High density fin formation is one of the most critical processes in the FinFET device fabrication flow. Given that a typical device is composed of an ensemble of fins, each fin must be nearly identical to avoid performance degradation arising from geometric variation. Thus, techniques for fin patterning must demonstrate the ability to form fins with a high degree of structural precision.
IBM researchers will discuss the use of directed self-assembly using block copolymers (BCP) and 193nm immersion (193i) lithography as a suitable way to make the fins of FinFETs for beyond the 10 nm node. Essentially, a topographic template pattern was created on a chemically neutral surface. Confinement of the BCP between the sidewalls of the template provides an ordering force that drives the pattern into registry with the surface topography. Electrical data produced from fins with a 29-nm pitch patterned with this approach showed good uniformity, with no signs of gross variation in critical dimensions.
(Paper#32.1, “Electrical Characterization of FinFET with Fins Formed by Directed Self Assembly at 29 nm Fin Pitch Using a Self-Aligned Fin Customization Scheme,” H. Tsai et al, IBM)