Exemplary methods of forming a semiconductor device may include etching a trench from a first surface of a semiconductor substrate to a first depth within the semiconductor substrate. The trench may be characterized by a first width through the first depth. The methods may include forming a liner along sidewalls of the trench. The methods may include etching the trench to a second depth at least ten times greater than the first depth. The trench may be characterized by a second width through the second depth. The methods may include filling the trench with a dielectric material. A seam formed in the dielectric material may be maintained below the first depth.