Method of limiting the lateral extent of a trench capacitor by a dielectric spacer in a hybrid orientations substrate is provided. The dielectric spacer separates a top semiconductor portion from an epitaxially regrown portion, which have different crystallographic orientations. The deep trench is formed as a substantially straight trench within the epitaxially regrown portion such that part of the epitaxially regrown portion remains overlying the dielectric spacer. The substantially straight trench is then laterally expanded to form a bottle shaped trench and to provide increased capacitance. The lateral expansion of the deep trench is self-limited by the dielectric spacer above the interface between the handle substrate and the buried insulator layer. During subsequent formation of a doped buried plate, the dielectric spacer blocks diffusion of dopants into the top semiconductor portion, providing a compact bottle shaped trench capacitor having high capacitance without introducing dopants into the top semiconductor portion.