JPH01238020A - Plasma processing device and processing system therefor - Google Patents

Abstract

PURPOSE:To realize a high efficiency, high quality radical processing by enabling a sample surface to be irradiated with a high density radical shielding any ion by disposing a mesh-like grid electrode between a sample and a boundary of produced plasma. CONSTITUTION:Microwaves 4 are introduced into a discharge tube 2 equipped with a coil 1 on the outside thereof through a waveguide 3, and a magnetic field from a magnetic field coil 1 and the microwaves 4 are applied to etching gas 5 introduced into the discharge tube 2 to produce plasma by electron cyclotron resonance. An enhancing magnetic field coil 9 is provided outside a sample chamber 8 which includes a sample table 7 for holding a sample 6. The sample chamber 8 is connected with the discharge tube 2. The direction of an enhancing magnetic field is opposite to the direction of the magnetic field generated by the magnetic field coil 1, both forming a cusp magnetic field orientation. Hereby, a boundary 11 of the plasma 12 on the side of the sample chamber 8 is formed. Further, a mesh-like grid electrode 10 having a positive potential is provided between the plasma boundary 11 and the sample table 7 to sharply reduce ions which can reach the sample 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma processing apparatus and a processing system therefor, and in particular, uses plasma generated by microwave discharge to form a thin film on the surface of a sample, or perform etching. The present invention relates to a plasma processing apparatus suitable for sputtering, plasma oxidation, etc., and a processing system thereof.

[Conventional technology]

Conventional plasma processing equipment that uses plasma generated by microwave discharge in a magnetic field has a magnetic field configuration that decreases from the discharge chamber, which is a part of the discharge space, toward the sample chamber equipped with the sample stage. The plasma generated in the sample moves along the magnetic lines of force toward the sample stage. On the other hand, depending on the type of sample, it is necessary to perform pure radical treatment without directly exposing the sample to plasma (ions, electrons), so a mesh-like grid electrode is installed between the sample stage and the discharge chamber, and a positive potential is applied to it. Therefore, attempts have been made to perform pure radical treatment while avoiding plasma, particularly ions, from entering the sample stage (see, for example, Japanese Patent Laid-Open No. 125820/1982).

However, according to this method, there is a problem that the mesh-like grid electrode is sputtered by the ions, and the grid material mixes into the sample surface.

As another method, an attempt was made to separate the discharge chamber and the sample chamber and connect them with thin piping to use the radicals after plasma extinction (for example, in Japanese Patent Application Laid-Open No. 58-408
(Refer to Publication No. 33), the lifetime of the radicals themselves is short, so there is a problem that the density of radicals reaching the sample decreases and the processing speed is low.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into account plasma, especially the separation method between ions and electrically neutral radicals, and requires high-quality radical treatment that enables efficient pure radical treatment and prevention of contamination of impurity atoms. There was a problem that it was not possible to do both at the same time.

An object of the present invention is to provide a plasma processing apparatus and a processing system thereof that can perform high-quality radical processing without reducing processing speed.

[Means to solve the problem]

The above object is to have a magnetic field configuration in the discharge chamber or between the discharge chamber and the sample stage that can create a boundary of the plasma generated in the discharge chamber, and between the plasma boundary and the sample stage. A plasma processing apparatus equipped with a grid electrode, and an auxiliary magnetic field generating means that generates a magnetic field that creates a boundary of plasma generated in the discharge chamber, located between the discharge chamber and the sample chamber, or on the side of the sample chamber. When a magnetic field is generated between the discharge chamber and the sample chamber, or on the side of the sample chamber, to create a boundary of the plasma generated in the discharge chamber, a current flows in the opposite direction to the magnetic field generating means, and the boundary of the plasma is generated. If not, use a plasma processing apparatus equipped with an auxiliary magnetic field generating means through which a current flows in the same direction as the magnetic field generating means, or between the discharge chamber and the sample chamber, or on the sample chamber side, with lines of magnetic force directed toward the sample in front of the sample. A plasma processing apparatus comprising a means for bending at right angles, a microwave and a discharge gas are introduced, and a magnetic field is applied to a discharge chamber forming part of the discharge space to generate plasma;
It is characterized by a combination of a process in which the plasma is directly irradiated onto the sample in the sample chamber and processed, and a process in which a plasma boundary is created in front of the sample by a magnetic field and the sample is processed in a state where it is not exposed to the plasma. This can be achieved by using a plasma processing system.

[Effect]

Generally, in the motion of plasma in a magnetic field, electrons and ions perform cyclotron motion around magnetic lines of force, so that diffusion across the lines of magnetic force is less than a few percent compared to diffusion in the direction of the lines of magnetic force. In particular, since the mass of electrons is small, their motion is controlled by the magnitude and direction of magnetic lines of force. As a result, the ions also repeat vibrations due to the Coulomb force with the electrons, and most of the ions undergo bipolar diffusion in the direction of the lines of magnetic force. The present invention makes use of the above-mentioned properties of plasma and bends the magnetic field lines from the discharge chamber toward the sample and the sample stand at right angles in front of the sample stand, thereby making the boundary of the plasma from the discharge chamber toward the sample stand A mesh-like grid electrode with a positive potential is placed in the space between the plasma boundary and the sample stage to significantly reduce the number of ions and electrons that enter the sample, and to act as an electrical barrier against ions that diffuse further. This method allows only electrically neutral radicals generated in the plasma to reach the sample, and the amount of sputtering on the grid electrode is extremely small.

