ELECTRON-CYCLOTRON-RESONANCE SPUTTER REMOVAL OF SIO2 ON SILICON-WAFERS

The in situ sputter removal of oxide layers prior to subsequent deposi tions or growth is increasingly important as device sizes and hence in terlayer contact sizes shrink. Electron cyclotron resonance (ECR) plas ma sputter removal of oxides has been investigated since it offers the combination of high plasma densities and low ion energy induced subst rate damage. In this study, ECR argon discharge sputter removal of SiO 2 was investigated using a 9 and 25 cm diam discharge. The uniformity and rate of oxide removal on 3 and 6 in. silicon wafers were investiga ted with respect to pressure (0.6-2 mTorr), microwave power (200-800 W ), radio-frequency induced bias (-30 to -80 V) and downstream position (6.3-11.8 cm) of the wafer. Uniformity and rate results show good cor relation to ion density measurements and to an ambipolar plasma diffus ion model.