A fabrication method for silicon beams and membranes defined in lateral and vertical dimensions, as well as superposed silicon membranes, all realized in bulk silicon using only one lithographic step is proposed. This proposal is based on observations made on structures obtained by High Temperature Annealing (HTA) in hydrogen atmosphere process. The combination of design configuration and materials technology (hard mask) with the process shows the possibility of new 3D devices and cavities beyond previously reported capabilities of with this technique. The specific design and hard mask engineering presented can lead to structures used in a bulk silicon platform for 3D devices with optical and electronic functions for the fabrication of bulk silicon waveguides and transistors on stressed membranes with enhanced mobility.