Scanned angled etching apparatus and techniques providing separate co-linear radicals and ions

A method of treating a substrate, comprising:

• providing the substrate on a substrate stage, wherein a main surface of the substrate defines a substrate plane;
• directing an ion beam comprising ion flux to the substrate along a trajectory defining a non-zero angle of incidence with respect to a perpendicular to the substrate plane;
• directing a radical beam comprising radical flux to the substrate along a trajectory defining the non-zero angle of incidence with respect to the perpendicular to the substrate plane;
• and
• scanning the substrate along a first direction, the first direction lying with the substrate plane, while the main surface of the substrate is oriented within the substrate plane, wherein the radical flux is displaced along the first direction with respect to the ion flux at the substrate plane.

A reactive angled ion beam etching system, comprising:

• a substrate stage, arranged to support a substrate and to scan the substrate along a first direction, the first direction lying within a substrate plane, defined by a main surface of the substrate;
• a plasma chamber, the plasma chamber comprising an extraction assembly disposed along a side of the plasma chamber, and facing the substrate stage, the extraction assembly comprising a plurality of extraction electrodes, oriented to extract an ion beam comprising ion flux and direct the ion beam along a non-zero angle of incidence with respect to a perpendicular to the substrate plane;
• and
• a radical source, the radical source oriented to direct a radical beam comprising radical flux along a trajectory defining the non-zero angle of incidence with respect to the perpendicular to the substrate plane, and
• wherein a given region of the substrate is exposed to the ion beam and the radical beam in a sequential manner when the substrate is scanned along the first direction, wherein the radical flux is displaced along the first direction with respect to the ion flux at the substrate plane.