Self-aligned nanoscale processing solutions via selective atomic layer deposition of oxide, nitride, and metallic films

Abstract

Nanoscale process integration demands novel nanopatterning techniques in compliance with the requirements of next generation devices. Conventionally, top-down subtractive (etch) or additive (deposition/lift-off) processes in conjunction with various lithography techniques is employed to achieve film patterning, which become increasingly challenging due to the ever-shrinking alignment requirements. To reduce the complexity burden of lithographic alignment in critical fabrication steps, self-aligned processes such as selective deposition and selective etching might provide attractive solutions. Selective atomic layer deposition (SALD) has attracted immense attention in recent years for self-aligned accurate pattern placement with sub-nanometer thickness control. During the atomic layer deposition (ALD) process, film nucleation is critically dependent on the surface chemistry of the substrate which makes it possible to achieve selective-ALD (SALD) by chemically modifying the substrate surface. Local modification of substrate surface opens up possibilities to achieve lateral control over film growth in addition to robust thickness control during ALD process. SALD offers numerous advantages in nanoscale device fabrication such as reduction of the lithography steps required, elimination of complicated etching processes, and minimization of expensive reagent use. In this work, we review our recent SALD efforts using various inhibition layers resulting in promising self-aligned deposition solutions for metaloxide, metal, and III-nitride thin films. We report a comprehensive investigation to select the most compatible inhibition layer among poly(methylmethacrylate) (PMMA), polyvinylpyrrolidone (PVP), and ICP-polymerized fluorocarbon layers for SALD of metal-oxide and metallic thin films. In addition, single-layer and multi-layered graphene layers are explored as plasma-compatible inhibition layers for selective deposition of III-nitride materials. Extensive materials characterization efforts are carried out to correlate the ALD recipe parameters with the selective deposition performance. The materials and deposition recipes developed in this work overcome various challenges associated with previous methods of SALD and provide alternative routes towards nano-patterning particularly for the sub-10 nm CMOS technology nodes as well as for sensors, photovoltaics, materials for energy storage, catalysis, etc.