JPH0748487B2 - Dry thin film processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is based on dry etching using microwave plasma and CVD (Chemical Vapor Deposition, a reaction in which a gaseous substance reacts to deposit a solid on a substrate). A thin film processing apparatus capable of forming a film, comprising means for generating microwaves, means for transmitting the microwaves, and the microwave transmitting means coupled via a plate-shaped vacuum window made of a dielectric material. Excitation for generating lines of magnetic force in which microwaves are introduced through a vacuum window and the gas introduced through the gas supply means is turned into plasma by a resonance effect with the microwaves to generate active atoms, molecules or ions. A plasma generating chamber having a solenoid and having an opening on the side facing the microwave transmission means, the opening having an axis coincident with the central axis of the magnetic flux of flux generated by the solenoid; A processing chamber in which a substrate is arranged, on which a surface is etched or a thin film is formed by the active atoms, molecules or ions that are coupled through an opening and flow out from the opening along the magnetic flux line, and the plasma generation The present invention relates to an apparatus provided with an exhaust means for exhausting the chamber and the processing chamber.

[Conventional technology]

In the technical field to which the present invention belongs, a process technology using ECR plasma has recently attracted attention. What is ECR Elect
ron Cyciotron Resonamce
It is an abbreviation for accelerating the electrons by using the resonance effect of the magnetic field and the microwave, and ionizing the gas by using the kinetic energy of the electrons to obtain plasma. Electrons excited by microwaves move circularly around the lines of magnetic force, where the centrifugal force and Lorentz force balance is called the ECR condition. When the centrifugal force is represented by mrω ² and the Lorentz force is represented by −qrωB, the condition for balancing these is ω / B = q / m. Where ω is the angular velocity of the microwave, B is the magnetic flux density, and q /
m is the specific charge of the electron. The microwave frequency of 2.45 GHz, which is recognized for industrial use, is generally used and in that case 0.0
875T is the resonance magnetic flux density.

For example, the second as a thin film processing device applying ECR plasma
The method shown in the figure is known. In this apparatus, the plasma generation chamber 3 and the processing chamber 9 are evacuated by an unillustrated evacuation means, and the raw material gas introduction pipe line 4 as a gas supply means is used.
Where N ₂ gas is allowed to flow into the plasma generation chamber 3, the waveguide 1 serving as a means for transmitting the microwave and the waveguide side under atmospheric pressure and the metal container evacuated to atmospheric pressure Three
It is sent to the plasma generation chamber 3 through a vacuum window 2 for airtightly separating the inside. A metal plate 17 having a large-diameter hole 7 in the center is attached to the lower part of the plasma generation chamber 3, and the metal plate and the plasma generation chamber 3 form a semi-open microwave resonator. Since the solenoid 6 is arranged outside the resonator and a magnetic field satisfying the ECR condition is generated inside the resonator, ECR plasma is generated inside the resonator. This plasma is pushed out into the processing chamber 9 and the sample table 10
When a silane gas (SiH ₄ ) is sent from the gas inlet 12 into the space heading toward the space and the gas is activated by the plasma, the generated active species reacts with the substrate 11 that is the sample to be processed to form a thin film on the substrate surface. To be done.

By flowing the etching gas instead of the N ₂ gas from the raw material gas introduction conduit 4, this apparatus can also be used for etching the substrate. A cooling pipe 5 cools the plasma generation chamber 3.

In the thin film processing apparatus configured as described above, the waveguide 1
Window 2 for passing microwaves that have propagated inside
In the past, a plate made of aluminum oxide (hereinafter, the common term: alumina) was used or a quartz plate was used.

[Problems to be solved by the invention]

The conventional problems when using a vacuum window made of an alumina or quartz plate are as follows. That is, in the case of a vacuum window made of an alumina plate, alumina having a purity of 99% or less is used. Therefore, a part of the microwave energy passing through the alumina plate is absorbed by the alumina plate and the alumina plate is Attempting to inject microwaves of about 1 KW or more into the plasma generation chamber, which had been heated, risked destruction due to strain due to the heat absorbed by the alumina plate. When the alumina plate is destroyed, the air in the waveguide flows into the plasma generation chamber and the processing chamber, and the load for exhausting against the vacuum exhaust system suddenly increases, which is not only harmful, but also used for thin film processing. , Outflow of harmful gas to human body is very dangerous. Further, even when a quartz plate is used for the vacuum window, there is a problem that the surface of the plasma generation chamber is scraped by the plasma of the etching gas.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a vacuum window capable of safely introducing a microwave power of 1 KW or more into a plasma generation chamber both manually and mechanically. A thin film processing apparatus is provided.

