JPH06264246A - Plasma treatment of substrate - Google Patents

Abstract

PURPOSE:To execute plasma treatment of a substrate by drawing out only the ions having a specific energy component by divergent magnetic fields and adequately controlling the energy of the ions. CONSTITUTION:The plasma treatment onto the substrate 10 is executed by forming the axial magnetic flux density distribution in a plasma generating section 2 as a Miller field and confining the plasma 7 into this magnetic field. Particularly, the peak value on the side near a treatment chamber 3 of the two peaks of the magnetic flux density distribution is arbitrarily changed, by which the effect of confining the plasma is regulated. As a result, the irradiation with the ions of the energy meeting the content of the plasma treatment is possible. The adequate execution of various kinds of the substrate treatments is thus possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating plasma using the electron cyclotron resonance (ECR) phenomenon and subjecting a sample substrate to plasma processing such as sputtering, CVD, etching and ion implantation. The present invention relates to a novel plasma processing method for a substrate for controlling the energy of ions in the plasma with which the substrate is irradiated and performing appropriate substrate processing.

[0002]

2. Description of the Related Art Conventionally, it has been difficult to control the energy of ions in the plasma with which a substrate is irradiated in a plasma processing apparatus using parallel plate plasma, and in order to control this, a bias voltage is applied to the substrate. I've been told. However, it is often necessary to irradiate low-energy ions of tens of eV or less for processing the substrate, and according to the above-described conventional method, it is difficult to irradiate low-energy ions of tens of eV or less due to problems in the device configuration. Met.

On the other hand, in Japanese Unexamined Patent Publication No. 63-227777, the plasma generated in the plasma generating portion is diverged from the plasma generating portion toward the substrate by a divergent magnetic field in which the magnetic flux density is weakened with an appropriate gradient. A technique of extracting and irradiating a substrate has been proposed.

This plasma processing apparatus 1 is shown in FIG.
In FIG. 3, 2 is a plasma generation part, 3 is a processing chamber, 4 is a microwave introduction window made of quartz glass, and the plasma generation part 2 is formed from the rectangular waveguide 5 through the microwave introduction window 4. The frequency of the microwave guided to, for example, 2.45G
Hz.

At the other end of the plasma generator 2 facing the microwave introduction window 4, a plasma extraction window 6 is provided.
A plasma flow 8 is drawn out from the plasma 7 generated in the plasma generator 2 through the drawing window 6 and is guided to the substrate 10 placed on the sample table 9.

An electromagnetic coil 11 is provided around the plasma generating portion 2 and the distribution of the magnetic field generated by the electromagnetic coil 11 is determined so that the conditions of electron cyclotron resonance by microwaves are satisfied inside the plasma generating portion 2. I shall.
For the microwave of frequency 2.45 GHz, this condition is the magnetic flux density of 875 Gauss, so the electromagnetic coil 11
Is configured to generate a maximum magnetic flux density higher than this. In addition, the magnetic field generated by the electromagnetic coil 11 is configured not only to be used for electron cyclotron resonance in the plasma generator 2 but also to reach the processing chamber 3 from the plasma extraction window 6 to the sample stage. 9 is also used to form a divergent magnetic field in which the magnetic flux density distribution in the processing chamber 3 is further reduced with an appropriate gradient, and thus is also used to draw the plasma flow 8 from the plasma generating unit 2 to the sample stage 9. I shall.

Due to the interaction between the magnetic moment of the circularly moving electrons and the magnetic field gradient of the divergent magnetic field, which are brought into a high energy state by electron cyclotron resonance, the electrons are moved to the sample stage 9
It is accelerated while moving circularly in the direction of. However, the sample table 9
Since the surface of the plasma generator 2 and the plasma generator 2 are electrically insulated from each other, the sample stage 9 generates a negative potential, decelerates the electrons in the plasma flow 8 and generates an electric field that accelerates the ions. Then, the condition that the same number of electrons and ions reach the sample table 9 is maintained. That is, with this divergent magnetic field configuration, the energy of electrons is converted into the incident energy of ions on the sample table 9, and an efficient plasma treatment is generated by an appropriate ion impact. The energy of the ions in this case is about 5 to 30 eV, and the value can be controlled by microwave power, gas pressure, or the like.

[0008]

According to the above prior art, since the plasma 7 in the plasma generator 2 is extracted by the effect of the divergent magnetic field, the energy of the ions can be controlled only with respect to the extraction direction component, and the extraction direction can be controlled. The kinetic energy component in the plane orthogonal to was not controllable.

The present invention was devised in order to improve such disadvantages of the prior art, and its main purpose is to:
It is an object of the present invention to provide a plasma processing method for a substrate, in which only ions having a specific energy component are extracted by a divergent magnetic field, and the energy of ions can be controlled appropriately.

