Silicon nitride single‐layer x‐ray mask

In LP‐CVD process, preparation of silicon nitride film with small tensile stress and low refractive index was investigated as a function of deposition temperature and reactant gas ratio (SiH₂Cl₂/NH₃). The small stress film with low refractive index can be prepared easily by high temperature deposition. Applying the film to an x‐ray mask membrane, a new silicon nitride single‐layer x‐ray mask with a large area window (such as 50 mm in diameter) and high transparency to visible light is realized. Using this mask, a submicron resist pattern (0.5 μm line and space) can be replicated easily by Si–K x‐ray exposure system.