Etching through silicon wafer in inductively coupled plasma

Inductively coupled plasma reactor (ICP) has been used to etch holes, trenc hes and other shapes completely through 380 and 525 mu m thick silicon wafe rs. Bosch/STS process of gas flow pulsing with SF6 etch step and C4F8 sidew all passivation step was employed. Etch rate reduction due to aspect ratio dependence and pattern size and shape effects have been explored. Etch stop has been studied both on bulk and SOI wafers. Notching effect was observed for high aspect ratio features but it was absent in large, low aspect rati o features. Aluminum etch stop layer has been shown to eliminate notching.