LITHOGRAPHY WITH A MASK OF BLOCK-COPOLYMER MICROSTRUCTURES

Dense, periodic arrays of holes and troughs have been fabricated in si licon, silicon nitride, and germanium. The holes are approximately 20 nanometers (nm) wide, 20 nm deep, spaced 40 nm apart, and uniformly pa tterned with 3X10(12) holes on a three inch wafer. To access this leng th scale, self-assembling resists were synthesized to produce either a layer of hexagonally ordered polyisoprene (PI) spheres or parallel cy linders of polybutadiene (PB) in a polystyrene (PS) matrix. The PI sph eres or PB cylinders were then degraded and removed with ozone to prod uce a PS mask for pattern transfer by fluorine-based reactive ion etch ing. A PS mask of spherical voids was used to fabricate a lattice of h oles and a mask of cylindrical voids was used to produce parallel trou ghs. This technique accesses a length scale difficult to produce by co nventional lithography and opens a route for the patterning of surface s via self-assembly. (C) 1998 American Vacuum Society. [S0734-211X(98) 01302-X].