Induced Chemical Networking of Organometallic Tin in a Cyclic Framework for Sub-10 nm Patterning and Interconnect Application

Abstract

Given the need for advanced resist materials in view of fast shrinkage of semiconductor node scaling, this work demonstrates the lithography application of an organotin-based cyclotrimeric species (Sn–CT) as a molecular resist for sub-10 nm patterning using electron beam lithography (EBL) and helium ion beam lithography (HIBL) techniques. While the resist has been successfully used for patterning ∼15 nm line/space features and ∼9 nm discrete line features at a dose of 2.5 mC/cm2 using EBL, ∼15 nm line/space features were printed on silicon at a dose of 16 μC/cm2 using HIBL. Moreover, Sn–CT has also been used for patterning complex features at a single nanometer regime such as real-scale device designs at ∼7 nm structure on silicon. A mechanistic study using X-ray photoelectron spectroscopy (XPS) revealed the formation of Sn–O–Sn and Sn–OH networks along with the loss of carbon-based group(s) upon radiation exposure, resulting in the generation of insoluble products in the exposed region, which becomes the basis of polarity switching and hence pattern development. The resist was found to have good etch resistance with respect to silicon. Moreover, Sn–CT has been explored as a good gap-filling material for silicon (Si) front-end devices and interconnects due to its low-κ dielectric (∼1.9) and high diffusion barrier properties.