[Means for solving problems]

This invention absorbs the vacuum window, heats the vacuum window and gives thermal distortion to the vacuum window, and at 1 KW or more, a part of the microwave energy that can destroy the vacuum window is a plate that constitutes the vacuum window. It is caused by impurities in the rectangular dielectric, and the amount of absorbed heat, that is, the dielectric loss can be reduced by reducing the impurities, and the material of the vacuum window is made to have a small dielectric loss. At the same time, even if the vacuum window is broken, the vacuum in the vacuum container is broken, that is, the degree of vacuum is moderately lowered, so that a sudden increase in the load of the vacuum exhaust system can be prevented, so that the device of the present invention can be prevented. That is, the means for generating microwaves, the means for transmitting the microwaves, and the microwave transmitting means coupled through the plate-shaped vacuum window made of a dielectric material allow the microwaves to be introduced through the vacuum window. In addition, it is equipped with an exciting solenoid for generating a magnetic force line for generating a magnetic field line that generates active atoms, molecules or ions by plasmaizing the gas introduced through the gas supply means by the resonance effect with the microwave, and the axis line causes the solenoid. A plasma generating chamber having an opening on the side facing the microwave transmission means, which coincides with the central axis of the magnetic flux, and the active atoms flowing out along the magnetic flux from the opening coupled through the opening; In a dry thin film processing apparatus comprising a processing chamber in which a substrate whose surface is etched by molecules or ions or in which a thin film is formed is arranged, and an exhaust means for exhausting the plasma generation chamber and the processing chamber, The vacuum window that allows microwaves to pass has a multiple window structure in which plate dielectrics are stacked in multiple layers at small intervals. The plate-shaped dielectric material formed facing the plasma generation chamber is assumed to have corrosion resistance to the gas used for film processing, and the remaining plate-shaped dielectric material is a dielectric material more than the dielectric material facing the plasma generation chamber. The loss shall be small.

[Action]

In this way, by making the vacuum window a multi-window structure, the plate-shaped dielectric on the plasma generation chamber side is highly corrosive to the gas used for film processing, for example, an alumina plate is used as in the conventional case. In addition to prolonging its service life, the alumina of this alumina plate is of high purity, for example, 99.9% pure.
The above alumina enables passage of microwaves having energy of about 1 KW or more, while the plate-shaped dielectric on the waveguide side is not as high as the alumina plate as the corrosive plate against the gas used for film processing. However, the dielectric loss is smaller than that of a high-purity alumina plate, and therefore there is no risk of thermal destruction.
For example, if a quartz plate is used, and even if the alumina plate on the vacuum vessel side is thermally damaged, this quartz plate will prevent the outside air on the waveguide side from flowing into the plasma generation chamber, resulting in a slow leak condition. Therefore, the load on the vacuum exhaust system is kept small, and there is sufficient time margin for the necessary measures for repairing the device, such as stopping the microwave generation, stopping the gas supply, and stopping the motion of the vacuum exhaust system. It is possible to easily transfer to equipment repair, and prevent gas that is harmful to the human body, such as silane gas (SiH ₄ ), from flowing out from the plasma generation chamber, and this gas can occur when it flows out. The risk of ignition can also be prevented.

〔Example〕

An embodiment of a dry type thin film processing apparatus constructed according to the present invention is shown in FIG. In the figure, the vacuum window 20 has an alumina plate 20a disposed on the plasma generation chamber 3 side with an alumina purity of 99.9% or more so that microwaves of about 1 KW or more can be passed through using a conventional device without any trouble. This alumina plate and a packing 21 are arranged on the waveguide side with the thickness of the packing 21 interposed therebetween, and a quartz plate 20b having a smaller dielectric loss is used to form plasma through the packing 21 sandwiching the alumina plate 20a on both sides. The chamber side and the waveguide side are airtightly shut off from each other.
The structure of the apparatus other than the vacuum window is the same as that shown in FIG. 2, and the description thereof will be omitted.

