JPH0661153A - Microwave plasma treatment device - Google Patents

Abstract

PURPOSE:To enable a plasma treatment device to uniformly treat the surface of a board by a method wherein a gas discharge structure having a two-dimensional array of a large number of holes for emitting neutral gas is provided at a boundary between a plane antenna and a plasma generating region, where the plasma treatment device generates plasma taking advantage of an electron cyclotron resonant effect. CONSTITUTION:A treating region where plasma 6 is generated and an antenna region are isolated from each other by a dielectric plate 3 and a dielectric gas discharge plate 7. Gas required for treatment is fed to a vacuum chamber 2 through a gas inlet 5 from outside. Gas fed to the vacuum chamber 2 is discharged out into a plasma generating region through a large number of holes which are below several millimeters in diameter and bored in the dielectric gas discharge plate 7. Plasma 6 of high density is generated by an electromagnetic cyclotron resonance induced between a magnetic coil 4 and microwaves radiated from a plane antenna 1. In this case, gas required for treatment is discharged out toward plasma 6 through a large number of holes provided to the dielectric gas discharge plate 7. Therefore, plasma can be kept spatially uniform in density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus for generating a plasma by utilizing an interaction between a microwave and a magnetic field and performing a surface treatment such as etching of a substrate or thin film formation by the plasma.

[0002]

2. Description of the Related Art In a conventional microplasma processing apparatus, as described in Japanese Patent Application Laid-Open No. 2-156526, no particular consideration is given to a method of supplying a raw material gas, and an antenna simply uses a linear electrode. .

[0003]

According to the conventional device,
Since the supply of raw material gas is around the plasma generation area,
When high-density plasma is generated to increase the processing speed, the supply of the source gas in the central portion of the substrate becomes insufficient, the plasma density is high in the periphery and low in the center, and the treatment on the substrate becomes non-uniform. Further, since the antenna structure is simply a linear electrode, the microwave radiation efficiency is low and the microwave utilization efficiency is not always good.

An object of the present invention is to provide a microwave plasma processing apparatus which solves the above problems.

[0005]

In order to achieve the above object, the present invention comprises a planar antenna for radiating microwaves to plasma and an electromagnet or permanent magnet for generating a magnetic field, and utilizes the effect of electron cyclotron resonance. In a plasma processing device that generates plasma by accelerating electrons to impact ionize neutral gas, a large number of holes for emitting neutral gas are arranged in a plane at the boundary between the planar antenna and the plasma generation region. A structure is provided, a reflector is provided behind the planar antenna, and the characteristic dimension of the antenna is an integral multiple of a half wavelength of the microwave.

[0006]

It is important to generate a high-density plasma in order to speed up the process, but when the gas required for the process is supplied from the periphery of the plasma generation region as in the conventional case, the plasma density distribution becomes nonuniform. . In the method of the present invention, the gas is discharged in a planar manner on the substrate, so that the gas distribution and the plasma density distribution are uniform, and the uniformity of processing is improved. Further, by making the electrode length of the planar antenna an integral multiple of the half wavelength of the microwave, the microwave resonates with the electrode portion and the microwave radiation efficiency improves. Further, by providing a reflector behind the planar antenna and adjusting the distance between the antenna and the reflector, microwaves radiated backward from the antenna can be efficiently reflected to the plasma side, and microwave utilization efficiency is improved. .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The apparatus of this embodiment comprises a vacuum container 2 and a magnetic field coil 4 for generating a magnetic field. Inside the vacuum container 2, a processing area where a substrate 8 held by a substrate holder 9 is located, a planar antenna 1 and a reflector. It consists of 10 antenna areas.
The processing area for generating the plasma 6 and the antenna area are
It is separated by a dielectric plate 3 and a dielectric gas discharge plate 7. The dielectric plate 3 and the dielectric gas discharge plate 7 are hermetically fixed to the vacuum container 2 with a gap of several mm or less, and the gap is required for processing through the gas inlet 5 from outside the vacuum container 2. Various gases are supplied, and the supplied gas is discharged to the plasma generation region through a large number of holes having a diameter of several mm or less formed in the dielectric gas discharge plate 7. Generation of plasma is done by magnetic field coil 4
Due to the effect of electron cyclotron resonance with the microwave radiated from the plane antenna 1 and the microwave, the gas is effectively ionized at a magnetic field strength of 875 gauss (when the microwave frequency is 4.45 GHz) that causes resonance, and the high density Plasma 6 is generated. In this case, the gas required for processing is supplied to the plasma 6 through a large number of holes in the dielectric gas discharge plate 7, so that the plasma density is spatially uniform and uniform processing is possible. Further, by operating the reflector 10 in the vertical direction to adjust the distance from the planar antenna 1, the plasma 6
Since the intensity of the microwave in the direction can be increased, the ionization of the gas becomes active and the plasma generation efficiency is improved. The structure of the planar antenna 1 is, for example, as shown in FIGS. 4 and 5, by setting the length of the antenna electrode to (n + 1/2) λ times (n: integer) with respect to the microwave wavelength λ,
A standing wave is formed in the electrode portion by the resonance of the microwave, and the radiation efficiency is improved. Further, when processing a large-area substrate, FIG.
As in the above embodiment, by connecting a plurality of the devices of this embodiment in a straight line or on a plane, the size of plasma can be changed according to the size of the substrate to be processed.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, a permanent magnet 11 is used in addition to the magnetic field coil 4 which is the magnetic field generating means of the first embodiment. The permanent magnet 11 is mounted near the planar antenna 1 to generate a magnetic field of several hundred Gauss in the generation region of the plasma 6, and the polarities N and S of the adjacent magnets are reversed to locally form a cusp magnetic field. In the present embodiment, the magnetic field strength necessary for electron cyclotron resonance is generated by using the magnetic field coil 4 and the permanent magnet 11 together, so that the electric power supplied to the magnetic field coil 4 can be reduced.

