Modified PMMA-polymers for masks in ion beam lithography

Ion sensitive polymers are modified for submicron structure technology application. Di-butyl maleate is used as an impurity in PMMA to modify the plasticity and continuity of the resist films. Experiments performed using light ions with energies of 30 to 50 keV show the improved contrast, sensitivity, and geometric stability of the new material. With the modification ratio increase up to 20% the sensitivity increases by about 25% and the contrast increases to 30 to 50% (dependent on the ion energy). When the ion range exceeds the resist thickness, secondary effects are visible. (author)