High resolution patterning in chemically amplified resists: The effect of film thickness

As thin film imaging becomes an accepted means of producing high-resolution microelectronics features, a host of new challenges has emerged. A dose dependence on resist thickness has been observed and systematically measured for chemically amplified resists exposed with 75 keV electron beam radiation. The required dose to print 100 nm images increased as the thickness of the film decreased. A physicochemical explanation for this dependence was sought which included exploring thickness-induced variations in thermal characteristics of the resist film. Over the range of film thicknesses examined, 80-360 nm, these parameters were deemed unlikely contributors to this phenomenon. Ultimately the data suggests that the dose variation with thickness may correlate to differences in the population of 'chemically effective' electrons with energies in the range of 10 to 100 eV that are responsible for the sensitization of electron beam resists. © 2001 SPIE - The International Society for Optical Engineering.