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Expect appreciable but nonuniform sidewall coverage, rounded upper edges and possible narrowing near the opening mouth. In sputtering, gas collisions and the extended source distribute arriving material over a broader range of directions than simple high-vacuum evaporation. At the specified pressure, the extent of that redistribution also depends on source-to-substrate distance and particle energies; pressure alone does not determine a unique sidewall thickness.

The top surfaces receive the nominal film. Oblique rays coat accessible walls, while the tall opening shadows some directions from its lower portions. Growth at the mouth can further shadow the floor or form an overhang. The sidewall film is therefore neither guaranteed zero nor guaranteed as thick as the horizontal film. This step coverage is generally unfavorable for clean lift-off process if it connects the film on the resist to the film on the substrate.

Zero step coverage means that a sidewall or hidden surface receives essentially no film even though a horizontal reference surface is coated. 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.