An inorganic resist technology and its applications to LSI fabrication processes

An Ag/Se-Ge inorganic resist technology is applied to photolithographic processes in LSI fabrication. This paper describes exposure latitude, RIE characteristics, resist fabrication and exposure throughputs, pattern alignment, defocus tolerances and fabrication yields of Al interconnection.Lateral Ag diffusion does not effectively improve the exposure tolerance. The technology exhibits good compatibility with other equipment and technologies, offering satisfactory throughput. Excellent accuracy in pattern alignment is obtained owing to dry-deposition fabrication and the suitable optical properties of the Se-Ge inorganic film, which result in regulated and distinct alignment signals. Defocus tolerance in the resist is larger than that of polymer resist by 2 ∽ 3 μm in the submicron pattern. Al interconnections using this resist demonstrate a short-circuit failure rate of less than 1% and small variation in linewidth having a standard deviation of σ_w = 0.08 μm.In practical processes, the significant advantages of this resist are its bilayer resist structure (doped Ag-Se-Ge and underlying Se-Ge) and its dry deposition, very thin, favorable optical characteristics.