(40a) Nutrient-Replenished On-Wafer Crystallization of Pure-Silica-Zeolite Films
Pure-silica-zeolite thin films were investigated for use as a new low-dielectric constant (low-k) material in computer microprocessors. The pore size and pore size distribution of porous low-k materials must be carefully characterized and controlled to ensure uniform properties and to prevent complications with groove etching, pore sealing, and Cu ion migration. Tetraethylorthosilicate (TEOS) was added to a pure-silica-zeolite MEL nanoparticle suspension, and the mixture was subsequently used for preparing spin-on low-k films. Investigation into the film microstructure indicated that the addition of TEOS significantly increased the fraction of the crystalline domains, decreased the intercrystal mesopore size, and narrowed the pore size distribution. Although the addition of TEOS led to lower porosity, the crystalline zeolite domains increased, and smaller and more uniform intercrystal pores were obtained. Since crystalline zeolite materials have lower k values, replacing the non-uniform, intercrystal mesopores with zeolite and uniform mesopores offsets the lower overall porosity. This nutrient-replenished on-wafer crystallization provides an improved understanding of the film microstructure and on-wafer crystallization behavior.