A Study on the Silicon surface and near-surface contamination by $CHF_3$/$C_2$$F_6$ RIE and its removal with thermal treatment and $O_2$ plasma exposure

$CHF_3$/$C_2$$F_6$ 반응성이온 건식식각에 의한 실리콘 표면의 오염 및 제거에 관한 연구

Thermal behavior and $O_{2}$ plasma effects on residue and penetrated impurities formed by reactive ion etching (RIE) in CHF$_{3}$/C$_{2}$F$_{6}$ have been investigated using X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) techniques. Decomposition of polymer residue film begins between 200-300.deg. C, and above 400.deg. C carbon compound as graphite mainly forms by in-situ resistive heating. It reveals that thermal decomposition of residue can be completed by rapid thermal anneal above 800.deg. C under nitrogen atmosphere and out-diffusion of penetrated impurities is observed. The residue layer has been removed with $O_{2}$ plasma exposure of etched silicon and its chemical bonding states have been changed into F-O, C-O etc.. And $O_{2}$ plasma exposure results in the decrease of penetrated impurities.