Area selective PECVD on metal oxide resist

This paper explores the use of a selective deposition process to selectively modify the thickness and/or the roughness of a metal-oxide extreme ultraviolet resist. It is shown that by controlling the time of a plasma enhanced chemical vapor deposition process, a selective deposition of 6 nm can be observed on the metal-oxide resist surfaces while no deposition is observed on the spin on glass (SOG) surfaces. Based on both material and plasma characterizations, the origin of selectivity is discussed. It is shown that for short process times, there is a deposition regime on the metal-oxide resist while a plasma/surface interaction regime occurs on the SOG material with a competitive effect between deposition and etch. Fluorine diffusion inside the metal-oxide resist prevents fluorine atoms from saturating the surface of the growing film. Finally, in addition to the selective deposition, a 50% roughness reduction of the metal-oxide surface is demonstrated.