JPH0729834A - High frequency plasma processing system - Google Patents

Abstract

PURPOSE:To provide a high frequency plasma processing system in which generation of reaction products is suppressed in a discharge tube and adhesion thereof to the wall surface or falling there onto a substrate is prevented. CONSTITUTION:The high frequency plasma processing system comprises a vacuum vessel 1 equipped with a discharge tube 4, a mechanism 8 for evacuating the vessel 1, a mechanism 9 for introducing a reaction gas into the vessel, a mechanism 10 for supplying high frequency power into the discharge tube to generate plasma of the reaction gas, and a substrate holding mechanism 2 disposed oppositely to the discharge tube in the vessel, wherein the discharge tube 4 is provided with an electrode 5 which is applied with a bias voltage at a part opposing the substrate holding mechanism. The electrode is coated with a film as required. A temperature regulator 12 for setting the temperature on the surface of the electrode at an arbitrary level is also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency plasma processing apparatus, and more particularly to improvement of a high frequency plasma generating discharge tube in a high frequency plasma processing apparatus used in a plasma CVD apparatus or an etching apparatus.

[0002]

2. Description of the Related Art The structure of a conventional high frequency plasma processing apparatus is shown in FIG. In the conventional device, the high frequency power is introduced by the high frequency applying antenna 21 arranged around the discharge tube 20 formed of a dielectric material, and the high frequency power is introduced into the discharge tube 20. The lower part of the discharge tube 20 is open and connected to the diffusion chamber 22. The diffusion chamber 22 is a metal vacuum container, is held at a ground potential by the earth 23, and has a substrate holding mechanism 24 inside. The substrate 25 to be processed is placed on the substrate holding mechanism 24. An exhaust mechanism 26 and a gas introduction mechanism 27 are attached to the diffusion chamber 22. The exhaust mechanism 26 brings the interiors of the diffusion chamber 22 and the discharge tube 20 into a required reduced pressure state. In addition, the gas introduction mechanism 27 introduces the discharge gas into the diffusion chamber 22.

Gas is introduced into the interior of the diffusion chamber 22 in a required depressurized state by the gas introduction mechanism 27, and in this state, the gas is discharged from the diffusion chamber 22 to the discharge tube 20.
When it enters, it is discharged by the high frequency power introduced by the antenna 21, and thereby plasma is generated. The active species contained in the plasma are generated by the substrate 25 on the substrate holding mechanism 24.
To the surface of the substrate and etch the surface of the substrate.

[0004]

When the actual substrate processing is performed by the conventional high frequency plasma processing apparatus having the above structure, the reaction product adheres to the inner wall of the discharge tube 20 and the adhered material is deposited on the substrate 25. It had the drawback of falling.

In view of the above problems, an object of the present invention is to provide a high frequency plasma processing apparatus which prevents the reaction products in the discharge tube from falling onto the substrate.

[0006]

A high-frequency plasma processing apparatus according to the present invention comprises a vacuum container provided with a discharge tube formed of a dielectric material, and an exhaust mechanism for reducing the pressure inside the container. It is equipped with a gas introduction mechanism that introduces a reaction gas into the container, a high-frequency supply mechanism that supplies high-frequency power into the discharge tube to turn the reaction gas into plasma, and a substrate holding mechanism that is arranged inside the container so as to face the discharge tube. , And the discharge tube
An electrode to which a bias voltage is applied is provided at a position facing the substrate holding mechanism.

In the above structure, the surface of the electrode is preferably coated with carbon or a compound containing carbon.

In the above structure, the surface of the electrode is preferably covered with a dielectric.

In the above structure, preferably, the bias voltage applied to the electrodes is a DC bias or an AC bias.

In the above structure, preferably, a temperature adjusting device for setting the surface of the electrode to an arbitrary temperature is provided.

In the above structure, preferably, a magnetic field generating mechanism for generating a magnetic field is provided inside the discharge tube.

[0012]

In the present invention, the space potential of the generated plasma is controlled by providing an electrode at a predetermined position (the surface facing the substrate) of the discharge tube which is the plasma generation mechanism and applying a predetermined bias voltage. Controls the ion energy introduced into the electrodes and substrate. This suppresses the reaction product from adhering to the inner wall of the discharge tube. This reduces the amount of reaction products dropped onto the substrate.

Further, by using carbon or a compound containing carbon as a coating film on the surface of the electrode, it is possible to prevent the coating film from being reactively etched by the generated plasma and to prevent reaction products from adhering to the electrode. To prevent it from falling on top. Furthermore, at the same time, the ion-etched electrode coating, that is, carbon reacts with unsaturated species or neutral active species to generate saturated species, so that the selectivity during etching can be improved. Further, by using a dielectric as a coating film on the electrode surface, it is possible to prevent the metal surface of the electrode from being etched and prevent impurities from adhering to the substrate.

