JPH0415921A - Method and apparatus for activating plasma - Google Patents

Abstract

PURPOSE:To increase a film formation speed and an etching speed by applying a high-frequency electric field to plasma with an electrode on the path of the plasma introduced from a plasma generation chamber to the surface of a sample and accelerating the electrons and ions in the plasma. CONSTITUTION:A microwave from one end of a wave guide 2 is introduced into a plasma generation chamber 1 through a microwave introduction port 1c. A high-frequency-wave-applying coil-shaped electrode 7 is arranged to surround a plasma flow P and applies a high-frequency wave emitted from a high- frequency-wave generator 8 to plasma. When a film is formed on the surface of a sample S, reaction gas is supplied to the plasma generation chamber 1 and a reaction chamber 3 via gas supply systems 1g and 3g, plasma is generated by applying an electric field generated by the microwave to the inside of the plasma generation chamber 1, while a magnetic field is formed by an excitation coil 4, and introduced into the reaction chamber 3 through a plasma drawing window 1d and around the sample S, with the density and activity of the plasma enhanced by applying the high-frequency wave thereto with the high-frequency- wave-applying electrode 7, and the surface is reacted by the ion particles and radical particles in the plasma flow.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to electron cyclotron resonance (electron cyclotron resonance) using microwaves.
Electron Cyclotron Re5ona
The present invention relates to a method and apparatus for activating plasma when manufacturing semiconductor devices, electronic materials, etc. using plasma generated by excitation (ECR).

[Conventional technology]

Plasma devices that utilize electron cyclotron resonance have the advantages of being able to generate highly ionized plasma at low gas pressure, allowing a wide selection of ion energies, and having excellent ion directionality and uniformity. Therefore, research and development is progressing on it as an indispensable part of processes such as thin film formation and etching in the production of highly integrated semiconductor devices.

FIG. 6 is a longitudinal sectional view showing a conventional ECR plasma apparatus, and numeral 41 in the figure indicates a plasma generation chamber.

The plasma generation chamber 41 is formed in a cylindrical shape with a cooling channel 41a around the periphery, and a quartz glass plate 4 is provided at the center of the upper wall.
1b, and a plasma extraction window 41d at a position facing the microwave inlet 41c at the center of the lower wall. One end of a waveguide 42, the other end of which is connected to a microwave oscillator (not shown), is connected to the microwave inlet 41c, and a reaction chamber 43 is disposed facing the plasma extraction window 41d.
Furthermore, an excitation coil 44 is disposed concentrically with the plasma generation chamber 41 and one end of a waveguide 42 connected to the plasma generation chamber 41 so as to surround the plasma generation chamber 41 and the waveguide 42 connected thereto.

A sample stage 45 is disposed in the reaction chamber 43 at a position facing the plasma draw-out window 41d, on which the sample S is placed as it is or removably mounted by means such as electrostatic adsorption, and further reacted. An exhaust port 43a connected to an exhaust device (not shown) is opened in the lower wall of the chamber 43.

41g and 43g are gas supply systems, respectively.

In such an ECR device, a reaction gas is supplied through the gas supply systems 41g and 43g into the plasma generation chamber 411 and the reaction chamber 43, which are set to a required degree of vacuum, and a magnetic field is formed by the excitation coil 44. At the same time, a high frequency electric field by microwave is applied in the plasma generation chamber 41 to generate plasma, and the generated plasma is transferred from the plasma generation chamber 41 through the plasma extraction window 41d to the reaction chamber by a divergent magnetic field formed by the excitation coil 44. The sample S is led out to the vicinity of the sample S in the sample S, a surface reaction is caused by ions and radical particles in the plasma flow on the sample S surface, and processing such as film formation and etching is performed on the sample S surface.

Note that, if necessary, a high frequency is applied to the sample S from the high frequency oscillator 46 to induce a negative self-bias on the surface of the sample S,
Accelerate the ions toward the surface of the sample S. A film surface flattening process (J, νac, Sci
, Technol, B 4 f4), 818 (1
986)) or highly anisotropic ionic engineering method (J, νac, Sci, Technol, A
7 (3), 903 (1989)), etc. have been proposed.

