Damaged silicon contact layer removal using atomic layer etching for deep-nanoscale semiconductor devices

Abstract

Silicon atomic layer etching (ALET) using Cl2 is applied to remove the damaged layer on a 30 nm contact silicon surface formed by high-energy reactive ions during high aspect ratio contact etching, and its effects on the damage removal characteristics are investigated. Compared to a conventional damage removal method, such as the low-power CF4 plasma treatment technique, ALET produces less secondary damage to the substrate and gives exact etch depth control and extremely high etch selectivity to the contact SiO2 insulating pattern mold. When ALET is applied after a conventional damage removal technique, the sheet resistance of the damaged contact silicon surface is improved to a level close to that of a clean silicon surface, while exact atomic-scale depth control is maintained without changes in the pattern mold profile.