〔Example〕

Embodiments of the present invention will be explained below with reference to Figs. 1 and 2.6 Figure 1 shows an example in which the present invention is applied to a plasma processing apparatus that performs sample surface treatment (etching) using magnetic field microwave discharge. be. As shown in the figure, a microwave 4 is passed through a waveguide 3 into a discharge tube (chamber) 2 equipped with a magnetic field coil 1 on the outside.
is introduced, and the etching gas 5 introduced into the discharge tube 2 is excited or ionized by the magnetic field generated by the discharge chamber magnetic field coil 1 and electron cyclotron resonance by the microwave 4 to generate plasma 12. do. on the other hand,
There is an auxiliary magnetic field coil 9 outside the sample chamber 8 which is connected to the discharge tube 2 and includes a sample stage 7 that holds the sample 6, and the direction of the magnetic field produced by this coil is opposite to the direction of the magnetic field produced by the magnetic field coil 1. The plasma 1 generated in the discharge tube 2 by the slit forming the cusp magnetic field configuration.
A boundary 11 on the sample chamber 8 side of No. 2 is generated, and the plasma no longer comes out to the sample chamber 8 side. Furthermore, the plasma boundary 1
A mesh-like grid electrode 1 is provided between the plasma boundary 11 and the sample stage 7 to which a positive potential is applied by a DC power supply 14 in order to shield ions that cross the plasma boundary 11 and diffuse toward the sample chamber 8 side.
0 is set. Thereby, the number of ions that can reach the sample 6 can be significantly reduced, and only the radicals excited within the discharge tube 2 can reach the sample 6, making it possible to perform pure radical treatment.

FIG. 2 is an explanatory diagram of the magnetic field shape and principle of FIG. 1 according to an embodiment of the present invention, and shows the magnetic field direction (magnetic field lines 15) due to the magnetic field coil 1 and the auxiliary magnetic field coil 9.
The plasma 12 generated by the introduced microwave 4 has a plasma boundary 11 in the front part where the magnetic field direction by the magnetic field coil is reversed. Create.

On the other hand, the sample stage 7 holding the sample 6 and this plasma boundary 1
A mesh-like grid electrode 10a provided between 1 and 1
0b is given a positive potential and will screen out a small amount of ions diffusing from the plasma 12 (particularly from the center). As a result, the only particles in the plasma 12 that can reach the sample 6 are electrically neutral high-density radicals or two molecules of neutral atoms. In addition, since the grid electrodes 10a and 10b are not exposed to the plasma 12, they are not sputtered and contamination of the sample 6 with impurities can be prevented.

As described above, according to this embodiment, since it is possible to irradiate a sample with high-density radicals and prevent the incorporation of ions and impurity particles, it is possible to perform high-speed, high-quality radical processing (etching).

FIG. 3 shows another embodiment of the present invention, in which a magnetic field coil la is used to create the plasma boundary.

This is a magnetic field microwave discharge plasma processing (etching) apparatus in which the magnetic field directions of the two coils 1b are the same and a mirror magnetic field configuration is formed. mesh-like grid electrode 1
A plurality of 0s are arranged outside the outermost magnetic field line 15a corresponding to the plasma boundary. As a result, in this example, in addition to the effects of the embodiments of the present invention, there is an effect that a plurality of devices can be processed simultaneously.

FIG. 4 shows still another embodiment of the present invention, which includes a treatment step in which the plasma boundary is created and pure radical treatment is performed, and a plasma treatment in which the sample is directly irradiated with plasma without creating a plasma boundary. A processing method that combines the following steps is shown. FIG. 4(a) shows the magnetic field coil 1 and the auxiliary magnetic field coil 9.
This is the case where the directions of the magnetic lines of force 15b are the same, and the discharge tube 2
The plasma 12 generated within the chamber diffuses into the sample chamber 8 along magnetic lines of force and is irradiated onto the sample 6, which is exposed to the plasma 12.
Plasma processing is performed that actively utilizes the ions and electrons inside. At this time, the grid electrode 10 is moved to a position where it does not come into contact with the plasma in order to avoid sputtering caused by the plasma, and at the same time, the power switch 19 is also opened. FIG. 4(b) shows the case where radical treatment is performed following FIG. 4(a).
), by reversing the current direction of the auxiliary magnetic field coil 9, a cusp magnetic field configuration can be easily obtained to generate a plasma boundary 11 and to ensure that ions are prevented from flowing into the sample 6. The structure is such that a positive potential is applied to the glycide electrode 10 by closing a power switch 19 connected to a power source 14. Also, at this time, Figure 4 (
For a), the grid electrode 10 can be operated externally or
It is assumed that the sample 6 moves to the front side simultaneously with the reversal of the auxiliary magnetic field coil 9.

