A high-precision 3D structuring of dielectrics by sub-1 ps pulses is possible by dielectric breakdown and opens an unique possibility to create a high temperature electrons inside material under processing. The 3D nano/micro-structuring by dielectric breakdown is numerically simulated by 3D finite-differences time domain (FDTD) calculations where the plasma is simulated by a nano-sphere of metal (gold). The effect of anisotropic light scattering in the plane of incident polarization has been qualitatively explained by light inteaction with ionized (metalic) focal volume. It is shown that the experimentaly achieved densification of materials after irradiation by tightly focused sub-1 ps pulses is consistent with formation of new high-pressure phases.