Next, a third embodiment of the present invention will be described with reference to FIG. In the present embodiment, a permanent magnet 11 is used instead of the magnetic field coil 4 which is the magnetic field generating means of the first embodiment. The permanent magnet 11 is mounted near the planar antenna 1 to generate a magnetic field of several hundred Gauss in the generation region of the plasma 6, and the polarities N and S of the adjacent magnets are reversed to locally form a cusp magnetic field. In this embodiment, since the magnetic field is generated only by the permanent magnet 11, the size of the device is reduced and it is economical.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, the mounting position of the planar antenna 1 of the first embodiment is changed between the dielectric plate 3 and the dielectric gas discharge plate 7. In the present embodiment, the flat antenna 1 is provided in the flow path of the neutral gas, which hinders the gas flow to some extent.
Since the plane antenna 1 is located near the plasma 6 generation region, the efficiency of microwave absorption in the plasma 6 is improved.

[0011]

According to the present invention, the gas required for the processing is uniformly radiated onto the substrate and the plasma can be efficiently and uniformly generated. Therefore, the processing such as film formation and etching on the substrate is uniformly and highly efficient. There is an effect that can be done in. Further, even when processing a large-area substrate, it is possible to generate plasma in an arbitrary area and perform the processing by connecting a plurality of devices of the present invention.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a third embodiment of the present invention.

FIG. 4 is an explanatory view showing an example of a planar antenna structure of the present invention.

FIG. 5 is an explanatory view showing an example of a planar antenna structure of the present invention.

FIG. 6 is an explanatory view showing a method for connecting the devices of the present invention.

FIG. 7 is an explanatory diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

1 ... Planar antenna, 2 ... Vacuum container, 3 ... Dielectric plate, 4 ...
Magnetic field coil, 5 ... Gas inlet, 6 ... Plasma, 7 ... Dielectric gas discharge plate, 8 ... Substrate, 9 ... Substrate holder, 10 ... Reflector, 11 ... Permanent magnet.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideyuki Kazumi, Inventor, 1168 Moriyama-cho, Hitachi, Hitachi, Ibaraki Energy Research Institute, Hitachi, Ltd. (72) Shinji Shirakawa, 1168, Moriyama-cho, Hitachi, Ibaraki, Hitachi, Ltd. Energy Research Institute, Ltd. (72) Yoshiya Higuchi, Inventor Yoshiya Higuchi, 1168 Moriyama-cho, Hitachi, Ibaraki Prefecture Energy Research Institute, Hitachi, Ltd. (72) Inventor, Kazuo Suzuki, 3-2, 2-3, Saiwaicho, Hitachi, Ibaraki Stock Company Within Hitachi Engineering Services

Claims (6)

[Claims] 1. A plasma comprising a plane antenna for radiating microwaves to plasma and an electromagnet or a permanent magnet for generating a magnetic field, wherein electrons are accelerated by utilizing the effect of an electron cyclotron to collide and ionize neutral gas. In the plasma processing apparatus for generating a gas, a gas discharge mechanism is provided between the planar antenna and the plasma generation region, in which a large number of holes through which the microwaves can be transmitted and which discharge the neutral gas are arranged in a plane. Characteristic microwave plasma processing device. 2. The gas discharge mechanism according to claim 1,
A microwave plasma processing apparatus, characterized in that two dielectric plates are attached at intervals of several mm or less, and a large number of holes having a diameter of several mm or less are opened on the side of the plasma generation region of the dielectric plates. 3. The microwave plasma processing apparatus according to claim 1, wherein a microwave reflector is provided on the side of the plane antenna opposite to the plasma generation region, and the distance between the microwave reflector and the plane antenna is variable. . 4. The microwave plasma processing apparatus according to claim 1, wherein an electromagnet and a permanent magnet are used together as the magnetic field generating means. 5. The structure according to claim 1, wherein the structure of the planar antenna is comb-teeth-shaped, the intervals between the teeth of the comb are about a half wavelength of the microwave, and the length of the teeth is an integral multiple of a half-wavelength. A microwave plasma processing device. 6. The microwave plasma processing apparatus according to claim 1, wherein the planar antenna has a structure in which two or more electrodes are arranged in a radial pattern and the length of the electrodes is approximately an integral multiple of a half wavelength of the microwave.