Ultralow-k nanoporous organosilicate dielectric films imprinted with dendritic spheres

Integrated circuits that have improved functionality and speed in a smaller package and that consume less power are desired by the microelectronics industry as well as by end users, to increase device performance and reduce costs^1-4. The fabrication of high-performance integrated circuits requires the availability of materials with low or ultralow dielectric constant (low-k: k ≤ 2.5; ultralow-k: k ≤ 2.0) because such dielectrics not only lower line-to-line noise in interconnect conductors, but also minimize power dissipation by reducing the capacitance between the interconnects^1-4. Here we describe the preparation of low- and ultralow-k nanoporous organosilicate dielectrics from blends of polymethylsilsesquioxane (PMSSQ) precursor with globular ethyl acrylate-terminated polypropylenimine dendrimers, which act as porogens. These dendrimers are found to mix well with the PMSSQ precursor and after their sacrificial thermal decompositions result in closed, spherical pores of <2.0 nm radius with a very narrow distribution even at high loading. This pore size and distribution are the smallest and the narrowest respectively ever achieved in porous spin-on dielectrics. The method therefore successfully delivers low- and ultralow-k PMSSQ dielectric films that should prove very useful in advanced integrated circuits.