Roger Y. Leung

Organosiloxane based bottom antireflective coating for 193nm lithography

A spin-on sacrificial 193 nm UV absorbing organosiloxane film was developed to facilitate ArF photoresist (PR) patterning. To improve lithographic compatibility with acrylate based photoresists, different performance additives were evaluated as photoresist adhesion promoter. The results suggested that the type and loading of the photoresist adhesion promoter had a large impact on the profile and focus latitude of the patterned photoresist features. An efficient photoresist adhesion promoter candidate was identified, which has minimum impact on other solution and film properties. This work has led to the development of DUO 193 organosiloxane based bottom anti-reflective coating. Application of this film as a blanket level bottom anti-reflective coating or as a fill material for via first trench last (VFTL) dual damascene patterning is possible. The SiO structure intrinsic to this film provides a high degree of plasma etch selectivity to the thin ArF photoresists in use today. Furthermore, an equivalent plasma etch rate between DUO 193 and the low dielectric constant SiOCH films used as the dielectric layer in the backend Cu interconnect structure is possible without compromising the photoresist etch selectivity. Equivalent etch rate is necessary for complete elimination of the “fencing” or “shell” defects found at the base of the etched trench feature located at the perimeter of the top of the via. Advanced ArF PR features of 100 nm in width (and smaller) have been routinely patterned on DUO 193 film. Via fill, plasma etch rate, wet etch rate, ArF PR patterning and shelf life data will be discussed in this presentation.