FOCUSED ION-BEAM METROLOGY

The measurement of resist image size using a finely focused ion beam ( FIB) is described. Comparisons of FIB and scanning electron microscope (SEM) measurements of resist features are presented. The short penetr ation range of an ion relative to an electron is shown to offer fundam ental advantages for critical dimension metrology. Ion beams can induc e less dimensional change (damage) than SEMs during the measurement pr ocess, potentially yielding improved measurement precision. Resist cro ss sectioning using FIB is demonstrated, and the factors contributing to quality of the cross section are presented. An H2O gas assisted etc hing process for polymer resists has been developed and is shown to si gnificantly improve the quality of resist cross sections. (C) 1995 Ame rican Vacuum Society.