Alkali-Developable Organosilicon Positive Photoresist(OSPR)

A new alkali-developable organosilicon positive photoresist for a bi-layer resist system has been developed. Novel alkali-soluble organosilicon polymers, polysilsesquioxane, polysiloxane, and polysil-methylene, were prepared as the matrix polymers. Among these polymers, poly(p-hydroxybenzylsilsesquioxane) ( I) exhibited the highest 09RIE resistance. A composite (OSPR-1334)prepared from I and naphEho-quinone diazide becomes an alkali-developable positive photoresist which is sensitive to i - g line light. The sensitivity and the resolution of OSPR-1334 are almost the same as those of conventional novolac-based resists when aqueous tetra(2-hydroxyethyl)ammonium hydroxide is used as the developer. Also, OSPR-1334 has excellent resistance to O2RIE. The etch rate is 3.6 nm/min, while that of polyimide or novolac-based resists is 100 nm/min. Thus, OSPR-1334 is suitable for use as the top layer of a bi-layer resist system. Submicron patterns with high aspect ratio can be easily obtained with this new bi-layer resist system.