Method and apparatus for depositing a monolayer on a three dimensional structure

A method, comprising:

• providing a substrate in a first position, the substrate having a surface that defines a substrate plane and a substrate feature that extends from the substrate plane, the substrate feature having at least one surface that extends at a non-zero angle with respect to the substrate plane, the surface feature comprising a set of sidewalls, a trench and a top surface;
• directing an ion beam through an extraction plate, arranged adjacent the substrate and parallel to the substrate plane, while the substrate is in the first position, the ion beam comprising angled ions that are incident on the substrate at a nonzero peak angle between 15 degrees and 45 degrees with respect to a perpendicular to the substrate plane, the ion beam effective to form a first sub-monolayer comprising a first species on the substrate feature including the at least one surface, wherein the first sub-monolayer is a uniform sub-monolayer that is formed uniformly on the set of sidewalls, the trench and the top surface;
• scanning the substrate from the first position, to a second position, along a path that is parallel to the substrate plane;
• and
• directing a molecular beam to the substrate when the substrate is in the second position when the first sub-monolayer is disposed on the substrate feature, the molecular beam being effective to form a second sub-monolayer of a second species that is configured to react with the first sub-monolayer of the first species to form a uniform monolayer of a product material on the substrate feature including on the set of sidewalls, the trench and the top surface.