Structure to reduce etching residue

摘要

A structure for reducing partially etched materials is described. The structure includes a layout of an intersection area between two trenches. First, a large intersection area having a trapezoidal corner may be replaced with an orthogonal intersection between two trenches. The layout reduces the intersection area as well as the possibility of having partially etched materials left at the intersection area. The structure also includes an alternative way to fill the intersection area with either an un-etched small trapezoidal area or multiple un-etched square areas, so that the opening area at the intersection point is reduced and the possibility of having partially etched materials is reduced too.