Progress in self-developing metal fluoride resists

Thin films of metal fluorides such as AlF3, FeF2, CrF2, CsF, LaF3, BaF2, and SrF2 have been used as electron beam sensitive resists. When exposed in an ultrahigh vacuum system by a high intensity electron beam at line doses of 0.5 to 400 μC/cm at 100 keV on a thin membrane substrate, the films act as positive resists. At line doses of typically an order of magnitude less than in the case of the positive resist mode, the films also act as negative resists requiring the use of an appropriate developer. The exposure properties for these metal fluoride resists are discussed along with their film properties, sensitivity, and etching characteristics.