Atomic force microscopy study on the dissolution processes of chemically amplified resists for KrF excimer laser lithography

The surface images of chemically amplified KrF excimer laser resists after development were measured by atomic force microscopy (AFM). From the AFM im ages at various exposure doses, the dissolution behavior of the polyvinylph enol-based KrF resists differed from that of novolak-diazonaphthoquinone (D NQ) resists. An explanation for the different dissolution behavior has been proposed by considering the difference in the mechanisms of formation of s oluble sites between chemically amplified resists and novolak-DNQ resists ( non-chemically amplified resists). In addition, AFM topographic images of t he resists dissolving layer by layer were observed clearly in the resist sp in-coated on a Si wafer. The step heights of the layered structure observed by AFM are in good agreement with the computed value of the distance betwe en two adjacent nodes of standing waves formed by KrF excimer laser exposur e. The layered dissolution may be applied to the processing of thin polymer films.