Process Development of Radical Based Dry Clean for Advanced 3D NAND Fabrication

Abstract

As semiconductor device scaling marching toward sub-5 nm logic, 128+ layers 3D NAND, and 1x nm DRAM, wafer surface cleaning and residue removal in nanoscale, high aspect ratio (AR) structures become increasingly critical. Dry plasma clean technologies based on reactive radicals are developed as alternatives for traditional wet clean applications with significant advantages in process extendibility and environmental friendliness. Here we report a novel inductively coupled remote plasma design for radical based dry clean applications. A high gas dissociation efficiency and a high radical density were achieved with controllable radical component, energy, and reactivity. Two applications, including residue clean in high aspect ratio channel holes and contact holes (AR ~ 50:1), are tailored for 3D NAND manufacturing. Complete removal of oxide and polymeric residues, smooth and pristine Si surface, and considerably reduce contact resistance can be simultaneously achieved with the customized clean chemistries. Applications in mass production have been accomplished.