Inductively Coupled Plasmas: Optimizing the Inductive-Coupling Efficiency for Large-Area Source Design

An inductively coupled plasma (ICP) source enabling high-density plasma generation was developed for large area processing. Technological difficulties related to the scaling up of the coil antenna, dielectric vacuum window, and gas distribution have been addressed. The proposed solution consists in using a magnetic core to concentrate the magnetic field produced by the antenna. Both are placed within the plasma chamber, and the gas injection is done through the magnetic pole. A 75×72- cm2 plasma source has been designed based on this solution. First, the electrical operation and coil geometries were optimized. The results show that the use of a low excitation frequency (2 MHz) increases the electrical efficiency of the magnetic core, enabling a higher plasma-density generation than at the classical radio frequency of 13.56 MHz. The antenna configuration providing the better uniformity is composed of three loops connected in parallel. Some tuning inductances in series with each loop were added to balance the rf power, i.e., the plasma density over the reactor area. Deviation from plasma uniformities better than 12% over 60×60 cm2 were achieved. Preliminary SiO2 etching experiments with CF4 gas show that the etching uniformity deviation reaches 7% over 60×60 cm2 with etching rates larger than 150 nm/min. These results are very promising and open the way to the successful scale-up of ICP sources to large areas.

COLPO Pascal;  MEZIANI Tarik;  ROSSI Francois; 

2006-02-02

AMERICAN VACUUM SOCIETY

JRC32085

https://publications.jrc.ec.europa.eu/repository/handle/JRC32085,