Combination of Thermal Scanning Probe Lithography and Directed Self-Assembly of Block Copolymers

The fabrication of semiconductor quantum devices necessitates sub-20 nm features and high-density patterning, often exceeding the capabilities of current state-of-the-art lithographic techniques. To address this challenge, in this work, the combination of top-down thermal scanning probe lithography (t-SPL) and pattern transfer with bottom-up directed self-assembly (DSA) of block copolymers (BCP) is presented as a new lithography process suitable for quantum device fabrication. Nanohole arrays of varying shapes and sizes were patterned into SiO2 using a combination of t-SPL and reactive ion etching (RIE) for 5x depth-amplified pattern transfer. These arrays served as guiding patterns, inducing three distinct orderings of block copolymers (BCP): pattern hole shrink (PHS), pattern hole doubling (PHD), and high-pitched PHD. SEM images have been analyzed by image processing to determine guiding pattern/DSA pattern placement accuracy. It has been determined that the guiding pattern/DSA offset is sub-10 nm, so it does not hinder the pattern placement control lent by t-SPL. This combined t-SPL/DSA lithography process, capable of creating complex, high-resolution patterns with precise placement, holds a significant promise for fabricating advanced quantum devices.