By arbitrarily controlling the temperature of the electrode,
By controlling the adsorption rate of the reaction product adhering to the electrode surface, reducing the amount of the deposited film on the electrode surface and making the film quality dense, it is possible to prevent the reaction product from peeling off from the electrode surface.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the configuration of a high frequency plasma processing apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a diffusion chamber which is a metal vacuum container and is held at a ground potential by a ground 1a. A substrate holding mechanism 2 is arranged inside the diffusion chamber 1, and a substrate 3 to be processed is arranged on the substrate holding mechanism 2. A DC power supply 6A and an AC power supply 7A are connected to the substrate holding mechanism 2. A discharge tube 4 having a metal electrode 5 is provided on the upper wall of the diffusion chamber 1. The discharge tube 4 is made of a dielectric material, and is fixed to the upper wall of the diffusion chamber 1 by the flange 4a thereof. Further, a DC power supply 6B and an AC power supply 7B are connected to the electrode 5. The DC power supply 6B and the AC power supply 7B are selectively used as needed as described later. The internal space of the discharge tube 4 is connected to the internal space of the diffusion chamber 1. The substrate holding mechanism 2 is located below the internal space of the discharge tube 4, and the substrate holding mechanism 2 and the substrate 3 mounted on the substrate holding mechanism 2 are arranged so as to face the electrodes 5.

An evacuation mechanism 8 is attached to the diffusion chamber 1, and the evacuation mechanism 8 evacuates the inner space of the diffusion chamber 1 and the discharge tube 4 to a required reduced pressure state. The exhaust mechanism 8
Includes oil diffusion pumps, turbo pumps, oil rotary pumps, etc.
A reaction gas introduction mechanism 9 is attached to the diffusion chamber 1.

A high-frequency applying antenna 10 for supplying high-frequency power into the discharge tube is wound around the discharge tube 4, and an electromagnetic coil 11 for applying a magnetic field is arranged around the high-frequency applying antenna 10.

Further, a temperature adjusting device 12 capable of adjusting the temperature of the electrode 5 to an arbitrary temperature is provided for the electrode 5. Further, the metal surface inside the electrode 5 is coated with carbon, a compound containing carbon, or a dielectric (dielectric ceramics or the like), as the case may be.

The high frequency plasma processing apparatus having the above structure operates as follows.

First, the interior space of the diffusion chamber 1 and the discharge tube 4 is evacuated to a required reduced pressure state by the exhaust mechanism 8 and then the reaction gas introduction mechanism 9 introduces the reaction gas into the diffusion chamber 1 for vacuum exhaustion. And continue to maintain a reduced pressure. The reaction gas introduced into the diffusion chamber 1 enters the inside of the discharge tube 4. Next, high frequency power is applied to the inside of the discharge tube 4 by the antenna 10 to generate high frequency discharge and generate plasma. In this case, by applying a magnetic field with the electromagnetic coil 11, it is possible to increase the plasma generation efficiency. Further, at this time, if a special high-frequency applying antenna is used as the antenna 10, it becomes possible to excite the helicon wave and obtain higher density plasma. The discharge conditions differ depending on the type of reaction gas used and the internal pressure. As a result, the reaction gas introduced into the discharge tube 4 is activated, and the surface of the substrate 3 placed on the substrate holding mechanism 2 is etched by the generated active species.

In the above structure, the electrode 5 is provided in the discharge tube 4 at a position facing the substrate holding mechanism 2, and a bias voltage is applied to the electrode 5. Based on this structure, when the surface of the electrode 5 is not covered and the surface having conductivity is exposed, a DC bias is applied by the DC power supply 6B to control the potential of the electrode 5 to an arbitrary potential. It is possible to control the space potential of plasma.
As a result, the energy of ions entering the substrate 3 to be processed can be controlled, and the processing speed and damage of the substrate 3 can be controlled. Further, the spatial potential due to the plasma generated in the discharge tube 4 is made constant, and thus the stability of the discharge is obtained,
Improved reproducibility can be achieved. By maintaining the electrode 5 at the ground potential, the spatial potential due to the plasma generated in the discharge tube 4 can be made constant, the stability of the discharge can be obtained, and the reproducibility can be improved.

