applied from a magnetic coil to convert a processing gas introduced into the vacuum container into a plasma. In a helicon wave plasma processing apparatus for performing plasma processing on an object to be processed disposed at a position, the RF antenna is substantially outside a plasma generation region.
A helicon wave plasma processing apparatus, wherein the helicon wave plasma processing apparatus is disposed at a position distant from the vacuum vessel and capable of applying high frequency power to the plasma generation region.