[Problem to be solved by the invention]

However, if the microwave power is increased too much in order to increase the film formation rate or etching rate, the peripheral edge of the microwave introduction window 41c will be heated strongly and will be damaged or destroyed, so there is a problem that there is a limit to the increase in the microwave power. There is. In addition, the etching speed can be improved by applying high frequency to the sample stage, but in this case, the etching speed of the mask also increases, resulting in a decrease in selectivity between the mask and the substrate. Therefore, there was a problem in that the structure of the sample stage became complicated.

Note that when this method is used for film formation, the film formation rate decreases due to the buffing property of energetic ions.

The present invention has been made in view of the above circumstances, and provides a plasma activation method and a plasma activation method that can obtain high film forming and etching rates without increasing the power of microwaves or applying high frequencies to the sample. The purpose is to provide such equipment.

[Failure to solve the problem]

The plasma activation method according to the present invention is a method in which plasma generated in a plasma generation chamber by electron cyclotron resonance excitation using microwaves is guided to a sample surface in a reaction chamber to treat the sample surface. It is characterized by applying a high-frequency electric field to the plasma using an electrode placed on the way from the plasma generation chamber to the sample surface to accelerate electrons and ions in the plasma.

Further, the plasma activation apparatus according to the present invention is an apparatus for treating the surface of a sample by guiding plasma generated in a plasma generation chamber by electron cyclotron resonance excitation using microwaves to the surface of a sample in a reaction chamber. The method is characterized in that a coil-shaped or two or more stages of annular electrodes for applying a high-frequency electric field to the plasma are disposed on the way of guiding the plasma from the plasma generation chamber to the sample surface.

Furthermore, another plasma activation device according to the present invention is a plasma device that processes plasma generated in a plasma generation chamber by electron cyclotron resonance excitation using microwaves by guiding it to the surface of a sample in a reaction chamber. , characterized in that an electrode for applying a high frequency electric field to the plasma is disposed around the plasma generation chamber.

[Effect]

In the present invention, a high-frequency electric field is applied while the plasma is being guided from the plasma generation chamber to the sample surface, or within the plasma generation chamber, so that electrons and ions in the plasma are accelerated, and the accelerated particles are By colliding with reactive gas particles to ionize and excite them, the t-separation of the plasma increases, creating a high-density, highly active plasma state, which enables high-speed film formation or etching. .

[Example 1] Hereinafter, the present invention will be specifically explained based on examples thereof.9 Fig. 1 is a schematic vertical cross-sectional view of a plasma device according to the present invention (hereinafter referred to as the device of the present invention) configured as a CVO device. In the figure, 1 is a plasma generation chamber, 2 is a waveguide, 3 is a reaction chamber,
4 indicates an excitation coil.

The plasma generation chamber 1 is formed in a cylindrical shape with a cooling channel 1a around its periphery, and has a microwave inlet 1c closed with a quartz glass plate 1b at the center of its upper wall, and the microwave guide at the center of its lower wall. A circular plasma extraction window 1d is provided at a position facing the inlet 1c, one end of a waveguide 2 is connected to the microwave introduction port 1c, and a reaction chamber is provided facing the plasma extraction window 1d. 3 is arranged,
Furthermore, an excitation coil 4 is disposed around one end of the plasma generation chamber 1 and the waveguide 2 connected thereto.

The other end of the waveguide 2 is connected to a microwave oscillator (not shown), and the emitted microwave (2.45 GHz)
is introduced into the plasma generation chamber 1 from the microwave introduction port 1c. The excitation coil 4 is connected to a DC power source (not shown), and is designed to generate a magnetic field by passing a DC current into the plasma generation chamber 1 so that plasma can be generated by introducing microwaves into the plasma generation chamber 1. This magnetic field is a diverging magnetic field in which the magnetic flux density decreases toward the reaction chamber 3 side, and the plasma generated in the plasma generation chamber 1 is led out into the plasma reaction chamber 3.

A sample stage 5 is disposed in the lower center of the reaction chamber 3 at a position facing the plasma extraction window 1g, on which a sample S such as a wafer is placed as is or by means such as electrostatic adsorption. The bottom wall is provided with an exhaust port 3a connected to an exhaust device (not shown). Ig and 3g are gas supply systems.

