International DSA symposium edition:2 location:Grenoble date:11-13 october 2016
Directed self-assembly (DSA) of block-copolymers (BCP) is considered as a complementary patterning technique to Extreme ultra violet (EUV) lithography at dimensions below 20nm half-pitch. Critical challenges on DSA hole shrink and multiplication include critical dimension uniformity (CDU) and placement errors.
In this study we will demonstrate the impact of the conventional lithography step and variations in the template shape on the pattern placement and CDU of the DSA holes. We will focus on the formation of singlets (i.e. contact hole shrink), and doublets. Conventional lithography techniques (ArF or EUV) are used to create a pre-pattern that guides the phase separation process. After surface modification, a polystyrene-b-methyl methacrylate (PS-b-PMMA) is deposited in the templates and annealed at elevated temperature. Annealing results in a phase separation of the polymer into cylindrical patterns (Figure 1). After removing the minority block (in this case PMMA), this pattern is transferred in an underlying SiN layer for pattern placement and CDU characterization. The higher resolution of EUV enables template shape control. This is expected to give a pattern placement improvement. In addition, the templates can be pre-shaped to more commensurate shapes than ellipses (e.g. in peanuts), which is expected to further reduce placement errors.