[0010]

The object is to provide a vacuum chamber provided with a plasma generator and a processing chamber coupled to the plasma generator, an electromagnetic coil arranged around the plasma generator, and a micro-chamber. By the plasma processing apparatus including a waveguide coupled to the plasma generation unit through the wave introduction window, after confining the magnetic field of the plasma in the plasma generation unit using the axial magnetic flux density distribution as a mirror magnetic field,
This is achieved by performing a plasma treatment on the substrate. In particular, among the two peaks of the magnetic flux density distribution, it is advisable to arbitrarily change the peak value on the side closer to the processing chamber so that the plasma confinement effect can be adjusted.

[0011]

According to the structure of the present invention, it is possible to confine the plasma by the mirror magnetic field effect in the plasma generating part and to extract only the ions having a specific energy component. Energy can be controlled.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic block diagram of an embodiment of the plasma processing method of the present invention. The parts corresponding to those of the apparatus shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1, the magnetic flux density generated by the electromagnetic coil 11 can have two peaks in the axial direction within the plasma generating section 2. As described above, the upstream peak 12 has a magnetic flux density of 875 Gauss or more, and the downstream peak 13 is arbitrarily set to form a mirror magnetic field in the plasma generating unit 2.

Now consider a charged particle in the valley 14 of two peaks. This charged particle has a circular motion velocity V1 (Vv1 in the direction orthogonal to the magnetic force line and Vpl in the parallel direction) about the magnetic force line. The circular motion magnetic moment μ of charged particles in plasma is represented by μ = (1 / 2mVv1 ² ) / B, where B is the magnetic flux density, and this μ is a constant value. Therefore, as a result of this, Vv ² increases as the magnetic flux density increases, and finally Vp = 0 at a certain magnetic flux density, and the charged particles are reflected to the weaker magnetic flux density. Valley 14
And the magnetic moment of the charged particles at the downstream peak 13 does not change, so that (1 / 2mVv1 ² ) / B = (1 / 2mVv2 ² ) / B holds.

Assuming that the original particle movement direction is θ1 with respect to the magnetic field lines, Vv1 = V1sinθ1 Vv2 = V2sinθ2 From the above, the magnetic flux density in the valley 14 between both peaks 12 and 13 is B
1. If the magnetic flux density of the downstream peak 13 is B2, then sin ² θ1 / B1 = sin ² θ2 / B2. At the reflection point of the charged particles, Vp = 0 and θ = 90 °
Therefore, B2 = B1 / sin ² θ1. That is, for θ1 given by sin ² θ1 = B1 / B2, particles other than particles moving in the direction of a smaller angle (relative to the magnetic field line) in the valley 14 should be confined upstream of the downstream peak 13. become.

Thus, by controlling the magnetic flux density B2 of the peak 13 on the downstream side, it is possible to align the directionality of the ions extracted from the plasma generating section 2 and subjected to the plasma processing.

In FIG. 1, the magnetic flux density in the valley 14 is 30.
Since 0 Gauss and the magnetic flux density of the downstream peak 13 are 900 Gauss, θ1 that satisfies sin ² θ1 = B1 / B2 = 300/900 = 0.333 is about 30 °, which is 30 ° with respect to the magnetic field line.
Except for ions that move in the direction of a smaller angle, they are confined upstream of the downstream peak 13.

Considering this in the velocity space, as shown in FIG. 2, only ions having a velocity component smaller than 30 ° with respect to the magnetic field lines, that is, ions in the range shown by diagonal lines are extracted to the downstream side, and as a result, they are extracted. The moving directions of the generated ions have uniformity within ± 30 °.

The plasma extraction window 6 may not be used if necessary.

[0021]

As described above, according to the plasma processing method of the present invention, by confining the mirror magnetic field of the plasma, only ions having a specific energy component can be extracted from the plasma generating portion, so that strict ion It becomes possible to control energy. As a result, it becomes possible to perform ion irradiation with energy according to the content of plasma processing, and various substrate processing such as anisotropic etching of semiconductor wafers and thin film formation of new material material can be appropriately performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a vertical cross section of a plasma processing apparatus of the present invention and a magnetic flux density distribution on its central axis.

FIG. 2 is a diagram showing a longitudinal section of a plasma processing apparatus of the present invention and an ion confinement effect.

FIG. 3 is a vertical sectional view showing a conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Plasma generation part 3 Processing chamber 4 Microwave introduction window 5 Rectangular waveguide 6 Plasma extraction window 7 Plasma 8 Plasma flow 9 Sample stage 10 Substrate 11 Electromagnetic coil 12 Upstream peak 13 Downstream peak 14 Peak valley

Claims (2)

[Claims] 1. A vacuum chamber provided with a plasma generating part and a processing chamber coupled to the plasma generating part, an electromagnetic coil arranged around the plasma generating part, and the plasma generating via a microwave introduction window. In a method of processing a substrate by a plasma processing apparatus including a waveguide coupled to a portion, the magnetic field of the plasma is confined in the plasma generation portion using a magnetic flux density distribution in the axial direction as a mirror magnetic field, A plasma processing method for a substrate, characterized in that the plasma processing is performed. 2. The substrate according to claim 1, wherein among the two peaks of the magnetic flux density distribution, the peak value on the side closer to the processing chamber is arbitrarily changed to adjust the plasma confinement effect. Plasma treatment method.