JPH0594972A - Plasma treatment device - Google Patents

Abstract

PURPOSE:To prevent the feeding part of an upper electrode from starting discharge in a plasma treatment chamber, where the upper electrode and a lower electrode are provided inside the plasma treatment chamber confronting each other, and a treatment substrate placed on the lower electrode is processed by plasma generated between these electrodes. CONSTITUTION:A cylindrical support shaft 13 whose inside is open to outside air is provided to the upside of an upper electrode 12 penetrating through the wall of a reaction chamber, and an electric power is fed to the upper electrode 12 through a feeding shaft 14 provided inside the support shaft 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus for processing a semiconductor substrate such as plasma etching.

[0002]

2. Description of the Related Art In recent years, an apparatus shown in FIG. 2 has been known as an apparatus for performing processing using plasma such as plasma etching and plasma ashing, which is an indispensable technique in the semiconductor manufacturing process. There is. This is configured such that the upper electrode 2 and the lower electrode 3 are provided in the processing chamber 1 so as to face each other, and the reaction gas is introduced while the pressure inside the processing chamber 1 is lowered to a predetermined pressure by the exhaust system 4. By applying high frequency power to the upper electrode 2 while introducing a reaction gas from the system 5, the surface of the processed substrate 6 placed on the lower electrode 3 is finely processed by the plasma generated between the electrodes 2 and 3. However, the power supply to the vertically moving upper electrode 2 is configured to be performed from the electrode 2 through the power supply shaft 7 that penetrates the wall of the processing chamber 1 and extends upward.

On the upper surface side of the electrode 2, an umbrella-shaped portion 9a is provided which faces the upper surface and the side surface of the electrode 2 with a predetermined gap L therebetween.
And a discharge prevention cover 9 composed of a cylindrical portion 9b arranged so as to face the outer periphery of the power supply shaft 7 with a gap L and penetrate the wall of the reaction chamber 1, and the wall of the reaction chamber 1 and this discharge prevention cover 9 are attached. A shaft seal 10 slidably seals between the cylindrical portion 9b of the cover 9 and a cylindrical portion 9b of the discharge prevention cover 9 and the power supply shaft 7 is provided near the upper end of the cylindrical portion 9b. It was configured to be sealed by the seal 11.

The discharge prevention cover 9 is provided in this way in order to prevent problems caused by discharge from portions other than the lower surface of the upper electrode 2. That is, the upper electrode 2
When a discharge is generated from a portion other than the lower surface of the substrate, the loss of the applied high-frequency power increases, the processing speed of the substrate decreases, the anisotropy in etching etc. deteriorates, and the desired device performance is not exhibited. This is because, since discharge occurs in a portion that does not discharge, seals in the vicinity of the discharge are corroded by plasma, resulting in a problem that the life is greatly reduced.

[0005]

However, with the above-mentioned conventional structure, it is necessary to set the gap L to a predetermined value over the whole, which is difficult to manufacture and the gap L cannot be set properly. Therefore, despite the above structure, the above-mentioned extra discharge may occur. That is, the space between the discharge prevention cover 9 and the electrode 2 or the power supply shaft 7 has the same pressure (high vacuum) as that in the processing chamber 1, so the gap L is set to a predetermined value based on the theory of discharge in vacuum. If it is not, discharge cannot be prevented.

It is conceivable that an insulator having a predetermined thickness is interposed between the upper electrode 2 or the power supply shaft 7 and the discharge prevention cover 9 to set the gap L to a predetermined value. A water pipe or the like (not shown) for adjusting the temperature of the upper electrode must be arranged in this gap, and at least the periphery of the power supply shaft 7 (the cylindrical portion 9b) due to a problem such as interference with these.
It is extremely difficult in practice to interpose an insulator on the inner side of), and it is particularly difficult to prevent discharge from the power supply shaft 7.

The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide a plasma processing apparatus in which discharge from the power supply portion of the upper electrode is reliably prevented.

[0008]

In a plasma processing apparatus of the present invention, an upper electrode and a lower electrode are provided in a processing chamber so as to face each other, and the plasma is generated between these electrodes and placed on the lower electrode. A plasma processing apparatus for processing a processing substrate, wherein a cylindrical support shaft that penetrates a wall of a reaction tank and extends to the outside and is open to the atmosphere is provided on the upper surface of the upper electrode. It is characterized in that the power feeding is performed by a power feeding shaft arranged in the support shaft.

