Plasma characteristics and etch uniformity in CF4 magnetron etching using an annular permanent magnet

Abstract
Etch characteristics of SiO2 and Si obtained by magnetron etching using an annular permanent magnet were analyzed. From these analyses, etch characteristics were found to be classified into three regimes. Remarkable enhancements in SiO2 etch rate, 25–40 times, were observed at constant Vrf by applying magnetic field of 150 G. Ion densities over the cathode were found to be distributed linearly along the E×B drift direction. Such an ion density distribution will be formed by the repeated process (ionization→ion bombardment→electron emission and drift→ionization). Etch distribution can be averaged and flattened to a uniformity of below ±2% by the magnetic field being rotated in 90° steps.

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