Sensitivity and contrast of indium nitrate hydrate resist evaluated by low-energy electron beam and extreme ultraviolet exposure

We evaluate the sensitivity and contrast of indium nitrate resists by analyzing dose curves collected using electron beam lithography (EBL) and extreme ultraviolet (EUV) exposure. Three electron beam energies are tested: 100 eV, 2 keV, and 10 keV, with the dose calibrated via Faraday cup measurements. Atomic force microscopy measures the remaining resist height after EBL exposure and development for each dose. Multiple dose curves are collected at 100 eV to obtain an average contrast of 2.2 +/- 0.7 and a sensitivity of 210 +/- 100 mu C/cm(2). Benchmarking against an organotin-cluster resist (contrast of 0.9 and a sensitivity of 210 mu C/cm(2)) shows that indium nitrate exhibits comparable sensitivity and contrast. A post-exposure bake (PEB) condition of 90 degrees C for 1 min produces a noticeable leftward shift in the dose curve, corresponding to increased sensitivity. In addition, flood gun EUV exposure demonstrates a solubility switch with a sensitivity of 21mJ/cm(2) and a remaining resist thickness of 14 nm without PEB, comparable to or better than tin-based resists. The combination of high sensitivity, good contrast, and EUV response highlights indium nitrate as a strong candidate for next-generation EUV lithography. (c) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.