Advanced single precursor based pSiCOH k = 2.4 for ULSI interconnects

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A single precursor, octamethylcyclotetrasiloxane (OMCTS), was used to develop a pSiCOH interconnect dielectric with an ultralow dielectric constant k = 2.4. With no added porogen, the advanced pSiCOH dielectric has low pore size and low pore interconnectivity. The new OEx2.4 dielectric has a high carbon content with a significant fraction in the form of Si-CH2-Si bridging bond resulting in a film with relatively high modulus and increased resistance to process induced damage. The new OEx2.4 film shows significant improvement in device reliability (time dependent dielectric breakdown) over the reference k 2.55 and other k 2.4 dielectrics. This dielectric not only addresses the integration challenges but also provides capacitance benefit by retaining an overall lower integrated k value over the reference films. The results discussed in this paper indicate that the single-precursor OMCTS-based advanced pSiCOH, OEX2.4 dielectric is a strong candidate for sub-10 nm Cu/low k interconnects.