= Solution
\b[Zero <step coverage>] means that a sidewall or hidden surface receives essentially no film even though a horizontal reference surface is coated. \b[<Deposition shadowing>] occurs when an upper edge intercepts trajectories that would otherwise reach a lower region. A directional high-vacuum evaporant flux can therefore coat a feature top while leaving vertical or reentrant walls uncoated.
<Sputtering> generally releases material from an extended target with a broad angular distribution; gas collisions can further redistribute arrival directions. More oblique trajectories can reach sidewalls, so the extreme zero-coverage behavior of an ideal collimated evaporant beam is reduced.
The absolute claim that these effects never occur in sputtering is too strong. Low-pressure directional sputtering and high-aspect-ratio or reentrant features can still exhibit shadowing and poor coverage. Broader incidence improves access; it does not make a physical deposition process universally conformal.
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