Semiconductor trench inductor and transformer structures are provided, which include thin film conductive layers and magnetic layers formed within trenches etched in semiconductor substrates. Semiconductor trench devices effectively provide vertical oriented inductor and transformer structures whereby conductive coils and magnetic layers are vertically oriented on edge within trenches, thereby providing a space-saving compact design, and which allows the conductive layers within the trench to be enclosed by magnetic material, thereby providing a density of magnetic material that increases the storable energy density.