High aspect ratio hydrogenation-assisted lateral etching of (1 0 0) silicon substrates

In this paper a hydrogenation-assisted high aspect ratio lateral etching of (1 0 0)-oriented Si wafers is presented. After desired patterning, vertical etching is used to etch the silicon substrate to achieve appropriate heights. A plasma hydrogenation step is applied to create defects at a desired depth. The created damage is finally dissolved in Secco etchant, releasing an ultrathin silicon layer. The effect of hydrogen ions in the formation of defects at a desired depth has been investigated. Process variables such as hydrogenation temperature, time and plasma power were examined to observe their influence on lateral etching. In addition to scanning electron microscopy, EDX analysis has been performed to observe the presence of a silicon layer underneath chromium which served as the protection layer.