ASHING RESIDUES ON TIN ANTIREFLECTIVE COATING LAYERS

Residues appearing on the surface of the TIN antireflective coating (A RC) layer after a resist ashing process were investigated by transmiss ion electron microscope and field emission Auger electron spectroscopy . These residues tend to appear linearly in the center of Al lines cov ered with the TiN ARC layer, and are generally called the ''backbone.' ' We found that a triangular product mainly composed of Al atoms appea rs in the center of the resist surface in the final stage of the ashin g process and that a thin layer, about 10 nm thick, including Ti atoms , is formed to cover the triangular product and the resist surface. Du e to the small solubility of the thin layer including Ti atoms to the alkaline stripper, the triangular product under the thin layer remains as a backbone residue. We demonstrate that the formation of the backb one depends on the distribution of Al and Ti atoms in the sidewall pol ymer. (C) 1996 American Vacuum Society.