Next, when the surface of the electrode 5 is coated with carbon or a compound containing carbon, the coating film itself of the electrode 5 is reactively ion-etched by the active species generated by the discharge, and Prevents reaction products from adhering to the surface. Therefore, the reaction product can be prevented from dropping onto the substrate 3. At the same time, the carbon released by the reactive ion etching reacts with the neutral active species F to generate volatile saturated species CF _3, etc. when the F-based gas is used as the discharge gas. It increases the relative proportion of ions in the plasma and improves the selectivity and etching profile. Further, instead of the DC power source 6B, the AC power source 7B
The discharge can be stabilized by applying an AC bias at.

When the surface of the electrode 5 is coated with a dielectric material, the surface of the electrode itself can be prevented from being etched by the discharge gas and the electrode 5 becoming a pollution source. When, for example, SiO ₂ (dielectric ceramics) is used as the dielectric material,
Since SiO ₂ is stable, it hardly reacts with the active species generated by the discharge. Also when a reaction occurs,
When an F-based gas is used as the discharge gas, Si and F react with each other to generate a volatile saturated species SiF _4, which does not affect the processing of the substrate 3. Also during this reaction,
The amount of oxygen released is very small and the substrate 3 is not essentially affected. Further, when the electrode 5 is coated with a dielectric film, the AC power supply 7 is used instead of the DC power supply 6B.
By applying an AC bias at B, the discharge can be stabilized.

The temperature adjusting device 12 controls the temperature of the surface of the electrode 5 provided on the discharge tube 4 to an arbitrary temperature. According to the temperature control of the electrode 5, the adsorption rate and the residence time are reduced,
The deposition rate of reaction products can be reduced. At the same time, by lowering the deposition rate, the film quality of the reaction product becomes more dense, which makes it difficult to drop the deposit. As a result, the yield can be improved and the time between maintenances can be lengthened.

By generating a magnetic field inside the discharge tube 4 by the electromagnetic coil 11, it is possible to increase the efficiency of plasma generation inside the discharge tube.

[0027]

As is apparent from the above description, the present invention has the following effects.

Since the electrode to which the bias voltage is applied is provided at a predetermined position in the discharge tube, the spatial potential of the plasma generated in the discharge tube can be controlled, and the ion energy can be controlled to generate the reaction on the wall surface in the discharge tube. It can prevent the adherence of objects. In addition, by forming a film of carbon or a compound of carbon on the surface of the electrode, reactive ion etching is caused to prevent reaction products from adhering to the electrode,
It is possible to prevent the reaction product from falling onto the substrate. By forming the dielectric film on the surface of the electrode, it is possible to prevent the metal surface of the electrode from being etched and prevent impurities from adhering to the substrate. Since a device for adjusting the temperature of the electrode is provided,
The adsorption rate of reaction products adhering to the electrode surface can be reduced, the amount of deposited film on the electrode surface can be reduced, and the film quality can be made dense to suppress peeling, preventing reaction products from falling onto the substrate. You can do it.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the structure of a high-frequency plasma processing apparatus according to the present invention.

FIG. 2 is a schematic sectional view showing the structure of a conventional high-frequency plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diffusion chamber 2 Substrate holding mechanism 3 Substrate 4 Discharge tube 5 Electrodes 6A, 6B DC power source 7A, 7B AC power source 8 Exhaust mechanism 9 Reactive gas introducing mechanism 10 High frequency applying antenna 11 Electromagnetic coil 12 Temperature adjusting device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H05H 1/46 9014-2G

Claims (6)

[Claims] 1. A container provided with a discharge tube formed of a dielectric, an exhaust mechanism for reducing the pressure inside the container, a gas introduction mechanism for introducing a reaction gas into the container, and a discharge tube inside the discharge tube. In a high-frequency plasma processing apparatus comprising a high-frequency supply mechanism for supplying high-frequency power to turn the reaction gas into plasma, and a substrate holding mechanism arranged in the container so as to face the discharge tube, the discharge tube holds the substrate. A high-frequency plasma processing apparatus comprising an electrode to which a bias voltage is applied at a position facing the mechanism. 2. The high frequency plasma processing apparatus according to claim 1, wherein the surface of the electrode is coated with carbon or a compound containing carbon. 3. The high frequency plasma processing apparatus according to claim 1, wherein the surface of the electrode is covered with a dielectric. 4. The high frequency plasma processing apparatus according to claim 1, wherein the bias voltage applied to the electrode is a DC bias or an AC bias. . 5. The high frequency plasma processing apparatus according to claim 1, further comprising a temperature adjusting device that sets the surface of the electrode to an arbitrary temperature. 6. The high frequency plasma processing apparatus according to claim 1, further comprising a magnetic field generation mechanism that generates a magnetic field inside the discharge tube.