Tapered dielectric etch process for moat etchback

摘要

A tapered dielectric etch process that may be used for moat etchback in STI. After isolation trenches (14) are etched and filled, the invention may be used in the process to planarize the structure. First, a pattern (40), such as a reverse moat pattern is applied to the structure over the trench-fill material (16). The trench fill material (16) is then etched using the pattern (40). An isotropic etch is performed that removes the pattern (40) in the dense areas only. The isotropic etch may be combined with anisotropic etches performed prior to and/or after the isotropic etch to remove additional trench fill material (16). Thus, a significant amount of the excess trench-fill material (18) is removed prior to CMP. CMP may then be performed.