Aluminum taper etching has been developed to improve dielectric step coverage. The seventy degree tapered aluminum pattern is obtained on a flat topography by erosion of a sloped resist mask and high etching anisotropy in RIE. To improve process stability and controllability, resist/a-Si(amorphous silicon)/Al structure was adopted. Amorphous silicon decreases the reflectivity to reduce pattern degradation and has lower etching rate to serve as a secondary etching mask. A simple etching model was proposed to evaluate taper etching controllability and limitation. SEM observations and TEG evaluations show a good dielectric step coverage on tapered aluminum pattern.