In this Letter, 40 nm thick photoresist (PR)-compatible plasmonic nanolithography using a bowtie aperture incorporated with a metal-insulator-metal (MIM) structure is studied numerically and experimentally. The simulation results show that with a 20 nm index-matching layer, the light field that exits from the bowtie aperture penetrates into a 40 nm thick PR by using a MIM configuration. Imaging contrast calculations indicate that sub-45 nm resolution with an exposure depth in the order of tens of nanometers is achievable, which is confirmed by the experimental results. In addition, the ability to generate high-resolution, complex patterns using this technique via scanning is demonstrated. This brings plasmonic nanolithography using a bowtie aperture one step closer to practical applications.