Ion beam exposure of PMMA polymer resist

Abstract

Ion beam exposure characteristics of the polymer resist polymethylmethacrylate (PMMA) have been examined. The samples were bombarded by H +, He +, Li +, and As + ions in the energy range from 60 to 200 keV varying the ion dose between 1 × 10 11 and 3 × 10 13 cm −2. The development of the resist layers was done in a solution of methylisobutylketone and isopropyl alcohol. Ion beam sensitivity and contrast were determined as a function of development time. It could be shown that for light ions the thickness reduction during ion exposure and the developed depth are directly related to the electronic energy density deposited in the resist.