TELECENTRIC NUV-DUV IRRADIATOR FOR OUT-OF-CONTACT EXPOSURE OF LARGE SUBSTRATES

摘要

A condenser lens system is provided for forming an effective circular source of NUV-DUV radiation which is the telecentric stop of the system and is characterized by a short focal length and higher marginal irradiance to compensate for marginal cosine losses. The system utilizes a long arc medium/low pressure mercury lamp which is surrounded by a large paraboloidal reflector and is mounted below the focal point of the reflector to generate a converging radiation beam directed to the condenser lens system. The system then projects the effective circular source of NUV-DUV radiation to a lens system comprising two plano convex lenses to convert the effective circular source into a collimated beam for out-of-contact printing of large substrates. The highly collimated and spatially coherent beam can be used to irradiate a telecentric objective for projection exposure on wafer steppers or flood exposure systems.