As described above, according to this embodiment, it is possible to perform any combination of plasma processing and radical processing without moving the sample from the sample stage, especially when processing a sample composed of two or more different materials. This has the effect of making it possible to selectively perform plasma treatment and radical treatment in terms of time.

〔Effect of the invention〕

According to the present invention described above, a plasma boundary is generated,
In addition, by placing a mesh-like grid electrode between the sample and the plasma boundary, it is possible to irradiate the sample surface with high-density radicals while shielding ions, resulting in highly efficient and high-quality radical treatment. effective.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a magnetic field microwave discharge plasma processing (etching) apparatus showing an embodiment of the plasma processing apparatus of the present invention, and Fig. 2 is a cusp magnetic field configuration showing the principle of the present invention in Fig. 1. FIG. 3, a diagram showing the shape and plasma boundary, shows another embodiment of the present invention, and FIG. ) is a diagram showing a step of directly irradiating a sample with plasma to perform plasma treatment in the plasma processing system of the present invention, and FIG. 4(b) is a diagram showing a treatment step of performing pure radical treatment. 1, la, lb... magnetic field coil, 2, 2a... discharge tube (chamber), 3... waveguide, 4... microwave, 5...
... Etching gas, 6... Sample, 7... Sample stage, 8... Sample chamber, 9... Auxiliary magnetic field coil, 10, 1
0a, 10b...mesh-like grid electrodes, 11...
・Plasma boundary, 12... Plasma, 13... Vacuum exhaust, 14... DC power supply, 15, 15 a, 1
6--Magnetic field lines, 17a, 17b...Cooling water, 18...
・Discharge piping, 19...Power switch.

Claims (1)

[Claims] 1. A discharge chamber into which microwaves and discharge gas are introduced and which forms part of a discharge space; a magnetic field generating means for generating a magnetic field in the discharge chamber; A plasma processing apparatus comprising a sample chamber having a sample stage for holding a sample to be processed, and a grid electrode for controlling ion energy directed from the discharge chamber toward the sample stage. A magnetic field configuration is provided between the sample stages that can create a boundary of the plasma generated in the discharge chamber,
A plasma processing apparatus characterized in that the grid electrode is disposed between the plasma boundary and the sample stage. 2. A discharge chamber into which microwaves and discharge gas are introduced and forms part of a discharge space, a magnetic field generating means for generating a magnetic field in the discharge chamber, and a sample to be processed connected to the discharge chamber for holding the sample. In a plasma processing apparatus equipped with a sample chamber having a sample stage, auxiliary magnetic field generating means generates a magnetic field that creates a boundary of plasma generated in the discharge chamber, at an intermediate point between the discharge chamber and the sample chamber, or on the side of the sample chamber. A plasma processing apparatus characterized by comprising: 3. A discharge chamber into which microwaves and discharge gas are introduced and forms part of a discharge space, a magnetic field generating means for generating a magnetic field in the discharge chamber, and a sample connected to the discharge chamber to be processed. In a plasma processing apparatus equipped with a sample chamber having a sample stage, when a magnetic field is generated between the discharge chamber and the sample chamber or on the sample chamber side to create a boundary of the plasma generated in the discharge chamber, the above-mentioned method is used. A plasma processing apparatus characterized in that an auxiliary magnetic field generating means is provided, through which a current flows in the opposite direction to the magnetic field generating means, and through which a current flows in the same direction as the magnetic field generating means when the plasma boundary is not created. 4. A discharge chamber into which microwaves and discharge gas are introduced and which forms part of a discharge space, a magnetic field generating means for generating a magnetic field in the discharge chamber, and a sample connected to the discharge chamber to be processed. In a plasma processing apparatus that includes a sample chamber having a sample stage and a grid electrode that controls ion energy directed from the discharge chamber toward the sample stage, the grid electrode defines a boundary between plasma generated in the discharge chamber. A plasma processing apparatus characterized in that it is movably installed so as to be located in front of the sample when plasma boundaries are to be created, and not to be located in front of the sample when plasma boundaries are not to be created. 5. A discharge chamber into which microwaves and discharge gas are introduced and which forms a part of the discharge space, a magnetic field generating means for generating a magnetic field in the discharge chamber, and a discharge chamber connected to the discharge chamber to hold the sample to be processed. In a plasma processing apparatus equipped with a sample chamber having a sample stage, a means is provided between the discharge chamber and the sample chamber, or on the sample chamber side, for bending the lines of magnetic force directed toward the sample at right angles in front of the sample. A plasma processing device featuring: 6. Microwaves and discharge gas are introduced and a magnetic field is applied to the discharge chamber forming part of the discharge space to generate plasma;
A process in which this plasma is directly irradiated onto a sample in a sample chamber for processing, and a process in which a plasma boundary is created in front of the sample by a magnetic field and the sample is processed in a state where it is not exposed to the plasma. A plasma processing system featuring: 7. In the processing step, the magnetic field applied to the discharge chamber to generate plasma and the magnetic field to create a plasma boundary in front of the sample are determined by adjusting the magnitude, direction, and shape of the generated magnetic fields over the processing time. 7. The plasma processing system according to claim 6, wherein the plasma processing system is controlled within the plasma processing system.