The
semiconductor industry’s transition to three-dimensional
(3D) logic and memory devices has revealed the limitations of plasma
etching in reliable creation of vertical high aspect ratio (HAR) nanostructures.
Metal-assisted chemical etch (MacEtch) can create ultra-HAR, taper-free
nanostructures in silicon, but the catalyst used for reliable MacEtchgoldis
not CMOS (complementary metal–oxide–semiconductor)-compatible
and therefore cannot be used in the semiconductor industry. Here,
for the first time, we report a ruthenium MacEtch process that is
comparable in quality to gold MacEtch. We introduce new process variablescatalyst
plasma pretreatment and surface areato achieve this result.
Ruthenium is particularly desirable as it is not only CMOS-compatible
but has also been introduced in semiconductor fabrication as an interconnect
material. The results presented here remove a significant barrier
to adoption of MacEtch for scalable fabrication of 3D semiconductor
devices, sensors, and biodevices that can benefit from production
in CMOS foundries.