Photo Cleaning of Si Surface after Reactive Ion Etching

Reactive ion etching (RIE) is widely used for fine pattern transfer in VLSI. However, the dry etching induces damage and contamination onto the etched surface. After SiO2 RIE on Si for contact holes with CF4-H2 gas, the Si surface is covered by thin fluorocarbon film, and lattice damage is induced in the Si substrate [1]. Furthermore, it is also well known that thin halocarbon film covers the side wall in Si deep trench, which are etched with SF6 and halocarbon mixture gas [2]. These films, damaged layer and impurity contaminated layer have been removed with a combination of O2 plasma ashing and wet processing. In this report, a new dry photo process is presented for the surface residue removal after the RIEs.