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Processing and characterization of ultralow-dielectric constant organosilicate

01 November 2001

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A class of nanoporous organosilicate has been developed that can reach an ultralow-dielectric constant (kless than or equal to2). In this approach a series of triblock polymers, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO), are used as sacrificial materials in silicon based spin-on matrices, poly (methylsilsesquioxane) (MSQ) to generate pores when heated above 400 degreesC. To improve the electrical and mechanical properties, different parameters, such as temperatures, heating rates, polymer molecular weights, copolymer compositions, and the molecular weight of MSQ prepolymers, were studied. Heating temperatures and ramping rates have no large effect on dielectric constants and dielectric breakdown strength. However, at a higher temperature, 500 degreesC, the mechanical properties are found stronger than those from 400 degreesC. A higher molecular weight of MSQ prepolymer will also lead to higher mechanical properties of the final porous MSQ, while no temperature effect is observed. Block copolymers with different molecular weights and compositions give similar dielectric constants depending on the polymer loading in MSQ and no substantial change in the dielectric strength of the films with different compositions. (C) 2001 American Vacuum Society.