Plasma processing apparatus

Abstract

The present invention provides a plasma processing apparatus. The apparatus includes a vacuum chamber, a plasma reactor arranged in the vacuum chamber for plasma processing, an RF power source for providing RF signals to the plasma reactor and an RF power transmission unit for transmitting RF signals from the RF power source to the plasma reactor inside the vacuum chamber. The RF power transmission unit includes a transmission line for transmitting RF signals and an outer conductor for shielding the electromagnetic field around the transmission line. The invention can effectively avoid the problem of electric discharge when RF signals transmit in a vacuum chamber, resulting in more security and less transmission power loss.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application is a 35 U.S.C. §371 National Phase conversion of International (PCT) Patent Application No. PCT / CN2011 / 078063, filed on Aug. 5, 2011, the disclosure of which is incorporated by reference herein. The PCT International Patent Application was filed and published in Chinese.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to solar cell manufacturing, and more particularly, to a plasma processing apparatus for fabricating thin film solar cells.[0004]2. Background of the Invention[0005]Recently, large-area plasma processing apparatus have been widely used in the semiconductor field, such as thin film deposition or etching, for manufacturing such as flat panels and thin film solar cells. Radio-frequency (RF) power and frequency required for plasma processing are becoming higher and higher with the increase of processing size.[0006]In the current large-area plasma processing app...

AI Technical Summary

Benefits of technology

[0008]An objective of the present invention is to provide a plasma processing apparatus in which discharging is avoided when RF signals are transmitted in a vacuum chamber.

[0017]Compared with the prior art, the present invention may have following advantages: The RF power transmission unit has an outer conductor to shield the electromagnetic field around the transmission line, and thus RF signals can be effectively prevented from discharging in the vacuum chamber. The closed electromagnetic shielding body provided by the outer conductor, the outer wall of the plasma reactor, the inner wall of the vacuum chamber can further enhance the shielding effect from the electromagnetic field around the transmission line. The transmission line as a cylinder and the outer conductor with a cylindrical inner surface are coaxial and capable of maintaining a constant gap distance therebetween.

[0018]Particularly, the diameter of transmission line is greater than or equal to 10 mm, while the gap distance is equal to or less than 10 mm. On the one hand, such a design can guarantee low impedance of transmission line and low equivalent inductance of the RF power transmission unit, which helps to reduce power losses of the RF power transmission unit and reduce glowing power of the plasma processing apparatus; On the other hand, it can also enhance the minimum discharge voltage of RF signals within the gap between the transmission line and the outer conductor so as to avoid the occurrence of discharge phenomenon. Furthermore, the gap larger than 1 mm between the outer conductor and the transmission line can guarantee effective insulation.

Problems solved by technology

The discharge generated in the vacuum chamber may cause problems as follows: RF signals can not be effectively transmitted to the plasma reactor due to power losses, which may affect the plasma processing.

High power discharge may destroy the transmission line, RF power source and other electronic circuits of the apparatus, and even bring about safety accidents.

Therefore, how to transmit RF signals effectively and safely has become an urgent problem to be solved for the plasma processing apparatus.

Theoretically, increasing vacuum degree can reduce the probability of discharge, but it is hardly possible to create an environment with absolute vacuum.

Moreover, the increase of vacuum degree also correspondingly increases the use cost of apparatus.

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