強磁性トンネル接合用Al薄膜の酸化過程とマイクロ波励起プラズマ中の酸化種との相関

概要

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Langmuir probe diagnosis and optical emission spectroscopy were performed for microwave-excited plasma in order to clarify the physical factor in changing the transport properties of Co-Fe / Al-O / Co-Fe magnetic tunnel junctions (MTJs) fabricated with Ar+O_2, Kr+O_2, He+O_2 plasma. The main results were as follows: (1) Kr reduces the electron temperature of plasma at the substrate position, minimizing the ion irradiation damage during formation of an ultra-thin Al-O barrier. (2) The oxidizing species excited in plasma, such as O-radicals and O_2-ions, are drastically changed with changes in the inert gas species mixed with oxygen. The maximum energy of oxidizing species corresponds closely to the energy level of inert gas radicals. (3) O(2p)^1D radicals, which have a long life, are effectively produced in Kr+O_2 plasma and lead to a high oxidization rate of Al films.
社団法人日本磁気学会の論文
2003-12-01