Semiconductor structures and methods for suppressing latch-up in bulk CMOS devices. The structure comprises a first doped well formed in a substrate of semiconductor material, a second doped well formed in the substrate proximate to the first doped well, and a deep trench defined in the substrate. The deep trench includes sidewalls positioned between the first and second doped wells. A buried conductive region is defined in the semiconductor material bordering the base and the sidewalls of the deep trench. The buried conductive region intersects the first and second doped wells. The buried conductive region has a higher dopant concentration than the first and second doped wells. The buried conductive region may be formed by solid phase diffusion from a mobile dopant-containing material placed in the deep trench. After the buried conductive region is formed, the mobile dopant-containing material may optionally remain in the deep trench.