Fabrication of metal nano dot dry etching mask using block copolymer thin film

Dense and periodic arrays of Au, Cr, Ni and Al nano dots were fabricated on silicon substrate. To obtain nano size patterns, self-assembling resists were used to produce a layer of uniformly distributed parallel cylinders of PMMA in a PS matrix. The PMMA cylinders were degraded and removed by acetic acid rinsing, forming a PS mask to transfer the pattern. The patterned holes of PS template were approximately 20 nm wide, 40 nm deep, and 50 nm apart. About 100 Å-thick Au, 30 Å-thick Cr, Ni, and Al thin film was deposited by using e-beam evaporator. PS template was removed by lift-off process using N-formyldimethylamine (DMF). Arrays of metal nano dots were dry etched by using fluorine-based reactive ion etching (RIE). As a result, the nano template of PS was analyzed with field-emission scanning electron microscope (FESEM) and the sizes of Cr, Ni, Au and Al nano dots left on Si surface were measured by atomic force microscope (AFM). The sizes of metal nano dots were in the range of 17-22 nm.