CHARACTERIZATION OF SILICON DIOXIDE AND PHOSPHOSILICATE GLASS DEPOSITED FILMS

Silicate glasses, both undoped and lightly doped with phosphorus, prep ared by a low pressure plasma enhanced chemical vapor deposition (PECV D) system using tetraethylorthosilicate or silane as silicon sources a nd atmospheric pressure chemical vapor deposition technique using sila ne, were evaluated. The three analyzed phosphosilicate films were nomi nally 4.0 wt % doped. All the samples were deposited in the temperatur e range of 350-420-degrees-C. Their main properties such as refractive index, density, wet etch rate, stress, step coverage, moisture resist ance, and infrared absorption are reported. Infrared absorption measur ements were performed on both as-deposited and annealed films (430-deg rees-C for 15 min in N2) to investigate the presence of water and Si-O H groups, as well as P=O and Si-O bond interactions. The P-doped films were tested as final passivation layers on 1 Mbit erasable programmab le read only memory devices mounted in ceramic packages. Similar elect rical results have been obtained with three different phosphosilicate glass films. However, the most reliable results after assembly and pac kaging were obtained for films deposited by PECVD technique using tetr aethylorthosilicate as the source of silicon in the films.