Silylation after wet development

Phenolic resists can be silylated also after wet development with aqueous base [463,464]. In the silicon-added bilayer resist (SABRE) process (Fig. 165), a di-azoquinone/novolac resist is coated on a top of a planarizing layer and imaged in the conventional fashion by UV exposure and aqueous base development [463]. The phenolic polymer remaining in the unexposed area after development is silylated in a gas phase or in solution to provide 02 RIE resistance for dry etching of the underlying layer [463,464]. This bilayer scheme takes advantage of high contrast aqueous base development to produce square resist profiles, which are then converted to a well-defined Si mask by silylation for 02 RIE pattern transfer. Thus, a poor silylation contrast sometimes encountered 

The biasing technique by silylation to print features smaller than the nominal size was first reported from Siemens in 1990 [466]. In the CARL (Chemical Amplification of Resist Lines) process an imaging layer containing anhydride is silylated in solution with bis(aminosiloxane) either after exposure (Top-CARL) 

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