Direct current superposed dual-frequency capacitively coupled plasmas in selective etching of SiOCH over SiC
Autor: | Keigo Takeda, Hiroki Kondo, Tatsuya Komuro, Kenji Ishikawa, Tsuyoshi Yamaguchi, Makoto Sekine, Masaru Hori, Chishio Koshimizu, Seigo Takashima |
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Rok vydání: | 2011 |
Předmět: |
Amorphous silicon
Auxiliary electrode Materials science Acoustics and Ultrasonics Silicon Direct current Analytical chemistry chemistry.chemical_element Condensed Matter Physics Surfaces Coatings and Films Electronic Optical and Magnetic Materials chemistry.chemical_compound chemistry Etching (microfabrication) Wafer Silicon oxide DC bias |
Zdroj: | Journal of Physics D: Applied Physics. 45:025203 |
ISSN: | 1361-6463 0022-3727 |
Popis: | Superpositioning of negative dc bias in dual-frequency capacitively coupled plasmas (dc-superposed (DS)-CCP) was realized for the selective etching of carbon-doped silicon oxide (SiOCH) films over carbon-doped amorphous silicon (SiC) films, while the dc bias exceeded about −800 V. When a dc bias of −1200 V was superposed on 60 MHz VHF power on the top electrode opposed to a wafer on the bottom electrode biased with 13.56 MHz power, a selectivity of above 50 for SiOCH over SiC was obtained. From characterization of the plasma density and various chemical species in the gaseous phase, such as CF2, CF and atomic N, the density of CF2 significantly decreased with the application of dc bias ranging from −800 to −1200 V. This indicated that CF2 radicals were consumed at the surface of the counter electrode which was made of silicon. The bulk densities of the species including CF2 were decreased, especially due to excess surface loss caused by the bombardment of highly energetic ions accelerated by the superposed dc bias, as well as the rf sheath for the superposition of the negative dc bias. The DS-CCP technology is thus concluded to be indispensable for yielding highly selective etching of SiOCH over SiC. |
Databáze: | OpenAIRE |
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