SURVEY OF PROCESSING AFFECTS ON SUBSTRATE COMPATIBILITY OF CHEMICALLY AMPLIFIED RESISTS

Current efforts to reduce deep ultraviolet (DUV) photoresist profile abnormalities on silicon nitride (Si3N4) and titanium nitride (TiN) are summarized. The nitridic surface of the films is investigated to understand the mechanism that is responsible for severe photoresist footing at the photoresist/substrate interface. Resist footing was compared for various changes in resist processing and substrate pretreatments. For the oxide/Si3N4 stack the footing problem was studied using resists processed with different post exp osure bake temperatures, with substrates that had been pretreated and with different thicknesses of an organic barrier coat. ESCA analysis was used to examine the surface of the oxide/Si3N4 substrate for contaminants. For TiN substrates, the DUV resist footing problem was studied using different photoresists and TiN film of various stoickhiometries. Multiple characterization techniques were used to examine the TiN film including Auger electron spectroscopy, atomic force microscopy, Rutherford backscattering and reflectivity measurements. Considering these results, and information previously published, it is concluded that there exists detrimental surface and interface states on the TiN substrate that are principally responsible for the footing.