In the apparatus of the present invention, a coiled high-frequency application electrode 7 is provided in a space between the sample stage 5 in the reaction chamber 3 and the plasma extraction window 1d so as to surround the plasma flow P extracted from the plasma chamber 1. is provided, and its both ends are connected to the high frequency oscillator 8, so that the high frequency waves emitted from the high frequency oscillator 8 can be applied to the plasma.

Note that in the case of an ECR sputtering device, for example, the purpose of the applied high frequency is to induce a negative self-bias on the target surface and draw in ions, so it is necessary to use a high frequency of about 10 MHz that cannot be followed by ions. , even a frequency of several kHz is sufficient to bring about the effect of the present invention.

Therefore, in the method and apparatus of the present invention,
When forming a film on the surface of the sample S, a reaction gas is supplied into the plasma generation chamber 1 and the reaction chamber 3 through the gas supply systems 1g and 3g, and while a magnetic field is formed by the excitation coil 4, the reaction gas is supplied into the plasma generation chamber 1. Plasma is generated by applying an electric field by microwaves, and the generated plasma is guided from the plasma generation chamber 1 into the reaction chamber 3 via the plasma extraction window 1d by a divergent magnetic field formed by the excitation coil 4. A high frequency is applied by the high frequency application electrode 7 to further increase the density and activation of the plasma, and then guide it around the sample S to cause a surface reaction by ions and radical particles in the plasma flow on the surface of the sample S. A film is formed on the S surface.

FIG. 2 (al to <el respectively show other examples of electrodes used to apply high frequency waves to plasma, and in both cases, the upper side is a side view and the lower side is a plan view.

Fig. 2 (Jul) shows an annular electrode 23, which is arranged around the plasma flow with a required interval above and below. Fig. 2 (b) shows an annular electrode 24 4
They are arranged around the plasma flow at a required interval in the vertical direction, with the first and third poles being the same polarity, and the second and fourth poles being the same polarity.
The th and th are at the same pole. Figure 2 (C1 shows two electrodes 25 constructed by stretching a metal net around a ring-shaped peripheral frame, which are arranged around the plasma stream at a required distance in the vertical direction. The electric bridge shown in FIG. 2(d) has electrodes 21 and 21 each having a half-ring shape and are placed facing each other so as to surround the plasma flow.

FIG. 2 (el) shows an electrode 22 having an annular shape divided into eight parts, which is similarly arranged in an annular shape around the plasma flow.

It has been confirmed that substantially the same effect as the coiled electrode 7 shown in FIG. 1 can be obtained even when these electrodes 21 to 25 are used.

[Numerical example]

Using an apparatus as shown in Fig. 1, 5 liters of reaction gas (
4 gas at 150 sccm into the reaction chamber 3, and Ar gas at 5
0sccm was introduced into each plasma generation chamber 1, microwave power: 100OW, plasma generation chamber 1, gas pressure in the reaction chamber: 2Xl0-'Torr, and a Si (100) substrate was used as a sample substrate. This is a graph showing the relationship between the deposition rate, photoconductivity, and applied high-frequency power when forming an amorphous silicon thin film. The horizontal axis represents the high-frequency power (W), and the vertical axis represents the deposition rate (1 / minute)
, photoconductivity (S/cm) is shown.

Note that the frequency of the high frequency was 13.6 MHz.

As is clear from this graph, the film forming rate was 5,800 people/min before high frequency application, but it increased to 8,000 people/min by applying 500 W of high frequency.

The photoconductivity also varies from 10-”S/am to 10-”S/Cl.
11, indicating that a high-density and highly active plasma is being generated.

[Embodiment 2] FIG. 4 is a schematic vertical sectional view showing another embodiment of the present invention. The plasma generation chamber 31 is formed of a dome-shaped quartz chamber, and is arranged at the upper center of the reaction chamber 33 so as to communicate therewith.

One end of a waveguide 32 opened in a trumpet shape is connected to the outside of the plasma generation chamber 31 so as to wrap around it from above, and the waveguide 2 covering the plasma generation chamber 31 and the outside thereof is connected to the outside of the plasma generation chamber 31. An excitation coil 34 is disposed around one end of the coil.