[0009]

With the above structure, since the pressure around the power supply shaft is always atmospheric pressure, discharge from the power supply shaft (supporting the power supply shaft and the support shaft does not occur) without adjusting the distance between the power supply shaft and the support shaft to a delicate value. Discharge between shafts) is reliably prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plasma processing apparatus according to an embodiment of the present invention will be described below with reference to FIG. The same components as those of the conventional device shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.

This apparatus has a cylindrical support shaft 13 which is mounted on the center line of the upper surface of the upper electrode 12 and extends through the wall of the reaction chamber 1 so as to extend upward. The upper electrode 12 is supported and moved up and down, and the power supply shaft 14 disposed in the support shaft 13 supplies power from the high frequency power source 8 to the upper electrode 12. An insulating cover 15 is provided on the upper surface and the side surface of the upper electrode 12 except for the portion where the feeding shaft 14 extends.
Is attached, and this surface is covered with a discharge prevention cover 16 except for the portion where the support shaft 13 is attached.

Here, the support shaft 13 has a flange 1 at the lower end.
3a is formed, and is attached in a state where the end surface of the flange 13a is joined to the upper surface of the insulating cover 15. The joint surface at the lower end of the support shaft 13 is sealed by a seal 17, and the outer periphery thereof and the wall of the reaction chamber 1 are sealed by a shaft seal 18, but the upper end of the support shaft 13 is closed at the reaction chamber. 1 is open to the outside (atmosphere). That is, with such a configuration, the inside of the support shaft 13 (the feeding shaft 1
The atmosphere around 4) is always introduced.

Next, the power supply shaft 14 is formed so as to extend upward from the center of the upper surface of the upper electrode 12. In this case, the power supply shaft 14 functions as a conductive portion for connecting the high frequency power source 8 to the upper electrode 12, and at the same time, reacts. It also functions as a flow path for supplying the reaction gas from the gas introduction system 5 into the upper electrode 12. The insulating cover 15 is made of a material such as ceramics, and its thickness is set to a value that does not cause discharge from the upper surface or the side surface of the upper electrode 12.

In the apparatus shown in FIG. 1, plasma can be generated between the upper electrode 12 and the lower electrode 3 to process the substrate 6 according to the same principle as in the prior art, but unlike the prior art. The extra discharge from the upper electrode 12 is surely prevented. That is, since the pressure around the power supply shaft 14 is always atmospheric pressure, even if there is some variation in the distance between the power supply shaft 14 and the support shaft 13, the discharge withstand voltage during this period is sufficiently secured and the discharge from the power supply shaft ( (Discharge between the power supply shaft and the support shaft)
There is no danger of In addition, the discharge from the upper surface or the side surface of the upper electrode 12 depends on the thickness of the insulating cover 15.
The distance between the two is prevented by the discharge prevention cover 16 whose reliability is maintained at a proper value.

Therefore, with this apparatus, the above-mentioned problems due to excessive discharge do not occur, and the substrate can be processed with good yield while maintaining a high processing speed. Moreover, there is no need for delicate setting of the gap as in the device shown in FIG. 2 described above, and there is no insulating material around the power supply shaft so that water pipes for temperature adjustment can be easily arranged. Since it can be installed, it also has the feature of being easy to manufacture.

[0016]

As is apparent from the above description, in the plasma processing apparatus of the present invention, discharge from the power supply portion of the upper electrode, which has been difficult to prevent in the past, is prevented, and a high processing speed is achieved. There is an effect that the substrate can be processed with a good yield while maintaining it.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a plasma processing apparatus of the present invention.

FIG. 2 is a side sectional view showing a conventional plasma processing apparatus.

[Explanation of symbols]

 1 Reaction Chamber 3 Lower Electrode 6 Processed Substrate 12 Upper Electrode 13 Support Shaft 14 Feeding Shaft

Claims (1)

[Claims] 1. A plasma processing apparatus in which an upper electrode and a lower electrode are provided in a processing chamber so as to face each other, and a processing substrate placed on the lower electrode is processed by plasma generated between the electrodes. A cylindrical support shaft is provided on the upper surface of the upper electrode so as to extend through the wall of the reaction tank to the outside and the inside is open to the atmosphere, and the power supply to the upper electrode is arranged in the support shaft. A plasma processing device, which is configured to be performed by a shaft.