Enhancement or reduction of catalytic dissolution reaction in chemically amplified resists by substrate contaminants

Chemical interaction of resist and substrate at the interface, which modifi es the dissolution reaction, has degraded sidewall profile of resist featur es. Depending on the nature of the residue on the substrate, the "bottom pi nching" (BP) effect and footing are observed, especially for chemically amp lified (CA) resists, The BP effect is observed for CA resist on top of orga nic bottom antireflection coating (BARC), The BP effect is attributed to th e acid generated from the underlying organic BARC, With optimization on sof tbake temperature of BARC, the BP effect is eliminated. On a silicon nitrid e surface, new chemical information has been obtained which explains "footi ng" and BP effects in CA resists. X-ray photoelectron spectroscopy (XPS) me asurements indicate that the residual alkaline molecules on the nitride sur face play a major role in the formation of footing. It appears that the org anic contaminants are not responsible for footing, Less severe footing is o bserved if the nitride surface is plasma-deposited with a thin oxide cap, w hich suppresses the surface basicity, However, extended plasma deposition c auses resist BP, This is ascribed to the surface acidity of a newly formed oxide cap, which enhances the CA resist development process. Results show t hat the N (1 s) peak, after extended plasma treatment, has shifted to a hig her binding state, which suggests that the nitride surface becomes acidic, causing BP.