The other end of the waveguide 32 is connected to a microwave oscillator (not shown), and the emitted microwave (2.45GH2
) is introduced into the plasma generation chamber 31 through a quartz chamber. The excitation coil 34 is connected to a direct current (not shown), and by passing the direct current, a magnetic field is formed so that plasma can be generated by introducing microwaves into the plasma generation chamber 31.

A sample stage 35 is disposed within the reaction chamber 33, and the sample S is placed on it. Further, an exhaust port 33a connected to an exhaust device (not shown) is opened at the bottom of the reaction chamber 33. 33g is a reaction gas supply system.

In the present invention, inside the waveguide 32 and around the quartz chamber forming the plasma generation chamber 31,
A coil-shaped electrode 37 for applying high frequency is arranged surrounding this, and both ends thereof are connected to a high frequency oscillator 36, thereby applying the high frequency generated from the high frequency oscillator 36 to the plasma in the plasma generation chamber. It is now possible to do so.

Using a plasma device as shown in FIG. 4, 20 sccm of CH gas as a reaction gas was introduced from the reaction gas supply system 33b, microwave power: 100 OW, gas pressure 4.
Film formation was performed on a 5i (100) sample substrate using XIO bow Torr. Note that the frequency of the high frequency was 100 kHz.

FIG. 5 is a graph showing the relationship between the film formation rate and the applied high frequency power when an amorphous carbon thin film is formed on a substrate using the method and apparatus of the present invention. As is clear from this graph, the deposition rate increased from 1,100 persons/minute to 1,600 persons/minute by applying a high frequency wave with a power of 500 W, demonstrating the effectiveness of the apparatus of the present invention.

Although Examples 1 and 2 both show cases in which the present invention is configured as a CVD apparatus, it goes without saying that it can also be applied to an etching apparatus or the like.

〔Effect of the invention〕

As described above, the present invention increases the power of microwaves,
High-density and highly active plasma can be generated without applying high frequency to the sample, and when used for film formation, etching, etc., processing speeds such as film formation and etching speeds are improved, and semiconductor devices, It has an excellent effect on mass production of secondary materials.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of the apparatus of the present invention for carrying out the method of the present invention, FIG. 2 is a side view and a plan view showing another example of the high frequency application electrode in the apparatus of the present invention, and FIG. is a graph showing the test results of the device of the present invention shown in FIG.
The figure is a schematic vertical sectional view showing another example of the apparatus of the present invention for carrying out the method of the present invention, FIG. 5 is a graph showing the test results of the embodiment shown in FIG. 4, and FIG. 6 is a graph of the conventional apparatus. FIG. 3 is a schematic vertical cross-sectional view. 1... Plasma generation chamber reaction chamber 4... Excitation coil electrode 8... High frequency oscillator electrode 31... Plasma generation chamber 33... Reaction chamber 34... Excitation coil 37...
Electrode P...Plasma flow 2...Waveguide 3...
・Reverse 5... Sample stand 7... 21.22, 23, 24.25... 32... Waveguide 35... Sample stand S... Sample patent Applicant

Claims (1)

[Scope of Claims] 1. A method in which plasma generated in a plasma generation chamber by electron cyclotron resonance excitation using microwaves is guided to a sample surface in a reaction chamber to treat the sample surface, comprising: A plasma activation method characterized by accelerating electrons and ions in the plasma by applying a high-frequency electric field to the plasma using an electrode placed on the way from the chamber to the sample surface. 2. In an apparatus for guiding plasma generated in a plasma generation chamber by electron cyclotron resonance excitation using microwaves to a sample surface in a reaction chamber and treating the sample surface, the plasma is guided from the plasma generation chamber to the sample surface. A plasma activation device characterized in that a coil-shaped or two or more stages of annular electrodes are disposed in the middle for applying a high-frequency electric field to the plasma. 3. In an apparatus for guiding plasma generated in a plasma generation chamber by electron cyclotron resonance excitation using microwaves to a sample surface in a reaction chamber and treating the sample surface, a high frequency wave is applied to the plasma around the plasma generation chamber. A plasma activation device characterized by having an electrode for applying an electric field.