Study of barrier coats for application in immersion 193-nm lithography

We will describe our barrier coat approach for use in immersion 193 nm lithography. These barrier coats may act as either simple barriers providing protection against loss of resist components into water or in the case of one type of these formulations which have a refractive index at 193 nm which is the geometric mean between that of the resist and water provide, also top antireflective properties. Either type of barrier coat can be applied with a simple spinning process compatible with PGMEA based resin employing standard solvents such as alcohols and be removed during the usual resist development process with aqueous 0.26 N TMAH. We will discuss both imaging results with these materials on acrylate type 193 nm resists and also show some fundamental studies we have done to understand the function of the barrier coat and the role of differing spinning solvents and resins. We will show LS (55 nm) and Contact Hole (80 nm) resolved with a 193 nm resist exposed with the interferometric tool at the University of New Mexico (213 nm) with and without the use of a barrier coat.