In the vacuum window configured in this manner, if the alumina plate 20a on the plasma generation chamber side is destroyed due to the microwave energy absorbed by it, the impact of plasma particles in the plasma generation chamber, or the like, and falls off, for example, During the etching process, the surface of the quartz plate 20b disposed on the waveguide side on the plasma generation chamber side is exposed to the plasma of the etching gas and begins to be corroded, and the packing 21
Is affected by the destruction and drop-off of the alumina plate, and it is not always possible to maintain the same airtight condition as before the destruction, and the outside air on the waveguide side begins to enter the plasma generation chamber. However, since the destruction of the alumina plate 20a usually occurs in the central part except the packing 21, the airtightness is extremely low, and therefore the ingress of outside air is extremely slow, resulting in a so-called slow leak condition. Therefore, the load on the vacuum exhaust system will not suddenly increase and the function of the exhaust system will not be lost.After the alumina plate is destroyed, the generation of microwaves is stopped and the gas supply for film processing is stopped. However, a sufficient time margin is provided to stop the operation of the vacuum exhaust system and shift to the repair of the device.

〔The invention's effect〕

As described above, according to the present invention, a vacuum window that hermetically shields the plasma generation chamber from the waveguide side and allows microwaves to pass is formed by stacking plate dielectrics in multiple layers at small intervals. In addition to the multi-window structure, the plate-shaped dielectric that constitutes the vacuum window facing the plasma generation chamber should be corrosion resistant to the gas used for film processing, and the remaining plate-shaped dielectric should generate plasma. Since it is made of a material with a dielectric loss smaller than that of the dielectric facing the chamber, it is corrosion resistant to the gas used for film processing on the plasma generation chamber side, which is subjected to severe stress due to heat. Even if the plate-shaped dielectric material is destroyed, the airtight function of the remaining plate-shaped dielectric material is almost maintained and only a slow leak state occurs.
As a result, the function of the vacuum exhaust system is maintained without being impaired, so that there is sufficient time margin such as stopping the generation of microwaves, stopping the gas supply for film processing, and stopping the operation of the vacuum exhaust system. , The device can be easily repaired, and the plate-shaped dielectric placed on the waveguide side prevents the harmful gas to human body from flowing out from the plasma generation chamber, and the gas has flowed out. The danger of ignition that may occur when this is done is also prevented, and the effect is that the operation of the device can be carried out very completely with respect to the human body.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a dry thin film processing apparatus having a vacuum window according to an embodiment of the present invention, and FIG. 2 is a vertical sectional view of a conventional dry thin film processing apparatus. 1: Waveguide (microwave transmission means), 2, 20: Vacuum window, 3: Plasma generation chamber, 4: Gas supply means, 6: Excitation solenoid,
7: opening, 9: processing chamber, 11: substrate.

Claims (3)

[Claims] 1. A microwave generating means, a means for transmitting the microwave, and a microwave which is coupled to the microwave transmitting means via a plate-shaped vacuum window made of a dielectric material. And a gas supplied through the gas supply means is turned into plasma by the resonance effect with the microwave to generate magnetic lines of force that generate active atoms, molecules or ions, and the axis line is A plasma generation chamber having an opening on the side facing the microwave transmission means, the opening coinciding with the central axis of the magnetic flux of magnetic force generated by the solenoid, is connected through the opening, and the active gas flowing out along the magnetic flux of flux from the opening. A processing chamber in which a substrate whose surface is etched or a thin film is formed by atoms, molecules or ions is placed, and exhaust of the plasma generation chamber and the processing chamber In a dry thin film processing apparatus having an exhausting means for performing the vacuum window, the vacuum window for passing the microwave has a multiple window structure in which plate dielectrics are stacked in multiple layers at small intervals, and the vacuum window is configured. The plate-shaped dielectric material that faces the plasma generation chamber is assumed to have corrosion resistance to the gas used for film processing, and the remaining plate-shaped dielectric material has more dielectric loss than the dielectric material that faces the plasma generation chamber. A dry thin film processing device characterized by being made of a small size. 2. The dry thin film processing apparatus according to claim 1, wherein the plate-shaped dielectric member facing the plasma generation chamber is made of aluminum oxide, and the remaining plate-shaped dielectric member is made of a quartz plate. A dry type thin film processing device characterized in that 3. The dry thin film processing apparatus according to claim 2, wherein the plate-shaped dielectric made of aluminum oxide is made of aluminum oxide having a purity of 99.9% or more. Thin film processing equipment.