Magnetization losses in submicrometer CoFeB dots etched in a high ion density Cl2-based plasma

Faceting of the etch masks and chlorinated etch residues can reduce the magnetization of patterning magnetic materials substantially, and therefore, constitutes a considerable concern. To get more insight into the magnetization losses, CoFeB dots were etched in a high ion density Cl2-based plasma with a width ranging from 0.3to6.4μm. The magnetic properties of the CoFeB dots were measured by magnetometry. Submicrometer CoFeB dots showed significant magnetization reductions despite H2O rinsing. Scanning electron microscopy (SEM) studies revealed that etching in a Cl2-based plasma caused faceting of the masks, leading to sloped sidewalls. SEM pictures were used to determine the geometric volume, which was compared to the effective magnetic volume resulting from the magnetometry measurements. The SEM data are in good agreement with the magnetometry data, and a chloride penetration depth of only a few nanometers could be derived, indicating that the postetch rinsing is sufficient to prevent considerable corro...