Chemically amplified resist processing with top coats for deep-ultravioletand e-beam applications

Protective top coats and top antireflective coatings (ARCs) are frequently used in conjunction with chemically amplified resists. Top coats provide re sistance to airborne contamination, and are particularly important where ch arcoal filtration is not available in the processing area. They are also us eful in environments where delay times between process steps are not precis ely controlled. Conductive top coats can be used for e-beam applications to reduce charging and image placement errors. Top ARCs are used to reduce re flections at the resist/air interface, thereby lowering the amplitude of th e swing curve. All of these materials are applied on top of the photoresist after the postapply bake. In this article we report that depending on the subsequent processing conditions, top coatings can significantly impact the Lithographic performance of the photoresist. Alterations in development ra te, optical proximity effects, resist profile, and postexposure bake latitu de have been observed as a result of processing with an additional top film . The primary mechanism responsible for these changes is an alteration of t he diffusion characteristics of the photo acid generator during the deprote ction step. (C) 1998 American Vacuum Society. [S0734-211X(98)10306-2].