Nanometer-scale pattern registration and alignment by directed diblock copolymer self-assembly

We describe a fabrication method that combines the alignment capabilities of optical lithography with the sublithographic dimensions achievable using self-assembled diblock copolymer films. We use surface topography to direct the assembly of in-plane cylindrical copolymer domains so as to subdivide larger patterns defined using optical lithography, in the process registering the location of each 20-nm polymer domain to the lithographic pattern. Our approach provides an application for self-assembly in the fabrication of complex microelectronic circuits entailing alignment of multiple patterned layers. We detail the influence of such process parameters as lithographic pattern dimensions and density, copolymer film thickness, and anneal time on the quality of the resulting nanometer-scale-domain registration.