We theoretically utilize bowtie aperture combined with the Metal-insulator-metal (MIM) scheme to obtain sub-30-nm (λ/12) high aspect plasmonic spot. The improvement of the depth profile is attributed to the asymmetry electromagnetic mode excitation in the metal-insulator-metal structure and the decaying compensation of the reflective metal layer. It is demonstrated that the depth profile of the 28 nm hot spot is more than 20 nm, which is about 4 times of the bowtie aperture without the MIM scheme. Futuremore, the spot of 47 nm diameter (FWHM) and 25 nm depth was achieved in photo-resist in the experiment, which demonstrated the advantages of the new structure on reducing the size and improving the depth profile of the spot.structure