Analysis of the sidewall films formed during Si trench etching with photoresist mask in Cl-2/HBr-based plasma

The sidewall passivation films produced during Si trench etching with photo resist masks were examined in two etching systems, helicon and inductively coupled plasma (ICP). The trench profiles obtained from the ICP system were more tapered with thicker sidewall films compared to those from the helico n system. The trench etch profiles with Cl-2/HBr/O-2 plasma in the ICP syst em appeared to be double-sloped. X-ray photoelectron spectroscopy (XPS) ana lysis indicated that N-2 addition to Cl-2/HBr/O-2 plasma induced the format ion of Si-N bonds in the sidewall films, in addition to the Si-O and Si-Br bonds observed with Cl-2/HBr/O-2. The sidewall films formed in Cl-2/HBr/O-2 plasma showed higher oxygen intensities and chemical binding energies comp ared to those formed in Cl-2/HBr/N-2/O-2 plasma. (C) 2000 Elsevier Science B.V. All rights reserved.