Fabrication of nanometer-order dot patterns by lift-off using a fullerene-incorporated bilayer resist system

We propose a new bilayer resist system consisting of a fullerene-incorporat ed positive-type electron beam resist, ZEP520, top layer and a pure ZEP bot tom layer. In this system, the difference in resist sensitivity between the top and bottom layers can be readily optimized by changing the fullerene c ontent of the top layer so as to create an overhang resist pattern favorabl e for lift-off, A bilayer system composed of 20 wt% fullerene-incorporated ZEP and pure ZEP produces suitable overhang patterns with a sensitivity of similar to 60 mu C/cm(2). The applicability of the system has been verified through the successful fabrication of a highly-ordered array of self-organ ized similar to 50-nm InGaAs/AlGaAs boxlike structures and a SIC nanoprinti ng mold with a 150-nm-pitch dot array.