Semiconductor fabrication process for modifying the profiles of patterned features

A method for forming a sacrificial layer ( 30 ) over patterned structures ( 28 ) to allow structures ( 28 ) to be trimmed laterally without incurring much loss vertically. Structures ( 28 ) are patterned on a first layer ( 26 ) of a substrate ( 24 ). Thereafter, sacrificial layer ( 30 ) is deposited on structures ( 28 ). During this deposition, the thickness of sacrificial layer ( 28 ) grows vertically above structures ( 28 ) faster than it grows laterally adjacent to the structures' sidewalls. Sacrificial layer ( 30 ) and patterned structures ( 28 ) are then etched where the etch rate uniformity ensures that the sacrificial layer ( 30 ) covering the sidewalls is cleared before the sacrificial layer covering the horizontal portions thereby enabling etching of the patterned structure sidewalls without reducing the patterned structure height. The sacrificial layer may comprise a polymer formed with a low energy fluorocarbon plasma while the subsequent etch may employ an oxygen plasma.