The present disclosure, in some embodiments, relates to a method of semiconductor processing. The method may be performed by etching a substrate to define a trench within the substrate. A sacrificial material is formed within the trench. The sacrificial material has an exposed upper surface. A plurality of discontinuous openings are formed to expose separate segments of a sidewall of the sacrificial material. The plurality of discontinuous openings are separated by non-zero distances along a length of the trench. An etching process is performed to simultaneously etch the exposed upper surface and the sidewall of the sacrificial material.