Orientation of Block Copolymer Resists on Interlayer Dielectrics with Tunable Surface Energy

Abstract

It has been well established that one of most important factors to control the orientation of microdomains in block copolymer (BCP) films is the wetting behavior of a BCP at the interface (or on a substrate). From this perspective, we studied the wetting behavior of P(S-b-MMA) thin films on organosilicate (OS) interlayer dielectric layers (ILDs), which were employed as the target substrates for patterning by BCP lithography. We controlled the surface energy of OS substrates by varying the cure temperature of OS substrates ranging from 200 to 400 °C. As the cure temperature was increased, the wetting behavior of a P(S-b-MMA) film on the OS substrate changed from the asymmetric to the symmetric wetting, as confirmed by AFM, which, in turn, allowed us to find the optimal cure temperature for neutral wetting behavior. As a result, we obtained perpendicularly oriented BCP microdomains on the OS substrate cured at 360 °C without further surface modification. Finally, we were able to transfer sub-25 nm BCP patterns directly onto the neutral ILD layers through reactive ion etching. The process approach taken here clearly demonstrates that the process involved in BCP lithography could be simplified by eliminating the additional surface modification step on a target substrate.