Evaluation of charging damage caused by the pattern structures during Al etching

Aspect ratios increase as metal device design rules decrease and, in the current metal etching process, this higher aspect ratio has lead to increased electron shading (Hashimoto, 1993) which has been shown to cause electrical and physical damage (Tabara, 1996) to the device. In case of Al etching, it is very difficult to satisfy the device´s requirements due to its own characterization. In poly etching, the electron shading effect can be reduced by replacing the photoresist mask with a SiO₂ hard mask (Lee et al., 1998). This same method has been applied to Al etching and has demonstrated similar results. In this paper, we show that using an SiO₂ hard mask instead of photoresist is effective in preventing electrical damage in Al etching