High precision etching of Si/SiO₂ on a high-density helicon etcher for nanoscale devices

This paper describes an evaluation of a helicon high-density plasma etch tool for etching silicon, silicon oxide and nitride in the sub 50 nm range. The objective of this evaluation was to establish etching processes for the production of fully depleted silicon-on-insulator transistors with ultrathin bodies as well as the fin and the gate for the fin field effect transistor (FinFET)-type double gate transistor. Silicon features with linewidths down to 27 nm and selectivity Si:SiO₂ in excess of 300:1 were achieved. The influence of the etch parameters, e.g., HBr:O₂ ratio, total gas flow, and bias power, on etch rates, selectivities, and profiles, have been studied extensively.