SELECTIVE TRENCH MODIFICATION USING DIRECTIONAL ETCH

Disclosed herein are approaches for device modification, namely, trench elongation. In one approach, a method may include providing a substrate including a plurality of surface features defining a plurality of trenches, wherein a first trench has a first trench length extending in a first direction, wherein a second trench connected to the first trench has a second trench length extending in a second direction, and wherein the first direction and the second direction are non-parallel. The method may further include delivering ions into the substrate in a reactive ion etching process, wherein the ions are delivered at a non-zero angle relative to a perpendicular extending from the substrate, and wherein the reactive ion etching process increases the first trench length of the first trench without increasing the second trench length of the second trench.