Advance Low-k Dielectrics by the Sol-Gel Process

In this proposal, we plan to synthesize UV-curable, fluorinated polycarbosilane (PCS) using fluoronation and substitution reactions. Conventional polycarbosilane (PCS) has been proven to be a good replacement for spin-on glass (SOG). PCS can be converted to a highly porous silicon oxide/oxycarbide composite at relatively low process temperature by controlling heat treatment temperatures, atmospheres and the sequence. This highly porous fluorinated silicon oxide/oxycarbide composite can be expected to have much lower dielectric constant. By using polycarbosilane with different Si/C ratio to create more excess carbon and organics for burn-off, more than 50% porosity with extremely low dielectric constant (<2) cam be expected. Due to the inorganic nature of this composite, excellent mechanical strength and high temperature stability can be expected even for that with more than 50% porosity. Conventional or advance lithography (such as electrons, ions, X-ray) can be used to pattern the PCS films. No photoresists and related chemicals is needed, and no complicate etching process either. The washout PCS solutions can be recycled for further application. Therefore, this sol-gel PCS process of highly porous, fluorinated silicon oxide/oxycarbide composite films for low-k IMD applications will not only be with excellent material performance, ultra-low-cost, simple, high throughput, but also environmentally benign.