Inner Trench Type Tungsten Nano Dot Arrays Patterned by Using Diblock Copolymer Templates and Selective Ion Etching

Dense and periodic arrays of holes and nano dot were fabricated in silicon oxide and silicon. The holes were approximately 25 nanometers(nm) wide, 35 nm deep and 60nm apart. To access this length scale, self-assembling resists were used to produce a layer of hexagonally ordered parallel cylinders of polymethylmethacrylate(PMMA) in polystyrene(PS) matrix. The PMMA cylinders were deraded and removed with acetic acid rinse to produce a PS mask for pattern transfer. The silicon oxide was removed by fluorine-based reactive ion etching(RIE). Selective tungsten deposition was accomplished in nanoscale trench by using a low pressure chemical vapor deposition(LPCVD) method. Tungsten nano dot and trenched silicon size were 26nm and 30nm respectively.