Effects of N 2 Addition on Aluminum Alloy Etching in Inductively Coupled Plasma Source

• Published in: Japanese Journal of Applied Physics 1999-10, Vol.38 (10R), p.6090
• Main Authors: Kim, Kil Ho, Baek, Kye Hyun, Shin, Kang Sup, Park, Changwook, Lee, Won Gyu
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.38.6090

Addition of N 2 to the plasma activated with Cl 2 , BCl 3 , or their mixtures in an inductively coupled plasma source induces drastic changes in the plasma state. These N 2 -related changes in the plasma state sometimes result in abnormal phenomena in aluminum alloy etching, like the wave-like fringes on the sidewalls of patterned metal lines. Optical emission spectroscopy revealed that admixing small amounts of N 2 to the plasma activated with Cl 2 , BCl 3 , or their mixtures generally expedites dissociation processes to increase the density of Cl * radicals within it. On the other hand, N 2 addition also accelerates the formation of passivation polymers via carbon species sputtered from patterned photo-resists. The polymers adhere to the sidewalls of patterned metal lines and protect them against the lateral attacks of deflected etchants such as Cl * radicals. Our studies tell that the relative abundance of Cl * radicals within the plasma over the passivation polymers, which is controlled by the amount of N 2 addition, seems to be a critical factor in determining the occurrence of the wave-like fringes on the sidewalls of patterned metal lines.