The micro-and nano-fabrication researches for various polymeric materials such as perfluorinated polymers (PTFE, RX-PTFE, FEP, PFA), biodegradable polymers (PLLA), and electron beam resists (ZEP520 A, ZEP7000) were carried out by focused ion beam (FIB) direct mask less etching and electron beam induced reactions.The nano-scale fabrications of polymeric materials were succeeded by FIB direct mask-less etching.The etching rates for perfluorinated polymers, biodegradable polymer show the 5~6× 1016, 1~2× 10-18, μm/(ions cm2), respectively.It was found that the etching rates for perfluorinated polymers were about two ~ three orders higher than those for biodegradable polymer.For the nano-fabrication, ZEP resists were applied for the FIB and electron beam processes.We have found that the resists show very interesting behavior for the high dose irradiation range.The resists show positive-tone (scission type) in the low dose exposure, but at the high dose range the resists show negative-tone (crosslinking type).We have succeeded the nano-fabrication by using this phenomenon.In the conference we will show the mechanism of this interesting reaction and will show the demonstrative works for nano-fabrications.